Serial printing device
United States Patent 1 1 Giolitti et a1.  
 1 1 SERIAL PRINTING DEVICE [75] Inventors: Nicolo Giolitti; Sergio Garberi;  
 Lorenzo Bertino, all of lvrea. Italy [73] Assignee: lng. C. Olivetti &amp; Co., S.p.A., Torin, Italy [22] Filed: Jan. 15. 1973 [21] Appl. No.: 323,674  
 197/49. 71; 178/34; 101/93 C; 235/61 R, 61 PE. 61.6 R, 61.9 R. 59 T [56] References Cited UNITED STATES PATENTS 2.774.816 12/1956 Yost 197/49 X 3.247.941 4/1966 Beattic et a1 197/18 X 3.352.398 11/1967 C&#39;ruteher et a1..... 178/34 X 3.493.091 2 1970 Kapp 197 55 X 3.605.977 9/1971 Janz et al.. 197/55 X 3.608.692 9/1971 Henry 197/55 3.738.471 6/1973 Van der Werff et a1. 197/52 3.739.344 6/1973 Serracchioli et a1 197/49 X [451 Apr. 8, 1975 Primary E.\&#39;aminerEdgar S. Burr Assistant Examiner-RT. Rader Attorney. Agent. or Firm-1. J. Schaefer [57] ABSTRACT A serial printing device for an electronic calculating machine comprises a cylindrical type head movable with respect to the paper support and adapted to print numerical amounts and signs indicating the nature of the amounts in predetermined character positions of a row. The type head carries a plurality of digits and symbols disposed in two separate zones which are prearrangeable for printing by a shift mechanism connected to the type head by means of a differential. A character selector. connected to the type head through the differential is operable commonly for said digits and for said symbols. to select for printing a particular character in the zone of said two zones prearranged by said shift mechanism. The selector including a control unit. a plurality of eleetromagnetically actuated setting members and a rotating drum cooperating with said members as to be variably shifted. Programming means. responsive to the positions of the head with respect to the paper support control said shift mechanism for causing the type head to prearrange for printing. in each of said predetermined character positions of the row. the corresponding zone of numeric or symbolic characters.  
 25 Claims, 12 Drawing Figures ii. 232 24 159 j 29 ,zaeh&#39; SERIAL PRINTING DEVICE BACKGROUND OF THE INVENTION The present invention relates to a serial priming device suitable for use with a calculator or computer and which is adapted to print both amounts and characters or symbols indicating the nature of the amounts.  
  Serial printing devices for calculating machines are known. One known device is adapted to print the relevant operational symbols at the side of an amount and comprises a type drum arranged behind the sheet of paper. This drum carries as many vertical lines or files of types as there are printing positions in a printing line. One or two of these vertical lines or files disposed at the side of the amount carry operational symbols. while the remaining vertical lines carry the digits and the algebraic signs. The type drum is continuously rotatable and the characters are printed serially on the fly by a hammer arranged in front of the sheet of paper and which moves transversely of the drum. A device of this type is generally very fast. but has a rather complex electronic controller and may produce ragged or indistinct printed characters.  
  Also known are printing devices employing a type head comprising a group of symbolic or alphabetic characters and a group of numeric characters. These characters can be selected one at a time. each by a combination of code signals which is associated with it. The selection devices for printing devices of this kind require a high decoding capacity and have a rather lim ited speed because of the large number of movements necessary at each printing cycle for selecting all the characters carried by the head.  
  Printing devices are moreover known in which the characters are disposed in two separate zones prearrangeable for printing by a shift mechanism. In these devices. when they are commanded by an electronic controller. the shift mechanism is actuated by a combination of coded signals supplied by the controller. In the event of abnormalities of the electronic part during the operation of the device. the zone selected in the last transport operation remains prearranged for printing. A following printing cycle could therefore lead to the printing of a character in a zone different from that expected. which would therefore be wrong. Complex monitoring devices therefore become necessary for preventing this eventuality and ensuring return of the device to a predetermined inoperative position.  
 SUMMARY OF THE INVENTION The object of this invention is to create a serial printing device which is fast and very reliable and has a shift mechanism which is actuated as a function of the mutual position ofthe symbols with respect to the digits in a printing line.  
  According to the present invention. there is provided a serial printing device comprising a type head adapted to print numerical amounts and symbols indicating the nature of those amounts in predetermined character positions. the type head having digits and symbols disposed in two separate zones. a shift mechanism operable on the type head to prearrange either of the said zones for printing. a character selector operable commonly for the digits and for the symbols to select for printing a particular character in the zone prearranged by the transport mechanism. and programming means arranged so to control the shift mechanism as to cause this mechanism to prearrange in each of the predetermined charactcr positions a particular one of the two zones for printing.  
 BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of the invention is presented by way of example in the following description and shown in the the accompanying drawings. in which:  
  FIG. I is a partial exploded rear perspective view of the printing device embodying the invention;  
  FIG. 2 is another partial exploded rear perspective view of the device;  
  FIG. 3 is a further partial exploded rear perspective view of the device;  
  FIG. 4 is a rear perspective view of a detail of FIG. I.  
 FIG. 5 is a side view of a detail of FIG. 3;  
  FIG. 6 is a working diagram of a number of details of the device;  
  FIG. 7 is a working diagram of a number of details of FIG. I;  
  FIG. 8 is a working diagram of a number of details of FIG. 3;  
  FIG. 9 is a development in plan view of a detail of FIG. 3;  
  FIG. I0 is a development in plan view of another detail of FIG. 3;  
  FIG. I] is a diagrammatic plan view of a detail of FIG. I;  
  FIG. I2 is a block diagram of the electronic controller of the device.  
 GENERAL DESCRIPTION OF A PREFERRED EMBODIMENT The device comprises a cylindrical printing head 4| (FIG. I) mounted to rotate about a vertical axis on a carriage 22 which is in turn slidable parallel to a platen 21. A cyclically acting mechanism shifts the carriage by character-spacing steps and tilts it in each cycle to cause the selected type face to strike the platen. unless such action is excluded by a space character. Nonnumerical symbols are printed in the first two letter positions and numeric characters. also referred to as digits. of a numerical amount are printed in the remaining letter positions. This distinction between symbols and digits is preserved throughout the remaining description. with the understanding that digits&#34; include the decimal point and minus sign. Characters comprise both the symbols and the digits.  
  The symbols and digits are distributed in two rows around the printing head. The symbols lie in six columns occupying half the periphery of the head (giving a total of 12 symbols) and the 12 digits lie in six columns occupying the other half of the periphery.  
  Before the first symbol is selected a transport clutch 85 rotates the head through a differential 172 to centre the symbol sector with respect to the printing point; Le. a position half-way between the third and fourth symbol columns is aligned with the printing point. The head is moreover vertically positioned so that the printing point lies half-way between the said two rows. From the preliminary symbol position thus established it is necessary to adjust the head both vertically and rotationally to select the required digit.  
  After the second symbol has been selected and printed the transport clutch 85 rotates the head through a further l80 to establish the preliminary digit position in which the digit sector is now centered.  
  Symbol and digit selection take place in exactly the same way. the only difference being whether such selection is effected from the preliminary symbol position or the preliminary digit position. Row selection is determined by an electro-magnet 207 (FIG. 3) which determines whether a projection 299 or a projection 213 engages a cam edge of an axially slidable drum 237 which rotates once for each printing cycle; this determines whether the drum moves to the right or to the left and such motion is converted to up or down motion of the printing head by a linkage shown in FIG. I and comprising bell-crank 24I, connecting rod 243, lever arm 244, tilting bar 246, slider 245 and a tongue 251 on the slider and engaging in a groove of the printing head. The up or down movement of the head aligns the lower or upper row of characters with the printing point.  
  Column selection involves rotation of the head by /2. l or 2% times the column pitch either to the right or to the left and this rotation is provided by left or right motion of another drum I93 (FIG. 3) which rotates a toothed sector I91 (FIG. I) which in turn rotates the planet wheel 173 of the differential 172. The output shaft I59 of the differential carries an elongated pinion I8l which meshes with a gear 182 on the carriage. This gear also meshes with a ring gear 184 on the printing head to rotate the same.  
  The sliding motion of the drum I93 is controlled firstly by an electromagnet 205 (FIG. 3) which determines whether a projection 277 or a projection 211 en&#39; gages an inclined edge 273 or 272 on the drum to impart to the drum an initial movement to the left or the right. The sliding motion is further controlled by three electromagnets 206 controlling individual projections 212 cooperating with further inclined edges on raised parts 26!. 262 and 263 of the drum. The three projections 2I2 give rise to movements of A. 1 /2 and 2% times the column pitch respectively in whichever direc tion has been established by the said initial movement of the drum.  
  The printing cycles are controlled by a programming means including the transport clutch 85 and a selection clutch 58. Initially the transport clutch 85 engages and rotates a gear I58 forming the input to the differential 172, thereby to rotate the printing head to the preliminary symbol position. whereupon the clutch 85 automatically disengages. During its initial rotation, the clutch 85 prearranges the engagement of the clutch 58 which then drives the selection shaft 196 carrying the drums 237 and 193 and also a shaft 29 which controls the printing action and the character-feeding of the carriage. Both these shafts rotate four times for each revolution of the output gear 56 of the clutch 58. During the second quarter rotation of the gear 56, a cam 77 carried thereby prearranges a second engagement of the transport clutch 85, which accordingly rotates through a further l80 after the second symbol has been printed to establish the preliminary digit position.  
  There now follows a full, independent, description firstly of the construction of the device and then of its operation.  
 DETAILED CONSTRUCTION The printing device comprises a transversely fixed platen or paper cylinder 21 (FIG. I) and a type carriage movable parallel to the platen 21. The carriage 22 is constituted by a sleeve 23 slidable on a shaft 24 fixed in the side pieces 25 and 26 of the device. The sleeve 23 forms one piece with a check element 27 which is adapted to slide in an annular groove of a sleeve 28. The second sleeve is angularly fixed and transversely slidable on a slotted shaft 29 which can turn between the two side pieces and 26. The sleeve 28 is moreover provided with a thread 30 which is adapted to mesh with a rack 31. The rack 31 is arranged parallel to the platen 2I, extends over the entire length thereof and is fixed by means of two arms 32 and 33 to a shaft 34 turning in the two side pieces 25 and 26.  
  The printing device comprises a support plate 38 which is substantially horizontal and integral with a pin 183. This pin is provided with a prismatic portion engaging in a slot 35 in the cheek element 27, to which it is fixed by means of a nut 36 and a threaded portion 37 of the pin 183. The plate 38 supports a substantially vertical shaft 39 on which a cylindrical type head 41 is rotatable and slidable. The head 4l carries a set of numeric characters and a set of symbolic characters 42 distributed in two horizontal rows and twelve vertical columns. The head 41 is normally disposed with the two rows of characters or types centred with respect to the printing point on the platen 21. The columns of characters are distributed so that six of them corresponding to the symbolic characters, for example operational symbols, are located in a semi-cylindrical zone (FIG. I l disposed in front of the platen 21 and offset clockwise by about 22&#34; with respect to the platen itself. The other six columns consisting of numeric characters, corresponding for example to the ten digits. the decimal point and the minus algebraic sign. are located in turn in another semi-cylindrical zone disposed on the face remote from the platen 21 and also offset by 22 with respect to the platen itself.  
  To the cheek element 27 (FIG. I) there is fixed a coil spring 43 which engages round a return pulley 44 and is fixed to the side piece 25 of the device. Owing to the action of this spring 43, the carriage 22 (FIG. 4) is kept at rest in the proximity of the side piece 26, with one end of the sleeve 23 arrested against a shock-absorbing ring 46, for example of rubber.  
  The cheek element 27 is moreover provided with a notch 47 slidably engaged by a striking tab or lug 48 (FIG. I) which extends along the device throughout its length. The tab 48 can turn by means of two cylindrical ends between the side pieces 25 and 26 and is adapted to bring the types 42 into engagement with the platen 21 for pringing by means of an ordinary inked ribbon 49 (FIG. 4). At the right-hand end of the tab 48 in the drawing there is keyed a crank 5] (FIG. I) which cooperates. through a roller 52 and with the aid of a spring 53, with a striking cam 54 keyed on the shaft 29. In FIG. 7, the reference indicates the diagram of the angular movements of the crank 51 as a function of the positions of the shaft 29.  
  The printing device comprises a programming mechanism indicated generally by the reference 195 (FIG. 2). which comprises a selection clutch 58 and a transport or shift clutch 85. More particularly. the clutch 58 includes a driven part 57 rotatable on a shaft 61 and fast with a gear wheel 56. The wheel 56 is in mesh with a gear wheel of one quarter its own diameter, which is keyed at the lefthand end of the shaft 29 in FIG. 2.  
  The driving part of the clutch 58 is constituted by a hollow cylinder 59 having a central flange keyed on the shaft 61. This forms the driving shaft and. in turn. is rotated anticlockwise in the drawing by an electric motor 62 through the medium of a toothed belt 65. The cylinder 59 is provided with four windows 63 in which there can be inserted a clutch dog 64 guided slidably in two slots of a pair of projections 66 of the driven part 57.  
  The dog 64 engages with an opening a lug 69 of a control ring 71 connected to the driven part 57 by a coil spring 72.  
  The control ring 71 is provided with four control elements constituted by lugs 73 arranged at 90 from one another. One of these lugs is normally arrested against the top edge of an arm 74 turning on a fixed shaft 76 and keeps the dog 64 disengaged from the windows 63. The driven part 57 is integral with a positioning or counting cam comprising four-lobed selection cam 77 and is normally locked at rest by a positioning or counter-operating arm member 78. The arm member 78 is pivoted on the shaft 76 and is part of a selection sensor constituted by a bail 79 having another arm 80 also pivoted on the shaft 76. The arm 78 is adapted to cooperate with the cam 77 by the action ofa spring 81 on the arm 80. Referring to FIG. 6, the reference 70 indicates the diagram ofthe angular movements of the arm 78 of the bail 79 as a function of the rotary movements of the driving part 59 and the driven part 57.  
 The clutch 85 (FIG. 2) of the programming mecha nism 195 includes a driven part 84 which can also turn on the shaft 61. On the driven part 84 there is formed a programme cam constituted by a cam slot 83. The slot 83 is engaged by a pin 82 fixed to the arm 74. Referring to FIG. 6. the reference 75 indicates the dia gram of the angular movements of the arm 74 as a function of the movements of the part 59 and the driven part 84.  
  The clutch 85 has as its driving part the same cylinder 59, which is provided on the right with another four openings 90 arranged so that they are offset through 45 with respect to the openings 63. The openings 90 can be engaged by a clutch dog 86 which is guided by two slots of a pair of projections 87 of the driven part 84 which are disposed at rest parallel to the projections 66.  
  The dog 86 engages a lug 89 of a control ring 91 which can turn on the driven part 84. A spring 92 stretched between the part 84 and the ring 91 tends to cause the latter to rotate with respect to the part 84 and to shift the dog 86 towards the openings 90. The driven part 84 of the clutch 85 is provided with three notches 99, 100 and 101. At rest, a projection 95 of an arm 97 pivoting on a shaft 98 engages the notch 99 with the aid ofthe coil spring 81. The corresponding diagram of angular movements of the arm 97 as a function of the rotary movements of the driving part 59 and the driven part 84 is indicated by the reference 90 in FIG. 6. The ring 91 (FIG. 2) is provided with a pair of control elements constituted by two lugs 93 and 88 arranged at 180&#34; from one another. The lug 93 is longer than the lug 88 and is normally arrested by a projection 94 of a connecting rod 96, which keeps the dog 86 disengaged from the openings 90 and stops the driven part 84.  
  The connecting rod 96 connects one arm of a bail 104 pivoting on a fixed shaft 98 to one arm 106 ofa bail 117 pivoting on another fixed shaft 107. The arm 106 is connected in turn to the plunger 108 of a start eiectromagnet 109 energized by the device controller (not shown in the drawing). The plunger 108 is normally kept withdrawn from the electromagnet by the action of a spring 110 on the arm 106.  
  The lugs 88 and 93 of the clutch 85 are adapted to be arrested by a projection 112 of the arm 80. The lug 93 is moreover adapted to be arrested by a second projection 111 of the connecting rod 96, while the projections 94 and 111 are located to the left of the path of the shorter lug 88. Another projection 125 of the arm arrests :1 lug 113 of a lever 114 which is pivoted on a pin 115 fixed to the arm 97 and is connected to this arm by a coil spring 116 which urges it to turn anticlockwise.  
  The other arm l18 of the bail 117 is adapted to be arrested by one end of a stop slider 119 (FIG. 4) cooperating with a lever 121 pivoted on a fixed pin 120. A spring 122 acting on the slider 119 holds the other end of the lever 121 so that it normally bears against the side of the plate 38 and tends to push the slider 119 into the path of the arm 118. The action of the return spring 43, however, prevails over the action of the spring 122, as a result of which the end ofthe slider 119 is normally out of the path of the arm 118 and does not affect the movement of the latter.  
  The driven part 84 (FIG. 2) of the clutch comprises a control cam 123 which is adapted to cooperate with an arm 124 of the bail 104. The arm 124 is normally caused to bear on the cam 123 by the action of the spring through the medium of the arm 106 and the connecting rod 96. On a lower projection of the arm 124 there bears a pin 127 fixed to a cam follower lever 129. This lever is adapted to co-operate in turn with the cam 123 on the side diametrically opposite with respect to the arm 124. On the lever 129 there is pivoted a link 132 which is slidable in a fixed guide 128 and is pulled by a spring 131 to keep the pin 127 bearing on the arm 124. Referring to HO. 6, the references 133 and 135 respectively indicate the diagrams of the cam 123 referred to the arm 124 and to the lever 129 as a function of the angular positions of the part 59 and the part 84. The slider 132 (FIG. 2), in turn, through the medium of a pin 134. keeps normally open the contacts of a switch indicated generally by the reference 138 and disposed in series with the supply circuit of the motor 62.  
  The driven part 84 of the clutch 85 moreover comprises a follow-up cam 139 which co-operates with a pin 141 fixed to a first arm of a lever 142 pivoting on the shaft 76. On a second arm of the lever 142 there bears a pin 144 of a crank 146 keyed on the shaft 34. A spring 143 fixed at one end to a pin 145 of the crank 146 ensures the bearing action between the pin 14] and the cam 139 and between the pin 144 and the lever 142, keeping the rack 31 normally disengaged from the threaded sleeve 28. Referring to FIG. 6, the reference indicates the diagram of the angular movements of the lever 142, starting from the rest position, as a function of the rotary movements of the parts 59 and 84.  
  The other end of the spring 143 is connected to a lever 147 pivoting on the shaft 98 and normally bearing by means of a pin 148 between the teeth of a sawtoothed wheel 149 keyed on the platen 21 (FIG. 4). With the saw-toothed wheel 149 there also co-operates a pawl 151 which is pivoted on a lever 152 turnable on the shaft 98. The pawl 151 is urged against the teeth of the wheel 149 by a spring 153 stretched between the pawl 151 and the same lever 152. a pin I54 fixed to the lever 152 is engaged in turn in another cam slot 156 of the driven part 84 of the clutch 85. This cam ensures for the lever 152 an angular movement. as a function of the rotary movements of the parts 59 and 84. which is indicated by the reference 155 in FIG. 6 and constitutes. together with the pawl 151 (HO 2) and the sawtoothed wheel 149, the line-spacing mechanism of the device.  
  Finally. the driven part 84 of the transport clutch 85 is integral with a toothed wheel 157 meshing with a toothed wheel 158 (FIG. 1 )ofcqual diameter rotatable in the side piece 26. A transverse shaft 159 is rotatable in turn in the side piece and in a sleeve integral with the wheel 158. The toothed wheel 158 is integral with a bevel gear 171 forming a first crown wheel ofa differential 172. The gear 171 is in mesh. through a bevel planetary pinion 173. with another bevel gear 174 which forms the second crown wheel of the differential 172 and is keyed on the shaft 159.  
  On the shaft 159 there is moreover keyed a toothed cylinder 181 which extends across the entire width of the device. The cylinder 181 is engaged by a toothed wheel 182 rotatable on the pin 183 pf the plate 38. The  
 teeth of the toothed wheel 182 project to the left in FIG. 1 and mesh in turn with a ring gear 184 integral with the head 41. producing a unitary transmission ratio between the head 41 and the driven part 84 of the clutch 85.  
  The bevel pinion 173 is rotatable on a support 186 rotatable on the shaft 159 and provided. on the opposite side with respect to the pinion 173. with a toothed sector 187 in mesh with the teeth of a cup-shaped toothed sector 188 rotatable on a fixed pin 189. The sector 188 is integral in turn with another toothed sector 191 which is in mesh with a series of annular grooves 192 formed in a selection drum 193. The drum 193 (FlG. 3) is angularly fixed on a shaft 196 rotatable between the side pieces 25 and 26 of the device and is displaccable axially along the shaft 196 through the agency of a character selector indicated generally by the reference 194. which will be described in detail hereinafter. The shaft 196 represents the driving shaft of the selector 194 and carries at the left-hand end in FIG. 2 a toothed wheel 197 like the toothed wheel 55 and also meshing with the toothed wheel 56 of the driven part 57 of the selection clutch 58.  
  The programming mechanism 195 ofthe printing device controls. as will be described hereinafter. through the transport clutch 85 and the differential 172, the transport mechanism of the head 41 and. through the selection clutch 58, the said selector 194.  
  The shaft 196 carries at the righthand end in FlG. 3 a synchronizing cam 198 which actuates a lever 199 turnable on a shaft 200 rotatable in turn in the fixed frame. in accordance with a movement diagram indicated by the reference 195 in FIG. 7. On the lever 199 (FIG. 3) there is pivoted a slider 201 which holds the lever 199 in contact with the active profile of the cam 198 by the action of a spring 202. The slider 201 carries at one end a small magnet 203 which. when it is shifted. is adapted to close the contacts of a reading relay 204 known per se to call up from the electronic controller the signals appertaining to a character to be printed. These signals command the selective energization of a series of selection cleetromagnets 205, 206 and 207 included in the selector 194. When these clectromagnets are energized. they are adapted to retain a corresponding series of armatures 208, 209 and 210 which are each pivoted in turn to one ofthe actuating setting elements 211, 212 and 213.  
  The printing device is particularly suitable for electronic calculators and comprises a storage unit 403 (FIG. 12) one part of which has a working programme recorded therein. while another part constituting the calculation store true and proper contains the coded four-bit data, in manner known per se. The unit 403 is connected to a calculating unit 404 and. through the medium of an input interface circuit 406, to a keyboard 407. The unit 403 is moreover connected by an input 405 thereof to the reading relay 204 (FIG. 3).  
  Two outputs of the unit 403 (P10. 12) are respec tively connected to the electromagnet 109 by way of an amplifier 410 and to an interface circuit 412 by way of a four-bit decoder 411. The circuit 412, in turn. is connected through an amplifier assembly 409 to the elec tromagnets 205, 206 and 207 of the selector 194. The unit 403 is adapted to transfer the data contained in the calculation store part selectively to the decoder 411 under the control of the keyboard or of the calculating unit 404. or under the control of the reading relay 204 in manner known per se. Until the end of the transfer of these data, the unit 403 keeps the electromagnet 109 energized.  
  The contents of the calculation store part of the unit 403 can moreover be zeroized by a zcroizing key 414 which moreover causes the deactivation of the electromagnet 109 and causes the generation of a code which activates all the electromagnets 205. 206 and 207.  
  In addition to the coded data relating to the characters to be printed. the unit 403 is adapted to generate a space code which energizes all the clectromagnets 206 of the selector 194. thus excluding printing. as will be seen better hereinafter.  
  The setting elements 211. 212. 213 of the selector 194 (FIG. 3) have a lower projection 216 on which acts a corresponding L-shaped arm of a single leaf spring 214. The spring 214 is fixed on the shaft 200 and keeps the armatures 208. 209, 210 normally in contact with the cores of the electromagnets 205. 206. 207. On the shaft 200 there is fixed a crank 217 equipped with a pin 218 engaged in a slotted hole 219 in a connecting rod 221 pivoted in turn on the rocking lever 142 (FIG. 2). 1n the inoperative position. the crank 217 is held with the pin 218 at the left-hand end. in HO. 2, of the slot 219 by the action of a coil spring 222. On the shaft 200 (HO. 3) there is moreover fixed a follow-up element constituted by a second crank 223 equipped with a pin 224 which is adapted to co-opcrate with a projecion 226 of the lever 199.  
  The setting elements 212 are each held against the leaf spring 214 by a spring 220. The setting element 211. on the other hand. is connected by a pin 282 and a slot 283 to a lever 279 pivoting on a fixed spindle 281 and which by means of a coil spring 215 mormally holds the setting element 211 against the spring 214. Similarly. the setting element 213 is connected by a pin and slot to a lever 30] pivoting on a spindle 284 and is held so that it bears against the spring 214 by a coil spring 235. The action of the spring 214 prevails over that of the springs 215, 220 and 235.  
  The setting elements 211 and 212 of the electromagnets 205 and 206 are disposed in front ofthe drum 193 and are adapted to co-opcrate with cam portions of the drum 193 to shift it by variable amounts along the shaft 196 and select a corresponding column. in the manner which will be described hereinafter. when the corresponding electromagnets 205 and/or 206 are deenergized.  
  The setting elements 212 are moreover adapted to be sensed by a corresponding series of lugs 227 of a bail 228 turning on the shaft 200. An arm 229 of the bail 228 co-operates by the action of a spring 230 with a cam 231 keyed on the shaft 196 and which keeps the lugs 227 normally above the setting elements 212. The diagram ofthe movements ofthe arm 229 as a function of the angular positions of the shaft 196 is indicated by the reference 240 in FIG. 7. On the arm 229 (FIG. I) there is pivoted a connecting rod 232 which is guided by means of a slotted hole 233 by the cylindrical part of a tab 246 which can turn in the side pieces and 26. The connecting rod 232 is provided with a projection 234 which is adapted to arrest a lug 236 of the crank 51.  
  The setting element 213 (FIG. 3) is disposed in front ofa second selection drum 237 angularly fixed and axially slidable on the shaft 196. The drum 237 has cams adapted to co-operate with the setting element 213 positioned by the selection electromagnet 207 to be shifted variably along the shaft 196 in dependence upon the signals received from the store. The drum 237 is provided with an annular groove 238 which is engaged by a pin 239 fixed to a bell-crank lever 241 pivoted in turn on a fixed pin 242. The bell-crank lever 241 is connected by a link 243 to a crank 244 (FIG. 1) fast with the tab 246.  
  The tab 246 is slidably engaged by a notch 247 at the bottom of a plate 245 of the carriage 22. This plate is provided with a slot 250 and a slotted hole 248 by means of which it is guided by a cylindrical portion of the nut 36 and by the sleeve 23, respectively. The plate 245 moreover carries a block 249 terminating in a bar 251 which is slidably engaged by an annular groove 252 of the head 41.  
  The block 249 has a substantially octagonal crossscction with two vertical faces on which there normally bear two V-shaped ends 253 of two arms ofa positioning spring 254 having two turns wound on the cylindrical portion of the nut 36.  
  The positions of the toothed cylinder 181 (FIG. 1) are corrected by a lever 161 pivoting with a large play on the shaft 200 and adapted to engage by means of a toothed end between the teeth of the said cylinder 181. The lever 161 is shifted by a cam 162 keyed on the shaft 196 with the aid of a spring 163 and in accordance with a movement diagram indicated by the reference 155 in FIG. 7.  
  The head 4] is hollow and is provided with 12 longitudinal grooves 164 (FIG. 11) corresponding to the columns of characters or types 42. These grooves are adapted to be engaged by a toothed end of a lever 165 which can turn on the sleeve 23 and is free to turn in a corresponding axial slot 150 of the shaft 39. The lower end of the lever 165 is notched and eo-operates in turn with a pin 166 of a lever 167 pivoting on a pin I68 fixed to the plate 27. The lever 167 in turn cooperates through the action of a spring 169 stretched between the pin 166 and the plate 27 with a cam 170 formed on the sleeve 28 and moves in accordance with a diagram indicated by the reference 175 in FIG. 7.  
  The printing device operates in the following manner:  
 Selection of Symbols At the beginning of the cycle, in response to a command from the keyboard 407 or from the calculating unit 404, the unit 403 (FIG. 12) of the device controller sends a start signal in known manner to the electromagnet 109 through the amplifier 410. Moreover, by way of the decoder 411, the interface 412 and the assembly of amplifiers 409, it sends a series of signals representing the first symbol to be printed to the selection electromagnets 205, 206 and 207 (FIG. 3). The electromagnet 109 attracts the plunger 108, producing an anticlockwise rotation of the lever 106. The connecting rod 96 shifts to the left in the drawing, releases the lug 93 of the ring 91 from the corresponding projection 94 and causes the bail 104 to turn and bring the end ofthe arm 124 above the cam 123. The lower projection of the arm 124 rotates the lever 129 clockwise, shifting the slider 132 to the left in the drawing and closing the contacts of the switch 138. The electric motor 62 is set in motion and causes the shaft 61 connected thereto to rotate anticlockwise.  
  The ring 91 of the clutch now rotates slightly anticlockwise and, by means ofthe lug 89, shifts the clutch dog 86 towards the inner surface of the already rotating hollow cylinder 59. This surface slides on the dog 86 until the said dog 86 engages with one of the openings 90. The driven part 84 is thus carried along by the shaft 61 and also begins to rotate anticlockwise. The toothed wheel 158 now drives in rotary movement the crown wheel 171 (FIG. l)ofthe differential 172. Through the planetary pinion 173. the other crown wheel 174 and the cylinder 181 are set in rotation. as a result of which the pinion 182 causes the head 41 to rotate anticlockwise around the shaft 39 in such manner as to centre the zone 40 containing the symbolic characters (FIG. 11) with respect to the platen 21.  
  When the driven part 84 (FIG. 2) has rotated through about 12, the cam 139 allows the spring 143 to cause the lever 142 to rotate anticlockwise (see also the diagram in FIG. 6) through the medium of the crank 146 and the pin 144, shifting the connecting rod 221 to the left. The crank 217 then turns clockwise together with the shaft 200 through the action of the spring 222 until the pin 224 of the crank 223 (FIG. 3) is brought into contact with the projection 226 of the lever 199. The setting elements 211, 212 and 213 corresponding to the non-energized electromagnets move away from the cores thereof owing to the action of the respective springs 215, 220 and 235. Following the arms of the leaf spring 214, these setting elements move up to the drums 193 and 237 and are thus positioned to co-opcrate with the respective cam portions. The setting elements 211, 212 and 213 corresponding to the energized electromagnets, on the other hand, remain in the unset position, with the respective armatures in contact with the cores of the corresponding electromagnets. Through the medium of the shaft 34, the clockwise rotation of the crank 146 (FIG. 2) causes in turn the engagement of the rack 31 with the threaded sleeve 28.  
  In this first stage of rotation of the driven part 84, the pin 82 of the arm 74 is guided by a first part of the cam 83 which is of increasing radius (see also diagram 75 of FIG. 6). The arm 74 thus turns anticlockwise and releases the lug 73 of the selection clutch 58. The control ring 71 turns slightly anticlockwise owing to the action of the spring 72 and. through the medium of the lug 69, brings the dog 64 towards the inner surface of the cylinder 59. Since the openings 63 and 90 are offset by 45, the dog 64 can encounter one of the openings 63 only in correspondence with rotary movements of the cylinder 59 through 45 plus a multiple of 90 with respect to the inoperative position. On the release of the lug 73, the dog 64 therefore slides on the inner surface of the cylinder 59 and keeps the selection clutch 58 open or disengaged.  
  After a preliminary cycle of the driven part 84 corresponding to a rotation of about 22, the lug 93 of the ring 91 encounters the projection 112 of the arm 80 and opens or disengages the clutch 85, while the projection 95 of the arm 97 is inserted in the notch 100 and locks the driven part 84 in the position reached. Owing to the unitary transmission ratio existing be tween the toothed wheel 157 and the ring gear 184 (FIG. 1). at the end of the preliminary cycle the head 41 is arrested with the columns of symbols centred with respect to the platen 21.  
  With the clutch 85 (FIG. 2) open, after a further rotation of the driving part 59 through 23 (total rotation of 45), the dog 64 engages one ofthe openings 63 and closes or engages the selection clutch 58. Through the medium of the toothed wheel 56, the clutch 58 sets in motion the shaft 29 and the driving shaft 196 of the se lector 194 (FIG. 3), starting a selection sycle for the symbol to be printed.  
  When the shaft 196 has rotated through about 5 rotation of the part 57), the cam 231 allows the bail 228 to turn clockwise owing to the effect of the spring 230, causing the lugs 227 to probe the upper profile of the setting elements 212 (see also the diagram 240 of FIG. 7). If at least one of the electromagnets 206 is deenergized. as it is in the case when a symbol is to be printed. the corresponding positioned setting element 212 arrests the lug 227 with its upper edge. The connecting rod 232 (FIG. 1) shifts only a little to the left and the corresponding projection 234 remains out of the path ofthe lug 236 of the crank 51, thus prearranging the crank 51 for striking.  
  If the electromagnets 206 (FIG. 12) are all energized, in response to a space code from the unit 403. the setting elements 212 (FIG. 3) are all not positioned. Con sequent upon the sensing action of the lugs 227, the bail 228 then rests the end of the arm 229 on the low profile of the cam 231. The connecting rod 232 moves to the left and brings the projection 234 into the path of the lug 236, as a result of which the striking of the crank 51 is excluded.  
  In this first stage of rotation of the driven part 57, the cam portions of the first selection drums 193 and 237 (FIG. 3) co-operate with the positioned setting elements 211, 212 and 213 and are axially shifted by a variable amount along the shaft 196. By means of the grooves 192 (FIG. 1) and the sectors 191 and 188, the drum 193 causes the sector 187 and the planetary pinion 173 of the differential 172 to rotate about the shaft 159. Since the crown wheel 171 is now stationary. the other crown wheel 174 is rotated together with the cylinder 181, which causes the toothed wheel 182 to rotate on the pin 183. This toothed wheel transmits the motion with its front teeth to the ring gear 184, rotating the head 41 about the shaft 39 and thus selecting the column of the symbol to be printed.  
  The drum 237, moving along the shaft 196, causes the lever 241 to turn about the pin 242, so that the crank 244 and the tab 246 fast therewith are turned through the medium of the link 243. The plate 245 is now shifted vertically and, by means of the bar 251 and the groove 252, transmits the motion to the head 41, which slides along the shaft 39 and positions the row of the symbol to be printed, as a result of which the symbol to be printed is now positioned in front of the printing point. The positioning of the character is completed in a rotation of the shaft 196 of about to which there corresponds a 30 rotation of the driven part 57 of the selection clutch 58. Due to the rotation of the shaft 29 (FIG. 4), the sleeve 28 is moreover screwed on the rack 31 and begins to move together with the carriage 22 axially along the shaft 29 to the right in the drawing. The spring 254 engages the inclined sides of the block 249 (FIG. 1), correcting the axial position of the head 41.  
  When the shaft 196 has rotated through about (40 rotation of the part 57), the cam 162 (see also the diagram 155 of FIG. 7) turns the lever 161 clockwise and this locks in this way the cylinder 181. At the same time, due to the action of the spring 169, the cam of the shaft 29 causes the lever 167 to turn anticlockwise about the pin 168 (see also the diagram of FIG. 7). The lever 167, in turn, through the agency of the pin 166, rotates the lever 165, the toothed end of which engages in one of the longitudinal grooves 164 of the head 41, correcting the angular position thereof.  
  When the shaft 29 has rotated through 163 (42 rotation of the part 57), the striking cam 54 releases the roller 52. If the projection 234 is out of the path of the lug 236, due to the action of the spring 53 the crank 51 turns clockwise together with the tab 48. The plate or check element 27 then turns anticlockwise on the shaft 24, causing the selected symbol to strike against the sheet of paper through the inked ribbon 49. If, on the other hand, the projection 234 is in the path of the lug 236, the crank 51 is arrested after a brief rotation. thus preventing the striking of the head 41 and therefore the printing of the selected symbol.  
  During the following rotation of the shaft 29, the cam 54 causes the head 41 to return to the inoperative position. the two cams 162 and 170 releasing the head 41, and the cam 231 brings the bail 228 back to rest. Thereafter, the cam 198 (FIG. 3) causes the lever 199 to turn anticlockwise (see also the diagram of FIG. 7). rotating the shaft 200 anticlockwise through the projection 226 and the pin 224. The leaf spring 214 thus brings the previously positioned setting elements back to the inoperative position. carrying the armatures 208, 209 and 210 into contact with the cores of the corresponding electromagnets 205, 206 and 207 (FIG. 5).  
  When the driven part 57 has rotated through about 60 240 rotation of the shaft 196), the cam 198 (FIG. 3) shifts the slider 201 to the right until the magnet 203 is brought into correspondence with the contacts of the reading relay 204, which are thus closed. From the calculation store part of the unit 403 (FIG. 12) there is then retrieved a fresh combination of signals corresponding to a second symbol which energize the electromagnets 205, 206 and 207 selectively through the decoder 411, the interface circuit 412 and the assembly of amplifiers 409.  
  When the part 57 has rotated through about 60 (FIG. 2). the increasing profile of the following lobe of the cam 77 causes the bail 79 to turn anticlockwise (see also the diagram 70 of FIG. 6) and brings the projection 125 of the arm 80 below the lug N3 of the lever 4. This lever is thus released and. through the action of the spring 116, moves the lug 113 above the path of the arm 80 and is arrested by a projection thereof against the shaft 98. When the part 57 has rotated through about 75 (120 rotation of the part 59). the arm 80 releases the lug 93 of the transport clutch 85 from the projection 112. The ring 91 moves sharply anticlockwise owing to the action of the spring 92 and shifts the dog 86 towards the surface of the hollow cylinder 59. Since the openings 90 are mutually offset by 90, the dog can encounter an opening only by rotary movements of the part 59 of 22 plus a multiple of 90, as a result of which the driven part 84 temporarily remains stationary.  
  During the rotation of the driven part 57 from about 65 to about 90 (240-360 of the shaft 196). the cam 198 (FIG. 3). by means of its descending profile, causes the lever 199 and the shaft 200 to turn clockwise (see also the diagram 195 of FIG. 7). The leaf spring 214 leaves the setting elements 211, 212 and 213, which are positioned selectively by the springs and by the corresponding electromagnets to select a second symbol still during the printing cycle ofthe first symbol, which ends when the part 57 has rotated through 90 (FIG. 2).  
  When the part 57 has rotated through 120, the selection ofthe second operational symbol is completed and this is printed when the same part 57 has rotated through about 135 180 rotation of the part 59) in the manner already described for the preceding symbol. The shaft 29 (FIG. 2) has rotated by one revolution with respect to the position of the preceding striking operation and the sleeve 28 has shifted by one step. as a result of which the second symbol is printed alongside the preceding one at a distance corresponding to the pitch of the rack 31.  
  As soon as the carriage 22 begins to move to the right in FIG. 4. it releases the end of the lever 121. This lever now allows the spring 122 to shift the slider 119 until it is arrested against the side of the arm 118, which is raised by the energization of the electromagnet 109 (FIG. 2). The locking ofthe bail 117 in the rest position is thus prearranged for the purpose of preventing any premature actuation of the electromagnet 109 before the return of the carriage to the beginning. After the anticlockwise rotation ofthe arm 80, although the cam 77 presents a low profile to the arm 78, the end of the arm 78 remains raised by the cam 77 since the arm 80 is arrested by the lug 113 of the lever 114, so that the arm 80 can no longer have an effect on the transport clutch 85 until a cycle of prearrangement of the digit zone 45 (FIG. 11) is initiated.  
 Prearrangement of the Digit Zone After a 202 rotation of the part 59 (FIG. 2) (157 rotation of the part 57), the dog 86 engages one of the openings 90 and is carried along by the cylinder 59, setting the driven part 84 in rotation again. In this stage (rotation of one revolution and 268 of the shafts 29 and 196). the relay 204 (FIG. 3) has already retrieved from the store part of the unit 403 (FIG. 12) a fresh series of signals which now relate to the amount to be printed. The spring 214 (FIG. 3) again leaves the setting elements 211. 212, 213, which are positioned to select the first numeric character of the amount. The head 41 (FIG. 1) now rotates about the shaft 24 clockwise and returns to the inoperative position. keeping the toothed wheel 182 in engagement with the cylinder 18]. Owing to the rotation of the part 84 and through the medium of the crown wheels I71 and 174 of the differential 172, the head 41 rotates about the shaft 39 to prearrange the numeric character zone for printing, while owing to the rotation of the shaft 29 it is shifted parallel to the platen 2!.  
  After the part 84 has rotated through about 15 with respect to the standstill position (total rotation of 37). the cam 83 (FIG. 2). by means of a second portion now of decreasing radius of its profile (see also the diagram of FIG. 6), causes the arm 74 to turn clockwise, bringing the end thereof into the path of the arriving lug 73. The profile of increasing radius adjacent the notch causes the arm 97 to turn clockwise (see also the diagram 90 of FIG. 6). By means of the pin 115, the arm 97 causes the lever 114 to turn about the shaft 98, releasing the arm 80 which. owing to the action of the spring 81, turns clockwise until the end of the arm 78 is caused to bear on another lobe of the cam 77 (see also the diagram 70 of FIG. 6).  
  After a further rotation of the part 57 through 8 (total rotation of 180 of the part 57 and of 225 of the part 59), the lug 73 encounters the upper edge of the arm 74. The dog 64 is released from the opening 63 and opens or disengages the clutch 58, completing the cycle of selection of the second and last symbol. The selector 194 (FIG. 3). on the other hand. remains prearranged for the selection of the first digit of the amount. Due to the action of the spring 81 on the arm 80 (FIG. 2). the end of the arm 78 is brought against the abruptly decreasing profile of one of the lobes of the cam 77 and prevents rebound of the driven part 57.  
  When the driven part 84 has rotated through about with respect to the standstill position. the cam 139 presents to the lever 129 (see also the diagram 135 of FIG. 6) a high profile which keeps the said lever 129 turned clockwise and holds the switch I38 closed independently of the position of the arm I24 and therefore of the control of the electromagnet 109.  
  After the part 84 has rotated through 158 from the intermediate standstill position (total rotation of 360 of the part 59), the cam 83 causes the arm 74 to turn anticlockwise (see also the diagram 75 of FIG. 6). The arm 74 thus releases the lug 73 of the ring 71, prearranging the clutch 58 for closing or engagement.  
  When the part 8 4 has rotated through about the cam 123 presents the profile of smaller radius to the end of the arm 124. Since, on the other hand. the electromagnet 109 is still energized, the arm 124 remains in the previous position. keeping the connecting rod 96 still shifted to the left. When the part 84 has rotated through 180 from its intermediate standstill position (rotation of one revolution and 22 of the part 59), the lug 93 finally encounters the second projection 11] of the connecting rod 96 and opens the clutch 85, while the lug 88 is arrested against the upper edge of the projection 112. The arm 97, in turn, engages the projection 95 in the notch 101, thus locking the driven part 84.  
  During the 180 rotation of the part 84. the head 41 (FIG. I) has been rotated through 180 by the gear 157 and by the crown wheels of the differential 172. so that now the numeric character zone 45 is prearranged for printing and has the six columns of digits 42 centered with respect to the platen 21. The cam 139 (FIG. 2]. with a low and uniform profile (see also the diagram 140 of FIG. 6). has left the rack 31 in the preceding position of engagement with the sleeve 28.  
 Selection of Digits After a further rotation of about 23 of the part 59 with respect to the position reached at the end of the prearrangement operation (in all. one revolution and with the transport clutch 85 by now closed, the dog 64 engages one of the openings 63 and activates the selection clutch 58. The selector 194 (FIG. 3) is thus reactivated and produces the selection and printing of the first digit of the amount similarly to what has been described with regard to the selection and printing of the two symbols.  
  In the stage of transport of the head 41 (FIG. I). the carriage 22 has remained in the position reached at the end ofthe printing cycle ofthe second symbol. The first digit of the amount is therefore printed to the right of the second symbol. at one printing step therefrom. and the respective cycle is completed at one revolution and 135 of the part 59.  
  Immediately after the printing of the first digit. the cam I98 retrieves from the store 403 (FIG. 12) a fresh group of signals to select the second digit of the amount. The character selected in this way is printed beside the preceding one owing to the simultaneous shifting of the carriage. On the passage of the first lobe of the cam 77 (FIG. 2 l. the arm 78 of the bail 79 turns anticlockwise and remains in this position owing to the action of the lug 113 on the arm 80, in the manner previously described in regard to the selection of the symbols. More particularly. when the part 57 has rotated through about 75. the upper edge of the projection 112 releases the lug 88 of the transport clutch 85. which remains open. however. owing to the action of the projection III on the lug 93.  
  During the printing of the amount. the store 403 (FIG. 12) counts the digits printed and sends the space&#34; code every three digits. There is therefore a shifting of the carriage 22 (FIG. I) by one step unaccompanied by printing. so that the digits of the amount are grouped in thousands separated by a space.  
  Assuming that there are n digits in the amount. with n greater than or equal to 2. the nth cycle of selection of the digits is therefore initiated after a rotation of (n l 90 of the part 57 and a total rotation of 135 (u 2) 90 of the part 59. The nth digit having been printed. after a rotation ofthe part 57. the fresh signals retrieved by the relay 204 deenergize the electromagnet 109 (FIG. 2) and energize all the electromagnets 205. 206 and 207. The spring 110 rotates the arm I06 clockwise. causing the end of the arm 124 to hear of the low profile of the cam 123. The connecting rod 96 returns to rest. so that the projection I11 releases the control element 93 of the clutch 85, prearranging it for reactivation. The arm 118 is thus lowered and. owing to the action. of the spring 122. the slider 119 shifts to the left. re-introducing itself into the path of the said arm 118. The cam follower lever 129. on the other hand. shifts only a little. bearing on the high profile of the cam 123. so that it keeps the contacts of the switch 138 closed and the motor 62 running. Prearrangement of the Symbol Zone For the reasons already stated. a further rotation of 7 of the part 59 (total rotation of 102 (n 2) 90).  
 the dog 86 engages one of the openings 90 and closes the clutch 85, setting the driven part 84 in rotation again. After a fresh rotation of about 15 of this part 84 (total rotation of 224). the cam 83 (see diagram of FIG. 6) presents to the pin 82 a fourth descending portion of its profile which brings the upper edge of the arm 74 back into the path of the arriving lug 73. At the same time. the profile of increasing radius adjacent the notch 10] turns the arm 97 clockwise. releasing the arm from the lug 113 in the manner already seen. The lug 73 finally encounters the end of the arm 74, as a result of which it opens the clutch 58 and completes the cycle of selection of the nth digit of the amount. More particularly, the cam 198 (FIG. 3) causes the lever 199 to turn clockwise by means of its low profile. as a result of which the leaf spring 214 releases the set ting elements 211, 212 and 213, which remain disengaged. however. owing to the energization of the electromagnets 205. 206 and 207.  
  With the clutch (FIG. 2) activated. by rotation of the driven part 84. the head 4] (FIG. 1] again rotates about the shaft 39 and re-presents the symbolic character zone 40 in front of the platen 21. The cam 139, with the now increasing profile. turns the lever 142 clockwise and shifts the connecting rod 221 to the right in the drawing. Through the medium of the slotted hole 219 (FIG. 3). the crank 217 is turned anticlockwise and the leaf spring 214 urges the setting elements 211. 212 and 213 against the cores ofthe respective electromagnets 205 206 and 207 to ensure that they are all ready for the setting operation appertaining to a fresh amount.  
  Owing to the rotation of the lever 142 (FIG. 2), the crank 146 moreover turns anticlockwise and causes the rack 31 to be disengaged from the threaded sleeve 28. The spring 43 then draws the carriage 22 to the left in FIG. I, causing it to return to its rest position. The cam 156 (FIG. 2). in turn, rotates the lever 152 anticlockwise. The pawl I51 urges the teeth ofthe wheel 149 anticlockwise against the reaction of the rocking lever 147. producing the rotation of the platen 21 by one line-spacing step.  
  After a total rotation of the part 84 through 335, the cam 139 presents an abruptly decreasing profile to the lever 129 (see also the diagram of FIG. 6). Urged by the spring 131. the slider 132 opens the contacts of the switch 138, depriving the motor 62 of the supply voltage. Owing to inertia. the motor still carries out a brief rotation sufficient for the arrest of the lug 93 on the projection 94 of the connecting rod 96 and for the re-engagement of the projection 95 ofthe arm 97 in the notch 99. thus concluding the printing cycle of a line of characters.  
  It is obvious from the foregoing description that the device is provided with programming means constituted by the mechanism of FIG. 2, which are conditioned. through the medium of the bail 79. the lobed cam 77. the shaft 29 (FIG. 1) and the pair of elements consisting of the threaded sleeve 28 and the rack 31, by the position of the head 41. By means of the toothed wheel 157, the means 195 control the transport mechanism 157.158 and 172 in such manner as to prearrange the symbol zone 40 (FIG. 11) or the digit zone 45 of the head 41 for printing in correspondence with the position of the two symbols and the position of the digits of the amount.  
 Response to a Zeroizing Command The depression of the zeroizing or clearing key 414 (FIG. 12) erases the contents of the store 403, deactivating the electromagnet 109 and activating all the electromagnets 205. 206 and 207. If this takes place during the preliminary cycle of rotation of the clutch 85 (FlG. 2). the control cam 123 (see also diagram 133 of FIG. 6) keeps the arm 124 of the bail 104 turned anticlockwise. The connecting rod 96 remains shifted to the left with the projection 11] in the path of the lug 93 of the clutch 85. The clutch S8 is duly activated and starts a selection cycle. Owing to the energization of all the electromagnets 206. the selection drum 193 (FIG. 3) remains stationary. however. and the connecting rod 232 prevents the striking ofthe head 41 (FIG. 1). During this cycle. the bail 79 prearranges the clutch 85 for reactivation and the relay 204 (FIG. 12) retrieves a fresh series of signals from the store 403. The signals. being relative to a zero content. keep the electromagnets 206 activated. as a result of which no character is printed. Thereafter. as already described. the clutch 85 (FIG. 2) is reactivated. prearranges the digit zone 45 for printing and prearranges the clutch 58 for reactivation.  
  When the part 84 has rotated through 175, the cam 123 (FIG. 2) turns the arm 124 clockwise. bringing the connecting rod 96 back to the rest position. The clutch 85. however. is deactivated by the arrest of the lug 88 on the upper edge of the projection 112. The dog 64 then reactivates the clutch 58. starting a digit selection cycle in which once again no character is printed.  
  At one revolution and 120 of the part 59. a lobe of the cam 77 turns the arm 78 anticlockwise and releases from the projection 112 the lug 88 of the clutch 85. prcarranging it for reactivation. The first digit selection cycle having been completed. if a second one is initiated. this also takes place without any striking action of the head. During this second cycle. the dog 86 reactivates the clutch 58. which is in turn deactivated at the end of the second digit cycle by the arm 74 controlled by the cam 83.  
  The second 180 rotation of the part 84 having been completed. with the prearrangement of the symbol zone 40. the projection 94 of the connecting rod 96 arrests the lug 93. deactivating the clutch 85 so as to bring the kinematic trains back to their inoperative states.  
  It is therefore clear that. up to a rotation of 175 of the part 84, the control cam 123 keeps the member 96 with the projection 111 in the path of the control element 93 of the transport clutch 85 independently of the electromagnet 109. In this way. two symbol selection cycles and two digit selection cycles are effected. even if the clectromagnet 109 has been previously deactivated.  
 Selector The cam portions of the selection drum 193 (FIG. 3) are formed by protuberances constituted by two lateral sectors 259 and three intermediate sectors 26]. 262. 263. These three sectors have a development of about 160 (see also the development in plan in FIG. 9) and define with their flanks four grooves 264. 266, 267 and 268 which are equidistant and parallel. The sectors 261. 262 and 263 have a variously inclined portion which develops for about 80 in FIG. 3 and converges towards three leading edges. More particularly. the sector 261 has its left flank connected over a short distance to the leading edge and defines the groove 264 together with the sector 259. Starting from the leading edge. the right flank of the sector 261 has a part inclined to the right in FIG. 3 which runs towards the groove 266. The sector 262 has its leading edge centered between the two flanks, which. after a part inclined equally in both directions. define the grooves 266 and 267. Finally. the sector 263 has its right flank connected over a short distance to the leading edge and defines the groove 268. Starting from the leading edge. the left flank of the sector 263 has a part inclined to the left in FIG. 3 which runs towards the groove 267.  
  The leading edges of the sectors 261, 262, 263 are substantially aligned along a generatrix of the drum 193 and are disposed at rest in front of and above the path of the setting elements 212, at an angular distance of about 40. The number of setting elements 212 is also three and they are slidable in correspondence with slots in a U-shaped guide 269. Each of the setting elements 212. when it is positioned. is adapted to co-operate with the corresponding one of the sectors 261. 262. 263. More particularly. by the co-operation of a positioned setting element 212 with the corresponding left flank of the three sectors 26]. 262 and 263. the drum 193 is adapted to be shifted to the right by half a step. one and a half steps and two and a half steps. respec tively. in accordance with the respective diagrams 303. 304 and 305 of FIG. 8. By the co-operation of the setting elements 212 with the corresponding right flank of the three sectors 261. 262 and 263. the drum is adapted to be shifted by two and a half steps. one and a half steps and half a step. respectively. to the left. in accordance with the respective diagrams 307. 308 and 309 of FIG. 8.  
  The three setting elements 212 are moreover adapted to co-operate by means of the lower projections 216 with the arms of two substantially anchor-shaped plates 270 pivoted at their respective shafts to the connecting base of the guide 269. The two plates 270 are arranged one beside the other with their respective arms substantially aligned. Moreover. the adjacent arms are almost in contact so as to be both located in the path of the central setting element 212.  
  The drum 193 is provided with two prearranging cams formed by two raised sectors 271 with their flanks 272 and 273 converging towards a central groove 274 for a development of about anticlockwise (see also the development in plan in FlG. 9). This groove is normally slidably engaged by a guide or centering tongue 276 fixed to the guide 269 and adapted to co-operate also with the flanks 272 and 273. In front ofthe sectors 271 there is disposed the setting element 211 pivoted to the armature 208 of the electromagnet 205. and another setting element 277. The two setting elements are arranged below the tongue 276 and are slidable between the arms of the guide 269. When the setting ele ments 21 1 and 277 are positioned. they are adapted to co-operate with the flanks 272 and 273, respectively. of the sectors 271 to shift the drum 193 correspondingly to the right or to the left in accordance with the parts 311 and 312 of the diagrams of FIG. 8.  
  More particularly. the setting element 277 is guided through the medium of a slotted hole by the fixed shaft 281 and is connected by a pin and slot to the other arm of the rocking lever 279. Since the action of the leaf spring 214 prevails over the action of the spring 215 on the setting element 277. the setting element 277 is normally positioned in the path of the flank 273. while the setting element 211 is out of the path of the flank 272.  
  The grooves 192 of the drum 193 are finally adapted to co-operate with a toothed end 286 of an arm of the bail 228 controlled by the earn 231.  
  The second selection drum 237 of the selector 194 is also provided with cam portions constituted by two an nular grooves 291 and 292 which are substantially parallel for a development of about 170 and converge towards a common groove (see also the development in plan in FIG. In correspondence with the common groove 293, the grooves 291 and 292 are defined by flanks 294 and 296 (FIG. 10) of two prearranging cams constituted by two projecting sectors 297 (FIG. 3) which develop for about 150 in correspondence with the connecting zone between the grooves 291 and 292. The common groove 293 is normally engaged by a guide or centring tongue 298 fixed to the guide 269, which is moreover adapted to co-operate with the two grooves 291 and 292. More particularly. by co operation of the tongue 298 with the groove 291 or 292. the drum 237 is adapted to be shifted to the left or to the right. respectively, in accordance with the part 313 or 314 of the diagrams of FIG. 8.  
  The flanks 294 and 296 (FIG. 10) of the two sectors 297 are adapted to co-operate with the setting element 213 (FIG. 3) pivoted to the armature 210 of the electromagnet 207, and with another setting element 299 similar to the setting element 277. The setting elements 213 and 299 are also slidable between the arms of the guide 269 and are guided through the medium of slotted holes by the shaft 284. The setting element 299 is connected by a pin and slot to the other arm of the rocking lever 301. Since the action of the spring 214 prevails over the action of the spring 235, the setting element 299 is positioned in the path of the flank 296 (FIG. 10). while the setting element 213 is out of the path of the flank 294.  
  The four binary unit interface circuit 412 (FIG. 12) of the electronic controller is connected by way of the assembly 409 to the electromagnets 205, 207 by corresponding lines 416 and 417 and to the two lateral electromagnets 206 by another two corresponding lines 418 and 419. Finally. the central electromagnet 206 is supplied by an OR circuit 422 by way of an exclusive- OR circuit 423 connected in turn to the lines 418 and 419. By preventing in the store 403 the simultaneous deactivation of the two lines 418 and 419 and utilizing the three remaining combinations of activation of the two lines 418 and 419, selective deactivation of the three electromagnets 206 is obtained.  
  The &#34;space code. generated in the store 403 and decoded in the circuit 411, produces the activation of a connecting line 424 between another input of the OR circuit 422 and the activation of the lines 418 and 419. The three electromagnets 206 are energized simultaneously, as a result of which no character is printed.  
  The positioning of the selection drums 193 and 237 (FIG. 3) of the selector 194 in combination with the programming mechanism 195 (FIG. 2). takes place as follows:  
  The rotation of the shaft 196 (FIG. 3) having been started in the manner hereinbefore described. according to whether the electromagnets 205 and 207 are energized or deenergized, there are set. respectively. the setting element 277 or 211 by the electromagnet 205 and the setting element 299 or 213 by the electromagnet 207. Unless a space code has been generated.  
 one of the three electromagnets 206 is moreover deenergized. as a result of which the corresponding setting element 212 is in the path of the sector 261, 262 or 263. The other two electromagnets 206, on the other hand, are energized and retain the corresponding setting elements out of this path.  
  By the clockwise rotation of the drum 193. the centring element 276 immediately loses contact with the central groove 274. After a rotation of about 10, the prearranging cams 271 encounter the setting element 211 or the setting element 277. The flank 272 or 273, acting like a cam on the positioned setting element, then shifts the drum 193 axially to the right or to the left. respectively, in FIG. 3 (diagrams 311 and 312 of FIG. 8). When the shaft 196 has rotated through about 25, the sector 271 leaves the positioned setting element and keeps the drum 193, no longer guided, in the axial position reached in this way.  
  If the space code has been generated. no setting element 212 is positioned and the toothed end of the arm 286 is engaged in the grooves 192. The position of the drum 193 is thus corrected so as to produce an angular rotation of halfa step of the head 41 (FIG. 1), allowing the cams 162 and 170 to position the correcting or rectifying levers 161 and 165 correctly between the teeth of the cylinder 181 and in the grooves 164, respectivelyv If one of the setting elements 212 (FIG. 3) has been positioned, the bail 228 remains raised. as has already been described, and does not have any effect on the following operations. When the shaft 196 has rotated through about 45&#34;, the corresponding sector 261, 262 or 263 then cooperates with the positioned setting element 212. If the drum 193 has been prearranged by the setting element 211, the positioned setting elements 212 on the left, in the centre or on the right. respectively, cooperate with the inclined left flank of the corresponding sector 261, 262 or 263. In of rotation of the shaft 196, the drum 193 is then shifted to the right by half a step or by one and a half steps or by two and a half steps (diagrams 303, 304 and 305 of FIG. 8). Through the medium of the rack formed by the annular grooves 192 and the transmission mechanism already described. the head 41 (FIG. 11) then rotates anticlockwise and thus positions one of the three columns of characters 42 located to the right of the printing point in the zone prearranged for printing.  
  lfthe drum 193 (FIG. 3) has been prearranged by the setting element 277, the positioned setting elements 212 on the left. in the centre or on the right, respectively, co-operate with the inclined right flank of the corresponding sector 261, 262 or 263. In 120 of rotation of the shaft 196, the drum 193 is shifted to the left by two and a half steps. or by one and a half steps, or by half a step. respectively (diagrams 307, 308 and 309 of FIG. 8). The head 41 (FIG. 11) then rotates clockwise and positions one of the three columns of characters located to the left of the printing point.  
  During the subsequent rotation of the shaft 196, up to about 200, the positioned setting element 212 engages the groove 264, 266, 267., 268, retaining the drum 193 positively in the position reached.  
  As regards the drum 237, with the setting element 213 or 299 positioned, the tongue 298 leaves the groove 293 immediately after the commencement of the cycle. After a rotation of the shaft 196 of about 10. the prearranging cams 297 encounter the positioned setting element. The flank 294 or the flank 296 (FIG. acting as a cam on the positioned setting element 299 or 213, then produces a shifting of the drum 237 (FIG. 3) to the left or to the right. respectively. in FIG. 3 (diagram 313 or 314 of FIG. 8). bringing the converging part of the groove 291 or the groove 292 into correspondence with the tongue 298.  
  When the shaft 196 has rotated through about the positioned setting element leaves the common groove 293 and releases the drum 237. From about to about I08 of rotation of the shaft 196, the tongue 298 engages the converging part of the groove 29] or 292 previously prearranged. shifting the drum 237 by half a step to the left or to the right. During the succeeding rotary movements of the shaft 196, the tongue 298 co-operates with the parallel parts of the groove 291 or 292. keeping the drum 237 positively stationary in the position reached. Through the medium of the bell-crank lever 241 and the transmission mechanism already described. the head 41 (FIG. I) thus positions one of the two rows of characters 42 at each cycle.  
  When the shaft has rotated through about 240 (FIG. 3). the positioned setting element 212 ceases engagement with the corresponding groove of the drum 193.  
 After a rotation of the shaft 196 varying between 270 and 350. according to the number of steps by which the drum 193 has been shifted (diagrams 304 to 309 of FIG. 8). with the striking action having taken place by now and with the correcting elements 161 and 165 (FIG. I) disengaged. the inclined flanks 272 or 273 (FIG. 3) of the sector 271 encounter the guide tongue 276. Acting as a cam on the tongue 276, the sectors 271 bring the drum 193 back into the initial inoperative position. completing this stage after a rotation of the shaft I96 of about 350.  
  Similarly to the drum 193. after a rotation of the shaft 196 ofahout 270. the tongue 298 encounters the converging part of the groove 291 and 292 of the drum 237. The drum 237 is shifted towards the inoperative position. which it reaches when the shaft 196 has rotated through about 350, bringing the head 41 back into the initial inoperative position.  
  It is therefore clear that the selection clement constituted by the drum I93 or 237 is provided with a group of positioning cams 261, 262, 263 or 291 and 298. During the rotation of the drum 193, these cams are adapted to co-operate with positioning means. constituted by one of the three setting elements 212 or the tongue 298. when the drum 193 or 237 is shifted axially along the shaft 196 through the agency of the setting element 211, 277 and 299. In this way. the drum 193 and 237 is subsequently shifted along the shaft 196 by an amount equal to half a step. one and a half steps or two and a half steps. selecting the characters 42 of the head 41.  
  In the case of damage to the electronic controller or of interruption of the supply voltage. the anchor plates 270 prevent the positioning of more than one setting element 212. which would result in damage to the selector. In fact. the first setting element which is positioned causes one or two plates 270 to be turned by means of the projection 216. For example, by the positioning of the left-hand setting element 212 in FIG. 3, the projection 2l6 acts on the left arm of the left plate 270. which turns anticlockwise, bringing the right arm into the path of the central setting element 212. This arm moreover acts on the left arm of the right plate 270, which also turns anticlockwise, bringing itself into the path of the right-hand setting element 212. A possible simultaneous positioning of another setting element 212. for example the right-hand one, would cause the two plates 270 to be rotated clockwise. but, on the other hand. they are prevented therefrom by the lefthand setting element 212 which has been positioned first. In similar manner, the positioning of the central setting element causes the left-hand plate 270 to pivot clockwise and the right-hand plate 270 to pivot anti clockwise. respectively, into the locking position. The right-hand setting element 212, positioned first. causes the two plates 270 to pivot clockwise into the locking position and prevents the simultaneous positioning of the other two setting elements.  
  In the event of two or three setting elements being released at the same time. none of these can be positioned because of the impossibility of at least one plate 270 being rotated clockwise and anticlockwise simultaneously. The printing device then operates in a similar manner to that bereinbefore described for the simultaneous absence of positioning of the three setting elements 212.  
  It is understood that various modifications. improvements and additions of parts may be made in the print ing device without departing from the scope of the invention. For example. the device maybe used as alphanumeric output of a calculator in the case where it is planned to print amounts and descriptions in separate columns. In this case. the two parts of the head 41 will bear the digits and the letters. respectively.  
  In a variant. the programming means comprise a programme bar disposed parallel to the path of the head. This bar is provided with stops activating the transport mechanism in correspondence with the positions of the head in which the corresponding character zone must be prearranged for printing. In another variant. in addition to the programme bar controlling the transport mechanism. it also controls the character selector.  
  In a further variant. the programming means comprise a counter which counts the cycles of selection of the symbols. After this counter has counted the predetermined number of symbols. it activates the transport mechanism for prearranging the digit zone. At the end of the printing cycle. the counter is reset and reactivates the transport mechanism for prearranging the symbol zone.  
 We claim:  
  1. A serial printing device comprising a record supporting platen. a type head adapted to print numerical amounts as a result of an operation and signs indicating the nature of said operation and/or said amounts, spacing means for effecting relative character-spacing movement between said type head and said record supporting platen and for causing said signs to be printed in predetermined character positions. said type head having characters including digits for printing said numerical amounts and symbols for printing said signs. said digits and said symbols being respectively carried by two separate zones of said type head, shift means for causing said type head to prearrange one of said two zones for printing, setting elements means permutable for representing a code combination of one corresponding of both said digits and said symbols. selecting means controlled by said setting elements for causing said type head to select. for printing. one of said characters corresponding to said code combination in said one prearranged of said two zones. and a programming mechanism connecting said spacing means with said shift mechanism as to cause said type head to automatically prearrange for printing the zone of said two zones carrying the characters corresponding to said predetermined character positions.  
  2. A device according to claim I, wherein said char acter positions are successive positions in a row. said supporting platen being transversely fixed and said spacing means comprising a power drive shaft. and means connecting said shaft with said type head for transversely moving said type head with respect to said platen. and wherein said programming mechanism includes a shift clutch for operating said shift means. said shift clutch including a driving part. a driven part connected to said shift means and a command member for connecting for rotation said driving part with said driven part. cam means operatively connected synchro nously to said power driven shaft. sensing lever means cooperating with said cam means as to be moved between a first position causing said command member to connect said driving part with said driven part, to a second position causing said command member to disconnect said driving part from said driven part. and means for synchronizing said power driven shaft with said driven part of said shift clutch.  
  3. A device according to claim I wherein said charac ter positions are successive positions in a row. a predetermined number of said signs being printed before said amounts. said supporting platen being transversely fixed and said spacing means comprising a power driven shaft and means connecting said shaft with said type head for transversely moving said type head with respect to said platen. and wherein said programming mechanism comprises counting cam means synchronous with said power driven shaft. a sensing lever cooperating with said counting cam means as to count the successive character positions and a shift command member cooperating with said sensing levers as to cause said shift means to be operated after said predetermined number of signs has been counted so that the head is caused to alternate one of said two zones with the other of said two zones before said selector means is operated to select the particular character for the next one of said character positions.  
  4. A device according to claim 1 wherein said character positions are successive positions of a printing line and a predetermined number of said signs are printed before the printing of the digits of said amounts. said selecting means comprising a cyclically operable shaft and said programming mechanism comprising a selec tion sensor adapted to count cycles of operation of said selector for operating said shift means and a shift sensor adapted to sense the operation of said shift means for operating said selector.  
  5. A device according to claim 1, wherein said spac ing means comprise a motive shaft and means connecting said shaft with said type head for moving said type head with respect to said platen. and wherein said programming mechanism comprises a shift clutch having a shift driven part connected to said shift means. a shift driving part connectable with said shift driving part for imparting drive to said shift means. a selection clutch having a selection driven part connected to said selector means. a selection driving part connectable with said selector driven part for imparting drive to said selector. and a power shaft for powering said shift driving part and said selection driving part. synchronizing means being provided in said shift clutch and in said selector clutch for angularly displacing said selection driven part with a predetermined phase relative to said shift driven part.  
  6. A device according to claim 5, wherein said shift clutch and said selection clutch include corresponding clutch dogs. said shift driven part and said selector driven part including corresponding guide means for carrying said clutch dogs. said synchronizing means comprising a common cylindrical member carried by said power shaft and having a first axial portion forming said shift driving part of said shift clutch and a second axial portion forming said selection driving part of said selection clutch, each one of said first and second axial portion being provided with entraining openings so arranged around the corresponding peripheries of said axial portions and adapted to be engaged by said corresponding clutch dogs as to establish said predetermined phase.  
  7. A device according to claim 5 wherein said shift clutch includes a shift command member movably supported by said shift driver part. between a rest position holding said shift driven part disconnected from said shift driving part and a released position holding said shift driven part connected with said shift driven part and further comprising an actuatable start electromagnet. a control member ofsaid shift clutch connected to said electromagnet for being moved between a first position wherein said control member arrests said shift command member in said rest position and a second position wherein said control member respectively releases said shift command member. a programming cam carried by said shift driven part and a shift sensor responsive to the rotation of said programming cam for actuating said selection clutch.  
  8.111 a serial printing device for a calculating machine adapted to print numerical amounts as a result of an operation and a predetermined quantity of signs indicating the nature of said operation and/or said amounts comprising a record supporting platen; a type head having two separate zones carrying respectively digits for printing said numerical amounts and symbols for printing said signs. a rotatable motive shaft; shift means including a shift driving part connected to said motive shaft. a shift driven part. shift connecting means connecting said shift driven part with said type head for causing said type head to prearrange either of said two zones for printing and a shift command member movably supported by said shift driven part between rest positions holding said shift driven part disconnected from said shift driving part and released positions holding said shift driven part connected with said shift driving part; setting elements means permutable for representing a code combination of one character corresponding of both said digits and said symbols; selecting means including a selector driving part connected to said motive shaft, a selector driven part. a selector command member movably supported by said selector shift driven part between a rest location holding said driven part disengaged from said driving part and a released location holding said driven part connected to said driving part and a decoding mechanism controlled by said setting elements and interconnecting said selector driven part with said type head for causing said type head to select. for printing. said character corresponding to said code combination in said one prearranged of said two zones: and spacing means for effecting relative character-spacing movement between said type head and said record supporting platen. the combination comprising:  
 a first control member actuatable between an inoperative position wherein arrests said shift command member in one of said rest positions. and an operative position wherein releases said shift command member in one of said released positions,  
 a programme cam positioned by said shift driven part;  
 a shift sensor cooperating with said cam for controlling said selector command member. as to start a printing cycle ofthe character to be printed in correspondence of the prearrangement of said two zones;  
 a selection cam positioned by said selection driven part;  
 a selection sensor cooperating with said selection cam, said selection sensor being normally disposed in the path of said shift command member as to interfere with said shift command member and arrest said command member in another of said rest positions wherein said type head prearranges for printing the zone corresponding to said symbols. said selection cam causing said selection sensor to be shifted out of the path of said shift command memher so that said shift driven part is reengagcd to said shift driving part after printing cycles corre sponding to said quantity of signs; second control member actuatable for arresting said shift command member in a further ofsaid rest positions wherein said type head prearranges for printing the zone corresponding to said digits; and  
 means responsive to a last digit of said numerical amounts for moving said selector command member in said rest position, for arresting said printing cycles.  
  9. A device according to claim 8, further including a start electromagnet connected to said control member and actuatable for moving said shift control member. a control cam positioned by said shift driven part and an intermediate member connecting said control cam with said shift command member as to maintain said control member temporarily in the path of said shift command member independently of said start electromagnet and of said selection cam, so as to start at least one complete of said printing cycles of symbols and digits independently of the control of said start electromagnet.  
  It). A device according to claim 8, wherein said motive shaft is driven by an electric motor. further comprising a switch for arresting said electric motor. said switch being actuated by said start electromagnet. and being kept closed under the control of said shift driven part so as to keep said shift and selection driving parts in rotation independently of said start electromagnet until a started printing cycle is completed.  
  H. A device according to claim 8, wherein said type head is mounted on a carriage movable transversely with respect to said platen and said spacing means are operatively connected with said selection driven part, for moving said carriage during each one of said printing cycles. further comprising a stop element interfering with the movement of said carriage with respect to said platen. said stop element causing said shift command member to be positioned in one of said rest position so that the reengagement of said shift clutch for a new printing cycle is prevented until the return of said type head to a rest position with respect to said platen.  
  12. A device according to claim 8, wherein said type head is mounted on a carriage movable transversely with respect to said platen, and said spacing means include a rack parallel to said platen. and a worm rotatably supported by said carriage. said rack being adapted to be engaged by said worm for advancing said carriage in correspondence of the rotation of said worm, further comprising a feed cam carried by said shift driven part for disengaging said rack from said worm, a shaft parallel to said platen and rotated by said selection driven part. said worm being fast in rotation with said shaft and axially slidable thereon and a return spring for shifting said carriage toward a rest position. so that said feed cam disengages said rack from said worm at the end of the printing of a line of print.  
  13. A device according to claim 8, wherein said setting elements means comprise a plurality of actuating elements, urged by springs, further comprising a plurality of electromagnets provided with actuatable cores, adapted to retain selectively said actuating elements. a store on which are stored coded signals corresponding to said one character, a follow-up element for bringing cyclically said actuating elements into contact with said cores, a synchronizing element for retrieving fresh data from said store at the end of each selection cycle. said follow-up element being positioned by said selection driven part and a follow-up cam positioned by said shift driven part further controlling said follow-up cam as to cause said actuating elements to be kept into contact with said cores at the end of each of said printing cyclcs.  
  14. A device according to claim 13, further comprising striking means actuatable for causing said type head to strike against said platen to print the selected character. a sensing element cooperating with said actuating elements, as to sense said actuating elements and means controlled by said sensing element to prevent the actuation of said striking means in the event of a predetermined code combination of said actuating elements.  
  15. A device according to claim 8, wherein said shift connecting means comprise a differential gear including an output gear connected to said type head. a first input connected to said shift driven part, and a second input connected to said decoding mechanism.  
  l6. A device according to claim 8. wherein said type head comprises a cylindrical sleeve having a substantially vertical axis and wherein said device further comprises a transverse support parallel to said platen. a carriage slidable on said transverse support and mounting said sleeve for rotation about said vertical axis. means connecting said spacing means with said carriage for moving said type head transversely to said platen, a toothed cylinder rotationally positioned by said decoding mechanism. said toothed cylinder being parallel to said transverse support having teeth parallel to said platen and extending over the entire transverse range of movement of said head. at least one gear rotatably supported by said carriage and engaging with said toothed cylinder, and intermediate gear means connecting for rotation said gear with said sleeve.  
  17. A device according to claim 16, further comprising means for turning said carriage on said transverse support to bring a selected character into engagement with said platen for printing. and a ring gear fixed to said type head sleeve. said gear including a face having lateral teeth arranged thereon to mesh with said ring gear. and the engagement of said teeth with said toothed wheel being also partially retained during the turning of said carriage for printing the character.  
 18. A serial printing device for an electronic calculating machine comprising a platen;  
 a type head including a two separate zones. at first of said zones carrying a group of digits and a second of said zones carrying a group of symbols;  
 spacing means for transversely moving said type head with respect to said platen. as to cause said head to print. in a single row numerical amounts constituted by said digits and. before said numerical amounts. a predetermined number of symbols indi eating the nature of said amounts;  
 :1 shift clutch having a motive shaft. a shift driven and a shift command member carried by said shift driven part of said shift clutch. said shift command member describing a circular path as a result of the rotation of said shift driven path;  
 transmission means connecting said shift driven part to said type head for causing said head to prearrange for printing said first and said second of said zones. said shift command member being adapted. when arrested. to disengage said shift driven part from said shift motive part and to hold said driven part in the reached position. said shift command member being adapted. when released. to engage said shift driven part with said motive part. so that said type head prearranges for printing either of said zones;  
 at first control member actuatable between a rest position. wherein said control member interferes with the path of said shift command member for arresting it in a first position. and an operative position wherein said control member releases said shift command member;  
 an electronic control unit including storing means for storing said digits and said symbols as single characters having a code combinations of signals. and electromagnet means actuatable for starting a printing cycle of said row. said electromagnet means actuating said control member in said operative position;  
 a selector connected to said storing means and to said type head for selecting a particular character corresponding to said code combinations of signals in each of said zones;  
 a shift sensor for operating said selector:  
 programme cam means positioned by said shift driven part of said shift clutch and cooperating with said shift sensor. said programme cam means having a first portion positioning said shift sensor for operating said selector after a presetting rota tion of said shift driven part.  
 a selector sensor movable into the path of said shift command member. for arresting said shift command member in a second position such that said type head prearranges said second zone;  
 counting means responsive to said predetermined number of selected symbols for moving said selector sensor out of the path of said command member as to cause said shift clutch to be reengaged independently from said first control member.  
 and a second control member also actuated by said electromagnet means and movable in the path of said shift command member for arresting said shift command member in a third position such that said type head prearranges for printing said first zone. said programme cam means having a second portion for the printing of the digits of said amounts. and said electromagnet means releasing said second control means upon selection of a last digit of said amounts. so that said programme cam means cause said shift sensor to arrest said selector until said last digit of said amounts has been selected.  
  19. A device according to claim 18. wherein said type head includes a rotatable cylindrical support. said zones including two diametrically opposed sectors of said support and wherein said selector. for selecting said digits and said symbols. rotates said support about opposite directions starting from corresponding rest positions of said type head. and wherein said rest positions of the head are such that said digits and said symbols of said zones are off-centre with respect to the platen. said shift driven part of said shift clutch centering said digits and said symbols of said zones when said shift command member is arrested in said second position and in said third position.  
  20. A device according to claim 18. wherein said head comprises a cylindrical sleeve. said zones including two diametrically opposed surface sectors of said sleeve. and wherein said shift means further comprises a differential gear including an output gear connected for rotation to said type head. a first input of said differential being connected to said shift driven part. and a second input of said differential being connected to said selector.  
  21. A serial printing device for accounting and calculating machine comprising a type head including a plurality of characters selectable for printing and a selector for selecting said character. said selector comprising at least one prearranging setting element associated with a group of said plurality of characters; a selection element; support means for movably supporting said selection element in a first and in a second direction. said selection element carrying at least one prearranging cam; first moving means for moving said prearrang ing setting element between a un-set position far from said prearranging cam and a set position interfering with said prearranging cam; second moving means for moving cyclically said selection element in said first direction as a result of which said at least one prearranging cam co-operates with said prearranging setting element in said set position for shifting said selection element in said second direction by a predetermined stroke; positioning means supported adjacently said selection element associated with said plurality of characters; a groups of positioning cams carried by said selection element. one of said cams being adapted to cooperate with said positioning means. when said selection element is shifted by said stroke in said second direction. to move further said selection element by variable steps in said second direction; and transmission means connecting said selection element with said type head as to position said head in response to said vari able steps and thereby select one character of said group of characters of said type head associated to said set prearranging setting element and to said positioning cam.  
  22. A device according to claim 21. wherein said positioning means comprise a series of two positioning setting element associated with two of said plurality of characters of said head which may co-operate with two corresponding of said group of positioning cams. further comprising means for individually positioning each of said setting elements as to co-operate with said positioning cams of the said group.  
  23. A device according to claim 2|, wherein said selection element comprises a drum. said supporting means comprising a shaft on which said drum is axially slidable along said second direction and angularly fixed thereon, said second means driving said shaft by a cyclic rotation in said second direction. further comprising a centering member for co-operating with said drum to bring said drum hack to a rest position after said variable steps in said second direction. another prearranging cam also carried by said drum as to form a pair of prearranging cams together said at least one prearranging cam; another prearranging setting element associated with said one prearranging setting element as to form a pair of prearranging setting elements, said pair of elements being connected to said first moving means in such manner that to the un-set position of one there corresponds the set position of the other and vice versa. each of said pair of elements being adapted to co-operate with a corresponding prearranging cam of said pair of prearranging cams so as to shift said drum axially from the rest position in one direction or in the opposite direction.  
  24. A device according to claim 23, wherein said positioning cams of said group define grooves substantially helicoidal and arranged in contiguous pairs. the grooves of each pair being inclined in opposite directions with respect to the shaft supporting said drum, each of said positioning setting elements comprising a pin associated with a corresponding pair of said grooves to co-operate with one or the other groove of said pair. depending on the direction of movement occasioned by one of said pair of prearranging setting elements.  
  25. A device according to claim 22, further including interlocking levers associated to said positioning setting elements. pivot means for pivoting said levers adjacently said positioning elements, each of said locking levers including a pair of arms, one of said arms being disposed in the path of at least one associated setting element. so that each of said levers is rotated into a locking position for the other setting elements when the associated setting element is positioned. the arms of said levers co-opcrating mutually, so that the rotation of one of said levers into the locking position rotates the adjacent levers in corresponding locking positions.