Printer having a control circuit section of cassette type
BACKGROUND OF THE INVENTION 
     The present invention relates to a printer equipped with a control circuit section of cassette type which is detachably mounted in the printer. 
     Conventionally, a printer of a type having a control circuit which is adapted to be connected to an external controller such as a host computer, for control of various operating sections of the printer such as a printing mechanism and a printing sheet feeding mechanism, has been known. In the conventional printer of this kind, the control circuit of the printer is connected to the external controller by the use of flexible cord means having opposite ends each fixedly connected with one half portion of an associated connector, and the other half portion of one of the connectors at the side of the printer is securedly mounted on the rear wall of the printer, so as to connect the cord means with the printer at the rear side of the same printer. Further, in view of restrictions in design, the printer has been generally so constructed as to be fed with the printing sheet at the rear side of the printer. Accordingly, in the conventional printer, an annoying operation at the rear side of the printer remote from a user is required for connection and disconnection of the connector, and further, the cord and the thus fed sheet can interfere with each other, and therefore the sheet can be caught, broken or wrinkled, resulting in prevention of smooth supply of the sheet. 
     Furthermore, in the conventional printer, since the operating sections and the control circuit are disposed on substantially the same level in the direction of the printer, there occur various disadvantages. For instance, the printer becomes large in size, and complicated long wiring is required for connection between the control circuit and various component parts of the operating sections such as a printing head driving motor, a sheet feeding motor, various sensors, etc., to increase an amount of work in wiring. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a printer which is capable of effecting smooth sheet feed operation, and easily performing replacement and maintenance of a control circuit device determining an operation mode in which the printer is driven, which mode includes an interface condition with an external controller, and a type of pattern character to be printed, etc. 
     It is a further object of the present invention to provide a printer which is compact, and simple in wiring, and ensures reductions in number of component parts and an amount of work for assembly. 
     It is a still further object of the present invention to provide a printer having an improved external appearance. 
     According to the present invention, there is provided a printer having operating sections including a printing mechanism and a sheet feeding mechanism drivingly controlled by a control circuit device which is adapted to be connected to an external controller through cord means. 
     The printer comprises a cassette type control circuit section which forms a controlling part of the control circuit device, and is provided at its outer end portion with one half portion of a connector, which is adapted to be connected with the other half portion of the connector connected to an associated one end of the cord means. Arranged in an internal space of the printer is a receiving section for accommodating therein the cassette type control circuit section. The receiving section has an insert port which opens into one side of the printer different from a side thereof along which a printing sheet is fed to the sheet feeding mechanism of the printer. The cassette type control circuit section is detachably mounted in the receiving section of the printer through the insert port of the receiving section. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic perspective view showing a printer according to an embodiment of the present invention; 
     FIG. 2 is a schematic plan view of the interior of the printer of FIG. 1; 
     FIG. 3 is a front view, partially in cross-section, taken along line III--III of FIG. 2; 
     FIG. 4 is a fragmentary schematic perspective view showing an essential part of the printer of FIG. 1 wherein a cassette type control circuit section is pulled out from the printer; 
     FIG. 5 is a fragmentary schematic longitudinal section view showing a manner of mounting and demounting the cassette type control circuit section; 
     FIG. 6 is an enlarged fragmentary perspective view showing a connection between a control circuit device and a flat cable of FIG. 2; and 
     FIG. 7 is a schematic block circuit diagram of the cassette type control circuit section. 
    
    
     DETAILED DESCRIPTION 
     With reference to the accompanying drawings, an embodiment of the present invention will be explained. 
     FIGS. 1 through 6 show a printer according to an embodiment of the present invention. In FIGS. 1 to 3, the printer 101 comprises operating sections (to be described later) and a control circuit device (to be described later) which is adapted to receive control signals from an external controller such as a host computer 102 for processing these signals, so that the operating sections are drivingly controlled to effect printing onto a printing sheet 106. 
     The operating sections mainly comprise a printing mechanism and a sheet feeding mechanism, more particularly, a platen 1 adapted to be rotatively driven by a sheet feed motor 5, and a printing head 2 supported by a carriage 3 which is in turn supported by a guide rod 4 and slidable therealong, these elements 1 to 5 being supported by a first frame 6 which extends horizontally of the printer 101 in an internal space of the printer. Fixed between the first frame 6 and a left side wall of a second frame 9 extending in parallel with the frame 6 is a motor support plate 11 on which a printing head driving motor 12 and a train of reduction gears 13 operatively coupled to an output shaft of the motor 12 are mounted, so that the printing head 2 supported by the carriage 3 is reciprocated by the motor 12 through the reduction gears 13 and a traction wire (not shown) connected to the carriage 3. Further, a power switch 14 and various switches 15 including a function key are mounted on a left side wall and a front wall of the second frame 9, respectively. A paper end switch 16 is fixed on the first frame 6 at its location behind the platen 1, this frame 6 being formed with an aperture 6c at a location opposite a position which is assumed by a detecting lever 34 secured to a lower face of the carriage 3 when the printing head 2 is in a home position. Furthermore, a home position sensor 35 is fixed to a printed circuit board 7a of an auxiliary circuit section 7 (to be described in detail later) of the control circuit device in alignment with the aperture 6c. 
     The control circuit device is disposed at a location below the first frame 6 within the internal space of the printer 101, and comprises a control circuit section 8 which is disposed in a receiving section 104 defined at a right half portion of the second frame 9, and the auxiliary circuit section 7 which is secured to a left half portion of the frame 9. The circuit sections 7 and 8 are disconnectably connected with each other through male and female half portions 10a, 10b of a connector 10, the respective connector portions being secured to opposite end faces of these sections, respectively. 
     More specifically, the control circuit section 8 of the control circuit device is arranged to receive control signals from the host computer 102 for information processing to determine an interface condition with the computer and a type of character to be printed. This section 8 comprises, for instance, a central processor unit 81, ROMs 82, 83 for storing a control program and for generating character patterns, a buffer RAM 84, input/output ports 85, 86, as shown in FIG. 7. The circuit section 8 is constructed in the form of a cassette and so adapted that the whole arrangement thereof is integrally mounted in the receiving section 104 and integrally removed therefrom. Namely, as shown in FIG. 4, the receiving section 104 has an insert port 104a which opens into a side surface 101a of the printer 101, so that the cassette type control circuit section 8 is slidably inserted into and pulled out from the receiving section 104 through the insert port 104a thereof in the direction of the arrows A, B, with a rail-slot mechanism (not shown) formed in opposite faces of the sections 8, 104, for instance. Further, the control circuit section 8 has an outer end face 8b having a projection lower end 8c which is brought into urged contact with an outer side edge of a bottom wall of the printer 101 when the same section 8 is set in position in the receiving section 104, so that the outer end face 8b cooperates with the side face 101a of the printer 101 to form a continuous plane or exterior, as shown in FIG. 5. A dip switch 8d for setting various printing conditions is mounted on the cassette type control circuit section 8, and the first frame 6 is formed with an aperture 6a at a location corresponding to the dip switch 8d. The auxiliary circuit section 7 fixed to the second frame 9 has the above-mentioned printed circuit board 7a and connectors 20 to 23 mounted thereon, the connectors being connected to the sheet feed motor 5, the printing head driving motor 12, the switches 15, and the paper end switch 16 through wires 24 to 27, respectively. The section 7 further includes driving circuits (not shown) interposed between the connector 10 and the connectors 20 to 23 for driving the printing head 2 and the motors 5, 12, and an electric supply (not shown) connected to the driving circuits, etc., the driving circuits and the electric supply being mounted on the board 7a. 
     In FIG. 1, reference numeral 105 denotes a flexible cord for connecting the cassette type control circuit section 8 with the host computer 102. One half portion or female portion 105a of the connector is fixedly connected to an end of the cord 105 at the side of the printer 101, whereas the other half portion or male portion 8a of the same connector, which is adapted to be disconnectably connected to the female connector portion 105a, is secured to an outer end portion of the circuit section 8. 
     In FIGS. 2 and 6, reference numeral 30 denotes a flat cable for electrically connecting the printing head 2 with the auxiliary circuit section 7, the cable 30 extending from the head 2 in a horizontal direction and being bent at right angles at an end portion or a bent portion 30a on the control circuit section side and then extending in a vertical direction toward the circuit section 7. The first frame 6 is formed with an aperture 6b in alignment with a cable fixture 31 to which the bent portion 30a of the cable 30 is fastened, and a connector 32 fixed to an upper portion of the auxiliary circuit section 7 and electrically connected thereto, and a cable guide 33 fixed to this connector are disposed in alignment with aperture 6b, so that one end of the cable 30 on the auxiliary circuit section side is inserted through the aperture 6b and connected to the connector 32 and hence to the auxiliary circuit section 7. 
     The operation of the printer 101 with the above-mentioned arrangement will be now explained. 
     Assuming that the cassette type control circuit section 8 has been set in position in the receiving section 104 of the printer 101. First, a user connects the connector portion 105a of the cord 105 which is connected to the host computer 102, with the connector portion 8a of the control circuit section 8. This connecting operation can be easily carried out at the lateral side of the printer as compared with that in a conventional printer of the type wherein such operation should be performed at the remote rear side of the printer. 
     Next, upon actuation of the printer 101 and the external controller 102, control signals are supplied from the external controller 102 to the cassette type control circuit section 8 in which information processing is carried out in a known manner, and a resultant output is supplied therefrom to the printing head 2 and the motors 5, 12 through the connectors 21, 22, 33 of the auxiliary circuit section 7 connected to the former section 8 via the connector 10, so as to operate these elements 2, 5 and 12 to effect printing onto the sheet 106. At that time, the cord 105 connected to the lateral side of the printer 101 never interferes with the sheet 106 which is fed along the rear side of the printer. 
     When the user wishes to remove the cassette type control circuit section 8 from the printer for maintenance thereof or for change of character pattern and/or interface, after removing the cord 105 from the section 8, he grips the outer wall of the control circuit section 8 to pull same outward, so that the connector portion 10b on the control circuit section side is disconnected from the associated stationary connector portion 10a. As a result, the whole arrangement of the control circuit section 8 is fully slidably pulled out from the receiving section 104 of the printer through the insert port 104a thereof, with the help of the rail-slot mechanism formed in the sections 8, 104. Thereafter, upon insertion of the control circuit section 8 inspected or repaired, or a new circuit section 8 having different character pattern and interface, the thus inserted control circuit section 8 is placed in position in the receiving section 104, with the connector portions 10a, 10b connected to each other, and the lower end 8c of the outer end face 8b of the same section 8 abutted to the associated outer side edge of the bottom wall of the printer 101. As a result, the outer end face 8b of the section 8 is positioned in flush with the outer end face 101a of the printer to form a continuous exterior to provide the printer with a qualified external appearance. The mounting/dismounting of the cassette type control circuit section 8 can be easily carried out without interference with the printing sheet 106. 
     The present invention provides various advantages as shown below: 
     (i) Since the cord means for connecting the cassette type control circuit section with the external controller is connected to the side of the printer different from the side along which the printer sheet is supplied, the sheet and the cord means never interfere with each other, to permit the sheet to be fed to the printer smoothly. 
     (ii) Since the control part of the control circuit device which determines the types of character pattern and interface is arranged in the form of a cassette, the control part of the device can be maintained, inspected or repaired easily, and the mode in which the printer operates, i.e., the manner of interfacing between the printer and the external controller and the patterns of characters to be printed, for instance, can be easily set and arbitrarily changed. This makes it possible to test the printers performance with a special means such as a control circuit section only for test use prior to forwarding the printer, use of the printer in combination with selective external controllers operable in different interface conditions, and printing with arbitrary characters including various kinds of language. 
     (iii) Since the operating sections of the printer including a printing and sheet feeding mechanism and the control circuit device are disposed at different vertical positions in the printer, the printer can be reduced in size as compared with a conventional printer of a type where these elements are disposed at the same vertical level in the printer, and wiring for electrical connection between the device and the operating sections can be simplified and shortened, resulting in reductions in number of component parts of the printer and an amount of work for assemblage of the printer. For instance, the flat cable and the home position switch can be connected directly to the printed circuit board and thus wiring for these parts can be omitted. Further, shortened wiring makes it possible to reduce noise in operation of the printer. 
     (iv) Since the cassette type control circuit section is arranged so that, when the same section is mounted in position in the printer, the outer end face thereof cooperates with the associated side face of the printer to form a continuous plane or exterior, the printer is improved in external appearance.