the structure of this invention includes first cartridge boxes each of which has an instrument 3 extending above the top thereof . each cartridge box also has means ( a ) for extending all reeling flexible connecting pipes 2 therein are detachably mounted inside a backrest 1 . in addition thereto second cartridge boxes 5 each contain control devices ( b ) for controlling the power , air , water and medical solution to be supplied through the connecting pipes 2 to the instruments 3 . the second cartridge boxes are likewise mounted detachably inside the backrest 1 . now , the embodiment illustrated is shown as having air - driven turbine handpieces 30 for cutting the tooth , a liquid syringe 31 for rinsing , and a vacuum syringe 32 for suction as instruments 3 as shown in fig2 . in correspondence with the instruments 3 described above , first cartridge boxes 4 and second cartridge boxes 5 ( respectively five in all ) are shown . the first cartridge boxes 4 incorporate means ( a ) for extending and reeling flexible connecting pipes 2 respectively and are provided with the instruments extending from the top of the backrest . the means ( a ) for extending and reeling the pipes 2 as shown in fig3 and 4 , comprises a pulley 7 movable along a guide rail 6 . a flexible pipe 2 is reeved through the pulley 7 which is extensible upwardly . a flat spiral spring 17 is free at the internal spiral end and is connected fixedly at the external spiral end to the pulley 7 to provide returning resilience with respect to the upward movement of the pulley . the initial end 21 of the flexible connecting pipe 2 inside the box 5 is separated by a pipe joint 9 from the main pipe side and is connected to the joint 9 . as a manner of fixing the first cartridge box 4 to the backrest 1 , the box 4 , as shown in fig2 and 7 , is brought into contact with the inside surface 10 of the backrest 1 to extend along the body axis of a patient . cartridge box 4 is fixed at the lower end portion by a metal fixture 11 to the backrest and is fixed at the top end portion by a jaw of the box 4 , see fig3 . the top end portion 13 formed at the top end portion of the box 4 is inserted and supported within the pedestal 12 , see fig2 formed inside of the shoulder of the backrest 1 . the metal fixture 11 is , as shown in fig7 a bent metal fixture and is detachable by operation of screws 14 . at both side edges of the backrest 1 , rims 15 are formed and the top surface of the pedestal 12 and the top surfaces of the rims 15 are designed to be flush with each other . a back cover ( not shown ) is put on the pedestal 12 and rims 15 so that the backrest 1 can completely conceal the first cartridge boxes 4 ( and second cartridge boxes 5 ) disposed therein from view . part of the flexible connecting pipe 2 is exposed from the top of the box 4 so as to permit the easy drawing by the dentist of the instrument as shown in fig2 and 4 . a description will now be given of the detailed structure and function of the means ( a ) for extending and reeling the pipes 2 contained in the first cartridge box 4 , see fig3 and 4 . a pulley 7 can freely move along a guide rail 6 laid in the box 4 longitudinally of the box . the flexible connecting pipe 2 has the instrument 3 mounted at the end and is reeved through the pulley 7 . the pulley 7 has one end of the connection fitting 16 secured thereto as shown in fig3 and the other end of the fitting 16 is connected to the external end of the spiral spring 17 . the flat spiral spring 17 is wound on a reel 18 journaled rotatably below the pulley 7 in the box 4 and the internal end of the spiral spring 17 is free . accordingly , the pulley 7 is normally urged downwardly in the drawing and is positioned in the lowermost position shown in fig3 and 4 . in this position the flexible connection pipe 2 is drawn downwardly in the intermediate between the fixed supporting point side , i . e ., pipe joint 9 side and the instrument 3 side on the free end side , so that the pipe 2 is reeved over the pulley without sagging but substantially in a tensioned state . accordingly , when the pipe 2 is drawn upwardly , the spring 17 imparts returning resilience to such an upward drawing force . it will be understood from the fact that the internal spiral end is not fixed to the reel 18 that such a returning force will become substantially uniform irrespective of the distance the pipe 2 being drawn out or extended . in order to stop the pulley 7 in the upper position shown in dashed lines in fig4 an engageable fitting 19 is provided in position inside the box 4 . in correspondence thereto is provided an engageable spring 20 fixed at one end by a fixture 8 to the connection fitting 16 . this engageable spring 20 is at the upper end formed with a hook 21 , while the engageable fitting 19 is formed with a groove 190 . accordingly , when the pulley 7 that reaches the position of the groove 190 being engaged by the hook 21 of the engageable spring 20 , the pulley 7 is prevented from being drawn back by the resilience of the spring 17 and is stopped in the upper position . in this latched state , the resilience of the spring 19 does not act upon the pipe 2 , and consequently the dentist does not suffer any effect from the resilience of the spring upon the operation of the instrument 3 . when it is desired to retract the pipe 2 again , it is only necessary to draw out the pipe 2 slightly and to move the pulley 7 a little upwardly . then , the hook 21 moves away from the groove 190 and thereafter the pulley 7 would be drawn downwardly along the rail 6 by the resilience of the spring 17 . also , since the structure of the paying - out and reeling means is well - known in japanese utility model application no . 137 , 093 / 73 ( japanese utility model publication for public inspection no . 83 , 887 / 75 ), a further description thereof is omitted . next , the second cartridge box 5 contains therein a control device ( b ), as shown in fig5 and 6 , namely , all the necessary control devices for satisfying the required conditions on the instruments , such as a valve 22 for supply , suspension and switching of air for driving an air turbine , a means 23 for giving an electric signal for sending a switching signal , on - and - off valves for air , water , and medical solution to syringes ( not shown ), a means for starting and bringing the turbine to a sudden stop , etc . the manner of mounting this box 5 to the backrest is the same as that of the first box 4 , and the fixture 11 and other suitable fixing means are used . both boxes 4 and 5 , as shown in fig2 are preferably disposed in an adjacent relation with each other ( a bilateral relation herein ), or are disposed in such an overlying relation as the box 5 lies immediately below the box 4 although not shown . the disposition of the boxes in the manner mentioned above is desirable in that it reduces the space occupied to a minimum . there is interposed a pipe joint 9 between the boxes 4 and 5 , and the initial end of the connection pipe 2 in the box 5 and the final end of the pipe 2 in the box 4 are detachably connected to the joint 9 . also , it is understood that the trunk side of the pipe 2 in the box 5 is connected the supply sources of air , water , etc ., to a suction compressor or the like . this invention is of the construction described above , and can be said to provide a dental chair assembly which meets the needs of the time in that the assembly is detachably provided inside the backrest thereof with first cartridge boxes 4 , each of the boxes contains therein an instrument , a flexible connection pipe 2 connected to the instrument , and a means ( a ) for paying out and reeling the pipe 2 freely from the top of the shoulder part of the backrest 1 and in that the assembly is also likewise detachably provided inside the backrest with second cartridge boxes 5 , each of the boxes 5 being associated with each of the first boxes 4 and having a control device ( b ) disposed therein , and in consequence after the user purchased the assembly , when he desired to make some addition or change of position of the instruments 3 according to his own way of use , method of treatment or liking , he can satisfy his requirements by replacing each of the first boxes 4 with a different one or attaching new purchased parts to the box 4 without the help of the maker , thus can greatly save the time and cost necessary therefore and can also obtain the same benefit by replacing the boxes 4 and 5 with new ones when the assembly is in part out of order . it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings , since the invention is capable of other embodiments and of being practiced or carried out in various ways . also , it is to be understood that the phraseology or terminology employed therein is for the purpose of description and not of limitation .
the disclosure relates to a dental treatment chair assembly wherein the assembly is detachably positioned inside the backrest of the chair and comprises a number of cartridge boxes ; each of the boxes contains therein an instrument and an extensible connecting pipe and means for assisting manual extension and reeling - in of the pipes from the top of the shoulder part of the backrest , whereby a dentist can arrange the type , number and position of dental instruments in compliance with his convenience and desire by arranging the cartridge boxes . any instrument can be removed and repaired by withdrawing the cartridge box that contains the defective instrument .