Patent GB-752862-A (GB)
Title: Improvements in or relating to photographic contact printing apparatus
IPC: G03B27/06
Filed: 1954-07-09
Abstract: 752,862 Photographic contact-printing apparatus. KODAK, Ltd. July 9, 1954 [July 16, 1953], No. 20169/54. Class 98 (2). A photographic contact printer comprises a hinged platen 15, Fig. 1, movable from a normally raised position to a lowered position to hold a sheet of photographic material over a printing aperture, a reciprocable carriage 25 moved by an electric motor M (Figs. 7 and 17) between an inoperative position in which it disengages said platen and allows it to rise and an operative position in which it engages and holds said platen in its lowered position and electromechanical means for completing a printing cycle automatically. The printing cycle consists of movement of the carriage to the operative position for an exposure time selected by preset timer T followed by movement of the carriage back to the inoperative position. The electric circuit necessarily comprises a motor switch S18, a platen switch S17 in series with it, a manually-operated switch S16 in parallel with the platen switch to initiate the printing cycle, two single-pole double-throw switches S20 and S21 for reversing the motor M and a timer switch S19. As shown, switches S18, S19, S20 and S21 are mounted on a plate 81 for operation by slide-bars 93 and 97. As shown in Figs. 5 and 5A the drive linkage between the carriage and the switches comprises a driver slide-bar 86 having a driving-pin P projecting through slot 87 in plate 81 on which it is mounted for horizontal movement by studs 88 in slots 86<SP>1</SP>. Mounted for vertical movement on the driver slide-bar 86 is a release slide-bar 84 having a pin 83 which, when the driver slide-bar is moved to the right, rides up profile 85 of plate 81. The movement of the driver slide-bar is transmitted to the motor and timer switch slide-bar 97 by the co-operation of yoke 107 on bar 84 with pin 100. The reversing switch slide-bar 93 is actuated by a lost-motion coupling of pin 91 in slot 96 of bar 97. As shown in Fig. 1 the carriage 25, chain 34 for driving it and platen 15 are arranged as in Specification 648,295. A slider 162, sliding on rail 161, is provided with up-turned ends 163, 164 to engage roller 166 projecting from link 51 of chain 34 which is attached to carriage 25. The final movement of carriage 25 as it reaches either of its extreme positions is thus imparted to lever 167, the vertical arm 172 of which is attached to the end 164 of slider 162. The horizontal arm 169 of lever 167 is mounted for longitudinal movement on the reverse side of plate 81 by studs 171 in slots 170 and pin P enters hole 174 in the arm 169. In Fig. 6, the carriage is in the inoperative position and the driver slide-bar 86 and release slide-bar 84 are held to the extreme left by the lever 167, Fig. 1. In Fig. 7, the operating cycle has been initiated by momentarily closing switch S16. This energizes the motor M and, platen switch S17 is arranged so that when the platen is lowered by the initial forward movement of the carriage it is-closed, as shown. The switch positions remain as in Figs. 6 and 7 until the carriage nears the end of its forward run. It then moves the slide-bars, through slider 162 and lever 167 to the right and when it has come to rest the lamps L and timer T are working. Driver slide-bar was first picked up by yoke. 107 and as soon as it was moved to the right the roller of motor switch S18 came out of notch 101 and the motor was switched off. The momentum of the carriage then carried the bars further to the right enabling bar 97 to pick up bar 93 by pin 91 in slot 96 and carry it to the right, thus reversing the respective positions of switches S20 and S21. The starting field of the motor M is thereby reversed and the motor will now start up again in the reverse direction. Finally the roller of S19 has entered notch 95 in bar 93 and notch 99 in bar 97 so that it is closed and completes the circuit of the printing lamps L and the timer T. The off-set kink in detent spring 104 has also trapped pin 100 in yoke 104 of bar 84 as pin 83 rode up profile 85 of plate 81. When the timer times out, its internal snapaction actuates switches 76 and 75, thus switching off synchronous timer motor m and lamps Land starting motor M. As the carriage begins its return run spring 177 (Fig. 1) acting on lever 175 draws lever 167 and slider 162 back until the lever 175 abuts adjustable stop 178. Thus the driver slide-bar 86 moves to the left (in Fig. 6) and carries with it the release slide-bar 84 and the motor slide-bar 97 trapped in yoke 104. Fig. 17 shows the condition of the circuit during the return run, the roller of switch S18 having entered the notch 101 and the roller of switch S19 having left the notch 99 before the carriage disengaged from. the end 163 of the slider 162. As the carriage nears the end of its return run switch S18 is opened to switch off motor M and the momentum of the carriage acting through lever 167 carries bar 97 and, when pin 91 engages slot 96, bar 93 to the left, to return switches S20 and S21 to their original positions. The platen then rises, and may rise under the action of spring 184 acting through lever 180 and rigid link 182 alone. Solenoid 78 (Fig. 7) was de-energized when S18 was opened and the switches 76 and 75 were thereby re-set so that the circuit is as shown in Fig. 7 except that S18 is open. With the platen up the platen switch S 17 is open and the motor switch S 18 may therefore be closed without energizing the motor M. The motor switch S18 is closed under the action of lever 180 and spring 102. As the platen rises lever 180 depresses bar 84, thusfreeing pin 100 from detent spring 104. Bar 97 is then snapped to the right by spring 102 acting between -centring slide-bars 90 and 92. The slide-bars 90, 92 contact only bar 97 and are arranged so that spring 102 tends to return bar  97 to a central position when it moves either to the right or to the left. Hand-operated switch S24 allows the exposure to be immediately terminated and switches S14 and S22 enable it to be indefinitely prolonged. The lamps L may be pre-selected by switches S50.