Patent GB-863432-A (GB)
IPC: G03B27/02
Filed: 1958-05-01
Abstract: 863,432. Photographic contactprinting. MINNESOTA MINING & MANUFACTURING CO. May 1, 1958 [May 1, 1957], No. 13874/58. Class 98(2) In a contact-printer, a printreceiving card is superimposed in register on a print-making card while the latter is carried on a moving conveyer and the conveyer carries the cards past a light source to effect printing. As shown, microfilm print making elements 11 mounted on cards 10 are printed on to thermally developable film 16 in similar cards 14. A stack 20 of cards 14 are fed successively by a reciprocating picker blade 781 (Fig. 3) on to a conveyer belt 132<SP>1</SP> in time with similar feeding of cards 10 from stack 19. Conveyer belt 1321 brings cards. 14 into superposition with cards 10 on a conveyer. The conveyer consists of two inwardly grooved fixed tracks and two endless moving chains 36 which are carried on sprockets so as to run alongside of the fixed tracks and which have fingers 66 extending over and between the tracks so as to drive the cards along the grooves. The edges of the cards are held together in a single groove in one grooved track and the opposite edges are separately engaged in two grooves in the other track 17. The latter track describes a circular arc about a rotating drum (Fig. 4) over windows 200 of which the cards are clamped during exposure to light source 236. The single grooved track is interrupted at the drum where spring operated platens 210 press the film bearing ends of the cards together. The platens 210 are lifted by engagement of rollers 224 with fixed cam 232. Thereafter a guide member 281 (Fig. 11) enters the gap between the separated ends of the cards and strips the lower card 10 into the hopper of stack 24. Cards 14 are collected in stack 26 after thermal development by heaters 306. The drum, chain 36 and card feeding mechanisms are driven by motor M (Fig. 9) which is energised through contacts 345, 357 when plunger 342 of relay A is held in its upper position by holding circuit including switches 350 and contacts 355, 356. The printing lamp 236 and an air blower 377 for cooling the lamp are energised on closing switches 366 and 371. The circuit of the blower 377 is completed by relay B and a holding circuit enables the blower to remain energised if the lamp circuit is interrupted. After closing switch 335, the operation of start button 337 operates relay A to start motor M and heaters 306, 306<SP>1</SP>. During the return movement of picker blade 78<SP>1</SP> micro switches 309, 309<SP>1</SP> (see also Fig. 3) remain open and cam operated switches 320, 321 remain closed. When picker blade 78<SP>1</SP> moves forward to feed a card 14 synchronised cam 324 opens switch 321 and the leading edge of card 14 engages lever 314<SP>1</SP> to close switch 309<SP>1</SP>. If, however, no card 14 is fed, switch 309<SP>1</SP> remains open and the holding circuit of relay A is broken so that motor M and heaters 306, 306<SP>1</SP> are de-energised and solenoid 257 is energised through contacts 344, 345 to bring shutter 245 (Fig. 4) between lamp 236 and windows 200 so that the cards at the windows are protected from excessive irradiation. A failure to feed a card 10 prevents closure of switch 309 when switch 320 is open and thus again breaks the holding circuit of relay A. This circuit is also broken when the hoppers of stacks 24 and 26 become full and thus operate toggle switches 316 and 316<SP>1</SP> or when stop button 351 is depressed. An additional switch (not shown) may bridge switches 350 to enable the apparatus to be tested before cards are inserted in stacks 19 and 20.