Patent GB-1468282-A (GB)
Title: Electromagnetically controlled film transport device
IPC: G03B1/22
Filed: 1974-08-16
Abstract: 1468282 Film transport mechanism NIPPON KOGAKU KK 16 Aug 1974 [18 Aug 1973 24 Aug 1973 (2)] 36274/74 Heading G2E A film transport mechanism comprises a film transport member including a claw and reciprocable in a film transporting direction, a second reciprocable member, and electromagnetic means for selectively transmitting reciprocation of the second member to the first so as to move it into and out of a film-engaging position in synchronism with its reciprocation in the film transport direction. As shown, an eccentric cam 3, a face cam 4, and a shutter 2 are all mounted on a common shaft 1 driven by a motor M. The film transport member 6 has a claw 6a at one end which engages with the film perforations, and has at the other end a soft iron piece 6b. The member 6 can slide and pivot on a stationary shaft 5, and engages with the eccentric cam 3, so that as the latter rotates, the claw 6a is caused to execute an up-and-down  reciprocating movement in the direction of film transport. The second reciprocal member is a lever 7 which is also pivotable on shaft 5. A spring 9 biases lever 7 so that a contact 7a thereon engages against the cam face of cam 4. A plate spring 10 biases the iron piece 6b away from an electromagnet 8 mounted on lever 7. When magnet 8 is energized, iron piece 6b is attracted thereto, against the action of spring 10, so that claw 6a is urged into engagement with the film perforations. It moves into and out of such engagement according to the rotation of the face cam 4, which has a recessed portion and a protruding portion. When contact 7a engages in the recessed portion Fig. 6 member 6 pivots so that claw 6a engages in a film perforation. Thus the combined effect of cams 3 and 4 causes a combined movement of the claw into and out of the perforation and a transport movement, the so-called "rectangular" movement of the claw. The shift between the positions of Figs. 5 and 6 will continue as long as switch Si is maintained closed, so energizing the magnet 8. If contact 7a is initially engaged in the recess of face cam 4 Fig. 7 (not shown), the magnet is too far away from the iron piece 6b to attract it even when energized, since it cannot overcome the holding force of spring 10. After the face cam 4 has rotated sufficiently, however, to bring its protruded portion into engagement with contact 7a, lever 7 is pivoted so as to bring the magnet close enough for it to be effective when energized Fig. 4 (not shown). Thus at whatever time switch Si is closed, film transport will be initiated only at a predetermined position, without occurrence of halfframe feeding or the claw biting into an unperforated part of the film. A phase switch 13 is adapted to be closed only when the claw has entered a perforation, and once it is closed the power supply to the magnet is not cut off, even if switch Si is opened, until the face cam has rotated sufficiently to open the phase switch. Thus the claw will not be retracted from a perforation during a film transport movement even if switch Si is opened. A controlling circuit is described with reference to Figs. (not shown) 8 and 15. The modification of Fig. 10 (not shown) has an additional drive means so that the film may be transported in the reverse direction.