GB757273A - Improvements in or relating to film feeding and positioning mechanism - Google Patents

Abstract

757,273. Optical projection apparatus. KODAK, Ltd. Aug. 13, 1954 [Aug. 13, 1953], No. 23577/54. Class 97 (1). In a film feed mechanism successive film areas are fed into a gate by a sprocket operated by Geneva mechanism, the striker pin member of which operates means to open the gate in advance of the feed movements and to close it after the movement has ceased. In the projector shown, the film is fed from a spool 30 downwards into the gate by a sprocket 34 rotated intermittently by a Geneva mechanism comprising the cross 40 and striker pin disc 50 rotatable by a knob 46. The gate comprises two apertured members 21, 22, carrying glass plates 26 for clamping the film, pivoted at 23 and urged together by a spring 28. Their upper parts 69 lie on either side of the flattened end 68 of the shaft 61 on which the knob 46 is mounted and by rotation of which the gate members may be separated. The disc 50 carries two striker pins, separated by 180 degrees, together with segments for locking the cross when stationary. The angular setting of the disc relatively to the flattened shaft end 68 is such that a 45 degrees rotation of the knob 46 opens the gate, a further 90 degrees feeds the film and a final 45 degrees closes the gate. The cycle then repeats. To permit initial framing of the film the cross 40 is mounted loosely on the shaft but is coupled to it by a friction disc 41 engaging a disc 42 rigid with the shaft. The sprocket is rotated by the knob 46 until a film frame is correctly positioned in the gate. A resilient brake member 73 is then depressed manually to engage the milled periphery 75 of the disc 42 while the knob 46 is rotated to a position corresponding to the start of the feed cycle. The knob 46 is in splined engagement with the shaft 61 and can be moved outwardly from the cross against a return spring within the knob. This disengages driving pins and locking segments from the cross. The knob is retained in the retracted position by latching members 83, 86 in an angular position such that the flattened shaft end 68 opens the gate. The film is then free for rewinding on to the spool 30 by the handle 33.