Patent GB-1469977-A (GB)
Title: Film cassette conditioning mechanism
IPC: G03B17/26
Filed: 1974-06-17
Abstract: 1469977 Film cassettes POLAROID CORP 17 June 1974 [28 June 1973] 26660/74 Heading B8M [Also in Division G2]  A cassette having a spring-loaded film pressure plate, and an opening through which light can be admitted into the cassette, has actuator means which can control the position of the pressure plate, and control the amount of light being admitted, the two controls being actuated together for correlated operation. The cassette shown is of the self-processing type which is inserted into a camera for initially exposing the film, then transferred into a processor/projector unit, in which it is processed in situ, and then can be projected for viewing. During projection it is necessary for the film to be closely and accurately held in the film gate by a pressure plate, so that each film frame is properly imaged for viewing. Also, a light beam has to pass through the cassette for this purpose. During the processing stage, or during rewinding, the film has to be run from one spool to the other, and it is desirable that the pressure of the pressure plate be relaxed, so that the film may run freely, and at high speed if necessary. Also, during processing it is necessary to prevent any light from reaching the film emulsion. To this end, control of the position of the pressure plate and of light-excluding means are achieved by a single actuator mechanism. As shown, the cassette 10 is received in a slot 20 between walls 21, 24 of a housing 22 mounted in the processor/ projector unit. The lower part of the cassette has a prism 32 which reflects the projection light beam 42 entering through a light inlet 30 through the film 12 in the gate area 18, and out through the gate aperture 36 and an outlet port 34 in the floor 40 of the housing 22. Two light blocking or blinder units are provided, a plate 44, slidably mounted for blocking the inlet 30, and a pivotally mounted plate 82 for blocking the outlet 34. The pressure plate 38 is structurally integral with the cassette, and is normally biased by a spring 100 so as to hold the film in the projection plane. The film gate platform assembly 114 is fixed to the housing floor 40, as are two guide posts 118, 120 against which the film is held as it passes through the gate by two fingers 121, 122 on a laterally displaceable yoke 124. The blinder 44 is connected by link 76 to an arm (78, Fig. 1 not shown), which is actuated by a timing cam assembly, which controls the movement of the blinder 44. When development is taking place, the blinder plates 44 and 82 are in the Fig. 5 position, in which no light can enter through apertures 28 and 36. At the same time a slidable control frame 106, Fig. 9, is drawn to the left, and a pair of lifter members 142 and 144 mounted in platform assembly 114 lift the pressure plate 38 to a retracted position, and also retract the fingers 121, 122 so that they are no longer in engagement with the film, which can thus pass through the gate area without unnecessary frictional drag. For the projection mode, blinder 44 is drawn to the right by the timing cam assembly on link 76, against the action of its restoring spring 70. This aligns an aperture 58 in blinder 44 with aperture 28. At the same time a projection 52 on blinder 44, which has previously engaged against a lug 94 on blinder 82, thus pivoting it into the "closed" position of Fig. 5, is disengaged therefrom, and another projection 54 on the blinder engages lug 94 and so pivots it into the "open" position (Fig. 6 not shown). Also at the same time frame 106 is caused to slide to the right, so that yoke 124 is freed to be urged by spring 132 towards the gate, thus bringing fingers 121, 122 into guiding engagement with the film. Also at the same time, the lifter members 124, 144 disengage from the pressure plate, so allowing it to confine and locate the film correctly in the projection plane.