Patent GB-1487892-A (GB)
Title: Film cartridge and cartridge-loaded motion picture camera
IPC: G03B19/18
Filed: 1975-01-30
Abstract: 1487892 Film drive for cinematograph cameras EASTMAN KODAK CO 30 Jan 1975 [4 Feb 1974 10 Jan 1975] 4111/75 Heading G2E In a cinematograph camera adapted to receive a film cartridge with a film-driving means, and wherein the film cartridge may be one of two types requiring different film-driving forces, the camera has mechanism for driving the film in the cartridge through a torque-limited clutch which can be adjusted to transmit the driving force required by the film cartridge in use. As shown in Fig. 1, a film cassette 30, to be located in use in a chamber 12 formed in the wall of a motion picture camera 10, has a film take-up core 32. The core has a recess 32d with a central hub 32c from which lugs 32a, 32b extend across recess 32d. A take-up drive mechanism 40 has two interfitting sectors 46, 44, sector 44 having a lug 42 which, when the cassette is in position for use, is in driving engagement with one of the lugs 32a, 32b. As shown in Fig. 2, a drive motor actuates a gear 60. An annular plate 64 of friction material is secured in gear 60 and is engaged by the end 72a of a cylindrical member 72 telescoped into a housing 74 mounted on the sector 46 of the drive mechanism. The length of the housing 74 is such that it projects into the recess 32d of a cassette. With one type of cassette the housing 74 engages the bottom of the recess and is displaced to slide axially relative to its mounting on sector 46. The displacement of the housing by the cassette is calculated to increase the pressure by spring 76 to extent which appropriately increases the torque transmissible by the clutch. A cassette of a type with a recess 32d which is so deep that the housing 74 is undisturbed when the cassette is inserted Fig. 3 (not shown) is driven with a smaller maximum torque transmissible by the clutch as the spring 76 is at its full extent. An anti-backup mechanism may be used. In a second embodiment, the maximum torque transmissible to a cassette is determined by the modulus of a spring contained in the cassette. As seen in Fig. 8, a core 130 to be driven is rotatably mounted on a spindle 164 mounted on the wall 166 of the cartridge. The core has two tracks with sprocket teeth 132 for engaging the film perforations, and the generally cylindrical wall 174 which, with a radial wall 172, forms a well 176. A coil spring 188 is placed in the wall and compressed by a plate 178 which is perforated so that a member 170, extending axially from the bottom of the well, passes through it. The member 170, which may be of deformable plastics material, is flattened after assembly to hold the parts in position. Plate 178 has four upstanding lugs 182. The camera has a slipping clutch drive assembly, Fig. 6, consisting of a motor driven gear-wheel 140; an undulating washer 144 with a lug 145 engaging a recess 147 in gear-wheel 140; a fibre washer 146; a force plate assembly 148 consisting of a disc 158 with a cutout for a portion 152 carrying a driving lug 156; and a retaining ring 150. When the cassette is in position the core and the driving means engage to compress the undulating washer 144 of the slipping clutch to an extent depending on the characteristics of spring 188, in the cassette.