Patent GB-854973-A (GB)
Title: Improvements in or relating to cinematographic films and apparatus
IPC: G03B21/40
Filed: 1957-04-10
Abstract: 854,973. Kinematograph apparatus. KARAVIAS, A. N. April 10, 1957 [April 12, 1956; April 28, 1956; May 29, 1956; July 21, 1956; Nov. 22, 1956; Jan. 10, 1957; Jan. 31, 1957], No. 11756/57. Class 97(1) and 98(1) In a camera or projector two series of film frames are exposed or projected, the frames in any sequence being in the two series alternately, each frame being faded into the next by progressive masking across the frames, each series of frames being advanced while a frame of the other is being projected. In the camera shown in Fig. 1 the light beam from the objective O is split by a block YH, YI containing a partially reflecting surface and falls on films in gates ZH, ZI from magazines BH, BI or two parts of a loop of film from a single magazine. Transversely moving shutters EH, EI are operated by cams NH, NI to mask the gates alternately. The transverse movement of the shutters results in different exposures of different parts of the film frames. These differences are equalised by grey prisms built into the beam splitting block or graduated grey filters or by a graduated reflecting layer in the beam splitter. The two series of frames thus obtained are printed by the apparatus shown in Fig. 3. They are projected from gates ZHA, ZIA, using a light source AA, a beam splitting block YHA, YIA and an objective OA. Shutters EHA, EIA mask the gates alternately and the beam splitting block includes grey compensating prisms. Successive frames, taken alternately from the two series may be printed on to a film for projection in a normal projector. Since the camera frame frequency is less than normal, each frame may be printed twice or may be printed once by itself and then in superposition with its successor. Preferably however the frames are printed as two separate series on a film TP, the two series being relatively displaced along the film and relativly inverted for projection from separate objectives 01, 02 of a special projector (Fig. 6). For this purpose the beam from the objective OA (Fig. 3) is divided by a block YHB, YIB between gates XHB, XIB through which the film TP is fed successively and at which it is advanced alternately while covered by a reciprocating shutter EIB. The gates are covered by further grey compensating prisms. The arrangement shown in Fig. 6 may be constructed as a separate projector or as an attachment for an existing projector from which it derives its drive and projection beam. It contains a reciprocating reflector which diverts the projection beam to the two gates alternately. The mechanism for feeding the film at the two gates alternately is shown in Fig. 10. A pair of cams T rotate on a common shaft and one of them reciprocates a frame PK vertically on guides X. This frame carries rollers PP at its corners engaging members PB1, PB2 forming part of a frame PTO. The latter is carried on pivots acted on by springs PZT in slotted mounts OO. The members PB1, PB2 are shaped so that the frame PTO oscillates about the pivots for each revolution of the cam T. This oscillation brings the feed claws P1, P2 into operative engagement with the film alternately in the vicinity of the objectives 01, 02. The feed movements of the claws are produced by the second cam T, disposed similarly to the first, reciprocating a frame POI on the frame PTO. Gear wheels PN are carried on the frame POI and engage racks on the frame PTO and others on slidable members PO carrying the claws P1, P2, which thus reciprocate through twice the distance moved by the frame POI. The claws P1, P2 are longitudinally adjustable on the members PO, for framing purposes, by cams PE1, PE2 which reciprocate in the feed direction along guides PH1, PH2 but which may be adjusted -laterally by rotating these guides by handles PA1, PA2. These handles may be locked by pawls PX1, PX2.