Patent GB-683763-A (GB)
Title: Improvements in or relating to plate or film holders for photographic cameras
IPC: G03B17/26
Filed: 1948-11-30
Abstract: 683,763. Photographic film and plate holders. KALART CO., Inc. Nov. 30, 1948 [Dec. 10, 1947], No. 31030/48. Class 98 (i). A photographic plate or film holder comprises in combination a casing having septum and slide guide tracks, a septum adapted to receive a sensitized layer and slidable in the septum guide tracks, at least one slide for covering and uncovering a sensitized layer received by the septum and slidable in the slide guide tracks, locking means comprising a yieldable locking member disposed within the casing adjacent to the slide guide tracks, the slide having a notch in a side edge positioned to register with the locking member upon complete insertion of the slide while in a predetermined slide face position, and release means for the locking member comprising a control element movably mounted in the casing, one end of the control element protruding into the septum guide tracks, the control element being arranged to be engaged by the septum, upon insertion thereof, and to be moved into a position in which the locking member coacting with the control element engages the notch, the locking member returning to its disengaged position in response to a release of the control element upon withdrawal of the septum. The holder may also have locking means including a movable looking member supported on one side of the casing and arranged to extend into the path of the slide in the slide guide tracks and to be engaged by one of the slide corners for blocking, after withdrawal of the slide in a predetermined slide face position, a re-insertion of the slide in the same slide face position and to be moved by the opposite corner of the slide out of the path of the slide when the latter is re-inserted in reversed slide face position. Other locking means may be provided to prevent withdrawal of the slide before it is placed in the camera, to prevent withdrawal of the septum, and to lock the holder in position on the camera back. As shown, Fig. 1, a double plate holder comprises a casing 24 closed by slides 28. The longer sides of the casing carry central bars 38, Fig. 7, grooved at 39 to guide a plate-carrying septum 27. Frames 34 lie on either' side of bars 38 and are recessed at 31, 32, 33 (Fig. 1). The slides 28 are inserted between the frames 34 and casing 24, and their end portions 30 are marked differently on opposite sides to indicate whether the plate covered thereby is exposed or not, The holder may be constructed to hold one plate only if desired. To ensure that the slide is reversed after an exposure, the recess 33 contains a lever 40, Fig. 5, freely pivoted at 41. When the holder is loaded in the dark room it is turned upside-down so that lever 40 lies out of the path of the slide when it is inserted. When the holder is placed in the camera the slide withdrawn, and the exposure made, the nose 42 of lever 40 falls into the path of the slide, and prevents re-insertion by engaging a sharp corner of the slide unless the slide is first turned over, when the rounded corner 46 of the slide 28 engages and raises the nose 42, allowing the slide to be pushed home. If, after withdrawing the slide, no exposure is made, the camera is turned over so that the slide can be re-inserted without reversal. To prevent accidental withdrawal of the slide, a spring 50, Fig. 7, is fastened at 51 to bar 38 and lies in recess 32. A nose 52 of the spring is urged into the path of the slide, but may be retracted therefrom by pressure on a button 54 slidable in a hole 53 in casing 24. When loading, button 54 is pressed and slide 28 inserted. On release of the button, nose 52 of spring 50 engages a notch 55 in the slide, which cannot be withdrawn until the holder is inserted in the camera, when a part 21 of the camera back presses button 54 down. When the slide is re-inserted after reversal, notch 55 engages a spring similar to 50 in recess 31. This spring, however, lies out of the path of the slide unless urged therein by a button sliding in a hole in casing 24 and engaged by the septum 27. Thus, once the slide has been re-inserted it cannot be withdrawn until the septum has, been withdrawn, normally in the dark-room. A light trap consists in a tube of rubber or other resilient material covered with fabric such as velvet, extending across and closing the open end of the holder. The slides are pushed in between the fabric and casing 24.. The septum is locked in position by a U- shaped member 76, Fig. 13, straddling the centre web 77 of the septum, and sliding in a slot 82. A leaf-spring 84 urges the member to the right in Fig. 13, urging bevelled projections 83 into notches 83<SP>1</SP> in one of the bars 38 when the septum is pushed home. A pin 79 on member 76 extends through a slot 80 in a flange of the septum and carries a knurled knob 81 by which member 76 can be moved to the left to release the catch and remove the septum. Flanges 85 extending from the centre of the top of the septum to facilitate its withdrawal enter recesses 86 in the casing 24 when the septum is pushed home. Locking means are also provided to prevent removal of the holder from the camera unless the slide 28 is in position, and comprise a lever 90, Fig. 16, pivoted at 92 in a recess 91 in casing 24. The lever is biased so that when the slide is partially or wholly withdrawn a nose 95 of the lever enters a recess 96 in a part 21 of the camera body, preventing removal of the holder. When the slide is fully re-inserted, a sloping part 98 of the end 30 bears against a nose 94 on the opposite end of lever 90 to rock it and remove nose 95 from recess 96, so that the holder may be removed. With a double holder as shown in Fig. 1, two recesses 96 and levers 95 are provided on opposite sides of the holder, each slide operating one of the levers. The Specification as open to inspection under Sect. 91, also describes the application of the last-mentioned locking means to a magazine for cut film or plates, or a film pack, and to a roll film holder. In these cases, the holder has projections at the other end engaging recesses in a part of the camera, or vice versa. This subject-matter does not appear in the Specification as accepted.