Patent GB-662304-A (GB)
Title: Improvements in or relating to double exposure prevention mechanism for photographiccameras
IPC: G03B17/42
Filed: 1949-07-15
Abstract: 662,304. Photographic cameras. KODAK, Ltd. July 15, 1949 [July 30, 1948], No. 18761/49. Addition to 599,819. Class 98 (i). In the double exposure prevention mechanism described and claimed in the parent Specification, the lost-motion connection between the collar and the shutter release member is provided by a frictional member, mounted on the camera and restraining movement of the collar in both directions, and the collar and push-button of the release member are formed with portions of the same external contour so that the resilient portions of the locking levers may slide from one to the other when the pushbutton is actuated and moved into contact with the collar to displace the latter against the restraining effect of the frictional member, the push-button being movable in the reverse direction while the collar is held by the frictional member to enable the resilient portions of the levers to occupy locking positions between the push-button and the collar, thereby limiting inward movement of the release member until the cam on the film winding member is operated to displace the resilient portions to an inoperative position on the periphery of the collar. As shown in Fig. 1, levers 21, 22, pivoted at 23 on the camera wall and having resilient arms 27, 28 riveted thereto, are spring- urged at 26 into contact with a cam 20 on the film-winding shaft 11. The shutter 19 is actuated by a rod 34 having fixed thereto a push-button 31 and slidable thereon a collar 37, Fig. 2. Also fixed to rods 34 is another collar 40 which is spring-urged at 42. With the camera ready for exposure, the button 31 is pressed, moving the rod 34 to actuate the shutter and stress spring 42, a frusto-conical portion 33 on the button 31 entering a recess 56 in the collar 37 during this movement and causing the collar to move against the restraining motion of a friction washer 39, mounted in the camera wall. Prior to pressing the pushbutton 31, the resilient arms 27, 28 rested on the periphery of collar 37 so that, during movement of rod 34 and the collar 37, these arms slide on to the cylindrical surface 32 of the push-button, this surface becoming flush with the outer surface of the collar 37, as shown in Fig. 6. On releasing the button 31, the rod 34 moves outwards under the action of spring 42 and the collar 37 is held by the washer 39; the arms 27, 28 slide along the surface 32 and fall on to the conical portion 33 and then on to rod 34. On further outward movement of the rod, collar 40 engages collar 37 and moves it so that the arms 27, 28 are locked between the collar and a shoulder on the conical portion 33 of the pushbutton. With the arms 27, 28 in this position, further actuation of the shutter is prevented. On winding the film, cam 20 successively actuates the levers 21, 22 so that the arms 27, 28 move into a position of rest on the periphery of collar 37, as shown in Fig. 2, and rod 34 can now be moved to effect a further shutter operation. If a double exposure is desired, a slide 60 which is normally spring-pressed outwardly at 61 is moved by means of a handle 62 so that flanges 63, 64 on the slide engage tapered walls 65, 68 on the resilient arms 27, 28 of the levers and said levers are cammed apart to release the rod 34 without operation of the film winding member.