Patent GB-728763-A (GB)
Title: Improvements in or relating to photographic cameras
IPC: G03B17/42
Filed: 1952-09-22
Abstract: 728,763. Photographic cameras. KOCH, C. Sept. 22, 1952 [Oct. 9, 1951], No. 23753/52. Class 98 (1). A photographic camera having a ground glass focusing screen 54, a shutter spring-urged into closed position, an adjustable mechanism for controlling exposure times, and a control lever 22 for opening the shutter independently of the exposure-controlling mechanism, is characterized by an actuating lever 31 operatively connected to the control lever 22 and to a second spring means 42 for urging the lever 31 to a position where the shutter is opened, the lever 31 being adapted to be moved manually against action of the spring means 42 to a rest position where the shutter is closed and to be retained in the rest position by a spring-loaded detent 35, there being manual release means to move the detent 35 to release lever 31 to the action of spring means 42 for opening the shutter, and transmission means 49 connected to lever 31 and to a guide for a dark slide for moving lever 31 in shutter-closing direction when the slide is inserted, the movement of the transmission means being less than is required to engage lever 31 with detent 35, so that when the slide is removed the shutter is again opened. As shown, the shutter is mounted in an aperture in a casing 10 and is surrounded by a rotatable blade control ring 8. A slide 2, actuated by a flexible release 1, has a pawl 6 pivoted thereto. A spring 3 connected between pins 4, 6a on the casing 10 and the pawl 6 respectively urges the slide 2 against pin 4 and the pawl 6 into a notch 8a in ring 8. A spring 13 urges ring 8 to its rest position with a nose 14 thereon engaging a stop 11. When release 1 is actuated, slide Z moves and pawl 6 engages notch 8a to rotate ring 8. An arm 16 carrying a roller 17 is pivoted at 15 to ring 8, and is urged by a spring 17a into a horizontal position when the ring 8 is at rest. When ring 8 rotates, roller 17 rolls on the lower faces of a rhombic island 18 mounted on the casing 10. At the end of the movement of slide 2, pawl 6 escapes from notch 8a and ring 8 returns to rest position; during the return movement roller 17 rolls on the upper faces of the island 18. Control lever 22 has a roller 23 urged by a spring 26 against lever 16, so that the movement of lever 16 rocks lever 22, which opens the shutter, and closes it when roller 17 is again clear of island 18. The exposure time may be increased by a timing mechanism (not shown) which holds the shutter open until the expiry of a time set by means of a lever 58. The shutter may also be opened by means of lever 31, pivoted to the casing 10 at 32. One arm of lever 31 is pivoted to a link 39, to which spring 26 is anchored. The other arm of lever 31 has a pin 34 normally engaged by the spring- urged detent 35, which can be moved by pressing a button 35a, releasing the lever 31 which rocks under action of the tension spring 42. The link 39 has a sloping nose 40 engaging lever 22 which is thereby rocked to open the shutter blades to enable an image to be focused on the ground glass screen 54. When lever 31 is moved up to re-engage detent 35, the shutter closes again. Because of the shape of its nose 40, link 39 moves down during the shutteropening movement until a nose 39a thereon lies in the path of a step 8c on ring 8. If, while the shutter is open, release 1 is actuated, rotation of ring 8 causes step 8c to engage nose 39a to move link 39 back so that lever 39 re-engages detent 35 and the shutter is closed. The next actuation of the release then operates the shutter for an exposure. A Bowden cable 49 is connected between the casing 10 and the camera back 56. The cable core is connected to a rod 52 connected to lever 31, so that when the lever 31 is in shutter-opening position, the end 53 of the core protrudes into the camera back. The dark slide is inserted in front of the focusing screen 54, which is thereby moved back against springs 57 to press the end 53 of the cable core, which rocks lever 31 to close the shutter. The movement is not, however, sufficient to engage pin 34 and detent 35, so that when the dark slide is withdrawn the shutter opens again. The Bowden cable may be replaced by any other coupling which allows relative movement between the casing 10 and the back 56, or by electric mechanism. A red signal flag 44 is connected to lever 22 so as to be raised when the shutter is open. The cable release, lever 31 and shutter speed lever 58 are arranged to be visible and to be actuated from both in front of and behind the camera. The shutter may be removable from the camera. Reference has been directed by the Comptroller to Specification 693,867.