Patent GB-1223448-A (GB)
Title: Improvements relating to flashlamp control apparatus in photographic cameras
IPC: G03B15/04
Filed: 1968-11-08
Abstract: 1,223,448. Photographic apparatus. INTERNATIONAL POLAROID CORP. Nov. 8, 1968 [Nov. 9, 1967; March 26, 1968], No. 53099/68. Heading G2A. A photographic camera has a socket for a flashcube, the indexing of the socket being carried out as a result of the running down of the shutter blades 46, 48, rotation occurring as the blade 48 closes the shutter aperture. Shutter Operation. A knob 116 is depressed causing a cam 117 to close a switch S 1  thereby energizing a timing circuit 98 and causing an electromagnetic coil 102 to hold the closing blade 48 in the position shown. Further downward movement of knob 116 results in a shaft 114 rotating a control means 14 anti-clockwise (as seen). This rotation tensions drive springs 72, 74 and frees abutment means 68 from the opening blade 46, which is thus held only by latch means 18. The control 14 is eventually rotated so far that a cam surface 64 thereof moves a projection 94 of the latch means 18 out of contact with the blade 46 which is thus free to rotate under the influence of the spring 72, the movement of the latch 18 moving a finger 184 thereof to the bottom of a slot 160 in a slide 28. The aperture unblocking movement of the blade 46 closes a switch S 3  to ignite a flashbulb and opens a switch S 2  which will result in the de-energizing of the coil 102 after a predetermined time to release the closing blade 48 to run down under the influence of the spring 74. As the blade 48 rotates, a cam 60 thereof strikes the projection 94 causing the finger 184 to depress the slide 28, the slide returning to its upper position as the cam 60 passes the projection 94. The blade 48 reaches its aperture blocking position in which it abuts the blade 46. As the knob 116 is released and raised by spring action, the control means 14 is rotated clockwise towards its initial position, causing the abutment means 68 to engage the blade 46 to rotate it clockwise into its aperture blocking position. The abutting relationship between the blades 46, 48 effects rotation of the blade 48. The switches S 1  and S 3  are opened, and the switch S 2  closed resulting in re-energization of the coil 102. The latch means 18 rotates so as to bring the finger 184 back to the upper end of the slot 160 in the slide 28. Indexing. A flash-cube 25 is inserted in a socket 24 and rotated clockwise as seen to tension a drive spring 30. A projection 150 of an escapement wheel 26 is thereby rotated through 320 degrees, the projection travelling in a slot 152 of a support plate until it abuts an end 182 of the slot. Upon release of the flash-cube, the spring 30 rotates the wheel 26 and hence the flash-cube 25 through 10 degrees anti-clockwise, so that one face of the cube faces the scene to be photographed. This rotation is limited by a tooth 148 of the escapement wheel 26 being releasably detained by a first pallet 154 of the slide 28. When the movement of aperture closing blade 48 results in the slide 28 performing a quick down and up movement, the downward movement frees pallet 154 and tooth 148 thus allowing the wheel 26 and flash-cube to rotate until a second pallet 156 engages a tooth 148. The upward movement frees the pallet 156 and tooth 148 and the wheel 26 rotates the flash-cube again until the pallet 154 engages another tooth 148; thus the flash-cube is rotated through 90 degrees as the blade 48 covers the aperture. After the fourth flash-bulb has been fired, the downward movement of the slide 28 frees the pallet 154 as before, but before the second pallet can engage a tooth, the projection 150 abuts the other end 180 of the slot 152 to terminate rotation of the wheel with the flash-cube faces all inclined to the plane of the scene to be photographed. In another embodiment Figs. 5-7 (not shown), the electromagnetic holding device is responsive to an electric circuit for controlling exposure duration in accordance with scene brightness.