| 摘要 |
1276532 Photographic shutters EASTMAN KODAK CO 3 July 1969 [3 July 1968] 33563/69 Heading G2A A shutter blade S is held in a light admitting position by frictional engagement between an armature 52 and an electromagnet C. The blade is pivoted at 18 and has a return spring 20. Depression of push button 15 closes contacts 28 to switch on exposure timing circuit T and releases shutter driver 10 to impact projection 16 of shutter blade S, the projection wedging itself between the armature 52 and electromagnet C which is energized. At the end of the exposure interval determined by a timing circuit formed by photo-resistor 32 and capacitor 34, uni-junction transistor 36 fires to render SCR 44 conducting and SCR 40 non- conducting thus de-energizing electromagnet C to allow the shutter blade to regain its closed position. Stops 26, 102 are provided to limit movement of the shutter blade. Timing circuit switch 28 may alternatively be operated by movement of shutter driver 10 or by movement of blade S. |
