发明授权
- 专利标题: Data imprinting lamp control circuit
- 专利标题(中): 数据压印灯控制电路
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申请号: US972128申请日: 1978-12-21
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公开(公告)号: US4235544A公开(公告)日: 1980-11-25
- 发明人: Seiji Yamada , Norio Beppu
- 申请人: Seiji Yamada , Norio Beppu
- 申请人地址: JPX Osaka
- 专利权人: Minolta Camera Kabushiki Kaisha
- 当前专利权人: Minolta Camera Kabushiki Kaisha
- 当前专利权人地址: JPX Osaka
- 优先权: JPX52-178664[U] 19771227
- 主分类号: G03B17/24
- IPC分类号: G03B17/24 ; G03B17/18
摘要:
A lamp control circuit for energizing a data imprinting lamp in response to an actuation of a flash trigger switch in a camera, for a given period so that data images illuminated by the lamp are imprinted on a film with a suitable exposure. The control circuit includes a series connection of a SCR element and a capacitor, a trigger circuit for applying a single pulse to the control terminal of the SCR element, a capacitor discharge circuit for discharging with a given time constant the capacitor that has been charged through the SCR element, and a switching circuit for energizing the lamp while the terminal voltage of the capacitor is above a threshold level. The trigger circuit has a high input impedance to protect the control circuit from high voltage which otherwise may be applied thereto through a camera synchro terminal to which the input terminal of the trigger circuit is connectable.