发明名称 |
Light quantity controller and input device |
摘要 |
A light quantity controller and an input device are disclosed. The light quantity controller comprises a light source, a photo-sensor to detect a light quantity of the light source, a signal source for generating a reference signal, a comparator for comparing the detected light amount with the reference signal, and control circuit to control a duty ratio of the energization to the light source in accordance with the compare result to maintain the light quantity of the light source at a constant level. The light quantity controller further comprises a comparator to compare the energization signal to the light source with a reference signal to detect the degradation of the light source. The input device has a key matrix including a plurality of input ports and a plurality of output ports of a control unit interconnected through switches. A signal source independent from the output ports of the key matrix is connected to at least one of the input ports through switches.
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申请公布号 |
US4467246(A) |
申请公布日期 |
1984.08.21 |
申请号 |
US19810294572 |
申请日期 |
1981.08.20 |
申请人 |
CANON KABUSHIKI KAISHA |
发明人 |
TANAKA, KANO;TAKEDA, HIROAKI |
分类号 |
G03B27/52;(IPC1-7):H05B41/29;H05B41/39 |
主分类号 |
G03B27/52 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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