发明名称 |
DISTANCE DETECTOR FOR CAMERAS |
摘要 |
PURPOSE:To make the construction of the emission quantity control device of strobe simple and make the production cost thereof lower by changing the resistance value of a variable resistor constituting the distance detector in proportion to the square of the subject distance. CONSTITUTION:A mechanical movement transmitting means 6 so drives a resistor 2 that the driving length of the resistor 2 of a variable resistor 4 is proportional to the square of the distance moving length of a lens barrel 5. Hence, the variable resistor 4 inputs the output proportional to the square of the distance moving length of the lens barrel 5 to an integrating circuit 9 through a buffer 7 and a logarithmic expanding diode 8. The integrating circuit 9 integrates this input and the input expressed by the function with F value and the output thereof is inputted to a comparator 10. The comparator 10 outputs the strobe emission stop signal when the output voltage of the integrating circuit 9 has become equal to a reference voltage. In this way, the need for providing separate square circuits is eliminated and the construction of the strobe emission quantity control device may be simplified. |
申请公布号 |
JPS54148525(A) |
申请公布日期 |
1979.11.20 |
申请号 |
JP19780057386 |
申请日期 |
1978.05.15 |
申请人 |
FUJI PHOTO OPTICAL CO LTD |
发明人 |
NUMATA SABUROU |
分类号 |
G03B7/16;G01C3/00;G01C3/06;G01C3/32;G02B7/28;G03B3/00;G03B13/36 |
主分类号 |
G03B7/16 |
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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