| 摘要 |
PROBLEM TO BE SOLVED: To enable one person to easily put even an object which has small focus variation in focus without the need to carrying a middle-sized monitor for focus state confirmation in an installation site of a monitor camera etc. SOLUTION: A peak detecting and holding circuit 20 detects and holds a peak value in focusing, and a voltage-controlled amplifier has its gain controlled so as to output a maximum voltage with the peak value. A focus control signal amplified by the voltage-controlled amplifier is supplied to an LED 10 through a changeover switch 8 and an LED driver 9. The focus control signal has a low voltage when a lens is not in focus, increases in voltage as the lens is being put in focus, and has the maximum voltage when the lens is put in focus. When a monitor camera installing operator manually rotates the focus ring of the lens 1 to adjust the focus, the LED illuminates dark when the lens is not in focus, illuminates brighter as the lens is being in put in focus, and illuminates at a maximum when the lens is put in focus. COPYRIGHT: (C)2008,JPO&INPIT
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