| 摘要 |
PROBLEM TO BE SOLVED: To enhance reception characteristics, e.g. S/N, detection sensitivity and the like when a flicker optical signal from a transmitter is received by a plurality of pixels on a light receiving face by making the optical signal pass through an optical device. SOLUTION: An optical signal from a transmitter 5 passes through a diaphragm 12 and a lens 13 and impinges on an image sensor 15. The received signal is stored in a memory 20 and variations of all pixels are monitored by means of a microprocessor 21. Based on data stored in the memory 20, the microprocessor 21 makes a decision whether no signal is present, a signal is outputted or saturation has occurred. The number of pixels obtaining a signal output is counted and a decision is made that a lens position is optimal. The optimal position is shifted from a focus so that the optical signal is received by a plurality of pixels. COPYRIGHT: (C)2004,JPO
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