| 摘要 |
PROBLEM TO BE SOLVED: To compensate for variations in characteristics without needing adjustment of a reference signal. SOLUTION: The detector 100 comprises a plurality of sensor circuits U generating detections signals Sd of levels according to the distances from the surface of an object; a section circuit 20 selectively outputting each detection signal Se from each sensor circuit U; a D/A conversion circuit 32 generating reference signal Sref of a level according to a reference value R stored in a register 31; and a comparator 35 generating detection data D according to the magnitude of level of the detection signal outputted from each sensor circuit U and the reference signal Srf generated by the D/A conversion circuit 32. A CPU 41 calculates a spacial frequency by a predetermined operation to a plurality of detection data generated by the comparator 35, and updates the reference value R of the register 31 based on this spacial frequency F. COPYRIGHT: (C)2007,JPO&INPIT
|
