| 摘要 |
PURPOSE:To control the position of a CCD sensor so that it is set accurately at a bit by using a tilt control means to control the posture of the CCD sensor based on the difference of the light quanties received by the photodetecting parts. CONSTITUTION:A traveling object 8 carries a CCD sensor 5 and therefore has a tilt Q against a track T of an optical card 1. Under such conditions, the quantity of light received by a photodetecting element 13 is smaller than that of another photodetecting element 14. Thus a control means 17 drives the tilt control means 15 and 16 so as to obtain the coincidence between the quantities of light received by both elements 13 and 14. As a result, the sensor 5 can be set accurately on the track T of a bit 3.
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