| 摘要 |
PROBLEM TO BE SOLVED: To reduce adverse influences of a dark current of a light detector when scanning light beams are to be detected. SOLUTION: According to a method and an apparatus for detecting scanning light beams used for printing onto a medium, a detector 32 is set in a scanning route and a signal is sent to a first amplifier 42. A feedback loop 51 for maintaining the first amplifier 42 to a predetermined level is provided for the first amplifier 42 by setting a second amplifier 52. A time delay circuit 60 is set between an output of the second amplifier 52 and the first amplifier 42. A signal from the second amplifier 52 to a plus input terminal 56 of the first amplifier 42 is delayed. An output of the first amplifier 42 is accordingly forcibly set to be a predetermined value when the detector 32 does not generate a signal.
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