| 摘要 |
PROBLEM TO BE SOLVED: To easily detect a fault in the light amount detecting side for outputting signals in accordance with the detected amount of light by detecting the amount of light emitted from a light emitting element. SOLUTION: A fault of PD72 can be detected easily with a simplified structure because the PD72 can be detected as defective when the PD72 outputs a current, and the PD72 can be detected as normal when the PD72 does out output a current under the condition that an LD30 does not emit the optical beam. Moreover, light amount detection fault of the PD72 can be compensated easily with the simplified structure because light amount detection failure of the PD72 can be compensated by compensating the reference voltage Vref to cancel a voltage Vm detected by generation of migration, when the voltage Vm in accordance with the current outputted from the PD72 is equal to the voltage Vm indicating the initial stage of generation of migration under the condition that the LD30 does not emit the optical beam. COPYRIGHT: (C)2006,JPO&NCIPI
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