| 摘要 |
PURPOSE:To detect an abnormality in its early stage by discriminating a scan abnormality of an optical system based on information from a motor inversion instructing means for instructing an inversion of a rotating direction of a motor for scanning the optical system, a motor rotational quantity detecting means, and a motor rotating direction detecting means. CONSTITUTION:A motor rotating direction instructing signal 1' changes a potential level to a low level from a high level and instructs an inversion of a rotating direction of a motor at the time point when a photosensor 8 has run by a prescribed distance after the time point when it has detected an actuator 7 installed to optical system. a motor rotating direction signal 2' shows that the system is in the course of scan running, and that it is in the course of return running or stops, in case of a high level, and in case of a low level, respectively. It is discriminated that the system is normal in case when the motor rotating direction signal 2' is a low level at the time point when a prescribed number of pulses has been counted, and it is abnormal when said signal is a high level and in a scan state. It is discriminated at the time point when several output pulse of an encoder of a short period have been counted, therefore, the abnormality can be detected in a very early stage, and subsequently, it is possible to cope with it with a time to spare. |
