| 摘要 |
PURPOSE:To obtain a stable synchronizing signal and to form an exact image by setting a grating interval of a reference grating plate in accordance with a scanning speed of a light beam. CONSTITUTION:In a light beam scanner 10 for generating a synchronizing signal L2 by using a PLL circuit from a pulse signal obtained by scanning a reference grating plate 30 by a light beam, and recording or reading an image, etc., based on this synchronizing signal L2, a grating interval in a part which does not make a contribution to recording or read of the reference grating plate is set so as to correspond to a scanning speed of the light beam. Therefore, it is suppressed effectively that a frequency range of a pulse signal obtained from the reference grating plate 30 is converted to a wide band due to a variation of a scanning speed. In such a way, the PLL circuit can generate an exact and stable synchronizing signal by an inexpensive constitution, can read exactly an image, etc., or can form an image having a high quality.
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