| 摘要 |
PURPOSE:To simplify a scanner constitution and to make it small-size by providing a motor control means which detects intervals, at which a laser beam is made incident on a beam detector, to control the rotation number of a motor driving a polygonal mirror to a fixed value. CONSTITUTION:A laser beam L outputted from a semiconductor laser 1 is reflected on a polygonal mirror 103 rotated and driven by a scanner motor 2 and is focused on a photosensitive body 107 through image forming lenses 104 and 105 and a glass window 108. The beam L is emitted for a prescribed time before the output of a picture signal and is led to a photodiode 3 through a reflecting mirror 109 and a glass fiber cable 110. The diode 3 is turned on thereby, and a synchronizing signal (g) is generated from a horizontal synchronizing signal generating circuit 4, and a switch circuit 5 is turned on to send the one-line components of a picture signal fv, and the laser 1 is modulated. Further, the signal (g) is inputted to a motor control means 7 to control the rotation of the motor 2. Thus, the scanner constitution is simplified to make it small-size.
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