| 摘要 |
PURPOSE:To keep the surface potential of an exposure part of a photosensitive body constant and to obtain a stable picture by detecting the temperature of a semiconductor laser which emits a laser beam and controlling the laser output of the semiconductor laser on the basis of a temperature detection signal and a reference wavelength signal. CONSTITUTION:A temperature detecting means 23 such as a thermistor is provided at the vicinity of a semiconductor laser 18. A dip switch 30 indicates the wavelength of emitted light of the laser 18 at a prescribed temperature. The switch 30 measures temporarily the wavelength of emitted light of the laser 18, for example, at 25 deg.C room temperature and sets a reference wavelength signal X divisionally in 3 levels (a), (b), and (c) in accordance with the measured value. The reference wavelength signal X set by the switch 30 is read by a control means 25 to determine the center value of the output of the laser 18. A temperature detection signal Y detected by the means 23 is inputted to an A-D converter 24, and the value of the converted detected temperature is sent to the means 25. The means 25 controls a laser driving circuit 26 to correct the output of the laser 18. Thus, the surface potential of the exposure part of the photosensitive body is kept constant to obtain stable picture.
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