| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent an excess current due to a runaway of an APC, that is, to prevent a laser diode from breaking by a simple arrangement in which two switching current sources for the laser diode are provided, one is made to be a fixed current source and the other is made to be a current source to be adjusted by the APC. <P>SOLUTION: An image formation device which scans modulated laser beams on the basis of image information has the laser diode, a photodiode for receiving a part of laser beams and outputting a monitor current, a means for converting the monitor current to a voltage, a reference voltage generating means for generating a reference voltage, a comparison means for comparing the voltage obtained by converting the monitor current outputted from a light receiving element with the reference voltage outputted by the reference voltage generating means, and a laser driving control means for setting a driving current of the laser diode on the basis of the held voltage of a capacitor. A laser driving circuit in the image formation device is provided, in which the laser control means has the switching current source 1 to be switched by a fixed current, and the switching current source 2 to be switched by the driving current set by a sample hold means. The switching current sources 1 and 2 are connected to the laser diode to enable one laser driving at the same time. <P>COPYRIGHT: (C)2004,JPO |
