| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To solve the problems that, in an exposure system for an image forming device using a surface emitting laser as a light source, photocurrent is made very small due to the constraint in the optical system and that reverse-bias leakage current increases too large to neglect due to the increase of a light receiving area of a photo detector, with respect to the photocurrent at the time the laser of the photo detector is off, making the offset a trouble to control the light quantity. <P>SOLUTION: A correction circuit 15 is provided, wherein the output of an amplifier 13 at the time a light emitting device 11 is turned on is corrected with reference to an output of the amplifier 13 at the time the light emitting device 11 is turned off. Thus, even when applied, for example, to the exposure system using the surface emitting laser as a light source, correction is ensured in respect of the offset which is caused by the leakage current of the photo detector 12 due to the surface emitting laser, and the offset which is caused by the amplifier 13. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
