| 摘要 |
PROBLEM TO BE SOLVED: To securely detect an abnormality in a case where there is the abnormality in any of a plurality of laser diodes of a light source unit, without affecting a written image.SOLUTION: All of a plurality of laser diodes LD1, LD2 that a light source unit 100 has are synchronously lit only for a set period for each main scanning, optical beams L1, L2 emitted from the light source unit 100 with the synchronous lighting are received by a synchronous detection sensor 110 at a prescribed position outside an image region in the main scanning to generate an analog signal Sa, and a synchronous detection signal DTP is generated when the level exceeds a prescribed threshold level. Whether or not the synchronous detection signal DTP is generated is monitored during a period of the synchronous lighting of the laser diodes LD1, LD2 of the light source unit 100, and an abnormality of the light source unit 100 is detected when the synchronous detection signal DTP is not generated.SELECTED DRAWING: Figure 8 |
