| 摘要 |
PURPOSE:To stably form an image all the time by actuating a focal point shifting mechanism, adjusting a focal point, modulating a light source and forming an image on a scanning surface after the focal point is adjusted. CONSTITUTION:An actuating signal is inputted to a laser driver 1 from a control part 10 to introduce a switched-on condition where a wave is generated for a prescribed length of time from the laser driver 1. A fixed laser element 2 (laser light source) is lit with constant light quantity for a prescribed period in response to the signal. A laser beam from the fixed laser element 2 is projected to scan a bar code filter 7 disposed in a position optically equivalent to a photosensitive body 908. The laser beam transmitted through the bar code filter 7 is made incident on a photodetection element 8. A laser flux L forms an image on the bar code filter 7 disposed in the position optically equivalent to the photosensitive body 908 and any changes in quantity of the transmitted beam are detected, so that the position of a collimator lens system 3 is adjusted based on the detection signal. Thereby, the image with a high density a well as a high definition can be formed. |
