| 摘要 |
PURPOSE: To make the size of an optical detector and a deflector required for scanning a printing area of the surface of a photorecepter drum small by making the positions of plural beams on the deflector almost aligned. CONSTITUTION: This plural-beam scanner is constituted of a plural-beam emission means 1, an optical path change means 2, the deflector 3, a scanning lens 6 and the photorecepter drum 7. In such a case, the focal lengths of a collimator lens 22, a first ralay lens 23 and a second relay lens 24 are respectively defined as fCL, fRL1 and fRL2 . Then, when the gap between a semiconductor laser array 21 and the lens 22 is set to be fCL, a the between the lenses 22 and 23 is set to be fRL1 , the gap between the lenses 23 and 24 is set to be fRL1 +fRL2 and the gap between the lens 24 and the deflector 3 is set to be fRL2 , both of the first beam 11 and the second beam 12 are advanced in parallel with an optical axis of the lens between the lenses 23 and 24 and the positions thereof are aligned on the deflector 3. |
