| 摘要 |
PROBLEM TO BE SOLVED: To attain the high speed and the high resolution of a device with inexpensive constitution by setting a light beams performing a scanning later reaches the same position as that of the main scanning direction of a light beams performing a scanning in advance. SOLUTION: When laser light beams RA, RB from two pieces of semiconductor lasers arranged at one side out of a scan area are made incident on the deflection surface of a polygon mirror 34 with desired angles and an angle formed by the laser light beams RA, RB made incident on the deflection surface of the polygon mirror from respective semiconductor lasers with each other is defined asθL, this angleθL is set so that the rotational angle differenceθP of the polygon mirror at the time when the scanning beam of one side and the scanning beam of other side reach the same position of the main scanning direction, that is,θB-θA becomes 360 deg./(NP×NL), where NP is the number of surfaces of the polygon mirror and NL is the number of semiconductors. |
