| 摘要 |
PURPOSE:To obtain a high-definition picture by providing a photodetector constituted of (n) pieces of photodetector elements juxtaposed in the vertical direction and rotary polygon mirror provided with (k) pieces of mirror surfaces respectively having different surface tilt angles. CONSTITUTION:When a rotary polygon mirror 41 having (k) pieces of mirror surfaces and another rotary polygon mirror 42 having (k-1) pieces of mirror surfaces are rotated at the same face velocity in the same direction, the combination between the upper and lower mirror surfaces gets out of position at every rotation and, as a result, different mirror surface tilt angle combinations are obtained by the number of the mirror surface combinations and vertical scanning can be performed in kX(k-1) stages. When the set number of photodetector elements 40a arranged in the vertical direction is (n), 3XkX(k-1) pieces of scanning lines are obtained. Therefore, the number of the photodetector elements can be reduced without reducing the number of the scanning lines and, at the same time, distortions produced by the visual long and short sight fields can be reduced. Thus a high-definition picture can be obtained. |
