| 摘要 |
PURPOSE:To enable to efficiently drive a platen, by a method wherein a semi- circular disk form shutter plate is fixed to a platen shaft, a platen is rotated in a fixed direction when light from a photo sensor is not interrupted, and the platen is rotated in the reverse direction when the light is interrupted. CONSTITUTION:The semi-circular disk form shutter plate 9 is provided as one body with the shaft 3 so that the position where one-side edges 10 of the plate 9 reaches the photo sensor 5 from a fixed direction to interrupt the light corresponds to the condition wherein a position A' to be a reference of the platen 2 reaches a normal reference position A. In the condition wherein the light from the sensor 5 is not interrupted by the shutter plate 9, the platen 2 is rotated clockwise by a pulse motor 1, while in the condition wherein the light is interrupted, the platen is rotated counterclockwise. Accordingly, the platen can be located at the normal reference position by rotating it by an amount of not larger than about one half rotation, and the platen can be efficiently driven. |
