| 摘要 |
PURPOSE:To prevent a tape from being damaged by making beam incident on a position made eccentric to the rotary shaft of a rotating body, when the tape arranged around the rotating body is scanned with the reflected beam. CONSTITUTION:An optical system 20 is arranged in the upper direction of a rotary drum 1 and parallel beam 11 to be emitted from this optical system 20 is made incident from the upper direction of the rotary drum 1 on a prism mirror 2 in parallel and eccentrically to the rotary shaft of the rotary drum 1. Accordingly, when the reflection mirror 2 is rotated, since reflected beam 13 is rotated with the rotation of this mirror and gradually displaced in the axial direction of the rotary drum 1, a tape 12 is obliquely scanned by the reflected beam 13 even when the tape 12 is wound in parallel around without being inclined to the rotary drum 1. Thus, unnecessary force is not applied to the tape by the travel of the tape or the rotation of the rotary drum and the tape can be prevented from being damaged. |
