| 摘要 |
<p>PURPOSE:To improve a measuring accuracy by detecting the position in the width direction of the tape wound on a tape drawing post with the variation in the received light quantity of a light receiving sensor and keeping the distance between the sensor and post constant. CONSTITUTION:A back tension post 5 draws a tape 27 out of a cassette 1 so as to press the nonmagnetic face of the tape 7 by the revolving centering around the shaft 31 of a post support block 32. It is then moved until abutting to a stopper 30. When it is stopped in the state of its abutment on the stopper 30, the back tension post and tape 27 wound thereon are held in a constant distance to a sensor 21. A specific light is then radiated on the post 5 with the reference traveling position of the tape 27 as the center and the reflected light is detected on a photodetector 23. Due to the reflectivity differing with a specular finishing white post and black tape 27, the tape displacement is measured as the variation in the reflection light quantities of the post face.</p> |
