| 摘要 |
<p>PURPOSE:To detect assuredly the sag of a tape and stop the travelling of the tape, by providing a sensor consisting of a light emitting element and photodetector obliquely to the tape facing of the wall substance which control the range of sag of the tape rolled out by a capstan. CONSTITUTION:When the tape travels in the normal condition, the tape 11 rolled out between the capstan 16 and the pinch roller 17 is taken up smoothly around the circumference of the wound tape via the guides 14 and 15. Under these conditions, the light given from the light emitting element 25 is detected by the photodetector 26 to deliver the normal state detecting signal. In case a smooth winding is impossible for the tape, the tape 11 touches the surface of the wall substance 19. Thus the light from the element 25 is cut off, and accordingly the detecting signal is delivered from the photodetector 26 for occurrence of a sag of the tape. Based on this detecting signal, a protective action such as the stoppage of driving or the like is given.</p> |
