| 摘要 |
<p>PURPOSE:To reduce a useless current flowing a light emitting element except the time when the rotation of a reel base is detected by detecting a rotative change point of the reel base with a control circuit and controlling a current to flow in the light emitting element. CONSTITUTION:Upon detection of a rotative change of the reel base 1, a light emitting element output terminal 9 is immediately changed from L to H by the control circuit 7 to shut off the current of flowing in the light emitting element 3. When the reel base 1 is further rotated, a detecting output terminal 9 is changed from L to H after a given period of time less than a min. time value of a detecting output to be generated at a min. value of the rotational cycle of the reel base 1, i.e. when the rotating speed of the reel base is the fastest at the time of ending a magnetic tape wound around a reel, so that the light emitting element 3 is electrified again for emission. Then, when the rotation of the reel base is stopped, the light emitting output terminal of the control circuit 7 is changed to H, so as to shut off the current of flowing in the light emitting element 3. By this method, useless electric power to be consumed in the light emitting element at the time other than the rotating detection of the reel base can be reduced.</p> |
