| 摘要 |
PURPOSE:To decrease the accleration value of a tape in accordance with the tape winding diameter and to drop the necessary power supply voltage, by suppressing the motor driving current to a constant level in case the tape winding diameter of a take-up reel exceeds the prescribed value when a reel motor is accelerated. CONSTITUTION:A tape 10 is consequtively taken up to a machine reel 6 from a film reel 1 via a magnetic head 11 and an idler 4. Both a file reel tachometer 2 and a machine reel tachometer 7 produce a pulse respectively with their one turn. While a tape tachometer 5 produces several hundreds of pusles with one turn of the idler 4, and the rotating direction of the idler 4 can be detected owing to the double phase. In this example, the accleration B is reduced to limit the motorITK to a cetain level as shown by the dotted lines in the diagram when the tape winding diameter DTK of the take-up reel exceeds the prescribed value. Thus the driving capacity of a motor driving circuit can be reduced. This reduces the size of the motor driving circuit and also lowers the cost. |
