| 摘要 |
PURPOSE:To perform both the constant current driving and the constant speed driving of a reel motor in good condition, by carrying out the switching according to the operation mode of a tape deck. CONSTITUTION:A bridge circuit 10 is formed by using a reel motor 1 and a driving current detecting resistance R1 for the sides respectively and inserting a reference voltage source 2 to the side which is opposed to the resistance R1. A differential amplifier 3 uses the difference of potential between the detecting terminals B and C of the circuit 10 for the differential input; and a differential amplifier 6 uses the both-end voltage of the resistance R1 for the differential input. The constant speed travelling and the high speed travelling of a tape are switched in accordance with the operation of switches 4 and 8. Then the output of the amplifier 3 or 6 is supplied to the feed terminal A of the circuit 10 via a current amplifier 5. Furthermore each constant of the circuit 10 is set so that the load characteristics of the motor 1 bring about the coincidence between the start and end points of the tape winding with a characteristic curve which keeps the constant speed for the travelling of the tape. Thus the constant speed control is performed for the motor in the high speed driving mode. |
