| 摘要 |
<p>PURPOSE:To prevent malfunction due to noise from being generated with a simple constitution, by setting the time constant of a time constant circuit and a reference voltage for voltage detection specifically and prohibiting the generation of a detecting output by the ON and OFF of a transistor in a short time due to a reproduced amplifier output. CONSTITUTION:The transistor 104 is turned ON by a reproduced output from a recording part via an amplifier circuit 102, and is turned OFF by the reproduced output from a unrecorded part, and while it is turned ON, the charge/discharge of a capacitor in the time constant circuit where the time constant of a resistor 106 and the capacitor 105 is set at a prescribed time constant is performed. By the prescribed time constant, the detecting voltage to a voltage detection circuit 117 where the reference voltage for voltage detection is set specifically by voltage-dividing resistors 112 and 111 is prevented from being increased over the reference voltage by one or two times of the ON/OFF of the transistor 104 in a short time, and the generation of the detecting output from the circuit 117 is prohibited. And only after the OFF state of the transistor 104 being continued for a period corresponding to the time constant, the detecting output of the unrecorded part is outputted from the circuit 117, and the transistor 113 is turned ON, and a control circuit 115 is operated, thereby, it is possible to prevent the malfunction due to the noise from being generated with the simple constitution.</p> |
