JPS6034110Y2 - Tape recorder auto-stop circuit - Google Patents

Description

[Detailed description of the invention] This invention automatically turns on the power supply to the motor by detecting the presence or absence of rotation of the rotating body that rotates with the reel shaft during various operations such as playback and fast forwarding.

This invention relates to an auto-stop circuit for a tape recorder that performs OFF control.

For example, a conventional circuit of this type is constructed as shown in FIG. The switching operation of conducting and non-conducting is performed by the switching switch.

Reference numeral 2 denotes a switching thyristor which is turned on by a part of the charging current that instantaneously flows through the capacitor 4 flowing into the gate when the power switch 3, which is closed in response to various operations such as playback and fast forwarding, is closed. When turned on, the switching transistor 1 is inverted into a conductive state.

5 detects changes in the magnetic field generated by a magnet embedded in the rotating body when the rotating body rotates together with the reel shaft (not shown) during various operations such as playback and fast forwarding, and detects a change in resistance value. It is a magnetoresistive element that generates an alternating current signal as a signal, and 6 is a first control transistor that amplifies the alternating current signal from the magnetoresistive element 5.

Reference numeral 7 denotes a second control transistor which becomes conductive when the output signal from the first control transistor 6 is rectified by a diode 8.9 and then applied to the base, and remains conductive while the reel shaft is rotating. is maintained.

Reference numeral 10 denotes a third control transistor that becomes conductive when the second control transistor 7 becomes non-conductive, and the third control transistor 10 grounds the gate of the switching thyristor 2 when it is conductive. , turns off the switching thyristor 2 which is turned on.

Note that 11 is a driving transistor that cuts part of the charging current of the capacitor 4, and 12 is a diode for discharging the capacitor 4.

Therefore, in such a conventional circuit, power is supplied to the amplifier AMP, the motor M, etc. by 10 B through the closing of the power switch 3 → turning on the switching thyristor 2 → the conduction state of the switching transistor 1. When the tape reaches the end in various operating states such as fast forwarding, the output of the magnetoresistive element 5 stops due to the stoppage of rotation of the reel shaft, and the first and second control transistors 6 and 7 each become non-conductive. While inverting, the third control transistor 10
is reversed to conductive state and the switching thyristor 2 is turned off, so that the switching transistor 1
is inverted to a non-conductive state, cutting off the power supply to the amplifier AMP, motor M, etc., and performing an auto-stop operation during each operation such as playback and fast forwarding.

However, in such conventional circuits, if a pause mechanism and a remote mechanism are added and the mechanism is paused or remotely operated during playback or recording,
This pause occurs because the rotation of the reel shaft stops, causing a malfunction and causing the switching transistor 1 to become non-conductive, completely cutting off the power supply to the amplifier AMP, motor M, etc. Or, even if you cancel the remote operation and try to operate the mechanism again, you must first go through the stop operation and then perform the regeneration or recording operation again to trigger the gate of the switching thyristor 2 and make the switching transistor 1 conductive. I couldn't get it to work unless I did it.

Therefore, with such conventional circuits, it was not possible to perform the original pause or remote operation.

The present invention has been developed in view of this point, and the present invention has been developed to prevent the switching transistor 1 for power supply from becoming non-conductive due to malfunction during pause or remote operation. An example of this will be described below with reference to the drawings.

Note that the pause operation will be explained by taking as an example a so-called electrical pause, which is performed electrically by cutting off the power supply to the motor.

In addition, parts that are the same as those of the prior art are given the same drawing numbers, and detailed explanations thereof will be omitted.

That is, the circuit of the present invention has a pause switch 13 and a remote switch 1 that are opened during pause and remote operation, respectively.
4 is connected in series with the motor M, and the open end side of the motor M, which is opened by the pause switch 13 or the remote switch 14, is connected to the resistor 15 and the diode 1.
The control signal input circuit 17 is connected to the base side of the second control transistor 7 via a control signal input circuit 17 consisting of a transistor 6.

Therefore, if the pause switch 13 or the remote switch 14 is opened by pausing or performing remote operation during playback or recording, and the power supply to the motor M is cut off, the magnetic The detection signal from the resistance element 5 disappears and the first control transistor 6
is reversed to a non-conducting state, but the open end voltage (approximately equal to the power supply voltage 10B) on the open end side of the motor M is applied from the control signal input circuit 11 to the base of the second control transistor 7. Alternatively, the conductive state is maintained because it is applied as a control signal during remote operation.

Therefore, the third control transistor 7 is also maintained in a non-conducting state and does not turn off the switching thyristor 2, so that the switching transistor 1 is also maintained in a conducting state for supplying power to the motor M, amplifier AMP, etc. ing.

Therefore, when the pause or remote operation is canceled and the pause switch 13 or the remote switch 14 is closed, the motor M can be immediately rotated to resume the reproduction or recording state.

At this time, since the open end side of the motor M is grounded, the open end voltage applied as a control signal from the control signal input circuit 11 disappears, but as the reel shaft rotates, the open end voltage from the magnetic resistance element 5 is removed. Since the detection signal is applied again via the first control transistor 6, no malfunction will occur.

As described above, according to the circuit of the present invention, the presence or absence of rotation of the rotating body that rotates with the reel shaft during various operations such as playback and fast forwarding is detected and the power supply to the motor is automatically turned on.
, in a tape recorder that performs OFF control, a detection circuit that detects the presence or absence of rotation of the rotating body and outputs a detection signal, a control circuit that is controlled by the detection signal from the detection circuit, a motor, and the motor. Turn on the power supply to the motor circuit connected in series with the pause switch and the motor circuit controlled by the control circuit.

a switching circuit that turns off; and a control signal input circuit that is connected between the motor circuit and the control circuit and that detects a voltage change that occurs in the motor circuit during the pause or remote operation and applies a control signal to the control circuit. However, when the rotating body stops rotating, the control circuit is controlled by the detection signal from the detection circuit and the power supply to the motor circuit is turned off by the switching circuit. When the rotating body stops rotating, the control circuit can be controlled by the control signal from the control signal input circuit to continue supplying power to the motor circuit by the switching circuit. There is no risk of an auto-stop operation occurring, and this has extremely high practical value.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a conventional example, and FIG. 2 is a circuit diagram showing an embodiment of the present invention.

Claims (1)

[Scope of utility model registration request] In a tape recorder that detects the rotation of a rotating body that rotates together with the reel shaft during various operations such as playback and fast forwarding, and automatically controls ON and OFF of the power supply to the motor, A detection circuit that detects the presence or absence of rotation and outputs a detection signal, a control circuit that is controlled by the detection signal from the detection circuit, a motor circuit that includes a motor and a pause switch connected in series with the motor, and the control circuit. power supply to the motor circuit controlled by 4
a switching circuit that turns on and off the supply; and a control signal input circuit that is connected between the motor circuit and the control circuit and that detects a voltage change that occurs in the motor circuit during the pause operation and applies a control signal to the control circuit. When the rotating body stops rotating, the control circuit is controlled by the detection signal from the detection circuit, and the switching circuit turns off the power supply to the motor circuit.
F, when the rotating body stops rotating due to a pause operation, the control circuit is controlled by a control signal from the control signal input circuit so that the switching circuit continues to supply power to the motor circuit. Features an auto-stop circuit for tape recorders.