JPS634295Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an operation circuit for a tape recorder that can set the tape drive mechanism to a predetermined operating position by trigger operations such as playback, fast forward, and rewind.

That is, in recent years, it has become possible to set the tape drive mechanism to a predetermined operating position by trigger operations such as playback, fast forward, and rewind, by effectively utilizing the rotational driving force of the motor without using a plunger or the like. Many soft-touch operation tape recorders have been commercialized. For example, the first
As shown in the figure, a motor 2 and a preamplifier circuit 3 are connected via a trigger switch 1 that is turned ON when a trigger is operated using each operation button such as playback, fast forward, rewind, etc.
After supplying power to the bias circuit 4, etc., and setting the tape drive mechanism (not shown) to a predetermined operating position by the rotational driving force of the motor 2, the trigger switch 1 is turned OFF again. After that, power is supplied to the motor 2, preamplifier circuit 3, bias circuit 4, etc. via the main switch 5, which is closed until the tape drive mechanism is set to a predetermined operating position. . In addition, 6 is a recording/playback switch, and its movable part 6a is pressed during recording operation.
is switched to the recording terminal R side. Further, 7 is an input terminal to which an audio signal is input from a magnetic head or a tuner section, etc. The audio signal input to the input terminal 7 is amplified by a preamplifier circuit 3 and then sent to a speaker via a signal line 8. It is applied to an output amplifier circuit etc. connected as a load. As a mechanism for setting the tape drive mechanism section to a predetermined operating position by the rotational driving force of the motor 2, a toothless gear 9 as shown in FIG. 2 is generally used, and the toothless gear 9 is in a stopped state. Then, the toothless portion 9a is the drive gear 10.
Although it is in a non-meshing state with the drive gear 10 when facing the camera, it is rotated slightly (in this case, counterclockwise) by a separate trigger means during each trigger operation such as playback, fast forward, rewind, etc. When the meshing state is reached and one rotation is made, the toothless portion 9a corresponds to the non-meshing state again. That is, the tape drive mechanism section is configured to be set at a predetermined operating position by receiving the rotational driving force during one rotation of the partially toothed gear 9. It is assumed that the drive gear 10 is formed coaxially with a flywheel (not shown) to which rotational driving force is transmitted from the motor 2, for example. Then, the trigger switch 1 is turned on,
OFF control is performed by a timing cam 9b formed on the top surface of the partially toothed gear 9. In the stopped state as shown in the figure, the partially toothed gear 9 is in a non-meshing state with the drive gear 10, and the trigger switch 1 is not engaged. The actuating piece 1a is switched to the contact OFF side by contact with the timing cam 9b, and when trigger operations such as playback, fast forwarding, rewinding, etc. When the timing cam 9b is rotated, the timing cam 9b moves to the operating piece 1a.
The actuating piece 1a is switched to the contact ON side.

Therefore, the trigger switch 1 is turned on at each trigger operation, and after one rotation of the partially toothed gear 9 (that is, after the tape drive mechanism is set to a predetermined operating position), the timing cam 9b is turned to the operating position again. When it comes into contact with the portion 1a, it becomes in the OFF state.

However, in this type of tape recorder, the tape drive mechanism is set at a predetermined operating position by the rotational driving force of the partially toothed gear while it rotates once (that is, while the trigger switch is in the ON state). Because of this configuration, tape running becomes unstable during that time. That is, the time chart is shown in Fig. 3, where a indicates the switching operation of the tape drive mechanism, b indicates the ON/OFF operation of the main switch, and c indicates the ON/OFF operation of the trigger switch. During operation, an unstable tape running period T occurs in the tape drive mechanism section. If the amplifier circuit, bias oscillation circuit, etc. are in operation during such a period, for example, during playback operations, the playback signal from the magnetic head is amplified by the amplifier circuit and then emitted from the speaker via the signal line, producing unpleasant rising noise. There was a risk that the bias signal would be recorded as an audible frequency during a recording operation and would be reproduced as an unpleasant rising sound during playback. Similarly, there was a risk that an unpleasant falling sound would be produced during the stop operation.

On the other hand, the applicant filed the
No. 56-85852 (Utility Model Publication No. 57-198716) provides such an amplifier circuit with a muting circuit that bypasses its output signal, and a switching circuit that controls the operation of the muting circuit and the bias oscillation circuit. In addition, an operating circuit has already been proposed in which the switching circuit is controlled using a trigger switch, thereby eliminating unpleasant rising or falling sounds that occur when each trigger is operated.

However, in such an operation circuit, the circuit configuration is such that power is supplied to the switching circuit through the trigger switch even when the trigger switch is in the OFF state and the switching circuit is in the OFF state. When collector cut-off current or emitter cut-off current flows, so-called wasteful current consumption occurs.

The present invention has been developed in view of these points, and one embodiment thereof will be described below with reference to the drawings. Note that parts that are the same as those in the prior art will be given the same drawing numbers and their explanations will be omitted.

That is, in the figure, 11 is a control circuit, and 12 is an emitter connected to the operating piece 1a of the trigger switch 1, and its base is connected to the contact OFF side of the trigger switch 1, and is grounded via a resistor 13. A switching transistor 14 is a first muting transistor whose collector and emitter are connected between the signal line 8 and the ground, and whose base is a diode 15.
and is connected to the collector of the switching transistor 12 via a resistor 16. 17 has its collector connected to the bias oscillation circuit 4 and its emitter connected to the recording side terminal R of the recording/playback switch 6.
This is a power supply transistor that is grounded through the movable piece 6a and the movable piece 6a, and its base is connected to the actuating piece 1a side of the trigger switch 1 via a resistor 18. 19 is a second muting transistor whose collector is connected to the base of the power supply transistor 17 and whose emitter is grounded; its base is connected to the collector of the switching transistor 12 via a diode 20 and a resistor 21; has been done.

As described above, the circuit of the present invention is configured,
The operation will be explained below.

First, when the trigger switch 1 is in the OFF state, power is not supplied to the switching transistor 12 by the trigger switch 1, and the control circuit 11 is set to a completely inactive state. .

Therefore, collector cutoff current and emitter cutoff current flow through each transistor 12, 14, 19 of such control circuit 11 , and each transistor 12, 14,
There is no risk of unnecessary current consumption due to 19.

Next, for example, when a playback trigger operation is performed, the trigger switch 1 is turned on, power is supplied to the motor 2, preamplifier circuit 3, etc. via the trigger switch 1, and the tape drive mechanism section is started to switch to a predetermined operating position.
At the same time, power is supplied to the emitter of the switching transistor 12, and the switching transistor 12 becomes conductive, and due to the conduction of the switching transistor 12, the first and second muting transistors 14 and 19 also become conductive. A conductive state is established through the resistor 16 and the diode 15, and through the resistor 21 and the diode 20, respectively. Therefore, the first mutating transistor 14 bypasses the audio signal on the signal line 8, and the second muting transistor 19 bypasses the audio signal on the signal line 8.
By lowering the base potential of 7, the recording/playback switch 6
The bias oscillation circuit 4 is set to a non-operating state during a recording operation when the movable piece 6a is on the recording terminal R side.

That is, during the unstable tape running period until the tape drive mechanism is set to the playback position, the audio signal input to the input terminal 7 is amplified by the preamplifier circuit 3, and then passes through the signal line 8, causing an unpleasant rise. There is no risk of sound being emitted from the speaker. Similarly,
Since the bias oscillation circuit 4 is set to a non-operating state during the recording operation, there is no risk that the bias signal will be recorded as an audible frequency and emitted from the speaker as an unpleasant rising sound during playback.

After the tape drive mechanism is set to a predetermined playback position, the trigger switch 1 is turned on again.
It is in the OFF state, and a cut-off voltage is applied to the base of the switching transistor 12 through the main switch 5 and the trigger switch 1.
The switching transistor 12 is inverted to a non-conducting state. Therefore, the first and second muting transistors 14 and 19 are respectively inverted to a non-conducting state, the audio signal on the signal line 8 is led out to the speaker, and the bias oscillation circuit 4 is used for power supply during recording operation. transistor 1
It becomes operational through 7.

Next, when a stop trigger operation is performed in such a state, the trigger switch 1 is turned on, so that the switching transistor 12 is turned on.
becomes conductive again, and muting is applied to the signal line 8 in the same way as when triggering playback, and the bias oscillation circuit 4 is set to a non-operating state during recording.

As described above, according to the circuit of the present invention, the control circuit is controlled using the trigger switch that is turned ON when each trigger operation such as playback, fast forward, rewind, and stop is performed, and the control circuit controls the tape drive mechanism. The structure is configured so that the audio signal on the signal line is bypassed until the tape is set at a predetermined operating position, that is, during the unstable period of tape running, and the bias oscillation circuit is made inactive. The audio signal amplified by the amplifier circuit in the state is applied to the speakers etc. through the signal line, and there is no risk of unpleasant rising or falling sounds being emitted from the speakers, and the bias signal is audible during recording operations. There is no risk of it being recorded as a frequency.

Furthermore, according to the present invention, the trigger switch
When the control circuit is stopped in the OFF state, the trigger switch sets the control circuit to a completely inactive state in which no current is consumed by each transistor, so there is no wasted current consumption by each transistor that makes up the control circuit. It is of high practical value, especially in efficiently utilizing limited power sources such as batteries.

[Brief explanation of the drawing]

Fig. 1 is a conventional circuit diagram, Fig. 2 is a schematic configuration diagram of a mechanism for setting the tape drive mechanism to a predetermined operating position, Fig. 3 is a time chart thereof, and Fig. 4 is an embodiment of the present invention. FIG. 1...Trigger switch, 2...Motor, 4
...Bias oscillation circuit, 8...Signal line, 11 ...
...control circuit.

Claims (1)

[Scope of utility model registration request] When operating triggers such as play, fast forward, rewind, etc.
Power is supplied to the motor etc. through the trigger switch that is turned ON, and after the tape drive mechanism is set to a predetermined operating position by the rotational driving force of the motor, the trigger switch is turned OFF again. In the tape recorder, when the trigger switch is in the OFF state, power is not supplied when the tape recorder is stopped, and the trigger switch is in the ON state.A switching transistor that is supplied with power and becomes conductive for the first time when the trigger switch is operated; a first muting transistor that becomes conductive when the switching transistor is conductive and bypasses the audio signal on the signal line; and a second muting transistor that becomes conductive when the switching transistor is conductive and cuts off power supply to the bias oscillation circuit. A control circuit consisting of a transistor is provided, and the control circuit is set to a completely inactive state in which no current is consumed by each transistor in the trigger switch when the trigger switch is in an OFF state. However, when the trigger switch is in the ON state and the trigger is operated, the first and second tape drive mechanisms are set in the operating state until the tape drive mechanism section is set to a predetermined operating position, that is, while the trigger switch is in the ON state, the first and second switches are set in the operating state. An operating circuit for a tape recorder, characterized in that a control operation is performed by a muting transistor.