JPS6030831Y2 - Tape recorder control circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape recorder equipped with a so-called standby function that, when power is supplied by a timer device at a set time, releases the standby state and puts the tape recorder into a recording or playback operating state.

The standby state of this type of tape recorder is the same as when a pause operation is performed during the recording or playback operation, and when power is supplied by the timer device, the pause state is canceled and the recording or playback operation starts. Each mechanism of the tape recorder is configured to do this.

Methods for canceling such a temporary stop state include a method using the suction force of a plunger, a method using the rotational force of an electric motor, and the like.

The method of using the suction force of a plunger has the disadvantage that it is mechanically simple but expensive, and the method of using the rotational force of an electric motor is inexpensive but has the disadvantage of being mechanically complex. are doing.

The present invention relates to a device that utilizes the rotational force of an electric motor, which is a method suitable for popular tape recorders.

In such a tape recorder, even when power is supplied and the magnetic tape begins to be driven, it takes time for the amplifier circuit to reach a steady state, resulting in a harsh sound being recorded.

The present invention aims to provide a control circuit that is improved in this respect, and will be described in detail below with reference to the illustrated embodiments.

In the figure, 1 is a power terminal to which power is supplied by a timer device (not shown), 2 is a main switch, and 3 is an amplifier circuit constituting the tape recorder.
It is activated by the power supplied through.

4 is an electric motor, and 5 is a switch that is closed when a regeneration operation or the like is performed.

Reference numeral 6 denotes a supply transistor whose collector-emitter path is connected within the power supply path 7 to the motor 4, and a bias resistor 8 is connected between its collector and base.

9 is a first control transistor whose collector is connected to the base of the supply transistor 6 and whose emitter is grounded; the base is connected to the collector of the supply transistor 6 via a resistor 10 and a capacitor 11; , and is also grounded via a resistor 12.

Reference numeral 13 denotes a second control transistor whose collector is connected to the base of the first control transistor 9 and whose emitter is grounded, and whose base is connected to the emitter of the supply transistor 6 via a resistor 14. There is.

15 is a malfunction prevention capacitor connected between the base of the second control transistor 13 and the ground so that the second control transistor 13 does not turn on immediately when the power is turned on; 16 is a diode for discharging the charge of the capacitor 11; be.

The present invention is constructed as described above, and its operation will be explained next.

In the standby state, the main switch 2 and the switch 5 are in a closed state, and power is not supplied to the power supply terminal 1.

In this state, when the set time comes, power is supplied to the power terminal 1 from the timer device.

When power is supplied to the power supply terminal 1, power is supplied to the amplifier circuit 3 via the main switch 2, and the capacitor 1
A charging current flows through 1 for a predetermined period of time.

As a result, the charging current biases the first control transistor 9 into a conductive state, causing the supply transistor 6 to become non-conductive.

After a predetermined period of time has elapsed, the charging current of the capacitor 11 disappears, and the first control transistor 9 is reversed to a non-conducting state.

As a result, the supply transistor 6 which was in a non-conductive state is reversed to a conductive state and supplies power to the motor 4.

When power is supplied to the electric motor 4, the electric motor 4 starts rotating and exits the standby state, so that the tape recorder enters a recording or reproducing operation state.

In this way, even when power is supplied to the power supply terminal 1, the motor 4 does not start rotating immediately, so the amplifier circuit 3 is in a steady state during that time, and when the motor 4 starts rotating and enters the recording or playback mode, it may cause audible noise. There are no words in which sounds are recorded or played back.

Although the standby operation is performed as described above, the operation of the second control transistor 13 will be explained next.

When the second control transistor 13 is biased by the supply transistor 6, it is reversed to a conductive state and acts to cause the first control transistor 9 to be non-conductive and thus to make the supply transistor 6 conductive. .

That is, the second control transistor 13 applies positive feedback to the supply transistor 6 to hasten the inversion operation of the supply transistor 6, which speeds up the start-up of the discharge motor 4 and causes the above-mentioned standby state. When the rotational speed is released, the rotational speed can be set to the steady rotational speed or approximately the same rotational speed.

Therefore, it is possible to solve the problem that occurs when the motor starts up slowly, that is, the problem that harsh sounds are recorded or reproduced.

As explained above, according to the present invention, even if power is supplied by the timer device, the electric power is not immediately supplied to the electric motor, but is delayed for a predetermined period of time, and then the electric power is supplied to the electric motor. When the standby state is canceled and the amplifier circuit enters the operating state, the amplifier circuit is in a steady state, and no harsh sound is recorded when recording is performed.

In addition, when the power supply to the motor is started, the supply transistor is quickly reversed to the conductive state by providing a transistor that exerts a positive feedback effect, which improves the start-up characteristics of the motor. The present invention has this advantage.

[Brief explanation of the drawing]

The illustrated circuit is one embodiment of the control circuit of the present invention. Explanation of main drawing numbers, 1...Power terminal, 4...
...Electric motor, 6... Supply transistor, 9
...First control transistor, 13...
-Second control transistor.

Claims (1)

[Scope of utility model registration request] In a tape recorder with a standby function, when power is supplied by a timer device, the rotational force of the electric motor cancels the standby state and puts the tape recorder into an operating state such as recording. a first control transistor that is conductive for a predetermined period of time when power is supplied and makes the supply transistor non-conducting; a first control transistor that is conductive due to the current supplied through the supply transistor; A control circuit for a tape recorder comprising a second control transistor operative to cause the first control transistor to become non-conductive.