JPH0548293Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) This invention relates to a tape recorder that records and plays back information signals such as audio signals.
The present invention relates to a tape recorder that can prevent recording signals from leaking from a recording system to a reproduction system by performing a muting operation on the electronic volume.

(Prior Art) In tape recorders capable of recording and reproducing audio signals, a common circuit is often used for the reproduction signal system and the recording signal system.

In such a case, when using one signal system circuit without switching the switch circuit, use a muting circuit in the other signal system to cut off the passing signal and avoid duplication of signal circuits. I try to avoid it as much as possible.

On the other hand, setting the optimum recording level during recording is done using a volume (variable resistor), but an electronic volume may be used instead of the volume. This electronic volume is inserted into the signal system, and a control DC voltage is applied from the outside to the control terminal of this electronic volume, and this voltage value is changed to optimally set the level of the signal supplied to the recording head. There is.

FIG. 2 shows a conventional circuit showing an example of this. In the figure, 1 is a playback head, 2 is a playback amplifier (amplification circuit), 3 is a noise reduction circuit, and 4 is an audio signal output terminal, and these components constitute the playback signal system of the tape recorder. ing.

In the circuit constituting this reproduction signal system, a reproduction modulated audio signal reproduced from a magnetic tape (not shown) by a reproduction head 1 is amplified to a predetermined level by a reproduction amplifier 2, and at the same time, the frequency is corrected. and is supplied to the noise reduction circuit 3.

This noise reduction circuit 3 is supplied with a playback mode signal E2, and this noise reduction circuit 3 compresses the playback audio signal in the opposite manner to that during recording, and outputs the playback audio signal to the output terminal 4. .

On the other hand, the audio signal input terminal 5, the resistor R1,
An electronic volume 6, a recording amplifier 7, and a recording head 8 constitute a recording signal system circuit of the tape recorder.

The audio signal supplied to this input terminal 5 is supplied to an electronic volume 6 via a resistor R1, the level is set by the electronic volume 6, and the recording signal is expanded by the noise reduction circuit 3 to be recorded. It is amplified to a predetermined level by amplifier 7, and at the same time,
The signal is frequency corrected and supplied to the recording head 8.

Further, 9 is a mutating NPN transistor, which is connected between the input of the electronic volume 6 and the ground (earth). During playback, the controlled DC voltage supplied to the base of the transistor 9 via the resistor R2 causes the electronic The volume 6 and the ground are electrically connected (turned on).

Therefore, the recording input signal supplied to the input terminal 5 is not supplied to the electronic volume 6, and therefore, no output signal is output to the output of the electronic volume 6, so that the recording input signal is not leaked to the playback signal system. There's no way to go.

Furthermore, 10 is an electronic volume control voltage generator, which generates a control voltage for setting the electronic volume 6 to an optimum recording level.

(Problems that the invention aims to solve) In conventional tape recorders, the need to provide a dedicated muting circuit in the recording signal system made the circuit system complex, making it impossible to completely prevent the recording input signal from leaking into the playback signal system. In addition, this increased the amount of adjustment work required and the number of parts required, resulting in increased costs.

(Means for Solving the Problems) The present invention was made in view of the above-mentioned drawbacks of the conventional technology, and includes a reproduction signal system having a noise reduction circuit that is also used during recording, and a recording level setting in the middle of the reproduction signal system. In a tape recorder equipped with a recording signal system having an electronic volume interposed therebetween and a voltage generation circuit that generates a control DC voltage to control the electronic volume, the recording signal of the electronic volume reaches a minimum value during playback. An object of the present invention is to provide a tape recorder configured to supply a controlled DC voltage from the voltage generating circuit described above.

(Embodiment) FIG. 1 shows an embodiment of the tape recorder of the present invention. In FIG. 2, the same components are given the same numbers and their explanations will be omitted.

First, the case of recording will be described below with reference to FIG.

A control DC voltage V1 generated from the control voltage generator 10 is supplied to the control terminal of the electronic volume 6 in response to the recording mode signal E1 supplied to the noise reduction circuit 3 and the control terminal of the control voltage generator 10. Ru.

By this control DC voltage V1, the recording head 8
Then, the level of the electronic volume 6 is set so that the recording signal level supplied via the recording reduction circuit 3 and the recording amplifier 7 becomes the optimum recording level.

Next, the case of reproduction will be described below with reference to the same figure.

The control voltage V2 supplied from the control signal generator 10 to the control terminal of the electronic volume 6 in response to the playback mode signal E2 is set such that the recording input signal supplied to the input terminal 5 has a minimum value. The electronic volume 6 is controlled so that no signal is output to its output.

As a result, the recording signal is not supplied to the input of the noise reduction circuit 3 which is also used during recording and constitutes the reproduction signal system, and leakage of the recording signal can therefore be prevented.

Various circuit configurations can be considered for the configuration of the terminal volume 6, but when it is configured using transistors, for example, the collector of an NPN transistor is connected to the input signal side, and its emitter is connected to the output side. A control terminal is connected to the base, and the control voltage generator 10 supplies control DC voltages V1 and V2 to the control terminal during recording and playback, respectively, to control the impedance between the input and output of the electronic volume 6. , it should be small to almost zero (0) when recording, and almost infinite (∞) when playing back.
It is also possible to have a circuit configuration that controls the output so that the following happens.

In addition, in one embodiment of the present invention shown in FIG.
Although the reproduction head 1 and the recording head 8 have been described as dedicated heads, the present invention is not limited to this, and it goes without saying that the heads may also be used for both recording and reproduction.

(Effects) The tape recorder of the present invention has a reproduction signal system having a noise reduction circuit that is also used during recording, and an electronic volume for setting the recording level interposed in the middle of the system, and a control DC voltage that controls the electronic volume. In a tape recorder equipped with a recording signal system having a voltage generating circuit, the electronic volume is configured to supply a controlled DC voltage from the voltage generating circuit so that the recording signal reaches a minimum value during playback. Therefore, there is no need to use a special transistor for mutating, and the electronic volume control function is used to set the level so that the recording signal level supplied to the recording head during recording becomes the optimum recording level. By supplying the control voltage from the voltage generator, it is possible to reduce costs and improve reproduction characteristics.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the tape recorder of the present invention, and FIG. 2 shows an example used in a conventional tape recorder. 1... Playback head, 2... Playback amplifier (amplification circuit), 3... Noise reduction circuit, 4... Audio signal output terminal, 5... Audio signal input terminal, 6... Electronic volume, 7... Recording amplifier. (amplifier circuit), 8...
Recording head, 9... NPN transistor for mutating, 10... Control voltage generator, E1...
Recording mode signal, E2...Reproduction mode signal, R
1, R2...Resistor, V1...Control DC voltage during recording, V2...Control DC voltage during playback.

Claims (1)

[Scope of utility model registration request] A recording signal system having a reproduction signal system having a noise reduction circuit also used during recording, and a voltage generation circuit interposing an electronic volume for recording level setting in the middle thereof and generating a control DC voltage to control the electronic volume. 1. A tape recorder comprising: a control DC voltage supplied from the voltage generating circuit to the electronic volume so that the recorded signal becomes a minimum value during reproduction.