JPS62250556A - Video tape recorder - Google Patents

Abstract

PURPOSE:To reduce the number of components and to prevent a switching noise caused at the changeover of a channel and the recording/reproduction mode by providing a sound mute circuit receiving a channel switching signal or a recording/reproduction mode switching signal from a tuner to a 2nd processing circuit. CONSTITUTION:In the mode monitoring the sound signal received by the tuner 1 without recording, a mute signal is supplied to the sound mute circuit 12 from a channel selection circuit 15 at the channel switching in the tuner 1. Thus, no switching noise at channel changeover is caused. Further, a mute signal is fed from a system control circuit 14 to the sound mute circuit 12 at the changeover of the recording/reproduction mode and at the tape loading. Thus, no switching noise at the mode changeover is caused. Since the channel changeover is not locked at the recording mode, an undesired signal due to the channel changeover is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a video tape recorder equipped with a tuner and capable of selectively recording and reproducing television signals of desired channels.

[Conventional technology]

Generally, a home video tape recorder is equipped with an integrated tuner and is configured to be able to select and record and reproduce a desired channel independently of the television receiver. In such a video tape recorder, in order to enable recording signals to be monitored, a signal of a desired channel selected by a tuner is processed for recording, and is supplied to a magnetic head to enable recording. The reproduced signal can also be supplied to a reproduction signal processing circuit.

By the way, when switching channels of a tuner, an undesired signal is mixed into the output signal, and for this reason, according to the above circuit configuration, when monitoring a recording signal, especially the audio signal recording processing circuit and playback processing circuit. An undesired signal is output through the circuit and is supplied to the speaker, producing an unpleasant sound. Furthermore, during tape loading or when switching between recording and playback modes, an undesired signal is supplied to the speaker via the playback processing circuit, and unpleasant sounds are also generated in this case.

Therefore, conventionally used tuners, such as voltage synthesizer electronic tuners, are equipped with an audio mute circuit as disclosed in "Television Technology" August 1983 issue PP, 118-120. I try to mute the switching sound. In addition, as disclosed in "Television Technology" July 1984 issue R73, the audio signal to be recorded and the audio signal to be reproduced are processed by a common equalizer, and the audio signal to be recorded output from the equalizer is The reproduced audio signal is supplied to the output terminal and the magnetic head via the AGC, and is also output from the equalizer. The reproduced audio signal is supplied to the output terminal via a processing circuit dedicated to reproduction, and is reproduced with the audio signal to be recorded. In this case, an audio mute circuit is provided in the reproduction-only processing circuit to mute the switching sound when the recording/reproducing mode is switched.

[Problem that the invention seeks to solve]

According to the above-mentioned conventional technology, a video tape recorder does not have to be provided with an audio mute circuit for each source of undesired sound, and circuits with the same function are required twice, resulting in an increase in the number of parts. , which will lead to an increase in costs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a video tape recorder which eliminates such problems, reduces the number of parts, and prevents switching sounds that occur when switching channels and recording/playback modes.

[Means for solving problems]

To achieve this object, the present invention provides an audio circuit that includes a first processing circuit that processes an audio signal to be recorded, and an audio signal output from the first processing circuit and a reproduced audio signal. and a second processing circuit that processes the second processing circuit.
The processing circuit is provided with an audio mute circuit to which a channel switching signal in a tuner, a recording/playback mode switching signal, etc. are supplied as a mute signal.

[Effect]

The second processing circuit is supplied with the audio signal from the tuner and the reproduced audio signal, and an audio mute circuit provided in the second processing circuit is used when switching channels in the tuner and when changing the recording/playback mode. Both are muted when switching.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

The figure is a block diagram showing an embodiment of a video tape recorder according to the present invention, in which 1 is a tuner, 2 is an AFT (automatic frequency adjustment) circuit, 3 is an audio detection circuit, 4 is an input signal switching circuit, and 5 is an input signal. terminals, 6 is an ALC (automatic level control) circuit, 7 is a recording amplifier, 8 is a recording/playback head switching circuit, 9 is a playback amplifier, 10 is a recording/playback switching circuit, 11 is a line amplifier, 12 is an audio mute circuit, 13 is a 14 is a system control circuit L1s is a channel selection circuit, 16 is an ATF switching circuit, and 17 is a magnetic head.

In the figure, in the recording mode, the received RF' signal of the desired channel selected by the tuner 1 is transmitted to the audio detection circuit 3.
to obtain the audio signal of that channel. This audio signal is supplied to the ALC circuit 6 via the input signal switching circuit 4, and is controlled to have a constant level.

The audio signal output from this ALC circuit 6 is, on the one hand, amplified by a recording amplifier 7, then supplied to a magnetic head 17 via a recording/reproducing head switching circuit 8, and recorded on a magnetic tape (not shown). The audio signal output from the ALC circuit 6 also passes through a recording/reproduction switching circuit 10, is amplified by a line amplifier 11, passes through an audio mute circuit 12, and is supplied from an output terminal 13 to a speaker (not shown).

In this way, the received audio signal of the desired channel is monitored as well as recorded.

Note that the input terminal 5 is supplied with an audio signal from an audio device such as a microphone or a stereo device, and the input signal switching circuit 4 selects between the audio signal from the input terminal 5 and the audio signal from the audio detection circuit 3. or choose one.

In addition, the audio signal output from the input signal switching circuit 4 is
You can monitor without recording.

In this case, the audio signal output from the ALC circuit 6 is supplied to the magnetic head 17, but is not recorded because the magnetic tape does not run.
, a line amplifier 11, and an audio mute circuit 12, and are supplied from an output terminal 13 to a speaker.

Next, in the reproduction mode, the audio signal reproduced by the magnetic head 17 from the magnetic tape (not shown) is supplied to the reproduction amplifier 9 via the recording/reproduction head switching circuit 8 and is amplified to a predetermined level. The audio signal output from the playback amplifier 9 is transferred to the recording/playback switching circuit 10 and the line amplifier 1.
1 and an audio mute circuit 12, and is supplied from an output terminal 13 to a speaker (not shown).

Recording/playback head switching circuit 8 and recording/playback switching circuit 10
is controlled by the system control circuit 14 when switching the recording/reproducing mode.

Simultaneously with this switching control, the system control circuit 14 supplies the mode switching signal as a mute signal to the audio mute circuit 12.

Further, in the tuner 1, channel switching is performed by a channel setting signal from the channel selection circuit 15, and at this time, a control signal is supplied from the channel selection circuit 15 to the AFT switching circuit 16, which causes the APT circuit 2 to switch. Turns off.

In other words, when switching channels in tuner 1, AFT
When the tuner 1 is set to a desired channel while the circuit 2 is in an off state, the AP'I' circuit 2 is activated to perform fine adjustment of that channel. In this case, the channel selection circuit 15 supplies a control signal to the AFT switching circuit 16 and at the same time supplies a mute signal to the audio mute circuit 12.

Here, in the recording mode, the tuner 1 is channel locked and cannot switch channels. Further, in the reproduction mode, the channel selection circuit 15 is set to a non-operating state, and the audio mute circuit 12 is not supplied with a hemute signal from the channel selection circuit 15.

Therefore, in a mode in which the audio signal received by the tuner 1 is monitored without being recorded, a mute signal is supplied from the channel selection circuit 15 to the audio mute circuit 12 when the tuner 1 switches channels. This results in
There is no switching sound when switching channels. Further, a mute signal is supplied from the system control circuit 14 to the audio mute circuit 12 when loading the tape or switching the recording/reproducing mode. As a result, no switching sound is generated when switching between modes.

In the recording mode, since channel switching is locked and cannot be performed, undesired signals due to channel switching will not be recorded.

Even if a channel is operated in the playback mode, since the channel selection circuit 15 is in the off state, the played audio signal will not be unduly muted.

〔Effect of the invention〕

As explained above, according to the present invention, a single audio mute circuit can be used when switching channels, loading a tape, etc.
To provide a video tape recorder which can prevent undesired sounds generated when switching recording/playback modes, can reduce the number of parts and cost, and can solve the problems of the above-mentioned conventional technology and has excellent functions. be able to.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a video tape recorder according to the present invention. 1... Tuner 2... Automatic frequency adjustment circuit 3... Audio detection circuit 6... Automatic level control circuit 7... Recording amplifier 8... Recording/playback head switching circuit 9... Playback amplifier 10 ...Recording/playback switching circuit 11...Line amplifier 12...Audio mute circuit 13...Output terminal 14...System control circuit 15...Channel selection circuit 16...AFT switching circuit 17... ...Magnetic head.

Claims (1)

[Claims] 1. In a video tape recorder equipped with a tuner whose automatic frequency adjustment circuit is set to OFF state when a desired channel is selected, and which is capable of selectively recording and playing back the television signal of the desired channel, the audio circuit is selected by the tuner. a first processing circuit that processes the audio signal of a desired channel to be broadcast for recording; and a second processing circuit that selectively processes the audio signal processed by the first processing circuit and the reproduced audio signal. The second processing circuit is provided with an audio mute circuit to which a signal indicating the time of tape loading or switching of the recording/playback mode, and a signal for turning off the automatic frequency adjustment circuit are supplied as a mute signal. A video tape recorder characterized in that the video tape recorder is configured to be capable of preventing the generation of undesired sounds when switching, recording/playback mode switching, etc.