JPH04248166A - Sound signal muting circuit - Google Patents

Abstract

PURPOSE:To simplify a sound muting circuit corresponding to each operation mode of a sound signal processing circuit in a magnetic recording and reproduc ing device such as a VTR mounted with a hi-fi sound function. CONSTITUTION:The subject circuit is composed of a 1st circuit 2 for processing a hi-fi sound signal, a 2nd circuit 3 for processing a normal sound signal, an output changeover circuit 4 connected with outputs of the 1st and 2nd circuits 2 and 3 respectively and for changing them with a 3rd control signal (c) from a timer microcomputer 5 and a system control microcomputer 1 connected to the timer microcomputer 5 with a data bus 7, whereas a sound is discriminated by the presence of a 4th control signal (f) to be outputted from the above 1st circuit to the timer microcomputer 5, while a 5th control signal (g) is outputted from the said system control microcomputer 1 via a single signal line to the above 1st and 2nd circuits 2 and 3.

Description

Detailed Description of the Invention [0001] [Industrial Application Field] The present invention relates to a video tape recorder (
This invention relates to an audio signal muting circuit used in VTRs and the like. [Prior Art] Generally, VT equipped with HiFi audio function
For R, ST (stereo), Lch, Rch,
Depending on the input signal such as Normal, the system microcomputer supplies an audio mute signal to either the HiFi audio signal processing circuit or the Normal audio signal processing circuit, respectively, and mutes the corresponding circuit (see Figure 2). . In FIG. 2, the system microcomputer 1 has an S
It is connected to a HiFi audio signal processing circuit 2 such as T, Lch, and Rch, and a normal audio processing circuit 3, respectively. The output switching circuit 4 is connected to the ST of both signal processing circuits 2 and 3.
, Lch... etc. are connected to the timer microcontroller 5.
ST/L/R/No by control signal C output from
r mode and outputs a predetermined audio signal to the terminal 6. The timer microcomputer 5 and the system controller microcomputer 1 are connected by a data bus 7. Note that 8 is the audio block. In the above circuit configuration, ■ INSERT
In PAUSE mode, control signal d is output from system microcomputer 1 and turns SW1 and SW2 OFF. At this time, the audio output from system microcontroller 1
The Mute signal a is Low, the circuit 2 is in an operating state, and the HIFI audio signal is in a recording standby state. Furthermore, A
The audio NORMAL Mute signal b is output as Hi, making the circuit 3 inoperable. ■A. During DUB (dubbing/dubbing) PAUSE, the control signal e is output from the system microcomputer 1 and both SW1 and SW2 are turned off.
Make it. At this time, the Audio Mute signal a output from the system microcomputer 1 is Hi, making the circuit 2 inoperable. In addition, Audio Normal Mu
The te signal b is output as Low, the circuit 3 is in an operating state, and the NORMAL audio signal is in a recording standby state. Problems to be Solved by the Invention In the above circuit configuration,
Audio in INSERT or A-DUB mode
Switch SW for controlling Mute signals a and b
1, SW2 and a control signal d for controlling the switch
, e, and the accompanying wiring is complicated. [Means for Solving the Problems] The present invention provides ST, Lch
, Rch, etc.; a second circuit that processes a Normal audio signal;
The outputs of the second circuit and the second circuit are connected, and the mode switching control signal output from the timer microcomputer causes S
It consists of an output switching circuit that can selectively switch to either T/Lch/Rch/Nor, and a system controller microcomputer connected to the timer microcomputer via a data bus, and the HIFI output from the first circuit to the timer microcomputer is A configuration in which an audio mode is determined based on the presence or absence of an indicator lighting signal, and an audio mute signal is output from the system microcomputer via a single signal line to selectively disable the first and second circuits. shall be. [Operation] With the above-described configuration, the timer microcomputer detects whether the audio signal is HIFI (ST/Lch/Lch/
Rch) and transmits information to the system controller microcontroller via the data bus, and the system controller microcontroller selects an operating mode such as INSERT PAUSE mode or A-DUB (dubbing/dubbing) mode. A predetermined mute signal is output in accordance with the mute signal. Also, if there is no signal for lighting the HIFI indicator, the timer microcomputer determines that the audio signal is Normal and transmits that information to the system microcomputer.
The system microcomputer outputs a predetermined mute signal according to each operation mode. Embodiment The circuit configuration of the present invention will be explained with reference to FIG. Note that the same parts as those in FIG. 2 are given the same numbers, and the explanation thereof will be omitted. The main components in Fig. 1 are the same as in Fig. 2, but the wiring relationship has been changed, and the main changes are SW1, SW
2, and Aud from system microcomputer 1.
io Mute By using one signal line and connecting it in parallel to circuit 2 and circuit 3 in audio block 8, wiring can be simplified, and circuit 2 and timer microcomputer 5 can be connected to turn on the HIFI indicator. signal f
I am trying to transmit. The feature of the operation of the circuit configuration of the present invention is that the timer microcomputer 5 determines whether the input audio signal is a HIFI audio signal or a normal audio signal depending on the presence or absence of the HIFI indicator lighting signal f in FIG. Similarly to the timer microcomputer 5, the input signal HIFI/Normal is also
This is the point where it is possible to determine. Now, when HIFI audio is input to the first circuit 2 for HIFI audio processing, a HIFI indicator lighting signal f is transmitted from the circuit 2 to the timer microcomputer 5. As a result, the timer microcomputer 5 receives the input signal from HIFI audio (ST/Lch/
Rch), and outputs a control signal c to set the output switching circuit 4 to HIFI mode (ST, Lch, Rch).
). The timer microcomputer 5 also transmits HIFI information to the system microcomputer 1 via the data bus 7. Therefore, when the operating mode of the device in the system microcomputer 1 is, for example, the INSERT PAUSE mode, the Audio Mute signal g becomes Low, and the circuits 2 and 3 are both operating, but the output switching circuit 4 is set to the HIFI mode by the control signal c. Therefore, a predetermined signal is output to terminal 6. A-DU
In the case of B PAUSE mode, the Audio Mute signal g output from the system controller microcontroller 1 is High.
Therefore, both circuit 2 and circuit 3 are muted and inoperable. When the input signal is Normal, the signal f is not output, so the timer microcomputer 5 determines that the mode is Normal, and outputs the control signal c for switching the output switching circuit 4 to the Normal mode. The information is transmitted to the system controller microcomputer 1 via the data bus 7, and when in the INSERT PAUSE mode, the system controller microcomputer 1 outputs a Hi signal as an Audio Mute signal g.
gh is output, muting both circuit 2 and circuit 3 and rendering them inoperable. In A-DUB mode, the Audio Mute signal g is Low from the system microcontroller 1.
is output, causing both circuits 2 and 3 to operate, but since the output switching circuit 4 is switched to the normal mode as described above, a normal audio output is obtained at the terminal 6. Effects of the Invention Since the present invention is configured as described above,
At least one port on the system microcontroller can be reduced, the processing of the mute signal on the audio signal processing circuit side can be greatly simplified, and the number of switches can also be reduced, which has a large secondary effect of cost reduction. .

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram of the present invention.

FIG. 2 is a circuit block diagram of a conventional example.

[Explanation of symbols]

1 System microcomputer 2 HIFI audio signal processing circuit (first circuit) 3
Normal audio signal processing circuit (second circuit)
4 Output switching circuit 5 Timer microcomputer 7 Data bus c Third control signal f Fourth control signal g Fifth control signal

Claims (2)

[Claims] 1. A first circuit that processes HiFi audio signals such as ST, Lch, Rch, etc., a second circuit that processes Normal audio signals, and the first and second circuit outputs are connected to each other, and a timer is provided. It consists of an output switching circuit selectively switched by a third control signal from the microcomputer, and a system controller microcomputer connected to the timer microcomputer via a data bus, and a fourth output switching circuit that outputs from the first circuit to the timer microcomputer. The audio signal mode is determined based on the presence or absence of a control signal, and the system microcomputer outputs a fifth control signal to the first and second circuits via a single signal line. mute circuit. 2. The fourth control signal is a HiFi indicator lighting signal, and the fifth control signal is an audio mute signal that selectively disables the first and second circuits. 1 audio signal mute circuit.