JP2669939B2 - Audio signal mute circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio signal mute circuit used in a video tape recorder (VTR) or the like.

[0002]

2. Description of the Related Art Generally, a VT equipped with a HiFi voice function.
In R, audio mute signals are separately supplied from the syscon microcomputer to either the HiFi audio signal processing circuit or the Normal audio signal processing circuit according to the input signal of ST (stereo), Lch, Rch, Normal, etc. However, the corresponding circuit is muted (see FIG. 2).

In FIG. 2, the syscon microcomputer 1 is S
HiFi audio signal processing circuit 2 and Norma for T, Lch, Rch, etc.
l Each is connected to the voice processing circuit 3. The output switching circuit 4 is connected to the outputs of ST, Lch, etc. of both the signal processing circuits 2 and 3, and is set to one of ST / L / R / Nor modes by the control signal C output from the timer microcomputer 5. It is switched to output a predetermined audio signal to the terminal 6. The timer microcomputer 5 and the syscon microcomputer 1 are connected by a data bus 7. In addition, 8 is an audio block.

In the above circuit configuration, INSERT PAUSE
In the mode, the control signal d is output from the syscon microcomputer 1 to turn off SW ₁ and SW ₂ . At this time, the Audio Mute signal a output from the syscon microcomputer 1 is Low, the circuit 2 is in an operating state, and the HIFI audio signal is in a recording standby state. Incidentally, the Audio NORMAL Mute signal b outputs Hi, and the circuit 3 is made inoperative. A.DUB (dubbing dubbing) PAUSE control signal e from syscon microcomputer 1
Is output and both SW ₁ and SW ₂ are turned off. At this time, the Audio Mute signal a output from the syscon microcomputer 1 is
Hi, which disables circuit 2. Audio No-rmal
The mute signal b is output as Low and the circuit 3 is in the operating state.
NORMAL audio signal goes into recording standby.

[0005]

In the above circuit configuration,
INSERT or Audio Mute signal a, b in A-DUB mode
The switches SW ₁ and SW ₂ for controlling the switch and the control signals d and e for controlling the switch are required, and the wiring associated therewith is complicated.

[0006]

The present invention provides a first circuit for processing HIFI audio signals such as ST, Lch and Rch, a second circuit for processing Normal audio signals, and first and second circuits. An output switching circuit that is selectively connected to ST / Lch / Rch / Nor by a mode switching control signal that is output from the timer microcomputer and connected to each circuit output, and a system controller connected to the timer microcomputer via a data bus. A microcomputer, which determines the audio mode by the presence or absence of a HIFI indicator lighting signal output from the first circuit to the timer microcomputer, and from the syscon microcomputer through the single signal line An audio mute signal for selectively deactivating the second circuit is output.

[0007]

[Function] With the above-described configuration, the timer microcomputer determines that the audio signal is HIFI (either ST / Lch / Rch) by the HIFI indicator lighting signal output from the HIFI audio processing circuit, and also sets the data bus. Information is transmitted to the Syscon microcomputer via the
In AUSE mode or A-DUB (dubbing dubbing)
A predetermined mute signal is output according to the operation mode such as the mode. If there is no HIFI indicator lighting signal, the timer microcomputer determines that the audio signal is normal and transmits that information to the syscon microcomputer.
The syscon microcomputer outputs a predetermined mute signal according to each operation mode.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The circuit configuration of the present invention will be described with reference to FIG.
The same parts as those in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted. The main components of FIG. 1 are the same as those of FIG. 2, and the wiring relationship is changed. The main changes are SW ₁ and SW _2.
And remove Audio Mu from Syscon Microcomputer 1.
te A single signal line is connected in parallel to the circuit 2 and circuit 3 in the audio block 8 to simplify the wiring and connect the circuit 2 and the timer microcomputer 5 to the HIFI indicator lighting signal. f is transmitted.

The operation of the circuit configuration of the present invention is characterized by the presence or absence of the HIFI indicator lighting signal f in FIG.
The timer microcomputer 5 determines whether the input voice signal is a HIFI voice signal or No.
In addition to discriminating whether it is an rmal audio signal, the HIFI / Normal of the input signal can be discriminated in the syscon microcomputer 1 connected by the data bus 7 as in the timer microcomputer 5.

Now, to the first circuit 2 for HIFI voice processing, HIFI
When voice is input, the HIFI indicator lighting signal f is transmitted from the circuit 2 to the timer microcomputer 5. As a result, the input signal of the timer microcomputer 5 is HIFI voice (ST / L
ch / Rch), the control signal c is output, and the output switching circuit 4 is switched to the HIFI mode (either ST, Lch, or Rch). The timer microcomputer 5 also transmits the HIFI information to the syscon microcomputer 1 via the data bus 7. Therefore, the system operation mode of the syscon microcomputer 1 is, for example, INSE
In the RT PAUSE mode, the Audio Mute signal g becomes Low and both the circuit 2 and the circuit 3 are operating, but the output switching circuit 4 is switched to the HIFI mode by the control signal c. The signal is output. A-DUB
In the PAUSE mode, the Audio Mute signal g output from the syscon microcomputer 1 becomes High, and circuit 2 and circuit 3
Are both muted and inoperative.

When the input signal is Normal, the signal f is not output, so the timer microcomputer 5 determines that it is in the Nomal mode, and outputs the control signal c for switching the output switching circuit 4 to the Normal mode. The information is transmitted to the syscon microcomputer 1 via the data bus 7, and INSERT PAUSE
Audio Mute signal g from Syscon microcomputer 1 in mode
Is output as a high level, and the circuits 2 and 3 are both muted and rendered inoperative. In the A-DUB mode, Low is output as the Audio Mute signal g from the syscon microcomputer 1 to operate both the circuit 2 and the circuit 3, but the output switching circuit 4 is switched to the normal mode as described above. Normal voice output is obtained at the terminal 6.

[0012]

Since the present invention is configured as described above,
At least one port of the syscon microcomputer can be reduced, processing of the mute signal on the audio signal processing circuit side can be greatly simplified, and the number of switches can be reduced, which has a large side effect of cost reduction. .

[Brief description of the drawings]

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 control 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)

(57) [Claims] 1. A first circuit (2) for processing a HiFi audio signal such as ST, Lch, Rch, etc., a second circuit (3) for processing a Normal audio signal, and the first and second circuits. An output switching circuit (4) connected to each output and selectively switched by a third control signal from the timer microcomputer (5), and a syscon microcomputer (1) connected to the timer microcomputer by a data bus (7). The audio signal mode is discriminated by the timer microcomputer depending on the presence / absence of the fourth control signal output from the first circuit to the timer microcomputer when the HiFi audio signal is processed by the first circuit. , Based on the result of this determination, the output control circuit is switched by the third control signal and is transmitted to the syscon microcomputer via the data bus. An audio signal mute circuit, wherein a fifth control signal is output to the first and second circuits via a single signal line to perform mute control of the first and second circuits. 2. The fourth control signal is a signal for lighting a HiFi indicator, and the fifth control signal is the first control signal.
An audio mute signal for selectively deactivating one or both of the second circuit and the second circuit.
Audio mute circuit.