JP3060541B2 - Mute system for AV equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impulsive sound when AC power supply is suddenly cut off (hereinafter referred to as an off-sound noise).
Is related to a mute system of an AV device in which the error occurs.

[0002]

2. Description of the Related Art In audio-visual equipment such as a television receiver and an audio stereo set, it has been a problem to mute off-sound generated when a power failure occurs or an AC outlet is suddenly unplugged. There has been a configuration in which a relay circuit is arranged in series in a signal circuit system, and when a power supply abnormality occurs, the audio signal path is cut off by this relay circuit to mute the audio.

[0003]

However, the use of a relay circuit requires a considerable board area, which is not preferable, and has the problems that the performance of the audio signal circuit system is reduced due to aging of the relay contact.
Therefore, if the AV device has a microcomputer control function, the audio mute process can be executed by software. Therefore, it is preferable to execute the mute of the off-buzz sound. However, when the power is turned off by operating the normal power switch, audio mute control can be performed as a software process.However, it is not possible to cope with a power failure such as sudden interruption of power supply. It could not be used as a mute means for off-buzz sound.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides a mute system for AV equipment which enables mute processing of off-buzz sound by software. That is, it has a power supply circuit unit for obtaining power from an AC outlet, and outputs a first power supply line for supplying power to the audio signal processing unit from the power supply circuit unit and a mute processing control signal to the audio signal processing unit. And a second power supply line for supplying power from the power supply circuit unit to the control unit capable of supplying power from the power supply circuit unit to the power supply instantaneous interruption detection unit for detecting that power supply from the AC outlet is stopped being supplied. The power supply line No. 3 is set so that the time constant of the power supply voltage drop is (third power supply line) <(first power supply line) <(second power supply line), and the power supply When the stop of the supply of the voltage is detected, the control means outputs a mute processing control signal to the audio signal processing circuit so that the mute processing of the audio output is performed.

[0005]

According to the above configuration, the power supply voltage of the third power supply line introduced to the instantaneous power supply interruption detecting means drops fastest.
If the instantaneous power supply interruption detecting means detects the power supply voltage drop and then supplies a detection signal to the control means which is energized by the second power supply line, the control means executes the second processing as software processing upon detection of the power supply voltage decrease. A mute control signal is supplied to the audio signal processing unit that is energized by the first power supply line whose power supply voltage has not yet decreased similarly to the power supply line of
The audio signal can be muted. Further, since the power supply voltage of the second power supply line falls later than that of the first power supply line, the mute processing is surely performed until the audio signal circuit system is turned off.

[0006]

FIG. 1 is a block diagram showing an embodiment of an off-boke sound mute system according to the present invention. The mute system is applied as a sound signal circuit system and a control system thereof in a television receiver, a monitor device, an audio stereo set, and the like. Things.

Reference numeral 1 denotes an AC outlet, and 2 denotes an AC power supplied from the AC outlet to, for example, a digital IC circuit.
V and 12 V DC output, and a power supply circuit section which converts the voltage to a DC power supply voltage required for the device such as a voltage for an analog signal (analog 5 V, analog 12 V) or the like and supplies it to each circuit section. An audio signal processing unit 4 that performs processing such as volume adjustment and mute on the audio signal by an external control signal, and 4 denotes a speaker output unit.

Reference numeral 5 denotes a CPU for supplying at least various control signals to the audio signal processing unit 3. The audio signal processing unit 3 is supplied with power from a power supply circuit unit 2 through a power supply line (A). On the other hand, power is supplied to the CPU 5 from the power supply circuit unit 2 via the power supply line (B). Reference numeral 6 denotes an instantaneous interruption detection circuit unit, which detects that the power supply voltage introduced through the power supply line (C) has dropped due to an AC outlet being unplugged or a power failure, and outputs a power-off detection signal to the CPU 5.

Here, the power supply circuit section 2 is connected to an AC outlet 1
When the AC power input from the power supply is suddenly cut off, the time constant until the power supply voltage drops for each of the output side power supply lines (A), (B) and (C) is (C) <(A) ) <(B)
Is set to That is, as shown in FIG.
For example, when the AC outlet 1 is suddenly unplugged at time t _{0, the} power supply voltage [power supply line (C)] introduced into the instantaneous interruption detection circuit unit 6 is set to drop at the earliest time, and then t 2 after ₁ hour, the audio signal processor power supply voltage supplied to the 3 [power supply line (a)] is turned off, and power supply voltage supplied to the CPU5 after further lapse t ₂ hours [power supply line (B )] Is turned off.

In the instantaneous interruption detection circuit section 6, if the power supply voltage supplied from the power supply line (C) is compared with a reference voltage by, for example, a comparator to perform waveform shaping, a power-off detection signal as shown in FIG. Since it can be obtained, it is supplied to the power on / off detection port of the CPU 5. The CPU 5 performs processing at the time of power on and at the time of power switch off (when the power switch is manually turned off instead of the AC outlet 1 being pulled out) based on the input of the power on / off detection port. Software is formed as described above.

[0011] CPU5 even when the power is turned off until t ₂ when it is possible to continue the program operation to maintain the energized state. Therefore, based on the power-off detection signal supplied to the power-on / off detection port after time t _0, the processing enters the normal power switch-off processing mode, and as one of the power-off processing, the audio signal processing unit 3 can output a mute control signal S _M. Until the time point t ₁ when the power supply state in the audio signal processing unit 3 is maintained, the mute process is performed as one of the processes at the time of normal power-off. That is, in the present embodiment, even if a sudden power-off occurs, the CPU 5 can recognize the power-off by a normal switch operation and perform the processing. Since Ofuboko sound that occurs immediately after t ₀ point AC power supply voltage drops, so that can be eliminated output of Ofuboko tone by muting until such time point t _1. Moreover, there is an advantage that the operation program of the CPU 5 can be almost the same as the conventional one.

The instantaneous interruption detection circuit section 6 in this embodiment is configured as shown in FIG. 3, for example. Reference numeral 6a denotes a reset circuit section formed by a comparator, which shapes the power supply voltage supplied from the power supply line (C) into a waveform having a sharp down edge as shown in FIG. 6b
Is a three-state buffer having a gate input G and an input A
, A ternary output Y can be obtained as shown in Table 1. As the gate input G, an “H” signal is supplied from the CPU 5 when the device is in a “power-on” state in which the device is operating. Reference numeral 6c denotes a diode for preventing backflow.

[0013]

[Table 1]

Hereinafter, the provision of the three-state buffer 6b will be described. As described above, the output of the instantaneous interruption detection circuit unit 6 is input to the power on / off detection port of the CPU 5, and when the power on and power off are detected by the input of the power on / off detection port, the CPU 5 Predetermined processing is performed in accordance with each program, but two different controls may be performed at power-on. First, when the user turns on the power switch of the device main body while the AC outlet 1 is connected (hereinafter referred to as PS-ON). Next, when the power switch of the device body is in the ON state, power is automatically supplied after the AC outlet is inserted or the power failure ends (hereinafter, A
C-on).

[0015] As is well known, an AV device such as a television receiver can be operated by a remote commander, and even if the power switch of the device body is turned on, the device is not necessarily turned on. It is not something that becomes. When the power switch of the device main body is on and the operation state by the remote commander is on, the power is turned on. That is, when the power switch of the device main body is in the on state, on / off control can be performed only by the remote commander. If the remote commander is turned off but the power switch of the device body is not operated, a so-called standby state (a remote commander operable state) is set.

Normally, the CPU as the control device of the AV device always keeps track of the current state of the device, and when the power switch of the device body is turned off, the operation state by the remote commander immediately before the power switch is turned off is maintained ( (Last memory function) When the power switch is turned on again, the power switch is set to the state immediately before the previous off operation. For example, when the power switch is turned off from the standby state, the standby state is set again by turning on the power switch again.

By the way, in the case of the above-mentioned AC-ON, control by such a last memory is necessarily required. For example, a power failure occurs during the standby state, and when the power failure ends thereafter, it is not appropriate to “power on” just because the power switch of the main body is on, and it is preferable to return to the standby state. However, PS-
In the case of ON, if the user is turned off in the standby state and returned to the standby state again as described above, the user must further operate the remote commander, which is very complicated. For this reason, at the time of PS-ON, the CPU 5 controls so that the device is forcibly "powered on" regardless of the last memory.

That is, in the CPU 5 in the present embodiment, signals having different waveforms are input to the power-on / off detection port when AC-ON and PS-ON, so that AC-ON and PS-ON are distinguished. Detected separately and perform different processing. For this reason, when the power-off detection signal is output from the instantaneous interruption detection circuit unit 6 to the power-on / off detection port during AC-ON and PS-ON, the AC-ON and PS-ON detection signals are affected. To make the determination impossible, only when the gate input of the three-state buffer 6b is "H", that is, when the device is "power-on".
The "H" or "L" power-off detection signal is output only when the power supply is in the state described above, and otherwise the high impedance output is used to eliminate the influence on the AC-on and PS-on detection signals. Is what it is.

[0019]

As described above, according to the mute method for AV equipment of the present invention, the time constant of the power supply voltage drop is (third power supply line) <(first power supply line) <(second power supply line). It is set to be so as to detect an instantaneous power interruption from the third power supply line where the power supply voltage drops at the earliest at the moment of an instantaneous power interruption,
The control means supplied with the second power supply line supplies a mute control signal to the audio signal processing section supplied with the first power supply line, thereby performing mute processing of the audio signal. There is an effect that the mute processing of the off-buzz sound can be performed by software means even when a sudden power off such as pulling out or a power failure occurs.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating one embodiment of a mute system for AV equipment of the present invention.

FIG. 2 is a waveform diagram for explaining the present embodiment.

FIG. 3 is a block diagram of an instantaneous interruption detection circuit unit according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC outlet 2 Power supply circuit part 3 Audio signal processing part 5 CPU 6 Instantaneous interruption detection circuit part

Claims (1)

(57) [Claims] A power supply circuit for obtaining power from an AC outlet; a first power supply line for supplying power from the power supply circuit to an audio signal processing unit; and a mute processing control for the audio signal processing unit. A second power supply line for supplying power from the power supply circuit unit to control means capable of outputting a signal; and a power supply circuit for detecting a power supply interruption from the AC outlet. A third power supply line for supplying power from the unit is set such that the time constant of the power supply voltage drop is (third power supply line) <(first power supply line) <(second power supply line);
When the supply stop of the power supply voltage is detected by the power supply instantaneous interruption detection means, the control means outputs a mute processing control signal to the audio signal processing circuit unit so that the mute processing of the audio output is performed. A mute system for AV equipment, characterized in that it is configured.