JP2003204591A - Voice control circuit - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To control by a mute circuit so that a sound mute is surely applied when a power switch is turned off so that no popping sound from a speaker is generated. SOLUTION: As a configuration in which a control of a mute circuit is pulled from an inversion switch interlocked with a power switch, a mute circuit can be operated without a delay time, and a pop noise sound when the power is turned off can be easily suppressed.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit configuration provided with means for interrupting an audio signal of an audio output IC, and no pop noise is generated when a power switch is turned off. And a voice control circuit. [0002] In a color television receiver,
Conventionally, the output of a reset IC has been used as a circuit for suppressing pop noise (hereinafter referred to as pop noise) when the power switch is turned off. FIG. 2 is a diagram showing a configuration of a conventional circuit for suppressing pop noise. The mute operation at power-on and power-off will be described below with reference to FIG. First, the operation at the time of power-on will be described. 1 is an audio signal input terminal and 2 is an audio switching output
Input to IC. The voice switching IC 2 is the IIC BUS of the microcomputer 9
And the desired input signal is selected. The audio signal selected by the audio switching IC 2 is input to the audio output IC 3 and the output is sent to the speaker 4 to reproduce the sound. The audio output IC 3 has a built-in audio mute circuit 16 and is configured to be muted when the terminal voltage is LOW and to interrupt the audio output. Reference numeral 16 denotes an audio mute circuit, and a transistor 13 operates as a switch to control the audio mute of the audio output IC 3. Voltages from 11 power supplies are applied to the bases of 13 transistors. A resistor 12 is a current limiting resistor. Since the power supply 11 rises quickly, it rises quickly when the power switch is turned on.
, The mute circuit operates to cut off the audio output. With this configuration, pop noise is suppressed when the power is turned on. If the 13 transistors that were turned on when the power was turned on remain turned on, the sound from the speaker remains cut off, so that it is necessary to cancel the sound mute. Since the power switch 6 is on, the reset IC 8 has 5
Are regulated and supplied by the regulator 7. The voltage of the regulator (REG) of 7 is 8
Is also supplied to the reset IC. 8 when the voltage supplied to the reset IC 8 reaches the reference voltage.
Changes from LOW to HIGH. This output is supplied to 14 transistors and 9 microcomputers. A current flows through a transistor 14 through a current limiting resistor 15,
The transistor No. 4 is turned on. Next, since the transistor 13 is turned off, the audio mute is released and the audio is output from the audio output IC. On the other hand, since the HIGH signal is also supplied to the 9 microcomputers, the microcomputers are reset, and then the IIC data is sent to the 2 voice switching ICs, so that the desired input signal is selected. The microcomputer 9 controls the port of the television power control circuit 10 and determines whether the circuit is on or off. Next, the operation when the power is turned off will be described. When the power switch 6 is turned off, the power supply to the regulator 7 is stopped, so that the output voltage drops.
When the voltage supplied to the reset IC 8 becomes equal to or lower than the reference voltage, the output of the reset IC changes from HIGH to LOW and the microcomputer 9 is reset.
The port control to the television data control circuit of the C data and 10 is stopped. At this time, the second audio switching IC is no longer controlled, and audio signal switching noise occurs. Since this is output as a pop sound, it is necessary to operate 16 audio mute circuits to suppress the pop sound. According to such a configuration, when the power switch of the power supply 6 is turned off, the power supply voltage of the reset IC 8 decreases.
The output of the reset IC 8 becomes LOW. This voltage is detected and 14 transistors are turned off. Next, since the transistor 13 is turned on, the audio is muted, the audio output is cut off, and the pop noise can be suppressed. This delay time occurs because the output of the reset IC of 8 is set to LOW when it drops to the reference voltage. FIG. 3 shows the delay time at this time. FIG. 3A shows the output voltage waveform of the reset IC 8 and FIG. 3B shows the output voltage waveform of the regulator 7. The delay time from when the main power switch 6 is turned off to when the input voltage of the reset IC 8 reaches the reference voltage can be seen from FIG. In addition, since the fourteenth transistors operate as switches, increasing the base current increases the accumulated charge and further increases the delay time when the power is turned off. If the delay time becomes longer, the audio mute timing is further delayed.
Since the IIC control of the voice switching IC stops earlier, the switching sound becomes a pop sound and is output from the voice output IC 3. Therefore, if the base current of the 14 transistors is reduced to shorten the delay time, the current will be insufficient and the transistor 14 will not be turned on, so that there will be no sound even when the power is turned on. Thus, the base current of the transistor, hFE
Therefore, it is difficult to set the constants of the circuit. In addition, since the hFE decreases at a low temperature due to the temperature characteristics of the transistor, the pop noise level tends to deteriorate. In order to solve the above-mentioned problems, an audio control circuit according to the present invention uses a reversing switch in conjunction with a power switch instead of a reset pulse of a microcomputer for controlling a mute circuit. The delay time is eliminated and the mute circuit is operated. A sound control circuit according to the present invention is characterized in that the sound output IC has a sound mute function, a transistor for controlling the mute terminal is provided, and another transistor for controlling the transistor is provided. In order to control the transistor for the control, a reverse switch interlocked with the power switch is provided and cut off, so that when the power switch is turned off, the sound is muted without delay time, and the pop-up from the speaker is performed. It is characterized in that noise noise is not generated. Hereinafter, an embodiment of the present invention will be described with reference to FIG. (Embodiment 1) An embodiment of the present invention will be described with reference to FIG. The same components as those of the above-described conventional example are denoted by the same reference numerals, and description thereof is omitted. In the conventional example, the control of 14 transistors is performed from the 8 reset ICs, but in the present invention, the control is performed by the 6 switches. The resistor 17 is provided to turn on the transistor 14 when the television power control circuit 10 is on. The power switch 6 comprises an A switch and a B switch and is interlocked. When the switch of A is turned on, the switch of B is turned off, and when the switch of A is turned off, the switch of B is turned on. According to this configuration, when the power switch 6 is turned off, the switch A is turned off and the switch B is turned on at the same time, so that the base voltage of the 14 transistors is grounded without delay time. That is, reset of 8
Since the delay time in the IC is eliminated and the mute operation is advanced by the delay time, the circuit design becomes easy. Further, deterioration of the pop noise level due to the temperature characteristics of the transistor can be suppressed. As described above, according to the present invention, since the mute circuit can be directly controlled by the inverting switch interlocked with the power switch, pop noise from the speaker when the power switch is turned off can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of an audio output circuit in one embodiment of the present invention. FIG. 2 is a circuit diagram of an audio output circuit in a conventional example. FIG. 3 is a waveform of a reset IC of the audio output circuit. [Description of Signs] 1 Audio signal 2 Audio switching IC 3 Audio output IC 4 Speaker 5 Power supply 6 Power switch 7 Regulator 8 Reset IC 9 Microcomputer 10 TV power control circuit 11 Power supply 12 Resistance 13 Transistor 14 Transistor 15 Resistance 16 Sound Mute circuit 17 resistance

Claims (1)

Claims: 1. An audio output IC for processing an input audio signal and outputting the processed signal to a speaker, an audio mute circuit for controlling the audio output IC, and a switch for controlling power on / off. An audio control circuit, wherein the audio mute circuit is a first audio control circuit for controlling the audio output IC.
And a second transistor for controlling the first transistor are provided, and the switch is provided with an inverting switch linked to its operation, and the inverting switch is grounded when the power is cut off. An audio control circuit, wherein the output is output to the base of the second transistor.