JP2003087684A - Voice circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the power consumption of equipment which has a voice output device. SOLUTION: A voice signal level detecting circuit 5 always detects the level of the voice signal outputted from a voice preamplifier 2 and a microcomputer 7 controls a power supply circuit 6 according to the level of the voice signal detected by the voice signal level detecting circuit 5 to vary a source voltage supplied to a voice power amplifier 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device such as a television in an audio output device.

[0002]

2. Description of the Related Art In recent years, high-performance sources such as BS digital have come to be broadcast, and various types of signal generators for input signals have been developed. In the audio system as well, there is an increasing demand for higher sound quality, and there is also a strong demand for energy saving. Against this background, it is required for the audio circuit to reduce the power consumption without impairing the sound quality.

[0003] Conventionally, as one of methods for reducing power consumption in a voice circuit, Japanese Patent Laid-Open No. 2000-16515.
There is a method as shown in Japanese Patent Publication No.

FIG. 2 shows a block diagram of a conventional amplifier circuit used in a voice circuit or the like. In this method, the setting level detecting means 105 detects a value such as a volume set by the user using the output level setting means 110, and the power supply voltage supplied to the power amplifier 103 is changed based on the detection result. By making a change in 111, for example, at the time of outputting a low volume, the power supply voltage is not raised more than necessary and power consumption is reduced.

[0005]

SUMMARY OF THE INVENTION In the above amplifier circuit,
Power amplifier 1 linked to the output level set by the user
If the level of the audio signal input to the power amplifier 103 does not match the power supply voltage of the power amplifier 103, the level of the audio signal itself input to the input terminal 101 is low and is set to change When the dynamic range of the power amplifier 103, which is determined based on the output level, is greatly reduced, the power supply voltage is increased more than necessary, resulting in a loss of power consumption.

In view of the above-mentioned problems, the present invention provides an audio circuit for controlling so that a power supply voltage always matching the level of an input audio signal can be supplied to an amplifier.

[0007]

In order to solve the above problems, the audio circuit of the present invention detects the level of an audio signal and lowers the power supply voltage supplied to the audio power amplifier when the level is low. The audio circuit is characterized by controlling so as to raise the power supply voltage supplied to the audio power amplifier when the level is high.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention detects the level or distortion rate of an audio signal constantly or at a specific period, and automatically changes the power supply voltage according to the level or distortion rate. The power supply voltage of the audio power amplifier is automatically lowered when the audio signal level is low, and the power supply voltage is not raised more than necessary, so the power consumption of the audio circuit can be reduced. Also, when the audio signal level is high, the power supply voltage of the power amplifier is automatically raised within the required range, so that the increase in power consumption can be minimized and the audio distortion due to lack of dynamic range can be suppressed. Since it can be corrected, the sound quality can be improved.

(Embodiment 1) An embodiment of the present invention will be described below with reference to FIG. As an example, a television audio circuit is shown.

In FIG. 1, 1 is an audio signal input terminal, 2
Is an audio preamplifier that determines the sound quality and volume of the output audio signal, 3 is an audio power amplifier that amplifies the audio signal output from the audio preamplifier 2, and 4 is the audio signal that is output from the audio power amplifier 3 as audio. An audio output speaker, 5 is an audio signal level detection circuit for detecting the level of the audio signal output from the audio preamplifier 2, 6
Is a power supply circuit for supplying a power supply voltage to the audio power amplifier 3, 7 is a power supply circuit 6 for controlling the audio preamplifier 2 and based on the detection result of the audio signal level detection circuit 5.
The microcomputer 8 controls the power supply voltage value of the audio power amplifier 3.

First, the audio signal input to the audio signal input terminal 1 is input to the audio preamplifier 2. Then, the audio preamplifier 2 is controlled by the microcomputer 7, and the audio signal whose volume and sound quality are determined by this is input to the audio power amplifier 3 and the audio signal level detection circuit 5. With respect to the audio signal whose volume and sound quality have been determined, the audio signal level detection circuit 5 always detects the peak value of the signal level, and the peak value is input to the microcomputer 7. The microcomputer 7 controls the power supply circuit 6 based on this peak value and the value of the power supply voltage of the audio power amplifier called from the storage device 8 under the conditions described later, and the power supply voltage supplied to the audio power amplifier is controlled. Changed and voice power amplifier 3
The value of the newly changed power supply voltage supplied to the storage device 8 is stored in the storage device 8. The audio signal output from the audio preamplifier 2 is input to the audio power amplifier 3 under the aforementioned power supply voltage. The audio power amplifier 3 amplifies the input audio signal with a constant gain and outputs the amplified audio signal, which is output as audio by the audio output speaker 4.

Next, a specific operation of the microcomputer 7 when controlling the power supply circuit 6 will be described. First, when the power of the device is turned on, the power supply voltage of the audio power amplifier 3 is stored in the storage device 8 as an initial setting. Next, when the peak value of the audio signal detected by the audio signal detection circuit 5 is input to the microcomputer 7, a comparison between this peak value and the power supply voltage of the audio power amplifier 3 called from the storage device 8 will be described below. Do by the way.

A signal having the same level as the audio signal input to the audio signal level detection circuit 5 is input to the audio power amplifier 3, amplified with a constant gain and then output, so that the audio input to the audio power amplifier is output. The peak value of the signal is V
i, when the amplification factor of the audio power amplifier is a constant value A, the level of the audio signal input is A times, and the peak value of the audio signal output from the audio power amplifier is Vo, Vo = A × The relationship of Vi is established. Assuming that the power supply voltage of the audio power amplifier called from the storage device 8 is Vc, the microcomputer 7 compares Vo and Vc to make the power supply voltage have a predetermined margin.
The power supply voltage of the audio power amplifier is controlled so that the power supply voltage of the audio power amplifier becomes Vo + α when the margin value is α, and the power supply voltage value of the audio power amplifier determined as a result is stored in the storage device. 8 is stored.

In the above description, in the audio signal level detection circuit, the power supply voltage of the audio power amplifier is compared with the peak value of the audio signal to control the power supply voltage. Alternatively, the comparison with the power supply voltage of the audio power amplifier may be performed based on the average value or the execution value.

In the above description, the audio signal output from the audio preamplifier is detected, but the audio signal output from the audio power amplifier may be detected. In this case, in the audio signal level detection circuit, the peak value, the average value, or the execution value of the audio signal is compared with the power supply voltage of the audio power amplifier as described above, and the audio signal output from the audio power amplifier is compared. May be detected and the power supply voltage of the audio power amplifier is controlled so that the distortion rate is always less than or equal to a predetermined value.

Two specific operation examples of this audio circuit will be shown.

As a first example, an operation example in the case where the level of the audio signal input to the audio power amplifier is lowered and the dynamic range of the audio power amplifier becomes excessive is shown. When the peak value of the audio signal level output from the audio preamplifier 2 is V1, the peak value is A × V1 as being amplified by A times by the audio power amplifier 3, and therefore the margin α is secured. The power supply circuit 6 is controlled by the microcomputer 7 so that the power supply voltage of the audio power amplifier is A × V1 + α, and is stored in the storage device 8 as the power supply voltage of the audio power amplifier is A × V1 + α.

Therefore, the peak value of the output level of the audio signal output from the audio preamplifier 2 is lower than V1 described above.
When it changes to 2, the voice signal level detection circuit 5 detects that the peak value of the voice signal is V2, and the information that this value is the peak value is input to the microcomputer 7. Then, the microcomputer 7 calls from the storage device 8 the value stored as the power supply voltage of the audio power amplifier. In this case, it is A × V1 + α from the above. This A × V1 + α is compared with the power supply voltage value A × V2 + α of the audio power amplifier corresponding to the detected peak value V2 of the audio signal level. In this case, the power supply voltage value A × V2 + α of the audio power amplifier corresponding to the detected peak value V2 of the audio signal level is smaller than the power supply voltage value A × V1 + α of the previously controlled audio power amplifier. The power supply circuit 6 is controlled to lower the power supply voltage of A × V2 + α, and the storage device 8 stores the power supply voltage of the audio power amplifier as A × V2 + α.

As a second example, an operation example in the case where the dynamic range in the audio power amplifier becomes insufficient due to the increase in the level of the audio signal input to the audio power amplifier will be shown. Similar to the first example, when the peak value of the audio signal level output from the audio preamplifier 2 is V1, the peak value is A × V1 as being amplified by A times by the audio power amplifier 3, Margin α
In order to ensure the above, the power supply circuit 6 is controlled by the microcomputer 7 so that the power supply voltage of the audio power amplifier becomes A × V1 + α, and the power supply voltage of the audio power amplifier is stored in the storage device 8 as A × V1 + α. Remembered.

Therefore, the peak value of the output level of the audio signal output from the audio preamplifier 2 exceeds V1 mentioned above.
When the value changes to 3, the audio signal level detection circuit 5 detects that the peak value of the audio signal is V3, and the information that this value is the peak value is input to the microcomputer 7. Then, the microcomputer 7 calls from the storage device 8 the value stored as the power supply voltage of the audio power amplifier. In this case, it is A × V1 + α from the above. This A × V1 + α is compared with the power supply voltage value A × V3 + α of the audio power amplifier corresponding to the detected peak value V3 of the audio signal level. In this case, the power supply voltage value A × V3 + α of the audio power amplifier corresponding to the detected peak value V3 of the audio signal level is larger than the power supply voltage value A × V1 + α of the previously controlled audio power amplifier. The power supply circuit 6 is controlled so as to raise the power supply voltage to A × V3 + α, and the storage device 8 stores the power supply voltage of the audio power amplifier as A × V3 + α.

Although the value of the power supply voltage supplied by the power supply circuit is continuously variable in the above description, it may be variable discontinuously, that is, it may be changed in a plurality of steps.

By automatically changing the power supply voltage of the audio power amplifier according to the level of the audio signal in this manner, it is possible to always secure the dynamic range of the audio power amplifier without excess or deficiency.

[0023]

According to the audio circuit of the present invention, by automatically changing the power supply voltage of the audio power amplifier according to the level of the audio signal, the audio power amplifier is automatically operated when the audio signal level is low. Since the power supply voltage of is decreased and the power supply voltage is not increased more than necessary, power consumption in the audio circuit can be reduced.

Further, when the audio signal level is high, the power supply voltage of the power amplifier is automatically raised within a required range, so that the increase in power consumption can be suppressed to a minimum.
Since it is possible to correct the sound distortion caused by the lack of the dynamic range, it is possible to improve the sound quality.

[Brief description of drawings]

FIG. 1 is a block diagram of an audio circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional power amplifier circuit.

[Explanation of symbols]

1, 101 Audio signal input terminal 2,102 voice preamplifier 3 voice power amplifier 4, 104 audio output speaker 5 Audio signal level detection circuit 6 Power supply circuit 7 Microcomputer 8 storage devices

Continued front page    F-term (reference) 5C026 DA00 DA05 EA00                 5D020 AC01                 5J091 AA02 AA41 CA21 CA36 FA01                       KA00 KA33 KA62 SA05 TA01                 5J092 AA02 AA41 CA36 CA81 FA01                       FA10 GR01 GR05 KA12 KA17                       KA49 KA55 KA62 MA14 MA20                       SA05 TA01                 5J500 AA02 AA41 AC21 AC36 AC81                       AF01 AF10 AK00 AK12 AK17                       AK33 AK49 AK55 AK62 AM14                       AM20 AS05 AT01 RG01 RG05

Claims (2)

[Claims] 1. An audio circuit which detects the level or distortion rate of an audio signal and automatically changes the power supply voltage according to the level or distortion rate. 2. An audio preamplifier for determining sound quality and volume, an audio power amplifier for amplifying a level of an audio signal output from the audio preamplifier, a power supply circuit for supplying power to the audio power amplifier, and the audio An audio signal level detection circuit that detects the level of an audio signal output from a preamplifier, a microcomputer that controls the power supply voltage of the power supply circuit and the volume and sound quality of the audio signal output from the audio preamplifier, and the audio power amplifier An audio circuit equipped with a storage device for storing the power supply voltage value of.