JPH11205060A - Circuit for controlling sound quality - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a volume level for hearing from chaining even if the sound quality mode setting is changed and to change the frequency characteristic of a voice signal despite the circuit configuration being simple. SOLUTION: A voice signal (audio) is outputted to loudspeaker 50 side successively via an attenuator 10 for adjusting its level and a sound quality change- over circuit 20 for chaning its frequency characteristic. The attenuator 10 and the sound quality change-over circuit 20 are controlled by a control circuit 30, in accordance with the setting of a sound quality mode change-over switch 60. A data table which indicates the relation between a volume set value and a volume adjusting value, in order to beep the volume level constant for hearing even when the sound quality mode setting is changed has been prepared previously for each sound quality mode in the control circuit 30. When sound volume mode setting is changed, the control circuit 30 changes-over the sound quality change-over circuit 20 in accordance with it, obtains the volume adjusting value corresponding to the set value of present volume from the data table of the sound quality mode, which indicates the relation between the volume set value and the volume adjusting value and controls the attenuator 10 based on the volume adjusting value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit provided in a television receiver or the like, and more particularly to a sound quality control circuit having a function of changing a frequency characteristic of an audio signal according to a sound quality mode setting.

[0002]

2. Description of the Related Art As a conventional example of this kind of sound quality control circuit, there is a circuit disclosed in JP-A-4-44724. Here, the frequency components included in the audio signal are extracted by the band-pass filter group, the level of each signal extracted by the electronic volume circuit group is individually adjusted, and the frequency component for each band is synthesized by the mixing circuit. The level of the audio signal is adjusted by an amplifier, and the gains of the electronic volume circuit group and the amplifier are adjusted, whereby the audibility of the playback volume is corrected, so that playback with desired sound quality can be performed regardless of the playback volume. The circuit configuration is made possible.

[0003]

However, in the case of the above-mentioned conventional example, there is an essential disadvantage that the entire circuit is very complicated and the cost increases accordingly. In addition, when the sound quality is adjusted, the sound level of the audibility changes in accordance with the adjustment, and the sound volume may need to be adjusted.

The present invention has been made in view of the above background, and has as its object to change the frequency characteristic of an audio signal while having a very simple circuit configuration. An object of the present invention is to provide a sound quality control circuit in which the volume level in the sense of hearing does not change even when the setting of the sound quality mode is changed.

[0005]

A sound quality control circuit according to the present invention includes a plurality of filter circuits provided between an audio signal line and a ground or power supply line and for blocking a predetermined frequency component from the audio signal; The configuration includes a plurality of switch elements respectively connected in series to the plurality of filter circuits, and a sound quality control circuit for controlling on / off of the plurality of switch elements according to the setting of the sound quality mode.

In such a configuration, when the setting of the sound quality mode changes, the sound quality control circuit operates according to the setting, and all or some of the plurality of switch elements are switched on and off. When all or some of the plurality of switch elements are switched on and off, all or some of the plurality of filter circuits are selected accordingly, and a predetermined frequency component is blocked from the audio signal by the selected filter circuit,
As a result, the frequency characteristics of the audio signal change as set.

Another sound quality control circuit according to the present invention includes a plurality of filter circuits provided between an audio signal line and a ground or power supply line and for blocking a predetermined frequency component from the audio signal, and a plurality of filter circuits. A plurality of switch elements connected in series to each other, a volume control unit for adjusting the level of the audio signal, and controlling the on / off of the plurality of switch elements according to the setting of the sound quality mode and controlling the volume according to the set value of the volume A sound quality control circuit for controlling the adjustment unit, wherein the sound quality control circuit determines a relationship between the set value of the sound volume and the sound volume adjustment value in order to keep the sound volume level on the audibility to a change in the sound quality mode setting. Is prepared in advance for each sound quality mode, and a volume adjustment value corresponding to the current sound volume setting value is obtained from the data table corresponding to the sound quality mode setting. , And the configuration for controlling the sound volume adjustment section based on the sound volume adjustment value.

In such a configuration, when the setting of the sound quality mode is changed, the frequency characteristic of the audio signal changes in the same manner as described above, but at the same time, the level of the audio signal also changes.

That is, when the setting of the sound quality mode is changed,
In response to this, the sound quality control circuit operates, and the sound quality mode of the sound quality mode indicates a relationship between a sound volume setting value and a sound volume adjustment value prepared in advance to make the sound volume level on the audibility constant against a change in the sound quality mode setting. From the data table, a sound volume adjustment value according to the current sound volume setting value is obtained. The volume control unit is controlled based on the volume control value, and the level of the audio signal changes. Therefore, even if the setting of the sound quality mode is changed, the audible volume level of the reproduced sound reproduced by the audio signal is kept constant.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a sound quality control circuit according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a sound quality control circuit of the television receiver, and FIG. 2 explains data contents of a data table showing a relationship between a set value of a sound volume and a sound volume adjustment value recorded in a memory in the control circuit of the television receiver. FIG. 3 is a flowchart of software executed by the control circuit.

The sound quality control circuit A described here by way of example is provided in a sound processing circuit of a television receiver, and has a sound quality mode changeover switch 60 disposed on a front panel (not shown). When the setting of the sound quality mode (here, three types of high-sound emphasis, normal, and low-sound emphasis) is changed through the operation, the frequency characteristic of the audio signal (audio) extracted from the synthesized video signal is changed accordingly. It has a configuration. The audio signal (audio) that has passed through the sound quality control circuit A is supplied to the amplifier 40.
Via the speaker 50.

The sound quality control circuit A includes an attenuator 10 (corresponding to a volume control unit) for adjusting the level of an audio signal, and an audio signal (a) output from the attenuator 10.
and a control circuit 30 for controlling the attenuator 10 and the sound quality switching circuit 20 based on the output of the sound quality mode changeover switch 60 and the like (including a function as a sound quality control circuit). It is composed of

The attenuator 10 is an electronic volume in which a plurality of resistors and a multiplexer are combined. The attenuator 10 switches the selection of the multiplexer according to the volume control signal a generated by the control circuit 30 to change the resistance voltage division ratio. Thus, the amount of attenuation of the audio signal (audio) is changed in multiple stages.

Here, the level of the audio signal (audio) is changed using the attenuator 10, but an amplifier circuit having a function of changing the gain according to the volume control signal a may be used.

The sound quality switching circuit 20 outputs an audio signal (aud)
io) are configured by filter circuits 21 to 23 for cutting predetermined frequency components, and transistors Q1 and Q2 (corresponding to switch elements) for switching operation and non-operation of the filter circuits 21 and 23.

The filter circuit 21 is provided on the audio signal line, and is a circuit in which a resistor R1 and a capacitor C1 are connected in series. The filter circuit 22 is provided between the audio signal line (the input side of the filter circuit 22) and the ground line, and is a circuit in which a resistor R2 and a capacitor C2 are connected in parallel. The filter circuit 22 is provided between the audio signal line (the output side of the filter circuit 22) and the ground line, and is a circuit including a capacitor C3.

The transistors Q1 and Q2 have their emitters grounded, and the bases receive the sound quality switching signals b and c output from the control circuit 30. That is, the transistors Q1 and Q2 are switched on and off by the sound quality switching signals b and c.

When both of the transistors Q1 and Q2 are on, the filter circuits 21 and 23 operate, and the filter circuits 21 to 23 become π type as a whole, thereby performing a filtering process on the audio signal (audio). .
On the other hand, when both the transistors Q1 and Q2 are off, the filter circuits 21 and 23 do not operate, and the filter circuit 22 filters the audio signal (audio).

On the other hand, when the transistor Q1 is on and the transistor Q2 is off, the filter circuit 21 operates and the filter circuit 22 does not operate, and the filter circuits 21 and 22 become T-type as a whole.
The filter processing of o) is performed. The same applies to the case where the transistor Q1 is off and the transistor Q2 is on, and the filters 22 and 23 filter the audio signal (audio).

When the transistors Q1 and Q2 are turned on and off through the signals b and c, the frequency characteristics of the audio signal (audio) change, and the sound quality of the audio reproduced by the speaker 50 changes accordingly. Will do.

The sound quality switching circuit 20 is not limited to the above circuit configuration. A plurality of filter circuits may be connected to the audio signal line and the ground line (the audio signal line and the power supply line when the polarity of the audio signal (audio) is negative). Any configuration may be used as long as the configuration is such that the frequency characteristics of the audio signal (audio) can be changed by switching the operation / non-operation of these filter circuits by a switch element.

The control circuit 30 is a microcomputer for controlling the whole of the television receiver in accordance with a remote operation of the remote controller 10 or the like. The I / O port is connected to the attenuator 10 and the sound quality switching circuit 20 as described above, as well as the sound quality mode changeover switch 60 and the remote control sensor 80.

The remote controller 10 is for remotely controlling the video device. The remote controller 10 emits an infrared LED or the like in response to an operation result of an operation button (not shown), and transmits an operation code signal by this light emission. . The remote control 10 includes operation buttons for performing channel switching, volume adjustment, and the like. Although not shown, operation buttons having exactly the same functions as the operation buttons of the remote controller 10 are also provided on the front panel of the television receiver.

An operation code signal transmitted as infrared light from the remote controller 10 is received by the remote controller sensor 80.
The remote control sensor 80 is a light receiving LED for infrared rays, converts the received operation code signal into an electric signal,
Output to

A data table as shown in FIG. 2 is recorded in a memory in the control circuit 30 in advance. This data table is prepared in advance for each sound quality mode in order to keep the sound volume level of the sound reproduced by the speaker 50 perceptible even when the setting of the sound quality mode is changed by operating the sound quality switch 60. , The relationship between the volume setting value and the volume adjustment value is represented as a binary data pair.

The control circuit 30 has a function of controlling the sound quality control circuit A, and a program shown in FIG. 3 is prepared to exhibit this function. Hereinafter, the contents of this program will be described with reference to the same drawing, and the operation of the sound quality control circuit A will also be described.

When the setting of the sound quality mode is changed by operating the sound quality switch 60, an interrupt program shown in FIG. 3 is processed.

First, the setting of the sound quality mode input from the sound quality switch 60 is input (S1), and sound quality switching signals b and c for switching the transistors Q1 and Q2 on and off are generated according to the setting (S2). ).

Setting of sound quality mode and transistors Q1, Q
The relationship between ON and OFF of 2 is determined in accordance with the circuit configuration of the sound quality switching circuit 20, particularly the circuit constants of the filter circuits 20 to 23. Here, when the sound quality mode is set to low tone emphasis, the transistors Q1 and Q2 are both turned on. When the sound quality mode is set to normal, the transistors Q1 and Q2 are turned on and Q2 is turned off. A switching signal is generated.

The sound quality switching signals b and c from the control circuit 30
Is output, the transistors Q1, Q2
Is switched on and off.

Thereafter, a sound volume adjustment value corresponding to the current sound volume setting value is obtained by referring to the set data table of the sound quality mode among the data tables recorded in the memory (S3).

For example, assuming that the setting of the sound quality mode is treble emphasis and the current sound volume setting value temporarily stored in the control circuit 30 is L1, as shown in FIG.
A volume adjustment value AD1 is obtained with reference to the data table for treble enhancement. When the sound quality mode is set to normal, a data table for normal is read, and a volume adjustment value of AD3 is obtained by referring to the data table.

Next, a volume control signal a obtained by performing binary conversion and inverting the volume adjustment value obtained as described above.
Is generated (S4), and this program ends.

When the volume control signal a is attenuator 1
0, the audio signal (au) of the attenuator 10
dio) is a value inversely proportional to the volume adjustment value. That is, the level of the audio signal (audio) is proportional to the volume adjustment value.

The frequency characteristics of the audio signal (audio) whose level has been adjusted by the attenuator 10 change according to the setting of the audio quality mode by the audio quality switching circuit 20, and the audio signal (audio) processed in this manner is amplified. The signal is output to the speaker 50 via the speaker 40, and is reproduced as a broadcast sound here.

For example, when the setting of the sound quality mode is changed from treble emphasis to normal, simply changing the frequency characteristics of the audio signal (audio) tends to decrease the sound volume level in the sense of hearing.

However, in the case of the sound quality control circuit A, as shown in FIG. 2, even if the setting of the sound quality mode is changed from treble emphasis to normal, the volume adjustment value obtained by the control circuit 30 increases from AD1 to AD3. As a result, the level of the broadcast sound reproduced from the speaker 50 increases,
The perceived volume level is kept constant. The same applies to other sound quality modes. This means that even if the setting of the sound quality mode is changed, it is not necessary to correct the volume setting by operating the remote controller 70 or the like.

Therefore, the performance as a television receiver is improved, and the usability is improved. In addition, since the circuit configuration of the sound quality control circuit A is very simple, the cost can be reduced in this respect.

When the volume setting is changed by operating the remote controller 70 or the like, another interrupt program is executed. The basic contents are substantially the same as steps 3 and 4 of the interrupt program shown in FIG.

That is, as shown in FIG. 2, when the sound quality mode is set to high tone emphasis and the sound volume setting value is changed from L1 to L
When it is changed to 2, the data table for treble emphasis is referred to, the volume adjustment value changes from AD1 to AD2, and as a result, the level of the audio signal (audio) increases and the broadcast reproduced by the speaker 50 The volume of the sound increases.

The sound quality control circuit of the present invention is not limited to a television receiver, but can be applied to audio equipment such as a video device. Further, the function as the sound quality control circuit may be realized by hardware.

[0042]

As described above, in the case of the sound quality control circuit according to the first aspect of the present invention, it is possible to reduce the cost because the frequency characteristic of the audio signal can be changed while having a very simple circuit configuration. Can be.

In the case of the sound quality control circuit according to the second aspect of the present invention, while having a very simple circuit configuration,
Not only can the frequency characteristics of the audio signal be changed, but even if the setting of the sound quality mode is changed, the audible volume level does not change, so that it is not necessary to modify the volume setting, and the usability is improved. That is, cost reduction and higher performance of the circuit can be achieved.

[Brief description of the drawings]

FIG. 1 is a diagram for describing an embodiment of the present invention, and is a block diagram of a sound quality control circuit of a television receiver.

FIG. 2 is a graph for explaining the contents of a data table showing a relationship between a sound setting value and a volume adjustment value recorded in a memory in a control circuit of the sound quality control circuit.

FIG. 3 is a flowchart of software processed by the control circuit.

[Explanation of symbols]

 A sound quality control circuit 10 attenuator 20 sound quality switching circuit 21, 22, 23 filter circuit Q1, Q2 transistor 30 control circuit 60 sound quality mode switching switch 70 remote control

Claims (2)

[Claims] 1. A plurality of filter circuits provided between an audio signal line and a ground or power supply line for blocking a predetermined frequency component from an audio signal, and a plurality of filter circuits respectively connected in series to the plurality of filter circuits. A sound quality control circuit comprising: a switch element; and a sound quality control circuit that controls on / off of a plurality of switch elements according to a setting of a sound quality mode. 2. A plurality of filter circuits provided between an audio signal line and a ground or power supply line for blocking a predetermined frequency component from the audio signal, and a plurality of filter circuits connected in series to the plurality of filter circuits, respectively. A switch element, a volume control unit for adjusting the level of the audio signal, and a sound quality control circuit for controlling on / off of the plurality of switch elements according to the setting of the sound quality mode and controlling the volume control unit according to the set value of the volume. The sound quality control circuit has a data table indicating a relationship between the set value of the sound volume and the sound volume adjustment value in advance for each sound quality mode in order to keep the sound volume level on the audibility constant against the change of the sound quality mode setting. A volume adjustment value corresponding to the current volume setting value is obtained from a data table corresponding to the setting of the sound quality mode, and the volume adjustment unit is provided based on the volume adjustment value. A sound quality control circuit characterized by being configured to be controlled.