JPH06205085A - Sound volume adjusting device - Google Patents

Abstract

PURPOSE:To adjust the output sound volume at the optimum state by adjusting an amplification factor corresponding to the size of an audio input signal. CONSTITUTION:An audio signal is inputted to the input terminal of an operational amplifier 3 which constitutes an amplifier, and the terminal on the other side is connected to a reference power source Vref1, and also, it is connected to the output terminal via a resistor. A switch 7 is connected to a resistor 6 in parallel, and the resistor 6 is short-circuited by an on-operation. While, the audio input signal is generated setting rectifid output half-wave rectified by a rectifier circuit 17 as comparative output, and it is connected to comparators 18, 19. The comparator 18 is connected to a reference power source Vref2, and the comparator 19 to a reference power source Vref3, and when the comparative output is located between two reference values, the switch 7 is turned on by the output of a NOR 20, which changes the amplification factor for the audio input signal. Therefore, input with low level such as a dark noise, etc., and a large sound can be suppressed, and also, the sound can be compensated appropriately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a volume adjusting device used for volume adjustment of a telephone or the like.

[0002]

2. Description of the Related Art Conventionally, some telephones have a volume adjusting function for optimally adjusting the volume of a received voice.

However, conventionally, in the volume control device used in such a telephone, the voice input signal given from the exchange side is amplified by the amplifier and is output from the handset. In this case, the amplification factor of the amplifier is
The call volume is set to maximum when the audio input signal is maximum.

[0004]

However, in such a configuration, when the voice input signal becomes small due to the influence of the line quality or the like, the received sound volume also becomes small accordingly. This causes a problem that if the voice input signal becomes extremely small, the conversation becomes distant and the contents of the conversation cannot be understood.

The present invention has been made in view of the above circumstances, and provides a volume adjusting device capable of adjusting an output volume to an optimum state by adjusting an amplification factor according to the size of a voice input signal. With the goal.

[0006]

The present invention comprises means for generating a comparison output corresponding to a voice input signal, and two reference values set to different values, the value of the comparison output being the two reference values. Means to change the output when it lies between the values,
And a means for changing the amplification factor for the voice input signal according to the change of the output of this means.

Further, according to the present invention, means for generating a comparison output corresponding to a voice input signal and means for selecting two reference values set to different values according to the value of the comparison output generated by this means. And means for changing the output when the value of the comparison output is located between the two selected reference values, and means for changing the amplification factor for the voice input signal by the change in the output of the means. ing.

[0008]

As a result, according to the present invention, when the comparison output corresponding to the voice input signal is located between two reference values set to different values, the amplification factor for the voice input signal is changed. Therefore, it is possible to suppress unnecessarily large voice input including low-level input such as background noise, and for proper voice input signal, even if the call becomes small due to circuit quality etc. Can be compensated for, and the inconvenience that the conversation becomes distant and the contents of the conversation cannot be understood is eliminated.

Further, according to the present invention, two reference values set to different values according to the value of the comparison output corresponding to the voice input signal are selected, and the comparison output is positioned between these two reference values. In this case, since the amplification factor for the voice input signal is changed, the amplification factor of the operational amplifier can be changed by the optimum reference value according to the input voice signal, and the voice input signal can be accurately compensated.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of the same embodiment. In the figure, 1 is an input terminal to which an audio input signal is given, and this input terminal 1 is connected to one input terminal of an operational amplifier 3 which constitutes an amplifier via a capacitor 2.

The operational amplifier 3 has a resistor 4 at the other input terminal.
Is connected to the reference power source Vref 1 via
And the resistor 6 to the output terminal. In this case, a switch 7 is connected in parallel with the resistor 6, and the ON operation of the switch 7 allows the resistor 6 to be short-circuited.

Thus, the operational amplifier 3 sets the amplification factor A0 to ((R2 + R3) / R1) +1 when the switch 7 is off and the resistor 6 is connected, and the resistor 6 is short-circuited when the switch 7 is on. The amplification factor A0 (R
2 / R1) +1. Where R1
Indicates the resistance value of R4, R2 indicates the resistance value of R5, and R3 indicates the resistance value of the resistance 6, respectively.

The output terminal of the operational amplifier 3 is grounded through a series circuit of a resistor 8, a resistor 9 and a resistor 10. The connection point between the output terminal of the operational amplifier 3 and the resistor 8 and the resistor 8
The connection points of 9 and 9 and the connection points of resistors 9 and 10 are respectively connected to the fixed contacts 11a, 11b and 11c of the changeover switch circuit 11.

The changeover switch circuit 11 includes a movable contact 11
Fixed contacts 11a, 11b, 11c by switching operation of d
It is designed to select one. The movable contact 11d of the changeover switch circuit 11 is connected to the limit circuit 13 via the amplifier 12.

The limit circuit 13 suppresses the amplitude of the output signal from the operational amplifier 3 so as not to exceed the maximum volume standard value of the telephone when the voice input signal suddenly becomes large.

The output terminal of the limit circuit 13 is connected to the speaker (receiver) 15 via the speaker drive circuit 14.
Connected to.

On the other hand, the input terminal 1 to which the audio input signal is applied is connected to the rectifying circuit 17 via the amplifier 16. The rectifier circuit 17 includes diodes 171, 172,
It is composed of a capacitor 173 and a resistor 174 so that a rectified output obtained by half-wave rectifying an audio input signal is generated as a comparison output.

The output terminal of the rectifier circuit 17 is connected to one input terminal of each of the comparators 18 and 19. In this case, the comparator 18 supplies the reference power source Vref 2 to the other input terminal.
When the comparison output from the rectifying circuit 17 is lower than the potential of the reference power supply Vref 2, the “L” level is output, and when it is higher than the potential of the reference power supply Vref 2, the “H” level is output. Similarly, the comparator 19 has the reference power source Vref3 connected to the other input terminal, and the rectifier circuit 17
When the comparison output from is lower than the potential of the reference power supply Vref 3, the “L” level is output, and when it is higher than the potential of the reference power supply Vref 3, the “H” level is output. in this case,
The reference power source Vref 2 and the reference power source Vref 3 are set with different potentials. Here, the reference power source Vre
f 2 is set to a potential required to suppress background noise,
The reference power source Vref 3 is set to a potential required to suppress a sufficiently large voice input.

The output terminals of the comparators 18 and 19 are connected to the input terminals of an inverting exclusive OR circuit (Exclusive NOR: hereinafter referred to as E.NOR) 20. And E. N
The output terminal of the OR20 is connected to the switch 7, and E.O. NOR
When the output of 20 is at "H" level, the switch 7 is turned on.

Next, the operation of the embodiment configured as described above will be described.

When an audio input signal is applied to the input terminal 1, it is applied to one input terminal of the operational amplifier 3 via the capacitor 2 from the input terminal 1.

On the other hand, the voice input signal is given to the rectifier circuit 17. In the rectifier circuit 17, the audio input signal is half-wave rectified by the diodes 171, 172, and a rectified output smoothed by the capacitor 173 and the resistor 174 is generated as a comparison output.

Then, this comparison output is output to the comparators 18, 1
9 is applied to one input terminal respectively.

In this case, the comparator 18 has a reference power source Vre
f 2 is connected, the reference power supply Vref 3 is connected to the comparator 19, and the comparison output from the rectifier circuit 17 is the reference power supply Vref 2, V of each of the comparators 18, 19.
Compared to ref 3.

Here, when the comparison output from the rectifier circuit 17 is smaller than the reference power source Vref 2 as shown in the period t1 in FIG. 2, the output of the comparator 18 is at "L" level and the output of the comparator 19 is output. Becomes "L" level, and E. The output of the NOR 20 becomes "H" level. As a result, the switch 7 is turned on and the resistor 6 connected to the operational amplifier 3 is short-circuited, so that the amplification factor A0 of the operational amplifier 3 becomes (R2 / R1
) Becomes +1.

Then, the amplification factor A0 = by the operational amplifier 3.
The output amplified by (R2 / R1) +1 is given to the changeover switch circuit 11 via the resistors 8, 9, and 10 and reaches the level selected here, and the limit circuit 13 is outputted via the amplifier 12. And is further output from the speaker (receiver) 15 via the speaker drive circuit 14.

Next, when the comparison output from the rectifier circuit 17 is larger than the reference power supply Vref 2 and smaller than the reference power supply Vref 3 as shown in the period t2 of FIG. 2, the output of the comparator 18 is at the "H" level. Then, the output of the comparator 19 also becomes the "L" level, and the E. The output of the NOR 20 becomes "L" level. As a result, the switch 7 is turned off, and the short circuit of the resistor 6 connected to the operational amplifier 3 is released. Therefore, the amplification factor A0 of the operational amplifier 3 is ((R2 + R3) / R1) +
The value becomes 1, and the amplification factor A0 increases by (R3 / R1) from the above.

Then, the amplification factor A is set by the operational amplifier 3.
The output amplified by 0 = ((R2 + R3) / R1) +1 is given to the changeover switch circuit 11 via the resistors 8, 9, and 10 and reaches the level selected here, and the amplifier 12 is turned on. It is sent to the limit circuit 13 via the speaker drive circuit 14 and then output from the speaker (receiver) 15 via the speaker drive circuit 14.

By the way, when the input voice signal suddenly becomes large and the output change from the rectifier circuit 17 cannot follow this, the limit circuit 13 limits the amplitude of the output signal from the operational amplifier 3. That is, the output amplitude is suppressed and controlled so as not to exceed the maximum volume standard value of the telephone, and an adverse effect on the ear is prevented. Further, in this case, the filter built in the limit circuit 13 dulls the clamped waveform to suppress the distortion.

Further, when the comparison output from the rectifying circuit 17 is larger than the reference power supply Vref 3 as shown in the period t3 in FIG. 2, the output of the comparator 18 is at "H" level and the comparator 1
The output of 9 also goes to the "H" level, and the E. The output of the NOR 20 becomes "H" level. As a result, the switch 7 is turned on and the resistor 6 connected to the operational amplifier 3 is short-circuited, so that the amplification factor A0 of the operational amplifier 3 is (R2 / R1).
It becomes +1.

The amplification factor A is obtained by the operational amplifier 3.
The output amplified by 0 = (R2 / R1) +1 is the resistance 8,
It is given to the changeover switch circuit 11 via the resistors 9 and 10 and reaches the level selected here, and the amplifier 12
Is sent to the limit circuit 13 via the speaker driving circuit 14 and further output from the speaker (receiver) 15 via the speaker driving circuit 14.

Therefore, in this way, the rectifying circuit 17
When the comparison output from is apparently dark noise and is smaller than the reference power supply Vref 2, the amplification factor A0 of the operational amplifier 3 can be suppressed to a small value, and unnecessary noise output can be minimized. .

Further, the comparison output from the rectifying circuit 17 corresponding to the proper audio input signal is the reference power supplies Vref 2 and Vref 3.
If it is between the two, the amplification factor A0 of the operational amplifier 3 can be increased, so that even if the call becomes extremely small due to the circuit quality and the like, it becomes possible to compensate for this, and the call becomes far, The inconvenience of not being able to understand the conversation content is eliminated, and the call volume with excellent intelligibility can be generated. Then, when the input audio signal suddenly becomes large, the limit circuit 13 limits the amplitude of the output signal from the operational amplifier 3 to prevent an adverse effect on the ear. further,
By suppressing the distortion of the voice by blunting the waveform clamped by the filter of the limit circuit 13, it is possible to minimize the deterioration of the intelligibility of the call.

Further, when the comparison output from the rectifier circuit 17 becomes very large and is larger than the reference power supply Vref3, the amplification factor A0 of the operational amplifier 3 can be kept small, so that the call volume becomes unnecessarily large. Can be suppressed and distortion of the call voice can be suppressed.

Next, FIG. 3 shows a schematic structure of another embodiment of the present invention. In FIG. 3, the same parts as those in FIG. 1 are designated by the same reference numerals.

In this case, the output terminal of the rectifying circuit 17 is A /
The D converter 21 is connected. In addition, the comparators 18 and 19
The reference power source selection circuit 22 is connected to the other input terminal of the.

The A / D converter 21 generates a digital output according to the magnitude of the rectified output of the rectifying circuit 17 according to the audio input signal. Here, whether the rectified output is larger or smaller than a predetermined level. Two kinds of digital outputs that represent Then, this digital output is given to the reference power source selection circuit 22.

As shown in FIG. 4, the reference power source selection circuit 22 connects a series circuit of resistors 23, 24, 25, 26 and 27 between the power source V and ground, and connects the connection point of the resistors 23 and 24 to the resistor 24. The connection point of 25 is commonly connected through switches 28 and 29, and this connection point is connected to the reference power source Vref.
3 is connected to the other input terminal of the comparator 19, and
The connection point of the resistors 25 and 26 and the connection point of the resistors 26 and 27 are commonly connected through the switches 30 and 31, respectively, and this connection point is connected to the other input terminal of the comparator 18 as the reference power supply Vref 2. ing. And switch 2
8 and 30 A / D when the rectified output is larger than a predetermined level
It is turned on by the digital output of the converter 21, and the switches 29 and 31 are turned on when the rectified output is smaller than a predetermined level.
The digital output of the / D converter 21 is used to turn it on.

In addition, a series circuit of resistors 8, 9, and 10 shown in FIG. 1, a changeover switch circuit 11, an amplifier 1
2, the limit circuit 13, the speaker drive circuit 14, and the speaker (receiver) 15 are removed.

In this way, when a voice input signal is given to the rectifier circuit 17 from the input terminal 1 and a rectified output is generated from the rectifier circuit 17, this rectified output is applied to one input terminal of the comparators 18 and 19 as a comparison output. Given. Also, A
A digital output indicating whether the rectified output of the rectifier circuit 17 is larger or smaller than a predetermined level is generated from the / D converter 21, but if it is smaller than the predetermined level, the digital output at this time causes the reference power source selection circuit. In 22,
The switches 29 and 31 are turned on.

As a result, the potential at the connection point between the resistors 26 and 27 is supplied to the other input terminal of the comparator 18 as the reference power supply Vref 2, and the potential at the connection point between the resistors 24 and 25 is compared as the reference power supply Vref 3. Is supplied to the other input terminal of the rectifier circuit 19 and is compared with the comparative output of the rectifier circuit 17 as described above. As shown in FIG. 5, the comparative output of the rectifier circuit 17 is applied to the reference power sources Vref 2 and Vref. When it is between 3, the amplification factor A0 of the operational amplifier 3 is changed to be large.

When the rectified output from the rectifying circuit 17 is higher than a predetermined level, the digital output at this time turns on the switches 28 and 30 in the reference power source selecting circuit 22.

As a result, the potential at the connection point between the resistors 25 and 26 is applied to the other input terminal of the comparator 18 as the reference power supply Vref 2 ', and the potential at the connection point between the resistors 23 and 24 is the reference power supply Vref 3'. Is applied to the other input terminal of the comparator 19, and as described above, the rectifier circuit 1
7 is compared, and the comparison output of the rectifier circuit 17 is compared with the reference power sources Vref 2'and Vref 3'as shown in FIG.
If it is between the two, the amplification factor A0 'of the operational amplifier 3 is changed to be large.

Therefore, with this configuration, the reference power source Vref having a different value depending on whether the rectified output of the rectifier circuit 17 according to the voice input signal is higher or lower than a predetermined level.
Since 2 and Vref 3 are selected, the amplification factor of the operational amplifier 3 can be changed according to the optimum reference value according to the input audio signal, and the audio input signal can be accurately compensated. It is possible to generate a call volume with higher clarity.

The present invention is not limited to the above-mentioned embodiments, and can be carried out by appropriately modifying it within the scope of the invention. For example, in the embodiment shown in FIG.
The reference power supplies Vref 2 and Vref 3 are provided for the above, and the case where the amplification factor of the operational amplifier 3 is changed in two steps by these reference power supplies Vref 2 and Vref 3 has been described, but it is different for two or more comparators. If a reference power source is prepared and the number of switching of the feedback resistance of the operational amplifier 3 is increased based on the comparison result of these comparators, the amplification factor can be finely changed with respect to the comparison output from the rectifier circuit, and the audio input signal can be changed. You can get the optimum call volume according to the size of the. FIG. 6 shows a case where five reference power supplies Vref2 to Vref6 are prepared, and shows how the amplification factor A0 is finely changed with respect to the comparison output from the rectifier circuit.

[0047]

According to the present invention, when the comparison output corresponding to the voice input signal is located between the two reference values set to different values, the amplification factor for the voice input signal is changed. Therefore, it is possible to suppress unnecessarily large voice input including low level input such as background noise.
For a proper voice input signal, even if the call becomes small due to the circuit quality etc., this can be compensated, and the inconvenience such as the call becoming distant and the content of the conversation becoming incomprehensible disappears, and it becomes clear. It can generate an excellent call volume.

Further, according to the present invention, two reference values which are set to different values according to the value of the comparison output corresponding to the voice input signal are selected, and the comparison output is positioned between these two reference values. In this case, since the amplification factor for the voice input signal is changed, the amplification factor of the operational amplifier can be changed by the optimum reference value according to the input voice signal to accurately compensate the voice input signal. It is possible to generate a call volume with excellent intelligibility.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of one embodiment.

FIG. 3 is a diagram showing a schematic configuration of another embodiment of the present invention.

FIG. 4 is a diagram showing a schematic configuration of a reference power source selection circuit of another embodiment.

FIG. 5 is a diagram for explaining the operation of another embodiment.

FIG. 6 is a diagram for explaining the operation of another embodiment of the present invention.

[Explanation of symbols]

1 ... Input terminal, 2 ... Capacitor, 3 ... Operational amplifier, 4,
5, 6, 8, 9, 10, 23-27 ... Resistance, 7, 28-
31 ... Switch, 11 ... Changeover switch circuit, 12, 1
6 ... Amplifier, 13 ... Limit circuit, 14 ... Speaker drive circuit, 15 ... Speaker (receiver), 17 ... Rectifier circuit,
171, 172 ... Diode, 173 ... Capacitor, 1
74 ... Resistance, 18, 19 ... Comparator, 20 ... Inversion exclusive OR circuit, 21 ... A / D converter, 22 ... Reference power source selection circuit.

Claims (2)

[Claims] 1. A means for generating a comparison output corresponding to an audio input signal, and having two reference values set to different values, wherein the value of the comparison output is located between the two reference values. A volume adjusting device comprising: a means for changing an output; and a means for changing an amplification factor for the voice input signal according to a change in the output of the means. 2. A means for generating a comparison output corresponding to an audio input signal; a means for selecting two reference values set to different values according to the value of the comparison output generated by the means; It is provided with means for changing the output when the output value is located between the two selected reference values, and means for changing the amplification factor for the audio input signal according to the change in the output of the means. And volume control device.