JPH11136347A - Telephone set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the change of a sidetone level which is generated by control of a receiving talk volume by changing the leakage quantity of a sidetone circuit in a direction of making the change of a sidetone level small, in response to the change of an amplification factor of a gain variable amplifying part. SOLUTION: When a detection result of a receiving talk level detecting part 8 is lower than a reference level because talk voice of the other party is small, a volume controlling part 9 closes both the connections of switches S5 and S6 and makes the amplification factor of a gain variable amplifying part 4 one stage higher. Because of this, the amplification factor of the part 4 becomes large by 10db and becomes the largest amplification factor. Also, at the same time, the part 9 opens the connection of a switch S2 and also closes the connection of a switch S3. Because of this, leakage quantity of a sidetone circuit 3 reduces only by 10db and becomes the smallest leakage quantity. As a result, voice of the other party that is emitted from a loudspeaker 7 becomes large and turns into a volume level of a prescribed level that is easy to be heard. On the other hand, the level of a voice of a caller himself is maintained constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a telephone connected to a wired line or a telephone such as a portable telephone connected to a wireless line. It relates to a telephone to be adjusted.

[0002]

2. Description of the Related Art When talking with a partner using a telephone, the line length with the partner, the volume of the voice of the partner,
In some cases, the volume of the loudspeaker becomes too high, and in other cases, the volume of the speaker becomes too low, making it difficult to hear the other party's talk. A conventional technique for solving such inconvenience is disclosed in Japanese Utility Model Laid-Open No. 6-1537.
No. 0 is proposed. That is, in this technology,
An automatic volume control circuit is provided between the input and the output of the speaker amplifier. Then, based on the comparison result between the output of the receiving speaker and the reference value, control is performed so that the receiving sound volume of the receiving speaker is optimized.

In the prior art proposed in Japanese Patent Application Laid-Open No. 5-252253, an unnecessary noise component is reduced from a signal guided through a telephone line by providing a noise filter for removing a signal outside a voice band signal. Has been removed. By controlling the gain of the amplifying unit that amplifies the signal from which the noise component has been removed, the received signal can be easily heard.

In the prior art proposed in Japanese Patent Application Laid-Open No. 4-351144, a first method for determining the volume of a communication partner is disclosed.
And second determining means for determining the volume around the handset. Then, the reception sound volume is maintained at an appropriate value by changing the reception sound volume based on the judgment result by the first judgment means and the judgment result by the second judgment signal.

[0005]

However, in the case where the above-mentioned conventional technology is used, the following problems have occurred.
That is, a configuration is used in a telephone in which a signal from a transmission microphone is leaked to a signal path of a reception signal. In addition, in order to reduce the number of elements in the amplifier circuit, the amplifier circuit that amplifies the reception signal and drives the speaker
A circuit made into an IC is used. Therefore, the signal leaked from the sidetone circuit is guided to the input side of the amplifier circuit whose amplification factor changes. On the other hand, in the prior art, the amplification factor of the amplifier circuit is changed in order to set the reception sound volume to an appropriate value. Therefore, when the amplification factor of the amplifier circuit is changed, the sidetone level changes. As a result, since the other party's voice is low, when the amplification factor of the amplifier circuit is increased, the sidetone level also increases. Further, since the voice of the other party is loud, when the gain of the amplifier circuit is reduced, the sidetone level also decreases. For this reason, there has been a problem that the voice of the sender himself or herself emitted from the receiving speaker becomes too loud or too low.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to change a side tone level in response to a change in the amplification factor of a variable gain amplifier. Accordingly, it is an object of the present invention to provide a telephone capable of suppressing a change in side tone level caused by control of a receiving sound volume.

Another object of the present invention is to provide, in addition to the above object, a configuration in which the amplification factor of the variable gain amplifier and the leakage amount of the side tone circuit are changed stepwise in order to simplify the circuit configuration. It is another object of the present invention to provide a telephone capable of reducing the unnaturalness of the change in the received sound volume even when the call is received.

[0008]

In order to solve the above-mentioned problems, a telephone according to the first aspect of the present invention guides a reception signal to a speaker via a variable gain amplifier and changes a transmission signal from a microphone to a variable gain. A reception level detection unit for detecting a level of the reception signal, which is applied to a telephone leaking to an input path of an amplification unit, and a sidetone which can change a leakage amount of the transmission signal leaking to an input path of a variable gain amplification unit. Circuit, by controlling the gain of the variable gain amplifying unit based on the comparison result between the detection result of the receiving level detection unit and a preset reference level, to set the volume of the speaker to a predetermined level. A volume control unit that reduces the leakage amount of the sidetone circuit when increasing the gain of the variable gain amplifier, and increases the leakage amount of the sidetone circuit when decreasing the amplification ratio of the variable gain amplifier. Has a configuration was. That is, when the gain of the variable gain amplifier increases, the leakage amount of the side tone circuit decreases. Also, when the gain of the variable gain amplifier is reduced, the leakage amount of the side tone circuit increases. For this reason, the sidetone level at the output of the variable gain amplifier does not change despite the change in the amplification factor of the variable gain amplifier. Therefore,
The sidetone level is always maintained at an appropriate value even when control is performed to maintain the volume of the other party emitted from the speaker at an appropriate level.

The telephone according to the second aspect of the present invention,
In addition to the above configuration, the variable gain amplifying unit is applied to a telephone that changes the amplification factor in a stepwise manner and the side tone circuit changes the leakage amount in a stepwise manner, wherein the reference level is a first reference level; The volume control unit sets two types of reference levels, a second reference level set to a level lower than the first reference level, and a gain when a detection result of the reception level detection unit is higher than the first reference level. The gain of the variable amplifying unit is reduced stepwise, and the leakage amount of the side tone circuit is increased in a stepwise manner. When the detection result becomes lower than the second reference level, the gain of the variable gain amplifying unit is reduced stepwise. And the amount of leakage of the sidetone circuit is reduced stepwise. That is, when the level of the received signal is within the range between the first reference level and the second reference level, the gain of the variable gain amplifier does not change. Therefore, the degree to which the gain of the variable gain amplifier changes varies.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
This will be described with reference to the drawings. FIG. 1 is a block diagram showing an electric configuration of a telephone according to an embodiment of the present invention.

In FIG. 1, a public telephone line 21, which is a wired line, is led to a primary coil of an insulating transformer 2 via a diode bridge 1 for correcting polarity. One terminal of the secondary coil of the transformer 2 is connected to the network unit 11 via the capacitor C1. The other terminal of the secondary coil of the transformer 2 is grounded. The microphone 6 is a transmitter provided in the handset, and the output of the microphone 6 is amplified by the amplifier 5. Then, the amplified signal is guided to the network unit 11 as a transmission signal.

The network unit 11 connects a two-wire signal in which a transmission signal path and a reception signal path are superimposed to a transmission signal path from which an output from the amplifier 5 is guided and an input of the variable gain amplifier 4. This is a block for converting into a four-wire signal path including a received signal path. Also, the signal on the transmission signal path is leaked to the reception signal path.

The impedances Z1 to Z3 are circuits connected to the network unit 11 through switches S1 to S3 provided corresponding to the impedances Z1 to Z3, and determine the amount of transmission signal leakage in the network unit 11. I do. That is, when only the connection of the switch S1 is closed and the impedance Z1 is connected to the network unit 11, the amount of leakage in the network unit 11 becomes maximum.
When only the switch S2 is closed and the impedance Z2 is connected to the network unit 11,
The amount of leakage in the network unit 11 has an intermediate value. When only the connection of the switch S3 is closed and the impedance Z3 is connected to the network unit 11, the amount of leakage of the network unit 11 is minimized.

That is, the block 3, which comprises the network unit 11, the impedances Z1 to Z3, and the switches S1 to S3, changes the amount of leakage of the transmission signal to the input path of the variable gain amplification unit 4 in three stages. It is a sidetone circuit that can be used. The amount of leakage changes in 10 db steps.

The reception signal path output from the network unit 11 is guided to the minus input of the OP amplifier 12 via three resistors R1 to R3 connected in series.
A resistor R4 is connected between the output terminal of the OP amplifier 12 and the negative input. A switch S5 is connected in parallel to the resistor R2, and a switch S6 is connected in parallel to the resistor R3. Then, the OP amplifier 12
Is connected to the reference voltage V. Also,
An output terminal of the OP amplifier 12 is guided to a speaker 7 which is a receiver provided in the handset.

That is, the block 4 including the four resistors R1 to R4, the two switches S5 and S6, and the OP amplifier 12 has a gain whose amplification factor changes in three stages according to the connection state of the switches S5 and S6. It is a variable amplifier. When both the switches S5 and S6 are closed, the gain of the variable gain amplifying section 4 becomes maximum. Also,
When the connection of the switch S5 is opened and the connection of the switch S6 is closed, the amplification factor becomes an intermediate value. Further, when both the connections of the switches S5 and S6 are opened, the amplification factor becomes minimum. Note that the amplification factor changes in 10 db steps.

The receiving level detecting section 8 includes a variable gain amplifying section 4.
Is a block for detecting the level of the received signal based on the output level of the received signal. Therefore, the signal sent from the variable gain amplifier 4 to the speaker 7 is detected and rectified.
Then, a signal obtained by the detection and rectification is sent to the volume control unit 9 as a detection result.

The volume control section 9 is a block mainly composed of software executed by a microcomputer having a D / A converter. And
Based on the comparison result between the reception level detection unit 8 and the reference level, the control unit controls the volume of the speaker 7 to be a predetermined level. Further, even when the volume control is performed, control for preventing the level of side sounds from changing is also performed.

More specifically, the volume controller 9 stores a first reference level as a reference level. Also, a level 10 db lower than the first reference level is set to the second reference level.
Is stored as the reference level. In order to change the gain of the variable gain amplifying section 4 stepwise, the switch S
In order to control the connection between S5 and S6 and to change the leakage amount in the sidetone circuit 3 stepwise, switches S1 to S6
3 is controlled.

Note that, for the reason described later in detail, the receiving level detector 8 is configured to detect a peak level. The time constant for maintaining the detected peak level is
It is set to a relatively long time, on the order of a few seconds. Also,
Analog switches are used for the five switches S1 to S3, S5, and S6 in order to reduce the size and cost of parts.

The operation of the embodiment having the above configuration will be described below.

In the initial state, the connection of the switch S2 is closed, and the amount of leakage of the transmission signal to the reception signal path is set to an intermediate value. Further, the connection of the switch S5 is opened and the connection of the switch S6 is closed, and the gain of the variable gain amplifier 4 is set to an intermediate value. When a call is started in this state, the volume control unit 9 compares the detection result of the reception level detection unit 8 with the first reference level and the second reference level.
To the reference level. When the detection result falls within the range between the first reference level and the second reference level, the connection state of the switches S1 to S3, S5, and S6 is maintained in the initial state.

On the other hand, when the voice of the other party is loud and the detection result of the reception level detection unit 8 is higher than the first reference level, the volume control unit 9 opens the connection of the switch S6 to perform variable gain amplification. The amplification factor of the unit 4 is lowered by one step. For this reason, the gain of the variable gain amplifier 4 is reduced by 10 db,
The minimum amplification rate is obtained. At the same time, the volume control unit 9
The connection of the switch S2 is opened and the connection of the switch S1 is closed. Therefore, the leakage amount in the sidetone circuit 3 is 10 d
b increases to the maximum leakage amount. As a result, the speaker 7
The voice of the other party emanating from is reduced, and the sound volume at a predetermined level is easy to hear. On the other hand, the level of the speaker's own voice, that is, the level of the sidetone, does not change,
It is maintained at a certain level.

It is assumed that the level of the received signal decreases because the talker of the other party has changed while the variable gain amplifying unit 4 is set to the minimum gain. As a result, the detection result of the reception level detection unit 8 is smaller than the second reference level set 10 db lower than the first reference level.
Suppose you have reached the following level: When the detection result is equal to or lower than the second reference level, the volume controller 9 controls the variable gain amplifier 4
Is increased by one step, and the leakage amount of the side tone circuit 3 is reduced by one step. In other words, the amplification factor and the amount of leakage
Both are set to intermediate values. As a result, only the received sound volume is increased without a change in the sidetone level, and a predetermined level of volume is obtained that is easy to hear.

Even if the amplification factor and the amount of leakage are set to intermediate values,
When the detection result of the reception level detection unit 8 is lower than the second reference level, the volume control unit 9 further increases the amplification factor of the variable gain amplification unit 4 by one step to the maximum amplification factor.
In addition, the leakage amount of the side tone circuit 3 is reduced by one step to make the leakage amount the minimum.

On the other hand, in the initial state, since the voice of the other party is low, the detection result of the reception level detecting section 8 is the second level.
Is lower than the reference level, the volume control unit 9 closes both the connections of the switches S5 and S6, and
Is increased by one step. Therefore, the gain of the variable gain amplifier 4 is increased by 10 db, and becomes the maximum gain. At the same time, the volume control unit 9 opens the connection of the switch S2 and closes the connection of the switch S3. Therefore, the leakage amount in the sidetone circuit 3 is reduced by 10 db,
Minimal leakage. As a result, the other party's voice uttered from the speaker 7 becomes loud, and has a predetermined level of volume that is easy to hear. On the other hand, the level of the speaker's own voice,
That is, the level of the sidetone does not change and is maintained at a constant level.

In the state where the variable gain amplifying section 4 is set to the maximum amplification factor, the level of the received signal increases because the talker of the other party changes, and the detection result of the received level detecting section 8 becomes the first result. Suppose that it became higher than the reference level. When the detection result is higher than the first reference level, the volume controller 9 decreases the gain of the variable gain amplifier 4 by one step and increases the leakage amount of the side tone circuit 3 by one step.
That is, the amplification factor and the leakage amount are both set to intermediate values.
As a result, only the received sound volume is reduced without a change in the sidetone level, and a predetermined level of volume is obtained that is easy to hear.

Even if the amplification rate and the leakage amount are set to intermediate values,
When the detection result of the reception level detector 8 is higher than the first reference level, the volume controller 9 further reduces the gain of the variable gain amplifier 4 by one step to the minimum gain.
In addition, the leakage amount of the sidetone circuit 3 is increased by one step, and is set to the maximum leakage amount.

As described above, the volume control unit 9 uses the first reference level to determine whether to reduce the gain of the variable gain amplifying unit 4 and reduce the reception volume.
The second reference level is used to determine whether to increase the gain of the variable gain amplifier 4 and increase the received sound volume. Therefore, the control of the receiving sound volume is a control having a hysteresis of 10 db. As a result, the level of the received signal becomes 10% of the first reference level and the second reference level.
In the case where the gain fluctuates within the width of db, the gain of the variable gain amplifier 4 does not change. Therefore, it is possible to avoid frequent stepwise changes in the reception signal, and to reduce discontinuous changes in the reception sound volume. For this reason, the received voice is less likely to be unnatural.

As described above, the volume control section 9 controls the 10d
By performing the control having the hysteresis of b, the discontinuous change in the received voice volume is reduced, and the received voice does not become unnatural. However, since the voice of a person has no regularity, the level of the received signal may vary with a large width. In such a case, 1
Even when the control having the hysteresis of 0 db is performed, the gain of the variable gain amplifier 4 frequently changes, and the received voice may become unnatural.

One of the methods for avoiding such a situation is as follows.
One is to increase the width of hysteresis.
When this method is used, there is a disadvantage that the range of the change in the received sound volume also increases.

However, in the present embodiment, the reception level detector 8 is configured to detect the peak level, and the time constant for maintaining the detected level is set to a long time of about several seconds. For this reason, most of the time-dependent changes in the voice level and changes with a large level width are absorbed at the stage of generating the detection result in the reception level detection unit 8. Therefore, both the configuration of the reception level detection unit 8 to detect the peak level with a longer time constant for maintaining the level and the configuration in which the control in the volume control unit 9 has hysteresis are provided. The effect makes it possible to avoid an unnatural change in the received sound volume without causing an increase in the change range of the received sound volume.

The volume control section 9 can be configured as follows. That is, in the initial state in which the gain of the variable gain amplifier 4 and the amount of leakage of the side tone circuit 3 are set to intermediate values, if the detection result of the receiving level detector 8 is higher than the first reference level, The amplification factor of the variable amplification unit 4 is reduced by one step, and the leakage amount of the side tone circuit 3 is increased by one step. Then, this setting is maintained until the call ends. In the initial state, if the detection result of the reception level detection unit 8 is lower than the second reference level, the gain of the variable gain amplifier 4 is increased by one step, and the leakage amount of the side tone circuit 3 is reduced by one step. Decrease.
Then, this setting is maintained until the call ends.

Note that the present invention is not limited to the above embodiment, and the case where the control of the received sound volume is performed based on only the level of the received signal has been described. Similarly, the present invention can be similarly applied to a case where the received sound volume is controlled based on both of them.

Also, a case has been described where the microphone and the speaker are provided in the handset. However, as another configuration, the microphone and the speaker are provided in the slave unit connected to the master unit via the transmission / reception circuit. The same can be applied to a cordless telephone.

In the above description, a case is described in which the apparatus is connected to a wired telephone line. However, the present invention is similarly applied to a telephone connected to a wireless telephone line such as a portable telephone. Is possible.

The level difference between the first reference level and the second reference level is 10 db, and the gain of the variable gain amplifier 4 and the leakage amount of the side tone circuit 3 are both 10 dB.
Although the case where the configuration changes in b steps has been described, the level difference and the amount of change per step can be any other values.

[0038]

The telephone according to the first aspect of the present invention is directed to a telephone which guides a reception signal to a speaker via a variable gain amplifier and leaks a transmission signal from a microphone to an input path of the variable gain amplifier. A reception level detection unit that detects a level of the reception signal, a side tone circuit that can change a leakage amount that leaks the transmission signal to an input path of the variable gain amplification unit, and a detection result of the reception level detection unit. By controlling the gain of the variable gain amplifier based on the result of comparison with the preset reference level, the volume of the speaker is set to a predetermined level and the gain of the variable gain amplifier is increased. And a volume control unit for reducing the amount of leakage of the side-tone circuit when reducing the amount of leakage of the side-tone circuit when decreasing the gain of the variable gain amplifier. For this reason, in accordance with the change in the gain of the variable gain amplifier, the leakage amount of the sidetone circuit changes in a direction in which the change in the sidetone level decreases, so that the change in the sidetone level caused by the control of the receiving sound volume is reduced. It is possible to suppress.

A telephone according to the second aspect of the present invention
In addition to the above configuration, the variable gain amplifying unit is applied to a telephone that changes the amplification factor in a stepwise manner and the side tone circuit changes the leakage amount in a stepwise manner, wherein the reference level is a first reference level; The volume control unit sets two types of reference levels, a second reference level set to a level lower than the first reference level, and a gain when a detection result of the reception level detection unit is higher than the first reference level. The gain of the variable amplifying unit is reduced stepwise, and the leakage amount of the side tone circuit is increased in a stepwise manner. When the detection result becomes lower than the second reference level, the gain of the variable gain amplifying unit is reduced stepwise. And the amount of leakage of the sidetone circuit is reduced stepwise. Therefore, when the level of the received signal is within the range between the first reference level and the second reference level, the gain of the variable gain amplifier does not change. Therefore, the degree of change in the gain of the variable gain amplifier is reduced, so that even when the circuit configuration is simplified, it is possible to reduce the unnaturalness of the change in the received sound volume.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of a telephone according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 3 Side tone circuit 4 Variable gain amplifying unit 6 Microphone 7 Speaker 8 Reception level detecting unit 9 Volume control unit 21 Public telephone line Z1 to Z3 Impedance for determining leakage amount

Claims (2)

[Claims] 1. A telephone set for guiding a reception signal to a speaker via a variable gain amplifier and leaking a transmission signal from a microphone to an input path of the variable gain amplifier, wherein a reception level for detecting a level of the reception signal is provided. A detection unit, a side tone circuit capable of changing a leakage amount for leaking the transmission signal to the input path of the variable gain amplification unit, and a comparison result between a detection result of the reception level detection unit and a preset reference level. By controlling the gain of the variable gain amplifying section, the volume of the loudspeaker is set to a predetermined level, and when the gain of the variable gain amplifying section is increased, the leakage amount of the side tone circuit is reduced, and the gain is reduced. A telephone set comprising: a volume control unit that increases a leakage amount of a side tone circuit when reducing an amplification factor of a variable amplification unit. 2. The telephone according to claim 1, wherein said variable gain amplifying unit changes the amplification factor in a stepwise manner and said side tone circuit changes the leakage amount in a stepwise manner. And a second reference level set at a level lower than the reference level of the first and second reference levels.
When the detection result is lower than the second reference level, the amplification factor of the variable gain amplifying unit is gradually reduced when the detection result is lower than the second reference level. 2. The telephone according to claim 1, wherein the amplification factor of the amplification section is increased stepwise, and the leakage amount of the side tone circuit is reduced stepwise.