JPH08321873A - Hand set-type hands-free call device - Google Patents

Abstract

PURPOSE: To provide a hand set-type hands-free call device where receiving noise is heard till a hand set comes to an ear even when the hand set is detached from a call device mainbody. CONSTITUTION: The device is provided with a call transmitting circuit adding a microphone amplifier 21, a call receiving circuit adding a speaker driving amplifier 11, a call change-over circuit 5, a call transmission gain control circuit 22 controls the respective gains of the amplifiers 21 and 11, a call reception gain control circuit 12 and a howling preventing circuit 30 and is constituted of a time control circuit which controls the call reception gain control circuit 12 and gradually changes the gain of the speaker driving amplifier 11 based on the output of the call change-over circuit 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a handset type hands-free communication device having a handset capable of conducting a hands-free call, and more particularly to the use of the same speaker and microphone provided in the handset. The present invention relates to an improvement of a communication device that can selectively perform hands-free communication or handset communication.

[0002]

2. Description of the Related Art FIG. 7 shows the configuration of a conventional handset type handsfree communication device. This communication device is composed of a handset communication circuit A for hands-free communication, a handset communication circuit B for handset communication, and a signal switching circuit 6. The transmitter / receiver circuit B for handset communication is the speaker 10
b, a speaker driving amplifier 11b, a microphone 20b, a microphone amplifier 21b, and a 2/4 conversion circuit 4b.

On the other hand, the hands-free call transmitting / receiving circuit A similarly has a speaker 10a, a speaker driving amplifier 11a, a microphone 20a, a microphone amplifier 21a and 2/4.
A speaker drive amplifier 1 including a conversion circuit 4a
A howling prevention circuit 30 is provided between the 1a and the microphone amplifier 21a and the 2/4 conversion circuit 4a. The handset call transmitting / receiving circuit B collects the transmitted voice by the microphone 20b and converts it into an electric signal, the microphone amplifier 21b amplifies this signal, and the 2/4 conversion circuit 4b transmits this signal. The speech signal is output to the signal switching circuit 6 via the two-wire signal line.

Further, the 2/4 conversion circuit 4b takes out the received signal from the two-wire type signal line and outputs it to the speaker driving amplifier 11
b amplifies this signal, and the speaker 10b converts this signal into an audio signal and outputs it. In the above-mentioned hands-free call transmission / reception circuit A, the howling prevention circuit 30 further outputs the voice signal emitted from the speaker 10a to the microphone 20.
This is a circuit for preventing the so-called howling from occurring when the loop gain of the transmission / reception circuit exceeds 1 due to the acoustic coupling picked up by a, and a voice switch circuit or a voice switch circuit and an echo canceller are combined. Configured as a circuit.

The signal switching circuit 6 is a circuit for switching a hands-free call or a handset call,
In the hands-free call, the handset communication circuit A for hands-free communication is connected to the communication line, and in the handset communication, the transmission / reception circuit B for handset communication is connected to the communication line.
The configuration of the voice switch circuit is shown in FIG. The control unit 300 is provided with variable attenuators 301 and 302 in the receiving circuit and the transmitting circuit, respectively, and includes a digital filter or the like.
Monitors the input / output level of the variable attenuator 301 of the receiving circuit and the input / output level of the variable attenuator 302 of the transmitting circuit, and the control unit 300 based on these levels, the respective variable attenuators 301, 302. The amount of attenuation is controlled to prevent howling from occurring.

Next, another example of the configuration of the conventional handset type hands-free communication device is shown in FIG. This phone is
A handset communication circuit for a hands-free call and a handset communication circuit for a handset call are made common in one transmission / reception circuit. A microphone 20, a microphone amplifier 21, a speaker 10, and a speaker drive amplifier 11 are provided. , Call switching circuit 5, gain control circuit 7, howling prevention circuit 30
And a 2/4 line conversion circuit 4.

The call switching circuit 5 is a circuit for switching a hands-free call or a handset call, and the gain control circuit 7 controls the gains of the microphone amplifier 21 and the speaker drive amplifier 11 based on the output signal of the call switching circuit. To control. That is, the gain is increased in the hands-free call, while the gain is decreased in the handset call, and the same transmission / reception circuit is shared for the hands-free call and the handset call.

Here, both the microphone 20 and the speaker 10 are attached to the handset, and the call switching circuit 5 is configured as a detection circuit for detecting the attachment / detachment state of the handset to / from the communication device main body. If the handset is detached from the communication device body, it is determined to be a handset call, and if the handset is attached to the communication device body, it is determined to be a hands-free call.

According to such a communication device, a handset communication and a hands-free communication can be selected and used by the same communication device.

[0010]

However, the conventional handset type hands-free communication device has the following problems. First, of the two conventional examples described above,
The former embodiment is provided with a hands-free call transmission / reception circuit and a handset call transmission / reception circuit, so that the circuit scale becomes large, cost cannot be reduced, and two microphones and two speakers are provided. Since each of them is provided, it is difficult to reduce the size of the entire communication device.

Next, in the latter embodiment, since the same transmitting / receiving circuit is shared by the handset call and the hands-free call, the size and cost can be reduced, but there are the following problems. . The first problem is that when the handset is removed from the communication device and the handset call is transferred to the handset call, the volume of the speaker decreases at the same time as the handset removal operation. There was a problem that could not be heard.

As a second problem, if the howling prevention circuit lowers the level of high frequency band or cuts off a specific frequency to prevent howling from occurring, the sound quality of the call is deteriorated. Inevitable,
There is a problem that the communication quality is deteriorated not only during hands-free communication but also during handset communication by sharing the transmission / reception circuit.

As a third problem, in order to prevent the occurrence of howling during a hands-free call, it is necessary to constantly suppress the loop gain including acoustic coupling to 1 or less, so that the volume cannot be adjusted. However, although it is possible to adjust the sound volume during handset call, there is no communication device having such adjusting means, and it is not possible to adjust the sound volume.

As a fourth problem, if the gains of the microphone amplifier and the speaker drive amplifier are increased too much, so-called transmission blocking or reception blocking occurs in which the howling prevention circuit attenuates the transmission signal or the reception signal to suppress the loop gain. Therefore, the call volume could not be raised sufficiently. The present invention has been made in view of the above circumstances, and provides a handset-type hands-free communication device in which a received voice can be heard until the handset comes to the ear even when the handset is removed from the communication device body. The first purpose is to do.

It is a second object of the present invention to provide a handset type hands-free communication device which does not cause deterioration of the communication quality due to the howling prevention circuit during handset communication. A third object of the present invention is to provide a handset-type hands-free communication device that is equipped with a volume control means and is capable of adjusting the communication volume during a handset call.

A fourth object of the present invention is to provide a handset-type hands-free call device capable of adjusting the call volume even during a hands-free call by securing the howling margin by performing the waveform extension and the waveform extension. And

[0017]

A handset type hands-free communication device according to the present invention as defined in claim 1 comprises a microphone for converting a transmitted voice into an electric signal and a microphone amplifier for amplifying the converted electric signal. A handset circuit that is composed of a transmitter circuit that is used, a speaker drive amplifier that amplifies the receiver signal, and a speaker that converts the amplified receiver signal to voice and outputs the voice signal A call switching circuit for switching between a free call and a handset call, a transmission gain control circuit and a reception gain control circuit for controlling the gains of the microphone amplifier and the speaker driving amplifier based on the output signals of the call switching circuit, and a microphone. To prevent howling from occurring due to acoustic coupling from the speaker to the speaker A handset type hands-free call device for selectively performing a hands-free call or a handset call using the same microphone and speaker, wherein the microphone and the speaker are provided in the same handset, Based on the output of the call switching circuit, when switching from a hands-free call to a handset call, controlling the receiving gain control circuit,
It is configured to include a time control circuit that gradually changes the gain of the speaker drive amplifier.

A handset-type handsfree communication device according to a second aspect of the present invention is a howling control circuit for controlling the howling prevention circuit of the handset-type handsfree communication device according to the first aspect of the present invention. On the basis of the output of the call switching circuit, a circuit is provided for invalidating the function of the howling prevention circuit during a handset call.

According to a third aspect of the present invention, there is provided a handset-type hands-free speech communication apparatus according to the first aspect of the present invention, wherein the handset-type hands-free speech communication apparatus according to the present invention is based on the output of the speech switching circuit. A filter circuit that changes the frequency characteristic of the received signal during a call is provided in the received circuit. The handset-type hands-free communication device according to the present invention described in claim 4 is the handset-type hands-free communication device according to claim 1 or 2, which is a reception volume adjusting means for adjusting the gain of the speaker driving amplifier. Then, based on the output of the call switching circuit, a listening volume adjusting means for adjusting the volume of the receiving sound emitted from the speaker during the handset call is provided.

The handset-type handsfree communication device according to the present invention described in claim 5 is the same as the handset-type handsfree communication device according to the present invention described in claim 1 or 2, in which the speech speed of the received signal is reduced and A waveform expansion processing circuit for converting the frequency of voice, the waveform pressure expansion processing circuit, the transmission gain control circuit and the reception gain control circuit are controlled to reduce the speech speed of the reception voice emitted from the speaker, And a waveform expansion control circuit for converting the transmission volume and increasing the transmission volume or the reception volume.

The handset-type hands-free communication device according to the present invention described in claim 6 is the same as the handset-type hands-free communication device according to the present invention described in claim 1 or 2, in which the speech speed of the transmission signal is reduced. A waveform expansion processing circuit for converting the frequency of the transmission voice, the waveform expansion processing circuit, the transmission gain control circuit and the reception gain control circuit are controlled to reduce the speech speed of the transmission voice output to the communication line. And a frequency expansion control circuit for converting the frequency and increasing the transmission volume or the reception volume.

According to a seventh aspect of the present invention, there is provided a handset type handsfree speech communication apparatus according to the fifth aspect of the present invention, which is the same as the handset type handsfree speech communication apparatus according to the present invention. A means for receiving volume adjustment is provided for adjusting the volume of the received sound emitted from the speaker not only during a handset call but also during a hands-free call.

[0023]

In the handset type hands-free communication device according to the present invention described in claim 1, when the handset is detached from the communication device body, the call switching circuit detects this operation,
The transmission gain control circuit and the reception gain control circuit reduce the gains of the microphone amplifier and the speaker drive amplifier, respectively, based on the detection result, and shift from the handsfree call to the handset call.

At this time, the time control circuit controls the reception gain control circuit to gradually change the gain of the speaker drive amplifier and gradually reduce the volume of the speaker.
The received voice can be heard even after the handset is removed and before the handset reaches the ear. In the handset-type hands-free communication device according to the present invention described in claim 2, when the handset is detached from the communication device main body, the call switching circuit detects this operation, and the control circuit
The function of the howling prevention circuit is invalidated based on the detection result. In the handset-type hands-free communication device according to the third aspect of the present invention, when the handset is detached from the communication device body, the call switching circuit detects this operation, and the filter circuit detects the reception signal based on the detection result. The frequency characteristic of the received voice can be changed by changing the frequency characteristic.

In the handset type hands-free communication device according to the fourth aspect of the present invention, when the handset is detached from the communication device main body, the call switching circuit detects this operation, and the reception volume adjusting means detects the operation based on the detection result. The volume of the receiving sound emitted from the speaker. In the handset-type hands-free communication device according to the present invention as set forth in claim 5, the waveform expansion control circuit controls the waveform expansion processing circuit, the transmission gain control circuit and the reception gain control circuit to receive a voice from a speaker. The speech speed of voice is reduced, the frequency is converted, and the transmission or reception volume is increased.

In the handset type hands-free communication device according to the present invention as defined in claim 6, the waveform expansion control circuit comprises:
The waveform expansion processing circuit, the transmission gain control circuit, and the reception gain control circuit are controlled to reduce the speech speed of the transmission voice output to the communication line, convert the frequency, and transmit or receive volume. Increase. In the handset-type hands-free call device according to the present invention as set forth in claim 7, the reception volume adjusting means adjusts the gain of the speaker driving amplifier not only during the handset call but also during the hands-free call, and the sound is emitted from the speaker. Adjust the volume of the received sound.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of the construction of a handset type handsfree communication device according to the present invention as set forth in claims 1 and 2. This handset type hands-free communication device is shown in FIG.
The conventional handset type hands-free communication device shown in FIG. 1 is provided with a time control circuit 13 and a howling control circuit 31.

The time control circuit 13 is a call switching circuit 5
It is a circuit for controlling the reception gain control circuit 12 based on the output of. When the handset call is removed from the communication device main body to shift from the hands-free call to the handset call, the call switching circuit 5 detects the removal operation, and based on the detection result, the reception gain control circuit 12 causes the speaker drive amplifier 11 to operate. However, the time control circuit 13 controls the reception gain control circuit 12 so as to gradually decrease the gain.

The decrease in the gain may be a time constant change or a linear change. It takes about 1 to several seconds until the caller who picks up the handset brings the handset to his or her ear. Any change that reduces to the volume for a handset call during is required. By providing such a time control circuit 13, the received voice can be heard even after picking up the handset and bringing the handset to the ear, and the hands-free call can be smoothly transferred to the handset call. can do.

The howling control circuit 31 is a circuit for controlling the howling prevention circuit 30 based on the output of the call switching circuit 5. During a hands-free call, the howling prevention circuit 30 suppresses the loop gain to prevent howling from occurring due to the acoustic coupling between the microphone 10 and the speaker 20. When transferring from a hands-free call to a hands-free call by removing the call, the call switching circuit 5 detects the removal operation, and based on the detection result, the howling control circuit 31 causes the howling prevention circuit 30 to function thereafter. Invalidate.

That is, the howling prevention circuit 30 is used in a hands-free call, and the howling prevention circuit 3 is not required in a handset call.
Since 0 can be invalidated, in the handset call, the sound quality is not deteriorated due to the howling prevention circuit 30, and a handset call without discomfort is possible.

FIG. 2 shows an example of the construction of the handset type hands-free communication device according to the third aspect of the present invention.
This handset type handsfree communication device is configured by including a filter circuit 14 in the reception circuit of the handset type handsfree communication device shown in FIG. The filter circuit 14 includes a speaker 10 and a speaker driving amplifier 11
It is a circuit as an equalizer provided between the circuits, and is a circuit that changes the transfer characteristic for each frequency band of the received signal based on the output of the call switching circuit 5.

When the handset is removed from the communication device main body to shift from the hands-free call to the handset call, the call switching circuit 5 detects the removal operation, and based on the detection result, the filter circuit 14 presets the operation. A predetermined transfer characteristic is generated for each of the obtained frequency bands to change the frequency characteristic of the received signal. Therefore, the frequency characteristic of the received signal can be changed in the handset call to make the received voice easier to hear. Also,
When the howling prevention circuit 30 suppresses the signal in the high frequency band for preventing howling, the amplitude of the high frequency component is made larger than that of the other frequencies, so that the high frequency audio signal Can be heard.

FIG. 3 shows an example of the construction of the handset type hands-free communication device according to the fourth aspect of the present invention.
This handset-type hands-free call device is configured by including the volume adjusting means 15 in the handset-type hands-free call device shown in FIG. The volume adjusting means 15 is
It is a means for controlling the volume of the reception sound emitted from the speaker by controlling the reception gain control circuit based on the set value of the volume only during the handset call.

That is, when the caller sets the volume of the handset call by the volume adjusting means 15, when the caller removes the handset from the call device main body and the call switching circuit 5 detects the removal operation. only,
Volume control becomes effective. The volume adjustment is performed by the volume adjusting means 15 controlling the reception gain control circuit 12 based on the set value of the volume to control the gain of the speaker drive amplifier 11.

With such a configuration, volume control can be disabled during hands-free communication to prevent howling from occurring, while volume control can be performed during handset communication, and the reception volume can be set arbitrarily. Can be adjusted to. FIG. 4 shows an example of the configuration of the handset-type hands-free communication device according to the fifth aspect of the present invention. This handset type handsfree communication device is configured by providing a waveform expansion processing circuit 160 and a waveform expansion control circuit 161 to the handset type handsfree communication device shown in FIG.

The waveform expansion processing circuit 160 is provided between the howling prevention circuit 30 and the speaker drive amplifier 11, and is an expansion circuit (not shown) for reducing the speech speed of the received voice.
And a frequency conversion circuit (not shown) that converts the frequency of the received voice. The expansion circuit is a circuit that expands the received signal on the time axis to reduce the speed of the received sound emitted from the speaker. For example, D
It can be realized by a combination of SP (signal processing means) and memory.

The frequency conversion circuit is a circuit for shifting the frequency band of the received voice to a lower frequency band,
For example, it is realized as a filter circuit. The frequency conversion circuit described above can convert the received voice emitted from the speaker 10 into a lower voice. The waveform expansion control circuit 161 outputs a control signal to the waveform expansion processing circuit 160 or a transmission gain when the caller operates a waveform expansion button (not shown) provided on the communication device. A control signal is output to the control circuit 22 and the reception gain control circuit 12 to expand the reception voice or shift the frequency of the reception voice.

The waveform expansion control circuit 161 may be configured to perform the above-mentioned operation only during a hands-free call based on the output of the call switching circuit 5.
With such a configuration, it is possible to shift the frequency of the reception signal to a lower frequency and secure a howling margin in a hands-free call. Also,
Since the received voice can be extended on the time axis to slow down the voice speed, the received voice becomes easier to hear.

FIG. 5 shows an example of the construction of the handset type hands-free communication device according to the sixth aspect of the present invention.
This handset type handsfree communication device is configured by providing a waveform expansion processing circuit 230 and a waveform expansion control circuit 231 in the handset type handsfree communication device shown in FIG. The waveform expansion processing circuit 230 is provided between the howling prevention circuit 30 and the microphone amplifier 21, and is provided with a expansion circuit (not shown) for increasing the speech speed of the transmitted voice and a frequency conversion circuit (not shown) for converting the frequency of the received voice. (Illustration) and.

The expansion circuit is a circuit for expanding the transmission signal on the time axis to reduce the speed of the transmission voice included in the transmission signal. For example, as in the above embodiment, for example, the DSP ( It can be realized by a combination of a signal processing means) and a memory. The frequency conversion circuit is a circuit that shifts the frequency band of transmitted voice to a lower frequency band, and is realized as, for example, a filter circuit as in the above-described embodiments.

The waveform expansion control circuit 231 outputs a control signal to the waveform expansion processing circuit 230 when the caller operates a waveform expansion button (not shown) provided on the communication device, or A control signal is output to the transmission gain control circuit 22 and the reception gain control circuit 12 to expand the transmission voice or shift the frequency of the transmission voice. The waveform expansion control circuit 231 may be configured to perform the above-mentioned operation only during a hands-free call based on the output of the call switching circuit 5.

With such a configuration, the frequency of the received signal can be shifted to a lower frequency during a hands-free call, and a howling margin can be secured. Moreover, since the transmitted voice can be expanded on the time axis to slow down the speech speed, the other party can easily hear the transmitted voice. FIG. 6 shows an example of the configuration of the handset-type hands-free communication device according to the present invention described in claim 7. This handset-type hands-free communication device is provided with a waveform expansion processing circuit 160, a waveform expansion control circuit 161, a waveform expansion processing circuit 230, a waveform expansion control circuit 231 and a volume adjusting means 15 in addition to the handset type hands-free communication device shown in FIG. It is provided and configured.

As described above, by the waveform expansion processing circuit 160 and the waveform expansion processing circuit 230, the frequency of the reception signal and the transmission signal is shifted to a lower frequency during the hands-free call to secure the howling margin. Therefore, it is possible to adjust the volume of the received voice by adjusting the gain of the speaker drive amplifier 11. Therefore, the volume adjusting means 15 can adjust the volume not only in the handset call but also in the hands-free call.

[0045]

The handset type hands-free communication device according to the first aspect of the present invention is provided with a time control circuit so that the gain of the speaker drive amplifier can be gradually reduced when the hands-free communication is changed to the handset communication. it can. Therefore, the received voice can be heard even after the handset is picked up and the handset is brought to the ear, and the hands-free call can be smoothly changed to the handset call.

The handset type hands-free communication device according to the second aspect of the present invention is provided with a howling control circuit, uses a howling prevention circuit in a hands-free call, and uses a handset call.
The howling prevention circuit can be disabled. Therefore, in the handset call, the sound quality is not deteriorated due to the howling prevention circuit, and the handset call without discomfort can be performed.

In the handset type hands-free communication device according to the present invention as defined in claim 3, a filter circuit is provided, and in the handset communication, the filter circuit has a predetermined transfer characteristic for each predetermined frequency band. Then, the frequency characteristic of the received signal is changed. Therefore, the frequency characteristic of the received signal can be changed in the handset call to make the received voice easier to hear. Also, when the howling prevention circuit suppresses signals in the high frequency band to prevent howling, the amplitude of the high frequency components is increased compared to other frequencies to increase the high frequency sound. The signal may be audible.

The handset type hands-free communication device according to the fourth aspect of the present invention is provided with the volume adjusting means, and in the handset communication, the receiver gain control circuit is controlled on the basis of the set value of the volume to make the speaker. Adjust the volume of the receiving sound emitted from. Therefore, in the hands-free call, the volume is not adjusted to prevent howling from occurring, while in the handset call, the volume can be adjusted and the reception volume can be arbitrarily adjusted.

In the handset type hands-free communication device according to the present invention described in claim 5, by providing the waveform expansion processing circuit and the waveform expansion control circuit, the speech speed of the received voice is reduced and the frequency band of the received voice is reduced. Shift to a lower frequency band. Therefore, in a hands-free call, the frequency of the received signal can be shifted to a lower frequency to secure a howling margin.
Further, in a hands-free call, the received voice can be extended on the time axis to slow down the voice speed, which makes the received voice easier to hear.

In the handset type hands-free communication device according to the present invention as defined in claim 6, by providing the waveform expansion processing circuit and the waveform expansion control circuit, the speech speed of the transmitted voice can be reduced and the frequency of the transmitted voice can be reduced. Shift band to lower frequency band. Therefore, in a hands-free call, the frequency of the received signal can be shifted to a lower frequency to secure a howling margin.
Also, in a hands-free call, the transmitted voice can be expanded on the time axis to slow down the speech speed, and the communication partner can easily hear the transmitted voice.

Further, since the frequency of the voice to be transmitted can be reduced, the voice to be transmitted can be a low-pitched voice even when an elderly person or a woman is talking on the telephone, and the elderly person or the woman can be called. Because it is not understood that it is, there is a crime prevention effect such as preventing a prank call. The handset type hands-free communication device according to the present invention according to claim 7 is provided with a waveform expansion processing circuit and a waveform expansion control circuit, or a waveform expansion processing circuit and a waveform expansion control circuit, and volume control means. While securing the howling margin, the gain of the speaker drive amplifier is adjusted to adjust the volume of the received voice.

Therefore, the volume adjusting means can adjust the volume not only in the handset call but also in the hands-free call.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a configuration of a handset type hands-free communication device according to the present invention described in claims 1 and 2.

FIG. 2 is a diagram showing a configuration example of a handset type hands-free communication device according to the present invention as defined in claim 3;

FIG. 3 is a diagram showing a configuration example of a handset type hands-free communication device according to the present invention as defined in claim 4;

FIG. 4 is a diagram showing an example of the configuration of a handset-type hands-free communication device according to the present invention as defined in claim 5;

FIG. 5 is a diagram showing a configuration example of a handset type hands-free communication device according to the present invention as defined in claim 6;

FIG. 6 is a diagram showing a configuration example of a handset type handsfree communication device according to the present invention as set forth in claim 7;

FIG. 7 is a diagram showing a configuration of a conventional handset-type handsfree communication device.

FIG. 8 is a diagram showing a configuration of an audio switch circuit.

FIG. 9 is a diagram showing a configuration of a conventional handset-type handsfree communication device.

[Explanation of symbols]

 10 ... speaker 11 ... speaker drive amplifier 12 ... reception gain control circuit 13 ... time control circuit 14 ... filter circuit 15 ... volume control means 160 ... waveform expansion processing of reception circuit Circuit 161 ... Waveform expansion control circuit of receiving circuit 20 ... Microphone 21 ... Microphone amplifier 22 ... Transmission gain control circuit 230 ... Waveform expansion processing circuit of transmission circuit 231 ... Transmission Waveform expansion control circuit 30 ... Howling prevention circuit 31 ... Howling control circuit 5 ... Call switching means

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[Procedure amendment]

[Submission date] July 13, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

A fourth object of the present invention is to provide a handset-type hands-free communication device capable of adjusting a communication volume during a hands-free communication by securing a howling margin by performing waveform expansion .

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

The handset-type handsfree communication device according to the present invention described in claim 5 is the same as the handset-type handsfree communication device according to the present invention described in claim 1 or 2, in which the speech speed of the received signal is reduced and A waveform expansion processing circuit for converting the frequency of voice, and the above waveform expansion processing
Controlling the logic circuit, the transmission gain control circuit, and the reception gain control circuit to reduce the speech speed of the reception voice emitted from the speaker, convert the frequency, and expand the waveform to increase the transmission volume or the reception volume. And a control circuit.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0024

[Correction method] Change

[Correction content]

In the handset type hands-free communication device according to the third aspect of the present invention, when the handset is detached from the communication device body, the call switching circuit detects this operation, and the filter circuit detects the operation based on the detection result. Reception
The frequency characteristic of the received voice can be changed by changing the frequency characteristic of the signal.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0051

[Correction method] Change

[Correction content]

Further, since the frequency of the voice to be transmitted can be reduced, the voice to be transmitted can be a low-pitched voice even when an elderly person or a woman is talking on the telephone, and the elderly person or the woman can be called. Since it is not understood that it is, there is a crime prevention effect such as prevention of mischief . The handset type hands-free communication device according to the present invention as set forth in claim 7,
A waveform expansion processing circuit and a waveform expansion control circuit are provided, and
Providing volume control means to secure a howling margin
On the other hand, by adjusting the gain of the speaker drive amplifier,
Adjust the volume of your voice.

Claims (7)

[Claims] 1. A transmission circuit composed of a microphone for converting a transmission voice into an electric signal and a microphone amplifier for amplifying the converted electric signal, a speaker driving amplifier for amplifying the reception signal and an amplified reception signal. Based on the receiving circuit composed of a speaker that converts to voice and outputting, and the call switching circuit that detects the attachment / detachment state of the handset to the main body and switches hands-free call or handset call, based on the output signal of the above call switching circuit A transmission gain control circuit and a reception gain control circuit for controlling the gains of the microphone amplifier and the speaker drive amplifier, respectively, and a howling prevention circuit for preventing occurrence of howling due to acoustic coupling from a microphone to a speaker, The microphone and speaker are installed in the same handset and A handset type hands-free call device for selectively performing a hands-free call or a handset call using a microphone and a speaker, and when switching from a handsfree call to a handset call based on the output of the call switching circuit, A handset type hands-free communication device comprising a time control circuit for controlling a reception gain control circuit to gradually change the gain of a speaker drive amplifier. 2. A howling control circuit for controlling the howling prevention circuit, comprising a circuit for invalidating the function of the howling prevention circuit during a handset call based on the output of the call switching circuit. The handset type hands-free communication device according to claim 1. 3. The handset according to claim 1 or 2, wherein a filter circuit for changing the frequency characteristic of the received signal is provided in the receiving circuit during a handset call based on the output of the call switching circuit. Type hands-free communication device. 4. An earpiece volume adjusting means for adjusting the gain of a speaker driving amplifier, wherein the earpiece volume for adjusting the volume of an earpiece sound emitted from a speaker during a handset call based on the output of the call switching circuit. The adjusting means is provided, The adjusting means is provided.
Alternatively, the handset type hands-free communication device described in 2. 5. A waveform expansion processing circuit for reducing the voice speed of a received voice signal and converting the frequency of a received voice, said waveform expansion processing circuit, said transmission gain control circuit and said reception gain control circuit, While reducing the speech speed of the received voice emitted from the speaker and converting the frequency,
The handset type hands-free communication device according to claim 1 or 2, further comprising a waveform expansion control circuit for increasing a transmission volume or a reception volume. 6. A waveform expansion processing circuit for reducing the voice speed of a transmission signal and converting the frequency of a transmission voice, said waveform expansion processing circuit, said transmission gain control circuit and said reception gain control circuit. And a waveform expansion control circuit for reducing the voice speed of the transmitted voice output to the communication line, converting the frequency, and increasing the transmitted voice volume or the received voice volume. Handset type hands-free communication device described in 2. 7. An earpiece volume adjusting means for adjusting the gain of a speaker driving amplifier, wherein the earpiece volume adjusting means adjusts the volume of an earpiece voice emitted from a speaker not only during a handset call but also during a handsfree call. The handset type hands-free communication device according to claim 5 or 6, further comprising: