JPH07203007A - Hand-free telephone set - Google Patents

Abstract

PURPOSE:To provide a hand-free telephone set which can satisfactorily suppress the howling and echoes even in a large acoustic reflection environment produced in a bathroom. CONSTITUTION:A speaker/microphone part 200 includes a digital filter with which a controller 205 attains a transmission function having the adverse characteristic of the acoustic transfer function sent to a microphone 203 from a speaker 201. This filter can eliminates the sounds coming from the speaker 201 out of the speech sending signal received from the microphone 203. The speaker 201 and the microphone 203 are placed close to each other and therefore the acoustic transmission function is kept fixed between them regardless of the acoustic environment produced in a bathroom. At an urgent outgoing part 300, an auto-dialer 303 automatically transmits an urgent report to a prescribed destination when an urgent switch 301 is pushed by a person in the bathroom. Furthermore a set of an ultrasonic transmitter 309 and an ultrasonic receiver 311 monitors the movements of the bathing person and then starts the auto- dialer 303 to perform an automatic outgoing operation if the movements of the bathing person are not recognized for a long time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hands-free telephone, and more particularly to a hands-free telephone which can be used even in a reverberant environment such as a bathroom.

[0002]

2. Description of the Related Art One of the features of a hands-free telephone is that a telephone call can be made at some distance from a microphone and a speaker. In order to realize this, the problem of howling and echo prevention must be solved.

As a conventional technique therefor, for example, one disclosed in JP-A-1-272355 can be cited. This known telephone has a speaker and two microphones arranged at different distances from the speaker. Then, a delay time corresponding to the distance between the two microphones is added to the acoustic signal from the nearer microphone, and the difference between the delayed acoustic signal and the acoustic signal from the farther microphone is calculated. . As a result, the sound that has sneak into the two microphones from the speaker is canceled, and as a result, howling and echo are prevented.

[0004]

The above-mentioned howling prevention technique using the two microphones will surely be effective in a general room having a sufficiently sound absorbing wall. However, a satisfactory howling prevention effect cannot be expected with a hands-free telephone used in a special room such as a bathroom.

In general, the bathroom has an inner wall made of a material having a very high sound wave reflectance (a low sound absorption coefficient) such as tile or FRP. Therefore, the reverberation time is very long compared to other rooms, and in particular, a specific frequency component such as around 700 Hz is remarkably accompanied by a very long reverberation time (60 dB attenuation) of, for example, about 1.5 seconds. To be enhanced.

In an environment with large acoustic reflection such as a bathroom, in addition to the sound entering the microphone from the speaker in the shortest path, the sound reflected from the speaker to the wall and input to the microphone cannot be ignored. The wraparound sound that follows a complicated path due to this reflection cannot be removed by the simple delay and difference processing that assumes only the wraparound sound of the shortest path as in the above-described conventional technique. Therefore, howling and echo are not completely eliminated.

Further, since the resonance peak is high and sharp in the bathroom for the above-mentioned reason, there is a problem that once howling occurs, it resonates with the bathroom, further promoting howling and echo.

Therefore, a main object of the present invention is to enable a hands-free telephone to sufficiently suppress howling and echo even when used in an environment with large acoustic reflection such as a bathroom.

Further, the present invention provides, as a secondary object, an improvement for enhancing security during bathing, particularly in a telephone for a bathroom. That is, when an emergency or an abnormal situation occurs while taking a bath, it is possible to call and notify the appropriate person by the simplest and quickest possible procedure.

[0010]

A hands-free telephone according to a first aspect of the present invention provides a microphone such that the acoustic transfer function from the speaker to the microphone is constant, substantially unaffected by the external acoustic environment. And the speaker are arranged close to each other, and a corrected transfer acoustic signal is generated from the received signal given to the speaker by using a transfer function of the speaker to the microphone and a predetermined transfer function having an inverse characteristic. The transmission signal from the microphone is corrected by the correction sound signal.

The hands-free telephone according to the second aspect of the present invention is used in a bathroom, and responds to an abnormality detecting means for detecting an abnormal situation in the bathroom and an output of the abnormality detecting means. And an automatic call means for sending an emergency call to a previously registered call destination.

[0012]

In the hands-free telephone according to the first aspect, since the acoustic transfer function from the speaker to the microphone is constant,
A transfer function having the inverse characteristic of this acoustic transfer function is set in advance in the telephone, and the set transfer function is applied to the reception signal to create a correction signal, which is applied to the transmission signal to wrap around from the speaker. The acoustic signal is well removed from the transmitted signal. As a result, echo is prevented. At the same time, the transmission signal is prevented from diverging and howling is eliminated.

This telephone can effectively prevent howling and echo even in a bad acoustic environment such as a bathroom, because the acoustic transfer function between the speaker and the microphone is not substantially affected by this environment.

In order to keep the acoustic transfer function between the speaker and the microphone constant, for example, it is desirable that the microphone be arranged on the central axis of the speaker and in the acoustic emission direction of the speaker.

Further, if the microphone and the speaker are integrally combined, they can be installed in the room as a single unit, which is advantageous because the installation work is easy and the appearance is good.

In the hands-free telephone set according to the second aspect, when an abnormality occurs in the bathroom, an emergency call is automatically sent to a previously registered call destination.

In this telephone, as means for detecting abnormality,
For example, an emergency switch operated by a bather, a device that detects a continuous inoperative state of the bather in the bathroom using ultrasonic waves, or the like can be adopted. The former switch is convenient when making an emergency call at the discretion of the bather,
On the other hand, the latter device is useful for emergency calls when the bather cannot move, such as when the bather falls over in the bathroom.

Furthermore, in this telephone, it is desirable to automatically shift to a hands-free call mode using a microphone and a speaker after making an emergency call. This is because the bather can exchange more detailed information with the contact destination without performing any special additional operation.

Further, in this telephone, a plurality of call destinations are registered so that when the call destination who has sent the emergency call is busy or has no response, it is possible to further send the emergency call to another call destination. Is desirable. As a result, it is possible to reliably notify the appropriate party of the occurrence of an emergency, and security is further improved.

[0020]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows the overall structure of a bathroom hands-free telephone according to an embodiment of the present invention.

This telephone is composed of three parts: a main part 100, a speaker / microphone part 200, and an emergency transmission part 300.

The main section 100 is a section in which essential functional elements are mounted on the telephone, and includes a main circuit 101, a call switch 103 and the like. The main circuit 103 includes various circuits necessary for the telephone, such as a line capturing circuit, a selection signal generating circuit, an incoming call detecting circuit, a ringing tone generating circuit, a call circuit, their control circuits, and a power supply circuit. Call switch 103
Is a switch for manually performing off-hook and off-hook signal input for starting and ending a call.

The speaker / microphone unit 200 is a part for carrying out a hands-free call, and is a speaker 201 for amplifying and outputting a reception from the other party of the call, a microphone 203 for receiving a transmission from the bather, and an active call. It includes a reception signal and a controller 205 that performs a correction process described later on the transmission signal in order to eliminate howling and echo.

The emergency transmission unit 300 is for automatically transmitting an emergency notification to a preset addressee by a simple manual operation or completely automatically when an emergency or abnormal situation occurs while bathing. Is. This emergency dispatch unit 3
00 is an emergency switch 301, an auto dialer 303,
A controller 305, a data memory 307, an ultrasonic transmitter 309, an ultrasonic receiver 311 and a waveform comparator 313 are included.

In such a configuration, the features of the present invention are embodied in the speaker / microphone unit 200 and the emergency transmission unit 300. Below, these two parts 200, 3
00 will be described in detail.

First, the speaker / microphone unit 200 will be described.

As shown in FIG. 1, the received signal that has entered the main circuit 101 from the telephone line is a bandpass filter 20.
After being sent to 7 and narrowed down to a predetermined audio frequency range,
It is converted into a discrete-time digital signal by the A / D converter 209 and input to the controller 205. The received signal is added with an appropriate amount of sidetone in the controller 205, then sent to the D / A converter 215 to be converted into a continuous time analog signal, and then the low pass filter 217.
After removing unnecessary high frequency components by
It is output to 1.

On the other hand, the transmission signal output from the microphone 203 has unnecessary high frequency components removed by the low pass filter 219, is converted into a discrete time digital signal by the A / D converter 221, and is input to the controller 205. It This transmission signal is subjected to a correction, which will be described later, for removing the wraparound sound from the speaker 201 in the controller 205, and then sent to the D / A converter 211 to be converted into a continuous time analog signal. The analog transmission signal is narrowed down to a predetermined audio frequency band by the bandpass filter 213 and then sent out to the telephone line through the main circuit 101.

The passbands of the bandpass filters 207 and 213 are, for example, 300 to 3 kHz, and the cutoff frequencies of the lowpass filters 217 and 219 are, for example, 3 kHz.

Here, the speaker 201 and the microphone 203 are arranged in a very close distance. This is because the acoustic transfer function from the speaker 201 to the microphone 203 does not substantially change even if the bather moves in the bathroom. For this purpose, it is desirable that the effective distance between the speaker 201 and the microphone 203 be equal to or less than a quarter wavelength of the maximum frequency in the target audio frequency band. For example, when the maximum frequency is 1 kHz, the distance between them is 2.5 cm or less,
Further, when the maximum frequency is 3 kHz, it is desirable that it is 7.5 cm or less.

FIG. 2 shows one mode for realizing such a close arrangement of the speaker 201 and the microphone 203.

As shown in the partial sectional view of FIG. 2A and the front view of FIG. 2B, the speaker 201 and the microphone 203 are housed in the same box 501 and integrated with each other. The unit 500 is configured. Box 501
The inner wall of the is covered with a mat of a material having a good sound absorbing property, for example, a glass wool mat 503. Speaker 201
Is attached inside the circular window so that sound can be radiated from the circular window formed on the front wall of the box 501. The microphone 203 is supported by an arm extending from the inner peripheral wall of the circular window, and is fixed at a position on the central axis of the speaker 201 that can satisfactorily receive radiated sound from the speaker 201.

In the speaker / microphone unit 500, the effective distance between the speaker 201 and the microphone 203 is preferably one quarter wavelength of the maximum frequency component as described above, but if the distance is too short, the speaker 201
Since the frequency distribution from the microphone to the microphone 203 becomes abnormal, the shortest distance is actually selected within the range where the frequency distribution is substantially normal.

This speaker / microphone unit 500 is
It is installed in a position suitable for hands-free calling in the bathroom.
For example, as shown in FIG. 4, the head side position 60 of the bath 601 is
On the wall surface of the bathroom near 1a, the speaker / microphone unit 500 is mounted side by side with the remote controller 900 of the water heater in a direction in which the front surface is directed toward the bather.

FIG. 3 shows a functional configuration of the controller 205.

In FIG. 3, x (n) is a discrete-time reception signal, l (n) is a reception signal heard by a bather, and r (n) is an original discrete-time transmission signal uttered by the bather. , P (n)
Is a transmission signal including the wraparound sound output from the microphone 203, y (n) is a corrected transmission signal of discrete time output from the controller 205, and n is a discrete time of these signals. Further, g1 represents an acoustic transfer function from the speaker 201 to the bather, g2 represents an acoustic transfer function from the bather to the microphone 203, and w represents an acoustic transfer function from the speaker 201 to the microphone 203.

What is important here is that the speaker 201 and the microphone 203 are close to each other, as described above, and therefore, regardless of the size and structure of the bathroom and the position of the bather in the bathroom, etc. The acoustic transfer function w is substantially constant. This is an important factor for making the processing for howling and echo prevention by the controller 205 described below effective.

As shown in FIG. 3, the controller 205
Includes a digital filter 501, an attenuator 503, and adders 505 and 507. Digital filter 501
Has a transfer function H, and by applying this transfer function H to the reception signal x (n), a corrected acoustic signal q (n) for howling and echo prevention is generated. This corrected acoustic signal q
(n) is subtracted from the transmission signal p (n) from the microphone 203 by the adder 507, and the corrected transmission signal y (n) is generated and transmitted to the communication partner.

The attenuator 503 has an attenuation coefficient μ, and multiplies the corrected transmission signal y (n) by this attenuation coefficient μ to generate sidetone of an appropriate size. This sidetone is added to the reception signal x (n) by the adder 505 and sent to the speaker 201.

In the system of FIG. 3, the following equation holds. The following equation is expressed in Z conversion form, and the Z conversion of the physical quantity shown in lower case in FIG. 3 is shown in corresponding upper case.

P = W (X + μY) + G 2 · R (1) Q = H (X + μY) (2) Y = P−Q (3) The following formula is obtained from the formulas (1) to (3).

Y = {G 2 · R + (W−H) X} / {1−μ (W−H)} (4) From the equation (4), the final transmission signal Y can be obtained. The two points are that the received signal X is included and causes an echo at the other end of the call, and that if the value of μ (WH) is close to 1, the transmitted signal Y diverges and howling occurs.

Therefore, in order to eliminate howling and echo, WH = 0, that is, the transfer function H of the digital filter 501 is set equal to the transfer function W between the speaker and the microphone. In this case, the speaker
Since the transfer function W between the microphones is substantially constant regardless of the surrounding environment as described above, the transfer function W can be determined by measuring the impulse response between the speaker and the microphone in advance. If the coefficient matrix of the digital filter is set using the result of this impulse response as it is, the above condition W = H is obtained.

For example, the average reverberation time in the bathroom is 0.8
Since it is around seconds, if the target band is 300 to 3 kHz and the sampling clock is 6 kHz, 0.8 seconds corresponds to 4800 clocks. Therefore, it is sufficient to sample from the beginning of the impulse response up to about 4800 clocks and use this value as the coefficient matrix of the digital filter 501.

With the above-described structure, howling and echo of hands-free communication in the bathroom can be effectively prevented.

Next, referring again to FIG. 1, the emergency transmission unit 3
00 will be described.

The emergency switch 301 is a button switch that the bather presses when an abnormality occurs. When the emergency switch 301 is turned on, the auto dialer 303 is activated. Auto dialer 3
Reference numeral 03 stores in advance subscriber telephone numbers of one or more destinations to which the emergency call is to be sent, and when activated, outputs the telephone number data to the controller 305.

The controller 305 is an automatic dialer 3
Send the telephone number data from 03 to the main circuit 101,
In response to this, the main circuit 101 transmits the telephone number to the telephone line. When the destination answers, the main circuit 101
Notifies the controller 305 to that effect.

The controller 30 which has recognized the response from the callee
5 reads the emergency notification message data stored in advance in the data memory 307, reproduces this as an audio signal, and sends it to the main circuit 101. As a result, the emergency notification message is transmitted to the destination.

In this way, it is possible to make an emergency call to the appropriate other party by simply pressing the button. The emergency call message can include, for example, the bather's address, name, telephone number, message, and the like.

Further, a device for detecting the movement of the bather is also provided so as to be able to deal with the case where the bather is unable to move in the bathroom due to an abnormal physical condition. That is, the ultrasonic transmitter 309 radiates ultrasonic waves into the bathroom, and the ultrasonic receiver 311 detects this ultrasonic wave and sends it to the waveform comparator 313. The waveform comparator 313 monitors the temporal change of the received signal waveform by comparing the signal waveform from the receiver 311 with that in the past. As a result, if there is no change in the received waveform over a predetermined period of time, the waveform comparator 313 determines that the bather cannot move, and the controller 30
Notify 5. Then, the controller 305 activates the auto dialer 303, whereby the emergency call as described above is automatically performed.

After the emergency call is made by operating the emergency button or detecting the inactivity as described above, it is desirable to automatically return after a certain time to enter the normal hands-free call mode. Thereby, the bather can exchange more detailed information to the emergency call destination without using any hands on the spot.

Further, when the other party is busy or does not answer at the time of making an emergency call, it is desirable to sequentially select a plurality of callees registered in advance and automatically make a call.

In order for the above-mentioned emergency transmission unit 300 to function effectively, it is desirable that the inside of the bathroom is arranged as shown in FIG.

That is, the emergency switch 301 is housed in the switch unit 800 together with the call switch 103, and is installed together with the remote controller 900 and the speaker / microphone unit 500 in an easily accessible place such as the bathroom wall surface near the bathtub head side position 601a. . With this, bather 7
00 is the switch unit 80 in the normal bathing posture
0 can be manipulated.

The ultrasonic transmitter 309 is installed at a position where ultrasonic waves can be radiated to the entire bathroom, such as the ceiling surface of the bathroom 600. On the other hand, the ultrasonic receiver 311 is installed in a place where the bather's movement is well reflected in the ultrasonic waveform fluctuation, such as on the bathroom wall near the washing room 603 of the bathroom 600 or the bathtub head position 601a. To be done. As a result, it is possible to favorably detect whether or not the bather is moving.

Although a preferred embodiment of the present invention has been described above, the present invention can be implemented in various modes other than this embodiment.

[0059]

As described above, according to the first aspect of the present invention, the microphone and the speaker are brought close to each other so that the acoustic transfer function between the microphone and the speaker is not influenced by the external environment, and the acoustic transfer is performed. Since the transfer function having the inverse characteristic of the function removes the wraparound sound from the speaker to the microphone from the transmitted signal, howling and echo can be effectively prevented even in a bad acoustic environment such as a bathroom. .

Further, according to the second aspect of the present invention, since an abnormal situation is detected in the bathroom and an emergency call is automatically sent to a predetermined addressee, the safety in the bathroom is improved. To do.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a bathroom hands-free telephone according to an embodiment of the present invention.

FIG. 2 is a speaker 201 and a microphone 20 according to the embodiment.
The figure which shows arrangement | positioning with 3.

FIG. 3 is a block diagram showing a functional configuration of a controller 205 in the embodiment.

FIG. 4 is a diagram showing an arrangement in a bathroom in the same embodiment.

[Explanation of symbols]

 100 main unit 200 speaker / microphone unit 201 speaker 203 microphone 205 controller 300 emergency transmission unit 301 emergency button 303 auto dialer 305 controller 307 data memory 309 ultrasonic transmitter 311 ultrasonic receiver 313 waveform comparator

Claims (8)

[Claims] 1. In a hands-free telephone equipped with a microphone for transmitting and receiving speech and a speaker for receiving and amplifying speech, a sound transfer function from the speaker to the microphone is constant without being substantially affected by an external acoustic environment. As described above, the microphone and the speaker are arranged close to each other, and further, a reception signal given to the speaker using a predetermined transfer function having an inverse characteristic of an acoustic transfer function from the speaker to the microphone. A hands-free telephone characterized in that it is provided with a transmission correction unit for generating a correction acoustic signal from the microphone and correcting the transmission signal from the microphone by the corrected acoustic signal. 2. The hands-free telephone according to claim 1, wherein the microphone is arranged on a central axis of the speaker and in a sound emission direction of the speaker. 3. The hands-free telephone according to claim 2, wherein the microphone and the speaker are integrally combined so as to be installed indoors as a single unit. 4. A hand-free telephone for a bathroom equipped with a microphone for transmitting and receiving a voice and a speaker for receiving and expanding a voice, and an abnormality detecting means for detecting an abnormal situation in the bathroom, and an output of the abnormality detecting means. A hands-free telephone, comprising: an automatic transmission means for responding and transmitting an emergency call to a pre-registered call destination. 5. The hands-free telephone according to claim 4, wherein the abnormality detecting unit indicates an emergency switch operated by a bather installed in the bathroom and a continuous inoperable state of the bather in the bathroom. A hands-free telephone including at least one of a non-operation detector for detecting. 6. The hands-free telephone according to claim 5, wherein the non-operation detector emits ultrasonic waves into the bathroom, and ultrasonic waves receive ultrasonic waves emitted into the bathroom. A hands-free device, comprising: a receiver; and a fluctuation monitor that detects that the received ultrasonic wave does not fluctuate over a predetermined time, thereby detecting a continuous inoperative state of the bather. Telephone. 7. The hands-free telephone according to claim 4, further comprising control means for enabling the microphone and the speaker to enable hands-free communication after the emergency call is issued by the automatic calling means. Hands-free telephone characterized by the following. 8. The hands-free telephone according to claim 4, wherein the automatic caller has registered a plurality of callees, and one caller who has sent the emergency call is busy or has no response, A hands-free telephone which further sends the emergency call to another call destination.