JPH0817415B2 - Earset type handset - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a handset in a two-way simultaneous voice communication terminal, and more particularly to an earset type handset which can be transmitted and received while being worn on an auricle without using a hand.

[0002]

2. Description of the Related Art As a conventional handset in a two-way simultaneous voice communication terminal, there is a handset in a telephone called a handset. In this handset, a speaker, which is a handset placed against the ear, and a microphone, which is a handset placed in front of the mouth, are integrated and used by hand.

By the way, with the development of wireless technology in recent years, portable telephones, cordless types, and in-vehicle types have come into widespread use, and downsizing has been demanded. The handsets described above are the handsets for these telephones. It is used as a basic form, and it is the type of phone that can be used with one hand as usual.

This handset type handset is not suitable for office work or driving a car. In other words, because one hand is blocked because it has a handset and only one hand is available, it is inconvenient to write down while talking on the phone in the office, and there is a problem in safe driving when talking while driving. Occurs.

Therefore, recently, as a means for solving the above-mentioned problems, a hands-free type has been put on the market. This is one in which a speaker, which is a speaker, is fixed to one end of a headband that is fixed to the head, and a microphone, which is a microphone that is extended from this receiver and is attached to the tip of a bar-shaped arm, is attached to the back of the ear shell. A handset is attached to a hooking piece fixed to, a bar-shaped arm is extended from the handset, and a transmitter is attached to the tip.

In the former head-fixing type, there is a problem that it is troublesome to put on and take off and the hair is disturbed when used by a woman, and the head is fixed to the back of the auricle. The latter type is widely used because it is uncomfortable to wear on the ears and the arm for connecting the transmitter and receiver is an obstacle as in the former case, making it unsuitable for carrying. The current situation is that it has not yet reached.

[0007]

Therefore, there is an ear microphone that has been developed to solve the above-mentioned various problems and that is integrally incorporated in a case for inserting a transmitter and a receiver into the auricle. Here, the problem is how to eliminate howling. That is, how to prevent the vibration of the speaker or the sound emitted from the speaker from leaking to the microphone side.

For this reason, in the prior art, the volume of the speaker is lowered so that the volume does not exceed a certain level. In this case, although it is suitable for use in a quiet room or the like, it is unsuitable for use in a noisy outdoors or in a vehicle, and there is a problem that the environment for use is limited.

Further, since the sensitivity of the microphone is kept low, there is a problem that a sufficient volume is not transmitted to the other party and it becomes difficult to listen. When the speaker volume and microphone sensitivity are set to normal and the product is used in a noisy environment,
Since it is difficult to hear during a call, howling often occurs when the handset is covered with a hand, and it is not widely used at present.

The present invention is intended to solve the above-mentioned problems, and an object thereof is to increase the volume of sound from the speaker to a practically sufficient level and to increase the sensitivity of the microphone. It is an object of the present invention to provide an earset type handset in which howling does not occur even if the handset is covered with a hand in a mounted state.

[0011]

The earset type handset according to the present invention is intended to achieve the above-mentioned object, and the means is to extend from the bulge portion which can be mounted in the auricle of the ear to the lower part of the face. A case having a hollow portion extended to the inside, a receiver for outputting voice toward the ear canal entrance in the bulging portion of the case, and a microphone for collecting voice from the outside in the hollow portion of the case. A two-way simultaneous communication type transmitter / receiver composed of a porous material such as glass wool, rock wool, felt, high density sponge, or a fibrous material such as Japanese paper or cotton compressed in the cavity. In addition, a sound absorbing material having a passing voice band on the low frequency side around 300 to 1 KHz and a high cutoff frequency of 2.5 KHz or less is filled, and the filling material is formed into a sheet shape. ,And, The sheet may be wound overlapping a cylindrical shape.

Also, a case having a cavity extending from the bulging portion which can be fitted into the auricle of the ear toward the lower part of the face,
A two-way simultaneous call type transceiver comprising a receiver for outputting a voice toward an ear canal entrance in the bulging portion of the case, and a microphone for collecting a voice from the outside in the cavity of the case. To the microphone
1. It has a passing voice band on the low frequency side around 0 to 1 KHz.
A low-pass type or band-pass type filter including an active element and a passive element having a high cutoff frequency of 5 KHz or less is connected.

Further, in the filter, when the high cutoff frequency does not have a ripple characteristic in the amplitude frequency characteristic in the pass voice band, the amplitude is attenuated by 3 dB on the high frequency side from the maximum amplitude point in the pass voice band. When the amplitude frequency characteristic in the pass voice band has a ripple characteristic, the amplitude is higher than the ripple characteristic region in the pass voice band and higher than the amplitude average value in the ripple characteristic region. Is a frequency at a point where is attenuated by 3 dB.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an earset type handset according to the present invention will be described below with reference to the drawings. Reference numeral 1 denotes a case formed of synthetic resin in a substantially L shape, and a bulging portion 1a having a size that can be inserted into the entrance of the ear canal is formed on the receiver side, which is the short side of the L shape.

A vacant chamber portion 1b is provided in the bulging portion 1a.
And a sound emitting portion 1c is formed at the tip of the bulging portion 1a. In addition, a vertically long cavity 1d is formed on the side of the case 1, which is the long side of the case 1, and a small-diameter voice inlet 1e is formed at the lower end. A hollow sound conduit 2 is provided in the hollow portion 1d.

Reference numeral 3 denotes a speaker housed and fixed by a support member 4 made of an elastic body in the chamber 1b of the bulging portion 1a, and the sound from the speaker 3 is emitted from the sound hole of the sound emitting portion 1c. To be done. Reference numeral 5 is an electret-type microphone housed and fixed in the back of the sound conduit 2, and reference numeral 6 is a pass sound band limiting filter inserted in the sound conduit 2 between the microphone 5 and the sound intake 1e.

As the pass band limiting filter 6, a porous material such as glass wool, rock wool, felt or high density sponge, or a fibrous material such as Japanese paper or cotton is used to improve the sound absorbing effect. Use a material with a high density of pores or a material obtained by compressing fibers. The filter 6 is preferably a low-pass type or band-pass type filter having a pass voice band on the low frequency side around 300 to 1 kHz and a high cutoff frequency of 2.5 kHz or less.

Reference numeral 7 is a connection cord from the speaker 3 and the microphone 5, and is led out to the outside through the outside of the hollow portion 1d in the state of being integrated into one. Numeral 8 is a two-way simultaneous wireless communication device in a wireless earset type handset, which consists of a button cell on the back of the earlobe and a communication section designed to reduce the size of the dedicated LSI. The earlobe is sandwiched like an earring. (Fig. 4).

Next, the operation of the earset type handset having the above configuration will be described. First, the bulging portion 1a of the case 1 is fixed to the auricle, and the sound emitting portion 1c is inserted into the ear canal. In this state, the sound emitting portion 1c has a shape that does not completely block the external auditory meatus, and there is little feeling of blockage, and external sound leaks, so there is no safety problem, and the sound from the sound emitting portion 1c is not heard. There are few leaks. In this embodiment, the speaker 3 is inserted into the vacant chamber portion 1b of the bulging portion 1a. However, the speaker 3 is not placed at the entrance of the ear canal, and the sound pipe is used at another place. It is possible to lead to.

As described above, when a voice signal as an electric signal is input to the speaker 3 from the connection cord 7 with the handset set, the speaker 3 emits a voice. The sound emitted from the speaker 3 is the sound emitting unit 1.
Sound is emitted into the ear canal from the sound hole of c.

On the other hand, the voice from the wearer or the noise from the outside is transmitted from the voice intake 1e to the microphone 5 through the passing voice band limiting filter 6, is converted into an electric signal in the microphone 5 and is connected to the connection cord 7. It is sent to a more external amplifier.

From the standpoint of realizing an easy-to-use handset, the microphone for the handset is selectively sensitized only to the sound from the mouth of the user so that noise from the outside and speaker for the handset can be used. Ideally, there is no sensitivity to leaking sounds. However, the earset type handset has a small shape, and the external voice intake of the handset is closer to the ear than the mouth. It is necessary to devise a structure that lowers the directivity from. The pass voice band limiting filter 6 can also be used to improve directivity.

That is, the attenuation of sound until the sound wave incident from the sound inlet 1e of the sound conduit 2 which houses the pass sound band limiting filter 6 filled with the sound absorbing material reaches the microphone 5 is oblique with the front incident sound wave. Considering the incident sound wave, assuming that the sound absorbing material is uniformly filled, the attenuation of the incident sound wave is considered to be proportional to the travel distance until the incident sound wave reaches the diaphragm of the microphone 5.

Since the front incident sound wave reaches the diaphragm at the shortest distance, the oblique incident sound wave enters obliquely.
The reflection increases and the travel distance to the diaphragm becomes longer than that of the front incident sound wave. Therefore, the sound wave incident from the front is less attenuated than the sound wave obliquely incident, and the microphone 5 having directivity with respect to the incident light from the front is realized.

As a method for further improving the directivity, as shown in FIG. 3, a breathable sound absorbing material on a sheet is lapped in a cylindrical shape, and the sound absorbing material is wound in the sound conduit 2 and the sound center is centered in the sound conduit. When the sound absorbing material is housed so as to be coincident with the center of the winding, the substantial density of the sound absorbing material is lower than that of the sound from the direction different from the winding center. Therefore, the amount of attenuation varies depending on the sound entry path, and a stronger directivity can be provided in the winding center direction.

Further, as another method for improving the directivity, the diameter of the sound input portion of the microphone 5 is made substantially equal to the diameter of the sound conduit 2 to prevent the sensitivity of the microphone 5 from deteriorating and the axis of the sound conduit 2 to be prevented. The entrance of the sound from the outside of the sound conduit 2 may be further restricted by a hole having a diameter of 1.5 mm or less by further restricting the entrance of the sound from a direction different from the heart.

By the way, the above-mentioned pass voice band limiting filter 6 is a mechanical filter, but an electric filter may be used as a filter having a high cutoff frequency described later. Low-pass type shown in Fig. 5 (A) or Fig. 6
The bandpass filters shown in (A) are all active filters using operational amplifiers and used for audio signals. 5 (B) is a characteristic diagram of the low-pass filter, and FIG. 6 (B) is a characteristic diagram of the band-pass filter.

In order to remove the howling, the pass band is limited by using such a filter to attenuate the high frequency sound signal which becomes the howling source. When the amplitude frequency characteristic in the pass voice band does not have the ripple characteristic as shown in FIG. 7, the high cutoff frequency that becomes the boundary of the band limitation is 3 dB on the high frequency side from the maximum amplitude point in the pass voice band.
If it is the frequency at the point of attenuation and the amplitude frequency characteristic in the pass voice band has a ripple characteristic as shown in FIG. 8, it is on the higher frequency side than the ripple characteristic region in the pass voice band and the ripple characteristic It is defined as the frequency at the point where the amplitude is attenuated by 3 dB from the average value of the amplitude in the area.

Further, in order to prevent the deterioration of the voice quality due to the pass voice band limiting filter, a high frequency voice amplitude limiter circuit is provided in the bypass path to suppress the amplitude limit value of the limiter within the howling prevention range to cause howling. It is possible to compensate for the significant attenuation in the high frequency side audio frequency band while preventing the above.

This embodiment is shown in FIG. 9 (A). In this embodiment, the input side 6a connected to the output of the above-mentioned microphone 5 is connected in parallel to the pass band limiting filter 6b that passes 300 to 1 KHz, and the sound on the high side above the cutoff frequency of 2.5 KHz is connected. A high-frequency voice amplitude including a high-frequency voice extraction filter 6c ₁ for extracting a part or a front part of the frequency domain and an amplitude limiter 6c ₂ for limiting the output amplitude from the high-frequency voice extraction filter 6c ₁ to a predetermined value or less. A series circuit in which an attenuator 6d is connected to the limiter 6c and the high frequency sound amplitude limiter 6c is connected. The amplitude limiter 6d is added to the output from the pass band limit filter 6b.
Is added by the adder 6e.
It should be noted that FIG. 9B is a frequency characteristic diagram of the above circuit.

As for the operation, the sound from the speaker 3 is emitted into the ear canal by the same operation as described above, and the sound from the sound intake port 1e is the microphone 5.
In the above, the signal is converted into an electric signal and is output to the amplifier through the electric filter 6 and the connection cord 7.

By the way, in the above-described operation, the sound leaking from the external auditory meatus is reflected and diffracted in the vicinity of the auricle, passes through the external voice intake 1e of the transmitter, reaches the microphone 5 for the transmitter, and is converted into an electric signal. To be converted. The auricle, combined with the complex shape and skull that are unique to the external auditory meatus and auricle, creates a sound field with a unique frequency response due to sound reflection, diffraction, resonance, etc. It has a great influence on the sound field.

According to the research conducted by the inventor, if the sound intake of the microphone 5 is near the auricle, the speaker 3 is generated in this sound field.
The acoustic coupling coefficient between the microphone and the microphone 5 is 1 KHz or more
It has been found that the frequencies are selectively increased at specific frequencies within the telephone voice frequency band of 3.4 KHz.

Therefore, it was found that howling occurred when the volume of the speaker 3 was raised so that it could be used sufficiently even under a noisy condition, and the sensitivity of the microphone 5 was raised so that the voice could be sufficiently transmitted to the other party. Further, when used in a noisy environment, the user may cover his / her ears with his / her hands for the purpose of reducing external noise. Therefore, it has been found that howling is most likely to occur when the user covers the ears with his / her hands.

Therefore, the present inventor studied by focusing on the frequency band in the range where howling is likely to occur. Conventionally, it is known that attenuation in this frequency band lowers the clarity of voice and lowers the communication quality. Therefore, this frequency band is designed to have a flat frequency characteristic as much as possible.

However, it was discovered that, when the signal is intentionally attenuated within this frequency band, the deterioration of speech quality is practically unproblematic, and the attenuation characteristic that significantly suppresses howling can be realized as a pass voice band limiting filter. did.

That is, a cutoff frequency of 2.5 KHz or less (when the amplitude frequency characteristic in the pass voice band has no ripple characteristic, the point where the amplitude is attenuated by 3 dB from the maximum amplitude point in the pass voice band on the high frequency side of the band) When the frequency of is defined and the amplitude characteristic in the pass band has a ripple characteristic, the frequency at the point where the amplitude is attenuated by 3 dB from the average amplitude value of the ripple characteristic area in the pass band is A low-pass type or pass band limiting filter 6 having the above-mentioned () is arranged at the front face of the microphone 5 (in the case of a mechanical filter) or the output end of the microphone 6 (in the case of an electrical filter), The occurrence could be significantly suppressed.

According to the experiments by the present inventor, howling can be generated more effectively when the cutoff frequency is lowered, but the intelligibility is lowered, and when the cutoff frequency is increased, the intelligibility is improved. It turns out that howling is more likely to occur. It is known that when the sound from the free sound field reaches the eardrum, the sound pressure becomes higher as the frequency becomes higher from 1 KHz to around 2.5 KHz, and as a result, even if a pass voice band limiting filter is provided, communication quality is improved. It is inferred that it does not decrease significantly. The result of the experiment also proves this, and it has been proved that it is practically optimal to provide the cutoff frequency of 2.5 KHz or less.

Incidentally, in the above-mentioned first embodiment,
The mechanical bandpass filter 6 is replaced by the microphone 5
However, the passing voice band limiting filter 6 may be placed in front of the sound emitting part of the speaker 3, and the passing voice band limiting filter 6 may be placed in front of the microphone 5 and the speaker 3. You may distribute and arrange in. When the filter 6 is dispersed, the pass voice band limiting filter 6 is arranged in either one of the microphone 5 and the speaker 3 to obtain a specific frequency characteristic. Since the frequency characteristic of can be reduced to half, the effect will be shared between the speaker and the listener.

Further, in the second embodiment, the one in which the electrical pass voice band limiting filter 6 is connected to the output end of the microphone 5 is shown, but howling occurs in the voice signal passing path. Therefore, it may be connected to any part of the audio signal passage, that is, to the input end of the speaker 3.

Furthermore, the electric voice conversion performance of the speaker 3 itself may be made equal to the frequency characteristic of the pass voice band limiting filter 6, or the voice electric conversion performance of the microphone 5 itself may be made equal to the frequency characteristic of the pass voice band limiting filter. .

[0042]

As described above, according to the present invention, in a two-way voice communication device in which a transmitter is provided in the case arranged at the entrance of the ear canal and a receiver for emitting a sound is provided in the ear canal. By providing a filter that blocks high-frequency signals or sound in the sound signal path that is the medium,
Since no high-frequency signal or sound that easily causes howling is generated in the audio signal path, even if the volume from the speaker is increased or the sensitivity of the microphone is increased, the handset is covered with the hand when worn. Also has an effect such as howling does not occur.

[Brief description of drawings]

FIG. 1 is a perspective view showing a state in which an earset type handset of the present invention is attached to an auricle.

FIG. 2 is a partial cross-sectional side view of the earset type handset according to the present invention.

FIG. 3 is a perspective view showing an embodiment of the filter in the above.

FIG. 4 is a perspective view showing a state in which an earset type handset according to another embodiment is attached to an auricle.

5A is a circuit diagram of a low-pass filter, and FIG. 5B is a frequency characteristic diagram of the same.

6A is a circuit diagram of a bandpass filter, and FIG. 6B is a frequency characteristic diagram of the same.

FIG. 7 is an amplitude frequency characteristic diagram when there is no ripple.

FIG. 8 is an amplitude frequency characteristic diagram when there is a ripple.

FIG. 9 is a circuit diagram in the case of compensating for an audio frequency band on the treble side.

[Explanation of symbols]

 1 case 1a bulge 1d cavity 3 speaker 5 microphone 6 pass band filter

Claims (4)

[Claims] 1. A case having a cavity extending from the bulging portion that can be mounted in the auricle of the ear toward the lower part of the face, and a sound is output toward the ear canal entrance in the bulging portion of the case. A receiver and receiver, which is a two-way simultaneous call type transceiver including a microphone for collecting voice from the outside in the hollow portion of the case, wherein glass wool is provided in the hollow portion.
It is composed of a porous material such as rock wool, felt, high-density sponge, or a material obtained by compressing a fibrous material such as Japanese paper or cotton, and has a pass voice band on the low frequency side around 300 to 1 KHz. An earset type handset characterized by being filled with a sound absorbing material having a high cutoff frequency of 2.5 KHz or less. 2. The filler is formed into a sheet, and
The earset type handset according to claim 1, wherein the sheet is rolled up in a cylindrical shape. 3. A case having a cavity extending from the bulging part that can be mounted in the auricle of the ear toward the lower part of the face, and outputting sound toward the ear canal entrance in the bulging part of the case. What is claimed is: 1. A two-way simultaneous call type transceiver comprising a handset and a microphone for collecting voice from the outside in the hollow portion of the case, wherein the microphone has
2.5K with a passing voice band on the low frequency side near 1KHz
An earset type handset which is characterized in that a low-pass type or band-pass type filter consisting of an active element and a passive element having a high cutoff frequency below Hz is connected. 4. When the high frequency cutoff frequency has no ripple characteristic in the amplitude frequency characteristic in the pass voice band, the filter attenuates the amplitude by 3 dB on the high frequency side from the maximum amplitude point in the pass voice band. When the amplitude frequency characteristic in the pass voice band has a ripple characteristic, the amplitude is higher than the ripple characteristic region in the pass voice band and higher than the amplitude average value in the ripple characteristic region. The earset type handset according to claim 3, wherein is a frequency at a point at which 3 dB is attenuated.