JPS6010900A - Structure of speaker phone for telephone set - Google Patents

Abstract

PURPOSE:To obtain speaker phone structure having high preventing capability of howling by providing chambers containing respectively a non-directional speaker and a couple of microphones and positioning each microphone at nearly same acoustic propagating path. CONSTITUTION:A case 22 being the entire housing consists of an upper half part 22a and a lower half part 22b and they are approximately circular tube form, respectively. A speaker chamber 40 is formed in the upper half part 22a and a microphone chamber 40 is formed in the lower half part 22b. A speaker 11 is placed upward at the inner upper part of the speaker chamber 40, and irradiated sound is reflected on the 360 deg. omnidirectional relfecting plate 24 of downward circular cone form, then diffused radially in non-directionally via sound irradiating holes 23. Further, a couple of microphones 12, 13 in the microphone chamber 40 are placed in a geometrical arrangement so that the incident sound pressure vector to both microphones 12, 13 is identical as much as possible when the acoustic output irradiated from the speaker 11 is made incident thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a speaker for a telephone that houses a speaker and a microphone in one casing or housing, and allows for telephone calls even when the telephone is placed on a table or the like without the user's hands being removed. -Regarding a phono structure, in particular, it relates to a speaker phono structure that is optimal for effectively preventing howling.

In this type of speaker phono, the audio information received from the telephone line needs to be sufficiently amplified before being acoustically radiated so that it can reach the caller located as far away as possible. When receiving transmitted information from a caller who is also at a distant location, it is necessary to receive this information with the highest possible sensitivity and to ensure that it is amplified to a significant level so that it can be transferred to the telephone line. Therefore, amplifiers with large amplification levels are interposed in both the transmitting and receiving circuits, which creates an acoustic coupling between the speaker that acoustically radiates the received information and the microphone that receives the transmitted information. The fateful problem remained that if it was woken up, a strong howling would occur.

In order to take measures against howling, first of all,
The speaker phone structure must be geometrically and structurally resistant to howling. However,
In the past, the speaker phone structure itself did not have much ingenuity, and only circuit countermeasures were taken. For example, a method of changing the transmitting/receiving system to a so-called half-duplex communication system or a pseudo-duplex communication system, that is, a method of reducing the gain of the transmitting circuit when receiving a call, and reducing the gain of the receiving circuit during transmitting. etc.

However, as will soon be seen, this scheme completely defeats the inherent advantages of telephone lines as a full-duplex communication system. Originally, conversations should be simultaneous and bidirectional even through telephones, and this is the only way to convey subtle differences in nuance between parties.

The present invention has been made in view of the above-mentioned circumstances, and aims to change the conventional approach of relying solely on the circuit system for howling countermeasures. A speaker phone structure that has a structure that is resistant to noise and that is easy to configure as an input terminal device for an electronic circuit system for transmitting and receiving calls, even when countermeasures against howling are taken by devising the circuit configuration. We aim to provide the following.

The speaker phone structure of the present invention uses at least one pair of microphones that are housed within the housing and receive speech information from a caller.

When the radiated sound pressure of the speaker that radiates reception information into space is incident on each of these pair of microphones, the speaker and the microphone are connected so that the electrical conversion output vector of each microphone is at least approximately the same as a result. The relative mechanical and geometric configurations between the two are taken into account. In other words, the present invention devises the housing configuration so as to satisfy the relative mechanical and geometric arrangement between the speaker and the microphone.
be.

If this purpose can be achieved and the electrical conversion outputs of both microphones that receive the feedback input from the speakers can be made vectorial (the same), the configuration would be extremely simple to remove the speaker component using a circuit. become.

On the other hand, for information transmitted from a speaker who is never in the same position as the speaker, only this component can be easily extracted. This is because the feedback input from the speaker is in the same mode as the microphone output, and on the other hand, the transmitted information spoken by the speaker appears as not only a level difference but also at least a phase difference between the two microphone outputs.

The present invention will now be described with reference to the accompanying drawings, but for ease of understanding, an example of a transmitting/receiving circuit system that is effective when used with the speaker phone structure of the present invention will be explained first.

A circuit system as an example of this is shown in FIGS. 1 and 2, but this circuit system itself is separately disclosed by the applicant. However, as stated in advance, the speaker of the present invention
The phone structure can be used not only for this circuit system but also for a wide range of other applications.

In FIG. 1, the voice signal applied between the telephone lines Ll and L2 is applied to the balanced input type secondary winding of the coupling transformer 2 by closing the hook switch l. The secondary side is an unbalanced type, with a termination resistor 4 terminating between both terminals, and a varistor 3 installed in parallel to this to remove inductive pulses caused by lightning, etc. on the line. It is being

One end of the secondary side of the coupling transformer 2 is grounded, and the other end is connected to the positive phase input or non-inverting input 8 of the differential amplifier 8 for the reception system.
+ is connected. However, an impedance isolator or bidirectional impedance converter 6, which will be described later, is inserted between this positive phase input 8+ and the corresponding terminal of the coupling transformer, and as a further desirable consideration, the negative phase of this differential amplifier 8 A second impedance isolator 7 is also inserted between the input or inverting input 8- and the other terminal of the coupling transformer or ground. In the figure, these impedance isolators are designated by symbol 1. It is abbreviated as I.

Similar to known circuits of this type, the output of the differential amplifier 8 is applied to a speaker 11 via a suitable preamplifier 9 or power amplifier 10, and is converted into an acoustic output by the speaker 11 and output into the space. It's being radiated.

On the other hand, the analog sensor serving as the acoustic input to electrical output converter that receives the information transmitted by the caller may be an ordinary microphone, but in this circuit system, the A pair of microphones 12 and 13 are used.

As described later, this pair of microphones 12 and 13 are provided within the speaker/phono structure of the present invention.
The microphones are geometrically arranged so that when the acoustic output radiated from the speaker 11 is incident, the incident sound pressure vectors on both microphones are as similar as possible. The outputs of both microphones 12.13 are input to one of the forward and reverse re-inputs of the differential amplifier 14 for the transmission system. Therefore, in principle, if the output vectors of the microphones 12.13 are the same, this difference The acoustic output components that have passed from the speaker 11 to the microphones 12 and 13 do not appear in the output of the dynamic amplifier 14.

On the other hand, since it is unlikely that the caller is in the exact same position as the speaker 11, the transmission information issued by the caller is input to both microphones 12 and 13 using different sound pressure vectors. Therefore, the transmission information corresponding to the input vector difference between the outputs of each microphone is amplified and appears at the output of the differential amplifier 14. This transmitted voice information is further amplified sufficiently by a subsequent appropriate amplifier 18.1 However, in the case of a normal hand-held handset, the distance between the mouth and the microphone is constant, so the input voice level may vary. On the other hand, in the case of a speaker/phono, the position between the speaker and the microphone is not constant, and even more so when many people are participating in a conversation at the same time, the position of the person closest to the microphone may vary. It is normal for there to be a difference of 20 to 30 dB in microphone reception level between people who are far away.

Therefore, in this circuit system, the -] portion of the output of the amplifier 16 is guided to the AGO circuit 17, and the
By generating the GO voltage and controlling the voltage-controlled attenuator 15 provided on the amplifier input side with a control voltage of q, and adjusting the signal strength of the amplifier input, the level fluctuation of the input signal at the input terminal of the amplifier 16 is kept constant. I try to keep it within range.

The transmitted information signal that has been amplified to a sufficient extent by the amplifier 18 is passed through an appropriate bus sofa 18 with high input impedance and low output impedance, and then the coupling transformer side is set to the first port 81, as described above. is supplied to the second port 62 of the impedance isolator 6, and is sent out from the coupling transformer to the telephone line. In addition, the output signal of the amplifier 16 is also supplied to the second port 72 of the second impedance isolator 7 via a second similar buffer γ18. The first port 71 of the second impedance isolator 7 is grounded as described above.

On the other hand, the transmitting signal is equally supplied to either the normal phase or negative phase re-input of the differential amplifier 8 for the receiving system, considering the above-mentioned wiring relationship. Therefore, the transmitting information issued by the caller is canceled by the differential amplifier 8 for the receiving system, and does not go around to the receiving signal reproduction system.

In order for this desired effect to occur, the re-inputs to the differential amplifier 8 must be vectorially identical to each other. For this reason, it is of course necessary to manage the characteristics of both buffers 18 and 19 to keep them the same, but the impedance of the telephone line actually fluctuates by about 20% depending on the distance conditions of the other party, etc. is also a well-known fact. Therefore, if we do not provide an impedance isolator 6 that prevents impedance fluctuations at the other port from being observed from either port, line impedance fluctuations will affect the output of the buffer 18, A vectorial difference may occur between both buffers 18 and 19. When such a difference occurs, the differential amplifier 8 amplifies the signal in accordance with the difference, so that this undesirable transmission information signal component is eventually radiated from the speaker 11 as an acoustic output. Of course, this is undesirable from the viewpoint of howling countermeasures.

An impedance isolator or bidirectional impedance converter 6 is a circuit that prevents such line impedance fluctuations from affecting the output of the buffer 19.

Impedance isolator 6 (7) used here
), referring to FIG. 2. First, between the first port +32 (72), two amplifiers 21 and 21' are connected in opposite directions. It is connected to the. Of course, if left as is, as long as each amplifier has a significant amplification factor, oscillation will occur without fail. Therefore, each amplifier 2
1 and 21', attenuators 20 and 20' each having an amplification factor higher than that of the amplifier are inserted in series. With such a configuration, bidirectional signal transmission is ensured in this circuit, and the reverse transfer conductance of each amplifier 21, 21' itself is small, and in addition, an attenuator or attenuator 20 with a large attenuation degree is used. , 20' are inserted, so that even if there is a change in the impedance loaded on one port, the other port is not affected by it.

In principle, such an impedance isolator may be only one impedance isolator 6 in FIG. 1. However, such impedance
Although the isolator does not oscillate, the signal still goes around in one cycle, so it is expected that the frequency characteristics of the long sword impedance seen from one port will be quite complex. Therefore, even if this is the case, in order to maintain the vectorial identity of the two swords of the differential amplifier 8 at any frequency, it is necessary to install a second All you have to do is insert the impedance isolator 7.

With the above circuit configuration, the sound output from the speaker J711 is a positive feedback due to the so-called double canceling effect of the differential amplifier 14 for the transmitting system and the differential amplifier 8 for the receiving system. The speaker-phone structure of the present invention is an optimal speaker-phone structure for such a circuit system.
A speaker phone structure is shown in FIG. 3.4 as an embodiment of the present invention. This will be explained below.

The housing part 22, which constitutes the entire housing, consists in this case of an upper half 22a and a lower half 22b.

Each has a substantially cylindrical shape. The upper half and the lower half are internally separated acoustically by upper and lower partitions 22c. The upper half 22a substantially forms a speaker chamber 40 therein, and the lower half 22b substantially forms a microphone chamber 30 therein.

Although the present invention does not directly specify the material of the housing 22, synthetic resin is used in the practical example of the present applicant. In addition, the upper half 22a to the speaker chamber 4
0 and the lower half portion 22b to the microphone chamber 30 may be formed integrally, or may be formed separately and combined with each other by screw fitting or other suitable assembly means.

The speaker 11 is installed facing upward in the upper half 22a or the upper part of the speaker chamber 40, and the radiated sound is reflected by the downward cone-shaped 3606 omnidirectional reflector 24, and then passes through the sound extraction hole 23. It is diffused omnidirectionally in all directions of the radiation direction. Of course, one of the reasons for doing this is to make it possible for as many people as possible to talk at the same time. This is because it was intended to be. Furthermore, in order to prevent the vibrations of the speaker 11 from being transmitted to the lower half as much as possible, the speaker 11 is fixed to the upper half via a suitable damper 25. Of course,
The same effect can be obtained even if the speaker 11 is attached downward and the omnidirectional reflector 24 is attached upward. The speaker chamber 40 may be of a closed type or a rear open type, but since the internal sound pressure will not be so high, generally the sound pressure is radiated only through the sound extraction hole 23. It is preferable to use a closed type so that this can be carried out.

A microphone chamber 30 is formed in the lower half of the housing, and the pair of microphones 12 and 13 described above are housed in the microphone chamber 30, but the structure of this part and the relative positional relationship of each microphone are , which is clearly shown in FIG. 4, which is a cross section taken along the line IV--IV in FIG. In this embodiment, the interior of the lower half 22b is further divided into an upper circuit chamber 5o and a lower microphone chamber 30 by an upper and lower partition 22d.

The microphone chamber 3o has a diametrical acoustic partition 31, which doubles this chamber in the radial direction. An effective sound absorbing material 32 such as felt is attached to the partition 31 in order to increase the acoustic isolation effect between the two doubled chambers 30a and 30b. Therefore, it may be considered that there is a pair of microphone chambers dedicated to each microphone.

One microphone 12, 13 is provided in each chamber 30a or 30b, and in this case, each microphone 12, 13 is attached to a side surface of the partition plate 31 facing toward each chamber. However, the microphones are mounted so as to be separated from each other in the radial direction from the center 0 of the partition plate 31, and are mounted around the middle portion of the distance from the center position O to one end in the radial direction. Located in the lower half of the housing, each microphone chamber 3
An appropriate number of sound infiltration holes 29 are opened at appropriate intervals in the circumferential direction in the outer wall portions forming parts 0a and 30b, and sound input information from each direction is transmitted through the holes 28. -c is captured at each microphone 12.13.

However, in this outer wall portion as well, it is preferable not to provide the penetration hole 29 in a portion 33. so that a baffle portion or a reflecting portion that prevents or reflects sound from entering is formed over an angular range in the circumferential direction. There are 34. This is due to the following reason.

In the geometric arrangement of the housing 22 described above, each microphone 12.13 is equidistant from the sound source called speaker f, and the acoustic environment along the path from the sound source to each of these microphones is also approximately the same. You can think about it. Therefore, as mentioned above regarding the circuit system, the sound pressure vector emitted by speaker 1 is as follows for both microphones:
It can be assumed that they are under approximately the same conditions, and the vectors of the converted electrical outputs emitted by the microphones may also be approximately the same.

Therefore, as a desirable result, if the speaker phone structure shown in FIG. 3 is used to accommodate the microphones 12 and 13 for the circuit system shown in FIG. This will greatly help in canceling the output at the output of the differential amplifier 14 in the first place. As mentioned above, the circuit system shown in Figure 1 is separately disclosed by the applicant, but in place of this circuit system, a wooden speaker phone structure may be used, even if it is only by using known technology. If disclosed, it would be a common technology to receive the outputs of both microphones using a differential amplifier, and therefore, this speaker-phone structure can be effectively applied to such general circuit systems. .

On the other hand, the transmitted information spoken by the caller must have a significant level difference or phase difference between the two microphones 12 and 13. Considering this assumption, if the sound infiltration holes 29 described above are evenly distributed in the circumferential direction on the outer wall of the microphone chambers 30a and 30b dedicated to each microphone, the fourth In the figure, each direction is indicated by an arrow, but for each direction in the range from direction C to direction E, and each direction from the opposite direction, a pair of central partitions 31 is interposed. A significant input sound pressure vector difference or its converted electrical output torque difference occurs between the microphones 12,13. Therefore, transmission information output can be obtained at the output of the differential amplifier 14 without any problem in each of these directions, but transmission from a direction parallel or nearly parallel to the central partition, for example, direction A or the opposite direction. It should also be noted that sufficient effective sensitivity cannot be obtained if speech information is incident. It is conceivable that no significant input level difference can be obtained.

Therefore, in this preferred embodiment, the aforementioned baffles or reflectors 33,34 are formed on the walls of each microphone chamber 30a, 30b, respectively. Specifically, on the radial end side of one of the microphones installed offset with respect to the center O of the partition 31, over an angular range θ that constitutes the acoustic field of view of each corresponding microphone. A non-porous portion for blocking is formed, and this is used as a baffle or reflective portion 33,34. In this way, for example, in FIG. 4, the microphone 13 in the chamber 30a on the lower side of the diagram shows almost no sensitivity to acoustic information incident from the direction A, whereas the microphone 13 in the chamber 30b on the opposite side shows almost no sensitivity.
The microphone 12 located inside can exhibit sufficient sensitivity by taking into account the influence of reflection from the inside of the corresponding reflecting section 33. According to experiments, in order to guarantee sufficient effective sensitivity even when the reflection portions 33 and 34 are close to parallel to the partition 31, it is desirable that the viewing angle θ with respect to the center of the reflection portions 33 and 34 is approximately 1″45°. If the angle θ becomes larger than this, the detector consisting of a pair of microphones will start to exhibit directivity, and the advantage of omnidirectionality will be lost.However, the speaker-phone structure of the present invention is based on the principle. Since the main purpose of this structure is to prevent the acoustic output of the speaker force 11 from going around, being omnidirectional does not have a limited effect.

In the practical example of the present applicant, the circuit system shown in FIG.
7, and a battery 28 serving as a power source for providing operating energy is housed in a replaceable manner in the upper housing.

Although the present invention has been described above based on the embodiment, the present invention is not limited to this embodiment, and includes various modifications. In short, there are chambers that house omnidirectional speaker means and a pair of microphones, and these two chambers are integrally constructed, and each microphone also has its own dedicated chamber that is acoustically separated from each other. The gist of the present invention can be achieved as long as the microphones are housed in a room and are located at approximately the same sound propagation path position with respect to a single speaker. In the illustrated embodiment, the non-unidirectional speaker means is composed of the speaker 11 and the reflecting plate 24, but of course, this non-directional speaker means can be achieved by arranging a plurality of individual small speakers in the circumferential direction or by any other arbitrary method. Directivity can be satisfied. Additionally, it is preferable that the microphone alone be non-directional.

However, at least one pair is used, and even if more than one pair is used, a structure resistant to knowling can be provided as long as the gist of the present invention is followed.

In any case, as detailed above, according to the present invention, it is possible to provide a practical speaker phone structure with extremely high feedback prevention ability as a speaker phone structure for a telephone.
It is obvious that it will make a major contribution to this type of field in the future.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an example of a transmitting/receiving circuit suitable for incorporating the speaker phone structure of the present invention, FIG. 2 is a schematic diagram of a circuit of an example of an impedance isolator, and FIG. 3 is a speaker phone structure of the present invention. FIG. 4 is a schematic vertical cross-sectional configuration diagram of one embodiment of the present invention, and FIG. 4 is a sectional view taken along the line IV--IV in FIG. In the figure, 2 is a coupling transformer installed between the telephone line and
6 and 7 are impedance isolators or bidirectional impedance converters, 8 is a differential amplifier for the receiving system, 11 is a speaker, 12 and 13 is a microphone, 14 is a differential amplifier for the transmitting system, and 22 is the speaker as a whole.・Phone structure l\Using, 22a is the upper half of the housing, 22b
24 is a reflection plate for constructing an omnidirectional speaker means in combination with the speaker, 27 is an electronic circuit system, 28 is a support ring or wiring board for the electronic circuit system, 30
3 is a microphone room, 30a and 30b are rooms dedicated to each microphone, 31 is a partition plate, 33.34 is a reflector or a reflector, 40 is a speaker room, and 50 is a circuit room. Applicant Unison Co., Ltd.

Claims (1)

[Claims] One (7) A speaker and a microphone are housed in the housing, and information received from the telephone line is radiated into space from the speaker, and information sent from surrounding callers is captured by the microphone and sent to the telephone line. Phone speaker/
It has a phono structure, and has chambers each housing an omnidirectional speaker means and at least one pair of microphones, and both chambers are integrally constructed, and each microphone is also acoustically separated from each other. A speaker for a telephone, characterized in that each microphone is housed in a dedicated chamber, and each of the microphones is located at approximately the same sound propagation path position with respect to the speaker means. Phono structure.