WO1996025018A1

WO1996025018A1 - Microphone device

Info

Publication number: WO1996025018A1
Application number: PCT/JP1996/000292
Authority: WO
Inventors: Masashi Ohkubo; Toru Sasaki
Original assignee: Sony Corporation
Priority date: 1995-02-10
Filing date: 1996-02-09
Publication date: 1996-08-15

Abstract

A microphone device comprising at least three microphone elements arranged at prescribed intervals in a direction perpendicular to the axis of directivity, and a circuit for summing the output signals of the microphone elements. The microphone elements, which are unidirectional, are arranged at substantially regular intervals in such a manner that they all have planes of incidence toward a source of sound. This microphone device shows sharp directivity in middle range of frequency required by the input means of a voice recognizing device and high sensitivity against voice inputs from the front, while minimizing the level of noises from sides.

Description

TECHNICAL FIELD The present invention relates to a microphone device for improving directivity with respect to a sound source, and more particularly, to a car navigation system in which various command signals are input using voice. Microphone device useful for voice input means of voice recognition devices used in systems, convenience stores, etc. “Pokoseki” 5-to o Background technology Generally, to collect sound emitted from a sound source Microphone devices used for various purposes are required to have various directivities depending on the purpose of use.

Therefore, conventional microphone devices are either omnidirectional, which has a fixed sensitivity to sound sources located in any direction, or have directivity, which has a fixed sensitivity to sound sources located in a certain direction. Some have. For a microphone device having directivity, the sensitivity in the main axis direction of the microphone unit is set to 1 and the direction orthogonal to the main axis is set. There is provided a unidirectional microphone device having a sensitivity of 0.5, and a superdirective microphone device having a sensitivity of 0.5 or less in a direction orthogonal to the main axis of the microphone unit.

As a microphone device having super directivity, one end of a cylindrical acoustic tube having a perforated slit for perforation on its peripheral surface is attached to one end of a main axis in a direction directing in the axial direction of the acoustic tube. A so-called shotgun-type microphone device, which is a unidirectional microphone device with a microphone unit attached to it, and a secondary device in which two unidirectional microphone units are linearly arranged in the main axis direction. A sound pressure gradient type microphone device is known.

The so-called shotgun microphone device described above mainly exhibits super-directivity in the high frequency range, whereas the secondary sound pressure gradient type microphone device mainly exhibits super-directivity in the low frequency range. Present.

By the way, microphones used for voice input means of voice recognition systems used in force navigation systems and convenience stores, where various command signals are input using voice, are subject to voice recognition. Since it is used for the purpose of collecting only the voice of the person who becomes the target, sharp directivity is required in the midrange.

By the way, the conventionally used unidirectional microphone device is susceptible to noise from side directions other than the direction in which the main axis of the microphone unit is directed. Is not suitable. In other words, sounds other than the sound that should be collected are collected, so that accurate command signals cannot be obtained.

In addition, a shotgun type microphone device and a secondary sound pressure gradient type The earphone device has a problem that it is not only unable to satisfy the sharp directivity in the middle frequency range required for the voice input means of the voice recognition device, but is expensive. DISCLOSURE OF THE INVENTION An object of the present invention is to solve the problems of conventional microphone devices and to provide a microphone device useful as a voice input unit of a voice recognition device.

Another object of the present invention is to realize a sharp directivity in a middle frequency range required for input means of a voice recognition device, to have high sensitivity to a voice input from the front, and to extremely reduce a noise component input from a side. An object of the present invention is to provide a microphone mouth phone device that realizes less sound collection.

The microphone opening microphone device according to the present invention proposed to achieve the above-described object is arranged in a substantially single horizontal plane, is substantially equidistant from the sound source, and is substantially equal to the sound source. It comprises at least three directional microphone elements arranged at intervals and an adder for adding output signals from each microphone element.

Here, each microphone element is arranged in a single plane parallel to the diaphragm of each microphone element. A unidirectional microphone element is used for each microphone element.

Further, the microphone device according to the present invention has at least three microphone elements, each microphone element being disposed at a predetermined distance in a direction orthogonal to the main axis of directivity, and a microphone element provided with each microphone element. And an adder for adding the output signal. Where each microphone The mouthpiece elements are each composed of a unidirectional microphone element, and the sound collection surfaces face the same direction with respect to the sound source, and are arranged at substantially equal intervals.

Further, the microphone device according to the present invention includes a single microphone element and at least three sound guide paths for guiding sounds having equal lengths and coming from the outside to the microphone element. The openings at one end of each of the three sound guides are arranged so that the distances from the sound source are equal to each other and form a single horizontal plane. It is opposed to a microphone element. Here, the openings at one end of each of the three sound guide paths are arranged so as to form a plane substantially perpendicular to the single horizontal plane.

In this microphone device, an omnidirectional microphone element is used as the microphone element.

Further, the microphone element may be a unidirectional microphone element.

Further, a sound guide section provided with three sound guide paths may be provided on the front surface of the microphone element in the sound collection plane direction.

Still other objects of the present invention and advantages obtained by the present invention will become more apparent from the description of the embodiments described below with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of a microphone device according to the present invention <∑>. FIG. 2 is a plan view schematically showing the positional relationship between the microphone units and the directivities in the microphone device.

FIG. 3 is a perspective view showing an example in which the microphone device according to the present invention is applied to a voice input unit of a voice recognition device used in a force navigation system.

FIG. 4 is a characteristic diagram showing the directivity index frequency characteristics of the microphone device shown in FIG. 1 together with the directivity index frequency characteristics of the Gummic and secondary sound pressure gradient microphone devices.

Fig. 5 is a characteristic diagram showing the directional frequency characteristics when the distance between the microphone units in the microphone device is set to 3 cm. Fig. 6 is a graph showing the distance between the microphone units in the microphone device when the distance between the microphone units is 6 cm. FIG. 7 is a characteristic diagram showing the directional frequency characteristics when the distance is set to 12 cm. FIG. 7 is a characteristic diagram showing the directional frequency characteristics when the interval between the microphone units in the microphone device is set to 12 cm. .

FIG. 8 is a block diagram showing another configuration of the microphone device according to the present invention.

FIG. 9 is a characteristic diagram showing directivity frequency characteristics when the interval between each microphone unit in the microphone device shown in FIG. 8 is 6 cm.

FIG. 10 is a block diagram showing still another configuration of the microphone device according to the present invention.

FIG. 11 is a block diagram showing still another configuration of the microphone device according to the present invention.

FIG. 12 shows still another configuration of the microphone device according to the present invention. FIG.

FIG. 13 is a cross-sectional view of a principal part showing still another configuration of the microphone device according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, specific embodiments of a microphone phone device according to the present invention will be described with reference to the drawings.

As shown in FIG. 1, the microphone device according to the present invention includes three microphone unit 1, 2, 3 and a combiner 4 for adding and combining the outputs from these microphone units 1 _: 2, 3. And

As shown in Fig. 2, each of the microphone units 1, 2, and 3 has a single directivity. Here, the microunits 1, 2, 3 are arranged at equal intervals D in a direction orthogonal to the main axis of the directivity direction. Here, the interval D between the microphone units 1, 2, and 3 is set, for example, in a range of about 3 cm to 12 cm. The distance D between the microphone units 1, 2, and 3 is appropriately selected according to the size of the microphone unit used and the sound source to be collected, and is not limited to the above range. . The microphone units 1, 2, and 3 are arranged in parallel so that the main axes are located in a single horizontal plane. Furthermore, the diaphragm of each microphone element constituting each microphone unit is arranged so as to be located in a single plane parallel to the plane of these diaphragms.

The signal synthesizer 4 is a so-called wired addition and summation that directly connects the signal lines to which the outputs of the microphone units 1, 2, and 3 are supplied. A generator is used. The signal synthesizer 4 may be one that performs signal synthesis via an amplifier. Then, from the signal combiner 4, the outputs of the microphone units 1, 2, and 3 are combined and output.

By the way, the microphone device of the present embodiment is mounted on an automobile that receives a reference signal from a satellite, indicates a current position on a map displayed on a display screen, and guides a traveling direction. It is applied to the voice input means of the voice recognition device used in the used car navigation system. Specifically, as shown in FIG. 3, the microphone device is provided with a long housing 51 having a substantially rectangular cross-sectional shape, and each of the microphone units 1, 2, and 3 is provided in the housing 51. The microphone units 1, 2, and 3 are mounted so that the principal axes of directivity of the microphone units 1, 2, and 3 are parallel to each other, with the sound-collecting surface on which the diaphragms constituting each microphone element are located facing the front side. At this time, the intervals D i, D ₂ between the microphone units 1, 2, 3 are set to 55 mm. The microphone units 1, 2, and 3 are arranged in parallel so that the principal axes of the directions are located in a single horizontal plane. Each of the microphone units 1, 2, and 3 is It is mounted via a printed wiring board provided in the housing 51. A combiner 4 is provided on the printed wiring board, and each of the microphone units 1, 2, and 3 is connected to the combiner 4 via a wiring pattern of the printed wiring board, and each output is connected to the combiner 4. 4 is added and synthesized.

Further, each microphone unit 1, 2, 3 is arranged in the housing 51 such that the diaphragm of each microphone element is located in a single plane parallel to the plane of these diaphragms. That is, each micro The phone units 1, 2, and 3 are arranged in the housing 51 so that the positions in the front-back direction of the main shaft direction are matched.

On the front side of the housing 51 facing the sound-collecting surface of each of the microphone units 1, 2, and 3, a thin metal plate or a cloth front plate 52 with many small holes is attached. Have been. The front plate 52 absorbs sound so that sound incident on the front side of the housing 51 is reflected and does not enter each of the microphone units 1, 2 and 3. By providing such a front plate 52, each of the microphone units 1, 2, and 3 can reliably collect sound that enters only these microphone units 1, 2, and 3. it can.

A lead wire 53 for taking out the output from the synthesizer 4 to the outside is drawn out on one side surface of the housing 51.

This microphone device is configured to be applied to a voice input means of a voice recognition device used in a car navigation system mounted on a vehicle and used when installed in a vehicle. It is constructed so that the sound generated by the driver can be reliably collected and installed at a position where it will not interfere with driving. In the embodiment shown in FIG. 3, although not shown, the sunpiser is mounted on the rear side of the housing 51 so that it can be mounted on the surface of a sunshade for light shielding disposed above a driver's seat in an automobile or on a dashboard. Mounting means such as a clip to be gripped and hook-and-loop fasteners are provided.

In the microphone device of the present embodiment, since the microphone units 1, 2, and 3 are arranged in the housing 51 so that the positions in the front-back direction of the main shaft direction are matched, the microphone unit 1 does not protrude partly. It can be arranged along the surface of a mounting member such as a zigzag. According to Thus, even when the microphone device is placed in a car, the microphone device can be installed with sufficient danger avoidance without hindering the driving of the driver.

Here, when the microphone units 1, 2, and 3 are housed in the housing 51 whose back side is closed to form a microphone device, the incidence of sound from the back side is restricted. Not only a unidirectional microphone unit but also a bidirectional microphone unit may be used.

By the way, as shown in Figs. 1 and 2 above, this is one of the evaluation quantities for numerically grasping the directivity of the microphone unit in which the microphone units 1, 2, and 3 are arranged. When the directivity index was calculated, the directivity index frequency characteristic A as shown in Fig. 4 was obtained. In addition, FIG. 4 shows the directivity index and frequency characteristic A of the microphone device of the present embodiment calculated based on the frequency characteristics of the omnidirectional microphone device, together with the above-described shotgun type microphone device. The directional index frequency characteristic B and the directional index frequency characteristic C of the secondary sound pressure gradient microphone device are shown.

Here, the energy response of a directional microphone to a sound that is incident from all directions with equal probability and whose phase is completely irregular, and the energy-response of an omnidirectional microphone having the same frontal sensitivity are The ratio is called directivity, and the directivity is defined by the following equation (1). Directivity = f ⁴ⁿ D ² (Ω) άΩ

4π J ο 1)

D (θ) represents the ratio of the output voltage to the incident wave at an angle Ω and that of Ω = 0, and d Ω represents the small solid angle in the direction of the angle Ω.

If the directivity is symmetric with respect to the reference plane, the directivity is given by the following equation (2).

Directivity = + JD ² (9) sin0d0-

And the directivity index is given by the following equation (3)

Directivity = 10 log _1D (Directivity) (3)

Or the following equation (4)

Mo

Directivity = 10 1 og! (4)

M d

Is defined by In addition, M. Is the front sensitivity in a free sound field (plane wave), and M _diif is the diffuse sound field sensitivity. Here, since the directivity index of the unidirectional microphone is 1.478 dB, as is clear from FIG. 4, the microphone device of this embodiment and the shotgun type microphone device are: The directivity index in the low range, that is, the directivity is as sharp as a unidirectional microphone, but it exhibits sharp directivity in the midrange. On the other hand, the secondary sound pressure gradient microphone device has a sharp directivity in the middle and low frequencies. Further, the microphone device of the present embodiment exhibits sharp directivity in a high frequency range as compared with the shotgun type microphone device and the secondary sound pressure gradient type microphone mouth phone device.

As described above, in the microphone device of the present embodiment, since the outputs of the respective microphone units 1, 2, and 3 are added and synthesized by the synthesizer 4, the sound waves input to the respective microphone units 1, 2, and 3 are added. The corresponding output adds the in-phase component and cancels the out-of-phase component, and exhibits super-directivity at a frequency that depends on the interval D of each microphone unit 1: 2,3. In the microphone device of this embodiment, when the distance D between the microphone units 1, 2, and 3 shown in FIG. 2 described above was changed, when D = 3 cm, the frequency characteristics as shown in FIG. In addition, when D = 6 cm, the frequency characteristic as shown in Fig. 6 is exhibited. When D = 12 cm, the frequency characteristic as shown in Fig. 7 is exhibited. By setting the length to 4 to 8 cm, it is possible to perform collection with high sensitivity to the voice input from the front and very little noise from the side.

Here, in FIGS. 5 to 7 described above the principal axis direction is 0 ^beta, there is shown a frequency characteristics or directivity frequency characteristics for 4 0 ° direction and 9 0 ° direction relative to the main axis.

In addition, the microphone device according to the present invention is, for example, as shown in FIG. From the four microphone units 11 1, 1 2, 13, and 14 and the combiner 15 that adds and combines the outputs of the microphone unit 11, 1, 12, 13, and 14. It may be configured.

Also in this example, the microphone units 11, 12, 13, and 14 having unidirectionality are used. Here, the microphone units 11, 12, 13, 14 are arranged at equal intervals in the direction orthogonal to the main axis of the directivity direction, for example, at intervals of 6 cm. The interval between these microphone units 11, 12, and 13 is appropriately selected according to the size of the microphone unit used and the sound source to be collected. The microphone units 11, 12, and 13 are arranged in parallel so that the main axes are located in a single horizontal plane.

In the microphone device having such a configuration, a directional frequency characteristic as shown in FIG. 9 is obtained, and by increasing the number of microphone units arranged side by side, the directivity in a high frequency range becomes sharp.

Therefore, a plurality of unidirectional microphone units are juxtaposed at a predetermined distance from each other in the direction perpendicular to the main axis of the directivity, and the outputs of the respective microunits are added and combined by a combiner to produce an output signal. As a result, it is possible to realize a microphone-phone device having a sharp directivity in the mid-range, which is the main component of human speech.

By the way, in each of the above-described embodiments, the plurality of microphone units are arranged such that the diaphragms of the microphone elements constituting these microphone units are located in a single plane parallel to the plane of the diaphragms. As shown in Fig. 10, three or four microphone units 41, 42, 43 are located at the same distance R! You may make it arrange | position on the circumference which is located. Also in this case, the intervals D ₃ , D 4 of the respective microphone units 41, 42, 43 are equalized.

Further, in each of the above-described embodiments, the plurality of microphone units are arranged at equal intervals, but the intervals between the microphone units may be shifted within a range of about 1 to 1.2. That is, the deviation of the interval in the range of about 1 to 1.2 with respect to the wavelength of the human voice is within the error range for the directivity, and has no practical problem and hinders the object of the present invention. Not something.

Further, as shown in FIG. 11, a plurality of, for example, three microphone units 61, 62 and 63 are arranged vertically with respect to a horizontal plane P when viewed from the front in the arrangement direction. Even if there is a deviation of about 61, 62, or 63 in diameter, it is within an error range for the directivity, and there is no practical problem and does not hinder the object of the present invention.

In the case where the microphone device according to the present invention is used as a voice input device of a personal convenience, the interval between each microphone unit is set as a voice input device of a voice recognition device used in a car navigation system. It is desirable to widen the range of directivity as compared with the case where it is used. This is because when using the personal convenience, the head movement of the user becomes large. When this microphone device is used in a car navigation system, the movement of the driver is restricted, so reducing the interval between the microphone units improves the sound collection characteristics while improving the directivity. This is advantageous.

Here, they are juxtaposed at a predetermined distance from each other in a direction perpendicular to the main axis of directivity. Instead of obtaining the output signal by adding and combining the outputs of the plurality of microphone units obtained by the combiner with a combiner, sound waves are introduced into the waveguide at a position separated from each other by a predetermined distance in a direction perpendicular to the main axis of directivity. By mixing and inputting the signals to the microphone unit, an output signal can be obtained from one microphone unit.

This microphone device can be configured as shown in FIG. In this microphone device, three sound tubes 21, 22, and 23 are formed with an opening at one end side, and the openings are used as sound introduction ports 21 A, 22 A, and 23 A. It is composed of a director 20 connected at the output port on the other end side, and a microphone port 25 provided at the output port 2OA of the director 20. You.

Each sound tube 21, 22, 23 is positioned so that each sound inlet 21 A, 22 A, 23 A is located at a predetermined distance from each other in the direction perpendicular to the main axis of directivity. It is bent. Then, the director 20 mixes each sound wave incident from each of the sound wave inlets 21 A, 22 A, and 23 A at the connection portion 24 of each sound tube 21, 22, 23. Incident on the microphone unit 25. That is, each of the acoustic tubes 21, 22: 23 has a sound inlet 21 A, 22 A, and 23 A at a predetermined distance from each other in a direction perpendicular to the main axis of directivity. A sound passage portion for guiding each sound wave introduced from each sound wave introduction port 21A, 22A, 23A to the connection portion 24 is formed, and the connection portion 24 and the mixing portion for mixing each sound wave are formed. And ifes tfe "9.

Here, the respective sound wave introduction ports 21 A, 22 A, and 23 A of the director 20 are arranged so that the distances from the sound source are not equal to each other and form a single horizontal plane. That is, each sound inlet 21 A, 22 A, 23 A waves are arranged so that they are located on almost the same line or on a single circle around the sound source.

In the microphone device configured as described above, the in-phase components are added by mixing each sound wave incident from each sound wave introduction port 21 A, 22 A, and 23 A in the director 20. In addition, since the anti-phase components cancel each other out, each of the sound wave introduction ports 21 A, 22 A, and 23 A exhibits super-directivity at a frequency dependent on the distance D between the ports. A single microphone unit 25 can achieve sharp directionality in the sound range, and is highly sensitive to voice input from the front and has very little noise from the side.

My Kurohonyu two Uz Bok 2 5 used in the above-described microphones device, mounted on the end of the waveguide 2 0, collects sounds incident from the acoustic pipe 2 1, 2 2 ₃ 2 3 which are branched Therefore, it is necessary to use a non-directional sound source because the sound input from the side other than the direction to which each sound wave introduction port 21A, 22A, and 23A is directed, for example, is restricted. Can be. When an omnidirectional microphone unit is used, it also has sensitivity to waves from the back side and has a directional figure of eight, but this microphone device is used in a car navigation system installed in an automobile. When used as a voice input means of a voice recognition device used in a computer system, the back side is substantially closed and almost no sound is incident from the back side, so that the object can be sufficiently achieved.

When the omnidirectional microphone unit 25 is used, the impedance of the acoustic tubes 21, 22, and 23 is higher than that of the microphone unit 25. 22 The back of the microphone unit 25 to match the impedance of 2 and 23 It is desirable to adjust the impedance by closing the side.

Also, when a unidirectional microphone unit 25 is used, the sound coming from the rear side is not collected, so that the microphone unit 25 has the same characteristics as the microphone device shown in FIG. 1 described above. It can be.

Also, instead of the director 20 constituted by the acoustic tubes 21, 22, and 23 as described above, for example, as shown in a microphone device shown in FIG. 13, predetermined directions are perpendicular to the main axis of directivity. Acoustic passages 31, 32, 33 that guide the sound waves introduced from the acoustic wave inlets 31 A, 32 A, 33 A at a distance D, respectively, and acoustic passages 31, 31 A waveguide unit 30 formed with a mixing unit 34 for mixing the respective sound waves guided through 32 and 33 is used, and a microphone unit 35 is added to the mixing unit 34 of the director 30. It may be installed.

The distance between the acoustic passages 31 1, 32 A, 33 A and the mixing section 34 from the acoustic passage sections 3 1, 3 2, 3 3 is made equal so that the The sound waves introduced from 1 A, 32 A, and 33 A maintain their phase relationship with each other, and the mixing section 34 cancels out the opposite-phase component to which the in-phase component has been added. INDUSTRIAL APPLICABILITY In the microphone device according to the present invention, the output of at least three unidirectional microphone units arranged at a predetermined distance from each other in a direction perpendicular to the main axis of the directivity is synthesized. The output signal is obtained by adding and combining at, so that sharp directivity is realized in the midrange, Since it is possible to perform collection with high sensitivity to the voice input and very little noise from the side, the voice input means of the voice recognition device used in the car navigation system mounted on the car, By using it as a voice input means for the convenience, it is possible to accurately and reliably collect the voice of the driver or the operator.

Claims

The scope of the claims

1. At least three directional microphone elements arranged in a substantially single horizontal plane, at substantially equal distances from the sound source and at substantially equal intervals toward the sound source;

And an adding means for adding output signals from the microphone elements.

2. The microphone mouth phone device according to claim 1, wherein said microphone elements are arranged in a single plane parallel to a diaphragm of each microphone element.

3. The microphone device according to claim 1, wherein each of the microphone elements is a unidirectional microphone element.

4. At least three microphone elements, each microphone element being arranged at a predetermined distance in a direction orthogonal to the main axis of directivity,

And a summing means for summing the output signals from the microphone elements.

5. The microphone device according to claim 4, wherein each of the microphone elements is a unidirectional microphone element.

6. Each of the above microphone elements is constituted by a unidirectional microphone element, and the sound collecting surfaces are oriented in the same direction with respect to the sound source, and are arranged at substantially equal intervals. A microphone mouth phone device according to claim 4.

7. A single microphone element

Sounds of equal length and arriving from outside With at least three sound guideways leading to

The openings at one end of each of the three sound guides are arranged so that the distances from the sound source are equal to each other and form a single horizontal plane. A microphone device characterized by being opposed to a microphone element.

8. The method according to claim 7, wherein the opening at one end of each of the three sound guides is arranged to form a plane substantially perpendicular to the single horizontal plane. Microphone device.

9. The microphone device according to claim 7, wherein the microphone element is formed of an omnidirectional microphone element.

10. The microphone earphone device according to claim 7, wherein the microphone element is constituted by a unidirectional microphone element.

11. The sound pickup device according to claim 7, further comprising a sound guide provided on a front surface of the microphone element in a sound collection surface direction and provided with the three sound guide paths. Microphone device.