JP2001157298A - Optical microphone and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical microphone that can eliminate external disturbing vibration and attain high sensitivity and high S/N. SOLUTION: A partition wall 22 partitions off the inside of a unit case 21 into two air chambers 23a, 23b, diaphragms 3a, 3b are stretched in the air chambers 23a, 23b respectively, an optical unit consisting of a light emitting element 41 (42) and a light receiving element 51 (52) is placed to the air chamber 23a (23b) to form two microphone units 2a, 2b, the one microphone unit 2a is used for receiving sound and the other microphone unit 2b is brought into a sound shaft state to be used for noise cancellation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical microphone for picking up vibration of a vibrating plate vibrated by sound waves by light and a method of manufacturing the same, and more specifically, to effectively eliminate disturbance vibration such as handling noise. The present invention relates to an optical microphone capable of obtaining a high-quality audio signal with an improved S / N ratio, and a manufacturing method for easily assembling the optical unit.

[0002]

2. Description of the Related Art An optical microphone uses light as a medium for converting mechanical vibration of a diaphragm into an electric signal, and has a long history and various proposals have been made so far.
The basic configuration will be described with reference to a first conventional example of FIG. The optical microphone includes a cylindrical housing (for example, a microphone grip) 1 and a microphone unit 2 housed in the housing 1.

The microphone unit 2 has a bottomed cylindrical unit case 21 having an open end and an air chamber 23 therein. A disk-shaped diaphragm 3 is stretched over the opening of the unit case 21. I have. The diaphragm 3 is made of a metal or resin film, and the surface 31 to be irradiated with light is mirror-finished so that light is not irregularly reflected.

On the bottom 22 of the unit case 21, a light emitting section 4 for irradiating light toward the diaphragm 3 and a light receiving section 5 for receiving light reflected from the diaphragm 3 are provided. On the light emitting unit 4 side, a shielding wall 24 for preventing light from the light emitting unit 4 from directly entering the light receiving unit 5 is provided.

[0005] The vibration plate 3 vibrates by sound waves arriving through an opening 111 provided in the front surface 11 of the housing 1. As a result, a change occurs in the reflected light traveling toward the light receiving unit 5. By converting this light change into an electric signal and amplifying it, an audio signal proportional to the sound wave can be obtained.

Next, a second conventional example of another embodiment will be described with reference to FIG. In this optical microphone, a light shielding plate 32 is provided vertically at the center of the diaphragm 3. The light emitting unit 4 and the light receiving unit 5 are provided symmetrically on both side walls of the unit case 21 with the light shielding plate 32 as a center.

On the optical axis of the light emitting section 4, there is provided a convex lens L for condensing light substantially around the tip of the light shielding plate 32. On the optical axis of the light receiving unit 5, a convex lens L for condensing light from the light shielding plate 32 on the light receiving unit 5 is provided.

According to this configuration, when the sound wave vibrates the vibration plate 3 upon receiving the sound wave, the light shielding plate 32 vibrates accordingly. As a result, a change occurs in the amount of light incident on the light receiving unit 5, so that an audio signal proportional to the sound wave is obtained as in the first conventional example.

[0009]

The optical microphone also has a diaphragm in the same manner as the dynamic microphone and the condenser microphone. For example, when a hand microphone is used, the handling noise is transmitted to the diaphragm through the microphone housing. However, no means has been taken to prevent this.

In the optical microphone, what is important is how to accurately capture the mechanical vibration of the diaphragm as a light change. However, in the first conventional example, the light from the light emitting section is irregularly reflected. The light does not efficiently enter the light receiving unit. Due to this effect, improvement in S / N ratio and sensitivity cannot be expected much. Further, in the second conventional example, optical adjustment of the lens system is extremely difficult, and a high-level adjustment technique is required to adjust these. Therefore, it has not yet been commercialized.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and a first object of the present invention is to make it possible to reliably remove disturbance noise such as handling noise. To provide an improved optical microphone. A second object of the present invention is to reduce the power consumption of an optical unit including a light emitting unit and a light receiving unit,
It is another object of the present invention to provide an optical microphone whose output can be obtained as a digital signal. Also,
A third object of the present invention is to provide an optical microphone that efficiently guides light from a light emitting unit to a light receiving unit to achieve high sensitivity and a high S / N ratio. A fourth object of the present invention is to provide a method of manufacturing an optical microphone that can easily and accurately assemble a light emitting unit and a light receiving unit of an optical unit.

In order to achieve the first object, the present invention provides a vibration plate which receives a sound wave, vibrates, a light emitting element which irradiates light to the vibration plate, and a light receiving element which receives reflected light thereof. A first microphone unit disposed on a sound receiving surface side of a microphone housing, wherein the first microphone unit includes: a first microphone unit; A second microphone unit disposed in a sound-insulated state on the non-sound receiving side of the microphone housing as a back-to-back unit, and each of the microphone units has an air chamber formed independently of each other via a partition. The first microphone unit includes a first diaphragm that vibrates due to sound waves and housing-propagating vibration, a first light emitting element that irradiates the first diaphragm with light, and reflected light thereof. A first light receiving element for receiving light; a second vibrating plate vibrating only by the housing propagation vibration; and a second light emitting element for irradiating the second vibrating plate with light. And a second light receiving element for receiving the reflected light is provided. The output of the first and second light receiving elements is input to a differential input type converter to remove a noise signal due to the housing propagation vibration. It is characterized by doing.

The first microphone unit and the second microphone unit
Since the microphone units are back-to-back via the partition, for example, housing-propagating vibration such as handling noise is transmitted to the first diaphragm and the second diaphragm of each microphone unit almost simultaneously. Therefore, by inputting the output of each light receiving element to the differential input type converter, a noise signal due to the housing propagation vibration is removed.

In this case, the differential input type converter is an FET.
Preferably, the impedance converter is composed of
According to this, it is possible to cancel the electromagnetic wave noise and the electrostatic noise arriving at the impedance converter.

According to a preferred embodiment of the present invention, the first
The light-emitting element and the first light-receiving element, and the second light-emitting element and the second light-receiving element are each formed of the partition wall such that their respective light focal points are focused on the maximum amplitude displacement point of the vibrating film opposed thereto. It is provided in the central part.

According to this, the vibration of the vibrating membrane can be accurately detected, and the optical path length between the light emitting element and the light receiving element can be minimized. In this case, interfering interference light that does not pass through the reflection of the diaphragm is prevented between the first light emitting element and the first light receiving element and between the second light emitting element and the second light receiving element. It is preferable to provide a light shielding plate. Further, each of the light emitting elements and the light receiving elements may be provided with a lens for condensing light on the diaphragm.

In the present invention, each of the diaphragms is made of a synthetic resin film sheet, and a light reflection film made of a mirror-finished metal thin film is formed on at least the inner surface on the air chamber side. According to this, minute vibrations on the order of nm can be reliably captured.

In order to achieve the second object, the present invention provides a diaphragm which vibrates by receiving a sound wave, a light emitting element which irradiates light to the diaphragm and a light receiving element which receives reflected light thereof. In the optical microphone, the vibration of the diaphragm is captured by the light receiving element as a light change and converted into an audio signal, the light emitting element has a frequency of 10 KHz or more and a duty ratio of 1: 3 (lighting: extinguished) ) It is characterized by being driven by the above driving pulses.

According to this, the power consumption of the optical unit can be reduced as compared with the case of always lighting, which is suitable when a battery is used as a power supply. In addition, since the output of the light receiving element appears as a pulse, it is not necessary to separately convert the output of the light receiving element into a digital signal by an A / D converter when digitally processing the signal.

As the light receiving element, it is preferable to use a photovoltaic element of a photovoltaic voltage output type such as a solar cell or a photodiode by a bias-free method. In other words, this type of light receiving element improves the response speed and frequency characteristics by flowing a bias current, but generates noise inside the element due to the bias current, so that it becomes difficult to catch the minute vibration of the diaphragm. Because. Since the band handled by the optical microphone is an audio signal, the response speed of the light receiving element does not need to be so fast, and it is more important to reduce the noise component than that.

In order to achieve the third object, the present invention provides a vibration plate which vibrates by receiving a sound wave, a light emitting element which irradiates light to the vibration plate, and a light receiving element which receives reflected light thereof. A bottomed cylindrical housing having an air chamber with an opening on the sound receiving surface side and a predetermined volume inside, wherein the optical microphone converts the vibration of the diaphragm to a light signal by capturing the vibration of the diaphragm as light change by the light receiving element. And a diaphragm having a light reflecting film on an inner surface stretched over the opening of the housing, and disposed on the opening side of the housing so as to irradiate light toward the bottom side of the housing. A light-emitting unit, a reflector provided on the bottom side of the housing, and reflecting light from the light-emitting unit toward a light reflecting film of the diaphragm; and a light-reflecting unit provided on the bottom side of the housing. And a light receiving unit for receiving light reflected by the film.

Further, the third object is to provide a housing having a light reflecting surface formed in a concave spherical shape having a parabolic surface, and a light reflecting film on an inner surface in an opening of the light reflecting surface. The present invention is also achieved by a configuration in which a diaphragm is stretched, and a light emitting unit and a light receiving unit are arranged symmetrically on the opening side of the light reflecting surface around the focal point of the light reflecting surface. Can be.

In any case, a planar light-emitting body and a light-receiving body in which the respective elements are arranged in a matrix, for example, can be used for the light-emitting part and the light-receiving part. Therefore, both the light emission amount and the light reception amount can be increased, and the light leakage is small, so that the minute vibration of the diaphragm can be accurately detected.

By providing a mask having a light-transmitting opening of a predetermined shape on at least one of the light-emitting surface of the light-emitting element and the light-receiving surface of the light-receiving element, the optical path width and the light shape of light emission and reception can be arbitrarily determined. Can be changed to

When a light emitting element and a light receiving element are arranged adjacent to each other on a supporting substrate facing the diaphragm, a light shielding plate made of a conductive material is provided between the elements, and the height and width thereof are appropriately selected. By doing so, not only the distribution and angle of light emission can be adjusted arbitrarily, but also electromagnetic shielding and electrostatic shielding between elements can be performed. In this case, it is preferable that an electric insulating film is formed on the light shielding plate.

In order to achieve the fourth object, the present invention provides a vibration plate which vibrates by receiving a sound wave, a light emitting element which irradiates light to the vibration plate and a light receiving element which receives reflected light thereof, And a support substrate that supports each of these elements,
A substantially V-shaped or U-shaped concave groove is formed in the support substrate, and the light-emitting element and the light-receiving element are opposed to the concave groove such that the focal point of the light is located on the diaphragm. In the method for manufacturing an optical microphone disposed on a side wall, the light emitting element and the light receiving element are attached to predetermined positions of a flexible substrate, and then the flexible substrate is bent to form a concave groove of the support substrate. And the light-emitting element and the light-receiving element are arranged in the concave groove via the flexible substrate.

As described above, since the light emitting element and the light receiving element are mounted on the flexible substrate in advance, and are arranged in the concave groove of the support substrate, the assembling workability is greatly improved. become. When the light emitting element and the light receiving element are mounted at predetermined positions on the flexible substrate, a light shielding plate may be provided between them.

[0028]

Next, embodiments of the present invention will be specifically described with reference to the drawings.

First, the first embodiment shown in FIG. 1 will be described. The microphone includes a housing 1 formed in a cylindrical shape, for example, and the microphone unit 2 is housed in the housing 1 via a cushion member 6 made of, for example, viscoelastic rubber.

In this embodiment, the housing 1 is formed of a cylindrical container made of metal such as aluminum, and a plurality of openings 111 are formed concentrically on the front surface 11 (upper end in FIG. 1) as sound receiving holes. I have. Although not shown, a microphone unit 2 is provided in the housing 1.
Drive circuit and a signal output plug are incorporated. The use of the microphone is not particularly limited, such as a hand microphone or a microphone for a mobile phone or a personal computer.

The microphone unit 2 has a cylindrical unit case 21 having both ends opened. The unit case 21 is divided into a first air chamber 23a and a second air chamber 23b by a partition wall 22. . First air chamber 23a
And the second air chamber 23b are chambers having the same volume and independent from each other. The first diaphragm 3a and the second
The diaphragm 3b is stretched under the same tension. The first air chamber 23a and the second air chamber 23b have ventilation holes 211 and 212 communicating with the outside, respectively.

The light emitting section 4 and the light receiving section 5 are provided in the unit case 21 so as to face each other in the diameter direction of the case. In this embodiment, the light emitting section 4 has two light emitting elements 41 and 42 which are optically insulated by the partition wall 22, and one of the light emitting elements 41 is directed toward the first diaphragm 3a on the first air chamber 23a side. The other light emitting element 42 is arranged so as to emit light, and the other light emitting element 42 is arranged so as to emit light toward the second diaphragm 3b on the second air chamber 23b side. Each of the light emitting elements 41 and 42 may be an LED (light emitting diode).

The light receiving section 5 also has two light receiving elements 51 and 52 which are optically insulated by the partition 22. One of the light receiving elements 51 is a light reflected from the first diaphragm 3a on the side of the first air chamber 23a. And the other light receiving element 52 is arranged on the side of the second air chamber 23b so as to receive the reflected light from the second diaphragm 3b.

As shown in FIG. 2, the light receiving element 5
Reference numerals 1 and 52 are connected to a differential input impedance converter 50 composed of an FET (field effect transistor). For each of the light receiving elements 51 and 52, a solar cell or a photodiode is used.

According to this embodiment, the microphone unit 2 is composed of the first and second two microphone units 2.
a and 2b. That is, the first diaphragm 3a,
The first microphone unit 2a is formed by the light emitting element 41 and the light receiving element 51, and the second diaphragm 3b
And the light emitting element 42 and the light receiving element 52 form a second microphone unit 2a.

The first microphone unit 2a and the second microphone unit 2b are back-to-back via a partition wall 22, the first microphone unit 2a is arranged on the sound receiving surface side, and the second microphone unit 2b is located inside the housing 1. It is arranged on the side opposite to the sound receiving surface. The rear side (the lower side in FIG. 1) of the second microphone unit 2b is sound-insulated by the sealing plate 12, and the second microphone unit 2b functions as a disturbance noise canceling unit.

Each of the diaphragms 3a and 3b is, for example, ABS, P
Resin film such as ET, PPS (base thickness: 1-2)
.mu.m), and at least on its inner surface are formed light reflecting surfaces 31a and 31b formed by mirror-finish processing of a metal thin film layer. In addition, for example, Al, Ti, Ni,
Au or the like is used, and can be formed on the resin film by a plating method, a vapor deposition method, or a sputtering method.

The partition 22 is made of a disk having an outer shape substantially the same as the inner diameter of the unit case 21 and is integrally attached to the inner peripheral surface of the unit main body 21 so as not to leak light. The partition 22 is formed much thicker than the diaphragms 3a and 3b. Therefore, the partition wall 22 does not vibrate due to a sound wave or handling noise.

According to the microphone having this configuration, the first diaphragm 3a on the sound receiving surface vibrates not only by sound waves but also by housing propagation vibrations (disturbance vibrations) such as handling noise. On the other hand, the second diaphragm 3b on the non-sound receiving side does not communicate with the outside air, and vibrates only by disturbance vibration.

Therefore, by inputting the outputs of the respective light receiving elements 51 and 52 to the differential input type impedance converter 50, the noise due to the disturbance vibration picked up by the first diaphragm 3a and the second diaphragm 3b cause the noise. The picked-up noise is cancelled, and only a signal by a sound wave is extracted.

Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment also includes the first and second two microphone units 2a and 2b, which are back-to-back by the partition wall 22 as in the first embodiment, but differs from the first embodiment. And how the light emitting unit 4 and the light receiving unit 5 are attached to the first microphone unit 2a and the second microphone unit 2b.

That is, in the second embodiment, the first
In the microphone unit 2a, the light emitting element 41 and the light receiving element 51 are arranged at the center of the partition wall 22 as an adjacent pair, and also in the second microphone unit 2b, the light emitting element 42 and the light receiving element 52 are adjacent to each other. Are arranged at the center of the partition 22.

As described above, by disposing the light emitting section 4 and the light receiving section 5 at the center of the partition wall 22, the diaphragms 3a, 3b
, The minute vibration caused by the sound wave can be reliably detected in the vicinity of the maximum amplitude, so that both the S / N ratio and the sensitivity can be increased.

In this case, light shielding plates 71a, 71 are provided between the light emitting section 4 and the light receiving section 5 to prevent light from passing from the light emitting section 4 to the light receiving section 5, so-called interference light and transmitted light.
1b are erected vertically. Further, the light emitting unit 4 and the light receiving unit 5 are mounted on the partition wall 22 via the support substrate 7,
It is preferable to mount the impedance converter 50 on the support substrate 7.

Next, modifications of the above embodiments will be described with reference to FIGS. Since the first microphone unit 2a and the second microphone unit 2b have the same configuration, this modification will be described with respect to one of the first microphone units 2a.

When the light emitting element 41 and the light receiving element 51 are arranged on the partition 22 via the support substrate 7 as in the second embodiment, as shown in FIG. 72a and 72b are formed so that the light of the light emitting element 41 and the light receiving element 51 are focused on the diaphragm 3a.

As described above, by forming the inclined portions 72a and 72b on the support substrate 7 in advance, the light emitting element 41 and the light receiving element 51 can be assembled very accurately. Further, the condenser lens L is attached to the light emitting element 41 and the light receiving element 51, and the cylindrical light guide 7 is provided.
By covering the diaphragm 3 and 73, it becomes possible to more surely focus light on the diaphragm 3a.

When the light emitting element 41 and the light receiving element 51 are provided on the inner wall of the unit case 21 as in the first embodiment, as shown in FIG. The recesses 213 and 214 are formed so as to be directed toward the center of the plate 3a.
The light-emitting element 41 and the light-receiving element 51 may be accommodated in 3,214.

As shown in FIG. 6, the axis of the concave portion 213 on the side for housing the light emitting element 41 is directed to the critical angle θ of light with respect to the diaphragm 3a. The recess 214 is formed in parallel with the vibration surface of the diaphragm 3a, and the light receiving element 51 is accommodated therein. According to this, the light emitted from the light emitting element 41 travels along the light reflecting surface 31 of the diaphragm 3a and is taken into the light receiving unit 5 as it is. Even in this case, the vibration of the diaphragm 3a can be regarded as a light change.

As still another modification, as shown in the sectional view of FIG. 7A and the plan view of FIG.
Masks 91, 9 having light-transmitting over-opening portions 91a, 92a on the light-emitting surface of light-emitting portion 4 and the light-receiving surface of light-receiving portion 5, respectively.
According to this, the shape of the light-transmitting openings 91a and 92a is appropriately selected and, for example, a circle, a square, or an ellipse is formed, so that the light path width and the light shape of light emission and reception are changed. It can be arbitrary. In addition,
The mask may be provided on either the light emitting unit 4 or the light receiving unit 5.

As shown in FIG. 7, when the light emitting section 4 and the light receiving section 5 are arranged adjacent to the supporting substrate 7 facing the diaphragm, a predetermined height is provided between them. A light-shielding plate 71 having a width and a width is provided. By using the light-shielding plate 71 as a conductive material, electromagnetic shielding or electrostatic shielding between the elements 4 and 5 can also be performed. In this case, the light shielding plate 7
1 is preferably coated with an electrically insulating coating. Further, the light shielding plate 71 may be provided so as to surround the light emitting unit 4 and / or the light receiving unit 5. Note that each of the above modifications is
The present invention is applicable to a case where one unit is used alone.

Next, a third embodiment of the present invention shown in FIG. 8 and a fourth embodiment shown in FIG. 9 will be described. Note that the third and fourth embodiments may be used alone as one unit, or may be used as two units to cancel disturbance noise as in the first and second embodiments. Good.

In the microphone unit 2A according to the third embodiment shown in FIG. 8, the unit case 21 has an open bottom at one end (upper side in FIG. 8) and an air chamber 23 having a predetermined volume inside. A diaphragm 3 having a cylindrical shape and having a light reflection film 31 in a central opening thereof
Are stretched under a predetermined tension.

The light emitting section 4 is disposed at a side position of the diaphragm 3 so as to emit light toward the bottom 22a of the unit case 21. The light emitting section 4 is provided on the bottom 22a.
A reflecting plate 24 is provided which is inclined at a predetermined angle so as to reflect the emitted light toward the diaphragm 3. Also,
A pedestal 25 is formed on the bottom part 22a so that the light reflected from the light reflection film 31 of the diaphragm 3 is incident substantially at a right angle. The pedestal 25 is provided with the light receiving part 5.

According to the microphone unit 2A,
Light from the light emitting unit 4 is reflected by the reflector 24 toward the diaphragm 3, further reflected by the light reflecting film 31 of the diaphragm 3, and reaches the light receiving unit 5. In this state, when the diaphragm 3 vibrates due to the sound waves, the amount of light received by the light receiving unit 5 changes accordingly.

According to the third embodiment, the light-emitting section 4 can use a planar light-emitting body (LED array) in which a large number of LEDs are arranged in a matrix, for example. Accordingly, since a planar light-receiving body such as a photodiode array can be used, the amount of light incident on the light-receiving section 5 can be increased, whereby the S / N ratio and sensitivity can be improved. The height can be reduced.

Next, in the microphone unit 2B according to the fourth embodiment of FIG. 9, a spherical mirror 26 having a paraboloid is provided in the unit case 21. In this embodiment, a donut-shaped sealing plate 27 is fitted into the upper opening of the spherical mirror 26 and its central opening 2
The diaphragm 3 having the light reflection film 31 is stretched on the reference numeral 71 with a predetermined tension.

In this case, it is preferable that the diaphragm 3 is provided such that its center (the maximum amplitude point position) coincides with the focal point O of the spherical mirror 26. Lower surface 27 of sealing plate 27
In FIG. 1, a light emitting unit 4 and a light receiving unit 5 are provided at point-symmetric positions with respect to a focal point O of a spherical mirror 26. According to the fourth embodiment, not only a pair of the light emitting unit 4 and the light receiving unit 5 but also a plurality of them can be provided.

According to the microphone unit 2A,
Light from the light emitting section 4 is reflected by the spherical mirror 26 and is focused on the focal point O. Then, the light reflecting film 3 of the diaphragm 3
1 and further reflected by the spherical mirror 26 to enter the light receiving unit 5.

According to this configuration, as in the third embodiment, the amount of light incident on the light receiving section 5 can be increased, thereby improving the S / N ratio and the sensitivity. Further, by simply providing the diaphragm 3 on the focal point O of the spherical mirror 26, light can be easily focused on the diaphragm 3. Moreover,
A condenser lens and the like are not required, and a very simple configuration can be achieved.

As a matter common to the above embodiments, when driving the light emitting section 4 (or the light emitting element 41),
In the present invention, driving is performed by a driving pulse having a frequency of 10 kHz or more and a duty ratio of 1: 3 (lighting: extinguished).

The sound frequency handled by the microphone is usually about 100 Hz to 20 KHz. For example, in the case of a telephone band, it is about 300 Hz to 3.4 KHz. The audio signal can be sampled without inducing.

As described above, by driving the light emitting section 4 by a pulse train, it is possible to reduce the power consumption of the optical unit as compared with the case where the light emitting section 4 is always turned on. In addition, since the output of the light receiving element appears as a pulse, it is not necessary to separately convert the output of the light receiving element into a digital signal by an A / D converter when digitally processing the signal.

As for the light receiving element, it is preferable to use a photovoltaic element of a photovoltaic voltage output type such as a solar cell or a photodiode by a biasless method. That is, this type of photovoltaic element has a photocurrent output and a photovoltaic voltage output for each output type, but when the output type is a photocurrent output, noise is generated by the current flowing inside the element. Sometimes.

On the other hand, in the case of photovoltaic voltage output, no photocurrent flows inside the device, and there is no possibility that noise due to the current is generated. Therefore, noise is lower than in the case of photocurrent output. For this reason, by using a photovoltaic element of a photovoltaic output type such as a solar cell or a photodiode by a biasless method,
A small change in the diaphragm can be reliably detected without being affected by noise, and the S / N ratio and sensitivity can be improved.

Next, a method of manufacturing an optical microphone according to the present invention will be described. In manufacturing an optical microphone, it is important how to assemble the light emitting unit and the light receiving unit by positioning their relative positional relationship easily and accurately. In order to focus the light of the light emitting unit and the light receiving unit on the diaphragm, it is necessary to give them a predetermined inclination.

Therefore, as exemplified in FIG.
In order to give a predetermined inclination angle to the light emitting unit 4 and the light receiving unit 5,
A gutter-shaped hemispherical groove 75 made of, for example, a paraboloid is formed on the support substrate 7, and the light emitting unit 4 and the light receiving unit 5
In the present invention, as shown in FIG. 11, a flexible substrate 8 that can be bent flexibly along the hemispherical groove 75 is used in the present invention.

That is, while the flexible substrate 8 is flattened, the light emitting unit 4 and the light receiving unit 5 are mounted, and
A light shielding plate 81 is erected between them. Also, if necessary, an impedance converter and the like may be provided on the flexible substrate 8.
Implement on top. Thereafter, the flexible substrate 8 is bent and inserted into the hemispherical groove 75. Thus, the light emitting section 4 and the light receiving section 5 are arranged in the hemispheric groove 75 with a predetermined relative positional relationship.

As described above, according to the present invention, if attention is paid only to the alignment between the light emitting unit 4 and the light receiving unit 5, the light emitting unit 4 and the light receiving unit 5 do not need to be finely adjusted. Can be easily attached to the support substrate 7. This can significantly reduce work steps and costs.

In this example, the light emitting portion 4 and the light receiving portion 5 are given a predetermined inclination angle by the hemispherical groove 75, but the groove may be a V-shaped groove or a bathtub in cross section. Further, the flexible substrate 8 may be a simple flexible film or sheet. The material is not particularly limited.

[0071]

As described above, according to the present invention,
In the optical microphone, disturbance noise such as handling noise can be reliably removed. Further, the power consumption of the optical unit including the light emitting unit and the light receiving unit can be reduced, and the output can be obtained as a digital signal. Further, light from the light emitting section can be efficiently guided to the light receiving section, and high sensitivity and high S / N ratio can be achieved. Further, according to the manufacturing method of the present invention, the light emitting unit and the light receiving unit of the optical unit can be easily and accurately assembled.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an optical microphone according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of an impedance converter used in the present invention.

FIG. 3 is a schematic sectional view of an optical microphone according to a second embodiment of the present invention.

FIG. 4 is a schematic partial sectional view showing a first modification of the embodiment.

FIG. 5 is a schematic partial sectional view showing a second modification of the above embodiment.

FIG. 6 is a schematic partial sectional view showing a third modification of the above embodiment.

FIG. 7 is a schematic partial sectional view and a plan view showing a fourth modification of the embodiment.

FIG. 8 is a schematic sectional view of an optical microphone according to a third embodiment of the present invention.

FIG. 9 is a schematic sectional view of an optical microphone according to a fourth embodiment of the present invention.

FIG. 10 is a schematic perspective view showing a light emitting unit and a light receiving unit assembled by the manufacturing method of the present invention.

FIG. 11 is an explanatory diagram for explaining the manufacturing method of the present invention.

FIG. 12 is a schematic cross-sectional view showing an optical microphone as a first conventional example.

FIG. 13 is a schematic sectional view showing an optical microphone as a second conventional example.

[Explanation of symbols]

 Reference Signs List 1 housing 111 opening 2 microphone unit 2a first microphone unit 2b second microphone unit 21 unit case 211,212 vent hole 213,214 recess 22 partition 23,23a, 23b air chamber 24 reflection surface 25 pedestal 26 spherical mirror 27 sealing plate 271 center opening 3 diaphragm 3a first diaphragm 3b second diaphragm 4 light emitting unit 41 light emitting element 5 light receiving unit 50 impedance converter 51 light receiving element 6 cushion member 7 support substrate 71 light shielding plate 72a, 72b inclined portion 73, 74 Light guide 75 Hemispherical groove 8 Flexible substrate 91, 92 Mask 91a, 92a Light transmitting aperture

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04R 3/00 320 H04R 3/00 320

Claims (15)

[Claims] 1. A vibration plate that receives a sound wave and vibrates, a light-emitting element that irradiates light toward the vibration plate, and a light-receiving element that receives reflected light of the vibration plate. An optical microphone which converts the light into a light signal and converts it into an audio signal, comprising: a first microphone unit disposed on the sound receiving surface side of the microphone housing; A second microphone unit arranged in a sound-insulating state on the sound surface side, wherein each of the microphone units has an air chamber formed independently of each other via a partition, and a sound wave and a casing are provided in the first microphone unit. A first diaphragm vibrating by body propagation vibration, a first light emitting element for irradiating the first diaphragm with light, and a first light receiving element for receiving reflected light thereof are provided. In addition, the second microphone unit includes a second diaphragm that vibrates only by the casing propagation vibration, a second light emitting element that irradiates the second diaphragm with light, and a second light receiving element that receives reflected light thereof. Wherein the output of the first and second light receiving elements is input to a differential input type converter to remove a noise signal due to the housing propagation vibration. 2. The apparatus according to claim 1, wherein said differential input type converter is an impedance converter comprising an FET.
The optical microphone according to 1. 3. The first light emitting element and the first light receiving element,
And the second light emitting element and the second light receiving element are both
3. The optical microphone according to claim 1, wherein the optical microphone is provided at a central portion of the partition wall such that each light focus is focused on a maximum amplitude displacement point of the vibrating membrane opposed thereto. 4. An interfering light that does not pass through the reflection of the diaphragm between the first light emitting element and the first light receiving element and between the second light emitting element and the second light receiving element. The optical microphone according to claim 3, further comprising a light blocking plate for blocking. 5. The lens according to claim 1, wherein each of the light emitting element and the light receiving element is provided with a lens for condensing light on the diaphragm. The optical microphone according to the item. 6. Each of the diaphragms is made of a synthetic resin film sheet, and a light reflection film made of a mirror-finished metal thin film is formed on at least an inner surface of the diaphragm on the air chamber side. An optical microphone according to any one of claims 1 to 5. 7. A vibrating plate that vibrates by receiving a sound wave, a light emitting element that irradiates light to the vibrating plate, and a light receiving element that receives light reflected from the vibrating plate, wherein the vibration of the vibrating plate is transmitted to the light receiving element. An optical microphone that converts the light into a light signal and converts the light into an audio signal, wherein the light emitting element is driven by a driving pulse having a frequency of 10 KHz or more and a duty ratio of 1: 3 (lighting: extinguished). Optical microphone. 8. A vibration plate that receives a sound wave and vibrates, a light emitting element that irradiates light to the vibration plate, and a light receiving element that receives light reflected by the vibration plate, and transmits vibration of the vibration plate to the light receiving element. An optical microphone which converts a light change into a sound signal and converts the light into an audio signal, wherein a photovoltaic element of a photovoltaic voltage output type is used as a light receiving element by a bias-free method. 9. A vibration plate that receives a sound wave and vibrates, a light emitting element that irradiates light toward the vibration plate, and a light receiving element that receives light reflected by the vibration plate, wherein the vibration of the vibration plate is transmitted to the light receiving element. An optical microphone that converts the light into a light signal and converts the light into a sound signal, wherein at least one of the light emitting surface of the light emitting element and the light receiving surface of the light receiving element has a mask having a light transmitting opening of a predetermined shape. An optical microphone, which is provided. 10. A vibration plate that receives a sound wave and vibrates, a light emitting element that irradiates light to the vibration plate, and a light receiving element that receives reflected light thereof, wherein the vibration of the vibration plate is transmitted to the light receiving element. An optical microphone that converts the light into a light signal and converts the light into an audio signal, wherein the light-emitting element and the light-receiving element are disposed adjacent to each other with a light-shielding plate interposed therebetween, on a support substrate facing the diaphragm. An optical microphone, comprising: a conductive material. 11. The optical microphone according to claim 9, wherein an electrical insulating film is formed on the light shielding plate. 12. A vibration plate that receives a sound wave and vibrates, a light emitting element that irradiates light to the vibration plate, and a light receiving element that receives light reflected by the vibration plate, wherein the vibration of the vibration plate is transmitted to the light receiving element. An optical microphone that converts a light into a sound signal and converts the light into an audio signal. A diaphragm having a light reflecting film on the inner surface, a light emitting unit disposed on the opening side of the housing so as to irradiate light toward the bottom side of the housing, and a light emitting unit provided on the bottom side of the housing. A reflector that reflects light from the light emitting unit toward the light reflecting film of the diaphragm,
An optical microphone provided on a bottom side of the housing and receiving a light reflected by the light reflecting film. 13. A vibration plate that receives a sound wave and vibrates, a light emitting element that irradiates light to the vibration plate, and a light receiving element that receives light reflected by the vibration plate, and transmits the vibration of the vibration plate to the light receiving element. An optical microphone that converts the light into a sound signal by converting the light into a light signal, comprising: a housing having a light reflecting surface formed in a concave spherical shape having a parabolic surface; A diaphragm having a reflective film is stretched, and a light emitting portion and a light receiving portion are arranged symmetrically on the opening side of the light reflecting surface with respect to a focal point of the light reflecting surface. An optical microphone that features. 14. A vibrating plate that receives a sound wave and vibrates, a light emitting element that irradiates light to the vibrating plate, a light receiving element that receives reflected light thereof, and a supporting substrate that supports these elements. A substantially V-shaped or U-shaped concave groove is formed in the support substrate, and the light-emitting element and the light-receiving element face each other so that the focal point of the light is located on the diaphragm. In the method for manufacturing an optical microphone disposed on a side wall to be formed, after the light emitting element and the light receiving element are mounted at predetermined positions on a flexible substrate, the flexible substrate is bent to form a concave portion of the support substrate. A method of manufacturing an optical microphone, comprising inserting the light emitting element and the light receiving element in the groove through the flexible substrate while inserting the light microphone along the groove. 15. The optical microphone according to claim 10, wherein a light shielding plate is provided between the light emitting element and the light receiving element at a predetermined position of the flexible substrate. Production method.