EP1152638A1 - Optical microphone element and optical microphone - Google Patents
Optical microphone element and optical microphone Download PDFInfo
- Publication number
- EP1152638A1 EP1152638A1 EP00966509A EP00966509A EP1152638A1 EP 1152638 A1 EP1152638 A1 EP 1152638A1 EP 00966509 A EP00966509 A EP 00966509A EP 00966509 A EP00966509 A EP 00966509A EP 1152638 A1 EP1152638 A1 EP 1152638A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- diaphragm
- optical microphone
- opening
- sound wave
- sound
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R25/00—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception
- H04R25/40—Arrangements for obtaining a desired directivity characteristic
- H04R25/402—Arrangements for obtaining a desired directivity characteristic using contructional means
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R23/00—Transducers other than those covered by groups H04R9/00 - H04R21/00
- H04R23/008—Transducers other than those covered by groups H04R9/00 - H04R21/00 using optical signals for detecting or generating sound
Abstract
Description
- This invention relates in an optical microphone device which uses an optical microphone element, and it is related to the optical microphone element and the optical microphone device that have excellent noise decrease characteristics.
- A general microphone has a fault that a wind pressure causes a noise and obstructs a call when used in a motorcycle or windy environment. Japanese Patent Publication No. 58-36879 discloses a microphone device for noise prevention.
- The microphone device disclosed here stores a microphone element in the frame inside of the body. A compressed foaming body with a consecutive bubble fills a back portion of the frame body and surroundings of the element. The forming body with a consecutive bubble also fills the space between an inside protection board with a hole provided in front of the microphone element and an outside protection film with a hole provided in front of the frame body. On the edge of the frame body, a taper that spread out toward the front is formed. By covering the side and the back of the microphone element with foaming body as stated above, sensitivity becomes single directivity.
- An electret microphone for decreasing noise shown in Figure 7 and a dynamic microphone shown in Figure 8 are known. Figure 7 shows the structure of the electret microphone. Figure 7A shows a front view, Figure 7B shows a sectional side view, and Figure 7C shows a rear view. The electret microphone stores in a
body 10 adiaphragm 3 which oscillates by the sound pressure, and anelectrostatic element 4 which converts the oscillation of thediaphragm 3 to an electric signal. In this structure, voice enters through anopening 1 provided in thefront face 10a of the body. Asmall opening 2 is also provided in off site part of the back-plane 10b of thebody 10. - Figure 8 shows the structure of the dynamic microphone. Figure 8A shows a sectional side view, and Figure 8B shows a rear view: A
magnet 21 having an opening is stored in abody 20, and acoil 22 is twisted around themagnet 21. Adiaphragm 23 is set up in the front to confront themagnet 21. Asmall hall 23 is provided in the off site part in the back-plane 22b of thebody 20 so that a littlelarger hole 24 may be connected to a hole of themagnet 21. A sound pressure gradation caused by an oscillation of adiaphragm 23 is detected as a gradation of magnetic flux density by themagnet 21 on which acoil 22 is twisted, and this is converted to an electric signal. In the conventional microphone device shown in figure 7 and figure 8, if the sound which enters through the front face and the sound which enters through the back-plane face are equivalent against the diaphragm, these sounds are canceled by each other, and the microphone doesn't take influence by the sound. - In the microphone device disclosed in Japanese Patent Publication 58-36879, and figure 7 and figure 8, there was a limit of noise decrease capability. Sound from the front face direction and sound from the back-plane direction did not reach in the diaphragm symmetrically. Therefore, a noise decrease effect was 5-7 dB at most, and a microphone device with increased S/N ratio is not realized. On the other hand, an optical microphone device has been noticed as a microphone device that may follow the variation of the weak sound wave, and that has the high sensitivity and wide-band characteristics which does not depend on a use environment.
- Figure 6 shows the structure of the head part of the conventional optical microphone device. A
diaphragm 31 that oscillates by a sound wave is provided inside of themicrophone head 30, and asurface 31a at the side that a sound wave hits is exposed in the outside. Therefore, asound wave 37 that reached in thissurface 31a oscillates thediaphragm 31. The space inside of thehead 30 is divided to a portion facing asurface 31a and another portion facing anopposite surface 31b. In the portion facing thesurface 31b, alight source 32 such as an LED irradiating a light beam in thesurface 31b of thediaphragm 31 from a slant, alens 33 to make a light beam from this light source 32 a predetermined beam diameter, aphotodetector 35 which receives a reflection light reflected in thesurface 31b, and alens 34 to zoom a displacement of an optical path of the reflection light caused by the oscillation of thediaphragm 31 are provided. - In this structure, when a sound wave hits the
surface 31a of thediaphragm 31, and adiaphragm 31 oscillates, a receiving position of thereceiving surface 35a of the reflection light changes. If aphotodetector 35 is composed as a position sensor, an electric signal that met the oscillation of thediaphragm 31 from the irradiation location of the reflection light is taken out. This is the basic structure of the optical microphone device. However, even such optical microphone device is used, a noise decrease effect can't be expected very much. This is because adiaphragm 31 oscillates by the noise which reaches adiaphragm 31 and this is piled as a noise signal by oscillation by theusual sound wave 37. Therefore, it is an object of this invention to provide an optical microphone device with energizing the characteristics of the optical microphone device, and to provide an optical microphone of high noise decrease effect. - The optical microphone element of this invention comprises:
- a diaphragm which oscillates by the sound pressure;
- a storage container which the diaphragm is stored in and which has a first opening and a second opening provided in symmetrical positions to each other and confront the diaphragm;
- a light source which irradiates a light beam in the diaphragm; and
- a photodetector that receives a reflection light of the light beam irradiated in the diaphragm and which outputs a signal coping with the oscillation of the diaphragm. Furthermore, in the optical microphone element of this invention, the diaphragm, the light source and the photodetector are arranged so that a directivity response pattern on the first opening side and a directivity response pattern on the second opening side may be symmetrical to each other. An optical microphone device of this invention comprises:
- the optical microphone element;
- a substrate which the optical microphone element is carried on; and
- a cover that covers the first opening and the second opening symmetrically toward the substrate so that the sound wave may go through;
- wherein the incidence of the sound wave through the cover via the first opening and the second opening is made equally.
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- Figure 1 shows a structure of an optical microphone element of an embodiment of this invention.
- Figure 2 shows an appearance figure of an optical microphone device of this invention.
- Figure 3 shows a decomposition figure that shows the internal structure of the optical microphone device of this invention.
- Figure 4 shows a directivity response pattern figure of the sensitivity of the optical microphone element of this invention.
- Figure 5 shows a figure to explain the sound intensity of the microphone element put on the short distance field and the far range field.
- Figure 6 shows a structure of the conventional optical microphone device.
- Figure 7 shows a structure of the conventional electret microphone device.
- Figure 8 shows a structure of the conventional dynamic microphone device. In these figures, 100 is optical microphone element, 40 is storage container, 31 is diaphragm, 32 is light source, 35 is photodetector, 38 is the first opening, 39 is the 2nd opening, 54 is cover and 50 is substrate.
-
- Figure 1 shows a point part configuration of an
optical microphone element 100 that relates for an embodiment of this invention. The same code is put to the same part with the conventional element shown in figure 6, and the detailed explanation is omitted.
In the optical microphone element of the invention, adiaphragm 31 which oscillates by thesound wave 37 is provided in the central part of astorage container 40. Then, on both sides of the storage container, a1st opening 38 and a2nd opening 39 are set up to become symmetrical location to each other against adiaphragm 31. In this structure, a sound wave may enter from both openings into thestorage container 40 to oscillate thediaphragm 31. - As stated above, in the optical microphone shown in figure 1, When a sound pressure of a sound wave from the
1st opening 38 and that from the2nd opening 39 are equal, these two sound waves never oscillate adiaphragm 31 as they interfere each other on bothsides diaphragm 31. When two microphones that have equal sensitivities are arranged close and they receive sound wave which occurred in a far range, the two microphones detect the sound wave equally. - Figure 5 shows a characteristic curve of the distance vs sound intensity from the sound source. Generally, as shown in the figure, a sound wave occurs from the mouth of the person in a short distance from microphone element. In other words, most voice occurs at the short distance from this microphone element.
The voice of the person of this short distance has globular field characteristics so that it may be shown by a circular curve. On the other hand, the sound wave that occurs in the far range such as the sound wave by the noise has the characteristics of the plane field. Although the sound intensity of the globular wave is about the same along the spherical surface or the envelope and changes along the radius of that glob, the sound intensity of the plane wave almost becomes the same at all the points. - Optical microphone shown in figure 1 can be thought to associate two microphones. Therefore, when this was put on the far range field, the sound waves which have almost the same intensity and phase characteristics from the
1st opening 38 and the2nd opening 39 comes in thediaphragm 31, to interfere with each other, and those influences are decreased. On the other hand, as a sound wave from the short distance field enters from the1st opening 38 and the2nd opening 39 non-uniformly, a sound wave from the short distance field oscillates adiaphragm 31, and it is taken out as a signal by thephotodetector 35. - Figure 4 shows the directivity response pattern of the sensitivity of the optical microphone shown in figure 1. The optical microphone shown in Figure 1 has almost "8" shaped symmetrical directivity comprising a pattern in the front face direction to go to the
1st opening 38 and a pattern in the back-plane direction to go to the2nd opening 39. When the optical microphone shown in figure 1 is used, noise such as surroundings noise is imputed as sound from the far range field as shown in figure 5. In this case, as the sound wave enters equally from the1st opening 38 and the2nd opening 39 and interferes on thediaphragm 31 to extinct, adiaphragm 31 is never oscillated. - On the other hand, voice from the speaking person is inputted as sound from the short distance field. Therefore, reception sensitivities in two microphone elements M1, M2 are different to each other as shown in figure 5. Id est, the sound which enters from the
1st opening 38 and the sound from the2nd opening 39 are different in intensity, and adiaphragm 31 is oscillated. Thus an optical microphone which decreased the influences of the noise can be realized. - Figure 2 is an appearance figure which shows the point part configuration of the optical microphone device which the
optical microphone 200 in figure 1 was carried on. Figure 2A shows a front view, Figure 2B shows a side elevation view, and Figure 2C shows a rear view. Figure 3 is the decomposition figure that shows internal structure. Referring to figure 2 and figure 3, the configuration of the optical microphone device using an optical microphone is explained. Theoptical microphone 200 shown in Figure 1 is put almost on the center of the printedboard 50. Theoptical microphone 200 is put on the printedboard 50 so that the1st opening 38 may face upward and the2nd opening 39 may face downward. In this structure, theoptical microphone 200 achieve the directivity response pattern of the equal sensitivity in top and bottom as shown in figure 4. - An off
site circuit 51 to drive thisoptical microphone 200 is arranged on both surface of the printedboard 50 to surround theoptical microphone 200. To thesubstrate 50,cable 52 for microphone output and powering is connected. The printedboard 50 withsponges cover net cover - As explained above, the optical microphone device and the optical microphone element of this invention have the structure that a sound wave comes from the openings set up in symmetrical location against the diaphragm. In this structure, a sound wave such as noise from the far range field is cancelled and a sound wave from the short distance field is amplified and outputted. Therefore, an audio device that remarkably decreased the influences of the noise can be realized.
Claims (3)
- An optical microphone element comprising:a diaphragm which oscillates by a sound pressure;a storage container which the diaphragm is stored in and which has a first opening and a second opening provided in symmetrical positions to each other and confront the diaphragm;a light source which irradiates a light beam in the diaphragm; anda photodetector that receives a reflection light of the light beam irradiated in the diaphragm and which outputs a signal coping with the oscillation of the diaphragm.
- The optical microphone element according to claim 1,
wherein the diaphragm, the light source and the photodetector are arranged so that a directivity response pattern on the first opening side and a directivity response pattern on the second opening side may be symmetric to each other. - An optical microphone device comprising:the optical microphone element according to claim 1;a substrate which the optical microphone element is carried on; anda cover that covers the first opening and the second opening symmetrically toward the substrate so that the sound wave may go through;wherein the incidence of the sound wave through the cover via the first opening and the second opening is made equally.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP29422199 | 1999-10-15 | ||
JP29422199A JP2001119796A (en) | 1999-10-15 | 1999-10-15 | Optical microphone element and optical microphone system |
PCT/JP2000/007162 WO2001028286A1 (en) | 1999-10-15 | 2000-10-16 | Optical microphone element and optical microphone |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1152638A1 true EP1152638A1 (en) | 2001-11-07 |
Family
ID=17804913
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP00966509A Withdrawn EP1152638A1 (en) | 1999-10-15 | 2000-10-16 | Optical microphone element and optical microphone |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP1152638A1 (en) |
JP (1) | JP2001119796A (en) |
WO (1) | WO2001028286A1 (en) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3522212B2 (en) | 2000-11-10 | 2004-04-26 | 株式会社ケンウッド | Small displacement detection device using sound, etc. |
IL142689A0 (en) * | 2001-04-19 | 2002-03-10 | Phone Or Ltd | Optical microphone construction |
JP2002354593A (en) * | 2001-05-25 | 2002-12-06 | Olympus Optical Co Ltd | Microphone device |
JP3953752B2 (en) | 2001-06-19 | 2007-08-08 | 株式会社ケンウッド | Diaphragm structure of photoacoustic transducer |
KR101418750B1 (en) * | 2012-12-27 | 2014-07-11 | 전자부품연구원 | Optical microphone and manufacturing the same |
GB2558963A (en) * | 2017-01-18 | 2018-07-25 | Cirrus Logic Int Semiconductor Ltd | Flexible membrane |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS6031409B2 (en) * | 1980-07-17 | 1985-07-22 | 富士通株式会社 | laser microphone |
JPS61100715A (en) * | 1984-10-24 | 1986-05-19 | Nec Corp | Optical microphone |
JPS63260400A (en) * | 1987-04-17 | 1988-10-27 | Matsushita Electric Ind Co Ltd | Microphone |
-
1999
- 1999-10-15 JP JP29422199A patent/JP2001119796A/en active Pending
-
2000
- 2000-10-16 WO PCT/JP2000/007162 patent/WO2001028286A1/en not_active Application Discontinuation
- 2000-10-16 EP EP00966509A patent/EP1152638A1/en not_active Withdrawn
Non-Patent Citations (1)
Title |
---|
See references of WO0128286A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO2001028286A1 (en) | 2001-04-19 |
JP2001119796A (en) | 2001-04-27 |
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PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
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Effective date: 20010713 |
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RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: PHONE-OR LTD |
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RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: KOTS, ALEXANDER, C/O PHONE-OR LTD Inventor name: PARITSKY, ALEXANDER Inventor name: KOBAYASHI, OKIHIRO, C/O KENWOOD CORPORATION Inventor name: TAKAHASHI, KAZUO, C/O KENWOOD ENGINEERING CORP |
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Free format text: STATUS: THE APPLICATION HAS BEEN WITHDRAWN |
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Withdrawal date: 20020510 |