WO2007015324A1

WO2007015324A1 - Microphone element

Info

Publication number: WO2007015324A1
Application number: PCT/JP2006/309013
Authority: WO
Inventors: Kazuhiro Watanabe; Hiroyuki Sasaki
Original assignee: Tama-Tlo, Ltd.
Priority date: 2005-08-01
Filing date: 2006-04-28
Publication date: 2007-02-08
Also published as: JP2007043291A; KR20080031477A

Abstract

A microphone element using an optical fiber sensor, having a simple structure achieving lower production costs. An optical fiber (29a, 20b) is provided on a vibration sheet (13) for capturing vibration of a medium. The optical fiber (20a, 20b) has a core and a clad provided around the outer periphery of the core, a sensor (SP) for enabling a part of light being transmitted to interact with the surroundings, and a light source (14) for emitting light to an entry end of the optical fiber (20a, 20b), and a light receiving section (15) for detecting, through the sensor section (SP), light emitted from an exit end of the optical fiber (20a, 20b).

Description

Specification

Microphone element

Technical field

The present invention relates to a microphone element, and more particularly to a microphone element using an optical fiber sensor. Background art

[0002] Optical fibers have been widely used as means for transmitting signals, and sensors using optical fibers have been developed for various purposes in various systems.

Among these, microphones using optical fibers are described in the following patent documents (Japanese Patent Laid-Open Nos. 2002-232232, 2000-65633, and 11-252696).

[0003] Japanese Unexamined Patent Application Publication No. 2002-232999 describes an optical fiber loop interferometer type acoustic sensor and an acoustic detection method. A loop-shaped optical fiber that is passed through a diaphragm that vibrates with an acoustic signal.Converts vibrations transmitted to the diaphragm to electrical signals from changes in the intensity of interference light obtained by propagating light clockwise and counterclockwise through the fiber. It is.

[0004] Japanese Unexamined Patent Application Publication No. 2000-65633 describes an optical waveguide vibration sensor system for remote detection. The mechanical signal transmitted to the geophone from the interference pattern obtained by modulating the phase of the optical signal guided into the optical waveguide is converted into an electrical signal by the electrical signal generated by the geophone.

[0005] Japanese Patent Application Laid-Open No. 11 252696 describes a structure of a light modulation microphone. The light emitting / receiving section that accommodates the light emitting element and the light receiving element separated from each other by the partition and the optical waveguide that transmits light from the light receiving / emitting section are formed separately and integrated with the thin film diaphragm. The light of the light emitting part is reflected by the thin film diaphragm and received by the light receiving part. When the thin film diaphragm is vibrated by sound waves, the intensity of the light received by the light receiving part is modulated and converted into an electrical signal. It is.

[0006] However, the acoustic sensor described in Japanese Patent Laid-Open No. 2002-232999 is complicated as a whole device, and moreover, the device for detecting the interference light is expensive, so that it can be used as an acoustic sensor. There is a problem that becomes price.

Further, the optical waveguide vibration sensor system described in Japanese Patent Application Laid-Open No. 2000-65633 has a problem that the entire apparatus is complicated and the optical waveguide vibration sensor system becomes expensive. In addition, the microphone described in Japanese Patent Application Laid-Open No. 11-252696 has a problem in that a precise design is required and the manufacturing cost increases.

[0007] In addition, regarding the above optical fiber sensor, configurations using a so-called heterocore portion as a sensor are described in International Publication No. 97Z48994 and Japanese Patent Laid-Open No. 2003-214906.

However, in the pamphlet of International Publication No. 97Z48994 and Japanese Patent Laid-Open No. 2003-214906, there is no description about using a hetero-core type optical fiber sensor as a microphone.

Disclosure of the invention

Problems to be solved by the invention

[0008] A problem to be solved is that, in a microphone using an optical fiber sensor, it is difficult to reduce the manufacturing cost as a simple structure.

Means for solving the problem

[0009] The microphone element of the present invention includes a vibration sheet that captures vibration of a medium, a core provided on the vibration sheet, and a clad provided on an outer periphery of the core, and a part of the external environment of the transmitted light. An optical fiber having a sensor unit that enables interaction with the optical fiber, a light source that emits light to the incident end of the optical fiber, and the light emitted from the output end of the optical fiber via the sensor unit And a light receiving portion for detecting light.

In the microphone element of the present invention described above, an optical fiber is provided on a vibration sheet that captures vibrations of a medium. The optical fiber includes a core and a clad provided on the outer periphery of the core, and has a sensor unit that enables interaction with a part of the transmitted light.

Furthermore, a light source that emits light to the incident end of the optical fiber and a light receiving unit that detects light emitted from the output end force of the optical fiber via the sensor unit are provided.

[0011] In the microphone element of the present invention described above, preferably, the sensor unit includes the optical fiber. This is a hetero core part having a core diameter different from the core diameter of the bar, and is configured to be joined to the middle part of the optical fiber.

Alternatively, preferably, the sensor unit is configured such that a light transmitting member having a refractive index equivalent to a refractive index of the core of the optical fiber or a refractive index of the cladding is joined to a middle part of the optical fiber. It is.

In the microphone element of the present invention described above, the optical fiber is preferably provided on the vibration sheet so that the optical fiber is bent with the sensor portion as a top portion.

Alternatively, preferably, the optical fiber including the sensor portion is linearly provided on the vibration sheet.

[0013] In the microphone element of the present invention, preferably, the optical fiber is bonded to the vibration sheet.

Alternatively, preferably, the optical fiber is embedded in the vibration sheet.

The invention's effect

The microphone element of the present invention is a microphone using an optical fiber sensor, has a simple structure, and can be manufactured at low cost.

Brief Description of Drawings

FIG. 1 is a schematic configuration diagram of a microphone element according to a first embodiment of the present invention.

FIG. 2A and FIG. 2B are graphs showing the intensity of incident light and emitted light of the microphone device according to the first embodiment of the present invention.

FIG. 3A is a perspective view of the optical fiber in the vicinity of the sensor part SP for showing an example of the configuration of the sensor part, and FIG. 3B is a longitudinal sectional view in the vicinity of the sensor part.

FIG. 4A and FIG. 4B are cross-sectional views in the longitudinal direction in the vicinity of the sensor portion of the optical fiber, for illustrating an example of the configuration of the sensor portion.

FIG. 5 is a schematic configuration diagram of a main part of a microphone element according to a second embodiment of the present invention.

Explanation of symbols

[0016] 3 ... Hetero core part, 4 ... Interface, 13 ... Vibration sheet, 14 ... Light source, 15 ... Light receiving part, 16 ... Amplifier, 17 ... Speaker, 18 ... Computer, 20a, 20b … Light phino, 21, 31 ··· core, 2 2, 32 ··· Clad, 30 ··· Light transmitting member, SP… Sensor part, W… Leakage light

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of a microphone element of the present invention will be described with reference to the drawings.

[0018] i mm

FIG. 1 is a schematic configuration diagram of a microphone element according to this embodiment.

For example, optical fibers (20a, 20b) are provided by being attached to or embedded in a vibration sheet 13 that captures the vibration of the medium. The vibration sheet 13 can capture vibrations transmitted to a medium on which the resin sheet 13 such as air or water is placed, for example, a resin sheet or paper, and transmit the vibrations to the optical fiber (20a, 20b). Any material can be used.

The optical fiber (20a, 20b) has a configuration including a core and a cladding provided on the outer periphery of the core. The optical fiber 20a and the optical fiber 20b are configured to transmit light transmitted through the optical fiber (20a, 20b). It is connected by a sensor part SP that enables interaction with some external worlds. In the present embodiment, for example, the optical fibers (20a, 20b) are provided so as to be bent with the sensor part SP as the top.

Furthermore, the light is emitted from the light source 14 such as a laser diode or a light emitting diode that emits light to the incident end of the optical fiber (20a, 20b) and the light emitting end of the optical fiber (20a, 20b) via the sensor unit SP. A light receiving unit 15 such as a photodiode for detecting light is provided.

[0019] In the above configuration, when vibration is transmitted to the medium on which the resin sheet 13 such as air or water is placed and transmitted to the optical fiber (20a, 20b), the vibration is transmitted from the vibration sheet 13 to the optical fiber. (20a, 20b).

In the optical fibers (20a, 20b), sensor light of 14 light sources is transmitted and received by the light receiving unit 15.

At this time, in the sensor part SP provided in the middle part of the optical fiber (20a, 20b), the degree of interaction with the external environment changes corresponding to the transmitted vibration, and the intensity of the transmitted light changes. The intensity of the electrical signal obtained by receiving the output light from the optical fiber (20a, 20b) at the light receiving unit 15 is modulated in response to the vibration of the medium. In this way, the vibration is converted into an electrical signal. And function as a microphone. The output of the light receiving unit 15 can be amplified by the amplifier 16 and output from the speaker 17 as sound.

Alternatively, it can be captured as audio data in a computer 18 or a spectrum analyzer and subjected to desired data processing such as vibration frequency analysis.

FIGS. 2A and 2B are graphs showing the intensity of incident light from the light source 14 of the microphone element and the intensity of outgoing light received by the light receiving unit 15, respectively.

While the incident light has a constant intensity, the intensity of the emitted light is modulated in accordance with the vibration transmitted to the vibration sheet.

[0021] An optical fiber and a sensor unit constituting the microphone element will be described.

FIG. 3A is a perspective view of the optical fiber (20a, 20b) in the vicinity of the sensor portion SP to show an example of the configuration of the sensor portion SP, and FIG. 3B is a longitudinal sectional view in the vicinity of the sensor portion SP. It is.

For example, the optical fiber (20a, 20b) constituting the microphone element is a single mode fiber having a core diameter of 9 / zm, for example, and the optical fiber 20a and the optical fiber 20b are transmitted through the optical fiber (20a, 20b). It is connected by the sensor part SP that enables interaction with a part of the outside of the light to be transmitted.

The optical fibers (20a, 20b) have a core 21 and a clad 22 provided on the outer periphery thereof. The light from the light source 14 is also incident on the core 21 at the light incident end side force, and is emitted from the core 21 on the light emitting end side to the light receiving unit via the sensor unit SP.

The sensor part SP shown in FIGS. 3A and 3B is a hetero-core part 3 having a core diameter different from the core diameter of the optical fiber (20a, 20b), and includes a core 31 and a clad 32 provided on the outer periphery thereof. And have.

The diameter bl of the core 31 in the hetero-core portion 3 is smaller than the diameter aU of the core 21 of the optical fiber (20a, 20b), for example, al = 9 m and Η = 5 μm. Further, the length cl of the hetero-core part 3 is several mm to several cm, for example, about lmm.

The optical core (3) constituting the optical fiber (20a, 20b) and the sensor part SP is almost coaxial so that the cores are joined at the interface 4 perpendicular to the longitudinal direction. Etc. are joined together. As shown in FIGS. 3A and 3B, in the configuration in which the sensor part SP is joined to the middle part of the optical fiber (20a, 20b), the diameter bl of the core 31 in the hetero-core part 3 and the optical fiber (2 Oa , 20b) is different from the diameter al of the core 21 at the interface 4, and a part of the light leaks into the cladding 32 of the hetero-core part 3 due to the difference in the core diameter. When the diameters of the cores 21 and 31 are combined so as to reduce the leak W, most of the light enters the optical fiber 21 again and is transmitted. At this time, the insertion loss of the sensor is small, and the degree of leak W changes sharply due to changes in the external environment such as bending. Further, depending on the combination of the diameters of the core 21 and the core 31, the leak W can be extremely increased. In this case, a large amount of leak light W generates an evanescent wave at the interface between the clad 32 and the outside world, and acts on the outside world to sense a change.

[0024] Light that leaks as described above changes depending on the degree of bending of the optical fiber in the sensor unit SP and the environment in which the optical fiber is placed, so that changes that occur as a result of interaction with the outside world are detected. can do. In the present embodiment, the intensity of the leaked light is modulated by the vibration of the external force, and therefore the intensity of the light transmitted to the downstream optical fiber 20b is also modulated.

In this way, by converting the optical signal into an electric signal by the light receiving unit 15, an electric signal corresponding to the vibration of the medium can be obtained.

[0025] Other configurations may be adopted as the sensor unit SP.

FIGS. 4A and 4B are cross-sectional views in the longitudinal direction of the optical fiber (20a, 20b) in the vicinity of the sensor part SP for illustrating an example of the configuration of the sensor part SP.

In FIG. 4A, the diameter bl of the core 31 of the hetero-core part 3 constituting the sensor part SP is larger than the diameter aU of the core 21 of the optical fiber (20a, 20b).

As shown in FIG. 4B, in place of the hetero-core portion, the sensor portion SP is a light transmitting member having a refractive index equivalent to the refractive index of the core 21 or the refractive index of the cladding 22 of the optical fiber (20a, 20b). Can be made to be joined to the middle part of the optical fiber (20a, 20b).

[0026] In the drawing, a plurality of force members that connect one sensor part SP to the middle part of the optical fiber (20a, 20b) may be connected in series.

In addition, a plurality of optical fibers each provided with a sensor unit are provided on the same vibration sheet. You may choose.

As described above, the microphone element according to the present embodiment includes a vibration sheet that captures vibration of a medium, a vibration sheet that is provided on the vibration sheet, and a core and a cladding that is provided on the outer periphery of the core. An optical fiber having a sensor unit that enables interaction with a part of the outside of the optical fiber, a light source that emits light to the incident end of the optical fiber, and an optical fiber exiting from the output end of the optical fiber And a light receiving unit that detects light.

The microphone element of the present embodiment is a microphone that uses an optical fiber sensor, has a simple structure, and can be manufactured at low cost.

[0029] 2 fruit

The microphone element according to this embodiment is substantially the same as that of the first embodiment, but the arrangement of the optical fibers is different.

FIG. 5 is a schematic configuration diagram of a main part of the microphone element according to the present embodiment.

The optical fiber (20a, 20b) including the sensor part SP in the middle is provided on the vibration sheet 13 in a straight line.

[0031] Similar to the first embodiment, the microphone element of the present embodiment is a microphone that uses an optical fiber sensor, is a simple structure, and can be manufactured at low cost. Therefore, it is easy to use remotely, and electromagnetic induction does not occur in the sensor part, so it can be used in places where EMI interference is a concern. In addition, since the vibration sheet and optical fiber parts that detect vibration do not use electricity, they can be used in water or in places where there is a risk of fire.

[0032] The microphone element of the above-described embodiment is arranged in a liquid consisting of only a gas such as air as a medium on which the microphone element is placed, and captures vibrations transmitted in the liquid and converts them into electrical signals. It is also possible.

In addition, any form of vibration that can be transmitted to the optical fiber can be converted into an electrical signal. Therefore, the vibration sheet or the optical fiber is brought into contact with a vibrating object such as an automobile engine to generate the electrical signal. It can also be used as a vibration sensor to convert to, and it can also be used as an aerospace related vibration sensor. It can also be used as a security sensor for crime prevention by detecting vibrations generated by intruders in the monitoring area as electrical signals.

[0033] The present invention is not limited to the above description!

For example, the vibration sheet has a flat sheet shape, but is not limited thereto, and may have various shapes. As the material of the vibration sheet, various materials such as a resin sheet and paper can be used.

As the light source, a light emitting element other than a semiconductor light emitting element such as a laser diode or a light emitting diode can be used.

As the light receiving section, any element that converts light into an electrical signal can be used in addition to a photodiode.

In addition, various modifications can be made without departing from the scope of the present invention. Industrial applicability

The microphone element of the present invention can be applied to a microphone or a vibration sensor that converts vibration transmitted to a medium such as air or water into an electric signal.

Claims

The scope of the claims

[1] A vibration sheet for capturing the vibration of the medium;

An optical fiber having a sensor unit provided on the vibration sheet, including a core and a cladding provided on an outer periphery of the core, and capable of interacting with a part of the transmitted light; and an incident of the optical fiber A light source that emits light toward the edge;

A light receiving unit that detects the light emitted from the output end of the optical fiber via the sensor unit;

A microphone element having

[2] The sensor unit is a hetero-core unit having a core diameter different from the core diameter of the optical fiber, and is configured to be joined to a middle part of the optical fiber.

The microphone element according to claim 1.

[3] The sensor unit has a configuration in which a light transmitting member having a refractive index equivalent to a refractive index of a core of the optical fiber or a refractive index of a clad is joined to a middle part of the optical fiber. The microphone element as described.

[4] The optical fiber is provided on the vibration sheet so as to bend with the sensor portion as a top portion.

The microphone element according to claim 1.

[5] The optical fiber including the sensor portion is linearly provided on the vibration sheet.

The microphone element according to claim 1.

[6] The optical fiber is bonded to the vibration sheet.

The microphone element according to claim 1.

[7] The optical fiber is embedded in the vibration sheet.

The microphone element according to claim 1.