KR20080031477A - Microphone element - Google Patents

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

Microphone element {MICROPHONE ELEMENT}

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

Optical fibers have been widely used as a means of transmitting signals, and sensors using optical fibers have been developed for various purposes in various ways.

Especially, the microphone using optical fiber is described in the following patent documents (Unexamined-Japanese-Patent No. 2002-232999, Unexamined-Japanese-Patent No. 2000-65633, and Unexamined-Japanese-Patent No. 11-252696).

Japanese Patent Laid-Open No. 2002-232999 discloses an optical sensor and an acoustic detection method of an optical fiber loop interferometer type. The vibration transmitted to the diaphragm is converted into an electrical signal from the change in the intensity of the interference light obtained by propagating the light in the clockwise and counterclockwise directions to the loop-shaped optical fiber passed through the vibrating plate vibrating with the acoustic signal.

Japanese Patent Laid-Open No. 2000-65633 discloses an optical waveguide vibration sensor system for remote detection. The electrical signal generated by the geophone converts the mechanical vibration transmitted to the geophone from the interference pattern obtained by modulating the phase of the optical signal guided into the optical waveguide into an electrical signal.

Japanese Patent Laid-Open No. 11-252696 describes the structure of a light modulated microphone. The light receiving element and the light receiving element which are housed in a state in which the light emitting element and the light receiving element are separated by a partition wall, and an optical waveguide for transmitting the light from the light receiving element are formed separately, and are integrally formed with the thin film diaphragm, When the light is reflected by the thin film diaphragm and received by the light receiving unit, and the thin film diaphragm vibrates by sound waves, the intensity of light received by the light receiving unit is modulated and converted into an electrical signal.

However, the acoustic sensor described in Japanese Patent Laid-Open No. 2002-232999 has a problem that the entire apparatus is complicated, and the apparatus for detecting the interference light is expensive, so that the acoustic sensor is also expensive.

Moreover, the optical waveguide vibration sensor system described in Unexamined-Japanese-Patent No. 2000-65633 has the problem that the whole apparatus is complicated and expensive as an optical waveguide vibration sensor system.

In addition, the microphone described in Japanese Patent Laid-Open No. 11-252696 has a problem that precise design is required and manufacturing cost is high.

Moreover, about the optical fiber sensor, the structure which uses a so-called hetero core part as a sensor is described in the international publication 97/48994 pamphlet and Unexamined-Japanese-Patent No. 2003-214906.

However, International Publication No. 97/48994 and Japanese Patent Laid-Open No. 2003-214906 do not describe the use of a heterocore optical fiber sensor as a microphone.

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

The micro device of the present invention comprises a vibration sheet for capturing vibration of a medium, and a sensor provided on the vibration sheet and having a core and a cladding provided on an outer circumference of the core, so as to enable interaction with a part of an external part of the transmitted light. And an optical fiber having a portion, a light source for emitting light to the incidence end of the optical fiber, and a light receiving portion for detecting the light emitted from the output end of the optical fiber through the sensor portion.

In the micro device of the present invention, an optical fiber is provided on a vibration sheet for capturing vibration of a medium. The optical fiber has a core and a cladding provided on the outer periphery of the core, and has a sensor section that enables interaction with an external system of a part of the transmitted light.

Further, a light source for emitting light to the incident end of the optical fiber, and a light receiving unit for detecting the light emitted from the output end of the optical fiber through the sensor unit.

The microphone element of the present invention is preferably a hetero core part having a core diameter different from the core diameter of the optical fiber, and is configured to be joined to the intermediate part of the optical fiber.

Alternatively, the sensor unit is configured such that a light transmitting member having a refractive index equal to the refractive index of the core of the optical fiber or the refractive index of the clad is joined to the intermediate part of the optical fiber.

The microphone element of the present invention is preferably provided in the vibration sheet such that the optical fiber is bent to the sensor portion.

Or preferably, the optical fiber comprising a portion of the sensor portion is installed in the vibrating sheet in a straight line.

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

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

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

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram of the microphone element which concerns on Example 1 of this invention.

2A and 2B are graphs showing the intensity of the incident light and the 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, and Fig. 3B is a sectional view in the longitudinal direction in the vicinity of the sensor part, for illustrating an example of the configuration of the sensor part.

4A and 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.

5 is a schematic configuration diagram of a main part of a microphone element according to Embodiment 2 of the present invention.

(Explanation of symbols for the main parts of the drawing)

3 hetero core part

4 interface

13 vibration sheet

14 light source

15 light receiver

16 amp

17 speakers

18 computers

20a, 20b fiber optic

21, 31 cores

22, 32 Clad

30 light transmission member

SP sensor

W leek light

EMBODIMENT OF THE INVENTION Below, implementation of the microphone element of this invention is demonstrated with reference to drawings.

Example 1

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

For example, optical fibers 20a and 20b are attached to or mounted on the vibration sheet 13 for capturing the vibration of the medium. The vibrating sheet 13 is, for example, a material capable of capturing the vibration transmitted to the medium on which the resin sheet 13, such as air or water, is placed, such as a resin sheet or paper, and transmitting the vibration to the optical fibers 20a and 20b. do.

The optical fibers 20a and 20b have a core and a clad installed on the outer periphery of the core, and the optical fibers 20a and the optical fibers 20b include an outer space of a part of the light transmitted in the optical fibers 20a and 20b. It is connected by the sensor part SP which enables the interaction of the. In this embodiment, for example, the optical fibers 20a and 20b are provided so as to bend the sensor portion SP as the top portion.

Further, light is emitted from the light-emitting source 14 such as a laser diode or a light emitting diode that emits light to the incidence ends of the optical fibers 20a and 20b, and the light is emitted from the light-emitting ends of the optical fibers 20a and 20b through the sensor unit SP. The light-receiving part 15, such as a photodiode, which detects the light to be provided is provided.

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 fibers 20a and 20b, the vibration is transmitted from the vibration sheet 13 to the optical fibers 20a and 20b. Delivered.

The sensor light from the light source 14 is transmitted among the optical fibers 20a and 20b and is received by the light receiving unit 15.

At this time, in the sensor part SP provided in the intermediate portion of the optical fibers 20a and 20b, the degree of interaction with the external field changes in response to the transmitted vibration, and the intensity of the transmitted light changes, so that the light receiving portion 15 In the electric signal obtained by receiving the output light of the optical fibers 20a and 20b, the intensity is modulated in response to the vibration of the medium. Thus, the vibration is converted into an electric signal and functions as a microphone.

The output of the light receiving unit 15 can be amplified by the amplifier 16 and output as audio from the speaker 17.

Alternatively, the computer 18 or the spectrum analyzer can be accepted as audio data, and desired data processing such as vibration frequency analysis can be performed.

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

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

The optical fiber and sensor part which comprise the said microphone element are demonstrated.

3A is a perspective view in the vicinity of the sensor unit SP of the optical fibers 20a and 20b for illustrating an example of the configuration of the sensor unit SP, and FIG. 3B is a longitudinal direction in the vicinity of the sensor unit SP. It is a cross section.

For example, the optical fibers 20a and 20b constituting the microphone element are single-mode fibers having a core diameter of 9 µm, for example, and the optical fibers 20a and 20b are optical fibers 20a and 20b. It is connected by the sensor part SP which enables interaction with the outer space of a part of the light which transmits heavy.

The optical fibers 20a and 20b have a core 21 and a clad 22 provided at an outer circumferential portion thereof. Light from the light source 14 is incident on the core 21 from the light incident end side, and is emitted from the core 21 on the light exit end side to the light receiving unit via the sensor unit SP.

The sensor portion SP shown in FIGS. 3A and 3B is a hetero core portion 3 having a core diameter different from the core diameters of the optical fibers 20a and 20b, and includes a core 31 and a clad provided in the outer peripheral portion thereof. 32).

The diameter b1 of the core 31 in the hetero core portion 3 is smaller than the diameter al of the core 21 of the optical fibers 20a and 20b. For example, al = 9 μm, b1 = 5 [Mu] m. In addition, the length c1 of the hetero core part 3 is several mm-several cm, for example, about 1 mm.

The hetero core portions 3 constituting the optical fibers 20a and 20b and the sensor portion SP are substantially coaxial, for example, to a discharge which is generalized so that the cores are joined at the interface 4 orthogonal to the longitudinal direction. It joins by fusion | melting, etc. by this.

As shown to FIG. 3A and FIG. 3B, the diameter b1 of the core 31 in the hetero core part 3 in the structure by which the sensor part SP is joined to the intermediate part of optical fiber 20a, 20b. ) And the diameter a1 of the core 21 of the optical fibers 20a and 20b are different at the interface 4, and due to the difference in the core diameters, part of the light is clad 32 of the hetero core portion 3. Leak (W). When the diameter of the core 21 and the core 31 is combined to reduce the leak W, most of the light is incident on the optical fiber 21 and transmitted. At this time, the insertion loss of the sensor is small, and the degree of the leak W is sensitively changed in accordance with the change of the external field such as bending. In addition, depending on the combination of the diameters of the core 21 and the core 31, the leak W can be made extremely large. In this case, many leaks of light W generate an evanescent wave at the interface between the clad 32 and the outer field, and act on the outer field to accept the change.

Since the light leaked 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, it is possible to detect a change resulting from the interaction with the external world. In this embodiment, the intensity of the leaking light is modulated by the vibration from the external field, and thus the intensity of the light transmitted to the downstream optical fiber 20b is also modulated.

In this way, the light receiving unit 15 converts the optical signal into an electrical signal, thereby obtaining an electrical signal corresponding to the vibration of the medium.

It is also possible to employ | adopt another structure as the sensor part SP.

4A and 4B are cross-sectional views in the longitudinal direction in the vicinity of the sensor portion SP of the optical fibers 20a and 20b for illustrating an example of the configuration of the sensor portion SP.

In FIG. 4A, the diameter b1 of the core 31 of the hetero core part 3 constituting the sensor part SP is larger than the diameter a1 of the core 21 of the optical fibers 20a and 20b. have.

As shown in FIG. 4B, instead of the hetero core portion, the sensor portion SP has a light transmission member having a bending rate equivalent to the bending rate of the core 21 of the optical fibers 20a and 20b or the cladding 22. It is also possible to have a configuration in which 30 is joined to the intermediate portion of the optical fibers 20a and 20b.

Although one sensor part SP is connected to the intermediate part of the optical fibers 20a and 20b on a figure, you may connect several in series.

In addition, a plurality of optical fibers each having a sensor section may be provided in the same vibration sheet.

As described above, the microphone element according to the present embodiment has a vibration sheet for capturing vibration of a medium, and a vibration sheet provided on the vibration sheet, and having a core and a cladding provided on the outer periphery of the core, so as to interact with an alien part of the transmitted light. And an optical fiber having a sensor unit for enabling the light source, a light source for emitting light to the incidence end of the optical fiber, and a light receiving unit for detecting the light emitted from the output end of the optical fiber through the sensor unit.

The microphone element of this embodiment is a microphone using an optical fiber sensor, which has a simple structure and can be manufactured at low cost.

Example  2

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

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

Optical fibers 20a and 20b including a portion of the sensor portion SP in the middle portion are provided in the vibration sheet 13 in a straight line.

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

Since it is an optical fiber, it is easy to use remotely and since electromagnetic induction does not occur in a sensor part, it can also be used in the place where EMI disturbance is concerned. In addition, since no electricity is used in the vibration sheet for detecting vibration and the part of the optical fiber, it is also possible to use in water or in places where there is a risk of ignition.

The microphone element of the present embodiment described above can be placed in a liquid as well as a gas such as air as a medium on which the microphone element is placed, and can capture vibrations transmitted in the liquid and convert them into electrical signals.

In addition, any type of vibration transmitted to the optical fiber can be converted into an electrical signal, and thus can be used as a vibration sensor for converting vibration into an electrical signal by contacting a vibrating sheet or an optical fiber with a vibrating object such as an engine of a car. It can also be used as vibration sensors related to aerospace.

In addition, by detecting and detecting vibration generated by an intruder or the like in the monitoring area as an electric signal, it can be used as a security sensor for crime prevention.

The present invention is not limited to the above description.

For example, the vibrating sheet is in the form of a flat sheet, but is not limited to this and can be in various shapes. As a material of a vibration sheet, various materials other than a resin sheet, paper, etc. can be used.

As a light source, light emitting elements other than semiconductor light emitting elements, such as a laser diode and a light emitting diode, can be used.

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

In addition, various changes are possible in the range which does not deviate from the summary of this invention.

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

Claims (7)

A vibration sheet for capturing vibration of the medium; An optical fiber installed on the vibrating sheet and having a core and a clad installed on an outer circumference of the core, the optical fiber having a sensor unit configured to enable interaction with a part of the external part of the transmitted light; A light source for emitting light to an incident end of the optical fiber; And A light receiving unit that detects the light emitted from the output end of the optical fiber through the sensor unit; Microphone element having a. The method of claim 1, And the sensor part is a hetero core part having a core diameter different from the core diameter of the optical fiber, the microphone element being configured to be joined to the intermediate part of the optical fiber. The method of claim 1, And the sensor portion is configured such that a light transmitting member having a refractive index equal to the refractive index of the core of the optical fiber or the refractive index of the clad is joined to the intermediate portion of the optical fiber. The method of claim 1, And the optical fiber is installed on the vibrating sheet so as to bend the sensor portion as a top portion. The method of claim 1, And the optical fiber including a portion of the sensor portion is provided in the vibration sheet in a straight line. The method of claim 1, And the optical fiber is bonded to the vibration sheet. The method of claim 1, And the optical fiber is built in the vibrating sheet.

Images