JPS61183616A - Voice information fetching device - Google Patents

Abstract

PURPOSE:To omit a converting process to an electric signal, to apply it to optical transmission as it is,to minimize an influence of an external noise,and also to take out fine vibration by taking out the vibrating information of a diaphragm as interference light. CONSTITUTION:On the first layer 11 having prescribed thickness, the second layer 12 whose refractive index is different from that of the first layer 11 is provided closely. On the surface of the opposite side of a boundary surface 16 to the first layer 11 of the second layer 12, a diaphragm 13 is provided, so that the thickness of the second layer 12 is varied by vibration of the diaphragm 13. Also, a light reflecting plate 14 is provided on the inside of the diaphragm 13. In this state, reference wavelength light 3 is emitted from a light emitting device 1, the first reflected light 9 which has been reflected by the boundary surface 16, and the second reflected lights 10, 10A which have been reflected by the light reflecting plate 14 and have been emitted through the second layer 12 and the first layer 11 are photodetected by a photodetector 2, and vibrating information of the diaphragm 13 is taken out from the interference light of both beams of the reflected light.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an audio information retrieval device such as a microphone for retrieving audio information.

[Conventional technology]

Conventional microphones operate in a magnetic field created by a magnet.
Radio waves are induced by the vibration of the diaphragm and the movement of the coil, and the vibration information is converted into electrical information and transmitted via conductive wires.

[Problem that the invention seeks to solve]

The above-mentioned conventional microphones (1) directly transmit the current due to the minute electromotive force induced by vibrations through conductive wires, so they are greatly affected by external noise; In order to reduce the electromotive force, it is necessary to generate an electromotive force above a certain value.
There is a limit to the amplitude that can be extracted, so it is necessary to provide the microphone with directivity. There were drawbacks such as information loss.

[Means for solving problems]

The audio information retrieval device of the present invention includes a first layer having a constant thickness, a first layer that is in close contact with the first layer, a refractive index different from the first layer, and a side opposite to the interface with the first layer. A second layer is provided with a diaphragm on its surface and whose thickness changes due to the vibration of the diaphragm, and a single wavelength light is emitted, and this single wavelength light is incident on the first layer.
, a light emitting device arranged to pass through the second layer and be reflected by the diaphragm;
- The first reflected light emitted from the second layer and reflected by the diaphragm. The light receiving device receives the second reflected light that has passed through the first layer and is emitted, and extracts vibration information of the diaphragm from interference light of both reflected lights.

The operation of the audio information retrieval device of the present invention will be explained as follows. The diaphragm vibrates t in response to audio information, and the thickness of the second layer changes in response to the vibration of the diaphragm. Therefore, 1 emitter → first layer → second layer reflector → second layer →
The optical path length of the second reflected light of the first layer receiver changes.

On the other hand, since the thickness of the first layer is constant, the light emitter → the first layer
The optical path length of the first reflected light of the layer → the interface between the first layer and the second layer → the first layer → the amount of received light is constant. Therefore, vibration information of the diaphragm, that is, audio information can be extracted from the interference light of the first reflected light and the second reflected light.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings.

1st. FIG. 2 is a block diagram of an embodiment of the voice information retrieving device according to the present invention, showing a voice non-detection state and a voice detection state, respectively.

First layer 11. The second layer 12 is a layered layer of materials with different refractive indexes, and the thickness of the first layer 11 is constant.
A diaphragm 13 is provided on the surface of the second layer 12 opposite to the interface 12 with the first layer 11, and a light reflecting plate 14 is provided inside the diaphragm 13.

The light emitter 1 emits a single wavelength light (reference wavelength light) 3, and this reference wavelength 3 passes through the first layer 11 and the second layer 12 and is reflected at the center of the light reflecting plate 14. It is arranged outside the first layer 11. The light receiver 2 receives first reflected light (sampling reference light) 9 reflected at the interface 1B between the first layer 11 and the second layer 12 and emitted from the first layer, and a light reflecting plate 14.
10. Second reflected light (sampling light) that is reflected by the second layer 12 and the first layer 11 and exits. IOA
is received, and vibration information of the diaphragm 13 is extracted from the interference light of both reflected lights.

Next, the operation of this embodiment will be explained.

The reference wavelength light 3 generated by the light emitter 1 is refracted at the boundary surface 15 of the first layer 11, and travels within the first layer 11 as the first layer refracted reference light 4. The first layer refracted reference light 4 is the first layer refracted reference light 4
1 and the second layer 12, travels through the first layer 11 as the first layer reflected reference light 6, is refracted again at the interface 15 of the first layer 11, and becomes the sampling reference light 9.
becomes. On the other hand, the first layer refracted reference light 4 passes through the interface 16 between the first layer 11 and the second layer 12, becomes the second layer refracted reference light 5, and travels through the second layer 12. When the diaphragm 13 is not vibrating (FIG. 1), the second layer refracted reference light 5 is
It is reflected by the light reflecting plate 14, becomes the second layer reflected light 7, passes through the second layer 12, is refracted at the interface 1B between the first layer 11 and the second layer 12, and passes through the second layer 11. ', and is finally refracted at the boundary surface 15 of the first layer 11, and the sampling light 1
It reaches the light receiver 2 as 0. At this time, the sampling reference light 9 and the sampling light IO have different phases and therefore interfere with each other.

Next, when the diaphragm 13 receives an audio signal, the thickness of the second layer 12 changes due to the vibration. Due to the change in the thickness of the second layer 12, the second layer refracted reference light 5 is transferred to the diaphragm 13.
Since the second layer reflected light 7A is reflected with a different thickness from that when the diaphragm 13 is in a non-vibration state (FIG. 1), the second layer reflected light 7A is the same as the second layer reflected light 7A when the diaphragm 13 is in a non-vibration state. The phase is different from that.

Therefore, since the sampling light 10A when the diaphragm 13 is in a vibrating state and the sampling light 10 when the diaphragm 13 is in a non-vibrating state have different phases, interference light with the sampling reference light 9 may also occur. Comes differently.

In this way, the sampling reference light 9 and the sampling light 1
0. Vibration information of the diaphragm 13, that is, audio information is obtained from the interference light of the IOA.

〔Effect of the invention〕

As explained above, by extracting the vibration information of the diaphragm as interference light, the present invention can omit the process of converting it into an electrical signal, and can be directly applied to optical transmission.As a result, the influence of external noise can be minimized. In addition, by changing the wavelength of the reference incident light, it is possible to extract minute vibrations, and since the output signal is light, there are effects such as reducing loss in the transmission process.

[Brief explanation of the drawing]

FIGS. 1 and 2 are block diagrams of an embodiment of an optical interferometric conversion device according to the present invention, showing a state in which no sound is detected and a state in which a sound is detected, respectively. 1-m-emitter, 2-m-light receiver, 3-m-reference wavelength light. 4--1 first layer refraction reference light. 5-11 second layer refraction reference light, 61--first layer reflective reference light, 7.7'--1 second layer reflected light, 8.8'-11 first layer catadioptric light, 9 -m-sampling reference light, 10, 10'-11 sampling light, 11-11 first layer, 12-11 second layer, 13
-m-diaphragm, 14--single light reflection plate. 15-11 The interface between the first layer 11, 1G-11 The interface between the first layer 11 and the second layer 12. Patent applicant: NEC Corporation 151, agent
Patent attorney Susumu Uchihara.・、Mire

Claims (1)

[Scope of Claims] A first layer having a constant thickness, which is in close contact with the first layer and has a different refractive index from the first layer,
a second layer that is provided with a diaphragm on a surface opposite to the interface with the first layer and whose thickness changes due to the vibration of the diaphragm; and a second layer that emits light of a single wavelength; a light emitter arranged so that light enters the first layer, passes through the first and second layers, and is reflected by the diaphragm; and an interface between the first and second layers. The first reflected light is reflected by the first layer and emitted from the first layer, and the second reflected light is reflected by the diaphragm and the second reflected light is emitted from the first layer.
An audio information extraction device comprising: a light receiver that receives a second reflected light emitted after passing through a first layer, and extracts vibration information of the diaphragm from interference light of both reflected lights.