JPS61100715A - Optical microphone - Google Patents

Abstract

PURPOSE:To remove a defect such as influence due to external noise, to attain long distance transmission and to reduce a device at its size by forming a reflector on the surface of a diaphragm and irradiating single wavelength light upon the diaphragm to use Doppler effect due to the vibration of the diaphragm. CONSTITUTION:The reflector 8 is fitted to the surface of the diaphragm 2 on the incide of the microphone and single wavelength light projected from a single wavelength light sources 5 is irradiated upon the reflector 8 as incident light 3. The reflected light 4 of the incident light 3 by the reflector 8 is reached to a photodetector 6 and transmitted through an optical fiber 7. If the diaphragm 2 is vibrated in the vertical direction to the surface by voice 1, the reflector 8 is also vibrated similarly. At the reflection by the reflector 8, the incident light 3 obtained from the light source 5 is modulated at its frequency in accordance with the vibration of the reflector 8 on the basis of Doppler effect, detected by a photodetector 6 as reflected light 4 having fine change of frequency and then transmitted through the optical fiber 7.

Description

TECHNICAL FIELD The present invention relates to a microphone, and more particularly to a microphone capable of extracting audio as an optical signal.

Button mouth (Microphones usually have a diaphragm to receive vibrations from the air, and in the case of conventional microphones, for example,
Fll temporary vibrations are converted into electrical signals using a conversion system consisting of a net and a coil.

Furthermore, in order to transmit the electric signal, the microphone 07 ON output signal is amplified and then transmitted using a conductor, or the microphone output signal is converted into a radio wave signal and transmitted through the air.

However, in the case of such conventional microphones, it is inevitable that losses occur when converting the movement of the diaphragm into a 7I signal and when amplifying or converting the microphone output signal into a radio wave signal. Gen 45 undergoes change 4J
゛(The drawbacks such as being able to read L are h-). Further, there are drawbacks such as being easily affected by external noise when transmitting electrical or radio signals containing audio data, limited bandwidth of transmitted data, and limited transmission distance.

1. The present invention solves the above-mentioned disadvantages of the conventional NEC 4, eliminates the disadvantages such as the influence of external noise in the process of converting audio into electrical signals, radio signals, etc., and enables long-distance transmission. The purpose of the present invention is to provide a microphone that is capable of transmitting data and can be miniaturized.

The microphone according to the present invention is characterized in that a reflecting mirror is provided on the surface of the diaphragm, the diaphragm is irradiated with a single wavelength light, and the Doppler effect due to the vibration of the diaphragm is used. It is configured to use reflected light that is frequency-modulated around the frequency of be.

1-1-9 Below, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing an embodiment of a microphone according to the present invention. In the figure, a reflecting mirror 8 is provided on the surface of the diaphragm 2 on the side inside the microphone, and this reflecting mirror 8 is irradiated with a single wavelength light beam from a single wavelength light source 5 as incident light 3.

The reflected light 4 of the incident light 3 by the reflecting mirror 8 reaches the light receiver 6 and is transmitted through the optical fiber 7. The initial procedure for detecting air vibrations, that is, sound 1, with the microphone having such a configuration is as follows. 6 voices 1
When the diaphragm 2 vibrates in a direction perpendicular to its surface, the reflecting mirror 8 also vibrates in the same way. Therefore, when the desired light 3 from the single wavelength light source 5 is reflected by the reflecting mirror 8, it undergoes frequency modulation according to the vibration of the anti-g)l mirror 8 due to the Doppler effect, and the reflected light has a minute change in frequency. 4 as receiver 6
The light is received by the optical fiber 7 and further transmitted through the optical fiber 7.

FIG. 2 is a schematic diagram showing a second embodiment of the microphone according to the present invention, in which a single wavelength light source is provided outside the microphone and introduced into the microphone through an optical fiber 7. is a feature.

The rest of the configuration is the same as that of the first embodiment shown in FIG. 1, and the explanation will be omitted, but the configuration is such that the reflected light 4 is transmitted to the outside using the same optical fiber 7.

Note that in FIGS. 1 and 2, arrow 9 indicates the direction of vibration of the diaphragm.

Next, the principle by which the frequency of the incident light 3 is modulated by the vibration of the diaphragm 2 will be explained in detail with reference to FIGS. 3 and 4. In FIG. 3, the diaphragm 2 moves in the direction shown by the arrow 9' when the sound pressure changes from a high sound pressure state 1'' (peak) to a low sound pressure state 1 (a trough). When the incident light 3 has a wavelength λi as shown in the waveform 10, the frequency is modulated in a lower direction when reflected by the reflection !18, and the reflected light 4 has a wavelength 11 as shown in the figure.
It has a wavelength λ2 that is longer than the wavelength λ1 of the incident light 3. However, in this figure, the change in wavelength is illustrated in an enlarged manner for the sake of explanation. Next, as shown in Figure 4,
When the pressure of the sound 1 changes from a low state, that is, a sound pressure valley, to a high state, that is, a sound pressure peak, the diaphragm 2 moves in the direction shown by the arrow 9''.This causes the incident light 3 to be reflected. When reflected by mirror 8, the frequency is modulated toward higher frequencies,
The reflected light 4 has the wavelength λ1 of the incident light 3 as shown by the waveform 12.
It has a shorter wavelength λ3. Conversion into an optically modulated signal that has undergone frequency modulation according to the frequency of the audio 1 is performed as described above.

Effects of the Invention As explained above, the microphone according to the present invention is configured such that a reflecting mirror is provided on the surface of the diaphragm and a single wavelength light is irradiated onto the anti-9A mirror.
It is configured to convert the vibration of the reflecting mirror into a frequency change of the reflected light by the Doppler effect1, and is further characterized in that the reflected light is directly transmitted using an optical fiber. Therefore, it has the excellent advantage that it is possible to prevent the loss of kj in the process of converting the audio signal, and to roughly prevent the intrusion of external noise during signal transmission. Therefore, the transmission bandwidth of the audio signal converted into an optical signal can be made very wide, and long-distance transmission becomes possible. Furthermore, since the single wavelength light source can be placed outside the microphone, there are advantages such as a simpler structure and miniaturization.

Furthermore, in the above explanation, the part that further converts the reflected light that has passed through the optical fiber 7 into an electrical signal etc. is not shown.
Needless to say, this part can be constructed using a normal photoelectric conversion device.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing one embodiment of a microphone according to the present invention, in which a single wavelength light source is placed inside the microphone, and FIG. 2 is a schematic diagram showing another embodiment of the present invention. This is a schematic diagram of an example in which a single wavelength light source is placed outside the microphone, and FIGS. 3 and 4 are diagrams showing the process of converting audio into an optical signal. Explanation of symbols of main parts 2... Vibration plate 3... Incident light 4
...Reflected light 5...Single wavelength light source 6...Receiver 7...Optical fiber 8...Reflector

Claims (2)

[Claims] (1) A diaphragm arranged to vibrate in response to sound, a reflecting mirror provided on the diaphragm, a single-wavelength light source that irradiates single-wavelength light to the reflecting mirror, and the reflecting mirror. An optical microphone comprising an optical fiber that transmits the light reflected by the single wavelength light from the mirror. (2) The light according to claim 1, wherein the single wavelength light from the single wavelength light source is transmitted through the optical fiber and irradiated onto the reflecting mirror. microphone.