JPH02190099A - Optical microphone - Google Patents

Abstract

PURPOSE:To expand a frequency band by incorporating a mirror onto a rear side of a diaphragm receiving sound, providing a light emitting element and a light receiving element to detect the vibration of the diaphragm optically and a transducer transducing a change in the light received by the light receiving element into an electric signal. CONSTITUTION:The optical microphone consists of a diaphragm 1, a mirror 2, a laser diode 3, a photodetector section 4 and a photo transistor(TR) 6. A sound made incident externally is propagated to the diaphragm 1, the mirror 2 is vibrated simultaneously and a laser beam generated from the laser diode 3 is subjected to vibration modulation by the vibration when being reflected in the mirror 2. The laser beam is transduced into a current by the photo TR 6 to transduce the sound into an electric signal thereby attaining the function of the microphone. Since the sound is transduced into an electric signal with no contact with the diaphragm 1, high sensitivity is attained over a wide band.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical microphone, and particularly to an optical microphone that converts sound into an electrical signal and is compatible with high fidelity and high bandwidth.

[Conventional technology]

Conventional microphones convert sound into electrical signals by (1) those that convert vibrations using a coil in a magnetic field (dynamic type), (2) those that convert vibrations by changing the capacitance of a capacitor (condenser type), etc. There is.

[Problem to be solved by the invention]

However, the conventional microphone described above has a drawback in that it is difficult to widen the frequency band because the part receiving vibration and the part receiving electric signals are integrated.

[Means to solve the problem]

The optical microphone of the present invention has a mirror integrated on the back side of a diaphragm that receives sound, and has a light-emitting element and a light-receiving element to optically detect the vibration of the diaphragm. It is constructed with a converter that converts the change into an electrical signal.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

The optical microphone shown in FIG. 1 includes a diaphragm 1, a mirror 2, a laser diode 3, a light receiving section 4, and a phototransistor 6.

FIG. 2 is a longitudinal sectional view showing another embodiment of the present invention.

The optical microphone shown in FIG. 2 has almost the same configuration as that in FIG. 1, but uses an optical fiber 5 as a transmission path for the received light.

Next, the operation of the optical microphone shown in FIGS. 1 and 2 will be explained.

Sound incident from the outside is transmitted to the diaphragm 1 and causes the mirror 2 to vibrate at the same time. These use thin and strong materials.

Next, the laser beam generated from the laser diode 3 passes through the mirror 2.
[Effects of the Invention] The optical microphone of the present invention converts sound into an electrical signal without contacting the diaphragm, so it can be made highly sensitive over a wide band, and has a coil section. This has the effect of reducing changes in output impedance due to frequency.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing another embodiment of the invention.

Claims (1)

[Claims] A diaphragm that receives sound, a mirror that responds to the vibrations received by the diaphragm, a laser diode that generates lens light, and a diode that converts changes in the reflected light from the mirror irradiated with the laser light into electrical signals. An optical microphone comprising: