JPS60123197A - Acoustic signal/electric signal converter - Google Patents

Abstract

PURPOSE:To derive the change of sound pressure applied to a reflecting plate as the form of a current change by receiving the fixed light irradiated from a light emitting element by a photodetecting element via the reflecting plate, and supplying a sound signal to the reflecting plate. CONSTITUTION:A fixed quantity of light is irradiated to a reflecting plate 2 from a light emitting element 1, and a distance (d) is set so that the current value received by a photodetecting element 3 is set at a place near the center of a rectilinear and the sudden rise part of a characteristic curve. The distance (d) varies with addition of a sound signal to the plate 2. Then the current flowing to the element 3 changes. This current change is controlled by the component elements of the plate 2 and a holder 6 for said reflecting plate 2. Then the change of sound voltage is extracted in the form of a rectilinear current change.

Description

[Detailed description of the invention] The present invention relates to an electrical signal exchanger for acoustic signals.

In particular, it is an object of the present invention to provide an electric signal converter that is effective for use in microphones, etc., which can use either conductive or non-conductive materials as a diaphragm.

Both conventional electromagnetic microphones and electrostatic microphones have had difficult problems: the former microphones are affected by magnetic fields, and the latter require direct current bias to be applied to the diaphragm to operate them.

In consideration of this problem, the present invention irradiates a fixed amount of light from two light emitting sources to a light receiver via a reflector.

An acoustic signal (sound pressure) is applied to the reflector.

The change in the distance between the light emitting source and the light receiver due to the fluctuation of the diaphragm is interpreted as a change in the current flowing to the light receiver and converted. The present invention will be explained below based on one drawing.

FIG. 1 is a block diagram illustrating the operating principle of the present invention, where J is a light emitting element of a light source, and 2 is a reflecting plate, which is arranged at a certain distance d from the light emitting element 1.

Reference numeral 3 denotes a light receiving element, which is arranged at a distance d from the reflecting plate 2. 4 is a signal processor that processes the output from the light receiving element as an electrical signal.

When a constant L meter from the light emitting element 1 is irradiated onto the reflector plate 2,
The light reflected by the reflector 2 is received by a light receiver 3. At this time, depending on the mutual distance relationship between one light emitting element 1, the reflecting plate 2, and the light receiving element 3, the value of the current flowing through the light receiving element 3 has a characteristic curve as shown in FIG. Details regarding this will be explained later.

Further, FIG. 2 is a diagram showing a specific configuration example of FIG. 1, and one light emitting element 1 and one light receiving element 3 constitute an optical cable 5 housed in one hanger.

On the other hand, the two reflectors 2 can be vibrated ((held) by the reflector holder 6.

As shown in FIG. 3, the distance d between 1 reflection plate 2 and optical element 5
(Horizontal axis) Corresponding to K, a change in the amount of electricity flowing through the light receiving element 3 (vertical axis) is seen.

This means that in a small range (d+dDdz) of the distance d between the reflector 2 and the optical cable 5 in FIG.
dm) as a branching point, the current decreases by drawing a parallel curve (decrease in current).

Therefore, when a certain amount of light is irradiated from one light emitting element 1 onto the reflecting plate 2, the current value received by the light receiving element 3 is determined.

so that it is near the center of the straight and steep rising part of the characteristic curve in Figure 3 (do position).

Set the distance d in FIG. In this way, when an acoustic signal (sound pressure) is applied to the reflector 2, the distance d between the reflector 2 and the optical cable 5 changes in response to the change in sound pressure, and the current flowing through the light receiving element 3 changes. It operates around the third do point.

In other words, it can be interpreted as a linear change in current according to sound pressure.

In this case, if the components of the reflector 2 and its reflector holder 6 are adjusted 1, the displacement of the reflector 2 due to sound pressure can be adjusted to the 3rd level.
K control can be performed within the range of d1 to d2 in the figure (linear characteristics). About this.

This means that changes in sound pressure can be extracted as linear changes in current, and can be used as a micropon.

As explained above, the present invention allows the mutual arrangement distance relationship between the light emitting element, the light receiving element, and the reflecting plate to be the distance d, and adjusting the constituent elements of one reflecting plate and its holder. Since changes in pressure can be detected as linear changes, it can be used as a microphone. This is a conventional electromagnetic type.

It does not have the drawbacks of electrostatic microphones, has a simple configuration, and has great practical value.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram for detailed explanation of the present invention. FIG. 2 is a diagram showing a specific configuration example of FIG. 1, and FIG. 3 is a current characteristic curve diagram of the present invention. I: Light emitting element, 2: Reflector, 3. Light receiving element. 4. Signal processor, 5: Optical element, 6: Reflector holder. Patent applicant Nagano Japan Radio Co., Ltd.

Claims (1)

[Claims] A certain amount of light emitted from the light emitting element is received by the light receiving element via a reflecting plate, and an acoustic signal (sound pressure) is applied to the reflecting plate, thereby reducing the distance between the light emitting element and the light receiving element due to the vibration of the reflecting plate. 1. An electrical signal converter for acoustic signals, characterized in that the change is detected as a change in the current flowing through the light receiving terminal.