JPS63260395A - Microphone - Google Patents

Abstract

PURPOSE:To simplify circuit constitution by replacing a displacement in forward/ backward direction of a diaphragm vibrated by a sound wave into a change in the distance from the diaphragm to a photodetection section, detecting it as a change in the reflected light detecting area of the photodetection section and outputting the vibration of the diaphragm due to an input sound wave as a digital electric signal. CONSTITUTION:When the diaphragm 11 is vibrated and displaced in forward/backward direction by a sound wave S, the diaphragm 11 and a light source 12 interlocking therewith are changed in forward/backward direction at the same time. Thus, the radiated circle 11c is always constant and unchanged. Since the distance between the diaphragm 11 and the photodetection section 13 is changed by the displacement of the diaphragm 11, a reflected light receiving circle 13a of the photodetection section 13 is changed as shown in a concentric circle shown in broken lines at the inside and outside of the reflected light photodetection circuit 13a shown in solid lines the diaphragm 11 is at standstill. That is, the circle is larger as the diaphragm 11 is parted from the photodetection section 13 and smaller conversely when the diaphragm 11 approaches. The photodetection section 13 comprising plural photodetection elements such as CCD counts the photodetection number of the photodetector to convert the vibration of the diaphragm 11 into a digital electric signal.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a microphone used in audio equipment, and more specifically, to a microphone that directly converts sound waves of music or the like into digital electrical signals.

It concerns Crohon.

(Prior Art) A conventional method for inputting sound waves such as music as digital electrical signals to a digital audio device will be explained with reference to FIG.

FIG. 3 is a block diagram of a signal processing circuit that converts an analog electrical signal of a microphone into a digital electrical signal.

In the figure, a sound wave S is converted into a minute analog electrical signal by a microphone 1 into which it is input, and is amplified to a level that can be transmitted by a microphone amplifier 2, and then a transmission line 3.
The signal is then input to a digital audio device 4 indicated by a broken line frame in the figure.

The analog electrical signal input to the digital audio device 4 is amplified by an amplifier 5 to a level that can be sampled, and then a low-pass filter 6 removes unnecessary harmonic components to prevent aliasing distortion due to the alias effect during sampling. is removed. The analog electrical signal from which unnecessary harmonic components have been removed is sent to the sample-and-hold amplifier 8 by the sample-and-hold control signal C output from the clock generator 7.
After being sampled and held by the analog-to-digital converter 9, it is output as a digital electrical signal E in response to a conversion start signal output from the clock generator 7.

(Problems to be Solved by the Invention) However, the above configuration has the problem that the analog-to-digital converter 9 is expensive and it is difficult to obtain one with stable performance. moreover.

Since the output of the microphone passes through the transmission line 3 in the form of an analog signal, there are problems in that noise is likely to be mixed in, and distortion is likely to occur due to the amplification.

The present invention solves the above problems, and provides a microphone that can convert sound waves such as music into digital electrical signals and directly supply them to digital audio equipment without requiring a complicated signal processing circuit. It is something.

(Means for Solving the Problems) In order to solve the above problems, the present invention includes a light source having an irradiation angle, a part that absorbs or transmits light in the center, and a part that reflects light around it. a diaphragm arranged in a plane orthogonal to the optical axis of the light source and interlocked with the light source, and a plurality of light receiving elements that receive reflected light from the diaphragm and convert it into an electrical signal. A microphone is constructed from the parts, and the longitudinal displacement of the diaphragm vibrated by sound waves is replaced by a change in the distance from the diaphragm to the light-receiving part, which is detected as a change in the reflected light receiving area of the light-receiving part. This outputs the vibration of the diaphragm as a digital electrical signal.

(Function) According to the above configuration, the light source with an illumination angle of 2α and the diaphragm are linked, so even if the diaphragm is displaced by ±ΔX due to sound waves, the distance from the light source to the diaphragm does not change. First, the diameter of the irradiation circle on the diaphragm does not change, but the distance between the changing diaphragm and the fixed light receiving section is the displacement of the diaphragm ±ΔX.
When the maximum incident angle of light to the diaphragm and its reflection angle are both equal to α, the diameter of the reflected light receiving circle of the light receiving section changes by ±2Δx tanα. That is, if the diaphragm moves away from the light receiving section by ΔX, the diameter of the receiving circle for one reflected light becomes larger by 2Δx tanα, and conversely, if it moves closer by ΔX, it becomes smaller by 2Δx tanα.

This change in the area of the reflected light receiving circle is detected by a plurality of light receiving elements, and by counting the number of elements that have received the light, it can be converted into a digital electrical signal.

(Example) An example according to the present invention will be described with reference to FIGS. 1 and 2. Figures 1 (a), (b) and (Q) are, respectively,
FIG. 1 is a side sectional view of a microphone according to the present invention.

and cut at its AA' plane and BB' plane, respectively,
FIG. 2 is a rear sectional view and a front sectional view seen from the direction of the arrow.

In FIG. 1(a), the microphone according to the present invention has two
A circular part 11a is provided inside the cylindrical case 10 so as to be perpendicular to its center line, and as shown in FIG. A diaphragm 11 consisting of a portion 11b and a diaphragm 1
1, a light source 12 whose optical axis coincides with the above-mentioned center line, and has an irradiation angle of 2α, and a light receiving section formed by a plurality of light receiving elements such as a COD, which is arranged behind this light source 12. It consists of 13.

Note that the absorbing or transmitting portion 1 formed at the center of the diaphragm 11
1a is set so that reflected light does not return to the light source 12.

The operation of the microphone configured in this way will be explained. The diaphragm 11 vibrates due to the sound wave S.

When it is displaced back and forth, the diaphragm 11 and the light source 12 linked thereto simultaneously change back and forth, as shown by the broken line in FIG. 1(a). Therefore, the irradiation circle 11c shown by a solid line in FIG. 1(b) is always constant and does not change. However, the diaphragm 11
Since the distance between the diaphragm 11 and the diaphragm 13 changes by the amount of displacement of the diaphragm 11, the reflected light receiving area 13a of the diaphragm 13 is reflected by the solid line when the diaphragm 11 is at rest in FIG. 1(c). The inside and outside of the light receiving area 13a change like concentric circles shown by broken lines. That is, when the diaphragm 11 moves away from the light receiving section 13,
The closer you get to it, the larger it becomes, and the closer you get to it, the smaller it becomes. The light receiving section 13, which is composed of a plurality of light receiving elements such as a CCD, can convert the vibration of the diaphragm 11 into a digital electrical signal by counting the number of light received by the light receiving elements.

FIG. 2 is a block diagram for inputting music signals from the microphone of the present invention to digital audio equipment.

In the figure, a sound wave S is converted into a digital electrical signal by a microphone 14 according to the present invention, which is inputted to the sound wave S, and is inputted via a transmission line 15 to a digital audio device 16 shown in a broken line frame in the figure. In the digital audio device 16, the latch clock signal A based on the sampling frequency output by the clock generator 17 causes
The latch circuit 18 temporarily holds the input digital electric signal at regular intervals, and then outputs it as a digital music signal B. This digital music signal B is equivalent to the digital music signal E shown in FIG.

Note that if the diaphragm 11 of the microphone has the characteristics of a low-pass filter with a cutoff frequency that is 1/2 or less of the sampling frequency when the microphone output signal is processed by the digital audio equipment, sampling will be easier. No aliasing distortion occurs due to the accompanying Elias effect.

(Effects of the Invention) As explained above, according to the present invention, digital electrical signals required for digital audio equipment can be processed using a much simpler circuit configuration than the conventional analog-to-digital converter processing system. can be obtained. Furthermore, since the output of the microphone is a digital electrical signal, there is no noise mixed in during transmission to other equipment, and since no amplifier is required, no distortion occurs other than that generated by the microphone itself.

[Brief explanation of the drawing]

1(a), (b) and (Q) are a side sectional view, a rear sectional view taken along the AA' plane, a front sectional view taken along the BB' plane, and a second sectional view of the microphone according to the present invention, respectively.
FIG. 3 is a block diagram illustrating a method for providing music signals from a microphone according to the present invention and a conventional microphone, respectively, to digital audio equipment. 1.14...Microphone, 2...Microphone amplifier, 3.15...Transmission line, 4.16...Digital audio equipment, 5...Amplifier, 6...Low pass filter, 7,17 ...clock generator,
8... Sample and hold amplifier, 9... Analog-to-digital converter, 10... Housing, 11...
・Vibration plate, lla...absorption or transmission part, Ilb
...Reflection part, llc...Irradiation circle, 12...
Light source, 13... Light receiving section. 13a...Reflected light receiving circle, 18...Latch circuit. Patent applicant Matsushita Electric Industrial Co., Ltd. (b) (c) 10, -Kake'a 11-, -JMQIL
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Anti-arrogance number 11c-Jkl, Karako Fi 12
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:117 Figure 2 14. - Miglophone 15 ,,,Iin' Meshie Valley 16, -De l'';Tal 4-DeIo Answer 17 - Kuro Tsuku Sensei Group 18, -U,,Su[]Route 3rd Lj Microphone / 2-, microphone trend 3-IL standard 4-, digital audio system 5-0 amplifier 6-lower input filter 7-Kuro Tsuku teacher's base

Claims (1)

[Claims] It consists of a light source having an irradiation angle, a part orthogonal to the optical axis that reflects the irradiated light, and a part that absorbs or transmits the irradiated light, and a diaphragm that works in conjunction with the light source, and a diaphragm that receives the reflected light from the diaphragm. and a light receiving section consisting of a plurality of light receiving elements that convert the vibration into electrical signals. A microphone characterized in that a change in a reflected light receiving area is detected by a change in the number of light received by a plurality of light receiving elements, and the detected change is output as a digital electrical signal.