JPS595799A - Vibration-resistant microphone - Google Patents

Abstract

PURPOSE:To amplify normal acoustic vibrations without cancellation, by providing two diaphragms in the same enclosure at an interval, amplifying oscillation conducted to those two diaphragm by a succeeding amplifier in opposite phase relation and allowing outputs originating from the oscillations to cancel each other, and shielding one diaphragm acoustically. CONSTITUTION:Oscillations conducted from a microphone attachment part 3 with many oscillation through the enclosure 11 are impressed to the diaphragms at the same level and in phase. Electric outputs 4, 4' induced at both diaphragms 7 and 8 are equal in level and in phase and the amplifier 9 amplifies only their difference component, so none of enclosure oscillation components appears at the output 10 of the amplifier 9. A sound conduction hole 12 is made in the enclosure 11 in front of the diaphragm 7, which senses even acoustic oscillations, but the diaphragm 8 does not sense those because there is no corresponding sound conduction hole. Therefore, there is only the output 4 of the diaphragm 7 for the acoustic oscillations, so even the difference component is amplified by the amplifier 9, the acoustic oscillations appear at the output 10 without cancellation. Thus, the need for a special vibration-resistant mechanism, etc., is eliminated, so the size is reduced to facilitate its manufacture.

Description

[Detailed description of the invention] This article concerns microphones that are most suitable for use in devices that can be

Conventionally, microphones used in environments with a lot of vibration have been mounted by floating the microphone l using a cushioning material 2 such as sponge rubber, as shown in Fig.
As shown in the figure, there is one that combines a spring and a damper 6 to absorb vibrations at a frequency close to the resonance frequency of the microphone's diaphragm. In both figures, 3 is the mounting part of the microphone that vibrates a lot, 4 is the output of the microphone, and 5
is the support for the microphone.

However, all of these have drawbacks such as large shapes, unstable frequencies of vibrations absorbed by cushioning materials, springs, and dampers, delicate structures, and changes in characteristics due to impact, which can lead to damage. was there. However, this 1s damping material has a drawback in that it is subject to large changes over time and requires periodic replacement or readjustment.

In order to eliminate these drawbacks, the purpose of the present invention is to adopt a method of canceling the transmitted vibrations, rather than the conventional method of preventing vibrations from being transmitted to the diaphragm by transmitting them to the diaphragm. This is what I did. In other words, by providing two diaphragms in isolation within the same housing, the vibration transmitted to the two diaphragms? Since they are almost in phase and at the same level, if they are amplified in opposite phases in the subsequent amplification stage, the outputs of these vibrations will cancel each other out, and by acoustically shielding one of the diaphragms, the normal The acoustic vibrations are amplified without being canceled out, and will be explained in detail below.

FIG. 3 shows a first embodiment of the present invention, where 7 is a diaphragm that is sensitive to both acoustic vibrations and vibrations transmitted through the housing, and 8 is a diaphragm that is sensitive to only the latter vibration. 9 is a differential amplification element which amplifies the difference component of the signal induced from the diaphragm 7.8.

Here, from the microphone mounting part 3 where there is a lot of vibration to the housing 11.
The vibrations transmitted through are applied to the re-diaphragm 7.8 at the same level and in the same phase. The electrical output 4.4' induced by the re-diaphragm 7.8 also has the same level and phase, and since the amplification@9 amplifies only the difference component, the casing vibration component increases [@l! It does not appear in the output 10 of 9.

On the other hand, a sound guide hole 12 is provided in the microphone housing 11 in front of the diaphragm 7, and the diaphragm 7 can also feel acoustic vibrations, but the diaphragm 8 does not have a corresponding sound guide hole, so I don't feel any vibrations. Therefore, since only the output 4 of the diaphragm 7 responds to acoustic vibrations, even if the difference component is amplified by the amplifier 9, the acoustic vibrations will not be canceled and will appear in the output 10.

As explained above, the first embodiment of the present invention does not require a special anti-vibration mechanism as in the prior art, so it is compact and
It is simple and easy to manufacture, and its properties do not depend on wooden materials that change significantly over time, such as sponge rubber, springs, and dampers, so it can provide stable properties over a long period of time.

Next, a second embodiment of the present invention will be described. FIG. 4 is an explanatory diagram showing a second embodiment of the present invention, and the same reference numerals as in FIG. 3 indicate the same components.

In the first embodiment, two diaphragms are housed in the same microphone housing, but in the second embodiment, they are housed in separate microphone housings, as shown in FIG. This is what I did. That is, it is also possible to use two independent microphones 1.1' and arrange them close to each other in the housing 13, one of which is provided with the sound guide hole 12 and the other with no sound guide hole. The same effects as in the first embodiment can be obtained.

As explained in detail above, the present invention can cancel the vibrations transmitted through the casing and extract only the acoustic vibrations. This makes it possible to obtain a microphone that is most suitable for applications that require high reliability that will not be damaged even if dropped on the floor, such as when transmitting and receiving calls using a telephone.

[Brief explanation of drawings]

Figures 1 and 2 are explanatory diagrams of conventional vibration-resistant microphones.
FIG. 3 is an explanatory diagram of the first embodiment of the invention, and FIG. 4 is an explanatory diagram of another embodiment of the invention. 1 microphone, 7.8 diaphragm, 11 microphone casing, 12 sound guide hole, 13 casing into which the microphone is incorporated, 9 ・Differential amplification carp patent applicant Oki Electric Industry Co., Ltd. Agent Toshiaki Suzuki Figure 1 Figure 2 Figure 3 Figure 1 Figure 4

Claims (2)

[Claims] (1) Two diaphragms are provided in the same housing so as to be isolated from each other, and a differential amplification system is provided to amplify the difference component between the outputs of both diaphragms. A vibration-resistant microphone characterized in that by providing a sound guide hole only for the diaphragm, one diaphragm is affected by the casing vibration and acoustic vibration, and the other diaphragm is affected only by the casing vibration. . (2) WI4I according to Claim 1, characterized in that each independent microphone is used as a diaphragm!
moving microphone.