JP2022068640A - Vibration sensor - Google Patents

Abstract

To provide a vibration sensor capable of adjusting the frequency characteristics of a diaphragm during product assembly.SOLUTION: A vibration sensor includes a lower case with an open top, a middle case with an open bottom and a notch at its edge, which is housed in the lower case, a diaphragm whose edge is sandwiched between the edges of the lower case and the middle case and fixed to the edge of the lower case or middle case with an adhesive injected from the notch, and a sensor that detects a change in pressure due to vibration of the diaphragm.SELECTED DRAWING: Figure 2

Description

The present invention relates to a vibration sensor.

As the prior art of the vibration sensor, there are, for example, Patent Documents 1 and 2.

Jitsukaisho 48-084485 Gazette Jikkai Sho 62-203418

The problem with conventional vibration sensors is that it is difficult to adjust the frequency characteristics of the diaphragm during product assembly.

Therefore, an object of the present invention is to provide a vibration sensor capable of adjusting the frequency characteristics of the diaphragm during product assembly.

The vibration sensor of the present invention has a lower case with an open upper surface, an intermediate case with an open lower surface and a notch at the edge thereof, and an intermediate case housed in the lower case, and an edge thereof at the edges of the lower case and the intermediate case. It includes a diaphragm whose edge is fixed to the edge of the lower case or intermediate case by an adhesive that is sandwiched and injected through a notch, and a sensor that detects pressure changes due to vibration of the diaphragm.

According to the vibration sensor of the present invention, the frequency characteristic of the diaphragm can be adjusted during product assembly.

The perspective view of the vibration sensor of Example 1. FIG. An exploded perspective view of the vibration sensor of the first embodiment. The plan view of the vibration sensor of Example 1. FIG. FIG. 3 is a perspective sectional view of the vibration sensor of the first embodiment.

Hereinafter, embodiments of the present invention will be described in detail. The components having the same function are given the same number, and duplicate explanations are omitted.

Hereinafter, the configuration of the vibration sensor of the first embodiment will be described with reference to FIGS. 1 to 4. As shown in FIG. 2, the vibration sensor 1 of this embodiment includes a lower case 11, a diaphragm 12, an intermediate case 13, a sensor 14, a first packing 15, a second packing 16, and a sensor substrate. The structure includes 17, the upper case 18, the relay board 19, and the conductor 10.

<Lower case 11>
The upper surface of the lower case 11 is opened and includes a pair of screw holes 111.

<Diaphragm 12>
The peripheral edge of the diaphragm 12 is sandwiched between the edges of the lower case 11 and the intermediate case 13, and the peripheral edge is fixed to the edge of the lower case 11 or the intermediate case 13 by an adhesive injected from a notch 132 described later. , Vibrates with external vibration.

The diaphragm 12 is, for example, a thin metal plate having t0.1 or less, and may be stainless steel or the like. The diaphragm 12 may be made of a material other than the thin metal plate, for example, a resin film or paper. In this embodiment, the diaphragm 12 has a circular shape and a central portion having an upwardly convex dome shape.

The diaphragm 12 is arranged in a closed space surrounded by a lower case 11 opened on the upper surface and an intermediate case 13 opened on the lower surface. As shown in FIG. 4, the internal space created between the intermediate case 13 and the diaphragm 12 is referred to as an air chamber A, and the internal space created between the lower case 11 and the diaphragm 12 is referred to as an air chamber B. The sensor 14, which will be described later, is arranged in the air chamber A. The edge of the diaphragm 12 is fixed to the intermediate case 13 by a method without rattling (for example, adhesion by an adhesive or welding by heat as described above). The diaphragm 12 may be fixed to the lower case 11 instead of the intermediate case 13.

<Intermediate case 13>
The intermediate case 13 has a lower surface opened, has a pair of screw holes 131, three notches 132 on the edges thereof, and a through hole 133 in the center, and is housed in the lower case 11. The intermediate case 13 may be fixed to the lower case 11 by a method without rattling (for example, press-fitting, bonding, welding, screw fastening).

<Sensor 14>
The sensor 14 detects a pressure change due to the vibration of the diaphragm 12. The sensor 14 can be, for example, a microphone, and if it is a microphone, it is advantageous in terms of cost. The sensor 14 can be an ECM (electret condenser microphone). Further, the sensor 14 may be another pressure detecting element such as a MEMS microphone. The sensor 14 is solder-mounted on the lower surface (back surface) of the sensor substrate 17.

<First packing 15>
The first packing 15 is arranged in a stepped portion 134 provided so as to orbit the edge of the through hole 133. The first packing 15 is arranged to ensure airtightness around the sensor 14.

<Second packing 16>
The second packing 16 is arranged on a step portion 112 provided on the inner peripheral surface of the lower case 11. The second packing 16 is arranged to ensure the airtightness of the entire vibration sensor 1.

<Sensor board 17>
The sensor board 17 is screwed to the screw hole 131 of the intermediate case 13 by a screw 171 and the sensor 14 is fixed (mounted) on the lower surface thereof and placed on the first packing 15. As shown in FIG. 4, the air chamber A is sealed by sandwiching the first packing 15 between the sensor substrate 17 and the intermediate case 13 and compressing the packing.

<Upper case 18>
The upper case 18 is screwed to the screw hole 111 of the lower case 11 by a screw 181 to cover the lower case 11, the intermediate case 13, the sensor board 17, and the like, and the relay board 19 is placed on the upper surface thereof. It is provided with a recess 182 for the purpose. As shown in FIG. 4, a second packing 16 is sandwiched between the upper case 18 and the lower case 11 to ensure airtightness between the outside air and the internal space, and sound is input to the sensor 14 from the outside. It is preventing that.

<Relay board 19>
The relay board 19 is placed on the upper case 18 and screwed to the screw hole 183 provided in the recess 182 of the upper case 18 by the screw 193. A cable (not shown) is mounted (connected) on the relay board 19. The cable connected to the relay board 19 is assumed to be a multi-core wire, but may be a single-core wire.

<Conductor 10>
The conductor 10 connects the relay board 19 and the sensor board 17. The conductor 10 is provided for extracting an electric signal from the sensor substrate 17. The conductor 10 is preferably a thin conductor (metal wire), and may be, for example, a urethane copper wire or another material. If the relay board 19 and the sensor board 17 are connected in a bent (slackened) state of the conductor 10, unnecessary vibration (noise) is less likely to be transmitted to the inside of the vibration sensor 1, which is more preferable. One of the conductors 10 is soldered to the sensor substrate 17, and the other is drawn out from the through hole 184 provided in the recess 182 of the upper case 18 and soldered to the relay substrate 19. The through hole 184 is sealed by placing the relay board 19 and screwing it.

<Ventilation of air chamber A and air chamber B>
As shown by the broken line arrow in the partially enlarged view (see the inside of the thick frame ellipse in the figure) showing a part of the perspective sectional view of FIG. 4, the air generated between the intermediate case 13 and the diaphragm 12 A gap (ventilation passage) for ventilating the chamber A and the air chamber B generated between the lower case 11 and the diaphragm 12 is provided. The air chamber A and the air chamber B are communicated with each other by a ventilation passage, but both are isolated from the outside air. Since the ventilation passage is for pressure adjustment, a fine passage may be used.

<< Effect of vibration sensor 1 of this embodiment: Frequency characteristics can be adjusted >>
The resonance frequency of the diaphragm 12 can be changed and the frequency characteristic of the vibration sensor 1 can be adjusted by the amount of the adhesive injected from the notch 132. For example, the characteristics can be measured after the vibration sensor 1 is temporarily assembled, and the process of disassembling the vibration sensor 1 and injecting (increasing the amount) of the adhesive can be repeated based on the measurement result to fine-tune the frequency characteristics.

<< Effect of vibration sensor 1 of this embodiment: Improvement of sensitivity >>
When the diaphragm 12 built in the vibration sensor 1 is vibrated from the outside, a tremor occurs, and the tremor causes a pressure change in the internal space (air chamber A, air chamber B) in which the diaphragm 12 is installed. .. By detecting this pressure change with the sensor 14, it is possible to obtain an output larger than the output of the sensor 14 alone, and it is possible to improve the sensitivity.

<< Effect of vibration sensor 1 of this embodiment: Resonance frequency can be increased >>
Generally, the diaphragm in the vibration sensor resonates at the frequency of the natural vibration and the vibration is amplified, so that the primary resonance frequency of the diaphragm is the maximum frequency that can be measured. Therefore, in order to widen the measurable frequency range of the vibration sensor, it is necessary to increase the resonance frequency of the diaphragm. When the outer diameter and material of the diaphragm are fixed, the resonance frequency can be increased by increasing the thickness of the diaphragm, but the thickening causes a problem that the diaphragm becomes heavy and the sensitivity decreases.

In order to deal with the above problems, in the vibration sensor 1 of this embodiment, the diaphragm 12 is formed by processing it into a dome shape. This makes it possible to increase the resonance frequency while preventing a decrease in sensitivity.

<< Effect of vibration sensor 1 of this embodiment: Prevention of decrease in sensitivity due to heat >>
When the air chamber above the diaphragm and the air chamber below the diaphragm are separate enclosed spaces, if a pressure difference is generated between the air chambers due to heat, the diaphragm deforms to the lower pressure side for sensitivity. May be affected. Since the vibration sensor 1 of this embodiment is provided with a gap (ventilation passage) for ventilating the air chamber A and the air chamber B, the pressures of the air chamber A and the air chamber B can be uniformly maintained, and the sensitivity is lowered. Can be prevented. Since the purpose of the above-mentioned ventilation passage is to maintain the pressure uniformly, the cross-sectional area of the passage may be small, and it is more preferable if the ventilation passage is configured to open only when pressure is applied.

<< Effect of vibration sensor 1 of this embodiment: Realization of a structure that makes it difficult for noise to be transmitted >>
As shown in FIGS. 2 and 4, the sensor board 17 is fixed to the intermediate case 13 by screwing, while the relay board 19 is fixed to the upper case 18 by screwing, so that the relay board 19 to the sensor board 17 are fixed. It is possible to realize a structure in which vibration is not easily transmitted directly. As a result, vibration transmitted through the cable (not shown) connected to the relay board 19 is less likely to be transmitted to the sensor board 17 and the sensor 14, so noise can be recommended.

The relay board 19 and the sensor board 17 are electrically connected by a conductor 10. By making the conductor 10 a thin metal wire and wiring it with bending (slack), it is possible to form a structure in which vibration (noise) generated in the relay board 19 is not easily transmitted to the sensor board 17.

Claims (6)

The lower case with an open top surface and
An intermediate case with an open bottom and a notch at the edge, which is housed in the lower case,
A diaphragm whose edge is sandwiched between the edges of the lower case and the intermediate case and whose edge is fixed to the edge of the lower case or the intermediate case by an adhesive injected from the notch.
A vibration sensor including a sensor that detects a pressure change due to the vibration of the diaphragm. The vibration sensor according to claim 1.
A vibration sensor provided with a gap for ventilating an air chamber A generated between the intermediate case and the vibrating plate and an air chamber B generated between the lower case and the vibrating plate. The vibration sensor according to claim 1 or 2.
The diaphragm is a dome-shaped vibration sensor. The vibration sensor according to any one of claims 1 to 3.
A vibration sensor in which the sensor is a microphone. The vibration sensor according to any one of claims 1 to 4.
A sensor board that is screwed only to the intermediate case and the sensor is fixed to the lower surface thereof.
An upper case that is screwed only to the lower case and has a shape that covers the lower case, the intermediate case, and the sensor substrate.
A relay board that is placed on the upper case and screwed only to the upper case,
A vibration sensor including a conductor connecting the relay board and the sensor board. The vibration sensor according to claim 5.
The conductor is a copper wire, and a vibration sensor connecting the relay board and the sensor board in a state where the copper wire is bent.

Images