JP4411235B2 - Microphone structure - Google Patents

Description

  The present invention relates to a microphone structure.

  In general, a small wireless device such as a mobile phone uses a quarter-wave antenna, so that a large high-frequency current flows through the housing during electromagnetic wave transmission. For this reason, noise such as noise is induced in the microphone of the transmitter due to the influence of electromagnetic waves due to the current, and there is a problem that sound quality deteriorates. In addition, in a microphone for voice recognition used in an in-vehicle navigation device or the like, since operation input is performed by voice, there has been a problem that deterioration in sound quality leads to erroneous recognition of an operation instruction.

Therefore, as shown in Patent Documents 1 to 6, various countermeasures against electromagnetic interference are taken, such as covering the microphone element itself with a metal shield case.
As an example, FIG. 8 shows a microphone device 50 described in Patent Document 2, in which a microphone element 51 is accommodated in a container 52 made of conductive rubber. Further, a front cover 53 made of a wire mesh and a non-woven cloth is provided in front of the microphone element 51, and a front case 55 in which a plurality of transmission holes 54 are formed is provided on all of them. The rear side of the microphone element 51 is soldered to a printed circuit board 56 to which an electric signal from the microphone element 51 is transmitted. Here, the vertical direction in FIG. 8 is the front-back direction in the microphone device 50.

With such a configuration, sound leaking into the microphone element 51 from other than the transmission hole 54 can be absorbed and acoustically shielded by the flexibility of the conductive rubber constituting the container 52. Further, the microphone element 51 can be electrically shielded by the conductivity of the container 52, and the transmission output can be efficiently guided to the printed circuit board 56. Therefore, the microphone device 50 can be reduced with little deterioration in sound quality due to the influence of electromagnetic waves or the like.
Japanese Utility Model Publication No. 5-60079 JP-A-6-78040 JP 11-74955 A JP-A-11-155197 JP 2001-135967 A JP 2001-7589 A

  However, since the conventional microphone element employs a method of detecting sound by changing the electrostatic capacitance due to vibration of the vibrating membrane, it is easily affected by electromagnetic waves, and reliably shields electromagnetic waves that leak into the microphone element with a simple microphone structure. It was difficult.

  On the other hand, instead of a conventional electrostatic microphone, an optical microphone system that directly detects sound using light waves has been developed in recent years. In an optical microphone system, unlike an electrostatic microphone, it is less affected by the leakage of electromagnetic waves, but it is necessary to provide an electrical circuit as a photoelectric conversion signal output that converts and amplifies the detected optical signal into an electrical signal. In particular, when the electric circuit is located between the noise source and the microphone element, there is a problem that the electric circuit itself is affected by electromagnetic waves.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a microphone structure capable of effectively shielding electromagnetic waves with a simple configuration.

In order to solve the above problem, the invention according to claim 1 is a microphone structure,
A microphone element that detects sound as an electrical signal;
A printed circuit board provided on the lower surface of the microphone element for transmitting the electrical signal;
As well as covering the microphone element and the printed circuit board from above, a conductive upper case having a locking pawl which the printed circuit board is electrically connected to the engagement with the ground pattern of the printed circuit board,
A coil spring that is provided inside the upper case and presses the grounding pattern of the printed circuit board toward the locking claw by an urging force;
A conductive lower case that is engaged with the upper case and covers its lower surface;
It is characterized by providing.

According to the present invention, since the microphone element and the printed circuit board are covered with the upper case and the lower case having conductivity, it is possible to shield the electromagnetic waves in the air that leak into them. Accordingly, a microphone structure that can effectively shield electromagnetic waves with a simple configuration can be obtained.
In addition, since the coil spring provided in the upper case presses and holds the printed circuit board, the position of the printed circuit board is stabilized and the electrical connection with the microphone element is also stabilized. Furthermore, since the microphone structure can be easily assembled only by engaging the printed circuit board with the upper case and then engaging the lower case with the upper case, productivity is improved.

  Hereinafter, an embodiment of a microphone structure according to the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

  FIG. 1 is a perspective view of an optical microphone 1 according to the present embodiment, and FIG. 2 is a cross-sectional view taken along a line II in FIG. A lower case 2 as shown in FIG. 3 is provided below the optical microphone 1.

  The bottom surface of the lower case 2 has a substantially rectangular shape, and a plate-like edge portion 3 is erected substantially perpendicular to the bottom surface at the edge. A plurality of first locking claws 4 projecting inward are formed on the inner surfaces of both sides of the edge portion 3. Furthermore, the 1st cable holding part 5a which is notched circularly is formed in the rear-end center part of the edge part 3. As shown in FIG.

  An upper case 8 that opens downward is mounted on the lower case 2. An arc-shaped second cable holding portion 5 b corresponding to the cable holding portion 5 a of the lower case 2 is formed at the center of the rear end of the upper case 8. In addition, a partition plate 18 extending downward and extending toward the front end is provided at a substantially center inside the upper surface of the upper case 8. Above the partition plate 18, a sound guide portion 9 surrounded by the upper surface and side surfaces of the upper case 8 is formed. In addition, a sound receiving hole 10 for opening the lower part of the partition plate 18 and the sound guide portion 9 is formed behind the lower surface of the partition plate 18. Furthermore, a coil holding portion 19 that protrudes downward is formed along the vertical direction on the lower surface of the partition plate 18 and in front of the sound receiving hole 10. The coil holding part 19 houses a coil spring 11 that can be expanded and contracted in the vertical direction.

FIG. 4 is a perspective view of the upper case 8, and FIGS. 5 to 7 show an assembly process of the optical microphone 1 and a cross-sectional view of each configuration.
As shown in FIG. 4, locking holes 12 through which the first locking claws 4 engage are penetrated on both sides of the upper case 8. Moreover, as shown in FIGS. 5-7, the 2nd latching claw 13 ... which protrudes inside from the latching hole 12 is formed in the lower surface of the latching hole 12 so that it may incline inside, so that it goes upwards. Has been.

A flat printed board 14 is locked to the upper surface of the second locking claw 13. The coil spring 11 is in contact with the upper surface of the printed circuit board 14 (see FIG. 2), and since the urging force from the coil spring 11 is applied, the printed circuit board 14 is pressed by the second locking claw 13. Yes. A drive circuit electronic component 15 is mounted on the lower surface of the printed circuit board 14, and a ground pattern (not shown) is formed by a through hole. Further, one end of a cable 6 covered with an insulating film with a plurality of electric wires as a bundle is connected to the rear of the upper surface of the printed circuit board 14.
An external configuration (not shown) is connected to the other end of the cable 6 so that an electrical signal from the printed circuit board 14 is transmitted to the external configuration. Further, a cylindrical cable cover 7 is attached to the cable 6, and the cable cover 7 is held by the first cable holding part 5 a and the second cable holding part 5 b all around.

  On the upper surface of the printed circuit board 14, there is provided a light vibration detection unit 16 as a microphone element that detects light vibration caused by the sound wave guided by the sound guide portion 9 and passed through the sound receiving hole 10 as an electric signal. Here, the shape of the optical vibration detection unit 16 is a substantially rectangular parallelepiped shape, and a pressure contact connector 17 is provided on the lower surface of the optical vibration detection unit 16 for electrical connection by pressure contact with an electronic component or the like. The upper surface of the optical vibration detection unit 16 is in contact with the lower surface of the partition plate 18 and faces the sound receiving hole 10.

  Here, the upper case 8 and the lower case 2 are made of a conductive material or a surface-treated material, and are engaged with each other without a gap, thereby covering the optical vibration detection unit 16 and the printed board 14 in the air. Shield from electromagnetic waves.

  Next, an assembly process of the optical microphone 1 in the present embodiment will be described.

  First, the drive circuit electronic component 15 and the cable 6 are arranged on the printed circuit board 14. Next, as shown in FIGS. 5 and 6, the optical vibration detection unit 16 and the printed board 14 are covered and engaged with the upper case 8.

  Specifically, the optical vibration detection unit 16 is inserted through the upper case 8 so as to face the sound receiving hole 10 (see FIG. 5). Subsequently, the printed circuit board 14 is inserted into the upper case 8 to be brought into pressure contact with the pressure contact connector 17 of the optical vibration detection unit 16 and mounted on the upper surface of the second locking claw 13 (see FIG. 6). At this time, since the second locking claw 13 is formed to be inclined, the printed circuit board 14 can be easily inserted into the upper case 8. Further, the printed board 14 is pressed against the upper surface of the second locking claw 13 by the coil spring 11 of the upper case 8, and the position is stably attached. Further, since the optical vibration detection unit 16 is locked by contacting the partition plate 18 with its upper surface, the printed circuit board 14 is in pressure contact with the pressure contact connector 17 and is electrically connected to the optical vibration detection unit 16.

After the optical vibration detection unit 16 and the printed circuit board 14 are covered with the upper case 8, the upper case 8 is attached to the lower case 2. FIG. 7 is a cross-sectional view taken along the line II-II in FIGS. 1 and 2 in a state where the lower case 2 is attached to the upper case 8.
Specifically, the cable cover 7 is engaged with the second cable holding portion 5b of the upper case 8 and the first cable holding portion 5a of the lower case 2 to hold the cable 6 without a gap. At the same time, the first locking claw 4 of the lower case 2 is engaged with the locking hole 12 of the upper case 8 from the outside, and the opening and the locking hole of the upper case 8 are formed by the bottom surface and the edge 3 of the lower case 2. All 12 are covered.

  As described above, according to the present embodiment, since the optical vibration detection unit 16 and the printed circuit board 14 are covered with the upper case 8 and the lower case 2 having conductivity, in the air leaking from other than the sound receiving hole 10. It can shield electromagnetic waves. Further, since the coil spring 11 of the upper case 8 and the pressure contact connector 17 of the optical vibration detection unit 16 are in pressure contact with the printed circuit board 14, the position and electrical connection of the printed circuit board 14 are stabilized. Furthermore, the optical microphone 1 engages the first latching claw 4 of the lower case 2 with the latching hole 12 of the upper case 8 after the printed circuit board 14 is latched to the second latching claw 13 of the upper case 8. This makes it easy to assemble, so productivity is improved.

  As the printed board 14, a multilayer printed board having three or more layers can be used. In that case, if the ground pattern is formed on the entire surface other than both surfaces, the electrical stability can be further improved.

It is a perspective view of the microphone concerning this embodiment. It is sectional drawing in the II line | wire of FIG. It is a perspective view of the lower case concerning this embodiment. It is a perspective view of the upper case concerning this embodiment. It is explanatory drawing which shows the assembly process of the microphone concerning this embodiment. It is explanatory drawing which shows the assembly process of the microphone concerning this embodiment. It is sectional drawing in the II-II line of FIG.1 and FIG.2. It is sectional drawing of the conventional microphone.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical microphone 2 Lower case 3 Edge 4 1st latching claw 6 Cable 7 Cable cover 8 Upper case 9 Sound guide part 10 Sound receiving hole 11 Coil spring 12 Locking hole 13 Second latching claw 14 Printed circuit board 15 For drive circuits Electronic component 16 Optical vibration detection unit 17 Pressure contact connector

Claims (1)

A microphone element that detects sound as an electrical signal;
A printed circuit board provided on the lower surface of the microphone element for transmitting the electrical signal;
As well as covering the microphone element and the printed circuit board from above, a conductive upper case having a locking pawl which the printed circuit board is electrically connected to the engagement with the ground pattern of the printed circuit board,
A coil spring that is provided inside the upper case and presses the grounding pattern of the printed circuit board toward the locking claw by an urging force;
A conductive lower case that is engaged with the upper case and covers its lower surface;
A microphone structure comprising:

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