JP7340769B2 - Microphones and vehicle microphones - Google Patents

Description

The present disclosure relates to microphones.

In recent years, even in noisy environments, higher-performance microphones have been developed that make it difficult for noise to enter structurally or reduce noise by performing signal processing such as directional synthesis and noise suppression using multiple elements. A module is being developed. Such high-performance microphone modules are becoming popular for use in hands-free calls and voice recognition in vehicles. For example, there is a prior art of a small and thin microphone module structure that utilizes a small and thin mounting type microphone sensor that can be surface mounted using a MEMS construction method or the like as disclosed in Patent Document 1.

JP2017-183911A

Improvements in microphone performance include prevention of sound leakage around the sound hole of the microphone sensor, prevention of noise itself from entering through multiple paths, and signal processing performance using signals from multiple microphone sensors. It is necessary to prevent the deterioration of Therefore, a structure with a sealing function, that is, a structure in which the components are sealed is essential.

However, the above-mentioned conventional vehicle-mounted microphone has the following problems regarding the bush that seals the microphone and the bezel. In other words, it is not possible to ensure a large contact area between the bush and the bezel and high sealing performance cannot be ensured, or if an attempt is made to increase the contact area, the mounting area cannot be increased, which poses a problem in downsizing.

In addition, in order to strengthen the sealing, it is possible to install sealing parts or adhesive between the bezel and the case, but this increases the number of parts and man-hours, which increases costs. becomes a factor.

Furthermore, in recent years, flattening of frequency characteristics in a wide band has been required for in-vehicle microphones, such as wideband/super wideband hands-free systems. However, as in-vehicle microphones become smaller, resonance is caused due to their shape, such as the sound path becoming elongated, and this may pose a problem in meeting the above-mentioned frequency characteristic requirements.

The objective of the present disclosure is to improve sealing performance while maintaining miniaturization.

The main present disclosure for solving the above-mentioned problems includes a printed circuit board having a first sound hole, a microphone element mounted on the printed circuit board so as to cover the first sound hole, and a second sound hole. a microphone housing which houses the printed circuit board so that the second sound hole and the first sound hole face each other; and a microphone housing disposed between the second sound hole and the first sound hole. a third sound hole that is provided and communicates with the first sound hole and the second sound hole; and a first contact surface that contacts the printed circuit board at one end side of the third sound hole. , a bushing having a flange having a second contact surface that contacts the microphone housing at the other end side of the third sound hole; a conductive first filter having a width larger than the width of the sound hole, and the microphone element transmits sound waves from the outside through the second sound hole, the third sound hole and the third sound hole. The microphone collects sound through the first sound hole, the printed circuit board has a ground land, and the ground land and the first filter are in contact and electrically conductive .
The present disclosure also provides a printed circuit board having a first sound hole, a microphone element mounted on the printed circuit board so as to cover the first sound hole, and a second sound hole. a microphone housing that houses the printed circuit board so that the second sound hole and the first sound hole face each other; a microphone housing that is disposed between the second sound hole and the first sound hole; a third sound hole that communicates with the first sound hole and the second sound hole; a first contact surface that contacts the printed circuit board at one end side of the third sound hole; a bush having a flange having a second contact surface that contacts the microphone housing on the other end side of the sound hole; a felt attachment hole provided in the bush; and the felt attachment hole, a felt provided so as to close the third sound hole, and the microphone element transmits sound waves from the outside to the second sound hole, the third sound hole, and the first sound hole. The microphone collects sound through a hole, and the depth of the felt-attached hole is greater than the thickness of the felt.

According to the present disclosure, sealing performance can be improved while maintaining miniaturization.

A schematic diagram showing the structure of an in-vehicle microphone according to Embodiment 1 of the present disclosure A schematic diagram showing the structure of an in-vehicle microphone according to Embodiment 2 of the present disclosure A schematic diagram showing the structure of an in-vehicle microphone according to Embodiment 3 of the present disclosure A schematic diagram showing the structure of an in-vehicle microphone according to a modification of Embodiment 1 of the present disclosure A schematic diagram showing the structure of an in-vehicle microphone according to a modification of Embodiment 3 of the present disclosure A schematic diagram showing the structure of an in-vehicle microphone according to a modification of Embodiment 3 of the present disclosure A schematic diagram showing the structure of an in-vehicle microphone according to a modification of Embodiment 1 of the present disclosure

Embodiments of the present disclosure will be described below with reference to the drawings. Each of the embodiments described below is merely an example, and does not exclude the application of various modifications and techniques that are not specified in each of the embodiments below. Moreover, each configuration of each embodiment can be implemented with various modifications without departing from the spirit thereof. Furthermore, each configuration of each embodiment can be selected or combined as necessary.

In addition, in all the figures for explaining each embodiment, the same elements are generally denoted by the same reference numerals, and their explanations may be omitted.

In the following, an example will be described in which the direction in which the lower sound hole type mounted microphone sensor 43 collects incoming sound waves is downward.

(Embodiment 1)
FIG. 1 is a schematic diagram showing the structure of a vehicle-mounted microphone according to Embodiment 1 of the present disclosure.

The in-vehicle microphone of this embodiment includes a lower sound hole type mounted microphone sensor 43 (microphone element), a printed circuit board 41, a connector 10, a bush 30, a panel 20, and a bezel 50.

Here, the in-vehicle microphone has a configuration in which a printed circuit board 41 is housed in a housing space formed by a panel 20, a bezel 50, and a connector 10. In other words, the panel 20, the bezel 50, and the connector 10 constitute a microphone housing.

More specifically, a printed circuit board sound hole 46 (first sound hole) for sound collection is formed in the printed circuit board 41, and a lower sound hole is formed above the printed circuit board sound hole 46 so as to cover the printed circuit board sound hole 46. A hole-mounted microphone sensor 43 is provided. The lower sound hole type mounted microphone sensor 43 is, for example, a surface-mounted silicon microphone formed by a MEMS construction method.

Furthermore, a mounting component 42 for forming an electric circuit is arranged on the printed circuit board 41, and the connector pin 11 of the connector 10 is connected to the mounting component 42. The electrical signal generated by the lower sound hole type mounted microphone sensor 43 is output to the outside via the mounted component 42 and the connector pin 11.

A bush 30 is provided directly under the printed circuit board 41 as a sealing material. The bush 30 is disposed between the printed circuit board sound hole 46 and a bezel sound hole 51 (second sound hole) to be described later.

The bush 30 is installed around the printed circuit board sound hole 46. The bush 30 is provided with an outer flange-shaped bush sealing rib 32 (flange portion) at the lower end of its side surface.

The bush 30 has a bush sound hole 31 (third sound hole) extending in the vertical direction, a contact surface 81 (first contact surface) that contacts the lower surface of the printed circuit board 41, and a lower side of the bezel 50. It has a contact surface 82 (second contact surface) that comes into contact with the inner surface of.

The bushing sound hole 31 is arranged so that the printed circuit board sound hole 46 and the bezel sound hole 51 arranged opposite to the printed circuit board sound hole 46 communicate with each other. Then, the sound waves that have entered the bezel sound hole 51 propagate to the lower sound hole type mounted microphone sensor 43 via the bush sound hole 31 and the printed circuit board sound hole 46 .

The bush 30 is in close contact with the lower surface of the printed circuit board 41 and the lower inner surface of the bezel 50 at a contact surface 81 with the printed circuit board 41 and a contact surface 82 with the bezel 50 .

The contact surface 81 is a portion that contacts the lower surface of the printed circuit board 41 on the upper end side of the bush sound hole 31 . This contact surface 81 comes into contact with the lower surface of the printed circuit board 41 so as to surround the bush sound hole 31 .

The contact surface 82 is a portion that contacts the lower inner surface of the bezel 50 on the lower end side of the bush sound hole 31, and is the lower surface of the bush sealing rib 32. The contact surface 82 comes into contact with the lower inner surface of the bezel 50 so as to surround the bush sound hole 31 . The contact surface 82 is constituted by the lower surface of the bush sealing rib 32 having an outer flange shape.

The bush 30 is made of an elastic material, and the contact surfaces 81 and 82 are in close contact with the lower surface of the printed circuit board 41 and the lower inner surface of the bezel 50 . As a result, the bush 30 allows sound waves that have entered from the bezel sound hole 51 to leak out from the bush sound hole 31, and sound waves that have entered from areas other than the bezel sound hole 51 to wrap around the bush sound hole 31 and the printed circuit board sound hole. 46. As described above, since the contact surface 82 is constituted by the lower surface of the outer brim-shaped bush sealing rib 32, the area of the contact surface 82, that is, the area between the bush 30 and the bezel 50, is smaller than in the case where the bush sealing rib 32 is not provided. The contact surface can be increased. Thereby, leakage of sound waves from the bezel sound holes 51 and entry of sound waves from areas other than the bezel sound holes 51 can be effectively prevented.

Although the performance of the microphone module can be achieved even with a structure that does not include the bezel 50, the in-vehicle microphone of this embodiment further includes the bezel 50 as an exterior component around the panel 20 as described above. ing. In a microphone module that needs to be compatible with multiple designs, such as a vehicle microphone module, it is common to separately install a bezel 50 as an exterior component.

The bezel 50 and the connector 10 are assembled by fitting the mating claws 12 provided in the connector 10 into the bezel slits 52 provided in the bezel 50 .

At this time, the dimension between the lower surface of the printed circuit board 41 and the lower inner surface of the panel 20 is set to be the same as the height of the outer shape of the bush 30, or so that the height of the outer shape of the bush 30 is larger. ing. In the latter case, the bush 30 will be compressed.

Further, if necessary, for example to ensure dustproofing and appearance, the felt 25 may be installed using double-sided tape or the like so as to close the bezel 50 side of the bushing 30. By setting the depth of the felt attachment hole 33 (the recess for attaching the felt 25) provided in the bush 30 to be larger than the thickness of the felt 25, the sealing performance of the felt 25 can be ensured. Felt 25 constitutes the second filter of the present invention. The second filter may be any filter that allows sound waves to pass through and has a dustproof function, and is not limited to felt.

Note that by forming the felt 25 from a water-repellent material, it is possible to suppress the liquid from reaching the lower sound hole type mounted microphone sensor 43 via the bush sound hole 31.

The target sound to be collected, such as the voice uttered by the speaker, originally enters the lower sound hole type mounted microphone sensor 43 through the target sound path. That is, the above-mentioned sound to be collected originally passes through the bezel sound hole 51 provided in the bezel 50, the bush sound hole 31 provided in the bush 30, and the printed circuit board sound hole 46 in this order. It enters the hole-type mounted microphone sensor 43.

The sound to be collected that has entered the lower sound hole type mounted microphone sensor 43 is converted into an electrical signal by the lower sound hole type mounted microphone sensor 43. The electrical signal is converted into an output signal by an electrical circuit on the printed circuit board 41 and output from the connector pin 11.

At this time, if the sealing between the bushing sealing rib 32 and the bezel 50, in other words, the sealing of the abutting surface 82 on the bushing sealing rib 32 is poor, the target sound may be collected from other than the original target sound path mentioned above. enter in. In this case, an echo occurs because a phase shift occurs in the target sound due to a path difference from the original target sound path.

Further, when there are a plurality of lower sound hole type mounted microphone sensors 43, signals generated by sound waves having a phase shift are mixed, causing performance deterioration of the microphone module even in the process of signal processing. In addition, in actual installation in a vehicle, there is an example in which noise enters from the upper part of the connector 10, and there is also a possibility that noise enters from the contact surface 81 or the contact surface 82. Therefore, the sealing structure for noise reduction as described above prevents the microphone module performance from deteriorating.

In this embodiment, the bush 30 including the bush sealing rib 32 is made of a soft material (elastic material), and the bush sound hole 31 is connected from the printed circuit board sound hole 46 to the bezel sound hole 51. has. As a result, the overall structure of the microphone module can be made smaller and thinner, and the bezel 50 and panel 20 can achieve high performance sealing of the contact surface 81 or the contact surface 82 and strengthen the sealing. Since there is no need for sealing parts or adhesives between the two, it can be constructed at low cost.

Note that when there are multiple lower sound hole type mounted microphone sensors 43, one set of bezel sound hole 51 and bush sound hole 31 is provided for each of the printed circuit board sound holes 46 of each lower sound hole type mounted microphone sensor 43. It is preferable to install As a result, the sound input to the lower sound hole mounted microphone sensor 43 becomes more uniform, and the signal processing performance is further improved. In this case, by making the plurality of bush sound holes 31 each have the same shape, the sound input to the lower sound hole type mounted microphone sensor 43 becomes more uniform, and the signal processing performance is further improved.

As shown in FIG. 4, the bezel sound hole 51 may be made larger than the configuration shown in FIG. 1, and the felt 25 may be attached to a portion of the bush 30 other than the contact surface 82, thereby making the bush sound hole 31 smaller. This makes it possible to achieve high performance sealing of the abutment surface 81 or the abutment surface 82 and further downsize the vehicle-mounted microphone. That is, in the configuration shown in FIG. 4, by making the bezel sound hole 51 larger than the bush sound hole 31, the felt 25 can be directly attached to the bush 30, and the felt 25 can be attached to the bush 30 and the bezel 50. There is no intervention between the two. Therefore, the sealing properties between the felt 25 and the bush 30 can be improved, and the in-vehicle microphone can be further downsized.

Furthermore, by using a mounted microphone sensor consisting of a printed circuit board 41, mounted components 42, and a lower sound hole mounted microphone sensor 43, parts for connecting the microphone to the printed circuit board, such as lead wires, are no longer required, and the number of components can be reduced. becomes possible. Therefore, in addition to making the overall structure of the microphone module smaller and thinner, it is also possible to achieve sealing between the bezel and the microphone module to improve microphone performance.

Alternatively, as shown in FIG. 7, the bezel 50 may be counterbored to provide a recess 53, and the lower surface of the recess 53 may be used as the contact surface 82. As a result, the bush 30 can be disposed further downward, and the lower sound hole type mounted microphone sensor 43 on the bush 30 can be brought closer to the lower surface of the bezel 50. That is, by shortening the target sound path, the influence of the target sound path on the frequency characteristics can be reduced.

Moreover, since the number of parts and the number of work steps are not increased, it is possible to provide a high-performance and inexpensive microphone.

(Embodiment 2)
FIG. 2 is a schematic diagram showing the structure of a vehicle-mounted microphone according to Embodiment 2 of the present invention.

The in-vehicle microphone of the second embodiment shown in FIG. 2 has a solid filter 60 (first filter) inside the bush sound hole 31 instead of the felt 25 (see FIG. 1). Here, the solid filter 60 is an acoustic filter formed of a relatively hard solid having a constant shape and having fine cavities, and is, for example, a sintered body having fine cavities. Objects with microscopic cavities have the effect of lowering the high-frequency characteristics of sounds that pass through them. Therefore, if the solid filter 60 is provided in the bush sound hole 31, it is possible to eliminate the high frequency that occurs when the sound path such as the bush sound hole 31 becomes narrower or longer due to the miniaturization of vehicle microphones. This has the effect of canceling out the resonance at . That is, the frequency characteristics of the sound applied to the lower sound hole type mounted microphone sensor 43, particularly for high frequencies, can be adjusted to flatten the frequency characteristics. Therefore, it is effective to provide the solid filter 60 in response to a request for flattening of the frequency characteristics of the microphone in a wide band from an application using an in-vehicle microphone. Further, since the solid filter 60 has a constant shape, it is easier to handle than an acoustic filter formed of cloth. Note that instead of the solid filter 60, a soft filter that is not solid may be used.

Note that as a method of lowering the amplitude of the high frequency range, it is possible to use felt 25 with low air permeability in the first embodiment, but in order to maintain sealing performance by using felt 25, A felt pasting hole 33 is required. In the vehicle-mounted microphone of the second embodiment, the solid filter 60 is used in place of the felt 25, so the felt attachment hole 33 is not required. Therefore, the in-vehicle microphone according to the second embodiment is advantageous in terms of size reduction by the area of the felt attachment hole 33. In other words, the in-vehicle microphone of the second embodiment maintains the superiority of sealing performance and signal processing similar to that of the first embodiment, and also has excellent adjustment of the frequency characteristics of the sound applied to the in-vehicle microphone. Further miniaturization of in-vehicle microphones can be achieved.

Note that by forming the solid filter 60 from a water-repellent material, or by applying a water-repellent finish to at least the bezel side surface 61 of the solid filter 60 (hereinafter referred to as "solid filter bezel side surface 61"), the bushing can be made of a water-repellent material. Intrusion of liquid into the lower sound hole type mounted microphone sensor 43 via the sound hole 31 can be suppressed.

(Embodiment 3)
FIG. 3 is a schematic diagram showing the structure of a vehicle-mounted microphone according to Embodiment 3 of the present disclosure.

In the vehicle-mounted microphone of the third embodiment shown in FIG. 3, the solid filter 60 is made of a conductive material such as metal, or the solid filter 60 is plated with metal to make its surface conductive.

Further, a printed circuit board earth land 47 provided on the printed circuit board 41 is brought into contact with or joined to the solid filter 60, so that the solid filter 60 and the printed circuit board earth land 47 are electrically connected.

With this structure, in addition to the effects of the second embodiment, the solid filter 60 is given shielding performance against radio noise and static electricity, and is given resistance to radio noise or static electricity that enters from the bush sound hole 31 side. You can get the desired effect.

Note that by making the solid filter 60 conductive and water repellent, or by at least applying a water repellent treatment to the solid filter bezel side surface 61, liquid can pass through the bush sound hole 31 and reach the lower sound hole type mounted microphone sensor 43. Intrusion can be suppressed.

Note that the in-vehicle microphone shown in FIG. 5 or 6 is different from the configuration of the third embodiment shown in FIG. It is something that

In other words, the in-vehicle microphone shown in FIG. 5 differs from the structure of the in-vehicle microphone shown in FIG. It is electrically connected to a conductive solid filter 60 provided inside. In addition, the in-vehicle microphone shown in FIG. 6 differs from the structure of the in-vehicle microphone shown in FIG. It is electrically connected to the provided conductive solid filter 60.

The on-vehicle microphone shown in FIGS. 5 and 6 also has resistance to radio noise or static electricity that enters from the bush sound hole 31 side, and the lower sound hole type mounted microphone Intrusion of liquid into the sensor 43 can be suppressed.

The in-vehicle microphone of the present disclosure is used, for example, in a microphone module that is required to have high performance, be compact, and be thin, such as in a vehicle.

10 Connector 11 Connector pin 20 Panel 22 Fitting claw 25 Felt (second filter)
30 Bush 31 Bush sound hole (third sound hole)
32 Bush sealing rib (flange)
33 Felt attachment hole 41 Printed circuit board 42 Mounted parts 43 Lower sound hole type mounted microphone sensor (microphone element)
46 Printed circuit board sound hole (first sound hole)
47 Printed circuit board earth land 50 Bezel 51 Bezel sound hole (second sound hole)
52 Bezel slit 53 Recess 60 Solid filter (first filter)
61 Solid filter bezel side surface 81 Contact surface (first contact surface)
82 Contact surface (second contact surface)

Claims (10)

a printed circuit board having a first sound hole;
a microphone element mounted on the printed circuit board so as to cover the first sound hole;
a microphone housing having a second sound hole and housing the printed circuit board so that the second sound hole and the first sound hole face each other;
a third sound hole disposed between the second sound hole and the first sound hole and communicating with the first sound hole and the second sound hole; and the third sound hole. a flange having a first contact surface that contacts the printed circuit board at one end side and a second contact surface that contacts the microphone casing at the other end side of the third sound hole; bush and
a conductive first filter provided in the third sound hole and having a width larger than the width of the first sound hole;
The microphone element collects sound waves from the outside via the second sound hole, the third sound hole, and the first sound hole,
The printed circuit board has a ground land,
A microphone in which the ground land and the first filter are in contact and electrically conductive. The microphone of claim 1, wherein the first filter is a solid filter. The microphone according to claim 1 or 2, wherein the first filter is made of a water-repellent material, or at least a portion of the surface of the first filter is treated to be water-repellent. The microphone according to any one of claims 1 to 3, further comprising a water-repellent second filter provided so as to close the third sound hole. a printed circuit board having a first sound hole;
a microphone element formed by a MEMS construction method and mounted on the printed circuit board so as to cover the first sound hole;
a microphone housing having a second sound hole and housing the printed circuit board so that the second sound hole and the first sound hole face each other;
a third sound hole disposed between the second sound hole and the first sound hole and communicating with the first sound hole and the second sound hole; and the third sound hole. a flange having a first contact surface that contacts the printed circuit board at one end side and a second contact surface that contacts the microphone casing at the other end side of the third sound hole; bush and
a felt pasting hole provided in the bush;
a felt provided in the felt pasting hole so as to close the third sound hole,
The microphone element collects sound waves from the outside in the order of the second sound hole, the felt pasting hole, the third sound hole, and the first sound hole,
The depth of the felt pasting hole is greater than the thickness of the felt.
Car microphone. The vehicle- mounted microphone according to claim 5, further comprising a first filter provided in the third sound hole. The vehicle-mounted microphone according to claim 6, wherein the first filter is a solid filter. The vehicle-mounted microphone according to claim 6 or 7, wherein the first filter is conductive. The in-vehicle filter according to any one of claims 6 to 8, wherein the first filter is made of a water-repellent material, or at least a part of the surface of the first filter is treated to be water-repellent. microphone. The vehicle-mounted microphone according to any one of claims 5 to 9, wherein the felt is installed with double-sided tape.

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