Microphone device

Abstract

A microphone device is provided with: a microphone (10); a case that houses the microphone (10); a cushion (30) that is disposed between the microphone (10) and the case; and a cover (50) that presses the cushion (30) to fix the cushion to the case. The cushion (30) is provided with a cylindrical inner circumferential part (31) that comes into contact with the microphone (10), and an outer circumferential part (32) that is pressed by the cover (50). When a direction parallel to the axis of the inner circumferential part (31) is defined as the x direction, the cover (50) presses the outer circumferential part (32) from one side in the x direction, and a recessed part (36) is formed in a surface layer part on said one side of the inner circumferential part (31).

Description

Microphone device Cross-reference to related applications

[0001] This application is based on Japanese Patent Application No. 2025-11438 filed on January 27, 2025, the contents of which are incorporated herein by reference.

[0002] This disclosure relates to a microphone device.

[0003] In a microphone device such as an ultrasonic sensor, in order to suppress unnecessary vibrations on the side surface of the microphone while transmitting and receiving ultrasonic waves in front of the microphone, it has been proposed to assemble an elastic body such as rubber on the side surface of the microphone (see, for example, Patent Document 1).

[0004] Specification of Chinese Patent Application Publication No. 109906480

[0005] In a microphone device, from the manufacturing aspect, it is required that each member is easy to assemble. For example, when preparing a microphone, a case, a cushion composed of an elastic body, and a cover, and arranging the cushion, the microphone, and the cover in order on the case and pressing them from above with the cover to fix each component to the case, the assembly of each member is easy. As the shape of the cushion, a cylindrical shape that houses the microphone inside is considered in order to suppress vibrations on the side surface of the microphone while enabling transmission and reception of ultrasonic waves in the front. Also, as the shape of the cover, a cylindrical shape that covers the outer peripheral portion of the cushion while exposing the front of the microphone and the front of the inner peripheral portion of the cushion to enable transmission and reception of ultrasonic waves in front of the microphone and is engaged with the case is considered.

[0006] When using cushions and covers of such shapes, if the rigidity of the inner peripheral portion of the cushion is high, when the outer peripheral portion of the cushion is pressed by the cover, the tip of the inner peripheral portion of the cushion may move away from the microphone, and there is a possibility of a gap being formed between the tip of the cushion and the microphone. If a gap is formed, the characteristics of the microphone device may deteriorate.

[0007] In view of the above points, this disclosure aims to provide a microphone device that can suppress the degradation of characteristics.

[0008] To achieve the above objective, according to one aspect of this disclosure, the microphone device comprises a microphone, a case for housing the microphone, a cushion disposed between the microphone and the case, and a cover that holds the cushion in place and secures it to the case. The cushion comprises a cylindrical inner circumference that contacts the microphone and an outer circumference that is held in place by the cover. With the x-direction being the direction parallel to the axis of the inner circumference, the cover holds the outer circumference from one side in the x-direction, and a recess is formed on the surface of one side of the inner circumference.

[0009] According to this, the rigidity of the inner circumference of the cushion is reduced by the recess, so when the outer circumference is pressed by the cover, stress is generated in the inner circumference toward the microphone, making it less likely for foreign matter to enter a gap between the microphone and the cushion. Therefore, the deterioration of the microphone device's characteristics can be suppressed.

[0010] The reference numerals in parentheses attached to each component indicate an example of the correspondence between that component and the specific components described in the embodiments described later.

[0011] This is a perspective view of the microphone device according to the first embodiment. This is a perspective view of the base cushion. This is a cross-sectional view of the base cushion. This is a cross-sectional view of the microphone, base cushion, and cover. This is a cross-sectional view of a comparative example. This is a cross-sectional view showing a gap between the microphone and the base cushion in the comparative example. This is a perspective view of the base cushion in the second embodiment. This is a cross-sectional view of the base cushion in the second embodiment. This is a perspective view of the base cushion in the third embodiment. This is a cross-sectional view of the base cushion in the third embodiment.

[0012] The embodiments of this disclosure will be described below with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be denoted by the same reference numerals.

[0013] (First Embodiment) The first embodiment will be described. In this embodiment, the microphone device 1 shown in Figure 1 is mounted on a vehicle and used as an ultrasonic sensor that transmits and receives ultrasonic waves. However, the microphone device 1 may only transmit ultrasonic waves, or the microphone device 1 may only receive ultrasonic waves. Furthermore, the microphone device 1 may be mounted on a device other than a vehicle.

[0014] As shown in Figure 1, the microphone device 1 comprises a microphone 10, a case 20, a base cushion 30, a damper 40, a cover 50, a tip cushion 60, a circuit section 70, and a shielding plate 80. Figure 1 illustrates the state of the microphone device 1 before assembly. The assembly direction of the microphone 10, etc., is defined as the x-direction. The microphone 10, etc., is assembled to the case 20 from one side or the other side in the x-direction.

[0015] Microphone 10 transmits and receives ultrasonic waves. Microphone 10 has a piezoelectric element (not shown) inside, which is connected to the circuit unit 70 via a terminal 11 erected on the other side of microphone 10 in the x-direction. When a voltage is applied to microphone 10 from the circuit unit 70, ultrasonic waves are transmitted by the piezoelectric element vibrating in accordance with the applied voltage. When the piezoelectric element receives ultrasonic waves, microphone 10 outputs a signal to the circuit unit 70 corresponding to the received ultrasonic waves. Microphone 10 is arranged to transmit ultrasonic waves to one side in the x-direction and to receive ultrasonic waves arriving from the same side in the x-direction.

[0016] The outer casing of the microphone 10 is made of, for example, aluminum, and is roughly cylindrical in shape. The microphone 10 is positioned so that the axis of the outer casing coincides with a straight line L1 parallel to the x-direction. One side of the microphone 10 in the x-direction is the front, the other side in the x-direction is the back, and the surface connecting the front and back is the side. A recess 12 is formed on the side of the microphone 10, and the microphone 10 is fixed to the base cushion 30 by engaging a protrusion 34, which will be described later, with the recess 12.

[0017] The case 20 houses the microphone 10. The case 20 is made of a resin such as PBT (polybutylene terephthalate). The case 20 comprises a box-shaped base 21 with an internal space and a cylindrical holding portion 22 that protrudes from the base 21 to one side in the x-direction.

[0018] The base portion 21 houses the circuit portion 70. Terminals 23 are located inside the base portion 21, and terminals 23 are connected to the circuit portion 70 via wiring (not shown). A cylindrical connector portion 24 is formed in the base portion 21, and the circuit portion 70 is connected to the vehicle's ECU (Electronic Control Unit), etc., via wiring (not shown) that passes through the inside of the connector portion 24. The holder portion 22 holds the microphone 10, and the microphone 10 is housed inside the holder portion 22.

[0019] A circular frame-shaped base 25 is formed inside the holding portion 22. The holding portion 22 and the base 25 are arranged so that their axes coincide with a straight line L1, and the outer edge of the base 25 is joined to the inner wall surface of the holding portion 22. The microphone 10 is housed in the portion of the holding portion 22 that is on one side in the x-direction relative to the base 25. A protrusion 26 is formed on the outer wall surface of the holding portion 22. The protrusion 26 is the part that engages with the through hole 52, which will be described later.

[0020] The base cushion 30 is for suppressing unwanted vibrations on the side of the microphone 10 and is positioned between the microphone 10 and the case 20. The base cushion 30 is made of an elastic material such as silicone rubber.

[0021] As shown in Figures 1 to 3, the base cushion 30 is substantially cylindrical and positioned so that its axis coincides with the straight line L1. Of the base cushion 30, the cylindrical portion inside the straight line L2 shown in Figure 3 is designated as the inner circumference 31, and the portion outside the straight line L2 is designated as the outer circumference 32. The inner circumference 31 is the part that contacts the microphone 10, and the outer circumference 32 is the part that is pressed against by the cover 50. The axes of the inner circumference 31 and the outer circumference 32 coincide with the straight line L1.

[0022] The opening on the other side of the inner circumference 31 in the x-direction protrudes in part to form a circular frame-shaped base 33. A disc-shaped damper 40 made of an elastic material such as silicone rubber is fitted into a circular through hole formed in the center of the base 33. The damper 40 is for suppressing unwanted vibrations on the back of the microphone 10. The microphone 10 is housed in a space enclosed by the base cushion 30 and the damper 40 such that its back surface abuts against the damper 40 and the base 33, and its sides abut against the inner wall surface 35 of the inner circumference 31.

[0023] As shown in Figure 1, the damper 40 has a through hole 41 that penetrates the damper 40 in the thickness direction, i.e., the x direction. The terminal 11 protrudes from the back surface of the damper 40 to the other side in the x direction through the through hole 41. The terminal 11 is connected to the terminal 23 at this protruding portion.

[0024] As shown in Figure 3, a convex portion 34 is formed on the inner circumference 31 that is located on one side in the x-direction relative to the base 33, projecting radially inward. The microphone 10 is fixed to the base cushion 30 by the engagement of the convex portion 34 and the concave portion 12.

[0025] A recess 36 is formed in the inner wall surface 35 of the inner circumference 31 on one side in the x-direction, specifically in the portion of the inner circumference 31 located on one side in the x-direction from the convex portion 34. As shown in Figure 4, a gap G is formed between the inner wall surface 35 and the outer surface of the microphone 10 by the recess 36. In this embodiment, as shown in Figures 2 and 3, the recess 36 is formed in an annular shape over the entire circumferential direction of the inner circumference 31, thereby forming an annular gap G between the recess 36 and the microphone 10.

[0026] The cover 50 holds down the base cushion 30, fixing the microphone 10 and the base cushion 30 to the case 20. The cover 50 is made of, for example, PBT resin. As shown in Figures 1 and 4, the cover 50 is a substantially cylindrical member with openings on one side and the other side in the x-direction, and the opening end on one side in the x-direction protrudes radially inward to form a frame-shaped portion 51. The cover 50 holds down the outer circumference 32 from one side in the x-direction to the other side at the frame-shaped portion 51.

[0027] As shown in Figure 1, a through hole 52 is formed in the side wall of the cover 50, and the microphone 10 and the base cushion 30 are fixed to the case 20 by the protrusion 26 engaging with the through hole 52.

[0028] As shown in Figure 4, when the microphone device 1 is assembled, a portion of the surface layer on one side in the x-direction of the inner circumference 31 protrudes to the other side in the x-direction from the frame-shaped portion 51. This protruding portion is referred to as the protruding portion 37. The surface on one side in the x-direction of the frame-shaped portion 51 is referred to as the face 53. The recess 36 is formed on the inner circumference 31, extending from the protruding portion 37 to the other side in the x-direction from the face 53. Note that the recess 36 may be formed only on the protruding portion 37. Alternatively, the recess 36 may be formed only on the portion located to the other side in the x-direction from the face 53.

[0029] The sides of the cover 50 are covered by a cylindrical tip cushion 60 made of silicone rubber or the like. The tip cushion 60 is intended to suppress contact between the vehicle body and the cover 50 when assembling the microphone device 1 to the vehicle.

[0030] The circuit unit 70 generates a transmission signal and outputs it to the microphone 10, and processes the received signal from the microphone 10. As shown in Figure 1, the circuit unit 70 includes a substrate 71 made of glass epoxy resin or the like, and components constituting the transmitting and receiving circuit are arranged on one side of the substrate 71 in the x direction. The base 21 is open on the other side in the x direction, and the circuit unit 70 is assembled to the base 21 from the other side in the x direction.

[0031] The other opening in the x-direction of the base portion 21 is covered by a shielding plate 80. The shielding plate 80 blocks electromagnetic waves from the inside and outside of the case 20 and is made of aluminum or the like. The shielding plate 80 has an upright portion 81 erected on one side in the x-direction from its outer edge, and the upright portion 81 engages with the base portion 21 to fix the circuit portion 70 inside the base portion 21 and cover the opening of the base portion 21.

[0032] In the manufacturing process of the microphone device 1, each component is assembled to the case 20 from one side in the x-direction or the other side. Specifically, the damper 40 and the base cushion 30 are placed inside the holding part 22 from one side in the x-direction, the microphone 10 is placed in the space enclosed by the base cushion 30 and the damper 40, and the convex part 34 is engaged with the concave part 12.

[0033] Then, the cover 50 presses down on the base cushion 30 from one side in the x direction, compressing it in the x direction, and engages the protrusion 26 with the through hole 52, thereby fixing the microphone 10 and the base cushion 30 to the holding part 22. In addition, the tip cushion 60 covers the side of the cover 50.

[0034] Furthermore, the circuit section 70 is placed inside the base 21 through the opening on the other side in the x-direction, and the opening of the base 21 is covered with the shield plate 80. In this way, the microphone device 1 is assembled. This assembly process may be performed manually by an operator or by an automated assembly device.

[0035] The effects of this embodiment will now be explained. In the comparative example shown in Figure 5, the base cushion 30 does not have a recess 36. In such a configuration, if the axes of the microphone 10, base cushion 30, and cover 50 are misaligned when the cover 50 is assembled, the outer circumference 32 is pressed and compressed by the cover 50, causing stress in the base cushion 30 in the direction indicated by the white arrow in Figure 5. As shown in Figure 6, a gap may form between the microphone 10 and the tip of the protruding part 37. Such assembly defects may degrade the characteristics of the microphone device 1. In addition, foreign matter may enter the gap in the market environment.

[0036] On the other hand, in this embodiment, the rigidity of the inner circumference 31 is reduced compared to the comparative example due to the recess 36. Therefore, when the outer circumference 32 is pressed against the cover 50, a stress is generated in the inner circumference 31 toward the microphone 10, as shown by the white arrow in Figure 4, and the tip of the protrusion 37 comes into close contact with the microphone 10. Consequently, assembly defects are reduced and the assembled state is stabilized, which suppresses variations in the characteristics of the microphone device 1 and allows for the maintenance of good characteristics. Furthermore, the inclusion of foreign matter can be suppressed.

[0037] Furthermore, when mounting the microphone device 1 on the vehicle's bumper, it is necessary to suppress an increase in the size of the microphone device 1. In this embodiment, by simply changing the shape of the base cushion 30 compared to the comparative example shown in Figure 5, a gap is less likely to occur between the microphone 10 and the tip of the protruding part 37, thereby suppressing an increase in the size of the microphone device 1.

[0038] As described above, in this embodiment, a recess 36 is formed on the surface layer of the inner circumference 31 on one side in the x direction. As a result, the rigidity of the inner circumference 31 is reduced by the recess 36, so when the outer circumference 32 is pressed against the cover 50, stress is generated in the inner circumference 31 toward the microphone 10, making it less likely for foreign matter to enter a gap between the microphone 10 and the base cushion 30. Therefore, the assembled state is stable and a deterioration in the characteristics of the microphone device 1 can be suppressed.

[0039] (Second Embodiment) The second embodiment will now be described. This embodiment is a modification of the configuration of the recess 36 compared to the first embodiment, and is otherwise the same as the first embodiment, so only the parts that differ from the first embodiment will be described.

[0040] As shown in Figures 7 and 8, the recesses 36 in this embodiment are formed on a part of the inner circumference 31 in the circumferential direction. Specifically, multiple recesses 36 are formed and arranged at predetermined intervals in the circumferential direction of the inner circumference 31. This reduces the size of the void G, thereby suppressing the ingress of foreign matter into the void G.

[0041] This embodiment, with the same configuration and operation as the first embodiment, can obtain the same effects as the first embodiment.

[0042] Furthermore, according to the above embodiment, the following effects can be obtained.

[0043] (1) The recess 36 is formed in a part of the inner circumference 31 in the circumferential direction. This makes it possible to suppress the ingress of foreign matter into the void G.

[0044] (Third Embodiment) The third embodiment will be described. This embodiment is different from the first embodiment in the configuration of the recess 36, and the rest is the same as the first embodiment. Therefore, only the differences from the first embodiment will be described.

[0045] As shown in FIGS. 9 and 10, the recess 36 of this embodiment is formed on the outer wall surface 38 of the protruding portion 37. As a result, the protruding portion 37 is thin-walled and has reduced rigidity. Even in this embodiment where the recess 36 is formed at such a position, when the outer peripheral portion 32 is pressed by the cover 50, a stress directed toward the microphone 10 side is generated in the protruding portion 37.

[0046] This embodiment can obtain the same effects as the first embodiment from the same configuration and operation as the first embodiment.

[0047] (Other Embodiments) Note that the present disclosure is not limited to the above-described embodiments, and can be appropriately modified. Also, the above embodiments are not unrelated to each other, and can be appropriately combined except when the combination is clearly impossible. Further, in each of the above embodiments, the elements constituting the embodiment are not necessarily essential, except when it is explicitly stated that they are essential or when they are considered to be clearly essential in principle. Also, in each of the above embodiments, when referring to the shape, positional relationship, etc. of the components, etc., it is not limited to that shape, positional relationship, etc., except when it is explicitly stated or when it is limited to a specific shape, positional relationship, etc. in principle.

[0048] For example, the recess 36 may be formed on both the inner wall surface 35 and the outer wall surface 38. Also, the recess 36 formed on the outer wall surface 38 may be divided into a plurality of parts.

[0049] (Perspectives of this Disclosure) [First Perspective] A microphone device comprising: a microphone (10); a case (20) for housing the microphone; a cushion (30) disposed between the microphone and the case; and a cover (50) that presses down on the cushion and fixes it to the case, wherein the cushion comprises a cylindrical inner circumference (31) that contacts the microphone and an outer circumference (32) that is pressed down on by the cover, the cover presses down on the outer circumference from one side in the x-direction with respect to the x-direction, and a recess (36) is formed on the surface layer of the inner circumference on that one side. [Second Perspective] The microphone device according to the first perspective, wherein the recess is formed on the inner wall surface (35) of the inner circumference. [Third Perspective] The microphone device according to the first or second perspective, wherein the recess is formed over the entire circumferential direction of the inner circumference. [Fourth viewpoint] The microphone device according to the first or second viewpoint, wherein the recess is formed in a part of the inner circumference in the circumferential direction. [Fifth viewpoint] The microphone device according to the fourth viewpoint, wherein a plurality of recesses are formed at predetermined intervals in the circumferential direction of the inner circumference. [Sixth viewpoint] The microphone device according to any one of the first to fifth viewpoints, wherein the recess is formed on the outer wall surface (38) of the inner circumference. [Seventh viewpoint] The microphone device according to any one of the first to sixth viewpoints, wherein a part of the surface layer protrudes from the cover to one side, and the recess is formed on the protruding portion.

Claims

1. A microphone device comprising: a microphone (10); a case (20) for housing the microphone; a cushion (30) disposed between the microphone and the case; and a cover (50) that presses down on the cushion and fixes it to the case, wherein the cushion comprises a cylindrical inner circumference (31) that contacts the microphone and an outer circumference (32) that is pressed down on by the cover, the cover presses down on the outer circumference from one side in the x-direction with the x-direction parallel to the axis of the inner circumference, and a recess (36) is formed on the surface layer of the one side of the inner circumference.

2. The microphone device according to claim 1, wherein the recess is formed on the inner wall surface (35) of the inner circumference.

3. The microphone device according to claim 1, wherein the recess is formed over the entire circumferential portion of the inner circumference.

4. The microphone device according to claim 1, wherein the recess is formed in a part of the inner circumference in the circumferential direction.

5. The microphone device according to claim 4, wherein the recesses are formed in a plurality at predetermined intervals in the circumferential direction of the inner circumference.

6. The microphone device according to claim 1, wherein the recess is formed on the outer wall surface (38) of the inner circumference.

7. The microphone device according to claim 1, wherein a portion of the surface layer protrudes from the cover to one side, and the recess is formed in the protruding portion.

Images