JP2013110581A - Microphone device and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microphone device capable of reducing its assembly time and widen its sound detectable area (range of directivity) by delaying an acoustic wave on a sound channel relative to another one.SOLUTION: A MEMS microphone 10 (microphone device) comprises: a vibration part 14 including a diaphragm 141 vibrated by an acoustic wave, for converting the acoustic wave into an electric signal according to the vibration of the diaphragm 141; a first acoustic channel 171 accommodating therein the vibration part 14, for conducting an acoustic wave to a lower surface of the diaphragm 141; and a microphone housing 17 including a second acoustic channel 172, for conducting an acoustic wave to an upper surface of the diaphragm 141. The first acoustic channel 171 has an acoustic wave delaying part 121a formed thereon for delaying an acoustic wave relative to the second acoustic channel 172 by narrowing an acoustic channel cross section, which is perpendicular to a traveling direction of the acoustic wave.

Description

  The present invention relates to a microphone device and an electronic device, and more particularly to a microphone device and an electronic device in which a sound path for guiding a sound wave is formed.

  Conventionally, a microphone device in which a sound path for guiding a sound wave is formed is known (see, for example, Patent Document 1).

  Patent Document 1 includes a microphone (vibration unit) and a housing (housing) for housing the microphone, a first sound introduction space (first sound path) for guiding sound waves to the front surface of the microphone, and the rear surface of the microphone. There is disclosed a microphone device in which a second sound introduction space (second sound path) for guiding sound waves is formed. In this microphone device, an acoustic resistance material made of foamed resin that delays sound waves with respect to the first sound guide space is provided in the second sound guide space, thereby widening the range in which sound can be detected (directivity range). ing. Further, in the microphone device of Patent Document 1, the acoustic resistance material is incorporated into the second sound introduction space while the acoustic resistance material is sandwiched between the front housing and the rear housing constituting the housing.

JP 2005-295278 A

  However, in the microphone device disclosed in Patent Document 1, it is possible to widen the range (directivity range) in which sound can be detected by delaying the sound wave in the second sound introduction space (second sound path) by the acoustic resistance material. On the other hand, since it is necessary to incorporate the acoustic resistance material made of foamed resin into the second sound guide space while being sandwiched between the front housing and the rear housing, there is a problem that it takes time when assembling the microphone device.

  The present invention has been made to solve the above-described problems, and one object of the present invention is to delay the sound wave of one sound path with respect to the other while reducing the time and effort during assembly. It is an object of the present invention to provide a microphone device and an electronic device that can expand the range in which sound can be detected (directivity range).

  A microphone device according to a first aspect of the present invention includes a vibration plate that vibrates with sound waves, and includes a vibration unit that converts sound waves into an electrical signal based on vibrations of the vibration plate, a vibration unit that is housed therein, and a vibration plate. And a housing including a second sound path for guiding sound waves to the other surface of the diaphragm, and one of the first sound path and the second sound path is provided on one of the first sound path and the second sound path. A sound wave delay unit is formed for reducing the cross section of the sound path substantially orthogonal to the traveling direction of the sound wave and delaying the sound wave with respect to the other.

  In the microphone device according to the first aspect of the present invention, as described above, the cross-section of the sound path that is substantially perpendicular to the traveling direction of the sound wave is reduced in one of the first sound path and the second sound path, and the other. By forming a sound wave delay unit that delays the sound wave, the sound wave delay unit delays one sound wave of the first sound path and the second sound path to reach one surface of the diaphragm and the other surface. Since the sound pressure difference with the sound wave to be generated can be easily generated, the range in which sound can be detected (the range of directivity) can be expanded. It should be noted that by delaying one sound wave of the first and second sound paths with respect to the other, the range in which sound can be detected (the range of directivity) can be expanded. Confirmed by simulation. Moreover, since only one sound wave of the first sound path and the second sound path can be delayed with respect to the other only by forming a sound wave delay part that reduces the cross section of one of the first sound path and the second sound path. When assembling the microphone device, as compared with the case where an acoustic resistance material made of foamed resin that delays one sound wave of the first sound path and the second sound path with respect to the other is incorporated in the sound path while being sandwiched between cases Can be reduced. Therefore, in this microphone device, the range in which sound can be detected by delaying the sound wave of one of the first and second sound paths with respect to the other while reducing the time and labor when assembling the microphone device ( The range of directivity) can be expanded.

  In the microphone device according to the first aspect, the sound wave delay unit preferably delays the sound wave relative to the other by locally reducing the cross section of one of the first sound path and the second sound path. It is configured to let you. If comprised in this way, one sound wave of a 1st sound path and a 2nd sound path can be easily delayed with respect to the other by a sound wave delay part.

  In this case, preferably, the sound wave delay unit delays the sound wave by 30 μs or more and 50 μs or less with respect to the other by locally reducing the cross section of one of the first sound path and the second sound path. It is configured as follows. If configured in this way, the directivity of the microphone device can be set between the directivity and the omnidirectionality, so that the effect of the bidirectionality is maintained while being close to the omnidirectionality. Can do. Thereby, it can suppress that noise suppression performance falls, extending the range (directivity range) which can detect sound. In addition, by setting the delay amount to 30 μs or more and 50 μs or less, the directivity of the microphone device can be made to be a directivity between the bidirectionality and the omnidirectionality, and the directivity of the microphone device is bidirectional. As described later, it is possible to suppress the noise suppression performance from deteriorating while expanding the range (directivity range) in which sound can be detected by setting the directivity between directivity and omnidirectionality. It has been confirmed by the simulation of the present inventor.

In the configuration in which the sound wave is delayed by 30 μs or more and 50 μs or less, it is preferable that the sound wave delay unit locally 1.9 × 10 ⁻⁹ m of a cross section of one of the first and second sound paths. By setting the magnitude to ² or more and 18 × 10 ⁻⁹ m ² or less, the sound wave is delayed by 30 μsec or more and 50 μsec or less with respect to the other. With this configuration, the sound wave delay unit can easily delay one sound wave of the first sound path and the second sound path from 30 μs to 50 μs with respect to the other. As a result, the directivity of the microphone device can be easily set to a directivity between the bidirectionality and the omnidirectionality.

In the configuration in which the cross section of the sound path has a size of 1.9 × 10 ⁻⁹ m ² or more and 18 × 10 ⁻⁹ m ² or less, preferably, the sound wave delay unit has a length in the traveling direction of the sound wave of 20 μm or more. It is formed to be 100 μm or less. If comprised in this way, the sound wave delay part can delay more easily 30 to 50 microseconds of one sound wave of a 1st sound path and a 2nd sound path with respect to the other.

In the configuration in which the cross section of the sound path is set to a size of 1.9 × 10 ⁻⁹ m ² or more and 18 × 10 ⁻⁹ m ² or less, preferably, a sound wave is selected from one of the first sound path and the second sound path. The cross section of the sound path that is substantially orthogonal to the traveling direction of the sound wave between the position other than the position where the delay portion is provided and the other of the first sound path and the second sound path is 70 × 10 ⁻⁹ m ² or more. The sound wave delay unit locally has a cross-section of one of the first and second sound paths of 1.9 × 10 ⁻⁹ m ^{2 to} 18 × 10 ⁻⁹ m ^2. It is configured to be small. If comprised in this way, since it can suppress that a sound wave delays in locations other than the location in which the sound wave delay part was formed, the sound wave delay part ensures the sound wave of one sound path with respect to the other. It can be delayed from 30 μsec to 50 μsec.

  In the microphone device according to the first aspect, preferably, the vibration unit further includes a fixed electrode disposed so as to face the other surface of the vibration plate, and the vibration plate and the fixed electrode are caused by vibration of the vibration plate. The sound wave is converted into an electric signal by changing the distance between the sound wave and the sound wave delay unit, and the sound wave delay unit is provided in the first sound path that guides the sound wave to one surface of the diaphragm. If comprised in this way, while it can suppress that the dust etc. which penetrate | invade from the outside via a 2nd sound path reach the other surface of a diaphragm with a fixed electrode, while reducing the cross section of the sound path The sound wave delay unit can suppress dust or the like entering from the outside via the first sound path from reaching one surface of the diaphragm. Thereby, since it can suppress that dust adheres to one and the other both surfaces of a diaphragm, it can suppress that the sensitivity of a vibration part falls due to adhesion of dust.

  In the microphone device according to the first aspect, preferably, the housing includes a base substrate on which the vibration unit is mounted, and a cover substrate provided so as to cover the vibration unit, and the sound wave delay unit is the base substrate or the cover. Formed on the substrate. If comprised in this way, unlike the case where a sound wave delay part is formed separately from a base substrate and a cover substrate, the increase in a number of parts can be suppressed.

  In the microphone device according to the first aspect, preferably, the housing includes a base substrate on which the vibration unit is mounted, and a cover substrate provided so as to cover the vibration unit, and the surface of the base substrate or the cover substrate is provided on the surface. A plate-like sound wave delay member having a sound wave delay part is attached. If comprised in this way, even when providing the exclusive sound wave delay member which has a sound wave delay part, only the sound wave of one of the 1st sound path and the 2nd sound path can be easily done only by sticking on the surface of a base board or a cover board. Since it can be delayed with respect to the other, it is possible to suppress troublesome work during assembly of the microphone device.

  The microphone device according to the first aspect is preferably configured to have a directivity between both directivity and omnidirectionality by delaying the sound wave by the sound wave delay unit. If comprised in this way, the microphone apparatus which can suppress that noise suppression performance falls while expanding the range (directivity range) which can detect sound can be obtained.

  In the microphone device according to the first aspect, preferably, when the sound source is located at a long distance, the directivity between the bidirectionality and the omnidirectionality is more than the case where the sound source is located at a short distance. It is configured to have directivity close to both directions. By configuring in this way, it is possible to detect a wider range of sounds by approaching omnidirectionality for short-distance sound sources, and for short-distance sound sources. Noise suppression performance can be improved by being closer to the bidirectionality than the case.

  An electronic device according to a second aspect of the present invention is an electronic device including a microphone device, and the microphone device includes a vibration plate that vibrates by sound waves, and vibrations that convert sound waves into electrical signals based on vibrations of the vibration plates. And a microphone housing that houses the vibration unit therein, and communicates from the outer surface of the electronic device and guides sound waves to one surface of the diaphragm, and communicates from the outer surface of the electronic device and vibrates. A second sound path for guiding sound waves to the other surface of the plate is formed, and one of the first sound path and the second sound path has a smaller cross section of the sound path that is substantially orthogonal to the traveling direction of the sound waves. A sound wave delay unit that delays the sound wave with respect to the other is formed.

  In the electronic device according to the second aspect of the present invention, as described above, the cross section of the sound path that is substantially orthogonal to the traveling direction of the sound wave is reduced in one of the first sound path and the second sound path, and the other. By forming a sound wave delay unit that delays the sound wave, the sound wave delay unit delays one sound wave of the first sound path and the second sound path to reach one surface of the diaphragm and the other surface. Since the sound pressure difference with the sound wave to be generated can be easily generated, the range in which sound can be detected (the range of directivity) can be expanded. It should be noted that by delaying one sound wave of the first and second sound paths with respect to the other, the range in which sound can be detected (the range of directivity) can be expanded. Confirmed by simulation. Moreover, since only one sound wave of the first sound path and the second sound path can be delayed with respect to the other only by forming a sound wave delay part that reduces the cross section of one of the first sound path and the second sound path. Compared to the case where an acoustic resistance material made of foamed resin that delays one sound wave of the first sound path and the second sound path with respect to the other is inserted into the sound path while being sandwiched between microphone housings, it is troublesome during assembly. Can be reduced. Therefore, in this electronic device, the range in which sound can be detected by delaying the sound wave of one of the first sound path and the second sound path relative to the other (reducing the directivity) Range).

  According to the present invention, as described above, a range in which sound can be detected by delaying the sound wave of one of the first and second sound paths with respect to the other while reducing the time and effort during assembly. (Directivity range) can be expanded.

It is the top view which showed the whole structure of the mobile telephone by 1st Embodiment of this invention. It is the whole perspective view seen from the upper part of the MEMS microphone by a 1st embodiment of the present invention. It is the whole perspective view seen from the lower part of the MEMS microphone by a 1st embodiment of the present invention. It is the disassembled perspective view which showed the whole structure of the MEMS microphone by 1st Embodiment of this invention. It is sectional drawing which showed the MEMS microphone by 1st Embodiment of this invention. It is the top view which showed the 1st board | substrate layer of the MEMS microphone by 1st Embodiment of this invention. It is the top view which showed the 2nd board | substrate layer of the MEMS microphone by 1st Embodiment of this invention. It is the expanded sectional view which showed the sound wave delay part of the MEMS microphone by 1st Embodiment of this invention. It is the simulation result which showed the relationship between the delay amount and directivity pattern when a sound source is located at a short distance. It is the figure which showed the simulation result of the relationship between the amount of delay and directivity pattern when a sound source is located in a long distance. It is the figure which showed the actual measurement result of the relationship between a frequency and a sensitivity at the time of outputting white noise from a long-distance sound source. It is the figure which showed the simulation result of the relationship between the opening diameter of a sound wave delay part, and delay amount. It is the figure which showed the simulation result of the relationship between the aperture diameter of a sound wave delay part, and a gain. It is a figure for demonstrating the directivity pattern of a differential microphone. It is the figure which looked at the state where the user held the electronic device close to the ear and beside the face from the front. It is the figure which looked at the state where the user held the electronic device close to the ear and beside the face from the side. It is the figure which showed the state in which the user held the electronic device in front of the face. It is sectional drawing which showed the MEMS microphone by 2nd Embodiment of this invention. It is sectional drawing which showed the MEMS microphone by 3rd Embodiment of this invention. It is sectional drawing for demonstrating the manufacturing procedure of the MEMS microphone by 3rd Embodiment of this invention. It is a top view for demonstrating the manufacturing procedure of the MEMS microphone by 3rd Embodiment of this invention. It is sectional drawing which showed the MEMS microphone by 4th Embodiment of this invention. It is sectional drawing which showed the MEMS microphone by the 1st modification of 2nd Embodiment of this invention. It is the top view which showed the 2nd board | substrate layer of the MEMS microphone by the 2nd modification of 2nd Embodiment of this invention. It is sectional drawing which showed the MEMS microphone by the modification of 3rd Embodiment of this invention. It is sectional drawing which showed the MEMS microphone by the 1st modification of 4th Embodiment of this invention. It is sectional drawing which showed the MEMS microphone by the 2nd modification of 4th Embodiment of this invention. It is sectional drawing which showed the MEMS microphone by the 3rd modification of 4th Embodiment of this invention. It is sectional drawing which showed the electronic device by the 1st modification of 1st-4th embodiment of this invention. It is sectional drawing which showed the MEMS microphone by the 2nd modification of 1st-4th embodiment of this invention. It is sectional drawing which showed the MEMS microphone by the 3rd modification of 1st-4th embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
With reference to FIGS. 1-8, the structure of the mobile telephone 100 by 1st Embodiment of this invention is demonstrated. The mobile phone 100 is an example of the “electronic device” in the present invention.

  As shown in FIG. 1, the mobile phone 100 according to the first embodiment of the present invention includes a display unit 1 and a housing 2 having an opening 2 a that exposes the display unit 1. In addition, a mounting substrate 3 on which a MEMS (Micro Electro Mechanical Systems) microphone 10 is mounted is provided inside the housing 2. The MEMS microphone 10 is an example of the “microphone device” in the present invention.

  As shown in FIGS. 2 to 4, the MEMS microphone 10 includes a shield 11, a cover substrate 12, and a base substrate 13. Further, as shown in FIG. 4, a vibration part 14, a circuit part 15, and a chip capacitor 16 are mounted on the base substrate 13 of the MEMS microphone 10. Further, the cover substrate 12 and the base substrate 13 constitute a microphone housing 17 of the MEMS microphone 10 that houses the vibration unit 14, the circuit unit 15, and the chip capacitor 16. The microphone casing 17 is an example of the “casing” and “microphone casing” in the present invention. The MEMS microphone 10 is configured to function as a differential microphone by transmitting sound waves to the vibration unit 14 via two sound paths (first sound path 171 and second sound path 172). The MEMS microphone 10 of the first embodiment has a length of about 7 mm (length in the X direction), a width of about 4 mm (length in the Y direction), and a thickness of about 1.2 mm (Z direction), for example. Length).

The shield 11 is configured to cover the microphone casing 17 from the cover substrate 12 side. The shield 11 is made of metal (for example, nickel silver (white and white)) and is provided to prevent electrical noise. Further, as shown in FIGS. 2 and 4, two sound holes 111 and 112 are formed in the upper surface portion 11 a of the shield 11. The two sound holes 111 and 112 are formed so as to penetrate the upper surface portion 11a of the shield 11 in the vertical direction (Z direction). The sound holes 111 and 112 are formed in a track shape (oval shape) having a longitudinal direction of about 2.65 mm and a short side direction of about 0.6 mm in plan view. The sound holes 111 and 112 have a cross-sectional area (opening area) of about 1.5 × 10 ⁻⁶ m ² in a direction perpendicular to the traveling direction (Z direction) of the sound wave. The sound holes 111 and 112 are spaced apart from each other in the X direction. Further, as shown in FIG. 3, the shield 11 has a holding portion 113 that holds the microphone casing 17 from the lower side (Z2 direction side). The holding part 113 is configured to hold the base substrate 13 from below by being caulked.

The cover substrate 12 is formed of a glass epoxy resin such as FR-4 (Frame Regentant Type 4). Further, as shown in FIG. 4, the cover substrate 12 is arranged at a position sandwiched between the shield 11 and the base substrate 13. Further, as shown in FIGS. 4 and 5, the cover substrate 12 is formed with two sound holes 121 and 122 corresponding to the two sound holes 111 and 112 of the shield 11, respectively. Further, the cover substrate 12 is formed with a recess 123 that accommodates the vibrating portion 14, the circuit portion 15, and the chip capacitor 16. The cover substrate 12 is provided so as to cover the vibration part 14 and the like. In addition, the sound hole 122 and the recess 123 are connected to each other. The sound hole 121 is formed so as to penetrate the cover substrate 12 in the vertical direction (Z direction). The sound holes 121 and 122 are formed in a track shape having a longitudinal direction of about 2.65 mm and a short side direction of about 0.6 mm in plan view. The sound holes 121 and 122 have a cross-sectional area (opening area) of about 1.5 × 10 ⁻⁶ m ² in a direction perpendicular to the traveling direction (Z direction) of sound waves. Further, in the first embodiment, the sound holes 121 and 122 are arranged with an interval (for example, an interval of 5.0 mm) in the X direction.

  As shown in FIGS. 2, 4, and 5, the cover substrate 12 is formed with a sound wave delay part 121 a made up of a very small hole that delays a sound wave passing through the sound hole 121. As shown in FIG. 5, the sound wave delay part 121 a made up of extremely small holes is formed on the cover substrate 12. Moreover, the sound wave delay part 121a has a small circular cross section orthogonal to the traveling direction (Z direction) of the sound wave in the sound hole 121. The sound wave delay unit 121 a is disposed at the upper end of the sound hole 121. Details of the sound wave delay unit 121a will be described later.

  Similarly to the cover substrate 12, the base substrate 13 is formed of a glass epoxy resin such as FR-4. As a result, the thermal expansion coefficients of the cover substrate 12 and the base substrate 13 can be matched, so that when the MEMS microphone 10 is reflow-mounted, they are separated from each other due to the difference between the thermal expansion coefficients of the two. It is possible to prevent. As shown in FIGS. 2 to 5, the base substrate 13 has a three-layer structure including a first substrate layer 131, a second substrate layer 132, and a third substrate layer 133. Specifically, the first substrate layer 131, the second substrate layer 132, and the third substrate layer 133 are bonded together by an adhesive sheet (not shown).

  As shown in FIGS. 4 to 6, the first substrate layer 131 has a track-shaped (oval-shaped) sound hole 131 a corresponding to the sound hole 121 of the cover substrate 12, and a space in the X direction from the sound hole 131 a. A circular sound hole 131b arranged at a distance is formed. As shown in FIG. 4, a bonding pad 131c and a pad 131d are provided on the upper surface (surface on the Z1 direction side) of the first substrate layer 131.

Similar to the sound hole 121 of the cover substrate 12, the sound hole 131a of the first substrate layer 131 has a length of about 2.65 mm in the longitudinal direction and about 0.6 mm in the short direction, and the traveling direction of sound waves ( It has a cross-sectional area (opening area) of about 1.5 × 10 ⁻⁶ m ² in a direction orthogonal to the (Z direction). The sound hole 131b of the first substrate layer 131 has a diameter of about 0.6 mm and a cross-sectional area of about 2.8 × 10 ⁻⁷ m ² in a direction orthogonal to the traveling direction of the sound wave (Z direction) ( Open area). In addition, the sound hole 131b is configured such that the upper side (Z1 direction side) is covered with the vibrating portion 14.

  As shown in FIG. 4, the bonding pad 131c is provided to connect the base substrate 13 and the circuit unit 15 via a bonding wire (not shown). The pad 131d is provided to connect the base substrate 13 and the chip capacitor 16 with solder. Further, the bonding pad 131c and the pad 131d are formed on an electrode pad 133a (see FIG. 3) described later disposed on the lower surface (surface on the Z2 direction side) of the third substrate layer 133 through a circuit pattern and a through hole (not shown). It is connected.

  As shown in FIGS. 4, 5, and 7, the second substrate layer 132 has a hollow portion 132 a that allows the sound holes 131 a and 131 b of the first substrate layer 131 to communicate with each other. As shown in FIG. 7, the hollow portion 132 a is formed in a T shape in plan view.

  As shown in FIG. 3, four electrode pads 133 a are provided on the lower surface (surface on the Z2 direction side) of the third substrate layer 133. The MEMS microphone 10 is soldered and mounted on the mounting board 3 (see FIG. 1) via the electrode pad 133a.

  Here, in the first embodiment, as illustrated in FIG. 5, a diaphragm, which will be described later, of the vibration unit 14 is formed by the sound hole 121 of the cover substrate 12 and the sound hole 131 a, the hollow portion 132 a, and the sound hole 131 b of the base substrate 13. A first sound path 171 for guiding sound waves is formed on the lower surface of 141 (the surface on the Z2 direction side). Further, the sound hole 122 and the concave portion 123 of the cover substrate 12 form a second sound path 172 that guides sound waves to the upper surface (surface on the Z1 direction side) of the diaphragm 141 described later of the vibration unit 14. The first sound path 171 is configured to guide sound waves from the upper side (Z1 direction side) of the cover substrate 12 toward the exposed lower surface of the diaphragm 141. The second sound path 172 is configured to guide sound waves from the upper side (Z1 direction side) of the cover substrate 12 toward the upper surface of the diaphragm 141 through a back plate electrode 142 (to be described later) of the vibration unit 14. .

The sound wave delay part 121 a is formed only in the first sound path 171 of the first sound path 171 and the second sound path 172. In addition, the sound wave delay unit 121a formed of a very small hole locally reduces the cross section orthogonal to the traveling direction of the sound wave of the first sound path 171 (the direction indicated by the broken-line arrow in FIGS. 5 and 8). The sound wave of the sound path 171 is configured to be delayed with respect to the sound wave of the second sound path 172. Specifically, the sound wave delay unit 121a has a small circular cross section orthogonal to the traveling direction (Z direction) of the sound wave of the first sound path 171. As shown in FIG. 8, the cross section reduced by the sound wave delay part 121a has a diameter D of 50 μm or more and 150 μm or less. That is, in the sound wave delay unit 121a formed of a very small hole, a cross section perpendicular to the sound wave traveling direction of the first sound path 171 is locally set to a size of 1.9 × 10 ⁻⁹ m ² or more and 18 × 10 ⁻⁹ m ² or less. It is made small. In addition, the sound wave delay unit 121a has a length (thickness) T of 20 μm or more and 100 μm or less in the traveling direction of the sound wave of the first sound path 171. Moreover, the cross section orthogonal to the advancing direction of a sound wave has a magnitude ^| size of 70 * 10 < ^-9 > m < ² > or more in locations other than the location in which the sound wave delay part 121a of the 1st sound path 171 was provided. Moreover, the cross section orthogonal to the traveling direction of the sound wave of the second sound path 172 also has a size of 70 × 10 ⁻⁹ m ² or more. With such a configuration, the sound wave delay unit 121a can delay the sound wave of the first sound path 171 with respect to the second sound path 172 in the range of 30 μsec to 50 μsec.

  Further, the MEMS microphone 10 has a bi-directionality (nearly eight-shaped directivity pattern) having a Null range in which sound cannot be detected by the sound wave of the first sound path 171 being delayed by the sound wave delay unit 121a. 9 and FIG. 10) and omnidirectionality (circular directional pattern) capable of picking up sound uniformly over the entire range. Further, when the sound source is located at a long distance (for example, a distance of 1 m from the MEMS microphone 10), the MEMS microphone 10 has a short distance (for example, a MEMS) between the bidirectionality and the omnidirectionality. It is configured to have directivity closer to both directions than when located at a distance of 50 mm or less from the microphone 10. In addition, it is clear from the simulation result mentioned later that the MEMS microphone 10 of 1st Embodiment of this invention has the said characteristic.

  As shown in FIGS. 4 and 5, the vibration unit 14 is disposed on the upper surface of the first substrate layer 131 so as to cover the sound hole 131 b of the first substrate layer 131. Further, as shown in FIG. 5, the vibration unit 14 includes a diaphragm 141 that vibrates by sound waves, and a back plate electrode 142 that is disposed so as to face the upper surface of the diaphragm 141 (the surface on the Z1 direction side). Yes. The diaphragm 141 is an example of the “diaphragm” in the present invention, and the back plate electrode 142 is an example of the “fixed electrode” in the present invention. The vibration unit 14 is configured to detect a change in the capacitance of the capacitor formed by the diaphragm 141 and the back plate electrode 142 and convert sound waves into an electrical signal. That is, the vibration unit 14 is configured to convert sound waves into an electric signal by changing the distance between the diaphragm 141 and the back plate electrode 142 due to the vibration of the diaphragm 141. In other words, the vibration unit 14 converts sound waves into electrical signals based on the vibration of the diaphragm 141. Further, the vibration unit 14 is bonded to the upper surface of the base substrate 13 by an adhesive layer (not shown). Further, as shown in FIG. 5, the vibration unit 14 is connected to the circuit unit 15 by a bonding wire 15 a (for example, made of gold). Further, the back plate electrode 142 has a plurality of small through holes having a diameter of several μm, and can transmit sound waves to the diaphragm 141 side. Further, by forming the through-hole with a small diameter of several μm, it is possible to prevent dust larger than that (for example, dust of about several tens of μm) from reaching the diaphragm 141 side.

  As shown in FIGS. 4 and 5, the circuit unit 15 is disposed on the upper surface of the first substrate layer 131. The circuit unit 15 is configured to process the electrical signal output from the vibration unit 14. The circuit unit 15 is bonded to the upper surface of the first substrate layer 131 by an adhesive layer (not shown). The circuit unit 15 is connected to a bonding pad 131c (see FIG. 4) by a bonding wire (for example, made of gold).

  The chip capacitor 16 is disposed on the upper surface of the first substrate layer 131 as shown in FIG. The chip capacitor 16 is soldered to the pad 131d and mounted on the first substrate layer 131.

  In the first embodiment, as described above, in the first sound path 171, the sound wave delay unit 121 a that delays the sound wave with respect to the second sound path 172 by reducing the cross section of the sound path substantially orthogonal to the traveling direction of the sound wave. , The sound wave delay unit 121a delays the sound wave of the first sound path 171 so that the sound pressure difference between the sound wave reaching the lower surface of the diaphragm 141 and the sound wave reaching the upper surface can be easily generated. Can be detected (the range of directivity). In addition, since the sound wave of the first sound path 171 can be delayed with respect to the second sound path 172 simply by forming the sound wave delay unit 121 a that reduces the cross section of the first sound path 171, Compared to the case where an acoustic resistance material made of foamed resin that delays the sound wave with respect to the second sound path 172 is inserted into the sound path while being sandwiched between the microphone casings 17, the labor required for assembling the MEMS microphone 10 is reduced. Can do. Therefore, in this MEMS microphone 10, a range in which sound can be detected by delaying the sound wave of the first sound path 171 with respect to the second sound path 172 while reducing the time and effort at the time of assembling the MEMS microphone 10 (with directivity). Range).

  In the first embodiment, the sound wave delay unit 121 a is configured to delay the sound wave with respect to the second sound path 172 by locally reducing the cross section of the first sound path 171. Accordingly, the sound wave delay unit 121 a can easily delay the sound wave of the first sound path 171 with respect to the second sound path 172.

  In the first embodiment, the sound wave delay unit 121a is configured to delay the sound wave by 30 μs or more and 50 μs or less with respect to the second sound path 172 by locally reducing the cross section of the first sound path 171. To do. Thereby, since the directivity of the MEMS microphone 10 can be a directivity between the bidirectionality and the omnidirectionality, the effect of the bidirectionality can be maintained while approaching the omnidirectionality. Thereby, it can suppress that noise suppression performance falls, extending the range (directivity range) which can detect sound.

In the first embodiment, the second sound path is reduced by locally reducing the cross section of the first sound path 171 to a size of 1.9 × 10 ⁻⁹ m ² or more and 18 × 10 ⁻⁹ m ² or less. The sound wave delay unit 121a is configured to delay the sound wave with respect to 172 by 30 μs or more and 50 μs or less. Thereby, the sound wave delay unit 121a can easily delay the sound wave of the first sound path 171 with respect to the second sound path 172 by 30 μs or more and 50 μs or less. Thereby, the directivity of the MEMS microphone 10 can be easily set to a directivity between the bidirectionality and the omnidirectionality.

  In the first embodiment, the sound wave delay part 121a is formed so that the length in the traveling direction of the sound wave is 20 μm or more and 100 μm or less. Thereby, the sound wave delay unit 121a can more easily delay the sound wave of the first sound path 171 with respect to the second sound path 172 by 30 μs or more and 50 μs or less.

Further, in the first embodiment, the cross section of the sound path that is substantially orthogonal to the traveling direction of the sound wave in the second sound path 172 and the position other than the position where the sound wave delay unit 121a is provided in the first sound path 171, It is formed to have a size of 70 × 10 ⁻⁹ m ² or more, and the cross section of the first sound path 171 is locally 1.9 × 10 ⁻⁹ m ² or more and 18 × 10 ⁻⁹ m ² or less. The sound wave delay unit 121a is configured to be small. Thereby, since it can suppress that a sound wave delays in locations other than the location where the sound wave delay part 121a was formed, the sound wave of the 1st sound path 171 is reliably transmitted by the sound wave delay part 121a to the 2nd sound path 172. Can be delayed from 30 μs to 50 μs.

  In the first embodiment, the back plate electrode 142 having a small-diameter through hole is provided so as to face the upper surface of the diaphragm 141, and the sound wave delay unit 121 a is provided in the first sound path 171 that guides the sound wave to the lower surface of the diaphragm 14. Is provided. Thereby, the small-diameter through-hole of the back plate electrode 142 suppresses large dust (dust of about several tens of μm) entering from the outside via the second sound path 172 from reaching the upper surface of the diaphragm 141. In addition, the sound wave delay unit 121a having a reduced cross section of the first sound path 171 can suppress dust entering from the outside via the first sound path 171 from reaching the lower surface of the diaphragm 141. . Thereby, since it can suppress that dust adheres to both upper and lower surfaces of the diaphragm 141, it can suppress that the sensitivity of the vibration part 14 falls by adhesion of dust.

  In the first embodiment, the sound wave delay part 121 a is formed on the cover substrate 12. Thereby, unlike the case where the sound wave delay part 121a is formed separately from the cover substrate 12, an increase in the number of parts can be suppressed.

  Moreover, in 1st Embodiment, it is comprised so that it may have the directivity between bi-directionality and omnidirectionality by delaying a sound wave with the sound wave delay part 121a. As a result, it is possible to obtain the MEMS microphone 10 capable of suppressing the noise suppression performance from being lowered while expanding the range in which sound can be detected (directivity range). In addition, by reducing the directivity of the microphone device between the directivity and the omnidirectionality, the noise suppression performance is reduced while expanding the sound detectable range (directivity range). It has been confirmed by the inventor's simulation described later that it can be suppressed.

  In the first embodiment, when the sound source is located at a long distance, the directivity between the bidirectionality and the omnidirectionality is closer to the bidirectionality than when the sound source is located at a short distance. It is configured to have directivity. As a result, it is possible to detect a wider range of sound by approaching the omnidirectionality for a short-distance sound source, and both for a long-distance sound source than for a short distance. By approaching directivity, noise suppression performance can be enhanced.

  Next, simulation results and actual measurement results performed on the differential microphone in order to confirm the effect of the first embodiment of the present invention will be described.

  First, with reference to the simulation results shown in FIG. 9 and FIG. 10, the directivity when the sound source is located at a short distance (50 mm) and when the sound source is located at a long distance (1 m) will be described. Regardless of whether the sound source is a short distance or a long distance, if the sound wave of one of the two sound paths is not delayed with respect to the other (when the delay amount is 0 μsec), the directivity of the differential microphone is bi-directional. (Directivity pattern of approximately 8 characters). Moreover, regardless of whether the sound source is a short distance or a long distance, the directivity of the differential microphone gradually approaches the omnidirectional (circular directivity pattern) from the bidirectionality as the delay amount is increased. As a result.

  Further, in the range of the delay amount of 30 μsec or more and 50 μsec or less of the MEMS microphone 10 of the first embodiment, the directivity of the differential microphone is the directivity between the bidirectionality and the omnidirectionality. As a result, it was confirmed that by delaying the sound wave by 30 μs or more and 50 μs or less by the sound wave delay unit, the Null range can be reduced and the sound detectable range (directivity range) can be expanded. Further, from the results shown in FIG. 9, it was confirmed that when the sound source is at a short distance and the delay amount is 30 μsec or more, the fluctuation amount of sensitivity varying depending on the direction can be suppressed to 10 dB or less at the maximum. In other words, if the delay amount is set to 30 μsec or more, it is possible to confirm that sound waves arriving from any direction can be satisfactorily detected with respect to a short-distance sound source while suppressing variation due to the direction of the sound source. It was.

  Further, in the range where the delay amount is not less than 30 μsec and not more than 50 μsec, the near-distance directivity pattern has a more circular shape than the long distance. In other words, in the range where the delay amount is 30 μs or more and 50 μs or less, in the case of a long distance, the directivity closer to the bidirectionality than the short distance is shown between the bidirectionality and the omnidirectionality. . As a result, it was confirmed that noise suppression performance can be ensured if the delay amount is 50 μsec or less. In addition, by delaying the sound wave by 30 μs or more and 50 μs or less by the sound wave delay unit, it is possible to satisfactorily detect a sound wave arriving from any direction with respect to a short-distance sound source by suppressing variation due to the direction of the sound source. In addition, it was confirmed that noise suppression performance can be adequately secured for long-distance sound sources.

  Next, the noise suppression performance was evaluated when the delay amount was 40 μs in the range of 30 μs to 50 μs. The relationship between the frequency and sensitivity when white noise is output from a sound source at a long distance (1 m) will be described with reference to the actual measurement result shown in FIG. In the differential microphone in which the delay amount is set to 40 μsec, the sensitivity is lower by about 15 dB than the normal microphone having no noise suppression performance at any frequency. That is, it was confirmed that the differential microphone with a delay amount of 40 μs has a noise suppression effect of about 15 dB with respect to the normal microphone. As a result, the amount of delay is set to 30 μs or more and 50 μs or less, and the microphone directivity is set to be between bi-directional and omni-directional. It was confirmed that suppression performance can be obtained.

Here, with reference to the simulation result shown in FIG. 12, the relationship between the size (area) of the cross section reduced by the sound wave delay portion of the sound path and the delay amount (μ seconds) will be described. In FIG. 12, when the cross section reduced by the sound wave delay portion is circular, the size of the cross section is indicated by the opening diameter (diameter D in the first embodiment). As shown in FIG. 12, the delay amount decreased with increasing diameter D (area) at any thickness. Further, when the thickness T is in the range of 20 μm or more and 100 μm or less, the diameter D (area) is set to 50 μm (1.9 × 10 ⁻⁹ m ² ) or more and 100 μm (18 × 10 ⁻⁹ m ² ) or less. It was confirmed that the time can be set to 30 μs or more and 50 μs or less.

Next, the relationship between the aperture diameter (diameter D in the first embodiment) and the gain will be described with reference to the simulation result shown in FIG. In the range where the diameter D (area) is about 75 μm (4.4 × 10 ⁻⁹ m ² ) or less, the gain attenuation increases (the gain decreases) as the diameter D (area) decreases. In a range where D (area) is larger than about 75 μm (4.4 × 10 ⁻⁹ m ² ), there was no gain attenuation (gain attenuation was 0). Further, from the simulation results shown in FIG. 13, in order to secure a gain attenuation of −3 (dB) or more (in order to prevent the gain attenuation from becoming larger than −3 (dB)), the diameter D (area) is set. It was confirmed that it should be 50 μm (1.9 × 10 ⁻⁹ m ² ) or more. In general, gain attenuation is in a range where there is no problem as long as it is −3 (dB) or more. As a result, if the cross-sectional size (area) reduced by the sound wave delay portion of the sound path is set to 1.9 × 10 ⁻⁹ m ² or more and 18 × 10 ⁻⁹ m ² or less, gain attenuation is suppressed. It was confirmed that the sound can be detected well and sufficient noise suppression performance can be obtained while expanding the range in which sound can be detected.

  Further, as shown in FIG. 14, the directivity patterns of the differential microphones have the same shape three-dimensionally. That is, the directivity pattern of the differential microphone has the same shape even when the microphone is rotated about a straight line connecting the entrances of the two sound paths. Here, when the user holds an electronic device (for example, a mobile phone) on which the microphone is mounted next to the face close to the ear (see FIGS. 15 and 16), the user looks at the display unit of the electronic device and looks at the face. In both cases (see FIG. 17), the sound source is close, but the positional relationship between the user's mouth (sound source) and the microphone is different. For this reason, when a microphone mounted on an electronic device has bi-directionality, if a microphone is arranged so that sound detection is good in one way, the sound source is in the Null range in the other way. The sound may not be detected properly. In addition, when the user holds the side of the face close to the ear, as shown in FIG. 15, the microphone is rotated in a direction away from the user's face (lateral direction), or as shown in FIG. When the microphone is rotated in the front-rear direction, the microphone having bi-directionality may not be able to detect sound well because the sound source is in the Null range. On the other hand, when the MEMS microphone 10 having the directivity between the bi-directionality and the omnidirectionality is mounted on the mobile phone 100 (electronic device) as in the first embodiment, a short distance is required. Since the range in which sound can be detected with respect to the sound source is widened, sound can be detected well both when the mobile phone 100 is held beside the face and when it is held in front of the face. Further, as shown in FIGS. 15 and 16, even when the microphone is rotated in the lateral direction and the front-rear direction, the range in which sound can be detected with respect to a short-distance sound source is widened, so that sound can be detected well. be able to.

(Second Embodiment)
Next, the MEMS microphone 20 of the mobile phone 100 according to the second embodiment of the present invention will be described with reference to FIG. In the second embodiment, unlike the first embodiment, a configuration in which a sound wave delay unit 231a including a very small hole is provided in the base substrate 213 will be described. The MEMS microphone 20 is an example of the “microphone device” in the present invention.

As shown in FIG. 18, the base substrate 213 of the MEMS microphone 20 of the second embodiment is formed in a three-layer structure by a first substrate layer 231, a second substrate layer 132, and a third substrate layer 133. . The first substrate layer 231 is formed with a sound wave delay unit 231a made of a very small hole that delays the sound wave of the first sound path 171. The sound wave delay portion 231 a formed of a very small hole is formed at a position corresponding to the sound hole 121 of the cover substrate 12. The sound wave delay unit 231a has a small circular cross section perpendicular to the sound wave traveling direction (Z direction) of the first sound path 171. The cross section reduced by the sound wave delay portion 231a has a diameter of 50 μm or more and 150 μm or less. That is, in the sound wave delay unit 231a formed of a very small hole, a cross section perpendicular to the sound wave traveling direction of the first sound path 171 is locally set to a size of 1.9 × 10 ⁻⁹ m ² or more and 18 × 10 ⁻⁹ m ² or less. It is made small. The sound wave delay unit 231a is configured to delay the sound wave of the first sound path 171 with respect to the second sound path 172 in a range of 30 μsec or more and 50 μsec or less.

  In addition, the other structure of 2nd Embodiment is the same as that of the said 1st Embodiment.

  In the second embodiment, as described above, the sonic wave delay unit 231a is formed separately from the base substrate 213 by forming the sonic wave delay unit 231a in the first substrate layer 231 of the base substrate 213. An increase in the number of parts can be suppressed.

  As described above, in the configuration of the second embodiment as well, as in the first embodiment, the second sound path 171 is made smaller in cross section of the sound path substantially perpendicular to the traveling direction of the sound wave. By forming the sound wave delay unit 231 a that delays the sound wave with respect to the sound path 172, the sound wave of the first sound path 171 is delayed with respect to the second sound path 172 while reducing the labor for assembling the MEMS microphone 20. By doing so, it is possible to widen the range in which sound can be detected (directivity range).

  The remaining effects of the second embodiment are similar to those of the aforementioned first embodiment.

(Third embodiment)
Next, the MEMS microphone 30 of the mobile phone 100 according to the third embodiment of the present invention will be described with reference to FIG. In the third embodiment, unlike the first embodiment, a configuration in which a sound wave delay member 301 having a sound wave delay part 301a made of a very small hole is provided will be described. The MEMS microphone 30 is an example of the “microphone device” in the present invention.

  As shown in FIG. 19, a sonic wave delay member 301 having a sonic wave delay part 301a made of a very small hole is attached to the cover substrate 12 of the MEMS microphone 30 of the third embodiment. Specifically, the sound wave delay member 301 is attached to the upper surface of the cover substrate 12 with an adhesive layer (not shown). The sonic wave delay member 301 is made of a metal having high heat resistance, polyimide, or the like so that it can cope with high heat during reflow mounting. Preferably, the sound wave delay member 301 is made of polyimide having rigidity close to that of the cover substrate 12 formed of glass epoxy resin such as FR-4. Accordingly, the composite layer (composite) of the sound wave delay member 301 and the cover substrate 12 can be easily cut in a lump in a state where the sound wave delay member 301 is attached to the cover substrate 12. In addition, the sound wave delay member 301 can be easily formed by forming the sound wave delay member 301 from polyimide. If the sonic wave delay member 301 is made of polyimide in this way, labor during manufacturing can be reduced, so that productivity can be improved.

  Here, a manufacturing procedure of the MEMS microphone 30 of the third embodiment will be described. First, as shown in FIG. 20, the vibration unit 14 and the circuit unit 15 are mounted on the base substrate 13. Then, a sound wave delay member 301 is attached to the upper surface of the cover substrate 12 with an adhesive layer (not shown), and the cover substrate 12 is disposed on the base substrate 13 so as to cover the vibration unit 14 and the circuit unit 15. Thereafter, with the dicing films 310 disposed on the upper and lower surfaces, the dicing blades are cut along the cutting lines shown in FIGS. 20 and 21 to be divided into individual MEMS microphones 30. At this time, if the sound wave delay member 301 is made of polyimide, the composite layer (composite) of the sound wave delay member 301 and the cover substrate 12 can be easily cut in a lump.

Further, the sound wave delay portion 301 a of the sound wave delay member 301 is formed at a position corresponding to the sound hole 121 of the cover substrate 12. The sound wave delay unit 301 a has a small circular cross section orthogonal to the traveling direction (Z direction) of the sound wave of the first sound path 171. The cross section reduced by the acoustic wave delay unit 301a has a diameter of 50 μm or more and 150 μm or less. That is, in the sound wave delay unit 301a formed of a very small hole, a cross section orthogonal to the sound wave traveling direction of the first sound path 171 is locally 1.9 × 10 ⁻⁹ m ^{2 to} 18 × 10 ⁻⁹ m ² in size. It is made small. The sound wave delay unit 301a is configured to delay the sound wave of the first sound path 171 with respect to the second sound path 172 in the range of 30 μsec to 50 μsec. The sound wave delay member 301 has a sound hole 301 b having the same shape as the sound hole 122 at a position corresponding to the sound hole 122 of the cover substrate 12. The sound wave delay member 301 of the third embodiment has a thickness of 20 μm or more and 100 μm or less.

  The remaining configuration of the third embodiment is similar to that of the aforementioned first embodiment.

  In the third embodiment, as described above, the sound wave delay member 301 having the sound wave delay part 301a is attached to the upper surface of the cover substrate 12. Accordingly, even when the dedicated sound wave delay member 301 having the sound wave delay part 301 a is provided, the sound wave of the first sound path 171 can be easily delayed with respect to the second sound path 172 simply by being attached to the upper surface of the cover substrate 12. Therefore, it is possible to suppress time and labor when assembling the MEMS microphone 30.

  As described above, also in the configuration of the third embodiment, as in the first embodiment, the second sound path 171 is made to have a smaller cross section of the sound path substantially perpendicular to the traveling direction of the sound wave. By forming the sound wave delay unit 301 a that delays the sound wave with respect to the sound path 172, the sound wave of the first sound path 171 is delayed with respect to the second sound path 172 while reducing the labor for assembling the MEMS microphone 30. By doing so, it is possible to widen the range in which sound can be detected (directivity range).

  The remaining effects of the third embodiment are similar to those of the aforementioned first embodiment.

(Fourth embodiment)
Next, the MEMS microphone 40 of the mobile phone 100 according to the fourth embodiment of the present invention will be described with reference to FIG. In the fourth embodiment, unlike the first embodiment, the first sound path 471 and the second sound path 472 are provided so as to guide sound waves from the lower side (Z2 direction side) of the base substrate 413 to the vibration unit 14. Will be described. The MEMS microphone 40 is an example of the “microphone device” in the present invention.

  In the fourth embodiment, as shown in FIG. 22, the cover substrate 412 and the base substrate 413 constitute a microphone housing 417 of the MEMS microphone 40. The cover substrate 412 is formed with a recess 423 that accommodates the vibration portion 14, the circuit portion 15, and the like. The microphone casing 417 is an example of the “casing” and “microphone casing” in the present invention.

  Similar to the cover substrate 412, the base substrate 413 is formed of a glass epoxy resin such as FR-4. The base substrate 413 is formed in a three-layer structure by a first substrate layer 431, a second substrate layer 432, and a third substrate layer 433. Specifically, the first substrate layer 431, the second substrate layer 432, and the third substrate layer 433 are bonded to each other by an adhesive sheet (not shown).

  The first substrate layer 431 is provided with a track-shaped sound hole 431a and a circular sound hole 431b that is spaced from the sound hole 431a in the X direction. The sound holes 431a and 431b are formed in the same shape as the sound holes 131a and 131b of the first embodiment, respectively. The circular sound hole 431 b is provided at a position corresponding to the vibration part 14.

  Similar to the second substrate layer 132 of the first embodiment, a T-shaped hollow portion 432a is formed in the second substrate layer 432 in plan view. The hollow portion 432a is configured to communicate the sound hole 431b of the first substrate layer 431 and the sound wave delay portion 433a formed of a small hole described later of the third substrate layer 433. The second substrate layer 432 is formed with a sound hole 432b having the same shape as the sound hole 431a so as to correspond to the sound hole 431a of the first substrate layer 431.

The third substrate layer 433 is formed with a sound wave delay portion 433a made up of extremely small holes. In the fourth embodiment, the diaphragm of the vibrating portion 14 is constituted by the sound wave delay portion 433a formed of a very small hole of the third substrate layer 433, the hollow portion 432a of the second substrate layer 432, and the sound hole 431b of the first substrate layer 431. A first sound path 471 for guiding sound waves is formed on the lower surface of 141 (the surface on the Z2 direction side). The sound wave delay unit 433a is configured to locally reduce the cross section perpendicular to the traveling direction of the sound wave of the first sound path 471 to delay the sound wave of the first sound path 471. Specifically, the sound wave delay unit 433a has a small circular cross section orthogonal to the traveling direction (Z direction) of the sound wave of the first sound path 471. The cross section reduced by the sound wave delay unit 433a has a diameter of 50 μm or more and 150 μm or less. That is, in the sound wave delay unit 433a formed of a very small hole, a cross section perpendicular to the sound wave traveling direction of the first sound path 471 is locally 1.9 × 10 ⁻⁹ m ^{2 to} 18 × 10 ⁻⁹ m ^2. It is made small. The sound wave delay unit 433a is configured to delay the sound wave of the first sound path 471 with respect to the second sound path 472 in a range of 30 μsec or more and 50 μsec or less.

  The third substrate layer 433 is formed with a sound hole 433 b having the same shape as the sound hole 432 b so as to correspond to the sound hole 432 b of the second substrate layer 432. In the fourth embodiment, the back plate is formed by the sound hole 433b of the third substrate layer 433, the sound hole 432b of the second substrate layer 432, the sound hole 431a of the first substrate layer 431, and the recess 423 of the cover substrate 412. A second sound path 472 for guiding sound waves to the upper surface (surface on the Z1 direction side) of the diaphragm 141 of the vibration unit 14 via the electrode 142 is formed.

  The remaining configuration of the fourth embodiment is similar to that of the aforementioned first embodiment.

  As described above, also in the configuration of the fourth embodiment in which the first sound path 471 and the second sound path 472 are provided so as to guide the sound wave from the lower side (Z2 direction side) of the base substrate 413 to the vibration unit 14, As in the first embodiment, the first sound path 471 is formed with a sound wave delay unit 433a that delays the sound wave with respect to the second sound path 472 by reducing the cross section of the sound path substantially orthogonal to the traveling direction of the sound wave. Thus, while reducing the labor for assembling the MEMS microphone 40, the sound wave of the first sound path 471 is delayed with respect to the second sound path 472, and the range in which sound can be detected (directivity range) can be expanded. it can.

  The remaining effects of the fourth embodiment are similar to those of the aforementioned first embodiment.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the first to fourth embodiments, the example in which the present invention is applied to the mobile phone as an example of the electronic apparatus of the present invention has been described. However, the present invention is not limited to this. The present invention may be applied to electronic devices other than cellular phones. For example, the present invention may be applied to an electronic device equipped with a microphone device such as a digital camera, a video camera, a voice recorder, a portable information terminal, or a PC (personal computer).

  Moreover, although the sound wave delay part 121a was formed in the upper end part of the sound hole 121 of the cover board | substrate 12 in the said 1st Embodiment, this invention is not limited to this. In the present invention, the sound wave delay portion composed of a very small hole may be formed at the lower end portion of the sound hole of the cover substrate, or may be formed at the center portion of the sound hole.

  Moreover, although the example which provides the sound wave delay part 231a in the position corresponding to the sound hole 121 of the cover board | substrate 12 among the 1st board | substrate layers 231 was shown in the said 2nd Embodiment, this invention is not limited to this. In the present invention, as shown in FIG. 23, in the first substrate layer 231, a sound wave delay part 231b made of a very small hole may be provided at a position corresponding to the vibration part 14.

  Moreover, in the said 2nd Embodiment, although the example which forms the sound wave delay part 231a in the 1st board | substrate layer 231 was shown, this invention is not limited to this. In the present invention, as shown in FIG. 24, a sound wave delay portion 232 a made up of extremely small holes may be formed in the second substrate layer 232. In this case, the sound wave delay portion 232a is configured to locally reduce a partial cross section of the T-shaped hollow portion 232b.

  Moreover, in the said 3rd Embodiment, although the example which affixes the sound wave delay member 301 in which the sound wave delay part 301a was formed on the upper surface of the cover board | substrate 12 was shown, this invention is not limited to this. In the present invention, as shown in FIG. 25, a sound wave delay member 302 having a sound wave delay part 302 a formed of a very small hole may be attached to the lower surface of the cover substrate 12. In this case, the sound wave delay unit 302 a is provided at a position corresponding to the sound hole 121 of the cover substrate 12.

  In the fourth embodiment, in the configuration in which the first sound path 471 and the second sound path 472 are formed so as to guide the sound wave from the lower side (Z2 direction side) of the base substrate 413 to the vibration unit 14, the sound wave delay Although the example which forms the part 433a in the 3rd board | substrate layer 433 was shown, this invention is not limited to this. In the present invention, as shown in FIG. 26, the first substrate layer 431 may be formed with a sound wave delay portion 431c made up of extremely small holes. In this case, the sound wave delay part 431 c is formed at a position corresponding to the vibration part 14.

  In the fourth embodiment, in the configuration in which the first sound path 471 and the second sound path 472 are formed so as to guide the sound wave from the lower side (Z2 direction side) of the base substrate 413 to the vibration unit 14, the sound wave delay Although the example which forms the part 433a in the 3rd board | substrate layer 433 was shown, this invention is not limited to this. In the present invention, a sonic wave delay portion composed of extremely small holes may be formed in the second substrate layer. In this case, similarly to the modification of the second embodiment shown in FIG. 24, the sound wave delay unit is configured to locally reduce a partial cross section of the T-shaped hollow part.

  In the fourth embodiment, in the configuration in which the first sound path 471 and the second sound path 472 are formed so as to guide the sound wave from the lower side (Z2 direction side) of the base substrate 413 to the vibration unit 14, the sound wave delay Although the example which forms the part 433a in the 3rd board | substrate layer 433 was shown, this invention is not limited to this. In the present invention, as shown in FIG. 27, a sound wave delay member 401 having a sound wave delay part 401a formed of a very small hole may be attached to the lower surface of the cover substrate 412. In this case, the sound wave delay unit 401 a is formed at a position corresponding to the vibration unit 14. In addition, as shown in FIG. 28, a sound wave delay member 402 having a sound wave delay part 402a made of extremely small holes may be attached to the lower surface of the third substrate layer 433.

  Moreover, although the said 1st-4th embodiment showed the example which forms a sound wave delay part in the MEMS microphone as a microphone apparatus of this invention, this invention is not limited to this. In the present invention, the sound wave delay unit may be formed at a place other than the microphone device as long as the cross section of the sound path is reduced. For example, as shown in FIG. 29, a mounting substrate 51 on which a MEMS microphone 50 (microphone device) is mounted via an electrode pad 133a is attached to a casing 53 of an electronic device with a gasket 52 interposed therebetween. , The sound wave delay part comprising a very small hole for reducing the cross section perpendicular to the traveling direction of the sound wave of the first sound path 571 among the first sound path 571 and the second sound path 572 communicating from the outer surface of the electronic device to the vibration part 51a may be formed on the mounting substrate 51. In addition, a sound wave delay portion formed of a very small hole may be formed in the gasket 52 or the casing 53 other than the mounting substrate 51. In this case, a range in which sound can be detected by delaying the sound wave of one sound path with respect to the other while reducing the time and effort of assembly without providing a sound wave delay unit composed of a very small hole in the microphone device itself ( An electronic device capable of widening the range of directivity can be obtained.

  In the first to fourth embodiments, the example in which one vibrating unit 14 for functioning as a differential microphone is provided in the MEMS microphone as the microphone device of the present invention. However, the present invention is not limited to this. I can't. In the present invention, as shown in FIG. 30, the microphone device may further be provided with a vibration unit 614 for causing the microphone device to function as an omnidirectional microphone. In this case, both the two vibrating portions 14 and 614 are provided in the concave portion 123 of the cover substrate 12 constituting the second sound path 172. Accordingly, since the sound wave can be guided to the omnidirectional vibration unit 614 via the second sound path 172 in which the sound wave delay unit is not provided, the first sound is transmitted to the omnidirectional vibration unit 614. It is possible to prevent the influence of the sound wave delay part 121a formed on the road 171.

  In addition, when the above two vibration parts are provided, the sound can be detected when the vibration part for the differential microphone is used by switching so that the sound is detected by one of the vibration parts. The noise suppression performance can be ensured while widening the range, and when using the omnidirectional vibration section, both near-field and far-field sounds can be detected over a wide range. As a result, for example, when a user talks with a mobile phone in his / her hand, the noise suppression performance can be ensured while widening the range in which short-distance sounds can be detected using a vibration unit for a differential microphone. Can do. On the other hand, when a user makes a call with a hands-free function or records a conference or the like, it is possible to detect both short-distance and long-distance sounds in a wide range using the omnidirectional vibration unit. .

  Further, in the present invention, for example, as shown in FIG. 31, even if the sound wave delay member 301 has a configuration in which the cross section perpendicular to the sound wave traveling direction of the second sound path 172 is locally reduced, A sound wave delay unit 121b that delays the sound wave further than the second sound path 172 in which the sound wave is delayed by the delay member 301 may be provided in the first sound path 171. At this time, the cross section reduced by the sound wave delay member 301 of the second sound path 172 is a circular cross section having a diameter a, and the cross section reduced by the sound wave delay portion 121b of the first sound path 171 is also a circular cross section having a diameter a. In this case, the length b (thickness) of the sound wave delay unit 121b in the traveling direction of the sound wave is made larger than the thickness of the sound wave delay member 301, and the sound wave of the first sound path 171 is delayed with respect to the second sound path 172. To be configured. That is, in the present invention, the delay amount of the sound wave may be adjusted by adjusting the length (thickness) of the sound wave delay unit in the traveling direction of the sound wave. At this time, if the length (thickness) of the sound wave delay portion is increased, the delay amount is adjusted to be larger.

10, 20, 30, 40, 50 MEMS microphone (microphone device)
12, 412 Cover substrate 13, 213, 413 Base substrate 14 Vibration unit 17, 417 Microphone housing (housing)
51a, 121a, 121b, 231a, 231b, 232a, 301a, 302a, 401a, 402a, 431c, 433b Sound wave delay unit 100 Mobile phone (electronic device)
141 Diaphragm (diaphragm)
142 Back plate electrode (fixed electrode)
171, 471, 571 First sound path 172, 472, 572 Second sound path 301, 302, 401, 402 Sound wave delay member

Claims (12)

A vibration part that vibrates with sound waves, and a vibration part that converts sound waves into electrical signals based on vibrations of the vibration plate;
A housing including the vibration portion therein, a first sound path for guiding sound waves to one surface of the diaphragm, and a second sound path for guiding sound waves to the other surface of the diaphragm. ,
A microphone in which one of the first sound path and the second sound path is formed with a sound wave delay unit that reduces the cross section of the sound path substantially orthogonal to the traveling direction of the sound wave and delays the sound wave with respect to the other. apparatus.   The sound wave delay unit is configured to delay a sound wave relative to the other by locally reducing the cross section of one of the first sound path and the second sound path. Item 2. The microphone device according to Item 1.   The sound wave delay unit is configured to locally reduce the cross section of one of the first sound path and the second sound path so as to delay the sound wave from 30 μs to 50 μs with respect to the other. The microphone device according to claim 2, which is configured. The sound wave delay unit locally has a size of 1.9 × 10 ⁻⁹ m ² or more and 18 × 10 ⁻⁹ m ² or less of the cross section of one of the first and second sound paths. 4. The microphone device according to claim 3, wherein the microphone device is configured to delay the sound wave by 30 μsec or more and 50 μsec or less with respect to the other.   The microphone device according to claim 4, wherein the sound wave delay unit is formed so that a length in a sound wave traveling direction is 20 μm or more and 100 μm or less. Of one of the first sound path and the second sound path, in a traveling direction of sound waves between a position other than the position where the sound wave delay unit is provided and the other of the first sound path and the second sound path. The cross section of the substantially orthogonal sound path has a size of 70 × 10 ⁻⁹ m ² or more,
The sound wave delay unit locally has a size of 1.9 × 10 ⁻⁹ m ² or more and 18 × 10 ⁻⁹ m ² or less of the cross section of one of the first and second sound paths. The microphone device according to claim 4, wherein the microphone device is configured to be made smaller. The vibration unit further includes a fixed electrode disposed so as to face the other surface of the diaphragm, and an interval between the diaphragm and the fixed electrode is changed due to vibration of the diaphragm. Is configured to convert sound waves into electrical signals,
The microphone device according to claim 1, wherein the sound wave delay unit is provided in the first sound path that guides a sound wave to one surface of the diaphragm. The housing includes a base substrate on which the vibration unit is mounted, and a cover substrate provided so as to cover the vibration unit,
The microphone device according to claim 1, wherein the sound wave delay unit is formed on the base substrate or the cover substrate. The housing includes a base substrate on which the vibration unit is mounted, and a cover substrate provided so as to cover the vibration unit,
The microphone device according to any one of claims 1 to 7, wherein a plate-like sound wave delay member having the sound wave delay portion is attached to a surface of the base substrate or the cover substrate.   The microphone device according to any one of claims 1 to 9, wherein the microphone device is configured to have a directivity between both directivity and omnidirectionality by delaying a sound wave by the sound wave delay unit.   When the sound source is located at a long distance, the directivity between the bi-directionality and the omnidirectionality is configured to have a directivity closer to the bi-directional than when the sound source is located at a short distance. The microphone device according to claim 10. An electronic device including a microphone device,
The microphone device includes a vibration plate that vibrates with sound waves, and includes a vibration unit that converts sound waves into an electrical signal based on vibrations of the vibration plate, and a microphone housing that houses the vibration unit therein.
A first sound path that leads from the outer surface of the electronic device and guides a sound wave to one surface of the diaphragm, and a second sound path that leads from the outer surface of the electronic device and guides a sound wave to the other surface of the diaphragm And are formed,
One of the first sound path and the second sound path is formed with a sound wave delay unit that reduces the cross section of the sound path substantially perpendicular to the traveling direction of the sound wave and delays the sound wave with respect to the other. machine.

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