A MEMS optical microphone

Abstract

The application discloses a MEMS optical microphone, comprising: a shell, the shell having an inner cavity and a sound inlet for connecting the inner cavity with the outside; a micro-electro-mechanical module, the micro-electro-mechanical module comprising a diaphragm, the diaphragm being suspended in the inner cavity, a light lobe being formed on the diaphragm, an opening of the light lobe being formed with a light passing gap, a size of the light passing gap being increased or reduced with the size of the sound pressure; a photoelectric module, the photoelectric module comprising an electromagnetic radiation source and a sensor, the electromagnetic radiation source and the sensor being arranged on opposite sides of the diaphragm, a light beam emitted by the electromagnetic radiation source reaching the sensor through the light passing gap; and an integrated circuit module, the integrated circuit module being electrically connected with the photoelectric module. Compared with the prior art, the application has the advantages of high sensitivity, flat frequency response and the like, and provides potential for further improving the performance of the device.

Description

Technical Field

[0001] This invention relates to the field of microphone technology, and in particular to a MEMS optical microphone. Background Technology

[0002] Traditional microphones are based on capacitors. The diaphragm vibrates with the sound waves, and the voltage changes by changing the spacing between the capacitor substrates, thereby achieving sound-to-electric conversion.

[0003] An optical microphone is a relatively new type of microphone. It generally consists of three main modules: an optoelectronic module, an integrated circuit module (ASIC), and a microelectromechanical system (MEMS). The optoelectronic module emits light toward the MEMS module and receives the light reflected by the MEMS module. When sound waves actuate the diaphragm of the MEMS module, the diaphragm vibrates slightly and changes the intensity and phase of the light reflected back to the optoelectronic module. The optoelectronic module converts the intensity and phase signals of the reflected light into electrical signals and sends them to the integrated circuit module, thus realizing the conversion from sound signal to light signal and then to electrical signal.

[0004] With consumers demanding increasingly higher levels of experience, it is necessary to develop a MEMS optical microphone with superior performance. Summary of the Invention

[0005] The purpose of this invention is to provide a MEMS optical microphone to solve the technical problems in the prior art.

[0006] This invention provides a MEMS optical microphone, comprising:

[0007] A housing having an inner cavity and a sound inlet that connects the inner cavity to the outside;

[0008] A microelectromechanical module includes a diaphragm suspended in an inner cavity, and light lobes formed on the diaphragm. When sound pressure is applied, the opening of the light lobes forms a light-passing gap, and the size of the light-passing gap increases or decreases with the magnitude of the sound pressure.

[0009] The optoelectronic module includes an electromagnetic radiation source and a sensor. The electromagnetic radiation source and the sensor are disposed on opposite sides of the diaphragm. The light beam emitted by the electromagnetic radiation source passes through the light-passing gap and reaches the sensor.

[0010] An integrated circuit module is electrically connected to the optoelectronic module.

[0011] In the MEMS optical microphone described above, preferably, the light lobe forms a slit, and when sound pressure is applied, the light-passing gap is formed by widening the slit.

[0012] In the MEMS optical microphone described above, preferably, a plurality of light lobes are disposed on the diaphragm, and when sound pressure is applied, the light-passing gap is formed by the opening of the slits between the light lobes.

[0013] In the MEMS optical microphone described above, preferably, the first end of the light lobe is connected to an anchoring hinge.

[0014] In the MEMS optical microphone described above, preferably, the anchoring hinge is located at the middle of the first end of the light lobe.

[0015] In the MEMS optical microphone described above, preferably, multiple anchoring hinges are provided, and the multiple anchoring hinges are arranged in parallel and spaced apart.

[0016] In the MEMS optical microphone described above, preferably, the electromagnetic radiation source includes a laser or a light-emitting diode, and the sensor includes a photodiode.

[0017] In the MEMS optical microphone described above, preferably, the inner cavity includes a first shell wall, a second shell wall, and a side shell wall connecting the first shell wall and the second shell wall, the first shell wall and the second shell wall are opposite to each other, the microelectromechanical module and the integrated circuit module are disposed on the first shell wall, and the sound inlet is disposed on the first shell wall or the second shell wall.

[0018] In the MEMS optical microphone described above, preferably, multiple sound inlets are provided, and the multiple sound inlets are distributed on the first shell wall or the second shell wall.

[0019] In the MEMS optical microphone described above, preferably, the sound inlet is disposed on the first shell wall, and the microelectromechanical module further includes a support arm, the opposite ends of the support arm being connected to the diaphragm and the first shell wall respectively, so as to suspend the diaphragm in the inner cavity, the diaphragm dividing the inner cavity along the incident direction of the sound wave to form a front cavity and a rear cavity, the front cavity covering the sound inlet.

[0020] Compared with the prior art, the present invention provides one or more light lobes on the diaphragm. When sound pressure is applied, a light-passing gap is formed in the light lobe. The light-passing gap opens and closes in response to the pressure or sound signal applied to the diaphragm, and controls the amount of light transmitted through the light-passing gap. The transmitted light beam is converted into an electrical signal, which corresponds to the applied pressure level of the sound signal. It has the advantages of high sensitivity and flat frequency response, and provides potential for further improving the performance of the device. Attached Figure Description

[0021] Figure 1This is a schematic diagram of the structure of a MEMS optical microphone according to an embodiment of the present invention;

[0022] Figure 2 This is a top view of the first state of the light lobe of the first structure provided in the embodiment of the present invention;

[0023] Figure 3 This is a cross-sectional view of the first state of the optical lobe of the first structure provided in the embodiment of the present invention;

[0024] Figure 4 This is a perspective view of the second state of the light lobe of the first structure provided in the embodiment of the present invention;

[0025] Figure 5 This is a cross-sectional view of the second state of the light lobe of the first structure provided in the embodiment of the present invention;

[0026] Figure 6 This is a top view of the first state of the optical lobe of the second structure provided in the embodiment of the present invention;

[0027] Figure 7 This is a cross-sectional view of the first state of the optical lobe of the second structure provided in the embodiment of the present invention;

[0028] Figure 8 This is a top view of the second state of the light lobe of the second structure provided in the embodiment of the present invention;

[0029] Figure 9 This is a cross-sectional view of the second state of the optical lobe of the second structure provided in the embodiment of the present invention;

[0030] Figure 10 This is a top view of the third state of the light lobe of the second structure provided in the embodiment of the present invention;

[0031] Figure 11 This is a cross-sectional view of the third state of the light lobe of the second structure provided in the embodiment of the present invention;

[0032] Figure 12 This is a top view of the light lobe of the third structure provided in the embodiment of the present invention;

[0033] Figure 13 This is a top view of the light lobe of the fourth structure provided in the embodiment of the present invention.

[0034] Explanation of reference numerals in the attached figures:

[0035] 10-Shell, 11-Sound inlet, 12-First shell wall, 13-Second shell wall, 14-Side shell wall, 15-Inner cavity, 16-Front cavity, 17-Rear cavity;

[0036] 20-Microelectromechanical module, 21-Diaphragm, 22-Hinge area, 23-Optical lobe, 24-Light gap, 25-Support arm, 26-Anchoring hinge;

[0037] 30-Photoelectric module, 31-Electromagnetic radiation source, 32-Sensor, 33-Beam;

[0038] 40 - Integrated circuit module. Detailed Implementation

[0039] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0040] like Figure 1 As shown, an embodiment of the present invention provides a MEMS optical microphone, including a housing 10, a microelectromechanical module 20, an optoelectronic module 30, and an integrated circuit module 40, wherein:

[0041] The housing 10 has an inner cavity 15 and a sound inlet 11 that connects the inner cavity 15 to the outside. In the embodiment provided by the present invention, the inner cavity 15 includes a first housing wall 12, a second housing wall 13, and a side housing wall 14 connecting the first housing wall 12 and the second housing wall 13. The first housing wall 12 and the second housing wall 13 are opposite to each other. The microelectromechanical module 20 and the integrated circuit module 40 are disposed on the first housing wall 12. The sound inlet 11 is opened on the first housing wall 12 or the second housing wall 13. It should be noted that the side housing wall 14 can be integrally formed as part of the first housing wall 12 or the second housing wall 13, or it can be an independent part.

[0042] The microelectromechanical module 20 includes a diaphragm 21 suspended in the inner cavity 15. A hinge region 22 is provided on the diaphragm 21, and an optical lobe 23 is located at the hinge region 22. The first end of the optical lobe 23 is connected to the diaphragm 21 within the hinge region 22, and the second end of the optical lobe 23 is suspended. When sound pressure is applied, a light-passing gap 24 is formed by the movement of the optical lobe 23. The size of the light-passing gap 24 increases or decreases with the magnitude of the sound pressure. In use, sound waves enter the housing 10 through the sound inlet 11 and actuate the optical lobe 23. When the optical lobe 23 vibrates, it moves upward (or downward, depending on the type of microphone) and downward (or upward, depending on the type of microphone), like a standard oscillating structure, with a specific frequency and displacement. The frequency depends on the frequency of the sound wave, and the displacement depends on the pressure of the sound wave.

[0043] In a balanced state without pressure or sound signal, no sound waves enter the sound inlet 11, the light lobe 23 remains in its natural state, and light cannot pass through the light passage gap 24. When a sound wave enters from the sound inlet 11 and actuates the light lobe 23 of the microelectromechanical module 20, the light lobe 23 vibrates slightly and opens, thereby forming the light passage gap 24. The size of the light passage gap 24 changes with the magnitude of the sound pressure, and the amount of light passing through the light passage gap 24 changes accordingly. When the size of the light passage gap 24 is larger, more light passes through; when the size of the light passage gap 24 is smaller, less light passes through.

[0044] The optoelectronic module 30 includes an electromagnetic radiation source 31 and a sensor 32. The electromagnetic radiation source 31 includes, for example, an infrared (IR), visible light, or UV source, which can be a laser or a light-emitting diode. The sensor 32 includes a photodiode. The electromagnetic radiation source 31 and the sensor 32 are disposed on opposite sides of the diaphragm 21. In one feasible embodiment, the electromagnetic radiation source 31 is disposed on the first shell wall 12, and the sensor 32 is disposed on the second shell wall 13, with the electromagnetic radiation source 31 and the sensor 32 positioned directly opposite the light-passing gap 24. The sensor 32 is used to receive electromagnetic radiation from the electromagnetic radiation source 31. The light beam 33 emitted by the light lobe 23 covers the light gap 24. As the light lobe 23 vibrates, the size of the light gap 24 changes accordingly, and the amount of light passing through the light beam 33 also changes synchronously. The light intensity increases with the increase of sound pressure and the size of the light gap 24. The sensor 32 receives this light beam 33, and the change in light intensity generates a photocurrent. This photocurrent corresponds to the level of the applied sound signal, and sends the light signal represented by the photocurrent to the integrated circuit module 40 to realize the conversion from sound signal to light signal and then to electrical signal.

[0045] The integrated circuit module 40 is electrically connected to the optoelectronic module 30 and can also be connected to the microelectromechanical module 20. The integrated circuit module 40 (ASIC) includes electronic circuits that constitute a control or central processing unit and drive, control, and take necessary actions for relevant electronic and optoelectronic components in the system.

[0046] The above embodiment provides a light lobe 23 on the diaphragm 21. When the light lobe 23 vibrates, a light-passing gap 24 is formed inside the light lobe 23. The light-passing gap 24 opens and closes in response to the pressure or sound signal applied to the diaphragm 21, and controls the amount of light transmitted through the light-passing gap 24. The transmitted light beam 33 is converted into an electrical signal, which corresponds to the applied pressure level of the sound signal. It has the advantages of high sensitivity and flat frequency response, and provides potential for further improving the performance of the device.

[0047] Reference Figures 2 to 5 As shown, Figure 2 This is a top view of the first state of the light lobe 23 of the first structure provided in the embodiment of the present invention; Figure 3 This is a cross-sectional view of the first state of the light lobe 23 of the first structure provided in the embodiment of the present invention; Figure 4 This is a perspective view of the second state of the light lobe 23 of the first structure provided in the embodiment of the present invention; Figure 5 This is a cross-sectional view of the second state of the light lobe 23 of the first structure provided by the present invention. In the light lobe 23 of the first structure, there is only a single light lobe 23 in the hinge region 22. The outer contour surface of the light lobe 23 is adapted to the inner contour surface of the hinge region 22. When the light lobe 23 vibrates, the light-passing gap 24 is formed between the outer edge of the light lobe 23 and the inner wall of the hinge region 22. The hinge region is a triangular region, and the corresponding light lobe 23 is also a triangular structure. Those skilled in the art will know that the hinge region 22 can also be set to other shapes, and the shape of the corresponding light lobe 23 will also change accordingly. This is not limited here.

[0048] In a balanced state without pressure or sound signal applied, the light lobe 23 is in the first state, and the light lobe 23 is in a straight line with the diaphragm 21. The light beam 33 emitted by the electromagnetic radiation source 31 cannot pass through. When the sound wave enters from the sound inlet 11, the light lobe 23 is flipped, and the light lobe 23 is in the second state. The light lobe 23 forms a light-passing gap 24 between the hinge regions 22. The light beam 33 emitted by the electromagnetic radiation source 31 passes through the light-passing gap 24 and reaches the sensor 32. The greater the sound pressure, the greater the angle of the light lobe 23 flipping, and the more light beam 33 passes through. The sensor 32 receives this light beam 33, and the change in light intensity generates a photocurrent, which corresponds to the level of the applied sound signal.

[0049] Reference Figures 6 to 11 As shown, Figure 6 This is a top view of the first state of the optical lobe 23 of the second structure provided in the embodiment of the present invention; Figure 7 This is a cross-sectional view of the first state of the optical lobe 23 of the second structure provided in the embodiment of the present invention; Figure 8 This is a top view of the second state of the light lobe 23 of the second structure provided in the embodiment of the present invention; Figure 9 This is a cross-sectional view of the second state of the light lobe 23 of the second structure provided in the embodiment of the present invention; Figure 10 This is a top view of the third state of the light lobe 23 of the second structure provided in the embodiment of the present invention; Figure 11This is a cross-sectional view of the third state of the second structure of the light lobe 23 provided in the embodiment of the present invention. In the second structure of the light lobe 23, multiple light lobes 23 are provided in the hinge region 22. The structure formed by the multiple light lobes 23 is adapted to the shape of the hinge region 22. When sound pressure is applied, the light-passing gap 24 is formed between the outer edges of the multiple light lobes 23. The hinge region 22 is a hexagonal region, and each side of the hexagonal region is connected to a light lobe 23. The light lobe 23 is a triangular structure. The six light lobes 23 together form a hexagonal structure. The outline of this hexagonal structure matches the inner outline of the hexagonal hole.

[0050] In a balanced state without pressure or sound signal, the light lobe 23 is in the first state, and several light lobes 23 will block the hinge area 22, preventing the light beam 33 emitted by the electromagnetic radiation source 31 from passing through. When the sound wave enters from the sound inlet 11 and actuates the light lobe 23 of the microelectromechanical module 20, several light lobes 23 will be flipped, and a light gap 24 will be formed between the outer edges of adjacent light lobes 23. At this time, the light lobe 23 is in the second state, and the light beam 33 emitted by the electromagnetic radiation source 31 passes through the light gap 24 and reaches the sensor 32. The larger the angle of the light lobe 23 flipping, the more light beam 33 passes through. When the light lobe 23 is flipped to the maximum position, the light lobe 23 is in the third state, reaching the limit position detected by the photoelectric module 30, which corresponds to the maximum sound level that the microphone can detect.

[0051] Reference Figure 12 As shown, Figure 12 This is a top view of the third structure of the light lobe 23 provided in the embodiment of the present invention. In the third structure of the light lobe 23, the hinge region 22 is also a hexagonal region, and each side of the hexagonal region is connected to a light lobe 23. The light lobe 23 has a triangular structure, and six light lobes 23 together form a hexagonal structure. The first end of the light lobe 23 is connected to an anchoring hinge 26. The end of the anchoring hinge 26 facing away from the light lobe 23 is connected to the inner wall of the hinge region 22. There is a single anchoring hinge 26, which is located in the middle of the first end of the light lobe 23. This can improve the flexibility of the light lobe 23. When the sound pressure is low, the light lobe 23 can still produce a certain degree of deformation, producing a light-passing gap 24. The light-passing gap 24 can respond to a small degree of deformation of the light lobe 23, so that the amount of light passing through the beam 33 changes.

[0052] Reference Figure 13 As shown, Figure 13This is a top view of the fourth structure of the light lobe 23 provided in the embodiment of the present invention. Unlike the third structure, the fourth structure of the light lobe 23 has multiple anchoring hinges 26 arranged in parallel at intervals. This provides support to keep the light lobe 23 in its balanced position while improving compliance. Maintaining the balanced horizontal position of the light lobe 23 is important because it defines the size of the initial light gap 24 when no sound is applied. The light intensity at this position can serve as a reference when a sound signal is applied. Furthermore, in other embodiments, the light lobe 23 may have other structural, shape, or material modifications to improve compliance, and the diaphragm 21 may have a variable light gap 24 size when a sound signal is applied.

[0053] In the embodiments provided in this application, the size of the light beam 33 is larger than the maximum size of the light-passing gap 24. When the light-passing gap 24 expands to its limit position, its size is at its maximum. At this time, the light-passing gap 24 is still within the coverage area of ​​the light beam 33. If the size of the light beam 33 is smaller than the maximum size of the light-passing gap 24, this will result in the amount of light transmitted through the light beam 33 reaching its maximum value before the light-passing gap 24 has opened to its maximum size. In this case, when the size of the light-passing gap 24 further opens due to changes in the sound signal, for example, when the size of the light-passing gap 24 reaches its maximum size, the amount of light transmitted through the light-passing gap 24 will remain unchanged; therefore, a constant photocurrent is recorded in the sensor 32 for this level of sound signal. This means that even if the size of the light-passing gap 24 can be changed, the sensor 32 will limit the detection of certain levels of sound signals; this will limit the dynamic range of the sensor 32. By setting the size of the beam 33 emitted by the electromagnetic radiation source 31 to be larger than the maximum size of the light gap 24, the dynamic range of the MEMS optical microphone is improved, enabling it to sense a wider range of sound signals and providing higher sensitivity to linear changes in radiation or light intensity caused by sound signals.

[0054] In one feasible implementation, multiple sound inlets 11 are provided, and the multiple sound inlets 11 are distributed in a circumferential array on the first shell wall 12 or the second shell wall 13. These sound inlets 11 can apply uniform pressure to the light lobe 23, improve the vibration stability of the diaphragm 21, and increase the linear range of the optoelectronic module 30.

[0055] Reference Figure 1As shown, the sound inlet 11 is located on the first shell wall 12. The microelectromechanical module 20 also includes a support arm 25. The two ends of the support arm 25 are respectively connected to the diaphragm 21 and the first shell wall 12 to suspend the diaphragm 21 in the inner cavity 15. The diaphragm 21 divides the inner cavity 15 along the incident direction of the sound wave to form a front cavity 16 and a rear cavity 17. The front cavity 16 covers the sound inlet 11. The first shell wall 12 includes a PCB substrate. The front cavity 16 is the volume between the diaphragm 21 and the sound inlet 11. The front cavity 16 is an empty cavity without any components to improve performance. The rear cavity 17 is the volume between the diaphragm 21 and the internal volume of the shell 10. By placing the diaphragm 21 of the microelectromechanical module 20 close to the sound inlet 11, the front cavity 16 is smaller and the rear cavity 17 is larger, which is beneficial for further improving performance.

[0056] In the embodiments provided in this application, the shape of the diaphragm 21 includes a centrally symmetrical pattern. The shape of the diaphragm 21 is not limited to a circle, but can also be a centrally symmetrical pattern such as a square. The diaphragm 21 can be made of a single material or multiple materials. It can be monocrystalline silicon, silicon nitride, silicon oxide, polycrystalline silicon, polyimide, metal, or a combination thereof.

[0057] The light-passing gap 24 is located at the geometric center of the diaphragm 21. The amplitude is the largest at the center of the diaphragm 21. Even a small vibration can cause the size of the light-passing gap 24 to change, thereby affecting the amount of light passing through the beam 33 and improving the sensing accuracy of the sensor 32.

[0058] The above description, based on the embodiments shown in the figures, details the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention, but the present invention is not limited to the scope of implementation shown in the figures. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, that do not exceed the spirit covered by the specification and figures, should be within the protection scope of the present invention.

Claims

1. A MEMS optical microphone, characterized in that, include: The housing has an inner cavity and a plurality of sound inlets that connect the inner cavity to the outside. The inner cavity includes a first shell wall, a second shell wall, and a side shell wall connecting the first shell wall and the second shell wall. The first shell wall and the second shell wall are opposite to each other, and the plurality of sound inlets are arranged in a circumferential array on the first shell wall. A microelectromechanical module (MEMS) includes a diaphragm and a support arm. The diaphragm is suspended in an inner cavity. The opposite ends of the support arm are respectively connected to the diaphragm and a first shell wall to suspend the diaphragm in the inner cavity. The diaphragm divides the inner cavity along the incident direction of the sound wave to form a front cavity and a rear cavity. The front cavity covers the plurality of sound inlets. The diaphragm has a shape that is symmetrical about the center. A light lobe that can move in response to sound pressure is formed on the diaphragm. When sound pressure is applied, the light lobe moves to form a light gap. The size of the light gap increases or decreases with the magnitude of the sound pressure. The light gap is located at the geometric center of the diaphragm. The optoelectronic module includes an electromagnetic radiation source and a sensor. The electromagnetic radiation source and the sensor are disposed on opposite sides of the diaphragm. The electromagnetic radiation source is disposed on the first shell wall and surrounded by the plurality of sound inlets. The sensor is disposed on the second shell wall. The light beam emitted by the electromagnetic radiation source passes through the light-passing gap and reaches the sensor. The amount of light beam reaching the sensor after passing through the light-passing gap changes with the size of the light-passing gap to generate an electrical signal. An integrated circuit module is electrically connected to the optoelectronic module.

2. The MEMS optical microphone according to claim 1, characterized in that, The light lobe forms a slit, and when sound pressure is applied, the light-passing gap is formed by widening the slit.

3. The MEMS optical microphone according to claim 1, characterized in that, Multiple light lobes are disposed on the diaphragm, and when sound pressure is applied, the light-passing gap is formed by the opening of the slits between the light lobes.

4. The MEMS optical microphone according to claim 1, characterized in that, The first end of the light lobe is connected to an anchoring hinge.

5. The MEMS optical microphone according to claim 4, characterized in that, The anchoring hinge is located at the middle of the first end of the light lobe.

6. The MEMS optical microphone according to claim 4, characterized in that, The anchoring hinges are provided in multiple ways, and the multiple anchoring hinges are arranged in parallel and spaced apart.

7. The MEMS optical microphone according to claim 1, characterized in that, The electromagnetic radiation source includes a laser or a light-emitting diode, and the sensor includes a photodiode.

8. The MEMS optical microphone according to claim 1, characterized in that, The microelectromechanical module and the integrated circuit module are disposed on the first shell wall.

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