Microphone system

Abstract

A system is described, comprising a housing, a flexible printed circuit board (PCB), and a sensor. The flexible PCB has a first surface exposed to the environment and a second surface opposite to the first surface. The flexible PCB is mounted to the housing by mounting elements. When sound waves reach the first surface, at least a portion of the flexible PCB vibrates. The sensor is disposed on the second surface of the flexible PCB and is used to measure the vibration of the flexible PCB and output a corresponding electrical signal.

Description

Technical Field

[0001] This application relates to the field of microphones, and more specifically to microelectromechanical systems (MEMS) microphones that can be mounted on vehicles. Background Technology

[0002] MEMS microphones are miniature microphones that can be directly applied to electronic circuit boards. The microphone diaphragm can be etched directly into a silicon wafer. The microphone assembly is then placed on a printed circuit board and protected by a mechanical cover. MEMS microphones can be integrated into many fields, such as the automotive industry.

[0003] One problem with this design is that the microphone needs a sound hole in the mechanical cover through which sound enters and reaches the diaphragm of the MEMS microphone. Such an opening is easily affected by environmental factors such as water, dust, and debris.

[0004] A known solution to this problem is to use a mesh or plastic shield to protect the sound hole. However, in practice, such shields can become clogged with dirt and debris, severely impairing microphone performance and are difficult to clean.

[0005] The inventors aim to provide a system configured for use as a car microphone, wherein the microphone is sensitive enough for speech recognition and resistant to external influences such as water, dust and debris. Summary of the Invention

[0006] The aforementioned objective is achieved through the system of claim 1, particularly by using a flexible PCB as the microphone diaphragm, wherein a MEMS sensor configured to measure the vibration of the flexible PCB diaphragm is directly mounted on the flexible PCB. The surface of the flexible PCB exposed to the environment is empty, while the surface on which the MEMS sensor is mounted is isolated from the environment. Thus, the system is unaffected by environmental impurities. Furthermore, the system is very compact, while maintaining relatively simple and cost-effective overall assembly.

[0007] In one example, this disclosure relates to a system including a housing, a flexible printed circuit board (PCB), and a sensor. The flexible PCB has a first surface exposed to the environment and a second surface opposite to the first surface. The flexible PCB is mounted to the housing by mounting elements. When sound waves reach the first surface, at least a portion of the flexible PCB vibrates. The sensor is disposed on the second surface of the flexible PCB for measuring the vibration of the flexible PCB and outputting a corresponding electrical signal. Attached Figure Description

[0008] The embodiments described herein can be better understood by referring to the following description and accompanying drawings. The components in the drawings are not necessarily to scale, but rather the focus is on illustrating the principles of the embodiments. Furthermore, in the drawings, the same reference numerals indicate corresponding parts. In the drawings:

[0009] Figure 1 A first example of a microphone system based on one or more technologies described herein is shown in a side view.

[0010] Figure 2 The view from above shows what can be used. Figure 1 An example of a flexible PCB for the system.

[0011] Figure 3 The cross-sectional area of ​​a second example of a microphone system according to one or more technologies described herein is shown, (a) a side view without plug elements, (b) a perspective view from below without plug elements, and (c) a perspective view from above with plug elements.

[0012] Figure 4 A third example of a microphone system based on one or more technologies described herein is shown in a side view.

[0013] Figure 5 A fourth example of a microphone system based on one or more technologies described herein is shown in a side view. Detailed Implementation

[0014] Figure 1 An example of a microphone system 100 is shown. The microphone system 100 includes a housing 10, a flexible printed circuit board (PCB) 20, and a sensor 30. A flexible PCB is a PCB that can be bent, folded, or twisted. The housing 10 can be made of any suitable material, such as plastic or metal. In one example, the housing 10 is made of an injection-molded plastic material that can be used in an injection molding machine. In one example, the housing 10 is made of a glass fiber reinforced plastic material. In another example, the housing 10 is made of nylon. Thus, the manufacturing process of the housing is simple and inexpensive. In one example, the housing 10 is made from a single piece. In another example, the housing 10 includes at least two interconnected housing portions. The housing 10 may include at least one opening 110. In one example, the opening 110 may be open at both ends. In another example, the opening 110 may be closed at one end.

[0015] The flexible PCB 20 is mounted to the housing 20 via mounting element 40. The flexible PCB 20 has a first surface 21 that is at least partially exposed to the environment, particularly to sound waves (acoustic waves) emitted in that environment. The first surface 21 may be directly exposed to the environment. In another example, the first surface 21 is separated from the environment by a mesh (not shown) configured to prevent larger impurities from reaching the first surface 21 of the flexible PCB 20. The flexible PCB 20 also includes a second surface 22 opposite to the first surface 21. When sound waves reach the first surface 21, at least a first portion 23 of the flexible PCB 20 vibrates. Therefore, the vibration of the flexible PCB can indicate the incoming acoustic signal. Thus, the first portion 23 of the flexible PCB 20 can act as a microphone diaphragm sensitive to sound waves.

[0016] In one example, a first portion 23 of the flexible PCB 20 is disposed within an opening 110 of the housing 100. In another example, the first portion 23 of the flexible PCB 20 is independent. The first portion 23 is supported by the housing 10 only at at least one end. In another example, the edge of the first portion 23 is attached to the housing 10. Because the first portion 23 of the flexible PCB 20 is independent, it can vibrate in response to external pressure (e.g., sound waves). Therefore, movement of the first portion 23 of the flexible PCB 20 can indicate sound waves in the external environment.

[0017] Sensor 30 is disposed on the second surface 22 of the flexible PCB 20 (i.e., the surface not exposed to the environment) and is used to measure the vibration of the flexible PCB 20 and output a corresponding electrical signal. In one example, sensor 30 is a MEMS accelerometer used to measure the acceleration of the first portion 23 of the flexible PCB 20. Sensor 30 is mounted to the first portion 23 of the flexible PCB 20. In one example, sensor 30 is disposed in the middle of the first portion 23. In one example, sensor 30 is soldered to the second surface 22 of the flexible PCB 20. In one example, sensor 30 outputs an electrical signal to an analysis circuit (…). Figure 1 (Not shown in the diagram), for example, an amplifier circuit. Analysis circuitry can be connected to the vehicle's electronic systems. Sensor 30 can be digital or analog.

[0018] In one example, sensor 30 is a bone conduction sensor, such as an SV01-003 type sensor (analog sensor) or an SDV01-003 type sensor (digital sensor). These sensors are highly sensitive and have a frequency response that makes them suitable for reliable human speech recognition. They also have a high sound-to-noise ratio and are able to effectively shield ambient noise. In addition, they are very compact.

[0019] System 100 can function as a conventional MEMS microphone, where the flexible PCB 20 acts as the microphone's diaphragm. When sound waves reach the flexible PCB 20, it vibrates accordingly. Sensor 30 detects the diaphragm's vibration and transmits an output signal indicating the sound signal to an amplifier circuit. This amplifier circuit can be connected to automotive electronics. Since the flexible PCB 20 itself is the diaphragm, there is no need to create a sound hole for transmitting sound to it. This protects the electronic components of the flexible PCB 20, particularly sensor 30, from moisture, dust, and other impurities in the environment. In one example, system 100 has an IP69 protection rating, indicating that it is completely dustproof and waterproof. This allows it to be directly mounted on automotive surfaces, such as car doors. The microphone is also particularly easy to manufacture because all the necessary components can be housed on a single flexible PCB. In particular, crimping pins can be used to connect the flexible PCB to external components, such as for data exchange or to power the components of the flexible PCB, eliminating the need for any wiring inside the microphone itself.

[0020] In one example, system 100 is implemented in a vehicle. System 100 can be located inside or outside the vehicle. This is possible because the components of system 100 are isolated from the environment. Microphones with sound holes typically become clogged quickly due to the accumulation of impurities, leading to decreased microphone sensitivity and, in the worst case, complete microphone failure. In one example, system 100 is configured to detect the sound of an emergency vehicle on the street and output a corresponding signal to the vehicle's electronic equipment. The vehicle's electronic equipment can then notify the driver of the presence of the emergency vehicle. This improves vehicle safety. In another example, system 100 is configured to detect human voices and output a corresponding signal to the vehicle's electronic equipment, thus triggering vehicle action. The detected human voice may contain commands, and the vehicle's electronic equipment may execute the corresponding commands. System 100 can be located on the outside of the vehicle, such as a door or rearview mirror, and voice commands can be detected even when the vehicle user is outside the vehicle. This improves communication between the user and the vehicle. System 100 is particularly compact and easy to manufacture. In particular, due to the use of a flexible PCB as the diaphragm, mechanical covers are not required, reducing the overall number of components.

[0021] Figure 2 The view from above shows what can be used. Figure 1An example of the flexible PCB 20 of the system. The illustrated side of the flexible PCB 20 is the second surface 22, which is configured to be positioned away from the environment. In the example shown, the flexible PCB 20 includes a first portion 23, a second portion 24, and a third portion 25. The first portion 23 has a circular shape and extends into the elongated second portion 24. The second portion 24 connects the first portion 23 to the third portion 25. The width of the third portion 25 is greater than the width of the second portion 24 to accommodate additional electronic components, such as a rigid PCB 50 (shown in dashed lines). The first portion 23 of the flexible PCB 20 is configured to act as a diaphragm of a microphone, that is, to vibrate in response to sound waves when the flexible PCB 20 is placed in the microphone system 100.

[0022] The flexible PCB 20 includes multiple traces 26 printed on it and configured to interconnect various components disposed on the flexible PCB 20. A sensor 30 (shown in dashed lines) may be disposed on a first portion 23 of the flexible PCB 20. It may be connected to the traces 26 and configured to transmit an output signal to another electronic component via the traces 26. The sensor 30 may be soldered onto the flexible PCB 20.

[0023] In one example, sensor 30 is positioned at the center 31 of the first portion 23, which is the area of ​​greatest stress on the first portion 23. This allows for high-precision and high-sensitivity sensing of vibrations in the flexible PCB 20. However, sensor 30 can be positioned at different locations on the flexible PCB 20. In one example, sensor 30 is positioned at the edge of the first portion 23 of the flexible PCB 20 or on the elongated second portion 24. In yet another example, sensor 30 comprises multiple sensors positioned at different locations on the flexible PCB 20.

[0024] A third portion 25 of the flexible PCB 20 is configured to connect to another electronic component. In one example, the flexible PCB 20 is connected to an amplifier circuit configured to receive an electrical signal from the sensor 30, amplify the signal, and send the amplified signal to the vehicle's control panel. This additional electronic component may also be configured to drive the sensor 20.

[0025] Depending on the required application and the overall microphone design, other configurations of the flexible PCB 20 are also possible. In one example, the flexible PCB 20 consists only of a first portion 23. In one example, the first portion 23 has a circular shape and a diameter of 30 mm. This allows for a very compact arrangement. In another example, the first portion 23 has a polygonal or elliptical shape.

[0026] In the example shown, the flexible PCB 20 has a thickness of 0.11 mm and includes the following stack: a first polyimide layer with a thickness of 25 µm, an adhesive layer with a thickness of 25 µm, a copper layer with a thickness of 35 µm, and a second polyimide layer with a thickness of 25 µm. With this arrangement, the flexible PCB can even detect weak sound waves.

[0027] In one example, a reinforcing ring is provided around the flexible PCB 20. This makes the flexible PCB 20 more impact-resistant.

[0028] The exact shapes of the sensor, stack, and flexible PCB 20 may vary. However, it is important that at least a portion of the flexible PCB can be used as a diaphragm, either alone or in conjunction with another material configured to increase the strength of the flexible PCB.

[0029] Figure 3 (a) and (b) show the cross-sectional area of ​​the microphone system 200 in a side view and a perspective view from below, respectively. Figure 3 The system 200 shown is based on Figure 1 The system shown, in which the flexible PCB 20 and Figure 2 The flexible PCB shown is identical. In the example shown, the housing 10 includes a first housing portion 11 and a second housing portion 12, which are stacked on top of each other and separated by a small gap. The flexible PCB 20 is disposed between the first housing portion 11 and the second housing portion 12, such that it is sandwiched between the two housing portions 11 and 12. The first housing portion 11 includes a first opening 111, and the second housing portion 12 includes a second opening 121. The first opening 111 and the second opening 121 are aligned with each other in the vertical direction and together form an opening 110 through the housing 10. In one example, both the first opening 111 and the second opening 121 have a cylindrical shape. The first opening 111 and the second opening 121 may have the same shape.

[0030] In one example, the first housing portion 11 and the second housing portion 12 are manufactured by 3D printing. In another example, the first housing portion 11 is manufactured by 3D printing, while the second housing portion 12 is manufactured from polymer material by laser cutting. The second housing portion 12 may be made of acrylic material. In yet another example, both the first housing portion 11 and the second housing portion 12 are injection molded from plastic material. Alternatively, the first housing portion 11 and the second housing portion 12 may be made of metal.

[0031] In the example shown, the flexible PCB 20 covers the first end of the first opening 111 and the first end of the second opening 121. Specifically, the first portion 23 of the flexible PCB 20 extends between the first housing portion 11 and the second housing portion 12. The sensor 30 is disposed on the second side 22 of the first portion 23 of the flexible PCB 20, away from the external environment. In the example shown, the sensor 30 is disposed in the middle of the first portion 23.

[0032] The flexible PCB 20 is attached to the housing portions 11 and 12 via mounting elements 40. The mounting elements 40 include a pair of support elements 41 and 42 connected to the housing 10. Support elements 41 and 42 are respectively disposed on a first surface 21 and a second surface 22 of the flexible PCB 20. Thus, the first support element 41 is disposed between the bottom surface of the first housing portion 11 and the first surface 21 of the flexible PCB 20, while the second support element 42 is disposed between the top surface of the second housing portion 12 and the second surface 22 of the flexible PCB 20. In one example, the flexible PCB 20 is sandwiched between the pair of support elements 41 and 42. In another example, the edge of the first portion 23 of the flexible PCB 20 includes multiple through holes. The support elements 41 and 42 are melted by ultrasonic welding, causing the material of the support elements 41 and 42 to flow into the through holes around the edge of the first portion 23 of the flexible PCB 20, thereby securing the first portion 23 of the flexible PCB 20. This allows for a very secure mounting. In one example, the support elements 41 and 42 are configured such that the pressure on the support elements 41 and 42 is uniform. In one example, support elements 41 and 42 are configured as rings and positioned on the edge of the first portion 23 of the flexible PCB 20. The diameter of the circular first portion 23 of the flexible PCB 20 may be larger than the diameter of the openings 111 and 121. These support elements 41 and 42 may be made of a sealing material. In one example, support elements 41 and 42 are made of rubber. In another example, support elements 41 and 42 are made of foam material. In yet another example, support elements 41 and 42 are O-rings made of a material with a hardness of at least Shore 60A. Thus, the microphone's electronic components, particularly sensor 30, can be isolated from the environment and effectively prevented from being affected by dust and environmental conditions. Support elements 41 and 42 also help to dampen external vibrations picked up by the housing 10. Consequently, the microphone system is less susceptible to vibrations transmitted to the housing 10 from the environment (e.g., vehicle vibrations), which improves the performance of the microphone system.

[0033] In the example shown, the second housing portion 12 includes a first portion 123 and an elongated second portion 124, the first portion 123 including a second opening 121. The second elongated portion 24 and the third portion 25 of the flexible PCB 20 are mounted to the second portion 124 of the second housing portion 12. Thus, the second portion 24 and the third portion 25 of the flexible PCB 20 can be supported by the second portion 124 of the second housing portion 12, thereby keeping the flexible PCB 20 taut and improving the overall strength of the system 100.

[0034] System 200 also includes a second PCB 50 attached to housing 10 and flexible PCB 20. The second PCB 50 is connected to sensor 30 via trace 26 of flexible PCB 20 and configured to receive and process electrical signals from sensor 30. In one example, the second PCB 50 is soldered to a third portion 25 of flexible PCB 20. In another example, the second PCB 50 is mounted to a second portion of second housing portion 12 and positioned between the third portion 25 of flexible PCB 20 and a second elongated portion of second housing portion 12. Thus, flexible PCB 20 can be easily connected to the second PCB 50. A first portion 23 of flexible PCB 20 is disposed in the same plane as the second PCB 50. In one example, the second PCB 50 includes analog amplifier circuitry for amplifying sensor signals. In another example, the second PCB 50 is connected to the vehicle's electronic system. The second PCB 50 is configured to output a signal indicative of sound waves received by flexible PCB 20 to the electronic system. The electronic system may be configured to supply power to the second PCB 50. The electronic system can also be configured to control the second PCB 50 and / or the sensor 30. The vehicle's electronic system can then trigger actions based on signals from the second PCB 50. In one example, the second PCB 50 is connected to the electronic system via wires. In another example, the second PCB 50 is connected to the electronic system via press-fit pins. By using press-fit pins, no wires are required inside the microphone, thus simplifying the assembly of the microphone system.

[0035] In one example, the second PCB 50 is a rigid PCB. This makes the microphone system more robust and reliable. Specifically, the second PCB 50 can be used to support the end of the flexible PCB 20 and stably mount it to the housing 10. In another example, the flexible PCB 20 and the second PCB 50 are combined and designed as a single piece using a rigid-flexible design or by mounting all components on a single flexible PCB. Using a rigid-flexible PCB design makes it easier to assemble the final product because the microphone diaphragm and the second PCB are already interconnected. This is also a cost-effective solution. Alternatively, a single flexible PCB 20 can be used, with the amplifier circuitry located at a third section 25 of the flexible PCB 20.

[0036] exist Figure 3 In the examples (a) and (b), the second end of the second opening 121 of the second housing portion 12, opposite to the first end of the second opening 121, remains open. To completely protect the sensor 30 from environmental influences, the second end of the second opening 121 can be closed. For this purpose, the system 200 may also include a closure element covering the second end of the second opening 121. Figure 3 In the example shown in (c), the sealing element is a removable plug element 60. In one example, the removable plug element 60 is inserted into the second through-hole 121 of the second housing portion 12. The plug element 60 has a shape complementary to the second opening 121. In one example, the plug element 60 has a disc-shaped shape. The second surface 22 of the first portion 23 of the flexible PCB 20, the second housing portion 12, and the plug element 60 form a cavity 70. This cavity is sealed by the second support element 42 and the plug element 60. The plug element 60 may be made of a sealing material. In one example, the plug element is made of a plastic material. Alternatively, the sealing element is the bottom wall of the second housing portion 12. Measurements show that the acoustic performance of the microphone system 200, particularly the frequency response of the microphone, is greatly improved when the second opening 121 is closed. Furthermore, by closing the second opening 121, resonance in the frequency response can be reduced.

[0037] The frequency response of a microphone depends heavily on the geometry of the diaphragm, particularly its shape and size, and the housing. Therefore, the frequency response can be adjusted by modifying the dimensions of the diaphragm 20 and the housing 10. The microphone's frequency response also depends heavily on the volume of air enclosed within the cavity 70. In one example, the volume of the cavity 70 can be varied by using different types of plug elements 60. The plug elements 60 are easily replaceable. This makes it possible to adjust the microphone's frequency response in a very simple and quick manner. The plug elements 60 can be manufactured using 3D printing. Thus, they are cost-effective and easy to manufacture. In one example, the distance between the second surface 22 of the flexible PCB 20 and the plug element 60 is 1 mm or less. In another example, the distance between the second surface 22 of the flexible PCB 20 and the plug element 60 is at least 3 mm. Measurements show that the greater the space behind the diaphragm, the better the frequency response of the device. Figure 3 (c) The designed microphone exhibits excellent acoustic characteristics. Specifically, a sensitivity of -11 dBV can be achieved at 1 kHz. The test signal is a 1 kHz sine wave of 94 dBSPL. dBSPL describes the sound pressure level of the test signal from the loudspeaker relative to 20 µPa (equivalent to 0 dBSPL). 94 dBSPL corresponds to 1 Pa. dBV describes the voltage of the electrical signal from the microphone relative to 1 V, where a value of -11 dBV approximately corresponds to 0.28 V. Furthermore, a self-noise of -72 dBV can be achieved between 50 Hz and 20 kHz. Self-noise is an A-weighted value representing the relative loudness perceived by the human ear at different frequencies.

[0038] Figure 3 (c) The fully sealed construction of system 200 effectively protects the microphone's electronic components from environmental influences, particularly water, dust, other impurities, and temperature variations. Furthermore, since system 200 does not include any sound holes for air intake, there is no risk of blockage.

[0039] Figure 4 Another example of the microphone system 300 is shown in a side view. Figure 3 Compared to the example, the second housing portion 12 of housing 10 includes a bottom wall 125 that closes the second end of the second opening 121. The flexible PCB 20 and the first portion 123 of the second housing portion 12, including the second opening 121, thus form a closed cavity 70 that surrounds the sensor 30 and protects it from environmental influences. The cavity 70 is sealed by a second support element 42 disposed between the second surface 22 of the first portion 23 of the flexible PCB 20 and the second housing portion 12. No additional plug components are required. Because the system 300 requires fewer components, it is easy to assemble.

[0040] Furthermore, the housing 10 includes a second cavity 71, which is spaced apart from the first cavity 70 by a sidewall 126 of the second housing portion 12. The second cavity 71 is formed by a second portion 124 of the first housing component 11 and the second housing component 12. More specifically, the second portion 124 of the second housing portion 12 includes a third opening, one end of which is closed by a bottom wall 125, and the other end by a wall of the first housing portion 11. A flexible PCB 20 extends through the second cavity 71 and is connected to a second PCB 50. In the example shown, the second PCB 50 is attached to the wall of the first housing portion 11. Thus, the second PCB 50 and the flexible PCB 20 can be securely supported by the housing 10. In one example, the flexible PCB 20 is flat, and the third portion 25 of the flexible PCB 20 is connected to the second PCB 50. The flexible PCB 20 and the second PCB 50 are disposed in the same plane. The second cavity 71 also protects the electronic components of the second PCB 50 from environmental influences. The second PCB 50 can be connected to a vehicle control panel. The second PCB 50 can be configured to exchange data with the control board device and can be powered by the control board device. In the example shown, the second cavity 71 is sealed by the first support element 41 and the second support element 42.

[0041] Impurities from the environment may accumulate on the flexible PCB 20 and negatively impact its performance as a diaphragm, particularly suppressing its vibration and thus reducing the sensitivity of the microphone system. Specifically, they may affect the vibrational behavior of the flexible PCB 20. To prevent this problem, a protective device 80 (shown in dashed lines) can be provided at the second end of the first opening 111 of the first housing portion 11. In one example, the protective device 80 includes multiple through holes. The through holes have a sufficiently large diameter so that the protective device 80 will not be blocked by small particles. Therefore, the protective device 80 is particularly easy to clean. In one example, the protective device 80 is a grille or mesh. The protective device 80 can be made of plastic. The protective device 80 is used to protect the flexible PCB 20 from external influences and prevents debris and dust from accumulating on the first surface 11 of the flexible PCB 20. In particular, the protective device 80 can protect the diaphragm from impacts, such as from stones hitting the outside of a car when the microphone system is mounted on the outside of a vehicle.

[0042] Figure 5 Another example of a microphone system 400 is shown in a side view. (With) Figure 4Compared to the previous system, the second portion 24 of the flexible PCB 20 is bent. In the example shown, the flexible PCB 20 is bent by 180 degrees. This allows the second PCB 50, connected to the flexible PCB 20, to be positioned below the first portion 23 of the flexible PCB 20. The first portion 23 of the flexible PCB 20 and the second PCB 50 are positioned parallel to each other in two different planes and overlap. This allows for a very compact arrangement. However, other arrangements of the bent flexible PCB 20 are also possible. In one example, the flexible PCB 20 is bent by 90 degrees, and the second PCB is orthogonal to the flexible PCB 20. While the flexible PCB 20 can be bent freely, preferably, the bending radius of the flexible PCB 20 should not be too small to prevent damage to the electronic components disposed on the flexible PCB 20. In one example, the bending radius of the flexible PCB is at least ten times larger than the thickness of the flexible PCB 20. In one example, the bending radius of the flexible PCB 20 is at least 1 mm, preferably at least 1.5 mm.

[0043] for Figure 5 The system can omit the second portion 124 of the second housing component 12. Therefore, the resulting system is not only more compact but also easier to manufacture. In the example shown, the second housing portion 12 includes a bottom wall 125 configured to close the second opening of the second housing portion 12. Thus, the second surface 22 of the first portion 23 of the flexible PCB 20 and the second housing portion 12 form a cavity 70. The cavity 70 surrounds the sensor 30 disposed on the second surface 22 of the first portion 23 of the flexible PCB 20 and the second PCB 50. The first surface of the second PCB 50 is disposed on the bottom wall 125 of the second housing portion 12, and the third portion 25 of the flexible PCB 20 is disposed on the second surface of the second PCB 50 opposite to the first surface of the second PCB 50. This makes the system particularly robust. The cavity 70 is sealed by a second support element 42 disposed between the second surface 22 of the first portion 23 of the flexible PCB 20 and the second housing portion 12. This allows the sensor 30 and the second PCB 50 to be protected from environmental influences, particularly moisture and dust, using a single cavity. Since the cavity is enclosed by the bottom wall 125 of the second housing portion 12, no additional plug element is required.

[0044] In the example shown, the first housing component 11 is designed as a clamping element covering the first support element 41. Therefore, the first portion 23 of the flexible PCB 20 is clamped between the first housing portion 11 and the second housing portion 12. In one example, the curved second portion 24 of the flexible PCB 20 passes through an opening in the housing 10. In one example, the opening is located in the second housing portion 12. This opening may be located at the edges of the support elements 41 and 42. In one example, the first and second housing portions are designed as a single piece. This helps simplify assembly.

[0045] This application describes a system configured for use as a vehicle microphone. A flexible PCB is used as the microphone diaphragm, and a MEMS sensor is mounted on the flexible PCB. When sound waves reach the flexible PCB, the PCB vibrates. The sensor measures the vibration and transmits it to an amplifier circuit, which can be connected to automotive electronics. The blank side of the flexible PCB faces the environment, while the side with the MEMS sensor can be enclosed in a sealed cavity. This setup eliminates the need for a sound hole, which is typically necessary for sound to enter the housing and reach the microphone diaphragm, and protects the electronics from environmental influences, particularly water and dust, thereby improving the microphone's performance and sensitivity. Since the microphone assembly is isolated from the environment, the microphone's interior is prevented from becoming clogged with impurities. The proposed system is easy to manufacture because all necessary components can be placed on a single flexible or rigid-flexible PCB. Furthermore, if the PCB is connected to an external electronic system using press-fit pins, the microphone itself does not require wiring, further simplifying assembly. Assembly is even easier when the system uses a single rigid-flexible PCB because there is no longer a need to connect the diaphragm to the PCB including the amplifier circuit. Additionally, a very compact assembly can be obtained when the flexible PCB used as the diaphragm is bent. The system can be implemented in a vehicle, specifically as a compact microphone on the interior or exterior surface of the vehicle. It can be used for emergency vehicle detection or to listen to a user's voice commands, even when the user is outside the vehicle.

[0046] While various embodiments have been described and illustrated with respect to one or more specific implementations, changes and / or modifications may be made to the illustrated examples without departing from the spirit and scope of the features and structures described herein. In particular, with respect to the various functions performed by the aforementioned components or structures (units, components, devices, circuits, systems, etc.), the terminology used to describe such components (including references to “apparatus”) is intended to correspond to—unless otherwise stated—any component or structure that performs the specified function of the said component (e.g., functionally equivalent), even if it is not structurally equivalent to the disclosed structure that performs that function in the exemplary embodiments shown herein.

[0047] The appended claims specifically point to certain combinations and sub-combinations considered novel and non-obvious. These claims may refer to an element or a first element or its equivalent. Such claims should be understood to include the introduction of one or more such elements, thus neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and / or properties may be claimed by amendment to these claims or by setting new claims in this application or related applications. Such claims, whether broader, narrower, equivalent, or different in scope from the original claims, are considered to be included within the subject matter of this disclosure.

Claims

1. A system (100; 200; 300; 400), which includes: Outer shell (10); A flexible printed circuit board (PCB) (20) having a first surface (21) exposed to the environment and a second surface (22) opposite to the first surface (21), wherein the flexible PCB (20) is mounted to the housing (10) by mounting elements (40), and at least a first portion (23) of the flexible PCB (20) is configured to vibrate when sound waves reach the first surface (21); and A sensor (30) is disposed on the second surface (22) of the flexible PCB (20) for measuring the vibration of the flexible PCB (20) and outputting a corresponding electrical signal.

2. The system according to claim 1, wherein The mounting element (40) includes a pair of support elements (41, 42) connected to the housing (10) and respectively disposed on the first surface (21) and the second surface (22) of the flexible PCB (20), wherein, The flexible PCB (30) is sandwiched between the pair of support elements (41, 42).

3. The system according to claim 1 or 2, wherein The housing (10) includes a first housing portion (11) and a second housing portion (12), wherein the flexible PCB (20) is disposed between the first housing portion and the second housing portion (11, 12).

4. The system according to claim 3, wherein The first housing portion (11) includes a first opening (111), and the flexible PCB (20) covers a first end of the first opening (111).

5. The system according to claim 4, wherein The second housing portion (12) includes a second opening (121), wherein the second opening (121) is aligned with the first opening (111), and The system also includes a closing element (60; 125) covering the first end of the second opening (121).

6. The system according to any one of claims 1 to 5, wherein The sensor (30) is an acceleration sensor.

7. The system according to any one of claims 1 to 6, wherein The sensor (30) is soldered onto the second surface (22) of the flexible PCB (20).

8. The system according to any one of claims 1 to 7, further comprising: A second PCB (50) is attached to the housing (10; 110; 210), wherein the second PCB (50) is connected to the sensor (30) and configured to receive and process electrical signals from the sensor (30).

9. The system according to claim 8, wherein The second PCB (50) is connected to the vehicle's electronic system.

10. The system according to claim 8 or 9, wherein The second PCB (50) is a rigid PCB.

11. The system according to any one of claims 8 to 10, wherein The flexible PCB (20) and the second PCB (50) are designed as a single piece.

12. The system according to any one of claims 8 to 11, wherein The sensor (30) is disposed on the first portion (23) of the flexible PCB (20), and the flexible PCB (20) includes a second portion (24, 25) connected to the second PCB (50).

13. The system according to any one of claims 8 to 12, wherein The second portion (24) of the flexible PCB (20) is bent.

14. The system according to any one of claims 8 to 14, wherein The first portion (23) of the flexible PCB (20) and the second PCB (50) are disposed in the same plane.

15. The system according to any one of claims 8 to 14, wherein The first portion (23) of the flexible PCB (20) and the second PCB (50) are arranged parallel to each other in two different planes and overlap.

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