Adjustable electrostatic exciter of surface microphone and control method thereof

Abstract

The invention discloses an adjustable electrostatic exciter of a surface microphone, which comprises a shell, a plane bearing and a placement base, the plane bearing comprises a mounting part and a bearing part, the mounting part of the plane bearing is provided with a plurality of up-and-down adjusting nuts, and the bearing part of the plane bearing is provided with a plurality of up-and-down adjusting nuts; an adjustable electrostatic excitation plate which is adjusted up and down through the up-and-down adjusting nut is fixed on the up-and-down adjusting nut, and the adjustable electrostatic excitation plate comprises a fixed part and an electrostatic excitation part; the placing base is arranged below the adjustable electrostatic excitation plate, and a plurality of self-adjusting elastic limiting sliding blocks in different directions are arranged on the placing base and used for placing and fixing a surface microphone to be tested; the plane bearing is clamped on the shell, and the placing base is arranged on the shell. The invention further discloses a control method of the adjustable electrostatic exciter. The adjustable electrostatic exciter can adapt to various surface microphones, the distance between the electrostatic exciter and the surface microphones is adjusted, and the adjustable electrostatic exciter can adapt to high-voltage power supplies with different outputs.

Description

Technical Field

[0001] The present invention relates to the technical field of microphones, and particularly to an adjustable electrostatic actuator for a surface microphone and a control method thereof. Background Art

[0002] A surface microphone is a microphone with a relatively special shape, having a flat appearance and a small aspect ratio. Its appearance usually has two structures, namely a cylinder and a cuboid. Among them, the diameter of the cylindrical surface microphone is usually between 20 - 60 mm, and the height is between 2 - 8 mm. The length, width, and height of the cuboid-shaped surface microphone fluctuate within the range of approximately 18×9×1 mm plus or minus 2 mm. The shape of the surface microphone itself is relatively special and cannot be used interchangeably with conventional microphone calibration devices. Coupled with the lack of clear standards to constrain its external dimensions, there are significant differences in the dimensions of surface microphones from different manufacturers, causing great difficulties in calibrating them.

[0003] A surface microphone is a component of an acoustic measurement instrument and should be calibrated before use to ensure the accuracy of the test. Among the calibration parameters of a surface microphone, the calibration of the frequency response is particularly important. Currently, conventional-sized microphones usually use the electrostatic excitation calibration method to calibrate the frequency response of the microphone. However, the special shape and diverse external dimensions of the surface microphone pose great difficulties in calibrating its frequency response.

[0004] The distance d between the electrostatic actuator and the microphone diaphragm and the voltage U applied between the actuator and the microphone diaphragm are two floating parameters. The electrostatic excitation method requires that the effective distance d between the electrostatic actuator and the microphone diaphragm is generally about 0.4 mm - 0.7 mm. However, the existing electrostatic actuators set the distance d as a fixed value, thus also restricting the output of the voltage U. Summary of the Invention

[0005] To solve the problem in the prior art that the electrostatic actuator is poorly adaptable to the surface microphone and the distance between the electrostatic actuator and the surface microphone cannot be adjusted, the present invention proposes an adjustable electrostatic actuator for a surface microphone and a control method thereof.

[0006] The specific technical solution is as follows: An adjustable electrostatic actuator for a surface microphone, comprising:

[0007] A housing, a plain bearing, and a placement base. The plain bearing includes a mounting portion and a bearing portion. A plurality of upper and lower adjusting nuts are provided on the mounting portion of the plain bearing. An adjustable electrostatic excitation plate that can be adjusted up and down by the upper and lower adjusting nuts is fixed on the upper and lower adjusting nuts. The adjustable electrostatic excitation plate includes a fixing portion and an electrostatic excitation portion;

[0008] The placement base is arranged below the adjustable electrostatic excitation plate. A plurality of self-adjusting elastic limit sliders in different directions are arranged on the placement base for placing and fixing the surface microphone to be measured;

[0009] The plain bearing is clamped on the housing, and the placement base is arranged on the housing.

[0010] Further, a lifting baffle capable of moving up and down is arranged below the adjustable electrostatic excitation plate on the placement base for restricting the up and down movement of the surface microphone to be measured. The placement base, the lifting baffle and the electrostatic excitation part of the adjustable electrostatic excitation plate are coaxially arranged.

[0011] Further, a through hole is arranged at the center of the lifting baffle, and the shape of the central through hole of the lifting baffle is adapted to the electrostatic excitation part of the adjustable electrostatic excitation plate.

[0012] Further, a plurality of light-transmitting holes are arranged on the electrostatic excitation part of the adjustable electrostatic excitation plate.

[0013] Further, an upper fixing plate is arranged on the up and down adjusting nut. A precision laser rangefinder is arranged on the upper fixing plate. The precision laser rangefinder is attached to the electrostatic excitation part of the adjustable electrostatic excitation plate, and the axis of the precision laser rangefinder is parallel to the axis of the electrostatic excitation part of the adjustable electrostatic excitation plate.

[0014] Further, a base plate is arranged at the bottom of the housing. A lifting base is arranged at the bottom of the placement base. The lifting base is clamped in the housing. A spring is arranged between the lifting base and the base plate for locking the lifting base.

[0015] Further, the installation part of the plain bearing is clamped with the housing, and the bearing part of the plain bearing is arranged between the installation part of the plain bearing and the housing.

[0016] Further, the adjustable electrostatic excitation plate is connected with a signal input line.

[0017] A control method for an adjustable electrostatic exciter of a surface microphone is applicable to an adjustable electrostatic exciter of a surface microphone. The steps include:

[0018] Install the surface microphone: Place the surface microphone into the space between the self-adjusting elastic limit sliders from the top opening of the placement base and fix it;

[0019] Adjust the height of the electrostatic excitation plate: Turn on the precision laser rangefinder and adjust all the up and down adjusting nuts according to the measured value until the distance from the bottom of the electrostatic excitation plate to the surface microphone reaches the required value;

[0020] Adjust the parallelism of the electrostatic excitation plate: Rotate the upper sliding cover to the next equal - division angle. If the measured value at this time is greater than the required value, adjust the upper and lower adjusting nuts closer to the axis of the precision laser rangefinder; if the measured value at this time is less than the required value, adjust the upper and lower adjusting nuts farther from the axis of the precision laser rangefinder. Repeat the above steps until the measured value is equal to the required value.

[0021] Connect the signal source and conduct the electrostatic excitation response test of the surface microphone.

[0022] Furthermore, the height adjustment range of the electrostatic excitation plate is 0.3 mm - 1 mm.

[0023] The above - mentioned technical solution has the following advantages or technical effects:

[0024] 1. The adjustable electrostatic exciter of the present invention has high adaptability, can be clamped and tested for surface microphones of different specifications, and is convenient for calibration and use.

[0025] 2. The present invention can adjust the height of the electrostatic excitation plate by rotating the upper and lower adjusting nuts, and with the micron - level laser rangefinder, it ensures the accuracy of the adjustment of the electrostatic excitation plate, improving the accuracy and stability of the test.

[0026] 3. The upper sliding cover part of the present invention can rotate 360°. By rotating the thread to adjust the height of the electrostatic excitation plate, the distance and parallelism between the electrostatic excitation plate and the diaphragm of the surface microphone can be adjusted: it adapts to the outputs of different high - voltage power supplies and can also ensure the accuracy of the frequency response test. Brief Description of the Drawings

[0027] Figure 1 is the schematic cross - sectional structure diagram of the present invention;

[0028] Figure 2 is the schematic structure diagram of the present invention;

[0029] Figure 3 is the exploded schematic structure diagram of the present invention;

[0030] Figure 4 is the assembly schematic diagram of one of the surface microphones to be tested of the present invention;

[0031] Figure 5 is the assembly schematic diagram of one of the surface microphones to be tested of the present invention;

[0032] Figure 6 is the method flow chart of the present invention.

[0033] In the attached drawings, the markings are: 1 - base plate, 2 - housing, 3 - spring, 4 - lifting base, 5 - upper and lower adjusting nuts, 6 - lifting baffle, 7 - signal input line, 8 - self - adjusting elastic limit slider, 9 - precision laser rangefinder, 10 - adjustable electrostatic excitation plate, 11 - upper fixing plate, 12 - surface microphone to be measured, 13 - placement base, 14 - plain bearing. Detailed implementation manners

[0034] To make the technical solution of the present invention clearer, the following further describes the present invention in detail with reference to the attached drawings and specific embodiments.

[0035] Embodiment 1

[0036] As Figure 1 、 Figure 2 、 Figure 3 shown, an adjustable electrostatic exciter for a surface microphone includes:

[0037] A housing 2, a plain bearing 14 and a placement base 13. The plain bearing 14 includes an installation part and a bearing part. A plurality of upper and lower adjusting nuts 5 are provided on the installation part of the plain bearing 14. An adjustable electrostatic excitation plate 10 that is adjusted up and down through the upper and lower adjusting nuts 5 is fixed on the upper and lower adjusting nuts 5. The adjustable electrostatic excitation plate 10 includes a fixing part and an electrostatic excitation part. The placement base 13 is arranged below the adjustable electrostatic excitation plate 10. A plurality of self - adjusting elastic limit sliders 8 in different directions are provided on the placement base 13 for placing and fixing the surface microphone 12 to be measured. The plain bearing 14 is clamped on the housing 2, and the placement base 13 is arranged on the housing 2.

[0038] The surface microphone is flatter and has a smaller aspect ratio. This design is usually for better fitting to specific surfaces, such as walls, desktops or mechanical equipment, etc., to capture the sound vibrations on these surfaces. Conventional microphones often have a more three - dimensional shape with a larger aspect ratio and are more suitable for general sound collection tasks. Due to the special shape of the surface microphone, conventional microphone calibration devices often cannot be directly used. These calibration devices are usually designed based on the size and shape of three - dimensional microphones, so they cannot well adapt to the flat surface microphone with a small aspect ratio. The present invention is an adjustable electrostatic exciter designed for surface microphones. The surface microphone to be measured is fixed on the top of the placement base 13 through the self - adjusting elastic limit slider 8 to achieve the calibration of the surface microphone.

[0039] The placement base 13 is coaxially arranged with the plain bearing 14. The placement base 13 is arranged inside the plain bearing 14. A plurality of up-and-down adjusting nuts 5 are circumferentially and equidistantly arranged on the upper surface of the mounting part of the plain bearing 14. The plurality of up-and-down adjusting nuts 5 jointly fix the adjustable electrostatic excitation plate 10. Each up-and-down adjusting nut 5 is connected to a fixing part of the adjustable electrostatic excitation plate 10. The up-and-down adjusting nut 5 adjusts the overall length of the nut by rotating the thread, thereby adjusting the distance between the adjustable electrostatic excitation plate 10 and the microphone 12 on the surface to be measured.

[0040] One side of the top of the placement base 13 is provided with a flat groove. The flat groove is provided with an opening on one side close to the edge of the placement base 13 for placing the microphone 12 on the surface to be measured. The side of the flat groove far from the edge of the placement base 13 and the adjacent two sides are provided with limit slider mounting grooves. The three limit slider mounting grooves are used to respectively mount a self-adjusting elastic limit slider 8. The height of the self-adjusting elastic limit slider 8 is adapted to the thickness of the microphone on the surface and the height of the limit slider mounting groove. The height of the self-adjusting elastic limit slider 8 and the height of the limit slider mounting groove are 10 mm. As Figure 4 、 Figure 5 shown, the rectangular or circular microphone 12 on the surface to be measured is placed into the flat groove from the opening side, and the springs of the three self-adjusting elastic limit sliders 8 are adaptively compressed, so that the microphone 12 on the surface to be measured is fixed in a proper position.

[0041] An up-and-down adjustable lifting baffle 6 is arranged below the adjustable electrostatic excitation plate 10 on the placement base 13 for restricting the up-and-down movement of the microphone 12 on the surface to be measured. When the microphone 12 on the surface to be measured is placed, the lifting baffle 6 is lifted. After the microphone 12 on the surface to be measured is fixed, the lifting baffle 6 automatically rebounds to restrict the up-and-down movement of the microphone 12 on the surface to be measured. The placement base 13, the lifting baffle 6 and the electrostatic excitation part of the adjustable electrostatic excitation plate 10 are coaxially arranged.

[0042] A through hole is arranged at the center of the lifting baffle 6. The shape of the central through hole of the lifting baffle 6 is adapted to the electrostatic excitation part of the adjustable electrostatic excitation plate 10. When the adjustable electrostatic excitation plate 10 is lowered to the lowest height, the electrostatic excitation part of the adjustable electrostatic excitation plate 10 below the fixing part of the adjustable electrostatic excitation plate 10 just fits into the central through hole of the lifting baffle 6.

[0043] The electrostatic excitation part of the adjustable electrostatic excitation plate 10 is provided with a number of light-transmitting holes for the precision laser rangefinder 9 to measure. An upper fixing plate 11 is provided on the upper and lower adjusting nut 5. Both ends of the upper and lower adjusting nut 5 are respectively fixed on the upper fixing plate 11 and the mounting part of the plain bearing 14. The precision laser rangefinder 9 is provided on the upper fixing plate 11. The precision laser rangefinder 9 is attached to the electrostatic excitation part of the adjustable electrostatic excitation plate 10. The axis of the precision laser rangefinder 9 is arranged parallel to the axis of the electrostatic excitation part of the adjustable electrostatic excitation plate 10. The height of the electrostatic excitation part of the adjustable electrostatic excitation plate 10 is a fixed value. The actual measured value is the real-time measured value of the precision laser rangefinder 9 minus the height of the electrostatic excitation part.

[0044] A base plate 1 is provided at the bottom of the housing 2. A lifting base 4 is provided at the bottom of the placing base 13. The lifting base 4 is clamped in the housing 2. A spring 3 is provided between the lifting base 4 and the base plate 1 for locking the lifting base 4. During installation, the spring 3 and the lifting base 4 are sequentially placed into the housing 2. Finally, the placing base 13 is snapped into the housing 2. After the spring 3 rebounds, the placing base 13 and the lifting base 4 are locked, and the placing base 13 is fixed to the housing 2.

[0045] The mounting part of the plain bearing 14 is clamped to the housing 2. The bearing part of the plain bearing 14 is arranged between the mounting part of the plain bearing 14 and the housing 2. By rotating the upper fixing plate 11, the precision laser rangefinder 9 and the adjustable electrostatic excitation plate 10 can be rotated relative to the surface microphone 12 to be measured under the action of the bearing part of the plain bearing 14, so that different angles can be tested, and the parallelism between the adjustable electrostatic excitation plate 10 and the surface microphone diaphragm can be adjusted through the measured value of the precision laser rangefinder 9 that is not coaxial with the electrostatic excitation part of the adjustable electrostatic excitation plate 10.

[0046] The adjustable electrostatic excitation plate 10 is connected with a signal input line 7 for inputting an electrostatic excitation signal for testing.

[0047] The number of the upper and lower adjusting nuts 5 and the fixing parts of the adjustable electrostatic excitation plate 10 is three each.

[0048] Embodiment 2

[0049] As Figure 6 shown, a control method for an adjustable electrostatic exciter of a surface microphone includes the following steps:

[0050] Install the surface microphone: Place the surface microphone through the top opening of the placing base 13 and fix it between the self-adjusting elastic limit sliders 8;

[0051] Adjust the height of the electrostatic excitation plate: Turn on the precision laser rangefinder 9 and adjust all the upper and lower adjusting nuts 5 according to the measured value until the distance from the bottom of the electrostatic excitation plate to the surface microphone reaches the required value;

[0052] Adjust the parallelism of the electrostatic excitation plate: Rotate the upper sliding cover to the next equal - division angle. If the measured value at this time is greater than the required value, adjust the upper and lower adjusting nuts 5 closer to the axis of the precision laser rangefinder 9; if the measured value at this time is less than the required value, adjust the upper and lower adjusting nuts 5 farther from the axis of the precision laser rangefinder 9. Repeat the above steps until the measured value is equal to the required value.

[0053] Connect the signal source and conduct the electrostatic excitation response test of the surface microphone.

[0054] According to the electrostatic exciter calibration specification, the distance d between the electrostatic exciter and the microphone diaphragm and the voltage U applied between the exciter and the microphone diaphragm are two floating parameters. The electrostatic excitation method requires that the effective distance d between the electrostatic exciter and the microphone diaphragm is generally about 0.4 mm - 0.7 mm. However, the existing electrostatic exciters set the distance d as a fixed value, which also restricts the output of the voltage U. At the same time, the repeatability of the electrostatic exciter response is also specified: at the specified frequency of the electrostatic exciter response, usually 250 Hz, its repeatability is generally not greater than 0.04 dB; the consistency of the difference between the electrostatic exciter response level and the sound - pressure response level: the average value of the difference between the electrostatic exciter response level and the sound - pressure response level, and the deviation of the difference between the electrostatic exciter response level and the sound - pressure response level obtained by a single measurement are generally not more than ±0.1 dB. Therefore, it is also necessary to ensure the parallelism between the electrostatic excitation and the diaphragm of the microphone during the test.

[0055] In the present invention, after placing the surface microphone to be measured into the placement base 13, the installation is completed. There are through - holes on the electrostatic excitation plate. The precision laser rangefinder 9 is fitted and installed with the electrostatic excitation plate. The laser in the precision laser rangefinder 9 passes through the through - holes to measure the distance between the diaphragm of the surface microphone and the upper plane of the electrostatic excitation plate. Since the thickness of the electrostatic excitation plate is fixed, subtracting the thickness of the electrostatic excitation plate from the measured distance is the distance d between the diaphragm of the surface microphone and the lower plane of the electrostatic excitation plate. This effective distance d is generally about 0.4 mm - 0.7 mm and has a very high parallelism requirement. According to the measured distance, by adjusting the upper and lower adjusting nuts 5, any distance adjustment between 0.3 mm - 1 mm can be completed. At this time, the adjusted distance d is not an exact value, and there is also a parallelism problem between the electrostatic excitation plate and the diaphragm of the surface microphone. Since each component is fixedly installed on the plain bearing 14, by rotating the plain bearing 14 and combining the distance readings of the laser rangefinder, the upper and lower adjusting nuts 5 can be precisely rotated and adjusted to the same distance. After completing the 360 - degree rotation adjustment, adjust the distance readings of the laser rangefinder at each angle to the same reading, that is, complete the parallelism adjustment between the electrostatic excitation plate and the diaphragm of the surface microphone, and then connect the signal source to conduct the electrostatic excitation response test of the surface microphone.

[0056] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent for the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention shall be subject to the appended claims.

Claims

1. An adjustable electrostatic actuator for a surface microphone, characterized in that: include: A housing, a plane bearing and a placement base, wherein the plane bearing comprises a mounting portion and a bearing portion, the mounting portion of the plane bearing is provided with a plurality of up and down adjustment nuts, an adjustable electrostatic excitation plate which is adjusted up and down by the up and down adjustment nuts is fixed on the up and down adjustment nuts, and the adjustable electrostatic excitation plate comprises a fixing portion and an electrostatic excitation portion; The placement base is arranged below the adjustable electrostatic excitation plate, and the placement base is provided with a plurality of self-adjusting elastic limiting sliders in different directions for placing and fixing the surface microphone to be tested; The plane bearing is clamped on the shell, and the placement base is arranged on the shell.

2. The adjustable electrostatic actuator for a surface microphone according to claim 1, characterized in that: A lifting baffle plate that can be adjusted up and down is provided on the placement base below the adjustable electrostatic excitation plate to limit the up and down movement of the surface microphone to be tested. The placement base, the lifting baffle plate and the electrostatic excitation part of the adjustable electrostatic excitation plate are coaxially arranged.

3. The adjustable electrostatic actuator for a surface microphone according to claim 2, characterized in that: A through hole is provided at the center of the lifting baffle plate, and the shape of the central through hole of the lifting baffle plate is matched with the electrostatic excitation part of the adjustable electrostatic excitation plate.

4. The adjustable electrostatic actuator for a surface microphone according to claim 2, characterized in that: The electrostatic excitation portion of the adjustable electrostatic excitation plate is provided with a plurality of light-transmitting holes.

5. The adjustable electrostatic actuator for a surface microphone according to claim 4, characterized in that: An upper fixing plate is provided on the upper and lower adjusting nuts, and a precision laser rangefinder is provided on the upper fixing plate. The precision laser rangefinder is fitted on the electrostatic excitation part of the adjustable electrostatic excitation plate, and the axis of the precision laser rangefinder is arranged parallel to the axis of the electrostatic excitation part of the adjustable electrostatic excitation plate.

6. The adjustable electrostatic actuator for a surface microphone according to claim 1, characterized in that: A base plate is provided at the bottom of the shell body, a lifting base is provided at the bottom of the placement base, the lifting base is clamped in the shell body, and a spring is provided between the lifting base and the base plate for locking the lifting base.

7. The adjustable electrostatic actuator for a surface microphone according to claim 1, characterized in that: The mounting portion of the plane bearing is clamped with the housing, and the bearing portion of the plane bearing is arranged between the mounting portion of the plane bearing and the housing.

8. The adjustable electrostatic actuator for a surface microphone according to claim 7, characterized in that: The adjustable electrostatic excitation plate is connected with a signal input line.

9. A control method for an adjustable electrostatic actuator of a surface microphone, applicable to an adjustable electrostatic actuator of a surface microphone according to any one of claims 1 to 8, characterized in that the steps include: Install the surface microphone: Place the surface microphone from the top opening of the base into the self-adjusting elastic limit sliders and fix it; Adjust the height of the electrostatic excitation plate: Turn on the precision laser rangefinder and adjust all the upper and lower adjustment nuts according to the measured value until the distance from the bottom of the electrostatic excitation plate to the surface microphone is the required value; Adjust the parallelism of the electrostatic excitation plate: rotate the upper slide cover to the next equally divided angle. If the measured value at this time is greater than the required value, adjust the upper and lower adjustment nuts close to the axis of the precision laser rangefinder; if the measured value at this time is less than the required value, adjust the upper and lower adjustment nuts away from the axis of the precision laser rangefinder. Repeat the above steps until the measured value is equal to the required value. Connect the signal source to test the electrostatic excitation response of the surface microphone.

10. The control method of the adjustable electrostatic actuator of a surface microphone according to claim 9, characterized in that: The height adjustment range of the electrostatic excitation plate is 0.3 mm-1 mm.

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