CN110719557B - Nonlinear correction microphone - Google Patents
Nonlinear correction microphone Download PDFInfo
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- CN110719557B CN110719557B CN201911064019.1A CN201911064019A CN110719557B CN 110719557 B CN110719557 B CN 110719557B CN 201911064019 A CN201911064019 A CN 201911064019A CN 110719557 B CN110719557 B CN 110719557B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R19/00—Electrostatic transducers
- H04R19/04—Microphones
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H11/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties
- G01H11/06—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means
Abstract
The invention relates to a nonlinear correction microphone which comprises a sensitive film, a base main body, a low-sensitive rear polar plate, a high-sensitive rear polar plate, a shielding cavity, a high-sound-pressure output pole, a high-sensitive output pole and an amplifying circuit board. A high-sound-pressure low-sensitivity capacitor microphone and a low-sound-pressure high-sensitivity capacitor microphone are combined together to detect the same sound pressure, the two capacitors share a diaphragm, the small area of the center of a rear pole plate is the rear pole of the high-sound-pressure capacitor microphone, the large area of the periphery of the rear pole plate is the rear pole of the low-sound-pressure capacitor microphone, the output of the low-sound-pressure capacitor microphone is approximately linear, the output of the high-sensitivity capacitor microphone is nonlinear, and the output signal of the high-pressure microphone is utilized in an amplifier to correct the output of the high-sensitivity capacitor microphone.
Description
Technical Field
The invention relates to a nonlinear correction microphone, belongs to the technical field of microphones, and is used in the field of sound wave (including infrasonic wave) sensing.
Background
The microphone is applied to the infrasound detection field with a large dynamic range (0.01Pa-20kPa), and is divided from a transduction mode, the existing infrasound microphone is mainly piezoelectric, capacitive and electrodynamic, the microphone of the invention adopts the capacitive type, the capacitive type microphone has the characteristics of high sensitivity, wide and flat frequency response and good stability, the existing capacitive type microphone has a small detection range, the maximum is hundreds of Pa, and the reason is: the existing condenser microphone has the non-linear problem of large sound pressure detection, and the principle is as follows: the asymmetry phenomenon, in which the change in the capacitance pitch caused by the sound pressure exceeds a certain ratio, appears to be high in sensitivity to positive pressure and low in sensitivity to negative pressure.
Microphones using other principles such as electrodynamic type and piezoelectric type have the disadvantages of not wide enough frequency band, not flat in band, large self-noise and low sensitivity although the nonlinear effect is not obvious.
The invention can obviously improve the detection range and solve the nonlinear problem of large dynamic range under the condition of keeping the advantage of high sensitivity of the condenser microphone.
Disclosure of Invention
The invention aims to overcome the problem of nonlinearity of a large dynamic range of the existing condenser microphone, provides a nonlinear correction microphone, and solves the nonlinear problem of the existing condenser microphone when detecting large sound pressure.
The invention solves the non-linearity problem of the existing condenser microphone by adopting the following technical scheme:
the working principle of a general condenser microphone is as follows: when sound wave acts on the sensitive film, the film vibrates along with the sound wave, so that the distance between the film and the back polar plate is changed, the capacitance is changed, and the sound wave can be measured by detecting the change of the capacitance.
The invention relates to a nonlinear correction microphone which comprises a sensitive film 1, a high-sound-pressure output electrode 2, a high-sensitivity output electrode 3, an amplifying circuit board 4, a base main body 5, a shielding cavity 6, a low-sensitivity rear polar plate 7 and a high-sensitivity rear polar plate 8, wherein the low-sensitivity rear polar plate 7 is fixedly arranged on the high-sound-pressure output stage 2 without a gap, the high-sensitivity rear polar plate 8 is fixedly arranged on the high-sensitivity output stage 3 without a gap, and the amplifying circuit board 4 is tightly connected with the high-sound-pressure output electrode 2 and the high-sensitivity output electrode 3; the sensitive membrane 1, the high-sound-pressure output electrode 2, the high-sensitivity output electrode 3, the amplifying circuit board 4, the base main body 5, the low-sensitivity rear polar plate 7 and the high-sensitivity rear polar plate 8 are arranged in the shielding cavity 6, the low-sensitivity rear polar plate 7 and the high-sensitivity rear polar plate 8 output high-sound pressure and high-sensitivity respectively, and the output high-sound pressure and high-sensitivity are connected with the signal amplifying circuit board 4 through the high-sound-pressure output plate 2 and the high-sensitivity output plate 3 respectively.
And the signal of the high sound pressure output stage 2 in the amplifying circuit board 4 is connected to the signal amplifying loop of the high sensitive output stage 3 to compensate nonlinearity.
The shielding cavity 6 ensures the signal quality of the sensor and eliminates the influence of electromagnetic induction.
The sensitive film is a film made of steel, nickel or titanium metal, and no sand holes are formed in the sensitive film.
The amplifying circuit board 4 is fixedly installed with the low-sensitivity back polar plate 7 and the high-sensitivity back polar plate 8 without a gap.
The shielding cavity 6 is made of steel materials, and the pressure in the shielding cavity 6 is ensured not to change along with the external mechanical pressure.
The base main body 5 is the key for ensuring the accuracy of the sensor, the sensitive membrane 1, the low-sensitive rear polar plate 7, the high-sensitive rear polar plate 8, the high-sound-pressure output electrode 2 and the high-sensitive output electrode 3 are arranged on the base main body 5, the output electrodes have two paths of signals, one path is high-sound-pressure linear response output, and the other path is high-sensitive nonlinear output.
The low-sensitivity rear polar plate 7 and the high-sensitivity rear polar plate 8 are of a composite structure with two output poles, the middle is low-sensitivity high-voltage detection output, the periphery is high-sensitivity detection output, the low-sensitivity rear polar plate and the high-sensitivity rear polar plate are electrically insulated and fixedly connected together, and a stable relation is formed.
The high sound pressure output electrode 2 and the high sensitive output electrode 3 are electrodes with two paths of output and are tightly installed with the signal amplification circuit board 4.
The signal amplification circuit board 4 is provided with two paths of amplifiers, and the high sound pressure output signal is connected to a feedback loop of the high-sensitivity amplification circuit and is used for correcting the nonlinearity of the high-sensitivity output signal.
The invention has the beneficial effects that:
1. the double-capacitor detection is adopted, and the high-sound-pressure output signal with low sensitivity is used for correcting the high-sensitivity output signal with high sensitivity, so that high sensitivity and linear detection on sound pressure are realized. The low sensitivity output of the high voltage detection is equivalent to a microphone with large distance and small diaphragm diameter, and the high sensitivity output is equivalent to a capacitor microphone with high sensitivity, large diaphragm diameter and small distance. The composite detection method can reduce the nonlinearity by more than 20 dB.
2. Because the double capacitors are combined together, the device structure is basically the same as that of the common single capacitor microphone, so that the characteristics of wide frequency response, low noise and high sensitivity are maintained.
3. The two capacitors in the invention adopt the same sensitive film, so that no phase shift exists, and self-noise is correlated, so that noise is counteracted in negative feedback, and the signal-to-noise ratio is improved.
4. The lower limit of the detection frequency is lowered by increasing the sensitive membrane.
5. The amplifying circuit adopts a non-inductive detection circuit, the detection pressure range is expanded, the null shift is eliminated, and the manual zero setting is not needed.
Drawings
FIG. 1 is a schematic view of the structure
In the figure: 1. the high-sensitivity sound-pressure amplifier comprises a sensitive film, 2 high sound-pressure output electrodes, 3 high-sensitivity output electrodes, 4 amplifying circuit boards, 5 a base main body, 6 shielding cavities, 7 low-sensitivity rear pole plates and 8 high-sensitivity rear pole plates.
FIG. 2 sensitivity curves for low sound pressure high sensitivity microphone and high sound pressure low sensitivity microphone
In the figure: 9. a positive pressure sensitivity curve of the low sound pressure high sensitivity microphone, 10. a negative pressure sensitivity curve of the low sound pressure high sensitivity microphone, 11. a positive pressure sensitivity curve of the high sound pressure low sensitivity microphone, 12. a negative pressure sensitivity curve of the high sound pressure low sensitivity microphone;
the ordinate is sensitivity, unit mv/Pa; the abscissa is the sound pressure in Pa.
Detailed Description
The invention is further explained by the embodiment in the following with the attached drawings.
As shown in fig. 1, the nonlinear modified microphone includes a sensitive film, a base body, a back plate, a shielding cavity, an output electrode and a signal amplification circuit board, the sensitive film 1 is installed on the base body 5 and is in a tight state, a high sensitive back plate 8 and a low sensitive back plate 7 are assembled together behind the sensitive film 1, the high sensitive back plate 8 is electrically connected with the high sensitive output electrode 3, the low sensitive back plate 7 is electrically connected with the high sound pressure output electrode 2, and the high sensitive output electrode 3 and the high sound pressure output electrode 2 are respectively installed on the signal amplification circuit board 4. The high-sensitivity back plate 8 and the low-sensitivity back plate 7 are fixedly assembled together through a hard glue after curing, and the height difference between the two surfaces is kept accurate.
The height difference between the high-sensitivity rear polar plate 8 and the low-sensitivity rear polar plate 7 determines the degree of nonlinear correction, and also determines the maximum range of sound pressure after the high-sensitivity microphone linearly measures and corrects. The nonlinear correction is higher than the upper limit of linear measurement of the common condenser microphone by more than 20 dB.
Example 1
A nonlinear correction microphone is shown in figure 1 and comprises a sensitive film 1, a high sound pressure output electrode 2, a high sensitivity output electrode 3, an amplifying circuit board 4, a base main body 5, a shielding cavity 6, a low sensitivity rear polar plate 7 and a high sensitivity rear polar plate 8. The sensitive membrane 1 is arranged on a base main body 5, the amplifying circuit board 4 is fixed in the base main body 5, the base main body 5 is arranged in the shielding cavity 6, and the high sound pressure output electrode 2 and the high sensitive output electrode 3 are respectively arranged on the amplifying circuit board 4. The high sound pressure output electrode 2 is electrically connected with the low-sensitivity rear polar plate 7, and the high-sensitivity output electrode 3 is electrically connected with the high-sensitivity rear polar plate 8.
The sensitivity curve of the low-voltage high-sensitivity condenser microphone is tilted upwards along with the increase of positive pressure, and is bent downwards along with the increase of negative pressure, the upward tilting speed is higher than the downward bending speed, the upward tilting speed and the downward bending speed are different, and the characteristic is the nonlinear effect of the condenser microphone.
The sensitivity curve of the high-voltage low-sensitivity condenser microphone is tilted upwards along with the increase of positive pressure, and is bent downwards along with the increase of negative pressure, the upward tilting speed is higher than the downward bending speed, the upward tilting speed and the downward bending speed are not equal, and the characteristic is the nonlinear effect of the condenser microphone.
The non-linearity of the sensitivity curve of the low voltage high sensitive condenser microphone occurs earlier than the non-linearity of the sensitivity curve of the high voltage low sensitive condenser microphone.
The sensitivity of the low voltage high sensitive condenser microphone is higher than that of the high voltage low sensitive condenser microphone.
The sensitivity curve of the low-voltage high-sensitivity condenser microphone is represented by a thin line, which represents that the output noise is relatively small. The sensitivity curve of the high-voltage low-sensitivity condenser microphone is represented by a thick line, which represents that the output noise is relatively large.
The working principle of the invention is as follows:
the sound pressure input from outside causes the sensitive film 1 to vibrate, the distance between the sensitive film 1 and the low-sensitive back polar plate 7 and the distance between the sensitive film 1 and the high-sensitive back polar plate 8 are changed, two capacitance changes are caused, the output voltage of the two capacitors changes, and a sound signal is formed. The distance between the low-sensitive rear polar plate 7 and the sensitive film 1 is large, the area is small, the output voltage value is small, and the output voltage and the vibration of the sensitive film are in an approximate linear state. The distance between the high-sensitivity rear polar plate 8 and the sensitive film 1 is small, the area is large, the output voltage and the vibration of the sensitive film are in a nonlinear state, the sensitivity is high, and the output voltage value is large.
The output sensitivity formula of the capacitive sensor is as follows:
where D is the distance between the diaphragm and the back electrode and D is the diaphragm vibration displacement caused by sound pressure. k is a coefficient.
Wherein the amount of non-linearity is determined by the D/D equation.
In the scheme of the invention, the typical value of the diaphragm distance D1 of the high-sound pressure capacitance sensor is 200 μm, which is much larger than the typical value of 20 μm of the diaphragm distance D2 of the high-sensitivity capacitance sensor, and the difference between the two values is more than 10 times, so that (D/D2) > (10 × D/D1). Therefore, the nonlinearity of the high-sound-pressure capacitance sensor is more than 10 times lower than that of the high-sensitivity capacitance sensor, so that the nonlinearity can be reduced by more than 10 times by using the output of the high-sound-pressure capacitance sensor to correct the output of the high-sensitivity capacitance sensor, namely the nonlinearity is reduced by more than 20 dB.
The high-sensitivity capacitance sensor has large area, small diaphragm spacing and large capacitance, so the high-sensitivity capacitance sensor has low measurement frequency and small detection noise. The area of the high-sound-pressure capacitance sensor is small, the distance between the diaphragms is large, and the capacitance is small, so that the measurement frequency is high and the noise is large. Therefore, the output voltage value of the high-sound-pressure capacitive sensor is only used for correcting the output signal of the high-sensitivity capacitive sensor, and the high-sensitivity, low-frequency and low-noise linear measurement can be realized.
It should be noted that the nonlinear modified microphone can be designed as a dual-capacitor modified solution in other structures, or even a multi-capacitor composite solution, and other variations in the capacitor structure are within the scope of the claims of the present invention. The structural form of the sensitive membrane and the back plate is modified into other structural forms, and the modification scheme of multi-capacitance combination is adopted, so that the method belongs to the scope of the claims of the invention.
Claims (5)
1. A non-linearly modified microphone, characterized by: the microphone comprises a sensitive film (1), a high-sound-pressure output electrode (2), a high-sensitivity output electrode (3), an amplifying circuit board (4), a base main body (5), a shielding cavity (6), a low-sensitivity rear polar plate (7) and a high-sensitivity rear polar plate (8), wherein the low-sensitivity rear polar plate (7) is fixedly arranged on the high-sound-pressure output stage (2) without a gap, the high-sensitivity rear polar plate (8) is fixedly arranged on the high-sensitivity output stage (3) without a gap, and the amplifying circuit board (4) is tightly connected with the high-sound-pressure output electrode (2) and the high-sensitivity output electrode (3); the sensitive film (1), the high-sound-pressure output electrode (2), the high-sensitivity output electrode (3), the amplifying circuit board (4), the base main body (5), the low-sensitivity rear polar plate (7) and the high-sensitivity rear polar plate (8) are arranged in the shielding cavity (6), the low-sensitivity rear polar plate (7) and the high-sensitivity rear polar plate (8) respectively output high sound pressure and high sensitivity, and the output high sound pressure and the output high sensitivity are respectively connected with the amplifying circuit board (4) through the high-sound-pressure output electrode (2) and the high-sensitivity output electrode (3).
2. A non-linearly modified microphone according to claim 1, wherein: the signal of the high sound pressure output stage (2) in the amplifying circuit board (4) is connected to the signal amplifying loop of the high sensitive output stage (3) to compensate the nonlinearity.
3. A non-linearly modified microphone according to claim 1, wherein: the shielding cavity (6) ensures the signal quality of the sensor and eliminates the influence of electromagnetic induction.
4. A non-linearly modified microphone according to claim 1, wherein: the sensitive film material is steel, nickel or titanium.
5. A non-linearly modified microphone according to claim 3, wherein: the shielding cavity (6) is made of steel materials, so that the pressure in the shielding cavity (6) is ensured not to change along with the external mechanical pressure.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911064019.1A CN110719557B (en) | 2019-11-04 | 2019-11-04 | Nonlinear correction microphone |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911064019.1A CN110719557B (en) | 2019-11-04 | 2019-11-04 | Nonlinear correction microphone |
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| CN110719557A CN110719557A (en) | 2020-01-21 |
| CN110719557B true CN110719557B (en) | 2021-03-05 |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101257738A (en) * | 2007-02-26 | 2008-09-03 | 雅马哈株式会社 | Sensitive silicon microphone with wide dynamic range |
| CN102387456A (en) * | 2011-11-02 | 2012-03-21 | 深圳市豪恩声学股份有限公司 | Midget microphone and manufacturing method thereof |
| WO2013083203A1 (en) * | 2011-12-09 | 2013-06-13 | Epcos Ag | Double backplate mems microphone with a single-ended amplifier input port |
| CN104427450A (en) * | 2013-08-29 | 2015-03-18 | 鑫创科技股份有限公司 | Micro electro-mechanical system (MEMS) microphone device with multi-sensitivity outputs and circuit with the MEMS device |
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2019
- 2019-11-04 CN CN201911064019.1A patent/CN110719557B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101257738A (en) * | 2007-02-26 | 2008-09-03 | 雅马哈株式会社 | Sensitive silicon microphone with wide dynamic range |
| CN102387456A (en) * | 2011-11-02 | 2012-03-21 | 深圳市豪恩声学股份有限公司 | Midget microphone and manufacturing method thereof |
| WO2013083203A1 (en) * | 2011-12-09 | 2013-06-13 | Epcos Ag | Double backplate mems microphone with a single-ended amplifier input port |
| CN104427450A (en) * | 2013-08-29 | 2015-03-18 | 鑫创科技股份有限公司 | Micro electro-mechanical system (MEMS) microphone device with multi-sensitivity outputs and circuit with the MEMS device |
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| CN110719557A (en) | 2020-01-21 |
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