CN200947674Y - A miniature condenser microphone - Google Patents

Abstract

The utility model discloses a miniature condenser microphone, which comprises a shell, a high temperature resistant vibrating membrane group, a high temperature resistant hollow gasket, a back polar plate, a high temperature resistant back polar plate seat, a connecting frame and a circuit board; the bottom panel and the back plate of the shell are respectively provided with a through hole, the vibrating membrane group, the hollow gasket and the back plate seat are sequentially stacked on the bottom panel of the shell, the back plate and the connecting frame are sequentially stacked in the back plate seat, and the circuit board is embedded in the opening of the shell and is electrically connected with the connecting frame; the inner side of the circuit board is provided with a special chip which can provide direct current bias voltage. The utility model discloses a back plate seat, gasket, the vibrating diaphragm group that high temperature resistant material made make the product have high temperature resistant efficiency to adopt special chip to provide direct current bias voltage between back plate and the vibrating diaphragm group, make the microphone volume miniaturation, and the product need not electret technology and ageing treatment, sensitivity can change along with inside bias voltage's adjustment, improved the production efficiency of product, stability and qualification rate, guaranteed the tone quality of product, can realize surface mounting's miniature electric capacity microphone.

Description

A miniature condenser microphone

technical field

The utility model relates to a miniature capacitor microphone, in particular to a surface-mountable miniature capacitor microphone.

Background technique

A condenser microphone is a polyester diaphragm with a metal-plated surface that accepts sound waves as a plate (vibration plate) of the capacitor, and a fixed thick metal plate with a circular groove facing the diaphragm is used as a fixed plate of the capacitor (Back pole plate), between the vibrating plate and the back pole plate, there is an organic material thin-film spacer for insulation, so that a capacitive device with an air dielectric layer is formed between the vibrating plate and the back pole plate. The elastic structure of the thin polyester diaphragm can produce a small axial displacement after picking up the vibration of the external sound wave, thereby changing the air gap between the vibrating plate and the back plate, which results in the charge of the capacitor formed by the above two plates Changes in capacity. When the distance between the two plates decreases, the capacitance increases; when the distance increases, the capacitance decreases. The change of capacitance caused by the change of sound pressure changes the output voltage, so as to obtain the current of specific magnitude and direction. The advantages of condenser microphones are good frequency response, low noise, and low distortion. The disadvantage is that the charge on the two plates of the condenser microphone is maintained by an external polarized power supply (DC bias voltage), so the volume is large, it cannot be miniaturized, and the scope of application is small.

For this reason, people have invented a new type of electret condenser microphone. The electret condenser microphone is a condenser microphone made of electret material. Because the electret itself is charged, this condenser microphone does not need an external bulky pole. The capacitor formed by the two plates can produce an alternating charge change with the change of the gap, and the charge change can be converted into an alternating signal voltage output that changes with vibration through a dedicated IC circuit, which simplifies the operation of the condenser microphone. structure. The electret microphone has good electroacoustic performance, strong anti-vibration ability, low price, and easy miniaturization, so it is widely used in cassette recorders, wireless microphones, and voice control circuits.

With the technical development of new electronic products, there is a tendency to design the electronic products more compactly, and to design such compact products, surface mount technology (SMT) has been widely used. To implement SMT, surface-mounted components need to be exposed to high temperatures during the reflow soldering process. However, ordinary electret condenser microphones are difficult to adopt surface mount technology, even if they are made of high-temperature-resistant materials, the charge value of the electret will be severely attenuated at high temperatures, thereby reducing product sensitivity. In addition, there is a problem in the electret condenser microphone that since permanent charge is formed by forcibly injecting charge into an organic thin film (eg, FEP, etc.) The injected charge is easy to escape, thereby degrading the performance of the electret product.

In order to solve problems such as high temperature resistance, people have invented a new type of silicon semiconductor microphone. The silicon semiconductor microphone is to build a back plate and a diaphragm on a silicon crystal panel, and connect them with an appropriate circuit. Then use chemical etching technology to flatten the diaphragm and simply place it on the base, so that it can completely vibrate freely with the sound. The electric field change formed between the vibrating diaphragm and the back plate generates an electrical signal on the circuit. Silicon semiconductor microphones have two unique properties, namely, their extremely small size and their ability to withstand the high temperatures of reflow ovens. However, due to the small diaphragm of the silicon semiconductor microphone, the sound quality is difficult to reach the level of the original microphone, which limits the application field of the product.

Utility model content

The purpose of the utility model is to provide a miniature condenser microphone that meets the requirements of the SMT process and can be surface mounted.

In order to achieve the above-mentioned purpose, the utility model takes the following technical solutions:

A miniature condenser microphone, comprising a housing with a cavity, a vibrating membrane group with metal plating, a hollow gasket, a back plate, a back plate seat, a connection frame and a circuit board; the bottom panel of the above-mentioned housing and the above-mentioned back The pole plates are respectively provided with at least one through hole through the thickness direction, the above-mentioned vibrating membrane group, hollow gasket and back plate seat are stacked on the bottom panel of the above-mentioned shell in sequence, and the above-mentioned back plate and the above-mentioned connecting frame are stacked on In the above-mentioned back electrode plate seat, the above-mentioned back electrode plate and the above-mentioned vibrating membrane group are kept at a certain distance through the above-mentioned hollow gasket, the above-mentioned circuit board is embedded in the opening of the above-mentioned housing for sealing, and the upper and lower end surfaces of the above-mentioned connection frame are respectively connected to the above-mentioned back plate. The pole plate is electrically connected to the above-mentioned circuit board; the above-mentioned hollow gasket, vibrating membrane group and back plate base are all made of high-temperature-resistant materials, and the inner side of the above-mentioned circuit board is provided with a special chip that can provide DC bias voltage.

The above-mentioned dedicated chip includes a low-input capacitance amplifier, a low-noise charge pump with a built-in constant voltage and oscillator, and a low-pass filter for filtering high-frequency noise of the charge pump. The above-mentioned square diaphragm group and the above-mentioned square back plate One pole plate is electrically connected to the output end of the above-mentioned charge pump, and the other pole plate in the above-mentioned square diaphragm group and the above-mentioned square back plate is electrically connected to the input end of the above-mentioned amplifier, and the output end of the above-mentioned amplifier is the microphone. output.

The above shell, vibrating membrane group, hollow gasket, back plate, back plate seat, connection frame and circuit board are all in a corresponding square shape.

After adopting the above scheme, the utility model has the following advantages compared with the prior art:

1. The back plate seat, gasket and diaphragm group made of high temperature resistant materials make the product have the effect of high temperature resistance, and a special chip is used to provide DC bias voltage between the back plate and the diaphragm group, so that The volume of the microphone is miniaturized, and the product does not require electret process and aging treatment. The sensitivity can be changed with the adjustment of the internal bias voltage, which improves the production efficiency, stability and pass rate of the product, and ensures the sound quality of the product. Mounted miniature condenser microphone.

2. The whole structural spare parts and combination adopt square design, which has the effect of good positioning and large effective area, so as to improve the sound quality.

3. Simple structure and strong practicability.

Description of drawings

Fig. 1 is a schematic diagram of the appearance structure of the utility model;

Fig. 2 is a schematic diagram of the appearance structure of another viewing angle of the utility model;

Fig. 3 is a schematic diagram of the decomposition structure of the utility model;

Fig. 4 is a structural schematic diagram of another viewing angle of the circuit board in the utility model;

Fig. 5 is a schematic cross-sectional structure diagram of the utility model.

Fig. 6 is the schematic circuit diagram of the dedicated chip in the utility model.

Detailed ways

The utility model will be further described below in conjunction with the accompanying drawings and specific embodiments.

Please refer to Fig. 1 to Fig. 5, a kind of miniature condenser microphone of the present utility model, comprises square circuit board 10, square housing 20, square connection frame 30, square back pole seat 40, square back pole plate 50, hollow square Gasket 60 and square diaphragm group 70, wherein:

The square housing 20 has an opening accommodating cavity 21 , and twelve through holes 22 are disposed on the bottom panel 21 of the square housing 20 .

The square vibrating membrane group 70 is placed flat on the bottom panel 21 of the square housing 20. The square vibrating membrane group 70 is made of high temperature resistant material, and its surface has a metal coating, and the coating is facing the square back plate 50; the square vibrating membrane group 70 is formed into one by stretch film ring 71 and mylar 72, and forms one pole of the electric capacity that forms with square back pole plate 50.

The square spacer 60 is an insulator made of high temperature resistant material, which is hollow and placed flat on the square vibrating membrane set 70 to keep a certain distance between the square back plate 50 and the square vibrating membrane set 70 .

The square back plate seat 40 is made of high-temperature-resistant material and is in the shape of a hollow cylinder. The plate base 40 serves to position the square connection frame 30 and the back plate 50 .

The square back plate 50 is the other pole of the capacitor formed with the square diaphragm group 70 , and it is provided with three through holes 51 .

The square connection frame 30 is used to electrically connect the square back plate 50 and the circuit board 10;

The square circuit board 10 is matched with the opening of the accommodation cavity 21 , and the square circuit board 10 is placed flat on the square connection frame 30 and embedded in the opening of the accommodation cavity 21 to seal the accommodation cavity 21 . The inner surface of the square circuit board 10 is provided with a dedicated chip 11, and the square circuit board 10 adopts double-sided copper cladding, so that it has good shielding and anti-interference effects. The dedicated chip 11 includes a low input capacitance amplifier 12, a low-noise charge pump 13 with a built-in constant voltage and an oscillator, a low-pass filter 14 for filtering the high-frequency noise of the charge pump 13, through the amplifier 12 to the capacitor sound head ( Square back plate 50 and square vibrating membrane group 70) capacitance changes with the amount of charge caused by the sound wave, and the output is amplified into a corresponding alternating audio signal; the charge pump 13 provides a DC bias voltage for the capacitor sound head to make it charge A relatively high amount of charge is input; the AC ripple in the DC bias voltage is filtered out by the low-pass filter 14 to ensure the purity of the bias voltage. The special chip 11 can make the product not need electret process and aging treatment, and the sensitivity can be changed with the adjustment of the internal bias voltage to meet the application of various users.

The key point of the design of the utility model is to use a special IC chip and a back plate seat, a gasket, and a vibrating membrane group made of high-temperature-resistant materials, so that the product has the effect of high-temperature resistance, and can realize a surface-mounted miniature capacitor microphone. The whole structural parts and assembly adopt square design, which has the effect of good positioning and large effective area, which can improve the sound quality performance of the product and the accuracy of assembly positioning. In addition, using a dedicated chip, the microphone does not require electret technology and aging treatment, and the sensitivity changes with the adjustment of the internal bias voltage, thereby improving product stability and production efficiency, and reducing the cost of electret technology and aging treatment. The defective products produced improve the qualified rate of products.

The above is only a preferred embodiment of a miniature condenser microphone of the present utility model, and does not limit the technical scope of the present utility model in any way, so any slight modification, Equivalent changes and modifications all still belong to the scope of the technical solution of the present utility model.

Claims (3)

1, a kind of micro capacitance microphone comprises the shell with ccontaining cavity, the vibrating membrane group with coat of metal, hollow pad, back pole plate, backplane panel seat, connection box and wiring board; The bottom panel of above-mentioned shell and above-mentioned back pole plate offer the through hole of at least one impenetrating thickness direction respectively, above-mentioned vibrating membrane group, hollow pad and backplane panel seat are stacked and placed on the bottom panel of above-mentioned shell successively, above-mentioned back pole plate and above-mentioned connection box are stacked and placed in the above-mentioned backplane panel seat successively, make above-mentioned back pole plate and above-mentioned vibrating membrane group keep a determining deviation by above-mentioned hollow pad, the opening that above-mentioned wiring board is embedded at above-mentioned shell seals, and the upper and lower end face of above-mentioned connection box electrically connects with above-mentioned back pole plate and above-mentioned wiring board respectively; It is characterized in that: above-mentioned hollow pad, vibrating membrane group and backplane panel seat are all made by exotic material, and the medial surface of above-mentioned wiring board is provided with the special chip that dc offset voltage can be provided.

2, a kind of micro capacitance microphone according to claim 1, it is characterized in that: above-mentioned special chip comprises low input capacitance amplifier, be built-in with the low noise charging pump of constant voltage and oscillator and be used for the low pass filter of filtering charge pump high frequency noise, a pole plate in above-mentioned square vibrating membrane group and the above-mentioned square back pole plate is electrically connected with above-mentioned charging delivery side of pump, another pole plate in above-mentioned square vibrating membrane group and the above-mentioned square back pole plate is electrically connected with above-mentioned amplifier input terminal, and the output of above-mentioned amplifier is the output of microphone.

3, a kind of micro capacitance microphone according to claim 1 and 2 is characterized in that: above-mentioned shell, vibrating membrane group, hollow pad, back pole plate, backplane panel seat, connection box and wiring board are all corresponding square.

Images