TWI491272B - Double-layered electret electroacoustic transducers and electronic devices containing the same - Google Patents

Description

Double-layer electret electroacoustic conversion device and electronic device with electret speaker

The present invention relates to an electret electroacoustic transducer, and more particularly to an electroacoustic transducer comprising a double layer electret and an electronic device having an electret speaker.

Traditional loudspeakers are mainly divided into moving coil speakers, piezoelectric speakers and electrostatic speakers. The moving coil type speaker mainly uses the interaction of the magnetic field, the current and the force at right angles to control the piston-type repetitive motion of the diaphragm, and the volume cannot be reduced, so that it cannot meet the demand for thinning and thinning of the future 3C products.

Piezoelectric speakers use the piezoelectric effect. When an electric field is applied to the piezoelectric material, the piezoelectric material is deformed and the diaphragm is excited. However, the resonant frequency required for the piezoelectric material is high and the available bandwidth is insufficient. Therefore, the applicable fields are limited.

The principle of the electrostatic speaker is to hold a conductive diaphragm between two electrode plates with openings to form a capacitor-like structure, by supplying a DC bias to the conductive diaphragm, and supplying the two electrodes simultaneously to synchronize the positive and negative phases. The alternating voltage is transmitted through the electrostatic force generated by the positive and negative charges to drive the conductive diaphragm and radiate the sound. The conductive diaphragm used in the electrostatic speaker is extremely thin and light, and has the advantages of fast transient response, high resolution, low distortion, and immunity from electromagnetic influence.

Electret electroacoustic transducers are generally applicable to electrostatic speakers. After the electret diaphragm element is used for charging, it can maintain a high positive and negative or the same positive or negative bias for a long time, and the audio amplifier only needs to output a small AC audio power to achieve high quality. The sound field effect. Therefore, the electret electro-acoustic converter not only meets the requirements of lighter and lighter quality in the future market, but also has the advantages of power saving and cost saving.

In view of the above, one of the objects of the embodiments of the present invention is to provide an electroacoustic transducer device including a double-layer electret that meets the requirements of thinness and high sound quality.

According to an embodiment of the present invention, a double-layer electret electroacoustic conversion device includes: a first electrode formed on a first insulating plate having a plurality of holes; a double-layer electret diaphragm, and the first An electrode is disposed opposite to each other, wherein an aluminum plating layer is interposed between the double-layer electret diaphragms to form a laminated structure; and a first isolation structure is disposed between the first electrode and the double-layer electret diaphragm a second electrode formed on the second insulating plate having a plurality of holes opposite to the double-layer electret diaphragm; and a second isolation structure disposed on the double-layer electret diaphragm and the second Between the electrodes; and wherein, during operation, an alternating bias applied between the first electrode and the second electrode provides an electric field that drives the vibration of the electret diaphragm.

According to another embodiment of the present invention, a double-layer electret electroacoustic conversion device includes: a first electrode formed on a first insulating plate having a plurality of holes; a double-layer electret diaphragm, and the first An electrode is disposed opposite to each other, wherein an aluminum plating layer is interposed between the double-layer electret diaphragms to form a laminated structure; a first protective film is disposed on the double-layer electret diaphragm to prevent the double-layer resident The charge remaining on the surface of the polar body diaphragm is lost; the first isolation structure is disposed between the first electrode and the double layer electret diaphragm; and the second electrode is formed on the second insulating board having a plurality of holes And facing the double-layer electret diaphragm; the second protective film is disposed on the first and second electrodes to prevent the surface of the electret diaphragm from being in contact with the electret diaphragm a second isolation structure disposed between the double-layer electret diaphragm and the second electrode; and an adjusting member disposed on the first and second electrodes to assist the double-layer electret a vibration of the diaphragm; wherein, during operation, the application between the first electrode and the second electrode Providing a bias electric field to drive the vibration of the electret diaphragm.

According to another embodiment of the present invention, an electronic device with an electret speaker is provided, comprising: the double-layer electret electroacoustic conversion device of the previous embodiment; the control device accepting the incoming signal of the input device and converting it into a drive And a driving power source, wherein an alternating bias voltage is applied between the first electrode and the second electrode according to the driving signal to provide an electric field for driving the vibration of the electret diaphragm.

In order to make the invention more apparent, the following detailed description of the embodiments and the accompanying drawings are as follows:

The following is a detailed description of the embodiments and examples accompanying the drawings, which are the basis of the present invention. In the drawings or the description of the specification, the same drawing numbers are used for similar or identical parts. In the drawings, the shape or thickness of the embodiment may be expanded and simplified or conveniently indicated. In addition, the components of the drawings will be described separately, and it is noted that the components not shown or described in the drawings are known to those of ordinary skill in the art, and in particular, The examples are merely illustrative of specific ways of using the invention and are not intended to limit the invention.

Figure 1 is a schematic cross-sectional view showing a conventional electret electroacoustic transducer. Referring to FIG. 1 , the conventional electret electroacoustic conversion device 100 includes an electret diaphragm 120 , and two electrode plates 110 and 130 respectively disposed on opposite sides of the electret diaphragm 120 , and the insulating spacer structures 140 and 145 . They are respectively disposed between the electret diaphragm 120 and the electrode plate 110 and between the electret diaphragm 120 and the electrode plate 130. When the electrode plates 110 and 130 respectively receive the in-phase or reverse-phase AC audio voltage output by the AC power source 150 (for example, an audio amplifier), the electret diaphragm 120 generates a push-pull due to the electrostatic force. effect.

The electrode plates 110, 130 are typically metal plates or metal meshes comprising a plurality of holes or sound holes (not shown). There is sufficient space between the electrode plates 110, 130 and the electret diaphragm 120 for the electret diaphragm 120 to vibrate and push the surrounding air to transmit sound through the holes or sound holes of the electrode plates 110, 130.

The electret diaphragm 120 is made of an electret material and has a relatively high bias on the surface for a long time after charging. In particular, an electret material refers to a static charge that can be retained for a long time after undergoing electrification treatment of a dielectric material.

2 is a cross-sectional structural view showing a double-layer electret electroacoustic transducer according to an embodiment of the present invention. Referring to FIG. 2, the double-layer electret electroacoustic conversion device 200 includes a first electrode structure 210 having a first electrode 214 formed on a first insulating plate 212 having a plurality of holes (not shown). The double-layer electret diaphragm comprises two layers of electret diaphragms 222 and 226 disposed opposite to the first electrode, and a metal plating layer 224, such as an aluminum coating layer, is interposed between the double-layer electret diaphragms. The laminated electret diaphragm structure 220 is laminated. The first electrode 214 is disposed between the first insulating plate 212 and the electret diaphragm. The first isolation structure 240 is disposed between the first electrode and the double-layer electret diaphragm to provide sufficient space for the electret diaphragm structure 220 to vibrate to push ambient air through the hole or sound of the first electrode structure 210. The hole makes a sound. The second electrode 234 is disposed between the second insulating plate 232 and the electret diaphragm. The second electrode structure 230 has a second electrode 234 formed on the second insulating plate 232 having a plurality of holes, and is disposed opposite to the double-layer electret diaphragm. The second isolation structure 245 is disposed between the double-layer electret diaphragm and the second electrode to provide sufficient space for the electret diaphragm structure 220 to vibrate to push ambient air through the hole or sound of the second electrode structure 230. The hole makes a sound. In operation, an in-phase or reverse-phase AC audio voltage output by an AC power source 250 (eg, an audio amplifier), an AC bias applied between the first electrode 214 and the second electrode 234 provides driving of the electret diaphragm vibration Electric field.

According to an embodiment of the invention, the first and second insulating plates 212, 232 are rigid or rigid polymer substrates. For example, the first and second insulating plates 212, 232 are preferably printed circuit boards.

The electret material constituting the electret diaphragm structure 220 may be a fluorine-containing polymer material, and fluorine has the strongest electrical property. Therefore, the charge of the electret diaphragm structure 220 can be charged. Further, a plurality of nano-micron holes may alternatively be formed on the electret diaphragm structure 220 to substantially increase the surface area of the electret diaphragm structure 220. The electret material is preferably a fluorine-containing organic polymer material or a fluorine-containing organic inorganic polymer. The fluorine-containing polymer material includes expanded polytetrafluoroethylene (ePTFE), side-chained polytetrafluoroethylene (PFA), fluorinated ethylene propylene (FEP), and ethylene-tetrafluoroethylene polymer ( ETFE), and ethylene-trifluoroethylene (ECTFE) copolymer. [note: delete the deleted sentence. Reason is that we don’t want to cite patents owned by another party.]

The purpose of the first isolation structure 240 is to separate the electret diaphragm structure 220 from the first electrode structure 210 and to produce an electrical insulation effect. The first isolation structure 240 may be selectively bonded to the electret diaphragm structure 220 by a bonding material such as epoxy resin to be divided into a plurality of regions. After being fixed, the electret diaphragm structure 220 is maintained at a certain tension.

3 is a cross-sectional structural view showing a single-layer electret electroacoustic transducer according to another embodiment of the present invention. Referring to FIG. 3, the double-layer electret electroacoustic conversion device 300 includes a first electrode structure 310 having a first electrode 314 formed on a first insulating plate 312 having a plurality of holes (not shown). The double-layer electret diaphragms 322 and 326 are disposed opposite to the first electrode, wherein a metal plating layer 324, such as an aluminum plating layer, is interposed between the double-layer electret diaphragms to form a laminated electret diaphragm structure 320. . The protective films 321 and 327 are respectively disposed on both side surfaces of the double-layer electret diaphragm to prevent the loss of electric charge resident on the surface of the double-layer electret diaphragm. The material of the protective films 321 and 327 may be green paint, asphalt paint or fluorine-containing polymer plating. The first isolation structure 340 is disposed between the first electrode and the double-layer electret diaphragm to provide sufficient space for the electret diaphragm structure 320 to vibrate to push ambient air through the hole or sound of the first electrode structure 310. The hole makes a sound. The second electrode structure 330 has a second electrode 334 formed on the second insulating plate 332 having a plurality of holes, and disposed opposite to the double-layer electret diaphragm. The protective films 316 and 336 are respectively disposed on the first electrode 314 and the second electrode 334 to prevent loss of electric charge resident on the surface of the electret diaphragm when contact with the electret diaphragm. The material of the protective films 316 and 336 may be a green paint, an asphalt paint or a fluorine-containing polymer plating layer, and the tip discharge of the surface of the first electrode 310 can be effectively prevented. The second isolation structure 345 is disposed between the double-layer electret diaphragm and the second electrode to provide sufficient space for the electret diaphragm electret diaphragm 320 to vibrate to push ambient air through the second electrode structure 330. The hole or sound hole makes a sound.

In operation, an in-phase or reverse-phase AC audio voltage output by an AC power source 350 (eg, an audio amplifier), an AC bias applied between the first electrode 314 and the second electrode 334 provides driving of the electret diaphragm vibration Electric field.

4A is a cross-sectional view showing the structure of a double-layer electret electroacoustic transducer according to another embodiment of the present invention. Referring to FIG. 4A, the double-layer electret electroacoustic conversion device 400a includes a first electrode structure 410 having a first electrode 414 formed on a first insulating plate 412 having a plurality of holes (not shown). The double-layer electret diaphragms 422 and 426 are disposed opposite to the first electrode, wherein a metal plating layer 424, such as an aluminum plating layer, is interposed between the double-layer electret diaphragms to form a laminated electret diaphragm structure 420. . The first isolation structure 440 is disposed between the first electrode and the double-layer electret diaphragm to provide sufficient space for the electret diaphragm structure 420 to vibrate to push ambient air through the hole or sound of the first electrode structure 410. The hole makes a sound. The second electrode structure 430 has a second electrode 434 formed on the second insulating plate 432 having a plurality of holes, which is disposed opposite to the double-layer electret diaphragm. The protective films 416 and 436 are respectively disposed on the first electrode 414 and the second electrode 434 to prevent loss of charge remaining on the surface of the electret diaphragm when it is in contact with the electret diaphragm. The protective films 416, 436 may be insulating varnish, green lacquer, asphalt lacquer or fluoropolymer coating. The second isolation structure 445 is disposed between the double-layer electret diaphragm and the second electrode to provide sufficient space for the electret diaphragm structure 420 to vibrate to push ambient air through the hole or sound of the second electrode structure 430. The hole makes a sound. The adjusting member 460 is respectively disposed on the first electrode 414 and the second electrode 434, or the adjusting member is disposed on the two electrodes to assist the vibration of the double-layer electret diaphragm. The main purpose of the adjusting member in the embodiment is to assist in adjusting the vibration amplitude and angle of the electret diaphragm, and avoiding the vibration of the electret diaphragm touching the electrode to generate noise. In another embodiment, each of the electret electroacoustic conversion device units defined by the isolation structure may include a plurality of adjustment members 460' (as shown in FIG. 4B) to vibrate the electret diaphragm. The angle and amplitude achieve the best results. The number and height of the adjustment parts can be adjusted according to the actual product application, but still limited to not touching the electret diaphragm.

In operation, an in-phase or reverse-phase AC audio voltage output by an AC power source 450 (eg, an audio amplifier), an AC bias applied between the first electrode 414 and the second electrode 434 provides driving of the electret diaphragm vibration Electric field.

It should be noted that in addition to the above embodiments, there are other materials, components and structures suitable for the double-layer electret electroacoustic conversion device constituting the present invention, which should be the ones having ordinary knowledge in the technical field of the present invention. It can be easily replaced or replaced, and should still fall within the scope of the present invention. For the sake of brevity, a detailed description thereof will be omitted here.

An advantage of the double-layer electret electroacoustic transducer of the above embodiment of the present invention is that the electrodes are disposed on an insulating plate that is flat and has a plurality of holes. Compared with the use of the metal mesh electrode, the tip discharge is not caused in the case of increasing the driving voltage, thereby significantly improving the sound pressure level (SPL) tolerance of the electret electroacoustic converter. Therefore, the noise can be effectively reduced and the sound quality can be improved, so that it has the characteristics of fast transient response, high resolution, low distortion and no electromagnetic influence.

It should be understood that the embodiment of the present invention further provides an electronic device with an electret speaker, which is developed for system interface technology of an application product, and is widely used in electro-acoustic components of electronic products, including communication, information, consumer electronics, and The market for electroacoustic products in other fields.

FIG. 5 is a block diagram showing an electronic device with an electret speaker according to another embodiment of the present invention. The electronic device 500 with an electret speaker includes a double-layer electret electroacoustic conversion device 200, 300 or 400 as described in the previous embodiment, and the control device 510 receives the incoming signal from the input device and converts it into a driving signal. And driving power supply 520, according to the driving signal, applying an alternating bias voltage between the first electrode and the second electrode of the electret electroacoustic converting device 200, 300 or 400 to provide an electric field for driving the vibration of the electret diaphragm. Preferred examples of the electronic device 500 include a tablet computer, a notebook computer, an electronic book, an electronic photo frame, and a cover for the above device.

The present invention has been disclosed in the above various embodiments, but it is not intended to limit the scope of the present invention. Any one of ordinary skill in the art can make a few changes and refinements without departing from the spirit and scope of the present invention. . The scope of the invention is defined by the scope of the appended claims.

100. . . Traditional electret electroacoustic conversion device

110, 130. . . Electrode plate

120. . . Electret diaphragm

140, 145. . . Insulation spacer structure

150. . . AC power

200, 300, 400a, 400b. . . Double-layer electret electroacoustic conversion device

210, 310, 410. . . First electrode structure

212, 312, 412. . . First insulation board

214, 314, 414. . . First electrode

220, 320, 420. . . Laminated electret diaphragm structure

222, 322, 422. . . Electret

224, 324, 424. . . Metal plating

226, 326, 426. . . Electret

230, 330, 430. . . Second electrode structure

262, 332, 432. . . Second insulation board

234, 334, 434. . . Second electrode

240, 340, 440. . . First isolation structure

245, 345, 445. . . Second isolation structure

250, 350, 450. . . AC power

316, 336. . . First protective film

321, 327. . . Second protective film

416, 436. . . Protective film

460, 460’. . . Adjustment piece

500. . . Electronic device with electret speaker

510. . . Control device

520. . . Drive power

Figure 1 is a schematic cross-sectional view showing a conventional electret electroacoustic transducer.

2 is a cross-sectional structural view showing a double-layer electret electroacoustic transducer according to an embodiment of the present invention.

3 is a cross-sectional structural view showing a double-layer electret electroacoustic transducer according to another embodiment of the present invention.

4A and 4B are schematic cross-sectional views showing a double-layer electret electroacoustic transducer according to another embodiment of the present invention.

FIG. 5 is a block diagram showing an electronic device with an electret speaker according to another embodiment of the present invention.

300. . . Double-layer electret electroacoustic conversion device

310. . . First electrode structure

312. . . First insulation board

314. . . First electrode

316, 336. . . First protective film

320. . . Laminated electret diaphragm structure

321, 327. . . Second protective film

322. . . Electret

324. . . Metal plating

326. . . Electret

330. . . Second electrode structure

332. . . Second insulation board

334. . . Second electrode

340. . . First isolation structure

345. . . Second isolation structure

350. . . AC power

Claims (17)

A double-layer electret electroacoustic conversion device includes: a first electrode formed on a first insulating plate having a plurality of holes; and a double-layer electret diaphragm disposed opposite the first electrode, wherein the double A metal plating layer is interposed between the layer electret diaphragms to form a laminated electret diaphragm structure; a protective film is disposed on the double layer electret diaphragm to prevent the double layer electret diaphragm surface a resident charge is lost; a first isolation structure is disposed between the first electrode and the double layer electret diaphragm; and a second electrode is formed on the second insulating plate having a plurality of holes, and the double layer The electret diaphragm is disposed opposite to each other; the second isolation structure is disposed between the double layer electret diaphragm and the second electrode; and in operation, is applied to the first electrode and the second electrode The alternating bias voltage provides an electric field that drives the vibration of the electret diaphragm. The double-layer electret electroacoustic conversion device according to claim 1, wherein the first and second insulating plates are rigid or rigid polymer substrates. The double-layer electret electroacoustic conversion device of claim 1, wherein the first and second insulating plates are printed circuit boards. The double-layer electret electroacoustic transducer according to claim 1, wherein the double-layer electret diaphragm comprises a fluorine containing polymer. The double-layer electret electroacoustic conversion device according to claim 4, wherein the fluorine-containing polymer material comprises expanded polytetrafluoroethylene (ePTFE) and side chain polytetrafluoroethylene (PFA). , fluorinated ethylene propylene (FEP), ethylene-tetrafluoroethylene polymer (ETFE), and ethylene-trifluoroethylene (ECTFE) copolymer. The double-layer electret electroacoustic conversion device according to claim 1, wherein the protective film comprises green paint, asphalt paint or fluorine-containing polymer plating. The double-layer electret electroacoustic conversion device according to claim 1, further comprising a protective film disposed on the first and second electrodes to prevent contact with the electret diaphragm The charge remaining on the surface of the body membrane is lost. The double-layer electret electroacoustic conversion device according to claim 1, further comprising an adjusting member disposed on the first or second electrode to assist the vibration of the double-layer electret diaphragm. A double-layer electret electroacoustic conversion device includes: a first electrode formed on a first insulating plate having a plurality of holes; and a double-layer electret diaphragm disposed opposite the first electrode, wherein the double An aluminum plating layer is interposed between the layer electret diaphragms to form a laminated electret diaphragm structure; a first protective film is disposed on the double layer electret diaphragm to prevent the double layer electret diaphragm The charge remaining on the surface is lost; the first isolation structure is disposed between the first electrode and the double layer electret diaphragm; a second electrode is formed on the second insulating plate having a plurality of holes opposite to the double-layer electret diaphragm; and the second isolation structure is disposed on the double-layer electret diaphragm and the second electrode And at least one adjusting member disposed on the first and second electrodes to assist the vibration of the double-layer electret diaphragm; wherein, during operation, between the first electrode and the second electrode The AC bias voltage provides an electric field that drives the vibration of the electret diaphragm. The double-layer electret electroacoustic conversion device according to claim 9, wherein the first and second electrodes are rigid or rigid polymer substrates. The double-layer electret electroacoustic conversion device of claim 9, wherein the first and second insulating plates are printed circuit boards. The double-layer electret electroacoustic conversion device according to claim 9, wherein the double-layer electret diaphragm comprises fluorine containing polymers. The double-layer electret electroacoustic conversion device according to claim 12, wherein the fluorine-containing polymer material comprises expanded polytetrafluoroethylene (ePTFE) and side chain polytetrafluoroethylene (PFA). , fluorinated ethylene propylene (FEP), ethylene-tetrafluoroethylene polymer (ETFE), and ethylene-trifluoroethylene (ECTFE) copolymer. The double-layer electret electroacoustic conversion device according to claim 9, wherein the first and second protective films comprise green paint, asphalt paint or Fluorinated polymer coating. An electronic device with an electret speaker, comprising: the double-layer electret electroacoustic conversion device according to claim 1 or 9; the control device receiving the signal input from the input device and converting the signal into a driving signal; And driving power supply, applying an alternating bias voltage between the first electrode and the second electrode according to the driving signal to provide an electric field for driving the vibration of the electret diaphragm. The electronic device with an electret speaker according to claim 15, wherein the electronic device comprises a tablet computer, a notebook computer, an electronic book, an electronic photo frame, and a cover for the device. The double-layer electret electroacoustic conversion device according to claim 9, further comprising a second protective film disposed on the first and second electrodes to prevent contact with the electret diaphragm The charge remaining on the surface of the electret diaphragm is lost.