TWI531250B - Flat plane speaker - Google Patents

Description

Flat speaker

The present invention relates to a flat panel speaker, and more particularly to a piezoelectric flat panel speaker.

The working principle of piezoelectric flat panel loudspeakers is based on the inverse piezoelectric effect of certain piezoelectric materials. That is, when an alternating electric field is applied to the piezoelectric material, the piezoelectric material undergoes mechanical deformation correspondingly, thereby urging the surrounding air to vibrate.

The basic structure of a piezoelectric flat panel speaker of the prior art generally includes a piezoelectric element and first and second electrodes electrically connected to and spaced apart from the piezoelectric element. In order to ensure good electrical connection performance between the first electrode and the second electrode and the piezoelectric element during operation of the piezoelectric speaker, a metal film is generally prepared as the first and second electrodes on the piezoelectric element by a printing process. However, during the operation of the piezoelectric flat panel speaker, the piezoelectric element is mechanically deformed, and the electrode made of the metal material has poor fatigue resistance, so that it is susceptible to fatigue fracture due to the vibration of the piezoelectric element during operation.

In addition, the piezoelectric flat panel speaker of the prior art also uses an indium tin oxide (ITO) layer (hereinafter referred to as an ITO layer) having a conductive property as an electrode of a piezoelectric flat panel speaker, thereby preparing a transparent piezoelectric flat panel speaker. . However, the use of ITO as an electrode also has the disadvantage of being inflexible, has poor fatigue resistance, and is susceptible to fatigue fracture due to the vibration of the piezoelectric element. At the same time, the ITO layer needs to be deposited on the piezoelectric element in a high-temperature vacuum environment. On the surface, since the piezoelectric element itself is not resistant to high temperatures, The formation process of the ITO electrode easily causes the piezoelectric property of the piezoelectric element to deteriorate.

US Patent Application No. US20070081681A1, issued Apr. 12, 2007, discloses a piezoelectric flat panel speaker using a carbon nanotube film as an electrode, which is formed by containing a carbon nanotube The solution is formed on both surfaces of the piezoelectric element by coating, and then the solvent is evaporated at 50 ° C to 70 ° C. The carbon nanotube film does not need to be combined with the piezoelectric element under high temperature conditions. Therefore, the preparation process does not affect the piezoelectric properties of the piezoelectric element. However, in the carbon nanotube film formed by the above method, the carbon nanotubes are disorderly arranged, which is disadvantageous for exerting the excellent longitudinal conductivity of the carbon nanotube, thereby affecting the response speed of the entire piezoelectric flat panel speaker.

In view of this, it is necessary to provide a flat panel speaker with a relatively fast response speed.

A flat panel speaker comprising: a piezoelectric element including a first surface and a second surface opposite the first surface; a first electrode, the first electrode and the piezoelectric The element is electrically connected and disposed on the first surface thereof; a second electrode electrically connected to the piezoelectric element and disposed on the second surface of the piezoelectric element; wherein the first electrode and the first electrode The two electrodes are all a carbon nanotube structure, and the carbon nanotube structure comprises a plurality of carbon nanotubes arranged substantially in the same direction.

A flat panel speaker comprising: a piezoelectric element including a first surface and a second surface opposite the first surface; a first electrode, the first electrode and the piezoelectric The element is electrically connected and disposed on the first surface thereof; a second electrode electrically connected to the piezoelectric element and disposed on the second surface of the piezoelectric element; a diaphragm, the diaphragm is disposed On the first electrode or the second electricity a surface of the pole; wherein the first electrode and the second electrode are a carbon nanotube structure, and the carbon nanotube structure comprises a plurality of carbon nanotubes arranged substantially in the same direction.

Compared with the prior art, the flat panel speaker provided by the present invention has the following advantages: the flat panel speaker adopts a carbon nanotube structure as a first electrode and a second electrode, and the carbon nanotube structure includes a plurality of substantially the same direction The aligned carbon nanotubes have good electrical conductivity, so the entire flat panel speaker has better sensitivity and stability.

10,20‧‧‧ flat speaker

111,145‧‧‧Nano carbon tube

112‧‧‧ Conductive metal layer

1121‧‧‧Infiltration layer

1122‧‧‧ Conductive layer

12,22‧‧‧first electrode

14,24‧‧‧second electrode

143‧‧‧Nano carbon nanotube fragments

16,26‧‧‧Piezoelectric components

162,262‧‧‧ first surface

164,264‧‧‧second surface

18,28‧‧‧Audio signal input device

29‧‧‧ Diaphragm

1 is a schematic structural view of a flat panel speaker according to a first embodiment of the present invention.

2 is a schematic view showing the structure of a carbon nanotube film obtained by the first embodiment of the present invention.

Fig. 3 is a scanning electron micrograph of a carbon nanotube film taken in a first embodiment of the present invention.

4 is a schematic view showing the structure of a carbon nanotube coated with a conductive metal layer in the first embodiment of the present invention.

Figure 5 is a transmission electron micrograph of a carbon nanotube coated with a conductive metal layer in the first embodiment of the present invention.

FIG. 6 is a schematic structural view of a flat panel speaker according to a second embodiment of the present invention.

Hereinafter, a flat panel speaker according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1 , a first embodiment of the present invention provides a flat panel speaker 10 . The flat panel speaker 10 includes a piezoelectric element 16 including a first surface 162 and one opposite to the first surface 162 . a second surface 164; a first electrode 12 electrically connected to the piezoelectric element 16 and disposed on the first surface 162 thereof; a second electrode 14, the second electrode 14 and the piezoelectric Component 16 is electrically connected and set On its second surface 164.

The piezoelectric element 16 is a piezoelectric crystal, a piezoelectric ceramic, a piezoelectric semiconductor, or a piezoelectric polymer material. The material of the piezoelectric crystal may be lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ), lithium niobate (LiGeO ₃ ), lithium gallium hydride (LiGaO ₃ ) or bismuth ruthenate (Bi ₁₂ GeO ₂₀ ). The material of the piezoelectric ceramic may be barium titanate (BaTiO ₃ ), lead zirconate titanate, tantalate-based piezoelectric ceramic or lead magnesium niobate piezoelectric ceramic, etc., and the material of the piezoelectric semiconductor may be Zinc sulfide (ZnS), cadmium telluride (CdTe), zinc oxide (ZnO), cadmium sulfide (CdS), zinc telluride (ZnTe) or gallium arsenide (GaAs), etc., the piezoelectric polymer material may be poly Difluoroethylene (PVDF), polyvinyl fluoride (PVF), polyvinyl chloride (PVC), and the like. The thickness of the piezoelectric element 16 is not limited and may be determined according to actual needs.

The first electrode 12 and the second electrode 14 are both carbon nanotube structures, and the carbon nanotube structure comprises a plurality of carbon nanotubes arranged substantially in the same direction, and the carbon nanotube structure is The carbon nanotubes are evenly distributed. In addition, the plurality of carbon nanotubes of the first electrode 12 are substantially parallel to the first surface of the piezoelectric element 16, and the plurality of carbon nanotubes of the second electrode 14 are substantially parallel to the piezoelectric element The second surface of 16. And the carbon nanotube comprises one or more of a single-walled carbon nanotube, a double-walled carbon nanotube, and a multi-walled carbon nanotube. The single-walled carbon nanotube has a diameter of 0.5 nm to 10 nm, the double-walled carbon nanotube has a diameter of 1.0 nm to 15 nm, and the multi-walled carbon nanotube has a diameter of 1.5 nm to 50 nm. Nano.

The carbon nanotube structure is a self-supporting structure. The so-called self-supporting structure means that the carbon nanotube structure can maintain its own specific shape without being supported by a support. The self-supporting structure includes a plurality of carbon nanotubes that are attracted to each other by a van der Waals force, so that the carbon nanotube structure has a specific shape. specifically, The carbon nanotube structure includes a carbon nanotube film.

The carbon nanotube film may be a carbon nanotube film, a ribbon carbon nanotube film or a long carbon nanotube film.

The carbon nanotube film is directly obtained by drawing an array of carbon nanotubes, preferably directly by drawing a super-sequential carbon nanotube array. The carbon nanotube film comprises a plurality of carbon nanotubes arranged end to end in a preferred orientation in the same direction, please refer to FIG. 2 and FIG. 3, specifically, each nano carbon tube film comprises a plurality of continuous and oriented Arranged carbon nanotube segments 143, the plurality of carbon nanotube segments 143 are connected end to end by van der Waals force, and each of the carbon nanotube segments 143 includes a plurality of substantially parallel carbon nanotubes 145, the plurality of The mutually parallel carbon nanotubes 145 are tightly coupled by van der Waals forces. The carbon nanotube segment 143 has any width, thickness, uniformity, and shape. The carbon nanotube film has a thickness of 0.5 nm to 100 μm. For the structure of the carbon nanotube film and the preparation method thereof, refer to Taiwan Patent Application No. 200833862, which was published on August 16, 2008 by Fan Shoushan et al. In order to save space, only the above is cited, but all the technical disclosures of the above application are also considered as part of the technical disclosure of the present application.

The ribbon-shaped carbon nanotube film is obtained by pouring an elongated carbon nanotube array perpendicular to the length of the carbon nanotube array on a substrate surface. The ribbon-shaped carbon nanotube film comprises a plurality of carbon nanotubes arranged in a preferred orientation. The plurality of carbon nanotubes are arranged side by side in parallel with each other and closely coupled by van der Waals force, the plurality of carbon nanotubes having substantially equal lengths and having a length in the order of millimeters. The width of the ribbon-shaped carbon nanotube membrane is equal to the length of the carbon nanotube, so that at least one carbon nanotube in the ribbon-shaped carbon nanotube array extends from one end of the ribbon-shaped carbon nanotube membrane to another One end, thus spanning the entire strip of carbon nanotube membrane. The width of the ribbon-shaped carbon nanotube film is affected by The length of the carbon nanotube is limited. Preferably, the length of the carbon nanotube is from 1 mm to 10 mm. The structure of the ribbon-shaped carbon nanotube film and the preparation method thereof are described in Taiwan Patent Application No. 97,212,118, filed on Jun. 13, 2008. In order to save space, only the above is cited, but all the technical disclosures of the above application are also considered as part of the technical disclosure of the present application.

The long carbon nanotube film is obtained by a kite-flying method, in which a plurality of ultra-long carbon nanotubes grown on a substrate float on a receiving substrate under the action of a carbon source gas flow, and then stop. A carbon source gas is introduced to form the long carbon nanotube film over the receiving substrate. The long carbon nanotube film comprises a plurality of ultra-long carbon nanotubes parallel to the surface of the carbon nanotube film, and the plurality of carbon nanotubes are arranged substantially parallel to each other. The plurality of super-long carbon nanotubes may have a length greater than 10 cm. The distance between two adjacent ultra-long carbon nanotubes in the carbon nanotube film is less than 5 micrometers, and the adjacent two super-long carbon nanotubes are closely connected by van der Waals force. The structure of the long carbon nanotube film and the preparation method thereof are described in Taiwan Patent Application No. 97107078, which was filed on Feb. 29, 2008. In order to save space, only the above is cited, but all the technical disclosures of the above application are also considered as part of the technical disclosure of the present application.

When the carbon nanotube structure comprises the plurality of carbon nanotube membranes, the plurality of carbon nanotube membranes can be coplanar and without gap laying or/and lamination to prepare nanocarbons of different areas and thicknesses. Tube structure. In a carbon nanotube structure composed of a plurality of mutually stacked carbon nanotube membranes, the arrangement of the carbon nanotubes in the adjacent two carbon nanotube membranes is the same or different, preferably a carbon nanotube The arrangement direction is the same.

The thickness of the above-mentioned carbon nanotube structure can be selected as needed while ensuring strength. Preferably, the carbon nanotube structure has a thickness of 0.5 nm to 1 mm. When the above carbon nanotube structure has a small thickness, such as 0.5 nm to 99 nm, the carbon nanotube structure It has good transparency and its light transmittance can reach 86%~95%. In addition, since the carbon nanotubes in the above-mentioned carbon nanotube structure are mutually attracted by the van der Waals force to form a self-supporting structure, the self-supporting carbon nanotube structure as a whole has a large strength. At the same time, since the longitudinal conductivity of the carbon nanotubes is good, and the plurality of carbon nanotubes in the carbon nanotube structure of the embodiment are arranged substantially in the same direction, the carbon nanotube structure has a high uniformity. And the first electrode 12 and the second electrode 14 formed of the carbon nanotube structure have good electrical conductivity, so that the flat panel speaker 10 has high stability and sensitivity.

The carbon nanotube structures are bonded to the first surface 162 and the second surface 164 of the piezoelectric element 16 by conductive adhesives, respectively. The plurality of carbon nanotubes in the carbon nanotube structure are substantially parallel to the first surface 162 and the second surface 164 of the piezoelectric element 16. Since the carbon nanotube structure has strong light transmittance perpendicular to the length of the carbon nanotube, the nanocarbon tube layer is composed of a carbon nanotube layer having the same thickness and composed of a disordered arrangement of carbon nanotubes. The carbon nanotube structure has better transparency; in addition, since the carbon nanotube itself has better flexibility and bending resistance, the plurality of carbon nanotubes in the carbon nanotube structure are substantially parallel in the same direction. Arranged, and the adjacent carbon nanotubes are connected end to end by Van der Waals force, so that the carbon nanotube structure as a whole has good flexibility and bending resistance. Therefore, according to actual needs, a flat panel speaker 10 which is transparent, resistant to bending and has good sensitivity and stability can be formed. In addition, the carbon nanotube structure does not need to be prepared under high temperature conditions, and does not need complicated equipment, so the preparation process is simple and suitable for industrial production.

Referring to FIG. 4 and FIG. 5, further, the surface of the carbon nanotube 111 in the carbon nanotube structure may be coated with at least one conductive metal layer 112. The material of the at least one conductive metal layer 112 may include one or more of iron, cobalt, nickel, palladium, titanium, copper, silver, gold, and platinum. . The at least one conductive metal layer 112 may have a thickness of from 1 nm to 100 nm, preferably less than 20 nm. In this embodiment, the at least one conductive metal layer 112 includes, from the inside to the outside, a wetting layer 1121 having good wettability with the carbon nanotubes and a conductive layer 1122 having a high conductivity, the wetting layer 1121 and the conductive layer. 1122 is sequentially coated on the surface of the carbon nanotube 111, the wetting layer 1121 is a nickel layer, the conductive layer 1122 is a gold layer, the thickness of the nickel layer is about 2 nm, and the thickness of the gold layer is about 15 Nano. It can be understood that the at least one conductive metal layer 112 may further include a transition layer (not shown) and an oxidation resistant layer (not shown) disposed between the wetting layer 1121 and the conductive layer 1122. Both of them have a good combination with the wetting layer 1121 and the conductive layer 1122. The anti-oxidation layer is coated on the surface of the conductive layer 1122 and has high oxidation resistance.

The at least one conductive metal layer 112 may be formed on the surface of the carbon nanotube 111 in the carbon nanotube structure by an evaporation method, a sputtering method, a deposition method, an electroplating method, or an electroless plating method. Specifically, when the carbon nanotube structure comprises a plurality of stacked carbon nanotube films, the surface of the carbon nanotubes 111 of each of the carbon nanotube films may be first vapor-deposited to form a plurality of conductive metal layers 112. The carbon nanotube composite membrane, and the plurality of carbon nanotube composite membranes are overlapped with each other. For the specific preparation method of the nanocarbon nanotube composite membrane, please refer to No. 97108084 filed by Fan Shoushan et al. on March 7, 2008. Taiwan patent application. Table 1 shows the comparison of the sheet resistances before and after the formation of different conductive metal layers 112 on the surface of the carbon nanotubes 111 when the carbon nanotube structure is a single-layer carbon nanotube film. It can be found that in the structure of the carbon nanotubes. Forming a conductive metal layer 112 on the surface of the carbon nanotube 111 can reduce the electrical resistance of the first electrode 12 and the second electrode 14, thereby improving the conductivity of the first electrode 12 and the second electrode 14.

With the principle of the inverse piezoelectric effect, when an audio signal input device 18 inputs an audio signal through the first electrode 12 and the second electrode 14 to the piezoelectric element 16, the piezoelectric element 16 is elastically deformed. In this embodiment, since the first electrode 12 and the second electrode 14 disposed on the surface of the piezoelectric element 16 are composed of a flexible carbon nanotube, the elastic denaturation of the piezoelectric element 16 causes the first electrode The second electrode 14 and the second electrode 14 vibrate accordingly, thereby urging the surrounding air to vibrate and causing sound.

Referring to FIG. 6, a second embodiment of the present invention provides a flat panel speaker 20 that includes a piezoelectric element 26 that includes a first surface 262 and a first surface 262 opposite the first surface 262. a second surface 264; a first electrode 22 electrically connected to the piezoelectric element 26 and disposed on the first surface 262 thereof; a second electrode 24, the second electrode 24 and the piezoelectric element 26 is electrically connected and disposed on its second surface 264.

This embodiment is basically the same as the first embodiment described above, except that the flat panel speaker 20 further includes a diaphragm 29, and the diaphragm 29 can be bonded to the first electrode 22 or the second by a common adhesive. The surface of the electrode 24.

The material of the diaphragm 29 can be selected from conventional diaphragm materials used in conventional speakers in the prior art, such as resin, paper or metal materials. At the same time, the thickness of the diaphragm 29 is not However, it is only necessary to ensure that the vibration of the piezoelectric element 26 can drive the diaphragm 29 to vibrate at the same time, and push the surrounding air to vibrate and sound.

The specific operation of the flat panel speaker 20 is that an audio signal input device 28 is used to input an audio signal through the first electrode 22 and the second electrode 24 to the piezoelectric element 26, thereby causing the piezoelectric element 26 to be reversed. Vibrating by the piezoelectric effect, the vibration of the piezoelectric element 26 correspondingly drives the diaphragm 29 to vibrate, thereby urging the surrounding air to vibrate.

The vibration of the diaphragm 29 of the flat panel speaker 20 can vibrate and sound without using a complicated structure such as a magnetic system of a conventional speaker and a voice coil.

The flat panel speaker of the present invention has the following advantages: the flat panel speaker adopts a carbon nanotube structure as a first electrode and a second electrode, and the carbon nanotube structure comprises a plurality of carbon nanotubes arranged substantially in the same direction. Since the longitudinal conductivity of the carbon nanotubes is good, the first electrode and the second electrode of the present invention have good electrical conductivity, so that the entire flat panel speaker has high sensitivity and stability; and further, the nanocarbon of the present invention The tube structure has a self-supporting structure, so the first electrode and the second electrode have higher strength, thereby prolonging the service life of the entire flat panel speaker; since the carbon nanotube structure is perpendicular to the length of the carbon nanotube tube The light transmittance of the carbon nanotubes has a good transparency; the present invention further improves the first electrode and the second electrode of the flat panel speaker by forming a conductive metal layer on the surface of the carbon nanotube structure. The electrical conductivity of the electrode.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by persons skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

10‧‧‧ flat speaker

12‧‧‧First electrode

14‧‧‧second electrode

16‧‧‧Piezoelectric components

162‧‧‧ first surface

164‧‧‧ second surface

Claims (17)

A flat panel speaker comprising: a piezoelectric element including a first surface and a second surface opposite the first surface; a first electrode, the first electrode and the piezoelectric The element is electrically connected and disposed on the first surface thereof; a second electrode electrically connected to the piezoelectric element and disposed on the second surface thereof; and the improvement is that the first electrode and the second electrode are both The carbon nanotube structure comprises a plurality of carbon nanotubes arranged substantially in the same direction, and the surface of the carbon nanotube is further coated with at least one conductive metal layer. The flat panel speaker of claim 1, wherein the plurality of carbon nanotubes of the first electrode are substantially parallel to the first surface of the piezoelectric element. The flat panel speaker of claim 1, wherein the plurality of carbon nanotubes of the second electrode are substantially parallel to the second surface of the piezoelectric element. The flat panel speaker of claim 1, wherein the carbon nanotube structure comprises at least one carbon nanotube film. The flat panel speaker of claim 4, wherein the carbon nanotube film comprises a plurality of carbon nanotubes connected end to end by van der Waals force and arranged in the same direction. The flat panel speaker of claim 4, wherein the carbon nanotube film comprises a plurality of substantially parallel arranged carbon nanotubes. The flat panel speaker of claim 4, wherein the carbon nanotube structure comprises a plurality of carbon nanotube films, the plurality of carbon nanotube films being coplanar and without gaps laid or laminated. The flat panel speaker of claim 1, wherein the carbon nanotube structure is a self-supporting structure. The flat panel speaker of claim 1, wherein the carbon nanotube comprises one or more of a single-walled carbon nanotube, a double-walled carbon nanotube, and a multi-walled carbon nanotube. The flat panel speaker of claim 1, wherein the at least one conductive metal layer comprises a wetting layer and a conductive layer, and the wetting layer and the conductive layer are sequentially coated on the surface of the carbon nanotube. The flat panel speaker according to claim 10, wherein the material of the conductive metal layer comprises an alloy of nickel, palladium, titanium, copper, silver, gold, platinum or any combination thereof. The flat panel speaker according to claim 10, wherein the conductive metal layer has a thickness of from 1 nm to 100 nm. The flat panel speaker of claim 10, wherein the first electrode and the second electrode are respectively bonded to the first surface and the second surface of the piezoelectric element with a conductive adhesive. The flat panel speaker according to claim 1, wherein the piezoelectric element is made of polyvinylidene fluoride, polyvinyl fluoride or polyvinyl chloride. A flat panel speaker comprising: a piezoelectric element including a first surface and a second surface opposite the first surface; a first electrode, the first electrode and the piezoelectric The element is electrically connected and disposed on the first surface thereof; a second electrode electrically connected to the piezoelectric element and disposed on the second surface of the piezoelectric element; a diaphragm, the diaphragm is disposed On the surface of the first electrode or the second electrode; the improvement is that the first electrode and the second electrode are a carbon nanotube structure, and the carbon nanotube structure comprises a plurality of substantially aligned in the same direction The carbon nanotube, the surface of the carbon nanotube is further coated with at least one conductive metal layer. The flat panel speaker according to claim 15, wherein the diaphragm is bonded to the first electrode or the second electrode by an adhesive. The flat panel speaker according to claim 15, wherein the material of the diaphragm is resin, paper or metal.