TWI382399B - Acoustic device - Google Patents

Description

Sound device

The invention relates to a sound emitting device, in particular to a sound emitting device based on a carbon nanotube.

The sounding device generally consists of a signal input device and a sounding component, and a signal is input through the signal input device to the sounding component to emit a sound. The thermoacoustic device is one of the sounding devices, which is a sounding device based on the thermoacoustic effect.

H. D. Arnold and I. B. Crandall, in the document "The thermophone as a precision source of sound", Phys. Rev. 10, p22-38 (1917), describes a simple thermoacoustic device that uses a platinum sheet as the sounding element. Since the sounding frequency of the sounding element is closely related to the heat capacity per unit area, the heat capacity per unit area is large, the sounding frequency range is narrow, and the sound wave intensity is low; conversely, the heat capacity per unit area is small, the sounding frequency range is wide, and the sound wave intensity is high. Therefore, in order to obtain a wide range of vocal frequencies and a high sound wave intensity, it is required that the heat capacity per unit area of the sounding element is as small as possible. The metal platinum sheet with smaller heat capacity is limited by the material itself, and the thickness can be as small as 0.7 micron, and the sounding device using the platinum sheet as the sounding element can generate a sound frequency of up to 4,000. hertz.

In addition, Fan Shoushan et al. disclose a sounding device using a carbon nanotube, see the literature "Flexible, Stretchable, Transparent Carbon Nanotube Thin Film Loudspeakers", Fan Shoushan et al., Nano Letters , Vol. 8 (12), p 4539-4545 (2008). Referring to FIG. 1, the sounding device 10 includes a substrate 12, a carbon nanotube film 14, and two electrodes 16. The carbon nanotube film 14 is disposed on the substrate 12, and the two electrodes 16 are electrically connected to the carbon nanotube film 14, respectively. Since the sound generating device 10 uses the carbon nanotube film 14 as a sound emitting element, the carbon nanotube film 14 has a large specific surface area and a very small heat capacity per unit area, so that the sound generating device 10 can emit a sound that can be heard by the human ear. Strength, and has a very thin thickness and a wide range of audible frequencies (100Hz ~ 100kHz).

However, since the carbon nanotube film 14 is directly bonded to the substrate 12, the contact area of the carbon nanotube film 14 with the surrounding medium is reduced, and the heat generated by the carbon nanotube film 14 is large for sound generation. Part of being absorbed by the substrate 12 reduces the sounding effect of the sounding device 10; meanwhile, since the carbon nanotube film 14 is directly in contact with the two electrodes 16 by its own viscosity, the carbon nanotube film 14 The electrical connection effect with the two electrodes 16 needs to be improved, thereby improving the sounding effect of the entire sounding device 10.

In view of this, it is necessary to provide a carbon nanotube sounding device that effectively improves the sounding effect.

A sounding device comprising: a substrate; a first electrode and a second electrode, the first electrode and the second electrode are spaced apart from the substrate; a sounding element, the sounding element is a carbon nanotube structure, The carbon nanotube structure is electrically connected to the first electrode and the second electrode; wherein the sounding device further comprises a conductive bonding layer disposed on a surface of the first electrode and the second electrode, the sounding element Fixed to the conductive bonding layer, and the conductive bonding layer penetrates into the sounding element, and the sounding element phase The substrate is suspended and has a distance between the sounding element and the substrate.

Compared with the prior art, the sounding device can ensure that the sounding element has good electrical connection with the first electrode and the second electrode by fixing the sounding element in the conductive bonding layer; and, because of the sounding element and the substrate The suspension is disposed so as to have a distance therebetween, so that the sounding element has sufficient heat exchange with the surrounding medium, and the heat generated therein for sound generation can be quickly transmitted to the surrounding medium, thereby effectively improving the sounding effect of the sounding device. .

The sounding device provided by the embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

Referring to FIG. 2 , a first embodiment of the present invention provides a sounding device 20 . The sounding device 20 includes a substrate 21 , a first electrode 22 , a second electrode 23 , a conductive bonding layer 24 , and a sound emitting element 25 .

The first electrode 22 and the second electrode 23 are spaced apart from the substrate 21 . The conductive bonding layer 24 is disposed on the surface of the first electrode 22 and the second electrode 23, and the sound emitting element 25 is fixed to the conductive bonding layer 24 of the first electrode 22 and the conductive bonding layer 24 of the second electrode 23. The bonding layer 24 penetrates into the sounding element 25, and the sounding element 25 is electrically connected to the first electrode 22 and the second electrode 23 through the conductive bonding layer 24. The sounding element 25 is suspended from the substrate 21, and the sounding element 25 forms a space P with the first electrode 22, the second electrode 23, the conductive bonding layer 24, and the substrate 21, so that the sounding element 25 and the substrate 21 are There is a distance, preferably, the distance is less than or equal to 10 mm, and in the present embodiment, the distance is 0.25 mm.

The substrate 21 mainly functions to carry the first electrode 22 and the second electrode 23, and has a certain protective effect on the sound emitting element 25. The shape and size of the substrate 21 are not limited, and the material is an insulating material or a material having poor conductivity such as glass, resin or ceramics. Preferably, the material of the substrate 21 should have better thermal insulation properties, so as to prevent the excessive heat generated by the sound generating element 25 from being absorbed by the substrate 21, and the purpose of heating the surrounding medium to achieve sounding. In this embodiment, the substrate 21 is a square glass plate having a side length of 17 cm and a thickness of 1 mm.

The first electrode 22 is disposed in parallel with and spaced apart from the second electrode 23, and the sounding device 20 is electrically connected to an external circuit through the first electrode 22 and the second electrode 23. The first electrode 22 and the second electrode 23 can be fixed to the substrate 21 by bolting or bonding of a bonding agent or the like. In addition, the sounding device 20 may further include at least two positioning elements (not shown) disposed on the substrate 21 for limiting the first electrode 22 and the second electrode 23 to a specific position of the substrate 21. The two positioning elements can be respectively formed in a groove of the substrate 21, and the first electrode 22 and the second electrode 23 are partially received therein for the purpose of positioning.

The first electrode 22 and the second electrode 23 may be in the form of a filament, a layer, a rod, a strip, a block or other shapes, and the cross section may be in the shape of a circle, a square, a trapezoid, a triangle, a polygon or the like. Regular shape. The material of the first electrode 22 and the second electrode 23 may be selected from a metal, an alloy or an indium tin oxide (ITO), etc., preferably a metal wire. In this embodiment, the first electrode 22 and the second electrode 23 are stainless steel wires, and the stainless steel wire has a diameter of 0.25 mm.

The height of the first electrode 22 and the second electrode 23 affect the sounding element The distance between the first electrode 22 and the second electrode 23 is greater than the distance between the first electrode 22 and the second electrode 23, and the sounding element 25 is formed with the first electrode 22, the second electrode 23, the conductive bonding layer 24 and the substrate 21. The larger the space P is, the sufficient sound exchange is made between the sounding element 25 and the air or other external medium, so that the sounding effect of the sounding device 20 can be improved to some extent. At the same time, maintaining a certain distance between the sounding element 25 and the substrate 21 is more advantageous for accelerating the heat dissipation of the sounding element 25 itself, and also preventing the heat of the sounding element 25 from being excessively absorbed by the substrate 21, causing damage to the substrate 21 and affecting the sounding effect of the sounding element 25. .

The material of the conductive adhesive layer 24 is a conductive paste or a conductive paste. The main components of the conductive paste or the conductive paste include metal particles, a binder, a solvent, etc., and the metal particles may be gold particles, silver particles or aluminum particles. . In this embodiment, the material of the conductive adhesive layer 24 is preferably a silver conductive paste, that is, the metal particles in the conductive paste are silver particles. The conductive bonding layer 24 is formed by applying the conductive paste to the first electrode 22 and the second electrode 23.

The sounding element 25 includes a carbon nanotube structure including at least one carbon nanotube film, a plurality of carbon nanotube lines, or a composite structure of a carbon nanotube film and a nano carbon line. The thickness of the carbon nanotube structure (the diameter of the linear structure in the case of a linear structure) is 0.5 nm to 1 mm. The carbon nanotube structure may have a heat capacity per unit area of less than 2 x 10 ^-4 joules per square centimeter Kelvin. Preferably, the carbon nanotube structure has a heat capacity per unit area of less than 1.7 x 10 ^-6 joules per square centimeter Kelvin. The carbon nanotubes in the carbon nanotube structure include 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 50 nm, and the double-walled carbon nanotube has a diameter of 1.0 nm to 50 nm, and the diameter of the multi-walled carbon nanotube is 1.5 nm. 50 nm.

Alternatively, the carbon nanotube structure laid on the conductive adhesive layer 24 may be further treated with an organic solvent. Specifically, the organic solvent is a volatile organic solvent, and ethanol, methanol, acetone, dichloroethane or chloroform may be used, and preferably ethanol. The step of treating with an organic solvent may be carried out by dropping an organic solvent into a carbon nanotube structure through a test tube, or immersing the entire carbon nanotube structure in a container containing an organic solvent. The treated carbon nanotube structure is non-viscous and has good mechanical strength and toughness.

The carbon nanotube film is directly obtained by drawing an array of carbon nanotubes, and the carbon nanotube film comprises a plurality of carbon nanotubes arranged in a preferred orientation in the same direction, and the carbon nanotubes pass through the van der Waals The force is connected end to end.

The carbon nanotube structure may include, in addition to a single carbon nanotube film, a plurality of stacked carbon nanotube membranes. The carbon nanotube structure composed of a plurality of stacked carbon nanotube membranes has a higher strength than a carbon nanotube structure composed of a single carbon nanotube membrane, thereby ensuring that the carbon nanotube structure is not Destroy or change. Since the light transmittance of the single carbon nanotube film is good, in the embodiment, in order to maintain the light transmittance of the carbon nanotube structure, the number of the carbon nanotube film in the carbon nanotube structure is Less than or equal to 4.

In addition, when the width of a single carbon nanotube film cannot meet the requirements of practical applications, the plurality of carbon nanotube films can be coplanar without gaps to form a carbon nanotube film having a larger width for practical application. .

In this embodiment, the carbon nanotube structure as the sounding element 25 includes four An overlapping carbon nanotube film, wherein the arrangement of the carbon nanotubes in the adjacent two carbon nanotube films is vertically intersected, and the arrangement of the carbon nanotubes in at least one of the carbon nanotube films The direction is perpendicular to the direction in which the first electrode 22 and the second electrode 23 are arranged. The carbon nanotube structure has a length and width of 15 cm and a thickness of 100 nm. The carbon nanotube structure composed of four carbon nanotube membranes maintains the sound-emitting element 25 with good light transmittance.

The working medium of the sound emitting element 25 is not limited, and only needs to satisfy a resistivity higher than that of the sound emitting element 25. The medium includes a gaseous medium or a liquid medium. The gaseous medium can be air. The liquid medium includes one or more of a non-electrolyte solution, water, and an organic solvent. The liquid medium has a resistivity greater than 0.01 ohms. Rice, preferably, the liquid medium is purified water. The conductivity of pure water can reach 1.5 × 10 ⁷ ohms. The meter, which has a larger specific heat capacity, can conduct heat generated by the starting acoustic element 25, so that the sound emitting element 25 can be dissipated.

In order to partially embed the sound emitting element 25 into the conductive bonding layer 24, when a material such as a silver conductive paste of the conductive bonding layer 24 is applied to the first electrode 22 and the second electrode 23 and curing has not occurred, The sounding element 25 is laid in the silver conductive paste. Since the silver conductive paste is in a liquid state at this time, and there is a gap between the plurality of carbon nanotubes in the sound emitting element 25 including the carbon nanotube structure, the silver conductive paste is immersed in the gap between the carbon nanotube structures. The silver conductive paste forms a conductive bonding layer 24 by a subsequent curing process, and a portion of the sounding element 25 is embedded in the conductive bonding layer 24.

The method is to ensure that a portion of the sound emitting element 25 is immersed in the conductive bonding layer 24, and may further include a carbon nanotube junction that has been laid on the silver conductive paste. Applying a pressure, such as using a blowing device to blow the carbon nanotube structure, generating a wind pressure to fully immerse the silver conductive paste into the carbon nanotube structure, and then curing the silver conductive paste to form a conductive bonding layer. 24. The sound emitting element 25 is embedded in the conductive bonding layer 24.

The sounding element 25 of the sounding device 20 includes a carbon nanotube structure composed of a uniformly distributed carbon nanotube having a large specific surface area and the carbon nanotube structure The layered or linear shape, therefore, the carbon nanotube structure has a large specific surface area, a small heat capacity per unit area, and a large heat dissipation area. After inputting the signal, the sounding element 25 can rapidly rise and fall, generate periodic temperature changes, and quickly exchange heat with the surrounding medium to periodically change the density of the surrounding medium to emit sound. Therefore, in this embodiment, the sounding principle of the sounding element 25 is "electric-thermal-acoustic" conversion. Since the carbon nanotube structure has a certain light transmittance, the sounding device 20 is a transparent sounding device.

The sound pressure device 20 provided in this embodiment has a sound pressure level of more than 50 decibels per watt, and the sounding frequency ranges from 1 Hz to 100,000 Hz (1 Hz to 100 kHz). The sounding device 20 may have a distortion of less than 3% in the frequency range of 500 Hz to 40,000 Hz. In addition, the carbon nanotube structure in the embodiment has better toughness and mechanical strength, so the carbon nanotube structure can be conveniently fabricated into the sounding device 20 of various shapes and sizes, and the sounding device 20 can be conveniently applied to A variety of audible devices, such as audio, mobile phones, MP3, MP4, TV, computers and other devices that can be audible.

Referring to FIG. 3 and FIG. 4, a second embodiment of the present invention provides a sounding device 30. The sounding device 30 includes a substrate 31, a plurality of first electrodes 32, a plurality of second electrodes 33, a conductive bonding layer 34, a sounding component 35, and a first A conductive element 37 and a second conductive element 38.

In this embodiment, the substrate 31 is a square glass plate having a side length of 17 cm and a thickness of 1 mm.

In the present embodiment, the sounding device 30 includes four first electrodes 32 and four second electrodes 33. The four first electrodes 32 and the second electrodes 33 are alternately disposed at equal intervals on the substrate 31. The first electrode 32 and the second electrode 33 are stainless steel wires which are disposed on the substrate 31 by a bonding agent. Each of the first electrode 32 and the second electrode 33 has a length of 16 cm and a diameter of 0.25 mm.

The number of the first electrode 32 and the second electrode 33 is not limited to the embodiment. The number and distance of the first electrode 32 and the second electrode 33 are related to the size of the substrate 31. The distance between each of the adjacent first electrodes 32 and the second electrodes 33 may be equal or unequal. Preferably, the distance between each adjacent first electrode 32 and the second electrode 33 is equal. The distance is preferably from 10 micrometers to 3 centimeters. In this embodiment, the distance between the adjacent first electrode 32 and the second electrode 33 is 2 cm.

The conductive bonding layer 34 is disposed on at least one surface of the first electrode 32 and the second electrode 33. In this embodiment, the conductive bonding layer 34 is a silver conductive paste.

The sound emitting element 35 is laid on the conductive bonding layer 34 of the first electrode 32 and the conductive bonding layer 34 of the second electrode 33. The sounding element 35 is suspended relative to the substrate 31, and the sounding element 35 forms a complex space P' with the first electrode 32, the second electrode 33, the conductive bonding layer 34, and the substrate 31. The complex space P' is advantageous for the sounding element. 35 voices.

A portion of the sound emitting element 35 is embedded in the conductive adhesive layer 34, and the sound emitting element 35 is electrically connected to the first electrode 32 and the second electrode 33 through the conductive adhesive layer 34. The distance between the sound emitting element 35 and the substrate 31 is 0.25 mm, and is not limited to 0.25 mm, but may be greater than 0.25 mm or less than 0.25 mm. The sound emitting element 35 comprises a carbon nanotube structure comprising four overlapping carbon nanotube membranes, wherein the arrangement of the carbon nanotubes in the adjacent two carbon nanotube membranes is Vertically intersecting, and wherein the arrangement direction of the carbon nanotubes in at least one of the carbon nanotube films is perpendicular to the direction in which the first electrode 32 and the second electrode 33 are arranged. The carbon nanotube structure has a length and width of 15 cm and a thickness of 100 nm.

The first conductive element 37 is connected to the four first electrodes 32 of the sounding device 30, and the four first electrodes 32 are electrically connected to the first conductive element 37. The second conductive element 38 and the sounding device 30 are four. The second electrodes 33 are connected such that the four second electrodes 33 are electrically connected to the second conductive member 38. The sounding device 30 is electrically connected to an external circuit through the first conductive member 37 and the second conductive member 38.

Referring to FIG. 5 and FIG. 6 , a third embodiment of the present invention provides a sounding device 40 . The sounding device 40 includes a substrate 41 , a plurality of spacers 46 , a plurality of first electrodes 42 , a plurality of second electrodes 43 , and a conductive bonding layer . 44. A sounding element 45, a first conductive element 47 and a second conductive element 48.

The spacers 46 are disposed parallel to each other and spaced apart from the substrate 41, and the spacers 46 are positioned opposite to the positions of the first electrode 42 and the second electrode 43 at the position of the substrate 41. The spacers 46 are respectively fixed between the substrate 41 and the first electrode 42 and the second electrode 43 by adhesive bonding or bolting.

The plurality of first electrodes 42 and the plurality of second electrodes 43 are disposed on the substrate 41 through the spacers 46. The plurality of first electrodes 42 and the plurality of second electrodes 43 are alternately disposed at equal intervals on the substrate 41.

The conductive bonding layer 44 is disposed on at least one surface of the first electrode 42 and the second electrode 43. The sound emitting element 45 is disposed on the conductive bonding layer 44 of the first electrode 42 and the conductive bonding layer 44 of the second electrode 43. . The sound emitting element 45 is suspended from the substrate 41, and the sounding element 45 forms a plurality of spaces P" together with the first electrode 42, the second electrode 43, the conductive bonding layer 44, and the substrate 41, and the sound generating element 45 is partially embedded therein. The conductive bonding layer 44 is electrically connected to the first electrode 42 and the second electrode 43 through the conductive bonding layer 44. The distance between the sound emitting element 45 and the substrate 41 is equal to 0.25 mm, and is not limited to 0.25 mm, and may be greater than 0.25 mm or less than 0.25 mm.

In this embodiment, the materials, shapes, and numbers of the substrate 41, the first electrode 42, the second electrode 43, the sounding element 45, and the conductive bonding layer 44 are the same as those of the third embodiment.

The number of the spacers 46 is the same as the total number of the first electrodes 42 and the second electrodes 43. The spacers 46 may have any structure, and the spacers 46 may have the same structure as the first electrodes 42 and the second electrodes 43. different. The material of the spacer 46 may be a conductive material or an insulating material. The conductive material includes a metal, an alloy, a conductive paste, a conductive paste or an indium tin oxide, and the insulating material includes glass, resin or ceramic. In this embodiment, the material of the spacer 46 is glass. The height of the spacer 46 is not limited. If the height of the first electrode 42 and the second electrode 43 is small, the spacer 46 having a certain height may further raise the first electrode 42 and the second electrode 43. From The distance between the sound emitting element 45 and the substrate 41 is increased to ensure a sufficient space P" between the sound emitting element 45 and the substrate 41, so that the sounding element 45 is sufficiently hot with air or other external medium. The exchange, in turn, can improve the sounding effect of the sounding device 40 to some extent.

Compared with the prior art, the sounding device can ensure that the sounding element has good electrical connection with the first electrode and the second electrode by fixing the sounding element in the conductive bonding layer; and, because the sounding element and the substrate are suspended The arrangement is such that there is a distance between them, so that the sounding element has sufficient heat exchange with the surrounding medium, and the heat generated inside the sounding device can be quickly transmitted to the surrounding medium, thereby effectively improving the sounding effect of the sounding device.

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.

20, 30, 40‧‧‧ sounding devices

21, 31, 41‧‧‧ base

22, 32, 42‧‧‧ first electrode

23, 33, 43‧‧‧ second electrode

24, 34, 44‧‧‧ Conductive bonding layer

25, 35, 45‧‧‧ sounding components

37, 47‧‧‧ first conductive element

38, 48‧‧‧Second conductive element

46‧‧‧ spacer

P, P’, P” ‧ ‧ space

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view of a sound generating device in the prior art.

Figure 2 is a cross-sectional view showing a sound emitting device according to a first embodiment of the present invention.

Figure 3 is a cross-sectional view showing a sound emitting device according to a second embodiment of the present invention.

Figure 4 is a plan view of a sounding device provided by a second embodiment of the present invention.

Figure 5 is a cross-sectional view showing a sound emitting device according to a third embodiment of the present invention.

Figure 6 is a plan view of a sounding device provided by a third embodiment of the present invention.

32‧‧‧First electrode

30‧‧‧ Sounding device

31‧‧‧Base

33‧‧‧second electrode

34‧‧‧ Conductive bonding layer

35‧‧‧Sounding components

P’‧‧‧ space

Claims (20)

A sounding device comprising: a substrate; a first electrode and a second electrode, the first electrode and the second electrode are spaced apart from the substrate; a sounding element, the sounding element is a carbon nanotube structure, The carbon nanotube structure is electrically connected to the first electrode and the second electrode; and the sounding device further includes a conductive bonding layer disposed on the first electrode and the first The surface of the two electrodes is fixed to the conductive bonding layer, and the conductive bonding layer penetrates into the sounding element, the sounding element is suspended relative to the substrate, and the sounding element has a distance from the substrate. The sounding device according to claim 1, wherein a distance between the sound emitting element and the substrate is 10 mm or less. The sounding device of claim 1, wherein the sounding device comprises a plurality of first electrodes and a plurality of second electrodes, and the plurality of first electrodes and the plurality of second electrodes are alternately spaced apart. The sounding device of claim 3, wherein the sounding device further comprises a first conductive element and a second conductive element, the first conductive element being electrically connected to the plurality of first electrodes, the second conductive The component is electrically connected to the plurality of second electrodes. The sounding device of claim 3, wherein the plurality of first electrodes and the plurality of second electrodes are parallel to each other. The sounding device of claim 5, wherein the distance between each adjacent first electrode and second electrode is equal. The sounding device of claim 6, wherein the distance between the adjacent first electrode and the second electrode is from 10 micrometers to 3 centimeters. The sounding device according to claim 1, wherein the shape of the first electrode and the second electrode are respectively a filament, a layer, a rod, a strip or a block. The sounding device according to claim 1, wherein the shape of the cross section of the first electrode and the second electrode is a circular shape, a square shape, a trapezoidal shape, a triangular shape, a polygonal shape or an irregular shape. The sounding device of claim 1, wherein the materials of the first electrode and the second electrode are respectively a metal, an alloy or an indium tin oxide. The sounding device of claim 1, wherein the first electrode and the second electrode are respectively wires. The sounding device of claim 11, wherein the wire has a diameter of 10 mm or less. The sounding device of claim 1, wherein the conductive adhesive layer penetrates into both sides of the carbon nanotube structure. The sounding device of claim 1, wherein the conductive bonding layer is made of a conductive paste or a conductive paste. The sounding device of claim 14, wherein the conductive paste or the conductive paste comprises metal particles, a binder, and a solvent. The sounding device according to claim 1, wherein the carbon nanotube structure comprises at least one carbon nanotube film, a plurality of nano carbon pipes or a composite structure of a carbon nanotube film and a nano carbon line. . The sounding device of claim 1, wherein the sounding device further comprises at least two spacers, the at least two spacers are in one-to-one correspondence with the first electrode and the second electrode, and are disposed on the substrate With the first electricity Between the pole and the second electrode. The sounding device of claim 17, wherein the material of the spacer is an insulating material. The sounding device of claim 1, wherein the sounding device further comprises at least two positioning elements disposed on the substrate to respectively limit the first electrode and the second electrode The position of the base. The sounding device of claim 19, wherein the at least two positioning elements are grooves formed in the base.