TWI382772B - Thermoacoustic device - Google Patents

Description

Thermal sounding device

The invention relates to a thermo-acoustic device.

On October 29, 2008, Fan Shoushan and others disclosed a thermo-acoustic device using thermoacoustic effects, see the literature "Flexible, Stretchable, Transparent Carbon Nanotube Thin Film Loudspeakers", ShouShan Fan, et al., Nano Letters, Vol. 8(12), 4539-4545 (2008). The thermoacoustic element uses a carbon nanotube film as a thermoacoustic element, because the carbon nanotube film has a large specific surface area and a very small heat capacity per unit area (less than 2 × 10 ^-4 Joules per square centimeter Kelvin) The thermoacoustic element emits a sound that the human ear can hear and has a wide range of vocal frequencies (100 Hz to 100 kHz). In the thermoacoustic device, the carbon nanotube film can be suspended or attached to the surface of a glass plate. However, when the carbon nanotube film is suspended, the carbon nanotube film is more easily destroyed. When the carbon nanotube film is completely adhered to the surface of the glass plate, the heat generated by the carbon nanotube film is mostly conducted by the glass plate, and cannot be used to heat the surrounding air, so that the density of the surrounding air cannot be changed to emit sound.

In view of the above, it is necessary to provide a thermoacoustic device in which a thermoacoustic element is not easily broken and has a good sounding effect.

A thermo-acoustic device comprising: a substrate having a surface; a thermo-acoustic element located on one side of the substrate facing the surface of the substrate; and a first electrode and a second electrode spaced apart And electrically connecting to the thermo-acoustic element, wherein the surface of the substrate is formed with a recess facing the thermo-acoustic element, the thermo-acoustic element has a first area and a second area, the a region and a second region are located between the first electrode and the second electrode, wherein the thermo-acoustic element of the first region covers the recess opening and is suspended, the second region of the thermo-acoustic component The surface of the substrate is in contact.

A thermo-acoustic device comprising: a substrate having a surface; a thermo-acoustic element located on one side of the substrate and facing the surface of the substrate; and a uniform thermal device for heating the thermo-acoustic element Thermally audible; wherein the surface of the substrate is formed with a plurality of openings facing the recess of the thermo-acoustic element, the thermo-acoustic element being in contact with the surface of the substrate, and covering at least a portion of the opening of the recess such that A portion of the thermo-acoustic element is suspended relative to the surface of the substrate.

A thermo-acoustic device comprising: a substrate having a surface; a thermally-induced sounding film on one side of the substrate facing the surface of the substrate; and a uniform thermal device for thermally inducing the thermal-acoustic film The sound is audible; wherein the surface of the substrate is formed with a recess facing the concave portion of the thermoacoustic film, the thermoacoustic film has a first region and a second region, and the first region of the thermoacoustic film covers The recess opening is not in contact with the substrate, and the thermally audible film of the second region is in surface contact with the surface of the substrate.

Compared with the prior art, the thermo-acoustic device has the following advantages: the second region of the thermo-acoustic element disposed on the surface of the substrate is in contact with the substrate, and the first region covers the opening of the recess of the substrate and is suspended, on the one hand, The substrate can support and fix the thermo-acoustic component. On the other hand, the recess of the substrate conducts heat from the thermo-acoustic component as little as possible through the substrate, and the recess of the substrate increases the thermo-acoustic component The area in contact with the surrounding gas or liquid medium such that the substrate does not affect the thermoacoustic elements of the thermoacoustic element.

Hereinafter, a thermo-acoustic sounding device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1 and FIG. 2 , a first embodiment of the present invention provides a thermal sound generating device 200 including a substrate 202 , a thermal sound generating element 204 , a first electrode 206 , and a second electrode 216 . The first electrode 206 and the second electrode 216 are spaced apart from each other and electrically connected to the thermo-acoustic element 204. A surface 230 of the substrate 202 has at least one recess 208. The thermally audible element 204 is located on a side of the substrate 202 having a recess 208 and faces the surface 230 of the substrate 202. The recess 208 has an opening in the surface 230, and the thermo-acoustic element 204 has a first area 210 and a second area 220, and the first area 210 and the second area 220 are located at the Between an electrode 206 and a second electrode 216. The thermally audible element 204 of the first region 210 covers the opening of the recess 208 and is suspended. The thermally audible element 204 of the second region 220 is in contact with and supported by the surface 230 of the substrate 202. The first region 210 and the second region 220 may be continuous or discontinuous regions, respectively.

The shape, size and thickness of the substrate 202 are not limited, and the surface 230 of the substrate 202 may be a flat surface or a curved surface. The material of the substrate 202 is not limited and may be a hard material or a flexible material having a certain strength. Preferably, the material of the substrate 202 has a resistance greater than that of the thermo-acoustic element 204 and has better thermal insulation properties to prevent excessive heat generated by the thermo-acoustic element 204 from being absorbed by the substrate 202. Specifically, the material of the substrate 202 may be glass, ceramic, quartz, diamond, plastic, resin or wood material. In this embodiment, the substrate 202 is a square transparent glass substrate 202. The surface 230 of the substrate 202 is a flat surface having a side length of 17 cm and a thickness of 20 mm.

Depending on the material of the substrate 202, the recess 208 may be formed on the surface of the substrate 202 by mechanical or chemical methods such as cutting, sanding, chemical etching, etching, and the like. Further, the substrate 202 having the concave portion 208 can be obtained by one molding of a mold having a predetermined shape.

The recess 208 may be one or more of a through slot structure, a through hole structure, a blind slot structure or a blind hole structure. When the substrate 202 has a plurality of recesses 208 , the plurality of recesses 208 are evenly distributed and distributed regularly or Randomly distributed, the first regions 210 respectively cover openings of the plurality of recesses 208 at the surface 230 of the substrate 202.

In this embodiment, the recess 208 of the substrate 202 is a through-groove structure. The depth of the through groove is the thickness of the substrate 202. When the through slot is parallel to one side of the surface 230 of the substrate 202, the length of the through slot is less than the side length. The shape of the through groove on the surface of the substrate 202 may be a rectangle, a shape, a polygon, an oblate shape or other irregular shape. When the surface 230 of the substrate 202 has a plurality of through grooves, the plurality of through grooves may be uniformly distributed, distributed in a regular pattern or randomly distributed on the surface 230 of the substrate 202. When the plurality of through grooves are parallel to each other and uniformly distributed on the surface of the substrate 202, the groove pitch d1 of each adjacent two through grooves is greater than 100 μm. In this embodiment, the surface 230 of the substrate 202 has a plurality of rectangular through-grooves equally spaced apart, the groove width is 1 mm, and the spacing d1 between each two adjacent through grooves is 1 mm.

The thermo-acoustic element 204 has a small heat capacity per unit area. In the embodiment of the present invention, the heat generating element 204 has a heat capacity per unit area of less than 2 x 10 ^-4 joules per square centimeter of Kelvin. Specifically, the thermoacoustic element 204 is a conductive structure having a large specific surface area and a small thickness, so that the thermoacoustic element 204 can convert input electrical energy into thermal energy and perform heat sufficiently quickly with the surrounding medium. exchange. Preferably, the thermoacoustic element 204 should be a self-supporting structure, the so-called "self-supporting structure", that is, the thermo-acoustic element 204 can maintain its own specific shape without being supported by a support. Therefore, the self-supporting thermally audible element 204 can be partially suspended. The thermally actuated element 204 of the self-supporting structure is sufficiently in contact with the surrounding medium and exchanges heat. The thermoacoustic element 204 can be a film-like structure or a linear structure, such as a thermally-induced acoustic film.

In this embodiment, the thermoacoustic element 204 comprises a carbon nanotube structure. Specifically, the carbon nanotube structure is a layered structure, and the thickness is preferably 0.5 nm to 1 mm. When the thickness of the carbon nanotube structure is relatively small, for example, 10 micrometers or less, the carbon nanotube structure has good transparency. The carbon nanotube structure is a self-supporting structure. The plurality of carbon nanotubes in the self-supporting carbon nanotube structure are attracted to each other by the van der Waals force, so that the carbon nanotube structure has a specific shape. Therefore, the carbon nanotube structure portion is supported by the substrate 202, and the other portions of the carbon nanotube structure are suspended.

The carbon nanotube structure includes at least one carbon nanotube film. The carbon nanotube film is directly drawn from the carbon nanotube array. The carbon nanotube film has a thickness of from 0.5 nm to 100 μm and a heat capacity per unit area of less than 1 × 10 ^-6 joules per square centimeter of Kelvin. The carbon nanotubes 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, the double-walled carbon nanotube has a diameter of 1 nm to 50 nm, and the multi-walled carbon nanotube has a diameter of 1.5 nm to 50 nm. Nano. The length of the carbon nanotube film is not limited, and the width depends on the width of the carbon nanotube array. Referring to FIG. 3, the carbon nanotube film in the carbon nanotube structure includes a plurality of carbon nanotubes connected end to end and arranged in a preferred orientation in the same direction, the plurality of carbon nanotubes being substantially parallel and substantially parallel to the Surface 230 of substrate 202. When the width of the carbon nanotube film is small, the carbon nanotube structure includes a plurality of carbon nanotube films coplanarly surfaced on the surface 230 of the substrate 202. In addition, the carbon nanotube structure may comprise a plurality of layers of mutually overlapping carbon nanotube membranes, wherein the carbon nanotubes in the adjacent two layers of carbon nanotube membranes have an angle of intersection α, α is greater than or equal to 0 degrees and less than Equal to 90 degrees.

In this embodiment, the thermo-acoustic element 204 is a single-layer carbon nanotube film disposed on the surface 230 of the substrate 202 and includes a first region 210 covering the recess 208 and The surface 230 of the substrate 202 contacts the second region 220. The carbon nanotube film has a thickness of 50 nm and a light transmittance of 67% to 95%.

The carbon nanotube film has a strong viscosity, so the carbon nanotube film can be directly adhered to the surface 230 of the substrate 202. Further, after the carbon nanotube film is adhered to the surface 230 of the substrate 202, the carbon nanotube film adhered to the substrate 202 may be treated with an organic solvent. Specifically, the organic solvent may be dropped on the surface of the carbon nanotube film by a test tube to infiltrate the entire carbon nanotube film. The organic solvent is a volatile organic solvent such as ethanol, methanol, acetone, dichloroethane or chloroform, and ethanol is used in this embodiment. Under the action of the surface tension generated by the volatilization of the volatile organic solvent, microscopically, some of the adjacent carbon nanotubes in the carbon nanotube film shrink into bundles. The contact area of the carbon nanotube film with the substrate is increased to be more closely attached to the surface 230 of the substrate 202. In addition, since some adjacent carbon nanotubes shrink into bundles, the mechanical strength and toughness of the carbon nanotube film are enhanced, and the surface area of the entire carbon nanotube film is reduced, and the viscosity is lowered. Macroscopically, the carbon nanotube membrane is a uniform membrane structure.

It can be understood that in order to better fix the carbon nanotube film on the surface 230 of the substrate 202, a bonding layer or bonding point may be disposed on the surface 230 of the substrate 202, so that the carbon nanotube film passes through. The bonding layer or bond point is affixed to the surface 230 of the substrate 202. It is conceivable in the prior art that in order to achieve a specific function, such as the above-described fixed function, the thermoacoustic element 204 may not be in direct contact with the surface 230 of the substrate 202, but may be disposed on an intermediate element surface, the intermediate element being disposed on The surface 230 of the substrate 202 is between the thermally audible element 204.

The first electrode 206 and the second electrode 216 are respectively electrically connected to the thermo-acoustic element 204 to connect the thermo-acoustic element 204 to an audio signal. Specifically, the first electrode 206 and the second electrode 216 may be spaced apart from a side of the thermo-acoustic element 204 facing away from the substrate 202. The first electrode 206 and the second electrode 216 are formed of a conductive material, and the shape and structure thereof are not limited. Specifically, the first electrode 206 and the second electrode 216 may be selected as elongated strips, rods, or other shapes. The material of the first electrode 206 and the second electrode 216 may be selected from a metal, a conductive polymer, a conductive paste, a metallic carbon nanotube or indium tin oxide (ITO).

In this embodiment, the two electrodes 206 are adjacent to opposite sides of the thermo-acoustic element 204 and are disposed in parallel with the through-groove. The first electrode 206 and the second electrode 216 are composed of a wire which can directly press the thermo-acoustic element 204 and be fixed on the substrate 202.

Since the carbon nanotubes have excellent electrical conductivity in the axial direction, when the carbon nanotubes in the carbon nanotube structure are arranged in a certain order, preferably, the first electrode 206 and the second electrode 216 are disposed. It should be ensured that the carbon nanotubes in the carbon nanotube structure extend in the direction from the first electrode 206 to the second electrode 216. Preferably, the first electrode 206 and the second electrode 216 should have a substantially equal spacing therebetween, so that the carbon nanotube structures in the region between the first electrode 206 and the second electrode 216 can have a substantially equal The resistance value, and the length of the first electrode 206 and the second electrode 216 is greater than or equal to the width of the carbon nanotube structure, so that the entire carbon nanotube structure can be utilized. In this embodiment, the carbon nanotubes are arranged substantially perpendicular to the longitudinal direction of the first electrode 206 and the second electrode 216, and the first electrode 206 and the second electrode 216 are disposed in parallel with each other. The audio signal is input to the carbon nanotube structure through the first electrode 206 and the second electrode 216.

It can be understood that since the phonation principle of the thermo-acoustic element 204 is "electric-thermal-acoustic" conversion, the thermo-acoustic element 204 emits a certain amount of heat while vocalizing. In this embodiment, the through-groove structure is beneficial to improve the heat dissipation effect of the thermo-acoustic element 204. Further, the thermo-acoustic device 200 may include a heat dissipating device (not shown) disposed on a surface of the substrate 202 away from the thermo-acoustic element 204.

When the thermal sound generating device 200 is in use, the first electrode 206 and the second electrode 216 can be connected to an audio signal source. The carbon nanotube structure has a small heat capacity per unit area and a large heat dissipation surface. After inputting the signal, the carbon nanotube structure can rapidly rise and fall, generate periodic temperature changes, and rapidly heat with the surrounding medium. Exchange, so that the density of the surrounding medium changes periodically, and then makes a sound. Therefore, the principle of sounding of the thermoacoustic element 204 is "electric-thermal-acoustic" conversion. The thermoacoustic device 200 composed of the above-described thermoacoustic element 204 can emit sound in a gas or liquid medium and has a wide range of applications. Since the carbon nanotube structure has a certain transmittance, when the substrate 202 is a transparent material, the thermo-acoustic device 200 can be a transparent thermo-acoustic device. Further, since the first region 210 of the thermo-acoustic element 204 is suspended, the thermally audible elements 204 of the region 210 are in contact with the surrounding medium on both sides, increasing the area of the carbon nanotube structure in contact with the surrounding gas or liquid medium. And, since the second region 220 of the thermoacoustic element 204 is in contact with and supported by the surface 230 of the substrate 202, the thermoacoustic element 204 is not easily broken.

Referring to FIG. 4 and FIG. 5 , a second embodiment of the present invention provides a thermal sound generating device 300 including a substrate 302 , a thermal sound generating component 304 , a first electrode 306 , and a second electrode 316 . A surface 330 of the substrate 302 has a plurality of openings 308 facing the thermally audible element 304. The thermally audible element 304 is disposed on the surface 302 of the substrate 302 having a recess 308 and covers the openings of the plurality of recesses 308. The first electrode 306 and the second electrode 316 are spaced apart from each other on the surface of the thermoacoustic element 204.

The thermo-acoustic device 300 of the second embodiment has substantially the same structure as the thermo-acoustic device 200 of the first embodiment, except that the recess 308 of the thermo-acoustic device 300 is a through-hole structure. The depth of the through hole is the thickness of the substrate 302, and the shape of the through hole on the surface 330 of the substrate 302 may be rectangular, circular, triangular or other irregular shape. When the surface 330 of the substrate 302 has a plurality of through holes, the plurality of through holes may be uniformly distributed, distributed regularly or randomly distributed on the surface of the substrate 302. When the plurality of through holes are evenly distributed on the surface 330 of the substrate 302, the spacing d2 between the adjacent two through holes is greater than 100 micrometers. In this embodiment, the surface 330 of the substrate 302 has a plurality of circular through holes distributed in an array having a radius of 0.5 mm and a spacing d2 between adjacent through holes of 1 mm. The through-hole structure is easy to shape. When the diameter of the through-hole is controlled to be small, as many through holes as possible can be formed on the surface 330 of the substrate 302, so that the thermo-acoustic element 304 and the surrounding gas or liquid medium have more Contact area.

Referring to FIG. 6 , a third embodiment of the present invention provides a thermal sound generating device 400 including a substrate 402 , a thermal sound generating element 404 , a first electrode 406 , and a second electrode 416 . A surface 430 of the substrate 402 has a plurality of openings 408 facing the recess 408 of the thermoacoustic element 404. The thermally audible element 404 is disposed on the surface 430 of the substrate 402 having the recess 408 and covering the opening of the plurality of recesses 408 . Specifically, the thermoacoustic element 404 has a first region 410 and a second region 420. The thermally audible element 404 of the first region 410 covers the opening of the recess 408 and is suspended. The thermally audible element 404 of the second region 420 is in contact with and supported by the substrate 402.

The thermoacoustic device 400 of the third embodiment is substantially identical in structure to the thermoacoustic device 200 of the first embodiment, except that the first electrode 406 and the second electrode 416 are spaced apart from the thermoacoustic element 404 and the Between the substrates 402. Specifically, the first electrode 406 and the second electrode 416 are directly disposed on the surface 430 of the substrate 402. The thermo-acoustic element 404 covers the first electrode 406 and the second electrode 416.

The first electrode 406 and the second electrode 416 can be the same as the first electrode 206 and the second electrode 216 of the first embodiment, and are a wire fixed on the substrate 402. In addition, since the first electrode 406 and the second electrode 416 are directly formed on the surface 430 of the substrate 402, the first electrode 406 and the second electrode 416 may also be a metal layer formed by screen printing or deposition etching. At this time, the first electrode 406 and the second electrode 416 are formed on the surface 430 of the substrate 402 that is in contact with the second region 420 of the thermoacoustic element 404. In this embodiment, the first electrode 406 and the second electrode 416 are conductive silver paste layers formed by screen printing. In this embodiment, the first electrode 406 and the second electrode 416 are disposed on the surface 430 of the substrate 402 prior to the thermal sound generating element 404. Therefore, the first electrode 406 and the second electrode 416 have a simpler forming manner, which is advantageous for industrialization. application.

Referring to FIG. 7 , a fourth embodiment of the present invention provides a thermal sound generating device 500 including a substrate 502 , a thermal sound generating element 504 , a plurality of first electrodes 506 , and a plurality of second electrodes 516 . A surface 530 of the substrate 502 has a plurality of openings 508 facing the thermally audible element 504. The thermally audible element 504 is disposed on the surface 530 of the substrate 502 having a recess 508 and covers the openings of the plurality of recesses 508. The plurality of first electrodes 506 and the plurality of second electrodes 516 are spaced between the thermo-acoustic element 504 and the substrate 502.

The thermo-acoustic device 500 of the fourth embodiment has substantially the same structure as the thermo-acoustic device 400 of the third embodiment, except that the thermo-acoustic device 500 includes a plurality of first electrodes 506 and a plurality of second electrodes 516. The plurality of first electrodes 506 and the plurality of second electrodes 516 are spaced apart from each other between the thermo-acoustic element 504 and the substrate 502. The heights of the plurality of first electrodes 506 and the plurality of second electrodes 516 are not limited. Preferably, the plurality of first electrodes 506 and the plurality of second electrodes 516 have a height of 1 micrometer to 200 micrometers.

Further, the plurality of first electrodes 506 and the plurality of second electrodes 516 are spaced apart in an abab manner. The plurality of first electrodes 506 are electrically connected, and the plurality of second electrodes 506 are electrically connected such that the thermo-acoustic element 504 between the adjacent first electrode 506 and the second electrode 506 inputs an audio signal.

This connection is such that the thermally audible elements 504 between the adjacent first electrode 506 and the second electrode 506 are connected in parallel to each other, thereby reducing the voltage required to drive the thermoacoustic element 504 to sound.

Referring to FIG. 8 and FIG. 9 , a fifth embodiment of the present invention provides a thermal sound generating device 600 including a substrate 602 , a thermal sound generating element 604 , a first electrode 606 , and a second electrode 616 . A surface 630 of the substrate 602 has a plurality of openings 608 facing the thermally audible element 604. The thermally audible element 604 is disposed on the surface 630 of the substrate 602 having a recess 608 and covers the openings of the plurality of recesses 608. The first electrode 606 and the second electrode 616 are spaced apart from each other and electrically connected to the thermo-acoustic element 604.

The thermo-acoustic device 600 of the fifth embodiment has substantially the same structure as the thermo-acoustic device 200 of the first embodiment, except that the concave portion 608 of the thermo-acoustic device 600 is a blind groove structure. The depth of the blind groove is smaller than the thickness of the substrate 602, and the length of the blind groove is not limited. The shape of the blind groove on the surface 630 of the substrate 602 may be rectangular, arcuate, polygonal, oblate, or other irregular shape. Referring to FIG. 10, the thermo-acoustic device 600 has a recess 608a, and the cross-section of the recess 608a perpendicular to its longitudinal direction may be semi-circular. Referring to Fig. 11, the thermoacoustic device 600 has a recess 608b whose cross section perpendicular to the longitudinal direction thereof may be a triangle. In addition, the recess may also be trapezoidal or other irregular shape. When the surface 630 of the substrate 602 has a plurality of blind grooves, the plurality of blind grooves may be uniformly distributed, distributed in a regular pattern or randomly distributed on the surface 630 of the substrate 602. Referring to FIG. 12, the thermo-acoustic device 600 has a plurality of concave portions 608c which are blind grooves, and when the plurality of blind grooves are parallel to each other and evenly distributed on the surface 630 of the substrate 602, adjacent two blinds The groove pitch d3 of the groove may be close to zero, that is, the area where the substrate 602 is in contact with the thermo-acoustic element 604 is a plurality of lines. It can be understood that in other embodiments, by changing the shape of the recess 608, the area where the thermo-acoustic element 604 contacts the substrate 602 is a plurality of points, that is, between the thermo-acoustic element 604 and the substrate 602. Point contact, line contact or face contact.

In this embodiment, the surface 630 of the substrate 602 has a plurality of rectangular blind grooves arranged in parallel at equal intervals, the groove width is 1 mm, and the spacing d3 between each two adjacent through grooves is 1 mm.

The concave portion 608 in the thermoacoustic device 600 of the present embodiment has a blind groove structure. The blind groove structure is more advantageous than the channel structure to reflect the sound waves emitted by the thermo-acoustic element 604, thereby enhancing the vocal intensity of the thermo-acoustic device 600 on the side of the thermo-acoustic element 604. When the distance d3 between the adjacent blind grooves is close to zero, the substrate 602 can support both the thermo-acoustic element 604 and the maximum surface area of the thermo-acoustic element 604 in contact with the surrounding medium.

It can be understood that when the depth of the blind groove reaches a certain value, the sound wave reflected by the blind groove will be superimposed with the original sound wave, thereby causing destructive interference and affecting the sounding effect of the thermo-acoustic element 604. To avoid this, it is preferred that the blind groove has a depth of less than 10 mm. In addition, when the depth of the blind groove is too small, the thermal sound generating element 604 suspended by the substrate 602 is too close to the substrate 602, which is disadvantageous for heat dissipation of the thermoacoustic element 604. Preferably, the blind trench has a depth greater than 10 microns.

Referring to FIG. 13 and FIG. 14 , a sixth embodiment of the present invention provides a thermal sound generating device 700 including a substrate 702 , a thermal sound generating element 704 , a first electrode 706 , and a second electrode 716 . A surface 730 of the substrate 702 has a plurality of recesses 708 that open toward the thermally audible elements 704. The thermally audible elements 704 are disposed on the surface 730 of the substrate 702 having recesses 708 and cover the openings of the plurality of recesses 708. The first electrode 706 and the second electrode 716 are spaced apart from each other and electrically connected to the thermo-acoustic element 704.

The thermo-acoustic device 700 of the sixth embodiment has substantially the same structure as the thermo-acoustic device 600 of the fifth embodiment, except that the recess 708 of the thermo-acoustic device 700 has a blind hole structure. The depth of the blind via is less than the thickness of the substrate 702, and the shape of the blind via on the surface 730 of the substrate 702 may be rectangular, circular, triangular or other irregular shape. When the surface 730 of the substrate 702 has a plurality of blind holes, the plurality of blind holes may be uniformly distributed, distributed in a regular pattern or randomly distributed on the surface of the substrate 702. When the plurality of blind holes are evenly distributed on the surface 730 of the substrate 702, the spacing d4 between the adjacent two blind holes may be close to zero. In this embodiment, the surface 730 of the substrate 702 has a plurality of circular blind holes distributed in an array, the radius of the blind holes is 0.5 mm, the spacing d4 between adjacent blind holes is 1 mm, and the depth of the blind holes is The radius of the blind hole.

The blind hole structure is easy to shape. When the diameter of the blind hole is controlled to be small, as many blind holes as possible can be formed on the surface 730 of the substrate 702, so that the thermo-acoustic element 704 has more contact area with the surrounding medium. When the distance d4 between the adjacent blind holes is close to zero, the substrate 702 can support both the thermo-acoustic element 704 and the maximum surface area of the thermo-acoustic element 704 in contact with the surrounding medium.

It can be understood that in the above-mentioned thermal sound generating device, the concave portion is not necessarily limited to the groove structure or the hole structure, and the shape of the concave opening can be designed into various figures such as geometric figures, characters or letters, etc., in consideration of other practical needs. Referring to FIG. 15 , a seventh embodiment of the present invention provides a thermal sound generating device 800 including a substrate 802 , a thermal sound generating element 804 , a first electrode 806 , and a second electrode 816 . A surface 830 of the substrate 802 is formed with at least one recess 808 opening toward the thermo-acoustic element 804. The opening of the recess 808 at the surface 830 of the substrate 802 is a continuous spiral structure.

Referring to FIG. 16 , an eighth embodiment of the present invention provides a thermal sound generating device 900 including a substrate 902 , a thermal sound generating element 904 , a first electrode 906 , and a second electrode 916 . A surface 930 of the substrate 902 is formed with an opening toward the at least one recess 908 of the thermo-acoustic element 904. The opening of the recess 908 at the surface 930 of the substrate 902 is a continuous meandering structure.

When the above-mentioned thermo-acoustic device is in use, the thermo-acoustic element performs rapid heat exchange with the surrounding medium under the action of the audio signal, rapidly raises and lowers the temperature according to the frequency of the audio signal, and heats the surrounding medium, and the surrounding medium is heated. The heating of the sound-emitting element changes in density according to the frequency of the audio signal, causing the surrounding medium to rapidly expand and contract, thereby making a sound.

Referring to FIG. 17, a ninth embodiment of the present invention provides a thermo-acoustic device 1000, which includes a substrate 1002, a thermo-acoustic component 1004, and a uniform thermal device 1040. The thermoacoustic element 1004 is located on one side of the substrate 1002 and faces a surface 1030 of the substrate 1002. The surface 1030 of the substrate 1002 has at least one opening toward the recess 1008 of the thermoacoustic element 1004, the recess 1008 has an opening in the surface 1030 of the substrate 1002, and the thermo-acoustic element 1002 has a first region 1010 And a second area 1020. The thermally audible element 1004 of the first region 1010 covers the opening of the recess 1008 and is suspended. The thermally audible element 1004 of the second region 1020 is in contact with and supported by the surface 1030 of the substrate 1002.

The thermo-acoustic device 1000 of the ninth embodiment is substantially identical in structure to the sound-emitting device 200 of the first embodiment, except that the thermo-acoustic device 1000 includes a coherent thermal device 1040 for causing the thermo-acoustic component 1004 heat caused sound.

In this embodiment, the thermo-acoustic component 1004 is spaced from the heating device 1040. The heating device 1040 is a laser or other electromagnetic wave sounding device. The electromagnetic wave signal 1050 emitted from the heating device 1040 is transmitted to the thermoacoustic element 1004.

It will be appreciated that the laser can be placed in the thermo-acoustic component 1004. When the substrate 1002 is a transparent substrate through which the laser light can pass, the laser can be disposed corresponding to the surface of the substrate 1002 away from the thermo-acoustic element 1004, so that the laser light emitted from the laser passes through the substrate 1002 to the thermal sound generation. Element 1004. In addition, when the substrate 1002 includes at least one through hole, even if the substrate 1002 is made of an opaque material, the laser may be disposed corresponding to a surface of the substrate 1002 away from the thermo-acoustic element 1004. In addition, when the electromagnetic device 1040 emits an electromagnetic wave signal, the electromagnetic wave signal can be transmitted to the thermo-acoustic component 1004 through an insulating substrate 1002. At this time, the heating device 1040 can also be away from the substrate 1002. The surface of the thermoacoustic element 1004 is disposed.

Further, the thermo-acoustic device 1000 can include a modulation device 1060 for receiving an electromagnetic wave signal 1050 from the heating device 1040, modulating the intensity and frequency of the electromagnetic wave signal 1050, and modulating the electromagnetic wave. Signal 1050 is passed to the thermo-acoustic component 1004. In this embodiment, the electromagnetic wave signal 1050 is a pulsed laser signal, and the modulation device 1050 is an electro-optic crystal.

In the thermoacoustic device 1000 of the present embodiment, when the thermoacoustic element 1004 is irradiated with electromagnetic waves such as laser light, the thermoacoustic element 1004 is excited by the energy of absorbing electromagnetic waves, and the absorbed light energy is absorbed by non-radiation. Convert all or part of it to heat. The temperature of the thermoacoustic element 1004 changes according to the frequency and intensity of the electromagnetic wave signal 1050, and is rapidly exchanged with the surrounding air or other gas or liquid medium, so that the temperature of the surrounding medium also changes with the frequency. Causes the surrounding medium to expand and contract rapidly, thereby making a sound. Further, in the embodiment, the thermo-acoustic element 1004 is a carbon nanotube structure, and the absorption of electromagnetic waves by the carbon nanotubes is close to an absolute black body, and the frequency of the sound emitted by the carbon nanotube structure is wide. (1Hz~100kHz), the sound effect is better. It can be understood that the thermo-acoustic component 1004 can emit ultrasonic waves when the frequency of the electromagnetic wave signal is increased.

It can be understood that since the thermal sound generating device works by converting a certain form of energy into heat at a very fast speed and performing rapid heat exchange with the surrounding gas or liquid medium, the medium is expanded and contracted, thereby emitting Sound, so in the first to eighth embodiments described above, the first electrode and the second electrode can also be regarded as a uniform heat device by applying a power amplified audio signal to the thermoacoustic element. Thereby, the thermo-acoustic element generates heat, thereby heating the surrounding medium to emit sound. Therefore, those skilled in the art can understand that the energy form is not limited to electric energy or light energy, and the heating device is not limited to the electrode or electromagnetic wave signal generator in the above embodiment, and any of the thermo-acoustic elements can be made. A device that generates heat and heats the surrounding medium in accordance with changes in audio can be considered as a consistent thermal device and is within the scope of the present invention.

In this embodiment, when the thermo-acoustic component is a layer of A4 paper-sized carbon nanotube film, the heating device is an electrode, and a microphone is placed in the positive electrode at an input voltage of 50 volts. The carbon nanotube film is measured at a distance of 5 cm, and the sound intensity of the carbon nanotube film is measured to be 105 dB sound pressure level (dBSPL), and the sound frequency ranges from 100 Hz to 100 kHz (ie, 100 Hz to 100 kHz). When the concave portion is a blind groove structure or a blind hole structure, the depth of the concave portion is preferably 10 μm to 10 mm in order to avoid destructive interference.

The thermo-acoustic device provided by the embodiment of the invention has the following advantages. First, the thermo-acoustic element is disposed on the surface of the substrate and the first region covering the opening of the recess of the substrate is suspended. On the one hand, the substrate can support and fix the thermo-acoustic element, and on the other hand, the concave portion of the substrate The heat emitted from the thermally-sounding element is conducted as little as possible through the substrate, and the recess of the substrate increases the area of contact of the thermally-sounding element with the surrounding medium such that the substrate does not affect the sounding of the thermally-sounding element. Second, the recess of the substrate may be various through-groove structures, through-hole structures, blind-slot structures or blind-hole structures. When the concave portion of the substrate is a through-channel structure or a through-hole structure, the through-channel structure or the through-hole structure facilitates heat dissipation of the thermo-acoustic device, so that the temperature of the thermo-acoustic device is not excessively high. When the concave portion of the substrate is a blind groove structure or a blind hole structure, the blind groove structure or the blind hole structure facilitates reflection of sound, and the sound emitted by the thermo-acoustic element is transmitted to the direction in which the thermally-induced sound-emitting element is away from the substrate.

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 those skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

200,300,400,500,600,700,800,900,1000. . . Thermal sounding device

202, 302, 402, 502, 602, 702, 1002. . . Substrate

204, 304, 404, 504, 604, 704, 804, 904, 1004. . . Thermoacoustic component

206,306,406,506,606,706,806,906. . . First electrode

208,308,408,508,608,608a,608b,608c,708,808,908,1008. . . Concave

210,410,1010. . . First area

216,316,416,516,616,716,816,916. . . Second electrode

220,420,1020. . . Second area

230,330,430,530,630,730,1030. . . surface

1040. . . Heating device

1050. . . Electromagnetic wave signal

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a top plan view showing a thermoacoustic device according to a first embodiment of the present invention.

Figure 2 is a cross-sectional view of the thermoacoustic device of Figure 1 taken along line II-II'.

Figure 3 is a scanning electron micrograph of a carbon nanotube film in a thermoacoustic device of the present invention.

Fig. 4 is a top plan view showing a thermoacoustic device according to a second embodiment of the present invention.

Figure 5 is a cross-sectional view of the thermoacoustic device shown in Figure 4 taken along line V-V'.

Figure 6 is a cross-sectional view showing a thermoacoustic device according to a third embodiment of the present invention.

Figure 7 is a cross-sectional view showing a thermoacoustic device according to a fourth embodiment of the present invention.

Figure 8 is a top plan view showing a thermoacoustic device according to a fifth embodiment of the present invention.

Figure 9 is a front elevational view showing a thermoacoustic device according to a fifth embodiment of the present invention.

Figure 10 is a front elevational view showing a thermoacoustic device having a semicircular blind groove structure in accordance with a fifth embodiment of the present invention.

Figure 11 is a front elevational view showing a thermally induced sound generating device having a triangular blind groove structure in accordance with a fifth embodiment of the present invention.

Figure 12 is a front elevational view showing a thermoacoustic device having a zigzag blind groove structure in accordance with a fifth embodiment of the present invention.

Figure 13 is a top plan view showing a thermoacoustic device according to a sixth embodiment of the present invention.

Figure 14 is a cross-sectional view of the thermoacoustic device shown in Figure 13 taken along the line XIV-XIV'.

Figure 15 is a top plan view showing a thermoacoustic device according to a seventh embodiment of the present invention.

Figure 16 is a top plan view showing a thermoacoustic device according to an eighth embodiment of the present invention.

Figure 17 is a front elevational view showing a thermoacoustic device according to a ninth embodiment of the present invention.

200. . . Thermal sounding device

204. . . Thermoacoustic component

206. . . First electrode

208. . . Concave

216. . . Second electrode

Claims (36)

A thermo-acoustic device comprising: a substrate having a surface; a thermo-acoustic element located on one side of the substrate facing the surface of the substrate; and a first electrode and a second electrode spaced apart And electrically connecting with the thermo-acoustic element; the improvement is that a surface of the substrate is formed with a recess facing the concave portion of the thermo-acoustic element, and the thermo-acoustic element has a first region and a second region. The first region and the second region are located between the first electrode and the second electrode, and the thermo-acoustic element of the first region covers the recess opening and is suspended, the thermo-acoustic component of the second region Contacting the surface of the substrate. The thermoacoustic device according to claim 1, wherein the substrate surface is further formed with a plurality of the concave portions, the plurality of concave portions being uniformly distributed, distributed in a regular pattern or randomly distributed. The thermoacoustic device of claim 2, wherein the first region covers the plurality of recess openings, respectively. The thermoacoustic device according to claim 1, wherein the shape of the recess opening is a geometric figure, a letter or a letter shape. The thermal sound generating device of claim 1, wherein the recess comprises one or more of a through groove structure, a through hole structure, a blind groove structure, and a blind hole structure. The thermoacoustic device according to claim 5, wherein the through-groove structure or the blind groove structure are arranged in parallel with each other on a surface of the substrate. The thermo-acoustic device according to claim 6, wherein the groove spacing of each of the two adjacent groove structures or the blind groove structure is equal. The thermal sound generating device of claim 5, wherein the through hole structure or the blind hole structure is distributed in an array on a surface of the substrate. The thermoacoustic device according to claim 5, wherein the blind groove structure or the blind hole structure has a depth of 10 micrometers to 10 millimeters. The thermoacoustic device according to claim 1, wherein the substrate is made of glass, ceramic, quartz, diamond, plastic, resin or wood material. The thermoacoustic device according to claim 1, wherein the substrate is a transparent substrate. The thermoacoustic device according to claim 1, wherein the first electrode and the second electrode are disposed on a side of the thermo-acoustic element facing away from the substrate or disposed on the thermo-acoustic element Between the substrate and the substrate. The thermoacoustic device according to claim 1, wherein the first electrode and the second electrode are disposed on a surface of the substrate in contact with the second region of the thermoacoustic element. The thermo-acoustic device according to claim 1, wherein the thermo-acoustic device comprises a plurality of the first electrodes and the second electrodes arranged alternately, and the plurality of first electrodes are electrically connected The plurality of second electrodes are electrically connected to each other. The thermoacoustic device according to claim 1, wherein the thermoacoustic element has a heat capacity per unit area of less than 2 x 10 ^-4 joules per square centimeter of Kelvin. The thermoacoustic device according to claim 1, wherein the thermoacoustic element has a sound emission frequency of 1 Hz to 100 kHz. The thermoacoustic device according to claim 1, wherein the thermoacoustic element comprises a carbon nanotube structure. The thermoacoustic device according to claim 17, wherein the carbon nanotube structure comprises a carbon nanotube film, a plurality of stacked carbon nanotube films or a plurality of coplanar surfaces. Carbon tube film. The thermoacoustic device of claim 18, wherein the carbon nanotube film comprises a plurality of substantially parallel carbon nanotubes, the carbon nanotubes being substantially parallel to a surface of the substrate. The thermoacoustic device according to claim 19, wherein the carbon nanotubes in the carbon nanotube film extend in a direction from the first electrode to the second electrode. A thermo-acoustic device comprising: a substrate having a surface; a thermo-acoustic element located on one side of the substrate facing the surface of the substrate; and a uniform thermal device for thermally inducing the thermo-acoustic element Sounding; the improvement is that a surface of the substrate is formed with a plurality of openings facing the concave portion of the thermo-acoustic element, the thermo-acoustic element is in contact with the surface of the substrate, and at least a portion of the opening of the recess is covered to enable A portion of the thermo-acoustic element is suspended relative to the surface of the substrate. The thermoacoustic device according to claim 21, wherein the heating device comprises a first electrode and a second electrode spaced apart from each other and electrically connected to the thermo-acoustic element for use in heat The audible component is energized by an alternating current. The thermoacoustic device according to claim 21, wherein the thermoacoustic element comprises a carbon nanotube structure. The thermoacoustic device according to claim 23, wherein the carbon nanotube structure comprises a carbon nanotube film, a plurality of laminated carbon nanotube films or a plurality of coplanar surfaces. Carbon tube film. The thermal sound generating device of claim 21, wherein the concave portion comprises one or more of a through groove structure, a through hole structure, a blind groove structure, and a blind hole structure. The thermoacoustic device according to claim 21, wherein the shape of the recess opening is a geometric figure, a letter or a letter shape. The thermo-acoustic device according to claim 21, wherein the heating device is a laser for transmitting a laser signal of varying intensity to the thermo-acoustic component to thermally excite the thermo-acoustic component. A thermo-acoustic device comprising: a substrate having a surface; a thermally-induced sounding film on one side of the substrate facing the surface of the substrate; and a uniform thermal device for thermally inducing the thermal-acoustic film An improvement in that the surface of the substrate is formed with a recess facing the concave portion of the thermoacoustic film, the thermoacoustic film having a first region and a second region, the first of the thermoacoustic film The region covers the recess opening and is not in contact with the substrate, and the thermally audible film of the second region is in surface contact with the surface of the substrate. The thermoacoustic device according to claim 28, wherein the heating device comprises a first electrode and a second electrode spaced apart from each other and electrically connected to the thermoacoustic film for use in heat The acoustic film is caused to pass through an alternating current to cause it to be thermally audible. The thermoacoustic device according to claim 28, wherein the thermoacoustic film comprises a plurality of substantially parallel carbon nanotubes, the carbon nanotubes being substantially parallel to a surface of the substrate. The thermoacoustic device according to claim 28, wherein the second region of the thermoacoustic film is continuous, and the second region surrounds the first region. The thermoacoustic device according to claim 31, wherein the first region of the thermoacoustic film is a continuous spiral structure or a meandering structure. The thermoacoustic device according to claim 31, wherein the first region of the thermoacoustic film is composed of a plurality of discontinuous portions. The thermoacoustic device according to claim 30, wherein the first electrode and the second electrode are elongated and substantially parallel, and the carbon nanotube is substantially parallel to the first electrode and the second electrode. vertical. The thermoacoustic device according to claim 28, wherein the shape of the recess opening is a geometric figure, a letter or a letter shape. The thermo-acoustic device according to claim 28, wherein the heating device is a laser for transmitting a laser signal of varying intensity to the thermally-induced acoustic film to thermally vocalize the thermo-acoustic film.