A thermoacoustic units includes at least one first electrode, at least one second electrode, a sound wave generator electrically connected with the at least one first electrode and the at least one second electrode, a housing, and at least one socket connector. The housing receives the at least one first electrode, the at least one second electrode, and the sound wave generator therein. The at least one socket connector is located on the housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims all benefits accruing under 35 U.S.C. §119 from China Patent Application No. 200910210787.3, filed on Nov. 10, 2009, in the China Intellectual Property Office.

BACKGROUND

1. Technical Field

The present disclosure relates to acoustic devices and, particularly, to a thermoacoustic device.

2. Description of Related Art

An acoustic device generally includes a signal device and a loudspeaker. The signal device provides electrical signals to the loudspeaker. The loudspeaker receives the electrical signals and then transforms them into sounds audible to humans.

There are different types of loudspeakers that can be categorized according to their working principles, such as electro-dynamic loudspeakers, electromagnetic loudspeakers, electrostatic loudspeakers and piezoelectric loudspeakers. However, the various types ultimately use mechanical vibration to produce sound waves, in other words they all achieve “electro-mechanical-acoustic” conversion. Among the various types, the electro-dynamic loudspeakers are most widely used. However, the electro-dynamic loudspeakers are dependent on magnetic fields and often weighty magnets. The structures of the electric-dynamic loudspeakers are complicated. The magnet of the electric-dynamic loudspeakers may interfere or even damage other electrical devices near the loudspeakers.

Thermoacoustic effect is a conversion of heat into acoustic signals. The thermoacoustic effect is distinct from the mechanism of the conventional loudspeaker, in which the pressure waves are created by the mechanical movement of the diaphragm. When signals are supplied to a thermoacoustic element, heat is produced in the thermoacoustic element according to the variations of the signal and/or signal strength. The heat propagates into surrounding medium. The heating of the medium causes thermal expansion and produces pressure waves in the surrounding medium, resulting in sound wave generation. Such an acoustic effect induced by temperature waves is commonly called “the thermoacoustic effect”.

Carbon nanotubes (CNT) are a novel carbonaceous material having extremely small size and extremely large specific surface area. Carbon nanotubes have received a great deal of interest since the early 1990s, and have interesting and potentially useful electrical and mechanical properties, and have been widely used in a plurality of fields. Xiao et al. discloses an thermoacoustic device with simpler structure and smaller size, working without the magnet in an article of “Flexible, Stretchable, Transparent Carbon Nanotube Thin Film Loudspeakers”, Xiao et al., Nano Letters, Vol. 8 (12), 4539-4545 (2008). The thermoacoustic device includes a carbon nanotube film loudspeaker. The carbon nanotube film used in the thermoacoustic device has a large specific surface area, and extremely small heat capacity per unit area that make the sound wave generator emit sound audible to humans. Accordingly, the thermoacoustic device adopted the carbon nanotube film has a potential to be actually used instead of the loudspeakers in prior art.

However, the drawn carbon nanotube film is formed by drawing from a carbon nanotube array. The size of a single drawn carbon nanotube film is limited by the size of the carbon nanotube array. Thus, the size of the loudspeaker is difficult to be enlarged. Further, the carbon nanotube film drawn from the carbon nanotube array is very thin and weak. Therefore, when the large single carbon nanotube film is used, it is hard to avoid damage of the carbon nanotube film. Therefore, a large loudspeaker is difficult to be achieved.

What is needed, therefore, is to provide a well protected thermoacoustic device with a desired large size.

DETAILED DESCRIPTION

Referring toFIG. 1, a thermoacoustic device100according to an embodiment includes a plurality of thermoacoustic units10connected together by at least one connector assembly. The at least one connector assembly electrically and mechanically connects the thermoacoustic units10in parallel. Each thermoacoustic unit10is an independent member that can be detached from the thermoacoustic device100. Each thermoacoustic unit10includes a sound wave generator14that is capable of producing audible sounds using a thermoacoustic principle.

Sound Wave Generator

The sound wave generator14has a very small heat capacity per unit area. The heat capacity per unit area of the sound wave generator14is less than or equal to 2×10−4J/cm2*K. The sound wave generator14can be a conductive structure with a small heat capacity per unit area and a small thickness. The sound wave generator14can have a large specific surface area for causing the pressure oscillation in the surrounding medium by the temperature waves generated by the sound wave generator14. The sound wave generator14can be a free-standing structure. The term “free-standing” includes, but is not limited to, a structure that does not have to be supported by a substrate and can sustain the weight of it when it is hoisted by a portion thereof without any significant damage to its structural integrity. The suspended part of the sound wave generator14will have more sufficient contact with the surrounding medium (e.g., air) to have heat exchange with the surrounding medium from both sides of the sound wave generator14. The sound wave generator14is a thermoacoustic film.

The sound wave generator14can be or include a free-standing carbon nanotube structure. The carbon nanotube structure may have a film structure. The thickness of the carbon nanotube structure may range from about 0.5 nanometers to about 1 millimeter. The carbon nanotubes in the carbon nanotube structure are combined by van der Waals attractive force therebetween. The carbon nanotube structure has a large specific surface area (e.g., above 30 m2/g). The larger the specific surface area of the carbon nanotube structure, the smaller the heat capacity per unit area will be. The smaller the heat capacity per unit area, the higher the sound pressure level of the sound produced by the sound wave generator14. The heat capacity per unit area of the carbon nanotube structure can be less than or equal to 2×10−4J/cm2*K. In one embodiment, the heat capacity per unit area of the carbon nanotube structure is less than or equal to about 1.7×10−6J/cm2*K.

The carbon nanotubes in the carbon nanotube structure can be arranged orderly or disorderly. The term ‘disordered carbon nanotube structure’ includes a structure where the carbon nanotubes are arranged along many different directions, such that the number of carbon nanotubes arranged along each different direction can be almost the same (e.g. uniformly disordered), and/or entangled with each other. The disordered carbon nanotube structure can be isotropic. ‘Ordered carbon nanotube structure’ includes a structure where the carbon nanotubes are arranged in a systematic manner, e.g., the carbon nanotubes are arranged approximately along a same direction and or have two or more sections within each of which the carbon nanotubes are arranged approximately along a same direction (different sections can have different directions). It is understood that even ordered carbon nanotube structures can have some variations therein.

The carbon nanotubes in the carbon nanotube structure can be single-walled, double-walled, or multi-walled carbon nanotubes. It is also understood that there may be many layers of ordered and/or disordered carbon nanotube films in the carbon nanotube structure.

The carbon nanotube structure may have a substantially planar structure. The thickness of the carbon nanotube structure may range from about 0.5 nanometers to about 1 millimeter. The carbon nanotube structure can also be a wire with a diameter ranged from about 0.5 nanometers to about 1 millimeter. The larger the specific surface area of the carbon nanotube structure, the smaller the heat capacity per unit area will be. The smaller the heat capacity per unit area, the higher the sound pressure level of the sound produced by the sound wave generator14. The carbon nanotube structure can include at least one carbon nanotube film.

In some embodiments, the carbon nanotube structure can include at least one drawn carbon nanotube film. The drawn carbon nanotube film includes a plurality of successive and oriented carbon nanotubes joined end-to-end by van der Waals attractive force therebetween. The carbon nanotubes in the carbon nanotube film can be substantially aligned in a single direction. The drawn carbon nanotube film can be a free-standing film. The drawn carbon nanotube film can be formed by drawing a film from a carbon nanotube array that is capable of having a film drawn therefrom. Referring toFIG. 2andFIG. 3, each drawn carbon nanotube film includes a plurality of successively oriented carbon nanotube segments143joined end-to-end by van der Waals attractive force therebetween. Each carbon nanotube segment143includes a plurality of carbon nanotubes145parallel to each other, and joined by van der Waals attractive force therebetween. As can be seen inFIG. 2, some variations can occur in the drawn carbon nanotube film. The carbon nanotubes145in the drawn carbon nanotube film are also oriented along a preferred orientation. The carbon nanotube film also can be treated with a volatile organic solvent. After that, the mechanical strength and toughness of the treated carbon nanotube film are increased and the coefficient of friction of the treated carbon nanotube films is reduced. The treated carbon nanotube film has a larger heat capacity per unit area and thus produces less of a thermoacoustic effect than the same film before treatment. A thickness of the carbon nanotube film can range from about 0.5 nanometers to about 100 micrometers. The thickness of the drawn carbon nanotube film can be very thin and thus, the heat capacity per unit area will also be very low. The single drawn carbon nanotube film has a specific surface area of above about 100 m2/g. In one embodiment, the drawn carbon nanotube film has a specific surface area ranged from 200 m2/g to 2600 m2/g. The specific surface area of the drawn carbon nanotube film is tested by a Brunauer-Emmet-Teller (BET) method. In one embodiment, the drawn carbon nanotube film has a specific weight of about 0.05 g/m2.

The carbon nanotube structure of the sound wave generator14can also include at least two stacked carbon nanotube films. In some embodiments, the carbon nanotube structure can include two or more coplanar carbon nanotube films. These coplanar carbon nanotube films can also be stacked one upon other films. Additionally, an angle can exist between the orientation of carbon nanotubes in adjacent films, stacked and/or coplanar. Adjacent carbon nanotube films can be combined only by the van der Waals attractive force therebetween and without the use of an adhesive. The number of the layers of the carbon nanotube films is not limited. However, as the stacked number of the carbon nanotube films increasing, the specific surface area of the carbon nanotube structure will decrease, and a large enough specific surface area (e.g., above 50 m2/g) must be maintained thereby achieving sufficient sound volume. An angle between the aligned directions of the carbon nanotubes in the two adjacent carbon nanotube films can range from 0 degrees to about 90 degrees. Spaces are defined between two adjacent and side-by-side carbon nanotubes in the drawn carbon nanotube film. When the angle between the aligned directions of the carbon nanotubes in adjacent carbon nanotube films is larger than 0 degrees, a microporous structure is defined by the carbon nanotubes in the sound wave generator14. The carbon nanotube structure in an embodiment employing these films will have a plurality of micropores. Stacking the carbon nanotube films will add to the structural integrity of the carbon nanotube structure.

In other embodiments, the carbon nanotube structure includes a flocculated carbon nanotube film. The flocculated carbon nanotube film can include a plurality of long, curved, disordered carbon nanotubes entangled with each other. A length of the carbon nanotubes can be above 10 centimeters. Further, the flocculated carbon nanotube film can be isotropic. The carbon nanotubes can be substantially uniformly dispersed in the carbon nanotube film. The adjacent carbon nanotubes are acted upon by the van der Waals attractive force therebetween, thereby forming an entangled structure with micropores defined therein. It is understood that the flocculated carbon nanotube film is very porous. Sizes of the micropores can be less than 10 micrometers. The porous nature of the flocculated carbon nanotube film will increase specific surface area of the carbon nanotube structure. Further, due to the carbon nanotubes in the carbon nanotube structure being entangled with each other, the carbon nanotube structure employing the flocculated carbon nanotube film has excellent durability, and can be fashioned into desired shapes with a low risk to the integrity of carbon nanotube structure. Thus, the sound wave generator14may be formed into many shapes. The flocculated carbon nanotube film, in some embodiments, will not require the use of structural support due to the carbon nanotubes being entangled and adhered together by van der Waals attractive force therebetween. The thickness of the flocculated carbon nanotube film can range from about 0.5 nanometers to about 1 millimeter. It is also understood that many of the embodiments of the carbon nanotube structure are flexible and/or do not require the use of structural support to maintain their structural integrity.

The carbon nanotube structure includes a plurality of carbon nanotubes and has a small heat capacity per unit area and can have a large area for causing the pressure oscillation in the surrounding medium by the temperature waves generated by the sound wave generator14. In use, when electrical signals, with variations in the application of the signal and/or strength are applied to the carbon nanotube structure of the sound wave generator14, heating and variations of heating are produced in the carbon nanotube structure according to the signal. Variations in the signals (e.g. digital, change in signal strength), will create variations in the heating. Temperature waves are propagated into surrounding medium. The temperature waves in the medium cause pressure waves to occur, resulting in sound generation. In this process, it is the thermal expansion and contraction of the medium in the vicinity of the carbon nanotube structure that produces sound. This is distinct from the mechanism of the conventional sound wave generator, in which the pressure waves are created by the mechanical movement of the diaphragm. The operating principle of the sound wave generator14is an “electrical-thermal-sound” conversion.

Each thermoacoustic unit10includes a substrate11, at least one electrode12, at least one second electrode13, a sound wave generator14, a housing15, and at least one socket group. The at least one socket group is located on the housing15, and is capable of mating with a plug connector18thereby connecting the thermoacoustic units10together. The substrate11, at least one electrode12, at least one second electrode13, and sound wave generator14are housed in the housing15.

In the embodiment shown inFIG. 1, the thermoacoustic unit10includes one first electrode12and one second electrode13. The first and second electrodes12,13are spaced from each other, and both electrically connected to the carbon nanotube structure14. Electrical signals are input from the first and second electrodes12,13to the sound wave generator14. The electrical signals can be conducted from the first electrode12to the second electrode13through the sound wave generator14.

Each thermoacoustic unit10includes the at least one first electrode12and the at least one second electrode13. They can be parallel to each other. The first and second electrodes12,13can be disposed either between the sound wave generator14and the substrate11as shown inFIG. 1, or on top of the sound wave generator14. In other embodiments, some of the first and second electrodes12,13can be disposed on the sound wave generator14, and the other first and second electrodes12,13can be located between the substrate11and the sound wave generator14.

The first and second electrodes12,13can have a wire shape, a strip shape, a bar shape, or other shapes. The material of the first and second electrodes12,13can be selected from conductive materials such as metals, alloys, ITO, and conductive polymers. The first and second electrodes12,13can be formed by printing conductive paste on the substrate11. In an embodiment, the first and second electrodes12,13are stainless steel wires with a diameter less or equal to about 2 millimeters fixed on the substrate11.

The carbon nanotube structure in the sound wave generator14has a very large specific surface area, and thus the carbon nanotube structure is adhesive in nature. Therefore, the sound wave generator14can be directly adhered on the first and second electrodes12,13. In other embodiments, a conductive adhesive can be further used to adhere the sound wave generator14to the first and second electrodes12,13. In one embodiment, the conductive adhesive is a silver paste layer.

In one embodiment, the carbon nanotubes in the carbon nanotube structure are substantially aligned along a direction from the first electrodes12to the second electrodes13. When the first electrodes12are parallel to the second electrodes13, the aligned direction of the carbon nanotubes can be substantially perpendicular to the first electrodes12and the second electrodes13.

The substrate11carries and supports the sound wave generator14, the first electrode12and the second electrode13. In one embodiment, the sound wave generator14can be spaced from the substrate11by the first and second electrodes12,13. Thereby, the two surfaces of the sound wave generator14can be both in sufficient contact with surrounding air for a thermal exchange therebetween. A distance between the sound wave generator14and the substrate11can be set as desired. In one embodiment, the distance is about 1 centimeter. The first and second electrodes12,13can be mounted on the substrate11by screws or binder. The first and second electrodes12,13can also be printed on the substrate11.

In other embodiment, the sound wave generator14can also be in contact with the substrate11, thereby being protected by the substrate11. The surface of the substrate11that is in contact with the sound wave generator14can further define one or more heat dissipating recesses. The sound wave generator14covers and is suspended above the heat dissipating recesses. The surface of the substrate11that is in contact with the sound wave generator14can further have a heat reflective film. The heat generated from the sound wave generator14can be reflected by the heat reflective film on the surface of the substrate11.

The material of substrate11can be selected from insulating materials such as glass, resin, plastic, ceramic, and so on. The substrate11provides a protection on one side of the sound wave generator14. In one embodiment, the substrate11is both electrical insulative and thermal insulative. In one embodiment, the substrate11is a rectangle glass board with a length of about 17 centimeters, a width of about 12 centimeters, and a thickness of about 2 millimeters. It is to be understood that the substrate11is optional, and the first and second electrodes12,13can be fixed to the housing15.

The housing15can include a carrying member152and a protecting member154engaged with the carrying member152. The carrying member152is a hollow structure with an opening (not labeled). The carrying member152defines a hollow space1524therein. The substrate11, first and second electrodes12,13, and sound wave generator14are located in the hollow space1524. The protecting member154covers the opening of the carrying member152. There is a distance between the sound wave generator14and the protecting member154. The protecting member154protects the sound wave generator14on the side away from the substrate11.

The carrying member152can have any desired shape with the hollow space housing the substrate11, the first and second electrodes12,13, and the sound wave generator14therein. In the embodiment shown inFIG. 1, the carrying member152has a cubic shape, and includes a floor1520and four sidewalls1522connected to the floor1520. The four sidewalls1522are perpendicular to the floor1520, and define the hollow space1524together with the floor1520. The four sidewalls1522define the opening.

The protecting member154and the opening of the carrying member152can have the same shape and can be mated together. The sidewalls1522can further include spring plates, and the protecting member154can further include notches. The spring plates are mated to the notches when the protecting member154covers the opening. The protecting member154can also fixed on the opening of the carrying member through other means such as screws or binders.

The carrying member152can be made of insulating materials such as glass, ceramic, resin, wood, plastic, silicon, and crystal. In the embodiment shown inFIG. 1, the carrying member152is made of plastic.

The protecting member154is a porous structure with a plurality of through holes therein. The protecting member154can be a mesh weaved of a plurality of metal wires, or plastic plate defining a plurality of through holes. The through holes of the protecting member154dissipate heat generated from the sound wave generator14to the outside.

The protecting member154is spaced from the sound wave generator14with a distance. An insulative spacer can be further located on substrate11to separate the sound wave generator14from the protecting member154.

Each socket group can include a first socket connector16and a second socket connector17. The socket groups are located on the sidewalls1522of the carrying member152of each thermoacoustic unit10. The number of the socket groups on one thermoacoustic unit10can be set as desired. The location of the socket groups can be set along the way that the thermoacoustic units10are connected together.

In the embodiment shown inFIG. 1, each thermoacoustic unit10adopts two socket groups respectively located on the opposite sidewalls1522of the carrying member152. In the thermoacoustic unit10, the first electrode12is connected to the first socket connector16of each of the two socket groups located on the sidewalls1522; and the second electrode13is connected to the second socket connector17of each of the two socket groups located on the sidewalls1522. The first electrode12and second electrode13can be respectively connected to the first socket connector16and the second socket connector17through lead wires, conducting pads, or other connecting means.

The thermoacoustic device100includes two or more thermoacoustic units10and at least one plug connector18connecting the two or more thermoacoustic units10together.

Referring toFIG. 4, the thermoacoustic units10are electrically connected in parallel in a circuit. The first electrodes12in all the thermoacoustic units10are connected together and connected to a first terminal121of a signal output device22. The second electrodes13in all the thermoacoustic units10are connected together and connected to a second terminal131of the signal output device22. The signal output device22can be an amplifier. The amplified audio electrical signals are output from the first and second terminals121,131of the amplifier, and input into every sound wave generator14in every thermoacoustic units10by the first electrodes12and second electrodes13.

Referring toFIG. 5, when the thermoacoustic unit10includes a plurality of first electrodes12and a plurality of second electrodes13, the first electrodes12and the second electrodes13are arranged in a staggered manner (e.g. one first electrode12, one second electrode13, and so on). In other words, the first and second electrodes12,13are alternately connected to the sound wave generator14. In each thermoacoustic unit10, all the first electrodes12are connected together in parallel in the circuit, and all the second electrodes13are connected together in parallel in the circuit. In one embodiment, two conducting pads or conducting wires can be used to respectively connect the first electrodes12together and connect the second electrodes13together. The more the first and second electrodes12,13are used in the thermoacoustic unit10, the lower the drive voltage of the electrical signals is needed to drive the thermoacoustic unit10to produce audible sounds.

The thermoacoustic device100includes at least one connector assembly that is used to connect the thermoacoustic units10together electrically and mechanically. Each connector assembly can include two socket groups of the thermoacoustic unit10and a plug connector18. The two socket groups are adapted to be connected together through the plug connector18.

The plug connector18includes a first cable182, two first plugs186connected to the two ends of the first cable182, a second cable184that is insulated from the first cable182, and two second plugs188connected to the two ends of second cable184. The first plug186is mated with the first socket connector16, the second plug188is mated with the second socket connector17. The first plug186is adapted to be inserted into the first socket connector16, and the second plug188is adapted to be inserted into the second socket connector17. Thus, two thermoacoustic units10can be connected together by one plug connector18therebetween. When and after one first plug186of the plug connector18is inserted into the first socket connector16of one thermoacoustic unit10, and the other first plug186of the plug connector18is inserted into the first socket connector16of another thermoacoustic unit10, the two first electrodes12of the two thermoacoustic unit10are electrically connected together in parallel in the circuit. When and after one second plug188of the plug connector18is inserted into the second socket connector17of one thermoacoustic unit10, and the other second plug188of the plug connector18is inserted into the second socket connector17of another thermoacoustic unit10, the two second electrodes12of the two thermoacoustic units10are electrically connected together in parallel in the circuit. By this means, all the first electrodes12of all the thermoacoustic units10are electrically connected together in parallel in the circuit, and all the second electrodes13of all the thermoacoustic units10are electrically connected together in parallel in the circuit, by a number of plug connectors18in the thermoacoustic device100. Meanwhile, all the thermoacoustic units10are mechanically joined together by the plug connectors18to become the united thermoacoustic device100. All the sound wave generators14are electrically connected in parallel in the circuit. It can be understood that the first cable182and the second cable184can be situated in a single cable. In the single cable, the first cable182and the second cable184should be insulated from each other.

The first and second terminals121,131of the signal output device22can be connected to one thermoacoustic unit10by a plug connector18. The electrical signals output from the signal output device22are conducted from all the first electrodes12through the carbon nanotube structure of the sound wave generators14and reach to the second electrodes13. The voltage changes of the electrical signals causes thermal generating changes of the carbon nanotube structure to produce sounds.

The thermoacoustic unit10can be detached from the thermoacoustic device100by pulling out the plug connector18that is connected to the thermoacoustic unit10. The number of the thermoacoustic units10in the thermoacoustic device100can be set as desired. The thermoacoustic units10can be assembled when in use, and detached when in stored or transport. When one of the thermoacoustic units10is broken down, the broken thermoacoustic unit10can be easily changed from the thermoacoustic device100, due to the modular design. By changing the connecting manner, the thermoacoustic units10can be set along a in the periphery of the room. Meanwhile, all the thermoacoustic units10are connected in parallel in the circuit, and the maximum power of the thermoacoustic device100is larger than that of a single thermoacoustic unit10. Accordingly, the volume of sounds can be increased. To increase or decrease the maximum volume of the thermoacoustic device100, a number of thermoacoustic units10can be attached to or detached from the thermoacoustic device100.

In the thermoacoustic device100, the plurality of thermoacoustic units10can be arranged as an array. Referring toFIG. 6andFIG. 7, the thermoacoustic device100can include a 2×2 array of thermoacoustic units10. Referring toFIG. 6, the location of the socket group on the housing15of the thermoacoustic units10can be the same, and the 2×2 array of the thermoacoustic units10is mechanically folded from a linear connected group of four thermoacoustic units10. The four thermoacoustic units10are the same. Referring toFIG. 7, the locations of the socket group on the housing15of the thermoacoustic units10can be different. Some of the thermoacoustic units10have their socket groups on two connected sidewalls1522of the housing15. The arrangement of the inner lead wires in the housing15connected the first and second electrodes12,13to the first and second socket connectors16,17can be changed accordingly. It is understood that the all of the side walls can have first and second socket connectors16,17.

Referring toFIG. 8, a thermoacoustic device200according to an embodiment includes a plurality of thermoacoustic units10connected together by a plurality of connector assemblies. Each connector assembly can include a first socket connector26, a second socket connector27, a first plug28and a second plug29. Each of the thermoacoustic unit10can include at least one first and second socket connectors26,27, and/or at least one first and second plugs28,29. The first socket connector26is adapted to be connected to the first plug28. The second socket connector27is adapted to be connected to the second plug29. The first and second plugs28,29each have a pin shape. The first socket connector26and the first plug28are insulated from the second socket connector27and the second plug29.

The first and second socket connectors26,27can be located on one sidewall1522of the carrying member152of each thermoacoustic unit10. The first and second plugs28,29can be located on the other opposite sidewall1522of the carrying member152of each thermoacoustic unit10. In an 2×2 or more array of thermoacoustic units10, the first and second plugs28,29and the first and second socket connectors26,27in some of the thermoacoustic units10can located on the connected sidewalls1522of the carrying member152.

The first socket connector26and the first plug28are both electrically connected to the first electrode12of the thermoacoustic unit10. The second socket connector27and the second plug28are both electrically connected to the second electrode13of the thermoacoustic unit10. By inserting the first plug28to the first socket connector26and inserting the second plug29to the second socket connector27, all the first electrodes12of all the thermoacoustic units10are connected together in parallel and all the second electrodes13of all the thermoacoustic units10are connected together in parallel. Accordingly, the thermoacoustic units10are electrically connected in parallel in the circuit. The first and second terminals of the signal input device22can be electrically connected to the first socket connector26and the second socket connector27.

Referring toFIG. 9, more specifically, the first plug28can be mated to the first socket connector26. The first socket connector26can include a through hole264defined by the sidewall1522, and a conducting sleeve pad262attached on the inner wall of the through hole264. The conducting sleeve pad262is electrically connected to the first electrode12by lead wire. The first plug28can be locked on the sidewall1522of the thermoacoustic unit10. The sidewall1522can define an opening284, and a recess286can be located on the opening284. The first plug28can include a resilient buckle282. The resilient buckle282can be resilient deformed under pressure. The resilient buckle282is mated with the recess286of the opening284, and thereby coupled to the sidewall1522. Another conducting sleeve pad288can be attached on the inner wall of the opening284and in contact with the first plug28. The conducting sleeve pad288is electrically connected to the first electrode12by lead wire. Thus, different first electrodes12in different thermoacoustic units10can be electrically connected together in parallel in the circuit.

The mating of the second plug29and the second socket connector27is similar to the first plug28and the first socket connector26. Thus, all the sound wave generators14of all the thermoacoustic units10are electrically connected in parallel in the circuit.

In the embodiment shown inFIG. 8, the thermoacoustic units10can be closely connected with each other, thereby reducing the size of the thermoacoustic device100.

Referring toFIG. 10andFIG. 11, a thermoacoustic device300according to an embodiment includes more than one thermoacoustic unit10connected together by one or more connector assemblies. Each connector assembly can include a first socket connector362, a second socket connector364and a plug connector37. The plug connector37can have a pin shape with two opposite plug ends. The first and second socket connectors362,364in the same connector assembly are respectively located on the carrying members152of two thermoacoustic units10. Each thermoacoustic unit10can include one first socket connector362connected to the first electrode12and/or one second socket connector364connected to the second electrode13. The first socket connector362and second socket connector364can be located on two opposite sidewalls1522of the thermoacoustic unit10. The two plug ends of the plug connector37can be respectively mated with the first and second socket connectors362,364. Thereby, the first electrode12in one thermoacoustic unit10is connected to the second electrode13in another thermoacoustic unit10, and all the thermoacoustic units10are electrically connected in serial in the circuit.

It is to be understood that the above-described embodiments are intended to illustrate rather than limit the invention. Any elements described in accordance with any embodiments is understood that they can be used in addition or substituted in other embodiments. Embodiments can also be used together. Variations may be made to the embodiments without departing from the spirit of the invention. The above-described embodiments illustrate the scope of the invention but do not restrict the scope of the invention.