Patent Publication Number: US-9906865-B2

Title: Piezoelectric loudspeaker

Description:
BACKGROUND OF THE INVENTION 
     (a) Field of the Invention 
     The present invention relates to a piezoelectric loudspeaker, and more particularly to an ultra-thin structure of a piezoelectric loudspeaker. 
     (b) Description of the Prior Art 
     A piezoelectric loudspeaker is also called a ceramic loudspeaker, and comprises an oscillator composed of a metal sheet and multiple layers of piezoelectric ceramic sheets. Alternating voltage is inputted to the oscillator, such that the oscillator can curve and oscillate. Longitudinal vibrator type, dual-state type, piezoelectric polymer type, and many other types of piezoelectric loudspeakers are known to have thin and small-sized characteristics. 
     The oscillator of a conventional piezoelectric loudspeaker is quite thin and usually applied to mobile phones or tablet personal computers. The flaky oscillator is connected with an essential electrical wire or signal line by welding, and then the oscillator is adhered to the circuit board of a mobile phone. The assembly and welding procedure are complicated, and the quality of weld will have a great effect on the sound produced. The inventor of the present invention has invented a piezoelectric loudspeaker as disclosed in U.S. Pat. No. 8,053,954 to overcome the aforesaid problems. 
     The piezoelectric oscillator as disclosed in U.S. Pat. No. 8,053,954 is composed of two sheets. A shock absorption member is provided at the middle of the oscillator close to a fixed end thereof. However, the amplitude of oscillation of a free end of the oscillator, opposite the fixed end, may be so large that the piezoelectric loudspeaker may have noises to influence the quality of the sound. Accordingly, the inventor of the present invention has devoted himself with his many years of practical experiences to solve these problems. 
     SUMMARY OF THE INVENTION 
     The primary object of the present invention is to provide a piezoelectric loudspeaker that has a structure to reduce noises. Through damping members disposed in the piezoelectric loudspeaker and the assembled structure of the damping members and an oscillator and a loudspeaker box, it is easy to install the damping members and the noises can be reduced effectively. 
     In order to achieve the aforesaid object, the piezoelectric loudspeaker of the present invention comprises a loudspeaker box, an oscillator, two damping members, and a plurality of terminals. The loudspeaker box comprises a main body and a cover. The main body has an accommodation trough at one side thereof, at least one positioning portion located at a first end of the accommodation trough, and a first retaining trough located at a second end of the accommodation trough. The cover has a second retaining trough. The cover is adapted to cover the accommodation trough of the main body. An oscillator is disposed in the accommodation trough of the main body of the loudspeaker box. The oscillator comprises a plate and two piezoelectric members coupled to two sides of the plate. The plate has a fixed end coupled to the positioning portion at the first end of the accommodation trough and a free end extending toward the first retaining trough at the second end of the accommodation trough. The two damping members are made of silicone and disposed in the first retaining trough of the loudspeaker box and the second retaining trough of the cover, respectively. The two damping members are pressed against an edge of the free end of the plate of the oscillator. The plurality of terminals are disposed in the accommodation trough of the main body of the loudspeaker box and electrically connected with the oscillator. 
     Through the damping members made of silicone, the present invention provides a better shock absorption effect to effectively reduce the noises caused by the free end of the oscillator and to effectively enhance the tone. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the piezoelectric loudspeaker of the present invention; 
         FIG. 2  is another perspective view of the piezoelectric loudspeaker of the present invention; 
         FIG. 3  is an exploded view of the piezoelectric loudspeaker of the present invention; 
         FIG. 4  is a perspective view of the cover of the present invention; 
         FIG. 5  is an exploded view of the oscillator of the present invention; 
         FIG. 6  is a sectional view of the piezoelectric loudspeaker of the present invention; 
         FIG. 7  is a partial enlarged view of the piezoelectric loudspeaker of the present invention; 
         FIG. 8  is a perspective view of the first terminal of the present invention; 
         FIG. 9  is a sectional view of the first terminal of the present invention when in use; 
         FIG. 10  is a perspective view of another first terminal of the present invention; 
         FIG. 11  is a sectional view of another first terminal of the present invention when in use; 
         FIG. 12  is a perspective view of the second terminal of the present invention; 
         FIG. 13  is a sectional view of the second terminal of the present invention when in use; 
         FIG. 14  is a perspective view of another embodiment of the loudspeaker box of the present invention; and 
         FIG. 15  is a perspective view of a further embodiment of the loudspeaker box of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings. 
     As shown in  FIG. 1 ,  FIG. 2  and  FIG. 3 , a piezoelectric loudspeaker according to a preferred embodiment of the present invention comprises a loudspeaker box  1 , an oscillator  2 , two damping members  3 , and a plurality of terminals  4   a ,  4   b ,  5 . The loudspeaker box  1  comprises a rectangular main body  11  and a cover  12 . The main body  11  has an accommodation trough  13  at one side thereof, at least one positioning portion  14  located at a first end of the accommodation trough  13 , and a first retaining trough  15  located at a second end of the accommodation trough  13 . The cover  12  has a second retaining trough  16 , as shown in  FIG. 4 . When the cover  12  covers the accommodation trough  13  of the loudspeaker box  11 , the retaining trough  16  corresponds to the first retaining trough  15 . The oscillator  2  is disposed in the accommodation trough  13  of the main body  11  of the loudspeaker box  1 . The oscillator  2  comprises a plate  21  and piezoelectric members  22  coupled to two sides of the plate  21 , as shown in  FIG. 5 . A circumferential portion of the plate  21  has a plurality of positioning protrusions  211 . The plate  21  has a fixed end coupled to the positioning portion  14  at the first end of the accommodation trough  13  and an opposing free end extending toward the first retaining trough  15  at the second end of the accommodation trough  13 , such that the oscillator  2  is suspended in the accommodation trough  13 , as shown in  FIG. 6 . The piezoelectric members  22  can be ceramic piezoelectric sheets, which are coupled to the two sides of the plate  21  and limited by the positioning protrusions  211 . The two damping members  3  are made of silicone and disposed in the first retaining trough  15  of the loudspeaker box  1  (as shown in  FIG. 3 ) and the second retaining trough  16  of the cover  12  (as shown in  FIG. 4 ), respectively. The two damping members  3  are pressed against the positioning protrusions  211  at the free end of the plate  21  of the oscillator  2 , as shown in  FIG. 7 . The terminals  4   a ,  4   b ,  5  are disposed in the accommodation trough  13  of the main body  11  of the loudspeaker box  1 , and are electrically connected with the plate  21  and the piezoelectric members  22  of the oscillator  2 . For the piezoelectric loudspeaker of the present invention, there is no need to use double-sided adhesive tape or a fixing member for installing the damping members  3 . It is easy to install the damping members. Through the damping members  3  made of silicone, the present invention provides a better shock absorption effect to effectively reduce the noises caused by the free end of the oscillator  2  and to effectively enhance the tone. 
     As shown in  FIG. 3  and  FIG. 4 , each damping member  3  of the present invention is preferably made of silicone, and comprises two press portions  31  and a fixing portion  32  connected between the two press portions  31 . The two press portions  31  are integrally formed with the fixing portion  32 . The press portions  31  each have a rectangular shape and are adapted to press the positioning protrusions  211  at the free end of the plate  21  of the oscillator  2 , as shown in  FIG. 7 . The fixing portion  32  has a reverse U shape or other shape, with two ends connected to the press portions  31 . The fixing portion  32  is retained in the first retaining trough  15  and the second retaining trough  16  to prevent it from moving. The first retaining trough  15  of the main body  11  and the second retaining trough  16  of the cover  12  each have a reverse U shape corresponding to the fixing portion  32 . The reverse U-shaped fixing portions  32  of the damping members  3  are respectively disposed in the reverse U-shaped troughs, which are assembled and positioned quickly to avoid sliding. 
     As shown in  FIG. 3 , the terminals of the present invention comprise two first terminals  4   a ,  4   b  for quickly connecting with an electric wire and electrically connecting with guiding members of the oscillator  2 . The first terminals  4   a ,  4   b  are disposed on first terminal installation portions  171  of the main body  11 , respectively. Each of the first terminals  4   a ,  4   b  is formed with a guiding elastic piece  41   a ,  41   b . The guiding elastic piece  41   a  of the first terminal  4   a  is in contact with the plate  21  of the oscillator  2 . The guiding elastic piece  41   b  of the first terminal  4   b  is in contact with a second terminal  5 . Through the second terminal  5 , the first terminals are connected with the piezoelectric members  22 . Specifically, as shown in  FIG. 8 ,  FIG. 9 ,  FIG. 10 , and  FIG. 11 , each of the first terminals  4   a ,  4   b  is bent to form a   -like shape having two first clamping pieces  42  and an open mouth  43 . Namely, the two first clamping pieces  42  are connected to each other at one end thereof and the open mouth  43  is formed between the two first clamping pieces  42  at an opposite end thereof. One side of one of the two first clamping pieces  42  is formed with the guiding elastic piece  41   a ,  41   b . One of the two first clamping pieces  42  of each of the first terminals  4   a ,  4   b  has a wire buckle  44  which obliquely protrudes toward the other of the two first clamping pieces  42 . The wire buckle  44  is adapted to buckle an electric wire  10  inserted through the open mouth  43 . Furthermore, the other of the two first clamping pieces  42  of each of the first terminals  4   a ,  4   b  is provided with a buckle board  45  at the open mouth  43 . The buckle board  45  has a through hole  46  for the electric wire  10  to be inserted between the two first clamping pieces  42 . The through hole  46  corresponds to a wire insertion hole  18  of the main body  11 , as shown in  FIG. 6 . After the external electric wire  10  is inserted into the through hole  46 , as shown in  FIG. 9  and  FIG. 11 , the electric wire  10  is clamped by the first clamping pieces  42  and the buckle board  45 , providing a quick electrical connection. 
     As shown in  FIG. 3 , the main body  11  of the present invention comprises a second terminal installation portion  172  for the second terminal  5  to be installed thereon. The second terminal  5  is in contact with the piezoelectric members  22  at two sides of the plate  21  of the oscillator  2 . The guiding electric piece  41   b  of the first terminal  4   b  is in contact with the second terminal  5 . Specifically, as shown in  FIG. 12  and  FIG. 13 , the second terminal  5  is bent to form a  -like shape having two second clamping pieces  51  and an open mouth  52 . Namely, the two second clamping pieces  51  are connected to each other at one end thereof and the open mouth  52  is formed between the two second clamping pieces  51  at an opposite end thereof. One of the two second clamping pieces  51  is in contact with one of the two piezoelectric members  22  of the oscillator  2 , and the other of the two second clamping pieces  51  is in contact with the other of the two piezoelectric members  22  of the oscillator  2 . One of the two second clamping pieces  51  is formed with a guiding piece  53 . The guiding elastic piece  41   b  of the first terminal  4   b  is in contact with the guiding piece  53  of the second terminal  5 . 
     As shown in  FIG. 14 , an outer surface of the main body  11  or the cover  12  of the loudspeaker box  1  is provided with a plurality of support blocks  19   a . When the loudspeaker box  1  is installed on a circuit board, the support blocks  19   a  are adapted to support the loudspeaker box  1 . As shown in  FIG. 15 , the periphery of the main body  11  or the cover  12  of the loudspeaker box  1  is provided with a support frame  19   b  to form a resonance cavity  191   b  encircled by the support frame  19   b . One side of the support frame  19   b  has a notch  192   b  in communication with the resonance cavity  191   b . When the loudspeaker box  1  is installed on a circuit board, the support frame  19   b  is adapted to support the loudspeaker box  1  so that the resonance cavity  191   b  is located between the loudspeaker and the circuit board to provide a better resonance effect. 
     Although particular embodiments of the present invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the present invention. Accordingly, the present invention is not to be limited except as by the appended claims.