Patent Publication Number: US-2021167275-A1

Title: Sound Vibration Sensor using Piezoelectric Element having Cantilever Structure

Description:
TECHNICAL FIELD 
     The present disclosure relates to a piezoelectric sound vibration sensor having a cantilever structure. 
     BACKGROUND 
     Conventional earsets having a structure with an external microphone has a disadvantage in that a speaker&#39;s voice cannot be clearly transmitted to a counterpart according to noise of a surrounding environment when making a call or performing simultaneous translation. Therefore, instead of the external microphone, an earset having a sound vibration microphone capable of detecting a user&#39;s voice vibration at a location in direct or indirect contact with the user&#39;s skin has been developed. 
       FIG. 1  is a diagram schematically showing an earset including a sound vibration microphone according to the related art. 
     The ear set  1  is worn on or inserted through the user&#39;s ear canal  2 , and the user&#39;s voice is transmitted to the earset  1  through a bone  3 . That is, when the user speaks, the bone vibrates, and a voice vibration recognition sensor senses the vibration of the bone, whereby the user&#39;s voice may be clearly transmitted to the counterpart in a noisy environment. 
     SUMMARY 
     Therefore, an aspect of the present disclosure provides a piezoelectric sound vibration sensor having a cantilever structure. 
     According to an aspect of the present disclosure, there is provided a sound vibration sensor using a piezoelectric element having a cantilever structure, including: a housing forming an exterior; a piezoelectric element having a cantilever structure installed in the housing; a support structure supporting a fixed end of the piezoelectric element; a weight attached to a free end of the piezoelectric element; and an energizing part transmitting an output from the piezoelectric element, wherein the sound vibration sensor comes into contact with a speaker&#39;s body, receives vibration of the body generated when the speaker utters a sound through the housing, and amplifies the vibration by the free end of the piezoelectric element to detect the voice vibration of the speaker using a piezoelectric characteristic of the piezoelectric element. 
     As another example of the present disclosure, the fixed portion of the piezoelectric element fixed by the support structure may be 40% or less of a total volume. 
     In addition, as another example of the present disclosure, a thickness of the piezoelectric element may be 0.3 mm or greater. 
     In addition, as another example of the present disclosure, a weight of the weight may be 5 mg or greater. 
     In addition, as another example of the present disclosure, the weight may be formed of metals having a density of 5 or greater. 
     In addition, as another example of the present disclosure, the support structure may be formed by a curved structure of the housing. 
     In addition, as another example of the present disclosure, two or more piezoelectric elements having different thicknesses may be provided. 
     In addition, as another example of the present disclosure, upper surfaces of the two or more piezoelectric elements may be coplanar. 
     In addition, as another example of the present disclosure, the sound vibration sensor may further include: a damping structure for preventing damage to the piezoelectric element. 
     In addition, as another example of the present disclosure, the damping structure is a polyurethane foam or a damping bond attached to the housing. 
     In addition, as another example of the present disclosure, the sound vibration sensor may further include: a reinforcing plate attached to a lower surface of the piezoelectric element to prevent damage to the piezoelectric element. 
     In addition, as another example of the present disclosure, the sound vibration sensor may further include: a spring installed between the free end of the piezoelectric element and the housing. 
     In addition, as another example of the present disclosure, the sound vibration sensor may further include: an amplifier installed on the energizing part and amplifying a signal from the piezoelectric element. 
     Since the piezoelectric sound vibration sensor having the cantilever structure provided by the present disclosure detects vibration generated by a speaker&#39;s voice using the piezoelectric element, external noise may be fundamentally blocked. 
     In addition, the piezoelectric sound vibration sensor having a cantilever structure provided by the present disclosure has excellent vibration detection capability because the piezo element has the cantilever structure. 
     Those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram schematically showing an earset including a sound vibration microphone according to the related art. 
         FIG. 2  is an exploded view of a sound vibration sensor using a piezoelectric element having a cantilever structure according to a first embodiment of the present disclosure. 
         FIG. 3  is a cross-sectional view of a sound vibration sensor using a piezoelectric element having a cantilever structure according to the first embodiment of the present disclosure. 
         FIG. 4  is a cross-sectional view of a sound vibration sensor using a piezoelectric element having a cantilever structure according to a second embodiment of the present disclosure. 
         FIG. 5  is a perspective view showing components other than a housing of a sound vibration sensor using a piezoelectric element having a cantilever structure according to a third embodiment of the present disclosure. 
         FIG. 6  is a cross-sectional view of a sound vibration sensor using a piezoelectric element having a cantilever structure according to a fourth embodiment of the present disclosure. 
         FIG. 7  is a cross-sectional view of a sound vibration sensor using a piezoelectric element having a cantilever structure according to a fifth embodiment of the present disclosure. 
         FIG. 8  is a cross-sectional view of a sound vibration sensor using a piezoelectric element having a cantilever structure according to a sixth embodiment of the present disclosure. 
         FIG. 9  is a cross-sectional view of a sound vibration sensor using a piezoelectric element having a cantilever structure according to a seventh embodiment of the present disclosure. 
         FIG. 10  is a cross-sectional view of a sound vibration sensor using a piezoelectric element having a cantilever structure according to an eighth embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, the present disclosure will be described in detail with reference to the accompanying drawings. 
       FIG. 2  is an exploded view of a sound vibration sensor using a piezoelectric element having a cantilever structure according to a first embodiment of the present disclosure, and  FIG. 3  is a cross-sectional view of a sound vibration sensor using a piezoelectric element having a cantilever structure according to the first embodiment of the present disclosure. 
     In the sound vibration sensor using a piezoelectric element having a cantilever structure (hereinafter, referred to as a “sound vibration sensor”) according to the first embodiment of the present disclosure, a housing including a lower housing  110  and an upper housing  120  forms an exterior and components for sensing vibrations are installed in the housing. 
     The lower housing  110  has a lower surface and side walls, having a box shape with an opened upper surface, and the upper housing  120  is coupled to the lower housing  110  to close the opened upper surface. A piezoelectric element  220  in the form of a strip having a length greater than a thickness or a width is installed in the lower housing  110 . Here, one end of the piezoelectric element  220  is fixed and the other end thereof is a free end, having a cantilever structure. The piezoelectric element  220  is preferably formed of a PZT ceramic material. 
     A support structure  210  supporting the fixed end of the piezoelectric element  220  is provided in the lower housing  110 . It is preferable that the fixed portion of the piezoelectric element  220  fixed by the support structure  210  is 40% or less of a total volume. This is because if the volume of the fixed portion of the piezoelectric element  220  increases, a vibration width of the free end is reduced to limit a detection range of sound vibration. 
     Meanwhile, a weight  230  is attached to the free end of the piezoelectric element  220 . The weight  230  has the advantage of amplifying vibration of the piezoelectric element  220 , thereby increasing the detection range of sound vibration of the sound vibration sensor. Here, the weight  230  is preferably 5 mg or greater in weight. If the weight is smaller, the vibration amplification effect of the weight  230  decreases, and thus the weight is preferably 5 mg or greater in weight in order to increase detection efficiency of the piezoelectric element  220  and minimize noise. Meanwhile, it is preferable that the weight  230  is formed of metals having a density of 5 or greater that may reduce the volume and increase the weight. Here, the weight  230  may have any shape as long as the weight  230  is attached to the piezoelectric element  220 , without limiting vibration of the piezoelectric element  220 . For example, the weight  230  may have any shape such as a cylinder shape, a cap shape surrounding the free end of the piezoelectric element  220 , a rectangular parallelepiped or a regular cube. The weight  230  may be attached to the piezoelectric element  220  by an adhesive member such as a bond or tape. 
     Meanwhile, an energizing part (or a conductive part)  300  capable of transmitting an output of the piezoelectric element  220  is connected to the fixed end side of the piezoelectric element  220 . One end  302  of the energizing part  300  is connected to the piezoelectric element  220  within the housings  110  and  120  and the other end  304  of the energizing part  300  is drawn out of the housings  110  and  120  to form a contact point with the outside. 
     The sound vibration sensor detects vibration generated by a speaker&#39;s voice transmitted through the housings  110  and  120  using piezoelectric characteristics of the piezoelectric element  220 . The piezoelectric element  220  is installed in a cantilever structure and vibrations of the housings  110  and  120  are amplified at the free end, and thus the piezoelectric element  220  may sensitively detect sound vibration. In addition, since it is attached to the speaker&#39;s body and detects vibration generated when a voice is spoken, external noise cannot be detected by a sensor. Therefore, if the sound vibration sensor is used as a microphone, external noise may be fundamentally blocked. 
       FIG. 4  is a cross-sectional view of a sound vibration sensor using a piezoelectric element having a cantilever structure according to a second embodiment of the present disclosure. 
     The sound vibration sensor according to the second embodiment of the present disclosure also includes the housing, the piezoelectric element  220 , a weight  230 , and the energizing part  300 . However, the support structure for supporting a fixed end of the piezoelectric element  220  is not separately attached to the lower housing  110   a . Instead, a portion of the lower housing  110   a  is bent inward to form a support structure  112   a  capable of supporting the piezoelectric element  220 . 
       FIG. 5  is a perspective view showing components excluding a housing of a sound vibration sensor using a piezoelectric element having a cantilever structure according to a third embodiment of the present disclosure. 
     A sound vibration sensor according to the third embodiment of the present disclosure is different from the previous embodiments in that it includes two piezoelectric elements  222   a  and  224   a . In the third embodiment of the present disclosure, two piezoelectric elements  222   a  and  224   a  are provided, but three or more may also be provided. When a plurality of piezoelectric elements  222   a  and  224   a  are provided, there is an advantage in that a detection range for detecting voice vibration is increased. In this case, the piezoelectric elements  222   a  and  224   a  may have different thicknesses, thereby increasing accuracy of voice vibration detection. By varying the thickness of the piezoelectric elements  222   a  and  224   a , not only amplitudes of free ends of the piezoelectric elements  222   a  and  224   a  are changed but also the piezoelectric characteristics are different, and thus accuracy of voice sensing may be increased by combining signals generated at the piezoelectric elements  222   a  and  224   a.    
     Here, when the thicknesses of the piezoelectric elements  222   a  and  224   a  are different from each other, upper surfaces of the piezoelectric elements  222   a  and  224   a  may have the same height, i.e., may be coplanar, by varying heights of portions supporting the piezoelectric elements  222   a  and  224   a  in the support structure  300   a . The energizing part  300  may be easily attached by arranging the upper surfaces of the piezoelectric elements  222   a  and  224   a  to be coplanar. 
       FIG. 6  is a cross-sectional view of a sound vibration sensor using a piezoelectric element having a cantilever structure according to a fourth embodiment of the present disclosure.  FIG. 7  is a cross-sectional view of a sound vibration sensor using a piezoelectric element having a cantilever structure according to a fifth embodiment of the present disclosure. The sound vibration sensor according to the fourth embodiment of the present disclosure and the sound vibration sensor according to the fifth embodiment of the present disclosure have a damping structure for preventing damage to the piezoelectric element  220 . In the fourth embodiment of the present disclosure, a damping bond  400  is applied on the lower housing  110  at a position close to the weight  230 . In the fifth embodiment of the present disclosure, polyurethane foams (such as PORON®)  402  and  404  are attached to the lower housing  110  and the upper housing  120 . The polyurethane foams  402  and  404  are appropriately disposed in empty spaces in the housings  110  and  120  and prevent impact from being applied to the piezoelectric element  220  due to a fall or the like. 
       FIG. 8  is a cross-sectional view of a sound vibration sensor using a piezoelectric element having a cantilever structure according to a sixth embodiment of the present disclosure. The sound vibration sensor according to the sixth embodiment of the present disclosure includes a reinforcing plate  500  attached to the piezoelectric element  220  in order to prevent damage to the piezoelectric element  220 . The reinforcing plate  500  does not serve to damp but may prevent the piezoelectric element  220  from being damaged. 
       FIG. 9  is a cross-sectional view of a sound vibration sensor using a piezoelectric element having a cantilever structure according to a seventh embodiment of the present disclosure. The sound vibration sensor according to the seventh embodiment of the present disclosure includes the reinforcing plate  500  attached to the piezoelectric element  220  to prevent damage to the piezoelectric element  220  as in the sixth embodiment. In addition, an elastic member  600  is provided between the free end of the piezoelectric element  220  and the housing. The elastic member  600  serves to damp vibration of the free end. In the seventh embodiment of the present disclosure, the elastic member  600  is installed between the weight  230  attached to a lower portion of the free end of the piezoelectric element  220  and the lower housing  110 . However, the installation position of the weight  230  and the elastic member  600  may be changed as necessary. 
       FIG. 10  is a cross-sectional view of a sound vibration sensor using a piezoelectric element having a cantilever structure according to an eighth embodiment of the present disclosure. Similar to the previous embodiments, the sound vibration sensor according to the eighth embodiment of the present disclosure includes the housings  110  and  120 , the support structure  210 , the piezoelectric element  220 , the weight  230 , and the energizing part  300 . Here, an amplifier  310  for amplifying a signal of the piezoelectric element  220  may be provided on the energizing part  300 . 
     As described above, the present invention is not limited to the above-described examples and various modifications may be made by a person skilled in the art to which the present invention pertains, without departing from the spirit of the invention as defined by the claims of the present invention, and such modifications also fall within the claims.