Patent Publication Number: US-9833812-B2

Title: Vibration generating device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority and benefit of Korean Patent Application No. 10-2014-0121756 filed on Sep. 15, 2014, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     The present disclosure relates to a vibration generating device. 
     Vibration generating devices, converting electric energy into mechanical vibrations through the generation of electromagnetic force, have commonly been mounted in mobile phones, and the like, in order to silently notify users of call reception by transferring vibrations thereto. 
     Meanwhile, recently, vibration generating devices using piezoelectric elements have been used. Such a vibration generating device using a piezoelectric element, relying on the principle of an inverse piezoelectric effect in which displacement is generated when voltage is applied to the piezoelectric element, uses the principle of allowing a mass body of a vibrator to be moved by the displacement generated by the piezoelectric element to generate vibration force. 
     Here, the piezoelectric element generally has a rectangular parallelepiped shape in which a length thereof is greater than a width thereof. However, in this case, since the piezoelectric element should be relatively long in order to secure displacement and vibrations, an overall length of the vibration generating device is increased, and the piezoelectric element is vulnerable to external impacts, such as those occurring in a case the device is dropped by a user. 
     In addition, since the vibration generating device has an overall rectangular parallelepiped shape, a volume thereof may be increased, which may not accord with the need for the miniaturization of components. 
     RELATED ART DOCUMENT 
     (Patent Document 1) Korean Patent Laid-Open Publication No. 2006-0000894 
     SUMMARY 
     An aspect of the present disclosure may provide a vibration generating device having improved response characteristics. 
     According to an aspect of the present disclosure, a vibration generating device may include: a housing having an internal space; a base member installed in the housing to be disposed in a central portion of the housing; a first plate installed on the base member; a first piezoelectric element installed on an upper surface of the first plate; a second piezoelectric element disposed to face the first piezoelectric element through a connection member; a second plate installed on the second piezoelectric element; and a vibration amplifying part installed on an upper surface of the second plate. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The above and other aspects, features and advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a schematic perspective view showing a vibration generating device according to an exemplary embodiment of the present disclosure; 
         FIG. 2  is a schematic cross-sectional view showing the vibration generating device according to an exemplary embodiment of the present disclosure; 
         FIG. 3  is an exploded perspective view showing the vibration generating device according to an exemplary embodiment of the present disclosure; 
         FIGS. 4 and 5  are views for describing an operation of the vibration generating device according to an exemplary embodiment of the present disclosure; and 
         FIG. 6  is a schematic cross-sectional view showing a vibration generating device according to another exemplary embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. 
     The disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. 
     In the drawings, the shapes and dimensions of elements may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like elements. 
       FIG. 1  is a schematic perspective view showing a vibration generating device according to an exemplary embodiment of the present disclosure;  FIG. 2  is a schematic cross-sectional view showing the vibration generating device according to an exemplary embodiment of the present disclosure; and  FIG. 3  is an exploded perspective view showing the vibration generating device according to an exemplary embodiment of the present disclosure. 
     Referring to  FIGS. 1 through 3 , a vibration generating device  100  according to an exemplary embodiment of the present disclosure may include a housing  110 , a base member  120 , a first plate  130 , a first piezoelectric element  140 , a connection member  150 , a second piezoelectric element  160 , a second plate  170 , a vibration amplifying part  180 , and a circuit board  190  by way of example. 
     The housing  110  may have an internal space and form an appearance of the vibration generating device  100 . 
     Meanwhile, the housing  110  may include a case  112  having an internal space and having a lower end portion that is open and a bracket  114  coupled to the lower end portion of the case  112  to form a closed space, as shown in more detail in  FIG. 2 . 
     As an example, the case  112  may have a circular box shape of which a lower end portion is open, and the bracket  114  may have a plate shape coupled to the case  112 . 
     As described above, the base member  120 , the first plate  130 , the first piezoelectric element  140 , the connection member  150 , the second piezoelectric element  160 , the second plate  170 , the vibration amplifying part  180 , and the like, may be installed in the housing  110  having the internal space. 
     Although the case in which the housing  110  has a coin shape has been described by way of example in the present exemplary embodiment, a shape of the housing  110  is not limited thereto, but may be variously modified. 
     Here, terms with respect to directions will be defined. As viewed in  FIG. 1 , a radial direction refers to a horizontal direction, that is, a direction from an outer peripheral surface of the housing  110  to the center thereof or a direction from the center of the housing  110  toward the outer peripheral surface thereof, and a vertical direction refers to a direction from a bottom surface of the housing  110  toward a top surface thereof or a direction from the top surface of the housing  110  toward the bottom surface thereof. 
     In addition, a circumferential direction refers to a rotation direction along the outer peripheral direction of the housing  110 . 
     The base member  120  may be installed in the housing  110  to be disposed in a central portion of the housing  110 . As an example, the base member  120  may be fixedly installed on a central portion of the bracket  114 . 
     Meanwhile, the base member  120  may have a coin shape and serve to allow the first plate  130  to be spaced apart from the bracket  114 . That is, the first plate  130  may be installed on an upper surface of the base member  120  to thereby be disposed to be spaced apart from the bracket  114 . 
     The first plate  130  may be fixedly installed on the upper surface of the base member  120 , as described above, and have a disk shape. Meanwhile, the first plate  130  may be made of a metal. However, the first plate is not limited to being formed of the metal, but may be formed of any material as long as it may be restored to its original state after being deformed. 
     In addition, the first plate  130  may have a diameter larger than that of the first piezoelectric element  140 . 
     In addition, the first piezoelectric element  140  may be installed on an upper surface of the first plate  130  and be deformed in the case in which power is applied thereto. In addition, the first piezoelectric element  140  may have a circular coin shape, and the first plate  130  may be deformed together with the first piezoelectric element  140  by deformation of the first piezoelectric element  140 . 
     That is, since the first plate  130  has a central portion fixedly installed on the base member  120 , when the first piezoelectric element  140  is deformed, an edge of the first plate  130  may be vertically deformed in a state in which the central portion of the first plate  130  is fixed. 
     In other words, the first plate  130  may be deformed to have a convex shape or a concave shape in a state in which the central portion thereof is fixed. 
     The connection member  150  may serve to connect the first and second piezoelectric elements  140  and  160  to each other so that the first and second piezoelectric elements  140  and  160  are disposed to face each other. 
     In addition, the connection member  150  may include a plurality of connection members  150  which are disposed to be spaced apart from each other in the circumferential direction at edges of the first and second piezoelectric elements  140  and  160 . 
     Meanwhile, the connection members  150  may be formed of a material having restoring force by elastic deformation and having elasticity to allow the first and second piezoelectric elements  140  and  160  to be freely deformed at the time of deformation of the first and second piezoelectric elements  140  and  160  while suppressing a decrease in a deformation amount by the deformation of the first and second piezoelectric elements  140  and  160 . 
     The second piezoelectric element  160  may have a circular coin shape and be deformed in an opposite direction to a direction in which the first piezoelectric is deformed when the first piezoelectric element is deformed. That is, in the case in which an edge of the first piezoelectric element  140  moves upwardly, such that the first piezoelectric element  140  is deformed to have a concave shape, the second piezoelectric element  160  may be deformed to have a convex shape. In addition, in the case in which the first piezoelectric element  140  is deformed to have a convex shape, the second piezoelectric element  160  may be deformed to have a concave shape. 
     Meanwhile, an edge of the second piezoelectric element  160  may be connected to the first piezoelectric element  140  by the connection members  150 . Therefore, the edge of the second piezoelectric element  160  may be restricted to the first piezoelectric element  140 , and a central portion thereof may be moved and deformed. 
     The second plate  170  may be installed on the second piezoelectric element  160  and have a disk shape. In addition, the second plate  170  may also be deformed together with the second piezoelectric element  160 . In addition, the second plate  170  may also be made of a metal. In addition, the second plate  170  may have a diameter larger than that of the second piezoelectric element  160 . 
     The vibration amplifying part  180  may be fixedly installed on an upper surface of the second plate  170  and serve to amplify vibrations generated by the deformation of the first and second piezoelectric elements  140  and  160 . 
     Meanwhile, the vibration amplifying part  180  may include an elastic member  200 , a yoke  210 , and a mass body  220 . 
     The elastic member  200  may have a central portion fixedly installed on the upper surface of the second plate  170  and an edge fixed to the yoke  210 . To this end, the elastic member  200  may include a bonded installation portion  202  fixedly installed on the upper surface of the second plate  170 , a ring portion  204  disposed outside of the bonded installation portion  202  and having a ring shape, and an elastic deformation portion  206  connecting the bonded installation portion  202  and the ring portion  204  to each other. 
     Meanwhile, the elastic deformation portion  206  may have a spiral shape, and the elastic deformation portion  206  may be provided in plural. 
     That is, in the case in which the first and second plates  130  and  170  are deformed by the deformation of the first and second piezoelectric elements  140  and  160 , the bonded installation portion  202  of the elastic member  200  may move together with the second plate  170 . 
     Therefore, the elastic deformation portions  206  of the elastic member  200  may be deformed to vertically move the mass body  220  installed on the ring portion  204 . 
     The yoke  210  may have a lower surface fixedly installed on the ring portion  204  and have the mass body  220  seated on an upper surface thereof. To this end, the yoke  210  may have a ring shape. However, although the case in which the elastic member  200  and the mass body  220  are connected to each other through the yoke  210  has been described by way of example in the present exemplary embodiment, the present disclosure is not limited thereto. That is, the elastic member  200  may be directly installed on the mass body  220 . 
     The mass body  220  may serve to amplify the vibrations generated by the deformation of the first and second piezoelectric elements  140  and  160 . Meanwhile, the mass body  220  may also have a coin shape and be formed of a material having a high specific gravity in order to amplify the vibrations. For example, the mass body  220  may be formed of a material such as tungsten, iron, or the like. 
     In other words, in order to increase a vibration amount by adjusting a resonance frequency through an increase in a mass in the same volume, the weight  220  may be formed of the material having the high specific gravity. 
     In addition, a damper member  230  may be installed on the upper surface of the second plate  170  in order to prevent contact between the second plate  170  and the mass body  220 . Meanwhile, the damper member  230  may have a ring shape and be formed of a material having elasticity in order to prevent noise and damage due to the contact between the mass body  220  and the second plate  170 . 
     Meanwhile, in the case in which power is applied to the first and second piezoelectric elements  140  and  160 , a frequency of a current applied to the first and second piezoelectric elements  140  and  160  may coincide with a resonant frequency of the vibration amplifying part  180 . Therefore, in the case in which the power is applied to the first and second piezoelectric elements  140  and  160 , the vibration amplifying part  180  may vibrate to amplify the vibrations by the deformation of the first and second piezoelectric elements  140  and  160 . 
     The circuit board  190  may be connected to the first piezoelectric element  140  and have one end exposed from the housing  110 . The circuit board  190  may be seated on the bracket  114 , and have power connection electrodes  192   a  formed on a power connection part  192  thereof exposed from the housing  110 . 
     Meanwhile, the circuit board  190  may be electrically connected to the second piezoelectric element  160 . 
     As described above, since the first and second plates  130  and  170  are deformed by the deformation of the first and second piezoelectric elements  140  and  160 , force transferred to the elastic member  200  may be amplified. Therefore, an operation speed may be improved as compared with a vibration generating device having the same diameter, such that rapid response characteristics may be secured. 
     In addition, the first and second piezoelectric elements  140  and  160  may be disposed to face each other without increasing a diameter of the piezoelectric element, such that a vibration amount may be increased without increasing a size of the vibration generating device  100 . 
     Meanwhile, the first and second piezoelectric elements  140  and  160  may have the circular coin shape and the elastic member  200  may be provided, such that the size of the vibration generating device  100  may be further decreased. 
     Hereinafter, an operation of the vibration generating device according to an exemplary embodiment of the present disclosure will be described with reference to the accompanying drawings. 
       FIGS. 4 and 5  are views for describing an operation of the vibration generating device according to an exemplary embodiment of the present disclosure. 
     That is,  FIG. 4  shows a state in which the vibration amplifying part of the vibration generating device according to an exemplary embodiment of the present disclosure moves upwardly, and  FIG. 5  shows a state in which the vibration amplifying part of the vibration generating device according to an exemplary embodiment of the present disclosure moves downwardly. 
     First, referring to  FIG. 4 , when power is applied to the first piezoelectric element  140  through the circuit board  190  (See  FIG. 3 ), the first piezoelectric element  140  may be deformed. Here, the first plate  130  having the central portion fixedly installed on the base member  120  may be deformed together with the first piezoelectric element  140 . 
     That is, the edge of the first plate  130  may move upwardly in a state in which the central portion of the first plate  130  is fixed to the base member  120  by the deformation of the first piezoelectric element  140 . 
     In other words, the first piezoelectric element  140  and the first plate  130  may be deformed to have a concave shape. 
     Here, the second piezoelectric element  160  may be deformed in an opposite direction to a direction in which the first piezoelectric element  140  is deformed. That is, in the case in which the first piezoelectric element  140  is deformed to have a concave shape, the second piezoelectric element  160  may be deformed to have a convex shape. 
     Meanwhile, the second piezoelectric element  160  may be disposed to face the first piezoelectric element  140  through the connection members  150  and be disposed to be spaced apart from the first piezoelectric element  140 . Further, the second piezoelectric element  160  may be connected to the first piezoelectric element  140  by the connection members  150 . In addition, the connection members  150  may be disposed to connect the edges of the first and second piezoelectric elements  140  and  160  to each other. 
     Therefore, when the second piezoelectric element  160  is deformed, the central portion of the second piezoelectric element  160  may be formed in a state in which the edge of the second piezoelectric element  160  is fixed to the connection members  150 , such that the second piezoelectric element  160  may have a convex shape. Therefore, the second plate  170  may also be deformed to have a convex shape by the deformation of the second piezoelectric element  160 . 
     As described above, the elastic deformation portion  206  of the elastic member  200  may be deformed by the deformation of the first and second piezoelectric elements  140  and  160 . 
     Meanwhile, referring to  FIG. 5 , when power is applied to the first piezoelectric element  140  through the circuit board  190  (See  FIG. 3 ), the first piezoelectric element  140  may be deformed. Here, the first plate  130  having the central portion fixedly installed on the base member  120  may be deformed together with the first piezoelectric element  140 . 
     That is, the edge of the first plate  130  may move upwardly in a state in which the central portion of the first plate  130  is fixed to the base member  120  by the deformation of the first piezoelectric element  140 . 
     In other words, the first piezoelectric element  140  and the first plate  130  may be deformed to have a convex shape. 
     Here, the second piezoelectric element  160  may be deformed in an opposite direction to a direction in which the first piezoelectric element  140  is deformed. That is, in the case in which the first piezoelectric element  140  is deformed to have a convex shape, the second piezoelectric element  160  may be deformed to have a concave shape. 
     Meanwhile, the second piezoelectric element  160  may be disposed to face the first piezoelectric element  140  through the connection members  150  and be disposed to be spaced apart from the first piezoelectric element  140 . Further, the second piezoelectric element  160  may be connected to the first piezoelectric element  140  by the connection members  150 . In addition, the connection members  150  may be disposed to connect the edges of the first and second piezoelectric elements  140  and  160  to each other. 
     Therefore, when the second piezoelectric element  160  is deformed, the central portion of the second piezoelectric element  160  may be formed in a state in which the edge of the second piezoelectric element  160  is fixed to the connection members  150 , such that the second piezoelectric element  160  may have a concave shape. Therefore, the second plate  170  may also be deformed to have a concave shape by the deformation of the second piezoelectric element  160 . 
     As described above, the elastic deformation portion  206  of the elastic member  200  may be deformed by the deformation of the first and second piezoelectric elements  140  and  160 . 
     As described above, since the first and second plates  130  and  170  are deformed by the deformation of the first and second piezoelectric elements  140  and  160 , force transferred to the elastic member  200  may be amplified. Therefore, an operation speed may be improved as compared with a vibration generating device having the same diameter, such that rapid response characteristics may be secured. 
     Hereinafter, a vibration generating device according to another exemplary embodiment of the present disclosure will be described with reference to  FIG. 6 . However, the same components as the above-mentioned components will be denoted by the same reference numerals and a detailed description therefor will be omitted. 
       FIG. 6  is a schematic cross-sectional view showing a vibration generating device according to another exemplary embodiment of the present disclosure. 
     Referring to  FIG. 6 , a vibration generating device  300  according to another exemplary embodiment of the present disclosure may further include first and second contact prevention members  440  and  450 . 
     The first contact prevention member  440  may be installed on at least one of an upper surface of the mass body  220  and a ceiling surface of the housing  110 , serve to prevent generation of noise due to contact between the housing  110  and the mass body  220 , and prevent damage to the housing  110  in the case in which the housing  110  and the mass body  220  contact each other due to external impact. 
     Meanwhile, the second contact prevention member  450  may be installed on at least one of an outer peripheral surface of the mass body  220  and an inner peripheral surface of the housing  110  and prevent contact between the housing  110  and the mass body  220  generated at the time of tilting of the mass body  220  to prevent generation of noise. Further, the second contact prevention member  450  may also prevent damage to the housing  110  in the case in which the housing  110  and the mass body  220  contact each other due to external impact. 
     As set forth above, according to exemplary embodiments of the present disclosure, response characteristics may be improved. 
     While exemplary embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and variations could be made without departing from the scope of the present invention as defined by the appended claims.