Patent Publication Number: US-2021188089-A1

Title: Instrument cluster

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from and the benefit of Korean Patent Application No. 10-2019-0172515, filed on Dec. 20, 2019, and Korean Patent Application No. 10-2019-0172517, filed on Dec. 20, 2019, which are hereby incorporated by reference for all purposes as if fully set forth herein. 
     BACKGROUND 
     Field 
     Exemplary embodiments of the invention relate generally to a vehicle instrument cluster and, more specifically, to an instrument cluster allowing a drive to receive a danger alert or danger information of a vehicle through a sound and an image. 
     Discussion of the Background 
     Recently, the automobile market is rapidly growing with a trend of favoring intelligent vehicles having advanced information technology (IT) and convenient functions in addition to improving the original functions of vehicles. 
     In this trend, electronization of vehicles is proliferating, and functions in which IT and wireless communication technology are combined are rapidly increasing. Particularly, products for supporting the stability and convenience of drivers are being released, and one of the products is an instrument cluster which is an instrument panel. 
     An instrument cluster displays a vehicle speed, revolutions per minute (RPM), a temperature of cooling water, an amount of fuel, and the like to allow the driver to visually recognize information thereof. 
     Generally, the instrument cluster provides the information with a real image in front of the driver. 
     In this case, in the conventional instrument cluster, a direction of visual display information is different from an oriented direction of a speaker sound. 
     That is, in the conventional instrument cluster, since a speaker is installed on a rear surface of the vehicle to be separated from a conventional sound system, directions of an image and a sound (warning sound and the like) that the driver sees and hears are different. 
     Accordingly, since sound image localization is not implemented, there is a high possibility that the driver feels it is difficult to recognize a certain situation due to confusion caused by a directional difference between visual information and the speaker sound. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and, therefore, it may contain information that does not constitute prior art. 
     SUMMARY 
     Exemplary embodiments of the present invention provide a vehicle instrument cluster having a vibration speaker structure in which a sound image is displayed in a center of a screen through an inner glass serving as a speaker diaphragm and a sound field is formed in the entire screen to help a driver with improved situation recognition. 
     Additional features of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. 
     An exemplary embodiment of the invention provides a vehicle instrument cluster having a vibration speaker structure-, the vehicle instrument cluster including a frame accommodating a component configured to display vehicle operation information therein and having an open front surface, a cover glass including an outer glass having a hollow shape surrounding an outer edge of the front surface of the frame and an inner glass surrounding a center of the front surface of the frame and positioned to be spaced apart from the outer glass, an exciter disposed on a rear surface of the inner glass and configured to vibrate the inner glass, and a suspension disposed between and connected to the outer glass and the inner glass spaced apart from each other. 
     The suspension may have a corrugated shape to be disposed between and connected to an inner circumferential surface of the outer glass and an outer circumferential surface of the inner glass. 
     The suspension may be disposed between and detachably connected to an inner circumferential surface of the outer glass and an outer circumferential surface of the inner glass. 
     The suspension may maintain a front-rear movement of the inner glass vibrated by the exciter and block vibration energy of the inner glass from being transferred to the outer glass. 
     The exciter may be disposed on each of both ends of the rear surface of the inner glass. 
     The exciter may be coupled to the inner glass through a snap-fit coupling method. 
     The exciter may include a housing accommodating a voice coil and a magnet therein, a plurality of brackets formed on an outer circumferential surface of the housing, and coupling hooks formed to be bent and extend in a forward direction of the brackets and press-fitted to the rear surface of the inner glass. 
     A plurality of coupling protrusions formed to protrude and be engaged with and press-fitted to the coupling hooks may be formed on the rear surface of the inner glass. 
     The coupling protrusion may include a seating surface in contact with the bracket, and a coupling rod protruding from the seating surface in a rearward direction. 
     The plurality of brackets may be formed at equidistant intervals along the outer circumferential surface of the housing, and a coupling hole through which the coupling rod passes through may be formed in at least one of the brackets. 
     Another exemplary embodiment of the invention provides a vehicle instrument cluster having a vibration speaker structure, the vehicle instrument cluster including a frame having an accommodation space therein and an open front surface, a cover glass including an outer glass having a hollow shape surrounding an outer edge of the front surface of the frame and an inner glass surrounding a center of the front surface of the frame and positioned to be spaced apart from the outer glass, an exciter disposed on a rear surface of the inner glass and configured to vibrate the inner glass in a front-rear direction, and a holder disposed in the frame and supporting the exciter. 
     The inner glass may not come into contact with the outer glass when the inner glass is vibrated by the exciter. 
     There may be a step difference between the inner glass and the outer glass in the front-rear direction. 
     The outer glass may be formed in a shape in which an end portion of an inner circumferential surface thereof is bent in a rearward direction. 
     The exciter may be disposed on each of at least three points on the rear surface of the inner glass. 
     Another exemplary embodiment of the invention provides a vehicle instrument cluster having a vibration speaker structure, the vehicle instrument cluster including a frame having an accommodation space therein and an open front surface, a cover glass including an outer glass having a hollow shape surrounding an outer edge of the front surface of the frame and an inner glass surrounding a center of the front surface of the frame and positioned to be spaced apart from the outer glass, and an exciter disposed on a rear surface of the inner glass and configured to vibrate the inner glass in a front-rear direction. 
     In this case, the vehicle instrument cluster having a vibration speaker structure may further include a holder disposed at a center of an inner portion of the frame and supporting the inner glass. 
     The inner glass may be formed to have a structure detachable from the holder. 
     The holder may surround a display included in a central portion of the frame, and a portion, which is in contact with the inner glass, of the holder may be formed in a curved surface shape. 
     The exciter may be provided as a plurality of exciters disposed on both ends of the rear surface of the inner glass. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention. 
         FIG. 1  is a perspective view illustrating a vehicle instrument cluster according to a first embodiment of the present invention. 
         FIG. 2  is a cross-sectional view taken along line A-A′ illustrated in  FIG. 1 . 
         FIG. 3  is a view illustrating a coupling relationship between an exciter and an inner glass of the vehicle instrument cluster according to the embodiment of the present invention. 
         FIG. 4  is a perspective view illustrating a vehicle instrument cluster according to a second embodiment of the present invention. 
         FIG. 5  is a cross-sectional view taken along line B-B′ illustrated in  FIG. 4 . 
         FIG. 6  is a perspective view illustrating a vehicle instrument cluster according to a third embodiment of the present invention. 
         FIG. 7  is a cross-sectional view taken along line C-C′ illustrated in  FIG. 6 . 
         FIG. 8  is a cross-sectional view taken along line D-D′ illustrated in  FIG. 6 . 
         FIG. 9  is a cross-sectional view taken along line E-E′ illustrated in  FIG. 6 ; 
         FIG. 10  is a perspective view illustrating a vehicle instrument cluster according to a fourth embodiment of the present invention. 
         FIG. 11  is a cross-sectional view taken along line F-F′ illustrated in  FIG. 10 ; 
         FIG. 12  is a schematic perspective view illustrating an elastic member in the vehicle instrument cluster according to the fourth embodiment of the present invention. 
         FIG. 13  is a view illustrating modified examples of the elastic member and a cover glass in the vehicle instrument cluster according to the fourth embodiment of the present invention. 
         FIG. 14  is a cross-sectional view taken along line G-G′ illustrated in  FIG. 10 . 
         FIG. 15  is a view illustrating a coupling relationship between an exciter and the cover glass in the vehicle instrument cluster according to the embodiment of the present invention. 
         FIG. 16  is a graph showing a cut-off characteristic of the elastic member, which removes a disturbance of a frequency greater than or equal to a specific frequency, in the vehicle instrument cluster according to the fourth embodiment of the present invention. 
         FIG. 17  is a perspective view illustrating a vehicle instrument cluster according to a fifth embodiment of the present invention. 
         FIG. 18  is an exploded perspective view illustrating the vehicle instrument cluster according to the fifth embodiment of the present invention. 
         FIG. 19  is a cross-sectional view taken along line H-H′ illustrated in  FIG. 17 ; 
         FIG. 20  is a schematic perspective view illustrating a magnet bearing in the vehicle instrument cluster according to the fifth embodiment of the present invention; 
         FIG. 21  and  FIG. 22  are graphs showing result values according to a change in position of an inner magnet in the magnet bearing of  FIG. 20 . 
         FIG. 23  is a cross-sectional view taken along line I-I′ illustrated in  FIG. 17 . 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
     The invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure is thorough, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals in the drawings denote like elements. 
     Unless defined otherwise, it is to be understood that all the terms (including technical and scientific terms) used in the specification has the same meaning as those that are understood by those who skilled in the art. Further, the terms defined by the dictionary generally used should not be ideally or excessively formally defined unless clearly defined specifically. It will be understood that for purposes of this disclosure, “at least one of X, Y, and Z” can be construed as X only, Y only, Z only, or any combination of two or more items X, Y, and Z (e.g., XYZ, XYY, YZ, ZZ). Unless particularly described to the contrary, the term “comprise”, “configure”, “have”, or the like, which are described herein, will be understood to imply the inclusion of the stated components, and therefore should be construed as including other components, and not the exclusion of any other elements. 
     The scope of the present invention is defined by the appended claims. Meanwhile, the terms used herein are provided only to describe the embodiments of the present invention and not for purposes of limitation. In the present specification, unless the context clearly indicates otherwise, the singular forms include the plural forms. It will be understood that the term “comprise” or “comprising,” when used herein, specifies some stated components, steps, operations and/or elements but do not preclude the presence or addition of one or more other components, steps, operations and/or elements. 
     A vehicle instrument cluster having a vibration speaker structure of the present invention allows directions of image information and a sound relating to vehicle operation to be the same so that an optimum environment in which a driver can recognize a situation is provided. 
     As a method thereof, in the present invention, exciters are basically mounted on a cover glass, and the cover glass is used as a speaker diaphragm. 
     In this case, in order to use the cover glass as the speaker diaphragm, an installation structure is required in which vibration of the cover glass is preserved rather than the cover glass being fixed to a connecting portion. 
     That is, when the exciter is mounted on the cover glass in a state in which the connecting portion is fixed to the cover glass, vibration of the cover glass configured to vibrate due to the exciter is attenuated by the connecting portion. 
     Accordingly, due to lack of air vibration causing sound generation, there is a problem in the performance of the speaker as a result of the lack. To this end, the vehicle instrument cluster of the present invention proposes a structure in which a divided cover glass is used as a speaker diaphragm through first to third embodiments which will be described below. 
     In addition, since the present invention will be described from a structural viewpoint in which the cover glass may function as a speaker diaphragm, a description about a functional mechanism of a speaker will be omitted or only some of the description will be described. 
     First Embodiment (Suspension Structure Connecting Divided Cover Glass) 
       FIG. 1  is a perspective view illustrating a vehicle instrument cluster according to a first embodiment of the present invention, and  FIG. 2  is a cross-sectional view taken along line A-A′ illustrated in  FIG. 1 . 
     Referring to  FIGS. 1 and 2 , a vehicle instrument cluster  100  includes a frame  110 , a cover glass  120 , exciters  130 , and a suspension  140 . 
     The frame  110  is a frame that accommodates components configured to display vehicle operation information therein and has an open front surface. In this case, the vehicle operation information may refer to information in which a vehicle speed, revolutions per minute (RPM), a temperature of cooling water, an amount of fuel, and the like are displayed. 
     The cover glass  120  includes an outer glass  121  and an inner glass  122 . Basically, the cover glass  120  has a form surrounding the front surface of the frame  110  and performs a speaker diaphragm function. 
     The outer glass  121  surrounds an outer edge of the front surface of the frame  110  and is formed in a hollow shape. In this case, the outer glass  121  is detachably connected to the outer edge of the front surface of the frame  110 . 
     The inner glass  122  surrounds a center of the front surface of the frame  110 . The inner glass  122  is positioned to be spaced apart from the outer glass  121 . That is, the inner glass  122  and the outer glass  121  are separated from each other. 
     The exciter  130  is an apparatus configured to supply an excitation current and is also referred to as an exciter. The exciter  130  vibrates the inner glass  122  using a signal current flowing in a voice coil. 
     To this end, the exciter  130  is disposed on a rear surface of the inner glass  122  and vibrates the inner glass  122  in a front-rear direction. 
     In this case, the exciters  130  are disposed both ends of the rear surface of the inner glass  122  so that the inner glass  122  has a stereo effect as a speaker diaphragm. 
     The suspension  140  is disposed between and connected to the outer glass  121  and the inner glass  122  spaced apart from each other. 
     That is, the suspension  140  has a corrugated shape to be disposed between and connected to an inner circumferential surface of the outer glass  121  and an outer circumferential surface of the inner glass  122 . 
     In this case, the suspension  140  maintains a front-rear movement of the inner glass  122  vibrated by the exciter  130  and blocks vibration energy of the inner glass  122  from being transferred to the outer glass  121 . 
     The suspension  140  may be disposed between and detachably connected to the inner circumferential surface of the outer glass  121  and the outer circumferential surface of the inner glass  122 . 
       FIG. 3  is a view illustrating a coupling relationship between the exciter and the inner glass of the vehicle instrument cluster according to the embodiment of the present invention. 
     Referring to  FIG. 3 , the exciter  130  is coupled to the inner glass  122  through a snap-fit coupling method. That is, the exciter  130  and the inner glass  122  are detachably press-fitted to each other. 
     The exciter  130  includes a housing  131 , brackets  132 , and coupling hooks  133 . 
     The housing  131  accommodates the voice coil and a magnet therein. 
     The plurality of brackets  132  are formed on an outer circumferential surface of the housing  131 . In this case, the plurality of brackets  132  are formed at equidistant intervals along the outer circumferential surface of the housing  131 . In addition, one or more coupling holes  132   a  are formed in the plurality of brackets  132 . 
     In this case, it is more appropriate that the plurality of coupling holes  132   a  are not formed in the bracket  132 , but the plurality of coupling holes  132   a  may or may not be formed in the bracket  132  according to a position of the bracket  132 . 
     The coupling hook  133  is formed to be bent and extend in a forward direction of the bracket  132 . The coupling hook  133  is press-fitted to the rear surface of the inner glass  122 . 
     In this case, a plurality of coupling protrusions  123  engaged with and press-fitted to the coupling hooks  133  are formed on the rear surface of the inner glass  122 . 
     The coupling protrusions  123  include seating surfaces  123   a  and coupling rods  123   b.    
     The seating surface  123   a  is in surface contact with the bracket  132 . 
     The coupling rod  123   b  is formed to protrude in a rearward direction from the seating surface  123   a . The coupling rod  123   b  passes through the coupling hole  132   a  of the exciter  130 . 
     Second Embodiment (Holder Structure Supporting Exciter Connected to Inner Glass) 
       FIG. 4  is a perspective view illustrating a vehicle instrument cluster according to a second embodiment of the present invention, and  FIG. 5  is a cross-sectional view taken along line B-B′ illustrated in  FIG. 4 ; 
     Referring to  FIGS. 4 and 5 , a vehicle instrument cluster  100  includes a frame  110 , a cover glass  120 , exciters  130 , and a holder  150 . 
     In this case, overlapping descriptions of the above components and the above-described components of the first embodiment will be omitted. 
     In the vehicle instrument cluster  100  according the second embodiment, an outer glass  121  and an inner glass  122  are separated not to be in contact with each other. 
     In other words, this means that the inner glass  122  on which the exciters  130  are mounted does not come into contact with the outer glass  121  when the inner glass  122  is vibrated by the exciters  130 . 
     In this case, there is a step difference between the inner glass  122  and the outer glass  121  by a separation distance L in a front-rear direction. 
     In this case, it means that the separation distance L is a physical distance between the inner glass  122  and the outer glass  121  which do not come into contact with each other when the inner glass  122  vibrates. 
     The outer glass  121  is formed in a shape in which an end portion of an inner circumferential surface thereof is bent in the rearward direction. In this case, the end portion of the inner circumferential surface of the outer glass  121  faces an end of an outer circumferential surface of the inner glass  122 . 
     Meanwhile, the exciters  130  are disposed at three or more points on a rear surface of the inner glass  122  to maximize a function of the inner glass  122  as a speaker diaphragm. In this case, the holder  150  is disposed in the frame  110  to support the exciters  130 . 
     Third Embodiment (Holder Structure Supporting Center of Inner Glass) 
       FIG. 6  is a perspective view illustrating a vehicle instrument cluster according to a third embodiment of the present invention, and  FIGS. 7 to 9  are cross-sectional views taken along lines C-C′, D-D′, and E-E′ illustrated in  FIG. 6 . 
     Referring to  FIGS. 6 to 9 , a vehicle instrument cluster  100  includes a frame  110 , a cover glass  120 , exciters  130 , and a holder  150 . 
     In the vehicle instrument cluster  100  according to the third embodiment, an outer glass  121  and an inner glass  122  are separated as in the second embodiment. 
     However, in the third embodiment, the holder  150  supporting the inner glass  122  is disposed at a center of an inner portion of the frame  110 . 
     In other words, the holder  150  according to the second embodiment has a form supporting the exciter  130 , and the holder  150  according to the third embodiment has a form supporting the inner glass  122 . 
     In this case, the holder  150  surrounds a display (not shown) included in a central portion of the frame  110 , and a portion, which is in contact with the inner glass  122 , of the holder  150  is formed in a curved surface shape. 
     The inner glass  122  may be formed to have a structure detachable from the holder  150 . 
     In a fourth embodiment and a fifth embodiment, when an exciter is mounted on a rear surface of a cover glass fixed to a connecting portion (mount portion) of a frame, vibration of the cover glass which vibrates due to the exciter is reduced due to the connecting portion. 
     Accordingly, due to a lack of air vibration causing sound generation, there is a problem in the performance of a speaker as a result of the lack. To this end, a vehicle instrument cluster of the present invention proposes a structure in which the cover glass separate from the frame is used as a speaker diaphragm through the fourth and fifth embodiments which will be described below. 
     Meanwhile, a forward direction described in the fourth and the fifth embodiment refers to a rear side of a vehicle and a rearward direction refers to a front side of the vehicle. 
     That is, the forward direction of the instrument cluster (panel) faces a driver when the driver views the front but refers to the rear side of the vehicle due to facing a trunk of the vehicle. Since the rearward direction of the instrument cluster faces a bonnet of the vehicle, the rearward direction thereof refers to the front side of the vehicle. 
     Fourth Embodiment (Installation Structure of Elastic Member (Vibration-Proof Rubber) on Cover Glass) 
       FIG. 10  is a perspective view illustrating the vehicle instrument cluster according to the fourth embodiment of the present invention, and  FIG. 11  is a cross-sectional view taken along line F-F′ illustrated in  FIG. 10 . 
     Referring to  FIGS. 10 and 11 , a vehicle instrument cluster  200  includes a frame  210 , a cover glass  220 , exciters  230 , an elastic member  240 , and a connecting member  250 . 
     The frame  210  is a frame that accommodates components configured to display vehicle operation information therein and has an open front surface. In this case, the vehicle operation information may refer to information indicating a vehicle speed, revolutions per minute (RPM), a temperature of cooling water, an amount of fuel, and the like. 
     Basically, the cover glass  220  has a form surrounding the front surface of the frame  210  and performs a speaker diaphragm function. 
     To this end, the cover glass  220  is connected to the frame  210  in a state in which the cover glass  220  is spaced apart from the frame  210 . In this case, a cover glass mount portion  221  formed on an end portion of the cover glass  220  faces a frame mount portion  211  formed on the front surface of the frame  210 . Here, the frame mount portion  211  is provided to have a hole structure in which a thread is formed on an inner circumferential surface thereof. 
     The exciter  230  is disposed on a rear surface of the cover glass  220 . The exciter  230  has a function of vibrating the cover glass  220 . 
     The elastic member  240  is disposed between the frame  210  and the cover glass  220 . The elastic member  240  is insertion-coupled to the mount portion  221  of the cover glass  220  in a state in which the elastic member  240  passes through the mount portion  221 . 
     In other words, the elastic member  240  passes through an inner circumferential surface of the cover glass mount portion  221  having a hollow shape and is insertion-coupled to the cover glass mount portion  221  in a form surrounding upper and lower ends of the cover glass mount portion  221 . 
     The elastic member  240  may be formed of vibration-proof rubber capable of removing a disturbance of a frequency greater than or equal to a specific frequency. 
     Here, the disturbance of a frequency greater than or equal to a specific frequency may refer to an internal reflected sound which may be generated due to an interaction between the frame  210  and the cover glass  220 . Detailed contents thereof will be described with reference to the accompanying drawings below. 
     The connecting member  250  connects the frame  210  to the cover glass  220  so that the elastic member  240  may be compressed by a predetermined displacement between the frame  210  and the cover glass  220 . 
     Here, the predetermined displacement refers to an extent (range) to which the elastic member  240  is displaced due to vibration of the cover glass  220  such that vibration energy of the cover glass  220  which vibrates due to the exciter  230  is not transferred to the frame  210 . 
     That is, the elastic member  240  should be displaceable to conserve the energy even when the cover glass  220  vibrates. 
     Accordingly, the connecting member  250  may connect the cover glass  220  and the frame  210  in the range in which the elastic member  240  is displaceable. 
     In this case, the connecting member  250  may be a shoulder screw. 
       FIG. 12  is a schematic perspective view illustrating the elastic member in the vehicle instrument cluster according to the fourth embodiment of the present invention. 
     Referring to  FIG. 12 , the elastic member  240  includes a web shaft  241 , an upper flange  242 , and a lower flange  243 . 
     The web shaft  241  passes through and is inserted into the mount portion  221  (see  FIG. 11 ) of the cover glass  220  (see  FIGS. 10 and 11 ) and is formed in a hollow shape. That is, the web shaft  241  includes an insertion hole  241   a  in a central portion thereof. 
     The upper flange  242  is formed to protrude outward from an upper end of the web shaft  241 . The upper flange  242  is disposed between the connecting member  250  (see  FIG. 11 ) and the cover glass  220  (see  FIGS. 10 and 11 ). 
     The lower flange  243  is formed to protrude outward from a lower end of the web shaft  241 . The lower flange  243  is disposed between the cover glass  220  (see  FIGS. 10 and 11 ) and the frame  210  (see  FIGS. 10 and 12 ). 
       FIG. 13  is a view illustrating a modified example of the elastic member and the cover glass in the vehicle instrument cluster according to the fourth embodiment of the present invention. 
     Referring to  FIG. 13 , an elastic member  240  includes an upper end pad  244  and a lower end pad  245 . 
     The upper end pad  244  is disposed between a connecting member  250  and a cover glass  220 . 
     The lower end pad  245  is disposed between the cover glass  220  and a frame  210 . 
     As described above, in the modified example illustrated in  FIG. 13 , a shape of an elastic member  240  is not integrally formed like in the fourth embodiment, and the elastic member  240  has a shape divided into an upper portion and a lower portion with the cover glass  220  interposed therebetween. 
     In the fourth embodiment, in the state in which the elastic member  240  passes through the cover glass mount portion  221 , the connecting member  250  passes through and is inserted into the insertion hole  241   a  (see  FIG. 12 ) of the elastic member  240 . 
     On the other hand, in the modified example of the fourth embodiment, since the elastic member  240  does not pass through a cover glass mount portion  221 , the connecting member  250  directly passes through and is inserted into the cover glass mount portion  221 . 
     Such a modified example is different from the fourth embodiment in the range in which the connecting member  250  shakes due to vibration. 
     In other words, in the fourth embodiment of the present invention, since the connecting member  250  is inserted into the elastic member  240 , the cover glass  220  has a high possibility of shaking in front-rear and up-down directions. 
     The connecting member  250  passes through the cover glass  220  and is fixedly inserted into the mount portion  211  of the frame  210  so that the elastic member  240  may be compressed by a predetermined displacement. 
     That is, in the modified example, since the connecting member  250  is directly inserted into the cover glass mount portion  221 , the cover glass  120  vibrates only in front-rear direction even when receiving the vibration. 
     In this case, the key point is that the elastic member  240  blocks vibration energy of the cover glass  220 , which vibrates due to the exciter  230  (see  FIG. 10 ), from being transferred to the frame  210 . 
       FIG. 14  is a cross-sectional view taken along line G-G′ illustrated in  FIG. 10 , and  FIG. 15  is a view illustrating a coupling relationship between the exciter and the cover glass in the vehicle instrument cluster according to the embodiment of the present invention. 
     Referring to  FIGS. 14 and 15 , the exciter  230  is an apparatus configured to supply an excitation current and is also referred to as an exciter. The exciter  230  vibrates the cover glass  220  using a signal current flowing in a voice coil. 
     To this end, the exciter  230  is disposed on the rear surface of the cover glass  220  and vibrates the cover glass  220  in the front-rear direction. 
     The exciters  230  are disposed on both ends of the rear surface of the cover glass  220  so that the cover glass  220  has a stereo effect as a speaker diaphragm. 
     In this case, the exciters  230  may also be disposed at three or more positions on the rear surface of the cover glass  220  at intervals. 
     The exciter  230  is coupled to the cover glass  220  through a snap-fit coupling method. That is, the exciter  230  and the cover glass  220  are detachably press-fitted to each other. 
     The exciter  230  includes a housing  231 , brackets  232 , and coupling hooks  233 . 
     The housing  231  accommodates a voice coil and a magnet therein. 
     The plurality of brackets  232  are formed on an outer circumferential surface of the housing  231 . In this case, the plurality of brackets  232  are formed at equidistant intervals along the outer circumferential surface of the housing  231 . In addition, one or more coupling holes  232   a  are formed in the plurality of brackets  232 . 
     In this case, it is more appropriate that the plurality of coupling holes  232   a  are not formed in the bracket  232 , but the plurality of coupling holes  232   a  may or may not be formed in the bracket  232  according to a position of the bracket  232 . 
     The coupling hook  233  is formed to be bent and extend in a forward direction of the bracket  232 . The coupling hook  233  is press-fitted to the rear surface of the cover glass  220 . 
     In this case, a plurality of coupling protrusions  222  engaged with and press-fitted to the coupling hooks  233  are formed on the rear surface of the cover glass  220 . 
     The coupling protrusions  222  include seating surfaces  222   a  and coupling rods  222   b.    
     The seating surface  222   a  is in surface contact with the bracket  232 . 
     The coupling rod  222   b  is formed to protrude in a rearward direction from the seating surface  222   a . The coupling rod  222   b  passes through the coupling hole  132   a  of the exciter  230 . 
       FIG. 16  is a graph showing a cut-off characteristic of the elastic member, which removes a disturbance of a frequency greater than or equal to a specific frequency, in the vehicle instrument cluster according to the fourth embodiment of the present invention; 
     When describing  FIG. 16 , in order to facilitate understanding of the corresponding graph,  FIG. 16  will be described with reference to  FIGS. 10 to 15  (reference numerals) which have been described above. 
     Referring to  FIG. 16 , a data value which denotes a property of the elastic member  240  in a state in which the cover glass  220  on which the exciter  230  is mounted is isolated by the elastic member  240  may be seen. 
     That is, a feature of the elastic member  240  is to remove a disturbance (internal reflected sound) of a frequency greater than or equal to a specific frequency. Due to the elastic member  240 , internal reflected energy of the cover glass  120  is reduced. 
     Generally, due to an interaction between a support surface (frame  210 ) and a speaker bottom (cover glass  220 ), speaker energy may be internally reflected so that a sound distortion may occur. 
     A speaker generates vibration and stimulates the support surface which generates an unnatural sound. In addition, a situation may occur in which energy resonates and is transferred to other spaces through the support surface, or the speaker stimulates other objects within a listening area. 
     In this case, the internal reflected sound may cause a decrease in sound clearness, or the sound may be three-dimensionally and widely spread. As a result, the internal reflected sound causes a sound distortion to lose the sound clearness and openness. 
     However, in the elastic member  240  of the present invention, since the cover glass  220  is isolated through a double structure to solve the above-described problem, a disturbance of a frequency greater than or equal to a specific frequency is removed so that the internal reflected energy of the cover glass  220  can be reduced. 
     Fifth Embodiment (Installation Structure of Magnet Bearing on Cover Glass) 
       FIG. 17  is a perspective view illustrating a vehicle instrument cluster according to a fifth embodiment of the present invention,  FIG. 18  is an exploded perspective view illustrating the vehicle instrument cluster according to the fifth embodiment of the present invention, and  FIG. 19  is a cross-sectional view taken along line H-H′ illustrated in  FIG. 17 . 
     Referring to  FIGS. 17 to 19 , a vehicle instrument cluster  200  mainly includes a frame  210 , a magnet bearing  260 , a cover glass  220 , and a limiter  270 . 
     In this case, among the above components, contents overlapping those of the fourth embodiment will be omitted. 
     The frame  210  has an accommodation space of which a front surface is open and includes a plurality of coupling pieces  212  formed on an end portion of an outer side thereof. In this case, the coupling piece  212  is formed to have a hollow shape and have a structure in which a portion of an end portion of a rear surface is bent. 
     The magnet bearing  260  includes an outer magnet  261  and an inner magnet  262 . 
     The outer magnet  261  is mounted on the coupling piece  212 . In this case, the coupling piece  212  surrounds a rear surface of the outer magnet  261  to prevent the outer magnet  261  from being separated to the outside. 
     In this case, the outer magnet  261  is formed of N and S poles which are vertically and alternately disposed and is formed in a hollow shape of which an interior is empty. 
     The inner magnet  262  is disposed inside the outer magnet  261  in a state in which the inner magnet  262  is spaced apart from the outer magnet  261 . 
     In this case, the inner magnet  262  is also formed of N and S poles which are vertically and alternately disposed like the outer magnet  261 , and the outer magnet  261  and the inner magnet  262  are disposed so that different poles are alternately disposed to generate an attractive force between the outer magnet  261  and the inner magnet  262 . 
     The inner magnet  262  is fixed to a fixed shaft  223  of the cover glass  220 . In this case, the fixed shaft  223  is fixed in a state of being inserted into the inner magnet  262 . 
     A non-contact state between the inner magnet  262  and the outer magnet  261  is maintained due to a magnetic force to protect vibration energy of the cover glass  220  which vibrates due to exciters  230  from being transferred to the outer magnet  261 . 
     The limiter  270  is connected to the fixed shaft  223  of the cover glass  220  to prevent the cover glass  220  from being separated from the coupling piece  212 . 
     To this end, the limiter  270  may have a width greater than a diameter of an inner circumferential surface of the outer magnet  261 . 
     In this case, the limiter  270  may be formed of an impact relief material such as a synthetic rubber so as to relieve an external impact. 
       FIG. 20  is a schematic perspective view illustrating the magnet bearing in the vehicle instrument cluster according to the fifth embodiment of the present invention, and  FIGS. 21 and 22  are graphs showing result values according to a change in position of the inner magnet in the magnet bearing of  FIG. 20 . 
     Referring to  FIGS. 20 and 21 , when the inner magnet  262  is moved in a front-rear direction with respect to a Z-axis, as shown in the graph of  FIG. 21 , an axial force is generated in a predetermined range of front-rear movement so that Fz is positioned at 0 mm. 
     Conversely, in  FIGS. 20 and 22 , when the inner magnet  262  is moved in an up-down direction, as shown in the graph of  FIG. 22 , a radial force is increased in a direction in which a radius thereof is increased, that is, as the inner magnet  262  is moved away from a center. 
     As a result, a center position of the inner magnet  262  is maintained due to the axial force and the radial force. 
       FIG. 23  is a cross-sectional view taken along line I-I′ illustrated in  FIG. 17 . 
     Referring to  FIG. 23 , the cover glass  220  on which one or more exciters  230  are mounted is floated in the air by the magnet bearing  260 . 
     In this case, the exciter  230  vibrates the cover glass  220  in the front-rear direction, and vibration energy of the cover glass  220  is conserved by the magnet bearing  260 . 
     That is, the vibration energy of the cover glass  220  which vibrates due to the exciter  230  is not transferred to the frame  210  through the magnet bearing  260 . 
     As described above, in the present invention, after a cover glass is divided into an outer glass and an inner glass, the inner glass on which an exciter is mounted is used as a speaker diaphragm so that a direction of an image of an instrument cluster can be the same as that of a sound thereof. 
     Accordingly, in the present invention, a sound image can be formed in a center of a screen, and a sound field can be formed in the entire screen to greatly help a driver to recognize a situation. 
     In addition, according to the embodiments of the present invention, vibration attenuation of the inner glass on which the exciter is mounted is minimized due to a holder and a suspension connected to the inner glass so that the inner glass can effectively function as the speaker diaphragm. 
     Although exemplary embodiments of the present disclosure have been shown and described hereinabove, the present disclosure is not limited to specific exemplary embodiments described above, but may be various modified by those skilled in the art to which the present disclosure pertains without departing from the scope and spirit of the disclosure as disclosed in the accompanying claims. In addition, such modifications should also be understood to fall within the scope and spirit of the present disclosure.