Patent Publication Number: US-6211775-B1

Title: Vibration apparatus capable of generating and externally transmitting a sound wave of audible frequency and transmitting a vibration for notification

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a vibration apparatus capable of generating and externally transmitting a sound wave of audible frequency and transmitting a vibration for notification, which is provided in a communication device such as a portable phone, a beeper or the like to selectively perform a sounding function and a vibrating function relying upon a frequency of a current inputted therein. 
     2. Description of the Related Art 
     Generally, the notification of the reception of an incoming call in a portable communication device can be performed by a sounding function and a vibrating function. Between these two functions, the sounding function by which bell or speaker sound can be discharged is mainly used, and the sounding function can be converted into the vibrating function to be used in such a situation where a silent atmosphere must be inevitably maintained. 
     In order to perform the sounding function and the vibrating function, a micro-speaker and a vibrating motor are provided in a communication device to be selectively operated in compliance with an instruction inputted by a user. 
     Referring to FIG. 1, there is shown a longitudinal cross-sectional view illustrating a construction of a conventional micro-speaker. The micro-speaker includes a case  1 . A magnet  2 , a voice coil  3  and a vibrating coil  4  are arranged in the case  1 . In other words, the magnet  2  is secured at a center portion in the case  1 . A cylindrically formed voice coil  3  is arranged around the magnet  2  such that it surrounds the magnet  2 , and an upper end of the voice coil  3  which extends upward through the case  1  is attached to a vibrating coil  4 . The magnet  2  has N and S poles which are stacked one up the other, and a portion adjacent to an edge of the vibrating coil  4  to which the voice coil  3  is attached, is securely fastened to a fastening member. 
     Accordingly, if a high frequency alternate current is inputted into the voice coil  3  through a lead wire, the alternate current flows at a lower end of the voice coil  3  which is inserted into the case  1 , to form a magnetic field while interacting with the magnet  2 . 
     At this time, when the magnetic field is formed in the same direction as a magnetic filed formed by the magnet  2 , attractive force is generated between the magnet  2  and the voice coil  3  to lower the voice coil  3 . If a polarity of a current which flows through the voice coil  3  is converted into a reverse polarity, repulsive force is generated between the magnet  2  and the voice coil  3  to raise the voice coil  3 . 
     By repeatedly lowering and raising the voice coil  3  using the high frequency current inputted into the voice coil  3 , the vibrating plate  4  to which the voice coil  3  is attached moves up and down. By this upward and downward movement of the vibrating plate  4 , a sound wave is generated. 
     In a speaker manufactured using a principle that the vibrating plate  4  is moved up and down by the inputted high frequency current to generate a sound wave, a high frequency signal such as a melody, a bell or a sound signal of a sender, which is inputted in advance into the voice coil  3 , is discharged by the upward and downward movement of the vibrating plate  4  to perform the sounding function. 
     However, because the speaker can simply produce a sound, to afford not only the sounding function but also the vibrating function, a separate vibrating motor must be provided. 
     On the other hand, as demands toward miniaturization and thinning of a communication device are increased, while it is necessary for several components to be omitted and a size of the communication device to be reduced, a speaker and a vibrating motor are still used together for notifying the reception of an incoming call in a communication device. 
     Recently, various vibration generating apparatuses for simultaneously performing a speaker function and a vibration function are disclosed in the art. A typical example of these vibration generating apparatuses is described in Japanese Patent Laid-Open Publication No. Heisei 10-14195 (published on Jan. 16, 1998) as shown in FIG.  2 . 
     The vibration generating apparatus includes largely a permanent magnet  300  fastened to a fastening member  400 , upper and lower yokes  310  and  320  attached to upper and lower surfaces of the permanent magnet  300  for preventing magnetic flux from being leaked and forming a magnetic flux path, a coil  121  arranged such that it is crossed with the magnetic flux of the permanent magnet  300 , a first vibrating body  120  supported to the fastening member  400  by a first elastic member  110 , a second vibrating body  220  supported to the first vibrating body  120  by a second elastic member  210 , and a current supplying section  500  connected to the coil  121  for supplying a current of a predetermined frequency to the coil  121 . 
     In the vibration generating apparatus constructed as mentioned above, if a current is inputted into the coil  121  from the current supplying section  500 , electromagnetic force is generated due to interaction between the permanent magnet  300  and the coil  121 . Accordingly, by periodically changing the current flowing through the coil  121  to have a high frequency and a low frequency, electromagnetic force is periodically generated as external force to a magnetic circuit section having the permanent magnet  300  and the upper and lower yokes  310  and  320  and to the first vibrating body  120 , and by this, a forced vibration occurs in a first vibration system  100  including the first vibrating body  120 . 
     By this vibration, a second vibration system  200  is also vibrated, and as a result, vibrations are occurred in the first and second vibration systems  100  and  200  by the permanent magnet  300  and the coil  121 . 
     That is to say, if a current having a frequency which corresponds to a natural vibration frequency of the first vibrating body  120  is inputted into the coil  121 , vibrating function which is similar to conventional vibrating function is accomplished by the first vibrating body  120 . Also, if a current having a frequency which corresponds to a natural vibration frequency of the second vibrating body  220  is inputted into the coil  121 , a sound is generated by the second vibrating body  220 . 
     However, in the vibration generating apparatus of the related art, since the vibrating function is performed by the fact that the first vibrating body  120  is vibrated to be collided with the case  400  to generate a vibration which is to be sensed by a user through the case  400 , although a shock-absorbing material is attached to the case  400  at a place where the first vibrating body  120  is collided with the case  400 , noise is generated by the collision, and since the vibration is transmitted through the first and second elastic members  110  and  210  to the case  400 , lower vibration level is obtained. 
     Also, durability of the vibration generating apparatus is deteriorated due to the repeated collision between a bobbin  122  of the first vibrating body  120  and the case  400 . Moreover, it is difficult to properly design material and shape for the first elastic member  110 , the second vibrating body  220  and the second elastic member  210  and to determine elastic modulus for the first and second elastic members  110  and  210 , whereby the vibration generating apparatus cannot be easily manufactured. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been made in an effort to solve the problems occurring in the related art, and a primary object of the present invention is to provide a vibration apparatus capable of generating and externally transmitting a sound wave of audible frequency and transmitting a vibration for notification, which performs both a sounding function and a vibrating function with a simple structure, thereby to promote miniaturization of a communication device. 
     Another object of the present invention is to provide the vibration apparatus capable of generating and externally transmitting a sound wave of audible frequency and transmitting a vibration for notification, in which components are prevented from being collided one with another when performing the vibrating function, thereby to increase durability of the communication device and render the communication device to be semi-permanently used. 
     Still another object of the present invention is to provide the vibration apparatus capable of generating and externally transmitting a sound wave of audible frequency and transmitting a vibration for notification, which can realize miniaturization and thinning of the communication device. 
     In order to achieve the above objects, a vibration apparatus according to the present invention includes a voice coil and a pair of vibrating coils into which currents are inputted from the outside. In the vibration device, if a high frequency current is inputted, a vibrating plate or a vibrating body having a construction which is similar to that of the vibrating plate moves up and down, thereby to generate a sound wave, whereby it is possible to notify of reception of an incoming call by the sound wave. If a low frequency current is inputted, because currents having different polarities flow to both ends of each of the pair of vibrating coils which are disposed in a side-by-side relationship such that they are opposite to a magnet, the magnet or the vibrating body onto which the pair of vibrating coils are attached seesaws sideways, thereby to generate a vibration as a seesaw motion of the magnet or the vibrating body is transferred to a cover attached to a case of a communication device, whereby it is possible to notify of reception of an incoming call by the vibration. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above objects, and other features and advantages of the present invention will become more apparent after a reading of the following detailed description when taken in conjunction with the drawings, in which: 
     FIG. 1 is a longitudinal cross-sectional view illustrating a construction of a conventional micro-speaker; 
     FIG. 2 is a longitudinal cross-sectional view of a vibration generating apparatus of the related art; 
     FIG. 3 is a longitudinal cross-sectional view of a vibration apparatus in accordance with a first embodiment of the present invention; 
     FIG. 4 is an exploded perspective view of the vibration apparatus of FIG. 3; 
     FIG. 5 is a plan view illustrating another possible arrangement of vibrating coils according to the present invention; 
     FIG. 6 is a longitudinal cross-sectional view illustrating operations of the vibration apparatus according to the first embodiment of the present invention when a sound wave is generated by a second vibrating section; 
     FIG. 7 is a longitudinal cross-sectional view illustrating operations of the vibration apparatus according to the first embodiment of the present invention when a seesaw vibration is generated by a first vibrating section; 
     FIG. 8 is a longitudinal cross-sectional view of a vibration apparatus in accordance with a second embodiment of the present invention; 
     FIG. 9 is a longitudinal cross-sectional view illustrating operations of the vibration apparatus according to the second embodiment of the present invention when a sound wave is generated by a second vibrating section; 
     FIG. 10 is a longitudinal cross-sectional view illustrating operations of the vibration apparatus according to the second embodiment of the present invention when a seesaw vibration is generated by a first vibrating section; 
     FIG. 11 is a longitudinal cross-sectional view of a vibration apparatus in accordance with a third embodiment of the present invention; 
     FIG. 12 is a longitudinal cross-sectional view illustrating operations of the vibration apparatus according to the third embodiment of the present invention when a sound wave is generated by a second vibrating section; 
     FIG. 13 is a longitudinal cross-sectional view illustrating operations of the vibration apparatus according to the third embodiment of the present invention when a seesaw vibration is generated by a first vibrating section; 
     FIG. 14 is a longitudinal cross-sectional view of a vibration apparatus in accordance with a fourth embodiment of the present invention; 
     FIG. 15 is a longitudinal cross-sectional view illustrating operations of the vibration apparatus according to the fourth embodiment of the present invention when a sound wave is generated as a vibrating section moves up and down; 
     FIG. 16 is a longitudinal cross-sectional view illustrating operations of the vibration apparatus according to the fourth embodiment of the present invention when a vibration is generated as the vibrating section seesaws sideways; 
     FIG. 17 is a longitudinal cross-sectional view illustrating operations of the vibration apparatus according to the fourth embodiment of the present invention when a sound wave is generated as the vibrating section moves up and down in the case that a structure for supporting a vertical shaft is modified; 
     FIG. 18 is a longitudinal cross-sectional view illustrating operations of the vibration apparatus according to the fourth embodiment of the present invention when a vibration is generated as the vibrating section seesaws sideways in the case of the structure of FIG. 17; and 
     FIG. 19 is a graph showing a relationship between frequency and amplitude of a current. 
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in greater detail to a preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings and the description to refer to the same or like parts. 
     Referring to FIG. 3, there is shown a longitudinal cross-sectional view of a vibration apparatus in accordance with a first embodiment of the present invention; and FIG. 4 is an exploded perspective view of the vibration apparatus of FIG.  3 . The vibration apparatus of the present embodiment is largely divided into a first vibrating section, a second vibrating section, a fixed section and a driving control section. 
     The first vibrating section includes an upper cover  10 , a lower cover  20 , a magnet  30  and a yoke  31 . The upper cover  10  has a cap-shaped configuration which opens downward. A center portion of a top wall of the upper cover  10  is formed with a sound discharging hole  11  which communicates the outside with the inside. The lower cover  20  has a cup-shaped configuration which opens upward. The lower cover  20  possesses an upper end which is coupled to a lower end of the upper cover  10 . A center portion of a bottom wall of the lower cover  20  is formed with an opening which has a diameter nearly approaching to that of the bottom wall of the lower cover  20 . 
     The magnet  30  is closely fitted into the opening formed in the bottom wall of the lower cover  20  to be securely fastened thereto, and the yoke  31  is bonded onto the magnet  30 . At this time, the yoke  31  has a diameter which is larger than that of the magnet  30  and at the same time, prevents magnetic flux leakage from the magnet  30 . The yoke  31  provides smooth magnetic flux flow which is connected to the magnet  30 , yoke  31 , upper cover  10  and lower cover  20 . 
     The second vibrating section includes a vibrating plate  40  and a voice coil  50  attached to the vibrating plate  40 . The vibrating plate  40  is arranged above the yoke  31  such that it is separated from an upper surface of the yoke  31  by a short distance and has a diameter which is larger than that of the yoke  31 . The vibrating plate  40  is flat plate-shaped vibrating means. The vibrating plate  40  is slopingly bent upward at a portion adjacent an edge thereof, and the edge of the vibrating plate  40  is fixedly secured to an inner surface of the upper cover  10 . 
     The voice coil  50  is configured such that it surrounds the magnet  30  and the yoke  31 , and has a diameter which is larger than that of the yoke  31 . An upper end of the voice coil  50  is fastened to a flat portion of the vibrating plate  40 . The voice coil  50  is an operating member which is moved up and down while interacting with the magnet  30  when a current is inputted. 
     The fixed section includes a fixed cover  60 , a pair of vibrating coils  70  and an elastic member  80 . The fixed cover  60  is positioned below the first vibrating section and attached to a case of a communication device as fastening means. The pair of vibrating coils  70  are attached onto an upper surface of the fixed cover  60  in a side-by-side relationship such that they are opposite to the magnet  30 . The elastic member  80  elastically connects the first vibrating section and the fixed cover  60  with each other and serves as connecting means for transmitting vibrating force to the fixed cover  60 . 
     Specifically, the vibrating coils  70  can be provided as a pair at both sides on the upper surface of the fixed cover  60  to be connected in series such that their winding directions are opposite to each other to have different polarities when currents flow, and alternatively, as shown in FIG. 5, at least two pairs of coils can be connected in series such that a coil into which a current is inputted is sequentially changed. Also, it is most preferred that the elastic member  80  for elastically supporting the first vibrating section is formed using a coil spring. 
     On the other hand, the driving control section  90  serves as power supplying means which selectively supplies currents to the voice coil  50  of the second vibrating section and the pair of vibrating coils  70  attached onto the upper surface of the fixed cover  60 , and causes the polarities of the supplied currents to be alternately changed. Especially, the driving control section  90  has a switching function for allowing currents having different polarities to flow through the pair of vibrating coils  70 . 
     In other words, the driving control section  90  has input terminals and output terminals which are connected to the voice coil  50  and the pair of vibrating coils  70 , respectively. The driving control section  90  supplies a current which has a frequency corresponding to a natural frequency of the first vibrating section and a current which has a frequency corresponding to a natural frequency of the second vibrating section, depending on a frequency of a current. 
     The driving control section  90  includes a current supplying part for selectively supplying currents to the voice coil  50  and the pair of vibrating coils  70  and a switching part for selectively switching connections between the pair of vibrating coils  70 . 
     Therefore, if a high frequency current for generating a sound wave which corresponds to the natural frequency of the first vibrating section, is inputted into the driving control section  90 , by supplying the high frequency current to the voice coil  50  while alternately changing its polarities, attractive force and repulsive force are alternately generated between the voice coil  50  and the magnet  30  as shown in FIG. 6, and according to this, the voice coil  50  which is movably arranged is moved up and down. By this, the vibrating plate  40  attached to the upper end of the voice coil  50  is also moved in a state that it is interlocked with the voice coil  50 , and a sound wave is generated by the upward and downward movement of the vibrating plate  40 . The sound wave generated in this way is discharged through the sound discharging hole  11  formed in the upper cover  10  to be sensed as a sound signal. 
     On the other hand, if a low frequency current for generating a vibration which corresponds to the natural frequency of the second vibrating section, is inputted into the driving control section  90 , by supplying the low frequency current to the pair of vibrating coils  70  attached onto the upper surface of the fixed cover  60  while alternately changing their polarities as in the case of the voice coil  50 , the first vibrating section seesaws sideways as shown in FIG.  7 . 
     That is to say, by the currents supplied to the pair of vibrating coils  70 , currents having different polarities flow through the pair of vibrating coils  70 , and at this time, attractive force and repulsive force are generated in the pair of vibrating coils  70  by interaction between the pair of vibrating coils  70  and the magnet  30  which are opposite to each other. 
     Namely, if attractive force is generated between one coil and the magnet  30 , since repulsive force is generated between the other coil and the magnet  30 , the magnet  30  which is movably disposed seesaws sideways. At this time, because the magnet  30  is integrally coupled to the lower cover  20  which is in turn coupled to the upper cover  10 , the entire first vibrating section seesaws sideways. 
     Vibrating force generated by this seesaw motion is transmitted through the elastic member  80  which connects the first vibrating section and the fixed cover  60  with each other, to the fixed cover  60 . The vibrating force transmitted in this way can be sensed by a user as a vibration through the case of the communication device to which the fixed cover  60  is attached. 
     In the meantime, by the magnet  30  of the first vibrating section, two magnetic circuits each having a magnetic gap are defined between the upper cover  10  and the lower cover  20  and between the lower cover  20  and the fixed cover  60 , respectively. It is most preferred that in these magnetic gaps, magnetic fields of the voice coil  50  and the pair of vibrating coils  70  are positioned such that they are orthogonal to a magnetic field of the magnet  30 . 
     Referring to FIG. 8, there is shown a longitudinal cross-sectional view of a vibration apparatus in accordance with a second embodiment of the present invention. 
     While the construction of the present embodiment is similar to that of the first embodiment in that it has a first vibrating section, a fixed section, a second vibrating section and a driving control section, in this embodiment of the present invention, the first vibrating section has an upper cover  10  and a magnet  30  secured to an inner surface of the upper cover  10 . The upper cover  10  has a cap-shaped configuration which opens downward, and the magnet  30  has polarities which are divided up and down. 
     The fixed section has a fixed cover  60  which is positioned below the upper cover  10  and connected to the upper cover  10  by a first elastic member  81 . The fixed cover  60  is formed at a center portion thereof with a sound discharging hole  61 . 
     The second vibrating section includes a vibrating plate  40  which is positioned above the fixed cover  60  and connected to the fixed cover  60  by a second elastic member  82  and a pair of vibrating coils  70  which are attached onto the vibrating plate  40 . At this time, the second elastic member  82  is positioned inside the first elastic member  81  which connects the fixed cover  60  and the upper cover  10  with each other. The pair of vibrating coils  70  are attached onto at least an upper surface of the vibrating plate  40  in a side-by-side relationship such that they are opposite to the magnet  30 , or as in the first embodiment, at least two pairs of coils can be connected to form the vibrating coils  70 . Specifically, the vibrating coils  70  are connected in series. 
     On the other hand, the driving control section  90  serves as power supplying means which supplies currents to the pair of vibrating coils  70  of the second vibrating section and causes the supplied currents to have the same polarity or different polarities. 
     Namely, the driving control section  90  selectively supplies a current which has a frequency corresponding to a natural frequency of the first vibrating section and a current which has a frequency corresponding to a natural frequency of the second vibrating section by supplying currents of predetermined frequencies to the pair of vibrating coils  70 . 
     The driving control section  90  includes a current supplying part for supplying currents to the pair of vibrating coils  70  and a switching part for selectively switching connections between the pair of vibrating coils  70 . 
     Therefore, if a high frequency current for generating a sound wave which corresponds to the natural frequency of the second vibrating section, is inputted into the driving control section  90 , by supplying the high frequency current to the pair of vibrating coils  70  while causing currents to flow in the pair of vibrating coils  70  in the same direction to allow the currents to have the same polarity, attractive force and repulsive force are alternately generated between the pair of vibrating coils  70  and the magnet  30  as shown in FIG. 9, and according to this, the second vibrating section having the pair of vibrating coils  70  which are movably arranged and the vibrating plate  40  which is attached to the pair of vibrating coils  70  is moved up and down. 
     By this upward and downward movements of the second vibrating section, a sound wave is generated between the vibrating plate  40  and the upper surface of the fixed plate  60 . The sound wave generated in this way is discharged through the sound discharging hole  61  formed in the fixed cover  60  to be sensed as a sound signal. 
     On the other hand, if a low frequency current for generating a vibration which corresponds to the natural frequency of the first vibrating section, is inputted into the driving control section  90 , by supplying the low frequency current to the pair of vibrating coils  70  attached onto the upper surface of the fixed cover  60  while switching connecting terminals of the pair of vibrating coils  70  such that currents flow in the pair of vibrating coils  70  in opposite directions to allow the pair of vibrating coils  70  to have different polarities, the first vibrating section seesaws sideways as shown in FIG.  10 . 
     That is to say, by the currents supplied to the pair of vibrating coils  70 , currents having different polarities flow through the pair of vibrating coils  70 , and at this time, attractive force and repulsive force are generated in the pair of vibrating coils  70  by interaction between the pair of vibrating coils  70  and the magnet  30  which are opposite to each other. 
     Namely, if attractive force is generated between one coil and the magnet  30 , since repulsive force is generated between the other coil and the magnet  30 , the first vibrating section having the natural frequency corresponding to a natural frequency of the low frequency current seesaws sideways. 
     The vibrating force generated by this seesaw motion is transmitted through the elastic member  81  which connects the first vibrating section and the fixed cover  60  with each other, to the fixed cover  60 . The vibrating force transmitted in this way can be sensed by a receiver as a vibration through the case of the communication device to which the fixed cover  60  is attached. 
     In the meantime, by the magnet  30  of the first vibrating section, a magnetic circuit having a magnetic gap is defined between the upper cover  10  and the fixed cover  60 . A magnetic field generated from the pair of vibrating coils  70  of the second vibrating section in the magnetic gap is positioned such that it is orthogonal to a magnetic field of the magnet  30 . 
     Referring to FIG. 11, there is shown a longitudinal cross-sectional view of a vibration apparatus in accordance with a third embodiment of the present invention. 
     The vibration apparatus of this embodiment has an outer case, a first vibrating section, a second vibrating section and a driving control section. 
     The outer case includes an upper cover  10  and a lower cover  20 . The upper cover  10  has a cap-shaped configuration which opens downward, and the lower cover  20  covers a lower end of the upper cover  10 . The upper cover  10  is formed at a center portion thereof with a sound discharging hole  11 . 
     The first vibrating section includes a magnet  30  which is connected to the lower cover  20  by an elastic member  80  and a vertical shaft  32  which movably guides the magnet  30 . 
     At this time, the vertical shaft  32  has a lower end which is connected to the lower cover  20  to prevent the magnet  30  from being excessively moved sideways. 
     The second vibrating section includes a vibrating plate  40  which is arranged between a top wall of the upper cover  10  and the magnet  30 , and a pair of vibrating coils  70 . At this time, the vibrating plate  40  is secured to an inner surface of the top wall of the upper cover  10 , and the pair of vibrating coils  70  are attached onto a lower surface of the vibrating plate  40  such that they are opposite to the magnet  30 . 
     Accordingly, a magnetic circuit having a magnetic gap is defined between the upper cover  10  and the lower cover  20  while the magnet  30  is placed at a middle portion, and in this magnetic gap, magnetic fields of the pair of vibrating coils  70  and the magnet  30  are orthogonal to each other to create electromagnetic force. 
     Further, at least two pairs of coils can be provided to form the vibrating coils  70  of the second vibrating section. Specifically, the vertical shaft  32  can be connected to the lower cover  20  via a damping member  22 , and according to this, an upper end of the vertical shaft  32  arranged between the upper cover  10  and the lower cover  20  can be moved sideways to some extent. 
     On the other hand, the driving control section  90  serves as actual control means connected to the pair of vibrating coils  70  of the second vibrating section for receiving and supplying predetermined frequencies. 
     The driving control section  90  includes a current supplying part for supplying currents having the predetermined frequencies to the pair of vibrating coils  70  and a switching part for selectively switching connections between the pair of vibrating coils  70  such that currents having the same polarity and different polarities can selectively flow through the pair of vibrating coils  70 . 
     Consequently, if a high frequency current for generating a sound wave is inputted into the driving control section  90 , the high frequency current is supplied to the pair of vibrating coils  70 , and at the same time, the connections between the pair of vibrating coils  70  are switched such that currents having the same polarity flow in the pair of vibrating coils  70  in the same direction. 
     If the currents are supplied as described above, attractive force and repulsive force are alternately generated between the pair of vibrating coils  70  and the magnet  30  as shown in FIG. 12 while creating electromagnetic force. 
     At this time, as the second vibrating section having a natural frequency which is the same as that of the high frequency current inputted into the pair of vibrating coils  70  repeatedly moves up and down at high speed, a sound wave is generated by the vibrating plate  40  of the second vibrating section. The sound wave generated in this way is discharged through the sound discharging hole  11  formed in the upper cover  10  to be sensed as a sound signal. 
     On the other hand, if a low frequency current for generating a vibration is inputted into the driving control section  90 , the low frequency current is supplied to the pair of vibrating coils  70 , and at the same time, the connections between the pair of vibrating coils  70  are switched such that currents having different polarities flow in the pair of vibrating coils  70  in opposite directions. 
     If the currents are supplied as just described above, attractive force and repulsive force are alternately generated between the pair of vibrating coils  70  and the magnet  30  as shown in FIG. 13 while creating electromagnetic force. 
     At this time, as the first vibrating section having a natural frequency which is the same as that of the low frequency current inputted into the pair of vibrating coils  70  repeatedly seesaws sideways, vibrating force is transmitted through the elastic member  80  of the first vibrating section to the lower cover  20 . The vibrating force transmitted in this way can be sensed by a receiver as a vibration while being transmitted to the case of the communication device. 
     In the meanwhile, in order to increase the vibrating force generated by the seesaw motion of the first vibrating section, as best shown in FIGS. 11 through 13, it is more preferable that a weight  33  having a predetermined weight be attached to a lower surface or a circumferential outer surface of the magnet  30 . 
     Also, as described above, in the case that a plurality of coils are used to form the vibrating coils  70  of the second vibrating section, if a current is sequentially supplied to only one coil in a rotational direction by the switching part of the driving control section, as attractive force is generated between the coil supplied with the current and the magnet  30 , the first vibrating section is eventually made to seesaw three-dimensionally and wave vibration effect can be obtained, whereby vibrating force can be more amplified. 
     Referring to FIG. 14, there is shown a longitudinal cross-sectional view of a vibration apparatus in accordance with a fourth embodiment of the present invention. The vibration apparatus of this embodiment largely includes an outer case, a vibrating section and a driving control section. 
     As aforementioned in the third embodiment, the outer case includes an upper cover  10  and a lower cover  20 . The upper cover  10  has a cap-shaped configuration which opens downward, and the lower cover  20  covers a lower end of the upper cover  10 . The upper cover  10  is formed at a center portion thereof with a sound discharging hole  11 . A pair of vibrating coils  70  are attached onto an upper surface of the lower cover  20 . 
     The vibrating section includes a magnet  30  which is connected to the lower cover  20  by an elastic member  80 , and a vertical shaft  32  which supports the magnet  30  such that it can be slid up and down. Specifically, an upper surface of the magnet  30  which is opposite to the sound discharging hole  11  of the upper cover  10 , is tapered upward from a center portion thereof toward an edge portion thereof. The vertical shaft  32  has a lower end which is connected to the lower cover  20  via a damping member  22  to allow an upper end of the vertical shaft  32  to be moved sideways to some extent. 
     By this arrangement, a magnetic circuit having a magnetic gap is defined between the upper cover  10  and the lower cover  20  while the magnet  30  is placed at a middle portion, and in this magnetic circuit, magnetic fields of the pair of vibrating coils  70  and the magnet  30  are orthogonal to each other to create electromagnetic force. 
     Further, at least two pairs of coils can be provided to form the vibrating coils  70  attached onto the upper surface of the lower cover  20 . A weight  33  having a predetermined weight can be attached to a lower surface or both side surfaces of the magnet  30  of the vibrating section, to amplify vibrating force of the vibrating section. 
     On the other hand, the driving control section  90  serves as actual control means connected to the pair of vibrating coils  70  attached onto the lower cover  20  for receiving and supplying predetermined frequencies. 
     The driving control section  90  includes a current supplying part for supplying currents having the predetermined frequencies to the pair of vibrating coils  70  and a switching part for selectively switching connections between the pair of vibrating coils  70  such that currents having the same polarity and different polarities can selectively flow through the pair of vibrating coils  70 . 
     Consequently, if a high frequency current for generating a sound wave is inputted into the driving control section  90 , the high frequency current is supplied to the pair of vibrating coils  70 , and at the same time, the connections between the pair of vibrating coils  70  are switched such that currents having the same polarity flow in the pair of vibrating coils  70  in the same direction. 
     If the currents are supplied as described above, attractive force and repulsive force are alternately generated between the pair of vibrating coils  70  and the magnet  30  as shown in FIG. 15 while creating electromagnetic force. 
     By this interaction, as the vibrating section repeatedly moves up and down at high speed, a sound wave is generated by the magnet  30  of the vibrating section. The sound wave generated in this way is discharged through the sound discharging hole  11  formed in the upper cover  10  to be sensed as a sound signal. 
     On the other hand, if a low frequency current for generating a vibration is inputted into the driving control section  90 , the low frequency current is supplied to the pair of vibrating coils  70 , and at the same time, the connections between the pair of vibrating coils  70  are switched such that currents having different polarities flow in the pair of vibrating coils  70  in opposite directions. 
     If the currents are supplied as just described above, attractive force and repulsive force are alternately generated between the pair of vibrating coils  70  and the magnet  30  as shown in FIG. 16 while creating electromagnetic force. 
     By this interaction, as the vibrating section repeatedly seesaws sideways, the seesaw motion is transmitted through the elastic member  80  which connects the vibrating section to the lower cover  20 . The vibrating force transmitted to the lower cover  20  in this way can be sensed by a receiver as a vibration while being transmitted to the case of the communication device. 
     In the meanwhile, in order to increase the vibrating force generated by the seesaw motion of the vibrating section, as best shown in FIGS. 14 through 16, it is more preferable that a weight  33  having a predetermined weight be attached to a lower surface or a circumferential outer surface of the magnet  30 . 
     Also, as described above, in the case that a plurality of coils are used to form the vibrating coils  70  of the vibrating section, if a current is sequentially supplied to only one coil in a rotational direction by the switching part of the driving control section, as attractive force is generated between the coil supplied with the current and the magnet  30 , the vibrating section is eventually made to seesaw three-dimensionally and wave vibration effect can be obtained, whereby vibrating force can be more amplified. 
     In the present embodiment, a shaft seat  23  as shown in FIG. 17 can be used in place of the damping member  22  to support the lower end of the vertical shaft  32 . In this case, the lower end of the vertical shaft  32  has a spherical cross-section to be inserted into and rotatably supported by the shaft seat  23 . 
     In the construction of the vibration apparatus according to the present embodiment, if a high frequency current is inputted into the pair of vibrating coils  70 , the magnet  30  of the vibrating section moves up and down along the vertical shaft  32  to perform a sounding function, and if a low frequency current is inputted into the pair of vibrating coils  70 , the upper end of the vertical shaft  32  seesaws sideways about the shaft seat  23  as shown in FIG. 18 to perform a vibrating function. 
     As described above, in the present invention, a sounding signal or a vibrating signal is generated by electromagnetic force created by a magnetic field flowing through the voice coil  50  or the pair of vibrating coils  70  and a magnetic field of the magnet  30 , depending on a signal inputted into the driving control section. 
     Especially, in the respective embodiments described above, the signal inputted into the driving control section  90  is a current having a predetermined frequency, and is largely divided into a high frequency current for generating a sound wave and a low frequency current for generating a vibration. 
     Generally, the high frequency current for generating a sound wave has a frequency signal of about 2 kHz which is within an audible frequency band, and the low frequency current for generating a vibration has a frequency signal of about 500 Hz. 
     In other words, when currents having various frequencies from a low frequency to a high frequency are inputted into the voice coil  50  or the pair of vibrating coils  70 , when assuming that K is constant and m is mass, because an amplitude is represented as given in an equation described below:        Amplitude   =     1       1   -     f     (       1     2   ∏       ·     K   m       )                   where           f   (     natural                 frequency     )     =       (     1     2   ∏       )          (     K   m     )          1   2                       
     it is to be readily understood from FIG. 19 that a severe variation in amplitude is generated at 500 Hz in low frequency and a severe variation in amplitude is generated at 2kHz in high frequency. 
     However, since an audible frequency which can be heard by the human ear as a sound is generally no less than 2 kHz, at a frequency range where amplitude is increased in low frequency, it is impossible to hear a sound and it is only possible to feel a vibration. 
     Also, due to the fact that amplitude is gradually decreased while passing through 500 Hz and is increased again at 2 kHz which is a high frequency, because frequency in this situation is included in an audible frequency band as a sound wave which can be heard by the human ear is generated, a person can hear the sound wave as a sound. 
     On the other hand, natural frequencies of vibrating bodies which are vibrated in the respective embodiments of the present invention correspond to vibrating frequencies included in a frequency band where they vibrate. 
     As described above, by moving up and down or seesawing sideways a vibrating body with a simple structure depending on a frequency of an inputted current, the vibration apparatus of the present invention can perform a sounding function to play a preset melody or ring a bell and a vibrating function to vibrate a case of a communication device, as occasion arises. 
     Consequently, even without the provision of a separate vibrating motor in a communication device such as a portable phone, a beeper or the like, since a sounding function and a vibrating function can be performed by the vibration apparatus of the present invention, the number of components can be reduced and the communication device can be miniaturized. 
     Due to the fact that a component mounting space is decreased, miniaturization of the communication device can be promoted and marketability can be improved. Moreover, due to the fact that the number of components is reduced and manufacturing and assembling processes are simplified, manufacturing cost can be remarkably reduced. 
     In the drawings and specification, there have been disclosed typical preferred embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.