Patent Publication Number: US-2011068641-A1

Title: Horizontal linear vibrator

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority of Korean Patent Application No. 10-2009-0090626 filed on Sep. 24, 2009, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a horizontal linear vibrator and, more particularly, to a horizontal linear vibrator designed to be mounted on a personal mobile terminal to vibrate. 
     2. Description of the Related Art 
     In general, one of the key functions requisite for communication devices is a call reception function. Commonly used call reception functions include a sound generating function that generates a melody or a bell sound and a vibration function that transfers vibrations to a device. 
     Among the functions, the vibration function is commonly used so as not to interfere with others by preventing a melody or a bell sound from being transferred to the exterior through a speaker. 
     In order to implement such a vibration function, in general, a small vibration motor is driven to transfer a driving force to a case of a device to make the device vibrate. 
     In particular, recently, as mobile terminals have been reduced in size and have improved in quality, the use of a touch screen type display device has been greatly favored, requiring a vibration generation function when a touch is applied to the touch screen, so the improvement of the vibration motor has gradually taken place. 
     A vibration motor applied to mobile phones generates rotatory power in order to rotate a rotational part of an unbalance mass, thus obtaining mechanical vibrations, and in this case, rotatory power is generated such that it is mostly subjected to a rectifying action through a brush and a contact point of a commutator (or rectifier) to provide current to a rotor coil. 
     However, in the brush type structure using a commutator, when the motor rotates, the brush passes through the gap between segments of the commutator, generating a mechanical friction and an electrical spark, abrading the brush and the commutator and thereby shortening the life span of the motor. 
     In addition, because voltage is applied to the motor by using a moment of inertia, time is taken to reach a target amount of vibrations, so it is difficult to implement vibrations suitable for touch screen-employed personal mobile terminals and the like. 
     SUMMARY OF THE INVENTION 
     An aspect of the present invention provides a horizontal linear vibrator which vibrates horizontally in a lengthwise direction of a personal mobile terminal and can be simply assembled. 
     According to an aspect of the present invention, there is provided a horizontal linear vibrator including: a bracket having a coil part with a hollow; a vibration unit including a yoke part having an accommodation space for accommodating the coil part therein and a passage hole formed to pass through the accommodation space; and a magnetic field unit including a magnet disposed in the accommodation space through the passage hole and providing an electromagnetic force to allow the vibration unit to horizontally move by an interaction of the coil part and the magnet. 
     The passage hole may have a circular shape, and the magnet may have a cylindrical shape corresponding to the passage hole. 
     An insertion hole may be formed on an outer surface of the bracket such that it is positioned in a straight line with the passage hole. 
     The magnets may be formed at both sides of a magnetic core such that their polarities face each other. 
     The vibration unit may include the yoke part accommodating the magnetic field unit therein, and the yoke part may include an extending part extending to be bent so as to be tightly attached to outer surfaces of a mass body. 
     A bobbin may be formed at an upper portion of the bracket such that the coil part is inserted therein. 
     The coil part may have a quadrangular shape. 
     A circuit board may be installed on the upper portion of the bracket and connected with an external input terminal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view for explaining a horizontal linear vibrator according to an exemplary embodiment of the present invention; 
         FIG. 2  is an exploded perspective view of the horizontal linear vibrator of  FIG. 1 ; and 
         FIGS. 3 to 5  are perspective views for explaining the process of assembling the horizontal linear vibrator and an effect of the horizontal linear vibrator according to an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The invention 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 invention to those skilled in the art. 
     In the drawings, the shapes and dimensions may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like components. 
     A horizontal linear vibrator according to exemplary embodiments of the present invention will now be described in detail with reference to  FIGS. 1 to 5 . 
       FIG. 1  is a perspective view for explaining a horizontal linear vibrator according to an exemplary embodiment of the present invention, and  FIG. 2  is an exploded perspective view of the horizontal linear vibrator of  FIG. 1 . 
     With reference to  FIGS. 1 and 2 , a horizontal linear vibrator  100  may include a bracket  110 , a vibration unit  120 , a magnetic field unit  130 , and a cover unit  140 . 
     The bracket  110  has a structure in which an upper portion and a lengthwise directional side portion of the bracket  110  are open to correspond to the cover unit  140 . Namely, the bracket  110  is formed to have a bracket lower plate  112  and widthwise directional side portions  114  and assembled with the cover unit  140  to form an internal space. 
     A bobbin  150  may be formed on an upper portion of the bracket lower plate  112  in order to insertedly fix a cylindrical coil  134 , and a circuit board  170  may be mounted to be positioned near the bobbin  150 . 
     The side portions  114  are formed to be bent to be perpendicular to the bracket lower plate  112  to allow spring members  180  to be insertedly fixed to an inner circumferential surface of the side portions  114 . Thus, as the both sides of the bracket  110  are bent to be perpendicular to the bracket lower plate  112 , having a channel-like shape, but the shape of the bracket  110  is not limited thereto. 
     An insertion hole  116  may be formed at a position of the side portion, of the bracket  110 , corresponding to the passage hole  125   b  formed at the yoke part  124 . In this case, the size of the insertion hole  116  may correspond to the size of the magnet  132 , and accordingly, the magnet  132  can be assembled by passing through the insertion hole  116  and the passage hole  125   b.    
     The bobbin  150  is positioned at the center of the upper portion of the bracket lower plate  112  and may include a vertical plate part  152  bent to be vertical to the bracket lower plate  112  and a cylindrical part  154  extending from the vertical plate part  152  such that it is horizontal to the bracket lower plate  112 . 
     The vertical plate part  152  and the cylindrical part  154  may have a hollow portion through which a magnet  132  moves reciprocally. 
     Here, a cylindrical coil  134  is insertedly fixed on an outer circumferential surface of the bobbin  150 , and the bobbin  150  has the cylindrical shape with a hollow portion therein allowing the magnet  132  to make a reciprocal movement therethrough. However, the structure of the bobbin  150  is not limited thereto, and the structure may be omitted. 
     The circuit board  170  is connected with an external input terminal and transfers power applied thereto to the cylindrical coil  134 . The circuit board  170  may include a pattern part  172  formed on its upper surface and an opening part formed therein to allow the bobbin  150  to pass therethrough. 
     However, the circuit board  170  is not limited to the configuration in which it is formed separately from the bracket  110 . Namely, the circuit board  170  and the bracket  110  may be integrally formed according to a designer&#39;s intention. 
     The coil part may include the cylindrical coil  134 . The cylindrical coil  134  serves to generate an electric field of a certain strength when power is applied thereto from an external source. The cylindrical coil  134  may be inserted onto the outer circumferential surface of the cylindrical part  154  of the bobbin  150 . 
     A coil line of the cylindrical coil  134  is connected with the pattern part  172  of the circuit board  170  through soldering, whereby power can be applied to the cylindrical coil  134  from an external source. However, the coil part is not limited to the cylindrical shape, and a rectangular coil may be applicable. 
     The vibration unit  120  includes the yoke part  124  accommodating both the cylindrical coil  134  and the magnet  132  therein, and a mass body  126  accommodating the magnet  132  and the yoke part  124 . The vibration unit  120  moves in a horizontal vibration direction by an interaction of the magnet  132  and the cylindrical coil  134 . 
     The magnetic field unit  130  includes the cylindrical coil  132  accommodated within the bobbin  150  and the magnet  132  disposed to be adjacent to the cylindrical coil  134 . 
     A vibration direction of the vibration unit  120  is determined according to the Lorentz Force by an electric force of the frequency generated from the cylindrical coil  134  and the direction of a magnetic field generated toward the yoke part  124  from the magnet  132 . 
     The magnet  132  serves to force the vibration unit to move linearly according to its interaction with the cylindrical coil  134  by generating a magnetic field of a certain strength. The magnets  132  are attached to both sides of a magnetic core  133 . 
     Here, the magnets  132  attached to both sides of the magnetic core  133  may be disposed such that the same polarities face each other. 
     In this case, a magnetic fluid may be coated on an outer circumferential surface of the magnet  132  in order to prevent the magnet  132  from being directly brought into contact with an inner circumferential surface of the cylindrical part  154  of the bobbin  150  when the mass body  126  vibrates horizontally. 
     Here, the magnetic fluid is obtained by stably dispersing magnetic powder in a colloid shape in a liquid and then adding a surfactant thereto to prevent the magnetic powder from being precipitated or coagulated due to gravitation or a magnetic field. For example, the magnetic fluid may include a magnetic fluid obtained by dispersing triiron tetroxide or iron-cobalt alloy molecules in oil or water and, recently, a magnetic fluid obtained by dispersing cobalt in toluene. 
     The magnetic powder is ultrafine particles having a size of 0.01 μm to 0.02 μm, has Brownian motion peculiar to ultrafine particles, and has the characteristics that the concentration of the magnetic powder particles in the fluid is uniformly maintained even when an external magnetic field, gravitation, centrifugal force, or the like, is applied thereto. 
     The yoke part  124  serves to self-close a circuit to smoothly form a magnetic flux of the magnet  132 . The yoke part  124  may have an internal space in which the cylindrical coil  134  and the magnet  132  are accommodated. 
     In order to have the internal space, side walls having a size enough to accommodate the magnet  132  and the bobbin  150 . The passage hole  125   b  may be formed on the side wall to allow the magnet  132  to be inserted therethrough. 
     Both sides of the yoke part  124  may include extending parts  125  bent so as to be positioned perpendicular to the bracket lower plate  112  and tightly attached to the outer side of the mass body. Thus, when a central portion of the yoke part  124  is accommodated in the accommodation space of the mass body  126 , the extending parts  125  can be tightly attached to the outer side of the mass body  126 , and thus, the mass body  126  and the extending parts  126  can be stably bound. 
     The mass body  126  serves to apply a certain mass to the vibration unit  120  for linear vibrations, and includes an accommodation space to accommodate the central portion of the yoke part  124  therein. Thus, the mass body  126  accommodates the central portion of the yoke part  124  accommodating the magnet  132  in its accommodating space, and assembled such that the extending parts  125  bent from the yoke part  124  are in contact with the outer sides of the mass body  126 . 
     The mass body  126  may have a mass of a certain size and vibrates horizontally in a vibration direction according to an interaction of the magnet  132  and the cylindrical coil  134 . Here, the vibration direction refers to a direction parallel to the cylindrical coil  134 . 
     The spring members  180  serve to elastically support the vibration unit  120  to move horizontally in a linear direction. In a state in which one side of the spring members  180  are fixed to the widthwise directional side portions  114 , the other side of the spring member  180  is fixed to the vibration unit  120 , thus elastically supporting the vibration unit  120 . 
     Here, the spring members  180  are provided as pairs in corresponding positions at both sides of the vibration unit  120 , and disposed at an upper portion of the bracket  110 . The spring member  180  may be, for example, a coil spring, a leaf spring, or the like. 
     The cover unit  140  is formed to cover the upper portion of the bracket  110  and protects the internal constituents against an external impact. 
     In this manner, the horizontal linear vibrator according to the present exemplary embodiment is mounted in a personal mobile terminal such that it vibrates horizontally in a lengthwise direction, of the personal mobile terminal, rather than in a thicknesswise direction, so the thickness of the personal mobile terminal can be reduced. Also, because the movement displacement of the vibration unit  120  is formed to be lengthy along the lengthwise direction of the personal mobile terminal to secure the movement displacement, vibration performance can be further improved. 
       FIGS. 3 to 5  are perspective views for explaining the process of assembling the horizontal linear vibrator and an effect of the horizontal linear vibrator according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 3 , the circuit board  170  is attached to the upper portion of the bracket  110 . Here, the circuit board  170  is connected with an external input terminal to transfer power applied thereto to the cylindrical coil  134 . 
     The cylindrical coil  134  may be disposed to surround the bobbin  150 , and, according to this configuration, an empty space may be provided at the center of the bobbin  150  and the cylindrical coil  134 , and the magnet  132  may be mounted in the empty space. 
     As shown in  FIG. 4 , the yoke part  124  is disposed to accommodate the cylindrical coil  134  on an inner surface of the bracket  110 . 
     Here, the passage hole  125   b  may be formed on the side wall of the yoke part  124  accommodating the magnet  132  and the bobbin  150 . 
     In this case, the insertion hole  116  may be formed at the position of the side portion, of the bracket  110 , corresponding to the passage hole  125   b  formed at the yoke part  124 . In this case, the passage hole  125   b  and the insertion hole  116  are positioned on the straight line. 
     Accordingly, as shown in  FIGS. 4 and 5 , the magnet  132  attached to both sides of the magnetic core  133  passes through the insertion hole  116  and the passage hole  125   b  so as to be disposed in the hollow of the cylindrical coil  134 . The magnet  132  generates a magnetic field of a certain strength to allow the vibration to linearly move according to its interaction with the cylindrical coil  134 . 
     As set forth above, according to exemplary embodiments of the invention, because the horizontal linear vibrator is mounted in a personal mobile terminal such that it vibrates in a horizontal direction, namely, in a lengthwise direction, rather than in a thicknesswise direction, of the personal mobile terminal, the personal mobile terminal can become slimmer. Also, because the movement displacement of the vibration unit is lengthy along the lengthwise direction of the personal mobile terminal to secure the movement displacement of the vibration unit, the vibration performance can be improved. 
     In addition, because the horizontal linear vibrator includes the yoke part having the passage hole passing through the accommodation space accommodating the coil part and the bracket having an insertion hole corresponding to the passage hole, after the bracket is assembled to the yoke part, a magnet can be easily inserted from the exterior, thus facilitating the assembling process. 
     While the present invention has been shown and described in connection with the exemplary embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.