Patent Publication Number: US-2011062801-A1

Title: Linear vibrator

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Patent Application No. 10-2009-0086615, filed Sep. 14, 2009, entitled “Linear Vibrator”, which is hereby incorporated by reference in its entirety into this application. 
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to a linear vibrator. 
     2. Description of the Related Art 
     Generally, portable electronic devices, such as mobile phones, have a means for generating vibrations which is one of the critical characteristics of the devices. To provide this, in the conventional art, a vibration motor which generates vibrations in such a way as to rotate an eccentric shaft or a shaft misaligned from the center of gravity thereof has been used. 
     However, when the conventional vibration motor rotates, a brush passes through a gap between segments, so that friction and sparks occur with the result that many problems are induced, for example, the lifetime of the motor is reduced. 
     In an effort to overcome the above-mentioned disadvantages of the vibration motor, a linear motor was proposed. The linear motor is constructed such that a vibration unit coupled to a spring vibrates in the vertical or horizontal direction using electromagnetic force generated between a magnet and a coil. Thus, compared to the vibration motor, friction and abrasion between elements are reduced, thereby increasing the lifetime of the motor. Furthermore, the linear vibrator can be manufactured in a small size. Due to these advantages, various styles of linear vibrators are being developed. 
     However, in the case of the conventional linear vibrator, because of a complication of the structure of the linear vibrator according to the reduction in size thereof, an event in which a structure for connecting the linear vibrator to a portable electronic device is broken may be frequently caused. In other words, the structure for connecting the linear vibrator to the electronic device is complex, so that a power connection terminal may be easily snapped by force applied thereto when connecting the linear vibrator to the to electronic device. 
     If the power connection terminal is broken, the linear vibrator cannot be operated, of course. This markedly reduces the reliability of the product. 
     Therefore, to prevent the power connection terminal from snapping even though external tension is applied thereto, a method of improving the internal structure of the linear vibrator is required. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in an effort to provide a linear vibrator which can prevent the problem of the power connection terminal between the linear vibrator and an electronic device snapping. 
     In a linear vibrator according to an embodiment of the present invention, a casing defines an internal space therein. A vibration unit is provided in the casing. The vibration unit vibrates upwards and downwards. A bracket supports the casing and the vibration unit. A circuit board is provided on the bracket. The circuit board is made of elastic material. An electric circuit and a plurality of electronic devices are provided on the circuit board. A coil unit is mounted to a central portion of the circuit board in a perpendicular direction, so that power is applied from the circuit board to the coil unit. A lead wire extends from a lower end of the coil unit. The lead wire is electrically connected to the circuit board. A soldering part is formed on the circuit board to connect the lead wire to the circuit board. The soldering part is disposed at a position other than a position corresponding to a direction in which a tension is applied to the circuit board when power is applied to the coil unit. 
     Furthermore, an orientation of the soldering part based on a center of the circuit board may be angled by 180° to the direction in which the external tension is applied to the circuit board. 
     In addition, an orientation of the soldering part based on a center of the circuit board may be angled by from 90° to 180° to the direction in which the external tension is applied to the circuit board. 
     In the present invention, the orientation of a soldering part on which a lead wire of a coil unit is coupled to a circuit board by soldering is not aligned with the direction in which external tension is applied to the circuit board. Therefore, when the circuit board of the linear vibrator is assembled with an electronic device, even though external tension is applied to the circuit board, the snapping of the wire on the soldering part can be prevented. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and 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 sectional view of a linear vibrator, according to the present invention; 
         FIG. 2  is an exploded perspective view of the linear vibrator according to the present invention; 
         FIG. 3  is a partial enlarged view illustrating a first embodiment of the linear vibrator according to the present invention; and 
         FIG. 4  is a partial enlarged view illustrating a second embodiment of the linear vibrator according to the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference now should be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components. In the following description, when it is determined that the detailed description of the conventional function and conventional structure would confuse the gist of the present invention, such a description may be omitted. Furthermore, the terms and words used in the specification and claims are not necessarily limited to typical or dictionary meanings, but must be understood to indicate concepts selected by the inventor as the best method of illustrating the present invention, and must be interpreted as having had their meanings and concepts adapted to the scope and sprit of the present invention so that the technology of the present invention could be better understood. 
     Hereinafter, an embodiment of the present invention will be described in detail with reference to the attached drawings. 
     As shown in  FIGS. 1 through 4 , a linear vibrator  100  according to the present invention includes a stator  110  and a vibration unit  120 . The vibration unit  120  vibrates in a vertical direction using reciprocal action between magnetic force generated by a magnet  121  and electromagnetic force which is generated by a coil unit  120  at a predetermined frequency. 
     The stator  110  includes a casing  111 , a spring  112 , the coil unit  114  and a bracket  115 . The casing  111  defines an internal space of the linear vibrator  100  and covers elements of the linear vibrator  100 . The spring  112  is disposed in the casing  111  and mounted to the upper plate of the casing  111  to elastically support the vibration unit  120 . The coil unit  114  is coupled to the lower end of the vibration unit  120 . The bracket  115  supports the entire linear vibrator  100 . 
     The casing  111  covers the upper part and the side part of the linear vibrator  100  and thus protects the elements of the linear vibrator  100  from an external impact. 
     The spring  112  is an elastic member which is connected to the vibration unit  120  and induces vibrations of the vibration unit  120  in such a way that when a frequency is applied thereto, the maximum displacement occurs at a resonance point. The spring  112  is fastened at a circumferential upper end thereof to the inner surface of the upper plate of the casing  111  and fastened at a lower end thereof to the upper end of the vibration unit  120 , thus elastically supporting the vibration unit  120 . 
     Here, it is preferable that the spring  112  be a plate spring which can be varied in shape from a state in which the upper and lower ends of the spring are spaced apart from each other by a predetermined distance to a state in which they are in the same plane when the vibration unit  120  moves in the vertical direction. The spring  112  can be fastened to the upper plate of the casing  111  by bonding or using a separate fastening member which is forcibly fitted into the casing  111 . 
     The coil unit  114  is mounted to the lower end of the vibration unit  120 . The coil unit  114  generates a predetermined frequency and electromagnetic force in conjunction with the magnet  121 . 
     Furthermore, a circuit board  130  which is provided with a variety of electric devices and an electric circuit is provided under the lower end of the coil unit  114  to apply an electric signal to the coil unit  114 . 
     The circuit board  130  has a pattern which applies external power to the coil unit  114 . Preferably, the circuit board  130  is made of elastic material. 
     The bracket  115  which supports the entire linear vibrator  100  thereon is coupled to the lower surface of the circuit board  130 . 
     The bracket  115  is made of non-magnetic or low-magnetic material to prevent it from affecting a drive unit. The circuit board  130  which is connected to an input terminal is mounted on the bracket  115 . 
     The vibration unit  120  which vibrates in the vertical direction includes a magnet  121 , a yoke  122  which covers the magnet  121 , and a weight  123  which is fitted over the to circumferential outer surface of the yoke  122  and has a predetermined weight. 
     The yoke  122  has a circular shape which covers the upper surface and the sidewall of the magnet  121 . An annular rim is integrally provided on the lower edge of the yoke  122  to facilitate the seating of the weight  123  around the yoke  122 . In addition, a coupling part (not shown) protrudes from the upper surface of the yoke  122  so that the spring  112  is coupled to the yoke  122  through the coupling part. 
     The yoke  122 , along with the magnet  121 , forms a magnetic circuit and optimizes the magnetic flux of the magnet  121  which is linked to the coil unit  114 . Furthermore, the weight  123  is fitted over the yoke  122  and is seated onto the annular rim of the yoke  122 . Hereby, the weight  123  can be reliably coupled to the yoke  122 . 
     The weight  123  functions to increase vibrational force when the vibration unit  120  vibrates using reciprocal action generated between the magnet  121  and the coil unit  114  when a power signal is applied to the coil unit  114 . The weight  123  is seated onto the annular rim of the yoke  122  in a shape in which it surrounds the yoke  122 . 
     The weight  123  is preferably made of material having specific gravity higher than that of iron. The use of material having high specific gravity can increase the weight of the vibration unit  120  and leave the volume constant and thus control the resonance frequency for a certain weight of a vibrating body, thus maximizing the vibrational force of the vibrator. 
     The weight  123  is configured to be prevented from coming into contact with the coil unit  114 , thus preventing abrasion therebetween. Preferably, the weight  123  extends in the radial direction in a shape corresponding to that of the spring  112  to increase the weight thereof. Due to this, the weight of the vibration unit  120  can be maximized in the given volume such that the vibrational force of the vibrator can be maximized. 
     Meanwhile, as shown in  FIG. 3 , recently, according to the trend to reduce the size of the linear vibrator  100 , the assembly structure of the linear vibrator  100  is also to complicated, and the structure for connecting power between the linear vibrator  100  and a portable electronic device is also complicated. 
     Therefore, there may be a problem in that a connector for applying power to the linear vibrator  100  may snap under the force applied to the linear vibrator  100  when it is connected to the electronic device. This problem renders the linear vibrator  100  inoperative, thus causing the entire electronic device to malfunction. 
     The present invention provides a structure preventing the above-mentioned problem. In the linear vibrator  100  according to the present invention, the coil unit  114  is perpendicularly attached to the circuit board  130 . Furthermore, ends of lead wires  116  which extend from the lower end of the coil unit  114  are connected to the circuit board  130  by soldering. Hereby, soldering parts  117  are formed on the circuit board  130 . 
     The circuit board  130  has predetermined elasticity, so that when power is applied to the circuit board  130 , it is elastically extended in the direction (a) of  FIG. 3  in which the tension is applied thereto. 
     Here, to prevent the lead wires  116  from being cut off from the soldering parts  117 , the locations of the soldering parts  117  must be misaligned from the direction in which the tension is applied to the circuit board  130 . 
     Preferably, as shown in  FIG. 3 , the orientation of the soldering parts  117  based on the center of the circuit board  130  is angled by 180° to the direction (a) in which the external tension is applied to the circuit board  130 , thus preventing the external tension from affecting the soldering parts  117 . Furthermore, as shown in  FIG. 4 , the soldering parts  117  can be oriented in any direction based on the center of the circuit board  130 , so long as the soldering parts  117  are not aligned with the direction (a) of the external tension to prevent the soldering parts  117  from being directly affected by the external tension. 
     In other words, to minimize the force with which the external tension is applied to the soldering parts  117 , it is preferable that the soldering parts  117  be disposed at positions spaced apart from the direction (a) of the external tension by from 90° to 180° based on the center of the circuit board  130 . 
     As such, the orientation of the soldering parts  117  on which the lead wires  116  of the coil unit  114  are coupled to the circuit board  130  by soldering is not aligned with the direction (a) in which the external tension is applied to the circuit board  130 . Therefore, when the circuit board  130  of the linear vibrator  100  is assembled with the electronic device, even though external tension is applied to the circuit board  130 , the snapping of wires on the soldering parts  117  can be prevented. 
     Although the embodiments of the present invention have been disclosed for illustrative purposes, it will be appreciated that the linear vibrator of the invention is not limited thereto, and those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention. 
     Accordingly, any and all modifications, variations or equivalent arrangements should be considered to be within the scope of the invention, and the detailed scope of the invention will be disclosed by the accompanying claims.