Linear vibrator

1. A linear vibrator, comprising:

a stator including first and second coil blocks coupled to a lower casing;

a vibrator including a magnet disposed at a position corresponding to the first and second coil blocks;

a yoke plate placed over the magnet and supporting the magnet;

an elastic member elastically supporting the magnet; and

a circuit board installed at the lower casing, the first and second coil blocks and the circuit board being electrically connected to one another;

wherein an opening is formed through the lower casing to expose the circuit board, and a terminal of the circuit board is exposed through the opening;

wherein the yoke plate comprises first and second coupling plates that are coupled to first and second ends of the magnet, respectively;

wherein the elastic member comprises: a first elastic member, one distal end of the first elastic member being coupled to the first coupling plate and the other distal end of the first elastic member having a first contact portion formed at bottom of the other distal end, and the first contact portion contacting the lower casing; and a second elastic member, one distal end of the second elastic member being coupled to the second coupling plate and the other distal end of the second elastic member having a second contact portion formed at bottom of the other distal end, and the second contact portion contacting the lower casing;

wherein the magnet comprises a four-pole magnet alternately having four different magnetic poles, the four-pole magnet including first to fourth magnet portions wherein each magnet portion has a magnetic pole;

wherein the first coil block includes first and second coil portions that are disposed at positions corresponding to the first and second magnet portions, respectively, and the second coil block comprises third and fourth coil portions that are disposed at positions corresponding to the third and fourth magnet portions, respectively;

wherein each of the first, second, third, and fourth coil portions is configured to vertically align with its corresponding magnet portion without overlapping with any adjacent magnet portions; and

wherein a length of each of the first and second coil portions is configured to be two or more times as great as a width of the first coil block, and a length of each of the third and fourth coil portions is configured to be two or more times as great as a width of the second coil block, such that vibrations of connecting portions connecting the first and second coil portions and vibrations of connecting portions connecting the third and fourth coil portions are inhibited.

2. The linear vibrator as set forth in claim 1 , wherein the second coil portion of the first coil block and the third coil portion of the second coil block are adjacent to each other.

3. The linear vibrator as set forth in claim 2 , wherein current flows through the first and third coil portions in a first direction, and current flows through the second and fourth coil portions in a second direction that is opposite to the first direction.

4. The linear vibrator as set forth in claim 2 , wherein the first and third magnet portions have the same magnetic pole, and the second and fourth magnet portions have the same magnetic pole.

5. The linear vibrator as set forth in claim 1 , wherein the first coil block and the second coil block are electrically connected to each other in series.

6. The linear vibrator as set forth in claim 1 , wherein each of the first and second elastic members is formed by bending a band-shaped metal plate at least two times in a zigzag fashion, the metal plate having a shape of a rectangular parallelepiped having length that is greater than width.

7. The linear vibrator as set forth in claim 6 , wherein the metal plate bent in the zigzag fashion is bent at 180°.

8. The linear vibrator as set forth in claim 1 , wherein the first and second coil blocks are shaped like oblong pillars having oblong openings therein.

9. The linear vibrator as set forth in claim 8 , wherein the oblong openings of the first and second coil blocks are arranged to be parallel to each other, and the first and second coil blocks are arranged to be adjacent to each other.

10. The linear vibrator as set forth in claim 1 , wherein the casing comprises a lower casing in which the stator is disposed, and an upper casing which is combined with the lower casing to define a receiving space.

11. The linear vibrator as set forth in claim 8 , wherein each of the upper and lower casings is made by machining a metal plate.