A speaker includes a case, a dome, a diaphragm, a first voice coil, a second voice coil, a first pole plate, a second pole plate, a first magnet, a second magnet and a yoke. The case is supported on the frame to form a receiving room therebetween. The yoke includes a bottom portion and a side portion perpendicularly extending upward from the center of the bottom portion. A first magnetic gap is formed between the inner wall of the side portion and the outer wall of the magnet for receiving the first voice coil, and a second magnetic gap is formed between the outer wall of the side portion and the inner wall of the second magnet for receiving the second voice coil.
1. A micro-speaker comprising:
a frame;
a case supported on the frame and cooperatively with the frame defining a chamber therebetween;
a diaphragm received in the chamber and attached to the frame;
a yoke received in the chamber;
a magnet received in the chamber and attached on the top of the yoke;
a pole plate received in the chamber and attached to the top of the magnet;
a voice coil attached to a bottom of the diaphragm and surrounding the magnet and the pole plate;
a printed circuit board mounted on the bottom of the frame;
wherein the printed circuit board defines a pair of pads formed on the bottom thereof and electrically connecting with the corresponding terminals of the voice coil to apply electric current to the voice coil, and a pair of conductive points extending from a side of the corresponding pads and each facing to each other, when generated, static electricity will be activated to discharge from the conducting points by the corona discharge.
2. The micro-speaker as claimed in claim 1 , wherein the printed circuit board is oblong configuration and has an outer diameter substantially equal to an outer diameter of the frame.
3. The micro-speaker as claimed in claim 1 , wherein the conductive point is triangular and made of copper.
4. The micro-speaker as claimed in claim 1 , wherein the distance between the pair of the pads is bigger than 0.2 mm.
5. The micro-speaker as claimed in claim 1 , wherein the frame is approximately oblong bowl-shaped, and includes a base plate, an upper side plate extending upwardly and perpendicularly from an outer periphery of the base plate, a rectangular flange extending outwardly from an outer side of the upper side plate, and a low side plate extending downwardly and perpendicularly from a bottom portion of the base plate.
6. The micro-speaker as claimed in claim 5 , wherein the base and side plates cooperatively define a receiving space therebetween, and the base plate is elliptical for supporting the yoke thereon.
7. The micro-speaker as claimed in claim 6 , wherein the upper side plate defines a pair of through slots spanning an entire height thereof and formed adjacent to the flange, the two opposite terminals of the voice coil can extend through the pair of through slots to electrically connect to the printed circuit board located at the bottom of the base plate.
8. The micro-speaker as claimed in claim 7 , wherein the case is oblong configuration and covers the diaphragm, the case includes a first top wall and a first connecting portion extending outward from an outer periphery of the first top wall.
9. The micro-speaker as claimed in claim 8 , wherein the printed circuit board includes a second top wall, and a second connecting portion extending outward from an outer periphery of the second top wall and covering on the bottom of the flange of the frame, the second top wall is annular and planar, and defines an opening on a central area thereof for being passed through the low side plate.
10. The micro-speaker as claimed in claim 9 , wherein the magnet and the pole plate are elliptically cylindrical configuration.