A micro-speaker includes a case having a ring wall forming a receiving cavity, a number of restricting apertures formed in the ring wall, a magnetic plate received in the case and having a main plate, a plurality of auxiliary plates extending from the main plate, and a number of protrusions extending from edges of the auxiliary plates, a first gap formed between two adjacent auxiliary plates communicating with the receiving cavity of the case, the main plate and the auxiliary plates being surrounded by the ring wall of the case, and the protrusions being located in the restricting apertures for restricting the magnetic plate in proper position.
1. A micro-speaker, comprising:
a case defining a ring wall forming a receiving cavity, the receiving cavity penetrating the case, the ring wall defining a plurality of restricting apertures therein, the restricting aperture being a through gap extending from the outer surface of the ring wall to the inner surface of the ring wall;
a plate-shaped magnetic plate including a main plate, a plurality of auxiliary plates extending from the main plate, and a plurality of protrusions extending from edges of the auxiliary plates in a radial direction of the auxiliary plate, the main plate and the auxiliary plates being surrounded by the ring wall of the case, and the protrusions being located in the restricting apertures for restricting the magnetic plate in proper position;
a first gap formed between two adjacent auxiliary plates communicating with the receiving cavity of the case.
2. The micro-speaker as described in claim 1 , wherein the magnetic plate further has a plurality of steps connecting the auxiliary plates and the protrusions.
3. The micro-speaker as described in claim 2 , wherein for each protrusion, two steps are provided connecting two sides of the protrusion to the corresponding auxiliary plate.
4. The speaker as described in claim 3 , wherein the ring wall has an inner surface, and the steps contact the inner surface of the ring wall.
5. The speaker as described in claim 2 , wherein a distance from any point at the most outer edge of step to a center point of the magnetic plate is greater than a distance from any point at the edge of auxiliary plate to the center point of the magnetic plate.
6. The speaker as described in claim 5 , wherein a distance from any point at the most outer edge of the protrusion to the center point of the magnetic plate is greater than a distance from the center point to the most outer edge of the step.
7. The speaker as described in claim 6 , wherein a second gap is formed between the inner surface of the ring wall and the steps.
8. The micro-speaker as described in claim 1 , wherein the magnetic plate further comprises a plurality of steps extending between the edges of the auxiliary plates and the ring wall, and the steps contact the inner wall of the case.
9. The micro-speaker as described in claim 8 , wherein each two adjacent auxiliary plates form a gap communicating with the receiving cavity, the gap defining a first recess and a second recess located on the main plate of the magnetic plate.
10. The micro-speaker as described in claim 9 , wherein the first recess between the ring wall and the edges of the auxiliary plates communicates with the second recess between two adjacent auxiliary plates, the second recess is communicating with the receiving cavity.
11. The micro-speaker as described in claim 8 , wherein a distance from a center point of the main plate to the ring wall is greater than a distance from the center point of the main plate to any point at the most outer edge of step.