A coil includes a first section, a second section spaced from the first section, a third section and a forth section connecting ends of the first and second sections for forming a closed loop. The third section includes a first portion directly contacting to the first section, and a second portion extending from the first portion and directly connecting to the second section, the first portion forms a protrusion away from the fourth section.
1. A coil for a transducer generating sound, comprising:
a first section;
a second section spaced from the first section;
a third section connecting two ends of the first and second sections;
a fourth section connecting the other two ends of the first and second sections for forming a closed loop; wherein
the third section includes a first portion directly contacting to the first section, and a second portion extending from the first portion and directly connecting to the second section, the first portion forms a protrusion away from the fourth section;
the protrusion includes a first part substantially parallel to the forth section and a second part substantially perpendicular to the forth section.
2. The coil as described in claim 1 , wherein the second portion is substantially parallel to the forth section.
3. The coil as described in claim 2 , wherein a distance between the first part and the forth section is larger than a distance between the second portion and the forth section.
4. The coil as described in claim 1 , wherein the length of the first part is smaller than a half of the distance between the first section and the second section.
5. The coil as described in claim 1 , wherein the length of the first part is larger than a half of the distance between the first section and the second section.