A speaker includes a magnetic circuit 1 that is formed in the center of a frame 5 , a voice coil 6 that is inserted in a magnetic gap of the magnetic circuit 1 , a damper 7 that is fixed to the frame 5 and the voice coil 6 , and a vibrating plate 8 that is fixed to the frame 5 and the voice coil 6 . An opening 10 is provided in a bobbin 12 of the voice coil 6 . The area of the opening 10 is 0.3% or less of the radial cross-sectional area of the bobbin 12 of the voice coil 6.
1. A speaker comprising:
a frame;
a magnetic circuit that is formed in a radial center of the frame and has a magnetic gap;
a voice coil that is inserted in the magnetic gap of the magnetic circuit, the voice coil including a bobbin having a radial cross-sectional area;
a damper that is fixed to the frame and the voice coil; and
a vibrating plate that is fixed to the frame and the voice coil;
wherein an opening is provided in the bobbin of the voice coil;
wherein the opening has an area equal to 0.3% or less of a radial cross-sectional area of the bobbin of the voice coil;
wherein a joint is formed between a top of a coil part of the voice coil and the bobbin;
wherein a clearance gap is formed at the joint between the top of the coil part of the voice coil and the bobbin; and
wherein the clearance gap is blocked by a coating material.
2. The speaker of claim 1 , wherein the damper is adhered to the voice coil by a damper adhered portion, and the opening of the bobbin is formed between a top of a coil part of the voice coil and a bottom of the damper adhered portion.
3. The speaker of claim 2 , wherein the area of the opening is equal to 0.3% or less, and 0.05% or more, of the radial cross-sectional area of the bobbin of the voice coil.
4. The speaker of claim 1 , wherein the area of the opening is equal to 0.3% or less, and 0.05% or more, of the radial cross-sectional area of the bobbin of the voice coil.
5. The speaker of claim 4 , wherein
the opening is formed through a sidewall of the bobbin.
6. The speaker of claim 4 , wherein
the bobbin of the voice coil has a cylindrical sidewall such that the radial cross-sectional area of the bobbin of the voice coil is circular; and
the opening is formed through the cylindrical sidewall of the bobbin.
7. The speaker of claim 1 , wherein
the opening is formed through a sidewall of the bobbin.
8. The speaker of claim 1 , wherein
the bobbin of the voice coil has a cylindrical sidewall such that the radial cross-sectional area of the bobbin of the voice coil is circular; and
the opening is formed through the cylindrical sidewall of the bobbin.