Patent ID: 7864976
Filing Date: 2011-01-04
Classification: H04R,Y10T

Abstract:
1. A speaker comprising: a voice coil bobbin comprising: a nonmetallic pipe body as a base of the voice coil bobbin; a first nonmagnetic electric conductor film that is formed on an inner peripheral face of the pipe body; a second electric conductor film that is formed on an outer peripheral face of the pipe body such that the first electric conductor film is covered by the second electric conductor film through the pipe body; and a center pole; wherein an electrostatic capacity that is formed between the voice coil bobbin and the center pole is detected and outputted as an electrical signal, and wherein an inner side insulator film is formed on an inner peripheral face of the first electric conductor film, and an electrostatic capacity which is formed between the first electric conductor film and the center pole is detected, and an outer side insulator film is formed on an outer peripheral face on the second electric conductor film, and a coil is wound around an outer peripheral face of the outer side insulator film to structure the voice coil bobbin.