Patent ID: 8165336
Filing Date: 2012-04-24
Classification: H04R

Abstract:
1. A voice coil comprising: a cylindrical bobbin formed of a first material; a coil which surrounds on an outer circumferential surface of the bobbin; and a plurality of reinforcement members formed of a material having a vibration propagation speed faster than the first material and provided on the outer circumferential surface of the cylindrical bobbin, wherein the reinforcement members are strip-shaped and are provided apart from each other on the outer circumferential surface of the cylindrical bobbin, each of the reinforcement members is aligned in a direction substantially perpendicular to a winding direction of the coil, and a ratio of a total of widths of the reinforcement members against a width of the cylindrical bobbin is set from 1/15 to ⅓, or wherein the reinforcement members are strip-shaped and are provided apart from each other on an area of the outer circumferential surface of the cylindrical bobbin other than an area on which the coil is wound, each of the reinforcement members is aligned in a same direction as a winding direction of the coil, and a ratio of a total of widths of the reinforcement members against a height of the cylindrical bobbin is set from 1/10 to ⅔.