Patent ID: 8687838

Claim:
A speaker unit comprising: a carbonaceous acoustic vibration plate; a voice coil made up of a cylindrically wound conductive wire, one open end portion of which is fixed in direct contact with the carbonaceous acoustic vibration plate; magnetic flux generating section configured to generate a magnetic flux that penetrates the cylindrical voice coil in a diameter direction; and drive section configured to supply a drive current corresponding to an audio signal to the voice coil, wherein the voice coil is made up of a plurality of unit voice coils corresponding to the number of bits of the digital signal configured by making the plurality of unit voice coils have different diameters and sequentially inserting the unit voice coils such that a unit voice coil of a smaller diameter is inserted into a unit voice coil of a greater diameter, and the drive section individually drives the each unit voice coil based on each bit value of the digital signal.