| 摘要 |
PURPOSE:To increase the allowable range of an air gap magnetic flux density of a voice coil motor by controlling the gains of the first and second variable gain amplifiers in response to the air gap magnetic flux density of the magnetic circuit of the motor. CONSTITUTION:A terminal board 14 outputs gain control signals 5, 6 in response to the air gap magnetic flux density of a voice coil motor. The first variable gain amplifier 2 amplifies a servo controller 1 controlled in gain by the signals 5, 6, outputs a power amplifier 4 drive signals 3, a power amplifier inputs the signal 3 to supply a drive current to a voice coil 12. The second variable gain amplifier 9 is controlled in the gain by the signals 5, 6, a current detecting resistance voltage signal 19 generated from a current detecting resistor 11 connected in series with the coil 12 is amplified to output a current detection signal 13. |
