Frishauf, Holtz, Goodman & Woodward
Linear DC motor driving device
 A driving device for a multipolar type linear DC motor using a PWM (pulse width modulation) driving signal for driving a linear DC motor by causing an excitation coil of the motor, placed in alternating fields, to generate an induction field, and switching polarities of the induction field. The device includes a magnet polarity detecting circuit for detecting a direction of a magnetic field acting on the excitation coil in the alternating fields, an electric filter for removing an output signal output from the magnet polarity detecting circuit and having the same period as a PWM drive period, and polarity switching control circuit for controlling a direction and generation time of an induction field generated by the excitation coil in accordance with an output signal from the magnet polarity detecting circuit. 
Olympus Optical Co., Ltd.
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Hajime Yoshihiro Mitsuhiko
Takahashi Shimada Saito