Patent ID: 8416664
Filing Date: 2013-04-09
Classification: G11B

Abstract:
1. A driving circuit for a stepping motor configured to move an optical pickup in a radial direction of an optical disc, the optical pickup configured to emit a laser beam to the optical disc as well as receive the laser beam reflected by the optical disc, the driving circuit comprising: a control signal generating circuit configured to generate a plurality of control signals for supplying driving currents to driving coils having a plurality of phases of the stepping motor during energized periods, with a de-energized period therebetween during which no driving current is supplied; a plurality of output circuits configured to supply the driving currents to the respective driving coils having the plurality of phases, in response to the plurality of control signals; an induced voltage detecting circuit configured to detect an induced voltage by comparing, with a threshold voltage, a voltage generated in each of the driving coils having the plurality of phases, during the de-energized period; a threshold voltage setting circuit configured to set the threshold voltage; and a determining circuit configured to determine whether a collision state is present where the optical pickup reaches an end of a range of movement in a radial direction of the optical disc, based on a detection result of the induced voltage detecting circuit, the threshold voltage set at a voltage between a voltage generated in each of the driving coils having the plurality of phases during the de-energized period when a rotor of the stepping motor stops or rotates in the collision state, and a voltage generated in each of the driving coils having the plurality of phases in the de-energized period when no collision state is present.