| 摘要 |
PROBLEM TO BE SOLVED: To provide a device for detecting a rotational state of a DC motor which can maintain position detection accuracy for a movable member driven by the DC motor even in special regions consisting of a starting state and a locking state of the DC motor by determining an accurate rotational state in the special regions.SOLUTION: In a device 2 for detecting a rotational state of a DC motor which has a current detection section (shunt resistance 43) for detecting an armature current Im of a DC motor 3, a filter section 44 for determining a ripple waveform Wrpl and a ripple detection section 7 for detecting a current ripple, the ripple detection section 7 includes: ripple amplitude determination means 71 for determining that there is a current ripple at the timing of a change in the ripple waveform Wrpl by an amplitude threshold; rotational state determination means 72 for determining a rotational state in which the armature current Im is substantially settled at a steady state value as a steady state region, and determining a rotational state in which the armature current is changing as a special region; and threshold setting means 73 for setting a steady state amplitude threshold and a special amplitude threshold used by the ripple amplitude determination means 71. |
