| 摘要 |
PROBLEM TO BE SOLVED: To provide a speed detector capable of detecting an accurate speed even when a duty imbalance and a phase error exist in a bi-phase pulse of an encoder, and responding to a present motor control device by only replacing the speed detector. SOLUTION: The speed detector includes a state determining means for determining four states from an A-phase state, a B-phase state, and output of a code detecting circuit, and four means for storing a time between pulses corresponding to each of the states, calculates a reference value of the time between the pluses by measuring the time between the pulses of the output pulse of a quadrupling circuit and housing in the four means for storing a time between pulses, calculates a time correcting value by comparing data housed in the four means for storing a time between pulses, and corrects the value of a timer storing means 2.
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