ROTATION-DETECTION UNIT AND ROTATION-CONTROL UNIT FOR DC MOTOR

Japanese Patent JP3776683

B2

PROBLEM TO BE SOLVED: To exactly detect a rotational speed of every rotational direction and the number of revolutions of a brush-type DC motor with a simple and spaceless configuration, and to effectively control the rotation. SOLUTION: A DC motor M1 comprises electrode brushes B11 and B12, and rotation-detection brushes BD1a and BD1b. Noise-elimination circuits 1a and 1b eliminate a noise component of a rotation-detection signal of each rotation-detection brush BD1a and BD1b. One of rotation-detection signal outputs of the noise-elimination circuits 1a and 1b that directs to a rotational direction is selected by a rotation-detection signal-selection means 4 and fed to a comparator 3. A comparison-reference voltage-generation means 2 generates a comparison-reference voltage, and feeds it to the comparator 3. The comparator 3 compares the rotation-detection signal that is selected by a rotation-detection signal-selection means 4 and the comparison reference voltage that is generated by the comparison-reference voltage-generation means 2. And thereby, a pulse train having a pulse cycle and a pulse width that correspond to the rotational speed is output.