METHOD FOR REDUCING SWITCHING NOISE AND HARMONIC NOISE OF BL DC MOTOR FOR USE OF OPTICAL DEVICE

摘要

PURPOSE: A method for reducing switching and harmonic noise is provided to improve performance and reliability of optical device by changing the location of hall element. CONSTITUTION: A method is characterized in that a plurality of hall elements(20) which are mounted at the center point between two motor slots(3) and sense switching of a DC motor are moved in left or right direction from the center point in such a manner that the cogging torque point of the DC motor and the electromagnetic switching point are not correspond, to thereby prevent switching and harmonic noise of the DC motor. The DC motor includes a rotor magnet having number of poles of 6, 12, 16 or 20 and number of motor slots of 9 or 12. The hall element is mounted among three phases of one motor slot from among three-phase(U,V,W) motor slots having identical phases in diagonal direction.