| 摘要 |
PROBLEM TO BE SOLVED: To suppress vibration caused by the output of a burushless fan motor drive circuit during operation of a brushless fan motor, without effects by a change in temperature and prevent noise caused by vibration from coming out from a case, etc., in which the fan motor is housed, in the brushless fan motor drive circuit which detects the position of a rotor by means of a Hall element and then switches the polarity of current in a coil. SOLUTION: A Hall element 4 is connected to a DC power supply, through a current controlling resistor (R1 ) 2 and a division resistor (R2 ) 3 is connected in parallel to the Hall element 4. A resistance value of the division resistor (R2 ) 3 is set considerably smaller than the impedance of the Hall element 4. By making the ratio of current allowed to flow in the division resistor (R2 ) 3 large, the Hall element 4 can be operated nearly at the constant voltage. By this method, the drive output becomes large, and the gradients in the rise and fall become gentle and therefore, the vibration at the time of switching the polarity can be controlled to be small, compared with the conventional method. |
