| 摘要 |
PROBLEM TO BE SOLVED: To suppress the occurrence of noises, according to the change of the weight of a curtain or length of a curtain rail, by annexing a control level adjuster, and controlling the calorific value of the main switch element to be roughly constant, according to the input condition of a motor. SOLUTION: The operating circuit 4a of a controller 4 outputs a control signal to control a PWM circuit for driving it at a specified speed, according to the operation speed of the motor M by the input of the detection signal from an operation speed detector 3. Moreover, the PWM circuit 4b receives the input of the drive signal from the operating circuit 4a, and output a pulse width control signal to the main switch Q1 through a control level adjuster 5. And, the control level controller 5 detects the input voltage of the motor controlled by the controller 4, and adjusts the control level of the controller 4 so as to make the calorific value of the main switch element Q1 roughly constant, according to the detection level. As a result, the noise generated from the switching power circuit can be reduced by increasing the quantity of noises absorbed as heat energy with a switching element when the load is small. |
