Abstract: A backlight device includes a light source module having a plurality of light sources, a detecting circuit, a control unit, and a pulse width modulation (PWM) driving circuit. The detecting circuit is used for detecting the brightness of the light source module and generating a detecting signal to the control unit, such that the control unit outputs a control signal according to the detecting signal. In addition, the PWM driving circuit is used for generating a PWM signal for driving the light source module. In the present invention, the PWM driving circuit adjusts the base frequency of the PWM signal according to the control signal without adjusting the duty cycle of the PWM signal, so as to control the brightness of the light sources.

Abstract: A backlight device includes a light source module having a plurality of light sources, a detecting circuit, a control unit, and a pulse width modulation (PWM) driving circuit. The detecting circuit is used for detecting the brightness of the light source module and generating a detecting signal to the control unit, such that the control unit outputs a control signal according to the detecting signal. In addition, the PWM driving circuit is used for generating a PWM signal for driving the light source module. In the present invention, the PWM driving circuit adjusts the base frequency of the PWM signal according to the control signal without adjusting the duty cycle of the PWM signal, so as to control the brightness of the light sources.

Abstract: A ball bearing fixed assembly in a direct current fan comprises a fan blade unit, a motor unit, and a fan base. The fan blade unit has an integral fan blade, a spindle at the lower central position thereof, a motor casing at an inner side of the fan blade, and a magnet bar that are attached to an inner side of the casing. The motor unit has an insulation frame, silicon steel sheets, a circuit board and coils. The silicon steel sheets horizontally surround the insulation frame, the circuit board is disposed below the insulation frame, and the coils are perpendicular to the silicon steel sheets and mounted within the insulating frame. A ball bearing is installed in a central position within the fan base and fits with the spindle. An oil chamber is disposed below the ball bearing with a first receiving room and a second receiving room. The second receiving room is disposed above the first receiving room.