Abstract: An exemplary light emitting diode illumination device powered by a liquid crystal display device (20) includes a light emitting diode light source (21) and a supporting member (23). The light emitting diode light source receives electrical power from the liquid crystal display device (22). The light emitting diode light source is connected to the liquid crystal display device via the supporting member. Because a power supply circuit of the liquid crystal display device has an electromagnetic interference filter function, a positive feedback function, and a negative feedback function, the brightness of the light emitting diode illumination device powered by a liquid crystal display device is steady.

Abstract: An exemplary printed circuit board (2) includes a substrate (21) and a printed circuit (20) formed on the substrate. The printed circuit includes a first input wire (210) and a ground wire (230). The first input wire includes at least one tip and the ground wire includes at least one tip facing the at least one tip of the first input wire. Each of the tips of the first input wire and the ground wire defines a pointed end.

Abstract: An exemplary backlight control circuit (200) includes a DC power supply (VDD), a load circuit (210), an input circuit (230), and a PWM IC (250). The load circuit includes two light sources (2113, 2114) and a rectifier and filter circuit (213). The input circuit includes a diode (231) and a capacitor (237). The PWM IC includes a current sampling pin (251) and an overvoltage protection pin (253). A low voltage terminal of a first one of the two light sources is connected to the current sampling pin via the rectifier and filter circuit, and a low voltage terminal of a second one of the two light sources is connected to a cathode of the diode. An anode of the diode is connected to the DC power supply and grounded via the capacitor. The overvoltage protection pin is connected to the DC power supply.

Abstract: An exemplary backlight driving circuit (20) a first power supply (260); a second power supply (270); a signal output terminal (280); an AND gate (210); a follower (220); a capacitor (290); a reverser (230); a first transistor (240), which is a N-Channel mode metal-oxide-semiconductor field-effect transistor (N-MOSFET), having a gate electrode connected to an output end of the AND gate through the follower, a source electrode connected to the signal output terminal, a drain electrode connected to the first power supply; and a second transistor (250), which is a N-Channel mode metal-oxide-semiconductor field-effect transistor (N-MOSFET), having a gate electrode connected to the output end of the AND gate through the reverser, a source electrode connected to the ground, a drain electrode connected to the signal output terminal.

Abstract: An exemplary backlight driving circuit (20) includes a first pulse generator (230), a second pulse generator (240), a transformer (250) having a primary winding (251), a first transistor (210), a second transistor (220), and a first capacitor (290). The first transistor is a P-MOSFET. The first transistor includes a gate electrode (211) connected to the first pulse generator, and a drain electrode (213) connected to a first terminal (252) of the primary winding. The second transistor is an N-MOSFET. The second transistor includes a gate electrode (221) connected to the second pulse generator, a source electrode (222) connected to ground, and a drain electrode (223) connected to the first terminal of the primary winding. The first capacitor includes one terminal connected to a second terminal of the primary winding.

Abstract: An exemplary backlight modulation circuit (200) includes a pulse generator circuit (210) configured for generating a first square pulse; a voltage division circuit (230) configured for receiving the first square pulse and generating a second square pulse according to the first square pulse; an oscillator circuit (240) configured for generating a reference voltage; and an amplifier (200) comprising a negative input configured for receiving the second square pulse from the voltage division circuit, and a positive input configured for receiving the reference voltage from the oscillator circuit as a reference pulse signal, the amplifier being configured for generating a backlight adjusting signal according to the reference pulse signal and the second square pulse.

Abstract: An exemplary backlight control circuit (20) includes at least two sampling circuits (21), at least two feedback circuits (22), and a PWM IC (23). Each of the sampling circuits includes a sampling output (210) and a backlight lamp (211). The PWM IC includes a current sense pin (230). The at least two feedback circuits correspond to the at least two sampling circuits, respectively. Each of the feedback circuits includes a resistor (222) and a diode (223) electrically coupled in parallel. The sampling output is configured to output a first voltage when the backlight lamp is in a normal working state, and output a second voltage when the backlight lamp has an open circuit. One terminal of the diode is electrically coupled to the sampling output of a corresponding one of the sampling circuits, and an opposite terminal of the diode is electrically coupled to the current sense pin.