Lg Display Co., Ltd.

Seongho Lim

Taewoo Kim

EungKyu Kim

A liquid crystal display (LCD) device having an LCD panel with a plurality of pixels is disclosed. The LCD device includes gate and data driving circuits to provide a gate pulse and a data voltage to the pixels, respectively, and a timing controller to control the gate and data driving circuits. The LCD device also includes a backlight unit to provide light to the liquid crystal panel. The backlight unit includes a light source having at least one LED channel, a driving voltage generator to supply a driving voltage to the LED channel, and an LED driver to supply a conditional pulse width and amplitude modulation (CPWAM) signal to the LED channel. The CPWAM signal has a pulse with an amplitude and a width that are both variable from one period of a predetermined length to another period of the predetermined length.

Backlight unit and liquid crystal display using the same

An apparatus for controlling the constant current for multi-channel LEDs includes: a plurality of LED channels each comprising an LED array, a transistor, and a variable emitter resistor; a feedback sensing circuit for sensing the collector or drain voltage of a transistor of each of the LED channels; and a controller for increasing the variable emitter resistance of an LED channel in which the collector voltage of the transistor is higher than those of the other LED channels, in response to a feedback sensing result input from the feedback sensing circuit.

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Seoul, South Korea

Seongho Lim