Patent ID: 8721096
Filing Date: 2014-05-13
Classification: G09G

Abstract:
1. A backlight unit of an LCD device that receives video data, comprising: a printed circuit board (PCB) substrate facing a rear surface of an LCD panel and extending along the rear surface of the LCD panel; a plurality of first light source units including a plurality of red, green and blue LEDs; a plurality of second light source units corresponding to the plurality of first light source units and including a plurality of white LEDs, wherein the plurality of the first light source units and the plurality of the second light source units are positioned alternately on the PCB substrate, wherein the plurality of red, green, blue and white LEDs being divided into a plurality of blocks, wherein each block includes red, green, blue and white LEDs, wherein the red, green and blue LEDs evenly spread across the PCB substrate to form an array of LEDs including a plurality of rows and columns; a control unit that outputs a first control signal to the first light source units and a second control signal to the second light source units based upon a luminance signal, wherein the control unit detects the luminance signal by analyzing inputted video data from a video system by each block, and the control unit includes a histogram analyzing unit that analyzes the luminance of white light emitted from the first light source units in accordance with a histogram containing luminance values for each gray scale of a video frame to obtain an analyzed luminance; a first light source driving unit that drives the first light source units according to the first control signal; and a second light source driving unit that drives the second light source units by each block according to the second control signal; wherein the second light source driving unit selectively drives the white LEDs of a corresponding block so that the white LEDs of the corresponding blocks are turned on in case where the detected luminance signal of the corresponding block is below a predetermined reference value, thereby a white light emitted from the white LEDs in the corresponding block is mixed with a white light emitted from the first light source units in the corresponding block to improve entire luminance of the white light and to achieve a uniform white light in the entire backlight unit; wherein the white LEDs emit the white light after a white light is emitted from the first light source units and after luminance of the white light emitted from the first light source units is analyzed; wherein the video frame is divided into three sub-frames of red, green and blue; wherein the first light source driving unit turns on the first light source units during a liquid crystal response block when the video data is provided to and maintained in a liquid crystal cell in each sub-frame by the control signal of the first light source unit; wherein the control unit detects the luminance signals by analyzing the video data; wherein the control unit comprises a luminance and color division unit and a histogram analyzing unit, the luminance and color division unit divides the video data into luminance element and chromatic elements.