Liquid crystal display
View Patent ↗The present invention relates to a method of controlling luminance of a backlight based on a processed image data after receiving information of image data, in order to improve the visibility of moving picture. An inverter according to the present invention includes a first block generating a first luminance control signal with an analog value depending on the luminance control signal with a duty ratio depending on a synchronization signal. The luminance control signals generated by the respective blocks are synthesized luminance control signal. Accordingly, a liquid crystal display employing two backlight control methods can be provided. Thus, it is possible to remove the drag phenomenon of a screen and, at the same time, to improve the visibility for moving picture.
1. A liquid crystal display comprising:
a liquid crystal panel assembly including a plurality of gate lines, a plurality of data lines crossing the gate lines, and a plurality of pixels formed at crossing points of the gate lines and the data lines;
a signal controller receiving image data and a synchronization signal from an external graphic source, generating a control signal for driving the liquid crystal panel assembly, and converting format of the image data;
a voltage generator generating gray voltages and gate voltages for driving the liquid crystal panel assembly;
a gate driver sequentially scanning the gate lines of the liquid crystal panel assembly by unit of horizontal scan period based on the gate voltages;
a data driver selecting the gray voltages corresponding to the image data from the signal controller for respective data lines on the liquid crystal panel assembly;
an inverter generating a first luminance control signal having an analog value depending on luminance distribution of the image data and a second luminance signal having a pulse duty ratio determined by multiples of a frame frequency, synthesizing the first luminance control signal and the second luminance control signal, and generating a lamp driving signal based on the synthesized signal; and
a lamp having on and off states and intensity controlled in response to the driving signal from the inverter.
2. The liquid crystal display of claim 1 , wherein the inverter comprises:
a first block generating the first luminance control signal having the analog value depending on the luminance distribution of the image data;
a second block generating the second luminance control signal having the duty ratio depending on a frequency of the synchronization signal; and
a synthesizer synthesizing the first luminance control signal and the second luminance control signal generated from the first and the second block,
and the liquid crystal display further comprises:
a transistor circuit generating a current based on a signal outputted from the synthesizer; and
a lamp driving unit generating a high-voltage lamp driving signal based on the current supplied from the transistor circuit.
3. The liquid crystal display of claim 2 , wherein the first block counts the image data depending on the luminance distribution, calculates the number of the image data representing a predetermined luminance range from the count, and generates a first luminance control signal by comparing the calculation with a stored data in a reference table.
4. The liquid crystal display of claim 3 , wherein the first block counts and calculates luminance distribution of the image data by unit of horizontal scan period.
5. The liquid crystal display of claim 2 , wherein the first block employs an analog dimming control and the second block employs a pulse-width modulation dimming control.