Liquid crystal display device and method of driving the same

Patent metadata

Field	Value
Publication number	US-9280945-B2
Application number	US-201314025484-A
Country	US
Kind code	B2
Filing date	Sep 12, 2013
Priority date	Sep 13, 2012
Publication date	Mar 8, 2016
Grant date	Mar 8, 2016

Abstract

An LCD device is disclosed which includes: a liquid crystal display panel in which there are a plurality of gate lines and a plurality of data lines; a data driver configured to apply data voltages to the data lines; a gate driver configured to apply gate pulses to the gate lines; and a charge share device configured to selectively perform a charge share operation by storing charges corresponding to a data voltage applied to one of the data lines during a first interval and providing the stored charges to said one or another one of the data lines during a second interval based on a comparison of first video data corresponding to said one of the data lines in the first interval with second video data corresponding to said one or another one of the data lines in the second interval.

First claim

What is claimed is:

1. A liquid crystal display device comprising:
a liquid crystal display panel including a plurality of gate lines and a plurality of data lines;
a data driver configured to apply data voltages to the data lines;
a gate driver configured to apply gate pulses to the gate lines; and
a charge share device configured to selectively perform a charge share operation, the charge share device comprising:
a line memory configured to store first video data from a first interval, the first video data comprising a first entire gray level of a first data line during the first interval and a second entire gray level of a second data line during the first interval;
a determiner configured to:
receive second video data from a second interval, the second video data comprising a third entire gray level of the first data line during the second interval and a fourth entire gray level of the second data line during the second interval;
determine at least two differences between entire gray levels of the first video data and entire gray levels of the second video data, the differences comprising a first difference between the first entire gray level and the third entire gray level and a second difference between the second entire gray level and the fourth entire gray level,
detect a number of the at least two differences that are not less than a first non-zero reference gray level, and
output a charge share signal in response to the detected number of the at least two differences that are not less than the first non-zero reference gray level; and

one or more charge sharers configured to:
store charges corresponding to a bias voltage in response to the first video data during the first interval, and
provide, in response to the charge share signal, the stored charges to even or odd-numbered data lines in response to the second video data during the second interval.

2. The liquid crystal display device of claim 1 , wherein the one or more charge sharers comprise:
a positive charge sharer configured to perform the charge share operation for the odd-numbered data lines; and
a negative charge sharer configured to perform the charge share operation for the even-numbered data lines.

3. The liquid crystal display device of claim 2 , wherein
the positive charge sharer and the negative charge sharer each include a charge capacitor to store the charges, and
the charge share operation is performed using the bias voltage charged in the charge capacitor.

4. The liquid crystal display device of claim 3 , wherein
the charge capacitor is charged with the bias voltage while the data voltages are applied to the data lines, and
the charge share operation is performed while the data voltages are not applied to the data lines.

5. The liquid crystal display device of claim 3 , wherein the bias voltage is a reference voltage corresponding to a gray level 0 .

6. The liquid crystal display device of claim 2 , wherein the determiner generates:
a first charge share signal used to control the positive charge sharer; and
a second charge share signal used to control the negative charge sharer.

7. The liquid crystal display device of claim 1 , wherein the determiner calculates an average gray level of the first video data and determines whether to perform the charge share operation on the basis of the average gray level of the first video data if the detected number is not more than a reference value.

8. The liquid crystal display device of claim 7 , wherein the reference value is a second reference gray level, and the determiner determines whether to perform the charge share operation based on the average gray level of the first video data being not more than the second reference gray level in response to the detected number corresponding to 2 .

9. The liquid crystal display device of claim 8 , wherein the second reference gray level is between a maximum gray level and the first non-zero reference gray level.

10. The liquid crystal display device of claim 7 , wherein the reference value is a third reference gray level, and the determiner determines whether to perform the charge share operation based on the average gray level of the first video data being not more than the third reference gray level in response to the detected number corresponding to 1 .

11. The liquid crystal display device of claim 10 , wherein the first non-zero reference gray level and third reference gray level are substantially the same.

12. The liquid crystal display device of claim 1 , wherein the data driver includes:
a digital-to-analog converter configured to convert video data into the data voltages;
a positive polarity buffer outputting positive data voltages from the digital-to-analog converter to the data lines, the positive polarity buffer including a positive polarity logic circuit; and
a negative polarity buffer outputting negative data voltages from the digital-to-analog converter to the data lines, the negative polarity buffer including a negative polarity logic circuit, the positive polarity logic circuit and the negative polarity logic circuit being coupled in series between a supply voltage line and a ground voltage line.

13. The liquid crystal display device of claim 1 , wherein the liquid crystal display panel is driven in a double rate driving mode.

14. A method of driving a liquid crystal display device including a plurality of gate lines and a plurality of data lines, the method comprising:
storing charges corresponding to a bias voltage while applying a data voltage to one of the data lines during a first interval;
storing first video data from a first interval, the first video data comprising a first entire gray level of a first data line during the first interval and a second entire gray level of a second data line during the first interval;
receiving second video data from a second interval, the second video data comprising a third entire gray level of the first data line during the second interval and a fourth entire gray level of the second data line during the second interval;
determining at least two differences between entire gray levels of the first video data and entire gray levels of the second video data, the differences comprising a first difference between the first entire gray level and the third entire gray level and a second difference between the second entire gray level and the fourth entire gray level;
detecting a number of the at least two differences that are at least a first non-zero reference gray level; and
determining whether to perform a charge share operation based at least in part on the detected number exceeding a threshold value, the charge share operation performed by providing the stored charges to said one or another one of the data lines during the second interval.

15. The method of claim 14 , further comprising outputting a charge share signal when the detected number equals a total number of the at least two differences.

16. The method of claim 14 , further comprising comparing an average gray level of the first video data with a second reference gray level when the detected number corresponds to 1 .

17. The method of claim 16 , further comprising outputting a charge share signal when the average gray level of the first video data is not more than the second reference gray level.

18. The method of claim 16 , wherein the first and second reference gray levels are substantially the same.

19. The method of claim 14 , further comprising comparing an average gray level of the first video data with a t

Assignees

• Lg Display Co Ltd

Inventors

• Oh Dae Seok
• Seo Bo Gun
• Park Yong Hwa

Classifications

• G09G3/3648

  using an active matrix (G09G3/367 - G09G3/3696 take precedence) · CPC title

• G09G3/3688

  suitable for active matrices only · CPC title

• G09G2310/0248

  Precharge or discharge of column electrodes before or after applying exact column voltages · CPC title

• G09G2330/023

  using energy recovery or conservation · CPC title

• G09G2310/027

  Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters · CPC title