Method of controlling polarity of data voltage and liquid crystal display using the same

• US 9,343,033 B2
• Filed: 12/20/2013
• Issued: 05/17/2016
• Est. Priority Date: 12/28/2012
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Cho, Changhun
• Primary Examiner(s): Bost, Dwayne
• Assistant Examiner(s): Oehrlein, Stefan M
• Application Number:
  US14/136,453
• Publication Number:
  US 20140184580A1
• Time in Patent Office: 879 Days
• US Class Current: 1/1
• CPC Class Codes: G09G 2320/0204 Compensation of DC component across the pixels in flat panels
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers

Abstract

A method of controlling polarity of a data voltage and a liquid crystal display using the same, the method including calculating a direct current DC value of the data from each group which data to be output through I-channels adjacent to each other in a source drive IC belong; accumulating the DC value; comparing an absolute value of the accumulation DC value of the n-th group obtained by adding the accumulation DC value of the n−1-th group accumulated up to the n−1-th group to the DC value of the n-th group (n is positive integer) with a predetermined threshold value; and changing a group polarity data when the absolute value of the accumulation DC value of the n-th group exceeds the threshold value.

Claims

1. A method of controlling polarity of a data voltage, the method comprising:

calculating a direct current (DC) value data to be written to each group of sub-pixels among a plurality of sub-pixel groups, from each group defined based on outputting data at a same time through I-channels adjacent to each other in a source drive integrated circuit (IC), where I is a multiple of 3 between 3 to 18;

setting a group representative value defining polarity of a first sub-pixel positioned leftmost in each corresponding group; and

selecting the group polarity data using a value obtained by inverting or maintaining the group representative polarity by comparing the DC value of the groups adjacent to each other with a sign of the DC value;

summing the DC values of each of the 1st through n-th groups to create an accumulation DC value for the n-th group, where n is a positive integer;

comparing an absolute value of the accumulation DC value of the n-th group to a predetermined threshold value;

and changing the group polarity data for the n-th group in response to the absolute value of the accumulation DC value of the n-th group exceeding the threshold value, wherein the DC value of each group is a value obtained by adding high gray level data among the data to be written to the corresponding group,

and wherein the group polarity data defines a first polarity representing the group.

2. The method of claim 1, wherein the group polarity data is included in a data stream in which the data belonging within one group are included and is transmitted to the source drive IC.

3. The method of claim 2, wherein the source drive IC selects the polarity of each of the data voltages to be output through the I-channels in response to the group polarity data.

4. The method of claim 1, further comprising:

selecting the group polarity data using the value obtained by inverting or maintaining the group representative polarity by comparing the DC value of the groups adjacent to each other with a sign of the DC value,

when the DC value of the 1-st group refers to DC(1), the DC value of the 2-nd group refers to DC(2), the DC value of the 3-rd group refers to DC(3) and the DC value of the 4-th group refers to DC(4),

when |DC(1)|=|DC(2)|, and a sign of the DC(1) and a sign of the DC(2) are the same, the group polarity data of the 2-nd group is selected to the value obtained by inverting the group representative polarity, and the group polarity data of the 1-st group is selected to the same polarity as the group representative polarity,

when |DC(1)|=|DC(2)| and the sign of the DC(1) and sign of the DC(2) are different from each other, the group polarity data of the 2-nd group and the group polarity data of the 1-st group are selected to the same polarity as the group representative polarity,

when |DC(1)+DC(2)|=|DC(3)+DC(4)| and a sign of the DC(1)+DC(2) and a sign of the DC(3)+DC(4) are the same, the group polarity data of the 3-rd group is selected to the value obtained by inverting the group representative polarity, and the group polarity data of the 2-nd group is selected to the same polarity as the group representative polarity, and

when |DC(1)+DC(2)|=|DC(3)+DC(4)| and the sign of the DC(1)+DC(2) and sign of the DC(3)+DC(4) are different from each other, the group polarity data of the 3-rd group and the group polarity data of the 2-nd group are selected to the same polarity as the group representative polarity.

5. The method of claim 1, wherein the high gray level data is a value based on a most significant bit of the data to be written to a corresponding group.

6. A liquid crystal display, comprising:

a display panel in which data lines and gate lines are orthogonal to each other and pixels are arranged in a matrix form;

a source drive integrated circuit (IC) configured to;

receive a group polarity data defining polarity of data to be written to each group of sub-pixels among a plurality of sub-pixel groups, the data including data of an input image and select polarity of each data voltage according to the group polarity data and outputting the data voltages to the data lines;

and a timing controller configured to;

calculate a direct current (DC) value of the data to be written to each corresponding group, each group defined based on outputting data at a same time through I-channels adjacent to each other in the source driver IC, where I is a multiple of 3 between 3 to 18, set a group representative value defining polarity of a first sub-pixel positioned leftmost in each corresponding group; and

select the group polarity data using a value obtained by inverting or maintaining the group representative polarity by comparing the DC value of the groups adjacent to each other with a sign of the DC value;

sum the DC values of each of the through n-th groups to create an accumulation DC value for the n-th group, where n is a positive integer,

compare an absolute value of the accumulation DC value of the n-th group to a predetermined threshold value,

and change the group polarity data for the n-th group in response to the absolute value of the accumulation DC value of the n-th group exceeding the threshold value,

wherein the DC value of each group is a value obtained by adding high gray level data among the data to be written to the corresponding group, and wherein the group polarity data defines a first polarity representing the group.

7. The liquid crystal display of claim 6, wherein the timing controller transmits a data stream obtained by adding the group polarity data to the data belonging within one group to the source drive IC.

8. The liquid crystal display of claim 7, wherein the source drive IC selects the polarity of each of the data voltages to be output through the I-channels in response to the group polarity data.

9. The liquid crystal display of claim 6, wherein the timing controller

selects the group polarity data using the value obtained by inverting or maintaining the group representative polarity by comparing the DC value of the groups adjacent to each other with a sign of the DC value,

when the DC value of the 1-st group refers to DC(1), the DC value of the 2-nd group refers to DC(2), the DC value of the 3-rd group refers to DC(3) and the DC value of the 4-th group refers to DC(4),

when |DC(1)|=|DC(2)|, and a sign of the DC(1) and a sign of the DC(2) are the same, the group polarity data of the 2-nd group is selected to the value obtained by inverting the group representative polarity, and the group polarity data of the 1-st group is selected to the same polarity as the group representative polarity,

when |DC(1)|=|DC(2)| and the sign of the DC(1) and sign of the DC(2) are different from each other, the group polarity data of the 2-nd group and the group polarity data of the 1-st group are selected to the same polarity as the group representative polarity,

when |DC(1)+DC(2)|=|DC(3)+DC(4)| and a sign of the DC(1)+DC(2) and a sign of the DC(3)+DC(4) are the same, the group polarity data of the 3-rd group is selected to the value obtained by inverting the group representative polarity, and the group polarity data of the 2-nd group is selected to the same polarity as the group representative polarity, and

when |DC(1)+DC(2)|=|DC(3)+DC(4)| and the sign of the DC(1)+DC(2) and sign of the DC(3)+DC(4) are different from each other, the group polarity data of the 3-rd group and the group polarity data of the 2-nd group are selected to the same polarity as the group representative polarity.

10. The liquid crystal display of claim 6, wherein the high gray level data is a value based on a most significant bit of the data to be written to a corresponding group.