Liquid crystal display device

• US 9,818,348 B2
• Filed: 01/27/2011
• Issued: 11/14/2017
• Est. Priority Date: 01/29/2010
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Kitayama, Masae, Hirata, Mitsuaki, Shimoshikiryoh, Fumikazu, Hyodo, Kenichi, Itsumi, Ikumi, Yamashita, Yuki, Sugisaka, Akane
• Primary Examiner(s): Lee, Benjamin C
• Assistant Examiner(s): Steinberg, Jeffrey S
• Application Number:
  US13/575,691
• Publication Number:
  US 20120320026A1
• Time in Patent Office: 2,483 Days
• Field of Search: 345 87-104, 345204, 345690
• CPC Class Codes: G02F 1/133707 Structures for producing distorted electric fields, e.g. bumps, protrusions, recesses, slits in pixel electrodes
• CPC Class Codes: G02F 1/13624 having more than one switching element per pixel
• CPC Class Codes: G02F 2201/52 RGB geometrical arrangements
• CPC Class Codes: G09G 2300/0452 Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• CPC Class Codes: G09G 2310/0205 Simultaneous scanning of several lines in flat panels
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2330/045 Protection against panel overheating
• CPC Class Codes: G09G 3/36 using liquid crystals

Abstract

A color display pixel P_CD in a liquid crystal display device (100) includes first through fourth pixels P₁ through P₄ arrayed in two rows by two columns, and first and second signal lines (13a, 13b) which are located in correspondence with each column of pixels and are supplied with signal voltages of polarities opposite to each other from a signal line driving circuit (30) in each vertical scanning period. A TFT (14) of one of the first and third pixel P₁ and P₃ is connected to the first signal line (13a), and a TFT (14) of the other pixel is connected to the second signal line (13b). A TFT (14) of one of the second and fourth pixel P₂ and P₄ is connected to the first signal line (13a), and a TFT (14) of the other pixel is connected to the second signal line (13b). The TFTs (14) of the first through fourth pixels P₁ through P₄ are controlled to be ON/OFF by a common scanning signal, and the polarities of the signal voltages supplied to the first and second signal lines (13a, 13b) are constant during an arbitrary vertical scanning period. Owing to this, the load on the signal line driving circuit is reduced.

Claims

1. A liquid crystal display device including a plurality of pixels arrayed in a matrix of a plurality of rows by a plurality of columns, the liquid crystal display device comprising:

an active matrix substrate including a pixel electrode provided for each of the plurality of pixels, a switching element connected to the pixel electrode, a plurality of scanning lines extending in a row direction, and a plurality of signal lines extending in a column direction;

a counter substrate facing the active matrix substrate;

a liquid crystal layer provided between the active matrix substrate and the counter substrate;

a scanning line driving circuit for supplying a scanning signal to each of the plurality of scanning lines; and

a signal line driving circuit for supplying a positive or negative signal voltage to each of the plurality of signal lines;

wherein;

the plurality of pixels form a plurality of color display pixels, and the plurality of color display pixels each include a first pixel, a second pixel, a third pixel, and a fourth pixel arrayed in two rows by two columns;

wherein the first pixel and the second pixel are adjacent to each other in the row direction, the third pixel and the fourth pixel are adjacent to each other in the row direction, the first pixel and the third pixel are adjacent to each other in the column direction, and the second pixel and the fourth pixel are adjacent to each other in the column direction, in each of the plurality of color display pixels;

the plurality of signal lines include first and second signal lines which are located in correspondence with each column of pixels and are supplied with signal voltages of opposite polarities from each other from the signal line driving circuit in each vertical scanning period;

in any given color display pixel, the switching element of one of the first and third pixels is connected to the first signal line, the switching element of the other of the first and third pixels is connected to the second signal line, the switching element of one of the second and fourth pixels is connected to the first signal line, the switching element of the other of the second and fourth pixels is connected to the second signal line, and the switching elements of the first, second, third and fourth pixels are controlled to be ON/OFF by a common scanning signal;

during any given vertical scanning period, the polarities of the signal voltages supplied to the first and second signal lines are constant;

in said any given vertical scanning period, a polarity of the signal voltage supplied to each of the first pixel, the second pixel, the third pixel, and the fourth pixel included in said any given color display pixel, and a polarity of the signal voltage supplied to each of the first pixel, the second pixel, the third pixel, and the fourth pixel included in a color display pixel adjacent to said any given color display pixel in the row direction, are opposite to each other; and

the first pixel included in said any given color display pixel and the second pixel included in the color display pixel adjacent to said any given color display pixel are directly adjacent to one another, and the third pixel included in said any given color display pixel and the fourth pixel included in the color display pixel adjacent to said any given color display pixel are directly adjacent to one another.

2. The liquid crystal display device of claim 1, wherein in a color display pixel adjacent to said any given color display pixel in the column direction, the switching element of one of the first and third pixels is connected to the second signal line, the switching element of the other of the first and third pixels is connected to the first signal line, the switching element of one of the second and fourth pixels is connected to the second signal line, and the switching element of the other of the second and fourth pixels is connected to the first signal line.

3. The liquid crystal display device of claim 1, wherein in said any given vertical scanning period, the polarities of the voltage signals supplied to the first pixel and the second pixel included in any given first color display pixel are opposite to each other, and the polarities of the voltage signals supplied to the third pixel and the fourth pixel included in the said any given first color display pixel are opposite to each other.

4. The liquid crystal display device of claim 1, wherein in said any given vertical scanning period, the polarities of the signal voltages supplied to any two given signal lines adjacent to each other, among the plurality of signals, are opposite to each other.

5. The liquid crystal display device of claim 1, wherein in said any given color display pixel, the switching elements of the first, second, third and fourth pixels are connected to a common scanning line.

6. The liquid crystal display device of claim 1, wherein the first, second, third and fourth pixels include one of a yellow pixel, a cyan pixel, a magenta pixel and a white pixel in addition to a red pixel, a blue pixel and a green pixel.

7. The liquid crystal display device of claim 1, wherein for displaying an intermediate gray scale level, the plurality of pixels each include a bright sub pixel exhibiting a luminance higher than that of the gray scale level to be displayed and a dark sub pixel exhibiting a luminance lower than that of the gray scale level to be displayed.

8. The liquid crystal display device of claim 1, wherein the any given vertical scanning period is 1/120 seconds or shorter.