Liquid crystal display device

• US 9,489,902 B2
• Filed: 09/05/2013
• Issued: 11/08/2016
• Est. Priority Date: 09/13/2012
• 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: Yoshida, Takehisa, Shimoshikiryoh, Fumikazu
• Primary Examiner(s): Shankar, Vijay
• Application Number:
  US14/427,344
• Publication Number:
  US 20150221267A1
• Time in Patent Office: 1,160 Days
• US Class Current: 1/1
• CPC Class Codes: G09G 2300/0447 for multi-domain technique to improve the viewing angle in a liquid crystal display, such as multi-vertical alignment [MVA]
• 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 2300/0478 related to liquid crystal pixels
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• CPC Class Codes: G09G 2320/028 by changing the viewing angle properties, e.g. widening the viewing angle, adapting the viewing angle to the view direction
• CPC Class Codes: G09G 2320/068 for control of viewing angle adjustment
• CPC Class Codes: G09G 3/3607 for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127
• 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 3/3659 the addressing of the pixel involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependant on signal of two data electrodes

Abstract

In a liquid crystal display device (100) according to an embodiment of the present invention, a plurality of color display pixels (CP) include three or more pixels (P) which exhibit different colors. The pixels (P) include a first sub-pixel (SP1) electrically connected to a first source bus line (SA) via a first TFT (T1) and a second sub-pixel (SP2) electrically connected to a second source bus line (SB) via a second TFT (T2). The control circuit (15) is configured to generate a first display signal voltage and a second display signal voltage that are to be supplied to the first sub-pixel (SP1) and the second sub-pixel (SP2) of a pixel (P) based on a grayscale level to be exhibited by the pixel (P) and grayscale levels to be exhibited by two or more remaining pixels (P) included in a color display pixel (CP) to which the pixel (P) belongs that are indicated by an input display signal, and output the generated first and second display signal voltages to the first source bus line (SA) and the second source bus line (SB), respectively.

Claims

1. A liquid crystal display device, comprising:

a plurality of pixels arranged in a matrix of rows and columns; and

a control circuit configured to receive an input display signal that is indicative of a grayscale level which is to be exhibited by the plurality of pixels and supply a display signal voltage to each of the plurality of pixels,

wherein the plurality of pixels form a plurality of color display pixels, each of the plurality of color display pixels including three or more pixels which exhibit different colors,

each of the plurality of pixels includes a first sub-pixel electrically connected to a first source bus line via a first TFT and a second sub-pixel electrically connected to a second source bus line via a second TFT, and

the control circuit is configured to generate a first display signal voltage and a second display signal voltage that are to be supplied to the first sub-pixel and the second sub-pixel of an arbitrary one of the plurality of pixels based on a grayscale level to be exhibited by the arbitrary pixel and grayscale levels to be exhibited by two or more remaining pixels included in a color display pixel to which the arbitrary pixel belongs that are indicated by the input display signal, and output the generated first and second display signal voltages to the first source bus line and the second source bus line, respectively.

2. The liquid crystal display device of claim 1, wherein for one grayscale level which is to be exhibited by the arbitrary pixel, the control circuit is capable of generating the first display signal voltage and the second display signal voltage that have two or more different absolute values according to the grayscale levels to be exhibited by the two or more remaining pixels.

3. The liquid crystal display device of claim 1, wherein

an arbitrary one of the plurality of color display pixels includes m pixels, from a 1^st pixel to a m^th pixel, where m is an integer which is not less than 3, grayscale levels which are to be exhibited by the 1^st pixel to the m^th pixel are 1^st grayscale level GL1 to m^th grayscale level GLm, luminances at a front viewing angle of the 1^st pixel to the m^th pixel achieved when the 1^st pixel to the m^th pixel exhibit the 1^st grayscale level GL1 to the m^th grayscale level GLm which are normalized on the assumption that a luminance at the front viewing angle achieved when a highest grayscale level is exhibited is 1 are 1^st frontal normalized luminance NL1 to m^th frontal normalized luminance NLm, respectively, luminances at an oblique 60°

viewing angle of the 1^st pixel to the m^th pixel which are normalized on the assumption that a luminance at the oblique 60°

viewing angle achieved when a highest grayscale level is exhibited is 1 are 1^st oblique viewing angle normalized luminance IL1 to m^th oblique viewing angle normalized luminance ILm, respectively, and

the control circuit is configured to generate the first display signal voltage and the second display signal voltage that are to be supplied to the first sub-pixel and the second sub-pixel of each of the 1^st pixel to the m^th pixel such that the maximum value of the difference between frontal luminance ratios between pixels which are obtained by normalizing the 1^st frontal normalized luminance NL1 to the m^th frontal normalized luminance NLm with respect to a highest one of the 1^st frontal normalized luminance NL1 to the m^th frontal normalized luminance NLm and oblique 60°

luminance ratios between pixels which are obtained by normalizing the 1^st oblique viewing angle normalized luminance IL1 to the m^th oblique viewing angle normalized luminance ILm with respect to a highest one of the 1^st oblique viewing angle normalized luminance IL1 to the m^th oblique viewing angle normalized luminance ILm is not more than 0.25.

4. The liquid crystal display device of claim 1, wherein

an arbitrary one of the plurality of color display pixels includes m pixels, from the 1^st pixel to the m^th pixel, where m is an integer which is not less than 3, the grayscale levels which are to be exhibited by the 1^st pixel to the m^th pixel are the 1^st grayscale level GL1 to the m^th grayscale level GLm, respectively, the 1^st grayscale level GL1 to the m^th grayscale level GLm include at least two different grayscale levels, and

the control circuit is configured to generate voltages which have equal absolute values as the first display signal voltage and the second display signal voltage respectively supplied to the first sub-pixel and the second sub-pixel of a pixel which is to exhibit a grayscale level of a largest value among the 1^st grayscale level GL1 to the m^th grayscale level GLm.

5. The liquid crystal display device of claim 4, wherein the control circuit is configured to generate the first display signal voltage and the second display signal voltage respectively supplied to the first sub-pixel and the second sub-pixel of each of the plurality of pixels exclusive of a pixel which exhibits a highest grayscale level among the m pixels included in the color display pixel such that a difference between the absolute values of the first display signal voltage and the second display signal voltage is a maximum.

6. The liquid crystal display device of claim 1, wherein

the first source bus line and the second source bus line extend in the column direction,

in each of the plurality of pixels, the first sub-pixel and the second sub-pixel are arranged in the column direction, and

a polarity of the first display signal voltage supplied from the first source bus line and a polarity of the second display signal voltage supplied from the second source bus line are each constant within a frame.

7. The liquid crystal display device of claim 6, wherein the polarity of the first display signal voltage supplied from the first source bus line and the polarity of the second display signal voltage supplied from the second source bus line are opposite to each other in a frame.

8. The liquid crystal display device of claim 6, wherein

some of the plurality of pixels which are arranged in the column direction are to exhibit a same color, and

two sub-pixels which belong to two pixels adjacent to each other in the column direction and which are electrically connected to the first source bus line are adjacent to each other in the column direction.

9. The liquid crystal display device of claim 1, wherein each of the plurality of color display pixels includes a red pixel, a green pixel, and a blue pixel.

10. The liquid crystal display device of claim 9, wherein each of the plurality of color display pixels further includes a yellow pixel.

11. The liquid crystal display device of claim 1, wherein the first TFT and the second TFT include a semiconductor oxide layer as an active layer, the semiconductor oxide layer including an In—

Ga—

Zn—

O semiconductor.

12. The liquid crystal display device of claim 11, wherein the In—

Ga—

Zn—

O semiconductor includes a crystalline portion.