Liquid crystal display device for display with gray levels

• US 5,499,037 A
• Filed: 06/14/1994
• Issued: 03/12/1996
• Est. Priority Date: 09/30/1988
• Status: Expired due to Term

• Current Assignee: Sharp Electronics Corporation (Hon Hai Precision Industry Co., Ltd.), Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Nakagawa, Kenichi, Numao, Takaji
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): Luu, Matthew
• Application Number:
  US08/261,234
• Time in Patent Office: 637 Days
• Field of Search: 345/87, 345/89, 345/103, 345/147, 345/149, 359/54, 359/61, 359/87, 358/455, 358/456, 358/458, 358/459
• US Class Current: 345/89
• CPC Class Codes: G02F 1/134336 Matrix
• CPC Class Codes: G02F 1/134345 Subdivided pixels, e.g. for grey scale or redundancy
• CPC Class Codes: G09G 3/2074 using sub-pixels
• 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 3/364 with use of subpixels

Abstract

A liquid crystal display device has an arrangement of a plurality of pixel display regions each including a plurality of divided pixels, and is capable of effecting display with a large number of gray levels. Each of the divided pixels is displayed individually and selectively with at least two gray levels. The liquid crystal device further includes pixel electrodes for individually and selectively enabling the divided pixels, and a gray level setting circuit for controlling the sum of the areas of the enabled divided pixels, thereby setting the gray levels of the pixels. In this device, one pixel display region includes n divided pixels and if each pixel can be displayed with m gray levels, the areas of the pixels are set to form a geometric progression using m as a common ratio, whereby display with mⁿ gray levels for one display region can be effected with high precision.

Claims

1. A liquid crystal display apparatus, comprising:

a plurality of scan electrodes arranged in parallel in a first direction;

a plurality of data electrodes arranged in parallel in a second direction perpendicular to said plurality of scan electrodes,

said plurality of scan electrodes and said plurality of data electrodes being utilized in a set of three electrodes each, thereby defining a 3×

3 matrix of rows and columns of picture elements, said matrix of picture elements further comprising,

a first group of pixels consisting of corner pixels of said matrix,

a second group of pixels consisting of first and third pixels of a second row of said matrix,

a third group of pixels consisting of first and third pixels of a second column of said matrix,

a fourth pixel group consisting of a center pixel of said matrix,

drive means for driving selected ones of said scan and data electrodes to display picture elements selected based upon a desired gray level display,

wherein said first and second groups of pixels comprise mutually equal sized pixels of a first size and said third and fourth groups of pixels comprise mutually equal sized pixels of a second size, said first size being greater than said second size, and

wherein the ratio of the sums of the areas of the pixels of said first, second, third and fourth groups of pixels is defined by the expression;

space="preserve" listing-type="equation">A;

B;

C;

D=8;

4;

2;

1

where A is the area of the first group of pixels, B is the area of the second group of pixels, C is the area of the third group of pixels, and D is the area of the fourth pixel group, thereby effecting a display having 16 gray levels.

2. A liquid crystal display apparatus, comprising:

a plurality of scan electrodes arranged in parallel in a first direction;

a plurality of data electrodes arranged in parallel in a second direction perpendicular to said plurality of scan electrodes,

said plurality of scan electrodes and said plurality of data electrodes being utilized in a set of three electrodes each, thereby defining a 3×

3 matrix of rows and columns of picture elements, said matrix of picture elements further comprising,

a first group of pixels consisting of corner pixels of said matrix,

a second group of pixels consisting of first and third pixels of a second row of said matrix,

a third group of pixels consisting of first and third pixels of a second column of said matrix,

a fourth pixel group consisting of a center pixel of said matrix,

drive means for driving selected ones of said scan and data electrodes to display picture elements selected based upon a desired gray level display,

wherein said first group of pixels comprises pixels of a first size, said second group of pixels comprises pixels of a second size, and said third group of pixels comprises pixels of a third size, and said fourth group of pixels comprises pixels of a fourth size, said first group of pixels being greater in size than said second, third and fourth groups, said second group of pixels being greater in size than said third and fourth groups, and said third group of pixels is greater in size than said fourth group, and

wherein the ratio of the sums of the areas of said first, second, third and fourth groups of pixels is defined by the expression;

space="preserve" listing-type="equation">E;

F;

G;

H-64;

16;

4;

1

where E is the area of the first group of pixels, F is the area of the second group of pixels, G is the area of the third group of pixels, and H is the area of the fourth pixel group, thereby effecting a display having 256 gray levels.