Liquid-crystal display, liquid-crystal control circuit, flicker inhibition method, and liquid-crystal driving method

• US 20010024181A1
• Filed: 01/12/2001
• Published: 09/27/2001
• Est. Priority Date: 01/17/2000
• Status: Active Grant

• Current Assignee: AU Optronics Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Ishikawa, Takuya, Funakoshi, Akihiro, Kubota, Tetsu
• Granted Patent: US 6,778,160 B2
• Time in Patent Office: Days
• US Class Current: 345/87
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2340/16 Determination of a pixel data signal depending on the signal applied in the previous frame
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

A liquid crystal display comprises an input for inputting a video signal from a host and a storage medium for storing the previous brightness level of the video signal input through the input. A determinator is provided for determining an output brightness level based on the previous brightness level stored in the storage medium and the next brightness level of the next video signal input to the input, so as to make the time integration quantity of a brightness change substantially equal to an ideal quantity of light in a stationary state with respect to the next brightness level. Further included are drivers for driving an image displaying liquid crystal cell based on the output brightness level determined by the determinator.

Claims

1. A liquid crystal display, comprising:

an input logic for inputting a video signal from a host;

a storage for storing the previous brightness level of the video signal input through said input logic;

a determinator for determining an output brightness level based on the previous brightness level stored in said storage and the next brightness level of the next video signal input to said input logic so as to make a time integration quantity of a brightness change substantially equal to an ideal quantity of light in a stationary state with respect to the next brightness level; and

a driver for driving an image displaying liquid crystal cell based on said output brightness level determined by said determination logic.

2. The liquid crystal display according to

claim 1

, wherein said determinator comprising a table for storing a brightness level determined by the characteristic of a liquid crystal cell according to a relation between the previous brightness level and the next brightness level, and determining the output brightness level by modifying said next brightness level based on the brightness level read from said table.

3. The liquid crystal display according to

claim 2

, wherein:

said video signal input through said input logic comprises a plurality of color signals; and

said table in said determinator is provided for each of said color signals.

4. A liquid crystal display, comprising:

a driver for driving each of the pixels forming an image for each frame to a liquid crystal cell displaying said image;

an input logic for inputting a moving-state video signal which changes from the on state to the off state on transition to a particular frame in said frames and returns to the off state after said particular frame is completed;

a setting logic for setting an offset for making the quantity of light closer to the quantity of light in a stationary state in which said moving-state video signal is continuously turned on for said particular frame;

a generator for applying said offset set by said setting logic to said moving-state video signal input through said input logic to generate an output video signal; and

an output logic for outputting said output video signal generated by said generator to said driver.

5. The liquid crystal display according to

claim 4

, wherein said offset set by said setting logic can be determined based on a time integration quantity and the quantity of light in said stationary state, said time integration quantity being a change in brightness in said moving-state vide signal integrated with respect to time.

6. The liquid crystal display according to

claim 4

, wherein:

said moving-state video signal input through said input logic comprises a plurality of color signals;

said offset set by said setting logic is determined for each of said color signals; and

said generator generates the output video signal for each color signal based on said offset determined for each color signal.

7. A liquid crystal control circuit, having a function for inhibiting flicker caused by a difference in brightness when an input wire-frame model is displayed by liquid crystal cells, comprising:

a storage portion for storing an offset in brightness in a moving state in which said wire-frame model having a predetermined gray scale changes from frame to frame with respect to a particular pixel, with relation to brightness output in a stationary state in which the wire-frame model having the predetermined gray scale is displayed on the particular pixel across a plurality of frames; and

a correction portion for applying said offset stored in said storage portion to the gray scale of the wire-frame model if said input wire-frame model is in a moving state.

8. The liquid crystal control circuit according to

claim 7

, further comprising a frame buffer for storing the brightness information of said input wire-frame model as the previous brightness,

wherein said storage portion stores said offset as table information based on a relation between said previous brightness stored in said frame buffer and the brightness of the next input wire-frame model.

9. A flicker inhibition method for inhibiting flicker caused by a difference in brightness when an input wire-frame model is displayed by a liquid crystal cell, comprising the steps of:

storing a relation between brightness in a stationary state in which a wire-frame model having a predetermined gray scale is displayed on a particular pixel and a plurality of frames and brightness in a moving state in which the wire-frame model having the predetermined gray scale changes frame to frame with respect to the particular pixel;

applying an offset based on said stored relation to the gray scale of said wire-frame model if said input wire-frame model is in a moving state; and

driving said liquid crystal cell based on said gray scale to which said offset is applied to display said wire-frame model.

10. The flicker inhibition method according to

claim 9

, wherein said storing step said moving state brightness used for storing said relation is the brightness when said particular pixel changes back to the off state one frame after said particular pixel is driven from the off state to the on state during the passage of the wire-model frame over the particular pixel.

11. The flicker inhibition method according to

claim 9

, wherein said storing step said brightness in the moving state which is used when said relation is stored is the quantity of light equal to a brightness change integrated with respect to time.

12. A liquid crystal driving method, comprising the steps of:

storing first brightness information for an input pixel in a frame buffer;

applying based on second brightness information for the next input pixel and said first brightness information stored in said frame buffer an offset for making the time integration quantity of a brightness change substantially equal to an ideal light quantity which is the brightness in a stationary state to said second brightness information;

outputting said second brightness information to which said offset is applied to a driving circuit for driving an liquid crystal cell; and

storing said second brightness information for the input pixel in a frame buffer.

13. The liquid crystal driving method according to

claim 12

, wherein:

said step of storing said first brightness information in the frame buffer stores said first brightness information for each of said color signals and said input pixel comprises a plurality of color signals; and

said step of applying the offset applies said offset to each of said color signals.

14. The liquid crystal driving method according to

claim 12

, wherein said offset applying step comprises the steps of reading a pre-stored offset based on a relation between said first and second brightness information and applying said read offset to said second brightness information.