Method for driving liquid crystal display panel, with reduced flicker and with no sticking

• US 5,479,188 A
• Filed: 06/02/1994
• Issued: 12/26/1995
• Est. Priority Date: 06/02/1993
• Status: Expired due to Term

• Current Assignee: InnoLux Corporation
• Original Assignee: NEC Corporation
• Inventors: Moriyama, Hiroaki
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): CHANG, KENT WU
• Application Number:
  US08/253,180
• Time in Patent Office: 572 Days
• Field of Search: 345/89, 345/95, 345/96, 345/147, 345/148, 345/149, 345/87, 358/458, 358/455, 358/456
• US Class Current: 345/89
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 3/2018 by time modulation using two or more time intervals
• CPC Class Codes: G09G 3/2051 with use of a spatial dither pattern
• CPC Class Codes: G09G 3/2055 the pattern being varied in time
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

In a liquid crystal display driving method, a first and positive voltage and a second and negative voltage are applied for displaying a first brightness level, respectively, and a third and positive voltage and a fourth and negative voltage are applied for displaying a second brightness level, respectively. In each unitary pixel block composed of two rows and two columns, a driving voltage is applied in such a manner that in each of four continuous frames, the first to fourth voltages are always applied to four pixels of the unitary pixel block, but in the four continuous frames, the four voltages are applied to each pixel in the order of the first to fourth voltages but in a phase different from the phase for each of the remaining three pixels. Thus, the four-frame thinning out system can be performed for displaying a halftone, with a minimized flicker.

Claims

1. A method for driving a liquid crystal display comprising a plurality of pixels arranged in a matrix having a plurality of rows and a plurality of columns, the method comprising steps of:

alternately applying, in two continuous frames of each four continuous frames, a first, positive voltage and a second, negative voltage to a pixel for displaying a first brightness; and

alternately applying, in the remaining two continuous frames, a third, positive voltage and a fourth, negative voltage to the pixel for displaying a second brightness different from said first brightness, so that a halftone between said first brightness and said second brightness is displayed,

wherein, in each unitary pixel block comprising pixels arranged in two rows and in two columns, all of said first to fourth voltages are sequentially applied to each pixel in said four continuous frames such that one voltage is applied in one frame, and said first to fourth voltages are simultaneously applied to four pixels of the unitary pixel block in each frame of said four continuous flames.

2. A method as claimed in claim 1 wherein said first to fourth voltages are applied to each pixel in the named order of said first voltage, said second voltage, said third voltage and said fourth voltage.

3. A method as claimed in claim 1 wherein said first to fourth voltages are applied to each pixel in the named order of said second voltage, said first voltage, said fourth voltage and said third voltage.

4. A method according to claim 1, wherein a voltage of said first, positive voltage is greater than a voltage of said third, positive voltage.

5. A method according to claim 4, wherein a voltage of said second, negative voltage is greater than a voltage of said fourth, negative voltage such that said brightness displayed by said first and second frames has a first gradation and said brightness displayed by said third and fourth frames has a second gradation, and such that a brightness having a third gradation is displayed a whole by said first to said fourth frames,

wherein said brightness having said third gradation is intermediate to that of said first and second brightnesses.

6. A method according to claim 1, wherein said unitary pixel block includes a plurality of brightnesses in each frame, such that a flicker component of four adjacent pixels of said unitary pixel block is mutually cancelled and such that a mean actual brightness per frame becomes a same value.

7. A method according to claim 1, wherein voltage waveforms respectively applied to each pixel of said unitary pixel block have a same value and a different phase, so as to prevent flickering in said liquid crystal display.

8. A method according to claim 1, wherein said first voltage, said second voltage, said third voltage, and said fourth voltage each have a different value and are sequentially applied to four pixels of said unitary pixel block in four continuous frames.

9. A method according to claim 1, wherein said liquid crystal display is devoid of a direct current (DC) voltage being applied thereto.

10. A method according to claim 2, wherein a voltage of said first, positive voltage is greater than a voltage of said third, positive voltage.

11. A method according to claim 10, wherein a voltage of said second, negative voltage is greater than a voltage of said fourth, negative voltage such that said brightness displayed by said first and second frames has a first gradation and said brightness displayed by said third and fourth frames has a second gradation, and such that said halftone having a brightness having a third gradation is displayed a whole by said first to said fourth frames,

wherein said brightness having said third gradation is intermediate to that of said first and second brightnesses.

12. A method according to claim 2, wherein said unitary pixel block includes a plurality of brightnesses in each frame, such that a flicker component of four adjacent pixels of said unitary pixel block is mutually cancelled and such that a mean actual brightness per frame becomes a same value.

13. A method according to claim 2, wherein voltage waveforms respectively applied to each pixel of said unitary pixel block have a same value and a different phase, so as to prevent flickering in said liquid crystal display.

14. A method according to claim 2, wherein said first voltage, said second voltage, said third voltage, and said fourth voltage each have a different value and are sequentially applied to four pixels of said unitary pixel block in four continuous frames.

15. A method according to claim 2, wherein said liquid crystal display is devoid of a direct current (DC) voltage being applied thereto.

16. A method according to claim 3, wherein a voltage of said first, positive voltage is greater than a voltage of said third, positive voltage.

17. A method according to claim 16, wherein a voltage of said second, negative voltage is greater than a voltage of said fourth, negative voltage such that said brightness displayed by said first and second frames has a first gradation and said brightness displayed by said third and fourth frames has a second gradation, and such that a brightness having a third gradation is displayed a whole by said first to said fourth frames,

wherein said brightness having said third gradation is intermediate to that of said first and second brightnesses.

18. A method according to claim 3, wherein said unitary pixel block includes a plurality of brightnesses in each frame, such that a flicker component of four adjacent pixels of said unitary pixel block is mutually cancelled and such that a mean actual brightness per frame becomes a same value.

19. A method according to claim 3, wherein voltage waveforms respectively applied to each pixel of said unitary pixel block have a same value and a different phase, so as to prevent flickering in said liquid crystal display.

20. A method according to claim 3, wherein said first voltage, said second voltage, said third voltage, and said fourth voltage have a different value and are sequentially applied to four pixels of said unitary pixel block in four continuous frames,

wherein said liquid crystal display is devoid of a direct current (DC) voltage being applied thereto.