Multi-line addressing methods and apparatus

• US 20070085779A1
• Filed: 09/29/2005
• Published: 04/19/2007
• Est. Priority Date: 09/30/2004
• Status: Active Grant

• Current Assignee: Cambridge Display Technology Limited (Sumitomo Chemical Company Limited)
• Original Assignee: Cambridge Display Technology Limited (Sumitomo Chemical Company Limited)
• Inventors: Routley, Paul, Halls, Jonathan, Smith, Euan
• Granted Patent: US 8,115,704 B2
• Time in Patent Office: Days
• US Class Current: 345/76
• 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 2310/0208 using active addressing
• CPC Class Codes: G09G 2310/0297 Special arrangements with multiplexing or demultiplexing of display data in the drivers for data electrodes, in a pre-processing circuitry delivering display data to said drivers or in the matrix panel, e.g. multiplexing plural data signals to one D/A converter or demultiplexing the D/A converter output to multiple columns
• CPC Class Codes: G09G 2310/04 Partial updating of the display screen
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/2014 by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/3216 using a passive matrix
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607

Abstract

This invention relates to methods and apparatus for driving emissive, in particular organic light emitting diodes (OLED) displays using multi-line addressing (MLA) techniques. Embodiments of the invention are particularly suitable for use with so-called passive matrix OLED displays. A method of driving an emissive display, the display comprising a plurality of pixels each addressable by a row electrode and a column electrode, the method comprising: driving a plurality of said column electrodes with a first set of column drive signals; and driving two or more of said row electrodes with a first set of forward bias row drive signals at the same time as said column electrode driving with said column drive signals; then driving said plurality of column electrodes with a second and subsequent sets of column drive signals; and driving said two or more row electrodes with a second and subsequent sets of forward bias row drive signals at the same time as said column electrode driving with said second column drive signals.

Claims

1. A method of driving an emissive display, the display comprising a plurality of pixels each addressable by a row electrode and a column electrode, the method comprising:

driving a plurality of said column electrodes with a first set of column drive signals; and

driving two or more of said row electrodes with a first set of forward bias row drive signals at the same time as said column electrode driving with said column drive signals;

then driving said plurality of column electrodes with a second set of column drive signals; and

driving said two or more row electrodes with a second set of forward bias row drive signals at the same time as said column electrode driving with said second column drive signals.

2. A method as claimed in claim 1 wherein said first and second column drive signals and said first and second row drive signals are selected such that a desired luminescence of said OLED pixels driven by said row and column electrodes is obtained by a substantially linear sum of a luminances determined by said first row and column drive signals and luminances determined by said second row and column drive signals.

3. A method as claimed in claim 1, wherein said first and second column drive signals and said first and second row drive signals are selected such that a peak luminance of a said pixel driven by said row and column electrodes is less than said peak luminance would be if said row electrodes were driven separately.

4. A method as claimed in claim 1, further comprising omitting said driving with said second row and column drive signals for two or more rows of said pixels having substantially the same desired luminance.

5. A method as claimed in claim 1, wherein said two or more row electrodes drive adjacent rows of said pixels.

6. A method as claimed in claim 1, wherein said two or more row electrodes drive separated or alternate rows of said pixels.

7. A method as claimed in claim 1, wherein said two or more row electrodes are substituted by one or more row electrodes in two or more successive image frames displayed on said emissive display.

8. A method as claimed in claim 1, further comprising omitting to drive said two or more row electrodes when said second row drive signals are substantially all less than a threshold drive value.

9. A method as claimed in claim 1, wherein both said first and second row drive signals and said first and second column drive signals comprise pulse width modulated drive signals.

10. A method as claimed in claim 1, wherein said first and second row and column drive signals comprise current drive signals.

11. A method as claimed in claim 10 further comprising driving said first and second row electrodes using a controllable current divider to divide said first column current drive signals between said two or more rows in accordance with said first row drive signals and to divide said second column current drive signals between said two or more rows in accordance with said second row drive signals.

12. A method as claimed in claim 1, wherein each said pixel comprises at least two sub-pixels of at least two different colours, each subpixel being addressable by a said row and column electrode, and wherein said driving of said two or more row electrodes comprises driving row electrodes of said two or more subpixels of a common pixel.

13. A method as claimed in claim 1, wherein each said pixel comprises at least two sub-pixels of at least two different colours, each subpixel being addressable by a said row and column electrode, and wherein said driving of said two or more row electrodes comprises driving row electrodes of subpixels of the same colour.

14. A method as claimed in claim 1, said further comprising selecting said two or more row electrodes from row electrodes in a group of three or more adjacent rows of electrodes.

15. A method as claimed in claim 1, wherein said row electrode driving comprises driving three or more of said row electrodes with said first and second sets of row drive signals, the method further comprising driving said plurality of column electrodes with a third set of column drive signals and at substantially the same time driving said three or more row electrodes with a third set of row drive signals.

16. A method as claimed in claim 1, wherein said emissive display is an OLED display.

18. A carrier carrying processor control code to implement the method of claim 1.

19. An OLED display driver comprising means to implement the method of claim 1.

17. (canceled)

20. An emissive display driver for driving an emissive display comprising a plurality of pixels each addressable by a row electrode and a column electrode, said display driver comprising:

means for driving a plurality of said column electrodes with a first set of column drive signals;

means for driving two or more of said row electrodes with a first set of forward bias row drive signals at the same time as said column electrode driving with said first column drive signals;

means for driving said plurality of column electrodes with a second set of column drive signals; and

means for driving said two or more row electrodes with a second set of forward bias row drive signals at the same time as said column electrode driving with said second column drive signals.

22. An emissive display driver as claimed in claim 20 wherein said row and column drivers comprise circuits to provide a controllable substantially constant current.

23. An emissive display driver as claimed in claim 20, wherein said emissive display is an OLED display.

26. An emissive display driver as claimed in claim 20, wherein said row and column drivers comprise circuits to provide a controllable substantially constant current.

21. An emissive display driver circuit for driving an emissive display, pixels of the display being addressed by row electrodes and corresponding column electrodes, said display driver comprising:

one or more column drivers to simultaneously drive a plurality of said column electrodes; and

one or more row drivers to simultaneously drive a plurality of said row electrodes corresponding to said column electrodes at the same time as said column electrode driving, such that a drive for a said column electrode is shared between a plurality of said row drivers.

24. An integrated circuit die chip comprising a plurality of drivers configured to drive a plurality of electrodes of an OLED display simultaneously, and display drive processing circuitry configured to determine drive signals for said plurality of electrodes;

and wherein said die has an aspect ratio of greater than 10 to 1 length to breadth.

25. A method of providing a multi-colour organic electro-luminescent display with an increased lifetime, the display comprising a matrix of pixels, each pixel having at least three sub-pixels, wherein a first sub-pixel comprises a sub-pixel of a first colour, a second sub-pixel comprises a sub-pixel of a second colour and a third sub-pixel comprises a sub-pixel of a third colour overlapping said first colour and said second colour, the method comprising determining the light output of the third sub-pixel as a component of the light output of the first sub-pixel and a component of the light output of the second sub-pixel, determining the maximum portion of light output emitable for a given colour using said third sub-pixel and subtracting the corresponding light output components from the first sub-pixel light output and the second sub-pixel light output.