Multi-line addressing methods and apparatus

• US 20070046603A1
• Filed: 09/29/2005
• Published: 03/01/2007
• 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, Smith, Euan
• Granted Patent: US 7,944,410 B2
• Time in Patent Office: Days
• US Class Current: 345/90
• 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 2310/021 Double addressing, i.e. scanning two or more lines, e.g. lines 2 and 3; 4 and 5, at a time in a first field, followed by scanning two or more lines in another combination, e.g. lines 1 and 2; 3 and 4, in a second field
• 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 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 electroluminescent, in particular organic light emitting diodes (OLED) displays using multi-ling addressing (MLA) techniques. Embodiments of the invention are particularly suitable for use with so-called passive matrix OLED displays. A current generator for an electroluminescent display driver, the current generator including: a first, reference current input to receive a reference current; a second, ratioed current input to receive a ratioed current; a first ratio control input to receive a first control signal input; a controllable current mirror having a control input coupled to said first ratio control input, a current input coupled to said reference current input, and an output coupled to said ratioed current input; said current generator being configured such that a signal and said control input controls a ratio of said ratioed current to said reference current.

Claims

1. A current generator for an electroluminescent display driver, the current generator comprising:

a first, reference current input to receive a reference current;

a second, ratioed current input to receive a ratioed current;

a first ratio control input to receive a first control signal input;

a controllable current mirror having a control input coupled to said first ratio control input, a current input coupled to said reference current input, and an output coupled to said ratioed current input;

said current generator being configured such that a signal on said control input controls a ratio of said ratioed current to said reference current.

2. A current generator as claimed in claim 1 further comprising a second ratio control input to receive a second control signal input, and wherein said ratio of said ratioed current to said reference current is dependent upon a ratio of said first control signal to said second control signal.

3. A current generator as claimed in claim 1, wherein said first and second control signals comprise current signals.

4. A current generator as claimed in claim 1, further comprising one or more digital to analogue converters to provide said control signal(s).

5. A current generator as claimed in claim 2, comprising a plurality of said ratioed current inputs and a corresponding plurality of said second ratio control inputs for setting a plurality of said current ratios, one for each of said second ration control inputs.

6. A current generator as claimed in claim 1, further comprising a plurality of drive connections, and a selector to select one of said drive connections as said reference current input and another of said drive connections as said ratioed current input.

7. A current generator as claimed in claim 6 wherein said selector is coupled to said drive connections to selectively couple a selected one of said drive connections to said reference current input and another of said drive connections to said ratioed current input.

8. A current generator as claimed in claim 6 wherein said current mirror comprises a plurality of mirror units, one for each of said plurality of drive connections, and wherein said selector is configured to selectively couple at least said first ratio control input to a said mirror unit.

9. An OLED display driver comprising a current generator for an electroluminescent display driver, the current generator comprising:

a first, reference current input to receive a reference current;

a second, ratioed current input to receive a ratioed current;

a first ratio control input to receive a first control signal input;

a controllable current mirror having a control input coupled to said first ratio control input, a current input coupled to said reference current input, and an output coupled to said ratioed current input;

said current generator being configured such that a signal on said control input controls a ratio of said ratioed current to said reference current.

10. A current driver circuit for driving a plurality of electrodes of an electroluminescent display, said driver circuit comprising:

a control input to receive a control signal;

a plurality of drive connections for said plurality of display electrodes;

a selector configured to select one of said plurality of drive connections as a first connection and at least one other of said drive connections as a second connection; and

a driver configured to provide respective first and second drive signals for said first and second connections, a ratio of said first and second drive signals being controlled in accordance with said control signal.