Display drive systems
AssigneeCambridge Display Technology Limited
InventorEuan Smith
Life of this patent
Estimating the term…
Abstract
This invention generally relates to methods, apparatus and computer program code for improved OLED (organic light emitting diode) display drive systems, in particular to compensate for burn-in. A method of compensating an OLED display device for burn-in of pixels of the OLED display, the method comprising: measuring a first voltage drop across at least one test pixel of the display; measuring a second voltage drop across at least one other pixel of the display; determining, from said first and second voltages and a from value (V1) representing a drive voltage increase for a loss in efficiency of said display due to burn-in, an estimated reduction in efficiency of said display due to burn-in; and compensating a drive to said display using said estimated efficiency reduction.
Claims14
A method of controlling a drive to a pixel of an OLED display having a test pixel and display pixels, the method comprising determining a drive current for the pixel to be controlled by first calculating a value of η/η0 using:
- V
- now
- test
- =
- V
- now
- other
- -
- 2
-
- V
- 1
-
- (
- 1
- -
- η
- η
- 0
- )
- where Vnowtest is the voltage drop measured across the test pixel at a test drive current, η0 is the luminance efficiency of said test pixel at said test drive current at an initial time;
- Vnowother is the voltage drop measured across at least one other pixel to be controlled at said test drive current, and V1 is the end of life voltage increase in said voltage drive for said test drive current;
- and scaling the drive current to the pixel to be controlled by multiplying the drive current requested by the value η0/η.
An active matrix OLED display having a test pixel and display pixels, the display comprising:
- a display controller configured to determine a drive current for a pixel of an OLED display, the pixel to be controlled by first calculating a value of η/η0 using:
- V
- now
- test
- =
- V
- now
- other
- -
- 2
-
- V
- 1
-
- (
- 1
- -
- η
- η
- 0
- )
- where Vnowtest is the voltage drop measured across a test pixel at a test drive current, η0 is the luminance efficiency of said test pixel at said test drive current at an initial time;
- Vnowother is the voltage drop measured across at least one other pixel to be controlled at said test drive current, and V1 is the end of life voltage increase in said voltage drive for said test drive current;
- and the display controller configured to scale the drive current to the pixel to be controlled by multiplying the drive current requested by the value η0/η,
- the display controller comprising:
- an input for measuring a first voltage drop across at least one test pixel of the display;
- an input for measuring a second voltage drop across at least one other pixel of the display;
- a store storing a value (V1) representing a drive voltage increase for a loss in efficiency of said display;
- a system for determining an estimated reduction in efficiency (η0/η) of said display from said first and second voltages and said value (V1);
- and
- a system for scaling the drive current to said pixel using said estimated efficiency reduction,
- wherein said active matrix OLED display further comprises a matrix of pixel driver circuits, each pixel driver circuit including a transistor having an input connection coupled to an OLED device of the pixel for measuring a voltage across said OLED device, an output coupled to a first electrode line of said display and a control connection coupled to a second electrode line of said display.
Dependencies are inferred from the claim text.