Uniformity and brightness measurement in OLED displays

1. A detection system for the detection of brightness and uniformity variations in a pre-defined group of light-emitting elements in an OLED display, comprising:

a) a two-dimensional OLED display having a pre-defined group of light-emitting elements distributed across the display comprising up to N W light-emitting elements in a first dimension and up to N H light-emitting element in a second dimension orthogonal to the first dimension, each light-emitting element having a light-emitting element width and a separation width from an adjacent light-emitting element in the pre-defined group in the first dimension and a light-emitting element height and a separation height from an adjacent light-emitting element in the pre-defined group in the second dimension, wherein the light emitting elements and separations in the first dimension have a characteristic element width P W and separation width S W , P W and S W being the element width and separation width from an adjacent element in the pre-defined group in the first dimension that provides the largest ratio, and the light emitting elements and separations in the second dimension have a characteristic element height P H and separation height S H , P H and S H being the element height and separation height from an adjacent element in the pre-defined group in the second dimension that provides the largest ratio;

b) a two-dimensional imager with a plurality of light-sensitive sensor elements sensitive to the light emitted by the light-emitting elements, wherein the number of light-sensitive sensor elements in a first dimension of the imager is greater than 2(N W −1)[(P W +S W )/MIN(P W ,S W )], and the number of light sensitive sensor elements in a second dimension orthogonal to the first dimension of the imager is greater than 2(N H −1)[(P H +S H )/MIN(P H ,S H )];

c) optical elements arranged so that the imager is exposed to all of the light-emitting elements in the predefined group of light-emitting elements of the OLED display simultaneously and at a magnification such that each light-sensitive sensor element records the light output from no more than one light-emitting element; and

d) a controller to control the OLED display and cause each of the light-emitting elements of the predefined group of light-emitting elements to illuminate and the imager to acquire images of the illuminated light-emitting elements in the OLED display.

2. A method for the measurement of brightness and uniformity variations in light-emitting elements of an OLED display, comprising the steps of:

a) providing a detection system according to claim 1 ;

b) illuminating all of the OLED display light-emitting elements within a pre-defined group distributed across the display;

c) acquiring an image of the OLED display light-emitting elements; and

d) processing the image of the OLED display light-emitting elements to provide a measurement of the brightness of each OLED display light-emitting element in the group.

3. The method of claim 2 further comprising the step of acquiring a dark image of the OLED display when no OLED display light-emitting elements are illuminated.

4. The method of claim 3 further comprising subtracting the dark image from the acquired image of the OLED display light-emitting elements before processing the image of the OLED display light-emitting elements.

5. The method of claim 2 further comprising the step of illuminating light-emitting elements on the edge or corner of the OLED display and performing a perspective transformation of the acquired image of the OLED display light-emitting elements before processing the image of the OLED display light-emitting elements to provide a measurement of the brightness of each OLED display light-emitting element.

6. The method of claim 2 further comprising the step of acquiring a plurality of OLED display images at a variety of light-emitting element illumination levels.

7. The method of claim 2 wherein the pre-defined group is defined by the color of light emitted by the light-emitting elements.

8. The system of claim 1 wherein the two-dimensional imager is incorporated into a digital camera.

9. The system of claim 1 wherein the light emitting elements have a variable spacing, variable size, and/or variable shape.

10. The system of claim 1 wherein the light emitting elements have a predominantly rectangular shape.

11. The system of claim 1 wherein the optical elements form a defocused image of the light-emitting elements of the OLED display on the imager.

12. The system of claim 1 wherein the optical elements form a focused image of the light-emitting elements of the OLED display on the imager.