Optical Correction for AMOLED Non-Uniformity Using Defocused Imaging
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Solution Overview
Problem
Modern display technologies, particularly AMOLED panels, suffer from luminance non-uniformity due to fabrication defects and aging, which existing optical correction methods struggle to address effectively, especially when the camera's spatial sampling rate falls below twice the display's pixel rate, leading to aliasing and pixel overlap issues.
Innovation Solution
An optical correction method involving a camera positioned in front of the display panel, intentionally defocused to blur individual pixels, capturing images of test patterns with spaced-apart activated pixels to avoid overlap, allowing for accurate luminance measurement and correction data generation without requiring a camera resolution higher than twice that of the display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the camera's spatial sampling rate is increased to avoid aliasing and pixel overlap, then measurement precision is improved, but device complexity and cost increase due to requiring higher resolution cameras
Solution Approach 1:
The patent segments the measurement process by displaying test patterns with activated pixels spaced apart at different locations and orientations. This segmentation allows the blurred images of individual pixels to be separated in the captured image, enabling accurate luminance measurement without requiring the camera to resolve every pixel individually. The measurement is performed across multiple segmented test patterns rather than attempting to capture all pixels simultaneously at full resolution.
Solution Approach 2:
The patent changes the spatial arrangement parameter of the test pattern by displaying activated pixels at various spacings and orientations (e.g., horizontal, vertical, diagonal arrangements). By varying these parameters across different test patterns, the system ensures that blurred images of pixels do not overlap in a way that causes aliasing, while using a standard resolution camera. This parameter variation enables accurate measurement without requiring high camera resolution.
2Measurement precision
If the camera is focused sharply on the display panel, then individual pixel resolution is improved, but pixel overlap and aliasing occur in captured images
Solution Approach 1:
The patent converts the harmful effect of camera blur into a beneficial feature. Instead of attempting to capture sharp images of individual pixels (which causes overlap and aliasing when using standard resolution cameras), the system intentionally uses a defocused camera to create blurred images. The test patterns are designed with spaced-apart activated pixels specifically to ensure that their blurred images do not overlap. This approach transforms the limitation of standard resolution cameras into an acceptable solution by making blur the expected condition rather than a defect to be overcome.
3Ease of manufacture
If standard resolution cameras are used for optical correction, then device cost is reduced, but measurement precision deteriorates due to aliasing and pixel overlap
Solution Approach 1:
The patent segments the measurement task across multiple test patterns with activated pixels arranged at different spacings and orientations. By displaying test patterns where pixels are activated in specific sparse arrangements (e.g., every other pixel, or pixels arranged in diagonal lines), the system ensures that when captured with a standard resolution camera, the blurred images of individual pixels remain separable. This segmentation approach enables accurate luminance measurement using cost-effective standard resolution cameras without requiring high-resolution equipment.
4Measurement precision
If test patterns with closely spaced pixels are displayed, then measurement coverage is improved, but pixel overlap and aliasing increase in captured images
Solution Approach 1:
The patent varies the spatial arrangement parameters of activated pixels across different test patterns. Instead of using a single fixed pattern, the system displays multiple test patterns with pixels arranged at different spacings, orientations, and densities. For example, one pattern may have horizontally spaced pixels, another vertically spaced, and another diagonally arranged. This parameter variation ensures that for any given camera position and blur level, the blurred images of pixels remain separable, enabling comprehensive measurement coverage without pixel overlap or aliasing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables accurate measurement and correction of pixel luminance non-uniformity, avoiding aliasing and pixel overlap, while accommodating lower camera resolutions, thus improving image quality and reducing costs by allowing the use of standard resolution cameras.
Implementation Method 1
defocusing the camera such that the focal point of the camera lies outside of a plane passing through the light-emitting devices of the display panel, the defocusing such that individual pixels of the display panel are blurred in images of the display panel captured by the camera
Data Source
AI summary
What is disclosed are systems and methods of optical correction for pixel evaluation and correction for active matrix light emitting diode device (AMOLED) and other emissive displays. Optical correction for correcting for non-homogeneity of a display panel uses sparse display test patterns in conjunction with a defocused camera as the measurement device to avoid aliasing (moiré) of the pixels of the display in the captured images.