OLED Compensation Module Reducing Memory for LTPS Mura
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Solution Overview
Problem
Active matrix OLED displays using amorphous silicon (a-Si) or low temperature poly silicon (LTPS) thin film transistors (TFTs) face inconsistent performance issues leading to mura phenomena, which result in non-uniform display appearances and require large memory capacity for storing threshold voltage and pixel mobility values for compensation.
Innovation Solution
An image compensation module that stores target and reference current values corresponding to gray levels, using a gamma parameter to calculate compensation gray levels, reducing memory requirements and enabling precise color display with high image quality by compensating for irregularities in LTPS TFTs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If threshold voltage and pixel mobility values are stored for each pixel to compensate mura phenomena, then display uniformity is improved, but memory capacity requirements increase significantly
Solution Approach 1:
The patent segments the compensation data by gray level instead of storing complete pixel-level lookup tables. It divides the compensation parameters into separate components: a first set of parameters for a first gray level and a second set of parameters for a second gray level, allowing selective retrieval and processing of only the necessary data portions for each display condition.
Solution Approach 2:
The patent extracts only the essential compensation parameters needed for each gray level from the complete pixel data, separating the compensation task into independent gray-level processing stages. This extraction approach removes unnecessary data while retaining the critical compensation information required for uniform display.
2Productivity
If LTPS TFTs are used to increase pixel aperture ratio and reduce manufacturing costs, then device performance is improved, but inconsistent performance properties cause mura phenomena
Solution Approach 1:
The patent performs preliminary compensation parameter measurement and storage during the manufacturing process. By measuring and storing threshold voltage and mobility values for each pixel and gray level during fabrication, the system prepares compensation data in advance, allowing precise color display to be achieved without requiring perfect manufacturing consistency.
Solution Approach 2:
The patent dynamically adjusts driving parameters (voltage or current) based on measured pixel characteristics and gray level requirements. By changing the driving parameters according to each pixel's specific threshold voltage and mobility values, the system compensates for LTPS TFT performance variations and achieves uniform display appearance.
Data Source
AI summary
One embodiment of the invention includes an image compensation module, an OLED display panel, and an OLED display apparatus. A target current value corresponding to a target gray level is stored in a compensation memory portion. A reference gray level and a reference current value corresponding to the reference gray level are stored in a reference memory portion. A compensation gray level can be obtained by an arithmetic compensation unit according to the target current value, reference gray level, reference current value, and gamma parameter. This may reduce the memory space needed for the compensation and reference memory portions, and compensate the images of the display apparatus and panel so that precise colors can be displayed with a high image quality.