Collective Pixel Voltage Compensation for Transistor Aging
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Solution Overview
Problem
Existing display devices face challenges in compensating for transistor changes due to temperature and ambient light variations, leading to inaccurate pixel outputs, as individual pixel compensation is time-consuming and prone to environmental changes during the convergence process.
Innovation Solution
A method is introduced to update parameters for groups of pixels using a Least Mean Square (LMS) adaptive algorithm, grouping pixels based on similar environmental changes, and performing collective updates to compensate for transistor variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If individual pixel compensation is performed, then manufacturing precision of pixel output is improved, but loss of time increases significantly
Solution Approach 1:
The patent merges the compensation process by grouping multiple pixels into pixel groups and performing collective parameter updates for each group rather than individually updating each pixel. This combining approach maintains compensation accuracy while significantly reducing the total convergence time required.
Solution Approach 2:
The patent segments the pixel array into multiple pixel groups, where each group is processed independently with its own parameter updates. This segmentation allows parallel processing of multiple pixels simultaneously, reducing overall convergence time while maintaining individual pixel compensation accuracy.
2Productivity
If fast parameter updates are performed, then productivity is improved, but measurement precision deteriorates due to environmental changes
Solution Approach 1:
The patent implements periodic parameter updates where pixel groups are sequentially updated at regular intervals. This periodic approach allows the system to maintain fast update speeds while ensuring that environmental conditions remain relatively stable during each update cycle, preserving measurement precision.
Solution Approach 2:
The patent performs preliminary measurements of pixel parameters before environmental conditions change significantly, then applies these measurements to calculate compensation parameters. This preliminary action ensures accurate parameter capture while maintaining fast update cycles.
3Loss of time
If collective pixel group updates are performed, then loss of time is reduced, but device complexity increases
Solution Approach 1:
The patent implements a universal control mechanism that can handle both individual pixel compensation and collective pixel group updates through the same hardware infrastructure. This multi-functionality reduces the need for separate complex control systems while enabling fast collective updates.
Solution Approach 2:
The patent introduces pixel group controllers as intermediary components that manage collective updates for groups of pixels. These intermediaries simplify the overall control architecture by handling group-level operations centrally while maintaining individual pixel compensation capabilities.
Data Source
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AI summary
A method for compensating for transistor aging in a display device is presented. The method entails dividing pixels into a plurality of groups including a first group, the first group including Z pixels wherein Z > 1, sampling a pixel current for each pixel in a subset of pixels in the first group, the subset including M pixels wherein 1 ≤ M ≤ Z, determining an ErrorM using the sampled pixel current for the M pixels and a predefined reference current, and adjusting an input voltage for a transistor in more than one of the Z pixels based on the ErrorM. The adjusting of the input voltage may include generating a modified voltage Vd, wherein Vd=A*Vin+B, and each of A and B is determined using ∑M sign(Errorm).