LCD Overdrive Diagonal Interpolation Circuit
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Solution Overview
Problem
Current LCD technologies face challenges with slow intermediate gray scale response, leading to poor dynamic contrast and display artifacts like 'ghosting,' 'blurring,' and 'streaking' due to their fundamental characteristics, which existing response time compensation methods, such as bi-linear interpolation, fail to adequately address, especially when interpolating gray levels along the diagonal.
Innovation Solution
An LCD overdrive interpolation circuit and method that performs diagonal interpolation followed by further interpolation, ensuring the final gray level equals the FROM and TO gray levels, using specific formulas depending on the interpolation target's position relative to the diagonal, thereby guaranteeing accurate interpolation and avoiding discontinuities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If bi-linear interpolation is used for LCD overdrive, then intermediate gray scale response is improved, but discontinuities and artifacts occur when interpolating along the diagonal
Solution Approach 1:
The patent segments the interpolation process into two distinct stages: first performing diagonal interpolation along the diagonal direction using LUT entries (0,0), (1,1), (2,2), etc., then performing orthogonal interpolation perpendicular to the diagonal. This segmentation resolves the contradiction by handling diagonal cases specially to avoid the discontinuities that plague standard bi-linear interpolation, while still achieving fast gray scale response through the overdrive mechanism.
Solution Approach 2:
The patent applies different interpolation methods based on the local characteristics of the data. When the FROM and TO gray levels are equal or nearly equal (diagonal case), it uses diagonal interpolation with a unity function to ensure continuity. When they differ significantly, it uses standard orthogonal interpolation. This local adaptation eliminates artifacts while maintaining fast response throughout the entire gray scale range.
2Quantity of substance
If a 17x17 FROM-TO LUT is used instead of a full 256x256 LUT, then memory requirements are reduced, but interpolation errors increase for non-entered gray levels
Solution Approach 1:
The patent changes the interpolation dimension by introducing diagonal interpolation along the (0,0)-(1,1)-(2,2) direction as a first pass. This diagonal dimension provides additional constraints and information that improve precision. By interpolating along the diagonal first and then performing orthogonal interpolation, the method achieves higher accuracy than standard bi-linear interpolation while maintaining the compact 17x17 LUT structure.
3Loss of time
If overdrive is applied to achieve fast gray scale transitions, then response time is reduced, but display artifacts like ghosting and streaking occur
Solution Approach 1:
The patent incorporates feedback by using the diagonal interpolation results to guide the orthogonal interpolation step. The diagonal interpolation provides a reference value that ensures the final interpolated result remains consistent with the diagonal constraint (when FROM=TO, result=FROM). This feedback mechanism eliminates the artifacts caused by aggressive overdrive while maintaining fast transition times.
Data Source
AI summary
A liquid crystal display (LCD) overdrive interpolation circuit and method, and an LCD drive system incorporating the circuit or method. In one embodiment, the circuit includes: (1) a diagonal interpolator operable to perform a diagonal interpolation along a diagonal direction in a lookup table based on TO and FROM gray levels and (2) a further interpolator coupled to the diagonal interpolator and operable to perform a further interpolation based on a result of the diagonal interpolation and the FROM gray level.