LCOS Dark Ring Polarity Segmentation for Fringe Effect Elimination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The fringe effect (bright lines) occurs between the dark ring and adjoining pixels in LCOS displays due to a constant voltage difference, degrading image quality, especially when showing all-black images with frame or line inversion.
Innovation Solution
Divide the dark ring into portions and adjust their polarity to match the adjoining pixels and gate driver scan direction, eliminating the voltage difference by using redundant pixels and a logic circuit to control polarity inversions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dark ring voltage changes from Vτ1 to Vτ10 at time t0 when activating the topmost scan line, then the liquid crystal polarity is inverted to show all-black image, but a constant voltage difference between the dark ring and adjoining pixels on lower scan lines causes fringe effect (bright lines)
Solution Approach 1:
The dark ring is divided into multiple independently controllable portions (e.g., first dark ring portion and second dark ring portion) corresponding to different scan line regions. This segmentation allows each portion to have its voltage adjusted independently to match the polarity of adjoining pixels in its region, eliminating the constant voltage difference that causes fringe effects while maintaining the all-black image display.
2Stability of the object's composition
If the dark ring is biased alternately at voltage Vτ1 and Vτ10 on a frame basis to avoid DC voltage deformation, then liquid crystal deformation is prevented, but a constant voltage difference with adjoining pixels creates fringe effect
Solution Approach 1:
Different portions of the dark ring are assigned different voltage polarities based on their spatial location and the scan direction. For example, when scanning from top to bottom, the first dark ring portion (adjacent to top scan lines) receives voltage of one polarity while the second dark ring portion (adjacent to bottom scan lines) receives voltage of opposite polarity. This local differentiation ensures each portion matches the polarity of its adjoining pixels, eliminating fringe effects while maintaining overall liquid crystal stability through alternating frame-based biasing.
3Productivity
If gate drivers scan from top to bottom with frame inversion, then the display refreshes correctly, but the dark ring voltage change creates constant voltage difference with lower scan line pixels
Solution Approach 1:
The dark ring voltage control is made dynamic by dividing it into multiple portions that can be independently controlled. The voltage applied to each dark ring portion is dynamically adjusted based on the scan direction and the polarity of adjoining pixels in real-time. This dynamic control allows the dark ring to adapt to different scanning patterns (top-to-bottom or bottom-to-top) and inversion modes, eliminating fringe effects while maintaining normal display refresh operation.
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
Significantly reduces the duration of constant voltage differences, minimizing the fringe effect and enhancing image quality without altering the manufacturing process.
Implementation Method 1
liquid crystal contained within pixels will be biased to obtain a zero transmission rate
Data Source
AI summary
A method for driving a dark ring of a liquid-crystal-on-silicon (LCOS) display is provided to prevent the fringe effect (bright lines) due to the constant voltage difference between the dark ring and the adjoining pixels within the LCOS display. A dark ring is divided into a plurality of portions. The polarity of each portion is controlled in accordance with the polarity of the adjoining pixels within the LCOS display and the scan direction of gate drivers such that the polarity inversion for each portion will coincide with that for the adjoining pixels within the LCOS display so as to avoid the fringe effect (bright lines).