Spatiotemporal Dithering Phase Control for LCD Charge Imbalance
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Solution Overview
Problem
Spatiotemporal dithering in LCDs leads to voltage and pixel charge imbalances, resulting in undesirable image artifacts due to the combination of reduced data bits for color representation and inversion techniques.
Innovation Solution
A method involving a graphics processor that periodically or aperiodically skips or alters spatiotemporal dithering patterns or phases, using a counter, timer, or charge monitoring to manage pixel charge thresholds, thereby preventing voltage and charge imbalances and eliminating image artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dithering is applied to simulate 8-bit colors using 6-bit data, then color resolution is improved, but image artifacts are generated due to voltage and charge imbalances
Solution Approach 1:
The patent applies periodic action by implementing frame-based polarity inversion where the polarity of voltage signals is alternated between consecutive frames. This periodic inversion prevents cumulative charge buildup in LCD pixels while maintaining dithering benefits, thereby eliminating image artifacts caused by charge imbalance
Solution Approach 2:
The patent converts the harmful effect of voltage polarity alternation (which causes display inversion) into a beneficial solution by synchronizing the polarity inversion with dithering patterns. The harmful charge imbalance is transformed into a controlled periodic phenomenon that can be compensated through algorithmic adjustment of dithering phases
2Reliability
If voltage polarity is alternated to prevent pixel damage, then pixel reliability is improved, but charge imbalance occurs leading to display inversion
Solution Approach 1:
The patent implements feedback by monitoring the frame number and using it to control the polarity inversion pattern. The system adjusts dithering patterns based on feedback from previous frame polarities, ensuring that charge balance is maintained while continuing to protect pixels from damage through alternating voltages
3Speed
If 6-bit color data is used instead of 8-bit, then response time is improved, but color depth is reduced
Solution Approach 1:
The patent uses dithering as an intermediary technique that bridges the gap between 6-bit and 8-bit color representation. By applying spatial and temporal dithering patterns, the system creates the perceptual effect of additional color levels beyond what 6-bit data can directly represent, thus recovering the apparent color depth while maintaining fast 6-bit response times
Data Source
AI summary
Devices and methods for reducing or eliminating spatiotemporal dithering image artifacts are provided. By way of example, a method includes providing positive polarity and negative polarity data signals to a plurality of pixels of a display during a first frame period, in which the first frame period corresponds a first spatiotemporal rotation phase. The method includes providing the positive polarity signals and the negative polarity signals to the plurality of pixels of the display during a second frame period, in which the second frame period corresponds a second spatiotemporal rotation phase. A spatiotemporal rotation phase sequence provided to the display comprises the first spatiotemporal rotation phase and the second spatiotemporal rotation phase. One of the first spatiotemporal rotation phase and the second spatiotemporal rotation phase of the spatiotemporal rotation phase sequence is altered during the first frame period or the second time period.