Display Pipeline Variable Refresh Rate Charge Management
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Solution Overview
Problem
Dynamic adjustments in frame refresh rates on displays can lead to long-term charge accumulation on liquid crystal display panels, particularly when the frame refresh rate cadence matches the polarity inversion cadence, causing visual artifacts and image quality issues.
Innovation Solution
Implementing a display pipeline that enforces an even number of frames at higher refresh rates before switching to lower rates, and overriding settings to ensure an even frame count, thereby preventing charge accumulation by alternating polarity on consecutive frames and managing frame refresh rate changes to mitigate charge buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the frame refresh rate is dynamically adjusted to match content requirements, then power consumption is optimized and display efficiency is improved, but charge accumulation occurs on the liquid crystal layer causing visual artifacts
Solution Approach 1:
The patent implements dynamic frame refresh rate adjustment that adapts to content requirements, allowing the display to switch between different refresh rates (e.g., 60Hz, 30Hz, 120Hz) based on the temporal characteristics of the displayed content. This dynamic adaptation optimizes power consumption while maintaining display quality.
Solution Approach 2:
The patent applies periodic polarity inversion to the liquid crystal layer, alternating the electric field direction between consecutive frames. This periodic action prevents charge accumulation by ensuring that ions and charged particles in the liquid crystal do not build up in one direction, thereby eliminating visual artifacts while maintaining the benefits of variable refresh rates.
2Reliability
If polarity inversion is applied to prevent charge accumulation, then image quality is maintained, but visual artifacts occur when frame refresh rate cadence matches polarity inversion cadence
Solution Approach 1:
The patent introduces asymmetry in the timing relationship between frame refresh rate changes and polarity inversion. By deliberately misaligning the cadence of frame rate transitions with the polarity inversion sequence, the system prevents synchronous accumulation patterns that cause visual artifacts while maintaining the protective effect of polarity inversion against charge buildup.
Solution Approach 2:
The patent predicts potential charge accumulation scenarios by analyzing the relationship between frame refresh rates and polarity inversion timing. When a problematic cadence match is detected, the system preemptively adjusts the frame refresh rate or polarity inversion timing to prevent visual artifacts before they occur, ensuring continuous image quality.
3Use of energy by moving object
If frame refresh rate is reduced to save power, then energy consumption decreases, but charge holds longer causing increased charge accumulation
Solution Approach 1:
The patent applies periodic polarity inversion at frequencies that are independent of the frame refresh rate. Even when the display operates at lower refresh rates (e.g., 30Hz) to reduce power consumption, the polarity inversion continues at its own periodic cycle, ensuring that charge accumulation is prevented regardless of how long individual frames are held on the display.
Solution Approach 2:
The patent introduces polarity inversion as an intermediary mechanism that mediates between the frame refresh rate and charge accumulation. This intermediary action decouples the relationship between frame hold time and charge buildup, allowing the system to reduce power consumption through lower refresh rates without proportionally increasing charge accumulation risks.
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
This approach effectively prevents long-term charge accumulation on the display panel, maintaining image quality and reducing visual artifacts associated with dynamic frame refresh rate adjustments.
Implementation Method 1
a liquid crystal layer and various circuitry for controlling orientation of liquid crystals within the layer to modulate an amount of light passing through the LCD panel
Implementation Method 2
periodic inversion of the electric field may be applied to the liquid crystal layer of the display to prevent the biasing of the liquid crystal layer
Data Source
AI summary
Systems, apparatuses, and methods for preventing charge accumulation on a display panel of a display. A display pipeline is configured to drive a display using a variable frame refresh rate. The display may also be driven by a polarity inversion cadence to alternate the polarity on the display panel on back-to-back frames. In some cases, the frame refresh rate cadence, as specified in frame packets which contain configuration data for processing corresponding frames, can cause a charge accumulation on the display panel if an odd number of frames are displayed at a first frame refresh rate before switching to a second frame refresh rate. Accordingly, in these cases, the display pipeline may override the frame refresh rate setting for a given frame to cause an even number of frames to be displayed at the first frame refresh rate.