LCD Rolling Backlight Synchronizes Refresh to Reduce Photo Activation
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Solution Overview
Problem
Liquid crystal displays (LCDs) face issues with photo activation of pixel transistors during refresh, leading to saturation and undesirable image quality due to backlight intensity exceeding specified levels, and artifacts like flicker and motion blur from unsynchronized light modulation and emission updates.
Innovation Solution
An independently controllable liquid crystal display system with a data refresh module and a backlight control module that synchronizes a predefined refreshing pattern with a dimming pattern, reducing backlight intensity during data refresh and allowing for variable dimming levels, including full switch-off, to minimize photo activation and artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the backlight illuminates at high intensity to ensure visibility, then the display brightness is improved, but photo activation of pixel transistors occurs during refresh leading to saturation and image quality degradation
Solution Approach 1:
The backlight is operated in periodic on-off cycles synchronized with the refresh cycle of the pixel transistors. During each refresh period when transistors are updating, the backlight is turned off; during non-refresh periods, the backlight is illuminated at high intensity. This periodic action eliminates photo activation while maintaining display brightness.
Solution Approach 2:
The backlight timing is coordinated in advance with the refresh cycle of the pixel transistors. Before the refresh operation begins, the backlight is switched off, and remains off throughout the refresh period. This preliminary action prevents photo activation before it can occur during transistor updating.
2Device complexity
If the backlight is uniformly lit as a single unit, then the manufacturing and control simplicity is maintained, but local dimming capability is lost preventing true black representation in dark scenes
Solution Approach 1:
The backlight is divided into multiple independently controllable backlight units rather than operating as a single uniform source. Each backlight unit can be individually dimmed or turned off, enabling local dimming capability where specific regions can be darkened to achieve true black representation while other regions remain illuminated.
3Adaptability or versatility
If light emitters and light modulating elements are updated independently, then the operational flexibility is maintained, but artifacts such as flicker and motion blur occur due to unsynchronized updates
Solution Approach 1:
The update timing of light emitters (backlight) and light modulating elements (pixel transistors) is merged and coordinated through a synchronized refresh cycle. Both components operate according to the same timing sequence, ensuring that backlight illumination periods align with stable pixel states, thereby eliminating flicker and motion blur artifacts.
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
The solution reduces the likelihood of photo activation and artifacts, enhancing image quality by synchronizing data refresh and backlight dimming, particularly beneficial for moving viewers by reducing smearing and achieving true black representation.
Implementation Method 1
a liquid crystal display (LCD) includes a backlight surface that is configured to produce the backlight
Implementation Method 2
light modulating elements that they illuminate are updated
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A liquid crystal display (LCD) that may include: a plurality of transistors groups forming a pixel array of said LCD, wherein the transistors groups are independently controllable; a plurality of backlight units, forming a backlight surface of said LCD, wherein the backlight units are independently controllable; a data refresh module configured to periodically refresh data at said groups of transistors, at a specified order, over a refresh cycle time; and a backlight control module configured to periodically dim the backlight units at said specified order over a backlight cycle time which is substantially shorter than the refresh cycle time.