Zoned Backlight Timing for Motion-Blur-Free LCD Scanning
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Solution Overview
Problem
The phenomenon of motion blur occurs in liquid crystal display devices due to the human eye observing transitional and final gray scales when the backlight is turned on before liquid crystals complete their rotation during gray scale transitions.
Innovation Solution
A control method for a display device with a display panel and backlight zones that are illuminated sequentially in a row-by-row scanning manner, ensuring the backlight is turned on after liquid crystals have fully rotated, and turned off before the next frame starts, with specific timing conditions to prevent overlap and halo formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the backlight is turned on during the gray scale transition period, then the display can be illuminated continuously, but motion blur occurs due to observing transitional and final gray scales simultaneously
Solution Approach 1:
The backlight is turned on in advance before the gray scale transition is complete, specifically timed to illuminate at the moment the liquid crystal rotation finishes. This preliminary timing action ensures that the backlight only illuminates the final stable gray scale image, preventing motion blur while maintaining continuous illumination.
Solution Approach 2:
The patent changes the timing parameter of backlight illumination from continuous or early activation to a precisely controlled delay timing. By adjusting the illumination timing parameter to coincide with the completion of liquid crystal rotation, the system eliminates motion blur while maintaining image continuity.
2Illumination intensity
If the backlight is turned on early to ensure continuous illumination, then lighting coverage is maintained, but the light-emitting area extends beyond the display zone creating halo effects
Solution Approach 1:
The patent applies local quality control by dividing the backlight into multiple independently controllable zones that correspond to display zones. Each backlight zone is illuminated only when its corresponding display zone is being scanned, ensuring light is emitted only where and when needed, thereby preventing halo effects while maintaining adequate illumination coverage.
3Area of stationary object
If multiple backlight zones are illuminated simultaneously to cover the entire display area, then complete illumination is achieved, but the complexity of timing control increases
Solution Approach 1:
The backlight device is segmented into multiple independently controllable backlight zones that correspond to display zones. This segmentation allows each zone to be controlled separately based on the row scanning progress, simplifying the timing control logic compared to illuminating the entire backlight simultaneously or using a single unified control signal.
Solution Approach 2:
The backlight control system dynamically adjusts which zones are illuminated based on the real-time scanning progress of the display panel. The illumination state of each backlight zone changes dynamically during the row scanning process, optimizing the illuminated area at each moment while maintaining manageable control complexity through systematic timing rules.
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
Prevents motion blur by ensuring backlight illumination aligns with liquid crystal rotation, maintaining image clarity and reducing visual artifacts.
Implementation Method 1
a liquid crystal layer, wherein a response time from when a voltage is applied to liquid crystals in the liquid crystal layer to when the liquid crystals rotate to a target gray scale is t3
Implementation Method 2
The backlight device includes a plurality of backlight zones that emit light independently
Data Source
AI summary
A control method for a display device including a display panel and a backlight device is provided. The display panel includes multiple display zones. The backlight device includes multiple backlight zones. The backlight zones are sequentially illuminated. The illumination time when the first backlight zone is illuminated satisfies followings: t1≥(m/n+a)×t2+t3, t1 is the time from the start of displaying each frame of an image to the illumination of the first backlight zone, m is the number of pixel rows, n is the number of the backlight zones, a is the number of pixel rows occupied by a portion of a light-emitting area that extends beyond the corresponding backlight zone when the backlight zone is illuminated, t2 is the scanning time for each pixel row of the display panel, and t3 is response time when the pixel row receives a row scanning signal.