Active Matrix Display Driving Method for Motion Blur Reduction
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Solution Overview
Problem
Active-matrix display devices, such as AMLCD panels, suffer from motion blur due to the response time of liquid crystals, which existing techniques like overdriving and black frame insertion often fail to fully address, resulting in artifacts like ghost images and double-edge images.
Innovation Solution
The method involves dividing each image frame into displayed frame portions followed by darker frame portions, with the temporal separation between them being less than a frame time, allowing pixel luminance to diminish, and adjusting image data and charging times to balance luminance across frame periods, using multiple gate line drivers and control signals to manage pixel charging and discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the response time of liquid crystal is reduced by overdriving, then motion blur is reduced, but artifacts such as ghost image and double-edge image occur
Solution Approach 1:
The frame period is divided into multiple sub-frames, with each sub-frame displaying a portion of the image data. This segmentation allows the liquid crystal to respond to incremental luminance changes rather than abrupt transitions, reducing motion blur without causing the artifacts associated with overdriving.
Solution Approach 2:
The patent applies periodic black frames interspersed among the sub-frames. These black frames periodically reset the liquid crystal state, preventing the accumulation of residual luminance that causes ghost images, while the rhythmic pattern of sub-frames maintains smooth motion perception.
2Speed
If black frame insertion technique is used to reduce motion blur, then response time is improved, but ghost image artifacts occur
Solution Approach 1:
Instead of inserting complete black frames that cause ghost images, the patent segments the frame into multiple sub-frames with incremental luminance transitions. This segmentation achieves the response time improvement of black frame insertion without the harmful ghost image artifact by maintaining continuous image data throughout the sub-frames.
3Stability of the object's composition
If image data is provided continuously for the entire frame time, then luminance stability is maintained, but motion blur occurs due to liquid crystal response time
Solution Approach 1:
The patent dynamically adjusts the luminance level in each sub-frame, transitioning from lower luminance in earlier sub-frames to higher luminance in later sub-frames. This dynamic approach allows the liquid crystal to track the changing luminance requirements throughout the frame period, achieving both fast response and stable final luminance.
Solution Approach 2:
The patent applies preliminary overdrive voltages in the initial sub-frames to accelerate the liquid crystal response before transitioning to the final luminance level. This preliminary action reduces the overall response time while maintaining luminance stability by the end of the frame period.
Data Source
AI summary
A method for driving an active matrix display wherein each image frame is divided into a number of displayed frame portions, each of which is followed by a darker frame portion. The image data in the darker frame portion is removed so as to allow the pixel luminance to diminish. The temporal separation between the displayed frame portion and the following darker frame portion is smaller than a frame time. In a display where the lines are driven repetitively for forming the display image in a plurality of frame times, the image data provided to a pixel, after the luminance in that pixel changes from low to high, is adjusted so that the brightness of the pixel in the preceding frame times appear higher or not lower than that in following frames times.