Local Dimming Duty Compensation for LCD Flicker Reduction
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Solution Overview
Problem
In liquid crystal display (LCD) panels using local dimming for light source control, flicker occurs due to luminance differences caused by variations in the driving duty of light-emitting blocks, especially when moving images with high gradation in dark backgrounds are displayed, leading to reduced display quality.
Innovation Solution
A method and apparatus that determine the duty of light-emitting blocks using block representative values from divided image blocks, comparing previous and current frame values to detect luminance shifts and compensate the duty of adjacent blocks to minimize flicker, thereby maintaining consistent luminance and reducing flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If local dimming control is applied to light-emitting blocks based on gradation average value, then power consumption is reduced and luminance control is improved, but flicker occurs due to luminance differences between adjacent blocks when images move
Solution Approach 1:
The patent applies preliminary action by predicting the duty of adjacent light-emitting blocks based on current and previous frame data before displaying the current frame. This prediction compensates for luminance shifts that would otherwise cause flicker, allowing the system to maintain display quality while using local dimming for power savings.
Solution Approach 2:
The patent implements feedback by comparing the predicted duty with the actual duty of adjacent light-emitting blocks and adjusting the prediction accordingly. This feedback mechanism ensures that luminance differences between adjacent blocks are minimized, preventing flicker while maintaining the power-saving benefits of local dimming.
2Illumination intensity
If duty of light-emitting blocks is varied according to image position, then luminance control is achieved, but luminance differences are generated between adjacent blocks causing flicker
Solution Approach 1:
The patent applies preliminary action by calculating and compensating for luminance shifts in adjacent light-emitting blocks before displaying each frame. This ensures that luminance consistency is maintained across block boundaries even when duty varies according to image position, preventing flicker while preserving luminance control.
3Device complexity
If block representative value is used to determine duty, then calculation complexity is reduced, but luminance shifting between adjacent blocks is not detected
Solution Approach 1:
The patent applies preliminary action by comparing block representative values from current and previous frames to predict luminance shifts before they manifest as visible flicker. This approach maintains low calculation complexity while enabling detection and compensation of luminance shifting between adjacent blocks.
Data Source
AI summary
A light source apparatus includes a light source, a duty determining part, a luminance shifting determining part and a duty compensation part. The light source includes a plurality of light-emitting blocks. The duty determining part determines a duty of light-emitting blocks by using a block representative value obtained from a plurality of image blocks that are divided in accordance with a plurality of light-emitting blocks. The luminance shifting determining part compares block representative values of a previous frame with block representative values of a current frame to determine whether a luminance shifting is generated at an adjacent light-emitting block. The duty compensation part compensates a duty of the adjacent light-emitting blocks when the luminance shifting is generated at the adjacent light-emitting blocks. Thus, the duty of the adjacent light-emitting blocks determined as a block representative value is compensated so that an occurrence of flicker may be decreased.