LCD Display Local Dimming for Object-Area Contrast Control
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Solution Overview
Problem
Existing liquid crystal displays (LCDs) face limitations in local dimming data expression, restricted to 10 bits, which hinders the improvement of contrast ratio and three-dimensional effects, and uniform backlight current application leads to issues like foggy phenomena and reduced expressiveness.
Innovation Solution
A display device with a liquid crystal panel and a backlight unit comprising multiple backlight blocks, controlled by a controller that extracts object areas from an input image, calculates a local dimming gain to enhance luminance, and adjusts current application based on this gain to improve luminance and contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If local dimming data is limited to 10 bits expression range, then device complexity is reduced, but manufacturing precision and luminance control accuracy deteriorate
Solution Approach 1:
The patent transitions from 10-bit to 12-bit local dimming data expression range, adding a new dimension of precision. This dimensional change enables 4096 grayscale levels instead of 1024, significantly improving luminance control accuracy and contrast ratio without fundamentally changing the device architecture.
Solution Approach 2:
The patent changes the data expression parameter from 10-bit to 12-bit, which directly increases the precision of luminance control. This parameter change allows for finer granularity in backlight dimming control, enabling more accurate representation of luminance levels and improving overall image quality.
2Device complexity
If uniform current is applied to all backlight blocks, then device complexity is reduced, but manufacturing precision and contrast ratio deteriorate
Solution Approach 1:
The patent applies different current levels to different backlight blocks based on local image requirements. Instead of uniform current distribution, the system dynamically adjusts current magnitude for each backlight block according to the luminance needs of corresponding image regions, achieving local optimization of contrast and detail visibility.
Solution Approach 2:
The patent implements dynamic current control where the current applied to each backlight block varies in real-time based on the displayed image content. This dynamic adjustment allows the system to optimize contrast ratio and visual quality for different scene requirements, transitioning from static uniform current to adaptive variable current.
3Illumination intensity
If luminance of object area is increased without gain control, then expressiveness is improved, but harmful foggy phenomenon occurs
Solution Approach 1:
The patent implements a feedback control mechanism using local dimming gain to regulate luminance enhancement. The gain value is calculated based on the relationship between object area luminance and background luminance, providing negative feedback to prevent excessive brightness that would cause foggy phenomena. This closed-loop control ensures luminance enhancement remains within optimal visual ranges.
Solution Approach 2:
The patent applies preliminary anti-action by pre-calculating and applying local dimming gain before luminance enhancement. The gain computation anticipates potential foggy phenomena by analyzing luminance ratios in advance, and applies compensatory control to prevent the harmful effect before it occurs, rather than correcting it after visibility degradation.
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
Enhances the expressiveness of objects, improves contrast ratio, and prevents foggy phenomena by dynamically controlling backlight block luminance, thereby increasing viewer immersion.
Implementation Method 1
a backlight unit including a plurality of backlight blocks that provide light to the LCD panel, wherein each of the plurality of backlight blocks includes a plurality of LEDs
Data Source
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AI summary
According to an embodiment of the present disclosure, a display device may comprise a liquid crystal display(LCD) panel, a backlight unit including a plurality of backlight blocks that provide light to the LCD panel, wherein each of the plurality of backlight blocks includes a plurality of LEDs and a controller configured to extract an object area from an input image, obtain a local dimming gain to increase a luminance of the extracted object area, and control a current applied to backlight blocks mapped to the object area based on the obtained local dimming gain.