LED Backlight Control Device for Luminance and Thermal Management
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Solution Overview
Problem
Existing liquid crystal display devices with LED backlights face issues of reduced luminance and potential luminance unevenness when high input duty is continuously applied, leading to increased temperature and reduced light emission efficiency.
Innovation Solution
A control device that dynamically adjusts the brightness of LED light sources based on luminance information from video signals, alternating between two lower brightness levels (second and third brightness) with longer periods at the second brightness, to maintain luminance while reducing temperature rise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the LED backlight operates continuously at high brightness to maintain video luminance, then the luminance is maintained, but the temperature of the LED increases causing reduced light emission efficiency and shortened lifetime
Solution Approach 1:
The patent applies periodic action by alternating the LED backlight between high brightness and low brightness states in a controlled cycle. The control unit switches the LED backlight on at high brightness during periods when the display shows dark content, then reduces to low brightness or turns off during bright content periods, preventing continuous high-temperature operation while maintaining perceived luminance through temporal integration.
Solution Approach 2:
The patent implements dynamics by making the LED backlight brightness adaptive and variable rather than static. The control unit dynamically adjusts the backlight brightness based on real-time analysis of video content luminance characteristics, switching between different brightness levels to match the display requirements while managing thermal load.
2Temperature
If the LED current is reduced to suppress temperature rising, then the temperature increases are suppressed, but the luminance of the displayed video is reduced
Solution Approach 1:
The patent employs feedback by continuously monitoring the luminance characteristics of the video content being displayed and using this information to control the LED backlight brightness. The control unit analyzes the video signal to determine appropriate backlight levels, creating a closed-loop system that adjusts illumination based on actual display requirements, thereby maintaining luminance while reducing unnecessary thermal load.
Solution Approach 2:
The control unit implements periodic high brightness illumination synchronized with dark content periods in the video, then reduces brightness during bright content periods. This temporal modulation maintains perceived luminance through frame-rate persistence while allowing the LED to cool during low brightness intervals, preventing both luminance loss and excessive temperature rise.
3Power
If part of the light source blocks are turned off to reduce LED current, then power consumption is reduced, but luminance unevenness is caused on the display panel
Solution Approach 1:
The patent divides the backlight into multiple independently controllable light source blocks or LED zones. The control unit can selectively adjust the brightness or turn off specific segments based on the luminance requirements of different display regions, enabling localized power management without affecting overall luminance uniformity. This segmentation allows precise control matching the spatial distribution of video content brightness.
Solution Approach 2:
The patent applies local quality by tailoring the backlight illumination characteristics to the specific requirements of different display regions. The control unit analyzes luminance distribution across the display and adjusts individual light source blocks accordingly, providing higher brightness where needed and reducing or turning off blocks in regions requiring lower illumination, thereby maintaining overall uniformity while optimizing power consumption.
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
This approach effectively suppresses luminance reduction and temperature increase in LED backlights, enhancing light emission efficiency and extending the LED's lifespan without the need for temperature sensors, thus reducing system costs.
Implementation Method 1
A liquid crystal display device includes a backlight having a plurality of light sources (LEDs)... performs lighting of each of the light sources (LEDs) with first brightness
Data Source
AI summary
Reduction of luminance is suppressed while effectively suppressing temperature rising of an LED of a backlight and a peripheral circuit. A backlight driving control unit (8) of a control device (50) included in a liquid crystal display device (10) according to an aspect of the invention increases and reduces, on the basis of two thresholds, power supplied to a backlight, and makes a time during which the power supplied to the backlight (9) is reduced longer than a time during which the power supplied to the backlight (9) is increased.