Backlight Device LED Density Current Control
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Solution Overview
Problem
Backlight devices for liquid crystal display devices face challenges in maintaining optimal LED brightness and longevity due to temperature-dependent characteristics, where densely arranged LEDs tend to overheat and sparsely arranged LEDs have lower brightness, necessitating controlled current supply based on arrangement density.
Innovation Solution
A backlight device with a substrate divided into densely and sparsely arranged LED areas, featuring a control unit that adjusts current supply to each area differently based on temperature, with a greater rate of decrease in current for densely arranged LEDs to manage heat and maintain image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If LEDs are densely arranged to increase brightness, then illumination intensity is improved, but temperature increases causing quality and lifetime degradation
Solution Approach 1:
The patent segments the LED array into multiple groups based on spatial position and arrangement density. Different current control strategies are applied to each segment: densely arranged LEDs receive current reduction at lower temperature thresholds, while sparsely arranged LEDs maintain higher current levels. This segmentation allows simultaneous optimization of brightness and reliability across different regions.
Solution Approach 2:
The patent implements local quality control by applying differentiated current adjustment rates to different LED groups. The control unit calculates separate temperature thresholds and current reduction rates for densely arranged versus sparsely arranged LEDs. This ensures that each region operates with optimal quality characteristics appropriate to its specific arrangement density and thermal environment.
2Reliability
If current is reduced to lower temperature, then reliability is improved, but brightness decreases
Solution Approach 1:
The patent implements dynamic current control that continuously adjusts LED operating current based on real-time temperature measurements and spatial position. The control unit dynamically calculates optimal current levels by considering both temperature thresholds and arrangement density, allowing the system to adaptively balance reliability and brightness rather than using fixed current reduction.
Solution Approach 2:
The patent changes multiple parameters simultaneously to resolve the contradiction: it adjusts current magnitude, current reduction rate, and temperature thresholds based on LED spatial position and arrangement density. By varying these parameters dynamically, the system maintains higher brightness where LEDs are sparsely arranged while applying more aggressive current reduction only where densely arranged LEDs generate excessive heat.
3Ease of operation
If uniform current is supplied to all LEDs, then ease of operation is improved, but image quality deteriorates due to temperature variations in different areas
Solution Approach 1:
The patent segments the uniformly controlled LED population into multiple groups based on spatial position and arrangement density. Each segment receives customized current control parameters including different temperature thresholds and current reduction rates. This segmentation maintains operational simplicity through automated control while achieving the image quality necessary for different display regions.
Solution Approach 2:
The patent implements feedback control by continuously monitoring temperature at multiple locations and using this information to adjust current supply to different LED groups. The control unit receives temperature feedback, calculates appropriate current adjustments based on pre-stored thresholds and reduction rates, and applies corrective current modifications to maintain uniform image quality across the display area despite temperature variations.
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 solution prevents quality and lifetime degradation of LEDs and improves image quality by managing heat and brightness distribution, reducing manufacturing costs and enhancing reliability.
Implementation Method 1
a plurality of first Light Emitting Diodes (LEDs) arranged in the first area
Implementation Method 2
When current is supplied to an LED, the LED generates heat
Data Source
AI summary
A backlight device, used in a liquid crystal display device, comprising: a substrate including first and second areas; a plurality of first light emitting diodes (LEDs) arranged in the first area at a density equal to or higher than a predetermined density; a plurality of second LEDs arranged in the second area at a density lower than the predetermined density; and a control unit configured to control current supplied to the first LEDs with respect to the temperature of the first area, and current supplied to the second LEDs with respect to the temperature of the second area so as to make the rate of change in effective value of the current supplied to the first LEDs different from the rate of change in effective value of the current supplied to the second LEDs when temperatures of the first and second areas are higher than a predetermined temperature.