LED Backlight Thermistor Placement for Color Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Area-active backlights in liquid crystal display devices face challenges in maintaining stable color temperature and luminance due to varying temperatures among LEDs, as existing techniques fail to accurately detect and control the temperature of individual LEDs in real-time.
Innovation Solution
The solution involves a configuration where a temperature detecting section is placed in a polygonal area surrounded by luminous bodies, allowing it to accurately detect temperatures without being affected by heat generated by the driving section, enabling efficient temperature corrections and stable color temperature and luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature detecting section is placed near the driving section to detect LED temperatures, then temperature detection accuracy improves, but the detection is affected by heat generated by the driving section
Solution Approach 1:
The temperature detecting section is extracted from the polygonal area surrounded by luminous bodies and placed in a different location. This separates the detection function from the heat-generating driving section, allowing accurate temperature measurement without thermal interference while maintaining the ability to detect LED temperatures for compensation control.
Solution Approach 2:
The patent introduces a temperature detecting section that acts as an intermediary element located in a polygonal area surrounded by luminous bodies but outside the driving section's heat influence zone. This intermediary position enables indirect temperature detection of LEDs without direct thermal contact with the driving section, resolving the contradiction between detection accuracy and heat interference.
2Illumination intensity
If area-active backlight control is implemented to control luminance for each area, then display quality improves, but temperature distribution becomes non-uniform and difficult to control
Solution Approach 1:
The backlight is divided into multiple luminous bodies arranged in a matrix, with each luminous body or group controllable independently. The driving section controls individual luminous bodies based on video signals, enabling area-active backlight control. Temperature compensation is applied segmentally to maintain color temperature stability across different illumination levels.
Solution Approach 2:
The patent employs temperature compensation by changing the driving parameters (current, voltage) of luminous bodies based on detected temperature values. When temperature increases causing color temperature shift, the driving parameters are adjusted to compensate and maintain stable color temperature despite non-uniform temperature distribution from area-active operation.
3Use of energy by moving object
If LEDs are driven at high power to improve luminance efficiency, then brightness output improves, but temperature increases causing color temperature instability
Solution Approach 1:
The patent implements a feedback control system where the temperature detecting section continuously monitors temperatures in the polygonal area, and the driving section adjusts driving parameters based on detected temperature values. This closed-loop feedback maintains color temperature stability by compensating for temperature-induced variations even when operating at high luminance efficiency.
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 configuration ensures stable color temperature and luminance in liquid crystal display devices by accurately detecting and correcting temperatures, improving the performance and efficiency of the backlight system.
Implementation Method 1
a temperature detecting section disposed in an area surrounded by the plurality of luminous bodies... detect a temperature in the polygonal area in which the temperature detecting section is disposed
Data Source
AI summary
An illumination device includes an LED package, an LED driver including an FET, and a thermistor disposed on a substrate. A plurality of such LED packages are disposed on the substrate such that a first area and a second area, each determined by vertices corresponding to LED packages, are defined on the substrate. The thermistor is disposed in the first area, and the FET is disposed in the second area, which is outside of the first area. The thermistor detects a temperature in the first area. Such a configuration allows the thermistor to detect, in accordance with the temperature in the area, the temperature of heat transferred from the LED packages, without being affected by heat generated by the FET. This makes it possible to efficiently make temperature corrections to stabilize color temperature and luminance.