LED Backlight Color Stability via Temperature Sensor
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Solution Overview
Problem
Liquid crystal display (LCD) devices with edge type backlight units face challenges in maintaining constant color temperature and color reproduction range due to temperature changes, leading to complex and costly LED driving circuits.
Innovation Solution
The LCD employs an LED assembly with red and blue LED chips and a green fluorescent substance, along with a temperature sensor on the LED PCB, to compensate for temperature-induced changes in light intensity, simplifying the LED driving circuit and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a color sensor and complicated LED driving circuit are used to maintain constant color temperature, then color reproduction range is improved, but device complexity and production cost increase
Solution Approach 1:
The invention extracts and removes the color sensor from the system by replacing it with a temperature sensor. The color sensor that was previously needed to detect and compensate for color temperature changes is eliminated, while the temperature sensor detects temperature changes that cause LED wavelength shifts, achieving the same compensation function with simpler components
Solution Approach 2:
The invention substitutes the optical detection mechanism (color sensor detecting light wavelength) with a thermal detection mechanism (temperature sensor detecting temperature changes). This replacement simplifies the system by using temperature measurement instead of complex color measurement, while still enabling compensation for LED color temperature drift
2Stability of the object's composition
If red, green and blue LED chips are used in each LED package, then color reproduction range is improved, but temperature-induced color coordinate changes complicate the driving circuit
Solution Approach 1:
The invention implements a feedback mechanism where the temperature sensor continuously monitors temperature changes in the LED package, and the driving circuit automatically adjusts the drive current to compensate for wavelength shifts. This closed-loop feedback system maintains stable color coordinates by responding to temperature variations in real-time
Solution Approach 2:
The invention changes the operating parameter (drive current) based on temperature measurements to compensate for wavelength shifts. By adjusting the current supplied to the LED chips according to temperature conditions, the system maintains stable color coordinates despite temperature-induced spectral changes
3Stability of the object's composition
If temperature compensation is implemented for all LED chips, then color temperature stability is improved, but production cost increases
Solution Approach 1:
The invention extracts and removes the expensive color sensor from the system, replacing it with a much cheaper temperature sensor. This extraction eliminates the need for costly color detection hardware while maintaining compensation functionality through temperature-based control
Solution Approach 2:
The invention uses a inexpensive temperature sensor instead of an expensive color sensor. The temperature sensor is a much cheaper component that still provides sufficient information for compensation, reducing production costs while achieving the desired color stability
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 stabilizes white light color coordinates across temperature changes, enhances color reproduction range, and reduces production costs by eliminating the need for a color sensor and complex circuitry.
Implementation Method 1
a fluorescent substance emitting the other one color out of the red, green and blue
Data Source
AI summary
A liquid crystal display device includes a backlight unit including an LED assembly, wherein the LED assembly includes: a plurality of LED packages; an LED PCB on which the plurality of LED packages are arranged being spaced apart from each other; and an LED driving circuit board that is connected to the LED PCB and includes a LED driving circuit, wherein the LED package includes first and second LED chips emitting two colors, respectively, out of red, green and blue, and a fluorescent substance emitting the other one color out of the red, green and blue, wherein a temperature sensor is formed in the LED PCB, and wherein the first or second LED chip is supplied with a compensated voltage according to temperature change by the temperature sensor.