LED Backlight Uniformity Control via Color Sensor Feedback
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Solution Overview
Problem
Liquid crystal display (LCD) devices using backlight units with light emitting diodes (LEDs) face challenges in achieving uniform brightness distribution and compensating for brightness deviations caused by heat, which affect the performance and application of LEDs in LCD backlight units.
Innovation Solution
A light device comprising a backlight unit with a light emitting diode (LED) array, color sensors for feedback on wavelength and light amount, and a controller that calculates average, maximum, and minimum values to adjust the duty ratio of pulse width modulation (PWM) driving power, ensuring uniform brightness and compensating for heat-induced deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If LED backlight units are used to illuminate LCD devices, then energy efficiency and longevity are improved, but uniform brightness distribution deteriorates due to heat-induced deviations
Solution Approach 1:
The patent employs color sensors to detect the actual brightness and color output of LED backlight units, feeding this information back to a controller. The controller adjusts the driving current of individual LED groups based on the feedback signals, compensating for brightness deviations caused by heat and achieving uniform illumination across the display panel.
Solution Approach 2:
The patent divides the LED backlight into multiple independent LED groups with individual color sensors and control circuits. Each LED group is controlled separately based on local brightness measurements, allowing localized compensation for heat-induced variations and achieving overall uniformity while maintaining energy efficiency.
2Illumination intensity
If multiple color sensors and control circuits are added to achieve uniform brightness, then brightness uniformity is improved, but device complexity increases
Solution Approach 1:
The patent segments the LED backlight system into multiple independently controllable groups, each with its own color sensor and control circuit. This segmentation allows for distributed control that achieves uniformity without requiring a single complex centralized control system, thereby managing device complexity through modular architecture.
Solution Approach 2:
The patent uses universal control circuits that can manage multiple LED groups with the same control logic and hardware architecture. The color sensors serve multiple functions by detecting both brightness and color information, reducing the need for separate sensing systems and thereby controlling overall device complexity while maintaining brightness uniformity.
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
The solution achieves stable and accurate control of LED brightness, ensuring uniformity and performance across the LCD panel, effectively addressing heat-related brightness deviations and maintaining consistent light output.
Implementation Method 1
a light emitting diode device for providing light
Implementation Method 2
a plurality of color sensors for sensing a wavelength and an amount of light from the light emitting diode device to transmit sensed values as feedback
Implementation Method 3
a backlight unit driver for supplying driving power comprising a duty ratio of pulse width modulation to the light emitting diode device
Data Source
AI summary
Provided is a light device. The light device according to one embodiment comprises a backlight unit, a plurality of color sensors, a backlight unit driver, and a backlight unit controller. The backlight unit comprises a light emitting diode device to provide light. The plurality of color sensors senses a wavelength and an amount of light from the light emitting diode device to transmit sensed values as feedback. The backlight unit driver supplies driving power having a duty ratio of pulse width modulation to the light emitting diode. The backlight unit controller receives the sensed values to calculate an average value, a maximum value, a median value, and a minimum value, and then controls the duty ratio using the average value, the maximum value, the median value, and the minimum value.