LED Backlight Control with Data Range Conversion
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Solution Overview
Problem
LCD backlight systems using LEDs face challenges in maintaining accurate control of light luminance due to varying luminance characteristics and temperature effects, leading to potential white balance issues, especially when LEDs deteriorate and exceed the control range of the controller.
Innovation Solution
A method and apparatus that convert sensing data exceeding the control range into a format within the control range by calculating a slope-based conversion, allowing for accurate control of light emission from RGB LEDs through a data converter and controller, ensuring consistent color coordinate and luminance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PWM control is used to control LED luminance, then power consumption is reduced and color reproducibility is improved, but when LEDs deteriorate the sensing data exceeds the control range making accurate control impossible
Solution Approach 1:
The patent applies dynamics by making the control system adaptive to changing LED characteristics over time. The controller dynamically adjusts the PWM duty cycle based on real-time sensing data from color sensors, allowing the system to compensate for LED deterioration and maintain accurate color control throughout the LED lifespan.
Solution Approach 2:
The patent changes the control parameter from fixed PWM duty cycle to dynamically adjusted duty cycle based on sensing data. By monitoring the actual light output and comparing it with target values, the system adjusts the PWM parameters to maintain accurate color control even as LED characteristics change due to aging or temperature effects.
2Measurement precision
If color sensors detect RGB light amounts to maintain white balance, then color accuracy is improved, but when LEDs deteriorate the detected amounts exceed the controller's control range
Solution Approach 1:
The patent implements feedback control by using color sensors to continuously monitor the actual RGB light output and comparing it with target values. The controller adjusts the PWM duty cycles for each LED based on the difference between detected and target values, creating a closed-loop system that maintains accurate white balance even when LEDs deteriorate.
Solution Approach 2:
The patent performs preliminary calibration by storing reference color values in a lookup table (LUT) during manufacturing. This pre-established reference data enables the controller to quickly compare actual sensor readings against target values and make immediate corrections, maintaining color accuracy without requiring complex real-time calculations.
3Illumination intensity
If sensing data exceeds maximum reference data value, then the LED luminance is too high for accurate control, but reducing LED output loses the ability to provide sufficient light
Solution Approach 1:
The patent applies dynamics by making the control system adaptive to changing LED characteristics over time. The controller dynamically adjusts the PWM duty cycle based on real-time sensing data from color sensors, allowing the system to compensate for LED deterioration and maintain accurate color control throughout the LED lifespan.
Solution Approach 2:
The patent uses partial action by adjusting only the PWM duty cycle parameter while keeping the LED operating current within safe limits. This allows the system to reduce effective light output through pulse-width modulation rather than reducing the actual LED drive current, maintaining both control precision and LED safety.
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
Enables precise control of light emission from LEDs, maintaining target color and luminance values even when sensing data exceeds the control range, thereby addressing the issue of deteriorated LEDs and ensuring stable white balance.
Implementation Method 1
light-emitting diodes (LEDs) have been employed for the backlight assembly
Implementation Method 2
Red light, green light and blue light emitted from the RGB LEDs
Implementation Method 3
the backlight assembly detects the amounts of light by using a color sensor having a sensitivity of wavelengths corresponding to each of the RGB LEDs
Data Source
AI summary
A light source apparatus includes a light source module, a light sensor, a data converter, a light source controller and a light source driver. The light source module includes a light source. The light sensor generates sensing data by sensing the amount of light generated from the light source. The data converter converts the sensing data which exceeds a maximum value of reference data of a control range into converted sensing data within the control range. The light source controller generates a control signal for controlling the amount of light from the light source based upon the sensing data corresponding to no more than the maximum value or based upon the converted sensing data. The light source driver drives the light source by providing the light source with a driving signal based upon the control signal.