Display Optical Feedback via Intensity Sensor
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Solution Overview
Problem
Current LCD devices face challenges with complex and expensive optical feedback systems that fail to account for light degradation due to liquid crystal material changes, leading to inefficient compensation for LED degradation.
Innovation Solution
A display device with a low-cost optical feedback system that includes light sources emitting different wavelengths, electro-optical elements, and a sensor to measure light intensity, controlled by a system that adjusts illumination parameters based on measured data to compensate for degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional color sensors with color filters are used to measure LED intensity, then LED degradation can be compensated, but the system becomes complicated and expensive
Solution Approach 1:
The patent extracts the color filter from the optical feedback system, using only a simple intensity sensor without color filtering. The system measures total light intensity from the backlight unit and uses this information to compensate for LED degradation, eliminating the need for complex color filter arrays while maintaining compensation functionality
Solution Approach 2:
The patent replaces expensive color sensors with inexpensive simple intensity sensors. By using a basic photodetector or photosensor that only measures overall light intensity rather than spectral composition, the system achieves cost-effective LED degradation compensation without requiring sophisticated measurement equipment
2Measurement precision
If light intensity is measured in the backlight unit, then LED degradation can be monitored, but changes in spectral content from light passing through liquid crystal material are not accounted for
Solution Approach 1:
The patent implements a feedback loop where the intensity sensor continuously monitors light output from the display, and the controller adjusts LED drive current based on measured intensity variations. This closed-loop feedback compensates for both LED degradation and liquid crystal spectral changes by measuring the actual light that exits the display, incorporating all optical path effects into the compensation algorithm
Solution Approach 2:
The patent changes the measurement parameter from spectral composition (using color filters) to overall intensity measurement. By measuring total light intensity and comparing it to reference values, the system can detect degradation effects without needing to resolve individual wavelength components, thereby accounting for cumulative optical path changes including liquid crystal spectral modifications
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 system effectively compensates for LED degradation by adjusting pulse width modulation and drive current, improving light transmission accuracy and reducing image quality loss while being cost-effective and simple.
Implementation Method 1
light sources, each for emitting light in a different respective wavelength range
Implementation Method 2
electro-optical elements defining pixels of an image, each for selectively passing light in one of the wavelength ranges
Implementation Method 3
a sensor for measuring the intensity of light output from a portion of the electro-optical elements
Data Source
AI summary
A display device for providing optical feedback includes light sources, each for emitting light in a different respective wavelength range, electro-optical elements defining pixels of an image, each for selectively passing light in one of the wavelength ranges and a sensor for measuring the intensity of light output from a portion of the electro-optical elements. To provide the optical feedback, a controller activates one of the light sources, alters those electro-optical elements within the portion of the electro-optical elements that are arranged to pass light in the wavelength range of a select one of the light source and reads out the measured intensity from the sensor. Based on the measured light intensity, the controller adjusts an illumination parameter associated with the select light source.