LCD Backlight Intensity Compensation for Pixel Degradation
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Solution Overview
Problem
Liquid Crystal Displays (LCDs) face performance degradation due to ionic compound buildup on electrodes over time, affecting light transmission and image quality, as existing technologies lack effective methods to consistently maintain pixel performance.
Innovation Solution
A method involving the application of a test voltage to each liquid crystal element, detection of light using photosensors, and adjustment of backlight levels to compensate for differences in light transmission across pixels, ensuring consistent image display and extending pixel lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If pixels are subjected to the same electric field over a long period of time, then the LCD can maintain consistent operation, but ionic compounds build up on electrodes and pixel performance degrades
Solution Approach 1:
The patent implements periodic action by periodically inverting the polarity of the electric field applied to each pixel. Instead of applying a unidirectional electric field continuously, the system alternates the field direction between positive and negative polarity at regular intervals. This periodic polarity inversion prevents ionic compounds from accumulating on single electrodes by periodically redistributing them, thereby maintaining pixel performance over extended operational durations without requiring physical cleaning or replacement
2Reliability
If backlight intensity is increased to compensate for pixel degradation, then light transmission through degraded pixels can be maintained, but energy consumption increases
Solution Approach 1:
The patent applies local quality by implementing spatially differentiated backlight intensity control. Rather than uniformly increasing backlight intensity across the entire display to compensate for pixel degradation, the system identifies specific degraded pixels through sensing and selectively increases backlight intensity only at those localized positions. This approach maintains image quality by compensating for light transmission losses in degraded pixels while minimizing overall energy consumption by leaving non-degraded pixels at normal backlight levels
3Manufacturing precision
If individual pixel compensation is implemented to maintain image quality, then display uniformity improves, but system complexity increases
Solution Approach 1:
The patent implements self-service by enabling the display system to automatically detect and compensate for its own pixel degradation without external intervention. Each pixel is equipped with or associated with a sensing mechanism that monitors its own light transmission characteristics. When degradation is detected, the system automatically adjusts parameters such as polarity inversion timing and local backlight intensity for that specific pixel. This self-diagnosing and self-correcting capability improves display uniformity while avoiding the need for complex external monitoring and control systems
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 approach effectively maintains image quality by compensating for variations in light transmission across pixels, reducing the impact of degradation and improving the overall performance and longevity of LCDs.
Implementation Method 1
The liquid crystal molecules have a first orientation in the absence of an electric field and are induced into a second orientation upon application of an electric field between the electrodes
Implementation Method 2
The difference in light polarization of the liquid crystals between the first and second orientations is used in combination with the polarizing filters such that control over the electric field determines whether, or to what extent, light will pass through the liquid crystal layer
Implementation Method 3
detecting an amount of light received at each of a plurality of photosensors
Data Source
AI summary
A computer program product (CPP) for controlling a liquid crystal display (LCD) includes code for applying a test voltage to each liquid crystal element (LCE) disposed in an addressable array forming the LCD, and code for detecting an amount of light received by photosensors while applying the test voltage to the LCEs, wherein each photosensor is aligned behind and logically associated with one of the LCEs. The CPP further includes code for applying selected voltage levels to each LCE to display an image, and code for controlling an amount of backlight produced by backlighting elements in an addressable array while the image is displayed. Each backlighting element is aligned behind and logically associated with one LCE, and at least one backlighting element is controlled to compensate for a difference between the amount of light detected by the photosensor logically associated with at least one LCE and the other photosensors.