LCD Viewing Angle Characterization via ISO-Inversion Mapping
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Solution Overview
Problem
Liquid crystal display (LCD) devices suffer from gray scale inversion and reduced contrast ratio when viewed from non-ideal angles, making it difficult to assess their operational limitations, especially in critical applications like avionics displays.
Innovation Solution
A method involving a test grid with multiple test points at various inclinations is used to measure luminance across a range of gray scale levels, allowing for the calculation and mapping of gray scale inversion and contrast ratio, enabling the generation of ISO-Inversion and ISO-Contrast charts to identify and troubleshoot viewing angle issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If LCD display elements use angularly-twistable liquid crystals to control light transmission, then the display can achieve a full range of gray scale levels from darkest black to brightest white, but the luminance perceived by viewers decreases monotonically as viewing angle increases from the normal position
Solution Approach 1:
The patent applies parameter changes by systematically varying the viewing angle parameters (horizontal and vertical inclination) to map how luminance and contrast ratio change across different viewing positions. This creates ISO-Inversion and ISO-Contrast charts that show operational limitations at different angular parameters, allowing users to understand and compensate for viewing angle effects without changing the fundamental liquid crystal operation.
2Reliability
If the display device is designed for optimal viewing from a normal position, then contrast ratio and brightness are maximized for that position, but viewers at non-ideal positions experience gray scale inversion and reduced contrast ratio
Solution Approach 1:
The patent applies preliminary action by pre-characterizing the display device's optical properties across multiple viewing angles before use. The ISO-Inversion and ISO-Contrast charts are generated in advance through systematic measurement at various horizontal and vertical inclinations, allowing users to know the display's operational limitations beforehand and adjust viewing positions or interpretations accordingly.
Solution Approach 2:
The patent introduces an intermediary mapping system that translates physical viewing angle parameters into optical property assessments. The test grid with horizontal and vertical inclination parameters serves as an intermediary framework that mediates between the fixed display structure and variable viewer positions, providing a systematic way to assess and communicate viewing quality at different angles.
3Measurement precision
If multiple test points at various inclinations are measured to characterize viewing angle effects, then comprehensive data for identifying gray scale inversion and contrast ratio limitations is obtained, but the measurement process becomes more complex and time-consuming
Solution Approach 1:
The patent applies segmentation by dividing the viewing angle space into discrete test points with specific horizontal and vertical inclination values. This segmented approach allows systematic measurement at manageable intervals rather than continuous assessment, creating a practical test grid that balances measurement precision with procedural complexity. The segmentation of gray scale levels into discrete steps (0-63 or 0-255) also facilitates systematic data collection.
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 provides comprehensive data for pinpointing and addressing gray scale inversion and contrast ratio problems, ensuring reliable performance characterization of LCDs, even when viewed from non-standard positions.
Implementation Method 1
a layer of angularly-twistable liquid crystals, so the light apparently emanates from a source internal to the device. The amount of angular twisting of the liquid crystal fluid material changes as a function of a voltage applied to an individual display element.
Data Source
AI summary
Exemplary embodiments provide a method for characterizing the optical display properties of a display. ISO-Inversion and ISO-Contrast charts are generated to pinpoint limitations in the display and trouble shoot the same.