Backlit Display Segmentation for Visual Field Test Contrast
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Solution Overview
Problem
Conventional light valve display technologies, such as LCDs, struggle to provide satisfactory luminance levels and dynamic range for visual field tests, limiting their ability to match the precise intensity levels required for visual field analysis and frequency doubling illusions due to limited contrast ratios and grayscale levels.
Innovation Solution
The method involves controlling the intensity of the backlight illumination and per-pixel light transmission of light valve devices, using frame interleaving and separate background and stimulus light sources to achieve higher contrast ratios and luminance levels, allowing for the creation of visual stimuli with broad intensity ranges and precise grayscale precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional light valve display technologies (LCDs) are used with standard backlight control, then device simplicity and cost-effectiveness are maintained, but luminance levels and dynamic range are insufficient for visual field tests
Solution Approach 1:
The display system is segmented into multiple independent light sources (first backlight unit for background illumination, second light source for stimulus presentation) that can be controlled separately. This segmentation allows each light source to be optimized for its specific function, achieving high luminance levels and dynamic range while maintaining overall system manageability through modular control architecture
Solution Approach 2:
The patent introduces a temporal dimension by presenting background and stimulus light in alternating frames rather than simultaneously. This frame-interleaved approach allows the display to achieve high contrast ratios and luminance levels by exploiting time-based separation, effectively adding a time dimension to the light control strategy without requiring complex spatial arrangements
2Measurement precision
If conventional light valve display technologies are used with standard contrast control, then device simplicity is maintained, but contrast ratio and grayscale precision are insufficient for visual field analysis
Solution Approach 1:
The control system is segmented into separate controllers for the first backlight unit and second light source, allowing independent optimization of each channel. The first backlight controller manages background illumination levels while the second controller presents stimulus patterns, enabling precise grayscale control for visual field analysis without requiring a single complex control system
Solution Approach 2:
The system dynamically switches between presenting background light and stimulus light in alternating frames, with each light source and controller adapting its parameters in real-time. This dynamic control allows the display to maintain high grayscale precision across varying luminance levels and contrast requirements throughout the visual field test sequence
3Adaptability or versatility
If single backlight illumination is used, then device simplicity is maintained, but the ability to present background and stimulus with different luminance levels is limited
Solution Approach 1:
The illumination system is segmented into a first backlight unit for background illumination and a second light source for stimulus presentation, with each unit having its own controller. This segmentation provides independent luminance control for background and stimulus, enabling flexible adaptation to different visual field test requirements while maintaining modular system architecture that manages complexity
Solution Approach 2:
The system employs periodic alternation between presenting background light frames and stimulus light frames at predetermined frame rates. This periodic action allows the single display device to present multiple luminance levels by exploiting temporal separation, achieving high adaptability for different visual field test protocols without requiring all light sources to be simultaneously active
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 enables the development of backlit displays that can emulate the luminance and contrast of gold standard visual field tests, such as the Humphrey Field Analyzer, while reducing system complexity and cost, and allows for the creation of diagnostically equivalent stimuli with fewer artifacts, enhancing the flexibility and accuracy of visual field testing.
Implementation Method 1
A liquid crystal display (LCD) device is a typical light valve apparatus. These devices display images by modifying the transmission of light.
Implementation Method 2
light valve display devices are generally provided with a light source (backlight, for example) which emits light from the rear side of a passive light modulation part therein to increase visual brightness of a display screen
Implementation Method 3
Passive light valve devices control the transmission of a background radiation light by adjusting the light transmittance
Data Source
AI summary
Embodiments of the present invention include approaches for controlling light valve devices to improve the range and precision of the contrast ratio and the grayscale levels of a display used for visual field tests. In one embodiment, two or more illumination devices are used to enable the display device to display a wide range of contrast stimuli at precise illumination intensities over a fixed background illumination level. In another embodiment, the gamma curves of the display elements are adjusted to allow greater variations in the brightness of the display.