Backlighting for Head Tracking Displays Using Segmented Light Guides
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Solution Overview
Problem
Current backlight systems for LCDs are inefficient in terms of bandwidth and graphics operation time, as they provide perspective images to areas where no observer's eye is located, leading to wasted resources, and the use of a large number of LEDs is costly and impractical due to geometrical constraints.
Innovation Solution
The development of alternative light guide concepts that utilize a limited number of LEDs and channel-shaped linear structures on a planar substrate, with features to reflect light towards a lenticular lens and LCD, allowing for independent control of light sources to follow the LCD scan, and the use of fiber optic strands or OLED panels to create narrow, independently controllable light lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a large number of LEDs are used to provide illumination across the entire display, then adequate lighting coverage is achieved, but the system becomes costly and geometrically impractical
Solution Approach 1:
The display is divided into multiple scan sections, and the backlight is segmented to illuminate only the current scan section. This allows using a limited number of LEDs that are activated sequentially rather than all LEDs simultaneously, reducing the total number of LEDs needed while maintaining adequate lighting coverage.
Solution Approach 2:
The backlight operates in a periodic manner, synchronizing with the LCD scan sequence. LEDs are turned on and off in periodic cycles corresponding to scan sections, allowing the same limited set of LEDs to serve the entire display area over time rather than requiring continuous illumination across the whole display.
2Area of stationary object
If perspective images are provided to areas where no observer's eye is located, then complete image coverage is achieved, but bandwidth and graphics operation time are wasted
Solution Approach 1:
The backlight illumination is made local to the current scan section rather than illuminating the entire display area. This ensures that light resources are allocated only to the specific area being scanned at any given time, improving bandwidth efficiency by avoiding unnecessary illumination of areas where no observer is present.
Solution Approach 2:
The backlight illumination dynamically adapts to the current scan position and observer location. The system adjusts which LEDs are active based on the scanning progress and detected observer position, allowing the illumination area to change dynamically rather than remaining static, thus optimizing resource usage.
3Device complexity
If light lines are made as small as possible to reduce complexity, then the number of LEDs is reduced, but the lines become harder to control independently
Solution Approach 1:
Each light line is segmented into multiple independently controllable sections that correspond to the LCD scan sections. This segmentation allows each physical LED or LED group to control a specific section independently, maintaining fine control even as the overall number of light lines is reduced.
Solution Approach 2:
The limited number of LEDs is designed to serve multiple functions by being reused across different scan sections. Each LED or LED group is configured to illuminate multiple sections sequentially, allowing a small number of light sources to perform the work of what would traditionally require many more dedicated light sources.
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 solution enables efficient use of light resources by directing illumination only to the observer's location, reducing waste and potentially eliminating the need for a lenticular lens, while maintaining the required properties of thin, independently controlled light lines, thus improving the efficiency and cost-effectiveness of the backlight system.
Implementation Method 1
channel-shaped linear structures on a planar substrate, with features to reflect light towards a lenticular lens and LCD
Implementation Method 2
the use of fiber optic strands or OLED panels to create narrow, independently controllable light lines
Data Source
AI summary
A major component within a backlight device for liquid crystal displays (LCDs), in particular those backlights used in lighting and optical techniques to produce autostereoscopic 3D images and high resolution images.