Directional Backlight for Autostereoscopic Displays
Solution Overview
Problem
Lenticular-based autostereoscopic displays face reduced resolution in 3D mode due to multiple pixels under each lens element, leading to simultaneous generation of multiple views, which decreases the available resolution compared to the native 2D panel resolution.
Innovation Solution
A directional backlight design using a lightguide with controllable light source arrangements and out-coupling structures that allow for time-sequential generation of collimated light at different angles, enabling multiple views without the need for a lenticular array, thus maintaining full native resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If lenticular lenses are used to direct different views to different physical locations, then multiple views can be generated simultaneously, but the resolution is reduced because multiple pixels are combined under each lens element
Solution Approach 1:
The patent applies time-sequential operation where the backlight alternates between different viewing directions in synchronization with the display panel. This periodic switching enables multiple views to be generated over time rather than simultaneously, preserving the full resolution of individual pixels for each view while maintaining multi-view capability.
Solution Approach 2:
The patent introduces dynamic control of the backlight directionality, allowing the light output direction to be changed over time. This dynamic adjustment enables the system to switch between different viewing angles sequentially, resolving the contradiction by making the multi-view system time-dependent rather than spatially fixed.
2Adaptability or versatility
If lenticular lenses are used to create multiple viewing cones, then the field of view is filled with views, but the structure becomes more complex and thickness increases
Solution Approach 1:
The patent extracts and removes the lenticular lens component from the display structure. Instead of using physical lenses to direct light, the invention relies on a directional backlight that inherently controls light propagation angles, simplifying the overall optical structure while maintaining the ability to provide multiple viewing directions.
Solution Approach 2:
The directional backlight serves multiple functions: it provides illumination for the display panel and simultaneously controls the directionality of light output to create multiple viewing cones. This multi-functional approach eliminates the need for separate optical elements, reducing structural complexity and thickness.
3Adaptability or versatility
If lenticular lenses are used for view formation, then different views are directed to different physical locations, but cone repetition occurs and full native resolution is not maintained
Solution Approach 1:
By using time-sequential switching of the backlight directionality synchronized with the display panel, each pixel's output can be directed to different physical locations at different times. This periodic action eliminates cone repetition while maintaining full native resolution, as each pixel contributes to different views sequentially rather than being optically combined.
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 allows for the generation of multiple views with higher spatial resolution in 3D mode by controlling light directionality, eliminating the need for a lenticular lens and reducing the thickness of the display, while avoiding cone repetition and maintaining full spatial resolution.
Implementation Method 1
a lightguide having top and bottom parallel faces, and a pair of opposite side edges... for redirecting light so that it escapes from the lightguide
Implementation Method 2
an array of light out-coupling structures formed at the top or bottom parallel face for redirecting light so that it escapes from the lightguide
Data Source
Figure 1
Figure 2~4
Figure 5~7
AI summary
A display backlight comprises an edge-lit lightguide having an array of light out-coupling structures to enable light to escape from the lightguide at the location of the light out-coupling structures. A light source arrangement is used for providing light into the lightguide at one or both of the opposite side edges. The light source arrangement is controllable to provide a selected one of at least first and second light outputs into the lightguide, the two light outputs having a different angle to the general plane of the lightguide and resulting in light which escapes from the lightguide with a different range of exit angles. In this way, a directional backlight output is enabled, based on the way light is coupled into a lightguide. This provides a simple structure only requiring control of the light provided to the lightguide. The backlight may for example enable an autostereoscopic display to be formed without the need for a lenticular array.