Directional Backlight Crosstalk Suppression via Wavelength Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Autostereoscopic displays face issues with reduced spatial resolution, image flicker, and increased visual strain due to stray light and image cross-talk, which are not effectively addressed by existing technologies.
Innovation Solution
A directional backlight system with a waveguide and reflective end, incorporating a filter to reduce reflections and absorb light in the conversion band preferentially, thereby minimizing stray light and image artifacts, and utilizing an array of light sources with wavelength conversion materials to direct light into specific optical windows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a reflective end is added to the waveguide to improve light utilization, then light efficiency is improved, but reflections at the input end cause image cross-talk and artifacts
Solution Approach 1:
The patent converts the harmful reflected light into a beneficial effect by using a wavelength conversion material that absorbs the reflected light in the emission band and re-emits it in a conversion band. This transforms the harmful reflection into useful light that can be directed to the output, improving overall light efficiency while eliminating cross-talk artifacts.
Solution Approach 2:
The wavelength conversion material acts as an intermediary between the reflected light and the output. It absorbs light in the emission band and converts it to the conversion band, serving as a mediator that transforms the harmful reflected light into useful output light, thereby resolving the contradiction between light efficiency and image quality.
2Stability of the object's composition
If defocusing is applied to reduce image flicker, then flicker is reduced, but image cross-talk increases and visual strain increases
Solution Approach 1:
The patent changes the spectral parameters of the light by using wavelength conversion. Instead of defocusing optically (which increases cross-talk), it converts the wavelength of reflected light from the emission band to the conversion band, achieving flicker reduction without the harmful side effects of increased cross-talk.
3Stability of the object's composition
If the pixel aperture shape is adjusted to reduce flicker, then flicker is reduced, but display brightness decreases and electronics complexity increases
Solution Approach 1:
The patent changes the spectral parameter of the light using wavelength conversion material, converting reflected light from the emission band to the conversion band. This approach reduces flicker while maintaining display brightness, avoiding the need to alter pixel aperture shapes that would reduce brightness and increase electronic complexity.
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 enhances the depth and clarity of 3D images, reduces visual strain, and improves viewing comfort by minimizing stray light and cross-talk, while maintaining high image quality and efficiency.
Implementation Method 1
a wavelength conversion material arranged to convert at least some of the light in the emission band generated by the light generation element into light in the conversion band
Implementation Method 2
a reflective end facing the input end for reflecting light from the input light back through the waveguide
Implementation Method 3
first and second, opposed guide surfaces for guiding light along the waveguide
Implementation Method 4
a filter, disposed between the input end and the light sources, and arranged to absorb light in the conversion band preferentially over light in the emission band so as to reduce reflections of light incident on the input end after reflection from the reflective end
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A directional backlight for a transmissive spatial light modulator comprises a waveguide having an input end, first and second, opposed guide surfaces for guiding light along the waveguide, and a reflective end facing the input end for reflecting light from the input light back through the waveguide. An array of light sources that output light predominantly in an emission band and in a conversion band are disposed across the input end of the waveguide and light is directed into respective optical windows in output directions distributed in the lateral direction in dependence on the input positions. To achieve crosstalk suppression, disposed between the input end and the light sources is a reflection reduction element that comprises a filter arranged to absorb light in the conversion band preferentially over light in the emission band, thereby reducing reflections of light incident on the input end after reflection from the reflective end.