Directional Backlight Flux Control for Uniform Viewing Windows
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Solution Overview
Problem
Spatially multiplexed autostereoscopic display devices suffer from reduced spatial resolution, image flicker, and non-uniform viewing windows due to gaps between pixels, leading to limited viewing freedom and increased visual strain, which existing solutions attempt to address through defocusing or adjusting pixel aperture shapes at the cost of brightness and efficiency.
Innovation Solution
A directional backlight system with a waveguide and an array of light sources positioned laterally across the input end, where the light sources are controlled to direct light into varying optical windows with luminous fluxes scaled inversely by their width, achieving Lambertian or non-Lambertian characteristics to optimize viewing comfort and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If adjusting the shape of the pixel aperture is used to reduce image flicker, then image flicker is reduced, but display brightness is reduced
Solution Approach 1:
The patent changes the luminous flux parameter of individual light sources rather than altering the physical shape of pixel apertures. By controlling the luminous flux distribution across the light source array, the invention eliminates flicker while maintaining full display brightness without requiring aperture shape modifications
2Use of energy by moving object
If uniform luminous fluxes are used across the array of light sources, then the waveguide exhibits non-Lambertian optical output characteristics, but the backlight does not appear to have uniform visual appearance
Solution Approach 1:
The patent applies local quality by controlling each light source in the array to have different luminous flux values based on its position. Light sources are driven with luminous fluxes scaled inversely by their width in the lateral direction, creating local variations that result in overall uniform Lambertian visual appearance across the backlight
Solution Approach 2:
The patent changes the luminous flux parameter of individual light sources based on their position in the array. By scaling luminous fluxes inversely by width and distributing them across different input positions, the invention transforms non-Lambertian optical characteristics into uniform Lambertian visual appearance
3Illumination intensity
If the backlight achieves Lambertian characteristics, then uniform visual appearance is achieved, but power consumption increases
Solution Approach 1:
The patent optimizes the luminous flux distribution parameter across the light source array to achieve Lambertian characteristics. By scaling luminous fluxes inversely by width and positioning light sources at different input positions, the invention achieves uniform visual appearance while minimizing total power consumption compared to traditional Lambertian backlights
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
The solution provides improved spatial resolution, reduced image flicker, and uniform illumination, while minimizing power consumption and visual strain, by dynamically controlling light distribution across the display, enhancing the overall viewing experience and efficiency of autostereoscopic displays.
Implementation Method 1
The waveguide has first and second opposed guide surfaces for guiding light along the waveguide
Implementation Method 2
a reflective end facing the input end for reflecting input light from the light sources back through the waveguide
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
An imaging directional backlight includes an array of light sources, and a control system arranged to provide variable distribution of luminous fluxes, scaled inversely by the width associated with the respective light sources in the lateral direction, across the array of light sources. The luminous intensity distribution of output optical windows may be controlled to provide desirable luminance distributions in the window plane of an auto stereoscopic display, a directional display operating in wide angle 2D mode, privacy mode and low power consumption mode. Image quality may be improved and power consumption reduced.