Temporally Multiplexed Autostereoscopic Display with Waveguide Backlight
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Solution Overview
Problem
Conventional autostereoscopic displays face limitations in spatial resolution, image flicker, and viewing freedom due to non-uniform viewing windows and the need for additional addressing electronics, which also increase cost and complexity.
Innovation Solution
The use of a time multiplexed autostereoscopic display apparatus with inclined viewing windows, employing a waveguide and directional backlight system that includes a transmissive spatial light modulator and a control system for observer tracking, allowing for directional illumination and independent image control for left and right eyes, enabling landscape and portrait modes of operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If spatially multiplexed autostereoscopic displays are used to provide multiple viewing windows, then viewing freedom is improved, but spatial resolution is reduced compared to native resolution of the spatial light modulator
Solution Approach 1:
The patent employs temporal multiplexing where the spatial light modulator alternates between displaying left-eye and right-eye images at different time slots. This periodic switching allows full-resolution images to be displayed sequentially for each eye, eliminating the spatial resolution loss inherent in simultaneous spatial multiplexing while maintaining multiple viewing windows through directional backlight control.
Solution Approach 2:
The system dynamically adjusts the directional backlight's light extraction features to steer viewing windows to different positions corresponding to observer eye locations. This dynamic repositioning allows the display to maintain full spatial resolution for each eye's image while providing viewing freedom as observers move, resolving the contradiction between static resolution and dynamic viewing adaptability.
2Object-affected harmful factors
If the shape of the pixel aperture is adjusted to reduce image flicker, then viewing freedom is improved, but display brightness is reduced and additional addressing electronics are required
Solution Approach 1:
The patent extracts the flicker-reduction function from the pixel aperture shape modification and relocates it to the directional backlight system. By using light extraction features in the waveguide to steer viewing windows and control light direction, the system reduces flicker without altering pixel aperture shapes, thereby maintaining display brightness and avoiding additional addressing electronics in the spatial light modulator.
Solution Approach 2:
The directional backlight acts as an intermediary between the spatial light modulator and the observer. It mediates the light path by steering viewing windows to match observer eye positions, which reduces image flicker caused by lateral movement while preserving the original pixel aperture characteristics and display brightness.
3Object-affected harmful factors
If defocusing of optical elements is used to reduce image flicker, then viewing freedom is improved, but image cross talk increases and visual strain increases
Solution Approach 1:
The patent replaces the optical defocusing mechanism with a directional light steering mechanism using light extraction features in the waveguide. Instead of mechanically or optically defocusing elements to reduce flicker, the system uses controlled light redirection to steer viewing windows to appropriate positions, reducing flicker without increasing image cross talk or visual strain.
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 spatial resolution, reduces image flicker, and provides low cross-talk and high uniformity, allowing for efficient and cost-effective autostereoscopic displays with improved viewing freedom in various orientations.
Implementation Method 1
a waveguide extending between an input end for receiving input light and a reflective end for reflecting the input light back through the waveguide
Implementation Method 2
the second guide surface has a plurality of light extraction features facing the reflective end and inclined to reflect the light guided back through the waveguide from the reflective end
Implementation Method 3
an array of light sources at different positions across the input end of the waveguide, the light extraction features of the waveguide being arranged to direct input light from different input positions across the input end into viewing windows in directions that are dependent on the input position
Implementation Method 4
a transmissive spatial light modulator comprising an array of pixels arranged to modulate light that has exited the waveguide
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
An autostereoscopic display comprising a temporally multiplexed display arranged to provide viewing windows in a range around 45 degrees to achieve landscape and portrait viewing in cooperation with an observer tracking system. The temporally multiplexed display may comprise a stepped waveguide imaging directional backlight.