Quasi-Retroreflective Prism Sheet for Compact Infinity Display
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Solution Overview
Problem
Existing display technologies face challenges in creating a compact, wall-mountable infinity display with low optical losses and manufacturing difficulties, particularly in maintaining parallelism between mirrors and achieving effective uncoupling of collimated images in waveguide designs, which results in image registration issues and ghost images.
Innovation Solution
A display apparatus using a quasi-retroreflective prism sheet with an array of micro-prisms that collimates and redirects image rays twice, allowing for a compact and unobtrusive wall-mounted display with improved image registration and reduced optical losses, enabling autostereoscopic or non-autostereoscopic views at or near the horizon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a waveguide design with gradient reflective mirror is used to achieve compact infinity display, then the device depth is reduced, but manufacturing precision is compromised due to difficulty in maintaining parallelism between mirrors
Solution Approach 1:
The patent extracts the gradient reflective mirror from the system and replaces it with a prism sheet having exit apertures. This removes the manufacturing complexity of maintaining mirror parallelism while preserving the compact waveguide form factor. The prism sheet is a simpler component that can be manufactured with standard precision tolerances.
Solution Approach 2:
The patent introduces a diffuser as an intermediary component between the waveguide and the prism sheet. This diffuser helps to uniformize the light distribution and decouple the precise optical alignment requirements from the prism sheet positioning, thereby reducing the manufacturing precision requirements for the prism sheet while maintaining optical performance.
2Volume of stationary object
If a closed waveguide form is used to achieve compact display, then the device size is reduced, but uncoupling control becomes challenging
Solution Approach 1:
The patent segments the waveguide front surface into multiple regions: total internal reflection regions and exit aperture regions. The exit apertures are strategically positioned and sized to allow controlled uncoupling of light at specific locations. This segmentation enables precise control over where and how light exits the waveguide, simplifying the uncoupling control in a compact form factor.
3Area of stationary object
If conventional collimated display is used to achieve large display area, then the collimated display area is increased, but the required apparatus depth increases making wall mounting difficult
Solution Approach 1:
The patent uses a prism sheet with exit apertures that redirects light in a different spatial dimension. Instead of requiring deep optical paths for collimation, the prism sheet creates virtual images at various depths by controlling the exit angles of light rays. This dimensional approach allows large display areas to be achieved with minimal apparatus depth suitable for wall mounting.
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 a compact, easy-to-manufacture display apparatus with reduced optical losses and improved image registration, enabling wide viewing angles and conventional aspect ratios, suitable for both autostereoscopic and non-autostereoscopic displays, while maintaining image quality and depth perception.
Implementation Method 1
a collimating device configured to collimate image point rays to produce collimated image rays
Implementation Method 2
the prism sheet comprising an array of micro-prisms, each micro-prism having two reflective facets arranged such that each collimated image ray is reflected off one facet and then an adjacent facet
Implementation Method 3
collimated image rays from an upper portion of the prism sheet converge with collimated image rays from a lower portion of the prism sheet within the image observation zone
Data Source
AI summary
The present invention describes an image display apparatus for directing an image towards an observer. The apparatus comprises a source of image point rays; a collimating device configured to collimate image point rays to produce collimated image rays; and, a prism sheet configured to receive the collimated image rays. The prism sheet comprises an array of micro-prisms, each micro-prism having two reflective facets arranged such that each collimated image ray is reflected off one facet and then an adjacent facet. Reflection from the second facet reorients the collimated image rays towards an image observation zone. The collimated image rays from an upper portion of the prism sheet converge with collimated image rays from a lower portion of the prism sheet within the image observation zone. The present invention also describes a method for directing an image towards an observer.