Tapered Light Guide Collimation for Compact Projection
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Solution Overview
Problem
Conventional lens systems, such as those used in rear projection televisions and flat panel displays, suffer from bulkiness due to the need for space between the focal point and the exit surface, resulting in undesirable margins and requiring costly alignment of prisms or slabs of light guides to collimate rays effectively.
Innovation Solution
A tapered light guide with a thin end and a thick end featuring a beveled mirror or optical equivalent, where the thickness profile is proportional to sin[(z+L)/kL], allowing collimated rays to emerge from the thin end and reducing the angle between rays and the plane of the light guide, eliminating the need for folding prisms and maintaining image quality without keystone distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a slab of light guide is disposed between the focal point and exit surface to allow rays to fan out, then rays can be collimated, but the system becomes bulky and creates undesirable margins
Solution Approach 1:
The patent changes the geometric parameters of the light guide from a uniform slab to a tapered structure where the thickness varies continuously. This parameter change allows the light guide to perform the same ray collimation function while reducing the overall system volume and eliminating the need for separate folding prisms.
Solution Approach 2:
The invention introduces a dimensional variation by making the light guide thickness non-uniform along its length. This dimensional change (from 2D uniform slab to 3D tapered structure) enables rays to fan out and collimate within a more compact volume, effectively solving the bulkiness problem.
2Area of stationary object
If folding prisms are used to remove the margin on screen, then the picture can fill the screen, but the alignment becomes complex and costly
Solution Approach 1:
The patent merges the functions of the light guide and the ray redirection mechanism into a single tapered light guide structure. This integration eliminates the need for separate folding prisms and their complex alignment, while still achieving full screen picture coverage.
Solution Approach 2:
The tapered light guide performs multiple functions simultaneously: it allows rays to fan out, collimates them, and redirects them to fill the screen area. This multi-functionality replaces what would traditionally require multiple separate components including folding prisms.
3Length of stationary object
If a tapered light guide is used to remove space between camera and object, then space is reduced, but a slab of light guide is still required for rays to fan-in
Solution Approach 1:
The patent applies parameter changes to the light guide thickness profile, creating a tapered structure that enables rays to fan-in efficiently. This parameter optimization reduces the required light guide volume while maintaining the space-reduction benefit between camera and object.
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 lens system with minimal or no margin, improving image uniformity and reducing production costs by eliminating the need for costly prisms and ensuring all rays exit before reaching the thin end, thus enhancing the efficiency and resolution of projected images.
Implementation Method 1
The light guide includes a bevelled mirror or optical equivalent at its thick end, the bevel being such that rays injected through a point at the thin end emerge collimated from one of the light guide surfaces
Implementation Method 2
A tapered light guide with a thin end and a thick end featuring a beveled mirror or optical equivalent, where the thickness profile is proportional to sin[(z+L)/kL], allowing collimated rays to emerge from the thin end and reducing the angle between rays and the plane of the light guide
Data Source
AI summary
A flat panel lens system as a tapered light guide that has minimal or no margin for fan out. The tapered light guide includes a thin end, and a thick end of which is a bevelled mirror or an optical equivalent. Light is injected into the thin end and the mirror is such that rays injected through a point at the thin end emerge collimated from one of the light guide surfaces, and that collimated rays injected at an appropriate angle through one of the light guide surfaces emerge from a point at the thin end. Bragg gratings can be utilized for color implementations as well. The tapered light guide can be fabricated as a single piece, by extrusion, injection molding, or the combination/variation of extrusion and injection molding, as well as other commonly known techniques.