Asymmetric Groove Light Guide Plate for Projection Displays
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Solution Overview
Problem
Current projection display apparatuses often suffer from issues such as ghost images and reduced display quality due to light leakage and inadequate light modulation, which affect the overall image display efficiency.
Innovation Solution
A projection display apparatus featuring a light guide plate with asymmetric grooves on its outer surface, a multilayer film coating on the sidewalls, and a focusing lens to improve light modulation and reduce ghost images, while maintaining a reduced thickness and enhanced image display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional light guide plate with symmetric grooves is used, then the structure is simple and easy to manufacture, but light leakage occurs and ghost images are generated reducing display quality
Solution Approach 1:
The patent applies asymmetry by configuring the light guide plate with asymmetric grooves where the first groove has a different shape from the second groove. Specifically, the first groove has a first sidewall inclined at a first angle to the normal, while the second groove has a second sidewall inclined at a second angle to the normal, where these angles differ. This asymmetric configuration prevents ghost images by ensuring that light reflected from different portions of the display does not converge to form unwanted duplicate images, thereby improving display quality while maintaining manufacturing feasibility.
2Length of moving object
If the light guide plate thickness is reduced, then the device becomes more compact, but light modulation efficiency decreases leading to inadequate image display
Solution Approach 1:
The patent applies local quality by introducing asymmetric grooves at specific locations on the light guide plate surface. These grooves are positioned and shaped to locally modify light reflection characteristics without requiring increased overall thickness. The asymmetric groove structures create controlled scattering and reflection zones that enhance light modulation efficiency in the reduced-thickness device, ensuring adequate image display while maintaining compact form factor.
3Ease of manufacture
If symmetric groove structures are used in the light guide plate, then manufacturing is easier, but light leakage occurs reducing optical performance
Solution Approach 1:
The patent applies asymmetry by configuring the light guide plate with asymmetric grooves where the first groove has a different shape from the second groove. Specifically, the first groove has a first sidewall inclined at a first angle to the normal, while the second groove has a second sidewall inclined at a second angle to the normal, where these angles differ. This asymmetric configuration prevents ghost images by ensuring that light reflected from different portions of the display does not converge to form unwanted duplicate images, thereby improving display quality while maintaining manufacturing feasibility.
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 effectively reduces light leakage, enhances contrast ratio, and prevents ghost images, resulting in improved optical performance and display quality by optimizing light propagation and modulation.
Implementation Method 1
a multilayer film coating comprised of dielectric or metal layers arranged on the first and second sidewalls, the multilayer film coating promoting polarization selection when optical reflection occurs on the first and second sidewalls
Implementation Method 2
The light guide plate includes a plurality of optical elements, each of the optical elements has a reference axis that is orthogonal to the second outer surface, and a first and a second sidewall that extend at two sides of the reference axis
Implementation Method 3
a focusing lens is arranged between the light modulator and the light guide plate, the focusing lens being positioned to focus on the light modulator
Implementation Method 4
The light guide plate has a light incidence surface through which the first light enters the light guide, a first outer surface through which a portion of the first light exits the light guide plate
Data Source
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AI summary
A projection display apparatus includes a light source (112) configured to emit a first light, a reflective light modulator (104) configured to modulate the first light to form a second light conveying a rendered image, a polarizer (108) and a light guide plate (106). The light guide plate can include a plurality of optical elements (146) embedded in the thickness of the light guide plate or provided on an outer surface of the light guide plate. An illuminating light entering the light guide plate can be redirected toward the light modulator by reflection at the grooves or optical elements. Moreover, an image light from the light modulator can travel through the light guide plate to the polarizer.