Curved Display Light Redirecting Layer for Exit Pupil Brightness
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Solution Overview
Problem
Conventional display systems face challenges in maximizing the fraction of light emitted by the display panel that is transmitted through the exit pupil, leading to reduced brightness and efficiency, particularly in head-mounted displays like virtual reality systems, due to factors such as unwanted ghosting and image blurriness caused by performance degradation of polarizing components and birefringence.
Innovation Solution
Incorporating a light redirecting layer between the display panel and the partial reflector, or modifying the backlight to alter the light output's direction and collimation, which includes a plurality of discrete spaced apart pixels configured to emit a cone of light with a central ray direction varying with pixel location, thereby increasing the brightness of the image projected through the projection lens system by at least 30 percent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional display panel emits light uniformly in all directions, then the light distribution is simple and manufacturing is easy, but the brightness at the exit pupil is reduced and light utilization efficiency is low
Solution Approach 1:
The display panel is divided into multiple discrete spaced-apart pixels, with each pixel emitting light in a specific directional cone. This segmentation allows precise control of light direction from each pixel, increasing the fraction of light that reaches the exit pupil while maintaining a relatively simple overall system architecture.
Solution Approach 2:
Each pixel is configured with different emission characteristics based on its location in the display panel. The central ray direction of each pixel's light cone varies with pixel location, creating local optical quality variations that collectively improve the overall brightness and image quality at the exit pupil.
2Reliability
If polarizing components are used to improve image quality, then contrast ratio and image clarity improve, but performance degradation and birefringence cause ghosting and image blurriness
Solution Approach 1:
The patent extracts and eliminates the problematic polarizing components from the optical system. By removing these components that cause birefringence and performance degradation, the system avoids ghosting and image blurriness while maintaining image quality through the directional light emission from discrete pixels.
Solution Approach 2:
Instead of using polarizing components that create harmful birefringence effects, the invention converts the approach by using directional light emission from discrete pixels to achieve image quality control. This alternative method achieves contrast and clarity without the harmful side effects of polarizing components.
3Illumination intensity
If the projection lens system has a large aperture to capture more light, then brightness improves, but the system size and complexity increase
Solution Approach 1:
The display panel performs preliminary light direction control by emitting light in specific directional cones from each pixel location. This preliminary action ensures that light is already oriented toward the exit pupil before entering the projection lens system, allowing the use of smaller aperture lenses while maintaining high brightness.
Solution Approach 2:
The invention changes the light emission parameters from uniform omnidirectional emission to directional cone emission with location-dependent central ray directions. This parameter change increases light utilization efficiency, allowing smaller lens apertures to capture sufficient light for bright projected images.
4Productivity
If discrete spaced-apart pixels are used to control light direction, then brightness and light utilization improve, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses discrete spaced-apart pixels that provide sufficient light direction control without requiring complete pixel coverage or extremely tight spacing. This partial action approach achieves the necessary brightness and light utilization improvement while maintaining reasonable manufacturing precision requirements.
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 approach significantly enhances the brightness of the image at the exit pupil by redirecting and collimating light more effectively, improving the contrast ratio and efficiency of the optical system, and increasing the fraction of light utilized by the lens system.
Implementation Method 1
The light extraction portion is configured to provide a light output central ray direction having an angle with respect to the optical axis that varies with location on an output surface of the light extraction portion
Implementation Method 2
For each pixel in the plurality of pixels, the imager is configured to emit a cone of light having a central ray which has a direction that varies with location of the pixel in the imager
Data Source
AI summary
A display system includes a pixelated display being curved about at least one axis and including a plurality of groups of pixels; a plurality of light redirecting elements where each light redirecting element corresponds to a different group of pixels in the plurality of groups of pixels; and an optical lens system adapted to receive light emitted by the pixelated display and transmitted by the plurality of light redirecting elements. The optical lens system transmits at least a portion of the received light. For at least one pixel in the plurality of groups of pixels, the light redirecting element corresponding to the pixel reduces an angle between a central light ray emitted by the pixel and a chief light ray emitted by the pixel.