Waveguide Light Expander for Compact Virtual Display
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Solution Overview
Problem
Portable electronic devices face limitations in displaying images due to the restricted size of their displays, which affects the ability to provide an optimal viewing experience for virtual images, especially in terms of size and clarity.
Innovation Solution
The optical apparatus includes a light expander and an optical device that expand and redirect light to produce converging light, allowing for a larger virtual display experience by expanding the exit pupil vertically and maintaining a compact design suitable for portable devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the display size is increased to provide a larger virtual image, then the viewing experience and image clarity are improved, but the device size and portability are compromised
Solution Approach 1:
The patent uses a waveguide structure that extends light propagation into a third dimension (depth/thickness), allowing the display area to be enlarged in the lateral dimensions while maintaining a compact device volume. The light is guided through the thickness of the waveguide substrate, enabling a larger virtual image without proportionally increasing the overall device size.
Solution Approach 2:
The optical components (light source, waveguide, diffraction gratings) are nested within a compact layered structure. The waveguide substrate contains embedded diffraction gratings, and the light source is positioned within or adjacent to the waveguide, creating a space-efficient nested arrangement that enables large display area while maintaining small device volume.
2Illumination intensity
If more light is used to improve image brightness and clarity, then the viewing quality is enhanced, but the power consumption increases
Solution Approach 1:
The patent converts potentially wasted light (stray light, light traveling in unwanted directions) into useful light for the virtual image. The diffraction gratings are designed to redirect light that would otherwise be lost, converting it into light that contributes to the virtual image formation, thereby improving brightness efficiency without increasing power consumption.
Solution Approach 2:
The patent optimizes light propagation parameters by using diffraction gratings with specific pitch and orientation to control the direction and distribution of light. By changing the diffraction parameters (grating pitch, angle), the system maximizes light utilization efficiency, ensuring that a higher proportion of generated light reaches the viewer's eye, thus improving perceived brightness without proportional increase in power consumption.
3Ease of operation
If complex optical systems are used to expand the exit pupil and improve virtual image quality, then the viewing comfort and image clarity are enhanced, but the device complexity increases
Solution Approach 1:
The waveguide substrate serves multiple functions simultaneously: it acts as the display medium, the light guiding structure, and the mounting platform for diffraction gratings. The diffraction gratings themselves perform multiple roles by both expanding the exit pupil and forming the virtual image. This multi-functionality reduces the number of separate components needed, thereby improving viewing comfort without proportionally increasing device complexity.
Solution Approach 2:
The patent merges the light guiding function and the image formation function into a single integrated waveguide structure with embedded diffraction gratings. Instead of using separate components for light guidance and virtual image formation, these functions are combined in one compact unit, simplifying the overall optical system while maintaining enhanced viewing comfort and image quality.
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 enables users to comfortably view enlarged images on a virtual display with improved clarity and efficiency, conserving power by minimizing light wastage and maintaining a compact form factor suitable for portable electronic devices.
Implementation Method 1
A light expander is provided which expands light, input into the light expander, in a first dimension and provides diverging light that diverges in the first dimension
Implementation Method 2
An optical device is provided which redirects diverging light, received from the light expander, to produce converging light that converges in the first dimension
Data Source
Figure 1
Figure 2A~2B
Figure 2C
AI summary
An apparatus, comprising: collimating means for collimating at least a portion of divergent light from each pixel on a display into a collimated beam and outputting a plurality of diverging light beams; first light expanding means for expanding the diverging light beams in a first dimension, the first light expanding means comprising an entrance face, an end face, an upper face, a lower face and first and second side faces, wherein the upper face, lower face and first and second side faces extend between the entrance face and the end face and wherein the lower face and the upper face diverge from one another, in the first dimension, as they extend from the entrance face towards the end face), and for providing diverging light that diverges in the first dimension; and redirecting means for redirecting diverging light, received from the first light expanding means, to produce converging light that converges in the first dimension; and second light expanding means for expanding the converging light in a second dimension, substantially orthogonal to the first dimension, and comprises an in-coupling portion configured to receive the converging light from the grooved reflector, and an out-coupling portion configured to output light to a user.