Light Guide Diffraction Structure for Wider HUD Viewing Angles
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Solution Overview
Problem
Conventional vehicle information projection systems using head-up displays have a limited visual field range for augmented reality displays, restricting the visibility of virtual images.
Innovation Solution
An optical system with a light guide body that includes a coupling region and expansion regions with diffraction structures, which changes and expands the light flux in both horizontal and vertical directions, allowing for a wider visual field by replicating the light flux and projecting it onto a windshield or other light-transmitting member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a conventional head-up display uses a pupil expansion type hologram, then the virtual image can be displayed, but the visual field range in which the image is visible is narrow
Solution Approach 1:
The light guide body is divided into multiple functional regions: a coupling region for receiving light from the display, and multiple expansion regions with different diffraction structures. Each expansion region diffracts light in different directions to replicate the light flux, creating multiple virtual images that collectively expand the visual field range while maintaining adaptability for different viewing positions
Solution Approach 2:
The patent introduces a third dimension (depth/thickness of the light guide body) to solve the two-dimensional limitation of visual field expansion. By stacking multiple expansion regions at different depths with different diffraction angles, the system expands the visual field not only horizontally but also in the vertical dimension, creating a three-dimensional light flux distribution that accommodates multiple viewing positions
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 optical system effectively expands the visual field range of the virtual image, enabling it to be seen over a broader angle, enhancing the visibility of the displayed information for the observer.
Implementation Method 1
The light flux incident on the incident surface of the light guide body is changed in a traveling direction by diffraction by a diffraction structure of a coupling region in the light guide body
Implementation Method 2
The light flux changed in the traveling direction is emitted from the emission surface after being expanded by being replicated in a first direction corresponding to a horizontal direction of the image visually recognized by the observer due to diffraction by a diffraction structure of an expansion region in the light guide body
Data Source
AI summary
A light flux incident on the light guide body is replicated in a first direction or a second direction by a diffraction structure of an expansion region. When a normal direction with respect to the light guide body of the expansion region is defined as a Z-axis direction, and a tangential plane is defined as an XY plane, the diffraction structure of the expansion region is configured such that a light flux duplicated when the light flux incident on the expansion region is transmitted through the XY plane of the expansion region from a positive direction of the Z axis and a light flux duplicated when the light flux is transmitted through the XY plane of the expansion region from a negative direction of the Z axis are accommodated within a viewing angle at which the image is visually recognizable.