Virtual Image Display Optics Using Diffraction to Cut Height
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Solution Overview
Problem
Virtual image display devices for vehicles face challenges in miniaturization while maintaining the size of the displayed image, as reducing the horizontal dimension increases the height, leading to a larger device physique.
Innovation Solution
A virtual image display device utilizing a diffraction reflection element with a plate shape along the vehicle's horizontal plane, where the incident angle is larger than the emission angle, reducing the height dimension and preventing the device from becoming larger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the horizontal dimension of the virtual image display device is reduced to miniaturize the device, then the device size is reduced, but the height dimension increases leading to a larger device physique
Solution Approach 1:
The patent applies asymmetry by configuring the diffraction reflection element with a specific orientation where the incident angle is larger than the emission angle. This asymmetric angular configuration allows the optical path to be folded more efficiently in the horizontal direction while minimizing vertical space requirements, thereby reducing both horizontal and height dimensions simultaneously
Solution Approach 2:
The patent utilizes dimensionality change by employing a diffraction reflection element that operates in three-dimensional space with specific angular relationships. By configuring the element to have a plate shape along the horizontal plane and setting incident and emission angles differently, the optical path is redirected through spatial manipulation, allowing compact device design without increasing height dimension
2Volume of moving object
If the horizontal dimension of the virtual image display device is reduced, then the device becomes more compact, but the size of the displayed image may be compromised
Solution Approach 1:
The patent employs dimensionality change by using a diffraction reflection element with specific angular configuration to fold the optical path through three-dimensional spatial manipulation. This allows the optical path length to be extended in a compact horizontal footprint, maintaining displayed image size while reducing device volume
Solution Approach 2:
The patent applies parameter changes by optimizing the incident angle and emission angle relationship, setting the incident angle larger than the emission angle. This angular parameter configuration maximizes the optical path efficiency within the compact device structure, ensuring that image size is maintained despite reduced horizontal dimensions
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 configuration suppresses the increase in device size, allowing for a more compact design without compromising the size of the displayed image, enhancing visibility and reducing the device's physical presence.
Implementation Method 1
a diffraction reflection element configured to reflect the display light emitted from the display unit by diffraction
Data Source
AI summary
A virtual image display device displays a virtual image by projecting a display light of an image toward a projection unit, and includes: a display unit configured to emit the display light; and a diffraction reflection element configured to reflect the display light emitted from the display unit by diffraction. The diffraction reflection element has a plate shape along a horizontal plane. The diffraction reflection element is configured to emit the display light toward the projection unit arranged above the diffraction reflection element when the display light is incident, and is set such that an angle of incidence on the diffraction reflection element is larger than an angle of emission from the diffraction reflection element.