Virtual Image Display Device Using Polarization Switching
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Solution Overview
Problem
Existing head-up display systems require a large moving screen to change the virtual image display distance, leading to increased device size and longer adjustment times, which complicates the reduction of driver fatigue and safety by altering the focal adjustment time during driving.
Innovation Solution
A virtual image display device with a polarization switching unit that changes the polarization direction of a light beam, allowing it to travel through different optical paths of varying lengths, enabling the display of virtual images at multiple distances without the need for a moving screen, thus downsizing the device and reducing adjustment time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a screen is moved to change the virtual image display distance, then the virtual image display distance can be adjusted, but the device size increases and the adjustment time becomes longer
Solution Approach 1:
The patent replaces the mechanical screen moving system with an optical path switching system. Instead of physically moving the screen to adjust virtual image display distance, the invention uses a polarization switching unit to change the polarization direction of light beams, which then travel through different optical paths (first optical path for normal distance, second optical path for extended distance) to achieve distance adjustment without mechanical movement.
Solution Approach 2:
The patent divides the optical path into multiple segments (first optical path and second optical path) with different lengths. By switching between these segmented optical paths using polarization switching, the system achieves variable virtual image display distance without requiring a single long mechanical travel range, thus reducing overall device size.
2Adaptability or versatility
If a screen is moved to change the virtual image display distance, then the virtual image display distance can be adjusted, but the adjustment time becomes longer
Solution Approach 1:
The patent replaces the mechanical screen moving system with an optical path switching system. Instead of physically moving the screen to adjust virtual image display distance, the invention uses a polarization switching unit to change the polarization direction of light beams, which then travel through different optical paths (first optical path for normal distance, second optical path for extended distance) to achieve distance adjustment without mechanical movement.
Solution Approach 2:
The patent uses periodic polarization switching to rapidly alternate between different optical paths. The polarization switching unit can quickly switch the polarization direction of light beams between unchanged and changed states, enabling fast adjustment of virtual image display distance without the time-consuming mechanical movement of screens.
3Loss of time
If the virtual image display distance is changed by moving the screen, then the focal adjustment time can be reduced, but the device complexity increases
Solution Approach 1:
The patent replaces the mechanical screen moving system with an optical path switching system. Instead of physically moving the screen to adjust virtual image display distance, the invention uses a polarization switching unit to change the polarization direction of light beams, which then travel through different optical paths (first optical path for normal distance, second optical path for extended distance) to achieve distance adjustment without mechanical movement.
Solution Approach 2:
The patent implements a dynamic optical path switching system that can rapidly adapt between different optical path lengths based on driving conditions. The polarization switching unit dynamically changes the polarization direction of light beams to select between the first optical path (for short focal adjustment time) and the second optical path (for extended display distance), allowing the system to respond quickly to changing driving conditions without mechanical complexity.
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 allows for a compact head-up display system that quickly adjusts the virtual image display distance, improving driver safety and reducing fatigue by minimizing the time required for focal adjustment during driving.
Implementation Method 1
a polarization switching unit provided on an optical path of the light beam emitted from the light source unit, the polarization switching unit switching a polarization direction of the light beam emitted from the light source unit between an unchanged first polarization direction and a changed second polarization direction
Data Source
AI summary
A virtual image display device includes a light source unit, a polarization switching unit, an image generation unit, an optical path unit and a projection unit. The polarization switching unit switches a polarization direction of a light beam emitted from the light source unit. The optical path unit includes a first optical path through which the light beam having the first polarization direction travels and a second optical path through which the light beam having the second polarization direction travels. A first virtual image is displayed at a first distance with the light beam that has traveled through the first optical path. A second virtual image is displayed at a second distance farther than the first distance with the light beam that has traveled through the second optical path.