HMD Optical System Crosstalk Reduction via Polarization Plates
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Solution Overview
Problem
Head-mounted displays (HMDs) for augmented reality face challenges in reducing crosstalk, where one eye sees unnecessary image information from the other's display, due to the size and optical system limitations, leading to unbalanced views and potential blocking of real image light.
Innovation Solution
The implementation of a head-mounted display system with polarization plates and wave plates in the optical systems for each eye, allowing real image light to pass through while blocking virtual image light from the opposing eye, using adjustable configurations to manage polarized light types and orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If polarization control is used to reduce crosstalk, then crosstalk is reduced, but real image light may be blocked and left-right views become unbalanced
Solution Approach 1:
The patent employs switchable wave plates that can be rotated to different orientations depending on the type of polarized light from the real image display device. This dynamic adjustment allows the system to adapt to different polarization states, ensuring that real image light passes through the polarization plates without being blocked, thereby maintaining balanced left-right views while still reducing crosstalk
Solution Approach 2:
The patent changes the polarization state parameters by introducing wave plates that can alter the orientation of polarized light. By adjusting the wave plate orientation according to the real image display's polarization type, the system transforms the polarization parameters to match the virtual image display's requirements, enabling effective crosstalk reduction without compromising real image visibility
Solution Approach 3:
The patent introduces wave plates as intermediary elements between the real image display and the polarization plates. These wave plates act as mediators that convert or adjust the polarization state of real image light before it reaches the polarization plates, preventing the blocking of real image light while maintaining the crosstalk reduction function of the polarization plates
2Manufacturing precision
If image generating device and optical system size are increased, then image quality improves, but crosstalk increases due to right eye seeing left-eye information and vice versa
Solution Approach 1:
The patent divides the optical system into separate left-eye and right-eye optical paths, each with dedicated polarization plates and wave plates. This segmentation ensures that virtual image light for each eye is independently controlled and blocked from reaching the other eye, effectively reducing crosstalk while maintaining large optical system sizes for high image quality
Solution Approach 2:
The patent introduces polarization plates and wave plates as intermediary elements in each optical path. These intermediaries selectively filter and control the polarization state of light, allowing virtual image light to be directed to the correct eye while blocking it from the other eye, thereby reducing crosstalk without requiring reduction of the optical system size
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 effectively reduces crosstalk by ensuring that real image light is uniformly viewed by both eyes, maintaining balanced and clear visual fields while suppressing unnecessary virtual image light interference.
Implementation Method 1
one first polarization plate disposed in an optical axis of the right-eye optical system at an emission side thereof as an emission side position; and another first polarization plate disposed in an optical axis of the left-eye optical system at an emission side thereof as the emission side position
Implementation Method 2
one first wave plate that can be disposed between the right-eye optical system and the one first polarization plate at the emission side position of the right-eye optical system so that the real image light emitted from the right-eye optical system passes through the one first polarization plate
Data Source
AI summary
There is provided a head mounted display including: an optical system comprising: right-eye and left-eye optical systems that guide a real image light and right-eye and left-eye virtual image lights; and an optical element comprising: first polarization plates disposed at emission sides of the right-eye and left-eye optical systems; wherein the right-eye virtual image light from the right-eye optical system and the left-eye virtual image light from the left-eye optical system are blocked by the first polarization plate at the emission side of the left-eye optical system and by that of the right-eye optical system respectively; and at least one of: first wave plates disposed at the emission sides of the right-eye and left-eye optical systems so that the real image light from the right-eye and left-eye optical systems passes therethrough; and second wave plates disposed at incident sides of the right-eye and left-eye optical systems.