One-Dimensional Retro Reflective Array for HMD Optical Folding
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Solution Overview
Problem
Conventional head-mounted displays (HMDs) are bulky and expensive due to the need for a two-dimensional reflective array and an additional beam splitter to fold images away from the source, complicating the design and increasing cost.
Innovation Solution
A one-dimensional retro reflective array is used, which deflects images along one axis while reflecting them in a perpendicular axis, eliminating the need for a beam splitter and allowing for a more compact design by using a partially reflective material coated with micro-prisms or dielectric layers, and is tilted to direct images onto the user's eye.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-dimensional reflective array and beam splitter are used to fold images away from the source, then the image can be reflected back to the point of origin in both horizontal and vertical axes, but the HMD becomes more complicated, bulky and expensive
Solution Approach 1:
The patent extracts and eliminates the beam splitter component from the conventional HMD optical path. By using a one-dimensional reflective array that directly deflects light at a different angle, the system removes the unnecessary beam splitter while maintaining the core function of reflecting images to the user's eye.
Solution Approach 2:
The patent introduces a one-dimensional reflective array as an intermediary optical element that performs both reflection and deflection functions. This single component replaces the two-component system (two-dimensional reflective array + beam splitter), simplifying the overall structure while achieving the same optical effect.
2Reliability
If a two-dimensional reflective array and beam splitter are used to fold images away from the source, then the image can be reflected back to the point of origin in both horizontal and vertical axes, but the HMD becomes bulkier
Solution Approach 1:
The patent extracts and eliminates the beam splitter component from the conventional HMD optical path. By using a one-dimensional reflective array that directly deflects light at a different angle, the system removes the unnecessary beam splitter while maintaining the core function of reflecting images to the user's eye.
Solution Approach 2:
The patent merges the reflection and deflection functions into a single one-dimensional reflective array component. This consolidation eliminates the need for separate beam splitter and reflective array components, reducing the overall volume and simplifying the HMD structure.
3Reliability
If a two-dimensional reflective array and beam splitter are used to fold images away from the source, then the image can be reflected back to the point of origin in both horizontal and vertical axes, but the HMD becomes more expensive
Solution Approach 1:
The patent extracts and eliminates the beam splitter component from the conventional HMD optical path. By using a one-dimensional reflective array that directly deflects light at a different angle, the system removes the unnecessary beam splitter while maintaining the core function of reflecting images to the user's eye.
Solution Approach 2:
The patent merges the reflection and deflection functions into a single one-dimensional reflective array component. This consolidation eliminates the need for separate beam splitter and reflective array components, reducing the overall volume and simplifying the HMD structure.
4Device complexity
If a one-dimensional retro reflective array is used to deflect images along one axis, then the design is simplified and bulk is reduced, but the image must be deflected at a different angle than conventional two-dimensional arrays
Solution Approach 1:
The patent changes the operational parameter of the reflective array from two-dimensional reflection (reflecting back to the point of origin in both horizontal and vertical axes) to one-dimensional deflection (deflecting at a different angle). This parameter change simplifies the overall device structure while requiring adjusted optical alignment to achieve the desired deflection angle.
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 simplifies the HMD design, reduces bulk, and eliminates the need for a beam splitter, enabling more flexible packaging and improved image projection without compromising image quality, allowing for both virtual and real-world image combination in a mixed reality display.
Implementation Method 1
a reflective array that retro-reflects along one axis (herein referred to as a one-dimensional retro reflective array) for receiving the image through the optical lens at a first angle with respect to the display, and deflecting the received image at a second angle different than the first angle with respect to the display to project the image onto an eye of the user
Implementation Method 2
the one-dimensional retro reflective array is coated with partially reflective material to perform selective reflection and transmission based on at least one of light polarization and light wavelength
Implementation Method 3
an optical lens for collimating the projected virtual image
Implementation Method 4
The reflective vertical micro-prisms reflecting the image in a horizontal axis onto the eye of the user
Data Source
AI summary
The present invention includes a head mounted display (HMD) worn by a user. The HMD includes a display projecting an image through an optical lens. The HMD also includes a one-dimensional retro reflective array receiving the image through the optical lens at a first angle with respect to the display and deflecting the image at a second angle different than the first angle with respect to the display. The one-dimensional retro reflective array reflects the image in order to project the image onto an eye of the user.