Angled Fold Lens for Compact Wearable Display Modules
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Solution Overview
Problem
Wearable headset devices with microdisplays are bulky due to protruding microdisplay assemblies, prone to entanglement and misalignment of optical components, and are costly and unreliable.
Innovation Solution
A compact display module using a single injection-molded plastic lens that generates a virtual image of a microdisplay at an angle, minimizing protrusion and eliminating the need for separate optical component alignment, with a lens defining an angled fold to form a virtual image plane non-perpendicular to the microdisplay surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate optical components (lenses and mirrors) are used to generate a virtual image, then the display module can be engineered with precise optical paths, but the assembly becomes bulky, complex, and susceptible to misalignment
Solution Approach 1:
The patent combines multiple separate optical components (lenses and mirrors) into a single integrated optical element that performs both focusing and image inversion functions. This merging eliminates alignment issues between separate components while maintaining the necessary optical path functionality, directly resolving the contradiction between reliability and device complexity.
Solution Approach 2:
The single optical element is designed to perform multiple functions simultaneously: it acts as both a focusing lens and an image-inverting mirror. This multi-functionality consolidates what would otherwise require separate components, reducing assembly complexity while ensuring reliable optical performance through a monolithic structure.
2Manufacturing precision
If microdisplay assemblies protrude past the headset frame for proper optical alignment, then the display can be properly viewed, but the headset becomes bulky and prone to entanglement
Solution Approach 1:
The patent employs a folded optical path design where the light path is redirected at non-perpendicular angles within a compact volume. This allows the optical system to achieve proper image formation without requiring the microdisplay to protrude significantly, effectively solving the contradiction by utilizing three-dimensional spatial arrangement rather than linear extension.
Solution Approach 2:
The optical components are nested within a compact housing that integrates the microdisplay, optical element, and viewing optics in a space-efficient arrangement. The folded optical path allows components to be positioned in a nested configuration rather than requiring linear space, reducing overall headset dimensions while maintaining optical precision.
3Reliability
If glass lenses are used for the optical element, then optical performance is maintained, but the weight and cost increase
Solution Approach 1:
The patent changes the material parameter of the optical element from traditional glass to molded plastic. This parameter change maintains the necessary optical performance for the application while significantly reducing weight and manufacturing cost. The molded plastic lens is designed with appropriate refractive index and surface curvature to achieve the required optical functionality without the weight penalty of glass.
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 reduces the bulkiness and risk of entanglement of wearable headsets, lowers production costs, and enhances reliability by using a single lens for reflection and focusing, while being lighter and less susceptible to damage.
Implementation Method 1
The lens is configured to focus light rays from a display surface of a microdisplay
Implementation Method 2
The lens also is configured to reflect, at a second surface of the lens, the light rays from the display surface to thereby cause formation of a virtual image
Data Source
AI summary
A compact display module, such as can be used in wearable computing headset applications, includes a microdisplay with a display surface that is virtually imaged by a lens. The lens is positioned to receive light from the display surface of the microdisplay. The lens defines an angled fold, whereby light from a display generated at the display surface is reflected within the lens to thereby form a virtual image of the display in a virtual image plane that is angled non-perpendicularly relative to the display surface of the microdisplay.