Bonded Planoconvex-Planoconcave Lens for Wide-Angle Virtual Image Display
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Solution Overview
Problem
Existing virtual image display devices face challenges in reducing size and thickness while maintaining a wide angle of view, leading to increased optical system burden, aberrations, and light reflection issues due to curved lens surfaces.
Innovation Solution
A virtual image display device configuration with a planoconvex first lens and a planoconcave second lens, bonded at a convex and concave surface interface, incorporating a half mirror and polarization elements to manage light path and reduce optical component thickness, allowing for a wide angle of view and relaxed light incident angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If curved lens surfaces are used to achieve a wide angle of view, then the angle of view is improved, but optical aberrations and total reflection increase
Solution Approach 1:
The optical system is divided into multiple lens units (first lens unit with positive power and second lens unit with negative power) instead of using a single curved lens. This segmentation allows the wide angle of view to be achieved through the combined effect of multiple elements with milder curvatures, reducing individual surface aberrations and total reflection risks.
Solution Approach 2:
The patent uses aspherical surfaces in the lens design to correct optical aberrations while maintaining a wide angle of view. The aspherical surfaces allow for better control of light rays across the field without requiring extreme curvatures that would cause total reflection, thus resolving the contradiction between wide angle and aberration control.
2Length of stationary object
If lens curvature is increased to reduce device thickness, then device thickness is improved, but optical aberrations and light incident issues worsen
Solution Approach 1:
The optical power is distributed across multiple lens elements rather than concentrated in a single highly curved surface. The first lens unit provides positive power and the second lens unit provides negative power, allowing the system to achieve the required optical strength with milder individual curvatures, thus reducing aberrations and light incident problems while maintaining thin profile.
Solution Approach 2:
The patent employs composite lens structures with different refractive indices and dispersion characteristics. By combining materials with different optical properties, the system achieves the required power with reduced curvature, minimizing optical aberrations and total reflection while maintaining compact thickness.
3Volume of moving object
If small image elements are used to expand and project images, then device size is reduced, but light incident angle problems increase
Solution Approach 1:
The optical system uses multiple lens units to progressively expand and project the image from the small image element. The first lens unit with positive power initially expands the image, and the second lens unit with negative power further projects it, distributing the angular transformation across multiple elements rather than requiring extreme angles at a single element.
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 achieves reduced size and thickness while maintaining a wide angle of view, minimizing aberrations and light reflection issues, enabling efficient image formation with improved optical performance.
Implementation Method 1
a half mirror provided in a bonding portion between the convex surface and the concave surface
Implementation Method 2
a transmission/reflection selection member provided in contact with the light emitting plane and configured to selectively transmit or reflect the light depending on a polarization state of the light
Implementation Method 3
a first lens disposed on a location where image light from the image element is extracted and including a light emitting plane configured to emit image light and a convex surface facing the image element side, a second lens disposed further toward to the image element side than the first lens and including a concave surface bonded to the convex surface of the first lens
Data Source
AI summary
A first lens and a second lens are bonded, and each of a light emitting plane and a light incident plane is a flat surface to shorten a configuration in an optical axis direction, and simultaneously, various optical elements such as a transmission/reflection selection member and the like can be mounted on a flat surface portion. Further, by providing a half mirror in a bonding portion between a convex surface and a concave surface to give power in folding an optical path, an image with a wide angle of view can be formed.