Virtual Image Display Optical System with Partial Reflector Light Guide
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Solution Overview
Problem
Virtual image display devices face challenges in reducing the thickness of the light guide while maintaining image quality and angle of view, due to the difficulty in correcting aberrations and achieving a wide field of view with existing optical systems.
Innovation Solution
The optical system incorporates a light guide with partial reflectors and an intermediate image forming portion, which splits image light into multiple beams, allowing for a wider angle of view and reduced thickness by forming an intermediate image within the light guide, and includes a reflector to convert image light into collimated light for improved image display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If collimated light is used to proceed through the lens serving as a light guide component, then the light guide can effectively guide image light, but the thickness of the lens cannot be reduced
Solution Approach 1:
The optical system is segmented into multiple functional components: a light guide with partial reflectors for light guidance, an intermediate image forming portion for aberration correction, and a lens for final image formation. This segmentation allows each component to be optimized independently, enabling thin light guide design while maintaining image quality through the intermediate image forming portion.
Solution Approach 2:
An intermediate image forming portion is introduced as an intermediary component between the light guide and the lens. This intermediary forms an intermediate image that corrects aberrations before the light reaches the lens, enabling the light guide to be thinner while maintaining reliable image quality.
2Length of stationary object
If existing optical systems are used to reduce light guide thickness, then the device becomes thinner, but aberration correction and wide field of view are difficult to achieve
Solution Approach 1:
The intermediate image forming portion performs preliminary aberration correction before the light reaches the lens. By correcting aberrations in advance at the intermediate image stage, the system achieves high manufacturing precision and wide field of view while maintaining a thin light guide configuration.
Solution Approach 2:
The patent introduces an additional optical dimension by adding the intermediate image forming portion between the light guide and lens. This dimensional addition provides the necessary degrees of freedom for aberration correction and wide field of view achievement without increasing the light guide thickness.
3Adaptability or versatility
If partial reflectors are used to split image light into multiple beams, then the angle of view is widened, but the optical system complexity increases
Solution Approach 1:
The light guide with partial reflectors serves multiple functions: it guides image light, splits light into multiple beams to widen the angle of view, and works in conjunction with the intermediate image forming portion for aberration correction. This multi-functionality reduces the need for separate components, thereby managing system complexity while achieving a wide angle of view.
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 enables a thinner and lighter virtual image display device with improved image quality, wider angle of view, and reduced manufacturing costs, while maintaining high-resolution image display and correcting aberrations effectively.
Implementation Method 1
The partial reflector is configured to transmit the image light incident from the first portion and reflect the image light incident from the second portion to guide the image light to exit the light guide
Implementation Method 2
The partial reflector is configured to transmit the image light incident from the first portion and reflect the image light incident from the second portion
Implementation Method 3
The reflector is configured to reflect the image light transmitted through the partial reflector and the second portion back to the partial reflector
Implementation Method 4
The intermediate image forming portion is configured to form an intermediate image with the image light in the light guide
Implementation Method 5
The light guide is configured to guide image light emitted from an image display element that displays an image, to proceed in the light guide
Data Source
AI summary
An optical system for a virtual image display device includes a light guide, a reflector, and an intermediate image forming portion. The light guide is configured to guide image light emitted from an image display element that displays an image, to proceed in the light guide. The light guide includes a partial reflector, a first portion on one side of the partial reflector, and a second portion on another side of the partial reflector. The partial reflector transmits the image light incident from the first portion and reflects the image light incident from the second portion to guide the image light to exit the light guide. The reflector reflects the image light transmitted through the partial reflector and the second portion back to the partial reflector. The intermediate image forming portion forms an intermediate image with the image light in the light guide.