Compact Projection Lens Optical System for Wearable AR
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Solution Overview
Problem
Current projection devices for wearable devices, such as augmented reality glasses, face challenges in achieving a small form factor and lightweight design due to the use of Liquid Crystal on Silicon (LCoS) and Digital Micromirror Device (DMD) display panels, which require light combiners like polarizing beam splitters and prisms, limiting the reduction of total volume.
Innovation Solution
A projection lens optical system comprising six sequentially arranged lenses with specific refractive powers (positive, negative, positive, negative, negative, and positive) and a short back focal length, designed to work with self-emissive display panels like micro LEDs or OLEDs, ensuring a compact and lightweight configuration while maintaining telecentricity and high light efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If LCoS or DMD display panels are used in projection devices, then display functionality is achieved, but the total volume cannot be reduced due to required light combiners and illumination optical systems
Solution Approach 1:
The patent removes the prism and polarizing beam splitter from the optical system, extracting these components that caused volume increase. By eliminating the need for light combiners when using self-emissive display panels, the invention achieves significant volume reduction while maintaining projection functionality.
Solution Approach 2:
The projection lens optical system is designed to work directly with self-emissive display panels (micro LED, OLED), making it universally applicable to various display types without requiring additional light combiners. This multi-functional design eliminates the need for separate illumination optical systems.
2Volume of moving object
If a compact optical system is designed for wearable devices, then device size is reduced, but maintaining telecentricity and light efficiency becomes more difficult
Solution Approach 1:
The optical system is divided into six lenses with specific refractive powers arranged in sequence. This segmentation allows each lens to contribute specifically to maintaining telecentricity and light efficiency while keeping the overall system compact. The conditional expressions define precise relationships between lens parameters to ensure optical performance.
Solution Approach 2:
The patent uses specific conditional expressions (LB/f≤0.5, LT/f≤1.5, Ω≥30 degrees, CRA≤15 degrees) to control and optimize the optical parameters. By carefully adjusting these parameters, the system achieves both compact size and maintained optical performance, resolving the contradiction between device size and reliability.
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 enables a compact and lightweight projection device suitable for wearable devices, providing a wide field of view and high light efficiency, suitable for augmented and mixed reality applications, with improved manufacturability and reduced heat susceptibility.
Implementation Method 1
The first to sixth lenses sequentially have positive, negative, positive, negative, negative, and positive refractive power
Data Source
AI summary
Provided are a projection lens optical system, and a projection device and a wearable device including the projection device. The projection lens optical system is used in a projection device of a wearable device and includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens, sequentially arranged from an emission area to an image plane, wherein the first lens has a positive refractive power, the second lens has a negative refractive power, the third lens has a positive refractive power, the fourth lens has a negative refractive power, the fifth lens has a negative refractive power, and the sixth lens has a positive refractive power, wherein the projection lens optical system satisfy the following Conditional Expression:LB/f≤0.5.