Prism Lens Group Propagation Optical System for Wide Angle View

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Solution Overview

Problem

Existing virtual image display apparatuses face challenges in providing a wide angle of view while maintaining a compact size, as increasing the diameter of the propagation optical system to achieve this results in discomfort and burden due to increased size and weight, particularly in head-mounted displays like smart glasses.

Innovation Solution

A propagation optical system is designed with a prism having negative power and a lens group with positive power, arranged between the image display element and the light guide element, which reduces the size of the system while ensuring a wide angle of view by bending and guiding light effectively, and distributing the load to reduce discomfort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the diameter of the propagation optical system is increased to achieve a wide angle of view, then the angle of view is improved, but the size and weight of the system increase causing user discomfort and burden

Engineering Contradiction:

Improveangle of viewVSAvoidweight of propagation optical system

Core Design Contradiction:

Adaptability or versatilityVSWeight of stationary object

Solution Approach 1:

The propagation optical system is divided into multiple functional components: a negative lens group (first lens group) positioned closer to the image display element, and a positive lens group (second lens group) positioned closer to the light guide element. This segmentation allows each group to contribute differently to light propagation, enabling a wide angle of view while keeping the overall system diameter compact and weight reduced.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If the diameter of the propagation optical system is increased to achieve a wide angle of view, then the angle of view is improved, but the size of the system increases causing user discomfort and burden

Engineering Contradiction:

Improveangle of viewVSAvoiddiameter of propagation optical system

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

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 allows for a compact propagation optical system that provides a wide angle of view, reduces user discomfort, and distributes the load to prevent burden, enabling longer wearability of head-mounted displays.

Implementation Method 1

The propagation optical system may include a prism that bends the propagation direction of the image light from an image display element

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

a lens group having positive power. The prism and the lens group are arranged between the image display element and the light guide element along an optical axis

Methodology Applied

Scientific EffectLens focusing: Lens

Data Source

PatentUS12117668B2Propagation optical system, virtual image display apparatus, and head-mounted display

Publication Date: 2024.10.15 RICOH CO LTD

AI summary

In a propagation optical system to propagate light from an image display element to a light guide element, the propagation optical system includes: a prism having a first surface having negative power to which light emitted from the image display element enters; and a lens group having positive power. The prism and the lens group are arranged between the image display element and the light guide element along an optical axis, and the prism is closer to the image display element than to the light guide element.