Light Guide Member Peripheral Area for Ghost Light Suppression
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Solution Overview
Problem
Virtual image display devices face challenges in providing a see-through function that suppresses ghost light generation when displaying external and video light simultaneously, as existing solutions like light-shielding members can block necessary light and are insufficient in preventing ghosting due to optical path deviations and reflections.
Innovation Solution
A virtual image display device with a light guide member that includes an effective light flux guide portion and a peripheral area forming portion, where the peripheral area forming portion is designed to prevent unnecessary light from contributing to ghosting by guiding it away from the observer's visual range, using a prism-type member that allows external light to pass through while guiding video light, and features expanded surfaces and surface roughness to reduce ghost light generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a light-shielding member is provided to block flare light and ghost light, then ghost light generation is suppressed, but necessary light may be blocked according to alignment upon arrangement
Solution Approach 1:
The patent extracts and removes the light-shielding member from the optical system, replacing it with a light guide member that has integrated light-shielding functionality. The light guide member's peripheral area forming portion acts as a built-in light shield that blocks ghost light without requiring separate alignment, thus preventing blockage of necessary light while suppressing ghost light generation.
Solution Approach 2:
The patent merges the light-shielding function with the light guide member by integrating the peripheral area forming portion into the light guide member's structure. This combination eliminates the need for separate light-shielding members and their complex alignment, allowing the light guide member to simultaneously guide video light and block ghost light without compromising necessary light transmission.
2Object-generated harmful factors
If a light-shielding member is provided to block ghost light, then ghost light is suppressed, but the device complexity increases due to additional components and alignment requirements
Solution Approach 1:
The patent combines the light-shielding function with the light guide member by integrating the peripheral area forming portion into the light guide member's structure. This merger eliminates the need for separate light-shielding members and their complex alignment, allowing the light guide member to simultaneously guide video light and block ghost light without compromising necessary light transmission.
Solution Approach 2:
The light guide member is designed with multi-functionality, serving both to guide video light through its effective light flux guide portion and to block ghost light through its peripheral area forming portion. This universal design reduces the total number of components and simplifies the overall device structure while addressing multiple optical control requirements.
3Weight of moving object
If the device size is reduced to improve fit, then device weight and thickness are reduced, but optical path deviation increases causing ghost light
Solution Approach 1:
The patent applies local quality by providing the peripheral area forming portion specifically around the effective light flux guide portion of the light guide member. This localized light-shielding structure is positioned precisely where ghost light is generated due to optical path deviation in compact devices, blocking harmful light while maintaining the reduced overall device size and weight.
Solution Approach 2:
The peripheral area forming portion is designed in advance to preemptively block ghost light paths that would result from optical path deviations in compact configurations. By incorporating this light-shielding feature into the light guide member's structure before assembly, the design anticipates and prevents ghost light generation without requiring additional space or complex alignment procedures.
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 effectively reduces ghost light generation, allowing for clear visualization of both video and external images without disturbing the external field of view, while also reducing the device's size and weight, and improving its optical performance with a large angle of view.
Implementation Method 1
a light guide member which has a plurality of surfaces and guides the video light from the video element through reflection and transmission on the plurality of surfaces
Implementation Method 2
the light guide member is a prism-type member which guides the video light from the video element and allows the external light to pass therethrough
Data Source
AI summary
A light guide member which guides video light includes a peripheral area forming portion extending to the outside of an effective light flux guide portion which is an area through which an effective light flux of the video light passes, and thus for example, even when ghost light resulting from components generated by unintended reflection or scattering in a position such as a side surface forming portion of the light guide member may be generated, the side surface forming portion can be separated from the effective light flux guide portion.