Virtual Image Display Device with Absorber Layer for Concave Transmissive Mirror
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Solution Overview
Problem
Existing virtual image display devices using transmissive reflective surfaces and concave mirrors suffer from image light leakage, allowing external observers to see the displayed images, compromising privacy.
Innovation Solution
A virtual image display device incorporating a concave transmissive mirror with a transmissive reflective surface and an absorber layer or absorption film on its external side, which reduces the intensity of image light transmitted outward, combined with a transmissive tilted mirror to direct image light towards the exit pupil, while maintaining see-through functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transmissive reflective surface is used to reflect image light, then the device can maintain see-through functionality, but image light leaks to the outside allowing external observers to see displayed images
Solution Approach 1:
The patent applies local quality by making different regions of the optical system have different optical properties. The beam splitter has a transmissive reflective surface that reflects image light while transmitting external light. The absorption member is strategically positioned to absorb only the image light that passes through the beam splitter, while external light paths remain unaffected. This localized application of different optical properties resolves the contradiction between maintaining see-through functionality and preventing image light leakage.
Solution Approach 2:
The absorption member acts as an intermediary element between the beam splitter and the external environment. It selectively absorbs image light that would otherwise leak outward, while being transparent or non-interfering to external light that needs to pass through to the user. This intermediary component resolves the contradiction by mediating between the need for see-through functionality and the need to prevent image light leakage.
2Object-generated harmful factors
If an absorption member is added to reduce image light leakage, then privacy is enhanced, but device complexity increases
Solution Approach 1:
The patent merges the absorption function with existing optical components. The absorption member is integrated into the optical path in a way that combines light absorption functionality with the overall optical system design. By merging rather than adding separate complex subsystems, the patent reduces image light leakage while minimizing the increase in device complexity.
Solution Approach 2:
The absorption member can be implemented as a thin film or coating on existing optical surfaces, such as the beam splitter or a separate optical element. This thin-film approach absorbs image light effectively while adding minimal bulk, weight, and structural complexity to the device. The flexible implementation allows integration without significantly increasing device complexity.
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
Effectively suppresses image light leakage, enhancing privacy by reducing the intensity of image light visible from the outside while ensuring the wearer can see virtual images superimposed on external views.
Implementation Method 1
image light is reflected by a transmissive tilted mirror such that the light impinges on a concave transmissive mirror
Implementation Method 2
The absorption member absorbs other part of the image light, the absorption member is provided along the second surface of the transmissive member
Implementation Method 3
the first reflection surface reflects a part of the image light and transmits other part of the image light... reflect, toward the transmissive tilted mirror, the image light reflected by the transmissive tilted mirror to form an exit pupil
Data Source
AI summary
A virtual image display device includes an image light generation device generating image light, a transmissive tilted mirror reflecting the image light from the image light generation device, and a concave transmissive mirror having a concave shape and reflecting, toward the transmissive tilted mirror, the image light reflected by the transmissive tilted mirror to form an exit pupil. The virtual image display device further includes an absorber layer or an absorption film on an external side of a transmissive reflective surface formed in the concave transmissive mirror.