See-through Head Mounted Display Light Control Element
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Solution Overview
Problem
Existing see-through head-mounted displays are bulky and heavy due to large image sources and optical components, leading to uncontrolled light escape, causing eyeglow and reduced privacy.
Innovation Solution
A thin and lightweight see-through head-mounted display design incorporating a partially reflecting mirror and a light control element to selectively block escaping image light, while allowing more incoming scene light, using polarization control to reduce eyeglow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a partially reflecting mirror is used to provide see-through view and display image, then the display can show overlaid images, but image light escapes through the front causing eyeglow and privacy loss
Solution Approach 1:
A light control element is introduced as an intermediary component between the partially reflecting mirror and the external environment. This element selectively controls light transmission based on polarization state, allowing scene light to pass through while blocking escaping image light, thereby eliminating eyeglow without compromising the see-through display functionality
Solution Approach 2:
The patent utilizes polarization state as a controlling parameter to differentiate between incoming scene light and outgoing image light. By applying a polarizing filter, the system changes the transmission parameter based on light direction - allowing unpolarized or differently polarized scene light through while blocking the polarized image light that would otherwise escape and cause eyeglow
2Reliability
If traditional image sources and optical components are used, then images can be displayed, but the head mounted display becomes bulky and heavy
Solution Approach 1:
The patent employs thin-film optical components including a thin partially reflecting mirror and a thin polarizing light control element. These thin-film structures replace traditional bulky optical components, maintaining the necessary optical functions while dramatically reducing the overall weight and thickness of the head mounted display device
Solution Approach 2:
The patent combines multiple optical functions into integrated thin-film components. The partially reflecting mirror simultaneously provides see-through capability and image reflection, while the light control element integrates polarization filtering and light control functions, eliminating the need for separate heavy components and reducing overall device weight
3Object-generated harmful factors
If a light control element blocks escaping light, then privacy is improved, but more scene light must be transmitted to maintain visibility
Solution Approach 1:
The patent exploits polarization state as a discriminating parameter to differentiate between incoming and outgoing light. The polarizing light control element is oriented to block the polarization state of escaping image light while transmitting the orthogonal polarization state or unpolarized scene light, thereby achieving privacy protection without compromising visibility
Solution Approach 2:
The patent utilizes polarization-dependent transmission characteristics similar to color filtering. The polarizing filter selectively transmits or blocks light based on its polarization 'orientation color,' allowing scene light to pass through while blocking image light, achieving both privacy and visibility requirements simultaneously
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 provides a thinner, lighter display that effectively reduces eyeglow and maintains privacy by blocking a higher percentage of escaping light while transmitting more scene light, enhancing user experience and visibility.
Implementation Method 1
a partially reflecting mirror reflecting and transmitting respective portions of image light from an image source and scene light from a see-through view of an external environment
Implementation Method 2
A light control element is provided to block escaping light comprised of the transmitted portion of image light
Implementation Method 3
using polarization control to reduce eyeglow
Data Source
AI summary
A see-through head mounted display apparatus with reduced eyeglow is disclosed. Two images of a scene are combined and presented to a user, the combined image including portions of reflected image light and light from a see-through view of an external environment. The apparatus includes a light control element to block escaping portions of image light and reflected portions of scene light, while allowing incoming scene light to be transmitted from the external environment. The images are produced using a partially reflecting mirror and a light control element. A portion of scene light is transmitted through the partially reflecting mirror and is combined with a portion of image light reflected from the partially reflecting mirror. A light control element is used to block a portion of the image light and a portion of the scene light to reduce eyeglow.