Transmissive Display Depolarization for Polarized Outside Light
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Solution Overview
Problem
Transmissive display apparatuses with see-through optical systems often suffer from luminance deterioration and coloring when outside light with polarization properties is viewed, particularly when using half mirrors with different transmission and reflection properties.
Innovation Solution
A transmissive display apparatus is designed with a semi-transmissive reflection unit and a depolarization member that cancels the polarization state of outside light before it reaches the eye, using a random local orientation phase difference member or high phase difference film to ensure non-polarization, allowing video light and outside light to overlap without significant luminance loss or coloring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a semi-transmissive reflection unit (half mirror) is used to superimpose video light and outside light, then light use efficiency is improved, but outside light with polarization property experiences luminance deterioration and coloring
Solution Approach 1:
A depolarization element is introduced as an intermediary component between the semi-transmissive reflection unit and the observer's eye. This element converts polarized outside light into non-polarized light, enabling it to pass through the polarization-sensitive half mirror without experiencing luminance deterioration or coloring, thus resolving the contradiction between maintaining high light efficiency and preserving outside light quality
Solution Approach 2:
The polarization state of outside light is changed from polarized to non-polarized by the depolarization element. This parameter change allows the outside light to be transmitted through the semi-transmissive reflection unit with uniform transmission characteristics for both s and p polarized components, preventing the luminance deterioration and coloring that would otherwise occur
2Reliability
If a semi-transmissive reflection unit with polarization-dependent transmission is used, then video light superimposition is improved, but outside light transmission quality deteriorates due to polarization filtering
Solution Approach 1:
The depolarization element converts the harmful polarized state of outside light into a beneficial non-polarized state. By doing so, it eliminates the differential transmission of s and p polarized components that causes luminance deterioration and coloring, while allowing the semi-transmissive reflection unit to maintain its video light superimposition functionality
Solution Approach 2:
The depolarization element serves as a mediator that modifies the outside light before it interacts with the polarization-sensitive semi-transmissive reflection unit. This intermediary action ensures that the outside light does not experience the harmful polarization filtering effects, thereby maintaining transmission quality while preserving the video light superimposition capability
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 prevents luminance deterioration and coloring, enabling clear viewing of outside light with polarization properties by ensuring the outside light enters a non-polarization state before being viewed, thus maintaining image clarity and visibility.
Implementation Method 1
a depolarization member that is disposed in a region more outside than a light-guiding region of the video light extending from the video element to an eye assumption position assumed as a position of an eye via the semi-transmissive reflection unit, using the eye assumption position as a criterion, and cancels a polarization state of the outside light passing through the semi-transmissive reflection unit and incident on the eye assumption position
Data Source
AI summary
imagelight and outside light are viewed to overlap in a half mirror layer which is a semi-transmissive reflection unit from a state in which a polarization property of the outside light is canceled by a depolarization member disposed more outside than a light-guiding region of the imagelight.