Virtual Image Display Optics for Sunlight-Resistant Contrast
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Solution Overview
Problem
Existing head-up display devices using liquid crystal displays face issues with sunlight causing damage to the polarizing plate and liquid crystal panel, leading to decreased contrast and resolution due to sunlight being condensed by the concave surface mirror, and reflected light superimposing on the virtual image, which affects image quality.
Innovation Solution
An information display device with an optical element containing a reflective polarizing plate fixed to a substrate, which selectively reflects P-polarized light components, and a moisture-proof film to reduce sunlight's impact, combined with aberration correction using a concave surface mirror and lens elements to enhance image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a concave surface mirror is used to provide high-definition virtual images, then image quality is improved, but sunlight is condensed and causes damage to the liquid crystal panel and polarizing plate
Solution Approach 1:
A reflective polarizing plate is introduced as an intermediary component in the optical path between the liquid crystal panel and the concave surface mirror. This plate selectively reflects P-polarized light components of sunlight while allowing image light to pass through, thereby preventing sunlight condensation damage to the liquid crystal panel while maintaining the high-definition image quality provided by the concave surface mirror.
2Illumination intensity
If the front glass is used as a reflective surface to expand the viewing region, then visibility is improved, but contrast performance decreases due to light reflection superimposing on the virtual image
Solution Approach 1:
The reflective polarizing plate changes the polarization state parameter of light in the optical path. By selectively reflecting P-polarized light components and transmitting other polarization components, it modifies the light parameters to reduce harmful reflections while maintaining visibility, thereby improving contrast performance without sacrificing viewing region expansion.
3Reliability
If a transmissive and reflective member (hot mirror) is provided to reduce sunlight damage, then reliability is improved, but device complexity increases
Solution Approach 1:
The reflective polarizing plate serves multiple functions simultaneously: it acts as a protective filter against sunlight damage, maintains high-definition image quality, improves contrast performance by reducing reflected light superimposition, and allows the system to use the front glass for viewing region expansion. This multi-functionality reduces overall device complexity compared to separate components for each function.
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 device minimizes sunlight damage to the liquid crystal panel and polarizing plate, improving contrast and resolution by reducing the P-polarized light component, ensuring high reliability and visibility of the virtual image.
Implementation Method 1
an optical element 3 having a function of reflecting a P-polarized light component is provided between the lens element 2 for correction and the image display device 4
Implementation Method 2
sunlight that transmits through the front glass and that is condensed by a concave surface mirror under a predetermined condition in the daytime causes so-called burning
Implementation Method 3
a moisture-proof film is provided on a surface of the reflective polarizing plate
Data Source
AI summary
An information display device that displays image information as a virtual image on a projection surface, the device including: an opening portion at a part of the housing, image light generating means for generating image light, image light processing means for performing a predetermined optical process on the image light, and image projecting means for projecting the image light such that a viewer can recognize the image information as the virtual image in front of the projection surface, and an optical element in which a reflective polarizing plate is fixed to a substrate having a transmissive property with an adhesive agent or with a pressure-sensitive adhesive agent is provided in a part of an optical path inside the housing, as means for selectively reflecting a P-polarized light component of light in a visible light region, and a moisture-proof film is provided on a surface of the reflective polarizing plate.