HUD Reflection Mirror Textured Surface Stray Light Reduction
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Solution Overview
Problem
Existing head-up displays (HUDs) suffer from a decrease in video quality due to stray light reflected from the outer peripheral portion of the reflection mirror, particularly when the backlight is lit or external light enters, leading to reduced image quality.
Innovation Solution
A head-up display with a reflection mirror featuring a textured surface on its outer peripheral portion, designed to deflect reflected light away from the driver's line of sight, using a saw-tooth like cross-section texture with a pitch range of 0.1 mm to 5 mm and an angle range of 0 to 90 degrees, which is more cost-effective than low-reflection coatings and provides enhanced stray light reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a low reflection coating is applied to suppress stray light, then stray light reduction is achieved, but manufacturing cost increases
Solution Approach 1:
The patent changes the physical parameters of the reflection mirror by forming a textured surface with specific pitch (0.1-5mm) and angle (0-90 degrees) characteristics on its outer peripheral portion. This parameter change enables the mirror surface to deflect stray light away from the driver's line of sight through geometric optics rather than requiring expensive low-reflection coatings, thus reducing manufacturing cost while maintaining stray light suppression effectiveness.
Solution Approach 2:
The patent applies the textured surface treatment specifically to the outer peripheral portion of the reflection mirror where stray light reflection occurs, rather than coating the entire mirror surface. This localized approach targets the specific area causing the problem, reducing material and manufacturing costs compared to full-surface low-reflection coatings while effectively suppressing stray light in the critical region.
2Ease of manufacture
If the outer peripheral portion of the reflection mirror is left smooth, then manufacturing is simpler, but stray light enters the projection image light reducing video quality
Solution Approach 1:
The patent applies different surface characteristics to different regions of the reflection mirror: the central region remains smooth for optimal video light reflection, while the outer peripheral portion is textured to deflect stray light. This local differentiation solves the contradiction by maintaining manufacturing simplicity for the majority of the mirror surface while adding precision treatment only where needed to prevent stray light contamination of the projection image.
Solution Approach 2:
The patent segments the reflection mirror into functional zones: a central smooth region for primary video light reflection and an outer peripheral textured region for stray light deflection. This segmentation allows each zone to be optimized for its specific function, maintaining overall manufacturing simplicity while achieving high video quality through targeted precision treatment of the peripheral segment.
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 textured surface effectively reduces stray light luminance to 1/10 or less, preventing a decrease in video quality and enabling high-quality virtual video display, while being more economical and efficient than conventional low-reflection coatings.
Implementation Method 1
the reflection mirror includes, on its outer peripheral portion, deflection means configured to direct a reflected light in a direction different from a direction toward a line of sight of the driver
Data Source
AI summary
A head up display that projects a video onto a windshield of a transportation, thereby displaying a virtual image related to the video to a driver, the head up display including a video display device including a light source and a display element and configured to form the video, and video light projecting means configured to project and reflect a video light emitted from the video display device on the windshield, thereby displaying the virtual image in front of the transportation, the video light projecting means including a reflection mirror that reflects the video light emitted from the video display device to the windshield, and the reflection mirror including, on its outer peripheral portion, deflection means configured to direct a reflected light in a direction different from a direction toward a line of sight of the driver.