Moth Eye Layer Translucent Cover for HUD Double Vision

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Solution Overview

Problem

Conventional head-up display devices experience a decrease in display luminance when viewed through polarized sunglasses due to the orientation of the translucent cover member, leading to potential deterioration in display quality and the formation of double images from reflected light.

Innovation Solution

A translucent cover member is designed with a moth eye layer and hard coat layer, made of ultraviolet curable resin, which is oriented to suppress display luminance reduction and prevent double images, using a polycarbonate resin base material for flexibility and protection, and is manufactured through a specific stretching and lamination process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a conventional translucent cover member is used in the head-up display device, then the display structure is simple and easy to manufacture, but display luminance reduction occurs when viewed through polarized sunglasses and double images are formed due to light reflection

Engineering Contradiction:
Improvedisplay luminanceVSAvoidcover member structure
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The translucent cover member is constructed as a composite structure with multiple layers including a base material layer, a moth eye layer, and a hard coat layer. Each layer serves a specific function: the base material provides structural support, the moth eye layer suppresses reflection to prevent double images, and the hard coat layer enhances durability. This composite approach resolves the contradiction by achieving superior optical performance and durability while maintaining manufacturability through layer-by-layer construction.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The cover member incorporates the moth eye layer specifically on the display light emission side where reflection suppression is most critical. This localized application of specialized optical structure addresses the double image problem at the precise location where it occurs, without requiring the entire housing or all components to be redesigned, thus balancing performance improvement with manufacturing complexity.

Inventive Principle:
Principle #3Local quality

2Reliability

If the translucent cover member is made of standard materials, then manufacturing is easier, but display quality deteriorates when viewed through polarized sunglasses

Engineering Contradiction:
Improvedisplay quality consistencyVSAvoidmaterial processing
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent specifies precise parameter ranges for the base material's stretching ratios (longitudinal direction: 2 times or more, transverse direction: 1.03 to 1.2 times) to control the molecular orientation and optical properties of the cover member. By carefully controlling these processing parameters, the cover member achieves consistent optical performance that prevents display quality deterioration when viewed through polarized sunglasses, while maintaining feasibility for industrial manufacturing through defined parameter ranges.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The base material undergoes pre-stretching and molecular orientation treatment before the final assembly of the cover member. This preliminary action of orienting the molecular structure in specific directions during manufacturing ensures that the optical properties are optimized in advance, preventing display quality issues before they occur during actual use with polarized sunglasses.

Inventive Principle:
Principle #10Preliminary action

3Strength

If no protective coating is applied to the translucent cover member, then the manufacturing process is simpler, but the cover member lacks durability and resistance to damage

Engineering Contradiction:
Improvecover member durabilityVSAvoidmanufacturing process
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The hard coat layer is integrated directly onto the base material during the manufacturing process, merging the protective function with the structural component. This combination eliminates the need for separate protective treatments or additional components, as the hard coat layer is applied and cured in-situ during cover member fabrication, thereby enhancing durability without significantly increasing manufacturing complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The hard coat layer forms a composite structure with the base material, creating a multi-layer system where the hard coat provides enhanced strength, scratch resistance, and durability, while the base material maintains structural integrity. This composite approach resolves the contradiction by achieving superior durability through material combination rather than through complex mechanical reinforcement or additional protective components.

Inventive Principle:
Principle #40Composite materials

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 suppresses display luminance reduction and double image formation, enhancing the display quality of the virtual image when viewed through polarized sunglasses by aligning the display luminance reduction axis with the virtual image viewing direction and utilizing a flexible and durable polycarbonate resin base material.

Implementation Method 1

a moth eye layer 22 that is formed on the display light L incidence side of the base material 21 and suppresses the reflection of light

Methodology Applied
Scientific EffectReflection suppression: Anti-Reflective Coating

Implementation Method 2

made of ultraviolet curable resin

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentEP3518021B1Head-up display device
Publication Date: 2021.06.09 NIPPON SEIKI CO LTD
  • EP3518021B1 patent drawingFigure 1~2
  • EP3518021B1 patent drawingFigure 3~4
  • EP3518021B1 patent drawingFigure 5~7

AI summary

The present invention provides a translucent cover member for a head-up display device and a head-up display device that suppress double vision of a virtual image. A translucent cover member (20) covers the opening of a housing, allowing the display light to pass therethrough. The translucent cover member (20) includes a base material (21) made up of a translucent resin and a moth eye layer (22) formed on the display light incidence side of the base material (21) and suppressing reflection of light. According to this structure, the moth eye layer (22) suppresses reflection of the display light. Thereby, it is possible to suppress double vision of a virtual image.