Wedge Interlayer Film for Uniform HUD Laminated Glass Visibility

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Solution Overview

Problem

Existing interlayer films for laminated glass with varying thicknesses at one end and the other end cause visibility variations across the glass sheet, particularly in head-up displays, which become more pronounced with expanded display areas.

Innovation Solution

An interlayer film with a thermoplastic resin and heat shielding compound, featuring a thicker end and a thinner end with a 0.1 mm or more thickness difference, includes regions with varying heat shielding compound content to maintain uniform visible and solar transmittance within 4% and 5.5% respectively, ensuring consistent visibility and heat shielding across the glass sheet.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a wedge-shaped interlayer film is used to suppress double images in HUD, then the visibility of measured information is improved, but visibility variation occurs across different areas of the glass sheet

Engineering Contradiction:
Improvevisibility of measured informationVSAvoidvisibility uniformity
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The interlayer film incorporates a gradient structure where the concentration of heat shielding particles varies across different regions. Specifically, the particle concentration is higher in the first area and lower in the second area, creating local quality differences that compensate for the wedge-shaped thickness variation and maintain uniform visible light transmittance and visibility across the entire glass sheet.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention changes the concentration parameter of heat shielding particles across different regions of the interlayer film. By adjusting the particle concentration from the first area to the second area, the optical properties of the interlayer film are modified to compensate for thickness variations, thereby maintaining uniform visibility and transmittance characteristics.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If heat shielding particles are added to the interlayer film to cut off infrared rays, then heat shielding properties are improved, but visibility variation and double display images occur in HUD

Engineering Contradiction:
Improveheat shielding propertiesVSAvoidvisibility uniformity
Core Design Contradiction:
Object-affected harmful factorsVSIllumination intensity

Solution Approach 1:

The interlayer film uses non-uniform distribution of heat shielding particles, with different concentrations in different areas. This local quality variation allows the film to provide adequate heat shielding while maintaining uniform visible light transmittance, preventing visibility variation and double display images in HUD applications.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The interlayer film is composed of a resin base material combined with heat shielding particles (such as metal oxide particles). This composite structure provides both the necessary heat shielding properties and the optical transparency required for HUD visibility, with the particle concentration optimized to balance these two functions.

Inventive Principle:
Principle #40Composite materials

3Illumination intensity

If the thickness difference between ends of the interlayer film is increased to suppress double images, then the focusing of reflected displays is improved, but visibility variation across the glass sheet becomes more pronounced

Engineering Contradiction:
Improvefocus of reflected displaysVSAvoidvisibility uniformity
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The interlayer film compensates for the wedge-shaped thickness variation by implementing local quality differences through gradient distribution of heat shielding particles. The particle concentration is adjusted in different regions to offset the optical path differences caused by thickness variation, maintaining uniform visibility while preserving the double image suppression effect.

Inventive Principle:
Principle #3Local quality

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 achieves uniform visibility and heat shielding properties across the laminated glass sheet, enhancing visibility and maintaining consistent transmittance levels, addressing issues of visibility variation and expanded head-up display areas.

Implementation Method 1

the energy amount of an infrared ray with a wavelength of 780 nm or longer which is longer than that of visible light is small as compared with an ultraviolet ray. However, the thermal action of infrared rays is large, and when infrared rays are absorbed into a substance, heat is released from the substance.

Methodology Applied
Scientific EffectInfrared absorption: Absorption (EM radiation)

Data Source

PatentEP3357893B1Interlayer film for laminated glass and laminated glass
Publication Date: 2025.10.15 SEKISUI CHEMICAL CO LTD
  • EP3357893B1 patent drawingFigure 1~3
  • EP3357893B1 patent drawingFigure 4~6
  • EP3357893B1 patent drawingFigure 7~9

AI summary

There is provided an interlayer film for laminated glass with which the visibility can be made uniform over the whole area of laminated glass. The interlayer film for laminated glass according to the present invention contains a thermoplastic resin and a heat shielding compound and has one end and the other end being at the opposite side of the one end and having a thickness thicker than the one end, the absolute value of a difference between the thickness of a thickest portion and the thickness of a thinnest portion is 0.1 mm or more, and in a sheet of laminated glass prepared by sandwiching the interlayer film between two sheets of heat ray-absorbing plate glass with a thickness of 2.1 mm, the absolute value of a difference between the visible light transmittance at the thickest portion of the interlayer film and the visible light transmittance at the thinnest portion of the interlayer film is 4% or less.