Flush Door Sealing Strip Structure for Lightproof Appearance

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Solution Overview

Problem

Existing flush doors, particularly those used as bedroom doors, suffer from light leakage through the gap between the door leaf and frame despite perfect installation, compromising their lightproof nature and high-quality appearance.

Innovation Solution

A sealing strip is designed with a first part made of a material with a higher light reflection factor and lower light absorption factor, and a second part made of a material with a lower reflection and higher absorption factor, ensuring the door maintains a uniform light appearance while preventing light transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If a light-colored sealing strip is used to match the light-colored frame and door leaf, then the aesthetic appearance is improved, but light leakage occurs through the sealing strip

Engineering Contradiction:
Improveaesthetic appearanceVSAvoidlight leakage
Core Design Contradiction:
ShapeVSObject-affected harmful factors

Solution Approach 1:

The sealing strip is designed with spatially varying optical properties: the outer visible surface has light reflection properties matching the frame color, while the inner core has light absorption properties to block light transmission. This local differentiation of material properties resolves the contradiction between aesthetic appearance and light leakage prevention.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The sealing strip comprises a composite structure with an outer layer of light-reflecting material and an inner core of light-absorbing material. This composite design allows the sealing strip to simultaneously achieve the visual appearance of a light-colored seal while preventing light transmission through the door gap.

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If a dark-colored sealing strip is used to prevent light leakage, then lightproof performance is improved, but the aesthetic appearance and uniformity are degraded

Engineering Contradiction:
Improvelight leakageVSAvoidaesthetic appearance
Core Design Contradiction:
Object-affected harmful factorsVSShape

Solution Approach 1:

The sealing strip is designed with spatially varying optical properties: the outer visible surface has light reflection properties matching the frame color, while the inner core has light absorption properties to block light transmission. This local differentiation of material properties resolves the contradiction between aesthetic appearance and light leakage prevention.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The sealing strip exhibits different optical characteristics at different locations: the outer surface appears light-colored to match the frame aesthetics, while the inner core is dark-colored to absorb light. This color differentiation through the thickness of the seal allows simultaneous achievement of aesthetic appearance and lightproof performance.

Inventive Principle:
Principle #32Color changes

3Object-affected harmful factors

If a rebated door design is used to improve lightproofing, then light leakage is reduced, but the elegant flush appearance is compromised

Engineering Contradiction:
Improvelight leakageVSAvoidflush appearance
Core Design Contradiction:
Object-affected harmful factorsVSShape

Solution Approach 1:

The light-blocking function is extracted from the door structure itself and transferred to the sealing strip. Instead of relying on the rebated door structure to prevent light leakage, the invention places a specialized light-absorbing core within the sealing strip, allowing the door to maintain its elegant flush appearance while achieving lightproof performance.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The sealing strip acts as an intermediary element between the door leaf and frame, providing the light-blocking function that would otherwise require structural modifications to the door itself. The light-absorbing core within the seal serves as a mediator to prevent light transmission while preserving the aesthetic flush design.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 ensures the door remains completely lightproof and maintains an elegant, uniform light appearance, even after prolonged use, by using co-extrusion to combine materials with different light reflection and absorption properties.

Implementation Method 1

a first part of the sealing strip extending along the sealing strip, which forms a substantial externally visible surface of the sealing strip, is made of a first material and a second part of the seal extending along the sealing strip is made of a second material, wherein the first material has a higher light reflection factor and a lower light absorption factor than the second material

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 2

a first part of the sealing strip extending along the sealing strip, which forms a substantial externally visible surface of the sealing strip, is made of a first material and a second part of the seal extending along the sealing strip is made of a second material, wherein the first material has a higher light reflection factor and a lower light absorption factor than the second material

Methodology Applied
Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentEP4001579B1Light-tight door
Publication Date: 2025.12.31 HUGA KG
  • EP4001579B1 patent drawingFigure 1~2
  • EP4001579B1 patent drawingFigure 3~4
  • EP4001579B1 patent drawingFigure 5~6

AI summary

To create a particularly elegant light-colored door (10) that is also perfectly suited as a bedroom door, the invention provides a door (10) with a flush door leaf (16) and a frame (14) to which at least one sealing strip (22) is attached for sealing a door gap (42) between the door leaf (16) and the frame, wherein the frame (14) has a light color on a surface that is visible at least when the door (10) is open, wherein a first partial area (24) of the sealing strip (22) extending along the sealing strip (22), which forms an externally visible surface of the sealing strip (22), is made of a first material (28), and a second partial area (28) of the sealing strip (22) extending along the sealing strip (22) is made of a second material (30), wherein the first material (26) has a higher light reflection factor and a lower light absorption factor than the second material (30).