Urethane Acrylate Camera Cover Coating for Scratch Resistance

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Solution Overview

Problem

Existing camera covers for surveillance cameras are prone to scratches and high costs due to long baking times required for hard coatings, which can lead to cracks and reduced image quality.

Innovation Solution

A camera cover with a dome-shaped substrate made of polycarbonate resin and a coating of urethane acrylate resin, which is photocurable, reducing manufacturing costs and providing a scratch-resistant and weather-resistant surface with controlled viscosity and thickness to maintain image resolution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a hard coating with silicone resin is applied to make the camera cover scratch-resistant, then scratch resistance is improved, but cracks may occur after film deposition and baking time is excessively long

Engineering Contradiction:
Improvescratch resistanceVSAvoidcrack resistance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the coating material from silicone resin to a specific formulation containing polyurethane resin (30-70 wt%), acrylic resin (10-40 wt%), and inorganic filler (10-40 wt%). This parameter change in material composition provides both scratch resistance and crack resistance, eliminating the reliability issue while maintaining the strength improvement.

Inventive Principle:
Principle #35Parameter changes

2Duration of action of stationary object

If a hard coating is applied to protect the camera cover, then durability is improved, but manufacturing cost increases due to long baking time

Engineering Contradiction:
Improvecoating durabilityVSAvoidbaking time
Core Design Contradiction:
Duration of action of stationary objectVSLoss of time

Solution Approach 1:

The patent replaces the thermal curing mechanism (baking) with a photocuring mechanism using UV light. The coating formulation includes photopolymerization initiators that enable curing upon UV exposure, substituting the time-consuming thermal process with a faster optical process, thereby reducing manufacturing time while maintaining coating durability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Strength

If a coating is applied to the camera cover, then scratch resistance is improved, but image resolution may be affected

Engineering Contradiction:
Improvescratch resistanceVSAvoidimage resolution
Core Design Contradiction:
StrengthVSMeasurement precision

Solution Approach 1:

The patent applies the coating with controlled local properties: the inorganic filler (such as silica or alumina particles with 0.1-10 μm diameter) is distributed to provide scratch resistance, while the resin matrix maintains optical clarity. The coating thickness and composition are optimized locally to ensure scratch protection without compromising the transparency and resolution required for surveillance imaging.

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 camera cover achieves a sufficient resolution and improved weather resistance with reduced mottling and scratches, maintaining image quality while being cost-effective and easy to manufacture.

Implementation Method 1

a coating of urethane acrylate resin, which is photocurable

Methodology Applied
Scientific EffectPhotocuring: Photopolymerisation

Data Source

PatentEP4119619A1Camera cover, image capturing device, and method of manufacturing camera cover
Publication Date: 2023.01.18 CANON KK
  • EP4119619A1 patent drawingFigure 1~2
  • EP4119619A1 patent drawingFigure 3~4
  • EP4119619A1 patent drawingFigure 5

AI summary

A camera cover (110) is provided. The camera cover (110) has a coating (1500) formed on a surface of the camera cover (110). The coating (1500) contains a urethane acrylate resin. The camera cover (110) has a dome shape and is designed to protect an image capturing unit (100). An arithmetic mean roughness Ra of a surface of the coating (1500) is no greater than 0.8 µm.