Explosion-Proof Thermal Imaging System with Composite Zinc Selenide Window

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Infrared cameras used in explosive environments face challenges with bulky, costly explosion-proof housings that compromise optical performance due to thick windows needed for pressure containment, and existing solutions do not adequately address the impact resistance required for explosion-proof approvals.

Innovation Solution

The thermal imaging system incorporates an explosion-proof housing with a zinc selenide window placed within the lens assembly, reducing the window's diameter and thickness while maintaining pressure containment, and uses a composite window design with polyamide layers for enhanced impact resistance, along with a reflector to protect the window from impacts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the window thickness is increased to contain explosive pressures, then the mechanical robustness and explosion-proof rating are improved, but the transmissivity of the window is reduced and the radiometric temperature measurements are adversely affected

Engineering Contradiction:

Improveexplosion-proof ratingVSAvoidradiometric temperature measurement

Core Design Contradiction:

StrengthVSMeasurement precision

Solution Approach 1:

The patent employs a composite window structure consisting of multiple layers including zinc selenide and polyamide materials. This composite design allows the window to achieve the necessary mechanical strength and explosion-proof rating while maintaining adequate infrared transmissivity for accurate radiometric measurements, thus resolving the contradiction between structural robustness and measurement precision.

Inventive Principle:

Principle #40Composite materials

2Strength

If the window thickness is increased to contain explosive pressures, then the mechanical robustness is improved, but the cost of the window increases

Engineering Contradiction:

Improvemechanical robustnessVSAvoidwindow cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The composite window design using zinc selenide and polyamide layers achieves the required mechanical robustness for explosion-proof applications without requiring excessive thickness of expensive materials. This reduces the overall manufacturing cost while maintaining the necessary strength and explosion containment capabilities.

Inventive Principle:

Principle #40Composite materials

3Strength

If the window thickness is increased to contain explosive pressures, then the explosion-proof rating is improved, but the transmissivity of the window is reduced

Engineering Contradiction:

Improveexplosion-proof ratingVSAvoidinfrared transmissivity

Core Design Contradiction:

StrengthVSIllumination intensity

Solution Approach 1:

The multi-layer composite structure with zinc selenide and polyamide materials is designed to optimize both mechanical strength and infrared transmissivity. The composite design allows sufficient infrared radiation to pass through while maintaining the window's ability to contain explosive pressures, thus resolving the contradiction between explosion-proof rating and transmissivity.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Different layers of the composite window have different properties optimized for specific functions: zinc selenide layers provide infrared transmissivity while polyamide layers contribute to mechanical strength and pressure containment. This local optimization of material properties throughout the window structure resolves the contradiction between strength and transmissivity.

Inventive Principle:

Principle #3Local quality

4Reliability

If a reflector is added to protect the window from impacts, then the impact resistance is improved, but the device complexity increases

Engineering Contradiction:

Improveimpact resistanceVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The reflector in the thermal imaging system serves multiple functions: it protects the optical window from impacts, reflects infrared radiation toward the sensor to improve image quality, and contributes to the overall structural integrity of the housing. By making the reflector multi-functional, the added complexity is justified by the multiple benefits it provides.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP3317627B1Improved explosive-proof thermal imaging system

Publication Date: 2022.06.01 ROSEMOUNT INC

Figure 1
Figure 2
Figure 3

AI summary

A thermal imaging system (100) is provided. The thermal imaging system includes an explosion-proof housing ( 108) with an optical window ( 120) configured to contain an explosive pressure. The optical window (120) allows electromagnetic thermal energy to pass. A thermal imaging sensor (102) is disposed within the explosion-proof housing (108). Thermal imaging electronics (104) are coupled to the thermal imaging sensor (102) and configured to provide at least one thermal image based on a signal from the thermal imaging sensor (102). A lens assembly (1 12, 1 1.4) is disposed at least in front of the optical window (120) external to the explosion-proof housing (108), A composite optical window (206) for thermal imaging is also provided. In another embodiment, a thermal imaging system (200) includes an explosion-proof housing (204) having an optical window (206) configured to contain an explosive pressure. An infrared (IR) camera (202) is disposed within the explosion-proof housing (204), A reflector (208) reflects electromagnetic thermal energy to the IR camera (202), but prevent an object from impacting the optical window(206).