Pyroelectric Sensor Abrasion-Resistant Coating
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Solution Overview
Problem
Pyroelectric sensors face challenges in maintaining high-resolution imaging due to the slow heat transfer and lateral diffusion caused by thick abrasion-resistant coatings, which hinder the reproduction of thermal patterns and increase electrical consumption.
Innovation Solution
A heterogeneous protective coating with pillars of high thermal conductivity embedded in a low thermal conductivity abrasion resistance layer, allowing rapid vertical heat transfer while minimizing lateral heat transfer, thus enhancing image contrast and reducing electrical consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick abrasion-resistant resin layer is used to protect the sensor, then abrasion resistance is improved, but heat transfer speed decreases and lateral heat diffusion increases
Solution Approach 1:
The patent uses a composite coating structure consisting of a resin matrix combined with high thermal conductivity particles (metal or ceramic). This composite material simultaneously provides abrasion resistance from the resin and rapid heat transfer through the thermally conductive particles, resolving the contradiction between protection and heat transfer speed.
Solution Approach 2:
The coating is designed with non-uniform thermal conductivity distribution by dispersing high thermal conductivity particles throughout the resin matrix. This creates local thermal pathways that accelerate heat transfer specifically where needed, while maintaining the overall abrasion-resistant property of the coating.
2Reliability
If a thick abrasion-resistant coating is used, then protection is improved, but reading time increases due to slow heat transfer
Solution Approach 1:
The composite coating with thermally conductive particles enables rapid heat transfer through the protective layer, reducing the time required for thermal equilibrium without compromising the thickness and abrasion resistance of the coating.
Solution Approach 2:
The coating's thermal conductivity parameter is enhanced by incorporating high thermal conductivity particles, which directly reduces the thermal diffusion time through the coating layer, thereby decreasing reading time while maintaining protective function.
3Reliability
If a thick abrasion-resistant coating is used, then protection is improved, but electrical consumption increases
Solution Approach 1:
The thermally conductive particles create efficient heat transfer pathways that reduce the energy required to achieve thermal contrast in the imaging process, lowering electrical consumption while maintaining the protective coating thickness.
Solution Approach 2:
By changing the thermal conductivity parameter of the coating through particle incorporation, the energy required for heat transfer is reduced, which directly decreases the electrical power needed to operate the sensor.
4Reliability
If a thick abrasion-resistant coating is used, then protection is improved, but image resolution decreases due to lateral heat conduction
Solution Approach 1:
The composite structure with thermally conductive particles creates preferential vertical heat transfer pathways that minimize lateral heat diffusion. This maintains thermal contrast between adjacent pixels, preserving image resolution while keeping the coating thick for protection.
Solution Approach 2:
The localized thermal pathways formed by the particles concentrate heat transfer in vertical directions, reducing lateral heat conduction that would otherwise blur thermal patterns and degrade image resolution.
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
This solution improves image contrast and reduces reading time by increasing vertical heat transfer speed, allowing for a thinner abrasion resistance layer without compromising protection, and simplifies material selection by eliminating the need for precise thickness control.
Implementation Method 1
A pyroelectric sensor exploits the pyroelectric properties of a material, that is, its ability to generate electrical charges in response to a change in temperature
Implementation Method 2
Heat transfer between the skin and the sensor's contact surface occurs by conduction, leading to an initial temporal temperature variation
Data Source
Figure 1A~1C
Figure 2A~2B
Figure 3A~3C
AI summary
The invention relates to a thermal pattern sensor (100) comprising several pixels arranged on a substrate (110). Each pixel has a pyroelectric capacitor formed by at least one portion of pyroelectric material located between a lower and an upper electrode. The sensor includes an abrasion-resistant coating (180), located on the side opposite the substrate and comprising pillars (183) embedded in an abrasion-resistant layer (182; 182'), the pillars having a thermal conductivity strictly greater than that of the abrasion-resistant layer. The invention makes it possible to reconcile a large thickness of the abrasion-resistant coating with a high heat transfer rate through it.