Pressure Sensor Protection Film Corner Placement

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Solution Overview

Problem

Pressure sensors face decreased accuracy due to deposits adhering to the surface of the diaphragm's recess, which affects pressure detection.

Innovation Solution

A pressure sensor design featuring a flexibly deformable diaphragm with a protection film covering the recess, where the film's corner portion is located outside the diaphragm in the in-plane direction, preventing deposit adhesion and minimizing its impact on diaphragm deflection characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protection film is provided on the surface of the recess, then deposit adhesion is suppressed, but the film may interfere with diaphragm deflection characteristics

Engineering Contradiction:

Improvepressure detection accuracyVSAvoiddiaphragm deflection interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The protection film is designed with different properties in different regions: the corner portion has different mechanical properties compared to the main body, allowing it to be positioned outside the diaphragm while still providing protection. This local differentiation enables the film to suppress deposit adhesion without interfering with diaphragm deflection.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The protection film extends in the in-plane direction beyond the diaphragm boundary, utilizing the dimensional space outside the sensitive detection area. By positioning the corner portion in the in-plane direction outside the diaphragm, the film provides coverage without constraining the diaphragm's thickness-direction deflection.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If the protection film covers the entire recess surface, then deposit adhesion is maximally suppressed, but manufacturing complexity increases

Engineering Contradiction:

Improveprotection effectivenessVSAvoidfilm formation complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The protection film is segmented into distinct functional regions: a main body portion covering the recess surface and a corner portion extending outside the diaphragm. This segmentation allows simplified formation processes while maintaining effective protection coverage.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS10921205B2Pressure sensor including protective film to avoid adhesion of foreign material

Publication Date: 2021.02.16 DENSO CORP

AI summary

A pressure sensor generates an electrical output according to a fluid pressure in a detection space applied to a diaphragm. The diaphragm is flexibly deformable in a thickness direction. The pressure sensor includes a pressure receiving recess defining the detection space and a protection film covering the pressure receiving recess. The protection film has a corner portion provided in an inner corner area of the pressure receiving recess and a thin film portion having a uniform thickness. The corner portion is located outside the diaphragm in an in-plane direction orthogonal to the thickness direction.