Sphygmomanometer Cuff Back Plate Curvature for Uniform Pressure

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Solution Overview

Problem

Conventional sphygmomanometers with narrow cuff dimensions experience stress concentration at the edge portions, leading to non-uniform pressing force distribution, resulting in measurement errors during blood pressure measurement.

Innovation Solution

A sphygmomanometer design featuring a bag-shaped sensing cuff with a back plate and a pressing member, where the surface facing the measurement site on both sides in the width direction is curved away from the site toward the tips, reducing stress concentration and ensuring uniform pressure distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the width-direction dimension of the cuff is reduced to improve appearance and wearing comfort, then the cuff becomes narrower, but stress concentration occurs at the edge portions causing non-uniform pressing force and measurement errors

Engineering Contradiction:

Improvewidth-direction dimension of cuffVSAvoidblood pressure measurement accuracy

Core Design Contradiction:

Length of moving objectVSMeasurement precision

Solution Approach 1:

The back plate is designed with non-uniform thickness, where the thickness increases from the edge portions toward the central portion. This local variation in thickness creates a corresponding variation in pressing force distribution, compensating for the stress concentration effect at the edges. As a result, the overall pressing force becomes more uniform across the cuff width, maintaining measurement accuracy even with a narrow cuff dimension.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The thickness parameter of the back plate is varied across its width. By making the back plate thicker at the central portion and thinner at the edge portions, the pressing force distribution is adjusted to counteract stress concentration. This parameter change allows the cuff to maintain uniform pressing force despite having a reduced width-direction dimension.

Inventive Principle:

Principle #35Parameter changes

2Shape

If the cuff width is reduced to improve appearance, then the device looks more compact, but uniform pressure distribution becomes difficult to achieve

Engineering Contradiction:

Improveappearance and compactnessVSAvoiduniformity of pressing force distribution

Core Design Contradiction:

ShapeVSManufacturing precision

Solution Approach 1:

The back plate incorporates local quality variations through its non-uniform thickness design. The central portion has greater thickness to provide higher pressing force, while the edge portions have reduced thickness to minimize stress concentration. This local differentiation achieves uniform overall pressing force distribution, enabling compact cuff design without sacrificing manufacturing precision.

Inventive Principle:

Principle #3Local quality

3Ease of operation

If the cuff width is reduced for better wearing comfort, then the device is more comfortable to wear, but stress concentration at edges causes discomfort and measurement errors

Engineering Contradiction:

Improvewearing comfortVSAvoidstress concentration and discomfort

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The back plate's non-uniform thickness creates a pressing force distribution that counteracts stress concentration. By making the central portion thicker and edge portions thinner, the design ensures that the pressing force is higher where needed (central area) and lower where stress concentration occurs (edge areas). This eliminates discomfort from excessive pressure at the edges while maintaining adequate pressure for accurate measurement, thereby improving wearing comfort.

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

This design ensures accurate blood pressure measurement by maintaining uniform pressure across the measurement site, reducing errors and enhancing comfort by minimizing stress concentration.

Implementation Method 1

a blood-pressure calculating part calculating a blood pressure based on a pressure of a fluid stored in the sensing cuff

Methodology Applied

Scientific EffectPressure detection:

Implementation Method 2

a predetermined amount of air for pressurization is supplied from a pump mounted on the main body to the blood-pressure measurement cuff

Methodology Applied

Scientific EffectFluid pressurization: Pressurisation

Implementation Method 3

air is also supplied to the pressing cuff to compress the artery of the wrist (radial artery, ulnar artery)

Methodology Applied

Scientific EffectMechanical compression: Compression

Data Source

PatentUS11832922B2Sphygmomanometer, and method and device for measuring blood pressure

Publication Date: 2023.12.05 OMRON CORP

AI summary

A sphygmomanometer includes: a bag-shaped sensing cuff to be worn to wrap a measurement site; a back plate disposed on the sensing cuff along a surface opposite to the measurement site; a pressing member for pressing the back plate toward the measurement site; and a blood-pressure calculating part calculating a blood pressure based on a pressure of a fluid stored in the sensing cuff. Regarding a longitudinal direction perpendicular to a circumferential direction of the measurement site to be wrapped by the sensing cuff, a surface facing the measurement site in edge potions on both sides in a width direction along the longitudinal direction of the back plate is curved in a direction away from the measurement site toward tips.