Sphygmomanometer Back Plate Width for Uniform Pressure
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Solution Overview
Problem
Conventional sphygmomanometers with narrow cuff dimensions cause stress concentration at the edge portions, leading to non-uniform pressing force and measurement errors when measuring blood pressure on the wrist.
Innovation Solution
A sphygmomanometer design featuring a bag-shaped sensing cuff with a back plate having a larger width dimension than the cuff, and a pressing member to ensure uniform pressure distribution across the measurement site, reducing stress concentration and measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the width-direction dimension of the cuff is reduced to about 25 mm for better appearance and wearing comfort, then the cuff becomes narrower and more comfortable to wear, but stress concentration occurs at the edge portions of the intervening member causing non-uniform pressing force and measurement errors
Solution Approach 1:
The patent applies local quality by making the intervening member wider than the cuff in the width direction. Specifically, the intervening member has a width of 37-43 mm while the cuff width is 25-29 mm, creating a localized expansion at the pressing interface. This localized dimensional change ensures uniform pressure distribution at the measurement site without requiring the entire cuff to be wider, thus maintaining wearing comfort while eliminating edge stress concentration and ensuring measurement accuracy.
2Volume of moving object
If the width-direction dimension of the cuff is reduced to about 25 mm, then the cuff becomes more compact and comfortable, but the pressing force to the measurement site becomes non-uniform causing measurement errors
Solution Approach 1:
The patent implements local quality by locally expanding the intervening member's width beyond the cuff width only at the pressing interface. The intervening member width (37-43 mm) exceeds the cuff width (25-29 mm) specifically where contact with the measurement site occurs. This localized dimensional differentiation ensures uniform pressure distribution without increasing the overall cuff volume, thus maintaining compactness and comfort while achieving accurate measurements.
Solution Approach 2:
The patent applies dimensionality change by extending the intervening member in the width direction (perpendicular to the cuff's longitudinal axis) beyond the cuff's width boundaries. This creates a broader pressing surface in the width dimension while maintaining the cuff's compact longitudinal profile. The intervening member protrudes laterally from the cuff edges, providing a wider pressure distribution area without increasing the cuff's overall bulk or compromising its compact form factor.
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 design achieves accurate blood pressure measurement by ensuring uniform pressing force across the wrist, reducing measurement errors and enhancing comfort.
Implementation Method 1
a pressing member for pressing the back plate toward the measurement site... making the pressing force to the measurement site uniform in the width direction
Implementation Method 2
Based on an output of the pressure sensor, a blood pressure measurement value is calculated by an oscillometric method
Data Source
AI summary
A sphygmomanometer of the present invention 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 dimension of the back plate in a width direction along the longitudinal direction is larger than a dimension of the sensing cuff in the width direction.