Blood Pressure Cuff Inflation Control Without Pump Restart Noise
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Solution Overview
Problem
Conventional blood pressure measurement devices face noise interference and inaccurate data due to the pump stopping and restarting during pressurization, especially when using high startup voltage pumps, leading to insufficient sampling rates and non-linear inflation.
Innovation Solution
Implement a pressurization control method using a nonlinear increasing inflation rate and a slow exhaust valve with nonlinear depressurization, controlled via pulse width modulation (PWM) with an adjustable duty cycle, allowing the use of high or low startup voltage pumps without pump stoppages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high startup voltage pump is used to shorten pressurization time, then productivity is improved, but noise interference occurs due to pump stoppages and restarts during measurement
Solution Approach 1:
The patent applies dynamics by making the pump's operating state changeable - transitioning from a static on/off control to a dynamic variable speed control. The pump operates at different speeds during different phases: high speed during initial pressurization to reduce time, and low speed during measurement phase to eliminate noise interference. This dynamic adjustment resolves the contradiction between productivity and noise interference.
Solution Approach 2:
The patent changes the operating parameters of the pump - specifically the rotation speed parameter. By adjusting the rotation speed from high to low at different measurement stages, the system achieves both short pressurization time (high speed) and noise-free measurement (low speed). This parameter change strategy directly addresses the technical contradiction.
2Object-affected harmful factors
If a low startup voltage pump is used to avoid noise interference, then noise interference is reduced, but pressurization time increases and measurement precision deteriorates
Solution Approach 1:
The system uses dynamic speed adjustment of the pump to resolve this contradiction. During the pressurization phase, the pump operates at high speed to ensure rapid pressurization and adequate sampling rate for precision. During the measurement phase, it switches to low speed to eliminate noise interference. This dynamic behavior allows the system to avoid noise while maintaining measurement precision.
Solution Approach 2:
The patent implements periodic action by dividing the measurement process into distinct phases with different pump operating modes. The pump alternates between high-speed pressurization mode and low-speed measurement mode. This periodic switching ensures that noise interference is avoided during measurement while pressurization precision is maintained through adequate sampling during the high-speed phase.
3Measurement precision
If linear inflation control is implemented, then measurement precision is improved, but device complexity increases due to feedback control requirements
Solution Approach 1:
The patent implements feedback control by continuously monitoring the pressure sensor data and comparing it with the target pressure curve. The controller adjusts the pump speed based on the deviation from the expected pressure progression, ensuring linear inflation control. This feedback mechanism achieves precise inflation control while the patent simplifies the overall system by using a single integrated controller rather than multiple separate control components.
Data Source
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AI summary
A pressurization control method for blood pressure measurement is applied on a blood pressure measurement device, and includes connecting an airbag unit with a pump, a slow exhaust valve unit and a pressure sensor, wherein the slow exhaust valve unit has a nonlinear depressurization rate; controlling the pump to pressurize the airbag unit with a nonlinear inflation rate until pulses of a pressure signal outputted from the pressure sensor is interpreted to obtain a blood pressure measurement result, wherein the pump inflates the airbag unit with an inflation rate increasing nonlinearly upon a temporal sequence, and the slow exhaust valve unit depressurizes the airbag unit with a nonlinear depressurization rate upon the temporal sequence.