Physiological Signal Interface Using Voltage-to-Current Conversion

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Solution Overview

Problem

Existing bedside monitors face challenges in downsizing and cost reduction due to noise interference between digital and analog signal communication paths, which increases the size and cost when attempting to separate these paths.

Innovation Solution

The integration of analog-to-digital conversion followed by voltage-to-current conversion allows for the simultaneous processing of analog signals from multiple sensors through a single interface, reducing noise interference and minimizing the number of terminals required, thereby enabling a more compact and cost-effective design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If digital signal connector and analog signal connector are integrated into a single connector, then the size and cost of the bedside monitor are reduced, but noise from digital signal communication mixes into analog signal communication path

Engineering Contradiction:

Improvesize of bedside monitorVSAvoidnoise mixture in signal communication

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent divides the signal transmission paths by converting digital signals to current signals, which are then transmitted through separate terminals within the integrated connector. This segmentation allows multiple signal types to coexist in a single connector without mutual interference, resolving the noise mixture problem while maintaining connector integration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the signal parameter from voltage-based digital signaling to current-based signaling for the digital-to-analog path. This parameter change allows the digital signal to be transmitted without causing voltage noise in the analog path, enabling integration without noise interference.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If shield is provided inside connector and/or digital signal path and analog signal path are separated, then noise mixture into analog signal path is avoided, but size and cost of connector increase

Engineering Contradiction:

Improvenoise mixture in signal communicationVSAvoidsize of connector

Core Design Contradiction:

Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

The patent replaces the mechanical/physical shielding approach with an electrical signal conversion approach. Instead of using shields or physical separation to prevent noise, the system converts digital voltage signals to current signals, which inherently prevent voltage noise coupling into the analog path, achieving noise protection without increasing connector size.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If multiple separate connectors are used for different sensors, then signal communication reliability is maintained, but device complexity and cost increase

Engineering Contradiction:

Improvesignal communication reliabilityVSAvoidnumber of connectors and terminals

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent creates a universal integrated connector that can handle multiple signal types (analog voltage signals from SpO2 sensors and current signals from other sensors) through a single interface. This multi-functional connector reduces the number of separate connectors needed while maintaining reliable signal transmission for all sensor types.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 approach effectively suppresses the increase in size and cost of the bedside monitor while preventing noise mixture in signal communication, enhancing design flexibility and signal processing ease.

Implementation Method 1

an analog-to-digital converter configured to convert a first analog voltage signal into a first digital voltage signal

Methodology Applied

Scientific EffectAnalog-to-digital conversion:

Implementation Method 2

a first voltage-to-current converter configured converts the first digital voltage signal into a first analog current signal

Methodology Applied

Scientific EffectVoltage-to-current conversion:

Data Source

PatentUS10159442B2Physiological information processing system

Publication Date: 2018.12.25 NIHON KOHDEN CORP

AI summary

First and second sensors attached to a living body are connected to first and second input connectors respectively. An analog-to-digital converter converts a first analog voltage signal input from the first sensor through the first input connector into a first digital voltage signal. A first voltage-to-current converter converts the first digital voltage signal into a first analog current signal. A first interface connector outputs a second analog voltage signal and the first analog current signal, the second analog voltage signal being input from the second sensor through the second input connector. A physiological information processing apparatus has a second interface connector through which the first analog current signal and the second analog voltage signal are input to the physiological information processing apparatus.