Respiratory Motion IC Rectification for Impedance Delay Errors
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Solution Overview
Problem
Impedance pneumography measurements for respiratory motion testing are prone to errors due to delays in signal propagation, leading to incorrect rectification and inaccurate impedance measurements.
Innovation Solution
A semiconductor integrated circuit with a pulse signal generator, rectifier circuit, control signal generator, and AD converter, which generates and phases pulse signals to account for signal delays, ensuring proper rectification and accurate impedance measurement by inverting potential difference signals at the appropriate timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a positive pulse signal is used for impedance measurement, then the circuit area is reduced and single-supply operation is achieved, but measurement errors occur due to signal propagation delay causing incorrect rectification
Solution Approach 1:
The control signal generator circuit generates control signals with predetermined timing that accounts for the signal propagation delay. By anticipating the delay between pulse signal output and potential difference detection, the rectifier circuit is controlled to perform rectification at the correct moment, ensuring accurate impedance measurement while maintaining the compact pulse signal architecture
Solution Approach 2:
The system uses the detected potential difference signal to generate control signals for the rectifier circuit. The control signal generator circuit adjusts the timing of rectification based on the actual signal propagation characteristics, creating a feedback mechanism that ensures accurate rectification timing despite the inherent delay in signal transmission through the body
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 solution effectively mitigates measurement errors by ensuring correct rectification and accurate impedance measurement, allowing for precise testing of respiratory movements.
Implementation Method 1
a pulse signal generator circuit configured to generate a first pulse signal, which is supplied to a first electrode out of the first electrode and a second electrode placed on a chest of a subject, and a second pulse signal, which is supplied to the second electrode, a phase of the second pulse signal differing by 180° to a phase of the first pulse signal
Implementation Method 2
a rectifier circuit configured to receive a potential difference signal and output a rectified signal produced by rectifying the potential difference signal
Implementation Method 3
a control signal generator circuit configured to supply a first control signal, the first control signal causing the rectifier circuit to invert the potential difference signal, which becomes a negative voltage value from the first timing, to a positive voltage value from the first timing
Implementation Method 4
an AD converter circuit configured to output a digital value based on a magnitude of the rectified signal
Data Source
AI summary
A pulse signal generator circuit generates first and second pulse signals for electrodes placed on the chest of a subject with phases that differ by 180°. A rectifier circuit receives a potential difference signal, which reflects an impedance between the electrodes that changes according to respiratory motion and in which timing of changes caused by changes in the first pulse signal or the second pulse signal is delayed from the timing of the changes in the first pulse signal and the second pulse signal, and outputs a rectified signal produced by rectifying the potential difference signal. A control signal generator circuit causes the rectifier circuit to invert the potential difference signal, which becomes a negative voltage value from the certain timing, to a positive voltage value from the certain timing. An AD converter circuit outputs a digital value based on the magnitude of the rectified signal.