Optical Flow Sensor Temperature Compensation
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Solution Overview
Problem
Existing optical flow measuring devices for medical infusion devices are susceptible to errors due to temperature-induced changes in sensor performance, requiring additional components and complexity for temperature compensation.
Innovation Solution
A flow measuring device with a digital signal processor that modifies and calculates output signals from optical sensors using predetermined temperature compensation factors, eliminating the need for temperature measurement, and compensates for temperature-induced changes by calculating a threshold voltage and applying a correction factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature compensation circuitry and additional transducers are added to compensate for temperature-dependent changes in optical sensors, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the temperature compensation function from hardware components (temperature transducers and compensation circuitry) and implements it through software algorithms in the microprocessor. The microprocessor executes temperature compensation routines that calculate corrected flow rates based on temperature-dependent characteristics of the optical sensors, eliminating the need for additional physical components while maintaining measurement accuracy.
Solution Approach 2:
The patent replaces the mechanical/physical system of temperature transducers and analog compensation circuitry with a digital software-based compensation system. The microprocessor uses algorithms to model and compensate for temperature effects on optical sensor output, substituting physical compensation hardware with computational methods that achieve the same measurement precision without increasing device complexity.
2Reliability
If temperature measurement and compensation components are added, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent makes the microprocessor perform multiple functions: it not only controls the optical sensors and measures flow rate but also executes temperature compensation algorithms. By integrating the temperature compensation function into the existing microprocessor software, the system achieves improved measurement reliability without adding dedicated temperature measurement and compensation hardware, thereby reducing manufacturing costs.
Solution Approach 2:
The system uses the existing microprocessor and its computational resources to self-compensate for temperature effects on optical sensor measurements. Rather than requiring separate dedicated components for temperature compensation, the microprocessor itself performs the compensation calculations using software routines that model temperature-dependent sensor behavior, making the system self-sufficient and reducing overall component count and manufacturing cost.
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 reduces errors caused by temperature changes without measuring the actual temperature, simplifying the device and maintaining accuracy in flow rate measurements for medical infusion devices.
Implementation Method 1
an optical measurement sensor that detects when a liquid in a vertical tube moves between two levels
Data Source
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AI summary
A flow measuring device, comprising a container for receiving a flow of liquid, a plurality of optical sensors associated with the container, each of the plurality of optical sensors producing an output signal dependent upon the presence of liquid reaching a level in the container associated with each optical sensor, means for modifying the output signal in accordance with at least one predetermined temperature compensation factor, and means for calculating a flow rate from the time at which the liquid traverses between two levels in the container.