Infant Warmer Heater Control with Dual Temperature Feedback
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Solution Overview
Problem
Existing infant warmers face limitations due to variations in supply voltage, heater characteristics, age, and ambient conditions, leading to inefficient heat regulation and slow response to power changes, which can impact the ability of premature or low-birth-weight infants to maintain body temperature.
Innovation Solution
An improved infant warming assembly with a radiant heater control apparatus that includes a heater surface temperature sensor, a skin temperature sensor, and a control loop with both a temperature component and a power component. The power component is driven by the heater surface temperature sensor and a control signal from the temperature component, allowing for precise control of heater power based on commanded skin temperature values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional infant warmers use only skin temperature feedback for heater control, then the control system is simple, but the heater response is slow and affected by voltage/heater variations
Solution Approach 1:
The patent implements dual feedback loops: an outer feedback loop using skin temperature sensor to determine desired heater temperature, and an inner feedback loop using heater surface temperature sensor to control actual heater power. This nested feedback structure improves control reliability by directly monitoring heater state while maintaining the simplicity of skin temperature-based setpoint determination.
Solution Approach 2:
The heater surface temperature sensor acts as an intermediary measurement device between the heater element and the control system. It provides direct temperature feedback about the heater's actual state, enabling more reliable power control without requiring complex voltage compensation or heater characteristic modeling.
2Speed
If infant warmers rely on commanded skin temperature control without direct heater temperature monitoring, then the system is easier to operate, but the response to power changes is slow
Solution Approach 1:
The control system is segmented into two independent but coupled control loops: an outer temperature control loop that determines the desired heater temperature based on skin temperature feedback, and an inner power control loop that rapidly adjusts heater power based on direct heater temperature measurement. This segmentation enables fast heater response while keeping the overall system easy to operate through automatic nested control.
Solution Approach 2:
The system performs preliminary determination of the desired heater temperature using the outer feedback loop based on skin temperature, before the inner loop executes rapid power adjustments. This preliminary action prepares the control system to respond faster to temperature deviations while maintaining operational simplicity.
3Measurement precision
If the heater control system does not account for supply voltage variations and heater characteristics, then the device is simpler to manufacture, but the temperature control precision deteriorates
Solution Approach 1:
The patent replaces complex mechanical/electrical compensation mechanisms (voltage regulators, heater characterization circuits) with a straightforward temperature sensing and feedback approach. By directly measuring heater surface temperature and using it for power control, the system achieves high temperature control precision without complicated voltage compensation or heater-specific calibration, simplifying manufacturing.
Solution Approach 2:
The system changes the control parameter from electrical (voltage/current) to thermal (temperature). By controlling the heater based on direct temperature measurement rather than electrical input, the system automatically compensates for voltage variations and heater characteristic differences, achieving precise temperature control without complex electrical compensation circuits.
4Measurement precision
If conventional warmers lack heater surface temperature sensing, then the system uses less energy for sensing, but the overall heat regulation accuracy decreases
Solution Approach 1:
The patent merges the temperature sensing function into the existing heater structure by placing a temperature sensor in direct thermal contact with the heater element. This integrated sensing approach provides accurate heater temperature measurement with minimal additional energy consumption, as the sensor uses the heater's own thermal field for measurement without requiring separate heating or complex signal conditioning.
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 provides more accurate and rapid heat regulation, independent of input voltage variations and heater characteristics, ensuring consistent skin temperature maintenance and reducing the need for software recalibration when replacing heaters, thus enhancing the performance and reliability of infant warming systems.
Implementation Method 1
a heater surface temperature sensor disposed on the heater element, the heater surface temperature sensor being structured to sense a current heater surface temperature
Implementation Method 2
a skin temperature sensor and a user interface that can be used to input a commanded skin temperature value. The skin temperature sensor and the commanded skin temperature value are used in controlling a temperature component of a control loop
Implementation Method 3
Infant warmers typically are employed in hospital or other medical settings to warm an infant in order to compensate for heat that is lost by a newborn through convection and radiation. It has thus been known to provide infant warmers that provide heat to an infant predominantly through radiation in the medium wave infrared spectrum
Data Source
AI summary
An infant warming assembly includes a heater assembly having a heater surface temperature sensor, a skin temperature sensor, and a user interface to input a commanded skin temperature value. The skin temperature sensor and the commanded skin temperature value are used in controlling a temperature component of a control loop. The heater surface temperature sensor is used in controlling a power component of the control loop that powers the heater based at least in part upon the heater surface temperature sensor and a control signal from the temperature component.