Integrated Heat Spreader and RTD for Skin Temperature Measurement
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Solution Overview
Problem
Handheld electronic devices face challenges in accurately measuring skin temperature due to limited space for active cooling and the inaccuracy of on-chip and on-board temperature sensors, which can lead to uncomfortable user experiences and safety hazards.
Innovation Solution
A combined heat spreader and temperature sensor design that introduces small gaps in the heat spreader to create electrical resistance, allowing for direct skin temperature measurement using a resistance temperature detector (RTD) without increasing device thickness, and is thermally coupled to the back surface of the device to spread heat effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If on-chip and on-board temperature sensors are used to predict skin temperature, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent combines the heat spreader and temperature sensor into a single integrated component. The heat spreader itself is configured with a resistance temperature detector (RTD) that directly measures skin temperature, eliminating the need for separate prediction algorithms and multiple sensors. This merging resolves the contradiction by achieving both low device complexity and high measurement precision through functional integration.
2Temperature
If active cooling devices such as fans are added to manage heat, then temperature control improves, but device complexity and size increase
Solution Approach 1:
The patent implements a self-service thermal management system where the integrated heat spreader with RTD continuously monitors skin temperature and automatically adjusts power distribution to electronic components. The system self-regulates heat generation at the source by dynamically controlling component power based on real-time temperature feedback, eliminating the need for active cooling devices like fans while maintaining effective temperature control.
3Temperature
If passive cooling devices such as heat sinks are strategically placed, then heat management improves, but device complexity increases
Solution Approach 1:
The patent makes the heat spreader multi-functional by integrating it with an RTD sensor. The same component that spreads heat across the skin contact surface also directly measures skin temperature, serving both thermal management and temperature sensing functions simultaneously. This universality resolves the contradiction by improving heat management without increasing device complexity, as one component performs multiple functions.
4Temperature
If spatial arrangement of electronic components is optimized to reduce heat, then skin temperature decreases, but productivity and computational performance are limited
Solution Approach 1:
The patent implements dynamic thermal management where power distribution to electronic components is continuously adjusted based on real-time skin temperature measurements from the integrated RTD. Rather than statically limiting component placement or performance, the system dynamically controls power delivery to maintain skin temperature within safe limits while maximizing computational performance when conditions permit, resolving the contradiction between temperature control and productivity.
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 enables accurate and direct measurement of skin temperature, improving user comfort and safety by maintaining skin temperature within safe limits while maintaining high heat spreading coverage and not compromising the device's thickness.
Implementation Method 1
portable electronic devices may be designed to spatially arrange electronic components so that two or more active and heat-producing components are not positioned proximally to one another. Many portable electronic devices also rely on passive cooling devices, such as heat sinks, to manage thermal energy among the heat-producing electronic components.
Implementation Method 2
the combined heat spreader and skin temperature sensor described herein may have a design that introduces small gaps in the heat spreader element to build an electrical resistance, whereby changes in the resistance can therefore be used to measure the skin temperature (e.g., a resistance temperature detector (RTD))
Data Source
AI summary
The disclosure generally relates to a hybrid design whereby a heat spreader arranged to reduce an external skin temperature on a handheld device may further enable the external skin temperature to be directly measured. For example, the heat spreader may be thermally coupled to at least one external surface and include at least one region in which a plurality of recesses are formed such that an electrical resistance is produced in the at least one region when a current is applied thereto. The heat spreader may be formed from a material having a substantially linear resistance-to-temperature correlation, whereby the electrical resistance produced in the at least one region may be measured and correlated to a temperature on the at least one external surface.