Self-Calibrating Temperature Sensor for Mobile Devices
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Solution Overview
Problem
Portable electronic devices, such as mobile phones and tablets, face challenges in accurately measuring ambient temperature due to self-heating components like processors and displays, which can skew temperature sensor readings, and internal temperature sensors may be affected by manufacturing or aging issues.
Innovation Solution
Incorporating additional temperature sensors inside the device for thermal coupling with heat-generating components and a compensator to adjust ambient temperature readings based on heat impact, along with a calibration module to account for steady-state heat distribution and offset corrections, using a thermal model to determine accurate compensated ambient temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the temperature sensor is exposed to ambient through openings in housing to provide sufficient coupling to environment, then the temperature sensor can sense ambient temperature, but heat from internal components migrates to the temperature sensor causing inaccurate readings
Solution Approach 1:
The device is segmented into multiple temperature sensing zones: an ambient temperature sensor positioned away from heat-generating components and internal temperature sensors placed near specific heat sources. This segmentation allows independent measurement of ambient temperature and internal heat effects, enabling compensation calculations to correct for self-heating interference.
Solution Approach 2:
A compensation algorithm acts as an intermediary between the temperature sensors and the final temperature reading. The algorithm processes signals from multiple sensors, calculates the heat contribution from internal components based on their operational states, and compensates the ambient temperature reading to eliminate self-heating effects.
2Measurement precision
If additional temperature sensors are placed inside the device for thermal coupling with heat-generating components, then the self-heating effect can be measured and compensated, but the device complexity increases
Solution Approach 1:
Existing internal components such as the processor and battery serve dual functions: their primary functions (computing and power storage) and as heat sources for temperature sensing. By monitoring the operational states of these multi-functional components, the system derives thermal information without requiring dedicated temperature sensors near each heat-generating element.
Solution Approach 2:
The system uses its own operational data (processor load, battery charge/discharge rates) to self-determine the heat generation levels. This self-service approach allows the device to calculate compensation values based on its own operational state without external calibration or additional sensing infrastructure.
3Manufacturing precision
If calibration measurements are conducted during active state of components to account for heat distribution, then accurate calibration parameters can be obtained, but energy consumption increases
Solution Approach 1:
Calibration measurements are performed periodically at predetermined intervals rather than continuously. The system conducts calibration during normal operation cycles, utilizing existing operational states to gather calibration data, thereby achieving accurate calibration parameters while minimizing additional energy consumption associated with dedicated calibration modes.
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 provides a more accurate representation of ambient temperature by accounting for self-heating effects and sensor offsets, ensuring reliable temperature measurements for improved device operation and user experience.
Implementation Method 1
temperature sensor for sensing a temperature ambient the portable electronic device which temperature sensor typically provides a sufficient coupling to the environment
Implementation Method 2
the ambient temperature sensed by the temperature sensor may be impacted in view of heat migrating from such components to the temperature sensor
Data Source
Figure 1a~1c
Figure 2
AI summary
In a portable electronic device, a temperature sensor (1) is provided for sensing an ambient temperature (TR) of the portable electronic device. At least one other temperature sensor (3) is provided for sensing a temperature (TI) inside the portable electronic device. The portable electronic device further comprises a set of components (2) radiating heat in an active state in response to the consumption of electrical energy. A calibration module (5) is adapted to conduct a calibration measurement during or in response to an active state of at least a first component out of the set, and is adapted to determine a set of calibration parameters (c1) in response to the calibration measurement for adjusting the at least one sensed inside temperature (T1). A compensator (4) is provided for determining a compensated ambient temperature (TA) dependent on at least the sensed ambient temperature (TS) and the at least one adjusted sensed inside temperature (cl, T1).