Thermal Sensor Current Limit Circuit for Skin Temperature Control
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Solution Overview
Problem
Handheld mobile devices generate excessive heat during charging, posing a risk to user safety and challenging manufacturers to maintain skin temperature within thermal specifications without compromising performance.
Innovation Solution
A thermal sensor is integrated into the case of a mobile device, coupled with a battery charger that includes a current limit circuit, which reduces the charging current when the skin temperature exceeds a threshold, thereby controlling the skin temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high current charging is applied to maximize charging speed, then charging performance is improved, but skin temperature increases beyond safe limits
Solution Approach 1:
The patent implements a feedback control system where a thermal sensor continuously monitors the skin temperature of the device case. When the temperature exceeds a predetermined threshold, the system automatically reduces the charging current through the current limit circuit. This closed-loop feedback mechanism dynamically adjusts charging parameters based on real-time temperature measurements, enabling fast charging when safe and current reduction when temperature becomes unsafe, thus resolving the contradiction between charging speed and temperature control.
Solution Approach 2:
The system dynamically changes the charging current parameter based on temperature conditions. At normal temperatures, high current is permitted for fast charging. When skin temperature exceeds the threshold, the current parameter is reduced to a lower level. This parameter adaptation allows the system to optimize charging speed while maintaining skin temperature within safe limits, directly addressing the technical contradiction.
2Temperature
If charging current is reduced to maintain skin temperature within specifications, then thermal safety is improved, but charging performance deteriorates
Solution Approach 1:
The patent employs dynamic current adjustment rather than a fixed low current setting. The current limit circuit continuously adapts the charging current based on real-time temperature feedback. When temperature is within specifications, the system permits high current for optimal charging speed. When temperature approaches or exceeds thresholds, the current is dynamically reduced. This dynamic approach ensures thermal safety while maximizing charging performance under safe operating conditions, resolving the contradiction between temperature control and charging speed.
Solution Approach 2:
The feedback mechanism enables the system to maintain skin temperature within specifications while preserving charging performance when conditions permit. The thermal sensor continuously monitors temperature and feeds this information to the current limit circuit, which adjusts current accordingly. This ensures safety is never compromised while allowing maximum charging speed whenever temperature conditions are favorable, thus resolving the contradiction.
3Temperature
If thermal sensor and current limit circuit are added to control skin temperature, then thermal safety is improved, but device complexity increases
Solution Approach 1:
The current limit circuit is designed to serve multiple functions: it provides over-current protection, implements thermal-based current adjustment, and enables fast charging control. By making this existing component multi-functional, the patent avoids adding a separate dedicated temperature control circuit, thereby minimizing the increase in device complexity while still achieving improved thermal safety through the sensor-circuit integration.
Solution Approach 2:
The patent merges the temperature control function with the existing current limit circuit. Rather than adding a completely separate temperature control system, the thermal sensor is integrated with the current limit circuit to jointly manage both current limiting and temperature control functions. This merging approach reduces overall system complexity compared to having separate independent circuits for each function, while still achieving the goal of improved skin temperature safety.
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
Effectively maintains the skin temperature within safe limits, preventing discomfort or injury while ensuring efficient charging performance by dynamically adjusting the charging current based on temperature readings.
Implementation Method 1
a thermal sensor configured on a case of a handheld electronic device
Implementation Method 2
Power through the devices generates heat, and charging the devices at high current further increases this heat
Data Source
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AI summary
The present disclosure includes circuits and methods for controlling skin temperature of an electronic device (100). In one embodiment, a thermal sensor (150) is configured on a case of a handheld electronic device. The thermal sensor is coupled to a battery charger (110) having a current limit circuit. If the sensed temperature of the case increases above a threshold, a current limit is reduced to reduce current in the battery charger.