Thermistor Switch Circuit for Continuous Temperature Detection
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Solution Overview
Problem
Existing temperature detecting circuits using thermistors suffer from discontinuous measurement accuracy and errors due to variations in supply voltage, especially when resistors are switched to adjust for temperature ranges.
Innovation Solution
A temperature detecting apparatus with a thermistor, a series-connected resistor, and a switch circuit comprising four switches, allowing the thermistor to be connected to either the power or ground side, and the resistor to the other side, enabling accurate temperature detection across a wide range without highly regulated power supplies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resistors are switched to adjust for temperature ranges, then temperature detection accuracy in specific ranges is improved, but measurement accuracy becomes discontinuous across the measurement temperature range
Solution Approach 1:
The patent applies dynamics by making the connection configuration dynamic rather than static. The thermistor can be dynamically connected to either the power supply side or ground side depending on the temperature range, allowing the circuit to adapt its configuration continuously across the measurement temperature range. This dynamic switching resolves the discontinuity problem by ensuring that accuracy optimization is maintained without creating abrupt transitions in measurement characteristics.
Solution Approach 2:
The patent changes the connection parameter (which side the thermistor connects to) based on temperature conditions. By switching the connection configuration between power supply side and ground side according to the measured temperature range, the system optimizes measurement accuracy for different temperature conditions while maintaining continuous accuracy across the entire measurement range.
2Device complexity
If the thermistor is connected to the ground side with fixed resistors, then circuit simplicity is maintained, but errors caused by variation in supply voltage cannot be reduced
Solution Approach 1:
The patent introduces dynamic switching capability that allows the thermistor connection to change between power supply side and ground side. This dynamic configuration enables the circuit to compensate for supply voltage variations by optimizing the voltage division ratio according to temperature conditions, thereby improving measurement accuracy without significantly increasing circuit complexity.
Solution Approach 2:
The patent changes the connection parameter (power side or ground side) based on temperature and voltage conditions. This parameter change allows the circuit to adapt to supply voltage variations and optimize measurement accuracy for different operating conditions, resolving the trade-off between circuit simplicity and measurement precision.
3Measurement precision
If highly regulated power supplies are used, then temperature detection accuracy is improved, but power supply complexity and cost increase
Solution Approach 1:
The patent applies dynamics by enabling the thermistor connection to switch between power supply side and ground side based on temperature conditions. This dynamic configuration allows the circuit to compensate for unregulated or loosely regulated power supply variations, achieving high measurement accuracy without requiring complex and expensive highly regulated power supplies.
Solution Approach 2:
The patent changes the connection configuration parameter according to temperature and voltage conditions, allowing the system to adapt to power supply variations. This parameter change enables accurate temperature detection even with simpler power supply regulation, reducing both complexity and cost while maintaining measurement precision.
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 configuration ensures continuous measurement accuracy and reduces errors caused by supply voltage variations, achieving precise temperature detection from -40°C to +120°C with minimal margin of error.
Implementation Method 1
a thermistor; a resistor connected in series to the thermistor; a temperature detector connected to a first node between the thermistor and the resistor
Data Source
AI summary
A temperature detecting apparatus includes a thermistor; a resistor connected in series to the thermistor; a temperature detector connected to a first node between the thermistor and the resistor; and a switch circuit including a first switch, a second switch, a third switch, and a fourth switch. The first switch and the third switch are connected in series, the second switch and the fourth switch are connected in series, the first switch and the second switch are connected to a power side, the third switch and the fourth switch are connected to a ground side, the thermistor is connected to a second node between the first switch and the third switch, and the resistor is connected to a third node between the second switch and the fourth switch.