Pressure Sensor Bridge Circuit Using Dual Temperature Coefficients
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Solution Overview
Problem
Pressure sensors with resistors outside the bridge circuit face reduced detection sensitivity due to voltage drop, leading to increased electric current consumption when exposed to temperature changes.
Innovation Solution
A pressure sensor design with resistors arranged in specific strain regions on the membrane, combining resistors with positive and negative temperature coefficients in series to minimize resistance changes due to temperature, maintaining high detection sensitivity while reducing current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resistor is connected outside the bridge circuit to compensate for temperature dependency, then temperature compensation is improved, but the voltage applied to the bridge circuit decreases due to voltage drop across the external resistor, lowering detection sensitivity
Solution Approach 1:
The patent merges the temperature compensation function directly into the bridge circuit by incorporating resistors with complementary temperature coefficients (positive and negative) as integral parts of the bridge structure. This eliminates the need for external compensation resistors, preventing voltage drops while achieving temperature compensation. The merging of compensation elements into the measurement circuit itself resolves the contradiction between temperature stability and detection sensitivity.
Solution Approach 2:
The patent utilizes parameter changes in resistance values with temperature by selecting materials with opposite temperature coefficients (one increasing resistance with temperature, the other decreasing). By carefully choosing these parameters, the bridge circuit maintains balance across temperature variations without requiring external components, thus preserving detection sensitivity while achieving temperature compensation.
2Measurement precision
If the power source voltage is increased to improve detection sensitivity, then detection sensitivity is improved, but electric current consumption increases
Solution Approach 1:
The patent changes the temperature dependency parameters of the resistors by using materials with opposite temperature coefficients. This allows the bridge circuit to maintain stable operation across temperature ranges without requiring increased power voltage, thus preserving detection sensitivity while avoiding increased current consumption. The parameter optimization at the component level eliminates the need for higher power input.
3Device complexity
If resistors with temperature dependency are used in the bridge circuit, then the circuit is simpler, but resistance values change with temperature, reducing measurement accuracy
Solution Approach 1:
The patent changes the temperature coefficients of the resistors by selecting materials with opposite temperature dependencies (one positive, one negative). When these resistors are arranged in the bridge circuit, their temperature-induced resistance changes counterbalance each other, maintaining bridge balance and measurement accuracy across temperature variations. This approach preserves circuit simplicity while achieving temperature compensation through intelligent material selection and circuit configuration.
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
The sensor maintains high detection sensitivity and prevents increased electric current consumption by canceling out temperature-induced resistance changes, allowing accurate pressure detection across varying temperatures.
Implementation Method 1
at least one of the first resistor to the fourth resistor include: a first portion as a resistance having a positive temperature resistance coefficient; and a second portion as a resistance connected to the first portion in series and having a negative temperature resistance coefficient
Implementation Method 2
a pressure sensor that detects strain due to a deformation of a membrane by resistance change
Implementation Method 3
a membrane generating a deformation in response to pressure
Data Source
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AI summary
[Problem] To provide a pressure sensor that can: accurately detect pressure even in an environment in which temperature fluctuates; and prevent increase in power consumption. [Solution] A pressure sensor that has: a membrane that deforms according to pressure; and a detection circuit that includes a first resistor and a third resistor that are disposed in a first distortion area that generates distortion characteristics in a prescribed direction on the membrane and a second resistor and a fourth resistor that are disposed in a second distortion area that generates distortion in the opposite direction to the first distortion area, said detection circuit forming a bridge circuit using the first to fourth resistors. At least one among the first resistor, the second resistor, the third resistor, and the fourth resistor has: a first section that has a resistance having a positive temperature resistance coefficient; and a second section that is connected in series to the first section and has a resistance having a negative temperature resistance coefficient.