Flexible PCB Pressure Sensor Temperature Compensation
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Solution Overview
Problem
Pressure sensors used as hidden keys in smartphones can be affected by temperature changes, leading to false activation or failure to respond due to inconsistent resistivity changes in pressure sensitive adhesive resistors.
Innovation Solution
A pressure sensor design featuring a flexible printed circuit board with multiple pressure sensitive adhesive resistors forming Wheatstone bridges, where voltage signals from temperature-affected resistors are used to compensate for temperature-induced errors, ensuring only pressure-generated signals are output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure sensitive adhesive resistors are used to form a Wheatstone bridge for pressure sensing, then pressure detection function is achieved, but temperature effect causes false activation or failure to respond
Solution Approach 1:
The patent applies local quality by creating different thermal environments for different resistor groups. The first Wheatstone bridge resistors (R1-R4) are positioned to experience temperature changes, while the second Wheatstone bridge resistors (R5-R8) are positioned to experience different temperature changes. This local differentiation allows the system to distinguish between pressure-induced resistance changes and temperature-induced resistance changes, thereby eliminating false activation and improving pressure detection reliability in temperature-affected conditions.
2Measurement precision
If multiple pressure sensitive adhesive resistors are added to form Wheatstone bridges for temperature compensation, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges temperature compensation functionality with the existing pressure sensing Wheatstone bridge structure. By integrating a second Wheatstone bridge (R5-R8) that experiences different temperature changes into the same circuit architecture, the system achieves temperature compensation without requiring separate compensation components. This merging approach improves pressure measurement accuracy while minimizing the increase in device complexity through shared circuit infrastructure.
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 design effectively eliminates temperature-related errors, maintaining measurement accuracy and preventing false alarms or delayed responses in high or low temperature environments.
Implementation Method 1
pressure sensitive adhesive resistors are used to form a Wheatstone bridge, so as to convert the pressure received into a voltage difference for output
Implementation Method 2
Resistivity of the pressure sensitive adhesive resistor changes with temperature
Data Source
AI summary
A pressure sensor and an electronic device are disclosed. The pressure sensor includes a flexible printed circuit board (110) and multiple pressure sensitive adhesive resistors. The multiple pressure sensitive adhesive resistors include pressure sensitive adhesive resistors R1, R2, R3, R4, R5, and R6. The flexible printed circuit board (110) includes a first surface (A) and a second surface (B) that are opposite each other. The pressure sensitive adhesive resistors R1, R3, and R5 are disposed on the first surface (A), and the pressure sensitive adhesive resistors R2, R4, and R6 are disposed on the second surface (B). The flexible printed circuit board (110) is provided with a through hole (C) that allows the first surface (A) to communicate with the second surface (B), and the through hole (C) is at least partially covered by the pressure sensitive adhesive resistors R1, R2, R3, and R4.