Capacitance Detection Phase Adjustment Circuit
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Solution Overview
Problem
Existing impedance detection circuits face a decrease in detection sensitivity due to phase delay issues caused by parasitic capacitance and high resistance in interconnection wires, which are not effectively corrected by phase compensation techniques.
Innovation Solution
A capacitance detection device with a phase adjustment circuit that advances the phase of the AC signal applied to the shield electrode, ensuring the detection signal and AC signal are in phase, thereby reducing phase delay and enhancing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase compensation is performed using existing impedance detection circuits, then the phase delay caused by parasitic capacitance is compensated, but the phase delay caused by high resistance in interconnection wires is not corrected, resulting in decreased detection sensitivity
Solution Approach 1:
The patent changes the phase parameter of the AC signal applied to the shield electrode by introducing a phase adjustment circuit. This circuit advances or delays the phase of the AC signal to compensate for phase delays caused by both parasitic capacitance and interconnection wire resistance, thereby improving detection sensitivity without significantly increasing device complexity
Solution Approach 2:
The patent introduces a phase adjustment circuit as an intermediary component between the AC signal source and the shield electrode. This intermediary circuit specifically addresses the phase delay issue caused by high resistance in interconnection wires, which was not corrected by existing phase compensation techniques
2Measurement precision
If the resistance of the interconnection wire is high or parasitic capacitance is large, then the phase delay of the input current is not substantially corrected by existing compensation techniques, but adding complex correction circuits increases device complexity
Solution Approach 1:
The patent adjusts the phase parameter of the AC signal to compensate for delays caused by high resistance and parasitic capacitance. By changing the phase of the applied signal rather than attempting to correct the delayed signal, the system achieves accurate phase alignment without requiring complex correction circuits
Solution Approach 2:
The phase adjustment circuit performs preliminary phase adjustment on the AC signal before it is applied to the shield electrode. This preliminary action prevents phase delay from occurring in the first place, rather than attempting to correct it after the fact, thereby maintaining simple circuit structure while achieving high phase correction accuracy
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 phase adjustment circuit effectively reduces detection sensitivity loss and improves dynamic range by aligning the phases of the detection signal and AC signal, maximizing the output signal level and detection accuracy.
Implementation Method 1
a phase adjustment circuit provided between the AC signal source and the shield electrode. The phase adjustment circuit advances the phase of the AC signal output from the AC signal source.
Data Source
AI summary
A capacitance detection device includes at least one detection electrode, a shield electrode disposed in close vicinity of the detection electrode, an AC signal source that supplies an AC signal to the shield electrode, a detection circuit that detects capacitance between a physical object in close vicinity of the detection electrode and the detection electrode on the basis of a detection signal output from the detection electrode and the AC signal output from the AC signal source, and a phase adjustment circuit provided between the AC signal source and the shield electrode. The phase adjustment circuit advances the phase of the AC signal output from the AC signal source.