Piezoelectric Input Device Noise Cancellation Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Piezoelectric sensors face increased impedance and susceptibility to extraneous noise when detecting pressure changes, leading to inaccurate signal detection due to their application on highly insulating substances like ceramic.
Innovation Solution
An input device is designed with a first and second piezoelectric sensor, each with electrodes positioned to generate charges based on pressure changes, and a switch circuit that alternates charge input to a charge detection circuit, effectively reducing noise interference by canceling out noise charges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If piezoelectric sensors are used to detect pressure changes, then pressure detection capability is achieved, but impedance increases and susceptibility to extraneous noise worsens
Solution Approach 1:
The piezoelectric sensor is divided into multiple independent piezoelectric elements (first piezoelectric element, second piezoelectric element, etc.). Each element generates charge independently in response to pressure changes, allowing the sensor to segment the detection function across multiple units rather than relying on a single high-impedance element.
Solution Approach 2:
Multiple piezoelectric elements are connected in parallel to combine their charge output. The charge detection circuit sums the charges from all piezoelectric elements, effectively reducing the overall impedance and noise susceptibility while maintaining pressure detection capability. The combined charge Q = q1 + q2 + ... + qn provides a stronger signal with lower impedance.
2Measurement precision
If piezoelectric sensors apply pressure to highly insulating substances, then pressure to electrical signal conversion is achieved, but impedance increases
Solution Approach 1:
Multiple piezoelectric elements are connected in parallel to combine their charge output. The charge detection circuit sums the charges from all piezoelectric elements, effectively reducing the overall impedance and noise susceptibility while maintaining pressure detection capability. The combined charge Q = q1 + q2 + ... + qn provides a stronger signal with lower impedance.
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 device significantly reduces the influence of extraneous noise, enhancing the accuracy of pressure change detection by ensuring that noise charges are effectively canceled out, leading to improved signal fidelity.
Implementation Method 1
Piezoelectric sensors have been widely used as one means for detecting pressures. A piezoelectric sensor applies pressure to a highly insulating substance, such as ceramic, to cause dielectric polarization to thereby converting the pressure into an electrical signal.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An input device that inputs information corresponding to a change in pressure due to load has: a first charge detection circuit 11 that outputs a first detection signal Sp corresponding to charges generated in a first piezoelectric sensor P1 and a second piezoelectric sensor P2; and a switch circuit 20 that is provided on a path through which the charges are transmitted from the first piezoelectric sensor P1 and the second piezoelectric sensor P2 to the first charge detection circuit 11. The first charge detection circuit 11 alternately iterates a first period T1 in which a first charge Q1 is input from a first positive electrode EP1 via the switch circuit 20 and a second period T2 in which a second charge Q2 is input from a second negative electrode EN1 via the switch circuit 20, reverses a sign of one of the first charge Q1 and the second charge Q2, combines a resulting charge with the other charge, and outputs the first detection signal Sp corresponding to the amount of accumulation of the combined charge.