Differential Readout for Capacitive Sensor Noise Reduction
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Solution Overview
Problem
Proximity sensor devices and fingerprint sensors are susceptible to noise, leading to degraded signal quality and increased false acceptance and rejection rates due to pattern-dependent references, which introduce image distortion and cannot be improved by conventional noise rejection methods.
Innovation Solution
The implementation of a system with a plurality of sensor electrodes, including receiver and transmitter electrodes, and a reference receiver electrode, where a processing system drives transmitter signals, receives resulting signals, and determines modified signals based on both receiver and reference signals to reduce noise and image distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional noise rejection methods are used, then processing speed is maintained, but signal quality is significantly degraded due to noise and image distortion
Solution Approach 1:
A reference receiver electrode is introduced as an intermediary element to capture reference signals that represent the noise and distortion affecting the sensor array. This reference signal serves as a mediator that allows the system to identify and compensate for harmful factors without degrading the quality of the primary sensing signals.
Solution Approach 2:
The system determines modified sensing signals by comparing the received signals with the reference signal, effectively changing the parameters of the signal processing to reject noise and distortion. This parameter change approach allows the system to maintain high signal quality by dynamically adjusting how signals are processed based on the reference measurement.
2Reliability
If a reference receiver electrode is added to the sensor array, then signal quality is improved by reducing false acceptance and rejection rates, but device complexity increases
Solution Approach 1:
The sensor array is segmented into functional groups: transmitter electrodes, receiver electrodes, and a reference receiver electrode. This segmentation allows the reference receiver to be treated as a separate, dedicated component for noise reference, simplifying the overall system architecture while improving reliability through specialized functionality.
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 enhances signal quality by reducing false acceptance and rejection rates and is applicable to both fingerprint sensors and capacitive touchpad sensors, effectively addressing noise-related issues and image distortion.
Implementation Method 1
an input device for capacitive touch sensing includes: a plurality of sensor electrodes
Implementation Method 2
determine a modified resulting signal based on the resulting signal received via the receiver electrode and the reference signal received via the reference receiver electrode
Data Source
AI summary
An input device for capacitive touch sensing includes: a plurality of sensor electrodes, the plurality of sensor electrodes comprising: a plurality of receiver electrodes, a plurality of transmitter electrodes, and a reference receiver electrode; and a processing system. The processing system is configured to: drive a first transmitter electrode of the plurality of transmitter electrodes with a transmitter signal, receive a resulting signal via a receiver electrode of the plurality of receiver electrode, the resulting signal comprising effects corresponding to the transmitter signal, receive a reference signal via the reference receiver electrode, and determine a modified resulting signal based on the resulting signal received via the receiver electrode and the reference signal received via the reference receiver electrode.