Capacitive Sensor Interference Detection via Sideband Demodulation
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Solution Overview
Problem
Capacitive image sensors in proximity sensor devices are susceptible to various types of interference, which affects their accuracy and reliability in detecting input objects.
Innovation Solution
A processing system comprising a sensor module and a demodulation module that transmits a first transmitter signal, receives a resulting signal, and demodulates it to produce upper and lower sideband signals, allowing for the determination of positional information of an input object by selectively measuring changes in capacitive coupling between transmitter and receiver electrodes, while also accounting for interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitive image sensors are used to detect input objects, then measurement precision is improved, but susceptibility to interference increases
Solution Approach 1:
The sensor system segments the detected signal into upper sideband and lower sideband components through demodulation. By separating the signal into distinct frequency components, the system can selectively process each sideband to extract accurate capacitive coupling measurements while filtering out interference that affects only one sideband.
Solution Approach 2:
The patent introduces an intermediary processing stage (demodulation module) that acts as a mediator between the raw sensor signal and the final measurement. This intermediary process transforms the affected signal into separable sideband components, allowing the system to extract useful information while eliminating interference through selective sideband processing.
2Object-affected harmful factors
If signal demodulation is performed to produce sideband signals, then interference filtering is improved, but device complexity increases
Solution Approach 1:
The demodulation module serves multiple functions simultaneously: it separates the signal into upper and lower sidebands for interference filtering, enables selective sideband processing for improved measurement accuracy, and provides the basis for determining capacitive coupling changes. This multi-functionality justifies the added complexity by delivering multiple benefits from a single processing stage.
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 approach enhances the accuracy and reliability of capacitive sensor devices by effectively filtering out interference and determining positional information with improved precision.
Implementation Method 1
determine a first measurement of a change in capacitive coupling between the transmitter electrode and the receiver electrode
Implementation Method 2
demodulating the resulting signal to produce an upper sideband signal and a lower sideband signal
Data Source
AI summary
An input device processing system comprises a sensor module that transmits a first transmitter signal with a transmitter electrode and receives a resulting signal with a receiver electrode. The first transmitter signal comprises a first transmitter frequency, and the resulting signal comprises effects corresponding to the first transmitter signal. A demodulation module demodulates the resulting signal to produce a first signal (e.g., an upper sideband signal) and a second signal (a lower sideband signal), selectably determines a first measurement of a change in capacitive coupling between the transmitter electrode and the receiver electrode based on at least one of the first and second signals, and determines positional information for an input object based on the first measurement.