Capacitive Sensor Electrode Ganging for Wake-on-Finger Detection
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Solution Overview
Problem
Existing fingerprint sensor devices require additional components and circuitry to detect the presence of a finger for Wake-On Finger (WOF) and navigation, increasing complexity and cost.
Innovation Solution
The implementation of a capacitive sensing input device with ganged transmitter and receiver electrodes, using single-ended or differential circuitry to drive common sensing signals and capture common detected signals, reducing the need for additional components and enhancing signal strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional components and circuitry are added near the sensor to detect object presence for Wake-On Finger, then detection capability is improved, but device complexity increases
Solution Approach 1:
The existing fingerprint sensor electrodes are made multi-functional by configuring them to perform both traditional fingerprint sensing and Wake-On Finger detection. The receiver electrodes are ganged together to detect common signals from multiple electrodes simultaneously, allowing the same hardware to serve dual purposes without requiring separate detection components.
Solution Approach 2:
Multiple receiver electrodes are merged or ganged together into a single detection node. By combining the signals from multiple receiver electrodes through ganging, the system achieves enhanced detection capability for Wake-On Finger while reducing the number of separate circuit paths and components needed.
2Reliability
If additional components and circuitry are added near the sensor to detect object presence for Wake-On Finger, then detection capability is improved, but manufacturing cost increases
Solution Approach 1:
The existing fingerprint sensor electrodes are made multi-functional by configuring them to perform both traditional fingerprint sensing and Wake-On Finger detection. The receiver electrodes are ganged together to detect common signals from multiple electrodes simultaneously, allowing the same hardware to serve dual purposes without requiring separate detection components.
Solution Approach 2:
The fingerprint sensor's existing electrodes and circuitry serve the additional function of Wake-On Finger detection. By making the receiver electrodes ganged to detect common signals, the system uses its own existing components to perform the detection function that would otherwise require separate dedicated hardware.
3Measurement precision
If traditional separate sensing signals are driven onto each transmitter electrode, then sensing precision is maintained, but power consumption increases
Solution Approach 1:
Multiple transmitter electrodes are ganged together and driven by a common sensing signal for Wake-On Finger detection. This merging of transmitter electrodes reduces the number of individual signal driving operations needed, thereby reducing power consumption while still maintaining adequate detection precision through the combined signal response.
Solution Approach 2:
For Wake-On Finger detection, the system uses a simplified sensing approach where a common signal is driven onto ganged transmitter electrodes rather than individual signals on each electrode. This partial action approach provides sufficient detection capability for Wake-On Finger purposes without the full power consumption of individual electrode signaling.
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 significantly reduces power consumption and complexity while achieving orders of magnitude larger signal strength, enabling efficient Wake-On Finger and navigation capabilities without the need for additional components.
Implementation Method 1
an input device for capacitive sensing includes: a plurality of transmitter electrodes and a plurality of receiver electrodes
Data Source
AI summary
An input device for capacitive sensing includes: a plurality of transmitter electrodes and a plurality of receiver electrodes. The input device is configured to: operate in a first mode by driving sensing signals onto each of the transmitter electrodes and receiving separate detected signals corresponding to each of the plurality of receiver electrodes; and operate in a second mode by driving a common sensing signal onto a plurality of the transmitter electrodes and receiving a common detected signal corresponding to at least one receiver electrode selected from the plurality of receiver electrodes.