Capacitive Input Device Multi-Finger Detection Circuit
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Solution Overview
Problem
Existing input devices struggle to efficiently detect the approach positions of multiple operating bodies, such as fingers, on a scanning pad due to complex structures and increased load on detecting circuits, which results in slow operation and high costs.
Innovation Solution
An input device with a plurality of scanning electrodes and a detection electrode that uses pulse driving signals with opposite rise and fall times to simplify the detecting circuit, allowing for simultaneous detection of multiple operating bodies by monitoring detection signals from a single detection electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sequentially monitor intersection capacitances at all intersections to detect multiple fingers, then detection accuracy is improved, but detecting circuit load increases and scanning time lengthens
Solution Approach 1:
The input panel is divided into multiple scanning regions with separate scanning electrodes for each region. Each scanning electrode independently scans its assigned region, allowing parallel detection operations that reduce the load on any single detecting circuit while maintaining comprehensive coverage of all intersections.
Solution Approach 2:
The patent introduces a spatial dimension by dividing the detection space into multiple regions with dedicated scanning electrodes. This transforms a single sequential scanning problem into multiple parallel scanning operations across different spatial zones, reducing circuit load and scanning time while preserving detection accuracy.
2Measurement precision
If sequentially scan all intersections to detect approach positions, then detection accuracy is improved, but scanning time increases
Solution Approach 1:
The input panel is divided into multiple scanning regions with separate scanning electrodes for each region. Each scanning electrode independently scans its assigned region, allowing parallel detection operations that reduce the load on any single detecting circuit while maintaining comprehensive coverage of all intersections.
Solution Approach 2:
Multiple scanning electrodes operate simultaneously and continuously across different regions, eliminating idle time between sequential scans. This parallel continuous operation maintains detection accuracy while significantly reducing total scanning time compared to sequential scanning of all intersections.
3Measurement precision
If use surface acoustic wave type or two-dimensional optical sensor array type to detect multiple contact positions, then detection capability is improved, but structure becomes complicated and cost increases
Solution Approach 1:
The patent combines the advantages of segmented scanning electrodes with a unified detection approach. Multiple scanning electrodes work together with a coordinated control system to achieve multi-point detection capability, avoiding the need for complex surface acoustic wave structures or two-dimensional optical sensor arrays while maintaining detection capability.
Solution Approach 2:
The scanning electrodes and detecting circuits are designed to perform multiple functions: they can detect single contact positions, multiple simultaneous contact positions, and track movement across different regions. This multi-functionality eliminates the need for specialized complex structures while achieving superior detection capability.
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 solution enables rapid and efficient detection of multiple operating bodies with a simplified circuit structure, reducing the time required to scan the input panel and lowering costs.
Implementation Method 1
when a finger touches the scanning pad, the coordinates of the contact position of the finger with the scanning pad are detected... detects the approach of a plurality of operating bodies... uses a variation in capacitance
Data Source
AI summary
An input device includes a plurality of X scanning electrodes and a common detection electrode that forms capacitances together with the X scanning electrodes. A first driving signal is sequentially supplied to the X scanning electrodes, and a second driving signal is supplied to the X scanning electrodes other than the X scanning electrodes adjacent to the X scanning electrode supplied with the first driving signal. It is possible to detect two X scanning electrodes simultaneously approached by the fingers by detecting a current generated in the detection electrode when the first driving signal P and the second driving signal N are supplied.