Capacitive Sensing Interference Cancellation Using Transmitter Electrodes
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Solution Overview
Problem
Existing input devices face challenges in accurately detecting and removing interference, which affects the accuracy of capacitive measurements and reduces frame time dedicated to capacitive sensing for input objects, as system resources are often divided between interference detection and proximity sensing.
Innovation Solution
The input device employs a method where transmitter electrodes are used to measure interference, with filtering circuitry adjusting resulting signals to remove interference, allowing for improved interference detection and cancellation without requiring additional receiver electrodes, thereby optimizing resource utilization and enhancing sensing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If system resources are divided between interference detection and proximity sensing, then interference detection can be performed, but frame time dedicated to capacitive sensing is reduced
Solution Approach 1:
The patent combines interference detection and proximity sensing functions into a unified capacitive sensing system. The same transmitter electrodes and receiver electrodes are used for both interference measurement and proximity sensing, eliminating the need to divide system resources between separate interference detection and sensing operations. This merging allows simultaneous or integrated execution of both functions within the same frame time, resolving the time loss contradiction.
Solution Approach 2:
The transmitter electrodes and receiver electrodes serve multiple functions: they are used both for measuring interference (by monitoring signal characteristics when no input object is present) and for proximity sensing (by detecting changes in capacitance when input objects are present). This multi-functionality allows the system to perform both interference detection and proximity sensing using the same hardware resources, thereby preventing frame time reduction.
2Measurement precision
If additional receiver electrodes are used for interference detection, then interference detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent makes the existing receiver electrodes universal by enabling them to serve dual purposes: proximity sensing and interference detection. Instead of adding dedicated receiver electrodes for interference detection, the system uses the same receiver electrodes that are already present for proximity sensing. This approach improves interference detection accuracy without increasing device complexity, as no additional electrodes are required.
Solution Approach 2:
The existing receiver electrodes perform interference detection as part of their normal operation. The system self-services by using the same hardware components for both interference measurement and proximity sensing, eliminating the need for additional dedicated interference detection electrodes. This self-service approach maintains measurement precision while avoiding increased device complexity.
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 enables more efficient interference detection and removal, increasing the accuracy of positional information determination for input objects and optimizing frame time for capacitive sensing, leading to improved usability and performance in electronic systems.
Implementation Method 1
transmitting a first sensing signal along a first transmitter electrode among various transmitter electrodes of the input device
Data Source
AI summary
A method of capacitive sensing may include transmitting a first sensing signal along a first transmitter electrode among various transmitter electrodes of an input device. The method may further include obtaining, using various receiver electrodes in the input device, a first resulting signal in response to the first sensing signal being transmitted along the first transmitter electrode. The method may further include obtaining a second resulting signal from a second transmitter electrode among the transmitter electrodes. The method may further include determining, using the second resulting signal, interference along the second transmitter electrode. The method may further include adjusting, using the interference along the second transmitter electrode, the first resulting signal to produce an adjusted resulting signal. The method may further include determining, using the adjusted resulting signal, positional information regarding a location of an input object in a sensing region of the input device.