Capacitive Sensor Interference Compensation via Inverted Voltage Driving
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Solution Overview
Problem
Proximity sensor devices face interference between electrodes used for display updating and input sensing, which reduces the signal-to-noise ratio and affects the accuracy of input sensing.
Innovation Solution
The system employs a processing system that drives source lines with a first voltage and sensor electrodes with an inverted version of this voltage, allowing the system to receive signals and determine positional information while mitigating interference between source lines and sensor electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If display updating and input sensing are performed simultaneously using the same electrodes, then the time available for both operations is increased, but interference is generated between the electrodes which reduces the signal-to-noise ratio and negatively impacts input sensing accuracy
Solution Approach 1:
The electrode array is divided into multiple groups, with each group containing electrodes that are driven with the same voltage polarity. By segmenting the electrodes into distinct groups and controlling their driving voltages independently, the system can perform display updating and input sensing simultaneously while managing interference through group-based voltage control
Solution Approach 2:
The system changes the voltage parameter by driving different electrode groups with different voltage polarities (first voltage polarity for some groups, second voltage polarity for others). This parameter variation allows the system to cancel out interference signals through differential measurement, thereby maintaining input sensing accuracy while enabling simultaneous display updating
2Ease of manufacture
If electrodes used for display updating are positioned near electrodes used for input sensing, then the device structure is simplified and manufacturing is easier, but interference is generated between the electrodes which reduces signal-to-noise ratio
Solution Approach 1:
The system converts the harmful interference effect into a beneficial signal by using differential measurement. The interference signal generated by display updating electrodes is treated as a reference signal that can be subtracted from the sensing signal, thereby recovering the true input signal. This approach allows close positioning of display and sensing electrodes without sacrificing signal quality
Solution Approach 2:
The system introduces an intermediary reference signal that represents the interference generated by display updating electrodes. This reference signal is used to compensate for the interference in the sensing channel, allowing the system to maintain high signal-to-noise ratio even when display and sensing electrodes are positioned close together
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 effectively reduces interference, enabling simultaneous or overlapping display updating and input sensing, thereby improving the accuracy of input sensing in proximity sensor devices.
Implementation Method 1
when electrodes used for display updating are positioned near electrodes used for input sensing, interference may be generated between the electrodes
Data Source
AI summary
Embodiments of the present invention generally provide an input device including a display device having an integrated capacitive sensing device. The input device includes a plurality of source lines, a plurality of routing traces coupled to a plurality of sensor electrodes, and a processing system. The processing system is configured to update a first sub-pixel coupled to a first source line by driving the first source line with a first voltage. The processing system is further configured to drive one or more routing traces included in the plurality of routing traces with a second voltage that is an inverted version of the first voltage. The processing system is further configured to receive resulting signals from at least one sensor electrode via the one or more routing traces while the one or more routing traces are driven with the second voltage, and determine positional information based on the resulting signals.