Capacitive Sensor Noise Reduction in LED Displays
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Solution Overview
Problem
Capacitive sensor devices in electronic devices face interference from light emitting diode (LED) displays, particularly due to the capacitive coupling between the LED's conductive layers and the sensor electrodes, which affects the accuracy of capacitive sensing signals.
Innovation Solution
Incorporating a processing system with dual receivers, one for determining capacitive sensing signals and another for measuring interference from the LED display's transparent conductive layer, allowing for simultaneous interference detection and signal processing to mitigate noise and improve sensing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If capacitive sensing is performed using sensor electrodes disposed on LED display, then touch input functionality is integrated into the display, but interference noise from the LED display's transparent conductive layer degrades sensing accuracy
Solution Approach 1:
The patent divides the sensing function into two separate receivers: a first receiver dedicated to capacitive sensing and a second receiver dedicated to interference measurement. This segmentation allows each receiver to specialize in its specific function, with the first receiver capturing the capacitive sensing signal and the second receiver capturing the interference signal from the transparent conductive layer, thereby resolving the accuracy degradation caused by integrated LED display interference
Solution Approach 2:
The patent introduces an intermediary processing mechanism that receives both the capacitive sensing signal from the first receiver and the interference signal from the second receiver. This intermediary processing stage combines or subtracts the interference signal from the sensing signal to produce a corrected output, effectively mediating between the harmful interference and the desired sensing function
2Measurement precision
If dual receivers are used for simultaneous interference detection and signal processing, then sensing accuracy is improved, but device complexity increases
Solution Approach 1:
The patent implements multi-functionality by having the processing system handle both capacitive sensing and interference measurement through a unified architecture. The first receiver processes capacitive sensing signals while the second receiver processes interference signals, and both are integrated into a single processing system that can simultaneously or sequentially handle both functions, reducing overall system complexity compared to separate independent systems
Solution Approach 2:
The patent employs periodic action by alternating between capacitive sensing operations and interference measurement operations in time-multiplexed fashion. The system can switch between using the first receiver for sensing and the second receiver for interference detection at different time intervals, or use both receivers in parallel with periodic signal processing, thereby managing complexity through temporal separation of functions
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 noise, enhancing the accuracy and reliability of capacitive sensing by allowing for real-time interference measurement and signal processing, thereby improving user interaction with electronic devices.
Implementation Method 1
interference generated by the LED display, particularly due to the capacitive coupling between the LED's conductive layers and the sensor electrodes
Data Source
AI summary
Embodiments herein provide input devices that include an LED display panel on which a discreet capacitive sensor is disposed to form a capacitive sensing region. The capacitive sensor includes a plurality of sensor electrodes that are used to generate capacitive sensing signals indicating user interaction with the input device. In one embodiment, the sensor electrodes are disposed on a cathode layer in the LED display panel such that the sensor electrodes are capacitively coupled to the LED display panel. Currents in the cathode layer can cause interference or noise when performing capacitive sensing. The input devices include an analog front end channel for measuring interference resulting from the cathode layer at the same time receivers measure capacitive sensing signals using the sensor electrodes. The input device may process the capacitive sensing signals differently depending on the measured interference.