Touch Controller Noise Cancellation During Charging
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Solution Overview
Problem
Touch sensor panels in devices coupled to chargers face noise interference from power adapters, leading to false touch readings and erroneous touch location identification due to noise stimulation during charging.
Innovation Solution
Implementing a power charging touch mode that includes low noise frequency selection, increased sampling to calculate averages, and simultaneous sampling to reduce noise effects, allowing the touch controller to switch to a noise-canceled or reduced touch scan mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the device uses a power adapter to charge the battery, then the battery charging function is improved, but noise is introduced that adversely affects the touch sensor panel performance
Solution Approach 1:
The system dynamically switches between normal touch scan mode and power charging touch mode based on whether the device is connected to a power adapter. This dynamic adaptation allows the touch controller to optimize its operation for the current power state, reducing noise interference during charging while maintaining normal performance when charging is not occurring.
Solution Approach 2:
The patent changes the touch scan parameters specifically during power charging mode. By modifying the scan mode parameters when noise interference is expected (during charging), the system can distinguish actual touch events from noise-induced signals, thereby resolving the contradiction between charging functionality and touch sensor accuracy.
2Speed
If the touch sensor panel operates in normal scan mode during charging, then the touch detection speed is maintained, but false touch readings and erroneous touch location identification occur
Solution Approach 1:
The touch controller dynamically adjusts the scan mode based on the charging state. During power charging, it switches to a specialized mode that filters noise while maintaining touch detection capability. This dynamic adjustment resolves the contradiction by adapting the detection parameters to the current operational context.
Solution Approach 2:
The system uses feedback from the power adapter connection status to determine the appropriate touch scan mode. By continuously monitoring whether the device is charging and adjusting the touch scan parameters accordingly, the system maintains both detection speed and accuracy under varying operational conditions.
3Device complexity
If the touch controller uses standard touch scan mode during charging, then the processing simplicity is maintained, but the ability to distinguish real touches from noise is reduced
Solution Approach 1:
The touch controller dynamically selects between normal and power charging scan modes based on the charging state. This dynamic approach allows the system to use simpler processing during normal operation while switching to enhanced noise-filtering processing only when charging occurs, thus maintaining reliability without permanently increasing complexity.
Solution Approach 2:
The system changes the touch scan parameters specifically during power charging mode to filter out noise. By modifying parameters only when necessary (during charging), the system maintains processing simplicity for the majority of operation time while improving reliability during the specific condition where noise interference occurs.
Data Source
AI summary
Touch scan modes for touch sensitive devices during device charge is disclosed. To prevent adverse effects to the touch sensor panel due to inductive noise while the device is charging, the touch controller can switch to a touch scan mode (i.e., power charging touch mode) that can cancel or reduce noise from the touch scan or touch image. Power charging touch modes can include low noise frequency selection, increased number of touch samples employed to calculate an average, and simultaneous sampling. In some examples, a power charging touch mode can be different from a normal touch scan mode (i.e., a touch scan mode when the device is not charging). With the one or more power charging touch modes, false touch readings, erroneous touch location identification, and/or undetected touches can be eliminated or reduced.