Capacitive Touch Detection Cycle Synchronization for Noise Cancellation
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Solution Overview
Problem
Existing touch detection systems in semiconductor devices face accuracy issues due to extraneous noise from AC chargers, particularly when the noise frequency coincides with the touch detection cycle, leading to decreased accuracy in higher definition displays where the display-scan cycle is shortened.
Innovation Solution
The semiconductor device employs a capacitive sensing controller to set the detection cycle as an odd multiple of half the display-scan cycle and the detection period as an integer multiple of the display-scan cycle, synchronizing with the periodic noise signal to invert the noise polarity and cancel its influence in consecutive detection periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the touch detection cycle is synchronized with the display-scan cycle to improve detection accuracy, then the noise from AC chargers accumulates periodically and worsens the detection accuracy
Solution Approach 1:
The patent applies periodic action by setting the detection cycle to an odd multiple of half the display-scan cycle period. This creates a periodic detection pattern that deliberately desynchronizes from the noise-generating display scanning, causing the noise to alternate in polarity between consecutive detection periods and thereby cancel out over time while maintaining regular detection intervals
Solution Approach 2:
The patent converts the harmful periodic noise into a beneficial cancellation effect by exploiting its periodic nature. By timing the detection cycles to coincide with odd multiples of half the noise period, the noise appears with opposite polarity in alternating detection periods, transforming the harmful accumulation effect into a self-canceling pattern that improves measurement accuracy
2Speed
If the detection cycle is shortened to increase detection frequency, then the touch response speed improves, but the display-scan cycle becomes too short to accommodate proper detection periods in higher definition displays
Solution Approach 1:
The patent applies dynamics by making the detection cycle flexible rather than fixed. It sets the detection cycle to an odd multiple of half the display-scan cycle period, allowing the system to adapt to different display resolutions and scanning speeds while maintaining optimal detection timing. This dynamic adjustment enables higher detection frequencies without compromising the minimum required detection period duration
3Measurement precision
If the detection period is set to an integer multiple of the display-scan cycle, then the noise cancellation is effective, but the detection frequency is limited by the display scanning speed
Solution Approach 1:
The patent uses periodic action by setting the detection period to an integer multiple of the display-scan cycle period. This creates a regular detection pattern that aligns with the display scanning rhythm, ensuring that noise cancellation remains effective while allowing multiple detection cycles to occur within each display scan period, thereby maintaining high detection frequency
Solution Approach 2:
The patent applies segmentation by dividing the detection process into multiple sub-cycles within each display-scan cycle. By setting the detection period to an integer multiple of the display-scan period, the system can perform multiple discrete detection operations during a single display scan, effectively segmenting the detection task to increase overall detection frequency while preserving noise cancellation benefits
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 the impact of extraneous noise on touch detection accuracy, even with longer noise cycles, allowing for reliable touch detection in systems using AC chargers that generate periodic noise, thereby reducing system costs and maintaining accuracy in higher definition displays.
Implementation Method 1
detect detection data according to capacitance between drive and detection electrodes
Implementation Method 2
periodically capture sensing signals on the detection electrodes to generate data for detecting an object proximate to the detection electrodes
Data Source
AI summary
Embodiments herein include a device, system, and method for periodically capturing sensing signals using one or more detection electrodes to generate data for detecting an object proximate to the detection electrodes. The sensing signals are captured during detection periods within periodic detection cycles where each of the detection cycles define a period of time between consecutive detection periods. In addition, the device, system and method set a duration of the detection cycle to 1/m (where m is appositive integer) of a duration of a display-scan cycle. The value of m is selected based on a periodic noise signal. Thus, the device, system, and method may prevent a periodic noise signal which has a cycle that is longer than the detection period from worsening the accuracy of touch detection.