Adaptive Touch Scanning via Dynamic Scan Rate Adjustment
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Solution Overview
Problem
Current touch interfaces in computing devices face inefficiencies due to fixed scan intervals, leading to increased power consumption and potential loss of touch responsiveness, as they fail to adapt to varying user interaction speeds, resulting in over-sampling or under-sampling issues.
Innovation Solution
Implementing an adaptive touch scanning system that dynamically adjusts the sampling frequency using a PID controller to maintain a pre-defined target distance between touch inputs, thereby optimizing scan intervals based on user interaction speed, minimizing energy consumption while maintaining high touch responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed high scan interval is used to guarantee good touch responsiveness, then touch event detection is improved, but power consumption increases and the device cannot enter lower power states
Solution Approach 1:
The scan interval is changed from a fixed value to a dynamic value that adjusts based on touch activity. The system uses an exponential backoff algorithm that increases the scan interval when no touch events are detected, and decreases it when touch events occur, allowing the device to enter lower power states during idle periods while maintaining responsiveness during active use
Solution Approach 2:
The system implements a feedback mechanism where the scan interval is continuously adjusted based on detected touch events. The exponential backoff algorithm uses the history of touch events to dynamically modify the scan interval, creating a closed-loop control system that balances power consumption and touch responsiveness based on actual user interaction patterns
2Speed
If frequent scans are performed to detect touch events promptly, then touch responsiveness is improved, but the device is prevented from entering sleep states
Solution Approach 1:
The system uses periodic scanning with a variable period that adapts to touch activity. Instead of continuous scanning at a fixed high frequency, the scan interval is adjusted periodically based on touch event detection, allowing longer intervals during idle periods while maintaining short intervals when touch activity is detected
Solution Approach 2:
The scan interval transitions from a static fixed value to a dynamic value that responds to touch activity. The exponential backoff mechanism dynamically adjusts the time between scans based on the recency of touch events, enabling the system to enter sleep states during idle periods while maintaining rapid response capability when touched
3Device complexity
If a fixed scan rate is used, then implementation is simple, but over-sampling and under-sampling occur reducing efficiency
Solution Approach 1:
The scan rate parameter is changed from a fixed value to a variable value that adapts to touch activity. The exponential backoff algorithm modifies the scan interval parameter dynamically based on touch event history, optimizing the balance between sampling accuracy and energy efficiency for different usage scenarios
Data Source
AI summary
An apparatus, touch controller, and system for adaptive touch scanning is described herein. The apparatus includes logic to calculate a distance traveled between two consecutive touch samples, and logic to compare the distance traveled with a target distance to find an actual error. The apparatus also includes logic to update the scan rate based on the actual error.