Multi-touch Auto Scanning Power Management
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Solution Overview
Problem
Conventional touch panel technologies are limited in their ability to track multiple points of contact simultaneously and consume excessive power during periods of inactivity, leading to inefficiencies and increased power consumption in handheld devices.
Innovation Solution
A multi-touch system that disables components like the touch-panel processor and system clock during inactivity, employs an auto-scan mode for periodic touch event detection, and uses a 'sniff' mode to conserve power by scanning the touch panel only when necessary, while measuring stray capacitance to determine touch events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous active scanning is performed to detect touch events, then touch detection reliability is improved, but power consumption increases
Solution Approach 1:
The system implements periodic scanning instead of continuous scanning by using a scan enable signal that activates the scanning process only at specific intervals. This allows the touch panel to be scanned periodically to detect touch events while consuming less power compared to continuous active scanning, directly resolving the contradiction between detection reliability and power consumption.
2Use of energy by moving object
If the touch panel is shut down during inactivity to save power, then power consumption is reduced, but user convenience deteriorates due to activation delay
Solution Approach 1:
The system performs preliminary actions by maintaining the touch panel in a standby state with periodic scanning capability before complete shutdown. The scan enable signal allows the system to quickly reactivate scanning without full initialization, providing a middle ground between complete shutdown and continuous operation that balances power savings with quick response to user input.
3Adaptability or versatility
If multi-touch capability is implemented to track multiple contact points, then functionality is improved, but device complexity increases
Solution Approach 1:
The system segments the touch detection process by using independent scanning channels that can be selectively enabled. Each channel can detect touch events independently, and the scan enable signal allows selective activation of scanning segments. This segmentation approach enables multi-touch capability while managing complexity through modular, selectable scanning operations.
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
The system effectively conserves power by reducing unnecessary scanning and enabling quick reactivation when needed, allowing for efficient detection of multiple touch points without continuous active scanning.
Implementation Method 1
measuring stray capacitance to determine touch events
Data Source
AI summary
A system and method for autonomously scanning a sensor panel device is disclosed. A sensor panel processor can be disabled after a first predetermined amount of time has elapsed without the sensor panel device sensing any events. One or more system clocks can also be disabled to conserve power. While the processor and one or more system clocks are disabled, the sensor panel device can periodically autonomously scan the sensor panel for touch activity. If one or more results from the autonomous scans exceed a threshold, the sensor panel device re-enables the processor and one or more clocks to actively scan the sensor panel. If the threshold is not exceeded, the sensor panel device continues to periodically autonomously scan the sensor panel without intervention from the processor. The sensor panel device can periodically perform calibration functions to account for any drift that may be present in the system.