Multi-Touch Panel Auto-Scan for Low-Power Touch Detection
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Solution Overview
Problem
Conventional touch panel technologies are limited in their ability to track multiple points of contact simultaneously and suffer from high power consumption during periods of inactivity, leading to inefficient power management and user inconvenience.
Innovation Solution
A multi-touch system that enables the disabling of components like the touch-panel processor and system clock during inactivity, employing an auto-scan mode and 'sniff' mode to conserve power, and measures stray capacitance in the touch panel sensor, allowing for periodic scanning and calibration without continuous intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the touch panel is actively scanned continuously, then touch events are detected accurately and promptly, but power consumption increases significantly
Solution Approach 1:
The system implements periodic scanning instead of continuous scanning by using a scan enable signal that activates the scan only during specific time intervals. The controller enters a low-power state between scan periods, and the scan enable signal periodically activates the scan function to detect touch events, thereby reducing power consumption while maintaining detection capability.
Solution Approach 2:
The system dynamically adjusts its operational state based on touch activity. When no touch events are detected, the system transitions to a low-power state with reduced scanning. When touch events are detected, the system activates full scanning functionality. This dynamic state adjustment allows the system to optimize between power consumption and detection accuracy based on real-time conditions.
2Use of energy by moving object
If the touch panel is shut down during inactivity, then power consumption is reduced, but the panel requires additional power to turn back on and causes user inconvenience
Solution Approach 1:
Instead of completely shutting down the touch panel, the system uses periodic scanning with a scan enable signal that activates the panel only during predetermined time intervals. This allows the panel to remain in a low-power state during inactivity while still periodically checking for touch events, thus avoiding the need for full shutdown and restart cycles that cause user inconvenience.
Solution Approach 2:
The system performs preliminary detection using a reduced scanning mode before fully activating the touch panel. The periodic scan with enable signal serves as a preliminary check that consumes minimal power, and only when touch events are detected does the system fully activate the panel, thereby avoiding unnecessary full activations and improving user experience.
3Device complexity
If conventional single-point identification is used, then the system is simpler to implement, but multiple simultaneous touch points cannot be tracked
Solution Approach 1:
The system segments the touch panel into multiple independently detectable regions or zones. Instead of treating the entire panel as a single detection point, the scan enable signal activates multiple scan channels that can independently detect touch events at different locations simultaneously. This segmentation allows multi-touch capability while maintaining relatively simple implementation through modular scanning architecture.
Solution Approach 2:
The system transitions from one-dimensional single-point detection to two-dimensional multi-point detection by implementing scans across both row and column dimensions of the touch panel. The scan enable signal coordinates scans that cover the entire panel surface, allowing detection of multiple touch points at different positions simultaneously, thereby adding spatial dimensionality to the detection capability.
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 multi-touch system effectively conserves power by enabling auto-scan and calibration modes, reducing unnecessary scanning, and accurately detecting touch events, thereby improving power management and user experience.
Implementation Method 1
measuring stray capacitance in a touch panel sensor during an auto-scan mode
Data Source
Figure 1
Figure 2A~2C
Figure 3A
AI summary
A system and method for autonomously scanning a sensor panel device, such as a multi-touch panel, is disclosed. In one embodiment, the system and method disables a sensor panel processor 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. Accordingly, 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, then the sensor panel device continues to periodically autonomously scan the sensor panel without intervention from the processor. Furthermore, the sensor panel device can periodically perform calibration functions to account for any drift that may be present in the system.