Capacitive Touchscreen Adaptive Scanning Power Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Capacitive touchscreen systems in battery-operated mobile devices face significant challenges in reducing power consumption, which affects their performance and battery life, especially when handling multiple touches and requiring continuous scanning of electrodes.
Innovation Solution
A capacitive touchscreen system that dynamically adjusts its scanning rate and mode based on touch activity, using a touchscreen processor to provide drive signals to electrically conductive drive traces and sense traces, allowing for mutual capacitance sensing, and implementing adaptive scanning rates to conserve power by reducing unnecessary sensing when no touches are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous scanning of electrodes is performed to detect multiple touches, then touch detection accuracy is improved, but power consumption increases
Solution Approach 1:
The patent implements dynamic scanning rate adjustment based on touch activity. The system transitions between different scanning modes (full scan, partial scan, reduced scan) depending on whether touches are detected, allowing the scanning rate to adapt dynamically. This resolves the contradiction by maintaining high accuracy when needed while reducing power consumption during idle periods.
Solution Approach 2:
The patent changes the scanning rate parameter based on system state. By modifying the scanning frequency from continuous full scan to intermittent partial scans, the system optimizes the balance between measurement precision and energy consumption. The scanning rate is adjusted as a key parameter responding to touch detection status.
2Speed
If scanning rate is increased to improve responsiveness, then system responsiveness is improved, but power consumption increases
Solution Approach 1:
The system dynamically adjusts scanning rate based on real-time touch detection. When touches are detected, the system switches to higher scanning rates (full scan mode) to maintain responsiveness. When no touches are detected, it transitions to lower scanning rates (rest mode) to conserve power. This dynamic adaptation resolves the contradiction between responsiveness and power consumption.
3Measurement precision
If full scan mode is used continuously, then touch detection accuracy is maintained, but battery life decreases
Solution Approach 1:
The patent implements periodic scanning instead of continuous full scanning. The system performs full scans only when necessary (when touches are detected) and uses reduced scanning during idle periods. This periodic action maintains detection accuracy when needed while extending battery life by avoiding unnecessary continuous scanning.
Solution Approach 2:
The system changes the scanning frequency parameter based on operational state. By reducing the scanning rate during rest mode and increasing it during active mode, the system optimizes the trade-off between maintaining detection accuracy and preserving battery life. This parameter adjustment directly addresses the contradiction.
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 reduces power consumption by selectively increasing scanning rates around detected touches and decreasing rates in untouched areas, thereby improving battery life and system responsiveness while maintaining accurate touch detection.
Implementation Method 1
mutual capacitances are developed between the first and second pluralities of traces by the drive signals at locations where the first and second pluralities of traces intersect to form pixels, such mutual capacitances changing in the presence of one or more fingers, hands or touch devices brought into proximity thereto
Implementation Method 2
Self-capacitance involves measuring the self-capacitance of a series of electrode pads using techniques such as those described in U.S. Pat. No. 5,543,588 to Bisset et al. entitled 'Touch Pad Driven Handheld Computing Device' dated Aug. 6, 1996
Implementation Method 3
When external objects are brought close to the electrode, additional charge is attracted to the electrode. As a result, the self-capacitance of the electrode increases.
Data Source
AI summary
Disclosed herein are various embodiments of a capacitive touchscreen system that is capable of sensing finger touches made on a capacitive touchscreen according to various scanning modes that reduce power consumption of the capacitive touchscreen system. The disclosed power saving scanning modes are modally focused, and can be used not only to reduce system power consumption, but also to enhance the user experience with the capacitive touchscreen system.