Multi-stage Stylus Scanning for Capacitive Touch Screens
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Capacitive touch screen systems face challenges in synchronizing with styluses, leading to high power consumption and increased costs, particularly when tracking synchronized styluses, and there is a need for efficient detection and tracking of both synchronized and unsynchronized styluses.
Innovation Solution
The system performs a full scan of electrodes to detect a stylus and determine its position, followed by reduced or fast scans of subsets of electrodes to track its movement, using an unsynchronized stylus approach that does not require synchronization with the capacitive sense array, allowing for reduced power usage and faster tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If synchronized stylus approach is used, then stylus tracking accuracy is improved, but power consumption increases
Solution Approach 1:
The scanning process is divided into two distinct stages: a first stage that performs comprehensive scans of the entire sense array to detect stylus presence and determine position, and a second stage that performs reduced scans of only those electrodes where stylus signal was detected. This segmentation allows the system to maintain accurate stylus tracking while significantly reducing power consumption by limiting continuous scanning to only the necessary electrode subsets.
2Measurement precision
If full scan of all electrodes is performed, then stylus detection accuracy is improved, but scanning speed decreases
Solution Approach 1:
The electrode scanning is segmented into complete scans during the first stage for accurate stylus detection, and then into reduced scans of only relevant electrode subsets during the second stage. This allows the system to achieve both high detection accuracy through initial comprehensive scanning and high scanning speed through subsequent targeted scanning of smaller electrode groups.
Solution Approach 2:
The first stage performs preliminary comprehensive scanning of all electrodes to identify which electrodes are actually interacting with the stylus. This preliminary action enables the second stage to focus scanning efforts only on relevant electrodes, thereby increasing scanning speed without sacrificing detection accuracy.
3Reliability
If synchronized stylus approach is used, then stylus signal detection reliability is improved, but system complexity increases
Solution Approach 1:
The system employs an unsynchronized stylus approach where the stylus operates independently without requiring synchronization with the capacitive sense array. The host device autonomously performs scanning and stylus detection without needing to coordinate timing or frequency with the stylus, thereby maintaining reliable signal detection while significantly reducing system complexity.
4Use of energy by moving object
If unsynchronized stylus approach is used, then power consumption is reduced, but stylus tracking precision may decrease
Solution Approach 1:
The scanning process is segmented into two stages: initial comprehensive scanning to detect stylus presence and determine position, followed by reduced scanning of electrode subsets to track stylus movement. This segmentation enables the use of unsynchronized stylus with lower power consumption while maintaining tracking precision through targeted scanning of relevant electrodes.
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 method reduces power consumption and costs while enabling efficient detection and tracking of styluses, improving the overall performance of capacitive touch screen systems by using unsynchronized styluses and optimizing scanning processes.
Implementation Method 1
The stylus receives the synchronization signal from the transmitter and generates a transmit signal, based on the synchronization signal, which is detected by the capacitive sense array. Sensing circuitry in or coupled to the capacitive sense array can detect the presence of the stylus and determine a location of the stylus based on the detected transmit signal from the stylus.
Data Source
AI summary
A system comprises a processing device and a capacitive sense array that includes a plurality of electrodes. The system performs a first scan of a plurality of electrodes in a capacitive sense array to determine a position of a stylus. The system also performs one or more additional scans of subsets of the plurality of electrodes to determine additional positions of the stylus. The system may continually perform the additional scans on of the subsets of the plurality of electrodes until the stylus is no longer detected.