Stylus Tip Shielding for Accurate Capacitive Detection at Tilt
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Solution Overview
Problem
Capacitive styluses are affected by the shadow effect when held at non-perpendicular angles to touch screens, leading to inaccurate position detection.
Innovation Solution
A dynamically switched tip shield on the stylus, coupled with a conductive tip and a force sensor, adjusts the electric field to improve position accuracy by reducing the shadow effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitive stylus is used with a capacitive touch screen, then the touch screen can detect stylus input, but the shadow effect occurs at non-perpendicular angles causing inaccurate position detection
Solution Approach 1:
A tip shield is introduced as an intermediary component between the conductive tip and the sensing area. The tip shield is configured to be electrically isolated from the conductive tip and positioned between the tip and the sensing area to block or reduce the shadow effect caused by the conductive tip at non-perpendicular angles, thereby improving position detection accuracy without sacrificing stylus detection capability
Solution Approach 2:
The tip shield is positioned specifically at the tip region of the stylus where the shadow effect is most pronounced. By localizing the shielding function to this critical area, the patent reduces the shadow effect precisely where it impacts measurement accuracy most, while maintaining overall stylus detection functionality across the entire sensing area
2Measurement precision
If a tip shield is added to reduce the shadow effect, then position accuracy improves, but device complexity increases
Solution Approach 1:
The tip shield is implemented as a thin, flexible component that can be integrated into the stylus tip assembly. This approach minimizes the added complexity by using a simple, lightweight structure rather than a complex mechanical or electronic system, making the shield easy to manufacture and integrate without significantly increasing device complexity
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
Enhances the accuracy of stylus detection on capacitive touch screens by minimizing the shadow effect, allowing for precise tracking even at non-perpendicular angles.
Implementation Method 1
a capacitive sensor array that senses changes in a capacitance signal in response to a presence of the stylus tip
Implementation Method 2
A dynamically switched tip shield on the stylus, coupled with a conductive tip and a force sensor, adjusts the electric field to improve position accuracy by reducing the shadow effect
Data Source
AI summary
A stylus detecting system includes a sense array including N number of first lines and M number of second lines crossing the N number of first lines; and a touch controller connected to the sense array and configured to: (i) in a touch object detecting mode, drive the N number of first lines as transmission (TX) lines with a finger sensing TX signal and measure reception (RX) signals on the M number of second lines as RX lines, and (ii) in a stylus detecting mode, measure a stylus TX signal transmitted by a stylus, on both the N number of first lines and the M number of second lines, using # number of multiple RX channels (#RX channels) to sense more than one line of the N number of first lines and the M number of second lines at the same time, such that a stylus scanning time is reduced as compared to using a single RX channel to scan all lines, thereby completing a stylus scan in fewer total scans.