Active Stylus Modulation for Touch Sensor Communication
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Solution Overview
Problem
Current touch-position sensors, particularly capacitive touch screens, face challenges in accurately determining the presence and location of objects like fingers or styluses due to interference and signal processing complexities, especially when multiple inputs are involved.
Innovation Solution
The implementation of a capacitive touch sensor system with an array of drive and sense electrodes on substrates, using a controller to process changes in capacitance across these electrodes, allowing for precise detection of touch or proximity through mutual-capacitance or self-capacitance methods, and an active stylus that can communicate effectively with the sensor system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitive touch sensor uses mutual-capacitance or self-capacitance methods to detect touch positions, then measurement precision is improved, but device complexity increases due to array of drive and sense electrodes and signal processing requirements
Solution Approach 1:
The touch sensor is divided into multiple drive electrodes and sense electrodes arranged in arrays, creating discrete sensing points across the touch surface. This segmentation allows precise localization of touch positions by identifying which specific electrode intersections experience capacitance changes, thereby improving measurement precision while managing complexity through modular electrode structures.
Solution Approach 2:
The patent transitions from single-point capacitance sensing to a two-dimensional array of drive and sense electrodes. By adding spatial dimensions to the sensing architecture, the system can detect touch positions across the entire touch surface area, significantly improving positional measurement precision. The mutual-capacitance method creates a grid of sensing points that maps touch location in both X and Y dimensions simultaneously.
2Measurement precision
If active stylus communicates with touch-sensor device through capacitance changes, then interaction precision is improved, but interference from multiple inputs increases
Solution Approach 1:
The active stylus and touch-sensor device establish a bidirectional communication system where the stylus transmits identification signals through capacitance changes and the controller processes these signals to provide feedback. This feedback mechanism allows the system to distinguish between multiple inputs by recognizing unique signal patterns from different styluses, thereby maintaining interaction precision even when multiple styluses are present. The controller can track and differentiate signals from multiple styluses based on their individual communication protocols.
Solution Approach 2:
The capacitance coupling between the active stylus and touch sensor acts as an intermediary communication channel. This intermediate coupling mechanism allows indirect signal transmission that can be distinguished from direct finger touches or other input methods. The stylus uses this intermediary capacitance path to transmit encoded identification signals, enabling the controller to differentiate stylus inputs from other touch types and reduce interference from multiple simultaneous inputs.
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 solution enables accurate and reliable detection of touch positions, reducing interference and improving interaction precision across various devices, including smartphones and tablets, by effectively processing capacitance changes and utilizing an active stylus for enhanced communication.
Implementation Method 1
When an object touches or comes within proximity of the surface of the capacitive touch screen, a change in capacitance may occur within the touch screen at the location of the touch or proximity.
Implementation Method 2
the drive unit to transmit the signal to the touch sensor device through electromagnetic coupling
Data Source
AI summary
In one embodiment, an apparatus comprises a sense unit and a drive unit. The sense unit is operable to sense a first signal from drive lines of a touch sensor. The touch sensor comprises the drive lines and sense lines arranged relative to the drive lines such that intersections of the drive lines and the sense lines form one or more capacitive nodes. The drive unit is operable to transmit a second signal based on the first signal to the sense lines such that transmission of the second signal changes the perceived capacitance of the one or more capacitive nodes.