Active Stylus Data Transmission via Capacitive Sense Array
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Solution Overview
Problem
Existing touch screen technologies face limitations with resistive touch screens, particularly in supporting multi-touch inputs and requiring tethered active styluses, which are inconvenient for private applications like personal computers and smartphones.
Innovation Solution
The development of an active stylus system that synchronizes with a host device using a capacitive sense array, allowing for the transmission of stylus data during coordinate scans, enabling simultaneous tracking of the stylus and touch objects on a capacitive touch screen without the need for a tethered connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tethered cable is used for active stylus connection, then data transmission reliability is improved, but device portability and ease of operation deteriorate
Solution Approach 1:
The patent extracts and removes the tethered cable from the active stylus system, transitioning to a wireless connection method. The stylus communicates with the host device through wireless signals (such as radio frequency or infrared) while the host device continuously scans for stylus presence and data using its capacitive sense array, eliminating the physical cable constraint while maintaining data transmission capability.
Solution Approach 2:
The patent introduces the capacitive sense array as an intermediary communication channel between the stylus and host device. The sense array serves dual purposes: detecting touch inputs and receiving stylus data wirelessly through capacitive coupling, enabling data transmission without a physical cable connection.
2Measurement precision
If coordinate scan time is dedicated solely to position detection, then measurement precision is improved, but data transmission speed deteriorates
Solution Approach 1:
The patent merges the coordinate scan function with the stylus data reception function into a single integrated process. The host device's capacitive sense array performs coordinate detection and stylus data acquisition simultaneously during the same scan period, eliminating the need for separate time allocations for these functions.
Solution Approach 2:
The patent implements continuous scanning of the capacitive sense array that simultaneously performs multiple useful actions: detecting stylus presence, determining coordinate position, and receiving stylus data. This continuous multi-functional scanning eliminates idle time and maximizes the utilization of each scan cycle for both position detection and data transmission.
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 enhances the usability of touch screens by allowing for efficient and untethered stylus operation, supporting multi-touch inputs, and improving data transmission efficiency, thus addressing the limitations of resistive touch screens and tethered styluses.
Implementation Method 1
capacitive sense array to determine coordinates of the stylus
Data Source
AI summary
Apparatus and methods of active stylus to host device data transmitting are described. One method receives, at a stylus, an indication that a host device is performing a first coordinate measurement operation to determine a coordinate of the stylus proximate to a capacitive sense array of the host device. The set of coordinate measurement operations includes a first measurement operation of a first set of electrodes of the capacitive sense array and a second measurement operation of a second set of electrodes of the capacitive sense array. While the host device is performing the set of coordinate measurement operations, the stylus transmits a data packet of stylus data to the host device. In particular, the stylus transmits a first bit of the data packet during the first measurement operation and transmits a second bit of the data packet during the second measurement operation.