Capacitive Stylus Detection via Partial Scanning
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Solution Overview
Problem
The existing systems that use capacitive touch screens face challenges in maintaining synchronicity between the capacitive sense array and the stylus, leading to increased power usage and costs, and require complex design-in support, especially when using synchronized styluses.
Innovation Solution
The system employs a method to detect both synchronized and unsynchronized styluses by performing initial scans of a subset of electrodes to determine the presence of a stylus, using in-phase and quadrature components of the signal to calculate a value that exceeds a threshold, and then conducts a full scan if necessary, allowing for efficient power usage and quicker 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 and device complexity increase
Solution Approach 1:
The patent segments the stylus into two operational modes: synchronized mode (for high precision tracking when needed) and unsynchronized mode (for normal operation). This allows the system to achieve accurate stylus tracking when required while consuming less power during typical use, resolving the contradiction between tracking accuracy and power consumption.
Solution Approach 2:
The system dynamically switches between synchronized and unsynchronized stylus operation based on application requirements. The capacitive sense array adjusts its operation mode in real-time, enabling high precision tracking only when necessary and reducing power consumption during normal operation, thus resolving the contradiction between measurement precision and energy usage.
2Measurement precision
If synchronized stylus approach is used, then stylus tracking accuracy is improved, but device complexity and design-in support requirements increase
Solution Approach 1:
The patent makes the capacitive sense array universal by enabling it to detect both synchronized and unsynchronized styluses using the same hardware infrastructure. The sense array can operate in multiple modes (finger touch mode, synchronized stylus mode, unsynchronized stylus mode) without requiring separate hardware layers, thereby reducing device complexity while maintaining high tracking accuracy when needed.
Solution Approach 2:
Instead of requiring the stylus to actively synchronize with the sense array (complex approach), the patent inverts the approach by enabling the sense array to detect passive unsynchronized styluses through capacitive coupling. This inversion simplifies the overall system architecture while maintaining the capability for accurate stylus tracking when synchronization is implemented.
3Measurement precision
If full scan of all electrodes is performed continuously, then stylus detection accuracy is improved, but processing time and power consumption increase
Solution Approach 1:
The patent applies partial scanning by initially scanning only a subset of electrodes to detect stylus presence and determine approximate location. Once a stylus is detected, the system then performs a full scan of all electrodes to achieve precise location tracking. This partial-or-full scanning approach maintains high detection accuracy while significantly improving processing efficiency compared to continuous full scans.
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 and enhances the ability to quickly track styluses, both synchronized and unsynchronized, without the need for additional hardware layers, thereby improving the overall efficiency and cost-effectiveness of the system.
Implementation Method 1
capacitive sensor devices... capacitive touch screens... capacitive sense array
Implementation Method 2
The transmitter may wirelessly couple the synchronization signal in a variety of ways including, inductance, radio frequency
Data Source
AI summary
A system comprises a processing device and a capacitive sense array that includes a plurality of electrodes. The system receives a first signal from a first scan of electrodes in a capacitive sense array. The system processes the first signal using a first set of sequences to detect a stylus. The system receives a second scan from a second scan of electrodes in a capacitive sense array. The system processes the second signal using a second set of sequences to detect the stylus.