Capacitive Stylus Timing Master Synchronization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional touch screen technologies, such as inductive and radio frequency sensing arrays, face issues like high power consumption, electromagnetic interference, high manufacturing costs, and the need for additional PCB layers, which hinder the development of efficient and reliable stylus tracking solutions for capacitive touch screens.
Innovation Solution
A capacitive sense array system that synchronizes with a stylus, allowing simultaneous tracking of both a passive touch object and a stylus, using a capacitive sense array with an N×M electrode matrix, where the stylus operates as the timing master, and the touch screen controller adjusts its timing to match, enabling efficient position tracking without the need for additional PCB layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If inductive sensing arrays are used for stylus tracking, then stylus position detection is achieved, but power consumption increases and electromagnetic interference occurs
Solution Approach 1:
The patent extracts the stylus tracking function from the traditional inductive sensing array and implements it using the existing capacitive sense array electrodes. By reusing the same electrode matrix for both touch object detection and stylus tracking, the system eliminates the need for separate inductive coils, thereby reducing power consumption and electromagnetic interference while maintaining stylus position detection capability
Solution Approach 2:
The capacitive sense array electrodes are designed to serve multiple functions: detecting touch objects (fingers) and tracking the stylus simultaneously. The controller distinguishes between these two functions by analyzing signal characteristics and timing, allowing one hardware component to perform multiple sensing tasks without requiring additional inductive sensing layers
2Measurement precision
If inductive sensing arrays are used for stylus tracking, then stylus position detection is achieved, but electromagnetic interference increases
Solution Approach 1:
The patent removes the inductive sensing array component that generates electromagnetic interference and replaces its function with capacitive sensing using the existing electrode matrix. This extraction eliminates the source of electromagnetic interference while preserving the stylus tracking capability through capacitive coupling detection
Solution Approach 2:
The patent converts the potential interference issue into a benefit by using the capacitive sense array's natural capacitive coupling to detect the stylus. Instead of fighting electromagnetic interference from inductive coils, the system leverages the capacitive properties of the electrode-stylus interaction for accurate tracking without harmful electromagnetic radiation
3Measurement precision
If additional PCB layers are added for inductive sensing, then stylus tracking capability is improved, but manufacturing cost increases
Solution Approach 1:
The patent makes the existing capacitive sense array electrodes perform dual functions: touch object detection and stylus tracking. By configuring the controller to distinguish between finger touches and stylus contact based on signal characteristics and timing synchronization, the system achieves stylus tracking capability without adding expensive inductive sensing layers or PCB modifications
Solution Approach 2:
The existing capacitive sense array serves itself by detecting both touch objects and stylus through the same electrode matrix. The controller automatically distinguishes between the two input types by analyzing signal patterns and timing, allowing the system to provide stylus tracking functionality using its existing hardware infrastructure without requiring additional manufacturing layers or components
4Measurement precision
If conventional capacitive sensing is used, then touch object detection is achieved, but simultaneous stylus tracking is not possible
Solution Approach 1:
The patent implements dynamic timing synchronization where the stylus operates as a timing master, sending synchronization signals that allow the controller to dynamically adjust its sampling and detection windows. This dynamic timing approach enables the system to distinguish between static finger touches and active stylus input, allowing simultaneous tracking of both touch objects and stylus without interference
Solution Approach 2:
The stylus provides feedback signals to the controller through capacitive coupling, including synchronization signals that indicate when the stylus is active and position information. The controller uses this feedback to adjust its detection algorithm, enabling it to simultaneously track touch objects and stylus by analyzing the timing and characteristics of the capacitive signals from the electrode matrix
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 reduces power consumption, minimizes electromagnetic interference, and lowers manufacturing costs by allowing concurrent and accurate tracking of both fingers and styluses on capacitive touch screens, enhancing the reliability and efficiency of touch screen systems.
Implementation Method 1
a capacitive sense array with an N×M electrode matrix
Data Source
AI summary
A stylus having a transmit drive circuit configured to transmit a signal to a capacitance sensor via capacitive coupling between the stylus and a capacitive sense array which is coupled to the capacitance sensor, which is configured to synchronize to the stylus, the stylus being configured to act as a timing master.