Clock Synchronization Tolerance for Touch Display and Stylus
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Solution Overview
Problem
Existing touch sensing systems face challenges in achieving accurate clock synchronization between touch display devices and styluses, particularly due to crystal inaccuracies, Bluetooth communication delays, and consecutive failed transmissions.
Innovation Solution
A method for determining clock synchronization between a touch display device and a stylus by calculating an accumulated timing error based on crystal inaccuracies, Bluetooth connection intervals, and consecutive failed transmissions, and then determining a total processing delay to establish a tolerance specification for synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If clock synchronization is performed between touch display device and stylus, then synchronization accuracy is improved, but timing errors due to crystal inaccuracies and Bluetooth delays cannot be fully eliminated
Solution Approach 1:
The system performs preliminary actions by calculating the accumulated timing error in advance based on crystal inaccuracies, Bluetooth connection intervals, and failed transmission counts. This allows the system to proactively compensate for timing errors before they significantly impact synchronization accuracy, rather than reacting after errors have accumulated.
Solution Approach 2:
The system implements feedback by continuously monitoring Bluetooth transmission status and recalculating the accumulated timing error based on actual transmission outcomes. When transmissions fail, the system adjusts the timing error calculation to reflect the actual state, ensuring the synchronization remains accurate despite varying communication conditions.
2Device complexity
If Bluetooth communication is used for synchronization, then device complexity is reduced, but processing delays increase due to communication overhead
Solution Approach 1:
The system measures and stores processing delays (first processing delay for synchronization signal, second processing delay for Bluetooth packet) in advance. By having these delay values pre-determined and stored, the system avoids real-time delay calculations during critical synchronization moments, reducing computational overhead and time loss.
Solution Approach 2:
The system introduces an intermediary calculation layer that separates the Bluetooth communication function from the timing calculation function. The Bluetooth module handles communication while the processing circuitry independently calculates timing errors using pre-measured delays, allowing both functions to operate optimally without interfering with each other's performance.
3Reliability
If consecutive failed transmissions are accounted for in timing error calculation, then synchronization reliability is improved, but calculation complexity increases
Solution Approach 1:
The system segments the timing error calculation into distinct components: crystal inaccuracy contribution, Bluetooth connection interval contribution, and failed transmission contribution. Each component is calculated separately and then combined, making the overall complex calculation manageable and maintainable while improving synchronization reliability through comprehensive error accounting.
Data Source
AI summary
A method, apparatus, and computer-readable medium for determining a tolerance specification of a clock synchronization between a touch display device (TDD) and a stylus. In the method, an accumulated timing error between the TDD and the stylus is determined based on crystal inaccuracies of the TDD and the stylus, connection interval of Bluetooth communication between the TDD and the stylus, and a number of consecutive failed transmissions of the Bluetooth communication. A total processing delay is determined based on a first processing delay and a second processing delay. The first processing delay is a time delay of sending a synchronization signal from touch driving circuitry of the TDD to Bluetooth circuitry of the TDD. The second processing delay is a time delay of sending a Bluetooth packet from the TDD to the stylus. The tolerance specification is determined based on the accumulated timing error and the total processing delay.