Variable Refresh Display Touch Synchronization via Extended Blanking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Variable refresh rate displays disrupt synchronization between display functions and touch, stylus, and force sensing functions, leading to degraded performance in touch sensitive devices.
Innovation Solution
Synchronizing touch, stylus, and force sensing functions with display frames or sub-frames by adjusting the refresh rate through extended blanking periods, and using pre-warning synchronization signals to prepare scan controllers, along with latency correction through time-stamping or dropping uncompleted scan results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If variable refresh rate displays are used to save power or improve performance, then energy efficiency and graphical performance are improved, but synchronization between display functions and touch/stylus/force sensing functions is disrupted
Solution Approach 1:
The system performs preliminary actions by generating pre-warning synchronization signals before extended blanking periods occur. These signals prepare scan controllers to adjust their timing in advance, ensuring that touch, stylus, and force sensing operations remain synchronized with the variable refresh rate display without interruption. This preliminary preparation prevents synchronization disruption rather than correcting it after the fact.
Solution Approach 2:
The system dynamically adjusts the timing of sensing operations to match the variable refresh rate of the display. Scan controllers modify their scan timing based on received synchronization signals, allowing the sensing frequency to flexibly adapt to changing display refresh rates. This dynamic adjustment maintains synchronization reliability while enabling the display to vary its refresh rate for power savings and performance optimization.
2Productivity
If variable refresh rate displays are used to improve performance in computationally intensive graphical environments, then graphical performance is improved, but synchronization between display functions and touch/stylus/force sensing functions is disrupted
Solution Approach 1:
Pre-warning synchronization signals are generated in advance of extended blanking periods to prepare scan controllers for upcoming timing changes. This preliminary action ensures that sensing operations are already adjusted before the display refresh rate changes, maintaining synchronization reliability during high-performance graphical scenarios where the display may switch to higher refresh rates.
Solution Approach 2:
The scan controllers dynamically adjust their operating parameters based on real-time synchronization signals from the display controller. This allows the sensing system to flexibly track display refresh rate changes, whether increasing for gaming performance or decreasing for power savings, ensuring continuous synchronization without degrading graphical performance.
3Use of energy by moving object
If extended blanking is used to adjust display refresh rate, then power consumption is reduced, but latency between scan results and corresponding image on display increases
Solution Approach 1:
The system performs preliminary actions by time-stamping scan results with precise timing information before extended blanking periods. This allows the system to track and compensate for latency introduced by variable refresh rates, ensuring that touch, stylus, and force data are correctly correlated with the corresponding display images even when refresh rates vary for power savings.
Solution Approach 2:
The system uses feedback mechanisms to monitor and correct latency between sensing operations and display refreshes. By tracking the timing of scan results relative to display frames and using synchronization signals, the system can identify and compensate for delays introduced by extended blanking periods, maintaining accurate temporal correlation between user input and visual output.
4Reliability
If scan results are dropped to correct latency, then synchronization accuracy is improved, but loss of sensing data occurs
Solution Approach 1:
The system performs preliminary actions by implementing a buffer mechanism that stores scan results with their time stamps before they are processed. This buffer allows the system to hold sensing data temporarily while waiting for the appropriate display refresh cycle, preventing data loss when synchronization timing doesn't align perfectly. The buffer ensures no sensing information is lost while maintaining synchronization accuracy.
Solution Approach 2:
The system uses feedback to monitor synchronization status and dynamically adjust data handling. When latency is detected, the system can selectively process or buffer specific scan results based on their timing relative to display frames, rather than indiscriminately dropping data. This feedback-driven approach maintains synchronization accuracy while minimizing sensing data loss.
Data Source
AI summary
Synchronization of display functions and various touch, stylus and/or force sensing functions for devices including a variable refresh rate (VRR) display is disclosed. In some examples, touch, stylus and/or force sensing functions can be synchronized with display frames and a display refresh rate can be adjusted by extended blanking of the display for one or more display frames. In other examples, touch, stylus and/or force sensing functions can be synchronized with display sub-frames and a display refresh rate can be adjusted by extended blanking of the display for one or more display sub-frames. Pre-warning synchronization signals can be generated to prepare one or more scan controllers to implement the appropriate scan events during and after extended blanking periods. Latency between the scan results and the corresponding image on the display can be corrected in software and/or firmware by time-stamping scan results or by dropping scan results from uncompleted scans.