Touch Panel Control for Variable Frame Rate Display Devices
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Solution Overview
Problem
Display devices with touch panels operating at variable frame rates face issues where touch detection processes during a first period can interfere with normal drive processes in a second period, leading to elongation of touch detection cycles.
Innovation Solution
Implementing a control unit that starts a first touch detection process within the first period, ends it before the second period begins, and outputs report data only when the first period is longer than a predetermined length, allowing for a second touch detection process and writing process to occur during the second period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the touch detection operation is performed during the first period in variable frame rate operation, then the touch detection cycle is shortened, but the touch detection process may interfere with the normal drive process in the second period
Solution Approach 1:
The frame period is divided into a first period for touch detection operations and a second period for normal drive operations. The control unit segments the time period to ensure touch detection completes before normal drive begins, preventing interference between the two processes while maintaining frequent touch detection cycles.
Solution Approach 2:
The control unit performs preliminary action by completing the touch detection operation during the first period before the second period starts. This ensures that any touch detection process is fully concluded before the normal drive process begins, eliminating potential interference and ensuring reliable operation in variable frame rate mode.
2Reliability
If the touch detection operation is not performed during the first period to avoid interference, then the normal drive process is not affected, but the touch detection cycle becomes longer
Solution Approach 1:
The frame period is segmented into two distinct periods: the first period dedicated to touch detection operations and the second period for normal drive operations. This segmentation allows the control unit to perform touch detection frequently (shortening the detection cycle) while ensuring that each detection operation completes fully before the next normal drive begins, thus avoiding interference.
3Stability of the object's composition
If the first period is made shorter to reduce frame period variation, then the frame rate stability is improved, but the touch detection process cannot complete before the second period starts
Solution Approach 1:
The control unit dynamically adjusts the first period length based on the required touch detection process duration. When the first period is short, the control unit extends it to ensure touch detection completes before the second period starts. This dynamic adjustment maintains frame rate stability while ensuring sufficient time for touch detection operations to complete without interference.
Data Source
AI summary
A display device with a touch panel starts a first touch detection process within an extension period, and ends the first touch detection process before a normal drive period starts. The display device with a touch panel performs a process of outputting first report data when a length of the extension period is equal to or longer than a predetermined length. The display device with a touch panel performs, after the normal drive period starts, a second touch detection process, a writing process, and a process of outputting second report data.