Touch Display Noise Synchronization for Accurate Stylus Detection
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Solution Overview
Problem
Electrophoretic display (EPD) systems using active capacitive stylus pens or electromagnetic radiation (EMR) stylus pens often experience significant noise issues, leading to incorrect or delayed location detection during the display process, necessitating complex filtering algorithms that delay coordinate generation.
Innovation Solution
A display device incorporating a noise detection circuit and processing circuit that detects and processes voltage signals from a common electrode to output free run and noise sync signals, allowing for real-time conversion of touch signals into location signals, with adaptive filtering to mitigate noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all signals generated in the display process are filtered, then noise is reduced, but coordinate detection is delayed or requires complicated algorithms
Solution Approach 1:
The patent segments the signal processing into two distinct paths: a fast path that processes touch signals in real-time without filtering, and a slow path that applies comprehensive noise filtering. The system dynamically selects which path to use based on noise detection, thereby avoiding the delay caused by always applying filters while still achieving accurate coordinate detection when needed.
Solution Approach 2:
The patent implements dynamic signal processing by continuously monitoring noise levels and adaptively switching between different processing modes. When noise is detected during display updates, the system activates filtered processing; otherwise, it uses real-time unfiltered processing. This dynamic adaptation resolves the contradiction between noise reduction and response speed.
2Reliability
If complex filtering algorithms are used to obtain coordinates, then noise is reduced, but processing complexity increases
Solution Approach 1:
The patent applies filtering selectively rather than universally - only to touch signals received during display update periods when noise is present. For all other times, simple real-time processing is used. This partial application of complex algorithms reduces overall processing complexity while maintaining reliability when needed.
Solution Approach 2:
The patent extracts and isolates the noisy time periods (display update moments) from the overall signal processing stream. By identifying these specific intervals through timing information and applying filtering only to signals received during these periods, the system avoids the complexity of applying complex algorithms to all signals while still achieving noise reduction where necessary.
3Speed
If touch signals are processed in real-time, then response speed is improved, but noise interference increases
Solution Approach 1:
The patent introduces timing information and noise detection mechanisms as intermediary elements between the touch signal input and coordinate generation output. These intermediaries analyze the signal conditions and automatically route signals through appropriate processing paths, enabling real-time processing of clean signals while filtering noisy signals without manual intervention.
Solution Approach 2:
The system uses feedback from noise detection circuits and timing information to continuously monitor signal quality. This feedback loop enables the system to automatically adjust its processing approach - switching between real-time and filtered processing based on current noise conditions, thereby maintaining both speed and reliability dynamically.
Data Source
AI summary
A display device includes a display panel, a noise detection circuit and a processing circuit. The display panel has a touch control function and is configured to detect a contact location of an object to output a touch signal. The noise detection circuit is configured to detect and process a voltage signal of a common electrode of the display panel to output a free run signal and a noise sync signal. The processing circuit is configured to receive the free run signal and the noise sync signal. When the free run signal is at a first level, the processing circuit receives the touch signal in real-time. When the free run signal is at a second level different to the first level, the processing circuit receives the touch signal according to the noise sync signal. The present disclosure also provides a control method for the display device.