Touch Screen Interference Reduction via Periodic Electrode Sampling
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Solution Overview
Problem
Touch screens face interference from pixel refreshing, which affects touch sensitive detection due to the limited number of electrodes and the timing of signal transmission, leading to potential brightness abnormalities and prolonged detection times.
Innovation Solution
A method involving multiple detections by sensing electrodes at intervals to generate detection values, with sums calculated to determine the position of an external conductive object, allowing for exclusion of irrelevant signals and reducing electromagnetic interference from pixel refreshing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple detections are performed at time intervals to reduce electromagnetic interference from pixel refreshing, then touch detection accuracy is improved, but detection time is prolonged
Solution Approach 1:
The patent implements periodic detection by performing multiple detections at specific time intervals (e.g., first, second, and third detections separated by time intervals corresponding to pixel refresh cycles). This periodic sampling allows the system to capture touch signal characteristics while avoiding electromagnetic interference from pixel refreshing, thereby improving detection accuracy without requiring continuous monitoring that would excessively prolong detection time.
Solution Approach 2:
The system performs preliminary detections before final touch determination to identify and exclude interference signals. By conducting initial detections at time intervals and comparing results, the system can preliminarily identify which detection results are affected by pixel refreshing interference and exclude them before making the final touch detection decision, thus improving accuracy while controlling overall detection time.
2Measurement precision
If the number of sensing electrodes is increased to improve touch detection coverage, then detection precision is improved, but device complexity increases
Solution Approach 1:
The patent makes the existing sensing electrodes serve multiple functions by utilizing them for both normal touch detection and interference signal identification through temporal sampling. The same electrodes are used across multiple detection cycles at different time intervals, allowing the system to distinguish between valid touch signals and pixel refresh interference without requiring additional dedicated electrodes for interference cancellation, thus maintaining detection precision while avoiding increased device complexity.
Solution Approach 2:
The sensing electrodes perform self-identification of their signal quality by comparing detection results across multiple time intervals. The system uses the electrodes' own response patterns over time to automatically identify which detection results are affected by interference and exclude them, eliminating the need for additional reference electrodes or complex external calibration systems.
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 approach effectively reduces electromagnetic interference and improves touch sensitive detection accuracy by distinguishing relevant from irrelevant signals, enhancing the precision and speed of touch detection.
Implementation Method 1
performing a first detection via multiple sensing electrodes of a touch screen to generate multiple first detection values
Implementation Method 2
every pixel of a modern liquid crystal display (LCD) has a corresponding pixel electrode used to twist polarity of liquid crystal, thereby changing transmittance of the liquid crystal of the pixel
Data Source
AI summary
A touch sensitive method for reducing interference from pixel refreshing: comprising: performing three detections, each separated by a time interval, via multiple sensing electrodes of a touch screen to generate multiple first detection values, second detection values and third detection values, respectively; adding detection values with respect to the multiple sensing electrodes up as multiple sums of detection values; determining that an external conductive object is approximating or touching the touch screen nearby a N-th sensing electrode according to the multiple sums; and determining a position of the object locates according to one of the first detection values, the second detection values and the third detection values.