Touch Signal Detection Circuit Interference Reduction
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Solution Overview
Problem
Current touch devices experience decreased detection precision and potential erroneous detection due to interference from liquid crystal display (LCD) electromagnetic signals during touch location detection.
Innovation Solution
The touch signal detection circuit design features transmitting and receiving electrodes perpendicular to each other, with the receiving electrode positioned perpendicular to the source driver line of the display screen, allowing for the subtraction of interfering signals and improved precision in touch location detection by a processing unit analyzing capacitance change values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a touch device uses LCD display to show electromagnetic signals, then the display function is achieved, but interference occurs in touch detection leading to decreased detection precision
Solution Approach 1:
The patent extracts the interfering electromagnetic signal from the LCD display and separates it from the touch detection signal. By identifying the characteristic frequency of the display interference and using band-stop filtering or signal subtraction techniques, the harmful electromagnetic interference is removed while preserving the touch detection capability.
Solution Approach 2:
The patent introduces an intermediary signal processing stage between the touch electrode and the detection circuit. This intermediary includes reference signal generation from the display driver and adaptive filtering mechanisms that mediate between the displayed content and the touch detection, allowing the system to compensate for interference in real-time.
2Ease of operation
If the touch device performs touch detection using mutual capacitance induction, then touch location detection is enabled, but interference from display electromagnetic signals causes erroneous detection or detection failure
Solution Approach 1:
The patent implements a feedback mechanism where the display driver provides reference signal information to the touch detection circuit. The system continuously monitors the electromagnetic interference generated by the display and adjusts the touch detection algorithm in real-time based on this feedback, enabling dynamic compensation for interference conditions.
Solution Approach 2:
The patent performs preliminary characterization of the display electromagnetic interference pattern during the initialization phase or in advance of touch detection. By pre-measuring and storing the interference signature from different display content, the system can prepare compensation parameters before actual touch detection occurs, improving reliability during critical detection moments.
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 design effectively reduces interference from display screen driving, enhancing the accuracy of touch location detection and preventing detection failures.
Implementation Method 1
A node formed between each transmitting electrode and each receiving electrode may be equivalent to one node mutual capacitance. When a user touches the touch device, a change in a node capacitance occurs at a touch point.
Implementation Method 2
When a liquid crystal display (Liquid Crystal Display, LCD for short) performs displaying a generated electromagnetic signal may cause interference to touch detection of the touch device
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5A
AI summary
Embodiments of the present invention provide a touch signal detection circuit and method, and a touch device. The touch signal detection circuit includes: a processing unit, at least one linear transmitting electrode, and at least two linear receiving electrodes; the transmitting electrode is perpendicular to the receiving electrode, the receiving electrode is perpendicular to a source driver line of a display screen, and each receiving electrode and each transmitting electrode form one node mutual capacitance; the processing unit acquires capacitance change values of at least two node mutual capacitances, and acquires a location of a touch signal according to the capacitance change values of the at least two node mutual capacitances. In technical solutions provided in the present invention, the transmitting electrode is perpendicular to the receiving electrode, the receiving electrode is perpendicular to the source driver line of the display screen, and then the location of the touch signal is acquired according to the capacitance change values, which are acquired by the processing unit, of the at least two node mutual capacitances. This can determine and reduce interference in touch signal detection caused by display screen scanning, thereby improving precision of touch location detection and a capability of resisting the interference from the display screen.