Position Detection Apparatus Signal Interference Reduction
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Solution Overview
Problem
The combination of electromagnetic and capacitive position detection systems in touch panels often results in interference between transmission signals, leading to deterioration of detection performance when used simultaneously, affecting the accuracy of pen and finger position detection.
Innovation Solution
The solution involves selecting position information of transmission conductors in one system to optimize the spatial distance and frequency relationship between transmission and reception conductors in both systems, thereby reducing signal interference and maintaining stable detection performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If electromagnetic and capacitive position detection systems are combined and operated simultaneously, then the position detection apparatus can detect both pen and finger pointers, but the transmission signal of one system interferes with the other system causing deterioration of detection performance
Solution Approach 1:
The patent implements periodic switching between electromagnetic and capacitive detection modes, where each system operates in alternating time intervals. The control unit switches the electromagnetic detection section and capacitive detection section on and off in a periodic manner, allowing one system to operate while the other is inactive, thereby eliminating mutual signal interference while maintaining the ability to detect both pen and finger pointers.
Solution Approach 2:
The patent dynamically adjusts the operational state of each detection system based on real-time detection needs. The control unit determines which system should be active at any given moment and switches between electromagnetic and capacitive modes dynamically, optimizing detection performance while preventing signal interference between the two systems.
2Adaptability or versatility
If both position detection systems operate simultaneously, then comprehensive pointer detection is achieved, but signal interference occurs leading to unstable detection performance
Solution Approach 1:
The control unit implements periodic switching between electromagnetic and capacitive detection systems, ensuring that only one system operates at any given time. This periodic operation pattern eliminates continuous signal interference while maintaining the functional capability to detect both pen and finger pointers, thereby stabilizing detection performance.
Solution Approach 2:
The patent extracts the interfering transmission signals from the simultaneous operation by separating the operational time intervals of each system. The control unit isolates the electromagnetic transmission signal and capacitive transmission signal in different time periods, removing the harmful interference effect while preserving the essential detection functions of both systems.
3Measurement precision
If the electromagnetic system generates alternating magnetic field for pen detection, then pen position can be detected, but the magnetic field acts as noise on the capacitive detection section
Solution Approach 1:
The control unit implements periodic switching where the electromagnetic system operates during designated time intervals to generate alternating magnetic fields for pen detection, while the capacitive system operates during separate time intervals. This periodic separation ensures that the magnetic field is generated only when needed for pen detection and is turned off during capacitive detection, eliminating the harmful noise effect on the capacitive system.
Solution Approach 2:
The electromagnetic transmission is performed in brief, intensive pulses rather than continuous operation. The control unit rushes through the electromagnetic signal transmission in short intervals, completing the pen detection function quickly while minimizing the duration of magnetic field generation, thereby reducing the opportunity for interference with the capacitive detection system.
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 suppresses signal noise between the systems, ensuring stable and accurate position detection for both pen and finger inputs, enhancing overall performance.
Implementation Method 1
the pointer position detection section of the electromagnetic system generates an alternating magnetic field having a predetermined frequency in order to cause a resonance circuit, which is incorporated in a pen as a position pointer, to resonate
Implementation Method 2
a capacitive system wherein position detection is carried out based on a variation of the capacitance between sensor conductors
Data Source
AI summary
A position detection apparatus is provided, which includes a plurality of position detection systems such as an electromagnetic-type position detection system and a capacitive-type position detection system. The apparatus is configured to select a transmission conductor among a plurality of transmission conductors in a first position detection system, and to select a reception conductor among a plurality of reception conductors in a second position detection system, so as to increase the spatial distance between the selected transmission conductor in the first position detection system and the selected reception conductor in the second position detection system as much as possible, to thereby reduce interference. Further, a relationship of frequency interleave may be provided between a transmission signal to be supplied to the transmission conductor in the first position detection system and another transmission signal to be supplied to the transmission conductor in the second position detection system.