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Projected capacitive touch screen electromagnetic interference problem solution

Developing mobile handheld devices with touchscreen human-machine interfaces is a complex design challenge, especially for projected capacitive touchscreen design, which represents the mainstream technology for multi-touch interfaces. Projected capacitive touchscreens can accurately locate the position where a finger touches the screen. It determines the finger position by measuring small changes in capacitance. A key design issue to consider in such touchscreen applications is the impact of electromagnetic interference (EMI) on system performance. The performance degradation caused by interference can have an adverse effect on touchscreen designs, and this article will explore and analyze these interference sources.

       Projected capacitive touch screen structure

        ), forming a cross matrix, each Tx-Rx node has a characteristic capacitance. Tx ITOis located belowRx ITOand separated by a layer of polymer film or optical adhesive (OCA. As shown in the figure, the direction of the Tx electrode is from left to right, and the direction of the Rx electrode is from outside the paper to inside the paper.

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