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고감도 터치스크린 감지를 위한 양방향 센싱과 전압쉬프팅을 이용한 센싱 기법

Dual Sensing with Voltage Shifting Scheme for High Sensitivity Touch Screen Detection

  • Seo, Incheol (School of Electrical Engineering and Computer Science, Chungbuk National University) ;
  • Kim, HyungWon (School of Electrical Engineering and Computer Science, Chungbuk National University)
  • 투고 : 2015.02.04
  • 심사 : 2015.04.01
  • 발행 : 2015.04.25

초록

본 논문에서는 상호 정전용량 터치스크린의 single line sensing 방법에서의 단점을 해결하기 위한 성능향상 구조를 제안한다. 제안 구조는 Dual sensing 기법과 voltage shifting 기법을 도입하여 센싱 신호의 노이즈를 효과적으로 제거하고 터치 유무의 센싱 신호 차이를 증가시킨다. Dual sensing 기법은 구동신호의 양방향 엣지를 사용하여 integration 속도를 2배로 증가시켜 감지시간을 감소시킨다. Voltage shifting은 ADC의 입력신호 동작범위를 최대화하여 신호 대 노이즈비 (SNR)를 개선한다. 23" 대형 상용 터치스크린을 이용하여 simulation 및 측정한 결과로 제안된 센싱기법은 43dB의 SNR 성능을 가지며, 기존 방식 대비 2배의 스캔 속도를 제공하여 대형 터치스크린을 위한 적합한 기술임을 보인다. 제안된 센싱기법은 현재 매그나칩 CMOS 0.18um 공정으로 TSP 컨트롤러칩으로 구현되었다.

This paper proposes a new touch screen sensing method that improves the drawback of conventional single-line sensing methods for mutual capacitance touch screen panels (TSPs). It introduces a dual sensing and voltage shifting method, which reduces the ambient noise effectively and enhances the touch signal strength. The dual sensing scheme reduces the detection time by doubling the integration speed using both edges of excitation pulse signals. The voltage shifting method enhances the signal-to-noise ratio (SNR) by increasing the voltage range of integrations, and maximizing the ADC's input dynamic range. Simulation and experimental results using a commercial 23" large touch screen show an SNR performance of 43dB and a scan rate 2 times faster than conventional schemes - key properties suited for a large touch screen panels. We implemented the proposed method into a TSP controller chip using Magnachip's CMOS 0.18um process.

키워드

참고문헌

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피인용 문헌

  1. Touch Screen Sensing Circuit with Rotating Auto-Zeroing Offset Cancellation vol.13, pp.3, 2015, https://doi.org/10.6109/jicce.2015.13.3.189
  2. Symmetric Signal Reconstruction and Frequency-Division Differential Driving for High Rate Touch Screen Sensing vol.12, pp.11, 2016, https://doi.org/10.1109/JDT.2016.2602244
  3. Touch Position Recovery Algorithm for Differential Sensing Touch Screen vol.14, pp.2, 2016, https://doi.org/10.6109/jicce.2016.14.2.106
  4. Enhancement of touch screen sensing based on voltage shifting differential offset compensation vol.94, pp.2, 2018, https://doi.org/10.1007/s10470-017-1078-0
  5. Concurrent Driving Method with Fast Scan Rate for Large Mutual Capacitance Touch Screens vol.2015, pp.None, 2015, https://doi.org/10.1155/2015/768293