Journal of the Institute of Electronics and Information Engineers (전자공학회논문지)

The Institute of Electronics and Information Engineers (대한전자공학회)
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A Fast Sensing Method using Concurrent Driving and Sequential Sensing for Large Capacitance Touch Screens

동시구동 및 순차센싱을 이용한 대형 정전용량 터치스크린용 고속 센싱 기법

  • Mohamed, Mohamed G.A. (School of Electrical Engineering and Computer Science, Chungbuk National University) ;
  • Kim, HyungWon (School of Electrical Engineering and Computer Science, Chungbuk National University) ;
  • Cho, Tae-Won (School of Electrical Engineering and Computer Science, Chungbuk National University)
  • Received : 2015.02.04
  • Accepted : 2015.03.26
  • Published : 2015.04.25
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Abstract

Recently the demand for projected capacitance touch screens is sharply growing especially for large screens for medical devices, PC monitors and TVs. Large touch screens in general need a controller of higher complexity. They usually have a larger number of driving and sensing lines, and hence it takes longer to scan one frame for touch detection leading to a low frame scan rate. In this paper, a novel touch screen control technique is presented, which scans each frame in two steps of simultaneous multi-channel driving. The first step is to drive all driving lines simultaneously and determine which sensing lines have any touch. The second step is to sequentially rescan only the touched sensing lines, and determine exact positions of the touches. This technique can substantially increase the frame scan rate. This technique has been implemented using an FPGA and an AFE board, and tested using a commercial 23-inch touch screen panel. Experimental results show that the proposed technique improves the frame scan rate by 8.4 times for the 23-inch touch screen panel over conventional methods.

최근 스마트폰의 발달과 더불어 대형 TV, 의료용 장비 및 전자 칠판에도 터치스크린의 수요가 급증하고 있다. 스크린 사이즈가 증가 할수록 고해상도를 위하여 훨씬 더 많은 채널이 추가 되면서 한 프레임을 스캔하는데 긴 시간이 소요되어 터치감지 지연이 큰 문제가 되고 있다. 본 논문에서는 이러한 문제를 해결하기 위하여 새로운 드라이빙 및 센싱 기법을 제안한다. 이 기법은 differential 드라이빙 방법으로 2 단계로 수행되어진다. 먼저 고속 센싱 프로세스를 통해 터치가 발생된 센싱 라인들을 우선 대략적으로 도출해 낸 후 정확한 터치 위치 스캔을 위해서 터치된 라인에서만 감지가 수행되어 진다. 이 방법을 사용하면 터치 패널의 frame refresh rate를 향상 시킬 수 있다. 제안된 구조는 FPGA와 개발된 AFE board로 구현되었으며, 23인치 상용 터치패널을 사용하여 테스트하였다. 이 기법은 기존 대비 frame scan rate를 8.4배 향상시킨다.

Keywords

References

  1. G. Barrett and R. Omote, "Projected-Capacitive Touch Technology," Information Display, Vol. 26, No. 3, pp. 16-21, March 2010.
  2. K. Lim, K. S. Jung, C. S. Jang, J. S. Baek, and I. B. Kang, "A Fast and Energy Efficient Single-Chip Touch Controller for Tablet Touch Applications," Journal of Display Technology, Vol. 9, no. 7, pp. 520-526, July 2013. https://doi.org/10.1109/JDT.2013.2243900
  3. S. M. Kim, H. Cho, M. Nam, S. G. Choi, and K. Cho, "Low-Power Touch-Sensing Circuit with Reduced Scanning Algorithm for Touch Screen Panels on Mobile Devices," Journal of Display Technology, Vol. 11, no. 1, pp. 36-43, Jan. 2015. https://doi.org/10.1109/JDT.2014.2359680
  4. Y. H. Tai, H. L. Chiu, and L. S. Chou, "Large-Area Capacitive Active Touch Panel Using the Method of Pulse Overlapping Detection," Journal of Display Technology, Vol. 9, no. 3, pp. 170-175, March 2013. https://doi.org/10.1109/JDT.2012.2236882
  5. M.G.A. Mohamed. H. W. Kim, and T. W. Cho, "Efficient Multi-Touch Detection Algorithm for Large Touch Screen Panels," IEIE Transactions on Smart Processing and Computing, Vol. 3, no. 4, pp. 246-250, August 2014. https://doi.org/10.5573/IEIESPC.2014.3.4.246
  6. I. Seo, U. Jang, M.G.A. Mohamed, T. W. Cho, H. W. Kim, H. K. Chang and S. Lee. "Voltage Shifting Double Integration Circuit for High Sensing Resolution of Large Capacitive Touch Screen Panels," in Proc. of The 18th IEEE International Symposium on Consumer Electronics (ISCE), Jeju, Korea, June 2014.
  7. I. S. Yang, and O. K. Kwon, "A touch controller using differential sensing method for on-cell capacitive touch screen panel systems," IEEE Transactions on Consumer Electronics, Vol. 57, no. 3, pp. 1027-1032, 2011. https://doi.org/10.1109/TCE.2011.6018851
  8. J. H. Yang, S. H. Park, J. Y. Jeon, H. S. Kim, C. B. Park, J. C. Lee, J. W. Kim and G. H. Cho, "A High-SNR Area-Efficient Readout Circuit using a Delta-Integration Method for Capacitive Touch Screen Panels," in Proc. of SID Symposium Digest of Technical Papers, Vol. 43, No. 1, pp. 1570-1573, June 2012.
  9. K. D. Kim, S. H. Byun, Y. K. Choi, et al., "A capacitive touch controller robust to display noise for ultrathin touch screen displays," in Proc. of IEEE International Solid-State Circuits Conference Digest of Technical Papers (ISSCC), pp. 116-117, San Francisco, USA, Feb. 2012.
  10. H. Shin, S. Ko, H. Jang, I. Yun, and K. Lee, "A 55dB SNR with 240Hz frame scan rate mutual capacitor 30${\times}$24 touch-screen panel read-out IC using code-division multiple sensing technique," in Proc. of IEEE International Solid-State Circuits Conference Digest of Technical Papers (ISSCC), pp. 388-389, San Francisco, USA, Feb. 2013.
  11. M.G.A. Mohamed, U. Jang., I. Seo., H. W. Kim, T. W. Cho, H. K. Chang and S. Lee. "Efficient algorithm for accurate touch detection of large touch screen panels," in Proc. of The 18th IEEE International Symposium on Consumer Electronics (ISCE), Jeju, Korea, June 2014.
  12. H. Ma, S. Heo, J. J. Kim and F. Bien, "Algorithm for improving SNR using high voltage and differential Manchester code for capacitive touch screen panel," Electronics Letters, Vol. 50, no. 24, pp. 1813-1815, Dec. 2014. https://doi.org/10.1049/el.2014.2269
  13. G. Choi, M.G.A. Mohamed, and H. W. Kim, "Distributed Architecture of Touch Screen Controller SoC for Large Touch Screen Panels," in Proc. of International SoC Design Conference, Jeju, Korea, Nov. 2014.
  14. I. Seo, T. W. Cho, H. W. Kim, H. G. Jang, S. W. Lee, "Frequency Domain Concurrent Sensing Technique for Large Touch Screen Panels", in Proc. of IEEK Fall Conference 2013, Seoul, Korea, pp.55-58, Korea Univ, Nov. 2013.
  15. U. Y. Jang, H. W. Kim, T. W. Cho, H. G. Jang, S. W. Lee, "Architecture of Multi Purpose Touch Screen Controller with Self Calibration Scheme", in Proc. of IEEK Fall Conference 2013, Seoul, Korea, pp.162-166, Nov. 2013.

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  2. Touch Position Recovery Algorithm for Differential Sensing Touch Screen vol.14, pp.2, 2016, https://doi.org/10.6109/jicce.2016.14.2.106