Browsing by Author "Liu, En-Chih"

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Design and implement the readout circuit of an in-cell high-resolution capacitive touch panel
(2017-01-01)
Ku, Tsung-Yen
;
Chao, Paul C. -P.
;
Huang, Chin-Hai
;
Liu, En-Chih
;
Yeh, Ming-Hua
This paper proposes a high resolution capacitive touch panel readout circuit to sense the Variation by self-capacitance method. This AM display of in-cell structure includes an active architecture for improved resolution, that controlling the TFT (Thin-film transistor) to make the accuracy better. In addition, the panel has 60 sensing point per 0.88 inches and the proposed readout circuit used switched capacitor charge amplifier(SCCA) to sensing the charge change and enhances the SNR (Signal-to-noise) by eliminating the baseline. The experimental results show that the proposed readout circuit SNR achieves 38dB and the frame rate is 200Hz.
Design and validation of the readout circuitry for an in-cell active-matrix capacitive (IAMC) touch panel
(2018-11-01)
Ku, Tsung-Yen
;
Chao, Paul C. -P.
;
Tu, Tse-Yi
;
Huang, Chin-Hai
;
Liu, En-Chih
This study is dedicated to design an in-cell active-matrix capacitive (IAMC) touch panel and its readout circuitry. This IAMC touch panel is in a structure that embeds all components for touch panel in a standard active matrix display. In this way, the thickness of the display-touch combined module can be significantly reduced, but introducing much noise from display to touch module, leading to higher mis-judgements on touches. To solve the problem, this study proposes a new readout circuit and digital signal processing techniques to tackle well the aforementioned noise for much accurate touch sensing. The readout consists essentially of an analog front-end switched capacitor charge amplifier (SCCA), a 12-bit SAR ADC and a digital signal processing (DSP) unit for calibration and filtering. A field-programmable gate array (FPGA) board is adopted to implement the designed digital signal processing in practice. The performance of the readout is tested for a 5x12, 0.88-inch IAMC touch panel with a scanning frequency of 200Hz. Experimental data show clearly that the sensed capacitance was successfully converted to 200 digits in a full dynamic range of 12-bits and a SNR of 52dB, which facilitates well accurate determination of touches and locations on an IAMC touch panel.