• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.6
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• pp.1069-1074
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• 2022

In this study, we prepared ITO thin films on the Nb₂O₅/SiO₂ double buffer layer and investigated electrical and optical properties according to the change of SiO₂ buffer layer thickness (40~50nm). The ITO thin film fabricated on the Nb₂O₅/SiO₂ double buffer layer exhibited a broad surface roughness with a small value ranging of 0.815 to 1.181nm, and the sheet resistance was 99.3 to 134.0Ω/sq. It seems that there is no problem in applying the ITO thin film to a capacitive touch screen panel. In particular, the average transmittance in the short-wavelength (400~500nm) region and the chromaticity (b^*) of the ITO thin film deposited on the Nb₂O₅(10nm)/SiO₂(40nm) double buffer layer showed significantly improved results as 83.58% and 0.05, respectively, compared to 74.46% and 4.28 of ITO thin film without double buffer layer. As a result, it was confirmed that optical properties such as transmittance in the short-wavelength region and chromaticity were remarkably improved due to the index matching effect in the ITO thin film with the Nb₂O₅/SiO₂ double buffer layer.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.3
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• pp.1-12
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• 2011

Large-sized multi-touch screen is usually made using infrared rays. That is because it has technical constraints or cost problems to make the screen with the other ways using such as existing resistive overlays, capacitive overlay, or acoustic wave. Using infrared rays to make multi-touch screen is easy, but is likely to have technical limits to be implemented. To make up for these technical problems, two other methods were suggested through Surface project, which is a next generation user-interface concept of Microsoft. One is Frustrated Total Internal Reflection (FTIR) which uses infrared cameras, the other is Diffuse Illumination (DI). FTIR and DI are easy to be implemented in large screens and are not influenced by the number of touch points. Although FTIR method has an advantage in detecting touch-points, it also has lots of disadvantages such as screen size limit, quality of the materials, the module for infrared LED arrays, and high consuming power. On the other hand, DI method has difficulty in detecting touch-points because of it's structural problems but makes it possible to solve the problem of FTIR. In this thesis, we study the algorithms for effectively correcting the distort phenomenon of optical lens, and image processing algorithms in order to solve the touch detecting problem of the original DI method. Moreover, we suggest calibration algorithms for improving the accuracy of multi-touch, and a new tracking technique for accurate movement and gesture of the touch device. To verify our approaches, we implemented a table-based multi touch screen.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.175-175
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• 2015

산화물과 금속을 적용한 하이브리드 투명전극 저항은 ITO보다 10배 낮은 전기저항 값을 얻었고, 투과도, Haze, $b^*$, 반사율 등 광학 특성도 매우 우수한 값을 얻었으며, 이 하이브리드 투명전극을 적용하여 TSP 모듈 10"를 구현하였다.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.4
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• pp.62-70
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• 2015

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.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.2
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• pp.68-76
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• 2010

Touch-enabled technology is increasingly being accepted as a main communication interface between human and computers. However, conventional touchscreen technologies, such as resistive overlay, capacitive overlay, and SAW(Surface Acoustic Wave), are not cost-effective for large screens. As an alternative to the conventional methods, we introduce a newly emerging method, an optical imaging touchscreen which is much simpler and more cost-effective. Despite its attractive benefits, optical imaging touchscreen has to overcome some problems, such as heavy computational complexity, intermittent ghost points, and over-sensitivity, to be commercially used. Therefore, we designed a hardware controller for signal processing and multi-coordinate computation, and proposed Infrared-blocked DA(Dark Area) manipulation as a solution. While the entire optical touch control took 34ms with a 32-bit microprocessor, the designed hardware controller can manage 2 valid coordinates at 200fps and also reduce energy consumption of infrared diodes from 1.8Wh to 0.0072Wh.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.5
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• pp.423-432
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• 2023

With the increasing demand for mobile devices featuring multi-touch operation, extensive research is being conducted on touch screen panel (TSP) Readout ICs (ROICs) that should possess low power consumption, compact chip size, and immunity to external noise. Therefore, this paper discusses capacitive touch sensors and their readout circuits, and it introduces research trends in various circuit designs that are robust against external noise sources. The recent state-of-the-art TSP ROICs have primarily focused on minimizing the impact of parasitic capacitance (Cp) caused by thin panel thickness. The large Cp can be effectively compensated using an area-efficient current compensator and Current Conveyor (CC), while a display noise reduction scheme utilizing a noise-antenna (NA) electrode significantly improves the signal-to-noise ratio (SNR). Based on these achievements, it is expected that future TSP ROICs will be capable of stable operation with thinner and flexible Touch Screen Panels (TSPs).

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.678-683
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• 2006

A novel and intuitive way of accessing applications of mobile devices is presented. The key idea is to use grip-pattern, which is naturally produced when a user tries to use the mobile device, as a clue to determine an application to be launched. To this end, a capacitive touch sensor system is carefully designed and installed underneath the housing of the mobile terminal to capture the image of the user's grip-pattern. The captured data is then recognized by a recognizer with dedicated preprocessing and postprocessing algorithms. The recognition test is performed to validate the feasibility of the proposed user interface system.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2005.11a
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• pp.245-248
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• 2005

This paper presents a novel user interface system which aims at easy controlling of mobile devices. The fundamental concept of the proposed interface is to launch an appropriate function of the device by sensing and recognizing the grip-pattern when the user tries to use the mobile device. To this end, we develop a prototype system which employs capacitive touch sensors covering the housing of the system and a recognition algorithm for offering the appropriate function which suitable for the sensed grip-pattern. The effectiveness and feasibility of the proposed method is evaluated through the test of recognition rate with the collected grip-pattern database.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.217.2-217.2
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• 2014

We prepared a flexible and transparent CuO/Cu/CuO multilayer electrodes on a polyethylene terephthalate (PET) substrate using a specially designed roll-to-roll sputtering system at room temperature for GFF-type touch screen panels (TSPs). By the continuous roll-to-roll sputtering of the CuO and Cu layer, we fabricated a flexible CuO(150nm)/Cu(150nm)/CuO(150nm) multilayer electrodes with a sheet resistance of $0.289{\Omega}/square$, resistivity of $5.991{\times}10^{-23}{\Omega}-cm$, at the optimized condition without breaking the vacuum. To investigate the feasibility of the CuO/Cu/CuO multilayer as a transparent electrode for GFF-type TSPs, we fabricated simple GFF-type TSPs using the diamond patterned CuO/Cu/CuO electrode on PET substrate as function of mesh line width. Using diamond patterned CuO/Cu/CuO electrode of mesh line $5{\mu}m$ with sheet resistance of 38 Ohm/square, optical transmittance of 90% at 550 nm and an average transmittance of 89% at wavelength range from 380 to 780 nm, we successfully demonstrated GFF-type touch panel screens (TPSs). The successful operation of GFF-type TPSs with CuO/Cu/CuO multilayer electrodes indicates that the CuO/Cu/CuO multilayer is a promising transparent electrode for large-area capacitive-type TPSs due to its low sheet resistance and high transparency.

• Journal of the Optical Society of Korea
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• v.19 no.5
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• pp.508-513
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• 2015

A capacitive-type touch screen panel (TSP) composed of silver nanowire (AgNW) crossing electrodes and transparent bridge structures was fabricated on a polycarbonate film. The transparent bridge structure was formed with a stack of Al-doped ZnO (AZO) electrodes and SU-8 insulator. The stable and robust continuity of the bridge electrode over the bridge insulator was achieved by making the side-wall slope of the bridge insulator low and depositing the conformal AZO film with atomic layer deposition. With an extended exposure time of photolithography, the lower part of the SU-8 layer around the region uncovered by the photomask can be exposed enough to the UV light scattered from the substrate. This leads to the low side-wall slope of the bridge insulator. The fabricated TSP sample showed a large capacitance change of 22.71% between with and without touching. Our work supplies the technological clue for ensuring long-term reliability to the highly flexible and transparent TSP made by using conventional fabrication processes.