• 전자공학회논문지 IE
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• v.46 no.4
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• pp.57-65
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• 2009

This paper presents the image contrast enhancement technique suitable for local dimming backlight of small-sized mobile display while achieving the reduction of the power consumption. In addition to the large-sized TFT-LCD, small-sized one has adopted LED for backlight. Since, conventionally, LED was mounted on the side edge of a display panel, global dimming method has been widely used. However, recently, new advanced method of local dimming by placing the LED to the backside of the display panel and it raised the necessity of sub-blocked processing after partitioning the target image. When the sub-blocked image has low brightness, the supply current of a backlight LED is reduced, which gives both enhancement of contrast ratio and power consumption reduction. In this paper, we propose simple and improved image enhancement algorithm suitable for the small-sized mobile display. After partitioning the input image by equal sized blocks and analyzing the pixel information in each block, we realize the primary contrast enhancement by independently processing the sub-blocks using the information such as histogram, mean, and standard deviation values of luminance(Y) component. And then resulting information is transferred to each backlight control unit for local dimming to realize the secondary contrast enhancement as well as reduction of power consumption.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.167.2-167.2
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• 2015

고 이동도(~10 cm/Vs), 낮은 공정온도 및 높은 투과율 등의 특성을 갖는 산화물 반도체는 저 소비전력, 대면적화 및 고해상도 LCD Panel에 적합한 재료로서 현재 일부 Mobile Panel 및 TFT-LCD Panel의 양산에 적용되고 있으나, 향후 UHD급(4 K, 8 K)의 대형, 고해상도 Panel에의 적용을 위해서는 30 cm2/Vs 이상의 고 이동도 재료의 개발 및 저 저항 배선의 적용에 따른 소자 신뢰성의 개선이 필요하다. Cu는 대표적인 저 저항 배선 재료로 일부 양산에 적용되고 있으나, Cu 전극과 산화물 반도체의 계면에서 Cu원자의 확산 및 Cu-O 층의 형성에 의한 소자 특성 저하의 문제가 있다. 본 연구에서는 고 이동도의 In doped-ZTO계 산화물 반도체를 기반으로 채널 층과 Cu source-Drain layer의 계면에서의 Cu element의 거동 및 TFT 소자 특성과의 상관관계를 고찰하고, 계면에 형성된 Cu-O layer에 대해 높은 전자 친화도를 갖는 Ca element를 첨가에 의한 TFT 소자 특성의 변화를 관찰하였다. 본 연구에서는 이러한 효과로 인한 소자 신뢰성의 향상을 기대하였으며, 우선 In doped-ZTO 채널 층에 Cu와 CuCa 2at% source-drain을 적용한 TFT 특성을 확인하였다. 그 결과, Cu는 Field-effect mobility: ~17.67 cm2/Vs, Sub-threshold swing: 0.76 mV/decade 및 Vth:, 4.40 V의 결과가 얻어졌으며 CuCa 2at%의 경우 Field-effect mobility: ~17.84 cm2/Vs, Sub-threshold swing: 0.86 mV/decade 및 Vth:, 5.74 V의 결과가 얻어졌다. 소자신뢰성 측면에서도 Bias Stress의 변화량 ${\delta}Vth$의 경우 Cu : 4.48 V에 대해 CuCa 2at% : 2.81 V로 ${\delta}Vth$:1.67 V의 개선된 결과를 얻었다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.9
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• pp.2023-2030
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• 2010

In this paper, we present research results of developing high performance scan conversion unit and implementing it on FPGA chip. To increase performance of scan conversion unit, we propose an architecture of scan converter that is a SIMD architecture and uses tile-based traversing method. The proposed scan conversion unit can operate about 124Mhz clock frequency on Xilinx Vertex4 LX100 device. To verify the scan conversion unit, we also develop shader unit, texture mapping unit and $240{\times}320$ color TFT-LCD controller to display outputs of the scan conversion unit on TFT-LCD. Because the scan conversion unit implemented on FPGA has 311Mpixels/sec pixel rate, it is applicable to desktop pc's 3d graphics system as well as mobile 3d graphics system needing high pixel rates.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.409-412
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• 2007

A lot of research for system-on-panel(SOP) have been done to integrate display systems including data driver, gate driver, timing controller, DC-DC converter, and smart functions such as embedded touch screen, ambient brightness sensing and luminance control, finger printing on the glass. Recently, the cost of an one-chip driver IC with various functions has decreased rapidly, and new mobile display interface technologies have been introduced. So it is necessary to examine the feasibility of SOP for practical mobile applications. In this paper, we will re-examine LTPS technologies for mobile displays in terms of various aspects and discuss the practical limitations on SOP technology and future technology trend of mobile displays.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.1
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• pp.98-106
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• 2009

This work proposes a 1280-RGB $\times$ 800-Dot 70.78mW 0.l3um CMOS LCD driver IC (LDI) for high-performance 16M-color low temperature poly silicon (LTPS) thin film transistor liquid crystal display (TFT-LCD) systems such as ultra mobile PC (UMPC) and mobile applications simultaneously requiring high resolution, low power, and small size at high speed. The proposed LDI optimizes power consumption and chip area at high resolution based on a resistor-string based architecture. The single column driver employing a 1:12 MUX architecture drives 12 channels simultaneously to minimize chip area. The implemented class-AB amplifier achieves a rail-to-rail operation with high gain and low power while minimizing the effect of offset and output deviations for high definition. The supply- and temperature-insensitive current reference is implemented on chip with a small number of MOS transistors. A slew enhancement technique applicable to next-generation source drivers, not implemented on this prototype chip, is proposed to reduce power consumption further. The prototype LDI implemented in a 0.13um CMOS technology demonstrates a measured settling time of source driver amplifiers within 1.016us and 1.072us during high-to-low and low-to-high transitions, respectively. The output voltage of source drivers shows a maximum deviation of 11mV. The LDI with an active die area of $12,203um{\times}1500um$ consumes 70.78mW at 1.5V/5.5V.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.898-901
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• 2005

We propose a novel pixel structure using bootstrapped voltage programming for amorphoussilicon TFT backplane of AM-OLED (Active Matrix-Organic Light Emitting Diode) displays. The proposed structure is composed of two TFTs and one capacitor. It operates at low drive voltage ($0{\sim}5V$) which can reduce power consumption comparing with the conventional pixel circuit structure using same OLED material. Also, it can easily control dark level and use commercial mobile LCD ICs. In this paper, we describe the operating principle and the characteristics of the proposed pixel structure and verify the performance by SPICE simulation comparing with the conventional pixel structure.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.686-689
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• 2003

This paper describes two kind of new concept for low power consumption for small area TFT-LCDs. First, the proposed analog buffer could reduce the static current by adopting new scheme. Second, new data driver structure reduced DC power consumption by reducing the number of operational amplifier (op-amp). As simulation results of Hspice, the quiescent current of proposed analog buffer is less than $0.8{\mu}A$ and the DC power consumption is reduced about $40{\sim}50%$ compared with conventional ones.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1473-1475
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• 2006

The electro-optic properties of an active-matrix polymer network liquid crystal display (AM-PNLCD) with crossed polarizer films to improve its contrast ratio were evaluated. By using crossed polarizer films, it shows good contrast ratio as well as wide viewing angle and adequate response time at normal TFT-twisted nematic (TN) LCD driving voltage (2.8V).

• Journal of Satellite, Information and Communications
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• v.9 no.1
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• pp.70-73
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• 2014

We have designed high performance flexible prism light-guide plate (LGP) in 5 inch TFT-LCD for mobile applications. We adopted novel material such as methacrylate and butyl acrylate mixture, as it called KURARITY. It has good flexibility by addition of butyl acrylate. And it has also good transmissivity because methacrylate is a major compound. Then, we achieved good test result to embody high brightness and flexible BLU in case of LGP of base and upper surface with 5 inch, thickness 1.5mm adding prism construct, it is superior brightness improvement than previous flexible LGP. It shows significant improvement than previous printing form about some 5% and in this course to flexible embody actual material it succeeded prism LGP production by 5 inch injection form process.

• Journal of the Korean institute of surface engineering
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• v.41 no.1
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• pp.6-11
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• 2008

An Indium Zinc Oxide(IZO) transparent conductive layer was deposited on a large size glass substrate by using magnetron dc sputtering method with varying a deposition temperature. As the deposition temperature decreased to a room temperature, the sheet resistance of IZO film increased. But this deposition temperature range is included in an applicable to a device. From a standpoint of the sheet resistance, the differences of the sheet resistance were not great and the uniformity of the layer was uniformed around 10%. Crystallization particles were shown on the surface of the layer as deposition temperature increased, but these particles were not shown on the surface of the layer as deposition temperature decreased to the room temperature. It didn't make a scrap of difference in a transmittance of varying deposition temperature. Therefore, it is concluded that IZO thin film manufactured by the room temperature deposition condition can be used as a large size transparent conductive layer of a liquid crystal display device.