• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.5
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• pp.327-333
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• 2011

Intelligent robots are widely needed in various areas of industry from extremely dangerous environments to service tasks. For autonomous mobile robots, it is significant to move itself safely to a destination point, recognizing its surroundings. Advances in sensor technology and its applications are achieved in order to develop an intelligent robot. In this paper, a mobile robot with a path-finding algorithm is presented. The path-finding algorithm is the one that does not only find a path to designated destination and also recognizes obstacles on the way, calculating its distance. 10 ultrasonic sensor are mounted on the front and rear of the mobile robot to figure out its position. Specular reflection and wide viewing angle, which are inherent characteristics of ultrasonic waves, cause errors in measuring distance.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.281-285
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• 2006

Recently LG.Philips LCD (hereafter "LPL") has announced the development of the world's largest 100-inch TFT-LCD with Advanced Super IPS technology. This magnificent LCD achieves the feature of a full high definition resolution $1920{\times}1080(16:9)$, 600nit brightness, 3000:1 dynamic contrast ratio, 92% color gamut, 180 degree viewing angle, and 5msec response time at all grays, targeted for HDTV and public display applications. Some unique technologies such as Cu bus line, advanced wide view polarizer, and high color gamut lamp were applied. A new stitching free technology was developed to overcome the size limitation of photo mask in both the TFT and CF processes. The size of the panel (100-inch) based on the wide format (16:9) is determined by the maximum efficiency of world's $1^{st}$ seventh generation line (glass size:$1950{\times}2250mm$) in LPL's Paju display cluster. In this paper, we will discuss the issues of 100-inch TFT-LCD.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.844-847
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• 2003

Display devices are becoming increasingly important as an interface between humans and machines in the growing information society. In display devices, PDP (Plasma Display Panel) has many advantages in that it has wide screen, wide viewing angle and is light weight, thin. In PDP driving method, if the brightness of input image is high, applying the fixed sustain pulse to the PDP panel will raise the PDP power consumption and may damages the PDP panel. To overcome these problems, the Plasma AI driving method was introduced by the Matshushita co. in Japan. The Plasma AI driving module calculates the peak value and average value of 1 frame image and adjusts the gradation and sustain pulses for 1 frame sustain. In this paper, the proposed PDP driving module is based on the Plasma AI driving module. The proposed driving module calculates peak value and average value, and the brightness distribution of 1 frame image. Using brightness distribution, the proposed driving module divides 1 frame input image into 15 image patterns. For each image pattern, minimum sustain pulses and sub-frames are used for the brightness of 1 frame image and the sustain weight for 64, 128, 192 gradation is proposed. Therefore, the sustain power consumption can be reduced.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.831-833
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• 2004

A novel transflective-type LC mode with good display performance has been developed In order to drive both transmissive and reflective modes simultaneously without any modulation of gamma in a single-gap structure, we have introduced a new design concept in the reflective region, where the capacitance is separated into liquid crystal($C_{LC}$} and organic layer($C_{OL}$), playing a key role as a voltage divider in our cap-divided VA-mode. With this cap-divided method having both merits of simplifying process and good legibility, we have achieved good optical characteristics such as high contrast ratio and wide viewing angle in a single-gap homeotropic panel design.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1049-1052
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• 2004

In general, contrary to the CRTs with impulsive emission, liquid crystal displays have motion artifacts such as blurring. ghost image, decrease of dynamic CR(contrast ratio), and stroboscopic motion due to hold type driving method. In this paper, to improve motion picture quality of LCDs. impulsive driving method of black data insertion was applied to the OCB mode which is well known for its fast LC response time and wide viewing angle properties. Subject evaluation was carried out with CRT, TN, SIPS(Super IPS). and impulsive driving OCB. Moving picture image quality near CRT was obtained in impulsive OCB driving mode

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.8
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• pp.724-728
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• 2005

Electro-optic characteristics of reflective hybrid aligned liquid crystal (LC) cell driven by fringe field using a nematic LC with positive dielectric anisotropy have been studied. Optimized optical configurations are achieved by using a single polarizer, half-wave film and a cell with quarter-wave retardation. The simulation results shows an optimum cell retardation of $0.30{\mu}m$. This value may allow a practical cell gap larger than $3{\mu}m$, which makes it easy to control in the manufacturing process. Furthermore, this LC cell with optimized cell parameters shows low wavelength dispersion and the contrast ratio greater than 5 over exists about $100{\circ}$ in vertical direction and $160{\circ}$ in horizontal direction. Also, when using the LC with positive dielectric anisotropy rather than negative dielectric anisotropy, the display shows low power consumption and fast response time.

• Journal of Power Electronics
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• v.7 no.4
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• pp.278-285
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• 2007

Recently, plasma display panels (PDP) have become the most promising candidate in the market for large screen size flat panel displays. PDPs have many merits such as a fast display response time and wide viewing angle. However, there are still concerns about high cost because they require complex driving circuits composed of high power switching devices to generate various voltage waveforms for three operational modes of reset, scan, and sustain. Conventional PDP driving circuits use path switches for voltage separation and a scan switch to offer a scan voltage for reset and scan operations, respectively. In addition, there exist reset switches to initialize PDPs by regulating the wall charge conditions with ramp shaped pulses, which means the necessity of specific power devices for the reset operation. Because power for the plasma discharge accompanied by a large current is transferred to a panel via path switches, high power rating switches are used for path switches. Therefore, this paper proposes a novel low-cost PDP driving scheme achieved by not only eliminating path switches but also merging the function of reset switches into other switches used for sustain or scan operations. The simulated voltage waveforms of the proposed topology and experimental results implemented in a 42-inch panel to demonstrate the validity of using a new gate driver that merges the functions of power switches are presented.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.8
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• pp.871-874
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• 2004

In recent, it is said that the trend of LCD is direction to pursue high qualities like as high transmittance, high contrast ratio, wide viewing angle, fast response time, and so on. Especially, it is known that these qualities are essential to large size LCD like as LCD TV and we can realize them through to uniform cell gap and deep black state. Until now, the ball spacer has been used to control of uniform cell gap. However, the existence of ball spacer inside the cell causes the deformation of the liquid crystal molecules and damage to alignment layer. Such a deformation of the liquid crystal causes light-leakage in the dark state, which lowers contrast ratio of the display. Nowadays, this problem has been solved by using Patterned Spacer on Color Filter. but Side Effect just as gravity mura has been induced. In this paper, we studied the mechanism on gravity mura in case of using patterned spacer on color filter.

• Journal of Information Display
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• v.10 no.4
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• pp.175-179
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• 2009

As the physical properties of nematic liquid crystals vary with respect to temperature, the performances of liquid crystal displays (LCDs) are highly dependent on temperature. Additionally, it is well known that the electro-optic characteristics of LCDs, such as transmittance and threshold voltage, also rely on the LCD switching modes. The temperature dependence of the electro-optic characteristics of the wide-viewing-angle LCD modes, such as in-plane switching (IPS), multidomain vertical alignment by patterned electrode (PVA), and fringe-field switching (FFS), have been studied, and the results showed that the FFS mode has lower temperature dependence compared to the IPS and PVA modes. Since the liquid crystal (LC) reorients in different ways in each mode, this result is associated with the temperature dependence of LC's bend and twist elastic constants, and also with the position of the main reorientation, either in the middle or on the surface of the LC layer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.10
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• pp.914-922
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• 2003

The FFS (fringe-field switching) mode was known to exhibit both a wide viewing angle and high transmittance, especially when using a liquid crystal with negative dielectric anisotropy. We have studied cell gap-dependent electrode-optic characteristics of the FFS mode using the LC with negative dielectric anisotropy. In case of a small cell gap of 2 ${\mu}$m, the transmittance at the center of pixel and common electrodes is relatively low because effect of surface anchoring that holds the LC to the initial state is larger than that in a large cell gap of 4 .urn such that the LCs in those regions cannot rotate enough. However, in case of a large cell gap of 4 .urn, the effect of surface anchoring becomes relatively small so that the LCs at the center of pixel and common electrode can be twisted enough by applied voltage, giving rise to high transmittance. Therefore, we can conclude that the light efficiency is dependent on the cell gap.