• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.504-507
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• 2002

We investigated electro-optic and ionic properties of twisted nematic cells by using control of chiral pitch. These properties are observed in practical experiment and simulations. C-V and V-T curve characteristics were obtained from three types of cells with d/p. It is shown that d/p ratio of short cells exhibit faster response time improved by 20% than normal cell. Also, inter-gray response time is improved each rise time and decay time. And, the increase of saturation voltage is happened because of the small twist angel change from initial state at high voltage near 5V. To compensate for longer black level tail, gamma curve index was varied from g = 2.2 to g = 2.7 in module status. Additionally, adding chiral dopant into TN cells improved ionic characteristics such as increasing VHR, Ion density and DC Hysteresis were decreased..

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.609-613
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• 2005

Advanced mobile communication devices require a bright, high information content display in a small, light-weight, low power consumption package. In this paper we will outline our progress towards developing such a low power consumption active-matrix flexible OLED ($FOLED^{TM}$) display. Our work in this area is focused on three critical enabling technologies. The first is the development of a high efficiency long-lived phosphorescent OLED ($PHOLED{TM}$) device technology, which has now proven itself to be capable of meeting the low power consumption performance requirements for mobile display applications. Secondly, is the development of flexible active matrix backplanes, and for this our team are employing poly-Si TFTs formed on metal foil substrates as this approach represents an attractive alternative to fabricating poly-Si TFTs on plastic for the realization of first generation flexible active matrix OLED displays. Unlike most plastics, metal foil substrates can withstand a large thermal load and do not require a moisture and oxygen permeation barrier. Thirdly, the key to reliable operation is to ensure that the organic materials are fully encapsulated in a package designed for repetitive flexing. We also present progress in operational lifetime of encapsulated T-PHOLED pixels on planarized metal foil and discuss PHOLED encapsulation strategy.

• Journal of Information Display
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• v.3 no.3
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• pp.1-11
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• 2002

Multi-view function is important to three-dimensional displays without dedicated glasses. It is the reason that the observers earnestly desire to change their positions freely. Multi-viewing is also principal to the reality of three-dimensional (3D) image displayed on the screen. The display of projection type has the advantage that the number of viewing points can be easily increased according to the number of projectors. The authors research on multi-view projection display with hologram screen. Powerful directionality of the diffracted beam from hologram screen is required unlike two-dimensional (2D) display. We developed a new method that all diffracted beams satisfied the same Bragg condition and became sufficiently bright to observe the 3D image under usual indoor light. The principle is based on the essential Bragg diffraction in the three-dimensional space. Owing to such three-dimensional Bragg diffraction we achieved an excellent hologram screen that could be multiple reconstructed in spite of single recording. This hologram screen is able to answer arbitrary numbers of viewing points within wide viewing zone. The distortion of 3D image becomes also sufficiently small with the method of dividing the cross angle between illumination and diffraction beam.

• Journal of the Institute of Convergence Signal Processing
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• v.12 no.1
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• pp.50-55
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• 2011

In this paper, we propose and demonstrate an effective video advertising method for on-line shopping malls. For the Internet advertising, we make a mouse with a small OLED display that can communicate with PC's Internet network. Without displaying the teasing Pop-ups on the PC's monitor, the advertising for a shopping mall is directly sent to the OLED display on the mouse. Also, the proposed method has merits of sending the advertising based on customer's preference by using IP multicasting, which the customer can select an advertising category in advance. When the customer want to buy an item on the OLED display, the detail advertising can be immediately accessed through a Web browser on PC's monitor by pushing a special button on the mouse.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.2
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• pp.25-31
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• 2009

The image processing methods are widely used in many industrial fields to detect defections in inspection devices. In this study an image processing method was conducted for the detection of abnormal pixels in a OLED(Organic Light Emitting Diode) type panel which is used for small size displays. The display quality of an OLED device is dependent on the pixel formation quality. So, among the so many pixels, to find out the faulty pixels is very important task in manufacturing processing or inspection division. We used a line scanning type BW(Black & White) camera which has very high resolution characteristics to acquire an image of display pixel patterns. And the various faulty cases in pixel abnormal patterns are considered to detect abnormal pixels. From the results of the research, the normal BW pixel image could be restored to its original color pixel.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1642-1645
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• 2007

The brightness of LED changes according to the current flowing through LEDs. The current mirror was used to drive LEDs effectively. The reference current of the current mirror was usually controlled by the resistor but the size of this resistor is very large and this resistor consumes too much power for high power LED backlight driving. The reference current of the current mirror LED driver was controlled by using flyback converter at small size with low power consumption in this paper. The concept of active current source was presented.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.175-178
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• 2008

A new laser-addressing method is proposed in this paper. With the characteristic of high power and small spot size, simple structure electronic paper can be addressed only by laser source, and high quality image with 300dpi resolution can be easily achieved.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.3
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• pp.13-18
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• 2010

This work proposes and characterizes switched-capacitor type cyclic digital-to-analog converter for display data driving. The proposed digital-to-analog converter composes simple structure, and can be implemented for low-power, small area display driver ICs. By circuit level simulations, it is verified that the op-amp input referred offset is attenuated at the DAC output and the circuit performance is robust at 0.5% of capacitor mismatch.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.289-292
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• 2002

A new technique to construct an auto-stereoscopic display that offers massive horizontal parallax images is proposed Multiple telecetnric imaging systems are arranged in a modified 2D array. The horizontal parallax images displayed by LCD panels are imaged to be superimposed on a 3D screen. All parallax images are displayed in the different horizontal directions because all imaging systems have different horizontal positions. The difference of the vertical display directions due to the imaging system's vertical positions is canceled by a vertical diffuser placed at the 3D screen. Observers can percept 3D images with the binocular disparity, the vergence, and the smooth motion parallax. In addition, the accommodation function may also work because a number of parallax images are displayed with a very small angle interval in the horizontal direction. A prototype 3D display including 64 color LCD panels was constructed.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.850-853
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• 2009

Many well-known pixel compensation circuits have been applied to control TFT $V_{th}$ variations on small size AMOLED panels. For large (>30-inch) AMOLEDs, luminance and color uniformity are affected by TFT variations, but also by ELVDD IR drop and cavity non-uniformity which are not easily compensated by in-pixel circuits. AMOLED panels may also suffer from manufacturing-induced mura. An external compensation method based on optical measurements is proposed and applied to large AMOLED panels. It improves luminance uniformity by up to 95% at 200nits and color uniformity by up to 99% (${\Delta}$u'v' <0.004) on large AMOLED panels, and provides-increased margin against processinduced mura.