• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1156-1159
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• 2008

Local dimming driving has advantages in reducing power consumption and improving contrast ratio(CR). In an LED backlight unit(BLU), many small LED blocks are implemented in 2-dimmensional space, and luminance of the blocks is controlled by a local dimming algorithm. However, such a BLU can induce various recognizable artifacts. A new novel algorithm is proposed for exact block luminance calculation to correct local dimming artifacts. Also we discuss modified low-gray-level dimming to achieve much aggressive power saving in a local dimming BLU system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.4
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• pp.660-667
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• 2008

To improve the luminous efficacy of PDPs, an AC PDP with new metal electrode structure is suggested. Operating voltage margin, power consumption, luminance, luminous efficacy, addressing jitter and ICCD image of test panel with proposed structure are measured, to compared with performances of the conventional ITO structure and proposed structures. To enhance luminous efficacy, we designed new structure which have asymmetric metal electrode structure. The experimental results show that the suggested structure shows luminance to maximum 89% and luminous efficacy to maximum 107% compared with conventional ITO standard structure. In addition, proposed structures with asymmetric electrode show low power consumption by $2{\sim}3%$, high luminance by $5{\sim}7%$, and high luminous efficacy by $2{\sim}3%$ compared with proposed symmetric electrode structures.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.799-802
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• 2004

In this paper, the active backlight control technology with data processing algorithm was developed in order to improve image quality for IPS-mode LCD-TV applications. The image blinking problem caused by repeatedly abrupt change of the backlight luminance was solved by algorithms-Fba(Flexible Boundary algorithm) and Cfa(Cumulative Feedback algorithm)-and the optimized number and space of backlight dimming steps based on perception. In the IPS-mode 42" TFT-LCD panel, the dynamic contrast ratio can be more than twice the typical level by means of lower block luminance and higher white luminance. Additionally, Power consumption and LCD temperature was decreased.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1291-1292
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• 2008

ITO is widely used as an anode material in OLED, because of its good transparency, low electrical resistivity, high work function, and efficient hole injection properties. The interface between the electrode and the organic layer in the OLED effects the charge injection process and may influence the electrical and the luminance properties. Surface treatment of ITO, such as an Aquaregia treatment has been shown to enhance the efficiency, and luminance characteristics of the OLED. In this study, we investigated the effect of Aquaregia treatment. The fundamental structures of the OLED were ITO/NPB/$Alq_3$/LiF/Al. The current density-voltage-luminance, efficiency, and lifetime characteristics were measured with untreated and Aquaregia-treated ITO substrates. The Aquaregia treatment was found to enhance the performance of OLED. For the Aquaregia treated device, the maximum luminance and efficiency were increased by about 2 times compared to the untreated device. The mechanism of the Aquaregia treatment is discussed based on AFM analyses.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.220-223
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• 2004

Inductively coupled plasma is commonly used for electrodeless lamp due to its ease of plasma generation. Optical characteristics significantly depend on the RF power and gas pressure of the plasma. This paper describes the measurement of luminance as a function of RF power and gas pressure with a goal of finding optimal operating conditions of the electrodeless lamp. The gas pressure was varied from 10[mTorr] to 300[mTorr] or 500[mTorr] and the RF power was varied from 10[W] to 200[W]. It was found that the luminance tends to be decreased when argon and neon pressure is increased, and the luminance is increased as RF power is increased. It was also found that the luminance per unit RF power is high when the argon and neon pressure is low and when the RF power is in the range of $30[W]{\sim}40[W]$ or 10[W].

• Korean Journal of Materials Research
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• v.19 no.6
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• pp.313-318
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• 2009

Polymer Light Emitting Diodes (PLEDs) with an ITO/PEDOT:PSS/PVK/PFO-poss/LiF/Al structure were prepared on plasma-treated ITO/glass substrates using spin-coating and thermal evaporation methods. The annealing effects of the PFO-poss film when it acts as the emission layer were investigated by using electrical and optical property measurements. The annealing conditions of the PFO-poss emission film were 100 and $200^{\circ}C$ for 1, 2 and 3 hours, respectively. The luminance increased and the turn-on voltage decreased when the annealing temperature and treatment time increased. After examining the Luminance-Voltage (L-V) properties of the PLED, the maximum luminance was found to be 1497 cd/$m^2$ at 11 V for the device when it was annealed at $200^{\circ}C$ for 3 hours. The peak intensity of the PLED emission spectra at approximately 525 nm in wavelength increased when the annealing temperature and time of the PFO-poss film increased. These results suggest that the light emission color shifted from blue to green.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.3
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• pp.255-260
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• 2023

In order to spread LED lighting, LED lighting technology directly driven by alternating current (AC) commercial power has recently been introduced. Since current does not flow at a voltage lower than the threshold voltage of the LED, a non-conductive section occurs in the current waveform, and the higher the threshold voltage of the LED, the more discontinuous current waveforms are generated. In this paper, multi-LED modules are connected in series so that the threshold voltage can be adjusted according to the number of LED modules. A small number of LED modules are driven at a low instantaneous rectified voltage, and a large number of LED modules are driven at a high instantaneous rectified voltage to lengthen the overall lighting time of AC-LED lighting, thereby minimizing the luminance deviation of AC-LED lighting. In addition, the load current flowing through the LED module is adjusted to be the same as the design current even at the maximum rectified voltage higher than the design voltage, so that the light brightness of the LED module is kept constant. Therefore, even if the rectified voltage applied to the LED module changes, the AC-LED lighting in which the light brightness is constant and the luminance deviation is minimal has been realized.

• Journal of IKEEE
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• v.22 no.4
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• pp.901-906
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• 2018

Due to the development of display technologies for images, the resolution and quality of images are increasing day by day. In accordance with the development of the display technology, researches have been actively conducted on technologies for converting and displaying existing images to higher resolution and quality. Since the results of theses studies are included in the image signal processor, hardware implementation is indispensable. In this paper, we propose a real-time HDR(High Dynamic Range) conversion hardware implementation of LDR(Low Dynamic Range) image using luminance distribution. The proposed method extracts the features of the image using the histogram of the luminance distribution, and extends the luminance and color based on the extracted features. In addition, when the proposed method is designed by hardware IP(Intellectual Property) and its performance is verified, 4K DCI(Digital Cinema Image) can be handled at a rate of 30fps at 265.46MHz.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1525-1528
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• 2008

High-luminance CNT-FED character-displays using simple line-rib-structure was performed. One display-panel had $48{\times}480$-dots and the sub-pixel pitch was 1mm. Another panel had $32{\times}256$-color-pixels, and the subpixel size was $0.6mm{\times}1.8mm$. The power consumption was less than 10W at character-displaying module. It should be useful for public display even under emergent no-power condition.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.299-301
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• 2004

Inductively coupled plasma is commonly used for electrodeless lamp due to its ease of plasma generation. Optical characteristics significantly depend on the RF power and gas pressure of the plasma. This paper describes the measurement of luminous efficacy as a function of RF power and gas pressure with a goal of finding optimal operating conditions of the electrodeless lamp. The gas pressure was varied from 10 [mTorr] to 100 [mTorr] and the RF power was varied from 10 [W] to 120 [W]. It was found that the luminous flux tends to be decreased when argon pressure is increased, and the luminous flux is increased as RF fewer is increased. It was also found that the luminance efficacy is high when the argon pressure is low and when the RF power is low.