• Transactions on Electrical and Electronic Materials
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• v.3 no.1
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• pp.38-41
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• 2002

We have investigated current-voltage-luminance characteristics of organic light-emitting diodes based on TPD/Alq$_3$organics depending on the application of forward-backward bias voltage. Luminance-voltage characteristics and luminous efficiency were measured at the same time when the current-voltage characteristics were measured. We have observed that the current-voltage characteristics shows a reversible current maxima at low voltage, which is possibly not related to the emission from Alq$_3$. Current-voltage-luminance characteristics imply that the conduction luminance mechanism at low voltage is different from that of high voltage one.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.639-642
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• 2005

A new dual-slope ramp (DSR) reset waveform is proposed to improve the dark room contrast ratio in AC-PDPs. The proposed reset waveform has two different voltage slopes during a ramp-up period. The first voltage slope is lower than the conventional ramp voltage slope, causing a reduction in the background luminance, whereas the second voltage slope is higher than the conventional ramp voltage slope, causing an increase in the background luminance. Thus, a bias voltage is also applied during the second voltage-slope period to adjust the background luminance and address discharge characteristics. As a result, the proposed dual-slope reset waveform can lower the background luminance, thereby improving the high dark room contrast ratio of an AC-PDP without reducing the address voltage margin

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.10
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• pp.704-709
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• 1999

The optical properties such as luminance and color coordinates for phosphor layer were studied with applied voltage and gas pressure, Xe mixing ratio, frequency using He and Xe mixing gas in chamber like AC PDP. The luminance of red phosphor layer at constant pressure(300Toor) is increased with increasing voltage, but color purity is not varied. The luminance of red phosphor layer at constant voltage(280V)is decreased with increasing pressure, but the color purity is not varied. But the luminance is increased with increasing Xe mixing ratio at constant pressure(200Toor). And also the color purity is improved by this process. The luminance is increased up to 40kHz, but the color purity with frequency is not varied.

• 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 the Korean Graphic Arts Communication Society
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• v.29 no.2
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• pp.33-44
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• 2011

The inorganic powder EL lamp was made by screen printing technique with a phosphor ink and a dielectric ink. The thickness of a phosphor ink layer and a dielectric ink layer is $35{\mu}m$ and $54{\mu}m$ respectively. A increasing ratio of the luminance of inorganic powder EL lamp to be a 1P1PD-phosphor ink layer in which increased voltage at constant frequency is higher 12% than when increased frequency at constant voltage. It is higher 57% than when increased frequency at constant voltage that the rate of increase of the luminance of inorganic powder EL lamp to be a 2PD-phosphor ink layer in which increased voltage at constant frequency. Finally, when increased voltage at constant frequency, a increasing ratio of the luminance of inorganic powder EL lamp to be a 2PD-phosphor ink layer is higher about 40% than that to be a 1P1PD-phosphor ink layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.85-88
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• 1998

Light-emitting diode(LEDs), diode arrays, and phosphor display panels are finding increased use in a variety of commercial applications. Present and anticipated application of these devices include solid state indicator(e.g., digital clocks, meter readout) and display systems(e.g., instrument panels, TV display), the application being determined by the light -output capability and size availability(cost) of the particular device. In this work, Phosphor based on ZnS:Cu are used. Relation by luminance with the thickness of insulating layer and phosphor layer are discussed. Increased thickness of insulating layer are stable on voltage to 300V. By considering thickness and voltage, optimal structure and thickness are investigated. Also in order to maximize even surface emission, various sieving process are introduced. Very similar phosphor particle size is selected. Luminance by various wave intensity is also investigated. 150cd/m$^2$ luminance are investigated in stable voltage and frequency.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.52 no.2
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• pp.61-67
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• 2003

To improve the luminance and luminous efficiency of a surface-discharge alternate current plasma display panel, we analyzed the sustain discharge characteristics as the voltage of the address electrode In the study. As the results, when the address voltage is a half of the sustain voltage in the sustain period, the luminance and luminance efficiency are the highest. The luminance efficiency increased about 16.2%~20.8% compared with the conventional type.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.461-464
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• 2008

We have developed low voltage driving red phosphorescent organic light-emitting devices using a new electron transport layer. $Ir(piq)_3$ and CBP were used as a phosphorescent dopant and an emission host, respectively. The device exhibits a luminance of $1000\;cd/m^2$ at a voltage of 2.8 V. This high luminance at low voltage results from a high electron conduction behavior of the new electron transport layer.

• Journal of the Korean institute of surface engineering
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• v.52 no.2
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• pp.72-77
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• 2019

To study the characteristics of AC driven OLED, we fabricated the fluorescent OLEDs and analyzed the electroluminescence characteristics of OLEDs with AC negative voltage. The luminance and the current density of the OLED decreased, and the number and size of the dark spots increased in proportion to the duration time and level of the applied AC negative voltage. The current efficiency of the OLED was improved when high AC negative voltage was applied within a short time. When the AC negative voltage of 10 V was applied for 1 minute, the efficiency was improved by 12.4%. Also, the degradation of luminance and current efficiency due to the duration of light emission was improved in the case of OLED applied for 1 minute with 10 V AC negative voltage. These are expected as a result of the improvement of the leakage current characteristics by eliminating the short-circuit region formed by the defect of the OLED at the AC negative high voltage. As a result, the continuous application of AC negative voltage reduced the luminance and the current density of OLED, but the temporary application of AC negative voltage with the proper time and voltage could improve the efficiency and lifetime of OLED.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1258-1261
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• 2005

The ramp type bias voltage applied to the common electrode during a reset-period is newly proposed to lower the background luminance and to improve the address discharge characteristics in AC-PDP. The positive ramp bias voltage is applied during the ramp-up period, whereas the negative ramp bias voltage is applied during the ramp-down period. The effects of the voltage slopes in both the positive and negative ramp bias voltages on the background luminance and address voltage characteristics are examined intensively. It is observed that the optimized positive and negative ramp bias voltages applied to the common electrode during the ramp-period can lower the background luminance and also enhance the address discharge characteristics of the AC-PDP.