• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.10
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• pp.909-913
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• 2002

The luminance and discharge characteristics of ac PDP may be significantly affected by a small amount of impurity gas in working gas. These impurity gases such as O$_2$, O, C and H$_2$ can be mixed in the manufacturing and /or discharge process. In this paper a small amount of impurity gas in acPDP are introduced quantitatively and the relationship between the amount of impurity gas and the luminance/discharge characteristics are investigated. The luminous efficiency decreased seriously with increase in the partial pressure of impurity gases, especially in H$_2$, O$_2$ and CO$_2$. Under the condition of the impurity gas ratio of 2${\times}$10$\^$-3/ for Ar, N2, H$_2$, CO$_2$ and O$_2$, the luminous efficiency decreased about 8%, 8%, 32%, 36% and 50%, respectively.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.860-865
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• 2004

Field emission display(FED) using carbon nanotubes (CNT) as field emitters is expected to large-area panels with high luminance and low power consumption. In order to perform the uniform luminance with low driving voltage, we introduced a new electrode to apply higher electric potential over the CNT cathode in 2003.[1] In the study, we described the luminance uniformity of the panel and the improvement of emission uniformity by increasing the emission-site density. The luminance uniformity of the several ideal dots which were selected over the display area in the panel was 2.8%. [2] The CNT cathode was irradiated by excimer-laser, which was effective to improve emission uniformity and lower driving voltage. A prototype of CNT-FED character display was performed for middle size message displays. The prototype panel had 48 x 480-dots and the resolution was 1-mm. The panel realized high luminance at low power consumption. It will be important characteristics for legible and ubiquitous displays. [3]

• Transactions on Electrical and Electronic Materials
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• v.8 no.6
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• pp.268-273
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• 2007

In this study, It was studied about the luminance characteristics of 17 inch direct-type back light using EEFL(external electrode fluorescent lamp) and CCFL(cold cathode fluorescent lamp). The EEFL has a long life time because the electrode is installed outside of lamp. And it is produced in lower price than conventional CCFL. Moreover, it does not need process of installing internal electrode. However, the EEFL technology has several problems such as difficulty of designing driving inverter and preventing this phenomenon along the skin of lamps. We suggested two types of backlight unit for LCD TV application using the EEFL and the CCFL. We found optimized optical design parameters. We set the optical variation parameters such as lamp height, lamp distance, total thickness, and angles of inner walls. We achieved 7580 nits of center luminance, 82% of luminance uniformity by using 20 lamps of the EEFL and 7297 nits of center luminance, 78% of luminance uniformity by using 16 lamps of the CCFL.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1915-1917
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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 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 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 pressure is low and when the RF power is in the range of 30 [W]${\sim}$40 [W].

• Journal of the Optical Society of Korea
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• v.12 no.3
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• pp.174-177
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• 2008

The luminance properties of FFL(Flat Fluorescent Lamp) backlights have been investigated in detail for the first time. The on-axis luminance gain as well as viewing-angle characteristics on various combinations of optical films were obtained from FFL backlight and compared to the results of conventional CCFL(cold-cathode fluorescent lamps) backlights. It was found that the on-axis luminance gains achieved by using optical films in the FFL backlight were lower than those in the CCFL backlight indicating that the recycling processes occurring between optical films and light sources/reflection sheet are not so effective in the FFL backlight due to the much larger area of, and thus higher absorption probability of the FFL. This result suggests that new optical films should be developed for FFL backlight and other flat-lamp backlight technologies.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.198-201
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• 2002

We have studied the temperature dependence of current-voltage and luminance-voltage characteristics of Organic Light Emitting Diodes(OLEDs). The OLEDS are based on the molecular compounds, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD) as a hole transport, tris(8-hydroxyquinolinoline) aluminum(III) (Alq$_3$) as an electron transport, and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as a buffer layer. The current-voltage and luminance-voltage characteristics were measured in the temperature range of 10[K] and 300[K]. A conduction mechanism in OLEDs has been interpreted in terms of space-charge-limited current(SCLC) and tunneling mechanism.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1185-1188
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• 2008

The on-axis luminance gain as well as the viewing-angle characteristics of flat-lamp-based backlights have been analyzed for the first time. The on-axis luminance gain on each optical film in flat-lamp backlight was smaller than that obtained from the conventional tubular-lamp-based backlight. The origin of and possible solution to this problem were suggested.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.1
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• pp.40-46
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• 2019

To study the frequency response characteristics of alternating-current-driven organic light-emitting diodes (OLEDs), we fabricated blue-fluorescent OLEDs and analyzed their electroluminescent characteristics according to the alternating current voltage and frequency. The luminance-frequency characteristics of alternating-current-driven OLED was similar to that of a low-pass filter, and the luminance of high-voltage OLED decreased at higher frequency than low-voltage OLED. The luminance characteristics of the OLED according to the frequency is due to the capacitive reactance in the OLED, generated during the alternating current driving. The frequency response characteristics of the OLED according to the voltage is due to the decrease in internal resistance of the organic layer. In addition, the negative voltage component of the alternating current did not affect the frequency response of the OLED. Therefore, the electroluminescent characteristics of OLED with an alternating current power of 60 Hz are not influenced by the frequency.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.6
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• pp.480-486
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• 2006

The radiation characteristics of a high-luminance light-emitting diode (LED) light source were studied to evaluate its potential as an energy-saving light source for fishing lamps. The angle of the LED light source with 50% illuminance was $8-15^{\circ}$, and it had strong directional characteristics. The wavelengths at which the radiance and irradiance were maxima were 709, 613, 473, 501, 525, and 465 nm for red, orange, blue, peacock blue, green, and white light, respectively. The underwater transmission characteristics of the LED light source were superior in the order blue, white, peacock blue, and green in optical water type I: blue, peacock blue, white, and green in optical water type II; and blue, peacock blue, green, and white in optical water type III. Setting the underwater transmission characteristics of the LED light source in optical water type I at 100%, the transmission of water types II and III decreased to 67 and 17%, respectively. Based on the underwater transmission characteristics calculated in optical water types I-III, the blue and peacock blue LED light sources can be used as an energy-saving light source for fishing lamps.