• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.1011-1013
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• 2007

We report the fabrication of a new inverted OLED devices having potential to be used for both AMOLED and lighting applications.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1081-1084
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• 2007

System on Panel (SOP) can integrate many functions by Thin Film Transistor (TFT) circuits on an insulator substrate without using external driver LSIs. However, to make practical SOP has become more and more difficult because of rapid cost reduction of the driver LSIs. This paper will review the circuit design technology trend for SOP and introduce an example of a practical SOP, 2.0inch QVGA full color active matrix OLED with 8bit source driver.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.17-18
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• 2006

Flat Panel Displays (FPDs) have made a revolution in the display industry. TFT-LCD (Thin Film Transistor Liquid Crystal Display) has been the main player of FPD for last two decades. As the industry continuously develops the technology for better performance with lower cost is constantly demanded where several post LCD technologies are being developed. One of the prime candidates of post LCD technology is AMOLED (Active Matrix Organic Light Emitting Diode) that is considered to be an ideal FPD due to its extraordinary display performance and potentially low cost display structure. This technology has been accepted to small size display applications, such as cellular phone, PDA and PMP, etc. In this paper it is discussed that how this technology can be extended to large size display applications, such as TV. The technical issues and solutions of TFT backplane and color patterning of OLED materials are discussed and proposed

• Proceedings of the Korean Society for Quality Management Conference
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• 2010.04a
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• pp.262-268
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• 2010

Organic light emitting diode is developed fast from 1963 after discovering electric light emitting phenomenon. First PMOLED(passive matrix OLED) product is manufactured and AMOLED(active matrix OLED) using TFT(thin film ransistor) is now in the center. PMOLED is mainly mounted at sub display. but AMOLED is mounted at main display. Also AMOLED expand the market to PMP(portable multimedia players), navigation and TV. Even thought OLED's market is opening to many applications, OLED is worried about lifetime until now. That's appeared in market in a very short time and is not known well about result of OLED's lifetime and reliability test. And there is no standard ssessment method and not enough study to standardization the method. A study's purpose is reduce the time for life test by accelerated current and it can do production possible design by accelerated life model in design phase. It's must be add to process variables and design variables(like ratio of light emitting, organic material structure, condition of aging, etc) to make the best use of supplied accelerated lifetime model in this paper. In terms of lifetime it needs each criterion of applications because of image sticking. In conclusion, it's possible to discover new defect because there is not much time to be opened in market and develop a method of manufacturing process & materials, so we need to study on the subject of this paper continuously.

• Design & Manufacturing
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• v.14 no.3
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• pp.44-49
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• 2020

One of display trends today is development of high pixel density. To get high PPI, a small size of pixel must be developed. RGB pixel is arranged by evaporation process which determines pixel size. Normally, a fine metal mask (FMM; Invar alloy) has been used for evaporation process and it has advantages such as good strength, and low thermal expansion coefficient at low temperature. A FMM has been manufactured by chemical etching which has limitation to controlling the pattern shape and size. One of alternative method for patterning FMM is laser micromachining. Femtosecond laser is normally considered to improve those disadvantages for laser micromachining process due to such short pulse duration. In this paper, a femtosecond laser drilling for thickness of 16 ㎛ FMM is examined. Additionally, we introduce experimental results for controlling taper angle of hole by vibration module adapted in laser system. We used Ti:Sapphire based femtosecond laser with attenuating optics, co-axial illumination, vision system, 3-axis linear stage and vibration module. By controlling vibration amplitude, entrance and exit diameters are controllable. Using vibrating objective lens, we can control taper angle when femtosecond laser hole drilling by moving focusing point. The larger amplitude of vibration we control, the smaller taper angle will be carried out.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.3
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• pp.205-210
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• 2022

A novel OLED pixel circuit is proposed in this paper that uses only n-type thin-film transistors(TFTs) to improve the luminance non-uniformity of the AMOLED display caused by the threshold voltage variation of an OLED driving TFT. The proposed OLED pixel circuit is composed of 6 n-channel TFTs and 2 capacitors. The operation of the proposed OLED pixel circuit consists of the capacitor initializing period, threshold voltage sensing period of an OLED·driving TFT, image data voltage writing period, and OLED·emitting period. As a result of SmartSpice simulation, when the threshold voltage of·OLED·driving TFT varies from 1.2 V to 1.8 V, the proposed OLED pixel circuit has a maximum current error of 5.18 % at IOLED = 1 nA. And, when the OLED cathode voltage rises by 0.1 V, the proposed OLED pixel circuit has very little change in the OLED current compared to the conventional OLED pixel circuit. Therefore, the proposed pixel circuit exhibits superior compensation characteristics for the threshold voltage variation of an OLED driving TFT and the rise of the OLED cathode voltage compared to the conventional OLED pixel circuit.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.553-556
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• 2008

We hereby report novel driving scheme to eliminate effect of "residual" image sticking (RRI) problem which arises due to hysteresis problem in Thin Film Transistor (TFT) in AMOLED Displays. The driving scheme applies "black" voltage after every data voltage period in order to drive AMOLED in uni-direction. The system can be easily implemented with 120 Hz driving scheme which is well matured in AMLCD industries. Our analyses show systematic evaluation of the problem and thereby solving it by simple methods which will be significantly effective of driving OLED towards mass manufacturing stage.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.51-54
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• 2007

Top-emission 3.5 inch qVGA IOD (Inverted AMOLED) was fabricated with inverted EL structure driven by a-Si TFT backplane. In order to get stable driving TFT, we used FCP(Field Control Plate) layer which was connected with the source of the driving TFT. And we developed planarization process to planarize the cathode layer which was the bottom layer of inverted OLED. Our unique IOD structure is “a-Si TFT/ Al(Cathode)/ LiF/ LG-201(ETL)/ EML(RGB)/ HTL/ LG-101(HIL & Buffer layer)/ IZO(Anode)”. LG-201(ETL) layer was studied for more efficient electron injection from cathode to EML, and LG-101(HIL & Buffer layer) covered by IZO anode was also explored for decreasing the EL surface damage.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1040-1043
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• 2009

a-IGZO is an attractive material to make an AMOLED device with uniform TFT properties for use in a large size display. However, this material shows TFT properties that are very sensitive to water or hydrogen. Therefore, it is essential to control these critical factors during fabrication of the backplane in order to improve the TFT performance. In this paper, we report the effect of passivation layer properties on the performance of the oxide TFTs.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.403-408
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• 2006

We have developed a four mask LTPS TFT p-channel process and fabricated active matrix backplanes based on a pixel circuit with three TFTs and one storage capacitor. Top emitting AMOLED displays have been produced to prove the working principle of the active matrix.