• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2005년도 추계종합학술대회
• /
• pp.877-880
• /
• 2005

DMB 서비스의 상용화 및 3D 게임, 휴대용 인터넷, 영화서비스 등의 멀티미디어 서비스를 위하여 최근 모바일용 기기에 VGA급 이상의 컬러 FPD의 채택이 본격화 하고 있다. VGA급 이상의 화면에 30fps의 실시간 동영상을 디스플레이 하려면 소프트웨어를 통한 구현방법은 프로세서의 성능이 이에 미치지 못하기 때문에 구현이 어렵고, 전용 하드웨어를 구성하여야만 풀 프레임의 동영상지원이 가능하다. 본 논문에서는 모바일 디스플레이 장치의 실시간 동영상 구현을 위한 flash memory controller, OLED interface로 이루어진 OLED 제어기를 제안하고 이를 FPGA로 구현하여 성능을 평가하고자 한다.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2005년도 춘계종합학술대회
• /
• pp.1030-1033
• /
• 2005

기존의 임베디드 시스템 장비는 간단한 메뉴화면, 배경화면 등의 디스플레이 환경을 제공하였다. 하지만, 임베디드 시스템 장비의 사용범위가 점차 확대대고, 사용자의 요구가 증가되면서 멀티미디어 콘텐츠 및 동영상의 지원 여부가 장비의 주요 성능으로 부각되고 있다. 하지만 기존 임베디드 시스템 장비에서는 소프트웨어로 디스플레이 환경을 구현하므로 멀티미디어 콘텐츠 및 동영상 지원에 대한 충분한 데이터 전송 대역을 확보하기 어려우며 메인 프로세서의 실행에 많은 부담을 주어 시스템 성능을 저하시키는 주요 원인이 되었다. 본 논문에서는 임베디드 시스템에 적합한 OLED/TFT-LCD 컨트롤러 모델을 제안하고 이를 Verilog-HDL을 이용하여 설계하여 기존의 임베디드 시스템 장비의 디스플레이 성능과 비교 평가한다.

• Journal of Semiconductor Engineering
• /
• 제3권1호
• /
• pp.154-160
• /
• 2022

In this paper, we design a DC-DC boost converter with RF noise immunity to supply a stable positive output voltage for OLED displays. For RF noise immunity, an input voltage variation reduction circuit (IVVRC) is adopted to ensure display quality by reducing the undershoot and overshoot of output voltage. The boost converter for a positive voltage Vpos operates in the SPWM-PWM dual mode and has a dead-time controller using a dead-time detector, resulting in increased power efficiency. A chip was fabricated using a 0.18 um BCDMOS process. Measurement results show that power efficiency is 30% ~ 76% for load current range from 1 mA to 100 mA. The boost converter with the IVVRC has an overshoot of 6 mV and undershoot of 4 mV compared to a boost converter without that circuit with 18 mV and 20 mV, respectively.

• 반도체디스플레이기술학회지
• /
• 제12권2호
• /
• pp.13-17
• /
• 2013

In lighting system where several large-area organic light-emitting diode (OLED) lighting panels are involved, panel aging may appear differently from each other, resulting in a falling-off in lighting quality. To achieve uniform light output across large-area OLED lighting panels, we have employed an optical feedback circuit. Light output from each OLED panel is monitored by the optical feedback circuit that consists of a photodiode, I-V converter, 10-bit analogdigital converter (ADC), and comparator. A photodiode generates current by detecting OLED light from one side of the glass substrate (i.e., edge emission). Namely, the target luminance from the emission area (bottom emission) of OLED panels is monitored by current generated from the photodiode mounted on a glass edge. To this end, we need to establish a mapping table between the ADC value and the luminance of bottom emission. The reference ADC value corresponds to the target luminance of OLED panels. If the ADC value is lower or higher than the reference one (i.e., when the luminance of OLED panel is lower or higher than its target luminance), a micro controller unit (MCU) adjusts the pulse width modulation (PWM) used for the control of the power supplied to OLED panels in such a way that the ADC value obtained from optical feedback is the same as the reference one. As such, the target luminance of each individual OLED panel is unchanged. With the optical feedback circuit included in the lighting system, we have observed only 2% difference in relative intensity of neighboring OLED panels.

• 전기전자학회논문지
• /
• 제24권3호
• /
• pp.853-858
• /
• 2020

본 논문은 통신기기에서 유입 되는 RF 노이즈에 대해 내성을 가진 OLED용 2-채널 DC-DC 변환기를 제안한다. RF 신호 내성을 위해, 입력전압 변동만큼 감쇠시키는 입력전압 변동감쇠 회로가 내장된다. 양의 전압 V_POS를 출력하는 부스트 변환기는 SPWM-PWM 듀얼모드로 동작하고, 데드 타임을 제어함으로써 전력 효율을 제고한다. V_NEG를 출력하는 인버팅 차지펌프는 2-상 출력 구조로 VCO를 이용한 PFM으로 동작해 작은 리플을 갖도록 설계된다. 0.18 ㎛ BCDMOS 공정으로 시뮬레이션 한 결과, 부스트 변환기 출력전압의 오버슈트와 언더슈트는 10 mV에서 각각 2 mV, 5 mV로 감소하였다. 또한, 2-채널 DC-DC 변환기의 전력효율은 39%~93%을 가졌고, 데드 타임 제어기를 적용한 부스트 변환기의 효율은 종전보다 최대 3% 증가하였다.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
• /
• pp.673-675
• /
• 2004

This study proposes controller with voltage-compensated drivers for producing gray-scaled pictures on passive matrix organic light emitting diodes (PMOLEDs) panels. The controller includes voltage type drivers so the output impedance of the driver is far less than that of the current-type driver. Its low output impedance provides better electron-optical properties than those of traditional current drivers. A free running clock and a group of counters are applied to the gray-scaled function so that phase lock loop (PLL) circuit can be reduced in the controller. A pre-charge function is used to enhance performance of the luminance of an active OLED pixel. As a result, distribution of the low gray level portion is achieved linear relationship with input data. In this work, the digital part of the proposed controller is implemented using FPGA chips, and analog parts are combined with a digital-analog converter (DAC) and analog switches. A still image is displayed on a $48^{\ast}64$ PMOLEDs panel to assess the luminance performance fir the controller. Based on its cost requirement and luminance performance, the controller is qualified to join the market for driving PMOLEDs panels.

• 한국정밀공학회지
• /
• 제26권11호
• /
• pp.70-76
• /
• 2009

Web tension control system recently have been applied to OLED(Organic Light-Emitting Diode), RFID of flexible material, e-Paper and PLED(Polymeric LED) and various web control algorithms have being developed for higher productivity and product quality These system need an accuracy model to design and implement controller. In this paper, the web tension control system with dancer roll is mathematically modeled. Mathematical model consists of 8 subsystems and each subsystems can be described as impedance structure which connected by velocity and tension. Mathematical model is different from the estimated model at high frequency range because of structure dynamics which is ignored on mathematical model. The estimated model is derived using ARMAX model. The controller is designed using the estimated model. The step response of the estimated model are compared with that of physical model for a validation of estimated model. The experimental results show a good match between them.

• Journal of Electrical Engineering and Technology
• /
• 제12권2호
• /
• pp.944-949
• /
• 2017

Recently, the demand of maglev systems in the manufacturing industry for LCD and OLED display panels, which are required to be very clean and possess vacuum systems, has been increasing due to their characteristics such as being non-contact, noise free and eco-friendly. However, it is still a challenge to simultaneously control both the propulsion and levitation for their interactive effect difficult to be exactly measured. In this paper, we proposed a new tuning method for controlling the magnetic levitation force robustly against the levitation disturbance caused by a propulsion system, based on LQ servo optimal control. The disturbance torque of the LSM propulsion system is calculated through FEM analysis in such a way that the LQ servo controller is determined in order to minimize the effect of the disturbance. The robust performance of the proposed LQ servo control method for the in-track type magnetic levitation systems is demonstrated via simulations and experiments.