• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.229-230
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• 2009

This paper proposes a new design of ultra-slim color mixing lens (CML) for backlight unit (BLU), and presents simulated performance of the design. The novel color mixing structure has a shorter mixing length (< 1cm) than the existing color mixing structure, and achieves high efficiency and uniformity.

• Journal of the Semiconductor & Display Technology
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• v.11 no.1
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• pp.21-27
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• 2012

The optical diffuser for direct-lit LED backlight unit was prepared by using extrusion compounding followed by thermoforming process. Poly(methyl methacrylate) (PMMA) with superior optical characteristics and polycarbonate (PC) with good thermal property were used as base resins, and crosslinked polystyrene (PS) and PMMA beads as diffusing agents were incorporated into resin matrix to derive light scattering and diffusing action. In the compounded plate, the diffusing beads were observed to be dispersed uniformly and distinctly in the continuous phase. The inclusion of polymeric beads up to 3 wt% substantially enhanced the optical characteristics such as luminance, luminance uniformity, haze for the diffuser. Two different diffusers of PC and PMMA-based compound with various compositions were compared in terms of measured optical, thermal, and mechanical properties, which would be expected to be utilized for the industrial application of LED backlight unit.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.6
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• pp.535-542
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• 2008

This paper presents a high efficiency half-bridge DC-DC converter for an LED backlight drive system of LCD module inspection equipment. The proposed converter improves the converter efficiency using characteristics of the asymmetrical half-bridge converter and the self-driven synchronous rectifier, and thus improves the total efficiency of the LED backlight drive system. The synchronous rectifier applied to the proposed converter is the new topological synchronous rectifier, which changes slightly the transformer structure and the synchronous switch connection in the asymmetrical half-bridge converter with a conventional self-driven synchronous rectifier. Since the proposed converter utilizes the transformer leakage inductor as its resonant inductor, its structure is simplified. The proposed converter well operates under the universal DC input voltage ($250{\sim}380V$). The operational principle and a design example for a 100W prototype are discussed in detail, respectively. Experimental results are shown for the designed prototype converter under universal DC input voltage.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1316-1318
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• 2009

Nonideality of LED lens and diffuser as well as crosstalk between backlights should be compensated because they have large effects on image qualities. The computation complexities of conventional compensations are greatly increased as resolution becomes higher. The block based compensation is proposed to alleviate the computation complexity considering backlight profiles and image pixel characteristics.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1349-1349
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• 2008

The applications of white LEDs has been expanded from mobile phone to LCD TV as a backlight source recently and now are penetrating into the lighting market. With these changes new requirements for LEDs phosphors are demanded. In this point of view recent technology trend of phosphors for LCD backlight and lighting will be discussed.

• Proceedings of the Optical Society of Korea Conference
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• 2009.10a
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• pp.253-254
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• 2009

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1503-1506
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• 2008

A novel white-LED (light emitting diode) backlight system for 46"LCD TVs which involves the current controlled X-Y channel driving method is proposed in this paper. There are two problems related to the LED current in the conventional X-Y channel driving driven by a constant voltage source. To solve these problems, a real time current sensing system is applied to the conventional one and the time-division current sensing method is employed.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1086-1089
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• 2006

We have developed 2.4" QVGA wide color gamut LCD module using RGB-LED backlight. The color gamut is achieved 100% of NTSC compared to 70% of NTSC when used with White-LED backlight. But RGB LED backlight is difficult to maintain its color balance since RGB LED is gradually degraded by the change of ambient temperature and a long term aging characteristic, etc. This paper describes a feasibility study of our optical feedback system developed for preventing such a color shift.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.522-524
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• 2005

The LED light source has many excellent advantages for the application of LCD backlight module. As we know, the operational temperature can significantly influence the characteristics of LEDs. Heat can damage the LED 's quality, and decrease its lifetime and output light intensity. In this paper, we perform computer software, Flomerics CFD (Computational Fluid Dynamics), to simulate heat distribution of the 20.1" LED backlight module we designing, and realize how the different heat sinks can solve the serious heat problem in practice.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.928-931
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• 2014

사용자와의 인터페이스가 많은 모바일 기기에서 TFT LCD는 현재 가장 많이 사용되는 디스플레이로 백라이트(backlight)로 인한 전력 소모가 많아 배터리 수명이 짧아지는 것이 큰 문제이다. 전력 절감을 위해 사용되는 backlight dimming 기법은 명암비 조정에 따른 이미지 왜곡의 보완 기법과 함께 많은 연구가 진행되고 있다. 본 논문에서는 PWM 구동에 의한 LED backlight 제어가 가능한 TFT LCD 보드 구현을 소개하고 이 보드를 대상으로 framebuffer와 LED 제어용 리눅스 장치 드라이버를 사용한 객체 기반의 저전력 인간 시각 만족의 화질 보상 dimming 알고리즘의 구현 연구 내용을 기술한다.