LED를 이용한 고휘도 평면광원의 설계 및 제작 = Design and fabrication of a high brightness flat ligh source using light-emitting diodes

다국어 초록 (Multilingual Abstract)

The dissertation deals the design and fabrication of flat panel light source using the LED which can exchange the use of fluorescent lamps and metal halide lamps.
Yellow phosphor was synthesized by using the spraying heat decomposition method and was fabricated for its use as to obtain the white color of LED. This was reported to be a main component of a flat panel light source. It was then combined with a blue LED chip. 1W, 2W, 3W and 4W grade white LEDs were obtained by the number of blue LED chips used.
Temperature keeping below 800℃, the obtained globular form showed insignificant binding force. However, it was observed that the product obtained at 1100℃ possessed the most suitable characteristics for the purpose. The light emitting characteristics were changed according to the doped Ce quantity. The most optimum doping density was when x was equal to 0.035. This showed the best lighting characteristics. Further, the XRD results enabled that with the heat treatment (above than 1700℃), it possessed the YAG phase. However, the sample treated relatively at lower temperature i.e., below 1700℃, it showed not pure YAG as accompanied with some CeO2 peak, which was disappeared completely at 1800℃. From these results, it was concluded that the reason of the luminous decrement was originated because of the impurity present. Based on the above observations, The synthesized globular phosphor subjected for the heat treatment 1800℃ for 6 hours of time in an electronic furnace showed reasonably good PL characteristics.
The fabricated white LED was used. It was further noted that the most appropriate surface to emit heat from the 4W grade LED was 16Cm2. The mentioned surface area was calculated with the precondition, keeping the heat dissipation system below 40℃ along with the thickness of the adopted flat aluminum 2mm.
The boost - converter type circuit was intended to operate the fabricated LED and a number of LEDs were lightened by using this system. Additionally, a driver IC that serve as PWM dimming was used. Hence, the PWM control circuit was also included, which was basically an analogue type. Because the duty rate of the IC could be controlled from 1% to 99%, the most proper lighting condition of the LED was acquired by applying this IC.
The lens that converts a point light source into a line light source was designed and fabricated to acquire the function of a line light source similar to a fluorescent lamp.
Moreover, the pattern design formula was derived to convert a line light source into an area light source. An area light source for the LED illumination was made by applying the pattern design formula for this light guide panel and the results were compared with the fluorescent lamp widely used at present.
It was reported that the brightness value of a 40W fluorescent lamp is 88.2Lux. On the other hand, the fabricated LED lighting system with 18W could emit 98.7Lux, which is 10.5Lux brighter than the brightness of the 40W fluorescent lamp. Therefore, the fabricated LED lighting system needed about half the electric power consumption comparing to the 40W fluorescent lamp along with 3Lux more brightness to the 40W fluorescent lamp.
Additionally, a LED tunnel lamp which was 30W was then fabricated using the same technology as described before. The brightness of this system was half degree when it was compared with the 80W tunnel lamp used commercially.
In this study, the optimized LED tunnel lamp showed the possibility to obtain the brightness which was two times higher than the tunnel lamp used commercially.

목차 (Table of Contents)

• 목 차
• Ⅰ. 서 론.................................................................. 1
• 1.1 연구 동기 및 필요성.............................................. 1
• 1.2 연구 목표 및 내용................................................. 3
• Ⅱ. LED Lighting chip의 설계 및 제작............................. 5
• 2.1 LED의 발광원리 및 재료......................................... 8
• 2.2 LED의 백색구현방법.............................................. 13
• 2.3 LED의 특징 및 응용분야......................................... 18
• 2.4 청색 LED와 황색 형광체를 이용한 백색 LED의 구현.... 21
• 2.4.1 황색 형광체의 제조............................................ 22
• 2.4.2 백색 LED의 구현............................................... 28
• 2.4.3 LED의 MACOB화.............................................. 33
• 2.5 결과 및 논의........................................................ 34
• Ⅲ. LED 구동회로의 설계 및 제작................................... 38
• 3.1 LED 구동사양....................................................... 38
• 3.2 설계시 기본적인 고려사항...................................... 44
• 3.3 LED의 구동방식.................................................... 48
• 3.4 구동회로의 설계................................................... 53
• 3.5 구동회로의 제작................................................... 59
• 3.6 결과 및 논의........................................................ 60
• Ⅳ. LED의 방열시스템 설계 및 제작................................ 64
• 4.1 전도(conduction)................................................. 67
• 4.2 대류(convection).................................................. 70
• 4.3 복사(radiation)..................................................... 72
• 4.4 방열 system 설계................................................. 73
• 4.5 방열 system 제작................................................. 76
• 4.6 결과 및 논의........................................................ 77
• Ⅴ. 점광원의 선광원화를 위한 렌즈의 설계 및 제작........... 82
• 5.1 굴절(refraction).................................................... 82
• 5.2 전반사(total reflection).......................................... 84
• 5.3 렌즈의 설계......................................................... 85
• 5.4 렌즈의 제작......................................................... 87
• 5.5 결과 및 논의........................................................ 88
• Ⅵ. 면광원의 설계 및 제작............................................ 93
• 6.1 도광판의 역할 및 제조방식..................................... 93
• 6.2 패턴의 정의 및 역할.............................................. 99
• 6.3 패턴설계이론 및 설계식......................................... 100
• 6.4 설계식의 타당성 검증............................................ 111
• 6.5 면광원의 제작 및 검토........................................... 119
• Ⅶ. 응용 시스템.......................................................... 129
• 7.1 LED 조명장치....................................................... 129
• 7.2 30W급 LED 터널등................................................ 136
• Ⅷ. 결 론.................................................................. 142
• 참 고 문 헌................................................................ 144
• ABSTRACT............................................................... 149