MCU를 이용한 POWER LED의 효과적인 Dimming 제어

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Analog, PWM(Pulse Width Modulation) and FM(Frequency Modulation) control have included the dimming methods for POWER LED. Analog dimming is achieved by adjusting forward current of POWER LED. Although it is possible to adjust linearly brightness levels between 0 % and 100% by analog dimming, it makes a variation of wavelength by changing the POWER LED's forward current.
PWM dimming is achieved by applying full current to the POWER LED at a reduced duty cycle. Generally, it is known that PWM dimming doesn't make variation of wavelength. However, it makes difficult to adjust linearly bright level between 0 % and 10%.
Frequency Modulation Dimming method that maintains the average duty cycle in a specified time period can be used to dim POWER LED. Although Frequency Modulation dimming method is same to dimming result by PWM in aspect of wavelength, this method has problem of flickering at low level dimming.
In order to complement disadvantages of existing dimming methods, an optimal dimming method was proposed in this paper. Proposed Dimming method uses PWM Dimming method at Dimming Range Between 10% and 100% and it uses the Analog dimming method changing the amplitude of PWM waves below 10%.
Experimentally, proposed Dimming method was shown to be possible to adjust linearly brightness levels between 0 % and 100% and represented a constant wavelength output in various Dimming levels between 10% and 100%.
Alternative Title
Effective Dimming Control of the Power LED Using the MCU
Alternative Author(s)
Kim Doo-Hyun
조선대학교 대학원
일반대학원 컴퓨터공학과
Awarded Date
Table Of Contents

제1장. 서 론 1
제2장. 관련 연구 5
제1절. PWM Dimming 5
1. PWM Dimming 원리 5
2. PWM Dimming 장ㆍ단점 7
제2절. Frequency Modulation Dimming 9
1. Frequency Modulation Dimming 원리 9
2. Frequency Modulation Dimming 장ㆍ단점 11
제3절. Analog Dimming 15
1. Analog Dimming 원리 15
2. Analog Dimming 장ㆍ단점 16
제3장. MCU를 이용한 Dimming 제어 19
제1절. Power LED Dimming 제어 방법 19
제2절. Power LED Dimming 회로 설계 22
1. LED 리플 전류에 따른 광 출력 상태 22
2. LED 리플 전류에 따른 접합 온도 상태 24
3. LED 순방향 전류와 광 출력의 특성 25
제3절. MCU를 이용한 Dimming 제어 회로 설계 34
제4절. MCU를 이용한 Dimming 제어 장ㆍ단점분석 38
제4장. 실험 결과 및 특성 검토 40
제1절. PWM Dimming 제어 실험 결과 및 특성 43
제2절. Frequency Modulation Dimming 제어 실험 결과 및 특성 45
제3절. Analog Dimming 제어 실험 결과 및 특성 47
제4절. MCU를 이용한 Dimming 제어 실험 결과 및 특성 49
제5장. 결 론 52

참고 문헌 53
조선대학교 대학원
김두현. (2013). MCU를 이용한 POWER LED의 효과적인 Dimming 제어.
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General Graduate School > 3. Theses(Master)
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