(JBE Vol. 21, No. 5, September 2016) (Regular Paper) 21 5, (JBE Vol. 21, No. 5, September 2016) ISS

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1 (JBE Vol. 21, No. 5, September 2016) (Regular Paper) 21 5, (JBE Vol. 21, No. 5, September 2016) ISSN (Online) ISSN (Print) LED a) A Synthesis Ratio of Light Emitting Diodes and Quantization Noise for Increasing Brightness of Head-up Displays Yongseok Chi a),, Light Emitting Diode(LED), Digital Micro Device(DMD) LED LED, LED. 39% LED %.. Abstract This paper studies a light emitting diode(led) overlapping method of a head-up display that consists of a digital micro device(dmd) panel and a red, green, blue LED in order to increase the brightness of display system and optical output power. This optimization overlapping method removes a quantization noise which occur due to LED overlapping too excessive and stabilizes the junction temperature of LED. In order to reduce junction temperature of LED, the a correlation between a green duty and LED overlapping ratio is studied. Throughout this study, the brightness of head-up display exhibited high increasement ratio of luminance around 33.3 percent at 39 percent overlapping method. Keyword : Head-up Display, LED, Junction temperature, Quantization noise a) (Division of Mechatronics Engineering, Dongseo University, Busan, Republic of Korea) Corresponding Author : (Yongseok Chi) ys.chi@gdsu.dongseo.ac.kr Tel: ORCID: ( ). (No. NRF-2015R1C1A1A ). This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(msip) (No. NRF- 2015R1C1A1A ). Manuscript received August 4, 2016; Revised September 23, 2016; Accepted September 23, (diagonal) 2inch (luminance), (illuminance) (sunlit snow) cd/m2

LED LED, LED. 2 LED LED. LED 70 90, LED, 90 20,000. LED LED [3].

2 : LED (Yongseok Chi: A Synthesis Ratio of Light Emitting Diodes and Quantization Noise for Increasing Brightness of Head-up Displays) [1]. DMD LED.. LED, (encapsulant) LED. LED 1 LED (junction temperature) LED [2]. LED LED, LED. 2 LED LED. LED 70 90, LED, 90 20,000. LED LED [3]. LED (Failure), LED 50% TTF(The Time to Failure) 50% LED 10% TTF 10%. TTF 50%, LED 80, LED 70. TTF 10%,, LED 1. LED Fig. 1. The thermal distribution around the LED chip

818 방송공학회논문지 제21권 제5호, 2016년 9월 (JBE Vol. 21, No. 5, September 2016) 그림 2. 접합온도에 따른 LED 수명과 휘도 상관관계 Fig. 2. The junction temperature, life time, and luminance of LEDs 온도가 90도 넘어갈 경우 수명은 1/8로 감소한다.

3 818 방송공학회논문지 제21권 제5호, 2016년 9월 (JBE Vol. 21, No. 5, September 2016) 그림 2. 접합온도에 따른 LED 수명과 휘도 상관관계 Fig. 2. The junction temperature, life time, and luminance of LEDs 온도가 90도 넘어갈 경우 수명은 1/8로 감소한다. 그렇기 막으로 Ⅳ장에서는 제안된 양자화 노이지 억제와 광효율 때문에 접합 온도 40도 이하에서 구동되는 것이 광 효율을 증대를 위한 논문의 실험 결과를 색 정밀도 측면과 광효 증대시키기 위해 가장 좋은 조건임을 알 수 있다. LED의 율 증대 측면에서 정리하였고 제안된 논문의 효과에 대하 수명과 온도 상관관계에서 알 수 있듯이, LED를 광원으로 여 기술하였다. 적용하는 헤드업 디스플레이에서 가장 중요한 요소는 LED 냉각을 통하여 LED 광 출력 효율을 증가시키는 것이며 또 한 안정적인 수명을 유지하는데 있다. 그리고 LED에 인가 하는 전류와 구동 방법에 따라서 변화하는 냉각 조건 및 광 효율을 최적화하는 것이 중요하다. 본 논문에서는 허상디스플레이의 휘도 증가를 위하여 Ⅱ. LED 색 합성 비율과 영상 양자화 노이즈 종 3 의 LED 광원을 사용한 헤드업 디스플레이 광학 구성 을 그림 3과 같이 나타내었으며, 이때 휘도 강조 효과 주파수의 관계 LED 색 합성의 최적화와 이로 인해 발생하는 DMD 패널의 (Broca-Sulzer Effect)와 그리고 인지 밝기와 영상 양자화 노이즈에 대한 상관관계 및 휘도에 영향을 를 정의한 Talbor-Plateau 효과를 위하여 LED에 인가되는 미치는 녹색 LED 합성 비율과 광효율 최적화에 대한 방 전류를 PWM(Pulse Width Modulation) 구동 방 으로 제 법에 대하여 기술하였다. Ⅱ장에서는 디스플레이 휘도 증 어하였다. 휘도 대를 위한 방법으로 LED 색 합성 알고리즘과 색 합성 비 율에 따른 DMD 패널의 양자화 노이즈를 억제시키기 위 한 색 합성 비율의 최적화에 대해 기술하였고 Ⅲ장에서는 LED 색 합성과 녹색 LED 합성 비율과의 상관관계에 대 하여 분석하여 광 효율 증대와 접합온도 안정화를 위한 녹색 LED의 합성 범위 최적화에 대하여 기술하였고 마지 식 강조 효과란 단계적으로 변화하는 백색광 을 사람의 눈으로 볼 때 휘도가 높을수록 감각(인지)되는 밝기의 입상 시간이 짧기 때문에 휘도 강조 효과를 얻을 수 있음을 가리킨다. Talbor-Plateau 효과란 임계 주파수 이상의 빛에 대해서 느끼는 밝기는 평균 휘도에 의해 느껴 지는 밝기 감각과 같음을 나타낸다. 사람의 색 인지 정도 는 녹색에서 가장 우수하며 청색과 적색 순서로 밝게 인지 [4] [5]

4,,,, DMD (color gamut).,, 16.67msec ( 1 ),,. 1 (primary color), 5 3. LED DMD Fig. 3. The optical light system of DMD panel using LEDs 4.

4 : LED (Yongseok Chi: A Synthesis Ratio of Light Emitting Diodes and Quantization Noise for Increasing Brightness of Head-up Displays). PWM LED DMD,, 3 LED 50%, LED LED.,, PWM,,,. LED PWM 13A 2 LED LED PWM. LED PWM. 60Hz (R-Y-G-C-B-M sequence) DMD (color sequence) [6-7]. 4,,,, DMD (color gamut).,, 16.67msec ( 1 ),,. 1 (primary color), 5 3. LED DMD Fig. 3. The optical light system of DMD panel using LEDs 4. DMD LED PWM ( ) ( ) Fig. 4. The PWM drving(left image) and color synthesis method(right image) of LEDs using DMD panel

(JBE Vol. 21, No. 5, September 2016) 5. LED ( ) ( ) Fig. 5. The quantization noise of color synthesis method(left image) and normal image(right image) of DMD panel (Quantization noise).,. 1 2 (secondary color) 8bits 10bits.

5 (JBE Vol. 21, No. 5, September 2016) 5. LED ( ) ( ) Fig. 5. The quantization noise of color synthesis method(left image) and normal image(right image) of DMD panel (Quantization noise).,. 1 2 (secondary color) 8bits 10bits LED DMD. LED PWM(Pulse Width Modulation).,, 31%, 50%, 19% PWM LED 10A 180lm, 13.5A ( LED 3.7V, 5.03A, 19.4V), 3.89%., LED, LED. LED 39.7% LED 10A ( 3.3V, 5.06A, 19.4V). LED 13.5A 33.3%.. 40% 1. LED Table 1. The increasing rate of brightness at LEDs overlap No overlap (red-green-blue sequence) LEDs overlap (red-yellow-green-cyan-blue sequence) LED overlap rate % Forward input current 10[A] 13.5[A] 10[A] Power consumption 3.31[A], 64.25[W] 5.03[A], 97.58[W] 5.06[A], 98.16[W] x, y coordinates 0.296, , , luminance 180[lm] 187[lm] 243[lm] increasing rate of brightness % 33.3%

: LED (Yongseok Chi: A Synthesis Ratio of Light Emitting Diodes and Quantization Noise for Increasing Brightness of Head-up Displays) LED.. LED PWM,, LED (forward current) (duty), 2 DMD.

6 : LED (Yongseok Chi: A Synthesis Ratio of Light Emitting Diodes and Quantization Noise for Increasing Brightness of Head-up Displays) LED.. LED PWM,, LED (forward current) (duty), 2 DMD. LED R-Y-G-B DMD, ( ) LED R-G-C-B DMD. R-Y-G-C-B DMD. 1 2 LED. 6 LED 2 LED. PWM, LED 2. LED (overlap) 5% 40% 5% 35%. 6 LED LED 53% 73%, LED., 2. LED, LED. LED 73%, % LED.. 2 LED.,, 1,, 6. LED ( ) LED ( ) Fig. 6. The increasing rate of brightness(left image) and green duty of LED(right image) at LED synthesis

7 (JBE Vol. 21, No. 5, September 2016) 2. LED Table 2. The hue accuracy at LEDs overlap 39% LEDs overlap Red Green Blue Yellow Cyan Magenta x-coordinates y-coordinates Hue accuracy 96% 98% 98% 99% 86.6% 99% 2 96%, 98%, 98%, 99%, 76.6%, 99%. LED DMD Rec.709,. (color reproduction), CIE(the international Commission on Illumination) color space [8]. (Hue accuracy) 6500K (point) 7 [9].... LED, LED,.,. (References) 7. Fig. 7. The hue accuracy DMD 5%~ 14%, 40%. 2 LED [1] U.S. Department of Transportation National Highway Traffic Safety Administration, Human Factors Aspects of Using Head Up Displays in Automobiles: A Review of the Literature, pp 8, August [2] Displaybank's LED Division, "Analysis of LED and LED applied product s radiation technology", pp 17, May [3] Luminus Devices, "Reliability of LED", PhlatLight LED Report, pp. 6-12, [4] Pinneo LR, Heath RG, Human visual system activity and perception of intermittent light stimuli, Neurological Sciences 5, pp , [5] A. Stockman, "Color from invisible flicker: a failure of the Talbot-Plateau law caused by an early 'hard' saturating non-linearity used to partition the human short-wave cone pathway" Vision research 38, Pergamon, pp. 3-21, [6] David C. Hutchison, "Introducing Brilliant Color Technology", Texas Instruments Report, pp. 2-5, [7] Texas Instruments Report, Moving to higher brightness & LED Projection based 0.55inch DMD & ddp2230", pp , 2008.

: LED (Yongseok Chi: A Synthesis Ratio of Light Emitting Diodes and Quantization Noise for Increasing Brightness of Head-up Displays) [8] Hunter Lab, "CIE 1976 L*a*b* color scale", pp. 1-4, 2007.

8 : LED (Yongseok Chi: A Synthesis Ratio of Light Emitting Diodes and Quantization Noise for Increasing Brightness of Head-up Displays) [8] Hunter Lab, "CIE 1976 L*a*b* color scale", pp. 1-4, [9] Symon D 'O. Cotton, Colour, colour spaces and the human visual system, School of Computer Science, University of Birmingham, Technical Report, May : ( ) : ( ) : ( ) ~ : LG ~ : SDI PDP ~ : LG ~ : - ORCID : - : Virtual Display, Head Up Display, Head Mounted Display, Wearable Display, Projector, IP-CCTV, LED and Laser.

(JBE Vol. 20, No. 6, November 2015) (Regular Paper) 20 6, (JBE Vol. 20, No. 6, November 2015) ISSN

(JBE Vol. 20, No. 6, November 2015) (Regular Paper) 20 6, 2015 11 (JBE Vol. 20, No. 6, November 2015) http://dx.doi.org/10.5909/jbe.2015.20.6.928 ISSN 2287-9137 (Online) ISSN 1226-7953 (Print) a) A Portable