Dimming 기능을 이용한 LED 평판 조명의 광학 특성 평가 및 시뮬레이션 분석

채성기(Sung Gi Chae),이윤철(Yoon Chul Lee),정동환(Dong Hwan Jung),김강호(Kang Ho Kim),조용익(Yong Ick Cho) 한국조명·전기설비학회 2011 한국조명·전기설비학회 학술대회논문집 Vol.2011 No.5월

기존 일반 조명을 대체 할 광원으로 LED 조명이 최근 이슈가 되고 있다. 더욱이 LED 조명의 가장 큰 장점인 에너지 절감 효과를 극대화 시키는 방법으로 실내·외 조명에서 Dimming Control에 대한 관심이 높아지고 있다. 이에 본 논문에서는 DIALUX 조명 분석 소프트웨어를 이용해 실내 환경에서 전류 값을 조정해 LED 평판 조명을 Dimming한 조도 Simulation값과 조명 분석 소프트웨어의 Dimming Function을 활용한 조도 Simulation 값의 상관관계를 살펴본다. 또한 Dimming에 따른 색 특성이 변화하는 문제를 파악하기 위해 Dimming에 따른 Spectrum 변화를 측정하여 조명의 전류별 색 특성을 분석하였다. Recently Issue came to the LED luminaires replaced by Conventional Lighting. Furthermore, There is a rising interest on LED Dimming Control for Indoor and Outdoor Lighting because of High Energy Saving effect. In this paper, we are finding out the Research of Dimming illuminance Simulation Value by adjusting the LED Flat Luminiaires Current in the Indoor Environment and illuminance Simulation Value by adjusting Illumination Analysis Software’s Dimming Function. In order to finding the problem of Color Shift by Dimming control, we measure the spectrum of LED Flat Luminaires and analysis Color Characteristic of Illumination Current grade.

디지털 조광 기법을 사용한 LED 가시광통신 시스템

김혜수(Hea-Su Kim),염정덕(Jeongduk Ryeom) 대한전기학회 2019 전기학회논문지 Vol.68 No.10

Depending on the conditions of the transmission data, the luminous flux changes in the visible light communication(VLC) system using light emitting diode(LED)s. Therefore, it is difficult to properly implement the lighting environment required by users, because of flicker or difficulty in maintaining the proper level of dimming. In this study, we proposed a new digital dimming technology using white LEDs to compensate for the increasing level of dimming caused by luminous flux of LEDs for data transmission, so that it can maintain the constant level of dimming. And we developed a VLC system using this technology. In the proposed digital dimming technology, the dimming level of dimmable LEDs and the variation in dimming level caused by the LEDs for data transmission are converted into binary values. Hence a new dimming level is created from their differences. The fluctuation of the dimming level due to the transmitted data signals is adjusted real-time in this technology. The dimmable LEDs and data LEDs are operated independently in the developed VLC system. In addition, by using bidirectional communication with LEDs for request signals, the transmitter and the receiver are synchronized easily and the multiple data transmission is possible. In order to verify the validity of this technology, we carried out the experiments to measure temperature by the sensor and transmit the measured temperature data using the developed system. From experimental results, rates of dimming variation of less than 2% have been achieved in every dimming level of over 10% using this technology. and the VLC system enabled telemetry for temperatures from - 55°C to 125°C.

소형 모바일 디스플레이의 Local Dimming 백라이트를 위한 영상 컨트라스트 향상 기법

정진영(Jin-Young Chung),윤기방(Ki-Bang Yun),김기두(Ki-Doo Kim) 大韓電子工學會 2009 電子工學會論文誌 IE (Industry electronics) Vol.46 No.4

본 논문에서는 대형 TFT-LCD 장치에서 소모전력 개선방안의 하나로 사용되는 Local Dimming 백라이트 제어방식을 휴대단말기와 같은 소형 디스플레이에 적용하고자 이에 적합한 영상 컨트라스트 향상기법을 제안한다. 대형 디스플레이뿐만 아니라 소형 디스플레이 장치로 널리 각광받는 TFT-LCD의 광원인 백라이트 LED의 배치는 기존에 측면조사 구조로써 Global Dimming 방법이 사용되어졌으나 근래 진보된 기술을 통해 액정 후면에 배치, Local Dimming 방법이 제안되면서 입력영상을 블록단위로 분할 처리해야할 필요성이 대두되고 있다. 즉, 분할된 블록의 영상이 어두울 경우 해당 백라이트 LED의 공급전류를 감소시켜 명암대비를 극대화시킴과 동시에 소모전력량을 감소시키는 방법이다. 본 논문에서는 입력영상을 같은 크기의 블록단위로 분할한후 각 블록 내 화소정보를 분석하여 밝기성분(Y)에 대한 히스토그램과 평균, 표준편차 등의 정보를 획득하여 블록단위로 독립적인 컨트라스트 향상과정을 수행함으로써 영상정보를 통한 1차 컨트라스트 향상을 실현하고 동시에 블록단위결과 정보를 Local Dimming을 조절하는 백라이트 제어부로 전달하여 광원제어를 통한 2차 컨트라스트 향상과 동시에 전류소모 감소 목표를 실현하고자 한다. This paper presents the image contrast enhancement technique suitable for local dimming backlight of small-sized mobile display while achieving the reduction of the power consumption. In addition to the large-sized TFT-LCD, small-sized one has adopted LED for backlight. Since, conventionally, LED was mounted on the side edge of a display panel, global dimming method has been widely used. However, recently, new advanced method of local dimming by placing the LED to the backside of the display panel and it raised the necessity of sub-blocked processing after partitioning the target image. When the sub-blocked image has low brightness, the supply current of a backlight LED is reduced, which gives both enhancement of contrast ratio and power consumption reduction. In this paper, we propose simple and improved image enhancement algorithm suitable for the small-sized mobile display. After partitioning the input image by equal sized blocks and analyzing the pixel information in each block, we realize the primary contrast enhancement by independently processing the sub-blocks using the information such as histogram, mean, and standard deviation values of luminance(Y) component. And then resulting information is transferred to each backlight control unit for local dimming to realize the secondary contrast enhancement as well as reduction of power consumption.

실내 멀티홉 VLC환경에서 디밍을 적용한 파워 성능 비교

김주석,이민정,김경석,Kim, Joo-Seok,Lee, Min-Jung,Kim, Kyung-Seok 한국인터넷방송통신학회 2017 한국인터넷방송통신학회 논문지 Vol.17 No.5

본 논문에서는 멀티 홉 VLC 환경에서 디밍 제어를 이용한 각 변조 방식의 전력 성능을 분석 하였다. 성능을 분석하기 위해서 VLC기반 실내 멀티 홉 시스템을 구성하였으며, OPPM과 VPPM의 두 가지 변조 방식 기법을 적용하였다. 시뮬레이션은 송신 전력과 수신 전력을 고려하여 각 변조기법의 dimming 제어 및 홉 수에 따라서 수행하였다. 그 결과, 변조에 따른 송신 전력 및 수신 전력에서, dimming이 증가함에 따라, OPPM은 VPPM보다 적은 전력 성능을 갖으며, 수신 전력 대 홉 수 및 dimming이 50 % 일 때, 홉 수가 증가하고 거리가 길수록 VPPM 및 OPPM의 수신 전력은 급속히 감소하는 것으로 나타났다. Visible light communication (VLC) offers communication function in addition to illumination. Because the signal communication capacity per cable is 1,000 times compared to the power line communication (PLC), optical fiber is being advertised as the basis of the information and communication. Also dimming control of LED is an important component needed to provide energy savings and quality of life. This study configured multi-hop VLC system model in a building using optical fiber and analyzed the power performance of two of modulations using dimming techniques. The transmission power and received power were used to compare the power performance in multi-hop VLC environments.

Backlight dimming based on saliency map acquired by visual attention analysis

Ahn, Yong Deok,Kang, Suk-Ju Elsevier 2017 Displays Vol.50 No.-

<P><B>Abstract</B></P> <P>Displays have been used in various applications from mobile phones to tablets, and the low power consumption is one of their most important factors. Backlight dimming is the most promising technique to achieve this because it significantly reduces the display power by controlling only the transmittance of liquid crystal. This paper proposes a new backlight dimming algorithm using visual attention analysis. Conventional algorithms have a serious saturation error in some images when performing backlight dimming, thereby degrading image quality. In contrast, the proposed algorithm analyzes image characteristics based on the saliency map, which considers human visual attention. It then truncates the meaningless information of the saliency map using an adaptive saliency level selection approach and calculates the maximum amount of saturation error that humans will not perceive. In addition, the proposed algorithm defines the objective function and computes the optimal starting gray level in that function to calculate the saturation error. Simulation results show that the proposed algorithm using the adaptive saliency level selection approach performs best. In addition, the average peak signal-to-noise ratio of the proposed algorithm was up to 3.762 dB higher than that of the conventional algorithm while slightly increasing the power consumption.</P> <P><B>Highlights</B></P> <P> <UL> <LI> It uses the saliency map based on the human visual attention for backlight dimming. </LI> <LI> It estimates the allowable saturation error based on the histogram to reduce the complexity after determining a valid saliency level. </LI> <LI> It effectively controls the saturation error by preserving the perceptual image quality while significantly reducing the power consumption. </LI> </UL> </P>

조광제어에 의한 LED램프의 광특성 변화 분석

장인현(In-Hyun Jang),김유신(Yu-Sin Kim),최안섭(An-Seop Choi) 한국조명·전기설비학회 2010 조명·전기설비학회논문지 Vol.24 No.10

Until now, dimmable fluorescent luminaires has been widely used for dimming systems, and LED is currently attracting attentions as a alternative lamp due to environmental problem issues. LED, one of eco-friendly high efficiency lamp, has advantage that dimming is easy than fluorescent luminaire. But there have been not enough research on technical development and application for LED dimming. Therefore, to analyze luminous quantity of dimmable LED, the illuminance, color temperature, luminance, and current were measured in the whole range of dimming. In the results of this study, the dimmable LED of various types showed a similar trend in the changed luminous quantity by dimming.

선택적 충전방식 전하펌프를 사용한 LED 램프 조광구동 기술

김재현(Jaehyun Kim),윤장희(Janghee Yun),염정덕(Jeongduk Ryeom) 한국조명·전기설비학회 2013 조명·전기설비학회논문지 Vol.27 No.9

A new LED lamp driving technology with a charge pump instead of a conventional DC-DC converter is proposed. The proposed driving technology is used to control the LED lamp with digital dimming. The power loss in the zener diodes is reduced because the charging process of the capacitors is selectively controlled according to the digital control signal. From the experimental results, when dimming four LED lamps simultaneously, the average driving circuit efficiency of 89% is obtained, regardless of the dimming level. White light with color temperature over a range of 2800∼7200K was produced by dimming control of red, green, blue and amber LED lamps with the proposed driving circuit. The characteristics of the driving circuits can be changed depending on the characteristics of the R, G, B, and A LED lamps. The efficiency of the driving circuits up to a maximum 89% can also be obtained depending on the combination of LED lamps. The driving technology with digital dimming control for LED lamps proposed in this paper would be effective for obtaining high efficiency in LED driving circuits and remote control of LED lamps using digital communications.

Human Visual System-aware Dimming Method Combining Pixel Compensation and Histogram Specification for TFT-LCDs

( Jeong-Chan Jin ),( Young-Jin Kim ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.12

In thin-film transistor liquid-crystal displays (TFT-LCDs), which are most commonly used in mobile devices, the backlight accounts for about 70% of the power consumption. Therefore, most low-power-related studies focus on realizing power savings through backlight dimming. Image compensation is performed to mitigate the visual distortion caused by the backlight dimming. Therefore, popular techniques include pixel compensation for brightness recovery and contrast enhancement, such as histogram equalization. However, existing pixel compensation techniques often have limitations with respect to blur owing to the pixel saturation phenomenon, or because contrast enhancement cannot adequately satisfy the human visual system (HVS). To overcome these, in this study, we propose a novel dimming technique to achieve both power saving and HVS-awareness by combining the pixel compensation and histogram specifications, which convert the original cumulative density function (CDF) by designing and using the desired CDF of an image. Because the process of obtaining the desired CDF is customized to consider image characteristics, histogram specification is found to achieve better HVS-awareness than histogram equalization. For the experiments, we employ the LIVE image database, and we use the structural similarity (SSIM) index to measure the degree of visual satisfaction. The experimental results show that the proposed technique achieves up to 15.9% increase in the SSIM index compared with existing dimming techniques that use pixel compensation and histogram equalization in the case of the same low-power ratio. Further, the results indicate that it achieves improved HVS-awareness and increased power saving concurrently compared with previous techniques.

ECO2에서 자연채광에 따른 Dimming-control의 에너지 절감 효과 표현 방법

윤재우(Jae Woo Yoon),박소민(So Min Park),심지수(Ji Soo Shim),송두삼(Doo Sam Song) 대한설비공학회 2024 설비공학논문집 Vol.36 No.6

ECO2에서 자연채광에 따른 Dimming-control의 에너지 절감 효과 표현 방법

윤재우,박소민,심지수,송두삼 대한설비공학회 2024 설비공학 논문집 Vol.36 No.6

본 연구에서는 건물에너지 절감을 위해 많이 활용되고 있는 자연채광에 따른 디밍제어의 에너지 절감 효과를 국내 건물에너지 성능 평가프로그램인 ECO2 프로그램에서 표현하는 방법을 제안하고, 이를 구현하기 위해 조명에너지 관련 입력값인 조명밀도의 보정계수를 산정하였다. ECO2 프로그램에서 조명에너지의 분석은 자연채광에 따른 조도 변화에 상관없이 실내 조명 대수에 따른 조명밀도[W/m2]로 고정하여 분석하기 때문에 디밍제어에 따른 조명에너지 감소를 표현할 수 없다. 따라서 본 연구에서는 ECO2 프로그램의 조명에너지 평가 방식 중 입력치 방식이 조명밀도 입력값만으로 조명에너지를 계산하는 점을 이용해 디밍제어를 적용할 때의 조명밀도를 산출하였다. 먼저, RELUX 시뮬레이션을 통해 대상 공간에 유입되는 자연채광을 분석하고, 자연채광의 유입 정도에 따라 인공 조명의 대수를 줄이는 인공 조명 설계를 진행하였다. 자연채광의 유입을 고려한 조명밀도는 계절 및 시간에 따라 변화하기 때문에 이를 단일 값으로 조정하기 위해 계절별 맑은 날씨와 흐린 날씨의 비율을 사용하였다. 본 연구 방법을 사용하여 계산된 최종 조명밀도를 ECO2 프로그램에 입력하여 디밍제어를 적용할 경우 최대 58.6%의 조명에너지 절감률을 확인하였다. 이후 디밍제어를 적용한 조명밀도와 본래 조명밀도 간의 비율을 활용하여 조명밀도에 대한 보정계수를 산정하였다. ECO2 프로그램에 조명밀도를 입력할 때, 대상 공간이 디밍제어를 사용한다면 본래 조명밀도에 본 연구에서 산정한 보정계수를 곱하여 입력하면 디밍제어에 따른 조명에너지 절감 효과를 표현할 수 있다. 본 연구는 자연채광에 따른 디밍 제어의 에너지 절감 효과를 ECO2 프로그램에서 표현하는 방법을 제안하는 것이 주된 목적인만큼 본 연구에서 제시한 연구 방법과 보정계수의 개념은 ECO2 프로그램을 이용하여 자연채광, 디밍제어를 통한 조명에너지의 절감 효과를 정량적으로 평가하고자 하는 연구자, 설계자들에게 유용하게 활용될 수 있을 것으로 사료된다. 본 연구의 방법론을 사용하여 보정계수를 산정할 수 있으며, 범용성을 갖기 위한 추가적인 변수를 고려한다면 자연채광에 따른 디밍제어의 에너지 절감효과를 보정계수를 통해 쉽게 표현할 수 있을 것으로 판단된다. 추후 연구에서는 건물에너지 관점에서 디밍제어에 따른 조명에너지의 절감이 냉난방 부하를 얼마나 줄일 수 있을지에 대한 검토를 진행하고자 한다. The objective of this research was to devise a methodology for quantifying the lighting energy conservation benefits afforded by dimming controls in daylight-responsive buildings, utilizing the ECO2 program. Initially, the influx of natural light into the designated area was quantified via RELUX simulation, allowing for the tailoring of artificial lighting levels at each location to correspond with the fluctuating density of daylight across different seasons and times of day. Through employing varying proportions of natural illumination during both clear and overcast conditions throughout the year, the artificial lighting intensity was accordingly modulated. Upon implemention of this approach, the maximum achievable lighting energy efficiency through dimming control was identified to be 58.6%. Furthermore, correction coefficients for the established ECO2 lighting intensity were determined by comparing the lighting intensities with and without the implementation of dimming control. Hence, by integrating these calibrated lighting intensities that account for dimming controls into daylighting environments, the energy-saving potential can be effectively depicted in ECO2.