• 전기전자학회논문지
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• 제22권3호
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• pp.767-773
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• 2018

본 논문에서는 높은 역률을 가지는 단순 구조 LED 구동 직류 전력컨버터를 제안한다. 제안한 전력컨버터는 PFC 부스트 컨버터와 전통적인 플라이백 컨버터를 오직 하나의 전력변환 회로로 병합함으로써 LED 구동 전력컨버터의 구조를 단순화한다. 그리하여 제안한 컨버터는 오직 하나의 PWM 제어기 IC를 이용하여 제어되고 높은 역률과 정출력 전압/전류 및 제작비용의 효율성을 달성한다. 따라서 제안한 컨버터는 LED 조명시스템의 산업 생산과 이용에 적합하다. 본 논문에서는 제안한 컨버터의 동작분석과 설계예시를 간단하게 설명한다. 또한 설계된 회로파라미터들에 근거하여 제작된 프로토타입의 실험결과를 통하여 제안한 컨버터의 동작특성을 입증한다.

• 전력전자학회논문지
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• 제15권1호
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• pp.35-42
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• 2010

본 논문은 고효율의 조명용 LED 구동회로를 위해 LLC 공진형 컨버터를 이용한 2단 구성의 LED 구동회로를 제안한다. 기존의 3단 구성의 LED 구동회로는 LED의 휘도 및 제어를 위해 별도의 비절연형 DC/DC 컨버터를 사용하여 낮은 효율의 문제점을 지니고 있었다. 이러한 문제를 해결하기 위해 제안된 회로는 비절연형 DC/DC 컨버터 단 없이 PFC단과 LLC단으로 총 2개의 단으로 구성하였다. LLC단에서 절연과 LED의 제어 및 휘도 조절 기능이 가능하여 90% 이상의 고효율 동작을 보장한다. 본 논문에서는 제안회로의 동작원리를 설명하고, 모의실험 및 45W급 LED 구동회로를 제작하여 하드웨어실험을 통해 제안회로의 유용성을 검증하였다.

• 한국산학기술학회논문지
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• 제11권8호
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• pp.2999-3004
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• 2010

LED는 다른 광원에 비해 동작수명이 길고, 친환경적이며, 에너지 효율이 높은 장점을 가지고 있다. 최근 LED 기술의 발전으로 인해 고휘도, 고용량의 LED가 개발됨에 따라, 표시장치에만 적용되던 LED를 조명장치에도 적용하는 기술이 확산되고 있다. 조명장치에 적용되는 파워 LED는 발열문제로 인한 소손을 막기 위해 구동전류를 일정한 전류값 이하로 제어할 필요성이 있다. 본 논문은 파워 LED의 구동전류를 설정된 값 이하로 제어하는 전류제 한 기능을 갖는 파워 LED 태양광 보안등 개발에 관한 연구이다. 태양광 발전에 의해 생산된 전력을 DC12[V] 축전지에 저장한 후, 야간에 승압형 DC-DC 컨버터를 통해 DC24[V]로 승압시켜 파워 LED로 공급한다. 태양광 보안등 제어기, 승압형 DC-DC 컨버터, 72[W]급 파워 LED 램프를 개발하여 동작을 확인하고 관련 데이터를 도출함으로써 제안된 시스템의 타당성을 입증하였다.

• 한국위성정보통신학회논문지
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• 제8권4호
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• pp.17-20
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• 2013

본 연구에서는 싸인 보드의 집중도를 올리기 위한 초음파 스피커 시스템의 음성신호이득, 방사패턴과 같은 상태정보 표시를 위한 LED 구동 회로를 소개한다. 초음파 스피커 시스템은 에너지 손실이 적고 음이 멀리 전달된다. 이러한 특징을 지닌 초음파 스피커는 일상생활에서 다양하게 쓰일 수 있다는 점에서 매우 유용하다. 상기 장점을 살려서 제안된 LED 회로는 초음파 스피커 시스템으로부터 인터페이스를 제공받아 선형적인 LED 밝기로써 상태정보를 표현한다. 설계된 회로는 동부 0.35um CMOS 공정을 사용하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1326-1329
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• 2009

In large-area LCD displays, we have developed two new control technologies for high-power LED backlight. The Novel control technology called scanning control and local gray control. In addition, a conceptual display system power management was developed. We have implemented high power-LED module driving system which can achieve power saving and cost down. Finally, we designed LED light-bar module of the side type as a backlight source. It not only achieved light & thin but also reduced the quantity of LEDs.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.1291-1296
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• 2005

In this paper, we prevent a display quality drop for image of characteristics brightness ununiformity depend on LED use to LED vision. It is about that method also a control system development equipped with brightness compensation function of LED vision which is done easily for LED set up of LED vision. Generally, It is calculate driving current value is attended by each brightness to brightness characteristics mathematical function establish by "Y=aX+b", When is doing brightness value for "Y", driving current value for "X", brightness compensation value by using time for "b", characteristics value for "a" ground with characteristics curve of LED. So much, First It is create brightness data of each pixel take a photograph red, green and blue of LED vision. Second It is get average error about each pixel which get average brightness value of entire. Last, It is handle a complicated for about gradationally regulation to color and brightness of image send to LED vision. Also It raise the whole average brightness value of vision adjust for "b" value to solve brightness drop problem of LED using the long time.

• 조명전기설비학회논문지
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• 제27권5호
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• pp.26-32
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• 2013

The LED has the proportional characteristic between the flux of light and its current and has caused voltage-current deviation on production process. Thus the unbalancing of each LED strings current occurred by its characteristic deviation. This unbalancing reduce a uniformity of the flux of light. Therefore, we researched to design method the LED driver based on DSP and the balancing transformer for a LED current balancing. These are applied to 50W LED module consist of 4 parallel strings. We analyzed the reduction of LED currents unbalance by experimental result from each method.

• Journal of the Optical Society of Korea
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• 제16권4호
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• pp.449-456
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• 2012

For two well-known modulation methods, stepwise current modulation (SCM) and pulse width modulation (PWM), the effects of driving current modulation conditions on chromaticity were experimentally investigated in a white LED lighting system. For the experimental implementation of both SCM and PWM, a white LED lighting was fabricated using phosphor converted (PC) white light emitting diodes (LEDs) and a driving circuit module was developed. By using them, the variations of illuminance, color coordinates, and spectrum were evaluated under various forward current conditions. Through the analysis in color coordinates, yellow shift in SCM and blue shift in PWM were observed on chromaticity diagrams with increasing average driving current. In addition, in order to analyze color deviation quantitatively, color distance before and after current increase, and the correlated color temperature (CCT) were calculated. As a result, for the white LED lighting in both modulation conditions, the maximum difference in the calculated CCT was obtained close to 1000 K. It means that careful consideration is required to be taken in the design of illumination systems to avoid serious problems such industrial accidents.

• 조명전기설비학회논문지
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• 제25권12호
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• pp.67-73
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• 2011

A method obtaining position data(x, y) of object accurately is proposed by using a pair of ultrasonic sensors composed of one transmitter and two receivers. And the driving system which controls the light of flat LED lamp locally using array of ultrasonic sensors (3 transmitters and 6 receivers) is developed. As a result, measured values of y are relatively reliable due to its small average of absolute errors of 1.03[cm]. The measured values of x have average error of 8.52[cm], and it is a large value. However, the average error is decreased by 0.65[cm] after applying algorithm for error correction. The experiments to control the light of flat LED lamp locally with algorithm for error correction are carried out. From the result, measured values of x with average error of 0.97[cm] are obtained and they are very good approximations of actual values.

• 조명전기설비학회논문지
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• 제29권12호
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• pp.8-14
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• 2015

An effective way to ensure that LEDs produce wanted light output is to use a current driving topology, because the brightness of LEDs is directly related to their current. However, this topology may lead to the lifetime shortening of a illumination system because over-currents may flow through non-damaged LEDs in case some LEDs are damaged. This paper presents an adaptive current control circuits for LEDs, which protect LEDs in a good state by limiting the driving currents according to the number of damaged ones. The proposed control circuits consist of a simple constant-current driver and a micro-controller which monitors the voltage of LED array without any auxiliary current sensors for fault diagnosis. And the driving current is automatically controlled into 6-levels according to the number of failures.