• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.1156-1159
• /
• 2008

Local dimming driving has advantages in reducing power consumption and improving contrast ratio(CR). In an LED backlight unit(BLU), many small LED blocks are implemented in 2-dimmensional space, and luminance of the blocks is controlled by a local dimming algorithm. However, such a BLU can induce various recognizable artifacts. A new novel algorithm is proposed for exact block luminance calculation to correct local dimming artifacts. Also we discuss modified low-gray-level dimming to achieve much aggressive power saving in a local dimming BLU system.

• Journal of Power Electronics
• /
• v.16 no.4
• /
• pp.1268-1276
• /
• 2016

A triode for alternating current (TRIAC) dimming light emitting diode (LED) driver, which adopts a variable switched capacitor for LED dimming and LED power regulation, is proposed in this paper. The proposed LED driver is power efficient, reliable, and long lasting because of the TRIAC switch that serves as its main switch. Similar to previous TRIAC dimmers for lamps, turn-on timing of a TRIAC switch can be controlled by a volume resistor, which modulates the equivalent capacitance of the proposed variable switched capacitor. Thus, LED power regulation against source voltage variation and LED dimming control can be achieved by the proposed LED driver while meeting the global standards for power factor (PF) and total harmonic distortion (THD). The long life and high power efficiency of the proposed LED driver make it appropriate for industrial lighting applications, such as those for streets, factories, parking garages, and emergency stairs. The detailed analysis of the proposed LED driver and its design procedure are presented in this paper. A prototype of 80 W was fabricated and verified by experiments, which showed that the efficiency, PF, and THD at V_s = 220 V are 93.8%, 0.95, and 22.5%, respectively; 65 W of LED dimming control was achieved with the volume resistor, and the LED power variation was well mitigated below 3.75% for 190 V < V_s < 250 V.

• Journal of the Korea Society of Computer and Information
• /
• v.21 no.5
• /
• pp.127-133
• /
• 2016

In this paper, an intelligent dimming control system is designed and implemented with the human visual response function using CDS sensor, PIR sensor and temperature sensor, etc. The proposed system is designed to detect a moving object by PIR sensor and to control the LED dimming considering the human visual response. Also, the dimming of LED light can modulate on the app, and simultaneously control dimming in real-world environments with smart phone app. A high-temperature warning or a fire hazard information is transmitted to user's smart phone according to sensor values and Data graph are provided as part of data visualization. Connecting the hardware controller, the proposed intelligent smart dimming control system is expected to contribute to the power reduction interior LED, smart grid building and saving home combining with internet of things.

• Journal of Industrial Technology
• /
• v.31 no.A
• /
• pp.95-101
• /
• 2011

According to recent technological developments in high-power LEDs, the stage lighting is one of most important areas to apply power LED system. Moving light for color rendering of stage uses the RGBW(red, green, blue, white) color mixing method. LED moving light system needs to have a wide range of dimming control as enough to operate at very low power. Also LED dimming system should not be induced color-shift and flicker in camera. This paper is experimentally verified the LED Moving Light driving circuit of 200Watt level designed to satisfy the above characteristics which applied the DC current-controlled and PWM mixed dimming method.

• Journal of Industrial Technology
• /
• v.30 no.B
• /
• pp.113-118
• /
• 2010

In this paper, We proposed remote dimming control system for Light Emitting Diode(LED) street light using Power Line Communication(PLC). LED will be used widly by indoor or outdoor lighting because of semi-permanent life and environment restriction. For energy saving of street light, the dimming control system is very necessary and the PLC is a very efficient technique. Thus, in this paper we proposed the remote dimming control system for LED street light using PLC. A performance of the proposed system was validated by experimental results.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.8
• /
• pp.128-135
• /
• 2013

This paper presents a high dimming ratio Power-LED driver IC with high power which is capable of controlling LEDs. In order to accomplish a high dimming ratio LED driver, the preloading inductor current methodology is proposed for the power stage of the proposed method to achieve the fast transient response time during the Power-LED load switching. The information containing the current flowing on the LEDs can be utilized to predict the amount of the current on the inductor. The minimum LED current rising time of existing high dimming ratio Power-LED driver is limited by $3{\mu}s$, however that of the proposed high dimming ratio Power-LED driver is reduced about 1/10. The LED driver is implemented with 0.35um 60V BCDMOS 2-poly 4-metal process. The measurement results show that the proposed LED driver system features the minimum rising time as small as 240ns at the dimming frequency of 1KHz with a 12V of input voltage, nine white LEDs and 353mA of LED current. The LED rising time and power conversion efficiency of the chip are measured to be 240ns and 93.72%, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.8B
• /
• pp.1204-1210
• /
• 2010

In this paper, in order to reduce the power consumption of LCD TV, we present a two-dimensional dimming algorithm for LED BLU(Backlight Unit) using light spread function and a pragmatic implementation method. In conventional two dimensional dimming algorithms, LED BLU is divided into MxN blocks and proper backlight luminance for each block is computed according to input image and used for dimming control. But, LED light of each block is diffused and affects the neighboring blocks so that luminance of each block becomes larger than that of intent. In the proposed algorithm, dimming control values are reduced by the amount of quantity affected by the neighboring blocks using light spread function, resulting in additional reduction of power consumption.

• Proceedings of the KIPE Conference
• /
• 2008.06a
• /
• pp.335-337
• /
• 2008

In this paper, an X-Y channel dimming light emitting diode (LED) backlight with temperature compensation for in LCD TVs is proposed. It shows local dimming effects such as reduced power consumption and high dynamic contrast ratio even with much less number of LED drivers than that of the conventional two-dimensional local dimming method. Moreover, the image distortion caused by temperature variation of LED block can be effectively compensated. The validity of the proposed dimming method is verified by simulation and experimental results based on a RGB-LED backlight of a 32-inch LCD TV.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.26 no.4
• /
• pp.22-27
• /
• 2012

In the study, an XML based platform is presented for LED dimming control. The XML platform is designed in an open architecture, providing with interoperability and scalability. Also, it enables the accommodation of off-the-shelf wired and wireless communication protocols and make it fast and easy to implement various application programs for LED dimming, comparing to the legacy platforms. In the study, a test best has been built for demonstration of the merits of the XML platform with dimming control by responding to the scenario of demand response event. Benefit calculation of the power saving and incentive from demand response shows the applicability and usefulness of the XML platform.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.1
• /
• pp.109-113
• /
• 2011

This paper analyzes the noise sources of an LED lighting module with TRIAC dimming control and proposes an improved EMI filter design for the reduction of conducted noise emission. TRIAC dimming invokes problems of input oscillation and capacitor overvoltage at the lighting module. The proposed double LC filter reduces high noise level from the circuit. The experimental and simulation results show that this approach can make significant contributions to the reduction of conducted noise emission from an LED lighting module with TRIAC dimming control.