1,720,962 research outputs found
Boost Integrated Flyback AC-DC Converter with Valley Fill Circuit for LED Light Bulb
No full textIn this paper, the boost integrated flyback converter derived AC-DC converter for the indoor Light Emitting Diode (LED) lamp application is proposed. The valley fill circuit is employed in the boost integrated flyback converter, which reduces voltage stress of storage capacitor. Under universal input voltage operation, the 120Hz output current ripple caused by the input line voltage is reduced through applying the valley fill circuit. The detailed features of the converter are analyzed. The prototype of 6W/24V AC-DC converter for indoor LED lamp application is implemented. The experimental results verify the reduction of 120Hz current ripple and high power factor (PF) in indoor LED drive system
An X-Y Channel Dimming LED Backlight with Temperature Compensation for LCD TVs
No full textIn 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 twodimensional 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
New X-Y Channel Driving Method for LED Backlight System in LCD TVs
No full textThis paper proposes a novel RGB-LED (light emitting diode) backlight system, for 32” LCD TVs, accompanied by a new X-Y Channel drive method in which its row and column switches control the individual division screen. This proposed driving method is able to produce division drive effects such as image improvement and reduced power consumption. Not only that, the number of converter needed in this method, that is 1 with 4*(m+n) switches, is much fewer than that of cluster drive method, that is 4*(m*n)
New X-Y Channel Driving Method for LED Backlight System in LCD TVs
No full textThis paper proposes a novel RGB-LED (light emitting diode) backlight system, for 32” LCD TVs, accompanied by a new X-Y Channel drive method in which its row and column switches control the individual division screen. This proposed driving method is able to produce division drive effects such as image improvement and reduced power consumption. Not only that, the number of converter needed in this method, that is 1 with 4*(m+n) switches, is much fewer than that of cluster drive method, that is 4*(m*n)
A new dual sustaining driver used two-different energy recovery circuits for large-sized plasma display panels (PDPs)
No full textA new dual sustaining driver used two-different energy recovery circuits for a large-sized plasma display panels (PDPs) is proposed. The proposed sustaining driver has two H-bridge inverters to be used in splitting a panel into two. Two different energy recovery circuits (ERCs) are employed to compensate energy for charging or discharging the panel. When PDPs with the two divided panels are driven by the proposed driver, there are good uniformity in gas discharge and reduction of power consumption due to the two different ERCs used in charging and discharging the panel. As a result, the proposed sustaining driver has low conduction loss, diminished switching loss of all main power switches and decrease of reactive power consumption for recovering energy. Moreover, production cost can be reduced because of one simplified ERC for discharging the panel and no additional driving circuits. To verify operation of the proposed circuit, experimental results will be shown by using 42-inch panel
Average Current Controlled X-Y Channel Driving White LED Backlight System for 46" LCD TV
No full textA novel white-LED (light emitting diode) backlight system for 46"LCD TVs which involves the average current controlled X-Y channel driving method is proposed, which is composed of 1 converter and row and column channel switches. In the conventional X-Y channel driving driven with a constant voltage source, the driving current of LED increases because the threshold voltage of LED decreases when LED temperature goes up. To maintain the luminance of backlight constant, the average current controlled X-Y channel driving will be employed. Finally the results are confirmed by experimental results
A novel adaptive dimming technique with X-Y channels for LED backlight system of LCD TVs
No full textA novel adaptive dimming technique with X-Y channels for light emitting diode (LED) backlight system of LCD TVs is proposed. It has matrix structured LED modules with row and column switches to control the brightness of individual division block. It shows local dimming effects such as reduced power consumption and high dynamic contrast ratio with even using much fewer number of LED drivers of proposed method than that of conventional local dimming method. Therefore, low cost and compact design of LED drivers can be achieved. This paper also contains a new adaptive dimming algorithm and image compensation technique for proposed system
A study on luminescence and discharge characteristics of EEFL (External Electrode Fluorescent Lamp) driven by square wave
No full textEEFL can be driven by square wave driving method. A square wave is applied directly to both ends of EEFL by cascaded multi-stage full-bridge inverter. The various current shapes of lamp are achieved by various inductors between lamp and inverter. In this paper, it is newly investigated that the area of current directly influences the luminance. Furthermore, the 3-level square wave is considered to drive EEFL with self-discharge characteristics. The highest luminance efficiency is achieved by properly controlling the rate of self-discharge usage
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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