• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.4
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• pp.320-326
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• 2014

In this paper, the new smart dimming algorithm which is mixed with PWM and PAM control method is proposed for reducing the power consumption of LED TV Backlight. The proposed technique is using the curve characteristics of LED forward voltage and current which is proportionally changing LED forward voltage as changing LED forward current. Therefore, each PWM and PAM control method has different LED forward voltage and current in the same brightness condition. The PWM control method adjusts the brightness of LED TV Backlight by only varying the duty ratio of PWM and constantly sustaining the amplitude of LED forward current and voltage. So, the level of LED forward current and voltage in the PWM control method is relatively high and constant regardless of duty ratio of PWM. On the other hand, the PAM control method adjusts the brightness of LED TV Backlight by directly varying the level of LED forward current. So, the level of LED forward current and voltage in the PAM control method is lowered according to the brightness level. For the above-mentioned reason, the PAM control method has the advantage of reducing the total power consumption of LED TV Backlight at the brightness condition of below 100%, compared with PWM control method. By implementing this characteristic to LED driver circuit with control algorithm in MCU, the power consumption of LED TV Backlight can expect to be reduced. The effectiveness of the proposed method, new smart dimming algorithm, CPWAM(=Conditional Pulse Width Amplitude Modulation), has been verified by experimental results.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1401-1404
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• 2008

Temperature Compensation Method of Local Dimming LED Backlight System is proposed. The luminance levels of the LED backlight are not stable over temperature and time due to the inherent characteristics of the LED. The characteristics of LED backlight are investigated and a temperature compensation method is presented. The image distortion caused by temperature variation of LED block can be effectively compensated by the proposed temperature compensation method.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.2
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• pp.1-6
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• 2005

This paper studies the OF-LED(Optical Fiber-LED) illuminated display board system for energy saving. The OF-LED illuminated display board system has PV module, batteries, charge 8t discharge system and dynamic full color display controller. Both maximum power point tracker (MPPT) and constant current & constant voltage controls (CCVC) are used to govern the charging system. This system. improves the charging efficiency of battery. The system is compact and operates only by PV except the rainy days when the sun is unfavorable. in the system display control and charging-discharging control by on-chip microprocessor are simultaneously carried out. To verify the unposed system, me simulation and experiment results show the operating characteristics with a laboratory prototype.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.9
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• pp.36-43
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• 2013

The prevalence of electronic devices in our modern life is accompanied with the generation of harmonics caused by the nonlinear characteristic load. Especially, the employment of LED have brought the rapid use of SMPS. SMPS is used for supplying the constant DC electric power to the LED display board, but it has a big problem which gives birth of harmonics causing by its high-speed switching. measurement HIOKI 3196 equipment to solve these harmonics were measured. In this study, we are LED Display Board Load Measuring the impedance response with $X_L$ changes for removing harmonics in the measured. And we adopted the suitable passive filter by the impedance response characteristic obtained in the $X_L$ variation experiments. We are trying to deeply the application of passive harmonic filter characteristics that generation in the LED Display Board through EDSA LED simulation.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1149-1151
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• 2007

As a follow-up to our previous work we present in this paper some experimental results on LED light recycling. Specifically we demonstrate for the first time that screen brightness can be increased using our light pipe based light recycling scheme for reallife projection display applications.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1555-1558
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• 2007

In study, we've disigned LGP that have optimized pattern for blue LED. We used to have active area 3.5" of LGP and blue led(6EA) of LUXPIA in Korea. Also, We made Pattern Generation.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1642-1645
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• 2007

The brightness of LED changes according to the current flowing through LEDs. The current mirror was used to drive LEDs effectively. The reference current of the current mirror was usually controlled by the resistor but the size of this resistor is very large and this resistor consumes too much power for high power LED backlight driving. The reference current of the current mirror LED driver was controlled by using flyback converter at small size with low power consumption in this paper. The concept of active current source was presented.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.76-78
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• 2009

A liquid crystal display that does not use color filters is proposed. A backlight unit that employs compartmentalized RGB LED arrays and a lenticular lens array is used instead of the color filters in order to direct RGB LED lights into the RGB subpixels. A design of color-filterless LED backlight and experimental results are presented.

• Journal of the Korean Vacuum Society
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• v.12 no.4
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• pp.235-238
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• 2003

Conventional LED displays use pixels which consist of red, green and blue LEDs of different operation voltages and degradation characteristics. Thus, the circuits are complicated and the display of each color changes independently with the operated time. In order to solve these drawbacks, an LED chip of a short wavelength and an LED lamp with the mixture of red, green, blue fluorescencers and epoxy on the LED chip were studied. The fluorescencers are excited by the light of the LED chip. The LED chip has an active layer of InGaN, a peak wavelength of 408 nm, a FWHM of 13 nm and the CIE index of (0.198, 0.087). White LED lamps were obtained and the CIE index change was observed with the change of the epoxy amount added to the fluorescencers.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.510-512
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• 2009

A volumetric 3D display system based on a rotating two dimensional color LED array is set up. It has a cylinder display space ${\Phi}800{\times}640mm3$ which is composed of 256 slices of pictures in one 3D image with each slice $320{\times}256$ LED pixels. The volumetric image has 4 gray scales and 64 colors. The main structure and working principle of the system is described in detail.