• Journal of Institute of Control, Robotics and Systems
• /
• v.22 no.5
• /
• pp.382-388
• /
• 2016

When Flat Panel Display (FPD) is made with backlight module, such as LED TV, it inherently suffers from the non-uniform backlight luminance problem that results in un-even brightness distribution throughout the TV screen. If the luminance of each pixel location of a TV screen as a function of the driving voltage can be measured, it can be used to compensate the non-uniformity of the backlight module. We use a carefully calibrated imaging system to take pictures of a TV screen at different levels of brightness and generate the compensation functions for the driving circuitry to correct the luminance level at each pixel location. Making use of the fact that the luminance of the screen is normally brightest at around the center of the screen and gradually decreases toward the border of the screen, the luminance of the whole TV screen is approximated by a mathematical function of the pixel locations. The parameters of the function are computed in the least square sense by the values of both the pixel luminance sent from the driving circuit and the grayscale value measured from the image taken by the imaging system. To justify the correction system, a simple second order polynomial function is used to approximate the luminance across the screen. When the driving circuit voltage is corrected according to the measured function, the variance of the screen luminance is reduced to one tenth of the one measured from the un-corrected TV screen.

• Journal of the Semiconductor & Display Technology
• /
• v.20 no.4
• /
• pp.62-67
• /
• 2021

In this study, we have successfully developed an unique NVIS Green A compatible LED by combining two technologies. One is white LED made with a black EMC (epoxy molding compound) lead frame. The other is NVIS Green A filter that shields the near infrared region made in the film method. The form factor of the developed NVIS Green A compatible LED was 2.0 × 2.0 × 0.95 mm. And it is possible to satisfy NVIS radiance and color limit specified in MIL-STD-3009 by controlling the concentration of Green A dye and the thickness of the NVIS filter as well as adjusting of color temperature of the white LED. From these results, we are expected that the developed NVIS Green A suitable LED is a promising solution for the weight reduction and the cost reduction of avionic applications.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2017.05a
• /
• pp.555-558
• /
• 2017

In this paper, we designed a power supply AC LED driving device which can display uniform power consumption and light efficiency even when AC power of different size is applied. By setting input voltages and deviations of different sizes, it is confirmed that the electric light characteristics are the same at two input voltages. In addition, according to peak voltage of AC power, improper lighting caused in specific LED section is improved, and LED lighting of all sections is implemented in all commercial AC input voltage.

• Journal of the Semiconductor & Display Technology
• /
• v.17 no.4
• /
• pp.76-79
• /
• 2018

In this paper, we developed a pressure monitoring system using silicon pressure sensor. The pressure monitoring system was developed on the basis of a microcontroller, and a self-developed silicon pressure sensor was applied. The pressure monitoring system outputs the current pressure value via UART communication. In addition, it includes a function of displaying by LED when the preset three-step pressure (low, medium, high pressure) is reached. The silicon pressure sensor used in the pressure monitoring system was set to 0 kPa, 10 kPa, 26 kPa, and the pressure monitoring system was evaluated because the measured maximum pressure was in the range of 100 kPa.

• Journal of the Semiconductor & Display Technology
• /
• v.9 no.1
• /
• pp.67-71
• /
• 2010

Head up display’s cooling system is auto-diagnosed resulting from the external environment. The quantity of heat depending on this Head up display’s cooling system layout determines the speed of FAN for system cooling. In other words, a system’s heat quantity is planned through the air density depending on altitude, the amount of wind in air depending on FAN control condition, and the algorithm that is proportional to delta temperature. To detect the altitude, we use the criteria of delta T, which is determined by the subtracted value of LED junction temperature, and atmospheric temperature that is recorded on the Head up display system. Depending on the classification of delta T value, the altitude section is determined. While we can use GPS as the tool to detect the altitude, we should predict the change of the air density as the altitude alters, and should not just measure the altitude. And the value of delta T is used as the criterion of detecting the altitude for increasing the cooling efficiency of the car’s inner Head up display system with reflecting the speed of the FAN dependent upon the air density. In our theory, altitude is depending on the value of delta T and stabilizing or maintaining the system’s temperature by changing FAN’s rpm depending on determined value of altitude.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.5
• /
• pp.26-33
• /
• 2015

Secondary optical system designed for LED bulb which emits light in all directions was simulated with Energy Star standards. Components of the optical system were LED light source, the cover of the LED bulb and reflector which is to confirm the diffuser plate and LightTools software was used to design the illumination optics. The main points of the secondary optical system design are the location of the LED light source, the shape of the LED bulb cover, the location of the reflection plate, and the scattering properties of the diffusing plate. Mechanism of the LED bulb is that the light emitted from the light source move on to the backward after reflected by the coated light cover from the inside and then the reflected light is scattered by the diffuser plate. The LED bulb was designed to satisfy the standard light distribution and color specifications of the Energy Star(IES LM-79-08).

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.8
• /
• pp.2999-3004
• /
• 2010

In comparison with some other light sources, LED has merits such as long lifetime, pollution free, and high energy efficiency. Lately, due to development of LED with high brightness and capacity, LED, which has been applied in display system only, has applied in the field of lighting system. As power LED for lighting system can be burned out by heat problem, the driving current of power LED has to be controlled below the designed value. In this paper, power LED photovoltaic lighting system, which has the current limitting function, has been described. After photovoltaic power is generated from PV panel. it is charged into a battery. And then, after the charged power is converted to DC24[V] through a boost DC-DC converter, it is supplied to power LED at night. It has been validated by designing and testing of 72[W] power LED lighting system, which includes a PV charger, a boost DC-DC converter and a current limiter for driving power LED.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.5 no.3
• /
• pp.288-293
• /
• 2010

In these information-communication society, the wireless system technologies are increasing to do all things with wireless solution for fast and convenient works. This trend drives ubiquitous solutions which are based on broadband wireless network that gives network connection whenever, everywhere. This paper deals a bookshelf management system using plower line communication and RFID module. This system includes a 900 MHz RFID reader, Passive RFID-Tags, an Atmeg128 microprocessor board attached LED Display Module, and a management PC with GUI Software. This system works well in power line communication, tag reading and LED display, and PC Management Software.

• Proceedings of the IEEK Conference
• /
• 2000.06e
• /
• pp.89-92
• /
• 2000

A wire communication module for PLC controller was developed. This system consists of RF module interface part, RS232 serial communication control part, LED display part and control S/W with GUI interface. RF communication frequency is controlled by PLL controlling and communication rate is also controlled as 1200 and 4800 bps. Communication and control status are displayed on LED. As a S/W part, graphic user interface on Window 95 O.S. was developed. To show the validity of the developed system, severial communication and control of PLC system were experemented.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2009.10a
• /
• pp.1379-1382
• /
• 2009

The 3D display has been used in optical projection technology to connect twenty mini- projectors with seamless image tiling. In this way, we can improve the projected resolution by reducing each project screen and increase projected area by connect several mini-projectors. In this article, the illumination system uses the LED light source, non- telecentric structure and LCOS panel, and it's total length is less than 10 centimeter. It can build a seamless large display by tiling multiple projectors.