LED display panels use matrix addressing techniques to organize the light emitting elements or pixels into a number of rows and columns with each pixel at an intersection of a particular row and a particular column. A light emitting device (LED) display is typically supplied with data addressed from graphical memory location in accordance with a column-major display. The LED display illuminates pixels on a column basis by providing sourcing and sinking currents to diodes in the display. An LED display is typically made up of various dots arranged in a matrix pattern having rows and columns. The dots are usually called pixels where the pixels are made up of several LEDs. Illuminating the pixel requires activating an intersecting row and column thereby providing a closed current path that includes the pixel to be illuminated. The individual LEDs emit light of three basic colors: red, green and blue. Typically, each pixel is composed of at least one LED of each color. In LED displays, one dot is formed by utilizing a plurality of cannon ball-shaped LED lamps each having different luminescent colors. The intensity of the LEDs is usually controlled by controlling the current to the individual LEDs. This is sometimes referred to as controlling the drive to an LED. A pixel can produce a specific perceived color by varying the drive to the three colors of LEDs that comprise the pixel. By controlling the current drive to each of the LEDs that makes up a pixel and in turn controlling each of the pixels that make up a matrix of pixels, an LED display device is capable of displaying a plurality of colors and light intensities so as to realize, for example, a multi-color display. As the resolution of displays increase, the number of pixels in each row and column also increases and the amount of time available to illuminate each pixel decreases. As the illumination time decreases, each pixel must be driven with a larger current to provide a pixel intensity that maintains acceptable image intensity and viewing characteristics. Dot-matrix LED display devices among other kinds of display device are relatively long life and easy to provide a large screen panel. A typical LED display device includes a plurality of digit sections. Each of the digit sections includes a plurality of LED segments in an array for providing illuminated displays of selected alphanumeric characters.

Video displays manufactured using clusters of red, green and blue light emitting diodes (LEDs) as pixels can be divided into modular enclosures and open frames. Modular Enclosure screens are fabricated in housings or frames which contain the processing, power distribution and cable assemblies required to drive the LED clusters which are either grouped on large printed circuit boards (PCBs) or encapsulated in a single housing. The fronts of these screens are covered with louvers to block sunlight which diminishes the video screens apparent contrast. Open Frame screens are designed to allow some transparency through the use of a slat system or a net system. In a slat system the LED clusters are on long PCBs. In the net system the LED clusters are mounted to a section of netting. An LED alphanumeric display can be built upon a printed circuit board that will serve as a substrate for the display and its associated circuitry. For purposes of interconnection, leads for power and intelligence can be brought out from one side of the board for insertion in a socket, another board, or some other receptacle. A matrix display panel used in highway message boards and in advertising boards includes a printed circuit board containing a matrix of LED lamps, another printed circuit board containing electronic parts for driving and controlling the matrix of LED lamps, and a housing having a matrix of through-holes to receive the LED lamps. In operation, the LED lamps thus arrayed are selectively turned on in response to control signals so as to display information consisting of characters, numerals, and graphics. The features and functionality of a LED array display board have becomes more enriched. Scrolling, blinking, built-in character formats are just some basic functions. With the advent of LED capable of emitting blue light rays with high intensity or luminance, there have been developed in recent years full-color LED display devices or apparatus of a large size which can realize high visibility even in the open air. More powerful LED array display board even has a multi-color display. The resolution is enhanced by reducing the dot size and has the LED packed more closely.

As light-emitting diodes have long life expectancy, high tolerance to humidity, low power consumption and minimal heat generation. LED display panels are widely used now throughout the world in all manner of situations to create images for visual displays in a variety of applications including communication and visual display devices. LED array display board is a popular instrument for commercial usage. Many banks, shops and cinemas are willing to install one piece of it because of its versatility. LED array display board can be very bright and eye-catching. Display signs used for advertising or for displaying direction or other information to motorists have an important feature in common. They should be eye-catching and their information should be easy to absorb. In advertising, a signboard made of an LED display generally standing at a conspicuous location, such as a bustling road, is widely used. The LED display comprises a plurality of LEDs controlled by special hardware and software to perform moving images on a screen thereof to attract the attention of passersby. The LED array display board is used in a bank to show the current stock market value, currency exchange rate and interests rate. It can also be used in a shop to tell people the prices and other commercial information. The size of the LED array also becomes larger and larger. The smallest LED array starts with a single line text display. But some huge LED array display boards can be taller than a man and have a multi-line text and even graphics display. LED display systems used for large-scale merchandising, architectural, stage, and theatrical displays are known as curtain displays, which typically are viewed by an audience at a distance of more than 50 meters. A plurality of LEDs mounted on such a display support structure is arranged in a grid, or matrix, at geometrically predetermined positions. The LED luminescence is projected to viewers as images in response to signals received in accordance with data sent from a controller. LED's are becoming increasingly popular as indicators in electrical and electronic devices. Because they are much more reliable than indicator lamps previously used, there is little need to install them in sockets designed to allow ready replacement. Many electronic systems, such as data networks, have displays that indicate the status of conditions in the system.

Display technology pervades all aspects of present day life, from televisions to automobile dashboards to laptop computers to digital cameras. Cathode-ray tubes (CRTs) used to dominate display applications in the 10-40 inch (diagonal) display size. CRTs, however, have many disadvantages including weight, lack of ruggedness, cost, and the need for very high driving voltages. Flat panel displays have become important elements in electronic products. At the present time, liquid-crystal displays (LCDs) have become dominant in display applications because of high display quality, small volume occupation, lightweight, low voltage driven and low power consumption. However, the cost of such displays is a significant factor. In addition, active matrix displays require a substantial power consumption since this type of display utilizes backlighting. Displays based on organic light emitting devices (OLEDs) have the potential for substantially reducing the cost of computer displays. OLEDs are emissive displays that provide an alternative to other types of light emission, such as vacuum fluorescence, plasma, inorganic electroluminescense, and inorganic light emitting diodes. LCDs fail to provide the bright, high light output, larger viewing angles, and high resolution and speed requirements that the large-screen display market demands. By contrast, OLED technology promises bright, vivid colors in high resolution and at wider viewing angles. In general, organic light-emitting diode displays have advantages of light emission, high luminous efficiency, wide viewing angle, fast response speed, high reliability, full color, low-voltage drive, low power consumption, and simple fabrication, making them a frequent choice in device configuration.

The organic light emitting diode is a photoelectric device which can convert the electric energy into optical form in high converting efficiency and is usually used in an indicating lamp or a displaying panel. Organic light emitting diodes (OLED) relies upon thin-film layers of materials coated upon a substrate. OLEDs are constructed on a transparent substrate coated with a transparent conducting material, such as Indium tin oxide (ITO), one or more organic layers and a cathode made by evaporating or sputtering a metal of low work function characteristics. The organic layers are chosen so as to provide charge injection and transport from both electrodes to the electroluminescent organic layer (EL) where the charges recombine emitting light. The driving method for the OLED includes a passive type and an active type, the active type is suitable for achieving a large-screen and high-definition display in light of aspects involving a material, a life, and crosstalks. This active type requires thin film transistor (TFT) driving, and a TFT array applying low-temperature polysilicon or amorphous silicon (a-Si) is drawing attention for this use. OLEDs are increasingly used in a variety of applications as discrete light-emitting devices or as the active element of light-emitting arrays or displays, such as flat-panel displays in camcorders, telephones, laptop computers, pagers, satellite receivers, cellular phones, calculators, and the like.