LED display Technical Data:
 
     Basic knowledge of LED display screen decades ago, the electronic display is a large bulbs or lighting composition, developed to a later picture tube (CRT), is mainly used in sports venues showing the game, and now the most advanced electronic display is a LED display . Other display technologies such as LCD, mechanical and electrical structure of the class display and lamp display in certain occasions there are some purposes, but the LED display proved to be the most reliable, efficient, energy saving, bright, technically the most to facilitate the achievement.

       LED light technology, the principle that certain semiconductor materials to current conditions in the pass will be issued under specific wavelengths of light, this electricity to light conversion efficiency is very high, for the different materials used for chemical treatment, it can be a variety of brightness and perspectives of the LED. LED display is the LED modules or pixel pipe assembly arranged in accordance with the actual needs of the size of matrix, coupled with dedicated display circuit, DC regulated power supply, software, framework and exterior decoration and so on, shall constitute a LED display. 1, LED displays an overview of what is LED? In some semiconductor materials, PN junction, the injected minority carrier and majority carrier recombination, when will the excess energy is released in the form of light, which converts electrical energy directly into light. PN junction reverse voltage increases, minority-carrier injection is difficult, it is not light. Such use of injection electroluminescent diodes called the principle of production of light-emitting diodes, known as LED. The characteristics of LED light-emitting diode LED is short (Light Emetting Diodeo). Because of its high brightness, fast response, low voltage, power consumption, resistance to vibration, impact resistance, long life, etc., to become indoor and outdoor information display terminals, the main light-emitting device. LED and LED display LED luminous color and light-emitting efficiency and production of LED materials and processes related to the present widely used red, green, and blue three kinds. As the LED voltage is low (only 1.5-3V), can take the initiative and have a certain brightness light-emitting and brightness but also with the voltage (or current) regulation, it is itself resistant to shock, anti-vibration, long life (100,000 hours), so in large display devices, There is no other display LED display with the match. The red and green LED together produced as a pixel is called color-screen or color display screen; the red, green, and blue three kinds of LED tubes put together as a pixel is called tri-color screen display, or Full color. Production of indoor LED screen pixel size is generally 2-10 mm, often used to produce several different color of the LED die into one package, outdoor LED screen pixel size, mostly 12-26 mm, each as elements from a variety of single-color LED composed of a number of common pixels of the finished product, said cylinder, two-color pixel 3 red tube generally composed of two green, three-color pixel cylinder with two red one green one blue component. Whether using LED production monochrome, bi-or tri-color screen, want to display images need to constitute the pixel brightness of each LED's have to be able to adjust the fine adjustment of the degree is to display gray levels. The higher the gray level, showing images of the more delicate, the color the more abundant, and the corresponding display control system is also more complex. General 256-level grayscale images, color transition is now very soft, while the 16-level grayscale color image, color transition boundaries very clear. Therefore, the current call for color LED screen made of 256 Gray. LED light-emitting materials used in the screen have the following several forms: ① LED light-emitting light (or a single lamp) usually by a single LED chip, reflective bowl, metal anode, metal cathode composition, outsourcing has a translucent ring of condenser capacity epoxy resin shell. Can be one or more (different colors) Single-light constitute a basic pixel, due to high brightness, multi-use outdoor display. ② LED dot matrix module constituted by a number of chip light-emitting matrix, encapsulated in plastic case with epoxy resin inside. For the ranks of scan driver, easy to constitute a high-density displays, used for indoor display. ③ SMD-type LED light-emitting light (or SMD LED) is a LED emitting light solder paste form of packaging that can be used indoor full color display, enabling a single point of maintenance, effectively overcome the phenomenon of mosaic. 2, LED display screen LED display classification categories varied in several ways according to the following general categories: (1) by use of the environment is divided into indoor, outdoor and semi-internal display indoor and outdoor area normally from less than 1 square meter to the more than ten square meters, a high point density in the non-direct sunlight or lighting environments, watching from a few meters outside the body does not have sealed waterproof screen capability. Outdoor display area in general from a few square meters to tens or even hundreds of square meters, point density than thin (mostly 1000-4000 points per square meter), brightness in the 3000-6000cd / square meter (toward different brightness different requirements), available at direct sunlight and under the conditions of use, viewing distance of tens of meters outside the screen body has a good wind-resistance capacity of rain and Lightning. Semi-outdoor range of outdoor and indoor screen between the two, with a high brightness can be used under the non-direct sunlight outdoors, screen sealed body have a certain, generally under the eaves or window inside. (2) by color into monochrome, dual-color, three-color (full color) monochrome display is only one color of light-emitting materials, multi-single-red, and in some special occasions can also be yellow-green (for example, funeral ). Dual color screens are generally red and yellow-green light-emitting material composition. 3-color screen is divided into full-color (full color), from the red, yellow-green (wavelength 570nm), blue composition and true color (nature color), from the red, pure green (wavelength 525nm), blue composition. (3) according to the control or use sub-synchronous and asynchronous synchronization mode refers to the basic LED display works the same in a computer monitor, it at least 30 fields / sec update rate corresponds to real little monitor on the map When mapping the computer image, usually gray in color with multi-display capabilities can be achieved by multi-media advertising effectiveness. Asynchronous mode is the LED screen has a storage and auto-playback capability, PC, edited the text and non-gray-scale images via serial port or other network interface incoming LED screen, then auto-play off-line LED screen, generally do not multi-grayscale display capability, primarily used to display a text message, you can multi-screen network. (4) pixel by pixel density or diameter of households classified as internal display LED dot matrix module specifications used in a more unified and are usually classified according to diameter of the pixel blocks are mainly: ∮ 3.0mm 60000 pixels / m ∮ 3.75mm 44000 pixels / m ∮ 5.0 mm 17000 pixels / sqm outdoor screen pixel diameter and pixel pitch is currently no uniform standard, the number of pixels per square meter around 1024 points, 1600 points, 2000 points, 2500 points, 4096 points, and other specifications. (5) by display performance video display can be divided into: general text for the full-color display screen: general as a single color display Photo display: General Quotes for dual-color display screen: general for the digital control or single - color display; 3, LED display screen LED display features a comprehensive understanding of the characteristics in order to select cost-effective LED display, and compared to other big-screen terminal display, LED display screen has the following characteristics.  High brightness: bright colorful outdoor display brightness is greater than 8000mcd/m2, is the only large-scale outdoor all-weather use;  Long life: LED life of up to 100,000 hours (ten years) or more;  View Large: Interior angle can exceed 160 degrees, outdoor viewing angle can be greater than 120 degrees; structure of modular, vary in screen size, as small as less than one square meter large it would amount to hundreds of thousands square meters;  Easy and computer interfaces, supporting software-rich, easy to operate flexible, clear picture quality and stability. Display networking: the use of a single computer can simultaneously control multiple screens display different content, the display can also work offline. Not only can display text and can display graphic images, fonts, font varied. Note: The common types of large-screen display terminals contrast merits of TV wall full-color and larger screen are separated by a sense of low brightness can not be used outdoors, color large, high cost, full-color PDP screen delicate small size and low brightness, short life full-color projector screen can not be delicate and low brightness in outdoor use, the screen by the light unevenly. 4, the basic concept of LED: Light Emitting Diode (LED) is an abbreviation. Single-point diameter (Single dot diameter) refers to a pixel in diameter, the unit usually mm. Pixel (PIXEL): that every single or multiple light-emitting tubes, light-emitting points. Is a screen that can be independently controlled is the smallest unit PIXEL acronym for picture element, in the three primary colors on the screen, pixel consists of three components: red, green, blue, each part by one or several LED composition, theory , namely the regulation of red, green, and blue brightness, you can show any color. Pitch (PITCH) distance from the center of adjacent pixels. The smaller the pitch, visual distances shorter and shorter. Resolution (Resolution) commonly used in digital display devices, said the total number of pixels are generally written in the form of width X high, such as 800X600. Viewing Angle (Viewing Angle) when the observer can see the LED when faced with LED maximum brightness, when the viewer moves left or right to see the brightness would be reduced, when the brightness reduced to half the maximum intensity, this When coupled with the perspective in which move in the opposite direction to get the perspective of the sum, saying that the level of visual angle, vertical viewing angle measured in the same way. LED manufacturers will give the perspective of parameters. Brightness (Brightness) Brightness on any display device are the most important parameters. The brightness of the main unit is called candle (candela), with the CD says that a single LED brightness is usually millicandelas, MCD, which are thousandths of CD, the one square meters of LED brightness combined to get the brightness per unit area, with nits (NITS), said, 1 NITS = 1 CD/m2. The brightness of red, green and blue must balance in order to accurately restore the true color, in other words, LED white to be white, not pink. If you are at the maximum brightness of red, green and blue, mixed-up color is usually not white, in order to get a white (commonly referred to as 6500K color temperature), red, green and blue in the need to reduce the brightness of one or two, in order to obtain the correct white, measurements must be repeated to adjust brightness, white balance, said this process. Visual distance (Viewing Distance) for a variety of display devices, the best viewing distance should be to the human eye can not distinguish between pixels of the minimum distance, this distance is about 3,400 times the distance between two points. TV and computers are usually smaller than the observed distance of this requirement, but can not be an acceptable distance of 1,700 times less than the distance between two points. Gray Scale (Grey Levels), also known as color depth, refers to the number of different brightness, red, green and blue have their own gray, in the full-color system, generally 256-level grayscale, you can create 256X256X256 = 16,777,216 colors, in the PC, known as the 24-bit color, in the LED display system, called 8-bit systems. LED display can show color depends on the number of RGB three-color gray-level, in the standard full-color display for 256 gray-scale, for sports stadiums LED full-color system, 256 gray scale is not enough, can not be accurately recovery to restore the color. Refresh rate (Refresh Rate) screen refresh rate, usually indicated by Hertz (Hz). And the frame rate is different. Frame rate (Frame Rate) screen displays the image frames per second, the amount usually depends on the input signal (25 fps for PAL, 30 fps for NTSC) field frequency (Field) PAL and NTSC half of the frame, because the PAL and NTSC is interlaced, each refresh half-frame display only. Advanced Concepts pure green (Pure green) and true green (true green) over the past 30 years, a variety of colors LED has been developed one after another, starting with red, yellow, yellow-green, blue LED, and a pure green LED in the 90 successive years by the Japanese Asian engineers invented. At this point, manufacturing LED full-color display is possible. Play video LED display must be pure green, yellow, and green to do If, color certainly true that if a pixel where the number of green tube a lot of blue than the red tube and pipe quantity, it is definitely yellow, and green tube , because the brightness of yellow-green is not enough, we must use multiple, but the yellow-green LED low prices. The species commonly known as pseudo-color display. GAMMA correction (gamma correction) This is a through the transformation function to reduce the number of gray scale, resulting in a more realistic environment, color and contrast, full-color color of the actual performance subject to many restrictions, when the night, it must reduce the screen body brightness and color can show at this time would be reduced, therefore, the digital RGB display colors certainly less than the 16M color, in order to solve this problem, require higher levels of gray, 1Bill color system (red, green and blue colors of 1024 ) can be expressed in more realistic colors, because expanded to 256 gray 1024, greatly enriched the number of colors that can be demonstrated. Virtual pixel technology (Virtual Resolution), also known as shared or dynamic pixels pixels will be four times the physical pixel by pixel fast parity parity column and row sub-delivered to four times the physical pixel on the display, the effect of is equivalent to the spacing reduced by half, the cost of basic, compared with the traditional practices, basic did not increase, but it can be done 4 times the original resolution. Consistency (Uniformity) the quality of the picture depends largely on the LED consistency. Consistency problem is that the problems inherent in LED, when LED production. Their brightness, viewing angle, there are other features that are inconsistent in fact, these parameters are distributed in a certain range, the manufacturer of better process control, the smaller the range, choose high-quality vendors to debug LED can reduce the workload of , the human eye for color and brightness very high sensitivity, for differences between the LED is easily missed, especially in the highlight of the display system, this difference is even greater, the designer must use various techniques to eliminate the difference and increase consistency. Chromatic aberration (Colour Shift) LED display by the three-color combination of red, green and blue to produce a variety of colors, but three kinds of color made from different materials, there are differences in perspectives, different LED's spectral distribution are changing, and these differences can be observed is called chromatic aberration. When the bias over a certain angle LED, its color change, the human eye to determine the true color screen capabilities (such as movie screen) than the observations better than computer-generated images. Unit board size (Cell board size) means a cell size of the plate, usually with the unit plate length multiplied by width of expression, said in millimeters. (48 × 244) resolution cell plate (Cell board pixels): refers to a cell plate number of pixels, usually pixel cell plate number of rows multiplied by the number of columns of expression, said.