A: LED display screen is introduced
LED display ( LED display ): also known as electronic display screen or floating word. It is composed of LED dot matrix, through the red or green lamp light out to display text, pictures, animation, video, content can be replaced at any time, each component are display module structure. Usually by the display module, control system and power supply system. Display [1] module is composed of an LED lamp dot matrix, is responsible for light emitting display; control system through the control of the corresponding region of light out, can let the screen to display text, pictures, video and other content, constant dance card is mainly the animated; power supply system is responsible for the input voltage and current to voltage and current display needs.
The LED display can display the change of digital, text, graphics and image; not only can be used for indoor environment can also be used in outdoor environment, has the advantages of a projector, TV wall, LCD screen can not match.
LED by the wide attention and rapid development, with its own advantages as inseparable. To sum up these advantages are: high brightness, low operating voltage, small power consumption, miniaturization, long life, impact resistance and stable performance. LED the development prospect, the current is moving in a higher brightness, higher weather resistance, light density, higher and higher light uniformity, reliability, full color and direction.
LED display superb performance:
Strong brightness in the visible range of direct sunlight screen surface, display content clearly visible.
Super gray control with 1024-4096 gray control, display color more than 16.7M, the color clear, three-dimensional sense of strong.
The static scanning technique using a static latch scanning mode, high driving power, and fully guarantee the brightness.
Automatic brightness adjustment with automatic brightness adjustment function, can get the best playback in different light environments.
Full use of imported large scale integrated circuit, greatly improving the reliability, convenient debugging and maintenance.
All-weather work perfectly adapted to all kinds of outdoor bad environment, anti-corrosion, waterproof, moisture-proof, lightning, earthquake strong overall performance, cost-effective, shows good performance, pixel tube can be used P10mm, P16mm and other specifications.
Digital video processing technology advanced, distributed scanning, modular design \ / constant current static driving, automatic brightness adjustment,
Super bright pure color pixel
Image clarity, no jitter and ghosting, eliminate distortion
Video, animation, graphics, text, pictures and other information display, online display, remote control.
Color and the technology of two, LED
Manufacture of LED material is different, can produce photons with different energies, which can control the LED wavelengths of light or color spectrum, that is. Using the first in the history of LED material is arsenic (As ) GaAs ( Ga ), the positive PN junction voltage drop ( VF, can be understood as light or voltage) is 1.424V, the light emitted by the infrared spectroscopy. Another commonly used LED material for the phosphorus ( P ) GaAs ( Ga ), the positive PN junction voltage is 2.261V, the light is green.
3 based on the two kinds of materials, early LED industrial use of GaAs1-xPx material structure, theory can be produced from infrared to any wavelength within the range of percentage of green LED, X represents the phosphorus element substituted. Arsenic. General LED wavelength color by PN junction voltage can be. One of the typical GaAs0.6P0.4 LED red, orange light LED GaAs0.35P0.65, GaAs0.14P0.86 Huang Guang LED. Due to manufacturing using gallium, arsenic, phosphorus three kinds of elements, so called the LED three elements led. While GaN ( GAN ) blue LED, GaP green LED and GaAs infrared LED, known as the two elements of the luminous tube. At present, the newest technology is a mixture of aluminum ( Al ), calcium ( Ca ), indium ( In ) and nitrogen ( N ) four elements of manufacturing four element material LED four elements of AlGaInN, can cover all the visible and UV spectral range. Light intensity: 4 luminous intensity measurement unit of unit of illuminance ( Lux Lux ), flux unit ( lumen Lumen ), unit of luminous intensity ( candela Candle power ) 5 1CD ( candle ) refers to the complete radiation, in the freezing point temperature, the luminous intensity per 1/60 cm2 area. ( previously referred to 2.2 cm in diameter, mass of 75.5 grams of whale oil candle, burning 7.78 grams per hour, flame height is 4.5 cm, luminous intensity along the horizontal direction ) to 6 1L ( LM) refers to the 1 CD light irradiation at a distance of 1 cm, area of luminous flux of 1 square centimeters of the plane. 7 1Lux ( Lux ) refers to 1L the luminous flux is uniformly distributed in the area of 1 square meters of illuminance. 8 general active luminous body adopts unit of luminous intensity light CD, such as incandescent lamps, LED; reflection or transmission object with the luminous flux unit lumen L, such as LCD projector; and unit of illuminance lux Lux, generally used for photography. The three unit of measurement are numerically equivalent, but need to understand from different angles. For example: if the brightness of a LCD projector ( flux ) of 1600 lumens, the projection to the total reflection screen size is 60 inches ( 1 square meters ), the illumination of 1600 lux, assuming that the light outlet 1 cm from the light source, the light outlet area of 1 cm2, the luminous intensity of light export to 1600CD. But the real LCD projector because of loss and the distribution of light loss, light propagation or transparent film is not uniform, the brightness will be greatly reduced, generally have 50% efficiency is very good. 9 practical use intensity calculation, often with relatively easy mapping data unit or to use. For the LED display the active luminous body generally use the CD / square meters as a unit of luminous intensity, and with the angle of observation as the auxiliary parameter, the equivalent unit of illuminance in Lux screen body surface; the numerical and screen the effective display area is multiplied, get in the best angle of the luminous intensity of the whole screen body, luminous intensity hypothesis the screen for each pixel in the corresponding space constant, this value can be considered as a whole body of the luminous flux of the screen. General outdoor LED display screen shall reach 4000CD / m2 or more brightness can have an ideal result in the sun. Common indoor LED, the maximum brightness of 700 ~ 2000 CD / square meters. The luminous intensity of a single LED to CD as a unit, and is equipped with the angle parameter, it doesn't matter and light intensity of LED color. Single light intensity from several mCD to five thousand mCD. The luminous intensity of LED manufacturers is refers to the LED at 20mA current intensity of light, the biggest point of view and the best location. Package LED shape and LED chip top lens from the top lens determines the location of the LED angle and the light intensity distribution. Generally speaking the same LED angle is bigger, the maximum luminous intensity is small, but in the entire three-dimensional hemisphere cumulative constant flux. 10 when multiple LED closer rule emissions, its luminous sphere are superimposed on each other, causing the light plane luminous intensity distribution is more uniform. In the calculation of the display luminous intensity, according to the LED view and LED emission density, the maximum point manufacturers provide the luminous intensity value is multiplied by 30% to 90% differ, as a single average luminous intensity. Luminescence lifetimes of 11 LED long, manufacturers generally marked for more than 100000 hours, the actual should also pay attention to the LED brightness decay period, such as the most used car taillight UR red tube lighting more than a dozen to a few hours later, brightness is only half of the original. Luminance attenuation material cycle and the production of LED has the very big relations, the four elements in the economic conditions permit should choose brightness slow decay of the LED. Color, white balance: 12 white is mixed according to proportion of RGB color brightness and brightness, when the green light is 69%, the red brightness 21%, blue brightness is 10%, mixed color in human eyes feel is pure white. But the chromaticity coordinates LED RGB color for process reasons can not reach the chromatographic effect, and control of color including the deviation of the color brightness white light, called color. 13 as for full color LED display screen before color matching, in order to achieve the best brightness and the lowest cost, should try to choose colors luminous intensity of LED device is approximately 3:6:1 ratio of pixel composition. 14 white balance requires three of the primary colors in the gray value of the same synthesized under still pure white. The 15 primary colors, color: 16 color refers to the color can synthesize a variety of colors. The color is red, light green, blue, the spectroscopic, three vertices in the table as primary colors wavelength ideal. If the color deviation, can be synthesized color area will reduce, will reduce the triangular spectral table, from the visual point of view, the color will not only have deviation, rich degree reduction. 17 LED issued a red, green, blue line according to the different characteristics of wavelength and can be divided into pure red, purple, orange, orange, orange, yellow, green, green, green, blue and green, blue, purple, blue, orange, green, blue and purple is pure red, pure green, pure cheap blue price a lot. Green is the most important of the three primary colors, because the green occupied the brightness white in 69%, and in the color table center horizontal alignment. So the relationship between color purity and price balance both, green is considered.
Classification of three, LED display
1, according to the color colors can be divided into
The single color display: a single color ( red or green).
Double colors: red and green screen double color, the 256 gray level, can display 65536 colors.
Full color display: red, green, blue three primary color, full color display 256 gray scale can display about sixteen million kinds of color.
2, according to the classification of display devices
LED digital display: display device for the 7 segment digital tube, suitable for making the clock screen, interest rate screen, electronic display screen digital display.
LED dot matrix display: display device is composed of many homogeneous alignment of light emitting diode matrix display module, suitable for broadcast text, image information.
LED video display: display device is composed by many light-emitting diodes, can display video, animation and other video files.
3, by using occasions classification
Indoor display: light, small, generalΦ 3mm-- Φ8mm, display the general area of a few to tens of square meters.
Outdoor display: the general area of dozens of square meters to hundreds of square meters, high brightness, can work under the sun, wind, rain, with waterproof function.
4, according to the classification of light spots and pitch diameter
Indoor screen (in diameter ): Phi 3mm, Phi 3.75mm, Phi 5mm,
Outdoor screen (by spacing points): PH10, PH12, PH14, PH16, PH20, PH25, PH31.25, PH37.5 ... ...
5 display mode is static, horizontal rolling, vertical scrolling and page display. Single block module control drive 12 ( can control up to 24 block ) 8X8 matrix, 16X48 matrix (32X48 matrix ), is a single block of MAX7219 ( or PS7219, HD7279, ZLG7289 and 8279 other LED display driver module ) 12 times ( 24 times )! Can use "cascade" means any large dot matrix display. Show good effect, low power consumption, and the cost of using MAX7219 circuit lower.