LEDs are widely valued and rapidly developed, and are inextricably linked to their own advantages. These advantages are summarized as follows: high brightness, low operating voltage, low power consumption, miniaturization, long life, shock resistance and stable performance. LED's development prospects are extremely broad, and the established company Shanghai Xingma Electronics, as the industry leader, plays a key role in the early development of the industry. At present, LEDs are moving toward higher brightness, higher weather resistance, higher luminous density, higher uniformity of illumination, reliability, and full color.
First, the type of Shanghai Xingma LED display:
1. According to the color classification, the single primary color display: single red or single green; two-color display: red and green double primary colors, 256 gray levels, can display 65536 colors; full color display: red, green, blue three primary colors, The 256-level grayscale full-color display can display more than 16 million colors.
2, according to the composition of the pixel unit classification digital display: display pixels for the 7-segment digital tube, suitable for making clock screen, interest rate screen, etc.;
Graphic display: display pixel is a dot matrix module , suitable for playing text and image information;
Video display: The display pixel is composed of many light-emitting diodes, which can display various video files such as video and animation.
3. According to the location of use, the indoor display screen is classified: the light-emitting point is small, the pixel spacing is dense, and it is suitable for close-range viewing;
Semi-outdoor display: between indoors and outdoors, not rainproof, suitable for information guidance at the threshold;
Outdoor display: large luminous point, large pixel spacing, high brightness, can work in the sun, with wind, rain and water resistance, suitable for long distance viewing.
4. According to the driving method, there are static, horizontal scrolling, vertical scrolling and page turning display.
Second, the types and advantages and disadvantages of LEDs used in the display of the horses According to the classification of the display screen, the pixel LEDs used can also be divided into the following types:
1. Advantages of dot matrix module: low cost, mature processing technology and stable quality; disadvantages: poor control of brightness and color consistency, prone to Marseg phenomenon;
2, the advantages of straight plug light: color consistency is better control, pixel spacing can be freely adjusted according to needs; Disadvantages: red, green and blue mixed color is not good, angle is not large, it is not easy to control the consistency of the angle, processing is easy to appear Uneven, uneven, easy to displace;
3, the advantages of the patch: display color, color mixing effect, angle consistency, etc. are the best; disadvantages: packaging, processing and other high costs;
Third, Xingma display LED packaging technology requires different application positions to use different specifications of the display, different displays need different technical requirements of LED devices, then the display LED with the technical requirements, the following different The classification is explained one by one:
1. SMD LED for indoor display.
The SMD LEDs for indoor display screens are further divided into “three-in-one†and “three-in-oneâ€, among which the former is used for relatively low-cost, and the display requirements are not high, and the latter has better display effect and relatively lower cost. High, the following is mainly to explain some "three in one";
1, brightness:
The first thing to consider is the proper proportion of the brightness of the product. At present, the red, green and blue brightness of most full-color displays are matched by 3:6:1 (that is, the red brightness of a pixel is 30%, the green is 60%, blue). The proportion of color accounts for 10%); in general, the package manufacturers and upstream chip manufacturers almost all test products according to 20mA, but the real application to the display, almost no current is driving the LED lights, in general The red, green and blue LEDs are different in the material of the wafer. They are not proportional to the heat, luminescence and brightness attenuation in actual use. Generally, the red attenuation ratio is smaller, the blue-green attenuation is larger, so in order to To ensure that the display life is relatively long, the designer will generally lower the blue-green drive current than red; for example: if the red is driven by 18mA, the green is driven by 15mA, and the blue is driven by 12mA, according to the IV-If relationship of the LED chip. :
Roughly we can figure out the actual brightness of the LEDs needed, the relationship between red, green and blue is:
R: 3÷90%
G: 6÷75%
B: 1÷60%
At the same time, the brightness should be binned. The purpose of the binning is to make the display screen not to let the naked eye see the difference in brightness. Generally speaking, the brightness difference of the human eye can be more sensitive. The difference is 30%. Equipment test error and installation mechanism error, design splitting is better according to 10%~20%.
2, color:
According to the optical effect, the white light is decomposed into a plurality of colors and gradually transitioned through the prism, and the colors are red, orange, yellow, green, cyan, blue, and purple, which is the visible spectrum. The human eye is most sensitive to red, green and blue. The human eye is like a three-color receiver system. Most of the colors can be synthesized in different proportions by red, green and blue. Similarly, most of the monochromatic light can be decomposed into red, green and blue.
This is the most basic principle of colorimetry, that is, the principle of three primary colors. The three primary colors are independent of each other, and no one of the two primary colors can be combined with the other two colors. Red, green and blue are the three primary colors, and the three colors are the most widely synthesized. The red, green and blue primary colors are added in different proportions to form a mixed color called additive color mixing. The three primary colors are three colors that are independent of each other, and neither of them can be produced by mixing other two colors.
The addition of different proportions of the three primary colors to obtain a color is called additive color mixing. The law is:
Red + green = yellow red + blue = purple blue + green = blue red + blue + green = white display LED best color matching is: red 620-630nm, green 520-530nm, blue 465-475nm, of course This range can also be reduced according to actual needs, such as red with 3nm as a file and blue-green with 2.5nm as a file.
Angle: In fact, the larger the angle, the better, but the more important is that the angle is not just big, but also the angle curve should be full and smooth, red, green and blue should be consistent, otherwise the display will be good. After that, some locations will display dark areas, or a certain color will be particularly bright or very dark;
3, electrical parameters LED electrical parameters are mainly expressed in the forward voltage (vf) reverse current (Ir) and anti-static (ESD), generally used for display screens are driven by 5v DC power supply constant current, so: LED Vf Generally, the consistency is not required to be too high, as long as the control is within a reasonable range (generally red 1.8-2.2v, blue-green 3.0-3.4v); ESD is generally the bigger the better, because ESD is everywhere, so LED The larger the ESD is, the less likely it is to make a display screen. The reverse current requires Vr=5v, Ir≦10uA.
Outdoor display with elliptical in-line LED
LEDs for outdoor display screens generally use elliptical structure in-line lamps. Compared with LEDs for indoor display screens, outdoor elliptical lamps mainly have horizontal and vertical angles at the angle of illumination. Generally, the display screen is outdoors. The horizontal viewing range is relatively large, and the vertical viewing range is relatively small;
Generally speaking, the lateral angle of the LED of the outdoor display is about 110 degrees, and the longitudinal direction is about 50 degrees. Because the angle of the direct insertion lamp has many factors, the main performance is as follows:
(1) The shape and appearance of the package of the LED;
(2) the cup structure of the bracket;
(3) the wafer and its structure;
(4) the refractive index of the encapsulating glue;
(5) consistency of material quality;
(6) packaging process (ie, the height position of the wafer);
Therefore, the angle of the LED for outdoor display is more difficult to master, not only requires good design, but also has a good process design and quality control level.
With the continuous improvement of technology, the requirements of display screens will be higher and higher, of course, the requirements for LED packaging technology will be equally high.
Shanghai Xingma Electronics Co., Ltd. specializes in providing various LED electronic screen solutions. Mr. Wang
LED entry must see, LED industry secrets
In recent years, with the Beijing Olympic Games, the Shanghai World Expo, and the Guangzhou Asian Games, LED display screens can be seen everywhere. The LED display can display changing numbers, texts and graphic images; it can be used not only in indoor environments but also in outdoor environments, and has the advantages that projectors, TV walls, and liquid crystal displays cannot match.