How does the LED display work?
Author:pazen Time:2021-06-10 15:43 Browse(791)
The basic structure of LED is an electroluminescent semiconductor material, which is placed on a shelf with leads, and then sealed with epoxy resin around to protect the internal core wire, so the anti-seismic performance of LED is good. The core part of light-emitting diode is a wafer composed of p-type semiconductor and n-type semiconductor. There is a transition layer between p-type semiconductor and n-type semiconductor, which is called p-n junction. In some semiconductor PN junctions, when the injected minority carriers are combined with the majority carriers, the excess energy will be released in the form of light, thus the electric energy can be directly converted into light energy. When the PN junction is applied with reverse voltage, it is difficult to inject a few carriers/
The basic structure of LED is an electroluminescent semiconductor material, which is placed on a shelf with leads, and then sealed with epoxy resin to protect the inner core wire, so the anti-seismic performance of LED is good.
the core part of LED is a chip composed of p-type semiconductor and n-type semiconductor.

How does the LED display work?

there is a transition layer between p-type semiconductor and n-type semiconductor, It is called p-n junction.
in some PN junctions of semiconductor materials,
when the injected minority carriers are combined with the majority carriers, the excess energy will be released in the form of light, so that the electric energy can be directly converted into light energy.
it is difficult to inject the minority carriers in the PN junction with reverse voltage, So it doesn't emit light.
this kind of diode based on the principle of injection electroluminescence is called light-emitting diode.
it is generally called led.
when it is in the positive working state (that is, the positive voltage is applied at both ends).
when the current flows from the anode to the cathode of the LED, the semiconductor crystal emits light of different colors from ultraviolet to infrared, The intensity of light is related to the current.
energy saving lamp is a kind of special fluorescent lamp.
it is based on the fluorescent powder on the lamp body excited by ultraviolet light.
at present, most of energy saving lamps are gas discharge lamps excited by electronic circuits.
LED is a light-emitting diode, which can be directly ignited by rated voltage, From the perspective of development, it is a new type of energy-saving lamp.
LED display screen is a planar display screen composed of LED lattice module or pixel unit.
due to its advantages of high luminous rate, long service life, flexible configuration, rich color and strong adaptability to indoor and outdoor environment.
since the late 1980s, With the continuous improvement of LED manufacturing technology, it has been widely used in foreign countriesAfter China's reform and opening up.
especially in the 1990s, with the rapid growth of national economy, the demand for information released in public places has become increasingly strong. The emergence of LED display just adapts to this market situation, so the design and manufacturing technology and application level of LED display have been rapidly improved.
in this paper, the development trend of LED display is introducedLED display has experienced from monochrome and two-color graphic display to image display, All the way to today's development of full-color Video display.
great progress has been made in terms of performance (brightness LED display and blue light) and system composition (computerized full dynamic display system).
at present, it has reached the level of ultra-high brightness full-color Video display.
it can be said that it can meet various application conditions Requirements.
its application fields have covered transportation, securities, telecommunications, advertising, publicity and other aspects.
China's LED display development can be said to be basically synchronized with the world level.
so far, it has formed an industry with considerable development potential.
it should be pointed out that.
China's LED industry has not only achieved great success in application technology, but also achieved great success in application technology, Moreover, it has outstanding performance in innovation ability. For example, zql9701 ultra large scale chip developed by Beijing Zhongqing data equipment Co., Ltd. represents the current international level of LED display control circuitCompared with the rapid development of LED display industry in China.
at present, there are too few books and materials about LED display, which is not convenient for designers, manufacturers and maintenance personnel. Therefore, the idea of writing a book on LED display technology came into being. At the invitation of the University of Electronic Technology Press, the book is about the general situation of LED display The related technical problems of LED display, graphic display, image display and video display are describedIn order to make the readers who are engaged in all kinds of LED display screen work can get some useful materials from this book.
in this paper, we hope that the readers who are engaged in all kinds of LED display screen work can get some useful materials from this bookThe LED display screen is a product of various comprehensive applications.
it involves optoelectronics, semiconductor devices, digital electronic circuits, large-scale integrated circuits, single-chip computers, microcomputers and other aspects and methods, and it will take a long time to introduce them, It is easy to dilute the theme.
on the other hand, simple and popular LED display hardware such as integrated circuit and single chip microcomputer has software.
each of the above fields has its own system.
in this book, we can't describe them one by one, we can only display the parts that are directly related to the meaning, instead of pursuing the completeness of each related technology itself; Two, try to adopt simple and popular solutions, and pursue advanced technology..
, for example, in some control circuits,.
can be realized by conventional integrated circuits, and it can avoid the trouble of starting all kinds of related technologies from scratch. In order to achieve the purpose of streamlining the content and highlighting the key points.
the book takes the following two countermeasures in dealing with the technology in related fields: first, focusing on the description of the screen as the main line.
introduces the application of related technology in LED display screen, and does not adopt the device scheme.
the book introduces the application of related technology in LED display screenControl principle of LED electronic display screenThe system consists of special computer equipment, display screen, video input port and system softwareComputer and special equipment: computer and special equipment directly determine the function of the system.
different types can be selected according to the different requirements of users for the system.
the functions of the system are determined by the computer and special equipmentDisplay screen: the control circuit of the display screen receives the display signal from the computer.
it drives the led to emit light to generate pictures, and outputs sound by adding power amplifier and speaker.
the display screen has the following functions: display screen, display screen, display screen, display screen, display screen, display screen, display screen, display screen, display screen, display screen, display screen, display screen, display screenVideo input port: video input port is provided.
the video input port is providedThe signal source can be VCR, VCD, camcorder, etc. it supports NTSC, pal and s_ Video and other formatsSystem software: special software for LED playback is provided.
PowerPoint or es98 video playback software is provided.
system schematic diagram is as follows:(2) system functions the system has the following functions:The computer is used as the processing control center.
the electronic screen corresponds to a certain area of the computer display (VGA) window point by point, the display content is synchronized in real time, the screen mapping position is adjustable, and the size of the display screen can be easily selected at will.
the system has the advantages of simple operation, convenient operation and convenient operationThe display dot matrix adopts ultra-high brightness LED (red and green dual primary colors).
256 gray levels, 65536 color change combinations, rich and realistic colors, and supports VGA 24 bit true color display mode.
the display dot matrix adopts ultra-high brightness LED (red and green dual primary colors)It is equipped with graphic information and three-dimensional animation playing software.
it can play high-quality graphic information and three-dimensional animation.
there are more than ten ways to display information in the playing software, such as covering, closing, opening curtain, color alternation, zooming in and out.
the software can play high-quality graphic information and three-dimensional animationSpecial program editing and playing software can be used.
text, graphics, images and other information can be edited, added, deleted and modified by keyboard, mouse, scanner and other input means.
the arrangement can be stored in the control host or server hard disk.
the program playing sequence and time can realize the integrated alternate playing and can be superimposed with each other.
the program can be edited, added, deleted and modified by using the special program editing and playing softwareIt can receive and display video signals such as VCR and VCDLED video display system:System introduction and features1. Modular design: the circuit design is divided into different modules according to their functions.
each module needs very little connection,It greatly improves the stability and reliability of the system.
the difficulty of debugging and maintenance is greatly reduced.
the reliability is high.
all hardware circuits are imported components.
the quality is high and the reliability is good2. Advanced distributed scanning technology: scanning control technology is used for the scanning of the display part.
the display part is divided into different units and scanned independently.
the signal transmission between each unit is synchronously controlled by the signal latch technology.
the stability of the display is greatly increased.
the display is stable3. Well designed communication interface technology: the communication distance can reach 1000 meters.
it can resist ± 15kV electrostatic discharge impact.
RS-422 special design interface.
greatly improves the reliability of system communication.
this paper introduces the design of RS-422 special interface4. Novel software design: Windows style interface.
rich experience in designing special software.
the software has strong functions and easy operation.
the general display software has a good user interface.
with clear menu window, users can arrange programs at will according to their needs, and can play video, animation text, plug-in messages, etc.
in addition, it can also play animation text, plug-in messages, etc5. Good visibility: the product adopts imported LED chips.
the display screen has the characteristics of high brightness, bright color, large viewing angle, long service life (100000 hours), high stability and fast response6. Easy to install: the display unit board or display unit box is adopted.
according to the user's requirements and application site requirements, the display screen can be arbitrarily assembled into the required size, and it is easy to maintain.
the display screen is easy to installIntroduction and classification of LED electronic display systemIn recent years, LED display market has developed rapidlyIt has been widely used in banks, posts and telecommunications, taxation, airports, stations, securities markets and other trading markets, hospitals, electric power, customs, stadiums and many other occasions that need to be announced and publicizedAt present, LED display screen as an important means of information dissemination has become a symbol of urban information modernization.
with the continuous progress of social economy and the continuous improvement of LED display technology, people's understanding of LED display screen will be more and more in-depth, and its application field will be more and more extensive.
with the continuous improvement of social economy and LED display technology, people's understanding of LED display screen will be more and more in-depthLED is the abbreviation of light emitting diode.
LED display screen is a display device composed of LED arrays.
it adopts low voltage scanning drive.
it has the following advantages: 1, low power consumption, 2, long service life, 3, low cost, 4, high brightness, 5, large viewing angle, 6, long visual distance, 7, many specifications and varieties.
LED display screen is a display device composed of LED arraysLED display products series a, monochrome, color bar display screen, B, computer-controlled digital display screen, C, monochrome graphic display screen, D, three color (red, green, yellow) graphic display screen, e, dot matrix and digital hybrid display screen (Securities screen), F, dual primary color (red, green) multimedia video synchronous display screen, G, three primary color (red, green, yellow) graphic display screen Blue) multimedia video synchronization displayAccording to the display color, LED display can be divided into three colors: single red, single green, red and green dual primary color, red, green and blue. According to the use function, LED display can be divided into graphic display, multimedia video display, quotation display and bar display. According to the use environment, LED display can be divided into indoor display, outdoor display and semi outdoor display. According to the luminous point diameter, LED display can be divided into three types φ 3.0、 φ 3.7、 φ 4.8、 φ 5.0、 φ 0, pH8, PH10, PH16, PH20 and so on.
the results showed that there was no significant difference between the two groupsLED display technology features a, excellent effect: using dynamic scanning technology.
stable picture, no impurity, clear image effect, vivid and diverse animation effect; The video effect is smooth; B. Rich content: it can display text, chart, image, animation and video information; C. Flexible mode: the display mode can be arranged by the user at will; D. Quality assurance: imported luminous materials, high-quality IC chips, noiseless high-power power supply; E. Large amount of information: the information displayed is not limited; F. Easy maintenance: modular design, easy installation and maintenance;Use environment: LED display can be divided into indoor LED display and outdoor LED display according to the use environment.
display color: LED display can be divided into single primary color LED display (including pseudo color LED display).
dual primary color LED display and full color (three primary colors) led display.
according to gray level, it can be divided into 16, 32, 64, 128 and 256 gray level LED displayDisplay performance: LED display screen is divided into text LED display screen and graphic LED display screen according to display performance.
computer video LED display screen, TV video LED display screen and quotation LED display screen, etc.
quotation LED display screen generally includes securities, interest rate, interest rate, etc LED display screen for futures and other purposes.
the basic light-emitting point is in the non market led display screen.
indoor LED display screen can be divided into three types according to the single point diameter of LED Φ 3mm、 Φ 3.75mm、 Φ 5mm、 Φ 8mm, and Φ 10 mm, etc; The outdoor LED display screen can be divided into three parts according to the pixel diameter Φ 16mm、 Φ 19mm、 Φ 22mm and Φ 26mm, etc.
according to the size of the nixie tube used, the market led display can be divided into 2.0cm (0.8inch), 2.5cm (1.0inch), 3.0cm (1.2inch), 4.6cmm (1.8inch), 5.8cm (2.3inch), 7.6cm (3inch) and other LED displays.
the market led display can be divided into two categoriesLarge screen display performance: Shanghai 80000 stadium, Shanghai Volkswagen, Shanghai International Trust and investment company, Shanghai real estate exchange Baoshan Iron and Steel Co., Ltd., etc. when users need to watch less information sources at the same time,
it is suitable to choose single large screen.
but in more complex monitoring fields, such as large-scale post and telecommunication system, road traffic management, energy distribution and transportation, industrial control, 110 alarm, etc., they need panoramic browsing and unified command, It is necessary to choose a large screen splicing system.
the large screen splicing system is no longer affected by the resolution and brightness of a single computer.
for example, a 2 × The resolution of a single computer is 1024 × When the brightness is 500lm, the resolution of the system is 2048 × 1536, and the brightness is 2000lm.
the results show that the brightness of the system is less than 1The splicing system is mainly composed of three parts: large screen projection wall, projector array and control system.
among them, the control system is the core.
at present, there are three types of splicing control systems in the world: Hardware splicing system, software splicing system, hardware splicing system and control system The hardware splicing system is an earlier splicing method.
the functions of the hardware splicing system include segmentation, split screen display and window opening, that is, to display an independent picture with any screen on the base map composed of four screens.
because of the hardware splicing.
the image processing is completely real-time dynamic display, and the installation operation is simple; The disadvantage is that the splicing scale is small, only four screens can be spliced, so it is inconvenient to expand and can not meet the needs of multi screen splicing; The window is fixed to a screen size, and can't be enlarged, reduced or moved.
software splicing system uses software to segment images.
using software method to splice images can flexibly control the special effects of images,If the window is opened at any position; Zoom in and out arbitrarily; The mouse can be used to drag the open window and control the screen wall on the console, which is as convenient as controlling your own display.
the splicing system of software and hardware can integrate the advantages of the above two methods, This system can display multiple RGB analog signals and dynamic graphics of XWindow.
it is specially designed for multi-channel real-time display.
the dynamic display of different windows can be realized through hardware, software and control / public interface.
it has high transparency: image overlay transparent display.
there are 256 levels of transparency, The system adopts parallel frame structure.
it can control up to thousands of projectors to work at the same time.
it has excellent parallel expansibilityThe comparison of projection display wall CRT LCD DLP's current international popular product sizes (diagonal / inch) 41, 44, 51, 72, 84, 100, 120, 150, 50, 60 67 light source 7-inch projection tube bulb.
the general service life (hours) of the bulb is more than 10000 1000 -- 6000 (UHP) 8000 -- 10000 (UHP) gap between screen <0.8mm <0.8mm <0.8mm optical seam (gap between image) 1mm 0.8mm the increase of the number of units used will increase the requirements of the control system, Therefore, it will increase the cost and other functions must be increased, Otherwise, there will be burning effect. There is no such requirement. The color (relative) has the best color reducibility and the worst between them. The lowest brightness (7-inch 170ansi lumen) is higher (above 600ansi lumen) is higher (above 600ansi lumen) convergence. The unit resolution is 640 * 480 / 800 * 600 * 600 / 1024 * 768 / 1280x1024 800 * 600 / 1024 * 768 / 1280x1024 brightness uniformity> 75%> 85% %Computer graphics / video maintenance may focus and color adjustment,When replacing the projection tube, you need to adjust the color and brightness only when replacing the bulb. Single screen: (wall mounted, box type): single screen large screen is generally composed of projector, rear projection screen, metal structure, optical reflection system and heat dissipation systemFunction: mainly used for dynamic video image and computer image display.
just like a large monitor or TV.
advantages: low cost.
the screen size is flexible, generally 72 "(1463mm) × 1097mm),84″(1706mm × 1280mm), 90″(1854mmm × 1396mm), 96″(1950mm × 1463mm), 100″(2032mm × 1524mm), 120″(2438mm × 1828mm), 125″(2508mm × 1874mm), 140″(2845mm × 2134mm), 150″(3048mm × 2286mm),160″(3252mm × Disadvantages: the larger the screen size is, the shorter the lamp life is (about 1000-6000 hours). It can not work continuously for 24 hours (if it has to work 7 / 24 continuously, you need to choose a professional control room projector. The cost is high). The splicing projection wall (large-scale splicing) is composed of multiple projectors, multiple screens, matrix and image processor. It is generally used for high resolution, The unit screen size is generally 72 "(1463mm) × 1097mm).
84″(1706mm × 1280mm), 90″(1854mm × 1396mm), 96″(1950mm × 1463mm),100″(2032mm × 1524mm), 120″(2438mm × 1828mm), 125″(2508mm × 1874mm), 140″(2845mm × 2134mm), 150″(3048mm × 2286mm),160″(3252mm × Generally, LCD or DLP projectors are selected, and imported optical lens screen or domestic scattering screen can be selected as the screen.
in this paper, the design of the projector is introducedAdvantages: 1) large display area.
low cost.
2) unit screen size.
flexible control, easy to control the display area.
2Disadvantages: 1) the larger the unit screen size is.
the larger the rear projection space is required.
2) due to the difference of brightness when multiple screens are spliced together.
it is necessary to select the projector and match the focus between the projector lens and the optical lens screen, so as to achieve uniform brightness between the center of a single screen and the four corners as far as possible, The brightness and color of multiple screens are the same.
3) the lamp life is short.
it is about 1000-6000 hours, which is related to the selected projector.
4) it can not work continuously for 24 hours (if it must work continuously for 7 / 24.
professional control room projector is needed, which has high cost).
.
.
the design of a professional control room projector is necessary
Hot labels
Related topics