What is the working principle of LED color display?
Author:Wang Jinzhu Time:2021-10-14 11:20 Browse(763)
Working principle of LED display screen:
The working principle of LED display screen:
LED is a solid-state semiconductor device, which can directly convert electricity into light.
the heart of LED is a semiconductor chip.

What is the working principle of LED color display?

one end of the chip is attached to a bracket, one end is the negative pole, and the other end is connected to the positive pole of the power supply, so that the whole chip is encapsulated by epoxy resin.
the semiconductor chip is composed of two parts.
one part is p-type semiconductor, In it, the hole is dominant, and the other end is n-type semiconductor, where the main electron is electron.
but when the two semiconductors are connected, a "p-n junction" is formed between them.
when the current acts on the chip through the wire.
the electron will be pushed to the p region, where the electron and the hole compound and then emit energy in the form of photons, This is the principle of LED display light.


LED system composition    computer and special equipment: computer and special equipment directly determine the function of the system.
different types can be selected according to different requirements of users for the system   <
display 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: 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    <
video input port: provide video input port.
the signal source can be VCR, VCR, camera, etc., and support NTSC, pal, s, etc_ Video and other formats   <
system software: special software for LED playback is provided.
PowerPoint or es98 video playback softwareLianchengfa group, a well-known LED manufacturer, provides you with the following reference materials:

1. The main structure of LED display screen (take the more complex synchronous full-color screen as an example)
1. Metal structure frame.
its function is to form the inner frame, which is equipped with various circuit boards such as display unit board or module and switching power supply
2. Display unit: it is the main part of LED display screen, It is composed of LED lamp and driving circuit.
the indoor screen is the unit display board of various specifications.
the outdoor screen is the module box.

3. Scanning control board: the function of the circuit board is data buffer.
it generates various scanning signals and duty cycle gray control signals.

4. Switching power supply: it converts 220 V AC into various DC to supply various circuits.

5 Transmission cable: the display data and various control signals generated by the main controller are transmitted to the screen body by twisted pair cable.

6. Main controller: buffer the input RGB digital video signal.
gray level transformation, reorganize and generate various control signals.

7 Special display card and multimedia card: in addition to the basic functions of computer display card, it also outputs digital RGB signal and line.
field, blanking and other signals to the main controller.
in addition to the above functions, multimedia can also convert the input analog video signal into digital RGB signal (video acquisition).

8. Computer and its peripherals

Fig.1 composition of LED display system

2 Main function module analysis
1. Video broadcasting
through multimedia video control technology and VGA synchronization technology.
various forms of video information sources can be easily introduced into the computer network system, such as broadcast and satellite TV signals, camera video signals, VCD video signals of video recorders, computer animation information, etc,So it can realize the following functions:
support VGA display, display all kinds of computer information, graphics and images.

support all kinds of input methods; Support pal, NTSC and other formats.

display color video images in real time.
realize live broadcast.

relay broadcast broadcast TV, satellite TV and cable TV signals.

real time broadcast (VCR, VCD, DVD, LD) of TV, camera, video disc and other video signals.

it has the function of simultaneously playing left and right pictures and words in different proportions
2 Computer broadcast
Graphic stunt display function: it has the functions of editing, zooming, flowing and animation.

display various computer information, graphics, images and 2 Three dimensional computer animation with superimposed text.

the broadcast system is equipped with multimedia software.
it can flexibly input and broadcast a variety of information.

there are a variety of Chinese fonts and font types to choose from.
at the same time, it can also input English, Spanish, French, German, Greek, Russian, Japanese and other languages.

there are a variety of broadcast modes.
for example: single / multi line translation, single line translation, double line translation, double line translation, double line translation, double line translation, double line translation, double line translation, double line translation and double line translation Single / multi line up / down, left / right pull, up / down, rotation, stepless zoom and so on.

it can edit, play and release notices, announcements and news in real time.
it also has a variety of fonts to choose from.

3. Network function
is equipped with standard network interface.
it can be connected with other standard networks (information query system, information management system, information management system, etc.) Municipal Publicity network system, etc.

collect and broadcast the real-time data of each database.
realize remote network control.

through the network system, you can enter the Internet Network
with sound interface.
the system can be used to control the networkIt can be connected to audio devices to achieve audio-visual synchronization.

4. The screen controller can control the display effect of its corresponding display screen.
it can automatically run a continuous cycle of programs.
according to the given program list, it can get the relevant display data, or it can be manually intervened, The pixel on the screen is directly mapped to the pixel on the corresponding area of the screen controller.

the brightness of the screen can be manually adjusted by the screen controller.
the gray nonlinear correction data suitable for the current environment can be selected, The screen controller can also automatically adjust the brightness of the display screen and select different gray nonlinear correction data according to the ambient brightness through the network system.

the screen controller can adjust the contrast and chroma of the image display.
the screen controller transmits the information to be displayed to the video processing and control unit for video processing.

5 The video processing and control unit
completes the image processing of the display data.
these processes include:
second level gray nonlinear correction, It can be adjusted automatically or manually.

automatic or manual stepless brightness adjustment.

the gray level control system can control the display screen to display 24 bit data of 8 bits for each primary color.
that is, 256 levels of gray level for each primary color.

image noise reduction processing.
to ensure that the image is cleaner and smoother.

image enhancement technology.
image edge enhancement technology.


motion compensation technology.
chroma tone In the system, the brightness of each primary color of a single module can be adjusted respectively,Adjust the color balance, basically eliminate the mosaic phenomenon, all modules and display module brightness consistency is good, monochrome display without visual difference.

the video processing and control unit will process the display information to the communication module for long distance transmission to the display screen.

7 The communication module ensures that the display content of the screen controller can be transmitted to the display screen for a long distance accurately.
the communication module encodes and decodes the transmitted information.
the communication module transmits the displayed information to the data distribution and scanning unit.


3 The main working principle of the display screen is that the LED display screen is usually composed of a main controller, a scanning board, a display control unit and a LED display screen body.
the main controller obtains the brightness data of each pixel of a screen from the computer display card, and then distributes it to several scanning boards, each scanning board is responsible for controlling several rows (columns) on the LED display screen, The LED display signal on each row (column) is transmitted in serial mode through each display control unit of the row, Each display control unit is directly facing the body of the LED display screen.
the work of the main controller is to convert the signal of the computer display card into the data and control signal format needed by the LED display screen.
the function of the display control unit is similar to that of the image display screen, Generally, it is composed of shift register latch with gray level control function.
but the scale of video LED display screen is often larger.
therefore, a larger scale integrated circuit should be used.
the function of scanning trigger is just a link between the preceding and the following.
on the one hand, it receives video signals from the main controller, On the other hand, it transmits the data belonging to the current level to its own display control units,At the same time, the data that does not belong to the same level should be transmitted to the next cascade scanning board.
video signal and LED display data.
the differences in space, time, sequence and other aspects need to be coordinated by the scanning board.
.
in this paper, the scanning board is used to coordinate the video signal and LED display data
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