LED display price, specifications, how to calculate the size and so on
Author:Liao Luqun Time:2021-09-10 15:46 Browse(709)
Hengguang color helps you answer:
Hengguang color helps you answer:
1. Led and LED display materials
1. The luminous color and luminous efficiency of LED are related to the material and process of making LED. At present, red, green and blue (R, G, b) are widely used.

LED display price, specifications, how to calculate the size and so on

due to the low working voltage of LED (only 1.5-3V).
it can actively emit light with certain brightness, The brightness can be adjusted by voltage (or current), and it is shock resistant, vibration resistant and has a long service life (100000 hours), so there is no other display mode that can match the LED display mode in large-scale display equipment.
the display screen with red and green LED as a pixel is called two-color screen or color screen; The display screen with red, green and blue LED tubes as one pixel is called three color screen or full color screen.
the pixel size of indoor LED display screen is generally 2-10 mm.
several kinds of LED chips that can produce different primary colors are often packaged into one. The pixel size of outdoor LED display screen is mostly 12-26 mm, and each pixel is composed of several monochrome LEDs, The common finished product is called pixel tube. The two-color pixel tube is generally composed of 3 red and 2 green, and the three color pixel tube is composed of 2 red, 1 green and 1 blue.
whether the LED is used to make monochrome, two-color or three color screens.
to display an image, the brightness of each LED that constitutes the pixel must be adjustable, The fine degree of adjustment is the gray level of the display screen.
the higher the gray level is.
the more delicate the image is, the richer the color is, and the more complex the corresponding display control system is.
the higher the gray level is, the more complex the display control system isGenerally, the color transition of 256 level gray images is very soft, while the color transition boundary of 16 level gray images is very obvious.
therefore.
Color LED displays are required to be 256 level gray.

2 The LED light-emitting materials used in display screen have the following forms:
① LED light-emitting lamp (or single lamp) is generally composed of a single LED chip.
reflective bowl, metal anode and metal cathode, which are wrapped with epoxy resin shell with light transmission and concentrating ability.
one or more single lamps (of different colors) can be used to form a basic pixel.
due to the high brightness, the, It is mainly used for outdoor display.

② LED lattice module consists of several chips to form a luminous matrix.
it is encapsulated in a plastic shell with epoxy resin.
it is suitable for row and column scanning drive.
it is easy to form a high-density display, Most of them are used for indoor display.

③ SMD LED is the package of LED light-emitting lamp in the form of soldering.
it can be used for indoor full-color display, which can realize single point maintenance and effectively overcome mosaic phenomenon.

2 Classification of LED displays
1 there are many types of LED displays.
they are generally classified in the following ways:
(1) according to the use environment, they are divided into indoor, outdoor and semi outdoor
the indoor screen area is generally less than 1 square meter to more than 10 square meters, the point density is high, and they are used in non direct sunlight or lighting environment, and the viewing distance is several meters away, The screen body does not have the ability of sealing and waterproof.
the outdoor screen area generally ranges from several square meters to dozens or even hundreds of square meters.
the outdoor screen area is generally from several square meters to tens or even hundreds of square metersThe point density is relatively sparse (mostly 1000-4000 points per square meter), and the luminous brightness is 3000-6000cd / square meter (different orientations, different brightness requirements). It can be used in direct sunlight, and the viewing distance is tens of meters away. The screen has good wind, rain and lightning protection ability.
the semi outdoor screen is between outdoor and indoor.
it has high luminous brightness, It can be used outdoors without direct sunlight, and the screen body is sealed to a certain extent, generally under the eaves or in the window.

(2) it can be divided into monochrome according to color.
dual primary color, tri primary color (full color)
monochrome refers to the luminous material with only one color, mostly single red, It can also be used in some special occasions (such as funeral home).
the dual primary color screen is generally composed of red and yellow green luminescent materials.
the three primary color screen is divided into full color.
it is composed of red, yellow green (wavelength 570nm), blue and true color, and it is composed of red, pure green (wavelength 525nm), (3) according to the control or use mode, it can be divided into synchronous mode and asynchronous mode.
the synchronous mode means that the working mode of LED display screen is basically the same as that of computer monitor.
it can map the computer image at the update rate of at least 30 fields per second, and usually has the ability of multi gray color display, It can achieve the effect of multimedia advertising.
asynchronous mode means that the LED display has the ability to store and play automatically.
the edited text and non gray images on the PC are transmitted to the LED display through the serial port or other network interfaces,And then the LED display screen automatically plays off-line. Generally, it has no multi gray display ability, and is mainly used to display text information, It can be connected with multiple screens.

(4) divided by pixel density or pixel diameter
because the specifications of LED dot matrix modules used in indoor screens are relatively uniform, the pixel diameter and pixel spacing of outdoor screens are generally divided as follows: ∮ 3.0mm 60000 pixels / m2 ∮ 3.75mm 44000 pixels / m2 ∮ 5.0mm 17000 pixels / m2 There is no uniform standard.
according to the number of pixels per square meter, there are about 1024, 1600, 2000, 2500, (5) according to the display performance, it can be divided into
video display screen: generally full color display screen
text display screen: generally single primary color display screen
Graphic display screen: generally double primary color display screen
quotation display screen: generally digital tube or single primary color display screen<
Third, the characteristics of LED display screen
comprehensive understanding of the characteristics of LED display screen.
is to select high cost-effective LED display screen. Compared with other large screen terminal displays, LED display screen mainly has the following characteristics.

high brightness: rich and bright colors.
the brightness of outdoor display screen is more than 8000mcd / m2, which is the only large-scale display screen that can be used outdoors all day large viewing angle: the indoor viewing angle can be greater than 160 degrees, and the outdoor viewing angle can be greater than 120 degrees
modular structure: the screen area can be large or small,As small as less than one square meter, as large as hundreds or thousands of square meters; Easy to interface with computer, rich supporting software, convenient and flexible operation, The screen is clear and stable.

Screen Networking: a microcomputer can control multiple screens to display different contents at the same time.
the screen can also work offline.
it can display both text and graphics.
the font and font are varied.

note: it is common to see large-scale display terminals compared with
screen types
advantages
disadvantages
advantages TV wall
full color, large area
screen has a sense of separation, low brightness, can not be used outdoors, large color difference, high cost
PDP
full color, fine screen
small area, low brightness, short life
projector
full color, fine screen
low brightness, can not be used outdoors, uneven light reception of screen.

IV Basic concept
LED: abbreviation of light emitting diode.

single dot diameter refers to the diameter of a pixel.
unit is usually mm.
pixel: refers to the light-emitting point composed of each single or multiple light-emitting tubes.
is the smallest unit on the drawing surface that can be independently controlled.
pixel is the abbreviation of picture element.
in the three-dimensional space On the primary color display screen, the pixel is composed of three parts: red, green and basket. Each part is composed of one or several LEDs. Theoretically, by adjusting the brightness of red, green and blue respectively, any color can be displayed.

pitch is the center distance of adjacent pixels.
in this paper, the color of the primary color display screen is analyzedThe smaller the space is.
the shorter the viewing distance is.

resolution is usually used in digital display devices.
represents the total number of pixels, which is usually written in the form of width x height, such as 800x600.
viewing angle
when the observer is facing the LED, the maximum brightness of the LED can be seen.
when the observer moves left or right, the brightness will be reduced, When the brightness is reduced to half of the maximum brightness, the sum of the angle at this time and the angle obtained by moving in the opposite direction is called the horizontal viewing angle, The vertical viewing angle is measured in the same way.
the manufacturer will give the parameters of LED viewing angle.

brightness is the most important parameter in any display device.
the main unit of brightness is candela.
it is expressed by CD. The brightness of a single LED is commonly used as millicandelas, MCD, that is, one thousandth CD, to add the brightness of a square meter of LED, In other words, the white of the LED must be white, not pink.
if the red, green and blue are at the highest brightness.
the mixed color is usually not white, in order to get white (commonly known as 6500k color temperature), the brightness of the LED must be balanced, The brightness of one or two of the red, green and blue must be lowered. In order to obtain the correct white, the brightness must be measured and adjusted repeatedly, which is called white balance.

viewing distance
for various display devices.
the brightness of the red, green and blue must be adjusted repeatedlyThe best observation distance should be the minimum distance that the human eye can't distinguish pixels, which is about 3400 times of the point spacing.
the observation distance of TV and computer is usually less than this requirement.
but the acceptable distance should not be less than 1700 times of the point spacing.

gray levels
also known as color depth.
refers to the number of different brightness, Red, green and blue have their own gray levels, which are generally 256 levels in the full-color system, and can produce 256 x 256 x 256=16777216 colors, which are called 24 bit color in PC and 8-bit system in LED display system.
the number of colors that can be displayed by LED display depends on the gray level of RGB three colors.
256 levels in the standard full-color display, for the LED full-color system of stadiums and gymnasiums, 256 grayscale is not enough to restore the color accurately.

refresh rate
the update rate of the display screen.
it is usually expressed in Hertz.
it is different from the frame rate.

the number of image frames per second displayed by the display screen.
it usually depends on the input signal (25 FPS for pal, 30 FPS for NTSC)
field frequency
half frame of PAL and NTSC, because pal and NTSC are interlaced scanning, only half frame of image is displayed every refresh.

advanced concept
pure green and true green have been used for the past 30 years.
the image of PAL and NTSC is interlaced scanningAll kinds of color LED have been developed one after another, first of all, red, yellow, yellow green, blue LED and pure green LED were invented by Japanese engineers in the 1990s.
so far.
it is possible to make LED full-color display screen.
the LED display screen for playing video must be pure green.
if it is made of yellow green, the color is certainly not true. If there are many green tubes in a pixel, More than red and blue tubes, it must be yellow and green tubes, because the brightness of yellow and green is not enough, so multiple yellow and green LEDs must be used, but the price of yellow and green LEDs is low.
this kind of display screen is commonly known as pseudo color screen.

gamma correction
this is a way to reduce the number of gray levels through the transformation function.
so as to produce a color and contrast closer to the real environment, The actual color of full-color screen is limited by many factors. At night, the brightness of the screen must be reduced, and the color that can be displayed will be reduced. Therefore, the color of digital RGB display must be less than 16m color. In order to solve this problem, a higher level of gray level is needed. 1bill color system (1024 levels of red, green and blue) can show more real color, because the gray level is expanded from 256 to 1024, It greatly enriches the number of colors that can be displayed.

virtual resolution technology is also called shared pixel or dynamic pixel.
the pixels that are 4 times of the physical pixels are quickly sent to the physical pixels for display according to the odd and even columns and odd and even rows in 4 times, and the effect is equivalent to reducing the spacing by half. Compared with the traditional method, the cost is basically not increased, But it can achieve 4 times of the original resolution.

uniformity
the quality of the whole picture largely depends on the consistency of the LED.
the quality of the whole picture depends on the consistency of the LEDThe problem of consistency is inherent in LEDs.
when LEDs are produced,
their brightness.
viewing angle and other characteristics are actually not unified. If these parameters are distributed in a certain range, the better the manufacturer's process control is, the smaller the range is. Selecting LEDs provided by high-quality manufacturers can reduce the workload of debugging, and human eyes are quite sensitive to color and brightness, It's easy to detect the difference between LEDs, especially in the highlight display system. Designers must adopt various technologies to eliminate the difference and increase consistency.

color shift
LED display screen is composed of red, green and blue colors to produce various colors.
however, the three colors are made of different materials, and the perspective is different, The spectral distribution of different LEDs is variable, and the difference that can be observed is called chromatic aberration.
when the LED is viewed from a certain angle,
its color changes, The ability of human eyes to judge the color of real pictures (such as movie pictures) is better than that of computer-generated pictures.

cell board size
refers to the size of a cell board.
it is usually expressed by multiplying the length of a cell board by its width, in mm.
(48 × 244)
cell board resolutions:
refers to the number of pixels in a cell board.
it is usually expressed by multiplying the number of rows of pixels in a cell board by the number of columns.
(for example: 64 × 32)
pixel density
also known as lattice density.
usually refers to the number of pixels per square meter of the display screen.
the number of pixels per square meter of the display screen
The maximum power consumption per sqm per square meter per hour.
usually refers to the power consumption when the display screen is all white.
because we adopt the capacity increasing design in the power supply design.
therefore, the maximum power of the power supply will not be reached when the display screen is full load, It plays a good role in protecting the display screen.

weight (kg)
usually refers to the weight of the screen per square meter (including power supply, power supply, etc.) However, it does not include the weight of the frame.

communication distance
the distance between the operating platform (computer) and the screen.
generally, the transmission of 8-core network cable is no more than 130m.
the optical fiber transmission is between 500m and 1300m.

support mode
the English full name of VGA is video graphic array.
that is to say, display graphics Image array, commonly known as graphics card interface.
VGA supports the simultaneous display of 16 colors or 256 grayscales at a higher resolution of 640x480.
at the same time, 256 colors can be displayed at a resolution of 320x240, Therefore, even if the resolution is low, the image is still vivid.
due to its good performance, VGA has quickly become popular.
manufacturers have expanded on the basis of VGA, such as increasing the video memory to 1m and making it support higher resolution, such as 800x600 or 1024x768. These expanded modes are called VESA (Video Electronics Standards Association),Video Electronic Standards Association's super VGA mode, referred to as SVGA, now the graphics card and monitor support SVGA mode.
whether it is VGA or SVGA.
the connection used is a 15 pin trapezoidal plug, which transmits analog signals.

v. calculation method of display size.

1. Calculation method of indoor display.

(1) give the specific data of the screen (length, width, width, width) A. example: what is the size of the screen Φ The screen is 5.8m long and 2.6m wide.

B. first of all.
clear Φ The technical parameters of 5 screens are 488 × 244mm, unit board resolution 64 × 32
C. calculate the number of unit boards used.
the number of boards used for screen length or width=the length or width of pre made screen △ the length or width of unit board
the number of boards used for screen length: 5.8m × 1000 △ 488=11.89 ≈ 12
the number of plates for screen width: 2.6m × 1000 △ 244=10.65 ≈ 11
D. calculate the actual screen size.

actual screen length or width=unit board length or width × Number of blocks for screen length or width
actual screen length: 488 × 12=5856mm, i.e. 5.856m
actual screen width: 244 × 11=2684mm, i.e. 2.684m
E. screen area: 5.856m × 2.684=15.72 (M2)
note: generally, the external frame size of the cleaning screen is 5-10cm on each side based on the screen size.

F. the resolution of the screen=the number of panels used × The resolution of the screen=(12 × 64) ×( eleven × 32)
(2) only the area of the screen is givenNo length and width.

A. example: make a screen with an area of 9 m2.
what is the screen specification Φ 5 (refers to the diameter of the pixel).

B. If only the area is given,
we need to calculate the length and width by ourselves.
we can calculate by the ratio of length to width of 4:3 or 16:9.
in this way, the picture effect is good.
(here 4:3 is taken as an example)
C. The theoretical screen length is the square root of length=(area △ 12) × 4
width=(square root of area 12) × 3
that is: length=3.46M
width=2.60M
D. length and width have been calculated.
the calculation below is shown in the example in (1).

2. Calculation method of outdoor display screen.

(1) the specific data (length and width.
area) of the screen are given.

A. example: the outdoor full-color screen of P20 is about 10m in length.
6m in width.
B, The specification of unit box (box length and width) is 1280 × 960mm, resolution 64 × 48
C. calculate the number of boxes.

the number of boxes used for screen length or width=the length or width of pre made screen △ the length or width of unit box
the number of boxes used for screen length: 10M × 1000 △ 1280=7.8123 ≈ 8
number of boxes for screen width: 6M × 1000 △ 960=6.25 ≈ 6
D. calculate the actual screen size.

actual screen length or width=box (specification) length or width × Number of boxes for screen length or width
actual screen length: 1280 × 8=10240mm, i.e. 10.24m
actual screen width: 960 × 6=5760mm, i.e. 5.76m
E. screen area: 10.24mm × 5.76=158.9824 ≈ 158.98 (M2)
F. resolution of screen=resolution length and width of box × Length and width of box=(64 × 10) ×( forty-eight × 6)
(2) only the area of the screen is given.
There is no length and width.

A. example: if you make a P20 outdoor full-color screen, the area is about 50 square meters.

B. If you only give the area.
we need to calculate the length and width by ourselves.
we can calculate it by the ratio of length and width of 4:3 or 16:9.
in this way, the picture effect is good.
(take 4:3 as an example)
C. The theoretical screen length is the square root of length=(area △ 12) × 4
width=(square root of area 12) × 3
that is: length=8.16m
width=6.12m
D. the approximate length and width can be obtained.
the following calculation reference example (1).

VI. the brightness calculation method of display screen
take full color screen as an example.
generally, the balance ratio of red, green, blue and white is 3:4:1
the brightness of red LED: brightness (CD) / m2 △ points / m2 × 3 (white balance ratio accounts for 30%) / 2
brightness of green LED: brightness (CD) / m2 / points / m2 × 6 (white balance ratio accounts for 60%)
brightness of blue LED: brightness (CD) / m2 △ points / m2 × 1 (white balance ratio accounts for 10%)
(1) the brightness of a single tube is calculated according to the known brightness of the whole screen.

for example, the density of 2500 dots per square meter.
2R1G1B, the brightness of 5000 CD / m2, then:
the brightness of red LED is 5000 △ 2500 × 0.3 △ 2=0.3cd=300mcd
the brightness of green LED is 5000 △ 2500 × 0.6=1.2cd=1200mcd
the brightness of blue LED is 5000 △ 2500 × 0.1=0.2cd=200mcd
brightness per pixel: 0.3 × 2 + 1.2 + 0.2=2.0 CD=2000mcd
(2) calculate the brightness of the whole screen when the brightness of a single tube is known
For example, take p31.25.
Riya tube as an example.

the main die specifications of HSM display screen
Red
Green
hsm-ph-a + (Riya)
180-440mcd
1020-2400 MCD
because of the white balance brightness ratio Red: Green: blue=3:6:1; The ratio of white balance is based on the brightness of the green tube to other tubes.
so it is as follows:
from the Red: Green=3:6, the brightness of the green tube is twice that of the red tube, that is, the brightness of the red tube is 2400 (blue) × 2=1200mcd, and because there are two red tubes in the four red, green and blue tubes, the brightness of a single red tube is 1200 / 2=600mcd.
from the green: blue=6:1, the brightness of the green tube is six times that of the blue tube, That is, the brightness of blue tube is: 2400 (blue) △ 6=400mcd, 1 luminous pixel=2 red tube + 1 green tube + 1 blue tube
that is, the brightness of a pixel=600 (red) × 2 + 2400 (green) + 400 (blue)=3400mcd=3.4cd, brightness per square meter=brightness of 1 luminous pixel × Pixel density per square meter (number)=3.4cd × 1024 (number of pixels)=3482cd.
calculated by 20% light loss.
the actual luminous brightness should be 2785.28cd.

supplementary knowledge:
there are two methods to control LED brightness.
one is to change the current flowing through the LED.
generally, the continuous working current of LED is about 20mA, except that the red LED is saturated,The brightness of other LEDs is basically proportional to the current flowing; Another method is to use the visual inertia of human eyes, and use the pulse width modulation method to achieve gray control, that is to change the light pulse width (i.e. duty cycle) periodically, as long as the cycle of repeated lighting is short enough (i.e. the refresh frequency is high enough), The human eye can't feel the light-emitting pixels shaking.
because PWM is more suitable for digital control.
today, microcomputer is widely used to provide LED display content, Almost all LED displays use pulse width modulation to control the gray level.
the control system of LED mainly controls the gray level of each pixel on the scanning board.
the scanning board decomposes the brightness value of each line of pixels from the control box (i.e. pulse width modulation), and then turns on the signal of each line of LED in the form of pulse (light up to 1, light up to 1, light up to 1, light up to 1, light up to 1, light up to 1, light up to 1, light up to 1, light up to 1, light up to 1, In this way, less devices are used.
but the amount of serial transmission data is large, because in a repeated lighting cycle, each pixel needs 16 pulses at 16 gray levels and 256 pulses at 256 gray levels, Generally, the LED display can only achieve 16 levels of gray.
another method is that the serial transmission content of the scanning board is not the switch signal of each LED, but an 8-bit binary brightness value.
each LED has its own pulse width modulator to control the lighting time.
in this way.
in a repeated lighting cycle, each pixel only needs 4 pulses at 16 levels of gray, Only 8 pulses are needed in 256 gray levels, which greatly reduces the serial transmission frequency.
the results show that the proposed method is simple and effectiveThe 256 level gray level control can be easily realized by this method.
it is usually composed of the main control box, the scanning board and the display control device.
the main control box obtains the brightness data of a screen pixel from the display card of the computer.
each scanning board is responsible for controlling several rows (columns) on the LED display screen, At present, there are two ways of serial transmission of display control signal: one is
7 Common installation methods of LED display screen
(1) installation methods (display screen installation structure diagram)
a floor type
b inlaid type
c hanging type
d supporting type
e pillar type
F wall mounted type
the above are the seven most commonly used installation methods in display screen installation at present.
for indoor display screen, a, B, C and C are generally used (2) frame structure and exterior decoration
the design of frame structure is determined by the installation requirements of the display screen, the size of the display area and the color of the surrounding environment.
on the premise of ensuring sufficient installation strength, the design of the frame structure is determined by the installation requirements of the display screen, the size of the display area and the color of the surrounding environment, The installation weight of the display screen should be reduced as much as possible.

there are three methods for the outer frame of indoor display screen: black aluminum alloy, aluminum alloy wrapped with stainless steel (matte, stainless steel) The color of the black aluminum frame is close to the background color of the display screen.

} the aluminum alloy is wrapped with stainless steel frame.
the drawing stainless steel is used,It is beautiful and generous.

the color is Sony gray, which is easy to be received by the visual.
in addition, it is compact in overall structure.
there is no gap.
its disadvantage is that it has requirements on the area of the display screen.

for outdoor display screen, in order to ensure sufficient installation strength.
its outer frame is steel structure, The exterior decoration is usually selected according to the site conditions and the requirements of customers, and the outsourcing aluminum-plastic plate is usually used.
its advantages are as follows:
} aluminum-plastic plate has a variety of colors and varieties.
it can be purchased according to different requirements according to the screen size and customer requirements, asynchronous control or synchronous control can be adopted.

(a) asynchronous RS232 communication mode control (computer serial port) Description: asynchronous control is to receive and store the text edited by PC and graphics without gray scale (PC sends data to asynchronous control card through serial port), and then send data through asynchronous control card Step control card controls the display of the display screen.
after the screen is powered off, the contents to be displayed are stored in the memory of the control card. After the screen is powered on, the, The CPU on the asynchronous control card reads the contents from the memory of the card, and then controls the display of the LED display.

the advantage of asynchronous control is that it realizes the function of offline and storing information.
the PC only has the function of modifying the contents of the LED display,The display function is realized by asynchronous control, which has the advantage that a PC can control multiple displays, so it can realize the networking use of multiple screens.

the disadvantage of asynchronous control is that the asynchronous control card can not realize the function of playing animation.
the content stored in the control card is limited by the memory of the control card, and can only store dozens of content, In addition, the screen area controlled by asynchronous control card is limited Φ 5 --- within 7 square meters, Φ 3.75 --- controlled within 2.8 square meters, If it exceeds the control range, it can only be synchronized.
note: if the communication distance of a single display exceeds 100 meters or two or more displays are connected to the network, a converter (232 to 422 converter, 200 yuan) is needed.
(b) 256 level gray level synchronization control note: the synchronization control is to transmit the signal of PC display card to the LED display in real time.
the LED display and computer display are connected Synchronous display (WYSIWYG), synchronous control includes a DVI display card, a data acquisition and sending card, a data receiving card (Note: more than 512 points need to use two receiving cards)
advantages of synchronous control
it can realize the function of playing animation and image, and the gray level output can reach 256 levels (256 colors for monochrome screen, For dual color screen, it can display 256 red colors × Green 256=65536 colors) (DVI display card + 256 level gray control card, 1280 control points × 512 points, control range Φ 5 -- 9.76m long, 3.9m high, Φ 3.75-6.1 m long and 2.448 m high)
note: how to know the area of LED display within the controllable range
controllable length=number of control card points (long) × Point spacing
controllable width=number of control cards (width) × Point spacing
controllable range=controllable length × Controllable width, baidu Qilin electronics,Enter, log in, fill in the size, height and width of your LED electronic display screen, select the control card, click calculate, and the program will automatically calculate the actual size, material, price, unit price, and display price per sq
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