LED Display FAQ

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LED Display FAQ


1. What is a LED and a Pixel?

LED is the acronym of Light Emitting Diode and it is a semiconductor that emits visible light when electricity passes through it. The emission of light depends on electrons flowing between anode and cathode and the color of the visual emission (that can be Red, Green, Blue, Amber, and White…) depends on the material utilized.

2. What is the Pitch and Resolution of the LED Display?

The pitch of a LED display defines the distance between the pixels, expressed in millimeters. This fundamental measure determines the characteristics and the performances of a LED maxi screen: the pitch indeed is a defining factor of a screen’s viewing distance.

3. What is the Definition and the 16 Bit Technology?

The “definition” is the number of vertical and horizontal pixels that are on the entire screen. For example, some standard definitions are 96×64 pixels (=low definition); 256×192 pixels (=medium definition): 640×480 pixels (=high definition). The definition is therefore related to the pixel pitch, the distance between the pixels.

4. What is the Virtual Pixel Technology and Contrast Level?

The Virtual Pixel is a technology of image management that allows visualizing pictures of a definition higher than the physical one, thanks to a technique called pixel interpolation? Virtual Pixel technology is able to control every single LED: this particular and exclusive screen management feature allows overlying every single pixel to the next one, creating a so-called Virtual pixel? (A pixel does not exist but is perceptible by the human eye).

5. What are the differences between Indoor and Outdoor Screens/Displays?

From a general point of view the difference between indoor and outdoor screens are the following: #1 – Resolution: as the outdoor screens are usually watched from greater distances, they do not need the highest resolution (from great distance the human eye do not discriminate small details anyways). The cost due to the big dimensions is therefore compensated by the lower resolution needed to provide a good image quality.

6. What is LED display, LED cabinet, LED module, LED module, LED pixels

The LED display is the final completed product for advertising or information showing, it was composed by a certain rows and lines of unit LED cabinet; the unit LED cabinet were composed by module certain quantity of LED modules, each LED module were composed by 16*16/16*8/8*8/4*4/1*1 LED pixels; each LED pixels were composed by 1R1G1B/ 2R1G1B/ 2R2G1B/ 2R1B/ 2R1G/ 2R/ 1R, etc.

7. What is virtual pixel, real pixel?

Real LED pixel is the physical LED pixel; virtual LED pixel is theoretically 4 times higher than real LED pixel. Actually, the real effect of the virtual pixel is not really 4 times better. It is only a much better, but not really can be 4 times better. When you LED display system is more than 640*480pixels, actually you don’t need to use virtual pixel if you plan to use the whole LED display for one advertising contents, but if you plan to divide a big LED screen into small sections for many advertising contents, the virtual pixel is still very necessary and useful for you to achieve much better effect.

8. What is dot correction, why it is better than the common control system?

Dot correction is a new technology and will be the direction of future LED display industry. The much more improved color consistence & high fresh frequency make it be the only solution for high level advertising need.

9. How to choose the rational product model of the LED display?

Corresponding with the LED display’s best viewing distance, size, application & installation, there will be many optional product models fit for each specific project. ROI & Budget is also very important factors.

10. What is best viewing distance, how to calculate the best viewing distance of the LED display?

Best viewing distance refers to the distance from the LED display, where the people can see a whole and clear picture of the image on the LED display.

There’s 2 ways to calculate the best viewing distance: one is by the pixel pitch, one is by the diagonal. There’s also the reason why there’s different viewing distance for same model LED display, also different viewing distance for same size LED display. .

11. Why there’s different viewing distance for same model of the LED display & different viewing distance for same size of the LED display.

There’s 2 ways to calculate the best viewing distance: one is by the pixel pitch, one is by the diagonal. There’s also the reason why there’s different viewing distance for same model LED display, also different viewing distance for same size LED display. .

12. What is RCG, What is CON?

RCG & CON is the 2 most important LED display screen system’s basic set up. For each LED display screen, it has only one RCG & CON file. If you lose it or break it, please contact with ERALED service dept for the file again.

13. What is flight case & wooden case? How to choose rational packing box?

Flight case has wheels and handles which is for the rental use LED display, to make the transportation be very convenient and protect the LED display better.

Wooden case is only for one time using transportation. After unpack, it cannot be used any longer. For the fixed installation LED panel system, wooden case packing is the only way and best way for packing since the low cost and same safety level for one time using.

If your LED display screen system is for the rental use, please choose the flight case packing for your LED display screen.

14. What’s the difference between synchronous control system? What is asynchronous control system?

Synchronous & asynchronous refers to the controlling PC working together with the LED display or not. Synchronous means when the LED display screen system is working, the controlling PC must open and cannot be closed. Asynchronous control system means when the LED display is working, the controlling PC can be closed and has not further relationship with the LED sign; the LED display can work independently after the basic set up and the program making.

15. How to choose the corresponding control system for your LED display.

Product model, controlling distance & application is the main factors. One more point is that the synchronous control system always has much better viewing effect and more powerful function.

16. What is simple cabinet, what is standard waterproof cabinet?

Simple cabinet has not backdoor, standard waterproof cabinet has backdoor, etc.

If you can make very good dustproof and waterproof system for your LED display, simple cabinet is also an optional solution when budget is limited

17. What is front maintenance, what is rear maintenance? How to choose the best servicing model for your LED display system

Front maintenance has two means to achieve: module front maintenance & cabinet front maintenance.

Rear maintenance has only one means: from the backdoor of the cabinet.

When the display is very small, cabinet front maintenance will be more convenient.

18. What is static display? What is scanning display? What’s the difference and which is better? How to choose the best scanning model for your LED panel?

Static and scanning display is the only 2 models currently. Static display used for P14-31.25mm, when pixel pitch is smaller than 14mm, the main working method is scanning.

19. What’s remote control & wireless control? How to choose the corresponding control model for your LED display system.(need to expand further in future, not enough: What’s the difference between remote control and wireless control.)

Remote control & wireless control is very necessary when the controlling HQ is far away from the LED display screen system.

Remote control & wireless control is by IP address and internet/intranet system to achieve.

20. What is selected LEDs, what is pure green & pure blue? Why the full color LED screen need selected LEDs & also pure green & pure blue LEDs?

For the common LED chip ,the wave length difference is very big and the brightness difference is very big too if not selected LEDs.

The selected LEDs means the LEDs is choose from a certain ratio of LEDs to choose the most constant LEDs.

Pure green & pure blue means the choose the green and blue LED chips strictly by the standard of main wavelength: G: 518-520, B: 466-468

Full color LED display need pure green & pure blue LED chip since if not it cannot achieve high gray grade and the image will be very poor.

21. What is the brightness control, how to achieve automatic brightness control?

Brightness control is needed since the environment brightness level is changing during the daytime. If you don’t adjust the brightness according to the environment, the LED display screen system will not have a perfect viewing effect.

There’s two ways to achieve the brightness control: manually changing & automatic changing. The automatic brightness changing can adjust the LED display screen system’s brightness perfectly according to the environment brightness level.

22. What is multi-function card?

Multi-function card can help the LED screen system achieve many functions, such as automatic False Alarms, fire &smoke alarms, brightness adjustment, etc.

23. What is sending card, receiving card & hub card of the LED display system:

Sending card, receiving card & hub card is the LED panel screen’s control system. Sending card is installed in the controlling PC, is the data sending equipment;Receiving card is installed in each cabinet, is the data receiving equipment; hub card is installed together with each receiving card, is the data distribution equipment.

All the above composed the main necessary parts of the control system

24. How to make a safe LED Display purchasing & money transferring? How to deal with cheaters and find out which supplier is fake?

There are many fake cheaters on the internet; we suggest you come to the factory directly for a visit before making the formal purchasing. Also you can find a local partner to complete the payment transferring. Also L/C is always safer than T/T. If possible, Using L/C payment terms will be safer.

25. What are the factors that effect screen size allowed by the user’s field?

(1) the connection of effective viewing distance and practical field size?

(2) pixel size and resolution

(3) area estimation based on cell

(4) screen mechanical installation and maintenance operation space

(5) infection of screen obliquity to distance

26. What are the displaying effects clients needed?

(1) characters displays: depends on its character size and resolution needs

(2) common video display: 320×240 dot matrix

(3) digital standard DVD display: 640×480 dot matrix

(4) full computer video 800×600 dot matrix

25. What’s the environmental brightness requirements to the LED display?

Common brightness requirements as below:

(1) indoor: >800CD/㎡

(2) semi-indoor: >2000CD/㎡

(3) outdoor (locate south ,face north) >4000CD/㎡

(4) outdoor (locate north ,face south) >8000CD/㎡

26. What are the brightness requirements of RGB in the white color configuration?

Red, Green, Blue contributes differently in white color quality, the root reason is due to human eyes’ retina feels different to light that has different wavelength. We got below proportions after mass experiments and inspections for your references:

Brightness proportion of simple RGB: 3:6:1

Brightness proportion of exact RGB: 3.0:5.9:1.1

27. Why high level full color display should use pure green tube?

In practical production of LED display, should choose tricolor that has high lighting efficiency and vivid pictures.

LED lamp, in order to make the area of color triangle as close as possible to color curve in tongue shape in chroma chart in order to meet abundant colors and emit enough brightness, the finial curve in tongue shape is 515nm wavelength light, so, high level LED panel choose pure green LED lamp whose wavelength close to 515nm. For example, to choose LED lamp which has wavelength 520nm, 525nm or 530nm.

28. How to calculate brightness of each lamp under the conditions of definite brightness and pixel density?

The calculating methods as below: ( for example: 2R,1G, 1B)

Red LED lamp brightness: brightness (CD)/M2÷dots/M2×0.3÷2

Green LED lamp brightness: brightness (CD)/M2÷dots/M2×0.6

Blue LED lamp brightness: brightness (CD)/M2÷dots/M2×0.1

For example: 2500dots/sqm, 2R1G1B, brightness requirement 5000 CD/M2, so:

Red LED lamp brightness: 5000÷2500×0.3÷2=0.3

Green LED lamp brightness: 5000÷2500×0.6÷2=1.2

Blue LED lamp brightness: 5000÷2500×0.1=0.2

Brightness per pixel: 0.3×2+1.2+0.2=2.0 CD

29. Why we choose DVI display connector standard?

(1) The DVI display connector meets the computer international standard

(2) no need to open cabinet, you can install easily

(3) high memory, display good quality dynamic pictures

(4) strong compatible ability of software and hardware

(5) support all operation system and application software, display neatly and conveniently

(6) volume-produce, low cost, convenient maintenance

30. Whether we can use a notebook to control the display or not, why?

Can’t. The display card of a notebook is inside, can’t realize connection with control system. Now, there is a type of notebook with DVI connector, it can realize notebook control.

31. What are the differences between using NICHIA tubes and Chinese tubes for full color LED display except prices?

(1) chips: NICHIA produces chips itself, Chinese tubes use USA or Taiwan chips usually.

(2) packaging: NICHIA does packaging itself, there is no manufacturer in China; there are more packaging factory for Chinese tubes.

(3) consistency: difference of chip wavelength is less in the same lot of NICHIA tubes, good consistency; worse consistency in Chinese tubes.

(4) life time: longer life time for NICHIA tubes, serious attenuation for Chinese tubes.

32. What are the differences between indoor module full color LED screen and SMD full color screen?

(1) lighting part: normally, the display module is olivine color for module full color screen, more expensive for pure green module; normally, use pure green chips for SMD full color screen.

(2) display effect : pixels in module full color screen looks wider, lower brightness, easy to cause mosaic phenomenon; better consistency and higher brightness for SMD full color screen.

(3) maintenance: not easy maintenance for module full color, higher cost of replacement of whole module; easy maintenance for SMD full color, cell lamp can be maintained and replaced.

33. Can SMD LED be used in outdoor screen? Why?

Can’t . Requirements for installation structure of outdoor screen is strict, SMD LED panel can not adapt to outdoor scurviness environment

High requirements for outdoor screen brightness, at present, SMD LED can’t reach the brightness requirements of outdoor screen

34. Why the lead time of outdoor screen is longer?

(1) materials purchase: the purchase term of LED lamps is longer, special imported chips, the lead time takes 4-6 weeks

(2) complicated producing technics : need PCB design, cover making, glue filling, white balance adjust, etc

(3) strict structure requirements: design for cabinet, need to consider windproof, rainproof, lightningproof , etc.

35.How to help client choose suitable display?

(1) the needs of displaying content

(2) visible distance,, visual angle confirm

(3) requirements of cabinet resolution

(4) requirements of installation environment

(5) cost control

36. What’s the normal length and width proportion of display?

Drawing screen: subject to displaying content

Video screen: normal 4:3 or approaching 4:3; perfect proportion 16:9

Controlled dots by a set of control system

Communication screen A card: single color, bicolor 1024×64

Communication screen B card:: single color: 896×512? bicolor: 896×256

DVI bicolor screen: 1280×768

DVI? full color screen: 1024×512

37. What factors should be taken into consideration of screen size design?

-There are three important factors in designing screen size:

(1) need of displaying content

(2) conditions of field and space

(3) unit template size (indoor display) or pixel size (outdoor LED display)

-Should increase drop press and startup facilities for 10KW aboved display

-Communication requirements: communication distance is defined by the length of communication line

-Install communication line should according to the length standard of used communication line suitable for the model of installed display.

The communication wires are not allowed to install in the same wire tube with the electronic wires.

-Installation requirements:

Make sure that the LED display be placed flat, don’t lean to the back.

-Hanging installation must use the adjustable pole for up and down.

-Have to fix the hooking lock for fare the LED screen drop off from the wall before install it onto the wall.

-Standing installation must have the position stable screw.

38. What are the index on the power consume and the requirements for the power supply OF THE LED screen?

The power consume of the LED screen have the Average power consume and the Maximum power consume. We also called the Average power consume as the Working power consume, it’s the factual power consume when it’s operating normally. The Maximum power consume is the power consume when it’s starting or full lighting and the other extreme situations. The Maximum power consume is the necessary factor to consider when using the AC electricity power supply, the depth of the wire and the switch, too. Generally, the Average power consume is one out of three of the Maximum power consume.

The LED display screen is the big size precision equipment. To operate in security and stability, the AV 220V power supply input port of the LED panel screen or the connected computers? Power supply input port need to connect with the ground.

Noted: computers? Power supply input port also must be connected with the body of the computer

39. What are the installation requirements of the LED display screen?

Power supply: the power supply connector must be match for the size of the LED display screen.

220V electricity power supply, live wire, neutral/null wire and the earth wire.

380V electricity power supply, three live wires, neutral/null wire and the earth wire.

The intercept area of the live wire is the same as the null.

The LED display screen above 0.1 million KW must have the lower-voltage equipment.

Communication requirements: the communication distance is decided by the length of the communication wire.

The communication wire must be installed under the length standard of the communication wire of the corresponding LED display screen.

40.What are the considering factors of the Outdoor LED display screen?

Main questions of outdoor display as below:

(1) display installed in the outdoor, solarization and drench, blow and dust, bad working environment, electrical equipment being wringing and damp will cause short circuit, even fire, cause conk out, even fire, result in loss.

(2) the display may be attacked by the strong electromagnetism made by the thunder and lighting.

(3) the big change of the environment temperatures. The Operating LED display will emit a lot of heating, if the environment temperature is too high, the molectron of the LED screen maybe operating un-normally to damage for its bad giving heating out, finally the LED display system will not operate normally as usual.

(4) the display has a wide range of angle, long viewing distance, big change of the environment light, especially the direct to the sunshine.

41. With these special requirements, the outdoor LED displays needed:

(1) The parts connecting the body of the LED display with the building must be waterproof and anti-leaking strictly as the display. The display must have the measurements for water giving out. Once leaked, it will be given out smoothly.

(2) The lightning rod should be installed on the LED display or the building. The body and the frame of the display must to keep connecting with the earth, the resistor of the earth wire should under 3 Q , so as to the heavy current from lightning can be discharged in time.

(3) Install the ventilator equipment to lower the temperature, keep the inner cabinet temperature in the range of -10 ~ 40 centigrade degree. The back top of the display must install the rolling electronic fans to give the heating out.

(4) Choose the industrial using IC with the working temperature range of -10 ~ 40 centigrade degree for fear the LED display can not start in the low temperature of the winter.

(5) To be seen from a long distance in the environment of high brightness, it must take use of the super-bright LED lamps.

(6) Choosing the new large angle LED lamps as medium; the LED panel will have a larger angle, vivid colors, consistent operation and a long life of more than 100 thousand hours. The medium has a popular package with the hat-edge and square shape in cylinder, sealed by Silicon glue, assembly without metal. Also the display has an unique exterior outface, solid and durable, has the characteristics of anti-dazzle, waterproof, impurity proof, protection from high temperature and short circuit.



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