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What should I know about the LED display operations?
Glossary
 
LED
Semiconductor – diode emitting light when electric current flows through it.
 
DIP
Dual In-line Package of LED, usually elliptical with two outputs. DIP LED contains a chip of one color (green, red or blue).
 
SMD 3in1 LED
Consists of three light-emitting chips - one per each color (red, green and blue). One SMD 3in1 LED makes one pixel of a screen. It is not possible to count virtual pixels for this equipment.
 
Pixel
Basic pixel consists of LEDs of basic colors - Red, Green, Blue. White color is made by composition of basic colors with the approximate ratio of R:3, G:6, B:1
 
Pixel pitch
Distance between geometric pixel centers, usually in mm. Pixel pitch is directly related to the minimum viewing distance. The smaller the pitch, the shorter the viewing distance at which we no longer see individual pixels.
 
Real pixel
Consists of a three or four LEDs of primary colors in the configuration 1R1G1B or 2R1G1B. Two red LEDs (R) have been previously used for two reasons. The first was performance of red LEDs, which was not sufficient for the required ratio of color components in white (R: 3, G: 6, B: 1), the second was voltage of the LED, which was roughly a half of the blue and green. A pair of red LEDs connected in series voltage reached a similar green and blue. This simplified the connection design. Today, the production of the red LEDs is facilitated by chips with different composition and so the voltage and brightness are suitable for use of a single LED.
 
All leading manufacturers of LED screens using high quality LEDs nowadays use pixel configuration 1R1G1B. SMD 3in1 also contain one chip of each color. Sometimes, especially for Chinese manufacturers or their distributors we find that the reason for using two red LEDs to prevent some kind of overloading and other nonsense. The reason is one and only one - the lowest price of the final product.
 
Virtual pixel
This technology is based on simple geometric principles supported by avanced technology. When LEDs are properly evenly spaced, it is possible to create another - virtual - pixel can be created between the two physical ones. With this technique the virtual resolution can be doubled.
 
 
What does a LED display consist of?
Cluster or LED module
Cluster or LED module  is basic building block of the LED module. It is a small waterproof module containing LEDs and control electronics made of durable plastic. The arrangement, where the control electronics is directly on a cluster is also called "intelligent cluster".
Module
Module or the often used term cabinet is the basic building block of an LED display. It is completely made ​​of aluminum. Basic resolution of  modules ranges from 64x64 to 192x192 pixels. Module dimensions are based on the pixel pitch. In addition to these basic sizes we are able to adjust their size in increments given by size of the cluster. Depending on the purpose of the LED screen, there are modules either for fixed installation, with wiring inside the module, or in the form for rent with external wiring and cage construction with quick-releases for fast assembly.
Supporting frame
Supporting frame is used for transferring static and dynamic powers to the place of installation. It could be a roof, facade, pillar etc.
Control PC and LEDbow software
Control PC with installed  control card is used to play streamed content, for previewing, and to send diagnostic data about the status of the LED display. The computer is connected with the screen in optical path, allowing connection even over long distances with great resistance against interference with radio communications. For shorter distance it is possible to use ordinary CAT 5 cable.  software allows for complete remote management of the control PC. You schedule an advertising campaign on your computer and you transfer and execute the campaign and the ad spots over the Internet. You can control multiple LED displays on your network at once.
 
 
 
What parameters of LEDs are important?
Is the brand of LED important?
Very much! Use of quality LEDs considerably affects lifetime and durability but also price of an LED display. Even though comparison of basic parameters of LEDs by various manufaturers might not necessarily yield substantial differences there are quite a few. The most important difference is speed of ageing of the LEDs ( Nejpodstatnějším rozdílem je rychlost stárnutí LED diod (loss of light intensity over time).
 
Often quoted 100 000 hours of lifespan of an LED display is really based on declared lifespan of the diodes. Usually it is claimed that with permanent current 20mA, 25°C temperature the brightness of an LED drops by 50%. It doesn't mean that after 100 000 hours the LED is dead. Nobody shows, though, what the drop in brightness is over time. Majority of customers assumes linear recession; however it is not true. Only manufacturers of hight quality LEDs (NICHIA, CREE) will reach more or less linear recession. Cheap chips and LEDs will have a high loss at the beginning, after couple of thousands of hours the brightness will dip even to 60%.
 
Another parameter is "reliability" of a chip. It mainly means the size of the chip, it's resistance against electrostatic penetration, the ability of the housing to dissipate heat, build of the housing, durability against UV, material used for the conductors (more expensive copper, cheaper steel) etc.
 
How can I determine manufacturer of LEDs on my display?
Type of used LEDs cannot be precisely verified. LEDs are not marked on the housing. The only reliable pointer is respectability of the manufacturer. The origin of LEDs can be proved only by purchase receipt but even then it is not certain that the LEDs on your screen are the ones from the receipt. In addition number of less trustworthy manufacturers claim the use of CREE LEDs but in reality these are LEDs manufactured by them only containing CREE chips.
 
 
 
What parameters of LED display should I been interested in
Minimal viewing distance
The shortest distance from which you can see an image continuously without distinct pixels. The smaller the pixel pitch, the shorter the minimum viewing distance. A simple guiding rule is that the physical pitch of pixels in millimeters corresponds to the minimum viewing distance in meters.
Maximum viewing distance
Has nothing to do with the pixel pitch. Only the physical size of LED display is crucial. In other words, LED display must be so large, that even the longest desired viewing distance will provide clearly visible display content..
Number of colors and color processing
Displayable colors are the key features of LED displays. The higher the number of colors you have, the more advanced technology must be used. This parameter is often intentionally falsified by less reputable manufacturers. Some manufacturers are deceiving you “just a little”, when their management system works in signal processing with 12 to 16 bits per color component (during gamma correction), but thanks to the LED display drivers can display only 8 or 10 bits. Less significant bits are just discarded and unused. Even then manufacturers say that the system has 16 bits per color component.
 
LED displays  not only process the full 16 bits color component, but also display. This requires a sophisticated and expensive technology, but the final image is incomparably better.
Refresh frequency
very important parameter of LED display is the number of frames displayed per second. Any value below 200Hz is basically useless. If the refresh rate is low, the image of the LED display flashes, can’t be photographed and when the camera is filming the screen, you can’t see same image on the record.
 
Many manufacturers change the refresh rate depending on the size of the LED display, so larger have a lower refresh rate. It has to do with constant speed of image data transport and that is dangerous practice. LED displays  have always fixed refresh rate 400Hz or 800Hz regardless of the size of the LED display.
 
We also use a number of mechanisms designed to improve the final image and increasing virtual refresh rate. LED displays  are perfectly readable by cameras and digital cameras with a very fast shutter.
Brightness
When using LED screens outdoors, the minimum brightness must be at least 5000cd/m2, indoors 1500cd/m2.
Viewing angles
They are the viewing angles from the perpendicular to surface of a LED screen at which decreases brightness LED screen to 50% against the value of brightness along the perpendicular (0° - directly to the screen). Angle value depends on the LEDs. Horizontal viewing angles using conventional LED diodes (DIP) are 120-140° and vertical viewing angles are 60-70°. The 3in1 SMD LED diodes have both viewing angles 120-160°.
 
 
 
How to choose the right LED display for my intention?
Important criteria
Selecting the appropriate type of LED displays is important moment for success of your project. If the LED display is disappointing for your clients, they will not pay. If you use unnecessarily expensive technologies (for example too high resolution) you will extend the period of return on your investment.
Based on placement:
indoor / outdoor
 
The difference between the two types is mainly in mechanical design and the amount of the achieved brightness. Outdoor LED displays have usually larger pixel pitch (10-30mm), indoor smaller (3-10mm). Outdoor LED displays must withstand all weather conditions, temperature changes and so on. The brightness of these LED displays must be high (min.5000cd/m2), so the image is visible even in direct sunlight..
 
Indoor LED displays does not resist such influences and may not serve brightness so high, usually 2000cd/m2. Beware of cases where choice between the use of indoor and outdoor LED screen is not so clear. For example: LED display located in the business center, but in the glass part of the building where the lighting conditions are the same as outside. Then the brightness of the indoor LED display would not be sufficient. Or the LED displays in multimedia dices on the ice rink. Brightness is sufficient here, but environmental conditions are rather as outside.
 
Low temperatures and especially high humidity, dangerous water condensation – comparable with rain or even worse. In this case, it is necessary to provide indoor LED display by cover, which should be at least IP43, if not outdoor IP65.
By viewing distance - choice of pixel pitch
Viewing distance of LED displays vary by location and use. We use several so-called pitch clusters. As long as the LED display is located in a distance of several tens of meters, there is no longer benefit of high density color points in order to compensate higher financial costs of the display. If you use the LED display that would artificially show the finest details, you will not be able to see them from long distance anyway.
 
 LED displays use pitch clusters from 8 mm to 30 mm. These distances represent the space between the colored dots. How much is a pixel pitch of LED display in mm, that many meters is optimal observation distance. For maximum viewing distance is crucial is the only real size of LED display. In other words, LED display must be so large, that even the longest desired viewing distance will provide clearly visible display content.
By location - service access
Different locations mean different options of service access. If the LED display is on the roof, rear service access is better.. If the LED display is on the wall, the better service access is from the front. Service access from the right side means fast service and lower cost of the supporting structure and the rental of equipment required to repair. Last but not least is the good look of installation of the LED display. Why having thin LED display, when you need at least another 700 mm space behind for service access? Then you are going to have clumsy box on the wall with a depth of 850 mm, when the screen is only 150 mm deep.
Fixed and rent installations
Depending on the use of LED displays there are modules for either fixed installation with wiring within modules, or in the form of rent with external cabling and cage structures for quick assembly.
Choosing a place for a LED display
Choosing a place for installation of LED display is one of the most important decisions and it will determine, how successful will your project be. In other words, a good place will sell anything, bad place will not save even the best LED display. In any case, the success of any media depends mainly on its content, the creativity and skills of the owner.
 
If you have a suitable place for a LED display, you will need rental contract and construction permission. The biggest obstacle is usually the opinion of the department of care of historical monuments and department of transport (police). We can arrange for you documents of a technical nature (statics, manufacturing documentation of supporting structures, etc.) or advise you how to get them. Finally you must have a suitable location for the control PC with an internet connection.
 
 
 
What should I know about the LED display operations?
LED display lifespan
Most manufacturers of LEDs provides a lifespan of 100,000 hours. After 100,000 hours at 20 mA continuous current and temperature 25° C decreases the brightness of the LEDs to 50%. However, such conditions almost never occur on the screen. Electric current is lower (mean value), but the temperature fluctuates. High temperatures can significantly shorten the life of LED chip. Such a long lifetime can be achieved only with high quality LEDs.
Power consumption
You should be given two data - max power (MAX) and operational power (AVG). To maximum power consumption must be dimensioned supply and its protection. It is the value given by sum of the maximum power consumption of installed power supplies. During operation, even with maximum possible brightness setting, max power will not be achieved. Operational consumption is between 25 and 35 percent of the maximum consumption.
Warranty period
LED displays  have full warranty for at least 36 months. The first three years you will not pay any service intervention or spare parts. Other manufacturers have often limited warranty, for example a replacement warranty of the defective parts with new ones (the warranty does not address who will disassemble the screen and install the new parts). Service support after the warranty period is very important too. Our company guarantees at least another 7 years of full service support, but usually this period is extended until the end of life of the device. We are real manufacturer and we do not have to rely on other suppliers.
 
 
 
 
How to choose the right LED display supplier
Supplier selection
We are ready whenever you need us.
 
LED display is not cheap and you are not taking it for a short time. It is a tool for the realization of your business plan and the choice of reliable supplier is very important. By purchasing LED display you are entering into a long relationship with your supplier.
High quality service
Many vendors claim that they are manufacturers, but they are not. Many of them sell LED
 displays as a supplement to another product range, some even claim that they never break down. The essential mistake in this case is usually lack of specialization, knowledge, long-term service and support. They are dependent on their suppliers, usually from China, over which they have no control. Repairs are performed only in exchange way and thus need expensive parts warehouse, which almost never exists.
 
The usual support from the Chinese supplier is two years in exchange for sending back defective parts or their employee assistance in the installation or repair. Sounds tempting, but only at the first glance. Sending parts takes long time, LEDs are not from the same production series, any bigger problem is almost unsolvable. You need to pay for the journey of the worker and ensure his visa. But you need your display to be repaired fast-NOW, because it earns you money
 
Some suppliers offer to calculate return on investment using profit calculators on their websites. The result is always perfect. Unfortunately it is not true. It does not reflect any specifics of the place and the price of advertising on the site. Always counts with 100% selling time and so on. It is very unreliable and misleading approach. t creates the impression that the display will pay for itself within a few months. That may be true, but only with your contributions, creativity and hard work.
 
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