Led Lite Vision F.A.Q. | LED Display Screen Led Curtain for Indoor and Outdoor Advertising.

What is a LED?

LED is the acronym of Light Emitting Diode, it is a semiconductor that emits visible light when electricity passes through it. The emission of light is caused by electrons flowing between anode and cathode and the color of the visual emission (that can be Red, Green, Blue, Amber, White…) depending on the material used. Contrarily, to normal incandescent bulbs, the LED does not have a filament and this warranties a longer life and a much bigger reliability regarding traditional lamps.

What is a PIXEL?

By definition, the pixel is the “luminous dot” present on every LED solution, from a simple alphanumerical Single Line display to Full Color maxi-screens. This luminous dot can be formed by 1 or more LEDs depending on dimensions and features of the device. For example, on a small-size Single Line display, the pixel is formed by 1 single LED, while on a king-size model the pixel can be formed by 20 LEDs. In some products, the pixel can be composed by up to 36 LEDs.




What is a “dot pitch”?

The pitch of a LED display expresses, in millimeters, the distance between pixels. This measure is fundamental to determine the characteristics and performance of a LED display. To know a display’s pitch is very important since this measure marks the minimum viewing distance, the module’s definition and therefore the total LEDs density present on the display, which means the resolution. It is important to highlight that by reducing the pixel pitch, the LED density increases exponentially: for example, reducing the pitch by 50%, you can have 4 times the number of pixels on the same surface.

Pitch 20mm
Total pixels = 9

Pitch 10mm
Total pixels = 36

Pitch 15mm
Total pixels = 16

Which is the difference between SMD and PTH LEDs?

SMD is the acronym of Surface Mounting Device and it is the new frontier of the electronic technology: the revolution brought by the SMD technology into the sector is represented by the miniaturization of all the electronic components, including LEDs. The SMD components are mounted on the surface of the electronic board, without “passing through it” as any other electronic component utilizing the former technology (called PHT, acronym of “Plating Through Holes”). The SMD LED is also placed on the external part of the board without both filaments (anode and cathode) having to pass through it, as described on the image below (proportions are real): LEDs utilizing SMD technology are different from common PHT LEDs for another very important characteristic: thanks to the miniaturization it is possible, in fact, to place 3 LEDs of different colors within the same case (as in the picture on the top right), resulting in a three colors LED. The possibility to visualize three colors at the same time (Red, Green and Blue) on a single LED allow to create maxi-screens with a very reduced pitch (distance between pixels) and therefore to get a much higher quality image.

PHT technology LED

PHT technology vs. SMD technology

SMD technology LED

What is the RESOLUTION of a display?

The resolution is nothing else but the number of pixels present on each m2. The resolution is therefore opposite proportional to the pixel pitch: smaller is the distance between two pixels, higher is the resolution (because the surface of the screen will have a higher number of LEDs). For example a 20mm pitch screen has a resolution of 2304 pixels: this measure is obtained by dividing the total length of a single module (975 mm) by the pixel pitch (in this case 20mm) resulting in the number of pixels on a single line: 975:20 = 48 pixels. By multiplying the number of pixels present on a single line by the total number of lines, you get as a result the total number of pixels present on the screen’s surface, which is called resolution. In our example, 48 x 48= 2304 pixels in total. Given this formula, we find out that a 30mm pitch screen has a resolution of 1024 pixels per module, and a 10mm pitch one has a resolution of 9216 pixels per module. It is important to notice that reducing the pixel pitch by only a few millimeters, the LED number increase exponentially and therefore the resolution.

Module’s Resolution 3 x 3 = 9 pixels

Module’s Resolution 6 x 6 = 36 pixels

What is the DEFINITION of a display?

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 closely related to the LED pitch, or distance between pixels. To simplify and clarify the terminology, we can say that the RESOLUTION is referred to a single module, while the DEFINITION is referred to the entire display once all modules have been assembled.

Screen Definition 18 x 12 = 216 pixels

Screen Definition 9 x 6 = 54 pixels

What's the difference between screens with SAME DIMENSIONS but DIFFERENT DEFINITION?

The difference is the distance from which the display should be viewed to get an optimal image quality. The display with a higher definition (the smaller pitch and therefore a bigger number of LEDs per m2) has an image quality ideal for short viewing distance. The screen with a lower resolution (a bigger pitch and therefore a smaller number of LEDs per m2) has on the other hand a lower image quality, ideal for longer viewing distance. It is important to clarify that the screen’s definition is determined by the viewing distance: if a screen will be observed from 300 meters, it doesn’t need a high resolution since the human eye can not discriminate small details from long distances. On the other side, a screen that must be seen from 30 meters away needs a higher quantity of details (therefore a higher resolution) since from such a short distance the human eye is able to recognize even small details. To make a comparison, in the table below are represented two hypothetical screens of the same dimensions, but with different definition: the first (fig. 1) has a higher definition and is ideal for short viewing distances. The second one (fig. 2) on the other hand, has a lower definition and it is ideal for longer viewing distances. To better understand this concept, we recommend to look at the pictures from few centimeters and then from 3 meters away from the monitor.

Higher Definition – Ideal for Short Viewing Distance

Lower Definition – Ideal for Longer Viewing Distance

What are the MINIMUM and MAXIMUM distances for watching a LED screen?

The minimum and maximum viewing distances of a LED screen are measured depending on two fundamental characteristics on the display, the pitch and the surface: #1 – the minimum distance is calculated converting into meters the number of millimeters found at the pitch. For example, a display with a 10mm pitch will be seen from the minimum distance of 10 meters, a 20mm pitch display has a minimum viewing distance of 20 meters. #2 – the maximum distance instead depends on the display’s dimension and it can be calculated by multiplying x10 and converting into lineal meters the number of square meters on the display. For example a 4×3 meters (=12m2) display can be viewed from 120 meters distance. When talking about maximum distance, there are two concepts to clarify, “readability” and “visibility”: we understand as “readability” the distance within the images broadcasted on the screen are readable, thus clearly recognizable. “Visibility” identifies on the other hand the distance within the luminous display is able to attract the human eye’s attention, even if images are not perfectly identifiable. The “visibility “of a screen is usually the double of its “readability” (in our former example: readability 120 meters = visibility 240 meters). Regarding written texts, the readability depends on the fonts’ size. As a general rule we can affirm that every text centimeter can be read from about 5 meter distance. For example, a 10cm high text can be read from about 50 meters.

Is it possible to visualize a VIDEO on a LED display?

Of course it is. LED displays have their main application field in the “live” video visualization during concerts, sports events and TV shows (only later such an advanced technology entered the advertising field too). For the video broadcasting, it is important to keep in mind that, to obtain a satisfactory quality of the final images, it is necessary to utilize a display with a minimum resolution of 192 x 128 pixels. The LED display is after all a copy of a PC monitor and therefore it is able to visualize anything like visualized on the computer monitor (for example, it’s possible to see a PC’s desktop).

What are the COLOR LEVELS?

Color levels are the “palettes” that any color can have. In the LED visualization field are kept into consideration the color levels of the three primary colors: Red, Green and Blue. The total number of color levels on a display defines the number of palettes needed to pass from the lowest level (opaque) to the highest one (totally vivid).

9 color levels

90 color levels

What is the 16 BIT TECHNOLOGY?

Displays utilizing a 8 bit technology per color, that degrades the image during the video elaboration phase, are able to visualize 256 color levels for each one of the three primary colors. This means that 256 x 256 x 256 = 16,8 millions colors can be visualized in total. Led Lite Vision’s screens instead utilize a 16 bit technology per color that allows to elaborate videos without altering the quality in a perceptible way for the human eye. After this elaboration (called Gamma Correction) it is possible to visualize 65,000 color levels for each of the three primary colors. This means that it is possible to visualize 65,000 x 65,000 x 65,000 = 280,000 MILLION colors in total.

8 bit technology
256 color levels
16,8 million colors

What is the COLOR TEMPERATURE and why is it important?

As an international convention defined by the CIE (International Commission of Illumination) states, while evaluating the properties of any source of light, it is used a measure that takes into account their chromatic content. Such measure is called “color temperature” and it is expressed in Kelvin degrees (°K). Low levels of color temperature correspond to color tones closer to red, while high levels correspond to color tones closer to blue. In LED screen, it is fundamental to keep constant these values to visualize high quality images. Our company’s screens have an electronic system of colors’ equalization that deals with these parameters automatically, depending on the environmental lighting, in order to obtain always a constant color temperature during both day and night performances.

Why is the PURE WHITE created with THREE LEDs of different colors?

Because the human eye has 3 types of receptors for daily vision and each one of them correspond to a primary color. The rest of the colors are the result of the simultaneous stimulation of these three kinds of receptors, through a phenomenon called addition synthesis (which mixes the chromatic components captured by the eye). Each color is generated by the mix of the three primary colors, in different percentages. The color of reference, the pure white, is obtained by mixing the three primary colors in the right percentage (about 50% green, 30% red and 20% blue). Led Lite Vision technology allows, by varying the percentages of these values, to obtain 280 million colors. This huge chromatic palette guarantees a superior image quality and an unbeatable visualization capacity.

 

Chromaticity Diagram
CIE 1931

RGB visualization system
Red-Green-Blue

SMD TOP LED real picture

What is the VISIBILITY ANGLE?

The visibility angle of a screen is by convention the angle within which the brightness of a display is superior by 50% to the frontal luminosity. For example, a screen with 6000 NIT luminosity (NIT = candelas per m2) if seen by the front will have a visibility angle equal to the angle by which the brightness is reduced to 3000 NIT. This visibility angle can vary depending on the LED used and the display’s technical features.

What is the IP rate (acronym of INGRESS PROTECTION) and what does it measure?

This is the protection grade against humidity and dust and it’s identified as “IP” or “Ingress protection). The IP level is described by two figures. The first one is referred to the protection level against dust, the second one against water. The Ingress Protection level is an international standard utilized to measure the waterproof condition of any electronic product. Devices with a higher IP level keep the internal components safe and clean. Our company’s maxi screens guarantee a IP65 level, which means the highest reachable level in the LED visualization field. In the table below are summarized the different IP levels and their meaning.

 

IP levels table 

What is the VIRTUAL PIXEL TECHNOLOGY?

The Virtual Pixel is a technology of image management that allows to visualize pictures of a definition higher than the physical one, thanks to a technique called “pixel interpolation”. Led Lite Vision’s Virtual Pixel technology is able to control every LED individually: this unique and exclusive screen management allows overlying each pixel to the next one, creating a so-called “Virtual Pixel” that means a pixel that does not exist but it is perceptible by the human eye. As we said before, the screen’s definition is one of the features that define the images’ quality and beauty: higher is the resolution, higher is the picture’s quality. Our company’s screens with Virtual Pixel technology can visualize images with a definition four times higher than the physical definition of the display; and therefore, images are more detailed and real.

Physical Definition
Without Virtual Pixel Technology


Virtual Definition
With Virtual Pixel Technology


What is the REFRESH RATE and why is it important?

The refresh rate indicates the number of times that the image refreshes every second. For example, a PC monitor has a “refresh rate” of 72 Hertz (Hz) and therefore it refreshes all the pixels of the screen, from top to bottom, 72 times every second. The refresh rate is fundamental since it determines the image’s quality: if it is too low, the human eye can see a flicker that causes headache and damage to our eyes. To provide a comparison, most of the TV monitors have a refresh rate of 50Hz and only a few last generation televisions have a 100Hz refresh rate. Led Lite Vision’s screens have a 240Hz refresh rate, which is almost three times higher regarding the most advanced cathode tube technologies. This feature is another prove showing Led Lite Vision’ quality and the state-of-the-art technology, result of many years researching and testing in situ.

What is the CONTRAST LEVEL?

It’s the difference between the light emitted by the screen and the environmental light reflected by the display’s surface. Minor is the light reflected, higher is the contrast and therefore the cleanliness of images. To increase the contrast Led Lite Vision’s screens adopt some particular anti-reflex flyers that split the environmental light and reflect it in different directions, increasing the visibility of the screen even in direct Sun light exposition.

Do LEDs really have a lifespan of 100,000 hours (or 11 years)?

To guarantee a 100,000 hours lifetime, LED producers state clearly two fundamental conditions that must be respected, the internal temperature and the power intensity. These measures have different values depending on the LED type and the manufacturer, but to provide a limit of comparison we can say that: #1 – the LED internal temperature must be below 120 °C (measured in a 25°C environment) #2 – the power on which the LED works must be below 20mA. If both conditions are maintained, the LED producer guarantees that after 100,000 hours (about 11 years always turned on) the LED brightness will be reduced by 50% regarding the initial value. Keeping in mind the importance of these parameters, Led Lite Vision has invested in technological solutions able to manage these values correctly and automatically, and keep them constant during the whole device life. Led Lite Vision products are also able to verify them with a series of related devices and controls as: #1 a special forced ventilation electronic system electronically controlled, #2 a specific chip that manages every single LED and on which a certain power phase is defined, #3 a special heat dissipation system.

What is the MODULAR SYSTEM?

It is a system that allows to build big LED screens assembling several modules, depending on the customer’s specific needs. Led Lite Vision’s modules have different sizes, depending on the application and they are put together using an auto-centering system useful for keeping the perfect pixel alignment both horizontal and vertical which guarantees a perfect image visualization. Led Lite Vision’s modular system offers huge vantages: it allows an easy transportation and a simple mounting procedure (thanks to the individual module’s lightweight and reduced dimensions), it allows an easy maintenance, doesn’t put any limit in shape, size and resolution and moreover allows a future screen upgrade.

Base Module

975 x 975 x 125mm

Modular System

Where can I find some SPARE PARTS?

With each screen, Led Lite Vision provides a number of spare parts, free of charge, enough to cover any failure due to a normal use. Also, any reparation made within the warranty period will be totally free.

What are the differences between INDOOR and OUTDOOR screens?

From a general point of view the difference between indoor and outdoor screens are the following: #1 – lower resolution: as the outdoor displays are usually watched from longer distances, they do not need a very high resolution. The cost for a big screen is therefore compensated by the lower resolution needed to provide a good image quality. #2 – protection against weather (IP 65 protection grade) and cooling system: screens are treated with a particular “tropicalization” technique that guarantees an excellent resistance to water, salty air and corrosive intrusions typical of outdoor installations. Moreover a special forced-ventilation system guarantees that the temperature inside the screen remains constant and never passes the critical levels. #3 – against-sun and against-vandalism protection system: outdoor screens have a special protection system that has the double function of protecting the screens from the sun (increasing the contrast levels and obtaining a better image) and from vandalism acts. #4 – higher brightness: the outdoor use requires high brightness LED components in order to be visible from longer distances and most of all able to contrast the direct sunlight.

Can you visualize images on BOTH SIDES?

Not on a single screen. LED screens have a support called printed circuit or electronic card, and they are fixed on one single side. To see images on both sides it is necessary to have two screens, standing one against the other by the rear side.

What is the PORTABLE STRUCTURE of a LEDwall?

LED graphic displays are installed with different carrying structures depending on the application. They can be installed on:

 trucks
 on a building or structure’s wall
 on stands
 on wood
 on trusses
 hanging from a wire

Do you need permission from the local City Hall?

Yes. For installing a maxi LED screen it is necessary to ask for the local council’s permission where you are going to place the device. The entities taking charge of this are always local, and therefore it is impossible to define a general regulation, since laws vary according to each government.

How much does a LED consumes when ON?

A LED consumption depends on the manufacturer, on the diode’s color and the power passing through it. As a representative title we can say that a LED consumption is between 15 and 100 ma (milliamperes) and its power can vary from 0.1 to 1 Watt.

How Much does a LED screen cost ?

The final cost of an Led Lite Vision screen is influenced by two main factors:

The resolution (meaning the total number of LEDs present on each module)
The screen size (meaning the number of modules needed to build it)

Due to the great variability of both factors, depending on each customer’s requirements, it is impossible to determine in advance the cost of a screen.
Usually the bigger is the screen, the better: big size screens are built by a higher number of vertical and horizontal pixels. Higher is the number of pixels available, higher is the screen’s definition and therefore better is the image and video quality. And at the same time, of course, the larger the screen is, the higher the cost.