LED is a light-emitting diode. It has a semiconductor, which when crossed by a continuous voltage, emits light known as electroluminescence. Depending on the type of semiconductor used, we will obtain red, green or blue light.
LED plate or LED module is a circuit integrating LEDs and other electronic elements necessary for ignition and color control. The plates are usually encapsulated in plastic or metal masks to protect their parts and facilitate assembling of the units including the plates.
It is important to know that LED plates forming a led screen have to be of the same production series, because if to combine plates of different series in one screen, different chromatic shades will appear when the screen reproduces an image. For that reason, it is advisable to manufacture the entire LED screen at once, so that all LED panels are of the same production series.
It usually happens that companies with immediate stock availability combine LED plates of different series to produce a led screen, and that in certain combination of colors leads to appearance of areas with different chromatic nuances on the screen, creating a visual puzzle of colors and tones, damaging image quality in the way.
There are several types of LEDs varying in terms of components used for light emission, as well as in terms of luminosity, viewing angles, assembling type or type of soldering used to insert a LED into an electronic plate. In addition to the general types, there are some special lines, such as different vandal-proof LEDs, for example.
Two models are used in LED screens:
LED DIP (Dual in-line package): It is a highly resistant encapsulated LED emitting only one color. For that reason, they are used in LED panels forming RGB tricolor set (with this combination all colors are created). These LEDs are a good option for outdoor LED screens, as they resist environmental factors and have great luminosity.
SMD LED (Surface-Mounted Device): Each of these LEDs combines the three RGB colors. Thanks to this, small pixel pitches providing good viewing angles are achieved.
These LEDs are used for both outdoor and indoor led screens.
- Great environmental resistance
- High brightness levels
- Better color fidelity and definition than the conventional DIP led
- Unique encapsulation with 3 colors
- Better vision at close distances
- Unique encapsulation of the 3 colors
- Better image definition
- Same advantages as LED SMD
- Additional protection dome against impacts or extreme environments
Pixel (acronym for picture element, “image element”), is the smallest homogeneous color’s unit being a part of a digital image. Enlarging any image enough, you can see the pixels composing it.
Pixels are color dots. Digital images are formed by these dots. When it comes to LED screens, pixel is the smallest combination of the three main colors: red, green and blue (RGB).
Pixel pitch defines the distance measured in millimeters between centers of pixels of a LED screen. The bigger is pixel pitch, the longer is the distance. Pixel pitch also influences the viewing distance. In other words, the smaller is pixel pitch, the shorter is the distance from which the screen can be viewed.
We must remember that it is not always needed to choose the smallest pixel pitch, since there is a direct relation between led screen size and pixel pitch. Hence, choosing pixel pitch without taking into account size of a screen is an error. To choose the right pixel pitch for your screen it is important to get correct advices from several manufacturers or sellers of LED screens and compare them.
Viewing angles of a LED screen are measured horizontally and vertically. They indicate on what level images on a screen are visible if viewed from perpendicular to the screen surface prospective.
For example: if you take a look at 160/120 viewing angle measurements, the first number (160) represents horizontal viewing angle and indicates that image on the screen is visible if a viewer moves within 160 degrees horizontally (back and forth).
The second number (120 degrees) represents vertical viewing angle, and indicates that image on the screen is visible within 120 degrees vertically. This vertical angle is very important for the LED screens placed above the floor, regardless of whether they are placed on poles, monopoles, facades and are hanging well.
The viewing angles of a screen can condition the correct perception of the contents by the audience. Therefore, it is recommended that your screen has a horizontal viewing angle of between 120 and 160 and a vertical angle of between 120 and 160. DIP LEDs are those that have lower viewing angles for the design of their own manufacturing, this being his only weak point.
Contrast is illumination intensity difference in the range of white and black. Contrast is expressed as a XXX:1 ratio and shows the difference between the brightest white and the darkest black that can be seen on a screen.
Currently, for indoor LED screens have been designed LEDs with a commercial name Black LED, because their coating resin is black. In the way, contrast of an image is increased when we tend to black. However, contrast of an image is decreasing when we tend to white, so we keep a balance between the contrast levels.
Candela per square meter (cd/m²) is a unit for luminance due to International System of Units and it is used to measure the light emitted or reflected from a particular area. Lumen per square meter is one candela of light falling on 1 m2 surface emitted by a light source located at one meter from the surface.
This unit is used to specify brightness emitted by a LED screen at its maximum power and in white color (however, keep in mind that this unit is also known as nit).
For outdoor led screen, it is recommended to use luminosity over 5,000 nits or candelas y. For indoor led screen or shop windows, brightness between 1,500 and 3,000 nits is recommended.
Color temperature is measured in Kelvin degrees and represents the comparative relation of the ways in which a sheet of white paper would be observed under different types of light. For example, under a tungsten light (incandescent lamp) or under the light of a fluorescent tube (daylight).
Those of more than 5,000 K are considered to be cold colors, while the colors with 2,700-3,000 K temperatures are known as warm ones. Low quality LED displays have fixed color temperatures, since their electronic equipment do not allow regulate them. The most advanced LED screens have systems that allow regulate color temperatures within 3,000 K-6,500 K.
IP Index refers to the international standard IEC 60529 and is a way to classify different degrees of ingress protection of the containers protecting electronic pieces devices include.
Resistance indexes suitable for outdoor led screen are IP65 and IP54. On the other hand, IP67 indexes are not recommended for continuous use, as they require additional ventilation in hot environments.
Refresh rate or frequency is the number of times per second of an image being drawn on a screen. The image formed on monitors is a consequence of hundreds of continuous refreshments, imperceptible to the human eye.
Low refresh rate causes flicker on a screen impairing in the way viewing of images and videos. Therefore, it is always advisable to choose screens with a high refresh rate.
Maintenance access tells us where you can access the elements inside of a led screen.
Rear maintenance screens require a space behind screen to access their internal parts. Sometimes, these screens can incorporate doors that must be 100% practical to perform maintenance tasks. If you are installing a rear maintenance LED screen, be sure to leave a space for the door opening to provide access for personnel.
Front maintenance LED screens are designed to be installed on walls, etc., therefore their internal parts are to be accessed from the front. The front maintenance screens are slightly more expensive than those of rear maintenance type due to the mechanisms they integrate for a front access.
Both indoor and outdoor large format LED screens are composed of LED plates or panels. These LEDs have to be turned on and off thousands of times per second in order to reproduce images and videos. This complex task requires millions of pulses of digital information sent by the LED’s controllers to each other.
The controllers can be integrated internally in the screen itself or connected externally. Without these controllers the screen would be a simple three-color RGB bulb without the ability to display any content. Some manufacturers or suppliers include these kind of controllers at no additional cost, but others charge it additionally. In any case, it is a mandatory element to acquire so that the screen is functional.
It is a device combining several functions. On one hand, it is a LED driver with multiple video inputs (HDMI, DVI, VGA, SDI, RCA, S-Video …). All of them can be selected from an LCD menu or by pressing corresponding buttons. Additionally, next-generation climbers incorporate an image processor that automatically adapts video signals to native resolution of a LED screen. This means that there is no need to redesign or manually adapt resolution needed for reproduction.
This type of equipment is generally used to broadcast live content on a big LED screen (DTT, professional HD video cameras, 2K / 4K, satellite signals …).
We invite you to check other sections of our website, discovering how to install led signs and screens. Many customers will find buying them as more affordable solution than renting. Check it out!