Led displays explained

What is a LED Screen?
A LED screen is a video display which uses light-emitting diodes. An LED panel is a small
display, or a component of a larger display or screen. They are typically used outdoors in
store signs and billboards, and in recent years have also become commonly used in
destination signs on public transport vehicles. LED panels are sometimes used as form of
lighting, for the purpose of general illumination, task lighting, or even stage lighting rather
than display.
Types of LED Screens
There are two types of LED panels: conventional (using discrete LEDs) and surface-mounted
device (SMD) panels. Most outdoor screens and some indoor screens are built around
discrete LEDs, also known as individually mounted LEDs. A cluster of red, green, and blue
diodes is driven together to form a full-color pixel, usually square in shape. These pixels are
spaced evenly apart and are measured from center to center for absolute pixel resolution. The
largest LED display in the world is over 1,500 foot (457.2 m) long and is located in Las
Vegas, Nevada covering the Fremont Street Experience. The largest LED television in the
world, the Center Hung Video Display at Cowboys Stadium, is 160 by 72 feet (49 by 22 m),
11,520-square-foot (1,070 m2).
Most indoor screens on the market are built using SMD technology—a trend that is now
extending to the outdoor market. An SMD pixel consists of red, green, and blue diodes
mounted on a chipset, which is then mounted on the driver PC board. The individual diodes
are smaller than a pinhead and are set very close together. The difference is that the
maximum viewing distance is reduced by 25% from the discrete diode screen with the same
resolution.
Indoor use generally requires a screen that is based on SMD technology and has a minimum
brightness of 600 candelas per square meter (cd/m², sometimes informally called nits). This
will usually be more than sufficient for corporate and retail applications, but under high
ambient-brightness conditions, higher brightness may be required for visibility. Fashion and
auto shows are two examples of high-brightness stage lighting that may require higher LED
brightness. Conversely, when a screen may appear in a shot on a television studio set, the
requirement will often be for lower brightness levels with lower color temperatures (common
displays have a white point of 6500 to 9000 K, which is much bluer than the common
lighting on a television production set).
For outdoor use, at least 2,000 cd/m² is required for most situations, whereas higher-
brightness types of up to 5,000 cd/m² cope even better with direct sunlight on the screen.
(The brightness of LED panels can be reduced from the designed maximum, if required.)
Suitable locations for large display panels are identified by factors such as line of sight, local
authority planning requirements (if the installation is to become semi-permanent), vehicular
access (trucks carrying the screen, truck-mounted screens, or cranes), cable runs for power
and video (accounting for both distance and health and safety requirements), power,
suitability of the ground for the location of the screen (if there are no pipes, shallow drains,
caves, or tunnels that may not be able to support heavy loads), and overhead obstructions.

Decoding the LED Signal to LED
Screen. How does it work?
A jumbo TV that is 60 feet (20 meters) high has to do the same thing that a normal television
set does -- it has to take a video signal and convert it into points of light. If you have read
How Television Works, then you know how a television that uses a cathode ray tube (CRT)
does this.
Here is a quick summary of how a black-and-white TV works:
 The electron beam in a CRT paints across the screen one line at a time. As it moves
across the screen, the beam energizes small dots of phosphor, which then produce
light that we can see.
 The video signal tells the CRT beam what its intensity should be as it moves across
the screen. You can see in the following figure the way that the video signal carries
the intensity information.
 The initial five-microsecond pulse at zero volts (the horizontal retrace signal) tells the
electron beam that it is time to start a new line. The beam starts painting on the left
side of the screen, and zips across the screen in 42 microseconds. The varying voltage
following the horizontal retrace signal adjusts the electron beam to be bright or dark
as it shoots across.
 The electron beam paints lines down the face of the CRT, and then receives a vertical
retrace signal telling it to start again at the upper right-hand corner.
A color screen does the same thing, but uses 3 separate electron beams and 3 dots of
phosphor (red, green and blue) for each pixel on the screen. A separate color signal indicates
the color of each pixel as the electron beam moves across the display. As the electron beam
paints across the screen, it is hitting the phosphor on the screen with electrons. The electrons
in the electron beam excite a small dot of phosphor and the screen lights up. By rapidly
painting 480 lines on the screen at a rate of 30 frames per second, the TV screen allows the
eye to integrate everything into a smooth moving image.
CRT technology works great indoors, but as soon as you put a CRT-based TV set outside in
bright sunlight, you cannot see the display anymore. The phosphor on the CRT simply is not
bright enough to compete with sunlight. Also, CRT displays are limited to about a 36-inch
screen. You need a different technology to create a large, outdoor screen that is bright enough
to compete with sunlight. LEDs may be little, but new high-brightness models are producing
a considerable amount of light.
First used as status and indicator lamps, and more recently in under-shelf illumination, accent
lighting, and directional marking applications, high-brightness LEDs have emerged within
the last six years. But only recently have they been seriously looked upon as a feasible option
in general purpose lighting applications. Before you recommend or install this type of
lighting system, you should understand the basic technology upon which these devices are
based.
Light-emitting diodes (LEDs) are solid-state devices that convert electric energy directly into
light of a single color. Because they employ “cold” light generation technology, in which

most of the energy is delivered in the visible spectrum, LEDs don't waste energy in the form
of non-light producing heat. In comparison, most of the energy in an incandescent lamp is in
the infrared (or non-visible) portion of the spectrum. As a result, both fluorescent and HID
lamps produce a great deal of heat. In addition to producing cold light, LEDs:
 Can be powered from a portable battery pack or even a solar array.
 Can be integrated into a control system.
 Are small in size and resistant to vibration and shock.
 Have a very fast “on-time” (60 nsec vs 10 msec for an incandescent lamp).
 Have good color resolution and present low, or no, shock hazard.
The centerpiece of a typical LED is a diode that is chip-mounted in a reflector cup and held in
place by a mild steel lead frame connected to a pair of electrical wires. The entire
arrangement is then encapsulated in epoxy. The diode chip is generally about 0.25 mm
square. When current flows across the junction of two different materials, light is produced
from within the solid crystal chip. The shape, or width, of the emitted light beam is
determined by a variety of factors: the shape of the reflector cup, the size of the LED chip,
the shape of the epoxy lens and the distance between the LED chip and the epoxy lens. The
composition of the materials determines the wavelength and color of light. In addition to
visible wavelengths, LEDs are also available in infrared wavelengths, from 830 nm to 940
nm.
The definition of “life” varies from industry to industry. The useful life for a semiconductor
is defined as the calculated time for the light level to decline to 50% of its original value. For
the lighting industry, the average life of a particular lamp type is the point where 50% of the
lamps in a representative group have burned out. The life of an LED depends on its
packaging configuration, drive current, and operating environment. A high ambient
temperature greatly shortens an LED's life.
Additionally, LEDs now cover the entire light spectrum, including red, orange, yellow, green,
blue, and white. Although colored light is useful for more creative installations, white light
remains the holy grail of LED technology. Until a true white is possible, researchers have
developed three ways to deliver it:
 Blend the beams. This technique involves mixing the light from multiple single-color
devices. (Typically red, blue, and green.) Adjusting the beams' relative intensity
yields the desired color.
 Provide a phosphor coating. When energized photons from a blue LED strike a
phosphor coating, it will emit light as a mixture of wavelengths to produce a white
color.
 Create a light sandwich. Blue light from one LED device elicits orange light from an
adjacent layer of a different material. The complementary colors mix to produce
white. Of the three methods, the phosphor approach appears to be the most promising
technology.
Another shortcoming of early LED designs was light output, so researchers have been
working on several methods for increasing lumens per watt. A new “doping” technique
increases light output several times over compared to earlier generations of LEDs. Other
methods under development include:

 Producing larger semiconductors.
 Passing larger currents with better heat extraction.
 Designing a different shape for the device.
 Improving light conversion efficiency.
 Packaging several LEDs within a single epoxy dome.
One family of LEDs may already be closer to improved light output. Devices with enlarged
chips produce more light while maintaining proper heat and current management. These
advances allow the units to generate 10 times to 20 times more light than standard indicator
lights, making them a practical illumination source for lighting fixtures.
Before LEDs can enter the general illumination market, designers and advocates of the
technology must overcome several problems, including the usual obstacles to mainstream
market adoption: Industry-accepted standards must be developed and costs must be reduced.
But more specific issues remain. Things like lumen-per-watt efficacy and color consistency
must be improved, and reliability and lumen maintenance should be addressed. Nevertheless,
LEDs are well on their way to becoming a viable lighting alternative.
There are two big differences between a jumbo TV screen that you see at a stadium and the
TV in your home:
 Obviously, it is gigantic compared to your TV. It might be 60 feet (20 meters) high
instead of 18 inches (0.5 meters) high.
 It is incredibly bright so that people can see it in sunlight.
To accomplish these feats, almost all large-screen outdoor displays use light emitting diodes
(LEDs) to create the image. LEDs are, essentially, little colored light bulbs. Modern LEDs
are small, extremely bright and use relatively little power for the light that they produce.
Other places you now see LEDs used outdoors are on traffic lights and automobile brake
lights.
On a color CRT television set, all of the colors are produced using red, green and blue
phosphor dots for each pixel on the screen:
In a jumbo TV, red, green and blue LEDs are used instead of phosphor. A "pixel" on a jumbo
TV is a small module that can have as few as three or four LEDs in it (one red, one green and
one blue). In the biggest jumbo TVs, each pixel module could have dozens of LEDs. Pixel
modules typically range from 4 mm to 4 cm (about 0.2 to 1.5 inches) in size.
To build a jumbo TV, you take thousands of these LED modules and arrange them in a
rectangular grid. For example, the grid might contain 640 by 480 LED modules, or 307,200
modules. The size of the ultimate screen depends on the size of the LED modules:

Full Color Integrated 3in1 SMD LED
Screens
The full color integrated 3in1 SMD LED screens by Vegas LED Screens is a revolutionary
development in the LED industry. It features higher definition and a super wide viewing
angle in comparison to the ordinary led screens. Each panel is made by custom quantities of
modules with an 8x8 or 4x4 configurations. Every 3-in-1 pixel in a reflect cavity is comprised
by three LED chips: Red, Green, and Blue.
A dot matrix LED screen is a LED display device used to display information on machines,
clocks, railway departure indicators and many and other devices requiring a simple display
device of limited resolution. The display consists of a matrix of lights or mechanical
indicators arranged in a rectangular configuration (other shapes are also possible, although
not common) such that by switching on or off selected lights, text or graphics can be
displayed.
A dot matrix controller converts instructions from a processor into signals which turns on or
off lights in the matrix so that the required display is produced.
Usual Resolutions for Dot Matrix LED Screens
Common sizes of dot matrix displays:
 128×16 (Two lined)
 128×32 (Four lined)
 192×64 (Eight lined)
Usual Character Resolutions for Dot Matrix LED Screens
 A common size for a character is 5×7 pixels, either separated with blank lines with no
dots (in most text-only displays), or with lines of blank pixels (making the real size
6x8). This is seen on most graphic calculators, such as CASIO calculators or TI-82
and superior.
 A smaller size is 3×5 (or 4x6 when separated with blank pixels). This is seen on the
TI-80 calculator as a "pure", fixed-size 3×5 font, or on most 7×5 calculators as a
proportional (1×5 to 5×5) font. The disadvantage of the 7×5 matrix and smaller is that
lower case characters with descenders are not practical. A matrix of 11×9 is often
used to give far superior resolution.
 Dot matrix displays of sufficient resolution can be programmed to emulate the
customary seven-segment numeral patterns.

Difference Between Real and Virtual
Pixels LED Screens
What is the difference between real pixel LED screens and
virtual pixel LED screens?
With the virtual pixel technology, the LED display will appear a more clear vision.
Theoretically the resolution will be 4 times of a real pixel technology LED display.The
difference of a real a virtual pixel LED screen of LED display can be seen in the next
pictures.
Virtual Pixel LED Screen Real Pixel LED Screen
How do virtual LED screens work?
Below you can clearly see how the virtual pixels are made, we surely recommend you a
virtual display, even so our new technology of Dot Matrix it’s still better than virtual pixels,
because the three colors RGB are in the same dot or pixel, just like the SMD technology and
also the Dot Matrix have a horizontal viewing angle of over 160 degrees. The virtual pixel
LED screens have a horizontal viewing angle of upto 130 degrees.

Do I need a wide LED screen to play
16:9 movies?
Playing Videos on LED Screens
To play videos on a LED screen a video file will be loaded into the LED screen software if
the format is in AVI or MPEG. Another option is that the video(s) or publicity spot(s) is
placed on a DVD and can be loaded with the LED screen software directly from the DVD.
But the question will be: "In what aspect ratio I have to produce my video?". The answer is
very simple and will be explained in this article!
Wide Screen and Letterbox Mode for LED Screens
A DVD-player or blu-ray can be connected to any LED screen, but with a Widescreen LED
screen you will get the most viewing enjoyment. DVD-Video supports multiple aspect ratios.
Video stored on a DVD in 16:9 format is horizontally squeezed to a 4:3 (standard TV) ratio.
On Wide-screen LED screens, the squeezed image is enlarged by the LED screen to an aspect
ratio of 16:9.
DVD video players and video files output widescreen video
on LED screens in three different ways
1. Letterbox (for 4:3 LED screens)
2. Pan & scan (for 4:3 screens)
3. Anamorphic or unchanged (for wide LED screens)
In widescreen or letterbox mode, if a movie is wider than 16:9 (and most are), additional thin
black bars will be added to the top and bottom at production time or the sides will be
cropped. Video stored in 4:3 format is not changed by the player. It will appear normally on a
4:3 screen. Widescreen systems will either stretch it horizontally or add black bars to the
sides.
Advanced Live Video Processor for LED Screens
With our advanced live video processor, the image can be adjusted horizontally and vertically
to make the image or video fit the screen. Another option is to produce the video in the right
aspect ration of the screen, due to the fact that some screens do have odd sizes which makes
the aspect ratio wider or longer.
Conclusion Aspect Ratio LED Screens
It is not necesary to have a wide screen LED screen to play different kind of movies, video
clips and pictures and animations. A LED screen can play any kind of aspect ratio, although it
might be possible that the image will be cropped leaving a black line at the top, bottom, left
or right of the image. But with the advanced live video processor it can be eliminated

although the image will deform a bit depending on the aspect ratio.
Prices LED Screens, LED Displays
and Electronic Billboards
How much does a LED screen or LED display cost?
The price or cost of a LED screen, LED display or electronic billboard depends on two
variables. Those two variables are the total size of the LED screen, and the total resolution
of the LED screen.
1. The total size of the LED screen: The bigger or larger the LED screen the higher
the cost. The prices are based on USD/sqm, which means that if the total size is
24sqm, the price will be 24 multiplied by the cost per sqm.
2. The total resolution of the screen: The more pixels, or the more number of LED´s,
the screen has the higher the cost will be. For example if a screen is 12sqm and has
49,000 pixels, it will be cheaper if the LED screen is 12sqm with 120,000 pixels.
This is because more LED lamps will be placed onto the screen which is a higher
cost. But on the other hand the more LED´s the screen has, the higher the detail will
be of the videos and images that the LED screen will be publishing.
Why LED screens have different costs and prices?
Everything depends on the customers´ needs. Some customers want the public to see their
LED screen from a distance of 10 meters and further, and others from 20 meters and further.
The more resolution/sqm a screen has the closer will be the viewing distance without loosing
detail looking at the screen from closeby. For that we always need the client to answer us
several questions to determine the right LED screen size and resolution and come with the
right proposal. Nothing is predetermined, but based on the needs of the client.
If you want to know what are our prices per square meter please let us know and give us a
call, or contact us by writing an email or online chat. We can send you our prices and you
can figure out what will be the right size and right resolution for your LED screen that fits
your budget.
LED Screens and Refresh Rate
What is the refresh rate for LED screens?
The refresh rate of a LED screen is the number of times in a second that the LED screen
hardware draws the data. This is distinct from the measure of frame rate in that the refresh
rate for LED screens includes the repeated drawing of identical frames, while frame rate
measures how often a video source can feed an entire frame of new data to a display.
For example, most movie projectors advance from one frame to the next one 24 times each

second. But each frame is illuminated two or three times before the next frame is projected
using a shutter in front of its lamp. As a result, the movie projector runs at 24 frames per
second, but has a 48 or 72 Hz refresh rate.
Increase refresh rate for decreasing LED screen flickering
On LED screens, increasing the refresh rate decreases flickering, thereby reducing eye strain.
However, if a refresh rate is specified that is beyond what is recommended for the LED
screen, damage to the display can occur.
Normally our LED screens of Vegas LED Screens have a refresh rate of over 300Hz, which
is more than 5 times the refresh rate of a normal cathode television which is 50Hz (PAL and
SECAM) or 60Hz (NTSC). For football stadiums (stadium LED screens and perimeter LED
screens) our LED screens can reach a refresh rate of over 800Hz, which means that they
won´t show any flickering when recorded with a video camera and broadcasted live on
television.
Life Time of our
LED Screens
What is the life time for our LED screens?
The life time for our LED screens is over 100,000 hours, but it depends how the client is
taking care of his LED screen and how it is used. When a LED Screens´ life time will get to
100,000 hours, it means that the brightness of the LED´s of the LED screen is about 50% of
it´s original brightness, depending on several factors that will enlarge a LED screen´s life
time or reach 100,000 hours.
The most important factors are, which are:
 LED Screen Maintenance
 LED Screen Temperature
 LED Screen Power Protection
 LED Chip Packaging
LED Screen Maintenance
Maintenance is a very important factor, dusty environments require more often maintenance
to the LED screen than clean environments. The soldering of the LED chips can dry out and
break which require changing often pieces like LED modules and receiving cards.
LED Screen Temperature
The temperature of the LED screen is very important to keep it cool. In hot environments it is
wise to install a cooling system inside the LED screen to avoid overheating.

LED Screen Power Protection
Electrical peaks can put more force on the electrical components which will decrease life
time. It is wise to install a protection that can control the peaks.
LED Chip Packaging
The LED chip packaging material is also a very important variable that will determine the
lifetime of a LED screen. For example iron has less life than cuprum LED packages. Besides
iron is more corrosive than cuprum.
Vegas LED Screens Quality
Explanation and Comparison
Vegas LED Screens Quality Explanation and Comparison
Below you can find the comparison of the main components we use for our LED screens
compared to other LED screen companies and factories. There are many ways to lower the
cost using cheaper materials like LED lamps with iron leg or low quality power supplies.
 We are usinghighqualitymaterials&partsto ensure the reliabilityof ourLED Screensfrom
the verybeginning;
 Full automaticproductionlineswithourstate-of-the artmanufacturingfacilities;
 Rigorousqualitycontrol fromthe raw materials& partsinspectiontofinal inspectionwith
advancedtestingequipment;
 Our expertiseandknow-howonLED displays;
 Experience gainedfrommanyinstalledsystemsworldwide.
Item Components Vegas LED Screens' Choice Other Factory's Choice
LED Lamp
LightningChip
1. LED manufacturerand
packagerby Nichia
2. LED manufacturerand
packagerby Cree
3. Top grade Silanwithbigger
chips
(highbrightnessandless
powerconsumption)
Fake lampsor
unprofessional
encapsulation
Lamp Leg Onlyuse Name brand Copperlegs
Use copperlegsor ironlegs
withunknownbrands

Encapsulation
Glue
Onlyuse Name brandfrom Taiwan DomesticBrand
Lamp
Board &
Driving
Board
PCB Board Name brand;Grade A material
Domesticbrand,normal
Grade B material
Connector Copperplatedwithgold Copperplatedwithnickel
DrivingIC Original TaiwanMacro Block Domesticunknownbrand
Resistance Tolerance ± 1% Tolerance ± 5%
Capacitance
Hightemperature resistance,upto
150 degree Celsius
Not-high-temperature-
resistance,only 90degree
Celsius
FasteningScrew Stainlesssteel withplating Iron withplating
Anti-Water
Glue
Name Brand DomesticBrand
Louver
Louver
1. PC + fiberglass(good
weatherproofed)- regular
screen
2. Softsiliconrubber- for
perimeterLEDscreen -
Grade A material
1. ABS or recycle PC
2. Grade B material
Anti-water
plasticglue
Low-temperatureresistance silicon Normal Silicon
Cabinet &
Assemble
Components
Cabinet
material:highqualitycoldrolled
steel (1.5mmstandard)
or Aluminum metal sheet5052
(2.0mm standard)
ThinnerMaterial
Rust Proof Electrostaticspraying StovingVarnish
Wires& Cables
Certifiedproduct;
Real coppercore withstandard
diameter
Non-certificatesand
standardcore and core
diameter
CoolingFan Name brandand certifiedproducts Non-certificates

Screw& Fixed
Pole
Stainlesssteel
Iron withZinc/ nickel
plating
Power Supply PowerSupply
Brand Names:
1. TDK - Lamda (Japanese
Brand)
2. Meanwell
Meanwell orotherbrands
like mingwell
Facts about Parts used for building LED Screens
Below you can find some very important facts about parts that are used for to build LED
screens for to improve lifetime and picture quality.
Name Brand:Meanwell orTDK-Lamda powersupplies
We are using name brand power supply for all our LED screen projects. Meanwell and TDK
- Lamda power supplies for LED screens are lightweight high-efficient power supplies
switched by high-speed semi conductors.
ExtraprotectionforLED Screensfromlouver
The louver itself will protect the LED screen from direct exposure of sunshine; our louver is
made of fiber-glass reinforced PC (except the sports stadium screens), which is strong in both
compressive loading and sensible strength by combining the two materials PC plastics and
glass fiber. It has much better performance against high temperature, erosion and UV
radiation, in comparison to ABS.
For sports stadium LED displays, we are using louver made of soft silicon rubber, which are
both protection for players from getting hurt if pumping on LED displays, and seemly protect
LED displays itself from being damaging if a ball hits the LED displays at high speed.
LED lamp BrandsforLED Screens
We purchase Cree LED lamps and Nichia LED lamps encapsulated by their own factory; for
Silan lamp, we also use a professional packager. Also our output of LED displays could be
very high per month, this means we have quite large purchasing volume of LED lamps at one
time, which could ensure our good bin selection of LED lamp i.e. large volume LED lamp
under the same lot and grade. Hence it could ensure the consistence of a single LED display
(even in large size like hundreds sqm) using the same lot and grade lamp. This is one of key
factors on the consistence of LED display.
What do the IP protection grades
for LED screens mean?

LED screens must be able to work 24 hours a day and 7 days a week and withstand extremely
stormy or sandy storm weather. For manufacturers it is required that the LED screens meet
the criterion for outdoor LED screens IP65, and for indoor LED screens IP20. So what do
these criterion mean? And what does IP65 and IP20 stand for?
The IP code (or International Protection Rating, sometimes also
interpreted as Ingress Protection Rating) consists of the letters IP
followed by two digits and an optional letter.
As defined in international standard IEC 60529, it classifies the
degrees of protection provided against the intrusion of solid objects
(including body parts like hands and fingers), dust, accidental contact, and water in electrical
enclosures of the LED display screens. The standard aims to provide users more detailed
information than vague marketing terms such as waterproof.
International Protection Rating Of Vegas LED Screens for
Outdoor LED Display
It's the technical introduction by reading which you will command all the conception in
details. But here as a company dedicated in LED display screens, we'd like to be short to
avoid any unnecessary mistake.
Front OutdoorLED Screens:IP67
The first digit indicates the protection against dust. And "6" means Dust Tight, which means
no ingress of dust and complete protection against contact. The second digit indicates the
protection against liquids. And "7" means ingress of water in harmful quantity shall not be
possible when the enclosure is immersed in water under defined conditions of pressure and
time (up to 1 m of submersion).
BackOutdoorLED Screens:IP55
The 2 digits indicate the same parameter with above. But the letters are different. And the
first "5" means Dust Protected: Ingress of dust is not entirely prevented, but it must not enter
in sufficient quantity to interfere with the satisfactory operation of the equipment; complete
protection against contact. The second "5" means: Water projected by a nozzle against
enclosure from any direction shall have no harmful effects.
According to the "The General Criterion For LED Displays": Indoor LED displays should be
IP20+, Outdoor LED displays should be IP33+ So with IP67 for the front side, and IP55 for
the rear side, we ensure the led display working well in all the outdoor environment and
weather conditions.
Clarify On the IP65 LED Screens
Sometimes clients are misled by non-professional suppliers who aim only selling out the led
screens. As the reliable partner, we think it's necessary to make clear each confusing point,
and be honest with true result. For the front side, it's no difficult to reach "IP65". But for the

rear side, as long as there's air inlet and outlet, the protection against dust can't reach "6" -
totally prevent the dust. In another words, as long as the heat dissipation design based on
fans, the air inlet and outlet is necessary. As a result, the ingress protection can't reach "6".
Vegas LED Screens LED Display Test Method of "IP_5"
1. The inside diameterof waterjet:6.3mm
2. Distance betweenthe displayandwaterjet:2.5-3m
3. Flowvelocity:12.5L/min±5%
4. TestTime:3 min/m2
5. TestCondition:Everyfeasible anglejetontothe testsample cabinets.
Relationship between pixel pitch
distance and viewing distance
According to the working environment, LED displays can be divided into indoor led screens,
outdoor led screens and semi-outdoor led screens. There are some data in theory which can
reflect the relationship between the pixel pitch and the best viewing distance.
The relationship between pixel pitch distance and the best viewing distance
Pixel Pitch P5 P6 P7.62 P8 P10 P12 P16 P20 P25
Viewing Distance (m) 11 14 17 18 23.5 28.2 35.5 46.99 56.4
Viewing Distance (ft) 36 46 56 59 77 92.5 116.5 154.16 185
In the actual application, because of the limitation of led display installation environment and
identify ability, led display’s smallest viewing distance is mean the shortest distance that can
identify the text and picture showing. The shortest viewing distance and led specification are
on below:
The smallest viewing distance and led display specification
Viewing Distance
(m)
3 ~ 5 5 ~ 8 8 ~ 10
10 ~
12
12 ~
16
16 ~
20
20 ~
25
> 25
Viewing Distance (ft)
10 ~
16
16 ~
26
26 ~
33
33 ~
39
39 ~
52
39 ~
66
66 ~
82
> 82
Pixel Pitch
P3
P4
P4.75
P4.75
P5
P6
P7.62
P7.62
P8
P10
P10
P12
P12
P14
P16
P16
P20
P20
P25
P25
P31.25
The Effective Control Distance Of
LED Displays and LED Screens
In this article, we will explain the effective control distance of full color LED displays and
LED screens signals transferred with a normal network cable. Generally, the signal cable of a

LED display is RJ45 which is a standard network cable. The control distance can reach up to
100m, which is enough for most clients needS. A LED screen will be installed with a
structure, the function of which is not only to back up the LED display and decoration, but
also, there will be a small control room inside the LED screen structure or nearby the LED
screen structure where a PC will be placed to control the LED screen.
Economic LED Screen Controlling
The most economic way for controlling a LED screen is using the basic RJ45 signal cable.
But for some special clients, they will not place the control PC nearby the LED display,
because it's not convenient for them to edit and program the content nearby the LED display.
Those clients will request for a longer control distance. In this condition, a fibre-optic
solution will be chosen. And in this way, the control distance from the LED screen to control
room where the controlling computer is placed can reach up to 10Km, or even more. This
will bring a relative high cost which won't make it an economic solution.
Usually for LED screens and LED displays that will be controlled over a long distance, an
internet connection can be choosen too. This only applies if an internet connection is
available for both locations to control the LED display and to control the PC. We recomment
to control the LED screen remotely by the internet of course.
LED Displays Controlling Remotely
For most application, the signal from the controlling PC to the LED display screen is
transferred via a RJ45 cable. The distance of 100m is normally far than enough for most
clients enough for most clients' requirements and most economic way. But some clients
would like to control the display in a further distance than 100m, or even thousands of Km.
For these cases the remote control by internet will be chosen.
For to realize controlling remotely the LED screen by internet you need the following:
 The internet connection ror both locations, for the LED screen as well as for the
controlling PC;
 Two PC's, one for to place at the LED screen and the other one to control the LED
screen remotely.
At last, we will introduce the signal transfer in a simple way. For most people it's not strange
to know that one PC can control another PC through internet. And the essential of LED
display remote control is the same. But our software will combine and set the control in a
convenient method. And the operator will easily control the display from quite a far distance.
For the detailed information please ask our sales for the manual of control system.
Wireless GPRS Solution for LED
Display Screens
The usage of LED display screens is getting wider, such as advertising LED screens, traffic
LED screens, etc. However, users have to do a lot of work to update the LED displays
contents due to numerous numbers and widely distribution. In order to solve this problem,

our company has successfully researched and developed LED display screens control systems
based on GPRS. As long as users can access the internet and find the control card which
connects with GPRS, they can control display contents and achieve off-site control. In this
way, users can solve problems by transmitting over a long distance and with one PC it
controls multiple LED display screens.
GPRS Traits for LED Display Screens
1. Making efficiencyreliable TransmissionControl Protocol (TCP)based onfeaturesof GPRS
communicationsoasto adjustpacketstransferrates(Mbps) and use GPRS bandwidth
effectively,average ratescouldreachto15kbps.
2. SupportingTransmitDataSearchingandDocumentResuming.Itjusttransmitsthe
amendmentparteverytime soasto reduce GPRS trafficandsave costsfor customers.
3. GPRS not onlycan transmitsimple textsmessage butalsopicturesandvideos.
4. ProgrammingSoftware willprocessvideosandpicturesaccordingtothe screen’ssize then
transmitthroughharmless compressionandstorage,makingastorage cell can perform
informationasmuchas possible.
LED Screen GPRS System Structure
1. Connectingusers’PCwithADSLrouterbyLAN line,insertingADSLrouterintoInternetby

telephonelineorinotherways.
2. Connectingcontrol cardwithGPRS modulesbyserial port232.
3. Connectingcontrol cardwithdisplayscreenbynormal adapterplate andflatcables.
Compositions of LED Screen GPRS Main Hardware and
Software
LED ScreenGPRS Hardware
1. ADSL router(recommendedtypes:TP-LINK,TD-W89541G)
2. LED displayscreencontrol card(ourcompany’sM-seriescontrol cards)
3. Normal adapterplate (HUB: usedforconnectingdisplayscreenwithcontrol card)
4. LED displayscreen
5. Users’PC that can control LED displayscreen(needtoinstall LEDEditorSoftware)
LED ScreenGPRS Software
1. Name of LED displayscreencontrol card:LED Editor
2. WirelessM-GPRS.exe software
3. Interface screenshotof LEDEditorSoftware as showninimage 1 below
4. Interface screenshotof M-GPRSwirelessSoftware asshowninimage 2 below

LED Screen Power Consumption
Explained
One of the most asked questions is how to calculate the maximal power consumption of a
LED screen. Well first of all, you should know the input current and the voltage of the LEDs
on the LED screen. Theoretically, in a labratory environment the greatest input current of the
LEDs on a LED screen is 20mA, and the voltage for the LEDs for the LED screens is 5V.
But in reality, the current of the LEDs of a LED screen can't reach 20mA. So the power
consumption of a LED is 20mA x 5V = 0.1W. So it is very simple how to calculate the power
consumption of one LED on a LED display.
Pixel Configuration of LED Displays
And secondly, what you should know is the pixel configuration of the LED display and the
resolution per square meter of the LED display. When you get this data you will know how
many LEDs are available on the LED display. For example, let's take a LED display with a
pixel pitch of P16mm, the pixel configuration is 2R1G1B, which means that each pixel
consists of 2 red LED's, 1 green LED and 1 blue LED. So this means that every pixel has 4
LED's. And the resolution per square meter of pitch 16mm LED display is 3906 pixels, which
means there are totally 3906 pixels in one square meter. According to the previous data the
calculation will be as folows: 4 x 3906 = 15,624 total LED's per square meter for this LED
display.
Maximal Power Consumption for LED displays
There are two types of driving methods for LED displays, which is the constant static driving
method and the scan driving method. First let's explain how to calculate the maximal power
consumption and average power consumption of a pitch 16mm LED display using constant
static current driving.
ConstantStatic CurrentDrivingMethod
The maximal power consumption of a pitch 16mm LED display is 15624 x 0.1W = 1.56Kw
pero square meter. The average power consumption of a pitch 16mm LED display is 1.56Kw
/ 2 = 780W. This calculation way is for static constant current driving LED displays.
ScanDrivingMethod
For scan driving LED displays, you must notice that it has a 1/4 driving, 1/8 driving or 1/2
driving. Taking a pitch 6mm indoor LED display as an example, the usual driving method is
1/8, so if you calculate according to above way, the maximal power consumption of a pitch
6mm indoor LED display will be extremely high and gives us more than 8Kw per square
meter. But in reality it is not correct, the reason is that you need to make the total calculation
result divided by 8 because the driving method is 1 over 8 (1/8), and like that you get a
maximal power consumption of 1.1Kw per square meter.

The Relationship between LED Screen
Brightness and Viewing Angle
What is the difference between a LED screens' brightness and viewing angle. Well depending
on the environment (indoor or outdoor) where a LED screen is installed, the requested
brightness of a LED screens is different according to the environmental contrast ratio.
Difference between Indoor LED Screens and Outdoor
LED Screens Brightness and Viewing Angle
Indoor LED screens request a lower brightness but request a high viewing angle. On the other
hand outdoor LED screens' request a higher brightness, and also a much better better grey
grade. Therefore the outdoor LED screens' viewing angle request is not as high as an indoor
LED screen, generally between ± 35--± 50 degrees.
Relationship between LED Screens' Brightness and
Viewing Angle
If the viewing angle of the LED screen becomes lower, the LED screen brightness will be
higher, or vice versa. If the contrast ratio between LED screens' brightness and environmental
brightness is higher, the led screens' showing performance will be more colorful. However, if
the brightness of the LED screen is too high, it is bad for the human eye, and much more
power consumption will be wasted. Also much more heat will be produced, and then the
temperature becomes much higher. For that the led chip's brightness decreases much faster,
and of course, its lifespan will become shorter.
Conclusion
Hereby, LED screens brightness and viewing angle should be applied to the LED screens'
environment.
What LED brand to
choose when buying a
LED screen
The LED's are surely the most important quality criteria when
it comes to LED video displays. They determine the image
quality of the display and are decisive in determining how the
image quality is retained over time. The quality
characteristics for LED's are very diverse, and, here too, the
maxim applies: the most expensive choice is not always the
best choice. To highlight an example from the automobile
industry: You are sure to be able to spontaneously list a

variety of luxury sedans, though you may not generally
consider these when selecting a new vehicle. Price and
purpose play major roles in the decision of which model to
choose. And also, luxury sedans differ in many ways,
although they often all meet the highest quality standards.
The quality of an LED is determined primarily by the chip
used. It determines the service life of the LED and how the
lighting behavior of the LED changes over time. The mayor
Chip manufacturers of LED's are:
 Nichia (Japan)
 Cree (USA)
 AXT (USA)
 Epistar (Taiwan)
 Silan (China)
The prevailing opinion on the market today is that LED's
made by Nichia are the best for use in LED video displays.
However, they are also undeniably the most expensive LED's
on the market by a wide margin. The price of LED's varies on
average from less than one cent per LED to up to 15 cents
and more, depending on the type of LED (RGB LED's with
three chips in one housing are often more expensive). An
extensive price difference can arise in manufacturing,
depending on the LED's used.
The most important factor for purchasing a LED screen and
determining which LED's to choose are:
 Brightness: The brightness of the LED's is measured
in mcd (milli-candela). The higher the brightness, the
better. You can run the display at a lower brightness,
thus increasing the service life or increasing visibility
during the day when the sun is shining.
 Electrostatic Discharge(ESD): The LED chips
produced by various manufacturers differentiate
themselves through a varying sensitivity to the effects
of electrostatic discharge (for example due to contact).
Display failures caused by electrostatic discharges can
be prevented by implementing safeguarding measures
against ESD in the production process. The following
LED chips listed are indicating the voltages that the
LED's can withstand in case of electrostatic
discharges:
o Cree: 2000V
o Nichia: 1000V
o Taiwanese LED Chips: 800V
o Chinese LED Chips: 200~800V
 Sensitivity to Temperature Variations: Poor LED

chips can fade faster, i.e. their service life can shorten,
if they are exposed to high temperature variations.
Depending on the country, temperatures can become
extremely hot or cold during the summer or winter
months, respectively. As a result, a poor LED quality
could cause premature fading of the overall, expensive
LED display.
 General Service Life: The general service life of the
LED's often lies between 50,000 and 100,000 hours.
(100,000 hours equates to 10 years of continuous
display operation at full white, if no other factors exist
which reduce the service life; such as increased heat
in the display housing, or operating the LED's at
overvoltage in order to balance brightness reduction.
 Brightness Reduction due Aging: Below is a table
indicating the lighting reductions which arise within
the first 10,000 hours: LED brightness reduction after
the first 10,000 hours, sorted by manufacturer:
Nichia
(Japan)
Cree
(USA)
AXT
(USA)
Silan
(China)
Epistar
(Taiwan)
Red
LED
2.5% Unknown Unknown Unknown 28%
Green
LED
2,50% 26% 8% 7% 28%
Blue
LED
2,50% 45% 8% 7% 28%

For the advertising screens we recommend always Silan
LED’s, or the Cree LED’s which are a little more expensive
than the Silan LED’s. Nichia LED’s, which are at least twice
as expensive than Silan LED’s, for LED screens is mostly
used for the professional industry like on stages or for
television programs where quality is of high importance due
to the high brightness and longer lifetime, and professionals
invest a higher amount to have the screen performance and
quality optimal at all times if not they are out of business and
glamour is important in those industries. For advertising
screens which are placed outside that quality is not necessary
to be as optimal as the professional industry like stages or
television programs because the screen is seen as an
investment to shorten the ROI to less than 1 year and using
the screen for advertising for over a period of at least 5 years
to 8 years and gain 5 to 7 years from advertising.
If investing in Silan LED’s the initial investment is about

25%(Cree) to 50%(Nichia) lower than investing in Cree and
Nichia LED’s. So for that Silan LED’s will have an ROI of
around 1 year depending on the portfolio of clients that the
screen owner has, the place where it is placed and price of the
advertisements. When advertisers want to publish their
products on the screen, of course quality is important but in
practical terms the selling price of the commercial space on
the screen will be the same if used Nichia or Silan or Cree
LED’s because they don’t care about the lifetime and
differences of brightness between Nichia, Silan or Cree
LED's, they just want to be seen and promote their products
and or services on the screen. What is important for the
publicity clients is the resolution, if it doesn’t look pixelated
they do see that as a plus and will attract more advertisers
because the better the resolution the higher the impact of the
advertisement and the higher the company’s goodwill of the
product announced. Also for Nichia and Cree LED’s the ROI
is one and a half to twice the time in comparison to Silan
LED’s which is two years at least.
Normally Silan and Cree LED’s need 100,000 hours to reach
around 40% of its total original brightness, Nichia will need
100,000 hours to reach 60% of its total original brightness.
This is because the materials used are much more expensive
for the Nichia LED’s than for the Cree and Silan LED’s and
are better conductors. Besides Nichia uses around 50% of the
energy used to burn the LED’s in comparison to the Silan and
Cree LED’s. For example 1sqm of 16mm pixel pitch Silan
and Cree LED’s consumes around 1200W/m2 and Nichia
575w/m2 which is less than 50% to get the same amount of
brightness.
Many of the quality factors for LED's play a role in how they
behave over time. Nichia LED's are the only ones for which it
is generally known that they thoroughly meet the required
criteria, positively setting themselves apart from other LED's
on the market. The long-term values for some of the other
manufacturers were not available. Many developments in the
LED field are so new that long-term values over five, ten, or
more years don't exist yet. If price and performance should be
balanced, we recommend LED's with Silan chips. In terms of
overall service life, Silan LED's are 1/3 weaker than Nichia
LED's but they cost significantly less. With the service life of
Silan LED's, you can run your display for 6 years of
continuous operation at full white, although running the
screen at full white is never done in reality. In displaying
average video image content, the effective service life
increases by two to four times as much, that is, 14 to 28 years,
depending on the image content. In contrast to the still very
expensive Cree LED's, Silan LED's age more evenly and also

don't have as much lighting reduction after 10,000 hours. This
proves particularly lucrative when exchanging individual
pixel cards, since the calibration requirement is lower.
Color Depth
(Gray Scale)
of LED
Displays
The LED display color depth, or gray scale, indicates the process depth of the colors showed
by a LED display. When looking at the technical specifications of a LED display given by
LED display suppliers you can always find values like "12-bit, 14-bit, 16-bit". Many clients
and even sales executives don't know what this value means. For that this article will explain
what the color depth, or gray scale, means.
 1-bit color (21 = 2 colors): often black and white
 2-bit color (22 = 4 colors)
So from above table, it's not difficult to find the color depth actually shows how many colors
can be shown on the LED display.
As well-known, LED display is RGB color model, and each pixel consists of red, green, and
blue color LEDs. And here we will explain further about it in below table:
 12-bit: there are 4 bits (16 possible levels) for each of the RG,B LEDs. So it would
show totally 16x16x16=4096 kinds colors.
 14-bit: In 14-bit process depth, there's a little difference from 12-bit. For the reason
that human eyes are not so sensitive to blue, than red or green. So it is assigned one
bit less than the others. So for red and green, there are 32 possible levels, and for
blue, there's 16 possible levels. So totally it can show 32x32x16=16384 colors.
 16-bit: It is very similar with above. But this time it's due to the green color are most
sensitive to human eyes. So it's assigned one bit more than the others. So for red and
blue, there're 32 possible levels. And for green, there are 64 possible levels. So it can
show totally 32x32x64=65536 colors.
Within the LED display industry many LED screen suppliers do not pay that much attention
wen making the LED displays' technical specifications accurate. And the technology
homogenization is currently very serious. The true situation is, for the widely-adopted
technology, the highest color depth is actually 14 bits. It is not arbitrarily speaking because

it's limited by the hardware part.
If adopting higher level IC and system, it wont be any problem to realize the 16-bit color
depth or gray scales. But with nowadays tech, it must lose the virtual pixel technology. And
actually the 14-bit color depth or gray scale doesnt make any big difference from 16-bit
color depth for the human eye.

Led displays explained

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