FAQs

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.

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:

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 8×8 or 4×4 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 6×8). This is seen on most graphic calculators, such as CASIO calculators or TI-82 and superior.
• A smaller size is 3×5 (or 4×6 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.

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?

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.

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.

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.

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.

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:

n 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.

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 efficiency reliable Transmission Control Protocol (TCP) based on features of GPRS communication so as to adjust packets transfer rates (Mbps) and use GPRS bandwidth effectively, average rates could reach to 15kbps.
2. Supporting Transmit Data Searching and Document Resuming. It just transmits the amendment part every time so as to reduce GPRS traffic and save costs for customers.
3. GPRS not only can transmit simple texts message but also pictures and videos.
4. Programming Software will process videos and pictures according to the screen’s size then transmit through harmless compression and storage, making a storage cell can perform information as much as possible.

LED Screen GPRS System Structure

1. Connecting users’ PC with ADSL router by LAN line, inserting ADSL router into Internet by telephone line or in other ways.
2. Connecting control card with GPRS modules by serial port 232.
3. Connecting control card with display screen by normal adapter plate and flat cables.

Compositions of LED Screen GPRS Main Hardware and Software

LED Screen GPRS Hardware

1. ADSL router (recommended types: TP-LINK, TD-W89541G)
2. LED display screen control card (our company’s M-series control cards)
3. Normal adapter plate (HUB: used for connecting display screen with control card)
4. LED display screen
5. Users’ PC that can control LED display screen (need to install LED Editor Software)

LED Screen GPRS Software

1. Name of LED display screen control card: LED Editor
2. Wireless M-GPRS.exe software
3. Interface screenshot of LED Editor Software as shown in image 1 below
4. Interface screenshot of M-GPRS wireless Software as shown in image 2 below

Interface screenshot of M-GPRS wireless Software as shown in the image below:

Configure M-GPRS for LED Screens

The factory default configuration has completed, connecting the M-GPRS with the control card directly as shown below.

Factory default, do not need configure anymore, if you want to change M-GPRS configuration, please refer to notes: methods of changing M-GPRS DTU configuration.

Operating steps of PC-Console

There are three steps to configure the PC console:

Step 1: Run M_GPRS.exe software then input following parameters, as shown in image below:

Step 2: Select GPRS DTU of on-line screen which needs to be operatedmap out port. As shown in the image below:

After confirming, users can see mapping port, as shown in the image below:

Step 3: Run Led Editor softwareselected serial port in step 2, as shown in the image below:

Note: this is virtual serial port so its baud rate may be any values in down-drop box.

Configuring LED Editor for LED Screens with One Control Card

One PC only controls one control card connecting with M-GPRS DTU. Configuration steps of Led Editor as follows: Click “Options” on menu → Software Setup → select “Communication parameters”: tick the box in the front of “stand-alone mode”, GPRS. As shown in the image below:

After this, users can connect GPRS with screen just as simple as connect local serial port with screen by LAN.

Configuring LED Editor for LED Screens with Multiple Control Cards

One PC can simultaneously control multiple control cards connecting with M-GPRS DTU. Configuration steps of Led Editor as follows: Click on “Options” in menu → Software Setup → select “Communication parameters”: tick the box in the front of “Multi-mode”, input password, (default password is 888). As shown in the image below:

Communication type is GPRS and there is VSP port table, as shown in the image below:

Screenshot of sending program by GPRS under multi-mode condition, as shown in image below:

Methods of changing M-GPRS DTU configuration

Configuration preparation and connection. You can insert web-enabled GPRS data card into SIM connector then connect M-GPRS configuration serial port with PC port by serial port line, at last, connect M-GPRS antenna.

Login configuration interface, three steps are needed:

Step 1: running M-GPRS-DTU-CF.exe software, click on “options” button then select the serial port that PC can connect with M-GPRS in the box of “COM”, click OK. Click on “start configuration”. As shown in image 20-13 in below:

Step 2: turn on M-GPRS power (power port is inner positive and exterior negative).

Step 3: when version information appears in configuration box, please press “enter” into configuration interface.

Note: turn on M-GPRS power within 15 seconds after clicking on “start configuration”.

Configure M-GPRS parameters

Step 1: configure “date center domain name/IP”, input IP address then press “enter” into the next step.

Step 2: configure “DSC port”input DSC monitoring port then press “enter” into the next step.

Step 3: configure baud rate which consistent with control card, have eight numbers and end number is 1.

Step 4: other parameters can be omitted, press “enter” until “storage configuration” and “restart” appear then input “YES” to complete configuration. At last, turn off power and restart.

Note: please inquiry suppliers about DSC domain name/IP and port.

Methods of configuring serial port baud rate of the control card

Serial port or internet connects with control card under stand-alone moderunning Led Editor → Menu → Options → Hardware Setup Baud rates of COM-R232 and M-GPRS must keep consistent with each other. As shown in the image below: