LED or Light Emitting Diode was first developed in 1962, emitting red color only. In 1980 other colors emitting diodes started appearing in the market. These new LEDs could emit Blue and Green color in appreciable true form and brightness. But the idea of mixing these LEDs on a single panel to form a video display came up somewhere in 1997-98. This opened an entirely new era of using LED displays for a wide variety of numerous applications in business advertising and informational display fields.
Today LED-based digital displays are playing a pivotal role in business promotion and information display. A long list of big ‘Digital display manufacturers’ producing LED advertising screens is serving the marketing business. Manufacturers are producing LED screens in many sizes and various color combinations. They can even display videos. Same single large size screen can serve the purpose of multiple advertisements. Contents of advertisements or displays change easily adding to the flexibility of LED advertising screen.
To understand the production process of LED Screen, one should understand some basic essentials. These are vital points in the production of LED screens.
LED signs are very simple in manufacturing. Semiconductors like Indium and Gallium are the basic ingredients essential in making the LED. But how they are arranged to displace pixel to create much more attractive, visible and moving images. This is concerning the production process.
For the students of electronics, basic know-how about LED displays designing and manufacturing may be of immense interest. Generally LED advertising screens are not available off-the-shelf. The sizes of screens vary widely according to the displaying content and the video quality or duration etc.
So many digital display manufacturers are there. But for each and every LED advertising screen, big or small, concerned managers have to discuss their requirements up to minute details before finalizing production order. Business promotion managers should be aware of all nitty-gritty. Salient features about the classification of LED screens and Technical aspects may, therefore, be worth discussing here briefly. This constitutes the first phase of LED screens production process.
Before producing LED-based digital display it is necessary to know how and where is that going to be used. Only with this knowledge, one can place a production order. Every LED sign, for example, ‘LED Billboard’, have to be in a certain specific color scheme, to be placed at some desired location, and to perform some worked out function.
Digital display screens, therefore, can be classified on the basis of the following considerations:
Display site: Digital display sites consideration largely depend on potential viewers. Accordingly, digital displays may be for:
Outdoor: Large size screens for a large number of viewers in open areas, like stadiums, need outdoor LED display screens.
Colors: Depending on requirement vs cost effectiveness LED Advertising screens may be produced in various combinations of differently colored LEDs:
Single color: A single color pixel consists of one color emitting LED. It may be Red or Green etc.
Dual color: Two primary colors red and green are used in dual color screens. With various combinations of two colors, up to 65,535 colors can be used in these screens.
Full Color: In these screens, three primary colors, red, green and blue are used to make various combinations up to 16,777,216 number of colors.
Functionality: Based on functionality digital advertising screens may be one of the following types:
Graphical Screens: These screens can display graphics, like Bars, along with the text. They are best suited for stock markets. Inputs are usually computer controlled. They are rich in colors and contents.
Digital Screens: These screens display text only and are widely used in ‘rates display’ related businesses like bank exchange rates, interests rates, etc. They are comparatively cheaper.
Hybrid Screens: Combination of both features to display Text and graphics, as per requirements are also available. These may be used in stock tickers.
Still, there are many features that differentiate one requirement from other in LED display screens production process. For instance:
Pitch. It stands for pixel distances and determines resolution as well as the distance of distinct vision. While the pixel means the number of LEDs it contains, the pitch refers to the distance between pixels. For example, a full-color screen may have a pixel consisting of three (Red, Green, and Blue) LEDs, whereas P10 (say) means the distance between pixels is 10mm.
It is difficult to determine the pitch correctly but producing proper LED display solely depends on the right pitch. For smaller or indoor screen pitch varies from P3 (5mm) to P10 (10mm) while for outdoor screens pitch is above P10.
Resolution for text display is usually around 8 x 5 i.e. 8 vertically placed pixels and 5 horizontally placed pixels. Fir videos display the resolution is very high, of the order of minimum 50,000 pixels in all.
LED Encapsulation. This feature refers to how the LEDs are packed. Mainly following encapsulations are used depending on the production requirement.
Modules and cabinet size. Every LED display screen is made up of a number of cabinets each containing a number of LED modules or LED panel. A single module is an assembly of LEDs, power supply, driver IC or chip and printed circuit board (PCB).
Other important details helpful in carrying out the production process include some technical features.
How many Modules (consisting of which LED type) will be required in a particular screen production order, is screen manufacturer’s problem. We have tried our best to discuss the essential technical requirements concerning the user, below.
Brightness. The higher level of luminance of Led advertising screens gives an edge to place these screens in the sun without compromising on visibility. Following comparison show clearly why giant LED advertising screen is more in demand. The brightness of light emitted per square meter or NITs (international unit for measurement of luminosity) of LED screens is much higher than LCD or flat screens.
The angle of vision. Adequate perception of image on the screen and on viewers depends on ‘Angle of vision’. It is a horizontal and vertical angle with respect to the perpendicular view of the screen. The horizontal range of angle vision is 120 to 160 whereas the vertical range is 90 to 160. To cater to the angle of vision, the type of LED used in LED advertising screen is equally considerable. SMD and Vandal resistant LED provide a better angle of vision because their LEDs of primary colors are available in one capsule. DIP, on the other hand, have primary color LEDs packed separately, can’t give a better angle of vision which is reduced. At extreme angles with DIP, visibility can fall to zero.
Contrast. The ratio between the best possible intensities on white and black on advertising screens is termed as a contrast. Higher ratio means more color tones capacity for display purpose.
For static images or graphics displays, the ratio between white and black is actually the real contrast. It is a bit difficult to determine as it depends on the hardware. Why because it is determined in an instant.
Dynamic contrast used for moving images is convenient to measure as it does not depend on hardware. For contrast, Indoor LED screens use commercial LED called Black LED.
Refresh frequency. So fast LEDs go on and off that it is imperceptible to the human eye. The images thereby are drawn and redrawn so a many times per second (Refreshing the screen), called frequency. The measuring unit of frequency is Hertz.
value depends on the hardware. High refresh frequency produces smoother images in dark scenes moving faster. Entertainments pertaining to media sector use high refresh frequency hardware.
Color Temperature. This shows how a white screen will look under different lights. Generally, there are here categories of color temperatures.
Vision Distance. It is the distance that has to be determined for distinct vision. To this end pixel pitch provide us to choose suitable pitch and hence LED density differently in small or large LED screens.
It is critical to choose the correct number of LED for a distance of vision because there is a number for specific distance for which using more LEDs will be useless.
Work Temperature. This means maintaining the particular temperature for working of cabinets. All LEDs and electronic components connected together placed in bigger assembly, called Cabinets, need to have good refrigeration. The working temperature or operating temperature range is another major consideration while designing modules/cabinets, for longer and continuous use of display screens.
For the longevity of LED and better performance temperature maintenance is important. The ideal temperature for LED to operate is 40 to 45 degree Celsius. Brightness will reduce at temperatures higher than this range.
Energy consumption. The economy of energy consumption is an important factor. This should be the main consideration prior to manufacturing LED screen. Energy consumption depends on screen size, brightness level and number of LEDs. More brightness means more energy consumption. Whereas we need more bright screens only while displaying in times of full sunlight. At other hours, the automatic reduction in brightness level may save electrical energy considerably.
Electrical power consumption, however, is essential for larger screens where the above-mentioned techniques are quite useful. As far LED screens in small size are concerned, they don’t need energy consumption economy to compensate investment.
That is all about what a business manager considering advertising with LED screens, should essentially be aware of. The digital display manufacturer thoroughly considers the well worked designs.
Invariably the digital display manufacturer receives the customized designs of digital displays. This is where the second or the final phase of digital display production undergo.
Order approval is the first step at a manufacturing factory. After approval technically verification is the following step and then the components assembly starts. After initial testing, debugging and quality checks shipping of screens take place according to schedule. The final installation is flexible. Either of the manufacturer or the customer (using installation manuals) can carry it out.