How Does led display solution Work?

Display technology

This article is about light-emitting diode (LED) based displays. For LED-backlit displays, see LED-backlit LCD . For matrixed text displays, see Dot-matrix display

Not to be confused with Vacuum fluorescent display

Detail view of an LED display with a matrix of red, green and blue diodes

A LED display is a flat panel display that uses an array of light-emitting diodes (LEDs) as pixels for a video display. Their brightness allows them to be used outdoors where they are visible in the sun for store signs and billboards. In recent years, they have also become commonly used in destination signs on public transport vehicles, as well as variable-message signs on highways. LED displays are capable of providing general illumination in addition to visual display, as when used for stage lighting or other decorative (as opposed to informational) purposes. LED displays can offer higher contrast ratios than a projector and are thus an alternative to traditional projection screens, and they can be used for large, uninterrupted (without a visible grid arising from the bezels of individual displays) video walls. microLED displays are LED displays with smaller LEDs, which poses significant development challenges.[1]

A LED video cube above the ice rink at Nokia Arena in Tampere, Finland.

History

[

edit

]

Light-emitting diodes (LEDs) came into existence in 1962 and were primarily red in color for the first decade. The first practical LED was invented by Nick Holonyak in 1962 while he was at General Electric.[2]

The first practical LED display was developed at Hewlett-Packard (HP) and introduced in 1968.[3] Its development was led by Howard C. Borden and Gerald P. Pighini at HP Associates and HP Labs, who had engaged in research and development (R&D) on practical LEDs between 1962 and 1968. In February 1969, they introduced the HP Model 5082-7000 Numeric Indicator.[4] It was the first LED device to use integrated circuit (integrated LED circuit) technology,[4] and the first intelligent LED display, making it a revolution in digital display technology, replacing the Nixie tube and becoming the basis for later LED displays.[5]

Early models were monochromatic by design. The efficient Blue LED completing the color triad did not commercially arrive until the late 1980s.[1]

In the late 1980s, Aluminium Indium Gallium Phosphide LEDs arrived. They provided an efficient source of red and amber and were used in information displays. However, it was still impossible to achieve full colour. The available "green" was hardly green at all – mostly yellow, and an early blue had excessively high power consumption. It was only when Shuji Nakamura, then at Nichia Chemical, announced the development of the blue (and later green) LED based on Indium Gallium Nitride, that possibilities opened for big LED video displays.

The entire idea of what could be done with LED was given an early shake up by Mark Fisher's design for U2's PopMart Tour of 1997. He realized that with long viewing distances, wide pixel spacing could be used to achieve very large images, especially if viewed at night. The system had to be suitable for touring so an open mesh arrangement that could be rolled up for transport was used. The whole display was 52m (170ft) wide and 17m (56ft) high. It had a total of 150,000 pixels. The company that supplied the LED pixels and their driving system, SACO Technologies of Montreal, had never engineered a video system before, previously building mimic panels for power station control rooms.

Today, large displays use high-brightness diodes to generate a wide spectrum of colors. It took three decades and organic light-emitting diodes for Sony to introduce an OLED TV, the Sony XEL-1 OLED screen which was marketed in 2009. Later, at CES 2012, Sony presented Crystal LED, a TV with a true LED-display, in which LEDs are used to produce actual images rather than acting as backlighting for other types of display, as in LED-backlit LCDs which are commonly marketed as LED TVs.

Large video-capable screens

[

edit

]

The 2011 UEFA Champions League Final match between Manchester United and Barcelona was broadcast live in 3D format in Gothenburg (Sweden), on an EKTA screen. It had a refresh rate of 100 Hz, a diagonal of 7.11 m (23 ft 3.92 in) and a display area of 6.192×3.483 m, and was listed in the Guinness Book of Records as the largest LED 3D TV.[6][7]

Development

[

edit

]

Early prototypes

[

edit

]

A claim for the 'first all-LED flat panel television screen' is presented in this section. It was possibly developed, demonstrated and documented by James P. Mitchell in 1977. Initial public recognition came from the Westinghouse Educational Foundation Science Talent Search group, a Science Service organization.[8][verification needed] The paper entry was named in the "Honors Group" publicized to universities on January 25, 1978.[9] The paper was subsequently invited and presented at the Iowa Academy of Science at the University of Northern Iowa.[10][11] The operational prototype was displayed at the Eastern Iowa SEF[12] on March 18 and obtained a top "Physical Sciences" award and IEEE recognition. The project was again displayed at the 29th International SEF at Anaheim Ca. Convention Center on May 8–10.[13] The ¼-inch thin miniature flat panel modular prototype, scientific paper, and full screen (tiled LED matrix) schematic with video interface was displayed at this event.[14][15] It received awards by NASA[16] and General Motors Corporation.[17][18][19] This project marked some of the earliest progress towards the replacement of the 70+-year-old high-voltage analog CRT system (cathode-ray tube technology) with a digital x-y scanned LED matrix driven with an NTSC television RF video format. Mitchell's paper and operational prototype projected the future replacement of CRTs and included foreseen applications to battery operated devices due to the advantages of low power consumption. Displacement of the electromagnetic scan systems included the removal of inductive deflection, electron beam and color convergence circuits and has been a significant achievement. The unique properties of the light-emitting diode as an emissive device simplify matrix scanning complexity and have helped the modern television adapt to digital communications and shrink into its current thin form factor.

The 1977 model was monochromatic by design.

Recent developments

[

edit

]

MicroLED displays are currently under development by numerous major corporations such as Sony, Apple, Samsung, and LG.

These displays are easily scalable, and offer a more streamlined production process. However, production costs remains a limiting factor.[20]

The 40m large LED display at the Armin Only event in April 2008 in the Jaarbeurs Utrecht

See also

[

edit

]

References

[

edit

]

• LED displays at Wikimedia Commons

There was a time when buying a display meant evaluating if you could even afford the space or the money for one. However, things have changed since then as those bulky CRT displays gave way to LCD (Liquid Crystal Display) technology.

But even LCDs didn’t last long, as technology got better and better. LED screens took over the market, and the leading LED screen manufacturer brands have dominated ever since.

Many people looking to buy a display wonder what an LED display is and how it functions. So in this article, you will learn all about LED screens, display types, how they work, and why you should get an LED screen.

Looking to buy? Check out our guide to buying an LED Display.

What is an LED Display?

LED stands for Light Emitting Diode. These diodes are tiny little bulbs that you might have seen on electronic devices.

Large LED displays use a large number of these diodes to light up the screen. These diodes are low power consumption devices that provide high brightness. As a result, an LED screen has several benefits over other display alternatives.

The fluorescent bulbs used earlier could only give black and white tones. However, an LED screen can display the entire colour spectrum by combining red, blue, and green colours (RGB).

The advantages of an LED screen are so many that you can find LED screens everywhere. From TVs to computer monitors to high-resolution billboards in shopping centres and LED video wall applications.

Short History of The Evolution of LED Displays

Even though LED display technology has become popular in the last 5-6 years, the evolution of the LED screen has taken over half a century. Here are some keystone events in this evolution:

• Nick Holonyak, an employee of General Electric, invented the first LED in 1962. It was a red LED and only red LEDs were available for the next 10 years.
• In 1969, Hewlett Packard made the first LED display- the HP Model 5082-7000 Numeric Indicator.

Image: HP Model 5082-7000 Numeric Indicator

• The first real application of an LED display takes place in U2’s Popmart tour of 1997. The display was 52m wide, 17m high, and used 150,000 light-emitting diodes. It was made on a mesh that could be rolled up for transport.
• In 2008, Sony created the world’s first OLED television, which was also the world’s thinnest TV at the time at a thickness of just 3 mm. This OLED television brought the benefits of LED screens to the limelight.
• By 2014, the manufacturing of plasma TVs was stopped in the US and replaced by LCD and LED televisions.

How Do LED Displays Work?

LED displays make use of a huge collection of light-emitting diodes on a flat panel. These diodes are either red, blue, or green. Each of these diodes is capable of emitting light of different brightness.

Just like you learned in art class, two or more colours can combine to create new colours. Similarly, red, blue, and green light from these diodes combined in varying ratios create every colour on the spectrum.

If you get close enough to an LED display, you can notice the individual diodes on the television panel.

Important Technical Terms to Know

While we are talking about LED technology, here are some technical terms that you should be familiar with:

• Pixel Pitch – Pixel pitch is the distance between the centres of two adjacent individual pixels on the LED panel. A short pitch results in high resolution and better picture quality. The minimum viewing distance from the LED display is also determined by the pixel pitch. If you view the LED display from a closer distance, you can spot the individual LEDs.
• Pixel Density – Pixel density is the number of pixels present on a given area of the screen. Generally, it is measured in pixels per inch (ppi). The quality of an image displayed on a screen improves significantly as the pixel density increases. Note that pixel density in smaller devices like the screen on your smartphones is considerably higher than large devices like a television or LED video wall. For instance, an iPhone may have a pixel density of over 458 ppi, while a 50-inch 4K TV might have only 80 ppi.
• LED Viewing Angle – The angle from the centre of the LED display at which picture brightness becomes less than 50% of the nominal. In simple terms, this angle tells us the maximum position at which the viewer can still clearly see the display image. For instance, if the angle is 40 degrees, the viewer can still see the image correctly 20 degrees left and 20 degrees right of the screen.
• LED Scan Rate – LED scan rate is a ratio that represents how much of the LED array lights up at a given point. For instance, a scan rate of 1:16 means 1/16th of the LEDs is lit at any given instant. After, the display moves to the next 1/16th. Not all the LEDs are activated. Doing so would result in high power consumption and require more processing power. Instead, a fraction of the LED array is lit at a given instant. Then the principle of Persistence of Vision is used, which means the image our eyes see lasts for a fraction of time.

What are the Different Types of LED Displays?

Based on their construction, LED screens can be categorized into various types. Each of these types has its purpose. Here are a few of the common categories:

Dot-Matrix LED Display

Dot-matrix LED displays are used to show numbers, alphabets, characters, and simple graphics. These displays consist of a rectangular array of LEDs followed by a space. They can be mounted serially to create a dot-matrix display.

These diodes are programmed to light up according to the number or character that is to be displayed. Each character requires about 5×8 pixels (or LEDs).

Because there is individual control over each LED, a dot matrix display provides more details and intricate graphics than a segmented display.

These displays can be used in meters, industrial controls, medical equipment, billboards, hoardings, and other uses.

7-Segment Display

7-segment displays are used to present numbers by splitting the display into 7 light segments.

These segments are arranged in a formation that looks like the number ‘8’. In this formation, every number from 0-9 can be presented by lighting the appropriate segment of the display.

These displays are one of the most common and simple and you will find them anywhere numbers are to be presented. A common example of this is digital clocks, digital thermometers, calculators, and other digital communications devices.

It is important to note that while 7-segment displays can recreate all the numbers, they cannot be used for lettering.

14-Segment LED Display

14-segment displays retain the basic 7-segment shape, plus additional LED segments placed in the diagonals and centre of the 8 shape.

These added sections make it possible to display letters along with numbers. This configuration is also known as the Starburst LED display.

These displays were popularized by arcade games in the ’80s. Even today, they are used in a wide range of applications that require specific requirements, such as a retro look or a simple alphanumeric display.

16-Segment LED Display

16-segment LED display improves upon the 14-segment design by further splitting the top and bottom horizontal segments of the 8-figure. The addition of these segments adds some clarity when displaying alphabets.

Complex LED Displays

Segmented and dot-matrix designs are sufficient for basic graphics and alphanumeric characters. But they are unsuitable for purposes such as TV, computer monitors, or other displays that require recreation of a complete spectrum of colours and complex graphics.

For this purpose, the LED screens are large-scale in nature, employing millions of LEDs. Unlike the segmented displays, the complex large-scale arrangements do not have segments or gaps between the LEDs.

Benefits of LED Displays

One important question to ask at this point is ‘why are LED displays so popular?’. If you remember the LED technology that we mentioned earlier, you might have guessed the benefits it can provide.

Even so, the advantages of LED displays are far more than what meets the eye at first glance. Some of them are:

• Size: Light-emitting diodes are tiny. For this reason, LED displays are smaller than any other alternative display technology that you can think of. They can be one-third the thickness of an LCD of the same screen size.
• Power Consumption: LEDs consume a minimal amount of electricity. Therefore, even a large LED display consumes a fraction of the electricity consumed by similar-sized LCD screens.
• Image Quality: LED screens have an RGB contrast, which means they can recreate true blacks and true whites. This creates a better image quality than other displays.
• Lifespan: Due to no moving parts and a simple design, LED displays tend to last longer than LCD screens or other displays.
• Viewing Angle: LED displays are evenly lit. Therefore, they provide a wider viewing angle.
• Eye Strain: LED displays offer greater control over high brightness and other features that can help reduce eye strain.

What are the Applications and Uses for LED Displays?

Today, LED display solutions are used in a wide range of applications. Some of these include:

• Television: TVs are the most popular application of LED screens right now. LED TVs have replaced almost the entire plasma and LCD screens market. Even within LED TVs, multiple technologies have come up, like the OLED and QLED TVs.
• Monitors: Computer monitor technology goes hand in hand with television technology. This is why monitors have also shifted towards LED technology. These are perfect for all computing applications, be it entertainment, work, or gaming.
• Smart Phones: Smartphone screens are crossing boundaries of high-definition picture quality, all thanks to LED displays. LED displays in smartphones are ultra-thin, with very high pixel quality.
• Advertising: There is no limit to how large an LED display sign can be. This is why outdoor and indoor screens are very popular nowadays for LED advertising and digital signage. You can find them used on all types of business, entertainment and sports events.
• Electronic Devices: Simple LED displays (like segmented displays) are used in electronic panels for showing alphanumeric characters.

How are LED Displays Going to Develop in the Future?

Even though LED screens have already replaced display technology everywhere, they still keep on evolving.

CRT displays remained in use for more than three decades. LED technology has been popular for only about six years, so it can be expected that it is going to remain for a long time.

One of the major driving factors for these displays is the various use cases outside of replacing television and indoor LED screens. Large LED displays such as LED video walls for advertising and digital signage in shopping centres are now common. These solutions make LED display technology much more diverse than any previously available solution.

While LED screens are already thinner than other alternatives, the size can be expected to be toned down even more. Another prediction is that the size of individual diodes decreases, thereby increasing the pixel density and significantly boosting the quality of an image on even the largest outdoor screen.

Endnotes

If you are thinking about buying an LED display for your personal or professional needs, don’t doubt your decision.

LED screens are the best technology available right now, whether you consider it as television on your living room wall or an advertisement window outside your office.