Difference between LCD and LED

LCD stands for "liquid crystal display". LED stand for "Light Emitting Diodes” also work on the base of liquid crystal displays.  While both LCD and LED  TVs base on liquid crystals system, it’s the backlighting that really makes them different from one another. All the LED TVs are basically LCD but all the LCD TVs are not LED,s simple just as all the eagles are birds but all the birds are not eagles.

Liquid crystal display explained

Liquid crystals to help create an image in both the LCD and LED TVs, The difference in these both are the backlights.  While a standard LCD uses fluorescent backlights, an LED uses light-emitting diodes for backlights.  LED monitors usually have superior picture quality, but they come in varying backlight configurations.  And some backlight configurations create better images than others which is generally known as different resolutions.

LCD vs LED a brief history

Plasma display were most common display before liquid crystal display until 2014. Than this system replaced by liquid crystal system in LCD TVs and LED TVs.

Liquid crystal 

There are three state of matters liquid solid and gases , out of these there are some strange blend of different states .

A liquid crystal is a substance that has properties of both a solid and a liquid.  When you get to the upper tiers of science, you begin to discover that everything you once knew is wrong.

The arrangements of molecules in liquid crystal is Typically, bunch up dense and unstructured.  But when the liquid crystal is exposed to electricity, the molecules suddenly expand and arrange themselves into a very structured, interconnected shape.

Pixel

Pixels are the basic building blocks of a digital image.  A pixel is a small dot that can emit colored light.  Your display is composed of thousands of pixels, and they're in a variety of different colors to give computer interface and the webpage that you're currently reading and video or image which your seaing like on LCD and LED TVs screens.

Every pixel is composed of three basic color filters, which are called "subpixels."  There's RGB-colured known as red, blue, and green subpixel for every pixel.

How display work in LED and LCD TVs

Every pixel is composed of two glass sheets, and the outermost sheet has the subpixels. The liquid crystals are sandwiched between the two sheets.

Backlight behind the screen produced white light liquid crystal is in there liquid arrangement known as randomly arrange light can't pass through it but while pixel is used when electricity applied they arrange themselves in orderly arrangement straighten out to allow light pass through it.

Main difference is type of backlighting 

Standard LCD monitors employ “cold cathode fluorescent lamps,” also known as CCFLs as backlights. These fluorescent lights are evenly placed behind the screen so that they deliver consistent lighting across the display. All regions of the picture will have similar brightness levels. Commonly Known as backlighting full-array.

LED TVs used  light-emitting diodes,”instead of fluorescent lamp. which are extremely small lights. There are two methods of LED backlighting: full-array backlighting and edge lighting.

With full-array backlighting, the LEDs are placed evenly across the entire screen, similar to an LCD setup. But what’s different is that the LEDs are arranged in zones. Each zone of LED lights can be dimmed (also known as local dimming).

Local dimming is a very important feature that can dramatically improve picture quality. The best images are ones that have a high contrast ratio; in other words, images that have both very bright pixels and very dark pixels simultaneously.

When there’s an area of the picture that needs to be darker (a night sky, for instance), the LEDs in that region of the picture can be dimmed to create a truer black.

There are no local dimming capabilities in LCD,s and edge-lighted displays in LED,s.

So evenly distributed backlighting with local dimming, enhance the picture qualities in LED,s.

These are the basic difference of LCD and LED.

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TV Terminologies: Important terms to know

There are several words or terminologies that we come across while reading or discussing Televisions (TVs). It becomes especially irritating when you have to buy a TV and you are faced with too many unknown terminologies. To help you with this issue and to make you familiar with these unfamiliar terms, we have prepared a list of TV terminologies.

Smart TV

A TV set with an internal operating system and internet connectivity is called a "Smart TV".

Smart TV, also known as a connected TV, is a traditional television set with integrated Internet and interactive Web 2.0 features, which allows users to stream music and videos, browse the internet, and view photos. Smart TVs are a technological convergence of computers, televisions, and digital media players.

Android TV

Android TV is a smart TV that uses the Android operating system. 

Generally Android TV is a smart TV operating system based on Android and developed by Google for television sets, digital media players, set-top boxes, and soundbars. A successor to Google TV, it features a user interface designed around content discovery and voice search, content aggregation from various media apps and services, and integration with other recent Google technologies such as Assistant, Cast, and Knowledge Graph.

Chromecast

Chromecast built-in is a technology that lets you cast your favorite entertainment and apps from your phone, tablet or laptop right to your TV or speakers.

DTS

DTS stand for Digital Theater Systems. Eventually, the company officially shortened its name to the acronym DTS.

A brief background on the significance of DTS in the evolution of the home theater includes:

DTS was founded in 1993 as a competitor to Dolby Labs in the development of surround sound audio encoding, decoding, and processing technology for cinema and home theater applications.

Home theater is full of monikers and acronyms. When it comes to surround sound, things can get confusing. DTS is one of the most recognizable acronyms in home theater audio. DTS is both a company name and a label used to identify a group of surround sound audio technologies.

DTS is both a company name and a label used to identify a group of surround sound audio technologies.

Transform your favorite shows and movies with the ultra-vivid picture of Dolby Vision and the immersive sound of Dolby Atmos for a premium TV experience.

Aspect ratio

Aspect ratio refers to the width and height ratio of a TV screen and defines the shape of the TV. There are various aspect ratios for TVs and it varies as per the resolution. Certain aspect ratios are suitable for certain resolutions only, designed to offer you the best picture quality without any distortion or stretching, and to prevent any blank space on any side of the picture.

The most common aspect ratio for TVs today is 16:9. When your TV’s content and aspect ratio doesn’t match, black bars appear in the blank space (vertical bars are called pillarboxes and the horizontal bars are called letterboxes). In some TVs, you can solve this problem either by zooming in the picture, cropping the picture, or using a mix of both.

Upscaling

Upscaling basically means stretching an image with a lower resolution to fit on a larger display. In this, the pixels of the image with low resolution are copied and are repeated to fill up the display of a higher resolution. Almost every TV comes with upscaling now. In the case of HD TVs, the upscaling process makes the lower resolution images look bigger and better on the screen by increasing the pixel count.

Bezel

In simple terms, the bezel means the frame around the screen or the structural form that you can see in the front of the TV, except its screen.

Bazel less means boarder less or frame less means very narrow line of frame present in it is almost negligible or tatally absent only screen can be seen.

Contrast Ratio

The contrast ratio in a TV means the ratio between its brightest and darkest settings.

The contrast ratio of a TV can be measured on two bases i.e., native and dynamic contrast ratio. The native contrast ratio, also known as static or on-screen contrast ratio, represents the role of the TV panel while the dynamic contrast ratio involves fluctuating the LED backlights installed on the back of the screen for better contrast.

CRT

CRT or Cathode Ray Tube (also known as picture tube) in CRT TV is a vacuum tube where the images we see on TV are created.

The phosphor-coated or fluorescent screen is scanned by electron beams to form the images. In some version it have only one picture tube and some have three for primary colours called read blue and green.

Ethernet port

The ethernet port of your TV allows you to connect your TV to the internet with the help of a cable.

Frame rate

Frame rate means the speed at which the consecutive image slides are displayed. It is usually expressed as frames per second or fps. Higher the frame rate, the higher the number of frames used and it will mean more bandwidth for streaming the video.

HDMI

HDMI or High-Definition Multimedia Interface is a digital interface that helps in transferring high-definition audio and video signals through a cable. It can be used to transfer a video quality of up to 4k Ultra HD resolution, 3D videos, and multichannel surround sound in high quality.

HDR

HDR or High Dynamic Range is a feature that affects the TV’s contrast ratio and color accuracy and helps make the pictures look more realistic.

KHz

KiloHertz or kHz represents a thousand frequency cycles per second. In simple words, it is a measurement of frequency i.e., the number of times a wave repeats itself in a second. 1 kHz means 1000 times per second. It is also used to measure the signal bandwidth, digital as well as analog. In the case of TVs, higher kHz means better sound quality.

OLED

OLED (Organic Light Emitting Diode) is a display technology that uses thin organic films between the two electrodes to produce light with the help of electricity. The organic process of creating the images on the screen with the light produced is called electroluminescence, meaning that the display is self-illuminating and does not need any backlight. OLED TV panels are lighter and thinner in comparison to LCD TVs and also help in saving energy.

Over the top services

Over-the-top services or OTT services are streaming services that offer media content directly to the viewers through the internet. These services are provided by bypassing the traditional platforms like broadcast, cable, and satellite TV can be streamed on an internet-connected TV like Smart TV.

Pixelation

Pixelation means stretching of the pixels beyond their original size and it is usually caused due to a weak signal.

Plasma

Plasma is a screen technology that was used in making the first flat display panels for large TVs and was a dominant TV technology just a few years back. A plasma display panel has small cells (like tiny CFLs) which are coated with red, green, or blue phosphorus. The cells also have neon or xenon gas inside them which creates invisible ultraviolet lights. These lights are then converted into the red, green, or blue light that we see on the screen via the light emitted by these cells.

When we compare plasma with LEDs, plasma TVs are better as they have better picture quality and viewing angles. But, it also has many disadvantages, one of them being that it is now outdated technology. Also, the little cells or gas packets behind the panels can cause burn-in on your screen i.e. burn the images in your screen to show them even when your TV is switched off. They are also available only in larger sizes and are not that energy-efficient.

Quantum Dots

Quantum dots can be defined as nanocrystals that absorb light and convert its wavelength. These are used in QLED TVs where they are placed in front of a normal LED backlight in a layer. All these crystals emit individual colors of their own based on their size. Though the light emitted by these quantum dots still goes through the filter, the lights are highly pure that helps in expanding the TV’s color range, and creates more intense and deeper colors. These dots also enhance the light efficiency of the TV and thus produce brighter pictures.

Resolution

Resolution can be defined as the number of pixels or dots that create the pictures that you see on your TV screen. It is denoted as the number of pixels in one horizontal line by the number of pixels present in one vertical line. Higher the number of pixels, the higher the resolution, and the better the picture quality.

There are four resolutions commonly used in TVs these days and each of them has a name as which are 1280×780 (HD), 1920×1080 (Full HD), 3840×2160 (Ultra HD/4k), and 7620×4380 (Ultra HD/8k). TV resolution is usually indicated in two ways, for example, 1080i or 1080p resolution. When you have both the options in front of you, choose the latter one. The “i” means interlaced and the “p” means progressive. The difference between both is that the interlaced videos display every alternate horizontal pixel line while the progressive lines display every horizontal pixel line, making the picture quality of progressive videos better than its counter part.

Refresh Rate

Refresh rate is defined as the number of times your TV screen refreshes itself in a second. It is denoted by Hertz or Hz. A higher refresh rate usually means smoother motion on the screen, but not always. However, the refresh rate should not be confused with the frame rate (fps). Frame rate represents the number of frames displayed on the screen per second. For clear motion and images, make sure that the refresh rate and frame rate of your TV match or in other words are the same, for example, if the refresh rate is 60 Hz, the frame rate should be 60 fps.

Soap Opera Effect

Soap Opera Effect is a visual effect created by most of the TVs by default. It involves creating additional frames in between the already existing ones by motion interpolation process to make the pictures look more crisp and realistic. It shows the content on your screen at a refresh rate that is higher than the original source of the content it is handy just as blur adjustment You can turn it off on in your TV from the settings.

Viewing Angle

Viewing angle means the maximum angle at which you can watch your TV screen comfortably without any color shift or loss of brightness. The ideal position is directly in front of the TV screen and at eye level. As per LCD/ LED TV manufacturers, the best viewing angle for your TV is 88o or more. At this angle, you get clear and well-defined images with the best color accuracy.

UHD

UHD or Ultra High Definition represents a higher resolution for the TV display. UHD TVs come in 4k (3840×2160) and 8k (7620×4380). These resolutions have a higher number of pixels than a normal HD TV. UHD displays are used in larger TVs, so you can enjoy a clearer and crisp image even while sitting relatively closer to the TV.

Upscaling

Upscaling basically means stretching an image with a lower resolution to fit on a larger display. In this, the pixels of the image with low resolution are copied and are repeated to fill up the display of a higher resolution. Almost every TV comes with upscaling now. In the case of HD TVs, the upscaling process makes the lower resolution images look bigger and better on the screen by increasing the pixel count.

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Cathod ray tubes in Televisions

 

William crock and J.J Thomsan discovered electron in 1875. Instrument used in this experiment called Cathod rays tube are gas discharge tube 

it is made up of glass tube. It has two metallic electrodes connected to a source of high voltage electrode connected to negative terminal of battery is called cathode and that connected to positive terminal of battery is called anode flourocent screen is fitted to recorded flourosence or glow. A vacuum pump is connected to tube which decrease pressure inside the tube which allows gas to polarizes when high voltage applied gas inside the tube start ionizing glow produced inside the tube travel from anode towards Cathode these rays are called cathode rays and tube is called cathode tube, latter on during studying properties of these rays scientist realize that these are very small particles instead of rays and these particles named elecron.

These type of Cathod ray tube (CRT) with slightly modifications used in television computer and computer monitor screens.

Televisions working principle are based on CRT

Basic working principle in Televisions are cathode ray tube.

The cathode ray tube (CRT) in a TV is a glass vacuum tube. The inner surface of the screen is coated with tiny phosphor dots that emit light in the three primary colors (red, green, and blue). These phosphor dots glow when struck by an electron beam, resulting in the images we see on screen. The electron beam is a focused stream of electrons pouring off an electrode to which negative voltage is being supplied.

The electrons emitted from the so-called electron gun strike the phosphor dots, causing them to glow. Deflection coils that create magnetic fields are used to enable the electron beam to strike any phosphor dot on the screen.

In LCD and LED TVs instead of Cathod ray tube produce images by using liquid crystals to either transmit or block light.

Differences between LCD and LED TVs are back lighting only basic principle is based on liquid crystal system in both LCDs and LEDs, but in Televisions basic working principle is based on the Cathode ray tube.

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Historical Review, Invention of Colour Television

Earlier television were in monochrome, but with advancements in technology, they also started coming in colored versions.

Colour Television in 19th  century 

Colour television was by no means a new idea.  In the late 19th century a Russian scientist by the name of A.A.  Polumordvinov devised a system of spinning Nipkow disks and concentric cylinders with slits covered by red, green, and blue filters.  But he was far ahead of the technology of the day;  even the most basic black-and-white television was decades away.  In 1928, Baird gave demonstrations in London of a color system using a Nipkow disk with three spirals of 30 apertures, one spiral for each primary color in sequence.  The light source at the receiver was composed of two Cathode ray tubes or gas-discharge tubes, one of mercury vapor and helium for the green and blue colors and a neon tube for red.  The quality, however, was quite poor.

Colour Television in 20th century 

In the early 20th century, many inventors designed color systems and their basic concept was later called the "sequential" system, different terminologies used as more and more new functions introduced. They introduce three successive coloured filter red, blue, and green to scane the picture. Idea was that in the result out put human eye would see original multicoloured.

Unfortunately, this system required too fast a rate of scanning which were not possible in black-and-white receivers would not be able to reproduce the pictures.  Sequential systems therefore came to be described as "noncompatible."

An alternative approach which is compatible with existing black and white recovers known as “simultaneous” system, which would transmit the three primary-colour signals together.

In 1924, Harold McCreary designed a system using cathode-ray tubes as camera speratly to scane each of three primary colour components of picture at receiving end. In each tube,  elecron struck the phosphors coated screen In the result glow of appropriate three primary Colour produced, series of mirrors would then combine these images into one picture.

At that time this was a new idea but not working properly .

In 1929 Herbert Ives and colleagues at Bell Laboratories transmitted 50-line colour television images between New York City and Washington, D.C.; this was a mechanical method, using spinning disks, but one that sent the three primary colour signals simultaneously over three separate circuits.

After World War II, the Columbia Broadcasting System (CBS) began demonstrating its own sequential color system, designed by Peter Goldmark.  Combining cathode-ray tubes with spinning wheels of red, blue, and green filters, it was impressive enough that's why Federal Communications Commission (FCC) to authorize the Goldmark system for commercial television, but Sarnoff warned against using a "horse-and-buggy" system that was incompatible with monochrome TV.  At the same time, Sarnoff whipped his troops at RCA into developing the first all-electronic compatible color system in 1950.

In this every 1/60 of a second the receiver’s three electron guns painted the entire picture simultaneously with red, green, and blue, left to right, line by line.

And the RCA colour system was compatible with existing black-and-white sets.

In 1952, the National Television Systems Committee (NTSC) was reformed, this time with the purpose of creating an "Industry Color System." Which adopted most of Europe and Japan as well. And after this varity of different colours and system like PAL (phase alternation line) introduce in Germany the United Kingdom, and the rest of Europe had adopted PAL. In France Henri de France developed SECAM Soviet Union adopted SECAM, both these system are based on NTSC system with slitly modifications, These are still the standards of colour television today, despite the arrival of digital television.

With the passage of time different name were given according to modifications of system three colour system then multi coloured and digital television now a days smart television like LCD and LED with high resolution advance futures and systems.

Digital television 

Digital television technology emerged to public view in the 1990s.  In the United States professional action was spurred by a demonstration in 1987 of a new analog high-definition television (HDTV) system by NHK, Japan's public television network.  This incited the FCC to declare an open competition to create American HDTV, and in June 1990 the General Instrument Corporation (GI) surprised the industry by announcing the world's first all-digital television system.  Designed by the Korean-born engineer Woo Paik, the GI system displayed a 1,080-line color picture on a wide-screen receiver and managed to transmit the necessary information for this picture over a conventional television channel.  Heretofore, the main obstacle to producing digital TV had been the problem of bandwidth. 

Within a few months of GI's announcement, both the Zenith Electronics Corporation and the David Sarnoff Research Center (formerly RCA Laboratories) announced their own digital HDTV systems.

In 1993 these and four other TV laboratories formed a "Grand Alliance" to develop marketable HDTV.  In the meantime, an entire range of new possibilities aside from HDTV emerged.  Digital broadcasters could certainly show a high-definition picture over a regular six-megahertz channel, but they might "multicast" instead, transmitting five or six digital standard-definition programs over that same channel.

Indeed, digital transmission made “smart TV” a real possibility, where the home receiver might become a computer in its own right. 

There are varity of smart television like LCD and LED available in market with high resolution advance futures and systems.

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