How does a Flat Screen TV work?
There are two types of flat-screen televisions. These are LCD (Liquid Crystal Display) TVs and PDPs (Plasma Display Panels). LCD TVs and plasma TVs both work differently from the traditional Cathode Ray Tube (CRT) TVs. Unlike CRT TVs, flat-screen TVs do not use an electron beam running back and forth behind the screen to produce a picture.
An LCD TV and a plasma TV use the same technology of switching millions of tiny picture elements called pixels on and off to produce a moving picture. Each of these pixels is colored red, green, or blue, depending on the light that falls on them. The main difference between an LCD TV and a plasma TV is how their pixels are switched on and off.
In an LCD TV, a colored picture is produced because the pixels use liquid crystals that rotate polarized light. In a plasma TV, the pixels are microscopic fluorescent lights electronically turned on and off.
How Does an LCD TV Work
At the back of the LCD TV is a large bright light that is turned on when the TV is switched on. In front of the light are millions of pixels that are further separated into sub-pixels. Each sub-pixel is colored red, green, or blue. Each pixel is composed of a tiny liquid crystal placed between two glass polarizing filters. When the light at the back of the LCD TV is turned on, the liquid crystals in each pixel are also switched on. These crystals rotate to permit some of the rays of light to pass through the polarizing filters.
Depending on which sub-pixels the light touches, the pixel lights up and produces a certain color. Without the rotating liquid crystals, no picture will be produced because the polarizing filters block out all the light passing through the pixels.
A pixel has its own separate transistor. This transistor switches the pixel on and off as many times as needed every second.
How Does a Plasma TV Work
A plasma TV is made up of two sheets of glass. Between these two sheets of glass are millions of pixels filled with two kinds of gas, namely neon and xenon. Each pixel is coated with a chemical called phosphor. This chemical is what makes the pixels red, green, or blue.
When the plasma TV is electronically turned on, the electricity causes the colored phosphors to produce light. This in turn paints the moving pictures on the screen.
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What about the LED TVs? How do they work, and why are they so expensive?
Are they really worth considering?
LEDs are used for the backlight only, the display panel is still LCD. By replacing the always-on fluorescent backlight with multiple LEDs, the set can turn on only the areas that need lighting.
This makes black areas truly black, instead of dark gray. If you have a spaceship against black space, only the LEDs behind the ship would be illuminated, the rest would be off.
LED backlighting also reduces power consumption somewhat.
Samsung UN46B7000 Luxia LED TV Review
Samsung UN46B7000 Luxia LED TV Review
Itís razor thin. Itís bright and sharp. Itís ready to go online. Itís an energy-sipper.
Itís a work of art.
At least thatís what Samsung would have you believe about its new LED-fired LCD televisions. Falling into the Series 7 level, the UN46B7000 LED TV is a 46-inch high-definition television priced at $2,999.99.
Itís a steep price to pay, considering a standard 46-inch Samsung LCD can be found for less than half of that. Both have 1080p resolution, but the less-expensive model canít come close to what the UN46B7000 offers.
Samsung UN46B7000 Luxia LED TV
It all starts with the LEDs. Rather than a standard cold-cathode florescent lamp (CCFL), which fires other LCD televisions, the UN46B7000 uses LED (light-emitting diode) lamps. The LEDs are smaller, brighter and far more energy-efficient. Samsung claims 40 percent savings on power over its standard LCD panels.
Additionally, Samsung LED TVs are free of lead and mercury, making the production process more environmentally friendly.
The UN46B7000ís green features are certainly laudable, but most consumers looking to spend $3,000 on a television are more interested in features and performance.
Like all of the televisions in Samsungís high-end series, the UN46B7000 is loaded. Itís internet-ready and boasts loads of connectivity options, ranging from HDMI (four connectors) to PC input to USB 2.0.
The internet abilities include onscreen widgets from Yahoo and Flickr, the photo-sharing website. With the wireless adapter, the UN46B7000 can serve as a monitor for an in-home PC network. The high-definition content loaded on your computer can easily be viewed on the best screen in the house.
The flat-panel itself refreshes at 120Hz, meaning the onscreen image will always be sharp and blur-free. Additionally, the UN46B7000 boasts a dynamic contrast ratio of 3,000,000:1. What that means, very basically, is that the whites are very bright and the blacks are very black.
Apart from the picture, one of the most noticeable features of the Series 7 LED televisions is size. The UN46B7000 is only an amazing 1.2 inches deep. Mounted to a wall, it will only stick out three or four inches from the surface.
The LED technology that makes the slimline form factor possible also enables a dramatic reduction in weight. The UN46B7000 weighs less than 50 pounds, making it much lighter than a standard LCD television.
Though the price tag is high, the Samsung UN46B7000 offers all of the features most in demand today: energy efficiency and environmental responsibility, along with cutting edge technology and the finest in LCD image rendering.
How DLP Sets Work
How DLP Sets Work
If you walk into a store to look at TVs or search for one online, you will see that there are hundreds of options to choose from. You can get a traditional cathode ray tube (CRT) TV set, a rear projector, or a big-screen TV, in dozens of sizes, shapes and colors. Ranging in size from 37 inches to more than 80 inches, big-screen TVs come in several different styles:
DLP sets are usually lower in price than plasmas and LCDs, and they tend to have a better picture. As DLP technology improves, the benefits continue to increase. If you are looking for the most bang for your buck, then DLP sets are definitely an option.
In this article, we’ll see what’s in a DLP set that makes it work, how it’s different from other TVs, what it’s currently being used for and where it’s headed in the future.
DLP technology is based on an optical semiconductor, called a Digital Micromirror Device (DMD), which uses mirrors made of aluminum to reflect light to make the picture. The DMD is often referred to as the DLP chip. The chip can be held in the palm of your hand, yet it can contain more than 2 million mirrors each, measuring less than one-fifth the width of a human hair. The mirrors are laid out in a matrix, much like a photo mosaic, with each mirror representing one pixel.
When you look closely at a photo mosaic, each piece of it holds a tiny, square photograph. As you step away from the mosaic, the images blend together to create one large image. The same concept applies to DMDs. If you look closely at a DMD, you would see tiny square mirrors that reflect light, instead of the tiny photographs. From far away (or when the light is projected on the screen), you would see a picture.
A DMD chip is a micro electro-mechanical system (MEMS). MEMS devices combine microscopic machines with the same silicon used in a computer. See How Semiconductors Work for more information.
The number of mirrors corresponds to the resolution of the screen. DLP 1080p technology delivers more than 2 million pixels for true 1920x1080p resolution, the highest available.
In addition to the mirrors, the DMD unit includes:
[LIST][*]A CMOS DDR SRAM chip, which is a memory cell that will electrostatically cause the mirror to tilt to the on or off position, depending on its logic value (0 or 1) [*]A heat sink [*]An optical window, which allows light to pass through while protecting the mirrors from dust and debris [LIST]
Before any of the mirrors switch to their on or off positions, the chip will rapidly decode a bit-streamed image code that enters through the semiconductor. It then converts the data from interlaced to progressive, allowing the picture to fade in. Next, the chip sizes the picture to fit the screen and makes any necessary adjustments to the picture, including brightness, sharpness and color quality. Finally, it relays all the information to the mirrors, completing the whole process in just 16 microseconds.
The mirrors are mounted on tiny hinges that enable them to tilt either toward the light source (ON) or away from it (OFF) up to +/- 12į, and as often as 5,000 times per second. When a mirror is switched on more than off, it creates a light gray pixel. Conversely, if a mirror is off more than on, the pixel will be a dark gray.
The light they reflect is directed through a lens and onto the screen, creating an image. The mirrors can reflect pixels in up to 1,024 shades of gray to convert the video or graphic signal entering the DLP into a highly detailed grayscale image. DLPs also produce the deepest black levels of any projection technology using mirrors always in the off position.
To add color to that image, the white light from the lamp passes through a transparent, spinning color wheel, and onto the DLP chip. The color wheel, synchronized with the chip, filters the light into red, green and blue. The on and off states of each mirror are coordinated with these three basic building blocks of color. A single chip DLP projection system can create 16.7 million colors.
Breakdown of a typical DLP light engine
Each pixel of light on the screen is red, green or blue at any given moment. The DLP technology relies on the viewer’s eyes to blend the pixels into the desired colors of the image. For example, a mirror responsible for creating a purple pixel will only reflect the red and blue light to the surface. The pixel itself is a rapidly, alternating flash of the blue and red light. Our eyes will blend these flashes in order to see the intended hue of the projected image.
A DLP Cinema projection system has three chips, each with its own color wheel that is capable of producing no fewer than 35 trillion colors. In a 3-chip system, the white light generated from the lamp passes through a prism that divides it into red, green and blue. Each chip is dedicated to one of these three colors. The colored light that the mirrors reflect is then combined and passes through the projection lens to form an image.
DLP Resolution and Reliability
In the fast-paced world of improving technology, some manufacturers of the newer DLP TVs have replaced the color wheel, as well as the projection lamp, with light emitting diode (LED) technology to give a higher quality to the image on the screen. LED technology uses illuminated lights in red, green and blue to provide the color, as opposed to a color wheel. DLP is the only technology to use LED.
Some of the benefits include:
There are also many other differences between DLP and other types of TVs, that make DLP a higher-quality product. In a traditional CRT TV, there are three "guns," or tubes, that can become misaligned. This causes the image to go out of alignment and appear fuzzy. You would need to have a trained technician come in and realign the tubes to restore a clear picture.
DLP is also insusceptible to phosphor burn-in, which can occur in plasma and CRT TVs. Phosphor burn-in is a permanent disfigurement of areas on the screen caused by still images being displayed continuously for long periods. For example, if you leave the TV on a channel that has a logo constantly showing, you may still be able to see the shadow of that logo when you change the channel.
Another advantage of DLP is the reduction of the "screen door" effect, also known as pixilation. Pixilation occurs when fine lines separate the projector's pixels and they are visible in the projected image. Because the space between each DMD mirror is microscopic, it is virtually impossible for pixilation to be visible.
The structure of a DLP also makes it one of the most reliable TVs on the market. What keeps a DMD from breaking or falling apart? There are three major components that keep it together:
DLP sets are much more affordable than the other plasma and LCD sets. They also come in larger screen sizes, yet remain slim and lightweight. Newer models are as small as 7 inches. In 2007, DLP wall-mounted sets were introduced to compete with the plasma and LCD screens, which provide increased contrast performance beyond 100,000 to 1.
Current and Future Uses of DLP
You've probably seen DLP technology and not realized it, because it's being adopted for use all over the world. Some current uses include:
A DLP projector
DLP Cinema is also growing at a lightning-fast pace. It’s currently being rolled out to movie theaters all over the world with 1,943 screens in North America, 572 in Europe, 398 in Asia and 26 in Latin America, plus an additional 285 installed in screening rooms and post-production houses [Source: DLP.com]. In mid-2006, approximately 32,000 cinema systems conversions were announced for North America, including the purchase of 13,000 systems by National CineMedia, the joint venture owned by Regal Entertainment Group, AMC Entertainment Inc., and Cinemark USA.
Future Uses of DLP
There are numerous projects in the works for DLP technology. One project, 3D digital projection, is currently in the testing phase at some theaters around the country. Conventional 3D projection requires the use of two synchronized projectors, which increases costs and requires projectionists to have a lot of technical knowledge. DLP Cinema 3D projection would eliminate that because it only needs one projector. There are 182 DLP Cinema-equipped movie screens in North America presenting feature films in 3D. Carmike Cinemas has recently announced plans to convert 500 of their DLP Cinema screens for 3D projections.
However, there are other uses being developed for DLP beyond projection and TVs. Some other applications that could incorporate its high-definition image creation are:
As time goes on, and the technology advances, scientists and developers are likely to discover even more uses for DMDs and DLP technology.
Last edited by Zero Gravity; 09-11-2009 at 02:17 PM.
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