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  HDTV

HIGH DEFINITION TELEVISION (HDTV) 
DISPLAY TYPES

What types are available?
  • Direct-view CRT:  
    CRT (cathode-ray tube) direct view televisions are the integrated (TV tuner/display/speakers) sets we have known for the past 50 years. CRT TV sets are available today which have HDTV capability but the old tube TV technology is rapidly being replaced by thinner and larger display technologies.

    Screen Size: Up to 40".

    Technology: single large CRT ("picture tube") a vacuum tube in which images are created when an electron beam scans back and forth across the back side of a phosphor-coated screen.

  • Rear-projection:  
    A rear-projection television usually ranges from 40 inches to 82 inches in screen size. Inside a rear-projection TV is a lamp, lens and a mirror that reflects an image that is projected from the projector to the display screen. This is done so that the actual television depth does not need to be as deep as a 2 piece rear projection set. The picture looks dimmer if you're viewing from the side. The lamp needs to be replaced periodically (much more often than a LCD light source). RPTVs (rear-projection TVs) take up more floor space than direct-view TVs and are not nearly as thin as LCD or Plasma displays.

    TV - DLP side view
    Screen Size: 40" to 82".
    Technology: Today's DLP displays are representative of rear-projection.

    2 Piece Rear-Projection: This type of projector is like a front projector, except the image is projected onto the screen from behind instead from the front. This option is not as viable for most home theater setups, but some find it to be preferable.

  • Flat-panel:  
    Flat-panel displays create bright, crisp images. These slim, wall-mountable TVs use either plasma or LCD (Liquid Crystal Display) panels.

    Screen Size: Up to 45 inches for LCD; 32, 42, 50, 63 inches and larger for plasma.

    Technology: LCD and Plasma display technology is different than traditional CRT technology. More on flat-panel LCD and Plasma displays. 

    See a  plasma-vs.-LCD comparison that explains how these flat-panel displays work.

  • Front-projection:
    A front projection TV is a two piece unit that projects the image from the front of the TV onto a screen. It is like the technology that is used in movie theaters. With this type of setup you will have two parts: 
    1) the projector and 2) the display screen. A front projection TV can be made with any of the following display types: LCD, CRT, DLP, D-ILA, or LCoS.

  • OLED:
    Organic LED Displays - razor thin display and bendable, this is the next big thing in display technology. Based on certain organic materials which glow red, green or blue when electric current is passed thru them. Kodak, Philips and Sony already have prototypes. Sony will sell OLED TVs in 2008. OLED technology is emerging as a leading next-generation technology for electronic displays.

HDTV Display Types









CRT (Cathode Ray Tube)
Cathode Ray Tube. A vacuum tube that produces light when energized by the electron beam generated inside the tube. The CRT has a heater element, cathode, and grids in the neck of the tube, making up the "gun". An electron beam is produced by the gun and is accelerated toward the front display, or screen surface of the tube. The display surface contains phosphors that light up when struck by the electron beam.

CRT stands for Cathode Ray Tube. CRT's use phosphors excited by a scanning electron beam to produce a picture.
 
DLP (Digital Light Processing)
At the heart of every DLP projection system is an optical semiconductor known as the Digital Micro-mirror Device, or DMD chip, which was invented by Dr. Larry Hornbeck of Texas Instruments in 1987.

The DMD chip is probably the world's most sophisticated light switch. It contains a rectangular array of up to 1.3 million hinge-mounted microscopic mirrors. Each of these micro-mirrors measures less than one-fifth the width of a human hair, and corresponds to one pixel in a projected image.

When a DMD chip is coordinated with a digital video or graphic signal, a light source, and a projection lens, its mirrors can reflect an all-digital image onto a screen or other surface. The DMD and the sophisticated electronics that surround it are what we call Digital Light Processing technology. DLP (Digital Light Processing) is a reflective technology it uses microscopic mirrors and a color wheel to control the passage of light. DLP tabletop TVs, because they are technically rear-projection sets, are thicker than most LCD models, but are significantly thinner than standard rear-projection CRT models, with a brighter image that is more precise. 

DLP technology isn't affected by image burn-in. DLP is a technology made by Texas Instruments. It uses a Digital Micro-mirror Device (DMD) which has approximately one million tiny mirrors to reflect light that creates a digital image. This is considered to be the best digital picture you can get! DLP is said to have a fill-rate of 88%. The fill-rate is determined by how much of the image is made up of elements compared to the space in between the elements. Thus, 88% means the screen is 88% full of color, while 12% of the image is in between those elements.
LCD (Liquid Crystal Display)
LCD 
LCD, or TFT-LCD, stands for thin-film-transistor liquid crystal display. It consists of a glass plate on the bottom, a color filter plate on the top and liquid crystal in between. The special properties of the liquid crystal are manipulated to create images. They are flat and thin, easy to carry around and consume less power.

LCD has millions of individual elements that are turned on and off to create the colors Red, Green, and Blue. If an element is turned on, light is projected through that specific LCD cell and you see the corresponding color. The fill-rate of LCD is said to be 83%. LCD technology uses a fixed-pixel array, and permits some very desirable flat-panel designs. The image is created by transmitting light through a small panel, with separate sections for each of the three primary colors. These panels are filled with liquid crystal. An electrical current directs each pixel to be either transparent or block the light. The picture forms by individually addressing each pixel to create the image.

Ideal for smaller applications, LCD is typically used in laptops and portable DVD players. Because LCD sets have a fixed resolution (one common resolution is 1024 x 768), they generally use scaling or line doubling to convert signals to match the screen's resolution. 

LCD technology isn't affected by image burn-in (making it ideal for video games or PC usage) and it is relatively power efficient. It is easier to set up than CRT-based rear or front projectors. Also, compared to rear-projection TV, LCD has a much more focused and accurate image across the entire screen, including the corners. You don't need to sit dead center to enjoy a great picture.
D-ILA (Digital Direct Drive Image Light Amplifier)
D-ILA is a type of LCD display that is owned by JVC. D-ILA, unlike LCD, uses a method of reflecting light through the elements twice before being passed to the lens. The fill-rate of D-ILA is said to be 93%.The D-ILA (Digital Direct Drive Image Light Amplifier) technology that JVC has developed is based on an innovation in microchip design that permits the viewer to enjoy the full range of benefits from any high quality source whether from a video deck or a computer device. For true HDTV performance, the D-ILA technology packs 2048 x 1536 pixels, a total of 3.2 million pixels, on a single 1.3" chip. This enables display of HD images at full-spec resolution of 1920 x 1080, with room to spare.

The D-ILA's innovative CMOS design is the key to reproducing all the details in a high-definition picture. By placing the matrix addressing switches and electronics right behind (not between) the light-modulating liquid crystal layer, JVC has created a D-ILA chip with a "3-dimensional" layout. The result is a 93% fill factor and virtual elimination of the annoying "grid" or "screen door effect" so evident in other fixed matrix display technologies. JVC developed the D-ILA technology as an alternative to LCD (liquid-crystal display) and Texas Instruments' DLP (Digital Light Processing) technologies for projecting digital images onto a screen. 

D-ILA works with standard video or digital sources and provides HDTV (high-definition television) performance with resolutions up to 2,048 x 1,536.
LCOS (Liquid Crystal on Silicon)
LCOS stands for Liquid Crystal on Silicon and is very similar to the technology of D-ILA, but is instead owned by Hitachi. LCoS also uses reflective techniques, but unlike DLP, it relies on LCDs that control the transmission of light from a source in front of the chips, not behind. LCoS technology boasts a high pixel count, which gives it a smooth, accurate image. LCoS sets can be thinner and lighter than CRT TVs, but, as rear-projection sets, are too heavy to hang on a wall. Liquid Crystal on Silicon is a reflective technology that uses liquid crystals instead of individual mirrors. In LCOS, liquid crystals are applied to a reflective mirror substrate. As the liquid crystals open and close, the light is either reflected from the mirror below, or blocked. This modulates the light and creates the image.
PLASMA
GAS PLASMA Technology Is Available In The Following: DIRECT VIEW DISPLAY
PLASMA FLAT PANEL DISPLAY: Plasma is a gas of charged particles (generally electrons and various ions) which interact with both externally applied electromagnetic fields and with fields they themselves generate. This interaction differentiates the behavior of plasmas from that of the more familiar gases. A basic Plasma screen consists of two thin sheets of glass containing tiny, gas-filled cells. Electronic current stimulates the cells to produce light and color. Like LCD, plasma televisions also produce a good image in a very thin, flat cabinet. Some plasma sets are lightweight enough to be mounted on a wall! However, the basic technology is very different from LCD. While LCD transmits light through the screen, plasma screens themselves emit light. The screen has a fixed number of pixels, and each pixel consists of three gas-filled cells, one for each of the primary colors. An electrical current is applied to the cell, and it glows the appropriate color. Because this occurs equally across the entire screen, the picture looks great from all angles.

Plasma has a maximum size limit it doesn't get much bigger than 63 inches. Additionally, the delicate coating that plasma uses is prone to image burn-in if operation is unattended. Finally, the panel drive electronics can use quite a bit of electricity.

Plasma has a focused and accurate image across the entire screen, including the corners, due to the nature of a fixed-pixel system. Compared to rear-projector displays, they tend to have a wider viewing area as well. However, because plasma sets are limited in resolution to the number of pixels in their display, they must rely on scalers that convert to a higher resolution if necessary. A plasma screen contains millions of compartments that contain noble gases such as Argon, Neon or Xenon. To turn these pixels on a current is passed into the compartment and they turn red, green or blue. This is the exact same technology that is used in Neon signs, except a neon sign usually only has one or two compartments of gas, whereas plasma screens have millions.
 

 


more on display types...

HDTV primer.

TV connections

Audio/video connections

Video input type Connection Used to connect
coaxial (RF) threaded F-type antenna, cable TV, VCR
composite video single RCA (usually yellow) VHS VCR, DBS, DVD, VHS and  camcorders
S-video 4-pin DIN-type (black) Super VHS VCR, DVD, MiniDV and Hi8 camcorders
component video RCA x 3
(red, green, blue)
DVD, HDTV
HDMI 19 multi-pin DVD, HDTV

 

Home theater receivers provide video inputs and outputs to enable video switching, which makes it convenient to choose from among your various video sources. 

Cost for HDTV:

Someone who wants to break into High-Def TV can buy a HDTV monitor today for as little as $250 that will give you an excellent picture. This will be a small flat screen, typically LCD, but still HDTV ready. Not all flat screen monitors are High-Def and not all are 16x9 widescreen. 

For a true High-Definition image you will need to pay much more for a (typically) larger display with 16x9 aspect ratio. 22 inch display sizes, 42 inch and even 50 inch displays may not actually be true High-Definition. Scalars in the displays will down-convert a true High-Definition signal to match the native resolution of the display which may be less than true High-Definition, although you will still get an excellent picture, much better than standard TV.

You'll need to also buy a HDTV tuner or have High-Def satellite TV or HD Cable TV or a High-Def tuner in a Video recorder. Cost for the HD tuner is around $200 while HD cable TV and HD satellite TV have monthly costs.

Also you may need to buy connection cables. Good quality cables for standard video connections should be $25 to $75 depending on the type of connections.

You might need to purchase an antenna for over-the-air broadcasts (local stations). A good quality antenna may cost about $100 but if you live in a big city with HDTV broadcasters within 50 miles, a $10 indoor UHF antenna might be all you need. 

If you want to mount the monitor on a wall or stand, that would be additional money for the mounting hardware. 

See
HDTV Prices

HDTV Basic Setup and cable connections wiring diagram

What do I need to get HDTV? 
 
How do I know a TV is HDTV?
 
HDTV Prices  





Learn about the various tv formats:
TV formats
Learn about tv features:
TV features
How do I get HDTV:
TV HDTV