| Television is a telecommunication system for | | | | projection TVs: CRT-based, LCD-based, and DLP |
| broadcasting and receiving moving pictures and sound | | | | (reflective micromirror chip) -based. Projection television |
| over a distance. The term has come to refer to all the | | | | has been commercially available since the 1970s, but at |
| aspects of television from the television set to the | | | | that time could not match the image sharpness of the |
| programming and transmission | | | | CRT; current models are vastly improved, and offer a |
| The elements of a simple television system are: | | | | cost-effective large-screen display. A variation is a |
| An image source - this may be a camera for live | | | | video projector, using similar technology, which projects |
| pick-up of images or a flying spot scanner for | | | | onto a screen. |
| transmission of films | | | | Flat panel LCD or plasma: Modern advances have |
| A sound source | | | | brought flat panels to TV that use active matrix LCD |
| A transmitter, which modulates one or more television | | | | or plasma display technology. Flat panel LCDs and |
| signals with both picture and sound information for | | | | plasma displays are as little as 1 inch thick and can be |
| transmission. | | | | hung on a wall like a picture or put over a pedestal. |
| A receiver (television) which recovers the picture and | | | | Some models can also be used as computer monitors. |
| sound signals from the television broadcast. | | | | Buying Tips & Suggestions |
| A display device, which turns the electrical signals into | | | | If you are shopping for a new television, there are |
| visible light. | | | | many things to consider before buying. Viewing habits, |
| A sound device, which turns electrical signals into | | | | size of unit, size of screen, price, brand, style, type, and |
| sound waves to go along with the picture. | | | | quality are all important issues. Don't forget to find out |
| Display technology | | | | about the cost and time required for delivery if you are |
| Thanks to advances in display technology, there are | | | | unable to retrieve the TV yourself. |
| now several kinds of video displays used in modern | | | | When it comes to size, you need to determine not only |
| TV sets: | | | | the size of the room in which the TV will be placed, |
| CRT: The most common displays are direct-view | | | | but also the size of the stand, entertainment center, or |
| CRTs for up to 40 in (100 cm) (in 4:3) and 46 in (115 | | | | other unit that will house the television. Don't forget to |
| cm) (in 16:9) diagonally. These are still the least | | | | bring a tape measure with you to the store so you |
| expensive, and are a refined technology that can still | | | | can measure the TV you want to buy and make sure |
| provide the best overall picture quality. As they do not | | | | it will fit inside the unit. You need a little extra space |
| have a fixed native resolution, in some cases they are | | | | around the television to allow airflow, to clean the TV, |
| also capable of displaying sources with a variety of | | | | and to hook up other components. |
| different resolutions at the best possible image quality. | | | | When it comes to getting your new TV home, make |
| The frame rate or refresh rate of a typical NTSC | | | | sure the one you chose will fit inside your vehicle. Also, |
| format CRT TV is 60 Hz, and for the PAL format, it is | | | | ask for help placing the television into your vehicle |
| 50 Hz. A typical NTSC broadcast signal's visible portion | | | | instead of struggling to maneuver it yourself. Make |
| has an equivalent resolution of about 640x480 pixels. It | | | | sure you have help available to bring the set in from |
| actually could be slightly higher than that, but the | | | | your car once you arrive at home as well. Some |
| Vertical Blanking Interval, or VBI, allows other signals to | | | | shops offer free delivery if you spend a certain |
| be carried along with the broadcast. | | | | amount or buy a certain size TV or larger. In this case, |
| Cutaway rendering of a color CRT | | | | you should take advantage of delivery, not only |
| Electron guns | | | | because it is more convenient, but also because the |
| Electron beams | | | | seller bears all the responsibility for the set until it is |
| Focusing coils | | | | safely placed inside your home. |
| Deflection coils | | | | When choosing a TV, pay special attention to picture |
| Anode connection | | | | quality. The darker the screen when the set is turned |
| Mask for separating beams for red, green, and blue | | | | off, the crisper the picture will be, because the TV can |
| part of displayed image | | | | provide greater contrast than those with lighter |
| Phosphor layer with red, green, and blue zones | | | | screens, such as those that appear light gray or green. |
| Close-up of the phosphor-coated inner side of the | | | | Also important is the curvature of the picture tube. Flat |
| screen | | | | screens are preferred, because images are viewed in |
| Rear projection: Most very large screen TVs (up to | | | | clean lines rather than curved lines, and there is far less |
| over 100 inch (254 cm)) use projection technology. | | | | glare from other light sources with a flat screen TV. |
| Three types of projection systems are used in | | | | |