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Benefits of a Flat Panel TV (back to top)

 

Conventional CRT (Cathode Ray Tube) televisions have limitations with regards to the size of the projection surface. The size of a CRT television is directly proportional to the diagonal length of its screen's surface. As the screen becomes larger, the electron beam required to illuminate the screen surface needs to be further away from the screen. This increased distance is necessary to facilitate illuminating areas away from the center, such as corners or edges. Thus, the larger the display of a CRT television, the more space it will occupy. With miniaturization influencing every electronic commodity and the growing need for space management, there arose a need for a compact alternative with equal or even better picture quality.

 

Enter the flat panel television! Flat panel display technology brought forth high quality imagery and slimmer display units compared to the bulky CRT TVs. A flat panel TV offers richer color output compared to a regular CRT television. Flat panel TVs are also thinner and completely flat as compared to the convex screens of conventional CRT televisions. They offer greater compatibility with home theatre systems, the HDTV standard and other digital standards. Flat panel televisions incorporate a number of modern technologies such as a Liquid Crystal Display (LCD), TFT-LCD and Plasma.

 

1. 4 Main Types of Flat Panel TVs (back to top)

 

Different types of flat panel televisions use different technologies to produce high quality video. The 4 main flat panel technologies available in the marketplace today are:

 

• LCD (Liquid Crystal Display)
• TFT-LCD (Thin Film Transistor Liquid Crystal Display)
• Micro Display
• Plasma

 

• LCD TVs (back to top)

  An LCD screen uses millions of tiny crystals, called pixels (picture elements), that emit light when activated by an electric current. It is also referred to as a Passive Matrix LCD screen. Each pixel emits varying intensities of light and colors depending upon the image. Most LCD TVs differ from each other with respect to the number of colors displayed, the contrast ratio and refresh rate of the screen. A high value for color and contrast ratio indicates rich picture quality. LCD TVs consume only one-third the power consumed by CRT televisions of the same dimensions. LCD TVs can be as thin as 4 inches and weigh a maximum of 10 pounds, saving up to 90% of space.

   

• TFT-LCD (back to top)

  A modified version of the LCD TV, a Thin Film Transistor LCD (TFT-LCD) television is based on the same principle as an LCD TV, except the fact that they are faster at displaying images in succession than regular LCD TV panels. An LCD TV takes almost 40 milliseconds to draw an image. A standard motion picture moves still images at the rate of 25 images per second or an image every 0.4 milliseconds. Due to the method involved in exciting the photons in an LCD screen, the time lag between two images being displayed is quite high as compared to the CRT display technology. As consecutive images are not displayed quickly enough, certain details or even intermittent images are dropped by the control circuitry to catch up with the subsequent images, the result is jittering or "ghosting" as it is often called. Ghosting results in a hazy picture with loss of details.

   

  A TFT-LCD TV uses a similar array of pixels controlled by special transistors for lighting up each of the pixels for creating images. The only difference being, each pixel has its own controlling transistor. Hence, the time taken to redraw an image in succession to the previous image is significantly reduced, as compared to a regular LCD TV. Generally, a TFT-LCD television has almost 1 million pixels, called Megapixels, for reproducing images of natural quality. A television having more than 1 Megapixel of resolution offers better sharpness and a larger viewable area. For example: a 17 inch television has approximately 1. 3 million pixels and 1. 3 million transistors. Most LCD TVs today are manufactured using the TFT technology instead of the older passive matrix technology.

   

• Micro-Display (back to top)

  A cross over between the LCD technology and the CRT method of displaying images, Micro-display technology promises better quality output at higher screen redraw speeds. A micro-display television uses a microchip of an array of small pixels that are densely packed together to create an image. A powerful lamp then bounces light off or through this array of pixels onto a larger screen often via a magnifier lens or glass. Micro-display technology's advantage over a conventional LCD screen is that the quality of the image remains high. This is due to the fact that the image is reproduced onto a smaller array of pixels, in addition to maintaining high refresh rates. On the other hand, micro-display lamps usually last for a short period of 3,000 to 10,000 hours -fortunately they are cheap and easily replaceable. Additionally, micro-display technology can display computer as well as high-definition and standard TV broadcasts. It also generates better quality graphics when fed a digital signal (DVI, HDMI, or FireWire) rather than an analog connection. Micro-display television sets are usually much thinner and lighter in weight than CRT televisions but thicker and heavier than an LCD set.

   

• Plasma (back to top)

  Based on a concept similar to the LCD display, plasma panels differ in the nature of the pixels. A plasma display unit is constructed out of an array of small cells containing xenon and neon gas sandwiched between two sheets of glass. Each cell is controlled by a pair of tiny electrodes positioned on the inner side of the front and rear glass panels. The electrodes release small pulses of electric charge in the cell. The inert gases in the cell ionize and release ultraviolet photons onto the phosphor layer containing the three basic colors for image reproduction -red, green and blue (RGB). The photons, upon impact with the array of cells, illuminate the surface with corresponding colors and create the desired image on the screen. This process results in an image with deeper and richer colors of up to 68 billion. The contrast ratio provided by a plasma screen can be as high as 10000:1.

   

 

2. Purchasing Criteria (back to top)

 

• Contrast Ratio (back to top)

The de facto standard implemented in most LCD TVs is a minimum contrast ratio of 500:1. Any figure lower than this would result in a poor reproduction of details, especially the darker shades. Simply speaking, a higher contrast ratio translates to darker blacks and brighter whites. A TV with a high contrast ratio, say 10,000:1, would even show images present in darker backgrounds that may not be visible in one with a contrast ratio of 500:1.

 

• Native Pixel Resolution (back to top)

Based on the screen size, picture resolutions can vary. HDTVs must be able to support a minimum resolution of 1280x 720 pixels. However HDTV-compatible flat panels mostly support a 1366x768 pixel resolution. Almost all sizes of LCD flat panel TVs support this resolution. The latest development in HDTV is the introduction of Blu Ray and High Definition DVD technologies by Sony and Toshiba respectively. These standards would support an HDTV resolution of 1920x1080 pixels. There are already some LCD TVs supporting these high resolutions.

 

• Number of Colors (back to top)

Present day flat panel televisions offer billions of colors, providing true-to-life picture quality. Colors supported in these televisions may range anywhere between 20 billion to 550 billion. However, the full potential of these billions of supported colors is only realized when viewing digital High Definition video; regular broadcast video does not offer such a high quality signal, often rendering these amazing capabilities useless.

 

• Screen Size (back to top)

Deciding on the size (diagonal length of the screen measured in inches) of a set depends on the size of the room it will be placed in. Generally a, 12 feet x 16 feet room is large enough for a 42 inch television set. Most TFT-LCD television sets are available in sizes ranging from 20 inches to 90 inches. Micro-Display televisions are more like CRT sets, and require more floor space than a TFT-LCD or Plasma TV set. Plasma TV sets are thin enough to be hung onto walls like picture frames, thereby saving space and adding style points to your room.

 

 

• Response Time (back to top)

A lower response time or refresh rate means smoother video transitions and sharper images with reduced haze. Lower the time taken to redraw a screen, the better the quality of displaying the visual in motion or high speed sequences. A flat panel TV's response time is tested the most while viewing high quality DVD video. Response time is also vitally important when used for graphic-intensive gaming or when the TV is hooked up to a computer for use as a PC monitor.

 

• Dot-Pitch (back to top)

While choosing for an LCD, TFT-LCD, or Plasma television, the dot pitch of the pixels should be around 0.25 mm to 0.30 mm. A 'dot pitch' is the distance between two pixels of the same color; say red pixel from a triad of the red, green and blue pixels. The closer the pixels are to each other, the sharper the picture quality. Most flat panels support a minimum resolution of at least 720 dots per inch (dpi) and a maximum of above 1080 dpi. Also, the larger the display, the higher the dot pitch should be. Choosing a high resolution TV set would allow for compliance with upcoming standards such as: HDTV, Ultra HDTV and Digital Video Broadcasts. It is important to note that due to the technology involved in Micro-Display TVs, there is no dot-pitch specification for these displays.

 

• HDTV-Compatibility (back to top)

HDTV or High Definition Television, is an audio/video standard that defines the quality of a motion picture. It is a digital broadcast in contrast to the common analog broadcast formats such as: PAL, NTSC and SECAM. It requires separate tuners built into the TV set. A HDTV broadcast has a resolution of at least 1080 active pixel lines and a 16:9 wide-screen format. The screen redraw method in an HDTV broadcast is 'progressive' instead of 'interlaced' as found in older CRT based TVs. A 'progressive' scan displays an entire picture versus alternating between drawing parts of the picture every other second. The interlaced scan method results in lower refresh rates, which in turn causes a flickering effect visible on older CRT televisions. Sound channels are implemented using the Dolby Digital 5. 1 sound standard, allowing for full surround sound capabilities. Future standards such as Ultra HDTV and Digital Video Broadcasting are poised to deliver higher quality video signals compared to conventional broadcasts. thereby delivering quality entertainment to common households.

 

• PC Connectivity (back to top)

Most flat panel televisions provide a PC input and can be used as a big screen, high resolution PC monitor. Since these televisions support higher resolutions and lower refresh rates, they are ideal for use as computer monitors. Some flat panel TVs even offer a 'TV-out' function.

 

• Sound Quality/Technology (back to top)

With so much emphasis on screen size and resolutions, sound quality often takes a back seat in flat panel TV selection. Most flat panel TVs come with built-in and often hidden speakers that provide surprisingly high quality sound. However, these TVs are best hooked up to a home theater system to do justice to their visual brilliance. The leading manufacturers of flat panel TVs offer various sound technologies such as SRS TruSurround XT and SRS WOW to provide 3D surround sound support.

 

• Price (back to top)

Variations of each of the aforementioned criteria will have a bearing on the price of your flat panel television. Other specifications remaining constant, LCD TVs should cost significantly less than Plasma displays, with Micro-Displays falling somewhere in between. Screen size is another major price influencer; the larger the screen size, the bigger the hole in your pocket! The buzzword in flat panel technology; 'HDTV compatibility' brings with it higher resolutions and contrast ratios and lower refresh rates and will therefore cost significantly more than non-HDTV TVs.

 

3. Making the Decision (back to top)

 

After deciding upon your requirements and preferences, you should compare various flat panel televisions that match those requirements offered by leading brands at a comparison shopping engine such as www.smarter.com. Smarter.com allows you to compare prices and features across models while also checking across multiple suppliers on the Internet. Additionally, you could also check in to a nearby store or outlet for a hands-on experience, check out picture quality and sound capabilities first-hand.

 

Chalk out your specific requirements and look for models that cater to those needs. Do not opt for a model that provides features you're never going to use. Make sure the size of the TV is in proportion with the dimensions of the room it is intended to occupy. If watching regular broadcast television is its main use, contrast ratio and resolution could be compromised in favor of a larger screen size; HDTV resolutions would be wasted on regular TV viewing. For hardcore gamers, good refresh rates and high resolutions would be vital. For smaller rooms, space efficient, wall mounting Plasma TVs are a better alternative to space occupying Micro-Display televisions.

 

Buying a good flat panel television set requires investment of a reasonable amount of time in researching and evaluating the various contenders. The trick is to strike the perfect balance between price and functionality; and the best way to begin is to find out exactly what your needs are. Hopefully now you have more information to help make your purchasing decision more informed, now go find a great flat panel TV!