LCD-TV:
The "classic" among flat-screen displays. Especially with smaller and cheaper monitors and televisions, almost exclusively LCD panels are used. LCD monitors are now quite inexpensive,
but are very viewing-angle dependent and only cover a portion of the color space visible to the human eye, so the colors do not appear particularly vibrant. Your PC monitor will also, with 99% probability, be a conventional LCD device. Move your head back and forth in front of the monitor and you will see the color changes.
Technology: Simply put, the liquid crystals in the monitor create color filters that only allow the desired color to shine through. For an LCD screen to produce an image,
the thin liquid crystal layer must be illuminated from the back. In a simple LCD screen, the light is produced by a special fluorescent tube and projected relatively evenly through the liquid crystals via an inclined
back panel. Therefore, conventionally illuminated monitors cannot be built arbitrarily thin. Further disadvantages of this lighting technology are, on the one hand, uneven brightness distribution, and on the other hand, a small color space, since the fluorescent tubes used do not cover the entire visible light spectrum.
A more detailed description with detailed information on the structure of an LCD/TFT screen can be found here: LCD Televisions
LED-TV: Instead of a fluorescent tube, white LEDs are used as backlighting. These are evenly distributed across the entire back panel. The advantages of this lighting technology are enormous: The television is able to reproduce more vibrant colors because the LEDs cover a larger color space than simple tubes. In addition, individual LEDs can be dimmed, allowing for a much higher contrast. Furthermore, televisions can be built thinner and require less power. Finally, the illumination of LED televisions is
significantly better than that of conventional devices. In short: Compared to conventional LCD TVs, LED TVs have only advantages and no disadvantages. The relatively small price difference for
high-quality devices is definitely worth a look at LED TVs.
RGB-LED-TV: The "pro league" of LED televisions uses colored light sources (RGB = RedGreenBlue) instead of white background LEDs. By adapting the illumination color to the color to be displayed,
contrast and color fidelity can be significantly increased again. However, the premium for RGB-LED devices is currently still enormous. Sharp's new RGB-LED generation, for example, starts at approx. €9000 (as of 9.4.2009).
Plasma-TV: The only real alternative to LED TV is currently plasma technology. Unlike LCD (and thus also LED TVs), plasma televisions do not require backlighting. Instead, there are up to two million plasma cells on the screen, which light up in the desired color when voltage is applied. The advantages of this technology are great: Excellent black levels, combined with rich, vibrant colors and enormous contrast are on the "pro side". Likewise, viewing angle independence is a good thing. However, the disadvantages of plasma televisions are no less serious: The power consumption of plasma televisions depends heavily on the image brightness. With a bright image with a high white content, a plasma TV requires significantly more power than an LCD television. Due to the high power consumption of the panel (up to 400 watts for 42″), the device heats up very strongly, which is why most plasma televisions have active fans. In current devices, however, the fans are almost inaudible. In addition, the power consumption, e.g. in Panasonic's NeoPDP devices, is significantly lower than in their predecessors. However, since LCD devices also require less and less power, one should not speak of a "advantage" of plasma here. Below is an overview of the advantages and disadvantages of the individual technologies:
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