Buyers Guides > Portable TVs & some technical background
Take a look at 3wisemonkeys range of portable TVs
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LCD or "Liquid Crystal Display", of course, refers to a display panel technology that relies on the behaviour of so-called "liquid crystal" molecules – which exist in a state between a conventional liquid and a crystal. This technology uses an applied electric field to control each picture element or "pixel" of the display. Perhaps the first thing to say about portable LCD TVs is that, nowadays, portability is a question of degree. LCD TVs, by their nature, are eminently more portable than their CRT or "Cathode Ray Tube" predecessors, even at fairly large screen sizes. In that sense, the term "portable LCD TVs" could strictly include any LCD TV with a screen size up to 52". However, for the purposes of this discussion we will use the term to refer to LCD TVs that are truly portable insofar that they can easily be carried and operated away from the home using a 12-volt power supply (from a car battery, for example) or their own rechargeable battery pack.
Portable LCD TVs are still more enjoyable to watch than, say, a CRT or Plasma TV of the same size because they have significantly higher native resolution and contrast ratio and faster response times. However, it would be unfair to expect a truly portable LCD TV to compete with an "HD Ready" or "Full HD" model designed solely for use in the home.
LCD TVs designed for static use in the home can have contrast ratios of up to 50,000:1, for example, whereas a contrast ratio of 1,000:1 is extremely high for a portable LCD TV and contrast ratios are often much lower. Contrast ratio is a measure of the luminosity of the darkest and brightest shades that can be displayed simultaneously on a screen and poor contrast ratios can result in wishy washy, desaturated colours. Nevertheless there is a limit to the contrast ratio that can actually be detected by the human eye and most portable LCD TVs are perfectly adequate in this respect. The award-winning August DA900C model, for example, features a 9" TFT or "Thin Film Transistor" LCD screen with a contrast ratio of 150:1 while further up the scale, in terms of screen size, the Nu WTW154 is a 15.4" model with a contrast ratio of 400:1.
Similarly, whereas larger static LCD TVs can have native resolutions up to 1,920 x 1,080 pixels, you won't find that level of resolution in truly portable LCD TVs. This is only reasonable in view of the fact that portable LCD TV screens range from 7" to 15" or so, measured diagonally. The two models already mentioned, the August DA900C and the Nu WTW15, offer native resolutions of 640 x 234 pixels and 1,200 x 800 pixels respectively. Where these models win hands down against their static counterparts is in convenience and flexibility. The August DA900C, for example, measures just 9.2" x 5.7" x 0.94" and weighs in at just over 1lb, but is nevertheless capable of receiving analogue terrestrial and digital "Freeview" TV channels and operating on mains or 12-volt power.