Enumclaw Courier-Herald


The science behind the screen| | Wally's World

October 22, 2013 · 9:26 AM

Back in the day when I was full of spark and vinegar, television sets, both portable and console, were huge, clumsy things. To move a large console with a 26-inch screen required nothing less than a team of horses or half the neighbors in your block.

I had a high-school physics class that explained the theory and practical functions of such antiques. Each TV set contained a cathode-ray tube. Remember? This cone-shaped contraption shot a bean of electrons from the rear, narrow end of the structure to the face of the tube – that is, the screen – where the electrons arranged themselves in horizontal lines and “miraculously” formed a picture.

Today, of course, instead of being two or three feet deep, TV sets are only a couple of inches thick and can easily be carried about and hung on a wall. If you haven’t done so lately, step into a retailer and look over the wide selection of truly awesome screens. It might blow you away.

Obviously, the cathode tube is terribly obsolete so, before I became similarly passé and ready for the trash pile, I decided to check out the technology and theory behind a modern TV. At their best, cathode tubes had roughly 30 pixels (specks) per diagonal screen inch. Current plasma and LCD sets have 100 or more pixels per diagonal inch, making a picture so sharp and clear you can see the sweat on the faces of spectators 20 rows behind home plate. (Math has never been my strong suit but, near as I can calculate, these figures are pretty accurate.)

Plasma screens are filled with various inert gases that become very luminesce and brilliant when stimulated by subatomic stuff.

LCD screens are something else, again. The acronym stands for “liquid crystal display.” What is that, you might reasonably ask. A “liquid crystal” sounds like an oxymoron and, to say the least, it’s a most unusual and weird state of physical matter, to be sure. Liquid crystals don’t obey the “laws” found in most high school physics textbooks. They are crystals that have somehow been turned into a thick, slippery syrup, just as their name implies. They refract and reflect light with all the brightness and sharpness of normal crystals – indeed, they have all the defining characteristics of normal crystals – but they can be poured. Of course, this strange stuff is used in more than LCD televisions. They’re also used in tiny screens like iPhones and iPads and in very large screens, as evidenced by the massive displays in sporting arenas.

Today, TV screens 70 or 80 inches across are still a bit too expensive for the average person, but they’ll become cheaper and rather commonplace in the next few years. Such wall-mounted screens, combined with surround sound, will revolutionize our entertainment world, especially when our computers are also fed into them. I don’t think it bodes well for motion picture theaters, unless they have gigantic screens like Seattle’s Cinerama.

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