V* Television Shrinks into IheRite Flatpicture tubes mean TVsets that trulyfit in thepalm of yourhand, byEllen MilhanKlein television, an idea tive of Matsushita Electric—Panason- the tube is much wider than it is deep.- some 20 years old now, is about ic's parent company—asked me, exag- Basically, there are two ways to to become a marketplace reality, gerating the price tag to emphasize that make a flat picture tube: design a varia- Pocket-sizeRCA talked about it in the early it takes big bucks to go from prototype tion of the standard CRT or explore a 19605, and in 1966 Motorola exhibited to production. His views were echoed new display technology. Methods have a prototype shirt-pocket TV set with a by the folks at Sharp Electronics and been developed to eliminate the elec- round, one-and-one-eighth-inch-diame- Toshiba, companies that have had sam- tron gun and phosphor screen of the ter, black-and-white screen. It was one pie flat TVs for a couple of years and, CRT in favor ofmatrix-controlled pic- and a quarter inches thick and weighed so far, have not gone beyond the hand- ture elements. A matrix is a grid of two under a pound. The same year, Popular built prototype stage. sets of electrode wiresrunning atright Mechanics described a flat-screen color What makes it hard to build a palm- anglesin parallel planes that almost but design and predicted that actual units size TV is the picture tube. The don't quite touch. Crossing points can were just around the corner. Why shallowest conventional cathode-ray be individually activated by applying didn't it happen? It turned out to be tube (CRT) is almost as deep as it is voltages across the appropriaterow and just too expensive using the technology wide. The problem is that the electron column wires. Sandwiched between the of the times. beam arising in the neck of the tube sets of wires is a layer of some sub- "How many people are willingto pay must be able to sweep the entire face of stance that reacts to voltage applied $5,000for a wristwatchTV?" an execu- the tube. This is difficult to manage if across it by generating light or under- USTRATION BY DENNIS lUZAK TECHNOLOGY ILLUSTRATED 85 Conventional Cathode-Ray Tube The relative dimensions ofa going a change in the way in which it conventional CRT are deter- reflects or transmits light. To mined by itsfunction. Several years ago Sharp Electronics an beam and form electron pro- accelerate it sufficiently topro- of Japan showed a two-inch-thick duce a picture with adequate totype with a six-inch screen. Its matrix brightness, a series ofelec- assembly used an electroluminescent trodes is required; this in turn technique involving a thin-film phos- necessitatesa long neck on phor that emits light when the The through mixture tube. angle Researchers are still which the beam is deflected voltage is applied. is limited by theamount of trying to change its yellowish glow to a current that can befed to the more neutral shade and make it re- deflection coil around the spond to lower voltages. A prototype neck ofthe CRT. Thus the Sanyo model uses a matrix of light- body must of the tube be manufacturers about as wide as it is deep. emitting diodes. Other are working with plasma (an electric discharge in a gas, similar to that of a neon sign), electrochromic materials that change color when stimulated, and phosphor electron beam electrophoretics (charged pigments screen propelled at the screen). Forming a full-fledged picture on a display matrix is not easy. Matrix tech- Sinclair Flat Cathode-Ray Tube In Sinclair's CRT, the elec- nologies, developed originallyfor use in electron gun tron gun ispositioned side- electronic instruments, calculators, dig- ways. This allows the tube ital watches, and the like, are pushed be thin to very fromfront the limits by flat-screen TV. to back, although it is almost to about twice as wide as the For one thing, controlling a matrix of, screen. The beam is steered say, 220 by 240 picture elements re- by means ofan electricfield quires abulky maze of wires. Addition- rather than a magneticfield, ally, each picture element mustrespond and the deflection plates persist until the next frame, are angled to compensatefor quickly, thefact that the beam turns then turn off quickly. Each display a corner. The viewer sees shows weaknesses when measured the same sideofthe screen against these criteria, but ofall ofthem that the electrons strike, the liquid-crystal display (LCD) seems through a Fresnel lens that closest to delivery. correctsfor image distortion. At least four manufacturers, To- shiba, Matsushita, Hitachi, and Seiko, Fresnel are working withLCDs. That's not too lens surprising when we remember that three ofthem are leaders in calculators Flat Matrix Display Matrix display consists of as well as television and that LCD cal- an electro-optic material culators have been vying for the title between two sets sandwiched "slimmest and thinnest" for years. In oftransparent electrodes, one set (row wires) running hori- an LCD, there's a thin layer of liquid zontally, the other (column crystal between the panels ofrow and wires) running vertically. column wires. Liquid crystal, unlike Energizing a row and column most other liquids, is composed ofmol- wire causes the matrix ma- ecules that tend to align themselves in terial to change optical electro-optic properties where they cross. an orderly way. It has many of the material An image isformed by ener- characteristics of solid crystal, includ- gizing a row wire toa fixed ing the ability to transmit light. When level and each column wire voltage is applied across a volume of by the t to a level determined liquid crystal, the molecules shift posi- brightness required at | each crossing point. * tion and change the way in which they 1 polarize light. Two polarizing filters, the electronic v7 one above and one below 1 "sandwich," determine whether the 86 JUNE/JULY 1982 fc. «!%^*^ Your video jitters. And we use stainless steel possible picture. That's whyour t §m_\kTa cassette pins to support the guiderollers video cassette mechanism is J l@l mechanism needs which providebetter alignment every bit as impressive as our w & to do more than store and tape-edge protectionthan video tape. and transportyour the plasticpinsused by some video tape. Because a lot can go manufacturers. wrong with yourpicture that has TDKmaintains tolerances up nothing to do withyour tape. to 2 A times tighter thanindustry "^ 4TDk Our specially engineered standards. We even build ! "*^^^^^^^^f^Ni^^^^^ cassette mechanism maintains our video cassette shell halves jKwjfiißP j |JH proper tape tension, preventing to micron tolerances for an X — « G^ jamming and snapped leaders exact top and bottom match. —— so that your tape can have We do everythingwe can to ~~~-~-^ a longer life. make sure that TDK Super ,^W1,8 1 1 We also designedour mech- Avilyn video tape andthe TDK Jm^T anism for optimal tape-to-head super precision mechanism will X2Cr H^I contact to prevent skewing and combine to giveyou the best The vision ofthe future. X. display transmits light or not. When been solved, but "we're stillworking on the polarity of the crystal matches that brightness." of the filters, light passes through; oth- SinceLCDs don't emit light (they re- erwise it is blocked. You can observe fleet or mask it), they consume as little the phenomenon for yourself by rotat- as 1.3 to 2.2 watts from the set's batter- ing an LCD watch while viewing it ■■■ ies. The price of such efficiency is that through polarizing sunglasses. (It's also H—BE their pictures cannot be seen in dark- a quick way to tell if your sunglasses B—mi ness. Hitachi circumvents this problem are polarizing.) by backing up its LCD screen with a in the case of a calculator or watch fluorescent panel. display, the background is normally a Due late this year from Sinclair Re- pale gray or yellow, and black alphanu- search ofCambridge, England, is aflat- meric figures float slightly above the screen mini-TV using a special, flat background. The figures themselves are I I CRT. About the size of a pocket either black or not—there are no half- TV picture. Present response times, re- dictionary, the mini-set is the brain- tones. An LCD television works in re- duced to about 30 microseconds (mil- child of Clive Sinclair, who brought us verse—its screen is black, and selected lionths of a second), solve that to some the first pocket calculator and, morere- picture elements are lightened electron- extent. Citing poor contrasts, another cently, the ZXB I personal computer, 3 ically. Naturally, the more elements difficulty with some video LCDs, Brit- The tube is tiny (4 by 2by /4 inches) there are, the sharper and more defined ish critic Barry Fox decries an "anemic and gives a picture three times brighter the picture. While 200-plus lines offer soot and whitewash picture." Fox also than a conventional three-inch CRT, only about half the resolution of a dislikes the relatively narrow viewing yet it is saidto require but one-fourth to CRT, they are adequate for a mini- angle that characterizes some LCDs, one-tenth the operating power. Project- screen. Shades of gray are made by Using a less viscous crystal material edretail price for the set is about $100! varying the voltage. Less voltage causes and a highly reflective back surface, Sinclair predicts that his mini-TV will only a partial shift in opacity. Toshiba claims a contrastratio of 20to dofor television what the transistor did Relatively slow response of individ- 1.