Video Hardware, Part 1 - LCD Panels
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Borrowing technology from laptop manufacturers, most major monitor makers sell monitors with liquid crystal displays (LCDs). LCDs have low-glare, completely flat screens and low power requirements (5 watts versus nearly 100 watts for an ordinary monitor). The color quality of an active-matrix LCD panel actually exceeds that of most CRT displays.
At this point, however, LCD screens usually are more limited in resolution than typical CRTs. Table 15.1 compares the typical resolutions of LCD monitors from 15'' to 22'' to mainstream CRT monitors ranging from 17'' to 22'' with comparable viewable areas.
Table 15.1 LCD and CRT Resolutions Compared LCD Size | LCD Resolution | CRT Size | CRT Viewable Area | CRT Maximum Resolution |
15'' | 1024x768 | 17'' | 16'' | 1024x768
1280x1024
1600x1200 * |
17'' | 1280x1024 | — | — | — |
18.1'' | 1280x1024 | 19'' | 18'' | 1600x1200 |
19'' | 1280x1024 | — | — | 1920x1440 * |
20.1'' | 1600x1200 | 21'' | 20'' | 1600x1200
1920x1440 * |
*Available on high-end monitors only
As you can see from Table 15.1, you need a 20.1'' or larger LCD panel to achieve resolutions above 1280x1024, although most 18'' CRT displays can achieve 1600x1200.
Despite recent price drops, LCD panels continue to be more expensive than comparably sized CRTs. A typical 15'' LCD panel sells for around $250–$400, compared to flat-screen 17'' CRTs, which sell for around $150–$250. However, as Table 15.1 shows, it is important to consider that an LCD screen provides a larger viewable image than a CRT monitor of the same size. See Figure 15.3 for an example of a typical desktop LCD panel.
Figure 15.3 Note the small footprint of this 15'' LCD, which makes these panels ideal for use in cramped quarters.
Two basic LCD choices are available today on notebook computers: active-matrix analog color and active-matrix digital—the latest development. Monochrome LCDs are obsolete for PCs, although they remain popular for Palm and similar organizer devices and are sometimes used for industrial display panels. Passive-matrix displays using dual-scan technology were popular for low-cost notebook models until a few years ago, but they have been completely replaced by analog or digital active-matrix displays. Passive-matrix displays are still used with handheld organizers or for industrial-use desktop display panels because of their relatively low cost and enhanced durability compared to active-matrix models.
Note -The most common type of passive-matrix display uses a supertwist numatic design, so these panels are often referred to as STNs. Active-matrix panels usually use a thin-film transistor design and are thus referred to as TFTs.
Desktop LCD panels are analog or digital active-matrix units. Typically, lower-cost 15'' LCD panels use the traditional analog VGA connector and must convert analog signals back into digital, whereas more expensive 15'' and most larger LCD panels provide both the analog VGA and the DVI digital connector found on most high-end and mid-range video cards. Note that some LCD vendors of VGA/DVI-compatible panels might provide only the cheaper analog VGA cable, leaving it to you to buy your own DVI cable. If you plan to connect your new LCD to your video card's DVI port, be sure that the panel supports DVI and that the cable is included. And, while you're shopping for an LCD panel, be sure to note which models include the DVI cable; the presence of a DVI cable in the box of a nominally more expensive display can more than make up the difference in price between it and an apparently less expensive panel that doesn't include the cable.
The latest trend in LCD displays is the so-called TV monitor. These LCD displays integrate TV tuners and AV video inputs to enable a single device to be used for business, gaming, and video entertainment. Many of these displays, particularly those with a 17'' or larger LCD panel, also incorporate a wide-screen (16x9 aspect ratio) design for better display of wide-screen video and TV content.
 | This chapter is from Upgrading and Repairing PCs, 16th edition,by Scott Mueller. (Que Books, 2004, ISBN: 0789731738). Check it out at your favorite bookstore today. Buy this book now! |
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