LCD Flat Panel Buying Guide

If there's one computer peripheral that most users take for granted, it's the display. Yet it's arguably the most important peripheral, since it provides the only means of seeing what's going on inside your computer. After a few hours of reading the screen, however, we often forget about the display and simply accept it as our window into the computer's operations.

Most users also give little thought to their selection of display, especially when buying a new computer. System manufacturers bundle a monitor and the buyer goes along with that choice-though sometimes you get to pick the size.

The reality is that you have to make many choices when selecting a display for your computer. Your decision may be shaped by budget limitations, how you'll use the computer, aesthetics, space constraints, or environmental concerns-or a combination of these factors.

This Buyers' Guide is divided into sections so that you can find the information you need quickly. The Choices section describes the different categories of displays you'll be faced with when you go shopping. The Budget section provides some generalized estimates of what you can expect to get with a certain price range. The Features section describes the most important features that differentiate displays of similar type and price. Some of these features affect all users,, but others will apply only too specific applications. Finally, the Reality Check section will help you steer clear of some of the most common buying misconceptions.

Even before you start to think about specific monitor features, you face some important choices. First, you must consider the size of the display that you need, and then the type of technology you wish to use.

• Screen Size. Display size is specified in terms of the diagonal measurement of the screen. In general, the larger the display, the more information you can show at one time. It is important, however, to keep resolution in mind. A large display that is limited to low-resolution images cannot show as much information as a smaller display that supports a higher-resolution image.

  For most office tasks, a 15-inch CRT (cathode-ray tube) is adequate. The extra cost of moving to a 17-inch CRT, however, may be well worth doing for Windows users, since it provides more space for multiple programs to be visible simultaneously. Specific applications can benefit from even larger displays: In desktop publishing, for example, it's helpful to have two full-size pages displayed side by side, as you can have with a 20-inch or larger display.

  Also, keep in mind that Windows supports multiple graphics adapters, so it's possible and sometimes more practical to get more display area by using two separate displays-a solution that will often will cost less than the price of a single, larger display.
   

• Display Technology. For desktop displays, your choices can be divided into two large groups: cathode ray tubes (CRTs) and liquid crystal displays (LCDs).
  • CRT Displays. A CRT relies on vacuum tube technology, which is based on principles developed more than 100 years ago. It's similar to the picture tubes used in a typical television set. Many important developments have evolved since then, resulting in displays that are brighter, have more accurate color, and support higher-resolution images. Design advances have also made it possible to reduce the overall size and weight of a CRT display.
     

    CRTs are called "emissive" displays, because the light is created at the screen's surface by glowing phosphors. Three electron guns located in the back of the picture tube send streams of electrons toward the tube's front face. That surface is lined with red, green, and blue phosphors, which glow when excited by electrons. By controlling the strength of the electron beams, the phosphors glow with varying intensities, creating many colors. The electron beams are controlled electronically so that the speed and location can be adjusted, making it possible for a CRT to display images at different resolutions.

    One important point to keep in mind is that the viewable image is never as large as the face of the CRT screen. This is because the size reported is actually the size of the tube measured diagonally--not the screen. So when you see an advertised CRT size, subtract one or two inches to get an approximate viewable area size.

    CRTs can be divided into two main categories:

    1. Shadow mask. The phosphors are arranged as circular dots with red, green, and blue triads covering the screen.
        
    2. Stripe mask (aperture grille). The phosphors are arranged in vertical stripes. This is the design made famous by Sony Trinitron tubes, but other companies have their own variations.

  
   

  • LCDs. LCDs are transmissible displays, because they rely on a bright backlight, and the individual liquid crystal cells either block or transmit the light in order to create the viewable image. Generally, three liquid crystal cells are arranged next to each other to create a single pixel. The individual cells get their color from the light passing through red, green, or blue filters; almost all LCDs' filters are arranged in vertical stripes. LCDs fill the entire display area with an image, so the panel size is the same as the viewable-area size. This means that a 17-inch LCD will have about the same viewable area as most 19-inch CRTs, and a 15-inch LCD is equivalent to a 17-inch CRT.

    LCDs are the standard for notebooks, because they are flat, lightweight, and require little power. These advantages in size and power make LCDs attractive for desktops as well. LCDs can be divided into two main categories:
     

    1. Passive matrix. The liquid crystal cells are switched on and off at the edge of the panel by rows and columns. Often the panel is divided horizontally into two regions, creating what's known as a dual-scan display. Passive-matrix LCDs are less expensive than active-matrix LCDs, because they're much simpler to build and are rarely found in desktop LCDs. Instead, they are most often found in low-end, lesser-priced notebooks.
        
    2. Active matrix. Also known as thin-film transistor (TFT) LCDs, because they have tiny transistors at every liquid crystal cell, Active-matrix transistors are used to turn the cell on or off. Because of the technology used, these panels are more expensive to make than passive-matrix LCDs. The upside is that the images are sharper, and the cells respond faster, making the displays suitable for moving images.

       
       
        

  • New-Technology Displays. There are also a couple of other technologies just over the horizon that eventually could have an impact on the market:
     
    1. OLED. One of the most promising upcoming technologies is organic light-emitting diode (OLED) display technology. OLED combines some of the best features of the CRT and LCD worlds. Like an LCD, it is a flat-panel technology that's lightweight and consumes little power; it's similar to a CRT in that it's an emissive display, generating its own light at the surface, so the image quality is more like a CRT than an LCD.
        
    2. Desktop rear projection. Another up-and-coming design is the desktop rear-projection display. Using the same tiny microdisplays found in portable data projectors, these displays are smaller versions of the familiar large, rear-projection television systems. They have a footprint similar to an LCD monitor and weigh only a bit more, but they support high-resolution screens of 20 inches or more diagonally--all at a more affordable price than CRTs or LCDs.

Budget

It's a good time to buy a new monitor. Fierce competition and production advances have driven prices steadily downward over the past dozen years. LCDs remain more expensive than CRTs with a similar display size, but even those prices have dropped dramatically in recent years. The LCD industry has been struggling with a feast-or-famine cycle of oversupply, followed by shortages that drive prices down and then up again. Worldwide LCD production capacity has grown in the past few years, which helps minimize these price swings, but the countervailing forces of increased demand as well as increased competition still leave the market subject to up-and-down price changes. The absolute dollar difference between LCDs and CRTs is getting smaller, however, which is helping increase the interest in LCDs as a viable desktop alternative. Recognizing that prices can change quickly in these markets, here's what your dollars will buy you in the following ranges:

• $0. Nothing is really free, but you can expect to get a 15-inch CRT bundled with many new computers-even the $799-budget configurations. Look for a display in this range if: you need to keep your system purchase price to a minimum.
  
   
• $80 to $150. Most 15-inch CRTs fall in this range, and you can find a few of the budget-priced 17-inch CRTs. Look for a display in this range if: your needs are modest and your budget is, too.
  
   
• $100 to $200. You'll find top brand 17-inch and bargain 19-inch CRTs in this range. Look for a display in this range if you need a large CRT display that's suitable for most applications. At this price, you'll find some very good choices.
  
   
• $200 to $300. At this price, 15-inch LCDs start to appear, along with brand name 19-inch CRTs. Look for a display in this range if you want an entry-level LCD or need a top-quality, large CRT.
  
   
• $300to $500. Some 17-inch LCDs are now available in this range, along with most 20- and 21-inch CRTs. Look for a display in this range if you're willing to spend more on your display than you spend on your computer.
  
   
• $500 to $1200. 18-inch and larger LCDs filling out the rest. Some high-performance 21-inch CRTs are also in this range, as well as a few larger CRTs, such as 24-inch models. Look for a display in this range if you need a large LCD or very large CRT for professional-applications, dual-page desktop publishing.
   

Features

There are literally dozens of features that differentiate displays. It's important to pay careful attention to those that will have the greatest impact on the kind of activity you most regularly perform with your computer. We've divided the most important features into three categories, depending on whether they apply to all monitors, CRTs only, or LCDs only:

All:

• Front-panel controls. All displays require some adjustment, even if only for brightness and contrast settings. Most monitors now have an on-screen menu to guide you through the process; this menu will help you make sense of the controls and screen prompts.
  
   
• DDC support. The Display Data Channel (DDC) is a standard set by the Video Electronics Standards Association (VESA) that allows computers to communicate with monitors. Among other information, this feature allows the monitor to tell the computer which resolutions, signal rates, and power-saving modes it supports. The Windows Plug and Play feature can then use this information to configure the computer to work with the display, without the need for separate driver information.
  
   
• Quick-exchange warranty. If your monitor fails, you won't be using your computer until you can get a replacement. Some display warranties include overnight replacement. If your installation is mission-critical, check for this coverage.
  
   
• Digital versus analog input. Though digital and analog connections are supported by both types of displays, the debate about which is better applies more to LCDs than to CRTs. The standard VGA-compatible connection takes the digital display information, which is stored in the graphics adapter's frame buffer. This data is then sent to the display. If that display is an analog monitor, the data is sent to a digital-to-analog converter (DAC) and then out the VGA connector as analog signals. If the receiving monitor is an LCD, the analog data must be converted back to digital. Because LCDs are digital, the quality of the signal may diminish as it's converted from digital to analog and back again. Also, some LCDs have difficulty synchronizing correctly to an analog signal, resulting in pixel jitter. A digital signal addresses each pixel directly, so there is no jitter. Most displays that accept digital signals use the DVI (Digital Video Interface) connector, but digital inputs are becoming less important, because many LCD monitors do a much better job of processing analog signals than they did in the past.
  
   
• Multiple inputs. If you need to work with more than one computer but have space for only one display, consider getting a model with multiple inputs. The best units will have a single button or switch on the front panel, making it easy to switch between the two displays.
   

CRTs:

• Refresh rate. Refresh is one of the most important display settings. If the refresh rate is too low-for example, lower than 72 Hz for most users-the image on the screen may appear to flicker. But don't set your monitor's refresh rate any faster than what's required to eliminate flicker; higher refresh rates can cause the image quality to degrade.
  
   
• Dot pitch (or stripe pitch). This measurement refers to the spacing between the phosphors on the CRT screen. For shadow mask monitors, it is the space between the triads of red, green, and blue dots. For stripe mask (or aperture grille) tubes, it is the horizontal space from a stripe of one color to the next stripe of the same color. Some shadow mask monitors report a horizontal dot pitch, which is smaller than the dot pitch and somewhat comparable to a stripe pitch measurement-if you're comparing monitors with different tube types. It's possible that a monitor will be specified to support a resolution that's higher than its phosphors can display. If a pixel is smaller than the horizontal pitch measurement, the monitor won't be able to produce a single pixel vertical line accurately at that resolution. A good rule of thumb is not to get higher than a 0.28 dot pitch on a 17-inch monitor.
  
   
• Flat-faced CRT. The popularity of LCDs has prompted CRT manufacturers to design tubes with a flat face. This helps reduce reflected glare, making the image more attractive. Flat-faced models typically cost more than traditional designs with curved screens.
  
   
• Screen geometry controls. No CRT is perfect, despite the manufacturers' best efforts. The best monitors have controls that let you adjust the image geometry so that the corners are square and shapes are proportionate. The convergence setting-one of the most important features for designers and CAD operators-helps align the three electron gun beams so that they overlap one another correctly when drawing a white line.
  
   
• Short neck design. As a rule of thumb, a CRT's case is as deep as the diagonal measurement of the picture tube. Newer designs can control the electron beams across a wide angle, so the picture tube neck can be shorter. This in turn makes the case smaller and the monitor a bit lighter, which can be an advantage in many environments.
  
   
• BNC (Bayonet Nut Connector) inputs. The standard VGA connector and cables can result in some signal degradation between the computer and the display. Larger, high-end displays, such as those designed for graphic-arts and computer-drafting applications, often offer coaxial BNC connectors instead of (or in addition to) the VGA connector. This can result in a better, more accurate signal.
   

LCDs:

• Native resolution. The actual number of pixels displayed is the panel's most important specification. Most LCD monitors allow you to scale images of other resolutions, but you'll get the sharpest result if you stick to the native resolution.
  
   
• Auto-adjust. If the LCD monitor uses an analog signal, it must synchronized to be sized and positioned correctly. The best models have a single button on the front panel that lets you initiate an automatic synchronization process.
  
   
• Viewing angle. With some LCD panels, viewing the image from an alternative angle can be difficult to impossible. If you need to see the image when you're not directly in front of the display, look for a design with a wider viewing angle. There are different technologies used to achieve this, but you should be able to view the image at up to 80 degrees off the axis in any direction.
  
   
• Pivoting display. Some LCDs pivot, so the screen orientation can change from landscape mode-where the image is wider than it is tall-to portrait mode. Software rotates the image and reformats it for the new orientation. This feature lets you view an entire letter-size page in full size on a 15-inch LCD.
  
   
• Mounting-arm compatible. One of the most attractive features of an LCD is that it takes up less space than a CRT. Many are designed to attach to arms that conform to a VESA mounting standard, so they can be mounted on a wall, saving even more space.
  
   
• Antitheft lock. LCDs are fairly expensive and relatively small, making them attractive targets for theft. Some models include security features, such as support for a Kensington lock, which can deter pilfering.