LCD and CRT Monitors

Monitors are the computers’ windows.

They show us everything we can see of what is going on inside the computer as we work or play. One’s budget should be the primary guide in choosing a monitor, but what type should one buy? The primary choices are between those based upon cathode ray tubes or CRTs, and those using liquid crystal displays or LCDs. Each has its strengths and weaknesses. If you want the best possible realism in the pictures displayed, buy a CRT. If you are primarily concerned with reading text, buy an LCD.

To learn more, scroll down. CRTs

CRT technology has proven to be a very reliable and high quality standard. Television screens have been using this technology for a very long time with great success. The process works by moving an electron beam across the back of the screen, lighting up phosphor points on the inside of the large glass tube, resulting in a sharp, clear image.

Although an older technology, CRTs remain unsurpassed for the realism of the pictures displayed, especially in terms of the contrast ratios, the depth and true rendering of colors, which are now available in the millions. If you work primarily with graphics and/or photographs and/or videos, or if you otherwise deal with color production, including any print media, then you will likely find a CRT to be your best bet. Likewise, CRTs remain the monitor of choice for those involved with medical imaging, and virtually anyone involved in the world of art.

Although the LCDs are improving in this regard, you still cannot get the degree of realism that a new CRT offers from even a high end LCD. Note the term NEW just used, because CRT displays do slowly degrade over time as the phosphors inside the tube gradually break down, and those parts are not cheap to replace.

Another advantage CRTs still have is their easy scalability to different resolutions. Resolution refers to the total number of pixels (short for “picture elements”) that the monitor can display horizontally x vertically. You can adjust the electron beam in the tube to lower resolutions while enlarging the picture and keeping its clarity intact. Conversely, as resolution goes up there is a natural tradeoff – that the image size must scale down to permit more information to be displayed on the same-sized screen, so there are some practical limits to the resolutions that one can view easily on various sized monitors.

For example, one should be highly suspicious of a 15” monitor that claims to show, say, 1,600 x 1,200 pixels. Perhaps it can deliver technically, but the image would be too small to make for ready comprehension, and so would in practice be unusable. Here are some recommended resolutions for various sized monitors, measured diagonally from the upper right to the lower left (or vice versa). Multiply the horizontal pixels times the vertical pixels to get the total number of picture elements used to draw the screen, e.g., 800 x 600 = 480,000 pixels.

15” – 800 x 600 to 1,024 x 768 pixels

17” – 1,280 x 1024 pixels

19” – 1,280 x 1,024 pixels

21” – 1,600 x 1,200 pixels

23” – 1,768 x 992 to 1,920 x 1,080 pixels

25” – 1,920 x 1,440 pixels

27” – 2,048 x 1,536 pixels

Please bear in mind that your monitor must match the computer’s video card. It should be capable of displaying the resolutions and colors that the adapter can produce. Conversely, if your monitor is capable of displaying resolutions much higher than the card can generate, you will get only what the card can produce, not what the monitor could show with a better video card. Any mismatch between the monitor and the video card will add up to money wasted.

Relatively flat screen CRTs are now the standard. Flat CRTs are designed to reduce the glare and distortion created by conventional CRT monitors. The flat tube increases image clarity while reducing glare from light sources within the room. Nonetheless, you will still likely need to buy a glare reduction screen cover. Consider it an essential part of your CRT monitor.

Also, CRTs offer a much larger viewing angle as opposed to LCDs, which is especially important when more than one person is viewing the screen, as when you want to use the monitor in conjunction with a home entertainment centre. Another advantage is the CRT’s extremely fast refresh rate, typically 70-85 hertz or cycles per second. This refers to how quickly a pixel can turn on and off. If this rate is low, fast motion will appear blurred, or even leave “trails.”

Try to ensure that your CRT monitor supports refresh rates above 70 Hz; anything less approaches the AC power frequency of 60 Hz. Low refresh rates result in screen flicker and cause eye strain. If you use your monitor more than a few minutes a day, simply don’t go there.

The distance between pixels is called dot pitch, and is measured in millimeters. The distance between pixels has a lot to do with the quality of the image. CRTs come with a range of dot pitches. If the one you are considering is above .28 mm, we’d suggest, again, just don’t go there. You want and need a monitor with a dot pitch of .28 or preferably less.

Another "don’t go there" concerns the interlacing/non-inter-lacing issue. If the scanning beam hits each and every line of pixels in succession, on each pass, the monitor is non-interlaced. The interlaced monitor scans the odd numbered lines on one pass, and then it scans the even lines on the second pass. This results in an almost imperceivable flicker, which will eventually result in eye-strain, blurred vision, sore eyes, headaches and perhaps even nausea. Make sure the CRT you are considering is non-interlaced. Avoid interlaced monitors like the bubonic plague.

When buying a computer monitor for your home, consider where it will be placed. Should desk space be an issue you'll want to choose an LCD display with a small footprint that will easily leave enough room on your desk for a keyboard and mouse pad. Like to watch DVD movies? You can save space in your home by watching them on your computer monitor instead of on a TV. If this interests you be sure to buy the largest-sized screen you can afford.

The CRT’s disadvantages must of course include its bulkiness and weight. This is not a highly mobile computer peripheral. Another disadvantage for those who use the monitor hour after hour is glare. While glare can be minimized through adjusting the set, it can only be wholly corrected with an anti-glare shield, which is an extra cost that should definitely be factored into a decision to buy a CRT. In terms of the long term costs of the monitor, a clear disadvantage is the much greater power consumption of CRTs as compared with the other technologies. To minimize this, set the screen saver to come on rather quickly, and consider skipping the fancy screen saver programs; a blank screen while you are away will do quite nicely. A final disadvantage, which in the midst of a Canadian winter can be quite welcome, is that they generate, store and disseminate a lot of heat.

LCDs

This is the newish technology, and like any other it’s sexy and cool. LCDs are some 80% less bulky than CRTs, and commensurately lighter, and therefore much more portable; in fact, virtually all laptops and notebooks have them. The latest high end LCDs have crisp image quality and are easy on the eyes. A primary advantage they have over CRTs will interest anyone who works primarily with text. That is, the pixels you find on LCDs have nicely defined edges – and this produces sharp and well-focused letters on the screen. If you are a writer, editor, proof-reader, etc., your best bet is a LCD.

LCDs have almost closed some of the gap with the CRTs in color rendering, especially at the high cost end, and of course the size and weight differences are huge. LCD screens tend to cause less eye fatigue and strain than CRTs without anti-glare screens. The LCDs are immensely more energy efficient, being an almost costless part to operate. The energy savings may not be much for an individual user, but if you are looking at a corporate office where 50 displays are in use, the energy savings might be more of an issue.

LCDs vary considerably in their response times, the speed with which they can turn pixels on, then off, then on again. Older and budget LCDs are so slow that they badly blur movies and fast action games. Although the gap is lessening, for many LCD monitors, especially at the low end, there is reduced color clarity as compared with CRTs. This is because the technology involves different ways to deal with the problem of low response times that are essentially “work arounds” rather than true solutions. For general use, get a monitor up to 24” with a response time of 16 milliseconds or less. For gamers, people using multimedia and color professionals, a response time of 12 milliseconds is the minimum. For hard-core gamers and video professionals, Look for a response time of 8 milliseconds or less.

There are two distinct types of LCD technology available today: active matrix and passive matrix. The preferred format is the active matrix, which uses a TFT (thin film transmitter) to produce a more secure picture with a relatively wide angle of view. TFT provides the best resolution of all of the flat panel technologies, but it's also the most expensive. There is enough difference in these formats that we can decisively say with respect to the passive matrix, just don't go there. Manufacturers are slowly phasing out passive matrix technology, due to its slow response time and overall lackluster performance.

LCDs offer two aspect ratios: standard format (4:3) or widescreen format (16:9 or 16:10). This online computer store recommends widescreen, because it allows you to view multiple windows side-by-side, and thereby see more of what you are writing or working on, or else to work with more than one application. Also, the widescreen format is taking over with high definition TVs, DVD movies, etc., so one might as well move with the times. Your monitor will likely last for a long time, and the widescreen format has already virtually arrived.

As is especially obvious with notebooks, because LCDs use polarized pixels, the effective viewing angle (technically, the viewing direction) can be quite narrow. This means that one must be pretty much directly in front of the screen to see anything clearly. This also means that one will often need to have a very highly adjustable stand to support the monitor, which should be factored in as an additional cost.

LCD monitors are not all created equal. PVA (patterned vertical alignment) and S-PVA (super patterned vertical alignment) are alternative versions of MVA technology, and some have a very high contrast ratios such as 3000:1. PVA panels all use at least true 8-bit color electronics and do not use any color simulation methods. Some S-PVA panels use even 10-bit color internally, which enables gamma and other corrections without banding. PVA and S-PVA can offer good black depth, wide viewing angles and S-PVA can offer additionally fast response times thanks to modern RTC technologies. At the moment, PVA and S-PVA monitors are the only LCDs that offer a wide viewing angle. Unfortunately, they usually cost about 30 per cent more than the others, so in this case you do get what you pay for.

Sometimes MVA and PVA type displays are categorized as VA type displays.

LCD monitors have a disadvantage compared with CRTs in that they can only function effectively at their “native” resolution. The screen can truly display only the number of pixels in its matrix, no more, no less. It can “display” a lower resolution, either by using a fraction of the available pixels, or by blending multiple pixels together to simulate a single smaller pixel. Either way, you get blurry or fuzzy images, especially with text, so plan to leave your LCD set at its native resolution. A potential problem is that if your graphics card does not support the display’s native resolution, you may get poor quality images or perhaps no images at all, so check this out before you part with your monitor dollars.

Because each LCD pixel is separately driven, one can have individual defective pixels that are either stuck on or else are dead. The computer industry has never fully agreed [ISO 13406-2 notwithstanding] on the maximum acceptable number of defective pixels. In practice, a SVGA LCD panel with 4 defective pixels is usually considered defective, and customers should request an exchange for a new one, especially if the defective pixels are close together or near the center of the screen. Some manufacturers now have a “zero defective pixel guarantee,” and will replace such screens for free.

LCD panels also may have or develop defects known as Mura, which look like small-scale cracks with very small changes in luminance or color. Consumers should reject such a screen.

As Wikipedia tells us: “Although LCDs typically have more vibrant images and better “real world” contrast ratios (the ability to maintain contrast and variation of color in bright environments) than CRTs, they do have lower contrast ratios than CRTs in terms of how deep their blacks are. A contrast ratio is the difference between a completely on (white) and off (black) pixel. Also, LCDs can have ‘blacklight bleed” where light (usually seen around corners of the screen leaks out and turns black into gray.” Another problem that Wikipedia notes is that “Some LCD monitors can cause migraines and eyestrain problems due to flicker from florescent backlights fed at 50 or 60 Hz. "

Typically, brightness is not a concern with CRT monitors, but because LCD monitors are backlit they have different brightness levels. The brightness rating for an LCD is commonly referred to as 'nits' and it commonly ranges from 70 to 250 nits. The higher the nits, the brighter the display.

The Bottom Line

Unfortunately the industry is very poor about properly listing the specifications for monitors to help buyers understand and compare them. At a given resolution, there is virtually no cost difference between CRTs and LCDs. The many announcements of the death of the CRT are slightly exaggerated. However, if you choose to buy a CRT online, bear in mind that they are bulky and heavy, which makes them expensive to ship. The massive and ongoing move toward buying from online computer stores is driving a lot of people toward LCDs, mainly for this reason.

Manufacturers add bells and whistles to help sell their products. Some features, like media card readers and USB hubs are nice to have but not always necessary. Others, such as multiple video inputs, are much more necessary. Most monitors have at least two video inputs, usually a VGA-style (analog) connection and a DVI (digital) connection; these will meet the needs for most users. Some monitors also support the newer HDMI connection. If you plan to watch high definition content, make sure that the DVI and/or HDMI connections are "HDCP-compliant." It is also of fundamental importance that the monitor stand should be sufficiently adjustable to meet your ergonomic needs. Make sure that any software needed to setup or control the monitor will be included in the monitor’s cost.

Generally avoid bundled computer deals that include a monitor, because the majority of such deals bundle in whatever is left over in stock, last year’s model, or a no-name loss-leader brand with poor specifications.

Warranties range from 90 days to one year. Read the fine print.

Do not be dazzled by extras, such as USB cards and built-in speakers. When shopping for a monitor, always bear in mind that the most important thing you are seeking is image quality, pure and simple. Even if you actually buy from an online store to save money (and usually you will save a lot), go to a local store to check out with your own eyes which models deliver the best image quality. You can always add extras, but you cannot increase the monitor’s basic performance.