Types of Projectors

Three technologies: LCD, DLP and LCoS

There are three projector technologies on the market, though two -- digital light processing (DLP) and liquid crystal display (LCD) -- are more commonly used. Historically, DLP projectors offered better contrast and black levels, while LCD projectors claimed better color saturation with less fan noise and lower operating temperatures.

Thanks to improvements in both technologies, the differences between LCD and DLP have narrowed substantially, but there are still some significant distinctions that could make one or the other more suitable for your purposes. DLP digital projectors are subject to what is known as the "rainbow effect," due to the fact that they use a color wheel to generate an image. Because of this, a small percentage of viewers see occasional flashes of solid color. The effect is minimized, but not eliminated, in DLP projectors that use faster color wheels. In addition, many DLP digital projectors are finicky about where they are placed relative to the screen, making placement trickier than with LCD. On the other hand, LCD projectors tend to suffer from what is known as the "screen door effect" -- images sometimes look as they would if you were viewing them through a mesh panel. Experts say DLP still has the upper hand in black levels and contrast, therefore producing the most cinematic image. LCD projectors hold a slight price advantage over DLP projectors.

A third technology, called liquid crystal on silicon (LCoS), is newer than DLP and LCD technologies and is becoming increasingly popular. LCoS projectors have an outstanding picture quality and are free from both the rainbow and screen door effects. LCoS first debuted on top-dollar theater projectors and cost anywhere from an astounding $10,000 to $15,000. However, this technology has advanced rapidly over the past few years, and while it is still generally pricier than DLP and LCD projectors, you can now find LCoS projectors under $2,000. Additionally, LCoS technology is used to drive the tiny inexpensive 3M MPro100 (*Est. $350) profiled earlier.

SVGA, XGA or Widescreen

Portable digital projectors come in a variety of resolutions and aspect ratios. Native resolution measures the sharpness of the projected image and refers to a projector's true resolution without compressing the number of pixels (compression degrades image quality). SVGA (800 pixels by 600 pixels) and XGA (1,024 pixels by 768 pixels) digital projectors display images in a 4:3 aspect ratio.

As noted by Art Feierman of ProjectorReviews.com, XGA resolution gives you "clean crisp data on any sized text and graphics." Because of that, and because the price difference between XGA and SVGA projectors has closed dramatically, XGA is the most popular choice among business projector buyers. Projectors with SVGA resolutions are still available, however, and since they are perfectly able to display the dozen or so lines of large text on a typical PowerPoint slide, they are a reasonable choice for buyers on a tight budget.

There has been an increase in the number of widescreen portable digital projectors. These digital projectors are offered in a number of native resolutions. Projectors with WVGA resolution (854 pixels by 480 pixels) match the full resolution of DVD movies, so you get every ounce of a DVD's image quality. WVGA is an unconventional standard that also includes resolutions of 800 pixels by 400 pixels and 848 pixels by 480 pixels. In fact, any display that's wider than VGA can be classified as WVGA.

Many widescreen business projectors have WXGA resolution. WXGA is another non-standard standard that includes several different resolutions. For business projectors, 1,280 pixels by 800 pixels is a popular WXGA resolution since it matches that of many 14- and 15-inch laptops. That resolution can also display widescreen 1,280 pixels by 720 pixels high-definition images or 1,024 pixels by 768 pixels XGA images without cropping or scaling.

Some digital projectors offer a native resolution of 1,400 pixels by 1,050 pixels called SXGA+. That matches the display resolution of many widescreen computer monitors and larger (17-inches and up) widescreen laptops. Some 14- and 15-inch laptops now also have SXGA+ graphics.

Brightness, contrast and lamp life

For business use, brightness -- measured in lumens -- is a major consideration. Since many presentations are given in conference rooms with standard office lighting, the image needs to be bright enough to be seen. For smaller boardrooms, a brightness of 1,000 to 1,500 lumens should be fine. For larger rooms or small auditoriums, look for 1,500 lumens or higher.

Contrast ratio refers to the difference between the darkest black and brightest white in a projected image. For data and graphics projections, editors at Laptop magazine say a ratio of 400:1 is sufficient. If you want to play video and DVDs, however, a contrast ratio of more than 1,000:1 means that dark scenes will be darker and more cinematic. Keep in mind that manufacturer brightness and contrast claims are almost always inflated, but they do give you a way to compare digital projectors.

The term "throw" reflects the distance between the projector and the screen. In the past couple of years, projector manufacturers have introduced ultra short throw projectors that can be placed very close to the screen and still produce a large, clear image that's free of geometric or other distortion. That can really come in handy if you're travelling to unfamiliar conference rooms and have to set the projector up in a small or awkward space.

Portability makes a big difference to business users. Heavier models can weigh up to ten pounds. The lightest office projectors weigh around two to three pounds. Pico or pocket projectors weigh less than a pound, but their usefulness for business applications is limited.

Digital projectors use lamps that must be replaced periodically. Average lamp life is about 2,000 to 3,000 hours, and replacement lamps can cost $300 or more. A few models of office projectors have long-life lamps rated to last longer. Although business projectors have warranties of up to three years, lamps are usually only under warranty for 90 days. Be sure to consider this in your long-term costs.

Finally, some portable projectors also come with an array of accessories that may be important to you. Included features like a carrying case, fully functional remote control and a laser pointer are part of some projector packages.