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[EMedia]
Reviews

Fujitsu Plasmavision PDS-4221 42" Display Panel

Peter H. Putman


EMedia Magazine, October 2000
Copyright © Online Inc.


Fujitsu Plasmavision PDS-4221 42" Display Panel
synopsis: Fujitsu's PDS-4221 is a 42" (diagonal) 1024 x 1024 pixel widescreen monitor, capable of showing video and computer graphics in a variety of pixel resolutions and picture aspect ratios. It's thin (3.3"), lightweight (70 pounds) produces very bright, contrasty images, and can be mounted in a variety of ways. While the PDS-4221 does a good job with computer graphics, its video performance leaves something to be desired.

price: $15,999, add $899 for optional speakers

Fujitsu Computer Products of America
2904 Orchard Parkway
San Jose, CA 95134
800/626-4686
Fax 408/594-3606
http://www.fujitsu.com
http://www.plasmavision.com

If you haven't seen a plasma display by now, you've surely heard about them. Plasma display panels–or PDPs, for short–are one of the hottest display products available. It's easy to see why: they combine big, bright images with wide viewing angles while cutting down on weight and depth. To many people, plasma displays are the incarnation of the "television you can hang on a wall" envisioned by science fiction writers many years ago.

what is plasma?

While the idea of a super- flat TV or computer monitor is pretty cool, you're probably wondering just how plasma works in the first place. In a nutshell, plasma panels are made up of thousands of tiny pixels, created when two ribbed structures are attached at right angles to each other. The ribs themselves are coated with color phosphors–red, green, and blue–and the sealed pixels contain a rare gas mixture (such as argon and neon), plus three electrodes.

When voltage is discharged across the pixel, the gas inside temporarily changes to a "plasma" state, and actually conducts the electrical charge from one terminal to another. As it does this, the gas emits a burst of ultraviolet light, which in turn causes the color phosphor in that pixel to glow brightly.

To best understand the concept, you need look no further than the ordinary fluorescent lamp, which also operates as a "plasma" device. When you turn one on, a device in the lamp creates a high-voltage discharge to "fire" the lamp. Once the lamp is turned on, a lower "sustain" voltage keeps it operating, until it is switched off.

The tiny pixels within a plasma panel are charging and discharging at very high speeds–fast enough to show video and high-refresh-rate graphics. A technique known as Pulse Width Modulation provides varying levels of brightness, using the ratio of "on" and "off" pixel states in a given time interval to determine light intensity.

screen size and pixel counts

Plasma panels are manufactured using a silk-screen process and are available as small as 25" and as large as 60". The shapes of the panel can resemble a computer monitor (4:3 or 5:4 aspect ratios), or they can take on the shape of a widescreen TV (16:9 aspect ratio). The actual pixel count of a panel is independent of the screen size–there are 25" displays with SXGA (1280 x 1024 pixel) native resolution, and 50" panels with wide XGA (1365 x 768 pixel) resolution.

Fujitsu is one of the leading manufacturers of plasma displays, having begun research and development of plasma technology way back in the late 1960s. (The first working plasma panels were invented at the University of Illinois in 1963.) Fujitsu started shipping full-color models in the United States in 1996, and currently offers two PDPs–the 42" widescreen PDS-4208, with wide VGA (852 x 480 pixel) resolution, and the review unit, a PDS-4221 42" widescreen panel with high-definition resolution (1024 x 1024 non-square pixels).

At first glance, the 1024 x 1024 pixel resolution doesn't make sense. Intuitively, these numbers would mean a square panel, not 16:9. But Fujitsu uses a non-square pixel that resembles a tiny 16:9 brick, which explains the widescreen aspect ratio. This technique was perfected so Fujitsu could develop a high-resolution panel using the same assembly line and tooling used for its wide VGA panels.

When you first look at the PDS-4221, your reaction is generally: where are the controls? The no-frills frame around the panel (which provides strength and a duct for cooling air) has a couple of indicator lamps, and that's it–until you find the drop-down control panel, directly under the center of the frame. The basic panel can't stand on it's own. Unlike some manufacturers, Fujitsu doesn't provide built-in legs, so you'll need to purchase the accessory stand (P-42TT11-H) or wall brackets (also available) to support it.

A separate remote comes with the panel, and it has a minimum of buttons. In addition to Power On/Off, there's an RGB input selector which chooses signals at either the 15-pin VGA connector or a row of five BNC jacks, and a VIDEO input selector which chooses between the same 5xBNC row or three other BNC jacks for component video. This is where you'd connect a DVD player or a digital television set-top box.

The panel's menu structure appears with very crude-looking characters. It boasts a full range of available adjustments, including image brightness and contrast, color saturation and hue, and sharpness. With computer signals, you can adjust their size and position on the screen, as well as brightness and contrast. You can select from several picture aspect ratios if you want to fill the image, including two Wide modes for widescreen DVDs and two Zoom modes for enlarging regular images to fill the screen–although with either some image "squashing" or cropping will result.

on the test bench

An auto-detect circuit in the PDS-4221 does its best to match the signal from your computer to the panel's display resolution, but doesn't always work. In my tests, I connected 25 different computer video signal standards to the panel to see how many it would lock up on and give me a clean picture. These rates started at VGA-1 (31.5 kHz scan, 70Hz refresh) and went up to 1600 x 1280 UXGA (89.3kHz scan, 67Hz refresh.)

The PDS-4221 was able to produce clean pictures from 10 input signals, while three more required some fiddling with the menu, and one wouldn't display cleanly at all. In addition, 11 signals resulted in an "Out of Range" menu display. In general, the PDS-4221 will display all VGA, SVGA, and most XGA input signals, but I wouldn't use it to view any higher-resolution computer images.

In video mode, things were a bit more predictable. Video signals from both my Sony DVP-S7000 DVD player and a Panasonic TU-DST51 DTV set-top box locked up immediately with the correct aspect ratio and picture-sync format. HDTV receivers use a three-wire component video format (YPbPr) similar to that of DVD players (YCbCr), but this component format is different from the four- (RGBS) and five- (RGBHV) wire formats used by computers.

If the panel doesn't automatically detect the correct signal format–and many don't–then you may get an all-green or all-pink image, which has to be corrected by going into the panel's menu and changing a setting. Fortunately, the PDS-4221 has enough smarts to make that changeover automatically, leaving you to just change from "VIDEO" to "RGB" input modes and vice-versa.

While video signals presented correctly, image quality was not up to par. Plasma panels suffer from a unique malady known as "false contouring," or the "creeping moss" effect. A false contour in an electronic image is caused when the image isn't sampled sufficiently. You can see this effect by changing the setting on your computer's display monitor from 16.7 million colors to 256 colors, and looking at a still photograph.

Where there is a gradual change in brightness from medium to low levels of gray, an artificial boundary will be seen. This is a false contour, and the PDS-4221 has plenty of them when displaying movies from DVD and even HDTV signals. At present, there is no external fix for false contouring–it can only be handled by changing the driving electronics in the panel, and even modifying the way the pixels are addressed.

Two other manufacturers have already come close to eliminating false contours (Pioneer and Panasonic), so it's reasonable to expect Fujitsu will get a handle on this problem in the near future. In the meantime, if you need a plasma panel to display still images with mostly mid- to high- tones of color, you probably won't notice and care about this effect.

In terms of brightness, the PDS-4221 is one of the best performers out there. After setting the brightness and contrast controls to their correct levels with test patterns, I measured 90.5 candelas per square meter (cd/m2) with a full white pattern. That's 25% brighter than a reference TV monitor, and 40% brighter than my 18" desktop LCD monitor.

Tests with a checkerboard pattern showed the panel to have an average contrast ratio of 153:1, which is comparable to a good CRT video or computer monitor. Peak contrast was measured at 186:1, so you'll get plenty of contrast from this panel. However, the black levels are on the high side at .7 cd/m2, and you'll see a dark gray instead of a dense black when the panel is switched on with no signals present.

Color saturation is quite good, and you can select from one of four color temperatures: cool, normal, warm, and studio. The first two are a bit on the blue side, and generally used to view computer graphics. The Warm mode is used to display video and HDTV, and will make flesh tones and yellow and red colors look more natural. The Studio setting results in an almost orange image, but is designed so the panel will look correctly on the set of a TV program.

I liked many things about the PDS-4221. There's no question it looks best with computer graphics, and it does an acceptable job with high-definition video. Regular video suffers from the false contouring problem and isn't nearly as crisp as it could be. The user interface is easy, but the menus look too crude and should be updated. Although the PDS-4221 can't correctly size many computer sync rates, it works well enough with the most common signals and is smart enough to sort them out from component video.


Peter H. Putman, a Certified Technology Specialist, is president of ROAM Consulting, Inc., which provides consulting and marketing communications services to manufacturers, dealers, and end-users of large-screen display products. Putnam currently writes for Video Systems, Sound & Video Contractor, Millimeter, Etown.com, and Church Production.

Comments? Email us at letters@onlineinc.com.

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