Panasonic Talks Tech
By Scott Wilkinson June 16, 2005 — This week, Panasonic hit the road to demonstrate their latest products to journalists in San Francisco, San Jose, and Los Angeles, California. Unfortunately, the shipping company they hired to get the gear from San Jose to LA dropped the ball (at least they didn't drop the gear!), failing to deliver the equipment on time, so most of the presentation was theoretical.

Their primary message was the value and quality of plasma panels, particularly in the right environment. Bill Schindler, Panasonic's vice president of electrical engineering, stressed that last point, and rightly so. He noted that LCD flat panels are excellent in rooms with lots of uncontrolled ambient light, but in a real home theater, plasmas are the way to go. After some market-research data (flat-panel sales are on the rise while CRT sales are falling—duh!), Schindler talked about Panasonic's new plasma factory near Osaka, Japan, which will open in September with an initial manufacturing capacity of 1.5 million units per year (including all sizes up to 65 inches). The ultimate capacity will be 3 million units per year, bringing Panasonic's total capacity to 5 million per year.

Then it was time to get down to some serious tech, and I was glad that Schindler could easily speak that language. He started by explaining that Panasonic plasmas use a lower priming voltage to prepare the pixels for firing, reducing the black level. Also, Panasonic plasmas apply the priming voltage once per frame rather than once per subfield as many others do, further lowering the blacks.

What's a subfield, you ask? So did I. I learned that during each frame of the video signal (that is, within each 1/60 of a second), a plasma panel flashes the image 10 times or more, and each of these images is called a subfield. In addition, each subfield lasts twice as long as the previous one—a "powers of 2" progression. The panel's gray-scale performance depends on which subfields are turned on when.

Schindler also talked about contrast ratios and how they depend in part on ambient light. In fact, LCD flat panels have better on-axis contrast ratios in bright environments, while plasmas beat them in dark rooms; the crossover point is around 100 lux of ambient light. And a plasma's contrast ratio remains much more consistent over a wide range of viewing angles. I was surprised to learn that an LCD's viewing angle is defined as the angle at which the contrast ratio drops to 10% of its on-axis value.

One interesting point of discussion was human visual acuity. According to Schindler, the human eye can resolve pixels 1mm across at a distance of 10 feet, and the optimal seating distance is just beyond where you can see individual pixels. This is critical when deciding if you really need a 1080p display. According to his acuity numbers, the optimum seating distance for a 45-inch 1080p display is around 6 feet; a 50-inch display requires around 7 feet, and a 71-inch display needs about 10 feet. Of course, a 720p (or 768p) display requires a longer seating distance, and in many real-world home environments with a seating distance of around 10 feet, there is no need to spend the extra money for a 1080p panel measuring less than 70 inches diagonally.

One bone of contention among plasma watchers is the issue of burn-in and phosphor aging. Schindler noted that early plasmas did suffer from these problems, but Panasonic's new plasma phosphors drop to 95% brightness after 6000 hours (which is better than a typical CRT), compared to 90% for the phosphors Panasonic used in 2004. As a result, burn-in is much less of an issue than it once was, and it isn't really a concern in home-theater applications. (Airport signage is another matter!)

Like many plasma and LCD flat-panel manufacturers today, Panasonic claims a time-to-half-brightness of 60,000 hours, which translates to over 20 years at eight hours a day, seven days a week. Schindler also pointed out that, while LCDs are typically spec'd for the same lifetime, that number must be cut in half if a panel is used in its high-brightness or "vivid" mode, which many are.

Of course, we all know that LCD flat panels are more expensive than plasmas of equal size; the glass alone costs twice as much. Schindler claimed that plasma costs have a lot of room to drop, especially in terms of mechanism and circuitry. He noted a study by DisplaySearch, an independent flat-panel market-research firm, which indicates that plasma will remain less expensive per screen inch than LCD for a long time to come. All in all, it was an interesting presentation.