Fujitsu is releasing a new laptop today that breaks one of the rules of notebook physics -- it has a bigger screen than a similar predecessor model, but it's lighter. How does that work? The reason is the change in screen technology from fluorescent-backlit to LED-backlit.

Back in August I talked with Paul Moore, senior director of mobile product marketing for Fujitsu, for a story headlined "The Future Of Mobile Tech: Next Year's Notebooks Will Be Worth Waiting For." The future, it turns out, is now. Moore spoke in general terms then about the display technology in the LifeBook S6510 Fujitsu announced today -- a 14-inch widescreen LED display on a laptop that weighs four pounds. That's with the optical drive. Take out the optical drive and it goes down to 3.7 pounds.

The 14-inch LED screen fits in the same space that would have been required by a 13.3-inch LCD screen. The difference, Moore said yesterday on the phone, is that the LED display panel doesn't require an inverter, a transformer that steps up the notebook's battery power to drive a high-voltage circuit that powers the screen's backlighting. LED backlighting runs on unmodified battery voltage, so the inverter, and the space it takes around the display can be used for something else, like a bigger display.

Taking out the inverter not only saves space, it makes the display more reliable (if you've ever had a laptop's inverter die on you, you've known heartache -- I know I have). It also saves weight and it saves power: the S6510's specs say it will run for 4-1/2 hours on its standard six-cell battery, or more than 6 hours with the optical drive removed from the modular bay and replaced with a second battery.

With the weight savings of the LED screen and new 9.5-mm thin optical drive, the $1,529 S6510 weighs about a pound less than the 13.3-inch version, said Moore. That's an impressive diet for any notebook, and a demonstration of the changes still coming in notebook technology.