The United States is introducing a redesigned $100 bill armed with a suite of new technological features aimed at foiling counterfeiters.

The bill unveiled Wednesday still features the familiar face of Benjamin Franklin.

But Franklin has been joined by a disappearing Liberty Bell in an inkwell and a bright blue security ribbon composed of thousands of tiny lenses that magnify objects in mysterious ways. Move the bill and the objects move in a different direction.

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Treasury Secretary Timothy Geithner, left, Federal Reserve chairman Ben Bernanke, U.S. Treasurer Rosie Rios and U.S. Secret Service deputy director Keith Prewitt unveil the new note. ((Manuel Balce Ceneta/Associated Press))

The new currency will not go into circulation until Feb. 10, 2011, giving the government time to educate the public in the United States and around the world about the changes.

As many as two-thirds of the $6.5 billion worth of $100 bills in circulation are believed to be held outside the United States. Even after the new bill is released, older bills will still be recognized as valid, Federal Reserve chair Ben Bernanke said at the unveiling on Wednesday.

"U.S. currency users should know they will not have to trade in their older design $100 notes when the new ones begin circulating," Bernanke said.

The redesign brings the highest-value U.S.-dollar denominated bill up to date with less-valuable U.S. bills, all of which have been given recent facelifts.

Starting in 2003, the Bureau of Engraving and Printing redid the $20 and then the $50, $10 and $5 bills. The $1 bill was not redesigned nor are there any plans to do that. The new $100 was originally supposed to be unveiled in late 2008 but was repeatedly delayed as new security features were added.

U.S. officials estimate that less that one per cent of all U.S. bills are counterfeited, with the $20 being the preferred target for U.S. fraudsters, while internationally, the more valuable $100 is most often faked.

The changes are aimed at thwarting counterfeiters who are armed with ever-more sophisticated computers, scanners and colour copiers.

The U.S. Treasury will now begin a public awareness campaign in 25 languages to educate consumers about the new bills.

"We wanted the changes to be very obvious, visible and easy to see," Larry Felix, director of the Bureau of Engraving and Printing, said.

'Best technology available'

The new blue security ribbon will give a 3-D effect to the micro-images that the thousands of lenses will be magnifying. Tilt the note back and forth and you will see tiny bells on the ribbon change to 100s as they move.

But that's not all. Tilt the note back and forth and the images will move side to side. Tilt the note side to side and the images will move up and down.

In addition, to the right of Franklin's portrait will be an inkwell that will change colour from copper to green when the note is tilted. The movement will also make a Liberty Bell appear and disappear inside the inkwell.

"As with previous U.S. currency redesigns, this note incorporates the best technology available to ensure we're staying ahead of counterfeiters," Treasury Secretary Timothy Geithner said.

Franklin will remain on the front of the $100 bill and Independence Hall in Philadelphia will remain on the back of the currency although both have been modified in ways aimed at making it harder to produce counterfeit copies of the bills.

"The new security features announced today come after more than a decade of research and development to protect our currency from counterfeiting," said U.S. Treasurer Rosie Rios, whose signature along with Geithner's will appear on the new currency.

With files from The Associated Press