Is a finger a stylus? If the claim construction is based on the patent specification's definition... maybe.
Among the patents asserted by Samsung in its April 27 suit against Apple is US6,292,179, Software keyboard system using trace of stylus on a touch screen and method. This is initially quite puzzling, because, as Steve Jobs rather emphatically pointed out when introducing the iPhone in 2007, it does not use a stylus.

"Oh a stylus, right? We're gonna use a stylus! No. No. Who wants a stylus? You have to get 'em and put 'em away, and you lose 'em. Yuck! Nobody wants a stylus, so let's not use a stylus. " - Steve Jobs, Macworld Keynote, 2007
The complaint states, however:
Upon information and belief, in violation of 35 U.S.C. § 271, Apple is and has been directly infringing, contributing to the infringement of, and/or inducing others to infringe the '179 patent by making, using, selling, and/or offering to sell in the United States, or importing into the United States, products or processes that practice the inventions claimed in the '179 patent, including without limitation, the Apple iPhone 3G, the Apple iPhone 3GS, the Apple iPhone 4, the iPod Touch, the iPad, the iPad 3G, the iPad2, and the iPad 2 3G.
The '179 patent comprises four independent claims, one for the software keyboard system and three for related methods. Independent system claim 1 contains the elements:
"a touch panel on said screen, generating a coordinate value in accordance with a position pressed by a stylus;"
and
"a controller controlling said display of said keyboard image, receiving said digital value for a trace of said stylus, and determining the position and direction of said trace;"
Independent method claims 7, 11, and 13 each contain the step:
"obtaining the trace of a stylus."
So, all of the claims require a stylus. Samsung did not include Ten One Design or other iPhone stylus makers as defendants. Where is the stylus coming from?
It would be hard to argue that a finger is within the plain meaning of the term "stylus." However, a patent applicant is allowed to be his own lexicographer, within reason. It appears that Samsung is trying to say they did just that, relying on language in the '179 specification to broaden the definition of stylus beyond its common meaning to include fingers:
"Here, "stylus" is used as a general term for any object which, when pressed onto a touch screen, can cause an input to a computer system or the like." ('179 patent, column 1, lines 14-16)
It seems odd to consider a finger an "object," and therefore a "stylus" under the patent's definition. However, that does seem to be Samsung's interpretation to justify asserting the patent.

"No stylus" - Macworld 2007 Keynote
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