On Tuesday, Oct. 25, the US Patent and Trademark issued US Patent No. 8,046,721, assigned to Apple, Inc. This patent grants Apple the exclusive right to make, use, sell, or import into the US, any hand-held or portable electronic device having a touchscreen that a user can unlock by sliding an image from one place to another on the touchscreen, or software that implements this function. Here is the broadest claim:

1. A method of unlocking a hand-held electronic device, the device including a touch-sensitive display, the method comprising: detecting a contact with the touch-sensitive display at a first predefined location corresponding to an unlock image; continuously moving the unlock image on the touch-sensitive display in accordance with movement of the contact while continuous contact with the touch screen is maintained, wherein the unlock image is a graphical, interactive user-interface object with which a user interacts in order to unlock the device; and unlocking the hand-held electronic device if the moving the unlock image on the touch-sensitive display results in movement of the unlock image from the first predefined location to a predefined unlock region on the touch-sensitive display.

Google’s Android operating system includes this method of unlocking a dormant device, and hence every Android smartphone infringes this patent.

Windows 8, Microsoft’s next operating system (release date not yet announced) includes many features to facilitate touchscreen input, and a slide-to-unlock function is one of them (at least on Windows 8 developer preview versions already shipped to software developers). The Windows 8 OS requires a user to slide a message from the bottom to the top of the screen, as opposed to the iPhone’s and Android’s left-to-right slider. However, the direction of motion is not an element of the broadest claims, and hence the Windows 8 OS would also infringe (if unchanged from the developers preview).

This patent adds considerable clout to Apple’s portfolio, and will certainly play a major role in the nascent patent war brewing between Apple and Google.