Germany's patent court invalidated Friday a patent held by Apple -- and contested by rivals Motorola and Samsung -- on its "slide to unlock" function for smartphones, but the ruling can still be appealed.

The federal patent court ruled that the the horizontal swiping gesture was not a technical innovation in itself and therefore did not meet requirements of European patent law.

The aim of the function was to make it easier for users to unlock their smartphone and not solve a specific technical problem, the court argued.

Apple can still appeal the ruling.