It's been long rumored that Apple is working on a smart iWatch, and another clue has surfaced to strengthen the case for its possible debut.
The company was recently awarded a patent -- which was initially filed in January -- for a curved battery for electronic devices. Because a curved battery wouldn't necessarily be needed for an iPhone or iPad, it's easy for one to assume it's for another portable device -- one with a curvature in its shape.
The filing with the U.S. Patent & Trademark Office details how "a curve is formed at one end of the battery cell during the manufacturing process" or how it could be formed at "two ends."
"The battery cell includes a set of layers including a cathode with an active coating, a separator and an anode with an active coating," the filing said. "The battery cell also includes a pouch enclosing the layers, wherein the pouch is flexible. The layers may be wound to create a jelly roll prior to sealing the layers in the flexible pouch."
Apple is very specific in its summary of how the battery will come to be: "A curve may also be formed in the battery cell by applying a pressure of at least 0.13 kilogram-force (kgf) per square millimeter to the layers using a set of curved plates applying a temperature of about 85.degree. C. (sic) to the layers."
Apple also cites one of the main reasons for its curved shape is "to facilitate efficient use of space."