Patent to lock: nitride coated steel and adapter for headphones

The metallic edge that surrounds the iPhone 4 has just gained an extra protection: a patent published by Apple describes a process of coating stainless steel that constitutes your smartphone with nitride, in order to protect the metal against physical and chemical damage, but without harming its appearance.

Patent coating of steel with nitride

The method described in the patent involves successive hot salt baths that result in the formation of a layer of 15 microns thick on the metal. Although thin, it would have a Vickers hardness of at least 1,000 (that of a 98 natural diamond). Shocked? We are too.

Adapter patent for headphone plug

Two other patents concern technologies to be employed with headphone connectors. One provides for the construction of an adapter to allow 2.5mm plugs to be used with 3.5mm inlets. This would be especially important for hearing impaired people using voice-to-text accessories, which use smaller plugs as standard.

The other invention deals with problems when disconnecting headphones with a microphone; the common process can result in the generation of a signal that would terminate a connection. The use of a removal detector connected to one of the plug contacts would solve this issue, preventing the appearance of false signals.

(via Patently Apple: 1, 2)