The patent titled "Head Mounted Display Apparatus For Retaining A Portable Electronic Device With Display" depicts a large eyeglass-style frame into which a smartphone could be seated.

A smartphone would essentially become a screen set directly before the wearer's eyes, with the option of picture-in-picture if a person wants to watch what is happening around him or her.

Coupling the headset device with an iPhone "temporarily integrates the separate devices into a single unit," according to the patent, which Apple filed for in late 2008.

Capabilities of each device would be extended to the other, the patent specified, leaving open the potential to incorporate Siri virtual assistant voice commands.

The gadget described in the patent is similar to Gear VR head gear released last year by Samsung and paired with the South Korean consumer electronics titan's large-screen Galaxy Note 4 smartphones.

At its developers conference in San Francisco last year, Google gave away simple kits to make cardboard virtual reality headsets that act as frames for Android powered smartphones.