
In addition to a display screen, the head-mounted display could include controls, a camera, microphone, speaker, batteries, sensors and more. These could be used for unique control methods while wearing the glasses.
“For example,” the application reads, “accelerometers on the head-mounted device and/or the portable electronic device can be used to detect the user’s head movements. In this example, the head-mounted device… can associate a particular head movement with a command for controlling an operating of the head-mounted display system.
Via appleinsider.com