Patent ID: 9372346
Filing Date: 2016-06-21
CPC Classification: G01S,G02B,G06F

Claim Text:
1. An angular detection apparatus for detecting pitch motion of a head mountable display (HMD), comprising: an optically detectable feature selected from the group consisting of at least one of a light source and a reflective marking, the optically detectable feature comprising a directional optically detectable feature and a substantially non-directional optically detectable feature, the substantially non-direction optically detectable feature being viewable over at least a range of angles by which the directional optically detectable feature is viewable; an optical detector configured to detect a separation between the directional optically detectable feature and the substantially non-directional optically detectable feature, one of the optically detectable feature and the optical detector being disposed at the HMD and the other being disposed at a fixed point, the fixed point being fixed such that when the HMD is subject to pitch motion, the fixed point is not subject to the pitch motion; and an orientation detector in operative communication with the optical detector and configured to detect the pitch motion of the HMD from a relative orientation of the HMD and the fixed point in dependence upon the detected separation between the directional and substantially non-directional optically detectable features.