Patent ID: 8915615

Claim:
A shutter assembly for a lighting apparatus, the shutter assembly comprising: an axial direction; a light path for passage of light emanating from a light source; at least one shutter plate moveable into a position external to or at least partially across the light path, wherein the shutter plate is rotated in a plane that is substantially perpendicular to the axial direction; a rotatable shutter lock being rotatable to directly or indirectly generate a friction force on the shutter plate; wherein the friction force generated on the shutter plate is dependent on the rotational position of the shutter lock and in at least one rotational position there is sufficient frictional force to retain the shutter plate in the position external to or across the light path; and, wherein the shutter lock comprises a rotatable plate which bears directly or indirectly against the shutter plate, wherein the rotational position of the rotatable plate sets the displacement of the shutter plate in the axial direction.