Patent ID: 6984050

Claim:
A heliostat for a sunlight concentration system which reflects and focuses sunlight to a light concentration portion, said heliostat comprising a frame member ( 7 ) rotatable according to a diurnal motion of the sun and a plurality of concave mirror elements ( 8 ) having a first curvature, with at least two concave mirror elements individually and pivotably connected to the frame member via an articulation ( 10 ), orientations of main axes of said concave mirror elements being variable, said concave mirror elements defining a single concave mirror having a second curvature, an orientation of a main axis of said concave mirror being controlled so as to constantly reflect incoming sunlight toward said light concentration portion, wherein: the orientations of the main axes of said concave mirror elements are changed so as to reduce said second curvature when the incident angle of sunlight with respect to the main axis of said concave mirror is large; and the orientations of the main axes of said concave mirror elements are changed so as to increase said second curvature when the incident angle of sunlight with respect to the main axis of said concave mirror is small.