Patent ID: 7920314

Claim:
A multi-sheet through-vision panel comprising: a first outer sheet having a first inner surface; a second outer sheet having a second inner surface, said first and second outer sheets being superposed with one another; a middle sheet located between the first and second outer sheets, said middle sheet having a first outer surface facing the first inner surface of the first outer sheet and a second outer surface facing the second inner surface of the second outer sheet; a sliding mechanism configured to slide the middle sheet with respect to the first and second outer sheets between first and second positions; and a round frame having an u-shaped cross-section, wherein the first and second outer sheets have a round shape and form a window together with the round frame being arranged around the outer boundaries of the first and second outer sheets, wherein the middle sheet has a substantially round shape with first, second, and third linearly cut boundaries, the first and second linearly cut boundaries forming linear side edges in a direction to a sliding movement of the middle sheet, and the third linearly cut boundary being perpendicular to the first and second linearly cut boundaries and configured to form an area to accommodate the sliding mechanism in the window, wherein at least one of the first and second inner surfaces has at least one light impairing zone, and the middle sheet has at least one light impairing zone on at least one of said first and second outer surfaces, wherein said light impairing zones are superposed with one another when said middle sheet is in said first position and wherein said light impairing zones are in a staggered arrangement when said middle sheet is in said second position, and wherein the sliding mechanism includes a bolt arranged perpendicularly to the first outer sheet traversing the first outer sheet, and a translation mechanism fastened to the bolt.