US Patent 9435126 Folding stairs, especially light wooden stairs

There is provided folding stairs having three segments of ladder stairs connected to one another with hinges. The first segment of stairs is connected with an articulated joint to a door frame using hinge holders fitted on the inside wall of the door frame, such that, during unfolding of these stairs rotation axle of the first segment of stairs does not change its position against the door frame. A flap is suspended to the first segment of stairs with at least two pairs of connecting rods, which together with the first segment of stairs and the flap form four-bar linkage.