Patent ID: 8245445

Claim:
A sash window comprising a window frame; at least two window sashes, including an upper sash and a lower sash, disposed in the window frame and occupying a common first vertical plane in a closed window position, the lower sash being connected by cables to a counterweight vertical-movement mechanism constructed to enable the lower sash to move vertically in the window frame, in parallel arrangement to the upper sash and in an open window position; two scissor mechanisms that are guided between jambs of the window frame so as to horizontally and frontally project said lower sash from the first vertical plane in the closed window position to a second vertical plane in the open window position, or vice versa, wherein each of said two scissor mechanisms includes a first arm and a second arm, with each of said first arm and said second arm being formed by two strips hingedly connected and said first arm and said second arm being articulated with respect to each other so as to pivot in opposite directions and whose arrangement in the window frame determines a single degree of freedom for the lower sash to project the lower sash frontally and horizontally outward in the window frame; and blocking elements to maintain said lower sash in said open window position, said blocking elements comprising a blocking slider, and wherein the lower sash is moved in a vertical path by said counterweight vertical-movement mechanism.