Patent ID: 6938377

Claim:
A double hung window comprising: an upper pane and a lower pane, said lower pane including a pivoting latch member, and said upper pane including a keeper, said keeper having a tongue for selectively receiving said pivoting latch member to prevent vertical movement between said upper and lower pane, said pivoting latch member being movable to an open position at which said upper and lower panes may move relative to each other; and said keeper including a force-applying surface providing a generally elongate surface having a slight radius of curvature for providing a downward force to said upper pane, said generally elongate surface being attached to said keeper, said force-applying surface being spaced in an upward direction relative to said tongue, such that said tongue is spaced toward said lower pane from said force-applying surface, said tongue extending along a first distance, and said force-applying surface extending along a second distance, with said second distance being more than twice said first distance.