Patent ID: 7070215

Claim:
A dual function lock for use on a double hung window comprising: (a) a base adapted to be attached to an upper rail of a sash; (b) a shaft having a longitudinal axis, the shaft including an upper end and a lower end, wherein the lower end includes at least one cog protruding transversely to the longitudinal axis, and wherein the upper end of the shaft is received by an opening in the base; (c) a handle rotatably connected to the base wherein the handle includes a locked position in which a first portion of the handle is configured to be positioned to engage an upper sash, and an unlocked position in which the first portion of the handle is configured to be positioned out of engagement with the upper sash; (d) a tilt latch drive member rotationally actuated by the cog and positioned coaxially with the longitudinal axis of the shaft, wherein the tilt latch drive member is adapted to receive an extensible member, wherein the tilt latch drive member has a null zone between the locked and unlocked positions of the handle wherein there is no substantial movement of the extensible member as the handle is rotated from the locked to unlocked positions, and wherein the tilt latch drive member is adapted to cause the extensible member to move in a direction toward the lock as the handle is rotated from the unlocked position to a tilt position.