Door latch bolt locking device

Claim 1

A door latch bolt locking device for use with a latch bolt having a transverse groove in its top surface to positively prevent the withdrawal of the latch bolt and the opening of the door, comprising: a slideable member adapted to be disposed flushly with the intersecting edge surface of the door and the inner surface of the door, said member having a first flat portion adapted to be substantially flush with the inner surface of the door, and an integral tongue portion at a right angle to said first portion and adapted to be substantially flush with the edge surface of the door; means for allowing said slideable member to be moved through a limited vertical distance in a substantially flush relationship with said door surfaces so that said tongue portion can move into and out of a received relationship with the transverse groove in the latch bolt; and means for positively maintaining said slideable member in the latch bolt-locked position when subjected to vertical forces, said maintaining means comprising a horizontally-extending member fixed to the inner surface of the door and adapted to be received by an opening in the slideable member; and said slideable member having an opening adapted to receive said horizontally-extending member in a snapping-in action and wherein said slideable member acts to receive and release said horizontally-extending member when said slideable member is pulled outwardly from its substantially flush engagement with the inner surface of the door, said slideable member being made of a material which will provide a biasing return force when the slideable member is pulled outwardly.