Closure fasteners – Keepers – With movable dog – catch or striker
Reexamination Certificate
2001-05-07
2003-06-24
Knight, Anthony (Department: 3676)
Closure fasteners
Keepers
With movable dog, catch or striker
C292S341180, C292S144000
Reexamination Certificate
active
06581991
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to mechanisms which can control access by personnel into and out of buildings or restricted areas. Specifically this invention is to a new and automated door latch actuator that can interface with a more T-type dead latch of a type typically used in commercial applications. This invention can be provided as originally equipment or as a retrofit on existing doors. The invention is also directed to methods of automatically actuating dead latches.
BACKGROUND OF THE INVENTION
This invention is directed to improvements to U.S. Pat. No. 5,474,342 issued Dec. 12, 1995 to Smith et al and to U.S. Pat. No. 6,022,056 issued Feb. 8, 2000 to Cope et al. Each of these patents was directed to operate with North American cylindrical dead latches (also sometimes called tubular or bored dead latches). When used with the North American cylindrical dead latch, the apparatus shown in the '342 Patent and the '056 Patent serve to release the door when electric signal is applied to it.
Where the conventional door latch assembly in the door is of the North American cylindrical dead latch type, the disclosure shown in the '342 Patent has an actuator element disposed in proximity to the distal ends of both the spring latch bolt and the dead latch bolt pin. The driver moves an actuator element between first and second actuator positions. When in the first actuator position, the actuator element is operative to retain the dead bolt latch pin in a disabled (retracted) state while allowing the spring latch bolt to extend into the latch/bolt cavity. The actuator element, when moved from the first actuator position, first releases the dead latch bolt pin which moves into the enabled (extended) state and afterward attacks the distal end of the spring latch bolt to move the spring latch bolt from the extended state to the retracted state.
The '056 Patent was an improvement over the several embodiments of the door latch actuator shown in the '342 Patent. Particularly, the door latch actuator in the '056 Patent employs a spring latch plunger and a dead latch plunger mounted in a housing that has latch cavities sized to receive the spring latch bolt and the dead latch bolt pin. The spring latch plunger engages and retracts under pressure of the spring latch bolt, and the dead latch plunger engages the dead latch bolt pin. A drive operates the plungers to first withdraw the dead latch plunger to allow the dead latch bolt pin to move to an enabling position for the spring latch bolt. Next, the drive advances the spring latch plunger and thereby the spring latch bolt is moved to release position, and the door may be opened. The drive in the '056 Patent is preferably a rotary drive using a motor driven crank and pin system. Sensors are provided to detect the position of the system.
A second type of latch is widely used, especially in commercial application, that significantly differs from the North American cylindrical dead latch. This type of dead latch is common referred to as a “mortise-type” dead latch. The mortise dead latch typically is robust and more costly than a cylindrical dead latch and, as noted, finds it is used almost entirely in commercial and industrial buildings. Assemblies shown in the '056 Patent employ small plungers that confront one another to operate spring latch and the dead latch which, in the cylindrical dead latch are directly adjacent one another. While the disclosure of the '342 Patent shows several embodiments, including an embodiment using two independently acting solenoids, the technology shown in these patents is difficult to directly apply to mortise-type dead latches. The main difficulty in adapting the technology inherent in the above cited patents derives from the position of the dead latch pin (also called the dead latch trigger) in relation to the spring latch. In the case of mortise-type latches, the dead latch pin is not adjacent to the spring latch but is rather above or below the spring latch depending upon the manufacturer. The wide variety of dead latch pin positions that exist in mortise latches poses a problem for efficient development of an automated door latch actuator. The direct application of the technology in the above described patents would necessitate a different door latch actuator for each different model of mortise dead latch in order to suit the varying positions of the dead latch pin. This increases manufacturing and inventory costs for both manufacturers and distributors.
While the technologies disclosed in the '342 Patent and the '056 Patent present significant advances over prior art automated security latch system, further development is indicated for door latch actuators for mortise-type dead latches. There is a need for door latch actuator constructions and methods which will operate mortise-type dead latch assemblies. There is a further need for a mortise-type dead latch automated actuator which can accommodate different mortise-type dead latch constructions thereby to reduce manufacturing and inventory costs. The present invention is directed to those needs.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a new and useful method and apparatus for automated actuating of mortise-type dead latch.
Another object of the present invention is to provide a door latch actuator and method that can be implemented with a variety of differently configured mortise-type lock assemblies.
A further object of the present invention is to provide a door latch actuator that is easily installed into existing door frames to interface with mortise-type dead latches.
Still a further object of the present invention is to provide a door latch actuator that is rugged yet simple in construction.
Still a further object of the present invention is to provide a door latch actuator which is relatively inexpensive in manufacture yet reliable in use.
In its broad form, the door latch actuator of the present invention is adapted to mount in a frame portion of a door and engage a mortise-type dead latch disposed on an edge portion of the door. Typically the mortise-type dead latch includes a spring latch and a dead latch pin or trigger that is linearly spaced-apart from the spring latch along the edge portion of the door. This spring latch is reciprocally moveable between an engaged position so that it can engage the door thereby to retain the door in a fastened state and a release position wherein the door is released from the fastened state. The dead latch pin is reciprocally moveable between enabled position that permits movement of the latch spring from the engaged position to the release position and a disabled position that prohibits movement of the spring latch from the engaged position to the release position. The spring latch is resiliently biased into an engaged position and the dead latch is resiliently biased into the enabled position.
The present invention thus includes a housing having a cavity with a forwardly disposed opening that is sized and adapted to receive the spring latch and the dead latch pin when the door is in the fastened state. A spring plunger is mounted for linear reciprocal movement in a longitudinal throw direction in the housing between an extended position and a retracted position. A dead latch plunger is also mounted for linear reciprocal movement in the longitudinal throw direction in the housing between an advanced position and a withdrawn position. A portion of the spring latch is selectively positionable at a selected first location in the opening of the cavity. This first portion of the spring latch plunger is operative to engage the spring latch bolt when the door is in the fastened state thereby to accommodate different locations of the spring latch on the edge portion of the door. A striker assembly is supported on the dead latch plunger and includes an assemble of strike elements operative to define a strike surface for the dead latch pin. The striker assembly provides a portal for the spring lat
Gegick Rebecca A.
Henson Michael R.
Knight Anthony
Kyle Michael J.
Martin Timothy J.
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