Closure fasteners – Bolts – Sliding
Reexamination Certificate
1999-09-30
2001-09-25
Knight, Anthony (Department: 3626)
Closure fasteners
Bolts
Sliding
C292S165000, C070S091000
Reexamination Certificate
active
06293598
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an improved door latch mechanism for a push-pull type door handle, and in particular to an improved lock design for a push-pull door latch mechanism having an override function.
BACKGROUND OF THE INVENTION
Known door latch mechanisms include the traditional rotary type where a door knob is rotated to unlatch a latch bolt, and so-called push-pull types in which a door handle is either pushed or pulled to retract the latch bolt. The push-pull type of door latch mechanisms are particularly suited to high traffic or sanitary environments, such as public restrooms, hospitals, clinics or the like, where it is desirable to unlatch the latch bolt without using ones hands.
It is well known that various infectious diseases are spread through contact with a contaminated surface such as a door handle or similar frequently contacted surface. Thus, it would be particularly advantageous to be able to open a door after washing ones hands without having to use ones hands because touching the door handle partially negates the beneficial effect of hand washing. The demand for such a device is particularly acute in facilities open to the general public such as in commercial or institutional settings.
Particularly in the case of hospitals, clinics, rehabilitation centers, nursing homes and similar facilities, it is further desirable to equip such a door latch mechanism with an integral locking mechanism including a lock override. Notably, it is desirable to temper the desire for privacy with the somewhat conflicting need to provide access to the occupant in the event of an emergency. Thus, what is truly required is a lock which prevents accidental intrusion while facilitating reasonable ease in overriding the lock in the event of an emergency.
One such door latch mechanism is disclosed in U.S. Pat. No. 5,403,047 which patent is hereby incorporated by reference. In the '047 patent, locking is obtained by interference with the push/pull action of the door handle. However, the door latch mechanism disclosed in the '047 patent contains several disadvantages. One disadvantage relates to the complexity of the door locking mechanism and the large number of parts required.
Consequentially, a first object of the present invention is to provide an improved push-pull latch mechanism including a latch mechanism and an override switch which utilizes a relatively simple construction.
A second object of the invention is to provide an improved push-pull latch mechanism which provides a more robust construction.
A third object of the invention is to provide an improved push-pull latch mechanism having component parts configured to facilitate interchangeability.
A fourth object of the invention is to provide an improved push-pull latch mechanism including a lock knob configured to be located on either interior or exterior sides of the door by merely interchanging the latch covers.
SUMMARY OF THE INVENTION
The above-listed objects are met or exceeded by the present push-pull door latch mechanism having a lock override feature. One feature of the invention relates to the use of a simple cam engaging lock, which enhances ease of assembly and is also relatively durable. Further, the design of the door latch mechanism of the present invention eliminates the need for a separate lock bolt, as privacy is maintained by preventing inadvertent actuation of the latch bolt.
Specifically, the present invention provides a push/pull door latch mechanism for laterally unlatching a retractable latch bolt of a latch bolt assembly, the latch mechanism including a first door handle provided on an interior side of a door, and a second door handle provided on an exterior side of the door. The first door handle acts upon a rotatable first cam. The first cam has a locking shoulder, a pin configured for engagement with the engagement portion of the first door handle, and a latch bolt assembly engaging portion operably connected to the latch bolt assembly.
In like manner, the second door handle acts upon a second rotatable cam. The second cam has a pin configured for engagement with the engagement portion of the second door handle, and a latch bolt assembly engaging portion operably connected to the latch bolt assembly.
First and second lock members are provided, each being configured for rotation between locked and unlocked positions, where in the locked position, the first lock member is rotated into engagement with the locking shoulder of the first cam. A lock coupling operably connects the first lock member and the second lock member such that rotational movement of one of the first and second lock members causes rotational movement of the other of the first and second lock members.
A lock knob is provided on the interior side of the door, the lock knob being operably connected to the first lock member and facilitating toggling of the first and second lock members between locked and unlocked positions. An override knob is provided on the exterior side of the door, and is operably connected to the second lock member which in turn is operably connected to the first lock member. Notably, toggling of the override knob toggles the first and second lock members between the locked and unlocked positions.
Rotation of the lock knob into the locked position causes rotation of the first lock member into engagement with the locking shoulder (of the first cam) and prevents rotation of the first and second cams. Correspondingly, rotation either of the lock knob and the override knob into the unlocked position causes rotation of the first lock member out of engagement with the locking shoulder and permits rotation of the first and second cams, thereby causing the latch bolt assembly to retract the latch bolt.
REFERENCES:
patent: Re. 36209 (1999-05-01), Walls
patent: 4986583 (1991-01-01), Campbell et al.
patent: 5403047 (1995-04-01), Walls
patent: 5474348 (1995-12-01), Palmer et al.
patent: 5609372 (1997-03-01), Ponelle
patent: 5730478 (1998-03-01), D'Hooge
patent: 6131966 (2000-10-01), Hensley et al.
patent: 6196599 (2001-03-01), D'Hooge
Architectural Builders Hardware
Greer Burns & Crain Ltd.
Knight Anthony
Rodgers Matthew E.
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