Horizontally supported planar surfaces – Folding – Legs fold axially parallel to surface edges
Reexamination Certificate
2001-05-17
2003-07-29
Wilkens, Janet M. (Department: 3637)
Horizontally supported planar surfaces
Folding
Legs fold axially parallel to surface edges
C108S130000, C108S132000, C248S436000
Reexamination Certificate
active
06598544
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to foldable support legs for tables, chairs, portable staging, risers, or other similar portable equipment requiring foldable legs for supporting a surface. More particularly, the present invention relates to an improved locking mechanism for folding legs which is simpler and stronger than other similar mechanisms.
2. Related Art
Portable tables, chairs, risers, etc. having foldable legs are well known. Such devices typically comprise a support surface of some kind having a plurality of support legs hingedly attached to the underside. The legs are rotatable from a folded position against the underside of the support surface, to an extended position where they are generally perpendicular to the support surface. When in the extended position, the support legs are typically locked into place by means of a lock arm, a catch, a linkage, or some other similar locking mechanism. The most common of these mechanisms typically involve hinged angular supports and sliding collars, or spring loaded catches.
To be functional and safe, these locking mechanisms must hold the legs firmly in place, without wobbling or twisting. However, they must be easy to lock and unlock, particularly for novices who are unfamiliar with the mechanism. Accordingly, it is preferable that such devices be lightweight, simple, and intuitive to use. Unfortunately, some prior leg locking mechanisms have relatively low strength, and are susceptible co failure. For example, hinged angular supports can easily buckle if a locking collar is not properly placed, possibly resulting in collapse of the legs and the support surface. Some prior leg locking mechanism can also be in the way of one's knees when sitting at the table. Others are complicated, expensive, and sometimes not very durable. Many of them are also quite heavy, and noisy, thus reducing the desirability, portability, and practicality of the support device.
SUMMARY OF THE INVENTION
It has been recognized that it would be advantageous to develop a locking mechanism for folding legs which is strong and durable, simple in construction and operation, and is relatively lightweight.
It has also been recognized that it would be advantageous to provide a locking mechanism for folding legs which eliminates or reduces potential hazards to one's knees, and which also provides for a wide range of leg styles.
The invention advantageously provides a locking mechanism for a support leg hingedly attached to a support surface. The locking mechanism includes a base, attached to the support surface, with a plurality of angularly spaced, radial teeth, and a coupler, attached to the support leg, having a plurality of angularly spaced, radial teeth configured to mate with the teeth of the base. A selectively releasable engagement mechanism is configured to engage and disengage the teeth of the base with the teeth of the coupler to allow selective rotation of the support leg from an extended position to a folded position, and to lock the leg in place in the folded and the extended position.
In accordance with a more detailed aspect of the present invention, the locking mechanism may include a pair of oppositely oriented bases attached to the support surface, each having a support leg connected thereto, and the pair of support legs being mechanically connected, the selectively releasable engagement mechanism further comprising an oppositely directed spring force built into each of the connected pair of legs, such that the natural position of the legs provides force to engage the teeth. A flexible tension member may be provided for countering the force of the engaging means to allow the tops of the legs to be drawn together, thus drawing the teeth out of engagement, allowing the legs to be rotated from the extended position to the folded position, and vice versa.
In accordance with another more detailed aspect of the present invention, the selectively releasable engagement mechanism may further comprise a biasing spring configured for biasing the counter-locking side of the coupler away from the locking side of the base, and a cam associated with the coupler, configured for creating a biasing force for biasing the counter-locking side of the coupler toward the locking side of the base, the biasing force of the cam being greater than the biasing force of the biasing spring. A release is associated with the cam, configured to release at least part of the biasing force of the cam, to allow the biasing spring to disengage the teeth of the base and the coupler, and allow rotation of the support leg when the release is actuated by a user.
Additional features and advantages of the invention will be apparent from the detailed description which follows, taken in conjunction with the accompanying drawings, which together illustrate, by way of example, features of the invention.
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Laws David J.
Smith Richard D.
Spendlove Dale
Swindler Phillip J.
Mity-Lite, Inc.
Thorpe North & Western LLP
Wilkens Janet M.
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