Buckles – buttons – clasps – etc. – Including readily dissociable fastener having numerous,... – Having filaments constructed from coated – laminated – or...
Reexamination Certificate
2002-04-11
2003-07-29
Sandy, Robert J. (Department: 3677)
Buckles, buttons, clasps, etc.
Including readily dissociable fastener having numerous,...
Having filaments constructed from coated, laminated, or...
C024S442000, C428S100000
Reexamination Certificate
active
06598274
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to hook and loop fasteners of the type that are well known and commercially available under the Trademark VELCRO. More specifically, the invention relates to hook and loop fasteners in which the two halves of such a fastener can be released from engagement with each other via external means without the application of direct, external physical force.
DESCRIPTION OF THE INVENTION
Hook and loop fasteners have been well known in the fastener art for many years and they have been used successfully in many and widely diverse applications. The secure engagement of one half to the other and the substantial force required to separate the two halves appear to have contributed significantly to the popularity of this type of fastener. However, the force that must be applied to achieve separation of the two halves, the brief but finite time required to achieve separation, and the incremental or progressive nature of the separation process, have been found to make the separation process difficult and/or unsatisfactory in some instances.
The inherently incremental nature of the known separation process, requiring the two halves to be progressively “peeled” apart, can make the use of hook and loop fasteners unsatisfactory and/or extremely difficult in applications that lack sufficient clearance for a peeling or tilting motion. Similarly, the finite time required to “peel” one half from the other sometimes precludes the use of hook and loop fastenings when relatively “instant” separation, such as the separation of snap fasteners, is required. Hook and loop fasteners designed for “heavy duty” applications with substantial holding force can require similarly substantial separation forces. Separation forces under these circumstances may exceed the physical ability of certain users, thereby further limiting the application of these worthwhile fastening devices.
SUMMARY OF THE INVENTION
The present invention is directed to providing a hook and loop fastener in which the time and force required to separate the two mating halves are reduced to a minimum. This invention is further directed to providing hook and loop fasteners that can be fabricated readily using available materials and known techniques. Another advantage of the hook and loop fastener of this invention is that disengagement of the two halves can be automated if desired. Further, disengagement can even be accomplished remotely, without direct application of external physical force.
Hook and loop fasteners in accordance with this invention can be fabricated in generally conventional manner, but, commercially available “shape-memory” alloy material such as Nitinol must be used to form at least part of the hook elements. Shape-memory alloy material comprises a key element of the hook and loop fastener of this invention.
An important aspect of shape-memory alloy material, also known as “muscle wire,” is that it is electrically responsive so as to change its shape when an electrical current flows through it. More specifically, shape-memory alloy material in wire form can be made to contract in length in response to the flow of electricity through the wire. This invention relies on this property of shape-memory alloy wire to allow the two halves of the hook and loop fastener to disengage from each other by passing electrical energy through the hook portion of the fastener. That is, the hooks are caused to straighten so as to loose their “hook” shape when an electrical potential is applied.
By selectively applying electrical energy to cause the hooks to assume a straight-line “memory” shape, the characteristic interlocking engagement of the hooks with the loops is released, and the two halves of the fastener are, in effect, instantly disengaged from each other. In light of this disclosure, it can now be seen that the application of electrical energy to a suitably constructed hook and loop fastener can be made to cause disengagement of the loop portion of such a fastener from the hook portion without the application of external physical force. That is, if desired, disengagement of the fastener assembly can be effected from a remote location using electrical energy only. In this regard, it will be understood that physical displacement generally will be required to achieve actual separation of the two halves of a fastener. In many applications such displacement can be achieved through the force of gravity alone, after the hook elements are “straightened.” However, in view of this disclosure, it will be apparent to those having ordinary skill in this art that various different arrangements can be employed utilizing the disengagement method and apparatus of this invention to achieve physical separation of two fastener halves.
In the disclosed embodiment of the invention, a two-part hook and loop fastener assembly of conventional configuration is formed using electrically conductive flexible material for part of the hook elements. More specifically, in the hook element half of the fastener, the hook elements are formed at least in part, of electrically conductive shape-memory alloy material such as Nitinol. It is known that Nitinol in wire or narrow strip shape, can be made to contract in length in response to the flow of electrical current. This invention contemplates the use of this kind of shape-memory alloy wire or strip. Although expansion or contraction of the material is possible, contraction is believed to be the more commonly available and therefore preferable characteristic.
It will be understood readily by those having ordinary skill in this art, that wires or strips made of materials having an expansion or contraction characteristic can be joined in parallel relationship with another “inert” material to form a single element, similar to the bimetallic element of a conventional thermostat. Such an element can be made to distort in a desired manner when one of the two materials contracts or expands. The hook elements of the fastener of this invention are constructed accordingly. That is, the hook-shaped elements are formed of a length of shape-memory material joined in parallel relationship with an inert material, the combination being formed to have the desired hook shape. Accordingly, a normally hook-shaped element having the contracting shape-memory material positioned along the outer curved circumference of the hook shape will tend to straighten into a straight-line or “rod” shape when the flow of electricity through the shape-memory “muscle wire” causes the outer circumference of the hook to shorten from its un-energized length. Shortening the outer circumference of the hook has the effect of “opening” the hook shape by straightening it toward a “rod” shape as the inner and outer circumferences of the hook approach equality in length. Thus, the usual, or non-memory form of the hooks corresponds to the conventional “hook” shape used in hook and loop fasteners, whereas the energized, “memory” shape of the normally hook-shaped elements is that of a substantially straight line or rod, free of any significant hook shape.
It can be seen readily that the substantially straightened rods on the first half of the fastener, free of any reversely bent “hook” shape, will disengage from and be free of locking or fastening engagement with the loop elements of the second half of the fastener. The formed, hook-shape elements are transformed into their straight rod “memory” condition by the flow of electricity through the shape-memory alloy wire material in accordance with the known characteristics of such materials.
In accordance with this invention, the base surface material of the hook half-portion of the fastener preferably will be electrically conductive. Hooks cut and formed of lengths of stock made of two materials joined in the manner herein identified can be produced and anchored in generally upright orientation to a desired base surface using suitable, known fabrication techniques. Techniques for achieving the necessary electrical connection between the shape-memory alloy portion of eac
Jackson André
Koninklijke Philips Electronics , N.V.
Sandy Robert J.
Waxler Aaron
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