Utility knife

Details Utility knife Utility knife

1999-03-25

2001-10-30

Watts, Douglas D. (Department: 3724)

Cutlery

Combined cutlery or combined with ancillary feature

With material-holder or disposal

C030S002000, C030S169000

Reexamination Certificate

active

06308418

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to tools. More particularly, the invention disclosed herein comprises a utility knife with a longitudinally reciprocatable blade shield and a readily removable blade retainer.
BACKGROUND OF THE INVENTION
With sharp edges designed for cutting, knives inherently present a danger of inadvertent cutting. This danger is particularly prevalent with utility knives where rapid and repeated cutting operations often are demanded. In such instances, the demanded speed or the monotony of repeated cutting operations may lead to a worker's not exercising a sufficient degree of care to maintain his or her own safety. For example, such a hurried or bored worker may use one hand to slice the razor blade quickly through a cardboard box or another article to be sliced, past the edge of the article, and into painful engagement with the worker's other hand, leg, or other body part Other problems often arise when a user employs a utility knife to perform a cutting operation and forgets to retract the device's razor blade. With this, a user swinging his or her arms while walking could inflict a painful gash to his or her own leg or to the body of another. Certainly, numerous other potential dangers resulting from an exposed razor blade will be obvious.
For many years, it was generally accepted that the dangers presented by utility knives were unavoidable. Advantageously, however, a plurality of inventors have made numerous attempts at making utility knives safer for normal use while compromising the knives' utility as little as possible. For example, the prior art reveals a utility knife with a pivotable, spring-biased guard that rotates from a blade-shielding position for protecting a user from the dangers of the razor blade to a blade-exposing position for allowing the performance of a cutting operation. Another utility knife provides an elongate safety guard that is disposed immediately adjacent to the cutting edge of the razor blade. The safety guard is longitudinally reciprocatable and is biased to an extended position such that it can retract to expose the razor blade to allow cutting and it can extend to shield the razor blade immediately after the utility knife is removed from the article being cut.
Unfortunately and notwithstanding the useful efforts of such previous inventors, utility knives continue to suffer from a plurality of disadvantages. For example, retractable blade shields in prior art devices normally shield both sides of a razor blade. With such shields, a user certainly enjoys some protection from the razor blade. However, the blade shield disadvantageously blocks the razor blade from a users sight. As a result, a user can forget or not notice that the razor blade is in an extended position whereby the very protection sought in providing the blade shield acts to endanger a user who might put the utility knife in the user's pocket or otherwise expose the user to danger from the unseen blade.
It must be recognized that utility knives have been disclosed with a blade shield disposed only on one side of a retained razor blade. These devices advantageously allow a user to view a retained razor blade even while the blade shield is in position protecting the user from the razor blade. However, such blade shields are known to be fixed relative to their respective utility knives. As a result, cutting with such utility knives requires that the razor blade be extended to a position beyond the blade shield or cutting operations with such a utility knife must be limited or specially adapted.
On a different note, one skilled in the art will be aware that in the most basic of utility knives, which is commonly referred to as a box cutter, replacing a razor blade comprises the relatively simple task of sliding a blade retainer from within a sheath, removing the dulled or broken blade from the blade retainer, inserting a blade with a sharp edge into the blade retainer, and sliding the blade retainer again into the sheath. Unfortunately, these box cutter utility knives can be among the most dangerous of utility knives. Not only is the razor blade completely unshielded when extended, but also the blade retainer is unrestrictedly slidable relative to the sheath whereby the razor blade can be extended unintentionally to present a most dangerous surprise.
Later-developed utility knives, for example those with shields or locking mechanisms, seek to cure one or more of the box cutter's drawbacks. In doing so, however, such knives have made it difficult or even impossible to replace spent razor blades. In many knives, a separate tool, such as a screwdriver, is required. Other knives are designed to be disposable, and they provide no means of replacing a spent razor blade. Such disposable knives often have elongate blades that are scored to allow a user to snap off distal sections of the blade when they become dull thereby to present a new, sharp section. Unfortunately, snapping sections from the blades of such knives presents a further danger from flying shards of worn metal.
In light of the foregoing, it becomes clear that a utility knife presenting a solution to one or more of the aforementioned deficiencies left by the prior art would be useful. However, it is dearer still that a utility knife presenting a solution to each and every one of the aforementioned problems while providing a number of heretofore unrealized advantages would represent a marked advance in the art.
SUMMARY OF THE INVENTION
Advantageously, the present invention is founded on the broadly-stated object of providing a utility knife that meets the needs that have been left unmet by the prior art. Stated more particularly, a principal object of the present invention is to provide a utility knife that is capable of shielding a razor blade with a reciprocatable shield in a manner that simultaneously allows a user to determine visually the position of the razor blade and, therefore, to appreciate the danger the utility knife presents. A further object of the invention is to provide a tool, such as a utility knife, that allows a user to separate constituent elements of the tool to enable, for example, a user to change razor blades expediently and safely. Another object of the instant invention is to provide a utility knife that presents an enlarged engaging shoulder disposed at an optimal angle for assisting a user in maintaining a consistent ideal, and safe cutting angle. A still further object of the invention is to provide a utility knife that is equally usable by left-handed and right-handed users. Yet another object of the invention is to provide a utility knife that, in addition to enabling a user to cut, also allows a user to scrape articles, such as stickers, from a given surface. Undoubtedly, these and further objects and advantages of the present invention will become obvious both to one who reviews the instant disclosure and to one who enjoys the opportunity to use an embodiment of the present invention.
In accomplishing the aforementioned objects, one preferred embodiment of the invention essentially comprises a tool in the form of a utility knife that comprises an elongate sheath with a body portion that has a proximal end and a distal end, a means for retaining a razor blade, and a blade shield reciprocatably coupled to the elongate sheath. The blade shield, which comprises a side member disposed adjacent to a first side of a retained razor blade, is longitudinally reciprocatable between a blade-shielding extended position for protecting a user and a blade-exposing retracted position for cutting. TAME blade shield may be biased to the blade-shielding extended position.
With this, the invention is extremely safe in use. One most basic reason is that the blade shield prevents inadvertent cutting with a retained razor blade because it is biased to shield the razor blade when not performing a cutting operation. The blade shield does so while uniquely allowing a user to see a retained razor blade even while the blade shield is in an ex

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