Cutlery – Sheathed – Sliding blade
Reexamination Certificate
1999-12-02
2001-12-11
Watts, Douglas D. (Department: 3724)
Cutlery
Sheathed
Sliding blade
C030S335000
Reexamination Certificate
active
06327780
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to the field of cutting tools, and more specifically to a safety mechanism for preventing the accidental deployment of a utility knife blade.
BACKGROUND OF THE INVENTION
Utility knives that incorporate retractable, replaceable razor blades are well known in the art. Utility knives are very versatile, enjoying popularity with the professional construction worker, the domestic handyman, and the amateur hobbyist alike. Utility knives generally include a retractable razor blade mounted within a protective handle or housing. The blade is fastened to a support structure such as a blade carrier or blade pusher, which extends through the surface of the housing. In operation, the blade is extended by sliding the blade holder forward. One deficiency of the prior art designs is that the blade may be inadvertently deployed, becoming a safety hazard. For example, if the blade holder catches on a pocket or a tool belt or is jostled by another tool in a toolbox, the blade may be deployed unbeknownst to the user. An unwary user reaching for a utility knife with the blade deployed can easily receive a severe cut.
There have been attempts in the prior art to address this problem. For example, U.S. Pat. No. 5,890,294 to Keklak et al. discloses a locking safety utility knife having an operating lever that deploys a blade when squeezed and a ratchet-like locking mechanism releasable by manipulation (depression) of a cam located at the end of the knife. However, the Keklak et al. device still exhibits the problem of accidental disengagement of the safety if the cam is accidentally depressed, allowing the knife to accidentally open and deploy the blade. Moreover, the cam is located on the end of the knife, increasing the likelihood of accidental depression.
Other known utility knives known in the art have sliding blades that are locked by blade holders that must be depressed as they are slid forward to engage the blade. Again, since the unlocking force and the deploying force may be resolved into a single angular force acting upon the blade holder, accidental release of the blade can readily occur if the blade holder catches on the user's clothing or on another tool.
There is therefore a need in the art for a safety mechanism for a utility knife that cannot be accidentally disengaged through the simple depression of a switch or cam. The present invention satisfies this need.
SUMMARY OF THE INVENTION
The present invention relates to a safety mechanism for a utility knife. The utility knife includes a knife blade mounted in a blade holder that may move between a retracted, blade-stowage position in the housing and a deployed position wherein the blade at least partially protrudes from the housing. The blade holder includes an actuating lever portion protruding from the housing. In one embodiment, a narrow channel is formed in the knife housing through which a tab connected to the blade holder may travel. The channel is foreshortened, such that the tab cannot travel far enough to allow the blade holder to move into the deployed position. The tab is biased to enter the channel when the blade holder is moved into a retracted position, and may only be disengaged by moving the actuating lever in the opposite direction of the deployed position, while simultaneously depressing the actuating lever. The blade may then be deployed by moving the still-depressed actuating lever towards the deployed position.
One object of the present invention is to provide an improved utility knife. Related objects and advantages of the present invention will be apparent from the following description.
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Bigham Gregory
Conway Jon R.
Lowery Gary L.
Beyers Gregory L.
Watts Douglas D.
Woodard Emhardt Naughton Moriarty & McNett
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