Retractable knife

Details Retractable knife Retractable knife

1998-11-04

2001-04-24

Watts, Douglas D. (Department: 3724)

Cutlery

Sheathed

Sliding blade

C030S335000

Reexamination Certificate

active

06219923

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to hand-held cutting knives, and more particularly to knives having retractable blades.
Hand-held utility knives such as those used by hobbyists, artists, draftsman, and those used for odd jobs around the home and office have long been known. A well-known form of such knife has a small metal blade detachably secured at one end of an elongate cylindrical handle and is ideal for detailed cutting work where tight control of the knife blade is required. Examples of such knives are sold under the X-Acto® trademark.
While known knives are excellent tools for detailed cutting, there is believed a need for a less expensive, more compact and disposable knife for the odd cutting job around the home or office. For some applications, the typical elongate handle can be a hindrance to the job at hand. Furthermore, the typical knife may not be practical for carrying and storage where a smaller sized knife would be preferable.
These and other limitations of known knives establish a need for a simple, compact, inexpensive and relatively safe utility knife.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a utility knife having a blade that automatically retracts upon activation by the user. In this manner the blade defaults to a safe position and is extended only when desired by the user.
It is another object of the invention to provide a knife that has few parts, is simple to assemble, and is relatively inexpensive to produce. Reducing costs and minimizing the materials of production would make such knives more disposable, thereby avoiding the necessity of changing blades as required with known types of knives.
A further object of the invention is to provide a relatively small utility knife easily gripped with the fingertips for detailed cutting.
These objects are accomplished by providing a retractable knife having a housing which has a front and a rear and which forms an internal cavity. Disposed within the internal cavity is a coil spring which defines a longitudinal passage within the spring. The spring has first and second ends, the first end being substantially fixed relative to the housing between the front of the housing and the second end of the spring. Positioned for longitudinal movement within the longitudinal passage of the spring is the blade. Being retractable, the blade is movable between an extended position relative to the housing and a retracted position within the housing. The spring biases the blade towards the retracted position. A manually operable push rod extends through the housing and is in contact with the blade for movement therewith.
The knife can further include a release switch positioned on the housing to engage the push rod when the blade is in the extended position. The switch is moveable to a position disengaged from the push rod for releasing the blade. The switch preferably has an integral resilient shaft about which it can pivot to release the blade.
The knife may also include a safety switch positioned on the push rod to engage the housing when the blade is in the extended position. The safety switch is moveable to a position disengaged from the housing to release the push rod.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows and in part will become apparent to those skilled in the art or may be learned by practice of the invention.


REFERENCES:
patent: 1448305 (1923-03-01), Langbein
patent: 3106017 (1963-10-01), Milbrandt
patent: 3885308 (1975-05-01), Gordin
patent: 5779724 (1998-07-01), Werner
patent: 5966817 (1999-10-01), Lee

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