Safety mechanism for preventing accidental deployment of a utility knife blade

Abstract

A safety mechanism for a utility knife, including a razor blade mounted in a blade holder slideably mounted in a blade chamber in the housing. A first blade holder includes an arm extending therefrom with an engaging surface thereon. A second blade holder includes a tab extending therefrom. When either blade holder is deployed from the housing, the tab contacts the engaging surface, thereby preventing deployment of the other blade until the original blade is retracted.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No. 60/624,310, filed Nov. 2, 2005, which is incorporated by reference in its entirety.

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. Furthermore, for utility knives with separate controls for deployment of each of two blades, there is a need for a safety mechanism that prevents deployment of both blades at the same time. The present invention satisfies both of these needs.

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. Two such blade holders are provided such that blades may be deployed from either end of the knife. In one embodiment, a first one of the blade holders includes an arm extending therefrom in the direction of the second blade holder. The second blade holder has a tab that engages the arm of the first blade holder, such that interaction between the arm and the tab prevent one blade holder from being deployed while the other blade holder is deployed.

In one form of the invention, a safety mechanism for a utility knife is disclosed, comprising: an elongated housing having an apertured anterior end and an apertured posterior end; an anterior blade chamber formed within the anterior end of the housing and aligned with the anterior aperture; a posterior blade chamber formed within the posterior end of the housing and aligned with the posterior aperture; an anterior blade holder slideably mounted in the housing and having an anterior blade-engaging portion positioned in the anterior blade chamber, and an arm operationally coupled to the anterior blade-engaging portion and extending substantially toward the posterior blade chamber, the arm having a contacting surface; a posterior blade holder slideably mounted in the housing and having a posterior blade-engaging portion positioned in the posterior blade chamber, an extension operationally coupled to the posterior blade-engaging portion, and a tab coupled to the extension and adapted to selectively engage the contacting surface; an anterior blade mounted in the anterior blade holder; a posterior blade mounted in the posterior blade holder; wherein the posterior blade holder is adapted to move between a recessed position wherein the posterior blade is completely within the housing and a deployed position wherein the posterior blade extends partially outside of the housing; wherein the anterior blade holder is adapted to move between a recessed position wherein the anterior blade is completely within the housing and a deployed position wherein the anterior blade extends partially outside of the housing; wherein the tab engages the contacting surface when one of the respective anterior and posterior blade holders are in the respective deployed position; whereby if the anterior blade holder is in the deployed position, then the posterior blade holder cannot be moved from the recessed position; and whereby if the posterior blade holder is in the deployed position, then the anterior blade holder cannot be moved from the recessed 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.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the preferred embodiment of the present invention.

FIG. 2 is an exploded side perspective view of the embodiment of FIG. 1.

FIG. 3 is a side elevational view of the blade holder of the embodiment of FIG. 1.

FIG. 4a is a side sectional view of the embodiment of FIG. 1 with the blade recessed and locked.

FIG. 4b is a side sectional view of the embodiment of FIG. 1 with the blade recessed and unlocked.

FIG. 4c is a side sectional view of the embodiment of FIG. 1 with the blade deployed.

FIG. 5 is a side elevational view of a first type of second embodiment blade holder of the present invention.

FIG. 6 is a side elevational view of a second type of second embodiment blade holder of the present invention.

FIG. 7 is an exploded perspective view of a second embodiment housing of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

Referring now to FIG. 1, there is illustrated a first embodiment of the present invention, indicated generally at 20. With reference to FIG. 2, the utility knife 20 includes a housing having an anterior end 24 and a posterior end 26. Preferably, the housing 20 has 180-degree rotational symmetry about a midpoint 25. In other words, the preferred embodiment is a double-acting utility knife 20 adapted to deploy a razor blade from either end 24, 26, embodiments having different numbers of blades are likewise contemplated.

Referring now to FIG. 2, the anterior and posterior ends 24, 26 of the preferred embodiment have apertures 28a-b formed therein. The apertures 28a-b are preferably slots, although they may have any convenient configuration. Chambers 30a-b are formed in the housing, each adapted to receive a blade holder 32 (see FIGS. 3 and 4a-c). Safety channels 34a-b are also formed in the housing adjacent the blade chambers 30a-b. Safety channels 34a-b are formed extending respectively from end walls 35a-b and open respectively into blade chambers 30a-b. A razor blade (illustrated in phantom at 36 in FIGS. 3 and 4a-c) may be removably coupled to each blade holder 32.

FIG. 3 illustrates blade holder 32. Blade holder 32 is adapted to hold a razor blade 36 in the blade-engaging portion 40, while actuating lever portion 42 extends out above the blade-engaging portion 40. Blade holder 32 also includes a tab or safety-channel engaging portion 44, which preferably extends at a substantially 90-degree angle from actuating lever portion 42. Safety channel engaging portion 44 is adapted to slidingly engage one of the safety channels 34a-b when blade holder 32 is operationally positioned in housing 22.

FIGS. 4a-c illustrate blade holder 32 slidingly positioned in housing 22 and in which a blade 36 has been operationally coupled. While FIGS. 4a-c detail a blade holder 32 positioned to deploy a blade 36 from the anterior end 24 of utility knife 20, it is understood that the illustrated process equally applies through symmetry to a blade deployed from the posterior end 26. FIG. 4a illustrates blade holder 32 occupying recessed position 46, with safety channel engaging portion 44 slidingly engaged in safety channel 34a. Blade holder 32 is prevented from moving towards anterior end 24 (and blade 36 is prevented from exiting slot 28a) by the end wall 35a of safety channel 34a lockingly engaging safety channel engaging portion 44.

FIG. 4b illustrates blade holder 32 being disengaged from safety channel 34a. A disengaging force vector acts on blade holder 32 such that channel engaging portion 44 is slid away from end wall 35a, down safety channel 34a, and into blade chamber 30a, thus releasing blade holder 32 and enabling blade holder 32 and held blade (illustrated in phantom at 36) for deployment.

As is shown in FIG. 4c, blade 36 is deployed by sliding blade holder 32 towards anterior end 24 of utility knife 20 while maintaining sufficient force on the safety channel engaging portion 44 (by depressing actuating lever portion 42) to prevent it from re-engaging safety channel 34a. Blade (illustrated in phantom at 36) in deployed position 50 partially extends through slot 28a.

Blade holder 32 is preferably formed from spring steel, but may be made of any material that will exert a biasing force against deformation. The spring steel exerts a biasing force on tab 44, pushing it into channel 34a as soon as it is aligned with channel 34a. Tab 44 must be pushed against the biasing force to remove tab 44 from channel 34a in order for the blade to be deployed.

A second embodiment of the present invention is illustrated in FIGS. 5-7, with continuing reference to FIGS. 1-4. Items in the second embodiment that are substantially similar to like items in the first embodiment are given like reference designators. The second embodiment utility knife of the present invention provides a safety feature that prevents accidental (or intentional) deployment of both blades at the same time.

As shown in FIG. 5, in order to provide this feature, a first blade holder 132 in the second embodiment is substantially identical to the blade holder 32, but includes an arm 60 depending therefrom in the direction of the second blade holder. The arm 60 includes a widened portion 62 at the distal end thereof. Portion 62 includes an engaging surface 62a.

A second blade holder 232 of the second embodiment is illustrated in FIG. 6. Second blade holder 232 includes an extension 64 with a tab 66 extending substantially perpendicular therefrom. Tab 66 is sized and positioned so as to contact engaging surface 62a of the first blade holder 132 if there is an attempt to deploy both blade holders 132,232 at the same time. As shown in FIG. 7, a channel 70 is formed in the central wall of the utility knife housing in order to allow passage of the arm 60 from the first blade holder 132 to the second blade holder 232.

In operation, when first blade holder 132 is retracted, second blade holder 232 may be fully deployed before tab 66 contacts engaging surface 62a. Once tab 66 is in contact with engaging surface 62a, first blade holder 132 may not be deployed because the interaction between tab 66 and engaging surface 62a prevents such movement. Similarly, if first blade holder 132 is deployed first, engaging portion 62a will come into contact with tab 66 once first blade holder 132 is fully deployed. This contact will then prevent deployment of second blade holder 232 until first blade holder 132 is retracted. Consequently, both blades of the utility knife cannot be deployed at the same time.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.

Claims

1) A safety mechanism for a utility knife comprising:

an elongated housing having an apertured anterior end and an apertured posterior end;

an anterior blade chamber formed within the anterior end of the housing and aligned with the anterior aperture;

a posterior blade chamber formed within the posterior end of the housing and aligned with the posterior aperture;

an anterior blade holder slideably mounted in the housing and having an anterior blade-engaging portion positioned in the anterior blade chamber, and an arm operationally coupled to the anterior blade-engaging portion and extending substantially toward the posterior blade chamber, the arm having a contacting surface;

a posterior blade holder slideably mounted in the housing and having a posterior blade-engaging portion positioned in the posterior blade chamber, an extension operationally coupled to the posterior blade-engaging portion, and a tab coupled to the extension and adapted to selectively engage the contacting surface;

an anterior blade mounted in the anterior blade holder;

a posterior blade mounted in the posterior blade holder;

wherein the posterior blade holder is adapted to move between a recessed position wherein the posterior blade is completely within the housing and a deployed position wherein the posterior blade extends partially outside of the housing;

wherein the anterior blade holder is adapted to move between a recessed position wherein the anterior blade is completely within the housing and a deployed position wherein the anterior blade extends partially outside of the housing;

wherein the tab engages the contacting surface when one of the respective anterior and posterior blade holders are in the respective deployed position;

whereby if the anterior blade holder is in the deployed position, then the posterior blade holder cannot be moved from the recessed position; and

whereby if the posterior blade holder is in the deployed position, then the anterior blade holder cannot be moved from the recessed position.

2) The safety mechanism of claim 1 further comprising a channel between the anterior blade chamber and the posterior blade chamber, wherein the arm passes through the channel.

3) The safety mechanism of claim 2 further comprising a wall separating the anterior blade chamber from the posterior blade chamber, whereby the channel is formed in the wall.

4) The safety mechanism of claim 1 further comprising:

an anterior safety chamber formed within the housing and oriented substantially parallel to the anterior blade chamber;

a posterior safety chamber formed within the housing and oriented substantially parallel to the anterior blade chamber;

the anterior blade holder having an anterior safety chamber engaging portion adapted to engage the anterior safety chamber; and

the posterior blade holder having a posterior safety chamber engaging portion adapted to engage the posterior safety chamber;

wherein the anterior and posterior safety chambers are adapted to releasably engage the respective anterior and posterior safety engaging portion of the respective anterior and posterior blade holders when the respective anterior and posterior blade holders are in the recessed positions;

wherein the respective anterior and posterior safety chambers are further adapted to prevent motion towards the respective anterior and posterior ends of the respective anterior and posterior engaged safety engaging portions; and

wherein the respective anterior and posterior blade holders must be pushed into the housing and away from the respective anterior and posterior apertures to release the respective anterior and posterior safety engaging portions from the respective anterior and posterior safety chambers, enabling the respective anterior and posterior blade holders to move into the deployed positions.

5) The safety mechanism of claim 4 wherein the respective anterior and posterior safety engaging portions are positively biased into the respective anterior and posterior safety chambers.

6) The safety mechanism of claim 1 wherein the respective anterior and posterior apertured ends are slits.

7) A utility knife comprising:

a housing;

a first blade holder;

a second blade holder; and

a safety mechanism which operationally couples the first blade holder and the second blade holder;

wherein the first blade holder is adapted to move between a first recessed position and a first deployed position;

wherein the second blade holder is adapted to move between a second recessed position a second deployed position;

wherein if the first blade holder is in the first deployed position, then the second blade holder cannot be moved from the second recessed position; and

wherein if the second blade holder is in the second deployed position, then the first blade holder cannot be moved from the first recessed position.

8) The utility knife of claim 7 wherein the safety mechanism comprises:

an arm coupled to the first blade holder, the arm having an engaging surface;

a tab coupled to the second blade holder and adapted to engage the engaging surface when one of the respective first and second blade holders are in the respective first and second deployed positions.

9) The utility knife of claim 7 further comprising:

a first blade chamber formed within the housing;

a second blade chamber formed within the housing; and

a channel between the first blade chamber and the second blade chamber;

wherein the first blade holder is substantially located within the first blade chamber, the second blade holder is substantially located within the second blade chamber and the safety mechanism passes through the channel.

10) The utility knife of claim 9 further comprising a wall which separates the first blade chamber from the second blade chamber whereby the channel is formed in the wall.

11) The utility knife of claim 9 further comprising:

a first safety channel formed within the housing and in communication with the first blade chamber;

a second safety channel formed within the housing and in communication with the second blade chamber;

the first blade holder having a first tab that is biased to engage the first safety channel when the first blade holder is moved into the first recessed position; and

the second blade holder having a second tab that is biased to engage the second safety channel when the second blade holder is moved into the second recessed position;

wherein the first blade holder must be moved toward the first recessed position before the first blade holder can be moved into the first deployed position; and

wherein the second blade holder must be moved toward the second recessed position before the second blade holder can be moved into the second deployed position.

12) The utility knife of claim ii wherein the respective first and second tabs are positively biased into the respective first and second safety chambers.

13) A utility knife comprising:

a housing;

a first blade holder;

a second blade holder;

a first blade mounted in the first blade holder;

a second blade mounted in the second blade holder; and

a safety mechanism which selectively couples the first blade holder and the second blade holder;

wherein the first blade holder is adapted to move between a first recessed position wherein the first blade is completely within the housing and a first deployed position wherein the first blade extends partially outside of the housing;

wherein the second blade holder is adapted to move between a second recessed position wherein the second blade is completely within the housing and a second deployed position wherein the second blade extends partially outside of the housing;

wherein if the first blade holder is in the first deployed position, then the second blade holder cannot be moved from the second recessed position; and

wherein if the second blade holder is in the second deployed position, then the first blade holder cannot be moved from the first recessed position.

14) The utility knife of claim 13, wherein the safety mechanism comprises:

an arm operationally coupled to the first blade holder, the arm having a contacting surface; and

an extension operationally coupled to the second blade holder and adapted to selectively engage the contacting surface when one of the respective first and second blade holders are in the respective first and second deployed positions.

15) The utility knife of claim 13, further comprising:

a first blade chamber formed within the housing;

a second blade chamber formed within the housing; and

a channel between the first blade chamber and the second blade chamber;

wherein the first blade holder is substantially located within the first blade chamber, the second blade holder is substantially located within the second blade chamber and the safety mechanism passes through the channel.

16) The utility knife of claim 15, further comprising a wall which separates the first blade chamber from the second blade chamber whereby the channel is formed in the wall.

17) The utility knife of claim 15, further comprising:

a first safety channel formed within the housing and in communication with the first blade chamber; and

the first blade holder having a first tab that is biased to engage the first safety channel when the first blade holder is moved into the first recessed position;

wherein the first blade holder must be moved toward the first recessed position before the first blade holder can be moved into the first deployed position.

18) The utility knife of claim 17 wherein the first tab is positively biased into the first safety chamber.

19) The utility knife of claim 15, further comprising:

a second safety channel formed within the housing and in communication with the second blade chamber;

the second blade holder having a second tab that is biased to engage the second safety channel when the second blade holder is moved into the second recessed position;

wherein the second blade holder must be moved toward the second recessed position before the second blade holder can be moved into the second deployed position.

20) The utility knife of claim 19 wherein the second tab is positively biased into the second safety chamber.