EP1150809B1

EP1150809B1 - Double-ended dual-mechanism retractable blade utility knife

Info

Publication number: EP1150809B1
Application number: EP99901318A
Authority: EP
Inventors: Greg L. Beyers
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-01-13
Filing date: 1999-01-13
Publication date: 2004-01-02
Anticipated expiration: 2019-01-13
Also published as: EP1150809A4; EP1150809A1; DE69913991T2; AU2104599A; DE69913991D1; ATE257060T1; CA2360413C; WO2000041856A1; CA2360413A1

Abstract

A double-ended dual mechanism retractable blade utility knife (10). The knife (10) includes two separately actuable mechanisms (382, 386) which allow extension and retraction of one or both blades (28, 34) independently of one another. The cutting surfaces (30, 31) of the respective blades (28, 34) are oriented towards opposite sides of the knife (10), thereby facilitating rotation of the knife (10) within the user's hand in order to change which blade (28, 34) is currently being used. The independent nature of the dual mechanisms allows both of the blades (28, 34) to be held in the extended position. A storage area (72) is further provided behind each of the mechanisms for the storage of spare blades (29).

Description

Technical field of the invention

The present invention generally relates to utility knives and, more particularly, to a double-ended dual-mechanism retractable blade utility knife.

Background of the invention

Utility knives which incorporate a retractable, replaceable razor blade have been popular in many applications for years. There are deficiencies, however, in the prior art designs which limit their usefulness in certain applications. For example, in the roofing trade it is generally necessary for the roofer to carry two such utility knives. One knife is equipped with a straight razor blade for cutting felt paper and the like, while the other knife is equipped with a hooked blade for cutting shingles and the like which have a granulated surface. Neither of these knives are well adapted for cutting the other type of material, therefore it is necessary for the roofer to carry both types of knives.

Carrying two knives, however, is inconvenient, especially when working on a roof. Whenever it is necessary to switch knives, the user must retract the first blade and stow the first knife, take out the second knife and extend the second blade. This is extremely inconvenient during applications where use of both knives in alternating succession is routinely required.

There have been attempts in the prior art to solve this problem. For example, U.S. Patent No. 5,337,481 to Mears discloses a single-ended utility knife with two blades held in two parallel blade carriers. The two blade carriers can be slid along the longitudinal axis of the housing independently of one another by means of buttons attached to each one of the carriers. The carriers are arranged such that the cutting edges of the blades both face the same long side of the knife. To switch blades the currently extended blade has to be retracted using one button and the other blade needs to be extended using the other button.

U.S. Patent No. 5,230,152 to Kennedy discloses a double-ended utility knife. The knife comprises a pair of blades, with one blade at each end of the knife held in a corresponding blade carrier. The blade carriers form part of an actuator which can be slid along the longitudinal axis of the knife by means of a handle. By operating the actuator one blade can be extended on one side of the knife while at the same time the other blade is retracted from the other side of the knife. The blade carriers are arranged so that the cutting edges of the two blades always face the same long side of the knife. This knife, however, exhibits most of the problems encountered with using to separate knifes. This is because to switch blades the knife must be turned around, and the handle must be operated to retract the first blade and extend the second blade. This procedure generally requires a two-handed operation.

A similar knife is known from U.S. Patent No. 5,093,994 to Karas. In this design the two blades are held in a common blade carrier. The carrier can be slid along the longitudinal axis of the knife by means of a button so that depending on the position of the button either one or the other of the blades can be extended. Again the carrier is constructed so that the cutting edges of the two blades are oriented in the same direction. Changing blades therefore requires the same complicated procedure as with the knife disclosed in U.S. 5,230,152.

From U.S. 4,586,256 to Weimann a one-sided knife with a single blade held in a single blade carrier is known. To switch blades the blade must be fully extended and a tab on the blade carrier must be operated to disengage the blade currently mounted and to replace it with a different blade.

There is thus a need in the prior art for a utility knife that allows use of two different blades without requiring the cumbersome manipulations required by prior art knives during blade changes. The present invention is directed toward meeting this need.

SUMMARY OF THE INVENTION

The present invention relates to a double-ended dual-mechanism retractable blade utility knife. The knife includes two separately actuable mechanisms which allow extension and retraction of one or both blades independently of one another. The cutting surfaces of the respective blades are oriented towards opposite sides of the knife, thereby facilitating rotation of the knife within the user's hand in order to change which blade is currently being used. The independent nature of the dual mechanisms allows both of the blades to be held in the extended position. A storage area is further provided behind each of the mechanisms for the storage of spare blades.

In one form of the invention, a double-ended dual-mechanism retractable blade utility knife is disclosed, comprising a housing; a first blade carrier operative to carry a first blade and to slide along a longitudinal axis of the housing; and a second blade carrier operative to carry a second blade and to slide along the longitudinal axis of the housing; wherein the first and second blade carriers may be slid along the longitudinal axis of the housing independently of one another.

In another form of the invention, a double-sided dual-mechanism retractable blade utility knife is disclosed, comprising a housing; a first blade carrier operative to carry a first blade and to slide along a longitudinal axis of the housing; a first space formed in the housing adjacent the first blade carrier, the first space sized to allow storage of first spare blades; a second blade carrier operative to carry a second blade and to slide along the longitudinal axis of the housing; and a second space formed in the housing adjacent the second blade carrier, the second space sized to allow storage of second spare blades; wherein the first and second blade carriers may be slid along the longitudinal axis of the housing independently of one another; and wherein a first cutting edge of the first blade is positioned on a first side of the longitudinal axis; and wherein a second cutting edge of the second blade is positioned on a second side of the longitudinal axis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of an exterior of the utility knife of the present invention.

FIG. 2A is a side elevational view of an interior of one half of the knife of FIG. 1.

FIG. 2B is a side elevational view of an interior of a second half of the knife of FIG. 1, illustrating the actuation mechanisms.

FIG. 3 is a side elevational view of a blade carrier of the present invention.

FIG. 4 is a side elevational view of the blade carrier of FIG. 3 with a straight razor blade mounted thereon.

FIG. 5 is a cross-sectional view of the utility knife of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1, there is illustrated a first embodiment of the present invention, indicated generally at 10.

The two ends of the utility knife 10 are identical, with one end being inverted about the longitudinal knife axis with respect to the other end. Therefore, identical reference numbers are used herein to denote identical parts, with the suffix "a" or "b" added to denote on which end of the knife 10 the part is located.

With reference to FIGS. 2A-B, the utility knife 10 includes two

mating housing halves

12 and 14 which are held together by a transverse threaded fastener 16 which passes through the hole 18 arid threadably engages the hole 20 which is formed as a portion of the housing half 14. The two

housing halves

12, 14 form a first open channel 22a in which is located a first actuating lever 24a. Movement of the first actuating lever 24a to the left in FIG. 2B causes a first blade (illustrated in phantom at 28) to be extended from a slot formed in the first end 26 of the utility knife 10. The first blade 28 includes a first cutting edge 30 facing downward in FIG. 2B Conversely, movement of the first actuating lever 24a to the right in FIG. 2B causes the first blade 28 to be retracted completely within the housing Similarly, a second open channel 22b is formed by the

mating housing halves

12, 14 transversely and longitudinally opposite from the open channel 22a. A second actuating lever 24b is disposed within the second open channel 22b and is operative to extend a second blade (illustrated in phantom at 34) from an open slot in a second end 36 of the utility knife 10 when the second actuating lever 24b is moved to the right in FIG. 2B. The second blade 34 includes a second cutting edge 31 facing upward in FIG. 2B Movement of the second actuating lever 24b to the left in FIG. 28 operates to retract the second blade 34 completely within the utility knife 10.

Each of the actuating levers 24a and 24b is attached to respective first and second blade carriers 38a and 38b, as illustrated in FIG. 2B. Because the configuration of first blade carrier 38a is identical to the configuration of second blade carrier 38b, such configuration is illustrated in FIGS. 3 and 4 without the use of "a" and "b" suffixes. For example, reference to blade carrier 38 in FIGS. 3 and 4 should be understood to apply to both first blade carrier 38a and second blade carrier 38b. An analogous numbering scheme is used to refer to the elements in FIG. 5 that are common to both the first and second sides of the knife 10. Referring now to FIGS. 3 and 4, the blade carrier 38 is preferably formed from metal and includes raised

transverse surfaces

40, 42 and 44 which operate to limit movement in three directions of a blade 28 mounted thereon (see FIG. 4). Movement of the blade 28 is further prevented by a tab 46 which fits into a notch 48 formed into the blade 28. The blade 28 has two such notches 48 which allow for reversing of the blade 28 within the blade carrier 38 for extended blade life. The blade 28 is of the type standardly used in this art.

Referring once again to FIGS. 2A-B, the first blade-carrier 38a is maintained in a retracted position by engagement of a first tab formed on the first end 50a of the first blade carrier 38a with a first indentation 52a formed in the

housing halves

12, 14. Similarly, the first blade carrier 38a is maintained in an extended position by interaction between the first tab formed on the first end 50a and a second indentation 54a notch 54 formed in the

housing halves

12, 14. The first tab formed on the first end 50a of the first blade carrier 38a is moved from first indentation 52a to second indentation 54a (and vice versa) by depressing the first actuating lever 24a, which causes the first arm 51a to flex, thereby disengaging the first tab formed on the first end 50a from the first and

second indentations

52a, 54a. Engagement of the first tab formed on the first end 50a with the first and

second indentations

52a and 54a therefore operates to securely maintain the first blade carrier 38a (and hence the first blade 28) in either the retracted or extended position.

The second blade carrier 38b is maintained in a retracted position by engagement of a second tab formed on the second end 50b of the second blade carrier 38b with a third indentation 52b formed in the

housing halves

12, 14. Similarly, the second blade carrier 38b is maintained in an extended position by interaction between the second tab formed on the second end 50b and a fourth indentation 54b formed in the

housing halves

12, 14. The second tab formed on the second end 50b of the second blade carrier 38b is moved from third indentation 52b to fourth indentation 54b (and vice versa) by depressing the second actuating lever 24b, which causes the arm second 51b to flex, thereby disengaging the second tab formed on the second end 50b from the third and

fourth indentations

52b, 54b. Engagement of the second tab formed on the second end 50b with the third and

fourth indentations

52b and 54b therefore operates to securely maintain the second blade carrier 38b (and hence the second blade 34) in either the retracted or extended position.

Referring now to the cross-sectional view of FIG. 5, it will be appreciated that when the

housing halves

12, 14 are coupled together, the blade carrier 38 is maintained within a longitudinal sliding track formed by

protrusions

56, 58, 60 and 62 formed integrally with the housing half 12 and by

protrusions

64,66, 68 and 70 formed in the housing half 14. These protrusions from the

housing halves

12, 14 form top and bottom C-channel tracks in which the blade carrier 38 runs. It will be appreciated by those skilled in the art that the exact configuration of such tracks is not critical to the present invention, merely that some means for limiting the motion of the blade carrier 38 be provided within the

housing halves

12, 14.

As best illustrated in FIG. 5, an indentation 72 is formed in the housing half 14 behind the blade carrier 38 in order to provide a space for storage of spare blades 29. The spare blades 29 may be first blades 28 and/or second blades 34, both of which will fit in this storage space. The spare blades 29 are stored in an inverted position as compared to the blade in the blade carrier 38.

The utility knife 10 of the present invention exhibits several advantages over prior art utility knives. First, the utility knife 10 allows independent extension and retraction of two blades. This is a particularly desirable feature when two different blades, such as a straight blade and a hooked blade, need to be used repeatedly during the same project. A further advantage of the dual-mechanism of the utility knife 10 is that it allows the cutting edges 30, 31 of the two

blades

28,34 to be oriented in opposite directions. Such an orientation of the cutting edges 30, 31 facilitates single-handed reorientation of the utility knife 10 in the user's hand in order to position the other blade for use. Such reorientation simply involves rotating the knife in the user's hand about an axis extending through the fastener 16. Such a flipping motion is easily accomplished with one hand. When both

blades

28, 34 are left in the extended position, the user may easily switch between

blades

28,34 by simply rotating the utility knife 10 with a single hand.

By comparison, the prior art double-ended utility knives required that one blade be retracted and the other blade be extended whenever the user desired to switch to the other blade. Furthermore, the cutting edges on the prior art double-ended utility knives face in the same direction, thereby making it extremely difficult to reorient the knife for use with the other end without employing both of the user's hands. Another useful feature of the utility knife 10 of the present invention is the provision of a somewhat wider handle than is customary in such knives, with the inclusion of the cavity 72 behind each blade carrying mechanism which allows for the storage of spare blades 29 on both sides of the knife 10. Not only does this increase the number of spare blades 29 which may be carried in the knife 10, it also facilitates carrying spare blades 29 for both types of blades (e.g. a straight blade 28 and a hooked blade 34).

Claims

A double-ended dual-mechanism retractable blade utility knife (10), comprising:

a housing (12, 14) having a longitudinal axis,

a first blade (28) having a first cutting edge (30),

a second blade (34) having a second cutting edge (31),

first blade carrier means (38a) for carrying the first blade (28) and for sliding along the longitudinal axis of the housing (12, 14), and

second blade carrier means (38b) for carrying the second blade (34) and for sliding along the longitudinal axis of the housing (12, 14),

wherein the first (38a) and second (38b) blade carrier means are adapted to slide along the longitudinal axis of the housing independently of one another, characterised in that
the first (28) and second (34) blades are adapted to be extended in opposite directions.
The utility knife (10) of claim 1, further comprising:

a first space formed in the housing (12, 14) adjacent the first blade carrier means (38a), the first space sized to allow storage of first spare blades (29), and

a second space formed in the housing adjacent the second blade carrier means (38b), the second space sized to allow storage of second spare blades (29).
The utility knife of claim 1 or 2, wherein each of the first (38a) and second (38b) blade carrier means comprise:

a first portion (40, 42, 44, 46) shaped to engage a blade (28, 34) and to prevent relative movement between the first portion (40, 42, 44, 46) and the blade (28, 34) along the longitudinal axis.
The utility knife (10) of claim 3, wherein each of the first (38a) and second (38b) blade carrier means further comprise:

a flexible arm (51) coupled to the first portion (40, 42, 44, 46), and

a tab formed on a distal end (50) of the flexible (51) arm,

wherein the tab engages indentations (52, 54) in the housing which limit travel of the blade carrier (38) along the longitudinal axis.
The utility knife of one of the previous claims, wherein the cutting edges (30, 31) of the two blades (28, 34) are oriented in opposite directions.