Note: Descriptions are shown in the official language in which they were submitted.
CA 02315664 2000-08-14
ADJUSTABLE SAFETY UTILITY KNIFE
BACKGROUND OF THE INVENTION
Field of the Inventio .
The present invention generally relates to hand tools and, more specifically,
to an adjustable safety utility knife.
De-sc-n'ption of the Prior Art.
Utility k-nives are widely used in construction, business and hobby
applications for cutting such materials as paperboard, wallboard, string and
other
objects. Commonly, such utility knives are in the form of an elongate hollow
housing that can be gripped by the user along an intermediate portion thereof
and
into which there are placed ixapezoidal flat cutting blades. The blades
typically
have a single cutting edge. The blade is typically slidably mounted between a
retracted position within the housing. and an extended position in which the
cutting
edge is at least partially exposed through a front end aperture or slot, the
slot being
coupled to a nlanually operated element, such as a button positioned in a
manner
convenient to be actuated by the user's hand.
Many utility knives include a region within the housing for storing one or
two additional blades that can be used to replace the operative blade when it
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CA 02315664 2000-08-14
becomes dull. In most cases a screw or similar means is used for attaching the
two
clam shell members together during normal use. When blades are to be replaced,
the screw is removed, allowing to two shell members to be separated, and
access is
provide to the replacement blades.
The flat cutting blades used in utility knives are most useful and are easiest
to use when the blades are extremely sharp. These blades, therefore, are
frequently replaced once they become dull. For this purpose, known utility
knives
provide storage within the handle for additional blades so that these will be
readily
available when needed. In order to facilitate this replacement procedure, some
utility knives provide a blade holder which stores the plurality of blades and
which
can be quickly and conveniently removed from the utility knife handle.
Also, a number of utility knife designs have been proposed which facilitate
the removal, reversal or replacement blades without separating the mating
handle
parts or shell members.
Further, while the flat cutting blades used in utility knives are relatively
thin, substantially frictional forces are frequently applied to or exerted on
these
blades, such as when the blades are used to cut heavy or thick cardboard,
wallboard or the like. As typically used, the utility knives are placed on the
material to be cut and, with the blade penetrated through the material, and
with the
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CA 02315664 2005-01-07
user's hand extended, the utility knife is pulled toward the user to effect
the cutting. The
frictional forces resulting on the blade are such as to pull on the utility
knife in the opposite
direction, tending to pull the utility knife out of the hand of the user. It
is desirable that the
user continue to maintain a good grip on the utility knife for safety reasons
as well as to
prevent damage to the workpiece being cut. Known utility knives, however, are
typically
made of metallic housings which provide a limited amount of friction between
the exterior
surface of the housing and the user's hand. Attempts have been made to
increase the amount
of friction available for this purpose by texturing the surface by providing
ribs, knurling, etc.
While such textured surfaces have somewhat increased the ability of the user
to grip the
utility knife housing, the greater the surface irregularities to enhance the
gripping action, the
more uncomfortable the knife is to use as any such surface irregularities tend
to penetrate the
skin of the user when the knife is tightly gripped to overcome the pulling
frictional forces on
the blade.
SUMMARY OF THE INVENTION
According to one aspect, there is provided an adjustable safety utility knife
comprising: an elongated ergonomically shaped handle formed of two elongate
shell
members each having a peripheral edge and an outer generally convex surface
and an inner
generally concave surface; fastening means for fastening the shell members at
the peripheral
edges along a vertical parting plane to form an elongated internal cavity, the
handle defining a
front end, a back end and an intermediate portion suitable for being gripped
by a user and also
defining top and bottom surfaces extending along opposite sides of the shell
members along
the peripheral edges, the handle having a slot-like aperture at the front end
substantially
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aligned with the parting plane and dimensioned for passage of a flat cutting
blade
therethrough; guide means within the elongated cavity for guiding the cutting
blade between a
first position for safely storing the blade fully inside the cavity and a
second position for
selectively extending the blade beyond the aperture to expose at least a
portion thereof; a
manually operated button arranged on the top surface and coupled to the guide
means for
selectively moving the blade between the first and second positions, the
handle having a rear
opening at the back end for providing access to the elongated internal cavity;
a carrier frame
having a blade cartridge receiving compartment and dimensioned to be removably
receivable
within the cavity through the rear opening between a retracted position in
which the carrier
frame is fully stored within the internal cavity of the handle end and an
extended position in
which the carrier frame is at least partially moved exteriorly of the back end
to provide access
of the cartridge receiving compartment; and a blade cartridge for storing a
plurality of flat
cutting blades receivable within the blade cartridge receiving compartment,
wherein the
carrier frame has a rear wall that generally conforms with the configuration
of the outer
convex surface of the handle, the rear wall having a rear slot-like aperture
generally parallel
to the parting plane and dimensioned for passage of a flat cutting blade
therethrough.
According to another aspect, there is provide an adjustable safety utility
knife
comprising: an elongated ergonomically shaped handle formed of two elongate
shell
members each having a peripheral edge and an outer generally convex surface
and an inner
generally concave surface; fastening means for fastening the shell members at
the peripheral
edges along a vertical parting plane to form an elongated internal cavity, the
handle defining a
front end, a back end and an intermediate portion suitable for being gripped
by a user and also
defining top and bottom surfaces extending along opposite sides of the shell
members along
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the peripheral edges, the handle having a slot-like aperture at the front end
substantially
aligned with the parting plane and dimensioned for passage of a flat cutting
blade
therethrough; guide means within the elongated cavity for guiding the cutting
blade between a
first position for safely storing the blade fully inside the cavity and a
second position for
selectively extending the blade beyond the aperture to expose at least a
portion thereof; a
manually operated button arranged on the top surface and coupled to the guide
means for
selectively moving the blade between the first and second positions, the
handle having a rear
opening at the back end for providing access to the elongated internal cavity;
a carrier frame
having a blade cartridge receiving compartment and dimensioned to be removably
receivable
within the cavity through the rear opening between a retracted position in
which the carrier
frame is fully stored within the internal cavity of the handle end and an
extended position in
which the carrier frame is at least partially moved exteriorly of the back end
to provide access
of the cartridge receiving compartment; and a blade cartridge for storing a
plurality of flat
cutting blades receivable within the blade cartridge receiving compartment,
wherein the
carrier frame is totally removable from the handle.
According to a further aspect, there is provided an adjustable safety utility
knife
comprising an elongated ergonomically shaped handle formed of two elongate
shell members,
each having a peripheral edge and an outer convex surface and an inner
generally concave
surface. Fastening means is provided for fastening such shell members at the
peripheral edges
along a vertical parting plane to form an elongated internal cavity. The
handle defines a front
end, a back end and an intermediate portion suitable for being gripped by a
user and also
defining top and bottom surfaces extending along opposite sides of the front
end substantially
aligned with the parting plane and dimensioned for passage of a flat cutting
blade
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therethrough. Guide means is provided within the elongated cavity for guiding
the cutting
blade between a first position for safely storing the blade fully inside the
cavity and a second
portion for selectively extending the blade beyond the aperture to expose at
least a portion
thereof. A manually operated button is arranged on the top surface and coupled
to the guide
means for selectively moving the blade between the first and second positions.
The guide
means includes a carriage within the elongated internal cavity for supporting
a flat cutting
blade and guide elements are provide on at least one of the inner generally
concave surfaces
for guiding the carriage or cutting blade carrier between the first and second
positions. The
carriage includes locking means for normally locking a cutting blade mounted
thereon to
substantially fix the cutting blade against relatively longitudinal movements
between the
cutting blade and the carriage. The locking means also includes an unlocking
element, the
actuation of which releases a cutting blade to permit relative longitudinal
movements between
the cutting blade and the carriage. Blade release means is provided on one of
the shell
members for actuating the unlocking element when manual force is applied
thereto.
Therefore, application of a force on the blade release means releases the
cutting blade and
enables it to be withdrawn through the end aperture.
In accordance with yet another aspect, there is provided an adjustable safety
utility
knife comprising an elongated ergonomically shaped handle formed of two
elongate shell
members, each having a peripheral edge and an outer convex surface and an
inner generally
concave surface. Fastening means is provided for fastening such shell members
at the
peripheral edges along a vertical parting plane to form an elongated internal
cavity. The
handle defines a front end, a back end and an intermediate portion suitable
for being gripped
by a user and also defining top and bottom surfaces extending along opposite
sides of the
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front end substantially aligned with the parting plane and dimensioned for
passage of a flat
cutting blade therethrough. Guide means is provided within the elongated
cavity for guiding
the cutting blade between a first position for safely storing the blade fully
inside the cavity
and a second position for selectively extending the blade beyond the aperture
to expose at
least a portion thereof A manually operated button is arranged on the top
surface and
coupled to the guide means for selectively moving the blade between the first
and second
positions. Slip resistant means is provided secured to the shell along the top
and bottom
surfaces between a rearmost operative position of the manually operated button
and the back
end. Such slip resistant means generally conforms to the outer convex surface
and enhances
gripping of the handle and minimizes slippage of the handle during use of the
utility knife
when gripped by a user.
BRIEF DESCRIPTION OF THE DRAWINGS
Other aspects, objects and advantages of the present invention will become
apparent
upon reading of the following detailed description of a preferred embodiment
of the present
invention when taken in conjunction with the drawings as follows:
Fig. 1 is a side elevational view of an adjustable safety utility knife with
an
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CA 02315664 2000-08-14
easily removable blade holder in accordance with the present invention;
Fig. 2A is a cross-sectional view of the utility knife shown in Fig. l, taken
along line 2-2, shown with the blade holder and carriage therein in the fully
retracted position;
Fig. 2B is similar to Fig. 2A except that the blade holder is shown in its
fully extended position in condition for removal of a blade from the
cartridge;
Fig. 3 is an enlarged side elevational view of the blade holder shown in
Figs. 2A and 2B, showing a cartridge positioned within the blade holder when
there are no blades within the cartridge;
Fig. 4 is a side elevational view of the front-loading adjustable safety
utility
knife in accordance with the present invention with the front portion of the
housing broken away to show the safety quick-release lock mechanism in
accordance with the invention;
Fig. 5A is a cross sectional view of the front portion of the utility knife
shown in Fig. 4 taken along line 5A-5A;
Fig. 5B is similar to Fig. 5A, but illustrating the condition of the elements
or
components of the quick-release lock mechanism when an external force is
applied
to the quick-release button, such as by a finger of the user;
Fig. 6 is an enlarged side elevational view of the blade supporting carriage
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illustrated in Figs. 4, 5A and 5B, shown in the normal condition when no force
is
applied to the upper button which unlocks the carriage from moving inwardly or
outwardly along the handle within the cavity;
Fig. 7 is a side elevational view of an adjustable safety utility knife with
slip
resistant elements in accordance with the invention; and
Fig. 8 is a cross sectional view of the utility knife shown in Fig. 7, taken
along line 8-8.
DESCRIPTION OF A PREFERRED EMBODIMENT
Referring now to the figures, in which identical or similar parts are
designated by the same reference numerals throughout, and first referring to
Fig. 1,
an adjustable safety utility knife in accordance with the present invention is
generally designated by the reference numeral 10.
The utility knife 10 includes an elongated ergonomically shaped handle 12
formed of two elongate shell members 14a, 14b, each having a peripheral edge
16a, 16b, respectively, and outer generally convex surfaces 18a, 18b, and
inner
generally concave surfaces 20a, 20b, respectively. A suitable fastener, such
as a
hansverse screw 22 (Fig. 1) is provided for fastening the shell members 14a,
14b
to each other at the peripheral edges 16a, 16b along a vertical parting plane
P-
(Fig. 2) to form an elongated internal cavity or compartment 24. The handle 12
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defmes a front end 26, a back end 28 and an intermediate portion 30 suitable
to be
gripped by the user, and also defmes top and bottom surfaces 32, 34,
respectively.
Top and bottom surfaces extend along the top and bottom surfaces of the shell
members 14a, 14b along the peripheral edges. The handle 12 has a conventional
slot-like aperture 36 (Fig. 1) and a front end 26 substantially aligned with
the
parting plane P and dimensioned for passage of a flat cutting blade 38
therethrough. A guide member, in the form of a cartridge 39, is provided
within
the cavity 24, in the front end 26 for guiding the cutting blade 38 between a
first
portion for safely storing the blade 40 inside of the cavity and a second
position
for selectively extending the blade beyond the aperture 36 for exposing a
portion
thereof, as shown in Fig. 1.
A manually operated button 40, of the type frequently used in utility knives,
is arranged on the top surface 32 and coupled to the guide element for
selectively
moving the blade 38 between the first and second positions.
Slip resistant elements 42, 44 are provided and arranged on the top and
bottom surfaces 32, 34, respectively. The elements generally conform to the
outer
convex surfaces 18a, 18b and enhance the gripping action of the handle 12 and
mininaize slippage of the handle during use.
As the shell members are fastened together by means of a single fastener in
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the nature of a screw 22, the shell members are preferably provided with one
or
more cutouts or recesses in one of the shell members and extensions in the
other
shell member that mates therewith. In the embodiment illustrated in Fig. 1,
the
shell member 14a is provided at the front end 26 thereof with upper and lower
recesses or cutouts R1, R2 that receive transverse extensions El, E2 that are
integraliy formed on the opposing she11 member 14b. It will be appreciated
that
when the recesses and extensions mate and interlock as shown, it will be clear
that
the shell members will not have a tendency to pivot or shift in relation to
each
other.
The blade guide or carriage 39 is mounted on suitable guide surfaces (not
shown) for guiding the cutting blade between a first retracted position for
storing
the blade fully inside the cavity and a second position for selectively
extending the
blade beyond the aperture 36 to expose at least a portion thereof, as shown in
Fig.
1.
The manually operated button 40 is arranged on the top surface 32 and
coupled to the guide element 39 for selectively moving the blade between the
fi,rst
and second positions.
Referring to Figs. 1, 2A and 2B, the handle 12 has a rear opening at the
back end 28 for providing access to the elongated internal cavity 24. The
opening
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CA 02315664 2000-08-14
is formed by a recess R3 which removes the rear part of the shell 18a up to
the
vertical edge R3' (Fig. 2B), retaining an arcuate or curved surface 12n which
forms part of the back end of the shell member 18b, as best shown in Figs. 2A
and
2B. A canrier frame is generally designated by the reference numeral 50, which
has a blade receiving compartment 50' and is dimensioned to be rernovably
receivable from within the cavity 24 through the rear opening between a
retracted
position as shown in Fig. 2A, in which the carrier frame 5.0 is fully stored
within
the Ynternal cavity 24 of the handle and an extended position shown in Fig. 2B
in
which the carrier frame 50 is at least partially moved exteriorly of the back
end to
provide access to the cartridge receiving compartment. A blade cartridge 52 is
provided which is slidably receivable within the carrier frame for storing a
plurality of flat cutting blades 38 receivable within the blade cartridge
receiving
compartment 50', each of the blades being fully removable through a rear slot
formed by a camier frame slot 50b and cartridge slot 52 that are aligned with
each
other as best shown in Figs. 2A and 2B.
The carrier frame 50 includes an arcuate portion having a curved surface
50a that generally conforms with the arcuate curved surface 12n (Fig. 2A) of
the
handle so that when the carrier frame is within the cavity 24 the exterior
surfaces
50a, 12n of the carrier frame and the back of the handle blend to provide a
unitary
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shape or appearance. A generally vertical slot 50b is provided in the arcuate
surface or wall 50a.
The carrier frame has a lateral wall 50c, most proximate to the shell member
18b, and an opposing waIl 50d which is substantially in line or co-planar with
the
wall of the shell member 18a, an outwardly directed tapered hook being formed
at
the end of a rearwardly projecting tab 50g.
At the end of the carrier frame 50 remote from the curved surface 50a there
is provided a rear wall 50h which includes a vertical tab 50i on the exterior
surface
of which there is provided a tapered projection 50j. The projection 50j
becomes
operative when the carrier is moved from its retracted to its extended
positions
shown in Fig. 2B, the projection 50j sezving as a limit stop by engaging a
positioning rib 12d formed on the shell member 18a. A similar vertical
projection
12e is provided on the inside surface 20b of the shell member 18a to serve as
a
positioning member for maintaining the lateral position of the carrier frame
within
the cavity 24. Thus, in its extended position the projection 50j engages the
vertical rib 12d, while movement of the carrier frame interiorly to its fully
retracted position causes the tapered hook 50f to engage a tapered projection
12h
formed on the inner surface 20a of the shell member 18a, as best illustrated
in Fig.
2A.
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Slits 50e provided above and below the wall extension 50g render the wall
50d more flexible in the intermediate region thereof, facilitating the
depression or
deflection of the wall extension 50g when the carrier frame needs to be
removed.
By pressing on the wa1150d, substantially at the center thereof, the tapered
hook
50f clears the tapered projection 12h to allow the carrier frame to slide out
from
with the housing of the handle, as shown in Fig. 2B.
A cartridge 52 that contains the cutting blades is generally designated by the
reference numeral 52. In order to substantially fix the position of the
cartridge 52
within the carrier frame 50 during normal operation, a number of features are
provided that secure the cartridge against movements relative to the carrier
frame.
Thus, inclined edges 52a on the cartridge are received within corresponding
inclined indentations or recesses 50k within the inside surface 20b of the
shell
member 18b. Additionally, an upwardly extending limit tap 52b is provided on
the cartridge which abuts against the inner surface of the upper end of the
inclined
surface 50a of the carrier frame, as shown in Fig. 3. Also, formed on the
bottom
wall 52c of the cartridge there is advantageously provided a lateral li.mit
tab 52d
which abuts against the inner surface of the wall 50d, to prevent undesired
lateral
movements and to ensure alignment of the slot 52s in the rear wall 52w with
the
slot 50b in the carrier frame. In order to further ensure the positional
stability of
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CA 02315664 2000-08-14
the unit during nornial use, the cartridge is preferably with a rear wa1152q
that
generally conforms to the interior surface or shape of the rear wall 50h of
the
carrier frame member, which permits the two aforementioned components to be
separated only by a relative sliding downward movement of the cartridge in
relation to the carrier frame, as best shown and suggested by the arrow M in
Fig. 3.
An additional positioning wall 50y is advantageously provided that extends
downwardly as shown in Fig. 3 to capture the wall 52q of the cartridge. With
this
construction, therefore, the cartridge is fully captured within the carrier
frame and
shares all linear, slid.ing movements therewith as the carrier frame is
extended and
retracted into the handle.
Mounted on the inside surface of the wa1152e of the carlridge 52,
substantially centrally of the longitudinal length of the cartridge, there is
provided
a retaining standoff 52h to each lateral side of which there are provided
vertical
ribs 52f, 52g as shown in Figs. 2A and 2B. A leaf spring 54 has a central
portion
thereof captured between the retaining standoff 52h and the wall 52e and is
prevented from shifting laterally by the vertical ribs 52f, 52g. The leaf
spring 54
has two lateral spring members or wings which are bent forwardly towards an
opening 52i in the wa1152j of the cartridge. It will be clear that insertion
of
cutting blades 38 within the cartridge, as shown, will be urged or biased
towards
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the opening 52i by means of the leaf spring, so that if there are any blades
within
the cartridge, one of these blades will be in abutment against the wall 52j
and
accessible for finger contact through the opening 52i.
While the longitudinal length of the inner cartridge is substantially equal to
the maximum dimension of the blades, the blades are prevented from shifting
within the cartridge by means of a movable tab 50k provided at the top of the
cartridge which is hinged, such as by a plastic hinge 50m at one end and
having a
downwardly directed right angle finger 50n dimensioned to be received within a
conventional open notch at the upper edge of the cutting blade. When the
assembly of the carrier frame and the cartridge are inserted into the handle,
the tab
50k is automati.cally forced downwardly by the inside surface 12y (Fig. 1) of
the
shell members, causing the finger 50n to be moved into one of the notches of
the
blade(s) thereby maintaining all of the blades in alignment within the
cartridge_
'PVhen a blade is removed from the cartridge and the carrier frame is
withdrawn or
brought to its extended position shown in Fig. B, the movable tab 50k clears
the
surface 12y and the tab is resiliently lifted to the position shown in Fig.-
3, clearing
the notches and allowing a blade to be removed from the cartridge. If the
cartridge
is not made from a plastic material to allow use of a plastic hinge, the tab
50k may
also be mounted using a standard hinge and a suitable spring may be used to
urge
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the tab to go to the position shown in Fig. 3.
In use, when a blade needs to be extracted or removed from the cartridge,
the wall 50d is initially manually pressed inwardly, allowing the tapered hook
50f
to clear the tapered projection 12h. This permits the carrier frame to be
moved
outwardly until the tapered projection 50j comes into abutment with the
positioning rib 12d. In this position, the opening or window 52i, concealed
when
in the retracted position shown in Fig. 2A, becomes exposed and a user may,
using
his or her fmger, contact the outermost blade that abuts the wall 52j of the
cartridge and slide the blade rearwardly through the aligned slots 52s and 50b
to
extract the blade. When removal is completed, the carrier frame may be slid
back
into the housing of the handle 12 to the position shown in Fig. 2A, at which
point
the carrier frame becomes locked within the handle by means of the tapered
hook
50f and the tapered projection 12h.
It will be noted from the foregoing that the removable blade holder in
accordance with the invention ensures that the blades are always securely
stored
within the holder and within the cartridge, the possibility of blades
inadvertently
falling out of the unit being extremely remote because of the dual encasement
construction. Also, the removal of the blades is easy and convenient. Because
there is a separate blade cartridge 52, individual blades need not be handled
when
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the blades are inserted into the unit for future use. The cartridge 52 is,
preferably,
supplied to the user as a pre-packaged unit so that the cartridge can simply
be
inserted and snapped into place without ever touching the blades. Inadvertent
opening of the blade compartment is, therefore, virtually inipossible. The
resulting design is, therefore, extremely safe to use and virtually child-
proof. As indicated, even if the carrier frame is withdrawn, this would not
expose the
dangerous cutting edges of the blades. The additional step of manually sliding
a
blade, through the opening or window 52i, would need to be taken to remove the
blade from the cartridge.
The utility knife 10 includes an elongated ergonomically shaped handle 112
formed of two elongate shell members 114a, 114b, each having a peripheral edge
116a, 116b, respectively (Fig. 5), and outer, generally convex surface 118a,
118b
and an inner generally concave surface 120a, 120b, respectively. A suitable
fastener, such as a transverse screw 122 (Fig. 4) is provided for fastening
the shell
members 114a, 114b to each other at. the peripheral edges 116a, 116b (Figs.
5A,
5B) along a vertical parting plane P (Fig. 5) to form an elongated internal
cavity or
compartment 124. The handle 112 defines a front end 126, a back end 128 and an
intermediate portion 130 suitable to be gripped by the user, also defining top
and
bottom surfaces 132, 134, respectively, extending along the tops and bottom
sides
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of the shell members 114a, 114b along the peripheral edges. The handle 112 has
a
conventional slot-like aperture 136 (Fig. 4) and a front end 126 substantially
aligned with the parting plane P and dimensioned for passage of a flat cutting
blade 138 therethrough. A guide IIiember, in the form of a carriage 139, is
provided within the cavity 124, in the front end 126, for guiding the cutting
blade
138 between a first position for safely storing the blade 140 inside of the
cavity
and an extended second position for selectively extending the blade beyond the
aperture 136 for exposing a portion thereof, as shown in Fig. 4. A manually
operated button 140, of the type frequently used in utility knives of this
kind, is
arranged on the top surface 132 and coupled to the guide element or carriage
139
for selectively moving the blade 138 between the first and second positions.
Slip resistant elements 142, 144 are secured between the shell members or
the top and bottom surfaces 132, 134, respectively, between a rearwardmost
operative position of the manually operative button and the back end 128. The
slip resistant elements 142, 144 generally conform to the outer convex surface
118a, 118b and enhance the gripping of the handle 112 and minimize slippage of
the handle during use of the utility knife when gripped by the user.
As the shell members are fastened together by means of a single screw 122,
the shell members are preferably provided with one or more cutouts or recesses
in
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one of the shell members and extensions in the other shell member that mate
therewith. In the embodiment illustrated in Fig. 4, the shell member 114a is
provided at the front end 126 thereof with upper and lower recesses or cutouts
R1,
R2 that receive transverse extensions E1, E2 which are integrally formed on
the
opposing shell member 114b. It will be appreciated that when the recesses and
extensions mate and interlock as shown, it will be clear that the shell
members will
not have a tendency to rotate or shift in relation to each other.
The blade guide element or carriage is mounted on suitable guide surfaces
112a, 112b for guiding the cutting blade between a first position for safely
storing
the blade fully inside the cavity 124 and a second position for selectively
extending the blade beyond the aperture 136 to expose at least a portion
thereof, as
shown in Fig. 4.
The manually operated button 140 is arranged on the top surface 132 and
coupled to the guide element or carriage for selectively moving the blade
between
the first and second positions.
Referring to Fig. 4, the housing is shown broken away to illustrate the
general position of the blade guide member or carriage 139 within the
elongated
internal cavity 124 for supporting the flat cutting blade. Guide surfaces
112a,
112b (Fig. 4) are provided on at least one of the inner generally concave
surface
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120a, 120b for guiding the carriage 139 and cutting blade between the first
and
second or extended and retracted positions. A plurality of teeth 1 12c (Fig.
4) are
provided along the longitudinal length direction DI of the front end of the
housing
112, the teeth being shown arranged along a straight or linear path for
reasons to
be more fully apparent hereafter.
Referring to Figs. 5A, 5B and 6, the details of the carriage 139 for enabling
the safe, quick release of the blade 134 will be described. The carriage
includes a
substantially planar body 139a (Fig. 6), preferably formed of a metal,
although
other materials may be used. Spaced ribs or ledges 139b, 139c are generally
aligned with each other as shown, and define a generally rectangular opening
or
space 139d within the body 139a. A lower ledge or rib 139d is provided which
is
parallel to the ribs 139b, 139c, and the opposing ribs are spaced from each
other to
substantially correspond to the height of the blade 138 so that the blade can
be
received between the opposing ribs witb small clearance. While the ribs 139b -
139d project towards the shell 118a (out of the paper, as viewed in Fig. 6),
the
body 139a is provided with spaced and substantially parallel projections 139g
and
139h which extend towards the shell member 118b (into the page, as viewed in
Fig. 6). The projection 139g includes an opening 139i and the projection 139h
includes an opening 139j to accommodate the stem 140b on which the button 110
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is supported to enable the button and the stem to move vertically in relation
to the
body 139a. A helical compression spring 146, captured between the projections
139g, 139h, normally urges the button and stem to move upwardly in relation to
the body 139a, bringing mating teeth 140c on the stem 140b to be generally
aligned and interlock with the teeth 112c on the housing of the handle 112.
When
so engaged or interlocked, the body 139a becomes locked in place and cannot
move forwardly or rearwardly in relation to the handle. However, when the
button
110 is depressed inwardly, the teeth 140c are moved downwardly in relation to
the
teeth 112c and the interlocking relationship is disrupted so that the user can
slide
the carriage 139 forwardly or rearwardly on the guides 112a, 112b.
A pawl 148 is provided with a verticaI cylindrical boss 148a through which
a vertical pin 150 extends between the projections 139g and 139h to render the
paw1148 pivotable about the axis A of the pin. The pawl includes a front
portion
148b forwardly of the pin 150 and a rear portion 148c, rearwardly of the pin
150.
A compression spring 152 is disposed between the body 139a and thc rear
portion
148c to normally rotate the pawl 148 in a counterclockwise direction when the
camiage is viewed from the top. Such normal disposition of the pawl ntaintains
a
right angle finger 148d extending through the opening 139d a distance
sufficient
to engage one of the notches 138a, 138b formed in the upper edge of the blade
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138. The finger 148d, therefore, normally locks the blade from moving in
relation
to the carriage.
As indicated, therefore, the right angle finger 148d, vvhich is in the nature
of
a lock or blocking element normally locks the cutting blade mounted thereon to
substantially fix the cutting blade against relative longitudinal movements
between the cutting blade and the carriage.
Referring to Figs. 5A and 5B,.a quick release mechanism 154 is illustrated
on the shell member 118b. The quick release mechanism 154 includes a pin 156
extending through an opening 112c in the shell member 118b, the pin 156 being
slidably mounted along a direction generally normal to the axis A of the pin
150.
A cap or button 158 is provided which covers the pin 156 and is provided with
an
exterior shape or configuration suitable for manual depression. The pin 156
may
be secured to the wall of the shell member 118b in any suitable or
conventional
manner, washer 160 being shown, the end of the pin 156 extending inwardly
beyond the washer 160 being enlarged in any conventional way, such as by
flaring, to pern:fit the pin to move inwardly into the cavity but not to
permit the pin
from moving outwardly beyond the condition indicated in Figs. 5A, 5B. The axis
B of the pin 156 is preferably aligned with the spring 152, the interior end
of the
pin 156 and spring 152 being arranged on opposite sides of the rear portion
148c
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CA 02315664 2000-08-14
of the paw1148. Thus, when no exterior pressure is applied to the cap 158 and
pin
156, the compression spring 152 is selected to be sufficiently strong to
rotate the
pawl 148 in a counterclockwise direction, as viewed in Fig. 5A, so that the
locking
finger 148d is received within an upper notch of the blade 138, while the pin
156
and cap 158 are urged outwardly to the maximum extent permitted by the washer
160. However, when it is desired to remove the blade 138 through the front
opening or aperture 136, the user presses the quick release cap 158, thereby
overcoming the forces exerted by both the springs 152 and 162, thereby
rotating
the pawl 148 in a clockwise direction, as viewed in Fig. 5A, to the condition
shown in Fig. 5B, in which the locking finger 148d is removed or extracted
from
the upper notch of the blade 138. Under this condition, there is nothing
retaining
the blade 138 from movement in relation to the carriage 139 and the blade may
be
easily and conveniently pulled forwardly out of the utility knife housing. The
same procedure can be applied for inserting a new blade. As long as the cap
158
is maintained in a depressed position, by applied of force F, the locking
finger
148b is displaced from its normal position and provides a clear path for the
blade
to be either inserted or withdrawn. Once the blade is inserted into the unit,
the cap
158 may be released and the blade locked in place as illustrated in Fig. 5A.
It will be appreciated that the above described quick release mechanism 154
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overcomes the difficulty with some prior art designs in which all of the
components or elements used to provide some of the functions described above
are
separable. Therefore, when the shell members 118a, I 18b are removed or
separated, the numerous components, including the springs, all separate and it
becomes very difficult to reassemble the elements in a way that makes them
readily functionable. With the present design, the carriage 139 is made as a
single
unitar y unit, all of the components described, with the exception of the
release
mechanism or button 154, are all mounted on the body 139a of the canriage 139.
Therefore, if the shell members 118a, 118b are separated, it becomes a simple
matter to simply reposition the body 139a on the guide ledges 112a, 1 12b and
the
unit can be quickly and conveniently reassembled since all of the springs, the
pawl, etc., are all permanently mounted on the body 139a.
The utility knife 10 includes an elongated ergonomically shaped handle 212
formed of two elongate shell members 214a, 214b, each having a peripheral edge
216a, 216b, respectively, and outer, generally convex surface 218a, 218b and
an
inner generally concave surface 220a, 220b, respectively. A suitable fastener,
such as a transverse screw 222 (Fig. 7) is provided for fastening the shell
members
214a, 214b to each other at the peripheral edges 216a, 216b along a vertical
parting plane P (Fig. 8) to form an elongated internal cavity or compartment
224.
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The handle.212 defines a front end 226, a back end 228 and an intermediate
portion 230 suitable to be gripped by the user, also defining top and bottom
surfaces 232, 234, respectively, extending along tops and sides of the shell
members 214a, 214b along the peripheral edges. The handle 212 has a
conventional slot-like aperture 236 (Fig. 7) and a front end 226 substantiaiiy
aligned with the parting plane P and dimensioned for passage of a flat cutting
blade 238 therethrough. A guide member, in the form of a carriage 238, is
provided within the cavity 224, in the front end 226 for guiding the cutting
blade
238 between a first portion for safely storing the blade 240 inside of the
cavity and
a second position for selectively extending the blade beyond the aperture 236
for
exposing a portion thereof, as shown in Fig. 7. A manually operated button
240,
of the type frequently used in utility knives of this kind, is arranged on the
top
surface 232 and coupled to the guide element for selectively moving the blade
238
between the first and second positions.
In accordance with an important feature of the present invention, slip
resistant elements 242, 244 are provided and arranged on the top surface 232
and
coupled to guide mechanism for selectively moving the blade 238 between the
first and second positions.
A feature of the present invention is the provision of the slip resistant
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elements 242, 244 secured between the shell members or the top and bottom
surfaces 232, 234, respectively, between a rearwardmost operative position of
the
manually operative button and the back end 228. The slip resistant elements
242,
244 generally conform to the outer convex surface 218a, 218b and enhance the
gripping of the handle 212 and minimize slippage of the handle during use of
the
utility knife when gripped by the user.
As the shell members are fastened together by means of a single screw 222,
the shell members are preferably provided with one or more cutouts or recesses
in
one of the shell members and extensions in the other shell member that mate
therewith. In the embodiment illustrated in Fig. 7, the shell member 214a is
provided at the front end 226 thereof with upper and lower recesses or cutouts
Ri,
R2 that receive transverse extensions El, E2 which are integrally formed on
the
opposing shell member 214b. It .will be appreciated that when the recesses and
extensions mate and interlock as shown, it will be clear that the shell
members will
not have a tendency to rotate or shift in relation to each other.
The blade guide element or carriage 239 is mounted on suitable guide
surfaces (not shown) for guiding the cutting blade between a first position
for
safely storing the blade fully inside the cavity 224 and a second position for
selectively extending the blade beyond the aperture 236 to expose at least a
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portion thereof, as shown in Fig. 7.
The manually operated button 240 is arranged on the top surface 232 and
coupled to the guide element or carriage for selectively moving the blade
between
the first and second positions.
Slip resistant elements 242, 244 are secured to the shell members 214a,
214b along the top and bottom surfaces between a rearwardmost operative
position of the manually operated button 240 and the back end, the slip
resistant
elements 242, 244 generally conforming to the outer convex surface of the
handle
housing and enhance the gripping by the user of the handle and minimize
slippage
of the handle during use of the utility knife when gripped by a user.
Preferably, the slip resistant elements 242, 244 are formed of an elastomeric
or rubber-like material.
The specific manner of attaching the slip resistant elements 242, 244 to the
handle 212 is not critical, and any suitable or conventional method of
attaching
same to the handle may be used. Referring to Fig. 8, however, one presently
preferred embodiment is illustrated in which the slip resistant elements 242,
244
are generally in the form of rectilinear strips having first and second
predetermined lengths Li, L2 along the top and bottom surfaces, respectively.
The peripheral edges along each of the predetermined lengths of the top and
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bottom surfaces have generally U-shaped offsets to each side of the parting
plane
P which together form a generally elongate rectangular opening defining
opposite
edges 246a, 246b that are generally parallel to the parting plane. Each slip
resistant element 242, 244 has dimensions substantially corresponding to an
associated rectangular opening and has opposite lateral grooves 242a, 242b
arranged to receive associated edges 246a, 246b in a tongue-and-groove
configuration to secure each strip within an associated opening in the handle
housing.
While it is not critical, the predetermined lengths Ll and L2 need not be
equal to each other. However, in the preferred embodiment they are
approximately equal to each other to provide the user with a substantial
gripping
area.
Each of the slip resistant elements is formed so as to enhance the gripping
action. Thus, the elements are preferably provided with external grip
enhancing
protuberances. In the embodiment shown, such protuberances are in the form of
a
plurality of transverse ribs that extend in a direction generally normal or
transverse
to the parting plane P.
As best shown in Fig. 7, the handle 212 is formed of forward and rearward
handle portions, each of which is substantially straight and defines a
longitudinal
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direction, directions D21 and D22, as indicated in Fig. 7. The longitudinal
directions are slightly angularly offset from each other, the slip resistant
material
being placed on a substantial length of the rear handle portion. Towards that
end,
each of the slip resistant elements preferably protrudes slightly beyond the
top and
bottom surfaces to provide a positive grip with the hand of the user. In the
embodiment shown, such slip resistant strips form generally outwardly shaped
arcuate profiles along the longitudinal directions of the handle. The specific
shape
and surface texture, however, is not critical. Thus, for example, the slip
resistant
elements may also be formed of a foam-like material of sufficient density to
withstand significant squeezing action or pressures applied thereon.
The handle 212 is also shown in Fig. 7 to include a channel C proximate to
the front end 226 and along the bottom surface 234 which can be used to cut
filamentary material such as string or rope, even when the blade 238 is fully
retracted, as the edge continues to rotate relative to each other.
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