Note: Descriptions are shown in the official language in which they were submitted.
CA 02493970 1999-12-28
SURFACE CONFORMING SHAVING RAZOR AND HANDLE THEREFOR
This application is a divisional of copending commonly owned Canadian Patent
Application No.
2,357,976 of December 28, 1999.
BACKGROUND OF THE INVENTION
The invention relates to a shaving razor that conforms to the surface being
shaved.
Shaving razors typically have straight cutting edges, while the surfaces being
shaved have varying
degrees of flatness or curvature and varying abilities to deform to provide a
flat surface for the straight edge
of the razor. Shaving an area of the body with pronounced curvature, e.g., an
ankle or knee, using a razor
having a straight cutting edge results in a localized area of contact. This
requires repeated strokes to shave
the entire area, and causes a high stress concentration at the localized area
of contact, which can increase the
possibility of a nick or cut at that area.
In accordance with the parent application, the invention defined therein may
be considered to be a
shaving razor which comprises: a handle; first, second and third blade units
that are mounted at one end of
the handle, each blade unit including a guard, at least one blade having a
cutting edge, and a cap; and a
mounting structure connecting each blade unit to the handle, the mounting
structure providing a pivotal
connection of the blade unit to the mounting structure about a pivot axis that
is transverse to the cutting edge,
and also providing up and down movement of the blade unit along a displacement
direction that is transverse
to a plane through the guard and the cap, thereby permitting each blade unit
to conform to the contour of a
surface being shaved.
Preferably, the first, second and third blade units each have a width that is
less than the entire width
covered by all three blades, and the cutting edges of the blade units
partially overlap each other as to avoid
gaps between blade units during shaving. Preferably, as well, the cutting
edges of the blades of the first and
second blade units are generally aligned with each other and have a gap
between them, and the third blade
unit is offset with respect to the first and second blade units, with its
blade overlapping the gap during all
positions of the pivoting and up and down movement.
Preferably, the mounting structure for each blade unit is independent of
mounting structures for the
other blade units, permitting each blade unit to pivot about a respective
pivot axis and to be displaced along
a respective displacement axis independent of the pivoting and displacement of
the other blade units.
CA 02493970 1999-12-28
SUMMARY OF THE INVENTION
On the other hand, the present invention may be broadly considered as
providing a shaving razor
which comprises: a handle; a blade unit that is mounted at the end of said
handle and includes a guard, at
least one blade having a cutting edge, and a cap; and a parallelogram, four-
bar linkage connecting the blade
unit to the handle. The linkage is made of an integral plastic piece and
includes two elongated members, a
proximal end member connected to the handle, and a distal end member connected
to the blade unit. Each
elongated member is pivotally connected via resilient first living hinges at
respective ends to the proximal
end member and the distal end member, the first living hinges providing up and
down movement of the blade
unit along a displacement axis that is transverse to a plane through the guard
and cap.
Embodiments of the invention may include one or more of the following
features. The razor may
include first, second and third blade units, with the mounting structure for
each blade unit being independent
of mounting structures for the other blade units, permitting each blade unit
to pivot about a respective pivot
axis and to be displaced along a respective displacement axis independently of
the pivoting and displacement
of the other blade units. The integral plastic piece of the four-bar linkage
has an at rest position in which the
elongated members are spaced from each other and a stop position in which the
elongated members contact
each other, and the piece is resiliently deformed at living hinges to provide
a force resisting movement from
an at rest position to a stop position, the blade unit moving up and down
along the displacement axis as the
elongated members move toward and away from each other. The mounting structure
has a second living
hinge providing pivoting about the pivot axis, the second living hinge being
resiliently deformed to provide
a force resisting pivoting about the pivot axis from a neutral position.
Planes through the guards and caps
of the blade units are generally coplanar when in an at rest position with
respect to the displacement axis and
at a neutral position with respect to the pivot axis. The cutting edges of
blades of the first and second units
are generally aligned with each other and have a gap between them, and a third
blade unit is offset with
respect to the first and second blade units, with its blade overlapping the
gap during all positions of pivoting
and up and down movement. The blades of the blade units are between'/4"
and'/4" long (preferably between
3/s" and s/e" long, and most preferably about'h" long). The blade units are
mounted to resist displacement
from an at rest position with a spring constant of between 5 and 30
(preferably between 10 and 29, and most
preferably about 15) gm force/mm . The blade units are mounted to resist
pivoting about the pivot axis from
the neutral position with a spring constant of between 3 and 20 gram-
millimeters/radian. The plastic of the
mounting structure is an elastomeric polymer, preferably a polyethylene block
amide available under the
PEBAX trade designation. The integral plastic piece is between 0.008 to 0.018
inch thick (preferably 0.012
to O.OI4 inch) at the living hinges providing the up and down movement. The
integral plastic piece is
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CA 02493970 1999-12-28
between 0.006 to 0.014 inch thick (preferably 0.009 to 0.011 inch) at the
living hinge providing pivoting.
The mounting structure can also provide pivoting about an angle parallel to
the cutting edge. The mounting
structure can be mounted at an angle with respect to the handle. Each blade
unit has plural blades.
In other aspects, the invention features, in general, a shaving razor handle
having a shape that is
comfortable and permits a variety of different grips to be used. In one
aspect, the upper surface of the handle
has an elongated index finger indent that is sufficiently long to support
multiple segments of an index finger.
In another aspect the lower surface ofthe handle has an elongated thumb indent
that is sufficiently long along
a longitudinal axis to support both segments of a thumb oriented along the
longitudinal axis. In another
aspect, the upper surface of the handle is sufficiently long and the distal
region is curved and shaped so as
to fit in the palm of a user when an index finger is placed at a proximal
region of the upper surface. In
another aspect, side surfaces of the handle have a neck region between two
wider regions, the neck region
being sufficiently long to receive a thumb on one side and a plurality of
fingers on the other side. The index
finger indent is about 5/s" wide and about 2'/4" long, and the thumb indent is
about 1 " wide and about 3" long.
The thumb indent has a lip at its distal end to indicate the end of the indent
to the user. The thumb indent
is scooped in an axis that is transverse to the longitudinal axis with a
sufficient curvature to receive the end
segment of a thumb oriented along the transverse axis.
Embodiments of the invention may include one or more of the following
advantages. The razor
provides a conforming blade system in which the force is evenly distributed
over areas of pronounced
curvature. There is more blade contact on curved surfaces with the result that
shaving is faster and more
efficient. There are lower stresses developed with the result that the razor
glides smoothly across the surface.
The razor is self adjusting, making it easy to use. The razor conforms to
pronounced curvature with
application of low forces on the blade units and adjusts to both convex and
concave surfaces. The shaving
razor maintains local shaving geometry on the skin (e.g., blade angle and
exposure), at the same time that
it provides more contact and adjusts to the curvature. The composite overall
size of the series of blade units
is similar in length to an ordinary cartridge. There are no unshaven stripes
between the individual blade
units. The footprint of the blade units fits into tight areas. The flexure
arms deflect in a controlled manner.
The individual blade units do not interfere with each other. The razor
achieves even load distribution among
the individual blade units, providing maximum percentage contact area for each
blade unit. The razor has
uniform load distribution across each blade unit. The stiffness of the arms is
selected to maintain contact
with the skin to thereby avoid vibration. The four-bar linkage provides up and
down motion while
maintaining the orientation of the plane of the blades' cutting edges. The
shaving razor provides a smooth,
safe and comfortable shave. The handle conforms to fit naturally in the user's
hand and accommodates many
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CA 02493970 1999-12-28
grip styles. It has soft gripping materials in key locations.
Other advantages and features of the invention will be apparent from the
following description of
preferred embodiment thereof and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view of a shaving razor.
Fig. 2 is an elevation of the Fig. 1 razor.
Fig. 3 is a view showing the arrangement, shape and footprint of the blade
units of the Fig. 1 razor.
Fig. 4 is an elevation of a four-bar linkage mounting structure and attached
blade unit of the Fig. 1
razor in an at-rest position.
Fig. 5 is an elevation of the Fig. 4 mounting structure and blade unit in a
flexed position of maximum
vertical displacement.
Fig. 6 is a diagrammatic side partial elevation showing the blade units and
portions of the mounting
structure of the Fig. 1 razor in at rest and neutral pivot positions.
Fig. 7 is a diagrammatic partial elevation showing the Fig. 6 blade units at
displaced positions and
pivot angles while shaving on a curved surface.
Fig. 8 is a top view of the handle of the Fig. 1 razor.
Fig. 9 is a bottom view of the handle of the Fig. 1 razor.
Fig. 10 is a side view of the handle of the Fig.l razor.
Figs. 11-15 are perspective views illustrating different hand grip positions
when using the Fig. 1
razor.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to Fig. 1, there is shown shaving razor 10 including handle 12 and
three-blade units 14,
16, 18 that are each connected to handle 12 by a respective mounting structure
20. Handle 12 has a hard
plastic area 22 and elongated index finger indent 24 with an elastomeric
surface layer, to be engaged by the
index finger or other fingers, depending upon what grip is being used.
Referring to Fig. 2, it is seen that in an at-rest condition in which the
mounting structures 20 are not
flexed, the bottom surfaces of blade units 14, 16, 18 lie in a common plane
26. Each mounting structure 20
includes a proximal end 28 connected to handle 12, a distal end 30 connected
to the respective blade unit 14,
16, or 18, and elongated members 32, 34 connecting distal end 30 to proximal
end 28.
Referring to Fig. 3, it is seen that the following blade unit 16 has a
symmetrical shape, while front
blade units 14, 18 have cut out portions 36 and extended cap areas 38. Each
blade unit includes at least two
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CA 02493970 1999-12-28
blades 40 and has finned, elastomeric guard 42 and cap 44. The blades 40 are
each about one-half inch long,
and the blades in following blade unit 16 overlap the gap that exists between
the blades for the two front
units 14, 18. The composite overall size length of blade units 14, 16, 18 is
similar in length to an ordinary
cartridge. Referring to Fig. 4, mounting structure 20 is shown in detail. It
is made of an integral
molded plastic piece of PEBAX~, a polyethylene block amide available from Elf
Atochem, Birdsboro, PA.,
or other elastomeric polymer. Mounting structure 20 includes thinned area 50
to enhance moldability. It also
includes connecting members 52 at the distal end 30. Mounting structure 20 has
four living hinge sections
54 at which the plastic is gradually thinned to about 0.0130 inch thick as is
shown in Fig. 4. This provides
a four-bar, parallelogram linkage structure including elongated members 32,
34, side member 56 at distal end
30, and side member 58 at proximal end 28. This parallelogram four-bar linkage
provides controlled
displacement such that blade unit 14 will maintain its orientation shown in
Fig. 4 as it is displaced upward
(e.g., resulting from increased force on the surface of blade unit 14) to the
position shown in Fig. 5. The
blade units do not rotate about axes parallel to the cutting edges during this
up and down movement, and the
mounting structures 20 do not bend or twist, providing only up and down
movement of the respective blade
unit, with a slight sideways displacement, as is apparent by comparing the
horizontal position of blade unit
14 in Fig. 4 with its position in Fig. 5. Because of this controlled movement,
the individual blade units do
not interfere with each other and they maintain their relative positions, to
guarantee that following unit 16
covers the gap between the blades of front units 14, 18 and avoid stripes. In
Fig. 4, mounting structure 20
is shown in an at-rest (i.e., unloaded) position. In Fig. 5, mounting
structure 20 is shown at a stop position
at which the thicker portions of elongated members 32, 34 abut each other,
preventing further upward
displacement. Living hinges 54 resiliently deform to provide pivoting and tend
to return back to the at-rest
position as the displacement force is reduced.
Referring to Figs. 4 and 6, it is seen that distal end 30 of each mounting
structure 20 has a living
hinge 62 above the respective blade unit 14, 16, 18 to provide rolling of the
individual blade units about
respective pivot axes 60. In Fig. 6, blade units 14, 16, 18, mounting
structures 20, and living hinges 62 are
shown in neutral at-rest positions such as they would achieve when they are
not being pressed against a
surface or when they are uniformly pressed against a flat surface. Living
hinges 62 are resilient, and will
resiliently return to this position. Corners 69 act as stops, preventing
further rotation by interaction with the
upper surfaces of respective cartridges. In Fig. 7, the blade units are shown
in deflected positions and
orientations that result from shaving on curved surface 70. On surface 70,
mounting structure 20 for
following blade unit 16 has been displaced upward slightly with respect to the
other two mounting structures
20, and blade unit 18 has pivoted counter-clockwise at its living hinge 62,
while blade unit 14 has pivoted
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CA 02493970 1999-12-28
clockwise at its living hinge 62. Each blade unit 14, 16, 18 thus is capable
of independent movement both
in an up and down displacement direction and in pivoting in order to
distribute the contact forces against the
surface being shaved and to follow and to conform to the curvature of the
surface being shaved. Thus lower
stresses result on the cutting edges. The combination of living hinges 54 and
living hinges 62 thus permit
blade units 14, 16, 18 to roll and move up and down without pitching or
yawing.
Handle 12 matches the natural curvature at rest in human hands, including the
curvature at the
transverse arch at the base of the palm, the curvature of the transverse arch
at the distal end of the palm at
the fingers, and the curvature of the longitudinal arch extending from the
base of the palm to the ends of the
fingers. The at-rest position of the hand is perceived to be the most
advantageous for doing work, and the
stress-less position of the hand gives the user a feeling of greater control
and comfort. In addition, handle
12 is provided with indents and neck regions to permit comfortable gripping in
a variety of grip positions,
as shown in Figs. 11-15.
Referring to Figs. 3 -10, handle 12 has upper surface 71, lower surface 72,
side surfaces 73, and end
74 for connection to blade units I 4, 16, 18. Index finger indent 24 on upper
surface 70 is about 5/a" wide and
about 2'/0" long, which is sufficiently long to support at least two segments
of an index finger, providing a
greater degree of control. Upper surface 71 also has a curved proximal (with
respect to the user's hand)
region 78. Upper surface 71 is sufficiently long and proximal region 78 is
shaped so that proximal region
78 fits in the palm of a user when an index finger is placed on index finger
indent 24; this also provides a
more comfortable fee( and good control. Lower surface 72 has elongated thumb
indent 76 that is about 1"
wide and about 3" long, which is sufficiently long along a longitudinal axis
to support both segments of a
thumb when the thumb is oriented along the longitudinal axis. Thumb indent 76
has lip 82 at its proximal
end to indicate the end of the indent to the user. Thumb indent 76 is scooped
in an axis that is transverse to
the longitudinal axis with a sufficient curvature to receive the end segment
of a thumb oriented along the
transverse axis. Side surfaces 73 converge to provide a neck region 80 between
two wider regions. Neck
region 80 is sufficiently long and shaped to receive a thumb on one side and a
plurality of fingers on the other
side.
Referring to Figs. I 1-I5, the handle accommodates different grip positions
that may be used by
different users when shaving different parts of the body, such as the legs,
the arms, the underarms, and the
bikini area. A first grip position (Fig. 11 ) involves the thumb at the back
of the thumb grip, and multiple
fingers wrapped over the upper surface of the handle. A second grip position
(Fig. I 2) involves holding the
proximal end of the handle in the palm, with the V between the thumb and index
finger being located over
upper surface 71. A third grip position (Fig. 13), called the pinch, involves
placing the thumb on thumb
CA 02493970 1999-12-28
indent 76 transverse to its longitudinal axis, and the other fingers extending
over and transverse to index
finger indent 24. A fourth grip position (Fig. 14) involves placing the index
finger over the length of the
index finger indent 24, the thumb at the neck region 80, and the remaining
fingers wrapped around the
proximal portion 78. A fifth grip position (Fig. 15) involves placing the
thumb over and transverse to the
thumb indent 76 at its back, and receiving the curved proximal portion 78 of
the handle on the side of a
curled index finger.
During shaving, the razor self adjusts and conforms to both convex (e.g.,
knees and ankles) and
concave (e.g., underarm) surfaces. The individual blade units 14, 16, 18
maintain local shaving geometry
on the skin (e.g., blade angle and exposure) at the same time that they
independently adjust to the curvature.
Only small forces are needed to cause upward displacement, such that there is
relatively even load
distribution among the individual blade units. Individual blades units 14, 16,
18 have even load distribution
across their blades.
Other embodiments of the invention are within the scope of the claims.
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