Note: Descriptions are shown in the official language in which they were submitted.
CA 02242199 1998-07-03
WO 97/25190 PCTl(1597/00407
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RAZOR BI~AI~E UNIT
This invention relates to shaving devices and
concerns a safety razor blade unit having at least one
blade with a cutting edge which is moved across the
surface of the skin being shaved by means of a handle
to which the blade unit is attached. The blade unit
may be mounted detachably on the handle to enable the
blade unit to be replaced by a fresh blade unit when
the blade sharpness has diminished to an unsatisfactory
level, or it may be attached permanently to the handle
with the intention that the entire razor be discarded
when the blade or blades have become dulled. Razor
blade units generally include a guard which defines a
surface for contacting the skin a.n front of the
blades) and a cap for contacting the skin behind the
blade(s), the cap and guard serving important roles in
establishing the so-called "shaving geometry", i.e. the
parameters which determine the blade orientation and
position relative to the skin during shaving. The
present invention is especially concerned with the
guard and/or cap of a razor blade unit.
It is known to provide a skin engaging guard
or cap with surface configurations intended to produce
pleasant tactile sensations during shaving, for example
as described in US-A-5191712.
The present invention aims to provide an
improved surface structure on a cap or guard and in
accordance with this object the invention resides in a
safety razor blade unit having at least one elongate
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blade, and a skin engaging member defining a surface
for contact with the skin during shaving, said surface
being defined by spaced hollow projections extending
upwardly from a base and open at their upper ends, the
projections being formed of a resiliently flexible
~
material whereby the upper ends of the projections can
deflect locally under forces encountered during
shaving.
Conveniently the projections can take the
form of tubes which may be arranged in one or more rows
extending along the base generally parallel to the
razor blade edge(s), with at least 10 tubes per row.
Suitably the projections have a height in the range of
0.38mm to l.5mm preferably about 0.75mm, an outer
diameter from 0.40mm to 3.OOmm, preferably about
0.60mm, and with the wall thickness at the base to
height ratio being between 1:1 and 1:15, preferably
around 1:7.5. An appropriate spacing between adjacent
projections, at least in the direction parallel to the
blade edge(s), is in the range from 0.10mm to a
distance equal to the maximum dimension of the
projection measured a.n said direction, the spacing a.n a
currently preferred embodiment being 0.20mm. If
desired adjacent projections can be interconnected,
such as by membranes moulded integrally with the
projections.
The projections may be of constant internal
and external diameter, but they can also taper in
either direction along their length both inside and/or
outside. A suitable wall thickness for the hollow
projections has been found to be around O.lOmm, at
least at their upper edges. It is not essential for ~
the projections to be completely annular in cross-
section and they can have one or more longitudinal
slots extending over their full height or only part of
their height.
In the preferred embodiments described in
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more detail below, tubes of circular in cross-section
are provided but this is not essential and other cross-
sectional shapes are possible, such as elliptical,
square or D-shaped.
The upper end faces of the projections can be
substantially flat and coplanar. Alternatively the
upper end faces may be inclined forwardly and
downwardly toward the base. Also the upper edges of
the projections may be rounded off, at least at the
fronts of the projections.
With a razor blade unit according to the
invention the projections forming the skin contacting
surface of the skin engaging member, because they are
hollow and open at the top, can be more responsive to
local forces during shaving, e.g. due to a hair being
encountered, than solid projections and as a
consequence there may be less tendency for hairs to be
deflected laterally by the projections. Furthermore,
the hollow projections form pockets in which moisture
or a shaving preparation, such as shaving soap or the
like, applied to the skin to facilitate the shaving
operation, can collect in small amounts. A shaving
preparation generally serves to lubricate the skin.
Any preparation collected in the pockets may assist in
lubricating the skin, e.g. at the end of a shave when
most of the preparation applied will have been removed,
or perhaps at the beginning of a shave if the skin has
not been well prepared. The skin engaging member could
even be supplied with the pockets containing shaving
enhancement product, or possibly communicating with a
reservoir of such a product to be dispensed through the
pockets, in essentially the same manner as described in
relation to the pocketed skin engaging members
disclosed in our International Patent Application No.
PCT/US95/08634 (W096/02369). With the present
invention delivery of product from the pockets may be
enhanced by a pumping action due to the projections
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flexing as the skin contacting member moves across the
surface of the skin.
Some embodiments of the invention are
r
described in more detail below with reference to the
accompanying drawings, in which:
a
Figure 1 shows in perspective a skin
contacting member for a blade unit according to the
invention;
Figure 2 is a plan of the skin engaging
member;
Figure 3 is a cross-section taken along the
line A-A of Figure 2;
Figures 4 and 5 are front and end elevational
views of the skin engaging member;
Figures 6 to 17 are enlarged cross-sectional
views of alternative forms of hollow projection;
Figure 18 is a plan view of a projection of a
modified embodiment;
Figure 19 is a front elevation of the
projection shown a.n Figure 18;
Figure 20 is a front elevation showing a
projection with an inclined top face;
Figure 21 is a cross-section through the
hollow projection of Figure 20;
Figure 22 a.s a cross-sectional view showing a
projection with a top edge which is rounded off at the
front, and
Figures 23 to 26 show in plan respective
alternative shapes for the projections.
The skin engaging member 1 illustrated in
Figures 1-6 is intended to form either a cap, or more
probably a guard surface in a safety razor blade unit
having one or more elongate blades. The member 1 is
elongated and will be mounted on a frame of the blade
unit to extend in parallel with the blades. The member
1 is moulded in one piece of an elastomeric material,
e.g. rubber or a thermoplastic elastomer such as that
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sold under the Trade Mark KR.ATON. It includes a
rectangular base 2 from which extend upwardly,
cylindrical open-topped hollow projections or~tubes 3.
The tubes are arranged in tour longitudinal rows in
which the tubes 3 are equally spaced at a distance not
greater than the outer diameter of the tubes, and the
tubes of alternate rows are longitudinally staggered by
a distance which is half the centre-to-centre pitch P
of adjacent tubes in the same row. As a consequence,
tubes of adjacent rows overlap in the longitudinal
direction, and as shown they also overlap in the front
to rear direction. The dimensions are as follows:
Base length - 1 . 30.00 mm
Base width - w . 2.5 mm
Tube height-h . 0.75mm
Tube outer diameter - dl . 0.60 mm
Tube inner diameter - d2 . 0.40 mm
Tube wall thickness- t . O.lmm
Tube pitch (in each row) -p . 1.23 mm
Number of tubes per row . 24
Total number of tubes . 96
The tubes 3 have a constant circular
cylindrical cross section as clearly illustrated in
Figure 6. However this particular tube shape is not
essential and Figures 7 to 11 illustrate alternative
shapes as follows:
In Figure 7 the hollow interior tapers
towards the base from a maximum inner diameter of 0.4mm
to a minimum inner diameter of O.lmm:
In Figure 8 the exterior is frusto-conical
and tapers from a diameter of 0.7mm at the base to
0.6mm at the top, the inner diameter being constant at
0.4mm;
In Figure 9 the exterior is frusto-conical as
in Figure 8, and the hollow interior tapers towards the
base and.has a maximum diameter at the top of 0.25mm so
that a greater wall thickness is obtained;
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In Figure 10 the exterior is frusto-conical
as in Figs 8 and 9, and the interior has a
corresponding frusto-conical shape so that the wall
thickness remains constant over the full height and the
inner diameter increases from 0.4mm at the top to
0. 5mm at the base;
In Figure 11 an inverted frusto-conical shape
with a constant wall thickness is shown, the maximum
inner diameter at the top being 0.5mm and the maximum
inner diameter at the base being 0.4mm;
In Figure 12 another inverted frustoconical
shape is shown, the inner diameter being constant at
0.3mm whereas the outer diameter increase from 0.5mm at
the base and the top peripheral edge of the tubular
projection is rounded off at a radius of O.lmm;
In Figures 13 and 14 the tubular projections
are as shown in Figures 8 and 9 respectively, except
that in each case the outside diameter at the base a.s
0.75mm;
In Figure 15 is shown a tubular projection
having the same external form of the projection of
Figure 14, but with a larger inner diameter at the open
top end where the wall thickness is minimum and about
0.lmm;
In Figure 16 the illustrated tubular
projection is the same as that of Figure 10 other than
that the outer diameter at the base is 0.75mm, and the
inner diameter at the base is 0.55mm, the wall
thickness being uniform at O.lmm; and
In Figure 17 the tubular projection is
similar in shape to that of Figure 11, but the
diameters are reduced, the outer diameter at the base
being 0.5mm, and the inner diameter increasing from
0.3mm at the base to 0.4mm at the open end, the wall '
thickness being constant at 0.lmm.
In the embodiments described above the
projections have completely annular cross-sections, but
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in the modified embodiment of Figures 18 and 19, the
tubular projection has a longitudinal slot extending
the full height of the tube at the front of the tube.
Apart from the slot, which has a width of 0.lmm, the
tubular projection is of the same shape and size as in
the embodiment of Figures 1-6. The slot could be
provided at other positions, and additional slots could
also be provided.
In all of the embodiments described above the
tubular projections have a height of 0.75m and are
essentially flat-topped in as much that the height is
the same around the projection periphery. This is not
crucial and it may be beneficial for the upper edge of
the projection to be relieved, in particular a.n the
forward facing direction. Figures 20 and 21 illustrate
an example of a tubular projection 3 basically the same
as the projections of Figures 1 to 6, but having a
forwardly and downwardly inclined top face 10, the
downward inclination being at an angle a of about 30°.
Figure 21 shows an alternative modification according
to which the front edge 1l at the upper end of the
tubular projection 3 is rounded off at a radius of
0.3mm. L~hile illustrated a.n relation to tubular
projections as in Figures 1 to 6, the inclined top face
10 and rounded edge 11 modifications of Figures 20 to
22 can be applied to any of the embodiments of Figures
7 to 19, and to the modified embodiments described
below.
All of the embodiments so far described have
tubular projections of substantial circular cross-
section. However, other cross-sections are also
' satisfactory, and some examples of other acceptable
cross-sections are illustrated in Figures 23 to 26.
' The projection 3 in Figure 23 is square in cross
section, the wall thickness t being 0.lmm, the exterior
having a side length Sl of 0.6mm and the interior
having a aide length S2 of 0.4mm. The tubular
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projection of Figure 24 is substantially D-shaped in
cross-section, being essentially the square section of
Figure 23 with one side replaced by a semi-circular
wall with an inside radius r1 of 0.2mm and an outside
radius r2 of 0.3mm. The semi-circular wall could be
arranged to face either forwardly or rearwardly. The
cross-section of the tubular projection shown in Figure
25 has the same external profile as that of Figure 24,
but the internal profile is circular with a diameter of
d~ of 0.4mm. Finally, Figure 26 shows a projection
having a cross-section shaped as an open-sided square
and is the same as the projection of Figure 23 but with
the rear wall omitted. It will be appreciated that
projections with the cross-sections of Figures 23 to 26
l5 could be arranged to taper internally and/or externally
as in the various projections of Figures 7 to 27. Of
course other cross-sectional shapes are also possible
such as triangular, elliptical or oral.
While in any particular embodiment all the
projections can conveniently be of the same shape and
size, this is not essential and projections of
different form could be combined in the same
embodiment.
The material of the skin engaging member will
have a flexibility appropriate for the particular shape
and size of projections provided, but a hardness of
less than 90 shore A will normally be appropriate.
Y
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