Razor Cartridge

Abstract

A razor cartridge has a housing with a blade mounting region between a guard and a cap. A first, second and third razor blade are sequentially mounted in the blade mounting region. An over-guard is secured over the blades. The cutting edges of the blades have an as-defined increased sharpness. The blades are mounted at a reduced angle between each blade portion bearing the cutting edge and a reference plane tangential to the cutting edges of the first and third blade. Individual longitudinal members of the over-guard that lie over each blade and have a progressively decreasing height above the reference plane in a front to back direction of the razor cartridge. A further longitudinal member is forward of the first blade and has a height above the reference plane.

Claims

1-10. (canceled)

11. A razor cartridge, comprising: a housing having a guard at a front region of the housing, a cap at a rear region of the housing, and opposed end walls connecting the guard and the cap, the housing defining a blade mounting region between the guard and the cap; a first razor blade closest to the guard, a next-adjacent second razor blade, and a third razor blade mounted in the blade mounting region, each having a respective cutting edge having a sharpness; a reference plane tangential to the cutting edge of the first razor blade and the cutting edge of the third razor blade, each blade body portion bearing the cutting edge being at an angle to the reference plane; an over-guard secured over the first razor blade, the second razor blade, and the third razor blade, and including a first longitudinal member in advance of the first razor blade, and a second longitudinal member lying respectively aft of the third razor blade, the second longitudinal member having a respective height above the reference plane; wherein the over-guard further includes a front to back cross rib, extending from the first longitudinal member to the second longitudinal member.

12. The razor cartridge of claim 11, wherein the over-guard has front to back extending slots in the first longitudinal member and the second longitudinal member.

13. The razor cartridge of claim 12, wherein the front to back extending slots are aligned in a front to back direction of the razor cartridge.

14. The razor cartridge of claim 12, wherein the front to back extending slots are offset in a front to back direction of the razor cartridge.

15. The razor cartridge of claim 12, wherein the front to back extending slots have a width of 0.8 mm.

16. The razor cartridge of claim 12, wherein the front to back extending slots have a depth of 0.52 mm.

17. The razor cartridge of claim 12, wherein the front to back extending slots have a pitch of 1.6 mm.

18. The razor cartridge of claim 11, wherein each of the first longitudinal member and the second longitudinal member have a respective height above the reference plane.

19. The razor cartridge of claim 11, wherein the cutting edge of each of the first razor blade, the second razor blade, and the third razor blade, has a cut-force sharpness in a range of about 5-6.5 N.

20. The razor cartridge of claim 11, wherein the angle is between 19 degrees and 21.5 degrees.

21. The razor cartridge of claim 11, wherein each height progressively decrease in a front to back direction of the razor cartridge.

22. The razor cartridge of claim 11, wherein the height of the second longitudinal member is in a range about 0.287 to 0.212 mm.

23. The razor cartridge of claim 11, wherein the height of the first member is equivalent to the height of the second member.

24. The razor cartridge of claim 11, further comprising a fourth razor blade and a fifth razor blade.

25. The razor cartridge of claim 11, further comprising a retainer, the retainer configured to retain the first razor blade, the second razor blade, the third razor blade, and the over-guard to the housing.

26. The razor cartridge of claim 11, wherein the over-guard comprises an injection molded ABS or POM, a die-cast zinc alloy, or stainless steel.

27. The razor cartridge of claim 11, wherein a first span between the first razor blade and the second razor blade is 2.72 mm.

28. The razor cartridge of claim 11, wherein a second span between the second razor blade and the third razor blade is 2.72 mm.

29. The razor cartridge of claim 11, wherein the first razor blade is spaced apart from the first longitudinal member by between 0.8 mm and 0.9 mm.

30. The razor cartridge of claim 11, wherein the third razor blade is spaced apart from the second longitudinal member by between 0.8 mm and 0.9 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 is an upper perspective view of a razor cartridge of the present disclosure;

[0011] FIG. 2 is a transverse sectional view of the cartridge;

[0012] FIG. 3 is a detailed portion of FIG. 2; and

[0013] FIG. 4 is a perspective view of another over-guard of the present disclosure.

DETAILED DESCRIPTION

[0014] Referring now to the drawings and in particular FIG. 1, a razor cartridge 20 is depicted. The cartridge 20 has a housing 30 with a guard 40 at a front region of the housing 30 and a cap 50 at a rear region of the housing 30. The guard 40 can optionally be provided with skin-engaging fins, as depicted, e.g. elastomeric fins. In the context of the present disclosure the terms front, forward, leading etc., and rear, aft, trailing etc. are used relative to a direction of motion of the razor cartridge 20 in use. The term longitudinal is used relative to an elongated direction 32 of the housing. The housing has opposed end walls 60 connecting the guard 40 and cap 50. The housing defines a blade mounting region 70 (see FIG. 2) between the guard 40 and the cap 50. A first razor blade 80, closest the guard 40, a second, immediately trailing razor blade 90, and a third rearmost razor blade 100 are mounted in the blade mounting region 70. Each razor blade 80, 90, 100 has a respective cutting edge 82, 92, 102 (see FIGS. 2 & 3). Three razor blades 80, 90, 100 are described as being mounted in the cartridge 20 of the present disclosure however this quantity should not be limiting and fewer (e.g. two) or more (e.g. four, five etc) razor blades can usefully be employed. An over-guard 120, being a separate component part of the assembly of the cartridge 20 is positioned over the blades 80, 90, 100. A retainer 130, e.g. one or more aluminum clips, is formed around the housing 30 to retain the blades 80, 90, 100 and over-guard 120 to the housing 30. In the embodiment depicted in FIG. 1 certain elements of the over-guard 120 are provided with hair-aligning slots 122 in the skin-engaging surfaced. The slots 122 can have a width 0.8 mm, a depth 0.52 mm deep, and a pitch 1.6 mm. The slots 122 can be aligned in a front to back direction of the cartridge 20, or can be offset.

[0015] The housing 30 is manufactured by injection molding a suitable thermoplastic polymer. For example, the housing 30 can be formed from ABS (acrylonitrile butadiene styrene) for benefits of chemical resistance (to substances typically found in use), impact resistance, and dimensional stability.

[0016] The over-guard is manufactured from a material having a tensile modulus 1.4-210 GPa. For example, the over-guard 120 can be injection molded ABS or POM. The over-guard 120 can be die-cast zinc alloy. The over-guard 120 can be (stainless) steel, e.g. formed in a perforation tool, or can be particulate stainless steel that is sintered to provide a solid body.

[0017] Referring now to FIG. 2, a transverse cross section of the cartridge 20 is depicted. The over-guard 120 for a three-blade cartridge 20 comprises essentially four longitudinally extending members. A first member 140 is in advance of the first blade 80 and has a leg 142 providing structural (stiffness) benefits. Members 150, 160, 170 lie respectively over the three blades 80, 90, 100, and have respective legs 152, 162, 172 also for structural (stiffness) benefits. Referring back to FIG. 1, the over-guard 120 is provided with a front to back cross rib 180, extending from member 140 to member 170 for further structural stability benefits.

[0018] In FIG. 4 another over-guard 120 is depicted, omitting the slots 122 of FIG. 1. In this Fig. it can be seen that all four longitudinally extending members are interconnected at opposed elongated ends of the over-guard 120.

[0019] Referring now to FIG. 3, a detailed portion of FIG. 2 is depicted. A reference plane 200 is tangential to the cutting edges 82, 102 of the first and last (e.g. third) blades 80, 100. The plane 200 can also be tangential to the cutting edge 92 of the other (e.g. second) blade(s) 90, especially in embodiments where the razor cartridge has two blades. The blade cutting edges are spaced apart by a span dimension along plane 200 by spans S1, S2 equal to 2.72 mm. Each blade cutting edge 82, 92, 102 is spaced from the respective immediately next-forward longitudinal member 140, 150, 160 by a distance 202, 212, 222 respectively in a range 0.8-0.9 mm. The distances 202, 212, 222 being measured from the respective cutting edge to the next-forward skin engaging tangent point of the over-guard 120. The longitudinal members 150, 160, 170 have a height H1, H2, H3 respectively from the upper respective skin engaging surface to the reference plane 200. The first longitudinal member 140 has a height from the upper skin engaging surface to the reference plane 200 that is equivalent to height H1. The blades 80, 90, 100 are each positioned such that the blade body portion bearing the cutting edge is at an angle A having a value about 20.5 degrees (e.g. in a range 19 to 21.5 degrees) to the reference plane 200. The angle A can be defined between the reference plane 200 and one (i.e. upper or lower) outer surface of the blade body portion, or can be defined (as shown) between the reference plane 200 and a notional center plane of the blade body portion. This value is slightly lower than the angle found in many typical modern wet shaving cartridges, which can be in a range 22-28 degrees, and has been found beneficial when used in the present device in conjunction with blade cutting edges having increased sharpness, as described below.

[0020] The cutting edges 82, 92, 102 of the blades 80, 90, 100 can have conventional sharpness, as generally found in typical modern wet shaving cartridges, i.e. about 7-14 N, with a median value about 10-10.5 N as measured in a cut force test, as described below. More preferably the blades have increased sharpness, e.g. about 5-6.5 N. In the cut force test the blades are cut perpendicularly (relative to the medium being cut) 15 times into fully water saturated WHATMAN cellulose chromatography paper, having thickness 0.9 mm and width 25.4 mm. The cutting speed is 15 mm/min and cutting depth into the paper is 0.8 mm. The above-mentioned sharpness cut force is the average plateau force from cut no. 7 to cut no. 9.

[0021] In experimental arrangements, cartridges having the following heights H1, H2, H3 were evaluated:

TABLE-US-00001 H1 H2 H3 (mm) (mm) (mm) Example 1 0.287 0.212 0.116 Example 2 0.150 0.129 0.069 Example 3 0.039 0.039 0.037

[0022] The values of H1, H2, H3 progressively decrease in a front to back direction of the cartridge. In controlled shaving test, the Applicants of the present disclosure have found the combination of sharper blade cutting edges, plus reduced blade body to reference plane angles, plus greater over-guard longitudinal member heights above a reference plane (e.g. of examples 2, and 1) provide benefits to sufferers of PFB, and also provide controlled beard length trimming for a permanent 5 o'clock shadow appearance for the user.

[0023] While various embodiments have been described above it should be understood that they have been presented by way of example only, and not limitation. For instance, modifications or changes as can be made within the scope of the attached claims and features disclosed in connection with any one embodiment can be used alone or in combination with each feature of the respective other embodiments. Thus, the breadth and scope of any embodiment should not be limited by any of the above-described exemplary embodiments but should be defined only in accordance with the following claims and their equivalents.