CA1076789A - Safety razor - Google Patents

Abstract

SAFETY RAZOR
ABSTRACT OF THE DISCLOSURE

A razor blade assembly which is flexible in at least one bending mode. A seat member of substantially planar shape has an integrally formed guard located transversely along its forward margin.
The guard and seat members are formed of a flexible material. A
flexible blade having a sharpened edge along a transverse margin is disposed on a surface of the seat member having its edge parallel to and rearwardly located of the guard bar. A cap member of flexible material has a planar surface in contact with the blade and a front margin located rearwardly of the cutting edge. The seat, blade and cap are yieldingly bonded together and freely flexible about an axis parallel to the plane of the blade and perpendicular to the cutting edge.

Description

1(~76789 BACKGROUND OF THE II~VENTION
This invention is directed to a nov'el safety razor construc-tion and more particularly directed to a flexible razor blade assembly.

Since the introduction of the safety razor, the blade assembly has consisted principally of three members, namely, a handle, a guard ba'r and seat combination, and a cap. The function of the guard bar/seat and cap is to properly locate and hold the blade io the proper location for cutSlng hair in controlled contact with the skin. Generally these elements have been manufactured as separate components which, when removably attached or fixedty attached to the handle, combine to main-tain desired geo.~etry in relationship of these elements during the act of shaving.

Of more recent development is the bonded cartridge or razor blade assembly in which the seat, cap and blade are permanently and rtgidly bonded together to achieve and maintain a desired shaving geometry and fixed relationship of the parts. In this arrangement,'the cartridge is adapted to be coupled as a complete and unltary assembly to the handle. This type of configuration is exemplified and disclosed in United States Patent 3,783,510, which employs a tandem or twin blade assembly with a spacer therebetween permanently and rigidly bonded to a cap and platform member, the platform member or seat having an integral guard bar and coupling members for attachment to the handle.

The advantage of the bonded cartridge is mainly one of con-

2~ ventence. It achieves no more than prlor art shaving systems previouslydescrlbed, i.e., discretc components assembled to the ra20r handle, but -2- ~
.

107~789 it does provide some ease of hand11ns with a concomitant ;ncrease in price.

There have been attempts to alter the operatlon and geo-metrical relationships ~f the blade assembly to achieve increased sl)aving comfort and efficiency. Patent No. 1,383,783 descrtbes a shaving system having a number of parallel arrayed blades fixed to a flexible support or platform, the purpose of the flexible support being to provide or enable the razor to adapt itself to contours of the face while being moved thereover. The platform of this prTor art device is flexible about an axis parallel to the plane of the blades and to t~e edges thereof; hence such structure fails to permit the blade itself to conform to facial or body contours.

Another attempt to fashion a blade assembly adaptable to user requirements is described in Patent 3,500,539. The device des-lS cribed therein utilizes a transversely arrayed guard bar connected to the blade platform by a yieldable web structure. Dependent upon the applied shaving force, the orientation of the guard with respect to the blade edge is altered resulting in changing blade exposure, blade tangent angle, and shaving angle. These terms are defined as follows: The blade exposure is the normal distance the blade edge extends above or below a plane tangent to the cap and guard bar;
the blade tangent angle is the angle formed between a plane tangent to the blade edge and the guard bar and a second plane bisecting the blade edge; the shaving angle is the angle formed between the plane bisecting the blade edge and the plane tangent to the cap and guard bar. Theoretlcally~ this type of arrangement might permit a shaver to select desired geometry by the application of a controlled force.
However, In practlcal appllcatlon, the achleving of the desired ' ~3~

geometry in this fashlon has proven difficult. It is further pointed out that the structure of this patent fails to provide for adapt-abTlity to the contours of the shaver's face or body.

Applicants have realized the desirab;lity of a shav7ng system which would maintain uniform, conslstent geometry when in use but which would also allow the blade to substantially conform to the contours of the sk;n surface in order to achTeve greater comfort, safety and '' efficiency. Such a system would allow selection of optimum shaving geometry and, if given sufficient flexibility, would permit the main-tenance of optimum geometry while the system was conforming to varying contours. Flexing of the assembly may be derived through mecha~;cal or structural changes of the blade assembly or through the utilization of materials which allow the cap and seat to yieldingly follow changing contours. In using a device of this nature, the cutting edge is allowed to stay in contact with a maximum amount of skln surface des~ito undula-tions therein, which a non-flexible system might only achieve when shaving a surface parallel to the blade edge. Obviously, the latter surface is unavailable on the human body ' The intent'of this invention is to define and provide a system which'maintains uniform and consistent shaving geometry while substan-tially conforming to the contours of the skin surface. Another object of the Invention is to provide a flexible razor blade assembly whereln' the cuttlng edge ;s maintained in optimum contact with the skin surface.
Yet anotiner object of the invention is to provtde a unitary bonded flcxlblc shaving cartridgc having at least one razor blade thereln.
Yct another object of the present invention is to provide a flexible car~rldge In which the components thereof are yieldlngly bonded togetber.

SUMMARY OF THE INVENTION
.
The foregoing disadvantages of prior art systems and the objects of the invention are satisfied and achieved by the present invention which provides a blade assembly comprising a flexible seat member having a surface, a flexible blade having a sharpened cutting edge disposed on the surface, and a flexible guard member located forwardly of the cutting edge, the seat, blade and guard member being yieldingly bonded together and flexible about an axis parallel to the plane of the blade and perpendicular to its cutting edge.
Another aspect of the present invention contemplates a seat member having a substantially planar surface and an integral platform formed transversely along a forward margin, the guard and seat members being formed of a flexible material. A flexible blade having a sharpened edge along a transverse margin is dis-posed on the seat member in contact with the planar surface with its edge parallel to and rearwardly located of the guard bar. A
cap member of flexible material has a planar surface in contact wlth the blade surface and a front margin located rearwardly of the cutting edge, the seat member, guard member, blade, and cap being yieldingly bonded together and flexible about an axis parallel to the plane of the blade and perpendicular to the cutting edge. In another aspect of the invention, cap and seat members are bonded together with a blade interposed therebetween, the assembly being flexible about an axis parallel to the plane of the blade and perpendicular to the cutting edge and wherein the shaving angle and blade tangent angle and exposure remain substantially constant during flexure of the assembly.
Another aspect of the invention contemplates seat, guard bar and cap members molded from a flexible polymer or other flexible material and in which the seat member has a plurality of ribs in parallel array perpendicular to its forward margin, the ribs being interconnected by _ 5_ 10767~9 flexlble webbing, thereby permitting flexure of the asscmbly about an axis parallei to the plane of the blade and perpendicular to the cutting edge.

The objccts and features of the present invention will be apparent upon consideration of the detail and specification hcreafter set forth taken in conjunction with the drawings, The drawings arc .
intended to be exemplary of the invention and standard symbols are used with consistent numbering throughout the different views.
.

. . . BRIEF DESCRIPTION OF THE DRAWING5 .
Figure l is an exploded fragmentary view of a twin bladc cartridge and razor handle made in conformity with the present invention; .

Figure 2 is a perspective view of the blade seat of Figure l;

. Figure 3 is an exploded perspective view of a single blade cartridge made in accordance with the present invention;

FTgure 4 is a schematic cross-sectional view of a blade -assembly showing blade angle, tangent angle, and expos.ure;

Ftgure 5 is a schematic perspective view showing the cartridge in concav~ flexure;

Figure 6 is a schematic perspective view showing the cartridge in convex flexure; and Figure 7 is a perspective view of another embodiment of the present invention.

1076785~
DESCRIP~ION OF THE PREFERRED EMBODIMENT
. Referring to Figure 1, there is shown a razor'blade asscmbly 10 made tn conformance with the present invention. A flexlble seat membcr 11 having an integral guard bar 23 is assembled to an adhesive strip 12, a first blade 13, a second adhesive strip 14, a spacer member 15, a third adhesive strip 16, a seconq blade 17, a fourth adhesive strip 18, and finally a cap member 19. When brought together under suitable comprcs-sive forces, the assembly comprises a bonded twin blade cartridge flexible about an axis parallel to the plane of the blades and perpen-' 10 dicula,r to their edges. A head member 20 of a shaving handle tnot shown) connects to seat 11 by means of linkage pins 21. When head 20 is coupled to seat 11, face 32 engages face 36.

.
, ' , Referring also to Figure 2, seat 11 includes an upper planar surface 8, a rear margin or'face 32 and side margins 9. Comb guard bar member 23 is transversely arrayed along the front margin of seat ll h,aving' raised portions or members 22 located at each end thereof to protect the user from coming in contact with blade c,orners. Seat 11 is formed by a series of parallel arrayed ribs 33 running transversely along its entire , length anai arranged perpendicular to its front margin. End ribs 32a are of greater cross-section than ribs 33 to lend structural ;ntegrity and cross-axis stiffness to the assembly. Ribs 32a found at either end of seat'll are integrally formed with and terminate in end members 22.
Also formed of greater cross-sectTon than ribs 33 are ribs 28 and 29 containing channels 24 and 25 into which pins 21 of head 20 are inserted.

Channel 24 is circular in cross-section extending from margin 32 to a point rearward of the front margln. Channel 24 opens Into an enlarged plenum 26 from whlch polnt on rTb 28 is blfurcated forming two rlbs havlng substantially the same cross-sectional dimension as ribs 33.

.

iO76789 When one of linkage pins 21 is inserted through channel 24, its expanded hcad is received in plenum 26, thereby allowing free ro~ation of pin 21 in channel 24, the dimensions of which are controlled accordingly. The enlarged head of pin 21 restricts extraction from channel 24. Channel 25 opening into p)enum 27 i5 substantially sinilar to channel 24 and plenum 26 except for its el~iptical cross-sectional geon-etry. The e!lipsoidal shape is selected so as to permit translational movement of pin 21 in channel 25 during flexure of seat 11. It can be appre-ciated that if seat 11 were flexed to conform to some given geometry the circumferential length of the arc segment located between the axes of channels 24 a~d 25 wou1d need increase, such increase being compen-sated for by translational movement of pin 21 in channel 25.

A preferred construction of seat 11 finds a web thickness of approximately 0.014 to 0.016 inch as providing optimal flexibility although this dimension may vary from approximately O.OlO to 0.030 inch with~ut seriously dimintshing performance. It has been further found that the tooth width of comb guard bar 23 is preferably approx-tmately 50% of the pitch increment, i.e., half the dimension from one face of the tooth to the same face of the next tooth, although again this dimension may be varied from about 25% to 75% of the pitch incre-ment without seriously affecting performance. The pitch increment itself is preferably approximately 0.124 to 0.126 inch, but may be varied between approximately 0.090 and û.200 inch in practlce pf the invention. To achieve desired bending or flexure of cartridge 10, pivot linkage plns 21 and channels 24 and 25 may be spaced apart a distance equaling approximately 50% of the transverse length of seat 11.
In a typical cartridge 10 design, th7s distance may vary and, for example, in a cartrldge having a transverse length of 1.6 ;nches the center-to-center spacing of channels 24, 25 may be approximately ~ 976 inch. A decrease in pivot pins 21 center-to-center spacing generally favors or decreases the forces necessary in producing convex deflection while an increase in center-to-center spacing produces the converse. In some applications it has been found advantageous to place the pins in end ribs 32a to provide minimum concave flexure force. With regard to deflection forces, lands 34 and 35 are placed about the entrance apertures of channels 24 and 25 ~ respectively. The lands minimize the area contact between margin 32 and face 36 of holder 20. It should also be noted that cartridge 10 bending may be achieved through a number of pivot linkage designs, e.g., rotatable cams, compliant materials, etc.
Seat 11 is preferably injection molded of a flexible plastic material such as polyvinyl chloride, polyethylene, ethylene vinyl acetate, silicone, urethane and thermoplastic rubbers. A number of products presently on the market, for example, Firestone FPC-1376~ Uniroyal TPR-1600E~ BoF~ Goodrich 83794 and Dupont Alathon 3175~ represent suitable molding materials containing the foregoing generic polymers. In a functional sense, a suitable material may be considered to be a polymer having required flexibility and stiffness which is capable of being adapted to high production molding techniques.
The flexibility of the material in cooperation with the struc-tural design provides the necessary compliance to satisfy the demands of the present invention.
Adhesive strips 12 ~ 14 ~ 16 and 18 act to bond the compon-ents of the cartridge togetherO Suitable adhesives are acrylics, rubbers, silicones and various other syntheticsO Examples of 30 adhesive products Trade Mark for an ethylene-vinyl acetate copolymer resin A g 10~6789 now available which have been found suitable are Minnesota Minlng ~
Manufacturing 415,463 Acrylic, NPE 9ûl Synthetic Rubber, and Dennison Silicone Rubber, Use of adhesives permits relative motion between each of the assembly elements during flexure of cartridgc 10; thus S reducing bending forccs and permitting greater conformity to skin contours. The use of such a yieldingly bonded laminar structure allows bending of cartridge 10 with a minimum geometrical disto~tion while permitting the component parts to return to their normal posit;oning upon the release of applied force. A ~ypical cartr;dge assembly requires 10 . a 9.1 gram shaving force to cause a .05û inch center deflectlon with , respect to the normal plane of the top surface of cap 19. The adhesive strips are preferably about 0.002 inch thick, but may be substantially varied in such dimensions without deleterious effect upon the performance - of the product.

15After disposition of tape strip 12 on top surface ô of sea~
blade 13 having a sharpened edge along its front margin is aligned rear-.
wardly of the front margin of seat 11 and yieldingly held in that position ~ ~ -by strip 12. Perforations S are longitudinally arrayed along its trans-verse le~gth, which perforations act to increase flexibility of blade 13 as well as being used during the edge grinding process; Changes In per-foratlon dimensions and locations may be used to tailor blade 13 flexibility.

Adhesive strip 14 is then placed along the top surface of blade 13 in alignment with its rear margin. In the twin blade design shown in Figure 1, a spacer member 15, again aligned with the rear margln of blade 13, is then bonded to strip 14. Spacer member 15 separates the blades to provide desirable twin blade shavlng geometry.
Spacer 15 Is normally approximately .015 to .020 Inch thick and is .. . .
.: - , : ~ . . :

fabricated from a flexible material. Over spacer 15 is placed adhesive strip 16, blade 17 and adhesive strip 18, all aligned along their rear margins. slade 17, as is the case in blade 13, has perforations 26 along its transverse length to increase flexibility thereof. The width of blade 17 is less than that of blade 13 so that its cutting edge lies rearwardly of the cutting edge of blade 13 and produces the aforementioned desired twin blade shaving geometry. Blades 13 and 17 are preferably approximately .0015 inch thick made of ferritic stainless steel commonly available for blade fabrication. It has been found that thicknesses ranging between .001 and .010 inch may be util-ized but do not realize the same optimal results.
The last element of assembly 10 is cap 19, which is yieldingly held to cap blade 17 by adhesive strip 18 to prevent lifting of cap leading edge 29. Flange members 30 of end walls 31 of cap 19 act to cover the ends of the assembly. In viewing -this completed assembly, it becomes obvious applicants have produced a twin blade cartridge yieldingly bonded together being flexible about an axis parallel to the planes of the blades l3 and 17 and perpendicular to their cutting edges.
A single blade construction conforming to the same functional requirements is shown in Figure 3. Single blade cartridge 40 comprises seat member 11 having integral guard bar 23 and end projections 22 thereon. Adhesive strip 12 is disposed upon planar surface 8 after which blade 13, adhesive strip 14 and cap 19 are in sequence bonded thereto. The single blade cartridge 40 displays the same flexure or bending character-istics as cartridge 10 and produces a blade assembly capable of conforming 1(~76789 to body contours while retaTning substantial)y constant shaving geo~etry.
Referring to Figurè 4, therc is shown a schematic representation of slngle blade shaving geometry utilized in the construction of cartridgc 40.
Thc span S referring to the distance x asured between the tip of blade 13 and a tangent point on comb guard 23 may be selected betwcen approximately 0.030 and o.o80 inch; tangent angle Alpha may be selected betwecn approxi-mately 15 and 40 ; and exposure E may bc selected !n a range betwecn . -.010 and ~.006 inch.

This same geometry may also be reflected in the twin blade cartridge 10 design of Figure 1 by applying the definitions to different reference elements. To explain--the geometry of first blade 13 falls '' within the same range as blade 13 of cartridge 40 if second blade 17 is considered the equivalent part to cap flange 29, i.e., the shaviny angle plane is defined as a plane tangent to the edge of blade 17 and guard bar 23 rather than tangent to cap flange 29 and guard bar 23. Sim;larly, the same construction can be applied to second blade 17 in arriving at ;ts shaving geometry by substituting the edge of blade 13 for the tangent' li'ne of guard 23. In a preferable embodiment based upon the forego!ng premise, the geometry of blades 13 and 17 are selected to be substantially ' 20 the same, namely, a span S of between .030 and .080 inch, a tangent angle Alpha of between 15 and 40, and an exposure E between -.010 a'nd 1.oo6 inch but with the second blade angle selected less than the blade angle.
As the Ihicknesses of blades 13 and/or 17 are altered, the arrangement and dimensioning of the other elements of the cartridge must be altered to achlcve the same or a different desired shaving geometry. It is these gcomctrtcal relatlonships that are maintained relatively constant whlle the cartrldge of the present Inventlon is being flexed through a range of 107f~789 different gending radii, both concave and convex, The preferred embodi-ments ~f both the twin and single blade cartrldges have a tangent anglc of approximatcly 20 to 24, an exposu're of approximatcly -0.004 to ~0.002 inch, and a span of approximatcly .045 to .070 inch.

Refercnce to Figures 5 and 6 demonstrates in a schematic sense the conformity of a bonded cartridge made in accordance with the present tnvention. In Figure 5, cartridge 50, shown as an idealized flat rectangular prism, is conforming to a concavTty in the shaving surfacc with cartridge 50 being moved toward the observer. Cartridge 50 assumes ~0 a complementary convex geometry with its center portion deflect;ng from a'plane containing pivot points 51 and 52 with the entTre surface assuming ' a given radius of curvature about axis 53. In FTgure 6, the samc car-tridge 50 is shown assuming a concave geometry about axis of curyature -54 conforming to a convexity in the shaving surface. As can be seen, lS the center of cartridge 50 deflects below the plane containing pivot ' ' pins 51 and 52 while the ends of cartridge 50 deflect above the same '~
plane, It should be noted that the port;ons of the cartridge extending beyond pivot points 51 and 52 may assume a totally different radius of curvature from that occurring between the same pivot points. Moreover, in confor~ing to undulations of the shaving surfacé, a plurality of : different radii of curvature may be achieved.

Figure 7 shows an alternate embodiment of applicants' novel concept. Here the entire blade assembly, absent the razor blades, of course, is molded as a single integral piece, i.e., seat 61, guard bar 62 and cap 63 are integrally formed of a flexible polymeric material.

.

~076789 The construct;on consists of a series of ribbed structurcs joined by thin flexible webs 67. Slots 65 and 66 are formed one below the other respectively in each rib section of cartr;dge 60 and the second and first blades are disposed in such slots. The blades may be movably pinned or adhesively bonded to the slots to achieve flcxibility and may be arranged to conform to the shaving geometry heretofore set forth.
The same alternative configuration may be utilized in a ~ingle blade design by the elimination of one of the b!ade slots and a commensurate decrease in the vertical dimension of the cartridge.

Applicants have produced a flexible shaving assembly capable '' of conforming to the varying contours of the shaving surface with minimal variations in shaving geometry. The novel cartridge achieves a dynamic flexibility through a range of different positions and forces applied by the user during the act of shaving. It enables the cutting edge to contact an increased skin surface, thereby producing enhanced shaving efficiency without degradation in performance or comfort.
The applicants' invention may be applied to a wide range of varying cartridge designs, for example, the guard bar may'be incorporated directly on the'blade edge by the encompassing of such edge by a wire spirally wound about the blade or the placement of projections along the blade edge'; these variations, as well as other modifications which may become evident to one of ordinary skill in the art, are considered to be within the sCo?e and ambit of applicants~ invention. The foregoing descriptton and draw;n~s are intended to be 111ustrative of appliçants' invention and not in any way delimiting of its scope.

Claims (9)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A blade assembly comprising a flexible seat member having a surface, a flexible blade having a sharpened cutting edge disposed on the surface, and a flexible guard member located forwardly of the cutting edge, the seat, blade, and guard member being yieldingly bonded together and flexible about an axis parallel to the plane of the blade and perpendicular to the cutting edge.

2. The assembly of claim 1 wherein said seat member surface is of substantially planar form, and further including a flexible cap member on the blade having a forward margin located rearwardly of the cutting edge.

3. The assembly of claim 2 wherein the assembly is yieldingly bonded with adhesives selected from the group consisting of acrylics, rubbers and silicones.

4. The assembly of claim 2 wherein the seat member includes a front margin and comprises a series of rib members interconnected by webs, and arrayed orthogonally to the front margin of the seat member.

5. The assembly of claim 4 wherein the guard bar member is a comb guard bar, the teeth of which are formed by forwardly extending portions of the rib members.

6. The assembly of claim 2 wherein the seat, guard bar and cap members are molded from a flexible polymeric material selected from the group consisting of polyvinyl chloride, poly-ethylene, ethylene vinyl acetate, silicone, urethane and thermo-plastic rubbers.

7. The assembly of claim 2 comprising a second blade disposed parallel to and rearwardly of the blade, and inter-posed between the blade and the cap member.

8. The assembly of claim 7 wherein the second blade is yieldingly bonded.

9. The assembly of claim 8 wherein the members are bonded by adhesive strips interposed between each of the members, and the assembly includes a spacer member interposed between the blade and the second blade.