RAZOR HEAD

Abstract: A razor head adapted to be pivotally mounted to a razor handle comprises an arcuate cam (40) defining a cam follower track (41) which can be engaged by a cam follower in the handle. The cam (40) is configured such that the biasing forces are substantially even throughout the arc of pivotal movement. This results in maintaining a constant cartridge orientation relative to the user's face after the initial orientation has been established.

Description: This invention relates to a razor head adapted to be pivotally mounted to a razor handle. Razors with pivotting blade units are well known in the art and, in fact, the concept extends back more than 50 years. The rationale behind the recent generation of pivotting cartridge razors is that when the razor is used the blade assembly responds to shaving forces and pivots to provide a shaving angle of skin to blade which is constant throughout the shave. Examples of pivotting cartridge patents are set our below. US-A-3,938,247 discloses a razor handle with a convex-concave combination which pivots in response to shaving forces when an otherwise stationary cartridge is attached. US-A-3,935,639 describes an arcuately convex cartridge which slides along mating guard rails attached to a concave extension of a razor handle. This assembly includes biasing means which directs the cartridge towards a "neutral" centre position between the pivotting extremes. US-A-4,403,414 describes a razor in which the handle forms a concave seat and the cartridge rotates within the seat. US-A-4,152,828 describes an off-centre universal joint on the handle designed to mate with a suitable receptacle on a cartridge and is biased to resume automatically a neutral position between the extreme pivot ranges of the joint. US-A-4,253,235 describes cams disposed on journal arms extending outward from a razor handle for providing biasing action for a pivotal cartridge assembly. US-A-4,282,650 and US-A-4,282,651 describe a pivotal cartridge featuring a centrally mounted pivot bar which is attached to a razor handle by a sliding gate. US-A-4,057,896 discloses a razor cartridge which is joined to a razor handle by pivotal bearing means with the bearings positioned near either end of the bottom of the cartridge. Positioned between the pivotal bearing means on the cartridge is a complex cam surface consisting of two oppositely inclined surfaces intersecting to form a dihedral angle. This cam is tracked by a cam follower on the handle which is biased by means of oppositely disposed flexible cam arms positioned on either side of the central cam arm. US-A-4,083,104 and US-A-4,026,016 disclose a razor cartridge such as that depicted in US-A-4,057,896. Also disclosed therein is the configuration for the razor cartridge which has been commercially successful. US-A-4,083,104 discloses a razor head having the features of the precharacterising clause of claim 1. This cartridge, rather than having the complex multi-faceted cam face of US-A-4,057,896 features a V-shaped profile with a flat surface which is engaged by a biased bullet shaped cam follower extending from the handle when the cartridge is attached. This combination along with others in the prior art utilizes the biasing force of a cam follower in a handle to direct the cartridge towards a neutral, i.e., centre position between the extremes of the pivot arc formed by the cartridge during shaving. When the razor is removed from the face, the force exerted against the bias is also removed and the orientation of the cartridge then returns to one in which the cam follower is positioned in the joint of the V-shaped cam. This biasing centre return is objectionable to many shavers who might otherwise prefer to change the cartridge orientation during shaving, because there is no establishment of the changed orientation with a series of strokes. The user is, as a result, constantly positioning the razor against the bias rather than having once established a suitable shading position having that position maintained throughout the shaving operation. According to one aspect of the invention there is provided a razor head adapted to be pivotally mounted to a razor handle, said razor head having at least one blade having a blade edge, blade supporting means for supporting the or each blade, pivotting means adapted to permit the head to pivot relative to said handle, and a cam having a face defining a cam follower track characterised in that the cam is of arcuate cross-section and defines a cam follower track which is in the form of a continuous outward curve to provide substantially even biasing forces throughout the arc of pivotal movement of the head and substantially eliminate biasing forces directed to return the head to a central, neutral position. Advantageously the radius of curvature of the cam face is between substantially 0.05 in. (0.13 cm) and substantially 0.120 in. (0.31 cm). Preferably the cam face is flat. The razor head may further comprise a cap overlying the or each blade. preferably two blades are provided, the blades being maintained in a spaced relationship. A guard bar may be provided which extends outward from the blade supporting means beyond the exposed blade edge. Means can be provided for joining the cap, the or each blade, and the blade supporting means in predetermined spatial relationship. Desirably the blade support means has a bottom profile with a substantially rectangular perimeter; preferably the pivotting means forms part of the profile. The pivotting means may be adapted to engage the handle and to attach the head to the handle. Preferably the pivotting means is positioned at or adjacent to each end of the razor head. The cam is desirably disposed between the pivotting means at each end of the razor head. The razor head may be removably secured to the handle or may be integral with the handle. Thus, the invention is applicable to a razor head in the form of a cartridge for attachment to the razor handle. The invention is also applicable to a disposable razor having a handle with integral head. According to another aspect of the invention there is provided a cartridge for a pivoting head razor said razor including a razor handle, said razor handle including means for pivotally attaching said cartridge, and biased cam follower means, said cartridge comprising in combination: a) at least one blade having a blade edge; b) a cap overlaying said blade; c) a blade seat for supporting said blade; d) a guard bar extending outward beyond the exposed blade edge from said seat; and e) means for joining said blade, seat and cap in a predetermined spatial relationship, with said blade seat having a bottom profile with a substantially rectangular perimeter, said profile including pivotal attachment means for engaging said handle positioned at or near each cartridge end, and a cam positioned between said attachment means, said cam having a flat face defining a cam follower track characterised in that the cam is arcuate in cross-section and the flat face defining the cam follower has a continuous outward curve to provide substantially even biasing forces throughout the arc of pivotal movement of the head and substantially eliminate biasing forces directed to return the head to a central, neutral position. Preferably two of said blades are provided, the blades being maintained in a spaced relationship. Advantageously the radius of curvature of the cam face is between substantially 0.05 in. (0.13 cm) and substantially 0.120 in. (0.31 cm). According to a further aspect of the invention there is provided a razor head adapted to be pivotally mounted to a razor handle, and arcuate cam means engageable by the razor handle, the arcuate cam means providing substantially even biasing forces throughout the arc of pivotal movement. The balancing of biasing forces results in maintaining the cartridge orientation relative to the face after the initial orientation has been established. Reference is now made to the accompanying drawings, in which:- Figure 1 is an exploded perspective view shown from below of a razor head according to the invention; and Figure 2 is an enlarged view along lines 2-2 of Figure 1. An exploded view of a razor head according to the invention in the form of a cartridge is depicted in Figure 1. The cartridge comprises two blades 12 with edges 13; the blades 12 are separated by a spacer 14 to define a cutting system 10. A cap 8 is provided with a series of four stakes 16 which extend through the cutting system 10, by means of openings defined by elongated slots 18 in blades 12, and by means of essentially symmetrical circular openings 15 in the spacer 14. The stakes 16 extend downward into receptacles in the form of apertures 24. The apertures 24 are provided in blade supporting means in the form of a blade seat 20. When the cartridge is completely assembled flanges 30 of the cap 8 are spaced above undercut portions 29 of the seat 20; the undercut portions 29 form a ledge. The cap 8 and set 20 are transversely longer than the cutting system 10 and the mating of flanges 30 and undercut portions 29 surrounds the side edges of the cutting system 10 to prevent user contact with the sides of the blades 12. The bottom surface of seat 20 features stop means in the form of stops 22, 22′, and 23, 23′ positioned slightly outboard of journal bearing means 21, 21′. The journal bearing means 21, 21′ engage journalling faces of razor handle arms (not shown) to maintain attachment between the handle (not shown) and the cartridge and also provide for a pivotting motion. Thus, the journal bearing means 21, 21′ serve as pivotting means to enable the cartridge to pivot relative to the razor handle. Also the journal bearing means 21, 21′ serve as attachment means to enable the cartridge to be attached to the razor handle. The stops 22, 22′ and 23, 23′ define the limit of the pivot arc. The razor cartridge thus far described is conventional and well known in the art. The cartridge further includes a cam 40 having cam surface 41, which defines a cam follower track in which a cam follower (not shown) provided on the razor handle moves. Unlike prior art cams, the cam 40 is outwardly arcuate in configuration and provides a flat face for a cam follower on the razor handle to travel along. Stops 42, 42′ are provided on the cam 40 to define the length of arc of the cam surface 41. By providing a cam 40 with an outwardly arcuate travel path for the cam follower, and a small radius of curvature, movement of the pivotting cartridge after attachment to the handle and in response to shaving forces provides the optimum position of orientation for the blades themselves. When the user applies a shaving stroke the orientation of the cartridge changes in response to the stroke. Contrary to the conventional V-shaped cam previously employed in cartridges, when the razor is lifted from the face, there is no biasing force directing the cartridge back to a central, i.e., neutral position in the pivotting arc. As a result, when the user shaves a first stroke and returns after lifting the razor from his face for a second stroke the orientation of the cartridge does not change in response to the elimination of the resistance of the face to the biasing force applied to the cam 40. Radii of curvature between about 0.05 in. (0.13 cm) and about 0.120 in (0.31 cm) define an optimum range for the cam radius which is particularly suited for elimination of biasing forces directed towards cartridge return. Greater radii of curvature will provide a greater biasing force. Smaller radii of curvature will reduce the pivot arc. One of the important features of the cam of this invention is that it can be utilized with cartridges which are identical to the V-cam cartridge in every other way and can be engaged by razor handles currently available having biased cam followers designed to engage cartridges with V-shaped cams; thus, the cam follower on the handle can have the bullet shape described above. These features mean that no substantial retooling or reinvestment is involved in the commercial utilization of the cartridge having the unique cam described above. Although the above specific description relates to a razor cartridge, the invention may also be applied to disposable razors having a handle with an integral razor head.

Claims: A razor head adapted to be pivotally mounted to a razor handle, said razor head having at least one blade (12) having a blade edge (13), blade supporting means (20) for supporting the or each blade, pivotting means (21,21') adapted to permit the head to pivot relative to said handle, and a cam (40) having a face defining a cam follower track (41) characterised in that the cam (40) is of arcuate cross-section and defines a cam follower track (41) which is in the form of a continuous outward curve to provide substantially even biasing forces throughout the arc of the pivotal movement of the head and substantially eliminate biasing forces directed to return the head to a central, neutral position. A razor head according to Claim 1, characterised further by a cap (8) overlying the or each blade (12), a guard bar extending outward from the blade supporting means (20) beyond the exposed blade edge (13), and means (16) for joining the blade (12), blade supporting means (20) and cap (8) in predetermined spatial relationship. A razor head according to Claim 2, characterised in that the blade supporting means (20) has a bottom profile with a substantially rectangular perimeter, and said pivotting means (21,21') forms part of said bottom profile. A razor head according to Claim 3, characterised in that the pivotting means (21,21') is adapted to engage the handle, and to attach the head to the handle, and is positioned at or adjacent to each end of the razor head, and characterised in that the cam (40) is disposed between the pivotting means (21,21') at each end of the razor head. A razor head according to any preceding claim, characterised in that two of said blades (12) are provided, said blades (12) being maintained in a spaced relationship. A razor head according to any preceding claim, characterised in that the radius of curvature of said cam face (41) is between substantially 0.05 in. (0.13 cm) and substantially 0.12 in. (0.31 cm). A razor characterised by a handle, and a razor head according to any preceding claim, said razor head being provided on said handle. A razor according to Claim 7, characterised in that said razor head is removably secured to said handle. A razor according to Claim 7, characterised in that said razor head is integral with said handle. A cartridge for a pivoting head razor said razor including a razor handle, said razor handle including means for pivotally attaching said cartridge, and biased cam follower means, said cartridge comprising in combination: a) at least one blade (12) having a blade edge (13); b) a cap (18) overlaying said blade (12); c) a blade seat (20) for supporting said blade (12); d) a guard bar extending outward beyond the exposed blade edge (13) from said seat (20); and e) means (16) for joining said blade (12), seat (20) and cap (8) in a predetermined spatial relationship, with said blade seat (20) having a bottom profile with a substantially rectangular perimeter, said profile including pivotal attachment means (21,21') for engaging said handle positioned at or near each cartridge end, and a cam (40) positioned between said attachment means (21,21'), said cam (40) having a flat face (41) defining a cam follower track characterised in that the cam (40) is arcuate in cross-section and the flat face defining the cam follower track (41) has a continuous outward curve to provide substantially even biasing forces throughout the arc of pivotal movement of the head and substantially eliminate biasing forces directed to return the head to a central, neutral position.

Inventors: FERRARO, FRANK A.
Applicants: WARNER-LAMBERT COMPANY
Application year: 1987
Main classification: B26B21
IPC codes: B26B21