Patent Description:
In general, a cartridge or blade unit of a safety razor has 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 cartridge is attached. Some shaving razors are provided with a spring biased cartridge that pivots relative to the handle to follow the contours of the skin during shaving. The cartridge may be mounted detachably on the handle to enable the cartridge to be replaced by a fresh cartridge 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 cartridges usually include a guard which contacts the skin in front of the blade(s) and a cap for contacting the skin behind the blade(s) during shaving. The cap and guard may aid in establishing the so-called "shaving geometry", i.e., the parameters which determine the blade orientation and position relative to the skin during shaving, which in turn have a strong influence on the shaving performance and efficacy of the razor. The cap may comprise a water leachable shaving aid to reduce drag and improve comfort. The guard may be generally rigid, for example formed integrally with a frame or platform structure which provides a support for the blades. Guards may also comprise softer elastomeric materials to improve skin <NUM> stretching.

In addition, covers have been developed that fit over shaving cartridges to facilitate cutting the hair to a specified length. These covers also guard the skin by raising the blades from the surface of the skin and thus limiting contact. However, since these covers are intended to be mounted over existing shaving razor cartridges that intended to shave the skin, the trimmer performance (i.e., cutting hair to length) of the cover is limited and not efficient. Thus, there is a need for a safety shaving razor that provides safe and efficient of cutting hair to a specified length. An example of prior art is given by the patent documentation <CIT>.

In one aspect, the invention features, in general a subassembly for a shaving razor cartridge with a base having a front wall with a top surface and a rear wall with a top surface. At least one blade is mounted to the base between the front wall and the rear wall. The at least one blade has a cutting edge positioned at least <NUM> above a plane tangent to the top surface of the front wall and the top surface of the rear wall.

In another aspect, the invention features, in general a method of assembling a shaving razor cartridge by providing a base having a front wall with a top surface and a rear wall with a top surface. At least one blade having a cutting edge is mounted to the base between the front wall and the rear wall. The cutting edge is positioned at least <NUM> above a plane tangent to the top surface of the front wall and the top surface of the rear wall. A cage having a plurality of ribs is mounted to the base.

In another aspect, the invention features, in general a shaving razor cartridge with a base having a front wall with a top surface. A cage is fixed to the base. The cage has an upper skin contacting surface with a plurality of ribs defining a plurality of open slots and a front face generally transverse to the upper skin contacting surface. The front face has a lower surface interconnecting a plurality of ribs that define a plurality of open slots extending into the front face and are communication with the open slots of the upper skin contacting surface. At least one blade is mounted to the base. The blade has a cutting edge positioned above the upper skin contacting surface and immediately behind the front wall. The lower surface of the front face is positioned a vertical distance below the cutting edge.

Other features and advantages of the present invention, as well as the invention itself, can be more fully understood from the following description of the various embodiments, when read together with the accompanying drawings, in which:.

Referring to <FIG> and <FIG>, front and rear perspective views of a shaving razor cartridge <NUM> are shown, respetively. The shaving razor cartridge <NUM> may be mounted to a handle (not shown). The shaving razor cartridge <NUM> may be removable or permanently mounted to the handle. For example, the shaving razor cartridge <NUM> may be detachably mounted on a handle to enable the shaving razor cartridge <NUM> to be replaced by a fresh shaving razor cartridge <NUM> 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. The shaving razor cartridge <NUM> may include a housing <NUM>. The housing <NUM> may be molded out of a polymeric material or manufactured from other materials, such as metal. The housing <NUM> may have an upper skin contacting surface <NUM> and a front face <NUM> that is transverse to the upper skin contacting surface <NUM>. The upper skin contacting surface <NUM> may define a plurality of open slots <NUM> that are in communication with a plurality of corresponding open slots <NUM> defined by the front face <NUM>. The open slots <NUM> may extend all the way to a rear face <NUM> (<FIG>) The open slots <NUM> may be defined and interconnected by a lower surface <NUM> of the front face <NUM>. Accordingly, when hairs contact the front face <NUM>, they are directed immediately to the open slots <NUM> (i.e., the open slots <NUM> extend into the front face <NUM>). The open slots <NUM> and <NUM> may be separated by corresponding ribs <NUM>. The ribs <NUM> may extend continuously along the upper skin contacting surface <NUM> and down the front face <NUM>. Accordingly, the front face may be defined by a plurality of ribs <NUM> and the lower surface <NUM> to form the open slots <NUM>. The ribs may have a width "w1" of about <NUM> to about <NUM> and preferably about <NUM> to about <NUM>. The ribs <NUM> may be spaced apart (i.e., width of the slots <NUM> and <NUM>) by about <NUM> to about <NUM> and preferably about <NUM> to about <NUM>. If the spacing between adjacent ribs is too great, the blades may shave the philtrum (the vertical indentation in the middle area of the upper lip) rather than cutting the hair to length (e.g., the philthrum may sag between the ribs <NUM>). In certain embodiments, the width "w1" may less than the distance between the ribs <NUM>. As will be described in greater detail below, a ratio of the width to height of the ribs <NUM> should be sufficient to prevent the ribs <NUM> from breaking or deforming during use. Furthermore, the spacing of the ribs <NUM> (i.e., slot width) and the width of the ribs <NUM> may impact the efficiency of the blades to cut hair. For example, the width of the slots <NUM> and <NUM> should be large enough for hairs to pass through and the width of the ribs <NUM> should be large enough to provide sufficient strength without trapping a surplus of hairs. The dimensions of the ribs <NUM> may also prevent skin from sagging between the ribs <NUM> and contacting the skin during a shaving stroke.

As shown in <FIG>, one or more blades 24a 24b and 24c may be mounted within the housing <NUM>, as shown in <FIG>. Each of the blades 24a 24b and 24c may have a corresponding cutting edge 26a 26b and 26c. The first blade 24a and first cutting edge 26a may be immediately adjacent the ribs <NUM> of the front face <NUM>. Although three blades 24a, 24b and 24c are shown, the razor cartridge <NUM> may have more or fewer blades <NUM> depending on the desired performance and cost of the razor cartridge <NUM>. The open slots <NUM> and <NUM> may extend transverse to the cutting edges 26a 26b and 26c. The blades 24a 24b and 24c may be secured to the housing <NUM> with one or more clips 28a and 28b. The blades <NUM> may be fixed in the housing <NUM> or may be resiliently mounted such that the blade members <NUM>, (e.g., respective cutting edges <NUM>) are biased against the clips 28a and 28b. The clips 28a and 28b may aid in retaining the blades 24a, 24b and 24c in an up and down direction (i.e., toward and away from the upper skin contacting surface <NUM>. The clips 28a and 28b may comprise a metal, such as aluminum, but plastic may also be used. The clips 28a and 28b may also be interconnected to form a one-piece assembly. Other assembly methods known to those skilled in the art may also be used to secure and/or mount the blades 24a, 24b and 24c to the housing <NUM> including, but not limited to, wire wrapping, cold forming, hot staking, insert molding, ultrasonic welding, and adhesives. As will be described in greater detail below, the ribs <NUM> may prevent the cutting edges 26a, 26b and 26c from contacting the skin during a stroke, so only hair is cut not skin.

Referring to <FIG>, an assembly view of the shaving razor cartridge <NUM> is illustrated. In certain embodiments, the housing <NUM> may comprise a two-piece assembly. For example, the housing <NUM> may comprise a base <NUM> (e.g., a lower portion) and ibta cage <NUM> (e.g., an upper portion) that is mounted over the base <NUM>. In certain embodiments, the base <NUM> may be permanently fixed to the case <NUM>. Accordingly, the cage <NUM> may define the upper skin contacting surface <NUM> and the blades 24a, 24b and 24c may be mounted to the base <NUM>. In certain embodiments, the cage <NUM> may secure the blades <NUM> within the base <NUM> (with or without the clips 28a and 28b). For example, the clips <NUM> may provide either a temporary or an extra measure of securement for the blades 24a, 24b and 24c.

The base <NUM> may have a front wall <NUM> and a rear wall <NUM> with respective top surfaces <NUM> and <NUM>. The first cutting edge 26a may be immediately behind the front wall <NUM> to facilitate the unobstructed passage of hair to the first cutting edge 26a. One or more of the top surfaces <NUM> and <NUM> may be recessed relative to the cutting edges 26a, 26b and 26c. The top surfaces <NUM> and <NUM> may extend along a length "L1". It is understood that the front wall <NUM> and the rear wall <NUM> may have one or more projecting features to aid in securement of the base <NUM> to the cage <NUM>. The top surfaces <NUM> and <NUM> may extend between and positioned below the clips 28a and 28b. The top surface <NUM> being recessed may allow for an open area in front of the first cutting edge 26a so hair is not trapped, as well as provide for an area on the housing for the clips 28a and 28b to rest above the top surface <NUM>. For example, one or more of the top surfaces <NUM> and <NUM> may be recessed relative to the first cutting edge 26a by more than <NUM>, such that the top surface <NUM> and <NUM> do not interfere with or touch the skin, during trimming of hair. As will be explained in greater detail below, all of the blades 24a, 24b, and 24c may be mounted to the base <NUM> such that the cutting edges 26a, 26b and 26c are positioned above the top surface <NUM> along the length "L1". In certain embodiments, L1 may be about <NUM> to about <NUM>. Accordingly, all the cutting edges 26a, 26b and 26c are not protected by a guard and cap as traditional razor cartridges and thus all the shaving forces would be applied directly to the cutting edges 26a, 26b and 26c because the top surfaces <NUM> and <NUM> are recessed such that they do not act as a guard and cap to support (e.g., contact) the skin. However, the cage <NUM> may be mounted over the base <NUM> to prevent the cutting edges <NUM> from contacting the skin, thus resulting in a very safe shave by cutting the hairs to a pre-determined length. The clips 28a and 28b may be mounted to the base <NUM> prior to the cage <NUM> being mounted to the base <NUM>. The cage <NUM> may define a pair of openings 38a and 38b dimensioned to receive the corresponding clips 28a and 28b. The cage <NUM> may be spaced apart from the clips 28a and 28b, to facilitate simple assembly. For example, the openings 38a and 38b may allow the clips 28a and 28b to be secured to the housing <NUM> either before or after the cage <NUM> is mounted to base <NUM>. The openings 38a and 38b may allow the cage <NUM> to directly contact the cutting edges 26a, 26b and 26c by not resting on top of the clips 28a and 28b. In certain embodiments, the cage <NUM> would rest directly against the cutting edges 26a, 26b and 26c, thus potentially eliminating the need for the clips <NUM>. Furthermore, hair and shaving debris may become trapped between the cage <NUM> and the cutting edge <NUM> if the cage <NUM> rested on top of the clips <NUM> and not the cutting edges 26a, 26b and 26c. The openings 38a and 38b may be enclosed and extend between the front face <NUM> and a rear face <NUM>. As also shown in <FIG>, the rear face <NUM> may interconnect the ribs <NUM> at a rear of the housing <NUM> (e.g., cage <NUM>) and lower surface <NUM> may interconnect the ribs <NUM> at a front of the housing <NUM> (cage <NUM>) to reinforce the ribs <NUM>.

Referring to <FIG>, a subassembly <NUM> is shown which may be incorporated in the shaving razor cartridge of <FIG>. The subassembly <NUM> may include the base <NUM>, blades 24a, 24b and 24c and clips 28a and 28b. The blades 24a, 24b and 24c may be mounted to the base <NUM> between the front wall <NUM> and a rear wall <NUM>. In certain embodiments, the length "L1" of the top surface <NUM> of the front wall <NUM> may be at least <NUM>% of an overall length "L2" of the blades 24a, 24b and 24c that are exposed (e.g., distances between the clips 28a and 28b). The top surface <NUM> may be bounded on lateral ends <NUM> and <NUM> by retaining walls <NUM> and <NUM>. The retaining walls <NUM> and <NUM> may extend above the top surface <NUM> to facilitate the positioning and securement of the clips 28a and 28b to the base <NUM>. For example, each clip 28a and 28b may be positioned between one of the retaining walls <NUM> and <NUM> and a corresponding lateral wall <NUM> and <NUM>.

Referring to <FIG>, a cross section view of the subassembly <NUM>, taken generally along the line <NUM>-<NUM> of <FIG> is illustrated. The top surface <NUM> on the front wall <NUM> of the base <NUM> may be positioned a vertical distance of at least <NUM> below the cutting edges 26a, 26b and 26c (e.g., a cutting plane <NUM>). In certain embodiments, the vertical distance d1 may be about <NUM> to about <NUM>. The position of the top surface <NUM> may allow the hair to reposition itself in a more upright position as hair is cut (e.g., by the first cutting edge 26a). For example, the top surface <NUM> may push down and trap long hairs in front of the blades <NUM>, if the top surface <NUM> was positioned too close to the cutting plane <NUM> (or the first cutting edge 26a), thus negatively impacting cutting efficiency, especially for longer hairs than tend to lay flat on the skin. One or more of the cutting edges 26a, 26b and 26c may be positioned a vertical distance "d2" above a plane P1 tangent to the top surface <NUM> of the front wall <NUM> and a top surface <NUM> of the rear wall <NUM>. The distance d2 may be greatest at the first cutting edge 26a closest to the front wall <NUM> and the least closest to the rear wall <NUM>. It is believed, without being held to theory, that increasing d2 closer to the front wall <NUM> improves cutting efficiency. After the hair is trimmed by the first cutting edge 26a, it is less likely to lay flat because it is shorter, thus d2 may be less at the second cutting edge 26b and even less at the cutting edge 26c closest to the rear wall <NUM>. In certain embodiments, d2 may be about <NUM> to about <NUM> as measured at any of the cutting edges 26a, 26b and 26c.

The shaving efficiency of the shaving razor cartridge <NUM> (<FIG>) may be enhanced by improving rinsability. Traditional shaving razor cartridges rely on smaller distances between cutting edges or intermediate guards between adjacent blades for improved comfort because pressure is distributed between the cutting edges 26a, 26b and 26c. However, the ribs <NUM> (<FIG>) absorb all of the pressure from the skin, not the cutting edges 26a 26b and 26c, which allows the cutting edges 26a 26b and 26c to be spaced further apart from each other. In certain embodiments, distances "d3" and "d4" between a pair of immediately adjacent cutting edges 26a, 26b and 26c may be greater than <NUM>, for example, about <NUM> to about <NUM>, or about <NUM> to about <NUM>, which may allow for even more effective rinsing by providing an open gap (as best seen in <FIG>) between immediate cutting edges 26a, 26b and 26c, without sacrificing trimming efficiency or comfort.

Referring to <FIG>, a cross section view of the shaving razor cartridge <NUM>, taken generally along the line <NUM>-<NUM> of <FIG> is illustrated. The cage <NUM> may be mounted to the sub-assembly <NUM> (i.e., the base <NUM>). The housing <NUM> (e.g., the base <NUM> and the cage <NUM>) may allow for hair to freely pass through the slots <NUM> (<FIG>) of the front face <NUM>. The upper skin contacting surface <NUM> and the front face <NUM> may intersect at an exterior angle "A1" that is less than <NUM> degrees, for example, about <NUM> degrees to about <NUM> degrees to facilitate the passage of hair through the slots <NUM> (<FIG>) of the front face <NUM>. The intersection of the front face <NUM> and the upper skin contacting surface <NUM> may form a radius R1 of the ribs <NUM>. In certain embodiments, R1 may be about <NUM> to about <NUM> and preferably about <NUM> to about <NUM>. The lower surface <NUM> may be positioned a vertical distance "d5" of at least <NUM> below the cutting edges 26a, 26b and 26c (e.g., about <NUM> to about <NUM>). The rear face <NUM> may have a top surface <NUM> extending between the ribs <NUM> (see also <FIG>) that is positioned a vertical distance "d6" below the cutting edges 26a, 26b and 26c, which may help release the hairs freely (i.e., prevent from hairs being flattened down during a shaving stroke), thus allowing for more efficient trimming of hair.

The upper skin contacting surface <NUM> may have an opposing interior surface <NUM> (e.g., height of the ribs <NUM>). The length of the hair left after trimming with the shaving razor cartridge <NUM> may be determined by a vertical distance "d8" measured from the upper skin contacting surface <NUM> to the opposing interior surface <NUM> (e.g., if the cutting edges 26a, 26b, 26c are in contact with the opposing interior surface <NUM>). It is understood that the cutting edges 26a, 26b, 26c may contact or be spaced apart from the opposing interior surface <NUM>. The vertical distance "d8" may be about <NUM> to about <NUM> and more preferably about <NUM> to about <NUM>. If d8 is too small, skin may bulge between the ribs <NUM> and contact the skin, thus cutting the hair too short. Furthermore, hair longer than <NUM> tends to lay flat and thus will not be cut if d8 is greater than <NUM>.

It is believed, without being held to theory, that increasing the vertical distance d5 and d6 improves cutting efficacy by minimizing interference of the hair before it is cut by the first cutting edge 26a (for d5) after it is cut by the last cutting edge 26c (for d6). Accordingly, the exposure of the cutting edges 26a, 26b and 26c may be determined by d8 (e.g., the height of the ribs <NUM>) and not a feature such as a guard in front of the blades that can push hairs down against the skin making them more difficult to trim. Guards contacting the skin do not present such an issue for typical shaving razors because the cutting edges are contacting and shaving the skin (i.e., cutting hair at or below skin level). Accordingly, the cutting edges are able to contact and cut the hairs that may lay flat, lift them up and cut them. However, cutting the hairs above skin level is more difficult because the cutting edges may not be able to reach hairs that lay flat. Accordingly, the housing <NUM> may define a horizontal gap <NUM> extending from the first cutting edge 26a to a front interior face <NUM>, opposing the front face <NUM>. In certain embodiments, the horizontal gap <NUM> may be about <NUM> to about <NUM> and preferably about <NUM> to about <NUM>. The gap <NUM> may allow for improved rinsing and allow longer trimmed hairs to rinse out through the housing <NUM>. The gap <NUM> may also allow for hairs to release and be presented to the first cutting edge 26a in a more upright position. The front wall <NUM> and top surface <NUM> may be recessed and thus not extend into the gap <NUM>. It is understood that the lateral end walls <NUM> and <NUM> (<FIG>) are positioned laterally of the bottom surface <NUM> and thus also does not extend into the gap <NUM>.

The positioning of the ribs <NUM> (<FIG> and <FIG>) over the cutting edges 26a, 26b and 26c helps prevent the skin from contacting the cutting edges 26a, 26b and 26c and eliminates the need of a guard bar in front of the cutting edges 26a, 26b and 26c to support the skin. For example, the height and the spacing of the ribs <NUM> may prevent skin from bulging between the ribs and contacting the cutting edges 26a, 26b and 26c. Furthermore, the ribs <NUM> (<FIG> and <FIG>) may also allow the cutting edges 26a, 26b and 26c to be spaced further apart from each other because the cutting edges 26a, 26b and 26c do not exert pressure against the skin.

Claim 1:
A subassembly (<NUM>) for a shaving razor cartridge (<NUM>) comprising:
a base (<NUM>) having a front wall (<NUM>) with a top surface (<NUM>) and a rear wall (<NUM>) with a top surface (<NUM>);
at least one blade (24a, 24b and 24c) being mounted to the base between the front wall and the rear wall, the at least one blade having a cutting edge (26a, 26b and 26c);
wherein the top surface on the front wall of the base is positioned a vertical distance of at least <NUM> below the cutting edge, characterized in that the subassembly (<NUM>) further comprises a cage (<NUM>) fixed to the base (<NUM>), the cage having an upper skin contacting surface (<NUM>) and a front face (<NUM>) that are defined by a plurality of ribs (<NUM>) forming a plurality of open slots (<NUM>, <NUM>).