Cutlery – Razors – Combined
Reexamination Certificate
1999-07-29
2001-06-12
Payer, Hwei Siu (Department: 3724)
Cutlery
Razors
Combined
C030S050000, C030S077000
Reexamination Certificate
active
06243951
ABSTRACT:
This invention relates to safety razors and in particular it refers to 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 on the handle to enable the blade unit to be replaced by a fresh blade unit when required. Replacement blade units are also commonly referred to as cartridges. Alternatively, a blade unit may be attached permanently to the handle with the intention that the entire razor should be discarded when the blade or blades have become dulled. Razor blade units generally include guard and cap surfaces for respectively contacting the skin in front of and behind the blade(s), these surfaces serving important roles ill establishing the so-called shaving geometry, i.e. the parameters which determine the blade orientation and position relative to the skin during shaving.
There have been prior proposals to equip a safety razor with a comb-like structure for contacting the skin in front of a blade edge, which structure is in some cases arranged on or to constitute the guard surface, while other arrangements include inclusion of the comb structure in a spacer between a pair of tandem blades. The comb structures are provided with a view to achieving a balance between safety and comfort on the one hand and closeness of shave on the other hand. Examples of prior art comb structures are described in U.S. Pat. No. 3,004,337, 4,272,885 and 5,359,774, in which it is explained that improved safety and comfort come from reduced contact between the skin and blade edge.
The prior art blade units having comb structures are equipped with fixed blades and are not easily adaptable to suit blade units in which blades are mounted to be movable under forces experienced during shaving in order to vary the shaving geometry.
In accordance with the present invention there is provided a safety razor blade unit comprising a frame with guard and cap surfaces thereon, a plurality of blades with substantially parallel blade edges mounted on the frame between the guard and cap surfaces, the blades being carried on respective blade supports for independent movement within the frame for varying the shaving geometry in accordance with forces imparted on the blades during shaving, at least one of the blade supports having rigidly connected thereto elements spaced apart along the blade carried on said blade support and projecting forwardly of the blade edge, the elements having skin contacting portions for contacting the skin immediately in front of the blade and substantially tangential to the blade edge.
The blade units having comb structures according to the prior art compromise closeness in attempting to improve safety and comfort. It has been found that excellent closeness results can be achieved while still benefiting from enhanced safety and comfort, with a preferred embodiment of a safety razor blade unit according to the invention. In the preferred embodiment the forwardly projecting elements have upper surface portions which in side elevation extend rectilinearly to a point spaced from the blade edge by a distance in the range of 0.10 to 0.30 mm. The projecting elements are preferably integral with the blade support, although they can be formed on a member firmly secured to the blade support. In either case the elements can be easily and conveniently incorporated in a blade unit having blades which are movable, and the elements remain effective despite the blade movements which occur during shaving. Furthermore, the elements have skin contacting surfaces which are closely adjacent the blade edge in all cases. Due to the upper surface portions, which can be flat or arched, lying substantially in a common plane with the blade edge, the elements have a tendency to function in similar fashion to skis or runners as they slide over the skin surface thereby guiding the blade for effective contact with the skin while deterring any tendency for blade displacement in a direction longitudinally of the blade edge.
In a preferred construction the projecting elements have flat sides and the lateral edges of the upper surface portions merge smoothly with radiused or divergent flank surfaces extending to the flat sides. These features contribute to the effectiveness of the elements while ensuring comfort is maintained.
Suitably the width of the elements is in the range of 0.1 to 0.3 mm. and the width of the upper skin contacting surface portions is not greater than 0.1 mm, which avoids any tendency for the elements to flatten the hairs against the skin surface.
The elements are preferably positioned with a pitch of less than 2 mm, e.g. in the range of 0.5 mm to 1.5, and a pitch of approximately 1.0 mm is especially appropriate.
To ensure a gentle initial contact between the elements and the skin surface they can be provided with rounded nose portions at their forward ends, these nose portions leading smoothly into the upper surface portions.
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PCT International Search Report, in corresponding PCT/US98/02675, mailed Jun. 15, 1998.
Payer Hwei Siu
The Gillette Company
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