Patent Application
20150013169
The present invention relates to razor cartridges, specifically the arrangement of blades within a razor cartridge.
There are a multitude of razors and razor cartridges currently on the market that have been fine tuned over the years to ensure they provide a close and comfortable shave. More recent razor cartridges on the market have multiple blades (for example, 3, 4, 5, or 6). Increasing the number of blades tends to improve the closeness and comfort of a shave, but leads to other problems. Typically, as additional blades are provided in a cartridge, the distance between adjacent blade edges has been reduced. This reduction in span between adjacent blade edges results in a closer shave, as consecutive blades are able to cut the same hair, with a first blade pulling a hair out of the skin surface while cutting it and then a subsequent blade cutting (and pulling) the same hair before it fully retracts. The reduction in span also provides for a more comfortable shave, as there is less room between blades for skin to bulge. However, there are downsides to reducing the span between adjacent blades, in particular the reduction in space for wash-through of hair and shaving debris.
It is therefore an object of the present invention to provide a razor cartridge that is able to capitalize on the benefits of a reduced span between blades without compromising on e.g. wash-through.
According to a first aspect, there is provided a razor cartridge comprising a housing with a front and a rear; at least two adjacent blades, each pair of adjacent blades having a leading blade and a trailing blade, the leading and trailing blade each having a cutting edge directed towards a front of the housing, the cutting edge of the leading blade being positioned between the cutting edge of the trailing blade and the front of the housing, wherein at least one pair of adjacent blades, and preferably each pair of adjacent blades, independently has
There are multiple benefits to reducing the span compared with conventional razors on the market. For example, a) the reduced span between blades takes better advantage of the hysteresis effect caused when multiple blades are able to cut the same hair, resulting in a closer shave; and b) there is less room for skin to bulge between the blades, significantly reducing the risk of nicks and cuts. The gap provided between the nearest points on adjacent blades mitigates the historical downside of reduced spans—that of limited space for wash-through between blades.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods, and materials are described below.
Other features and advantages of the invention will be apparent from the following detailed description, and from the claims.
While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as forming the present invention, it is believed that the invention will be better understood from the following description which is taken in conjunction with the accompanying drawings in which like designations are used to designate similar or substantially identical elements, and in which:
A span δs is defined between each pair of adjacent blade edges, and a total span δts is defined between the primary blade edge 48 and the final blade edge 50. The span between adjacent blade edges may be the same for each pair of blades in a cartridge, or the span between adjacent blade edges may vary at different points in the cartridge. For example, in a three-blade cartridge having a primary, second and final blade, the span between the primary and second blade edges may be less than, equal to or greater than the span between the second and final blade edges.
The span δs for each pair of adjacent blades is less than 1.0 mm, preferably less than 0.85 mm, more preferably less than 0.75 mm. There are multiple advantages associated with a span δs of less than 1.0 mm. Namely:
To facilitate wash-through between adjacent blades, an inter-blade gap δg is provided between each adjacent pair of blades. Each pair of blades has a leading blade 70 and a trailing blade 72, with the leading blade located nearer the front of the cartridge and the trailing blade located nearer the rear of the cartridge. The inter-blade gap δg measures the distance between the two closest points in each pair of blades. Typically, the distance between blades is shortest between the rear wall 58 of the leading blade 70 and the front wall 56 of the trailing blade 72. More typically, the inter-blade gap will be measured between the bent portion 50 of the leading blade 70 and the cutting portion 30 of the trailing blade 72.
a) The angle α of the cutting portion relative to the skin contact plane Ps of the leading blade;
b) The distance D from the blade edge to a tangent of the back wall of the supporting portion of the leading blade, measured in a direction perpendicular to the tangent;
The gap may be provided by one or both of a combination of the above. The gap δg should be at least 0.15 mm. Preferably, the gap δg is between 0.3 mm, 0.4 mm or 0.5 mm and 0.6 mm, 0.75 mm and 1.0 mm. In embodiments, the span between blade edges in the pair of blades is less than 1.0 mm, thus in preferred embodiments, the distance δg is less than or equal to the span between blades edges of the same pair of blades.
If the distance D is equal to or greater than the span between adjacent blades, as shown schematically in
δg=δs√{square root over (1−cos2)}(α)
According to this definition, to ensure an inter-blade gap δg of at least 0.15 mm, and for a span of less than 1.0 mm, α should be at least 9°.
The impact that the angle has is shown illustratively in
In preferred embodiments, the distance D is less than the span.
Where D is less than the span, then the gap is provided by a combination of the distance above, based on the angle of the leading blade, the span, and the difference between the span and distance D. Specifically, where D is 0.15 mm or more less than the span, then this distance D alone provides sufficient space for wash-through of hair and other shaving debris.
The distance D is, at least in part, determined by the length of the cutting portion, the radius of curvature between the cutting portion and the supporting portion and the angle between the two. To ensure a suitable and strong cutting surface, the cutting portion has a length of at least 0.15 mm. If the cutting portion is too small, there is likely to be insufficient space to form an appropriate blade edge. As the angle between the supporting portion and the cutting portion is decreased, the distance D is reduced. In preferred embodiments, the supporting portion of the blade is held in position vertically within the housing. In such embodiments, the angle between the supporting portion and the cutting portion is determined by the required blade plane angle.
The radius of curvature is between 0.20 mm and 0.60 mm, preferably 0.25 mm and 0.45 mm. The radius of curvature influences the strength of blade structure, for example, reducing the radius of curvature provides for a sturdier overall blade structure and reduces the overall area of the curved portion. Specifically, having a smaller radius of curvature permits a more preferable ratio of length of cutting portion to distance D.
The blade has a thickness T of between 0.05 mm and 0.15 mm, preferably 0.05 mm and 0.10 mm, measured between the front and back walls of the blade. This provides a blade thick enough to withstand typical forces experienced during shaving by minimizing the overall space occupied by the blade. In this respect, reducing the thickness of the blade allows additional space between corresponding points on adjacent blades through which shaving hair and debris may be washed.
Blades of a thickness described above are more prone to flexing under typical shaving forces compared with more traditional blades welded to thicker blade supports. Accordingly, as shown in
The guard is typically a unitary molded member that can be formed of a rigid plastic at the bottom and an elastomeric material at the top. The elastomeric material is chosen to provide flexibility for ribs, e.g. as is described in detail in U.S. Pat. No. 5,249,361. The tips of ribs are typically in a plane that is about half-way between a plane that passes through the cutting edges of the blades and the top of clips provided at the ends of the blades. The raised tips (relative to the cutting edges) may provide effective shielding of the blades and may also exert a traction force on the skin to stretch it and raise hairs before the primary blade, thus reducing overall cutting force.
During shaving, the blades may be independently resiliently movable with respect to housing 12. The housing may pivot with respect to the handle with the result that the cutting edges will follow the contours of the skin surface. It may be advantageous to set the blades to have different exposures relative to the skin contact plane as described in U.S. Pat. No. 6,212,777. The exposure is determined by the distance of the blade tip from the skin contact plane. Additionally, different blade spans can be set between groups of two adjacent elements that contact the skin, e.g. as also described in detail in U.S. Pat. No. 6,212,777.
According to some embodiments of the invention, a razor is provided, which generally comprises a razor cartridge according to the invention as described hereinabove, and a handle (or grip portion) permanently or removably attached to the cartridge. The razor can be manual or power driven and can be used for wet and/or dry application. The razor cartridge may be replaceable and/or pivotally connected to the handle (e.g. via a cartridge connecting structure) and in turn or independently permanently fixed to a handle (e.g. a disposable razor). In some embodiments, the cartridge connecting structure includes at least one arm to releasably engage the razor cartridge.
The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm”.
Every document cited herein, including any cross referenced or related patent or application, and any patent application or patent to which this application claims priority or benefit thereof is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.
While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 13175865.8 | Jul 2013 | EP | regional |
| 14170922.0 | Jun 2014 | EP | regional |
