Abstract:
The invention is directed to a shaving foil for a shaving system of a shaving apparatus, in which the shaving foil cooperates with an undercutter adapted to be driven relative to the shaving foil. The shaving foil includes a perforate region comprised of a plurality of hair-receiving apertures, wherein said apertures form a quasi-periodic pattern executed in accordance with a Penrose parquet.

Description:
RELATED APPLICATIONS 
   This application is a continuation of PCT application number PCT/EP02/08272, filed Jul. 25, 2002, which claims priority from German application serial no. 101 39 209.5, filed Aug. 9, 2001. The entire contents of the above PCT application are herein incorporated by reference. 

   TECHNICAL FIELD 
   This invention relates shaving foil patterning. More particularly, the invention relates to patterning a shaving foil to include at least one perforate region comprised of a plurality of hair-receiving apertures. 
   BACKGROUND 
   Known shaving foils are usually equipped with a periodically recurring aperture pattern in which the aperture cross-sections have a hexagonal, honeycomb-shaped geometry, a slot-shaped and/or circular geometry, or polygonal geometry—in particular equilateral polygonal geometry. Complete parqueting of the foil surface is easy to accomplish with honeycomb-shaped apertures. At the same time, foils having honeycombed-shaped apertures can include a very favorable ratio of bar area (e.g., solid area around the aperture) to aperture area. Foils with a honeycomb-shaped aperture structure have proven successful in practice for many years and enable a particularly thorough shave, while at the same time are extremely gentle on the skin. 
   When designing aperture patterns for shaving foils it is always necessary to optimize the compromise between thoroughness, for which particularly large aperture dimensions are suitable, and gentle treatment of the skin, which can be improved by smaller aperture dimensions. For example, in a more expansive shaving foil aperture, the skin can be pressed partially closer to the undercutter as the undercutter moves relative to the shaving foil. As a result, thoroughness is improved because the undercutter can be moved closer toward the hair root. However, at the same time, there is a higher risk, of course, that the user&#39;s skin will be irritated or at worst injured because the user&#39;s skin is also moved closer to the undercutter. 
   Regularly arranged aperture patterns result in very little variation in the alignment of the bars between the apertures. Bar alignment plays a particularly great role in the actual process of threading in and cutting hair. Generally, in foils having honeycombed-shaped apertures and/or foils described in accordance with DE-A 1 553 668, there are three to four preferred directions of parallel running bars in relation to the blades of the moving undercutter. Hair growth on the human skin, particularly growth of beard hair, is highly irregular by comparison, not only with regard to the distribution of individual hairs on the skin surface but also in terms of the spatial alignment of individual hairs in relation to each other. Hence, the more alignments provided by the bars of a shaving foil, the greater the probability of a cutting action taking place between a bar and a blade of an undercutter. 
   Shaving foils can also include several perforate regions, each with a different aperture geometry as shown in DE-A 1 553 668. However, the aperture patterns of the individual perforate regions shown in DE-A 1 553 668 are themselves periodic, and thus limit the probability of a cutting action taking place. 
   SUMMARY 
   It is an object of the present invention to provide a prior-art shaving foil that surpasses the known shaving foils, which are already of the highest quality standard, in terms of thoroughness and gentle treatment of the skin. 
   An aspect of the invention features a shaving foil designed in such a way that the perforate region forms a quasi-periodic pattern executed according to the Penrose parquet. 
   Penrose parquets are named after Roger Penrose who conducted theoretical investigations into irregular patterns that possess no translational symmetry or periodicity; refer also to the essay “Quasikristalle” by David Nelson, published in “Spektrum der Wissenschaft”, October 1986, pages 74–93. 
   In one aspect, the invention features a shaving foil for a shaving apparatus with at least one shaving foil and a cooperating undercutter adapted to be driven relative to each other. The shaving foil includes at least one perforate region including a plurality of hair-receiving apertures and having a quasi-periodic pattern executed according to the Penrose parquet. 
   In another aspect, the invention features a shaving foil for a shaving system. The shaving foil inclueds at least one perforate region including a plurality of hair receiving apertures and having a quasi-periodic pattern arranged to have at least five-fold symmetry (e.g., five-fold symmetry, 10-fold symmetry, 12-fold symmetry). 
   In another aspect, the invention features a shaving apparatus including a shaver head including an undercutter, a frame attached to the shaver head, and at least one shaving foil carried by the frame, wherein the shaving foil includes at least one perforate region including a plurality of hair-receiving apertures and having a quasi-periodic pattern executed according to the Penrose parquet. 
   In another aspect, the invention features a method of shaving hair. The method includes applying the above-described shaving apparatus to skin including hair and activating the undercutter. 
   According to an advantageous aspect of the invention, a provision is made for the perforate region of the shaving foil to be formed by complete parqueting using at least two different surface section elements, said surface section elements being equipped with at least one aperture. This embodiment offers the possibility of implementing different aperture sizes and/or aperture geometries. 
   In some embodiments of the invention, the perforate region is formed by complete parqueting using at least two different surface section groups, each being equipped with at least one aperture, said surface section groups being each comprised of at least two surface section elements. This embodiment also offers numerous variation options for arranging apertures of different size and/or geometry. By combining several surface section elements to form surface section groups the number of possible combinations of different apertures is significantly increased. 
   In some embodiments, the surface section elements are shaped as rhombuses, which are suitable for complete parqueting. In this embodiment, it is particularly advantageous for the acute angle of the rhombuses to equal 36° and/or 72°, with the surface section elements having in particular the same edge length. This takes account of the fact that the more acute the angles of the rhombuses, the greater the loss of aperture area on the foil due to the necessary rounding of the corners, which will be subsequently described. 
   The shaving foil of the present invention is suitable for all shaving apparatus drive concepts, regardless of the relative movement between the shaving foil and the undercutter. 
   The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 

   
     DESCRIPTION OF DRAWINGS 
       FIG. 1  shows the basic design of a shaver head; 
       FIG. 2  shows a section from a Penrose parquet; 
       FIG. 3  shows three different surface section groups; and 
       FIG. 4  shows a shaving foil whose perforate region is formed by parqueting using the surface section groups of  FIG. 3 . 
   

   Like reference symbols in the various drawings indicate like elements. 
   DETAILED DESCRIPTION 
     FIG. 1  shows an exchangeable frame  1  which carries two shaving foils  2 , each having a perforate region comprising a plurality of hair receiving apertures. Associated with the exchangeable frame  1  is a shaver head  3  which has undercutters  4  that are adapted to be driven in oscillatory manner. The drive mechanism itself is not shown in the drawing for better clarity and can be configured, for example, as an eccentric drive with an electric motor. The exchangeable frame  1  can be locked with the shaver head  3  by means of detent elements  5 . The exchangeable frame  1  is detachable from the shaver head  3  by actuating a release button  6 , for example for cleaning and maintenance purposes. 
   The undercutters  4  are configured in known fashion each as a blade assembly having a plurality of blades arranged parallel with one another. 
   Beard hairs threaded in from the outside through the apertures of the shaving foil  2  are captured during the shaving process by the oscillating undercutters  4  and are sheared off on the bars surrounding the apertures. 
   Referring to  FIG. 2 , the perforate region of shaving foil  2  is patterned with a Penrose parquet. It is a special characteristic of Penrose parquets that every pattern therein keeps on recurring, but not regularly. Penrose patterns are therefore a special class of non-periodic parquets, which are also referred to as quasi-periodic because each sub-pattern of the parquetry reoccurs an infinite number of times but not at regular intervals. Penrose parquets are composed of surface section elements with which a periodic parquet is not possible. In particular, Penrose parquets display a so-called five-fold symmetry, cover areas of any size completely and without overlap, and are comprised of at least two different types of surface section elements. 
   Penrose patterns can only be assembled in accordance with one special laying plan and are therefore clearly different from unordered or chaotic patterns. With Penrose patterns it is possible to achieve significantly greater ratios of aperture area to bar area than with chaotic patterns, which is particularly important for a shaving foil&#39;s degree of efficiency. 
   Bars surrounding the apertures in the shaving foil  2  display a strikingly large number of different alignments on the foil surface. This large number (e.g., at least 5) of different bar alignments not only has a positive impact on the shaving characteristics (e.g., thoroughness) but also enables a very good (e.g., uniform) attachment of the shaving foil over the associated undercutter, in spite of differing aperture sizes. This applies in particular when the shaving foil has to be arched when it is attached. In prior art foils that have differing aperture size and a regular, periodic pattern, problems with the uniformity of attachment occur when mounting shaving foils on the frame because the mounting of these prior art foils easily results in local distortions that adversely affect intimate contact of the shaving foil with the associated undercutter. 
   The size of the previously mentioned bars of shaving foil  2  naturally affect the aperture/bar ratio and hence for the effectiveness of the shaving system. A large aperture/bar ratio is thus desirable for shaving foils with a high degree of efficiency. The bar widths should therefore be kept as small as possible, i.e., as small as necessary for production reasons and/or for strength requirements. As a result, the individual bars within a perforate region should be made with the same width. By constructing the perforate region in accordance with the Penrose parquet it is possible to obtain improved aperture/bar ratios with the same bar width than would be possible with chaotically arranged apertures in a perforate region. 
   The existence of variously sized penetration apertures in the foil  2  allows, for example, the shaving of longer hairs in a first shaving motion in which the hairs can easily enter into large cross-sectional apertures to be cut there. With a subsequent shaving motion it is then possible for pre-shortened hairs or shorter hairs that thread into apertures of bigger cross section, but are not cut there, to be shaved by means of the apertures of smaller cross section. 
     FIG. 2  shows a perforate region that is constructed in accordance with a Penrose parquet. Section A on the right of the drawing shows a perforate region formed by parqueting using two different aperture elements in accordance with Penrose. Section A contains kite-shaped apertures  10  and arrow-shaped apertures  11 . The kite-shaped apertures  10  have a larger surface area than the arrow-shaped apertures  11 . Between the apertures  10 ,  11  are bars  12  of constant width. The acute angle of the kite-shaped aperture  10  as well as of the arrow-shaped aperture  11  equals 72°. When looking at this perforate region it becomes clear that individual local patterns occur again and again but not at regular intervals. Examples of these local patterns are, for instance, the decagon-shaped aperture group  13  or the pentagon-shaped aperture group  14 , in which the kite-shaped aperture elements  10  and the arrow-shaped aperture elements  11  always point with their acute angles to a common center. 
   The apertures in section B of  FIG. 2  differs from the apertures in section A firstly in that the corners of the individual apertures are rounded. The second difference between section A and section B is that the perforate region in section B includes three different types of apertures, whereas section A includes only two different types. In section B, the aperture elements  16  and  17  correspond respectively to the kite-shaped apertures  10  and the arrow-shaped apertures  11  from section A. However, all of the corners of the aperture elements  16  and  17  are rounded, whereas aperture elements  10  and  11  are angular. A third aperture element  18  in section B has a triangular opening with an acute angle of 36° and equally rounded corners. As in section A, the widths of the bars of foil material existing between the individual apertures are constant in section B. 
     FIG. 3  shows three surface section groups  25 ,  26  and  27  whose surfaces are each composed of individual surface section elements  28 ,  29 . The two surface section elements  28 ,  29  are rhombuses, each of equal edge length, with the acute angle of the surface section element  28  equaling 72° while the surface section element  29  has an acute angle of 36°. 
   The first star-shaped surface section group  25  is composed of five surface section elements  28  having acute corners that converge in a common point in the center of the first surface section group  25 . The leaf-shaped second surface section group  26  is comprised of three surface section elements  28  and one surface section element  29 . Similar to the first surface section group  25 , tips of three surface section elements  28  converge at common point. On that same point also lies the corner of the obtuse angle of the surface section element  29 . 
   The hexagonal third surface section group  27  is comprised of one surface section element  28  and two surface section elements  29 . In this arrangement, the two acute angles of the surface section elements  29  lie on a common point while the acute angle of the surface section element  28  lies on a common point with two obtuse angles of the surface section elements  29 . 
   Again, Penrose parqueting is possible using the described three surface section groups  25 ,  26  and  27 . To form a perforate region having a Penrose parquet for a shaving foil, the individual surface section groups are equipped with penetration apertures. 
   Each of the surface section elements  28  of the star-shaped first surface section group  25  possesses a penetration aperture  30 , which is of a rhombus-shaped configuration like the surface section element itself. However, the corners of the penetration aperture  30  are rounded. The sides of the surface section elements  28  and the sides of the penetration apertures  30  extend parallel with each other. The area of the penetration aperture  30  equals approximately 50% of the area of the surface section element  28 . 
   The leaf-shaped second surface section group  26  is equipped with a total of four apertures. Three triangular penetration apertures  31  are provided in the outwardly facing zones of the surface section elements  28 , with the corners of these triangular penetration apertures  31  being equally rounded. The aperture area of the penetration apertures  31  is somewhat greater than half the area of the penetration apertures  30 . In the region of the common point of the acute angles of the surface section elements  28  and the obtuse angle of the surface section element  29  of the second surface section group  26 , a provision is made for a further, pentagonal penetration aperture  32 . The pentagonal penetration aperture  32  also has its corners rounded. 
   Provided in the hexagonal third surface section group  27  are two hood-shaped penetration apertures  33 , whose tips have an angle of 72° and whose base edges extend parallel with each other so that a bar remains between the two penetration apertures  33 . The corners of the penetration aperture  33  are likewise rounded. 
   Rounding the corners of the penetration apertures  30  to  33  ensures that no hair to be shaved is able to get caught in one of the corners, in particular the corners with an angle smaller than 90°. The radii of the rounded corners are therefore greater than half a hair diameter. The edges of the respective penetration apertures  30  to  33  are arranged such that they always extend parallel with the edges of neighboring penetration apertures. The distance between the edges of two neighboring penetration apertures and their mutual alignment is selected such that the remaining material forms bars of constant width S. 
     FIG. 4  is a view of a shaving foil having a perforate region provided with penetration apertures  30  to  33  as contained in the surface section groups  25  to  27  of  FIG. 3 . This illustration shows a complete Penrose parquet with apertures of various size and shape.  FIG. 4  also shows that the bars formed a large number of different alignments between the penetration apertures. Furthermore, when looking at the aperture pattern it becomes clear that local patterns reoccur often but irregularly. This property also contributes to lending such a pattern an interesting optical appearance. In the case of shaving foils made of a shiny foil material this optical irregularity results in a particular shine due to the variously oriented reflection of light rays. 
   In the shaving foil shown in  FIG. 4 , further cutouts for attaching the shaving foil  2  to the exchangeable frame  1  are provided outside the perforate region with the penetration apertures  30  to  33  required for shaving. 
   All publications, applications, and patents referred to in this application are herein incorporated by reference to the same extent as if each individual publication or patent was specifically and individually indicated to be incorporated by reference in their entirety. 
   A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention.