Patent Publication Number: US-7721446-B2

Title: Wet razor with conforming blade support

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This application claims the benefit of priority from GB 0615113.8, filed Jul. 28, 2006, the contents of which is hereby incorporated by reference herein in its entirety. 
   FIELD OF THE INVENTION 
   This invention is concerned with safety razors, also called wet razors that exhibit a high degree of conformance to the surface being shaved. 
   BACKGROUND OF THE INVENTION 
   There are known wet or safety razors that are intended to provide a degree of conformance to skin curves. These are disclosed in U.S. Pat. No. 7,024,776 (Wain), and a blade suitable for use therein shown in U.S. Pat. No. 6,804,886 (Wain). United States Patent WO 99/04938 (Hawes et al.) proposes a flexible support for a shaving cartridge. Other suggestions known in the art for flexible blade supports are for example the following U.S. Pat. No. 4,754548 (Solow); U.S. Pat. No. 4,976,028 (Chen); U.S. Pat. No. 4,854,043 (Chen); and U.S. Pat. No. 4,516,320 (Peleckis). Powered, electric razors employing inner and outer cooperating shearing members such as “foils” supported to adapt in use are known from EP-A-1449627 (Uchiyama), and EP-A-1454720, but those constructions limit conformance during use. As described in EP-A-1449627 with reference to  FIG. 2  therein, the outer foil cutter ( 20 ) is fixed to the inside of the casing ( 22 ) at anchoring positions ( 24 ), and this inevitably reduces the flexing capabilities. Furthermore, the U-shaped foil configuration also acts to resist flexing of the foil along its length and, as the blade support bends the blades spread apart or come together so that distances separating the shearing edges of adjacent blades are changed and the shaving performance is consequently affected, which is undesirable. EP-A-1454720 describes a similar foil and cutter assembly but differs in that the inner cutter, instead of being resilient, is shaped so that the foil has a concave curvature along its length. A second foil and cutter assembly with a straight convex or concave configuration can be provided alongside the concave assembly. In this case, maintaining proper cooperation between the cutter blades and the foil over the full length of the foil becomes a problem when the inner cutter is reciprocated relative to the foil. 
   SUMMARY OF THE INVENTION 
   The present invention has for an object to at least alleviate the limitations of the prior art as explained above and to satisfy the need for a safety razor construction that can achieve improved contact and conformity between the blade and a curved skin contour. 
   Provided in accordance with the invention is an assembly in or for a safety razor, comprising an elongate flexible blade structure comprising one or more blades, characterized in that the blade structure is carried on a supporting structure that is deformable to permit the blade structure to flex, and that the supporting structure comprises a series of elements spaced apart along the blade structure and so linked together, such as by hinged connections, that the blade can flex to follow concave or convex curvatures along the length thereof. 
   The cutting performance remains substantially constant irrespective of the flexing of the blade or blades to conform to convex or concave skin curvatures. A supporting structure consisting of a series of spaced elements can provide effective supporting at a large number of points along the blade structure without seriously impairing the flexing capability of the blade. Preferably the number of support elements in the series is at least several, in particular at least five, and ideally around 10 or more, and there can be as many as 20 or 25. From 8 to 22, more especially 12 to 18 support elements are favorable. Conveniently the blade support elements are uniformly spaced apart along the blades, and preferably the blade support elements are linked together by integral hinged connections and extend from the hinged connections to free ends at which the blade structure is supported. The blade structure is preferably slidably received by the support structure and in a simple but highly effective construction the blade support elements have notches at the free ends, and a side edge portion of the blade structure is received in and guided by the notches. Longitudinal movement of the blade or blades is generally undesirable and the blade structure can conveniently be provided with a detent for engaging a blade support element to retain the blade structure against any longitudinal movement at the location of the engaged element. At least some movement in the longitudinal direction is permitted between the blade structure and other support elements so that flexing of the blade structure is not hindered. In order to minimize such relative movement the detent is preferably located at a medial position along the blade structure. 
   In its simplest form the blade structure can consist of a single elongate flexible blade mounted to the supporting structure, but it may also comprise a plurality of blades mounted on the supporting structure independently of each other. Conveniently, however, the blade structure includes one or more blades assembled in a frame having an elongate flexible member or part that cooperates with the support elements of the supporting structure. Conveniently, blades of the type disclosed in U.S. Pat. No. 6,804,886 B2 (Wain) can be used, the entire disclosure of which is incorporated by reference hereby. Another alternative with the scope of the invention is a blade structure comprising a flexible plate or sheet with a number of through holes, e.g. circular holes, which holes have cutting edges extending at least partially around their peripheries. 
   To control deformation of the supporting structure a guide arrangement is preferably included in the assembly for guiding relative movement of the linked support elements. The guide arrangement can include a frame in which the supporting structure is carried and at least two of the elements can be guided to move along substantially linear paths. In particular two elements can be guided in the longitudinal direction and a further element can be guided in a direction substantially perpendicular to the longitudinal direction. In this way a symmetrical form can be maintained as the blade structure and the supporting structure flex and change curvature. Conveniently the guided elements have lateral projections that engage in guide slots formed in an adjacent frame member. 
   One embodiment of the invention has two series of linked support elements for supporting the blade structure. A uniform support for the blade structure can be ensured by a symmetrical arrangement of the two series of linked supporting elements. One series of support elements can support the blade structure along a first edge portion, and the second series of support elements can be arranged to support the blade structure along another edge portion of the blade structure located opposite the first edge portion. 
   The supporting structure with the series of link support elements is conveniently mounted in a frame including an opposed pair of plates and at least one spacer disposed between the plates. Slots for guiding movement of the series of linked support elements can be provided in a frame plate. In addition, or alternatively, a spacer may include guide means for guiding movement of the support elements during deformation of the supporting structure. For example, the guide means can comprise a slot in the spacer and a slide member fixed to the supporting structure and engaged in the slot. 
   As previously mentioned the blade structure may include a flexible base frame. The base frame is preferably flat and may be stamped from a thin metal sheet or may be formed of plastic material. An edge portion of the base frame can be engaged with the series of linked support elements and/or each blade can be connected to the base frame at a plurality of positions along the blade. In one construction the base frame comprises opposed, parallel edge portions interconnected by bridging strips and end strips to which the blade or blades may be connected by any suitable means, such as spot welds or by adhesive. Alternatively, blade mounts may be disposed on the flexible base frame at spaced positions and be provided with slots or otherwise adapted to receive the at least one blade. 
   Another possibility is for the support elements to have blade seats thereon. The blade seats may be provided on support bridges that interconnect the upper ends of pairs of opposed support elements of two symmetrically arranged series of linked support elements. The blade seats conveniently comprise slots to receive the at least one blade of the blade structure. 
   The blade slots, whether in the blade mounts or formed by the blade seats are conveniently configured to receive a planar blade and to orientate the blade in an inclined disposition with the cutting edge uppermost. 
   When the blade structure includes a flexible base frame this frame can conveniently carry a guard member, for example a guard member of elastomeric material that may be molded in situ onto the base frame. The guard member may be positioned between an edge portion of the base frame which is engaged with the supporting structure and the at least one blade. Another possibility is for the guard member to be carried on a part of the base frame disposed remotely from an edge portion engaged with the supporting structure with respect to the at least one blade. In this case the part of the base frame carrying the guard member can be connected to the edge portion by a plurality of projecting frame pieces spaced apart along the edge portion. The guard member is preferably formed in one piece and extends continuously along the base frame. 
   Another form of guide arrangement to guide movement of the support elements comprises a guide member disposed adjacent the supporting structure, the guide member including a rigid central part with a pair of opposed arm extending therefrom, and coupling members, ideally hinged to the arms and connected pivotally to the supporting structure, coupled between the arms and the supporting structure adjacent the opposite ends of the supporting structure. The central part of the guide member is suitably engaged slidably with a slide member connected to a medial part of the supporting structure for guiding movement thereof. A guide slot can be defined by the guide member and be engaged by a slide block connected to the supporting structure. 
   In addition to providing support for the blade structure, the supporting structure can support a separate skin contact member, such as a strip containing an agent, e.g. a lubricating agent, for application to the skin during shaving. The skin contact member may additionally or alternatively constitute a source of other shaving enhancement products know per se. Conveniently the skin contact member includes opposed longitudinal edges slidably engaged with the supporting elements, and the longitudinal edges can be provided by a flexible carrier plate of the skin contact member. 
   It may be desirable for the support elements of the supporting structure to carry respective segments of a skin contacting member, particularly an elastomeric guard member, or a lubricating strip, which can be molded in one piece with the segments being interconnected by intervening webs. 
   The foregoing and other advantageous features of the preferred embodiments of this invention will become apparent from the detailed description which follows, reference being made to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
       FIG. 1  is an isometric view of showing a first embodiment of a safety razor blade unit assembly in accordance with the invention; 
       FIG. 2  is a front elevation of the blade unit shown in  FIG. 1 ; 
       FIG. 3  is a front elevation of the blade unit shown in  FIG. 1  with the blade structure omitted; 
       FIG. 4  is a top plan view of the blade unit shown in  FIG. 1 ; 
       FIG. 5  shows the blade unit of  FIG. 1  in end elevation; 
       FIG. 6  is an underneath plan of the blade unit shown in  FIG. 1 ; 
       FIG. 7  is an isometric view of the blade unit of  FIG. 1  with the blade structure removed; 
       FIGS. 8 and 9  are a front elevation and an isometric view, respectively, showing the supporting structure of the blade unit shown in  FIG. 1  deformed into a concave shape; 
       FIGS. 10 and 11  are a front elevation and an isometric view respectively showing the supporting structure of the blade unit shown in  FIG. 1  deformed into a convex shape; 
       FIG. 12  is a cross-section through one of the blades of the blade unit illustrated in  FIG. 1 ; 
       FIGS. 13A ,  14 A,  15 A are schematic illustrations showing successive stages in shaping the blade of  FIG. 12  by a pressing operation; 
       FIGS. 13B ,  14 B,  15 B are enlarged scale views of the circled areas of  FIGS. 13A ,  14 A,  15 A, respectively; 
       FIGS. 16A and 16B  are cross sections through two blades indicating the axis with respect to which the second moment of area is at a minimum; 
       FIG. 17  is a front isometric view showing a second embodiment of a safety razor blade unit assembly according to the invention; 
       FIG. 18  is a front elevation of the blade unit shown in  FIG. 17 ; 
       FIG. 19  is a front elevation of the blade unit shown in  FIG. 17  with the front plate of the main frame removed; 
       FIG. 20  is a cross section taken along the line XX-XX in  FIG. 18 ; 
       FIG. 21  is an end elevation of the blade unit shown in  FIG. 17 ; 
       FIG. 22  is a top plan of blade unit shown in  FIG. 17 ; 
       FIG. 23  is an underneath plan of the blade unit shown in  FIG. 17 ; 
       FIG. 24  is a rear isometric view of a third embodiment of a safety razor blade unit assembly according to the invention; 
       FIG. 25  is an exploded view illustrating the separate components of the blade unit of  FIG. 24 ; 
       FIG. 26  is a rear elevation of the blade unit shown in  FIG. 24 ; 
       FIG. 27  is a top plan view of the blade unit of  FIG. 24 ; 
       FIG. 28  is an end elevation of the blade unit of  FIG. 24 ; 
       FIG. 29  is an underneath plan of the blade unit of  FIG. 24 ; 
       FIG. 30  is a section taken along the line XXX-XXX in  FIG. 27 ; 
       FIG. 31  is an enlarged scale view illustrating a part of the supporting structure of the blade unit of  FIG. 24 ; 
       FIG. 32  is a rear isometric view of a fourth embodiment of a safety razor blade unit assembly constructed in accordance with the invention; 
       FIG. 33  is an exploded isometric view of showing the components of the blade unit of  FIG. 32 ; 
       FIG. 34  is a rear elevation of the blade unit shown in  FIG. 32 ; 
       FIG. 35  is an end elevation of the blade unit of  FIG. 32 ; 
       FIG. 36  is a top plan of the blade unit of  FIG. 32 ; 
       FIG. 37  is an underneath plan of the blade unit of  FIG. 32 ; and 
       FIG. 38  is a cross section taken along the line XXXVIII-XXXVIII in  FIG. 36 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Throughout the drawings and the description which follows the same reference numerals have been used to designate corresponding parts and components in the respective embodiments and unless otherwise indicated the description of any part given with respect to one embodiment will apply equally to corresponding parts of other embodiments designated with the same reference numerals. 
   The safety razor blade units illustrated in the drawings are in use mounted on razor handles, either permanently so that the entire razor is discarded when the sharpness of the blades has reduced to an unsatisfactory level, or replaceably so that a used blade unit can be replaced by a fresh blade unit with sharp blades. If desired the blade unit can be pivotably mounted on the handle in a manner well known per se. The attachment of the blade units to the razor handle forms no part of the present invention, for which purpose any suitable connection structure can be employed and will not be described further. 
   The blade unit of  FIGS. 1 to 12  has a flexible blade structure  1  which includes a generally flat base frame  2  on which a plurality of blades, namely five blades  3  as shown, are carried. The base frame includes edge portions  5  for supporting the blade structure  1  at the edges without impeding contact between the cutting edges  4  of the blades  3  and the skin being shaved. Protruding outwardly from each edge portion  5  of the frame  2  is a tooth  6  for anchoring the base frame  2  at a medial location along the blade unit as will become clear from the description that follows. The frame edge portions  5  are connected together by bridging strips  7  and by end strips  8  that provide supports and attachment points for the blades  3 . The blade structure  1  comprising the base frame  2  and the blades  3  mounted thereon is resiliently flexible. The base frame can be readily produced by stamping from a thin metal sheet or as a plastic molding and can have the metal blades  3  fixed securely thereto by spot welding or by adhesive at the bridging and end strips  7 ,  8 . 
   The blade structure  1  is carried on a deformable supporting structure  14  mounted in a main frame  15 . The main frame  15  has a pair of front and rear guide plates  18  held together and spaced apart by spacers  19 . The deformable supporting structure  14  includes a symmetrically opposed pair of unitary suspension members  22  that are disposed adjacent the respective guide plates  18 . Each suspension member comprises a series of upwardly directed support element  24  interlinked adjacent their lower ends by integral hinges  25  so that the free upper ends of the support elements are able to move towards and away from the upper ends of their adjacent elements and the suspension member is deformable from the generally straight configuration shown in  FIGS. 1 to 7  to the concave configuration shown in  FIGS. 8 and 9 , or the convex configuration shown in  FIGS. 10 and 11 . At their upper ends the support elements  24  have upwardly directed faces defined by shoulders and slots  26  immediately above these shoulders defined by finger elements overlying the shoulders. The edge portions  5  of the base frame  2  are received slidably in these slots  26  with the middle two support elements  24  of each suspension member  22  confining a detent notch  27  into which the projecting tooth  6  of the base frame  2  engages to retain the blade structure  1  against longitudinal movement relative to the middle support elements. Thus, as the blade structure  1  and the suspension members  22  flex concavely or convexly along their length the support elements  24  are able to slide relative to the base frame  2 , while the engagement between the middle support elements  24  and the teeth  6  retains the blade structure against unwanted movements relative to the supporting structure. Integral with support elements  24  disposed towards the ends of each suspension member  22  are bosses  28 , which are attached to the lower ends of the support elements, and pins  42  are inserted through the aligned bosses  28  of the two suspensions members  22 . 
   The deformation of the suspension members  22  under forces imposed on the blade structure  1  is controlled by the guide plates  18  each of which has a pair of longitudinally aligned guide slots  38  and a further linear guide slot  39  that extends in a direction perpendicular to the longitudinally aligned slots  38 . The central support elements  24  of each suspension member  22  are extended downwardly by leg  40  that is located alongside the guide slot  39  and has a projecting slide block  41  slidably engaged in the slot  39  so that the central support elements  24  are guided for movement in the direction of the slot  39 . Projecting ends of the pins  42  engage slidably in the guide slots  38 . The arrangement of the guide slots  28 ,  39  and pins  41 ,  42  ensures that the suspension members  22  and hence the blade structure  1  supported by them always adopt a smooth uniform curvature when displaced from the normal straight configuration due to a force imposed against the blade structure. A force directed at the central region of the blade structure e.g. when the blade structure is pressed against a convex skin contour will result in the blade structure and the deformable support structure  14  adopting a concave form, e.g. as depicted in  FIGS. 8 and 9 , whereas a force directed at the ends of the blade structure, as may occur when it is pressed against a concave skin contour will cause the blade structure and its supporting structure  14  to assume a convex curvature as depicted in  FIGS. 10 and 11 . 
   In each of the support members  22  all of the support elements  24  in the series may be linked by hinged connections  25  to the immediately adjacent support elements on either side. However, in the construction as shown in the drawings each of the two bosses  28  and the leg  40 , by means of which the suspension member  22  is coupled to the guide arrangement for controlling the deformation of the suspension member between concave and convex configurations, are connected firmly to two adjacent support elements  24  whereby these two elements always remain parallel to each other as the suspension member deforms. Because there is a large number of support elements that are positioned closely to one another having these pairs of adjacent elements which are not connected by hinges so that they do not move relative to one other does not impair the ability of the suspension member to deform and the blade structure supported thereby to adopt a smoothly concave or convex curvature. In an especially simple construction projections for engagement in the guide slots  38 ,  39  can be carried by, e.g. formed integrally with, respective support elements  24  of the suspension member. In addition whereas the detent which anchors the blade structure against longitudinal movement at the centre of the assembly is formed by a single tooth  6  which engages in the gap between two support elements other forms of detent can also be contemplated, such as the blade structure having two teeth  6  spaced apart to define a notch in which one of the support elements is engaged. Furthermore, a satisfactory detent can be provided by staked, pinned or other form of localized fixing between the blade structure and a support element of the supporting structure  14 . 
   The blade structure  1  comprises the base frame  2  and the plurality of blades  3 . Maximum flexibility of the blade structure is ensured by the blades and flat strips that make up the base frame being coplanar in the normal, undeformed condition of the blade structure  1  and its supporting structure. Each of the blades  3  comprises an elongate blade element with a forward edge section  50  ( FIG. 12 ) forming the sharp cutting edge  4 , the tip of this edge being confined between opposed surface portions  51 ,  52  referred to hereinafter as facets which taper towards the tip, and a substantially planar blade section  54  extending rearwardly from the forward edge section  50 . The forward edge section  50  is canted upwardly towards the tip of the cutting edge  4  so that a plane P t  bisecting the angle between the facets  51 ,  52  at the tip of the cutting edge is inclined at an angle α of around 20° to 25° to the plane P m  of the planar section  54 . The tip of the cutting edge  4  is can be positioned above the Plane Pu of the upper surface at the planar section at a height of up to 0.25 mm, preferably a height in the range of 0.05 to 0.15 mm. The inclination of the canted forward section  50  is obtained by bending a planar blade element blank  60 , as illustrated in  FIGS. 13A ,  14 A and  15 A, by pressing the blade element blank  60  in a tooling assembly comprising a lower first member  61  and an upper second member  62 . The lower tool member  61  defines a flat pressing surface  64  which is extended forwardly by a ramp surface  65 . The upper tool member  62  has a flat pressing surface  66  which confronts the flat pressing surface  64  of the lower member  61 , and the upper member  62  is moveable relative to the lower member  61  for pressing a blade element  60  between the flat pressing surfaces. The lower member  61  has a rear stop  67  for abutting the rear edge of a blade element blank  60  and a front stop  68  located on the ramp surface  65  for abutment with the tip of the blade edge. The stops  67 ,  68  may be adjustable to suit the width of the blade element blanks  60  to be pressed, and to adjust the position of the bend to be produced with respect to the tip of the blade edge  4 , the rear stop  67  being adjustable vertically and having an inclined front face for this purpose. 
   An elongated planar blade element blank  60  with a finished cutting edge  4  along its forward edge is introduced between the upper and lower tool members  61 ,  62 , and is brought to rest against the flat surface  64  of the lower member with its rear edge in contact with the rear stop  67  and the tip of the cutting edge  4  resting on the ramp surface  65  and against the front stop  68  ( FIGS. 13A  and B). The blank is therefore initially tilted at a small angle to the flat surfaces  64 . The upper member  62  is then driven downwardly bringing its pressing surface  66  into contact with the blank  60  and causing the portion of the blank  60  between the surfaces  64 ,  66  to be pressed flat against the surface  64 , and hence the forward edge section  50  of the blade to be pulled down against the ramp surface ( FIGS. 14A  and B). In one example the facets  51 ,  52  of the blade edge extend back from the edge tip by 0.3 mm, the blade thickness being 0.8 mm and, the front edge of the upper tool is aligned to contact the blade at a distance of 0.4 mm from the tip. When the upper member  62  is raised again, the bend produced in the blade blank  60  by the pressing operation recovers a little, but a permanent set in the blade blank  60  remains so that the forward edge section  50  is canted at the desired inclination with respect to the planar blade section  54  which extends rearwardly from it, and in a transition region between the forward section and planar section the lower surface has a convex curvature whereas the upper surface is non-convex, and more particularly concave. After completion of the blade shaping operation as described, a part of the blank including the canted forward edge section and a planar section several times wider, in the front to rear direction, than the canted forwarded edge section can be severed or snapped away from the blank to provide a flexible blade strip  3  of the desired width. The blades produced in this manner can then be used to produce blade structures as incorporated in the safety razor blade unit of  FIGS. 1 to 11 . 
   The blades  16  shaped and manufactured as described above, are characterized by a relatively high flexibility despite their being bent to raise the tip and incline the cutting edge  4  to obtain an effective blade tangent angle with the planar section  54  of the blade positioned parallel to the tangent plane. The flexibility can be conveniently expressed by the second moment of area of the blade cross section since razor blade materials currently used have Young&#39;s moduli which differ little from one another. The second moment of area I of a cross sectional area with respect to an axis X lying in the plane of the cross section is the sum of the products obtained by multiplying each element of area dA by the square of its distance y from the axis X. Thus: 
   It will be appreciated that the second moment of area is dependent on the shape and size of the cross section. 
   The minimum second moment area is the second moment of area measured with respect to that axis X which results in the smallest value for the second moment of area I min . Illustrated in  FIGS. 16A and 16B  are the cross sections, taken in planes perpendicular to the lengths of the cutting edges, of two blades  3 . The blade  3  of  FIG. 16A  is 0.08 mm thick and 0.80 mm wide with the planar section  54  being 0.40 mm wide, and its minimum second moment of area I min  with respect to the axis X is 0.322×10 −4  mm 4 . The blade of  FIG. 16B  has a thickness of 0.08 mm and a width of 0.80 mm with the planar section  54  being 0.10 mm wide, and in this case the minimum second moment of area is I min  0.145×10 −4  mm 4 . The blades  3  can be positioned in the blade structure  2  with the mid planes of their planar sections  54  substantially parallel to a plane tangential to guard and cap surfaces of the blade structure, and the second moments of area I measured about the axis parallel to these mid planes and intersecting the centers of area for the blades shown in  FIGS. 16A and 16B  have values of 0.443×10 −4  mm 4 , and 0.26310 −4  mm 4 , respectively. To achieve a desired level of blade flexibility in an assembled blade unit, it is also preferred that the second moment of area with respect to an axis passing through the centre of area and parallel to the mid plane of the planar section  54  is not greater than 1.0×10 −4  mm 4 , and more especially not greater than 0.5×10 −4  mm 4 . If the blade  3  has a cross section which is constant along its length the I values given above will apply at every position along the length. However, there may be short blade sections where the I values are different, because the cross section is different, and the desired flexibility can be assured by the blade having a form such that the specified I values apply along at least most of the length of the blade. 
   Although described above in connection with shaping a blade having edge facets which, prior to bending of the blade, are symmetrical with respect to the centre plane of the blade, this is not essential and the blade edge could have an initial asymmetrical form including a so-called chisel edge in which the tip lies at the top surface plane of the blade. 
   Further information and details regarding the blades  3  and their manufacture can be gathered from U.S. Pat. No. 6,804,886 B, the contents of which are incorporated herein by reference. 
   The safety razor blade unit illustrated in  FIGS. 17 to 23  is generally similar to the blade unit described above with reference to  FIGS. 1 to 16 , and the same description applies apart from the modifications that are mentioned below. The front plate  18  of the main frame has two trunnions  20  at its opposite ends for pivotal connection of the blade unit to a razor handle (not shown) to pivot about an axis parallel to the cutting edges of the blades  3  in a manner well known per se. The two spacers  19  of the main frame  15 , extending, between the opposed frame plates  18 , are integrated into a common spacer member  10  having a central upright part  12  defining a vertical guide slot  13 . The depending legs  40  of the respective suspension members  22  have slide blocks  41  that extend towards each other and into the guide slot  13  for the middle sections of the suspension members to be guided for vertical movement. The end regions of the suspensions members  22  are guided by pins  42  engaged in the slots  38  in exactly the same way as in the first embodiment described above, although the pins  42  are not shown in  FIGS. 17 to 23 . By virtue of the guiding arrangement between the supporting structure  14  and the main frame  15  the upper ends of the support elements  24  and the flexible blade structure  1  carried thereon are able to adapt to conform to both convex and concave curvatures as explained above in connection with the blade unit of  FIGS. 1 to 11 . The blade structure  1  in this embodiment includes in addition to the substantially sheet-like base frame  2  and the flexible blades  3  (there being four blades in this embodiment), an elastomeric guard member or strip  30 , with a series of upstanding parallel fins  31 , molded in situ onto the base frame. The guard strip  30  is highly flexible and does not impede flexing of the blade structure  1 . A body part of the guard strip can be located on the underside of the base frame  2  with only upwardly projecting parts, such as the fins  31  and a backstop element  32  located above the top surface of the base frame. The edge portions  5  of the base frame  2  are supported by the support elements  24  as in the first embodiment of  FIGS. 1 to 11 , and the guard strip  30  is located between that edge portion which is engaged with the support elements  24  of the suspension member  22  at the front of the blade unit, and the blades  3 . As depicted in  FIG. 22 , the parts of the elastomeric guard strip protruding above the frame plate can be separated into a plurality of segments along the blade structure and if desired the guard segments can separately formed. 
   The third embodiment of a safety razor blade unit illustrated in  FIGS. 24 to 31  includes a main frame  15  with front and rear plates  18  interconnected by an integral spacer member  10  of the same form as that of the second embodiment described above and including spacers  19  and a central guide part  12  defining a guide slot  13 . Thus the series of linked support elements  24  of the supporting structure are guided for movement in the same way as in the previous embodiment although once again the guide pins  42  which are slidably engaged in the guide slots  38  of the frame plates  18  are not shown in the drawings. 
   In the blade unit shown in  FIGS. 24 to 31  the blade structure  1  comprises a set of five individual blades  3  separately mounted on the supporting structure  14 . The supporting structure includes symmetrically opposed suspension members  22  each having a series of support elements  24 , with adjacent support elements  24  in each series being linked by integral hinges  25 , but in this embodiment the upper ends of each opposed pair of support elements are interconnected by support bridges  45  integral with the support elements  24 . Formed on each of the bridges are blades seats  46  for receiving the respective blades, and blade retaining fingers  47  disposed above and alongside the seats to engage over blades positioned on the seats. The seats  46  and the fingers  47  together define slots to receive the blades. The blades seats  46  are forwardly and upwardly inclined to set the blades  3  at a desired angle with the cutting edges  4  uppermost, which allows substantially planar narrow blades  3  to be employed without any need for any special shaping, e.g. in the manner described above in connection with  FIGS. 12 to 16 . If desired, however, the blade seats  46  could be made flat and bent blades as included in the first and second embodiments could be fitted onto the flat blade seats. Connected to, and conveniently formed in one piece with the blade support bridges  45  at the opposite ends of the supporting structure are end members  48  with notches  49  to receive the ends of the respective blades. Metal blade retainer clips (not shown) are wrapped around the end members  48  and the blade ends positioned thereon to retain the blades on the supporting structure and to prevent the blades becoming dislodged from the blade seats  46 . To avoid any undesirable longitudinal movement of the blades  3  relative to the supporting structure  14 , the blades are provided with detent teeth  6  which project from the rear edges of the blades and engage between two blade seats  46  so that the blades are held at central positions along their length without impeding sliding movement between the blades and the blade seats at positions away from the central location. The slide block  41  which is engaged in the guide slot  13  of the central part  12  of the spacer member  10  is fixedly connected to the legs  40  of the suspension members  22  after having been inserted through the guide slot  13 . 
   The blade unit of  FIGS. 24 to 31  includes a separate skin contact member  70  mounted on the supporting structure  14 . This skin contact member could be a guard member for engagement with the skin in front of the blades in the performance of a shaving stroke with the blade unit, but in the construction shown in the drawings the skin contact member  70  is a cap member for contact with the skin behind the blades and it comprises a flexible lubricating strip  71  carried on a flat flexible plate  72  having longitudinal edges  73  in front of and behind the lubricating strip. The suspension member  22  positioned adjacent the rear frame plate  18  has support elements  24  formed with upstanding portions  74  providing support faces, and fingers  75  located above these support faces and confining therewith slots  76  in which the longitudinal edges of  73  of the carrier plate  72  are slidably received. The longitudinal edges have detent teeth  77  projecting from their mid-portions to engage in notches defined between a pair of adjacent support elements  24  to hold the skin contact member against undesirable movement longitudinally of the supporting structure  14  of the blade unit. It will be appreciated that the skin contact member  70  is able to flex to follow the flexing of the blade structure  1  constituted by the individual blades  3  in the specific construction shown when the support elements  24  move for the blade unit to conform to concave or convex skin surface contours. 
   The support elements  24  of the suspension member  22  located in juxtaposition to the front frame plate  18  have guard segments  80  with upstanding fins  81  supported on their upper ends. The guard segments  80  are conveniently molded in situ from an elastomeric material and can be inter-connected by flexible webs  82  formed with U-shaped profiles so that the webs do not impede relative movement between the upper ends of the adjacent support elements  24 . 
   The embodiment of the invention illustrated in  FIGS. 32 to 38  excludes a main frame with front and rear plates, and instead is provided with a spacer member  10  which supports the deformable supporting structure and is arranged to provide guidance to control the relative movements of the support elements  24 . Two symmetrically opposed suspension members  22  are located on opposite sides, that is adjacent the front and rear of the spacer member, and as in the previous embodiments each suspension member including a series of support elements  24  linked together by hinged connections  25 . A flexible blade structure  1  is mounted on the upper ends of the support elements and has a flat base frame  2  with longitudinal edge portions  5  engaged in slots  26  provided in the free upper ends of the support elements  24 . The blade structure is described in further detail below. The bosses  28  provided at the ends of the suspension members have extensions  29  which act as spacers between the suspension members and the spacer member  10 . Fastening elements (not shown) are inserted through the bosses  28  and their extensions  29  and pass through holes  90  in the spacer member  10  to hold the assembly together. The spacer member  10  has a central part  12  with a vertical guide slot  13 , the open lower end of which is permanently closed by a gate element  91  after a slide block  41  has been inserted into the guide slot during assembly of the blade unit. The slide block  41  is fixedly connected to the legs  40  depending from the medially located support elements  24  of the two suspension members  22  whereby the centers of the suspension members are guided for vertical movement. Arms projecting from opposite sides of the central part  12  of the spacer member  10  have coupling members  92  connected thereto by integral hinges  93  for pivotal movement of the coupling members whereby their free ends move substantially linearly towards and away from each other as the coupling members  92  pivot about the axes of the hinges  93 . The holes  90  through which the fastening elements inserted through the bosses  28  of the suspension members  22  pass are located at the free ends of the coupling members  92  so that the bosses  28 , and hence the end regions of the suspension members, are guided for movement substantially linearly towards and away from each other in the longitudinal direction as the support structure  14  deforms to a convex or concave configuration, with the medial portions of the suspension members being guided to move substantially perpendicular to this direction by the engagement of the side block  41  in the guide slot  13 . 
   The blade structure  1  includes the flexible base frame  2  as already mentioned above, and five elongate blades  3 . Rather than being connected directly to the base frame as in other embodiments described above, the blades  3  are supported on blade mounts  94  which are secured to the base frame  2  and extend between the edge portions  5  at positions spaced apart therealong. The blade mounts  94  have inclined slots  95  in which the blades are respectively received to permit sliding movement between the blades  3  and the mounts  94 . End members  96  with similar slots  97  are provided at the ends of the base frame and clips (not shown) are wrapped over these end members to retain the blades securely in the slots  95 ,  97 . 
   The blade structure includes an elastomeric guard member  98  with upstanding fins  99  carried by a base frame extension part connected to the edge portion  5  at the front of the blade structure by forwardly projecting frame pieces  100  spaced apart along this edge portion. The guard member  98  can be of the same general structure form as the guard member  30  described above in connection with the embodiment of  FIGS. 17 to 23 . To provide additional support for the guard member forwardly directed lugs  101  are provided on the support elements  24  of the front suspension member  22  and have upwardly facing surfaces on which the underside of guard member  98  rests. 
   It will be understood that a cap member such as a lubricating strip could be similarly provided on the blade structure  1 , at the rear side thereof, either as well as or instead of the guard member  98  at the front side of the blade structure. Also, a segmented lubricating strip or other form of cap member, could be molded onto the supporting elements  24  to the rear of the blade structure  1  in similar manner to the way in which the segmented guard is molded onto the support elements at the front of the blade structure in the embodiment shown in  FIGS. 24 to 30 . 
   The described safety razor blade units described above are capable of conforming to skin contours ensuring shaving contact along the blades even when fairly sharp curvatures, such as in the region of a jawbone are encountered, and as a result an improved shaving efficiency can be achieved. 
   It should be understood that the foregoing description of the preferred embodiment is given by way of non-limiting example only and that modifications and variations are possible without departing from the scope of the invention as defined by the claims which follow. In addition, features described in relation to specific embodiments can be included in other embodiments. Thus, the different forms of blade structure included in the respective embodiments can be utilized with the various forms of supporting structures and guiding arrangements incorporated in other blade unit embodiments. 
   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.” 
   All documents cited in the Detailed Description of the Invention are, in relevant part, incorporated herein by reference; the citation of any document is not to be construed as an admission that it is prior art with respect to the present invention. 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.