Abstract:
The present invention is directed to an electric shaver having a shaver housing, and a shaving head housing that is connected to the shaver housing for pivotal movement between two end positions. The shaving head housing carries at least two shaving assemblies, of which at least one shaving assembly is retractable into the housing to a first, retracted position, and elastically biased toward a second, extended position, such that extension of the at least one shaving assembly is a function of contact pressure applied by a user. Actuating elements carried by the shaving head housing control a maximum degree of extension of the at least one shaving assembly as a function of a pivot angle between the shaver housing and the shaving head housing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of and claims priority to PCT Application Serial No. PCT/EP2007/004438, filed on May 18, 2007, through which priority is claimed under 35 U.S.C. §119(a) from German patent application number 10 2006 030 947.2, filed Jul. 5, 2006. The entire contents of PCT Application Serial No. PCT/EP2007/004438 are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This invention relates to an electric shaver with a pivotally mounted shaving head housing. 
     BACKGROUND 
     German patent application publication DE 36 10 736 A1 provides a dry shaver that includes a housing and a shaving head housing pivotable relative to the housing about a fixed pivotal axis. This shaving head housing accommodates two shaving assemblies extending parallel to one another and capable of linear oscillation, which, owing to the capability of the shaving head housing to pivot, are in a position to conform themselves optimally to the skin surface regardless of the housing&#39;s alignment condition relative to the skin surface, so that both shaving assemblies engage the skin always simultaneously, independent of the angle at which the shaver housing is held against the skin. In addition, because the two shaving assemblies are supported in the shaving head housing by a coupling block spring-loaded in vertical direction, they can react to the contact pressure applied by the user by a corresponding retracting movement, which causes the shearing plane to be lowered relative to the shaving head housing at least temporarily. For optimum conformance of the shaving assemblies to the skin to be shaved, it is of particular importance for the shaving head housing to be freely pivotable about the defined pivotal axis. Considering that the drive mechanism arranged in the housing needs to be coupled to the shaving assemblies at all times, the maximum possible pivotal range of the shaving head housing relative to the housing is limited. Embodiments of such dry shavers reduced to practice have a maximum pivotal range of less than 40°, that is, barely 20° from a mid-position in clockwise direction, and 20° in counterclockwise direction. 
     SUMMARY 
     According to one aspect of the invention, an electric shaver includes a shaver housing, and a shaving head housing that is connected to the shaver housing for pivotal movement between two end positions. The shaving head housing carries at least two shaving assemblies, of which at least one shaving assembly is retractable into the housing to a first, retracted position, and elastically biased toward a second, extended position, such that extension of the at least one shaving assembly is a function of contact pressure applied by a user. Actuating elements carried by the shaving head housing control a maximum degree of extension of the at least one shaving assembly as a function of a pivot angle between the shaver housing and the shaving head housing. 
     In some embodiments, the at least one shaving assembly is moved by the actuating elements at least partly towards the retracted position, when the at least one shaving assembly is a leading shaving assembly relative to a pivot direction. 
     In some embodiments, the at least two shaving assemblies have respective longitudinal axes extending parallel to one another and parallel to a pivotal axis of the shaving head housing, with the shaving assemblies being configured as linearly oscillating assemblies. In some arrangements, oscillation occurs along the respective longitudinal axes. 
     In some embodiments, the at least two shaving assemblies are floating-mounted in the shaving head housing. 
     In some embodiments, the at least two shaving assemblies each include an outer cutter and an under cutter biased into contact therewith. 
     In some embodiments, the actuating elements include at least one pivotable control lever that pivots in response to a pivotal movement of the shaving head housing relative to the shaver housing. 
     In some embodiments, a first arm of the control lever is acted upon by a stop, and a second arm of the control lever is coupled to at least one of the shaving assemblies. 
     In some embodiments, the at least one shaving assembly acts on another shaving assembly during at least a portion of a retraction stroke. 
     In other embodiments, the shaving head housing is lockable at a defined pivot angle with respect to the shaver housing. In some arrangements, the defined pivot angle is a maximum pivot angle. 
     In some cases, the shaving assemblies are arranged in an exchangeable frame adapted to be locked with the shaving head housing. 
     In some arrangements, an exchangeable frame is connectable to the shaving head housing, wherein the shaving assemblies are displaceably mounted in the exchangeable frame. 
     In some embodiments, the electric shaver is provided as a dry shaver. 
     Various embodiments described herein feature a shaving assembly that is biased towards a retracted position based on a contact pressure applied by a user, as well as actuating elements that control a maximum extension of the shaving assembly as a function of a pivot angle between a shaver housing and a shaving head housing. 
     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  is a view of the basic construction of a shaver including plural shaving assemblies which are arranged in a pivotal shaving head housing; 
         FIGS. 2 to 5  are various schematic views of the pivotal shaving head of a shaver of the invention; and 
         FIGS. 6 to 7  are views of the shaving head of a shaver of the invention illustrating three shaving assemblies in different pivotal positions. 
     
    
    
     Like reference symbols in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
       FIG. 1  shows in a perspective representation the basic construction of a shaver with a pivotal shaving head, including a housing  1  accommodating an electric drive mechanism and, as the case may be, single-use or rechargeable batteries or the like. Arranged on the housing  1  is an on/off switch  2  and, as the case may be, a trimmer  3  for shortening relatively long hair. Projecting from the upper end of the housing  1  is a drive element  4  which is coupled to the motor. A shaving head housing  5  receives under cutters  6  which are constructed to include cutter blocks having a plurality of blades extending in a direction transverse to the direction of oscillation. The under cutters  6  are held by a coupling element  7  which in turn is connected to the drive element  4 . Outer cutters constructed as perforated foils  8  are held in a frame  9  which is connectible to the shaving head housing by catch elements  10 , for example. The shaving head housing  5  in turn is mounted on holding arms  11  of the housing for pivotal movement about an axis X-X, for which purpose both the holding arms  11  and the shaving head housing  5  include suitable bearing points. With the drive mechanism activated, the under cutters  6  are caused to oscillate along their longitudinal axis and are thus operable in cooperation with the associated shaving foil  8  to cut off hairs extending through the perforations in the shaving foil. To accomplish this, it is necessary for the under cutter  6  to be always pressed into engagement with the shaving foil  8 , for which purpose the under cutters  6  are loaded by compression springs, not illustrated, which are seated between the shaving head housing or a component connected thereto and the under cutters. In addition, the two shaving assemblies each of which includes an under cutter  6  and a shaving foil  8  are mounted in the shaving head housing  5  in a way enabling them to perform a receding motion in vertical direction according to the drawing, whose magnitude is in turn dependent on the contact pressure applied by the user. The floating suspension enables the shaving assemblies to conform themselves closely to the skin contours to be shaved. Furthermore, the capability of the shaving head housing  5  to pivot with respect to the housing  1  enables both shaving assemblies to make optimum engagement with the skin simultaneously, regardless of the angular position of the housing relative to the skin. 
       FIGS. 2 and 3  are greatly simplified and schematic views of the kinematics of the shaving head of the shaver of the invention.  FIG. 2  shows the shaving head roughly in a mid-position relative to the housing  1 , while  FIG. 3  shows the shaving head housing  5  pivoted relative to the housing  1  to its maximum pivotal position.  FIGS. 4 and 5  correspond to  FIGS. 2 and 3 , respectively, showing however the shaving assemblies unfolded outwardly into the plane of projection through an angle of 90° for better clarity of illustration of the shaving head mechanics as a two-dimensional representation. 
     In  FIGS. 2 to 5 , the shaving head housing  5  is illustrated by a box-shaped or rectangular element  12  and is freely pivotally connected to the holding arms  11  by bearing points  13 . For the sake of clarity of illustration,  FIGS. 2 to 5  show only part of the shaving head; the remaining part of the shaving head is cut away by a cut extending perpendicularly to the longitudinal axes (see double arrows  14 ) of the shaving assemblies  16  and  15 . The whole shaving head  5  is however symmetrical to this cut-away area. Each of the shaving assemblies  15  and  16  shown in a simplified and schematic representation is composed of an outer cutter and an under cutter which are driven to oscillate relative to each other in accordance with the double arrows  14 . The details of the shaving assemblies  15 ,  16  and the drive mechanism of these elements is not illustrated in the Figures, but they include preferably an under cutter and an outer cutter biased into relative engagement and adapted to be driven to oscillate, with each shaving assembly being assembled in a prior operation as a complete module. This module in turn is floating-mounted in the shaving head housing by compression springs and suitable guides. The shaving assemblies  15 ,  16  are slidably mounted in the shaving head housing  5  by vertically oriented guide bolts and are biased vertically upwardly by compression springs  17  and  18 , respectively. The shaving assemblies are thus floating-mounted within the pivotal shaving head housing, in particular within an exchangeable frame ( 37 , see  FIG. 6  or  7 ). The guide bolts  19  which have their downwardly pointing ends secured in the shaving head housing  5  extend parallel to a center line S of the shaving head housing. 
     Control levers  21 ,  22  are pivotally mounted by respective pivot bearings  23  in an exchangeable frame securable in the shaving head housing  5 , which frame also accommodates the shaving assemblies  15 ,  16  and, as the case may be, the compression springs  17 ,  18 . In this arrangement, the control lever  21  is associated with the shaving assembly  15  and the control lever  22  with the shaving assembly  16 . The control levers  21 ,  22  are two-armed levers and include on their arms associated with the respective shaving assemblies  15  and  16  a respective follower  24  which engages in a corresponding elongated hole  25  of the associated shaving assembly. The other arm of the control lever  21  and  22  is associated with a control slide  26  and  27 , respectively, which are vertically slidably mounted in the shaving head housing. In this arrangement, the direction of displacement of the control slides  26 ,  27  is parallel to the center line S or to the longitudinal axis of the guide bolts  19 . 
     The control slides  26  and  27  are arranged in juxtaposition with the holding arms  11  and possess follower arms  28  extending in the direction of the associated holding arm  11 , accordingly in a direction transverse to the center line S. The follower arms  28  and hence the control slides  26 ,  27  can be raised by associated control trunnions  29  and  30 , respectively, depending on the pivotal movement of the shaving head housing  5  relative to the housing  1  or relative to the center line G. 
     When the shaving head  5  is in a mid-position as illustrated in  FIGS. 2 and 4  and no external load is applied to the shaving assemblies  15 ,  16 , these are urged upwardly against stops  31  of the guide bolts  19  by the compression springs  17 ,  18  in the interior of the shaving head housing  5 . The application of an external load to the shaving assemblies  15 ,  16  enables them to recede against the force of the compression springs  17 ,  18  in dependence upon the applied load. When this receding motion takes place without superimposition of a pivotal motion of the shaving head housing  5 , the associated followers  24  of the control levers  21  and  22 , respectively, are moved downwardly in accordance with the receding motion, so that the opposite lever arm is able to lift itself clear of the follower arm  28  of the corresponding control slide  26 ,  27 . The receding motion of the shaving assemblies  15 ,  16  is thus not restricted by the control levers  21 ,  22  and the control slides  26 ,  27 . In this arrangement, the receding motion can be performed not only as a parallel displacement of the shaving assemblies, but rather, a more pronounced receding motion of one side enables a tilting motion to be performed about an axis extending in a direction transverse to the longitudinal direction or direction of oscillation (double arrow  14 ) of the shaving assemblies. 
     However, when the shaving head housing  5  is pivoted with respect to the housing  1  or the holding arms  11  as shown in  FIGS. 3 and 5 , the leading shaving assembly, as seen looking in the pivot direction, is lowered relative to the shaving head housing  5  as described in the following.  FIGS. 3 and 5  show the shaving head housing  5  pivoted relative to the shaver housing in clockwise direction. This causes the shaving assembly  15  to be lowered which on such a pivotal movement is the leading one in the pivot direction. As a result of the pivotal movement described, the control slide  26  is pushed upwardly by the control trunnion  29 , while the control slide  27  is disengaged from the control trunnion  30 . The lifting motion of the control slide  26  in turn causes the control lever  21  to pivot about the pivot bearing  23 , as a result of which the follower  24  and with it the shaving assembly  15  coupled to it is moved downwardly by distance d (see  FIG. 5 ). This downward movement of the shaving assembly  15  occurs in opposition to the biasing force of the compression spring  17 , whereby the retracting stroke usable in this pivot condition is correspondingly reduced by an external load applied as the case may be. The full retracting stroke continues to be available to the shaving assembly  16 . It is solely owing to this lowering of the shaving assembly  15  as illustrated in  FIGS. 3 and 5  that the angular position of a tangent to both shaving assemblies  15  and  16  varies by angle w (see  FIG. 3 ). This angle w is added to the pivot angle between the housing  1  and the shaving head housing  5  as defined by the center lines S and G of the shaving head housing and the shaver housing, respectively. 
     In other terms, pivoting of the shaving head housing  5  serves to adjust the maximum extension of the shaving assemblies  15 ,  16 . As seen in the example of  FIG. 5 , the maximum extension position, when pivoted, is reduced by the distance d from the maximum extension position, when in the mid-position ( FIG. 4 ). Consequently, the interaction of the control levers  21 ,  22 , the control slides  26 ,  27  and the trunnions  29 ,  30  control a maximum degree of extension of the respective shaving assemblies  15 ,  16  as a function of a pivot angle between the housing  1  and the shaving head housing  5 . 
     The lowering of the shaving assembly  15  by the control slide  26  and the control lever  21  causes a compression of the compression spring  17  as a result of which the shaving head housing  5 , in the absence of the load responsible for the pivotal movement of the shaving head, locates itself automatically back into its mid-position under simultaneous relaxation of the compression spring  17 . 
       FIG. 6  shows in a perspective view a shaving head with three shaving assemblies in a mid-position. In the following, the reference numerals used in the preceding description of  FIGS. 1 to 5  will continue to be used for like parts. Arranged in the substantially cut away shaving head housing  5  which is pivotally connected to the holding arms  11  by the bearing point  13  are two shaving assemblies configured as foil shaving assemblies  15  and  16  which embrace between them a long-hair trimmer assembly  32  aligned in the same longitudinal direction. The long-hair trimmer assembly  32  includes two comb-type shearing elements known in the art, which are driven to oscillate relative to each other. All three shaving assemblies  15 ,  16  and  32  are floating-mounted, each by two guide bolts  19 , in the exchangeable frame  37  held in the shaving head housing  5  and are biased in upward direction by compression springs not illustrated in the figure, which, as the case may be, are arranged in the exchangeable frame  37 . 
     As explained in the foregoing with reference to  FIGS. 2 to 5 , the two shaving assemblies  15  and  16  are mounted in the shaving head housing  5  or in the exchangeable frame  37  and controlled by suitable kinematic elements. As shown in  FIG. 6  for the shaving assembly  15  in particular, it is mounted on two guide bolts  19  which are arranged in the area of the longitudinal end sections of the shaving assembly. To permit tilting of the shaving assemblies  15 ,  16 ,  32 , they are mounted on their two guide bolts  19  in fixed relation at the one end and in loose relation at the other end. To prevent the shaving assemblies  15 ,  16 ,  32  from rolling (rotation about the longitudinal axis), their ends are provided with a vertically extending slot which receives a respective rib  47  serving to guide the associated shaving assembly. Two control levers  21  engage with their followers  24  in elongated holes  25  of the shaving assembly  15 , with the control levers themselves being pivotally mounted in the exchangeable frame  37  by respective pivot bearings  23 . Accordingly, part of the actuating elements, namely the control levers,  21 ,  22 , is arranged in the exchangeable frame  37  while another part, namely the control slides  26 , is arranged in the shaving head housing. When the exchangeable frame  37 , which is a wearing part, is replaced, it is therefore not necessary to replace the entire actuating device. Because the shaving assembly  15  is biased in upward direction, the arm of the control lever  21  opposite the follower  24  rests against a control slide  26 . The control slides  26  are vertically slidably mounted. To this effect, their downwardly pointing end is configured to include a rod-shaped guide rail  33 . The bar-shaped follower arms  28  of the control slides  26  can be acted upon by the control trunnions  29 , which are integrally formed on a support  34  embracing the holding arm  11  at least in part and being therefore secured to it. 
     The structural design described in the foregoing applies by analogy also to the shaving assembly  16  with its corresponding components explained with reference to  FIGS. 2 to 5 , in which the control trunnions  30  capable of acting upon the control slides  27  are likewise provided on the support  34 . Serving as stops  31  for limiting the vertical upward movement of the shaving assemblies  15  and  16  are arms formed on the shaving assemblies, which arms are adapted to abut associated stops, not illustrated, within the exchangeable frame  37 . 
       FIG. 7  shows a pivoted position of the shaving head housing  5  with respect to the shaver housing  1  or the holding arms  11  in accordance with the direction of rotation P. As this pivoting movement proceeds, the control slides  26  are acted upon by the control trunnions  29  such as to cause them to be displaced upwardly. As a result, the shaving assembly  15  is pressed downwardly by the simultaneous pivotal motion of the two control levers  21 . The long-hair trimmer assembly  32  includes arms, not shown, which protrude laterally with respect to the shaving assemblies  15 ,  16  and embrace the undersides thereof. During the downward movement of the shaving assembly  15  imposed by the control levers  21  (or on a pivotal movement in opposition to the direction P of the shaving assembly  16 ), the long-hair trimmer assembly is thereby caused to follow this downward movement after the play is overcome. This ensures that upon lowering the outer shaving assembly  15  or  16  the long-hair trimmer assembly  32  does not protrude beyond a shared tangent applied to the arched shaving assemblies  15  and  16 . Any such protrusion of a long-hair trimmer assembly  32  would be detrimental to a gentle skin treatment during the shaving operation. 
     While a number of examples have been described for illustration purposes, the foregoing description is not intended to limit the scope of the invention, which is defined by the scope of the appended claims. There are and will be other examples and modifications within the scope of the following claims.