The present invention relates to a linkage mechanism for a razor, having a cartridge rockably mounted on a handle. The invention also relates to a method of mounting a component, e.g. a razor cartridge, for rocking about a virtual pivot axis.
Four bar linkages have been proposed to generate a virtual pivot axis and/or a side-to-side swivel axis in wet razors as in U.S. Pat. No. 6,115,924 (Oldroyd). Reference may also be made to U.S. Pat. No. 3,935,639 (Terry et al.) which discloses a four bar box-like structure arranged parallel to the longitudinal axis of the cutting head of a wet razor.
Other four-bar linkages in wet razors are known from U.S. Pat. No. 5,535,518 (Althaus), which purports to describe a parallelogram linkage in which each of two transverse links can buckle at a bend joint to unload a wet razor cartridge, and from U.S. Pat. No. 5,953,824 (Ferraro et al.), which discloses a linkage whose longitudinal arms have slots which are cammed by motion relative to fixed pins on the housing as the base transverse link rocks from side to side, in order allegedly to maintain a relatively constant distance between the razor head mounting pins.
Dry shavers having rockable heads are known. The rocking of the shaver head facilitates good contact between the shaver head and the user's skin during shaving.
WO 93/12916 (U.S. Pat. No. 6,098,289 (Wetzel et al.)) discloses a dry shaver having a head rockably mounted on a shaver body by means of first and second linkage mechanisms at respective ends of the head. Each linkage mechanism comprises a pair of transverse link members and a pair of vertical link arms pivotally mounted on the head and depending therefrom. Each arm is mounted on the shaver body by means of the transverse link members pivotably attached to the link arms at respective ends and to the shaver body at a central pivot axis lying in a common plane of symmetry of the first and second linkage mechanisms. The resulting four-bar linkage permits the head to rock about a virtual pivot axis located above its points of physical attachment to the link arms. This arrangement is a symmetric parallelogram, with the congruent pivot locations all lying in parallel lines.
Further linkage mechanisms of this type are described in U.S. Pat. Nos. 5,704,126 (Franke et al.), Pat. No. 5,159,755 (Jestaädt et al.) and Pat. No. 4,797,997 (Packham et al.).
It is known in the field of dry shavers, e.g. in those distributed widely in the United States by the company Braun under the trade designations “Flex Integral” or “Synchro”, to have the shaving head mounted on a pin bearing defining a pivot axis about which the head travels in an arc of about +/−24 degrees about a rest position.
As mentioned above, an advantage of the four bar linkage mechanism of the type known from U.S. Pat. Nos. 6,098,289 and 6,115,924 is that, as described in more detail hereinafter, a virtual pivot centre may be produced well above the points of attachment of the vertical side members to the shaving head. In fact, the virtual pivot may be located on, above or even below skin level, in dependence upon the height of the transverse link members, typically in the form of pivoting triangles or bell crank links. This may be achieved without the need for a physical upper pivot location. However, a disadvantage of the mechanism is that the two vertical side members have to be arranged essentially parallel to the vertical plane of symmetry of the mechanism. In other words, the three points of attachment of each arm to, respectively, the rocking head, the first transverse link member and the second transverse link member lie on a straight line parallel to the plane of symmetry. Applicant has recognized that the resulting mechanism is relatively bulky and cannot be accommodated in a slim handle.
According to one aspect of the invention, there is provided a linkage mechanism for a shaving appliance having a cartridge carrying at least one blade and mounted on the appliance handle for rocking about a virtual axis generated by the linkage, said linkage mechanism mounted on a handle and comprising: a pair of spaced support arms for pivotable attachment to the cartridge at first and second pivot axes, said first and second pivot axes being spaced by a first distance; a first transverse link member pivotably mounted on said handle for rotation about a third axis and being pivotably attached to each of said support arms at fourth and fifth pivot axes spaced by a second distance less than the first distance; and second and third transverse link members pivotably mounted on the handle at respective first ends thereof and being pivotably attached at respective second ends thereof to respective ones of said support arms at sixth and seventh pivot axes, said first, second, third, fourth, fifth, sixth and seventh axes being mutually parallel.
A particularly compact arrangement is achieved when said sixth and seventh pivot axes are spaced by a third distance less than said first distance. Here, some further possibilities exist: either the third distance is less than the second distance, or vice versa. Also, this third distance could be of equal magnitude as the second distance.
Ergonomic design freedom is maximized when said respective first ends of the second and third transverse link members are pivotally mounted on the handle at eighth and ninth pivot axes which are spaced apart, and parallel to said first and second axes (see e.g.
Constructional simplilcity is achieved when the distance between said first and sixth axes equals the distance between said second and seventh axes (see e.g.
In certain circumstances, an asymmetric construction may be preferred, in which the distance between said first and sixth axes is greater than the distance between said second and seventh axes (see e.g.
It is preferred that the distance between said first and fourth axes equals the distance between said second and fifth axes (see e.g.
Here a symmetrical arrangement may preferably be achieved when the distance between said first and sixth axes is less than the distance between said first and fourth axes (see e,g.
Alternatively, another compact arrangement is achieved when the distance between said first and sixth axes is greater than the distance between said first and fourth axes (see e.g.
Other advantages of the present invention lie in the capacity of the linkage arrangement to permit a very large arc of rocking motion in proportion to the relatively slender handle or body in which the linkage is accommodated.
Preferably, there are first and second spaced linkage mechanisms supporting the cartridge
According to another aspect of the invention, there is provided a linkage mechanism for carrying a razor cartridge which comprises a five-bar linkage pivotally supporting a cartridge for rotation relative to a handle about a virtual pivot axis. In a preferred embodiment, there are two spaced support arms which are pivotally connectable to a hair removal cartridge; a first common transverse link member pivotally mounted on the handle and pivotably attached to each of the support arms; and second and third stabilizing links pivotably mounted on the handle at respective first ends thereof and being pivotally attached at respective second ends thereof to respective ones of said support arms. In such an embodiment, the hair removal cartridge is not kinematically required as part of the “five-bar” linkage. When the second and third stabilizing links are pivoted at their respective first ends to the handle, these second and third links are movable relative to one another. In preferred embodiments the two spaced support arms are not parallel to one another.
According to another aspect of the invention, the razor cartridge itself kinematically forms one of the links of the five-bar linkage wherein the hair removal cartridge is pivotally supported for rotation relative to a handle about a virtual pivot axis. In such an embodiment, the five-bar linkage is determined by two spaced support arms which are pivotally connected to the cartridge; a first common transverse link member pivotally mounted on the handle and pivotably attached to each of the support arms; and at least one stabilizing link pivotably mounted on the handle at a first end thereof and pivotally attached at a respective second end thereof to one of said support arms. An additional transverse stabilizing arm may optionally be provided, for example to be more robust under load or to stabilize the support arms in the event the cartridge were detached.
According to a further aspect of the invention, there is provided a method of mounting a component, e.g. a razor cartridge for rocking about a virtual axis, the method comprising the following steps: pivotably attaching a pair of spaced support arms to the cartridge at first and second pivot axes, said first and second pivot axes being spaced by a first distance; pivotably mounting a first transverse link member on a handle for rotation about a third axis and pivotably attaching the first link member to each of said support arms, at fourth and fifth pivot axes spaced by a second distance less than the first distance; and pivotably mounting second and third transverse link members on the body at respective second ends thereof and pivotably attaching the second and third link members at respective second ends thereof to respective ones of said support arms at sixth and seventh pivot axes spaced by a third distance, said first to seventh axes being mutually parallel.
For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings.
FIGS. 5 to 7 show a schematic side view of a further linkage mechanism according to the invention;
FIGS. 8 to 10 show a schematic side view of a further linkage mechanism according to the invention;
FIGS. 11 to 13 show a schematic side view of a further linkage mechanism according to the invention;
FIGS. 14 to 16 show a schematic side view of a further linkage mechanism according to the invention;
FIGS. 17 to 19 show a schematic side view of a further linkage mechanism according to the invention;
FIGS. 20 to 26 show schematic views of linkage mechanisms according to embodiments of the invention, in which dimensions are indicated;
The linkage arrangement known from U.S. Pat. No, 6,115,924, which is hereby incorporated by reference, will be described in more detail with reference to
The bell crank levers 73 and 74 are pivoted at respective pivot points 77 and 78 to fixed points of the handle. These fixed points of the shaver frame are located on a central plane 75 of the linkage mechanism, this plane forming a plane of symmetry when the mechanism is in the neutral position shown in
Each of the vertical side members 71 and 72 is attached to the remainder of the mechanism at three pivot axes. For example, side member 71 is attached to the rocking cartridge R at axis 81, to the transverse link member 73 at axis 82, and to the transverse link member 74 at axis 83. Similarly, the second vertical side member 72 is attached at axes 84, 85 and 86 respectively.
Applicant herein has recognized that in order to function correctly, the pivot axes 81, 82 and 83 have to lie in a common plane parallel to a similar plane containing the pivot axes 84, 85 and 86. Each plane is moreover parallel to the central plane of symmetry 75. If, as seen in this side cross-sectional view, a line connecting pivots 81, 82, 83 were not parallel to a similar line connecting pivots 84, 85, 86, the mechanism would jam. As a consequence, the width of the linkage mechanism is essentially determined by the spacing between the axes of attachment 81 and 84 to the rocking cartridge R. Applicant herein has recognized that this is a disadvantage if it is desired to make the linkage mechanism more compact, for example to produce a slim handle or handle housing.
In the cross-sectional view of linkage arrangement shown in
Several embodiments of the present invention will be described in the following.
In the present invention, the constraint, for example, that the linkage be nearly as wide as its attachment location to the cartridge, is no longer necessary. The present invention employs an upper transverse linkage arrangement which is not congruent with the lower transverse linkage portion but which nevertheless generates a virtual pivot axis to permit rocking movement of the cartridge. The embodiments of the invention employ a five bar linkage comprising a main transverse link, two lateral support arms and two transverse stabilizing links. This permits a wide range of possible positions of the virtual pivot axis and also gives the designer the ergonomic freedom to package a large cartridge together with a relatively thin and skinny handle.
In the conventional parallelogram linkage, the centres of rotation of the transverse links lie in a plane which is usually coincident with the vertical plane of symmetry of the handle. In contrast, in some of the illustrated embodiments of the present invention, the transverse stabilizing links have inboard pivot locations which are spaced laterally away from one another. In further preferred embodiments, at least one of these pivot locations, or preferably both, are spaced from the imaginary vertical plane of symmetry of the linkage mechanism.
Referring to the drawings in more detail,
At the lower end of the support arm 5 is provided a support member 18 which is riveted to the support arm 5 by means of rivets 19, 20 and 21. A similar support member 22 is riveted to the lower end of the support arm 4.
A main transverse link member 6 is pivotably mounted on a housing frame 2 at a pivot axis 17 and has two limbs or mounting ends pivotably connected to the support members 18 and 22 (also referred to as connecting links) by respective film hinges allowing pivoting about axes 15 and 16. The main transverse link may be referred to as a common link since it interconnects both support members.
Two stabilizing transverse link members 7 and 9 are also provided. An upper support member 23 is riveted to the shaver body 2. The transverse link members 7 and 9 are each pivotably connected to the upper support 23 by respective film hinges allowing pivoting about axes 8 and 10. Thus, the locations at which the stabilizing link members, preferably at the upper part of the mechanism, are connected to the housing frame are spaced apart. The link members 7 and 9 are also pivotably connected to the first and second lower support members 18 and 22 by further film hinges 13 and 14 respectively.
It will be appreciated that the distance between the upper pivot axes 11 and 12 is greater than the distance between the axes of pivot hinges 13 and 14, which in turn is greater than the distance between the axes of pivot hinges 15 and 16. In the illustrated embodiment, the two upper transverse link members 7 and 9 are pivoted to the frame member 2 on two different pivot axes 8 and 10. The pivot points 8, 10 and 17 thus form the vertices of an isosceles triangle. It will be appreciated that in other embodiments, see e.g.
It will also be appreciated that in this embodiment the pivot axes associated with the right-hand support arm 5, i.e. axes 11, 13 and 15, lie in a first common plane (that is, as viewed in transverse cross-section as in
In the embodiment of FIGS. 1 to 4, the head 1 can pivot by an angle of ±9.5°. Modification of the design by enlargement of the lower transverse link member 6 and corresponding adjustment of the lengths of the upper transverse link members 7 and 9, can result in an increased pivot angle. Further modifications will occur to those skilled in the art on the basis of the above disclosure. For example, the use of film hinges is not essential. These could equally be replaced by pin hinges, as shown in FIGS. 5 to 19. Moreover, although it is thought essential to provide two transverse stabilizing link members 7 and 9 which are articulated relative one another (that is, they move relative to one another) to avoid the mechanism locking up, it is not essential that these should be pivoted at spaced pivot points. It would be equally possible for the transverse stabilizing link members 7 and 9 to be pivoted on the handle 2 at a common axis as shown in FIGS. 8 to 10. It would even be possible for the transverse link members 7 and 9 to cross over each other or over the central plane, such as shown in FIGS. 5 to 7. For example, with reference to
FIGS. 5 to 7 also demonstrate that the points of attachment of the stabilizing links 7 and 9 to the support arms 4 and 5 may be at differing distances from the head 1.
FIGS. 11 to 13 show a simplified embodiment essentially equivalent to that of FIGS. 1 to 3, but with pin hinges replacing the film hinges.
FIGS. 14 to 16 demonstrate that the main transverse link member 6 may be located between the head 1 and the transverse stabilizers 7 and 9.
FIGS. 17 to 19 demonstrate that it is even possible for the two stabilizers 7 and 9 to be positioned respectively above and below the main transverse link member 6.
The following table gives the height of the virtual pivot from the point of attachment of the main transverse link to the frame for a succession of angles of rotation of the main transverse link member. The table gives these values for the embodiments of
It will thus be appreciated that the slight amount of deviation during rotation of the virtual pivot axis from its at-rest neutral position is used as a design trade-off considering the size of the envelope within which the linkage can be contained and the desired amount of arc travel. It is noted that when using a conventional fixed pin bearing (physical axis) or a shell-like bearing (virtual axis) to support a shaving head about a pivot axis close to the shaving plane, such a pivot axis remains theoretically unchanged through the arc of travel. The present invention's linkage generates a dynamic virtual pivot axis that moves outward towards the skin surface only a small, finite amount and is acceptably close to a static pivot axis.
At least for upper virtual triangles whose sides have lengths that are longer than the lengths of the sides of the lower triangle, then, as between two differently sized upper virtual triangles (cf.
FIGS. 22 to 26 show schematic representations of further variants of the linkage mechanism according to the invention. It may be seen that in each case the head supported by the support arms is able to rotate by a total angle of approximately 25° whilst the virtual pivot is substantially static and moves only very slightly in a vertical direction. Whilst in most of the illustrated embodiments the angle included between the two top arms is equal to the angle subtended by the two limbs of the main transverse link member,
Next, the design process by which a linkage mechanism for use in a hair removal device can be generated will be described with reference to
The linkage of the present invention is preferably oriented as shown in
Further modifications will occur to those skilled in the art. All such modifications are intended to be covered by the following claims, irrespective of their summary in the claims or their back references.
Without limiting the scope of the invention, reference numbers used herein are listed:
Number | Date | Country | Kind |
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GB 0222742.9 | Oct 2002 | GB | national |
Number | Date | Country | |
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Parent | PCT/US03/31125 | Oct 2003 | US |
Child | 11089531 | Mar 2005 | US |