Shaver having adaptive surface

Abstract

A shaver comprises a skin engaging portion and a cutting element, wherein the skin engaging portion comprises a force-generating member that can be selectively activated during use to increase or decrease a force of attraction to the skin of a user. The force-generating members may be electro-adhesive elements. A controller may be provided to selectively activate these elements.

Claims

1. A shaver comprising: a skin engaging portion and a cutting element, wherein the skin engaging portion comprises a force-generating member, configured and arranged to generate a force of attraction to the skin of a user, wherein the force-generating member comprises an electro-adhesive element comprising at least two charge-holding electrodes connected to a voltage source to output a voltage to induce a local charge onto the skin of the user, the electro-adhesive element covered by an insulating layer to prevent contact between the at least two charge-holding electrodes and the skin, a control element configured to selectively adjust said force of attraction during use, wherein the control element comprises a sensor for measuring a parameter associated with the skin and, a controller configured to control the voltage source to change the voltage to selectively adapt the force of attraction in response to a measured property of the parameter.

2. The shaver according to claim 1, wherein the parameter is indicative of a direction of movement of the skin engaging portion with respect to the skin.

3. The shaver according to claim 2, wherein the controller is arranged to selectively adjust the force of attraction of the force-generating members located ahead of the cutting element in a measured direction of movement of the shaver across the skin.

4. The shaver according to claim 2, wherein the skin engaging portion comprises a face plate in which a plurality of cutting elements are located, each comprising a rotary shaving head having a rotating cutter, and a plurality of force-generating members are provided, distributed around a periphery of the face plate, wherein the controller is operable in response to a direction of movement measured by the sensor to selectively increase the force of attraction of those force generating members located ahead of the rotary shaving heads with respect to the measured direction of movement.

5. The shaver according to claim 1, wherein the parameter is indicative of a degree of doming of the skin ahead of the cutting element.

6. The shaver according to claim 5, wherein the controller is arranged to increase the force of attraction on detection of the degree of doming exceeding a predetermined value.

7. The shaver according to claim 1, wherein the skin engaging portion comprises a plurality of force-generating members and the force of attraction of each force-generating member can be selectively adapted independently of the other force-generating members.

8. The shaver according to claim 1, wherein the cutting element is moveable with respect to the skin engaging portion to perform cutting of hairs during shaving.

9. The shaver according to claim 8, wherein the shaver comprises a plurality of cutting elements each comprising a rotary shaving head having a rotating cutter.

10. The shaver according to claim 1, wherein the shaver is a wet-shaver having one or more elongate blades mounted in a guard.

11. The shaver according to claim 1, wherein the cutting element is moveable with respect to the skin engaging portion to cut hairs during shaving.

12. A method of controlling operation of a shaver comprising: moving a skin engaging portion of the shaver across a skin of a user in a direction of motion, whereby the skin engaging portion engages the skin and a cutting element of the shaver engages hairs to be cut, wherein the skin engaging portion includes a force-generating member configured to generate a force of attraction; adjusting the force of attraction between the skin and at least a region of the skin engaging portion during said movement, in order to adjust a degree of stretching of the skin ahead of the cutting element, wherein the force-generating member comprises an electro-adhesive element comprising two charge-holding electrodes connected to a voltage source to output a voltage to induce a local charge onto the skin of the user, the electro-adhesive element being covered by an insulating layer to prevent contact between the at least two charge-holding electrodes and the skin; measuring a parameter associated with the skin; and selectively adapting the force of attraction in response to a measured property of the parameter by controlling the voltage source to change the voltage.

13. A shaver comprising: a skin engaging portion: and a cutting element, wherein the skin engaging portion comprises a force-generating member, configured and arranged to generate a force of attraction to the skin of a user, wherein the force-generating member comprises an electro-adhesive element comprising adjacent first and second charge-holding electrodes covered by an insulating layer to prevent contact between the electrodes and the skin and connected to a DC source such that the first and second electrodes may be oppositely charged with respect to each other, a control element configured to selectively adjust said force of attraction during use, wherein the control element comprises a sensor for measuring a parameter associated with the skin and, a controller configured to selectively adapt the force of attraction in response to a measured property of the parameter.

14. The shaver according to claim 13, wherein the parameter is indicative of a direction of movement of the skin engaging portion with respect to the skin.

15. The shaver according to claim 13, wherein the parameter is indicative of a degree of doming of the skin ahead of the cutting element.

16. The shaver according to claim 13, wherein the controller is arranged to increase the force of attraction on detection of the degree of doming exceeding a predetermined value.

17. The shaver according to claim 13, wherein the skin engaging portion comprises a plurality of force-generating members and the force of attraction of each force-generating member can be selectively adapted independently of the other force-generating members.

18. The shaver according to claim 13, wherein the controller is arranged to selectively adjust the force of attraction of the force-generating member located ahead of the cutting element in a measured direction of movement of the shaver across the skin.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The features and advantages of the invention will be appreciated upon reference to the following drawings of a number of exemplary embodiments, in which:

(2) FIG. 1 shows a schematic cross-section of a conventional wet shaver;

(3) FIG. 2 shows a schematic cross-section of a shaver according to a first embodiment of the present invention

(4) FIG. 3 shows a perspective view of a conventional rotary shaver;

(5) FIG. 4 shows a partial cross-section through the shaver of FIG. 3 along line IV-IV;

(6) FIG. 5 shows a schematic cross-section through a rotary shaver according to the present invention;

(7) FIG. 6 shows a frontal view of the face plate of a rotary shaver according to a second embodiment of the invention; and

(8) FIGS. 7A and 7B show views of the shaver of FIG. 6 during use.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(9) FIG. 1 shows a schematic cross-sectional view of a conventional wet shaver 1 comprising a handle 2, a guard 4 and a pair of cutting blades 6 mounted within the guard 4. The guard has a skin-engaging portion 8 and the cutting edges 10 of the blades 6 lie approximately in the plane of the skin-engaging portion 8.

(10) During use, the skin-engaging portion 8 of the shaver 1 is pressed against the user's skin S and moved in a direction M. Due to the pressure exerted by the blades 6 and its inherent elasticity, the skin S is caused to form a bulge B extending towards the guard 4 in those areas where it is unsupported, such as between the blades 6 and between the blades 6 and the guard 4. This effect is known as doming. In order to reduce doming, the guard is provided with a skin-stretcher 12 ahead of the blades 6 and a lubricity strip 14 behind the blades 6. The skin-stretcher 12 is a region of increased friction comprising a ribbed rubber-like portion. The lubricity strip 14 comprises a lubricious water-soluble polymer and provides a region of reduced friction. The net effect of these regions is to cause the skin to be stretched or held taut in the area of the blades, thus reducing the amount of doming.

(11) FIG. 2 shows a wet shaver 20A according to a first embodiment of the present invention in a schematic cross-sectional view similar to that of FIG. 1, in which like elements are given similar references. The shaver 20 is generally similar to the conventional shaver 1, with the exception of the skin-stretcher 12, which is replaced by an electro-adhesive element 22. The electro-adhesive element 22 comprises a plurality of electrodes 24 embedded in an insulating layer 26. Alternate electrodes 24′, 24″ are connected to +ive and −ive terminals of a DC voltage source 28. By connecting the voltage source 28, the electrodes 24 become charged and induce a local charge onto the skin S, which is thus attracted by electrostatic force towards the element 22. FIG. 2 also shows a sensor 30 located on the guard 4 for determining the degree of skin doming ahead of the blades 6. The sensor 30 is an infrared (IR) photodiode capable of detecting IR radiation. An IR light source in the form of an LED 32 is also located within the guard 4 at a slight distance from the sensor 30. The sensor 30 and LED 32 are both connected to a controller 34, which includes appropriate circuitry for processing their signals. In use, the LED 32 emits IR light, which is reflected by the skin S. The controller 34 is set to determine when a bulge B is formed. At this point, a signal is given to the voltage source 28 to increase the applied voltage to the electrodes 24 in order to increase the electro-adhesive force. This results in increased friction ahead of the blades 6 and greater stretching of the skin S, leading to a reduction in the size of the bulge B. Although a simple control principle has been described, the skilled person will be well aware that more complex sensor circuitry may be used to evaluate proximity by modulation and triangulation techniques and that alternative acoustic, piezo-electric and tactile sensors may also be employed.

(12) FIG. 3 illustrates a conventional rotary electric shaver 100 used for “dry” shaving. The shaver 100 comprises a body 101 and three heads 102 mounted in a face plate 104. Each of the heads comprises an outer cap 106, having a plurality of hair receiving slots 108 by which hairs may enter into the cap 106 and be cut by a rotating cutter beneath (see below).

(13) FIG. 4 shows a detail through one of the heads 102 taken on line IV-IV in FIG. 3. Showing a hair H protruding through slot 108 of cap 106. Cutter 110 is shown moving in direction X to cut hair H by interaction with the slot 108 as is otherwise conventional. FIG. 4 also shows the manner in which the skin S bulges into the slots 108 at B. In this view, the head 102 is moving in the direction M which corresponds to the direction X. The bulge B is therefore pushed against one side of the slot 108. It will however be understood that the cutter 110 rotates and its local direction of movement X does not therefore always correspond to the direction of movement M of the head 102 across the skin S.

(14) Due to the bulge B of skin into the slots 108, the skin S may become damaged by contact with the cutter 110. This damage may be reduced by various means, including increasing the thickness of the cap 106 and reducing the width of the slots 108. Most of these adaptations have a negative effect on the closeness of the ultimate shave that can be achieved.

(15) FIG. 5 shows a schematic cross section through part of a rotary shaver 100A according to an embodiment of the present invention. Like elements to those of FIGS. 3 and 4 will be designated with like numerals.

(16) According to FIG. 5, the face plate 104 is provided with electro-adhesive elements 122. The electro-adhesive elements 122 each comprise a plurality of electrodes 124 embedded in an insulating layer 126 in the same manner as those described above in relation to FIG. 2. Alternate electrodes 124′, 124″ are connected to +ive and −ive terminals of a DC voltage source 128. By connecting the voltage source 128, the electrodes 24 become charged and induce a local charge onto the skin S, which is thus attracted by electrostatic force towards the element 122.

(17) Also similarly to FIG. 2, a sensor 130 is located on the face plate 104 for determining the degree of skin doming. The sensor 130 is an IR photodiode which operates together with an IR LED 132 to determine the bulging of the skin S through the slots 108 in the cap 106. The sensor 130 and LED 132 are both connected to a controller 134, which includes appropriate circuitry for processing their signals. In use, the LED 132 emits IR light, which is reflected by the skin S. The controller 134 is set to determine an amount of bulge B and issue a signal to the voltage source 128 to increase the applied voltage to the electrodes 124 in order to adjust the electro-adhesive force as required. In the present embodiment, bulging is measured through the cap but it is understood that this may be measured at various positions including at a recess formed in the face plate, ahead of the face plate or between the face plate and the cap or foil.

(18) Although a simple control principle has been described, the skilled person will be well aware that more complex sensor circuitry may be used to evaluate proximity by modulation and triangulation techniques and that alternative acoustic, piezo-electric and tactile sensors may also be employed.

(19) FIG. 6 shows a schematic frontal view of the face plate 104 of a rotary shaver 100B according to a further embodiment of the invention. Like elements to those of FIGS. 3 and 5 are given like references.

(20) FIG. 6 differs from the embodiment of FIG. 5 by the presence of a plurality of electro-adhesive elements 122 distributed around the periphery of the face plate 104 and an optical direction sensor 138 which in this embodiment is located at the centre of the face plate. The optical sensor 138 is operatively connected to the controller 134.

(21) FIGS. 7A and 7B illustrate frontal views of the face plate 104 of FIG. 6 during operation of the shaver 100B. During use, the optical sensor 138 takes images at a frequency of around 30 Hz and the controller 134 calculates a motion vector from the differences between successive images. The controller 134 uses the motion vector to determine the direction and speed of movement M. Based on this measurement, it increases the attractive force of the electro-adhesive elements 122 that are located ahead of the heads 102 and it decreases the attractive force of the elements 122 that are located behind the heads 102, relative to the direction of movement M. The skin is thus held tight and skin doming is reduced.

(22) Thus, the invention has been described by reference to certain embodiments discussed above. It will be recognized that these embodiments are susceptible to various modifications and alternative forms well known to those of skill in the art. In particular, the arrangement of FIGS. 5 to 7 may also be applied to reciprocating shavers using a foil instead of the cap disclosed.

(23) Many modifications in addition to those described above may be made to the structures and techniques described herein without departing from the spirit and scope of the invention. Accordingly, although specific embodiments have been described, these are examples only and are not limiting upon the scope of the invention.