FIELD OF THE INVENTION

The present invention relates to a bodycare device for performing a skincare procedure on a subject. BACKGROUND OF THE INVENTION

Bodycare devices are used for cleansing a subject's skin. Such bodycare devices generally comprise a brush which is applied to a subject's skin to remove detritus, such as dirt, dead skin, and make-up, from the subject's skin. It is also known to provide a motor to rotate the brush and move bristles of the brush over the subject's skin.

Such bristles tend to be stiff to aid removal of detritus from the area of the subject's skin being treated. However, the use of bristles may cause discomfort, pain, and irritation to the subject due to the scraping of bristles over the skin.

It is also known to provide a bodycare device which uses one or more high pressure jets of water to cleanse and exfoliate a subject's skin. However, the use of a high pressure jet can cause discomfort, a large amount of splashing, and require a large amount of water.

US2008/125682 describes a head for applying a product includes a removable member. The member may be used to dispense a product or for massage. The head includes a body that rotates the removable member about an axis of rotation, the removable member being removably coupled to the body; and a part including a movement restriction tab that restricts movement of the removable member along the axis of rotation, the rotation of the removable member being relative to this part. The removable member is configured to be secured to the part independently of its orientation relative to the restriction tab and to be detached from the part by being moved through two movements including a rotational movement and a translational movement. Additionally, the head can be connected to a container and drive mechanism to dispense and massage a product, such as a cosmetic product, into the user's skin.

US2006/276731 describes an appliance or device for massaging and/or dispensing a product. A preferred example includes a container holding the product, preferably a cosmetic product, a housing to which the container is mounted, and a massage element mounted on this housing. A rotary driving arrangement drives the massage element about an axis of rotation of the massaging element relative to the housing. A conduit is in fluid communication between an outlet from the container and the massage element. The container is configured for the packaging and dispensing of the product under pressure, with the conduit being connected to an outlet of a dispensing valve on the container.

US2012/209151 describes an electronic skin treatment device with an integrated specimen dispenser is disclosed, with which specimen dispense can be concurrently applied to target skin area while ultrasonic vibrations, mechanical massaging motions, galvanic stimulations, or light illuminations are used and as such a customizable, easier and better skin beautification can be achieved.

US2013/110032 describes a system and method for treating a surface are provided. A flexible or adaptable pad for treating a surface may be particularly suitable for treatment of uneven surfaces. An apparatus may include a mounting section and a flexible surface comprising a plurality of treatment sections. The treatment sections may comprise an abrasive material. Cracks or grooves on a surface of the apparatus enable a first and second treatment sections to assume a respective first and second positions with respect to a treated surface. An edge of a groove may be designed to increase an abrasiveness of the apparatus and may remove material from a treated surface.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a bodycare device which substantially alleviates or overcomes the problems mentioned above.

The invention is defined by the independent claim; the dependent claims define advantageous embodiments.

According to the present invention, there is provided a bodycare device for performing a skincare procedure on a subject comprising a treatment head having a liquid contact surface which is positionable proximate to a subject's skin, a liquid feed configured to provide liquid at the liquid contact surface, and a driver configured to cause motion of the treatment head relative to a subject's skin so that a shear flow is induced in liquid at the liquid contact surface to act on said subject's skin when the liquid contact surface is positioned proximate to said subject's skin.

With this arrangement the subject is able to treat skin without the bodycare device touching the skin being treated. As the liquid is acting on the subject's skin the induced shear flow is able to lift detritus from the skin. The moving treatment head does not contact the skin and so the bodycare device does not cause discomfort, pain, or irritation to the subject.

The driver may be configured to rotate the treatment head about a rotational axis perpendicular to the liquid contact surface.

The rotation of the treatment head causes a continuous rotational shear flow. Pressure gradients within the liquid cause a secondary flow of liquid which spirals inwards near the subject's skin and outwards near the liquid contact surface of the rotating treatment head. This induces a helical flow pattern helping to reduce the amount of splashing and therefore, the amount of liquid required by the bodycare device as well as transporting detritus towards the liquid contact surface.

The treatment head may be axially symmetric and a symmetric axis of the treatment head is co-axial with the rotational axis.

Therefore, the treatment head contacts the same amount of liquid in all radial directions. This helps to produce symmetrical velocity and pressure gradients in the liquid which yields a more symmetrical and therefore, more even and effective skincare procedure for the subject's skin.

The liquid feed may be configured to provide liquid at the liquid contact surface to form a liquid buffer between the treatment head and a subject's skin when the liquid contact surface is positioned proximate to said subject's skin.

Therefore, fresh liquid is provided at the liquid contact surface to be used to perform a skincare procedure on the subject's skin and can replace liquid lost due to splashing and/or leaking. The liquid buffer prevents the treatment head from coming into contact with the subject's skin whilst rotating which helps to prevent pain and injury to the subject.

The bodycare device may further comprise a housing with a cavity, wherein the treatment head is in the housing and the driver is configured to cause motion of the treatment head relative to the housing.

The housing may be placed against a subject's skin which reduces the amount of splashing and leaking of liquid. Therefore, the amount of liquid the bodycare device requires is reduced. Furthermore, the housing may prevent the treatment head contacting the subject's skin. The shear force between the housing and the liquid in the cavity enhances the effectiveness of the helical flow and therefore, the effectiveness of the bodycare device. The liquid contact surface may extend parallel to a plane of an opening of the cavity.

Therefore, symmetrical pressure and velocity distributions exist in the liquid used to treat the subject's skin which enhances the effectiveness of the helical flow. This enables the bodycare device to provide a more even and effective treatment as well as reduce leakage of the liquid.

The distance between the liquid contact surface and the plane of the opening may be adjustable.

Therefore, the bodycare device may be optimised to provide the best skincare procedure for the subject's skin. For, example, the liquid contact surface may be moved closer to the plane of the opening, and therefore, the subject's skin, in order to induce a larger shear force and increase the effectiveness of the bodycare device.

The liquid contact surface may be planar.

Therefore, the liquid contact surface only applies a shear force on the liquid. This helps to reduce unwanted flow patterns in liquid in the cavity which would disrupt the helical flow and reduce the effectiveness of the bodycare device.

The treatment head may be a disc.

Therefore, the treatment head has circular symmetry and is able to create a symmetrical shear flow in the liquid.

The liquid feed may be configured to provide liquid at the liquid contact surface at one of the peripheral edge of the treatment head and a mid-section of the treatment head.

Liquid can be introduced, or supplied, at the liquid contact surface to replace any liquid that has leaked out or splashed the subject. The liquid may be introduced at the peripheral edge of the treatment head in order to disrupt the liquid's helical flow in the cavity as little as possible. The liquid may be introduced at the mid-section of the treatment head to reduce the complexity of the bodycare device and ensure a more uniform distribution of liquid over the liquid contact surface.

The liquid feed may be configured to draw liquid away from the liquid contact surface.

Liquid containing detritus can be removed from the liquid contact surface and transferred away from the subject's skin. Therefore, removing liquid introduced at the liquid contact surface from the liquid contact surface allows space for fresh liquid at the liquid contact surface without leaking and splashing over areas of the subject's skin not being treated.

The liquid feed may be configured to draw liquid from the liquid contact surface at one of the mid-section of the treatment head and the peripheral edge of the treatment head.

Liquid can be removed from the liquid contact surface at the mid-section of the treatment head in order to disrupt the helical flow as little as possible and to remove detritus which rises up from the subject's skin in the helical flow. Liquid can be removed from the liquid contact surface at the peripheral edge of the treatment head in order to ensure a more uniform distribution of liquid over the liquid contact surface and to remove larger particles flowing near the periphery due to centrifugal forces.

The liquid feed may be configured to re-circulate liquid drawn from the liquid contact surface to provide liquid at the liquid contact surface.

Therefore, the amount of liquid required by the bodycare device is minimised. It also means that the bodycare device may be "wireless" as it would not require a connection to water mains during use.

The bodycare device may further comprise a flow controller configured to control the flow rate of liquid supplied at the liquid contact surface by the liquid feed.

The flow controller can help to ensure that the liquid level in the cavity is correct to provide effective cleaning whilst reducing the amount of liquid required by the bodycare device. Therefore, the liquid feed is able to vary the rate at which liquid is provided at and/or drawn from the liquid contact surface.

The bodycare device may further comprise a controller configured to adjust the rate of motion of the treatment head in dependence on the distance between the liquid contact surface and a subject's skin when the liquid contact surface is positioned proximate to said subject's skin.

Therefore, the bodycare device may have an inbuilt safety feature that enables the driver to reduce the rotational speed of the treatment head to prevent it injuring the subject in the event that the treatment head gets too close to or contacts the subject's skin. Alternatively, the driver may be able to increase the rotational speed of the treatment head to overcome the increase in shear force, felt on the treatment head caused by the liquid, such that the performance of the bodycare device is constant up to a cut-off point.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Fig. 1 shows a schematic side view of an embodiment of the bodycare device for treating skin;

Fig. 2 shows a schematic cross-sectional side view of a treatment end of the embodiment of the bodycare device for treating skin shown in Fig. 1;

Fig. 3 shows a schematic cross-sectional view of a liquid in a treatment zone in the treatment end of the embodiment of the bodycare device shown in Fig. 1, with the liquid depth exaggerated for clarity, and the primary and secondary flow fields present during use; and

Fig. 4 shows a schematic perspective view of the velocity gradients within the liquid present in the treatment zone in the treatment end of the embodiment of the bodycare device shown in Fig.l when the bodycare device is in use.

DETAILED DESCRIPTION OF EMBODIMENTS

A bodycare device 1 for performing a cleansing skincare procedure on a subject is shown in Fig. 1. The bodycare device 1 has a housing 2. A treatment end 3 is defined at one end of the bodycare device 1. The housing 2 has a handle portion 4. The handle portion 4 is elongate. The handle portion 4 enables a subject to hold and manoeuvre the bodycare device 1 and to position the treatment end 3. The housing 2 has a cavity 5, as shown in Fig. 2. The cavity 5 is at the treatment end 3 of the bodycare device 1. The cavity 5 is cylindrical. The cavity 5 has an opening 6 in the treatment end 3. The opening 6 provides access to the cavity 5. The opening 6 is circular.

The bodycare device 1 has a treatment head 7. The treatment head 7 enables a cleansing skincare procedure to be applied to skin of a subject during use of the bodycare device 1, as will become apparent hereinafter. The treatment head 7 is in the cavity 5. The treatment head 7 is rotatable in the cavity 5 about a rotational axis. That is, the treatment head 7 is rotatable relative to the housing 2. The treatment head 7 has a liquid contact surface 8. The liquid contact surface 8 is exposed at the treatment end 3 of the bodycare device 1. The liquid contact surface 8 faces the opening 6.

The treatment head 7 is mounted on a drive shaft 9. The drive shaft 9 connects the treatment head 7 to a driver 10. The driver 10 is received in the housing 2. The driver 10 is operable to rotate the drive shaft 9. The drive shaft 9 rotates the treatment head 7. In another embodiment, the treatment head 7 and drive shaft 9 are integrally formed. The driver 10 is therefore configured to rotate the treatment head 7 relative to the subject's skin.

The drive shaft 9 extends along the longitudinal axis, that is, the centre, of the treatment head 7 of the bodycare device 1. The longitudinal axis of the drive shaft 9 is its rotational axis. The longitudinal axis of the treatment end 3 and the longitudinal axis of the drive shaft 9 are concentric and on the rotational axis of symmetry.

The drive shaft 9 transfers the rotational force to the treatment head 7.

Therefore, the treatment head 7 rotates in the cavity 5 in the treatment end 3. In the present embodiment, the rotational speed of the treatment head 7 is 1000 rpm. However, it will be understood that the rotational speed of the treatment head 7 may be in the range of 700 rpm and 3600 rpm.

However, it will be understood that in an alternative embodiment, the driver

10 may be located in the treatment end 3. The driver 10 is connected to an electrical supply

(not shown). The electrical supply may be, for example, but not limited to, a mains supply (not shown) or a battery pack (not shown) located in the handle portion 4 of the housing 2.

The battery pack may be replaceable and/or rechargeable.

The bodycare device 1 further comprises a liquid feed 11. The liquid feed 11 comprises a liquid flow path throughout the bodycare device 1. The liquid feed 11 is configured to provide liquid at the liquid contact surface 8. The liquid feed 11 comprises an outer liquid passageway 12. In the present embodiment, the outer liquid passageway 12 acts as a liquid inlet passageway to allow the liquid feed 11 to provide liquid at the liquid contact surface 8 through a liquid inlet.

The liquid feed 11 is also configured to draw liquid provided at the liquid contact surface 8 away from the liquid contact surface 8. The liquid feed 11 comprises an inner liquid passageway 13. In the present embodiment, the inner liquid passageway 13 acts as a liquid outlet passageway to allow the liquid feed 11 to draw liquid from the liquid contact surface 8 through a liquid outlet.

The bodycare device 1 may further comprise a controller (not shown). The controller is configured to adjust the rate of motion of the treatment head 7 depending on the distance between the liquid contact surface 8 and the subject's skin. The controller varies the rate of rotation of the treatment head 7 about the rotational axis by controlling the output of the driver 10.

The treatment head 7 has a generally circular cross-section. The diameter of the treatment head 7 is less than the diameter of the treatment end 3 of the housing 2. The diameter of the treatment head 7 is less than or equal to the diameter of the opening 6 to the cavity 5. In the present embodiment, the diameter of the treatment head 7 is 10 mm. The diameter of the treatment head 7 may be greater than or equal to 1 mm. In an embodiment in which the diameter of the treatment head 7 is close to 1 mm an array of treatment heads 7 are used to cover a large surface of the subject's skin. The diameter of the treatment head 7 may be less than or equal to 50 mm. This provides an ergonomic benefit for a user.

The treatment head 7 has a peripheral edge 14. The peripheral edge 14 is the circumference of the treatment head 7. The peripheral edge 14 is the outermost part of the treatment head 7.

The treatment head 7 further comprises a treatment head aperture 15. The treatment head aperture 15 is located in a mid-section 16 of the treatment head 7. The treatment head aperture 15 extends from the mid-section 16 of the liquid contact surface 8 through the treatment head 7 towards the handle portion 4 of the housing 2.

The mid-section 16 of the treatment head 7 is a part of the treatment head 7 inside the peripheral edge 14. That is, the mid-section 16 may refer to the origin of the circular liquid contact surface 8 of the treatment head 7, the point of circular symmetry, or to a part of the treatment head 7 between the origin and the peripheral edge 14.

In the present embodiment, the treatment head aperture 15 has a circular cross- section and is concentric with the treatment head 7. Therefore, the treatment head aperture 15 is located centrally and the treatment head aperture 15 of the treatment head 7 is defined by an inner treatment head edge 17.

The treatment head 7 is an annular disc. The liquid contact surface 8 has an annular cross-section and a planar surface configured to induce a symmetrical shear stress in the liquid between the liquid contact surface 8 and the subject's skin. This liquid is in a treatment zone 18. The treatment zone 18 is defined below the liquid contact surface 8 as the space between the liquid contact surface 8 and the subject's skin.

The planar liquid contact surface 8 is a smooth surface. The smooth surface provides a uniform contact area. The uniformity of the contact area provides a rotationally symmetrical force on the liquid to produce a more symmetrical helical flow which increases the effectiveness of the bodycare device 1. The liquid contact surface 8 may be formed from, for example, but not limited to ceramics, metals such as stainless steel and aluminium, or polymers such as polymethyl methacrylate, polystyrene, polytetrafluoroethylene, and polypropylene. In an alternative embodiment, the liquid contact surface 8 may be a coating (not shown) on the treatment head 7. The coating may be formed from, but not limited to, polytetrafluoroethylene, anodized aluminium, ceramics, silicone, and cast iron.

The liquid contact surface 8 of the treatment head 7 extends parallel to a plane of the opening 6 to the cavity 5. The liquid contact surface 8 extends parallel to the plane of the opening 6 in order to provide symmetrical pressure and velocity distributions in the liquid used to treat the subject's skin. This enables the bodycare device 1 to provide a more even and effective treatment as well as reduce leakage of the liquid. However, the liquid contact surface 8 is offset from the plane of the opening 6 to the cavity 5.

The treatment head 7 is located in the treatment end 3 of the housing 2. The treatment end 3 of the housing 2 is generally cylindrical. The housing 2 comprises a first portion 19 and a second portion 20. The second portion 20 is located between the handle portion 4 of the housing 2, shown in Fig. 1, and the first portion 19.

The first portion 19 of the treatment end 3 of the housing 2 is a hollow cylinder with an open end. The open end defines the opening 6. The first portion 19 comprises an end wall 21. The end wall 21 is proximate the handle portion 4 of the housing 2. The end wall 21 is opposite the opening 6. The end wall 21 has a generally circular cross- section.

The end wall 21 comprises an end wall aperture 22. The end wall aperture 22 is located centrally in the end wall 21, such that the end wall 21 has circular symmetry. The end wall aperture 22 has a circular cross-section and is concentric with the end wall 21. Therefore, the end wall 21 is annular. The end wall 21 comprises an inner end wall edge 23 and an outer end wall edge 24. It will be understood that the end wall 21 may have an alternative configuration, for example, but not limited to, elliptical, triangular, or square.

The first portion 19 of the treatment end 3 further comprises a peripheral wall 25. The peripheral wall 25 extends perpendicularly from the outer end wall edge 24. In the present embodiment, the peripheral wall 25 is a circumferential wall. The peripheral wall 25 extends away from the handle portion 4 of the bodycare device 1, as shown in Fig. 1.

The peripheral wall 25 has an inner face 26. The inner face 26 of the peripheral wall 25 contacts the liquid in the cavity 5. The peripheral wall 25 is configured to prevent splashing and the loss of liquid from the cavity 5. The peripheral wall 25 further comprises a free end 27. The free end 27 is distal to the end wall 21. The free end 27 is placed proximate to or against the subject's skin.

The end wall 21 and the peripheral wall 25 define the cavity 5 in the first portion 19 of the treatment end 3. The plane extending between and confined by the free end 27 of the peripheral wall 25 defines the opening 6 to the cavity 5. The plane of the opening 6 is positioned substantially parallel to the subject's skin.

The treatment head 7 is located in the first portion 19 of the treatment end 3. The liquid contact surface 8 is proximate the opening 6 of the cavity 5. That is, the distance between the end wall 21 and the liquid contact surface 8 is less than or equal to the distance between the end wall 21 and the plane of the opening 6 of the cavity 5.

The distance between the liquid contact surface 8 and the subject's skin is proportional to the size of the diameter of the treatment head 7. In the present embodiment, the distance between the liquid contact surface 8 and the subject's skin when the bodycare device 1 is in use is one fifth (1/5) of the size of the diameter of the treatment head 7. The distance between the liquid contact surface 8 and the subject's skin may be greater than or equal to one tenth (1/10) of the size of the diameter of the treatment head 7. The distance between the liquid contact surface 8 and the subject's skin may be less than or equal to one half (1/2) of the size of the diameter of the treatment head 7.

In one embodiment, the distance between the liquid contact surface 8 and the plane of the opening 6 may be adjustable such that the distance between the liquid contact surface 8 and the subject's skin can be varied.

The diameter of the treatment head 7 is less than the diameter of the opening 6. Therefore, a gap 28 exists between the peripheral edge 14 and the inner face 26 of the peripheral wall 25 around the circumference of the treatment head 7. The gap 28 is configured to be the liquid inlet to the treatment zone 18. The gap 28 allows liquid to be provided at the liquid contact surface 8 of the treatment head 7. The treatment head aperture 15 is configured to be the liquid outlet from the treatment zone 18. The treatment head aperture 15 allows liquid to be removed from the liquid contact surface 8.

The second portion 20 of the treatment end 3 of the housing 2 is a hollow tube.

The second portion 20 extends between the first portion 19 and the handle portion 4 of the housing 2. The second portion 20 extends from the inner end wall edge 23 of the end wall 21 of the first portion 19 towards the handle portion 4. The second portion 20 extends perpendicularly relative to the plane of the opening 6 to the cavity 5. Therefore, it will be understood that the second portion 20 of the housing 2 may extend perpendicularly, as shown in Fig. 2, from the first portion 19 of the treatment end 3 to the handle portion 4 or at an acute angle.

The second portion 20 of the treatment end 3 houses the drive shaft 9. The drive shaft 9 is generally cylindrical. The drive shaft 9 has a circular cross-section. The drive shaft 9 extends perpendicularly from the surface of the treatment head 7 in the first portion 19 which is proximate to the end wall 21. The drive shaft 9 is concentric with the treatment head 7. The drive shaft 9 extends from the inner treatment head edge 17 through the second portion 20 into the handle portion 4, shown in Fig. 1, where it connects to the driver 10.

In the present embodiment, the diameter of the drive shaft 9 is less than the diameter of the second portion 20. The diameter of the drive shaft 9 generally corresponds to the size of the inner treatment head edge 17. Therefore, the outer liquid passageway 12 is formed between the second portion 20 of the treatment end 3 and the drive shaft 9. The outer liquid passageway 12 is annular. The outer liquid passageway 12 is configured to be a liquid inlet passageway.

In the present embodiment, the drive shaft 9 is a hollow cylinder. Therefore, the drive shaft 9 comprises the inner liquid passageway 13. The inner liquid passageway 13 is tubular. The inner liquid passageway 13 is configured to be a liquid outlet passageway.

The liquid feed 11 of the bodycare device 1 is configured to provide liquid at the liquid contact surface 8. The outer liquid passageway 12 is configured to be the liquid inlet passageway to allow the liquid feed 11 to provide liquid at the liquid contact surface 8 through the gap 28. The gap 28 is configured to be the liquid inlet to allow the liquid feed 11 to provide liquid to the liquid contact surface 8 of the treatment head 7.

The liquid feed 11 is also configured to draw liquid provided at the liquid contact surface 8 away from the liquid contact surface 8. The inner liquid passageway 13 is configured to be the liquid outlet passageway to allow the liquid feed 11 to draw liquid from the liquid contact surface 8 through the treatment head aperture 15. The treatment head aperture 15 is configured to be the liquid outlet to allow the liquid feed 11 to draw liquid from the mid-section 16 of the treatment head 7.

In the present embodiment, the outer liquid passageway 12, acting as the liquid inlet passageway, is defined between the treatment head 7 and drive shaft 9 and the first and second portions 19, 20 of the treatment end 3. The drive shaft 9 is received in the outer liquid passageway 12. The inner liquid passageway 13, acting as the liquid outlet passageway, is defined in the drive shaft 9. It will be understood that the liquid inlet passageway may be a conduit and may not use the drive shaft 9 as a wall.

The liquid feed 11 further comprises the liquid inlet and the liquid outlet. The gap 28 acts as the liquid inlet which is configured to allow liquid to be provided at the liquid contact surface 8. The treatment head aperture 15 acts as the liquid outlet which is configured to allow liquid to be drawn from the liquid contact surface 8. The liquid flowing into the cavity 5 of the treatment end 3 through the outer liquid passageway 12 is shown by a first arrow A in Figs. 2 and 3. The liquid flowing from the cavity 5 of the treatment end 3 through the inner liquid passageway 13 is shown by a second arrow B in Figs. 2 and 3.

The liquid feed 11 comprises a water source. The water source may be the water mains or, alternatively, a water reservoir (not shown) in the handle portion 4 of the housing 2. The liquid feed 11 may comprise a pump (not shown). The pump is configured to create a liquid flow through the rest of the liquid feed 11. The liquid feed 11 may further comprises a flow controller (not shown) configured to control the amount of liquid provided at and/or drawn from the liquid contact surface 8.

During use the subject holds the bodycare device 1, shown in Fig. 1 and Fig. 2, by the handle portion 4 and places the treatment end 3 against or proximate to the subject's skin. The driver 10 rotates the treatment head 7 at a predetermined speed. The rotational speed may be determined by the subject through the use of a user input (not shown) on the handle portion 4 of the housing 2.

The liquid feed 11 provides liquid at the liquid contact surface 8. The liquid flows along the outer liquid passageway 12 and into the cavity 5 in the treatment end 3 above the treatment head 7. As liquid continues to flow into the cavity 5 the liquid flows over the peripheral edge 14 and onto the subject's skin. When the free end 27 of the peripheral wall 25 is in contact with the subject's skin, no liquid is lost in this process.

The liquid feed 11 continues to provide liquid at the liquid contact surface 8 via the outer liquid passageway 12 until liquid in the cavity 5 is in contact with both the liquid contact surface 8 and the subject's skin. When the cavity 5 is full, the liquid is in contact with both the liquid contact surface 8, which is rotating relative to the housing 2, and the subject's skin, which is stationary relative to the treatment head 7. The liquid forms a buffer between the treatment head 7 and the subject's skin to prevent the liquid contact surface 8 from touching the subject's skin and injuring them.

The rotation of the liquid contact surface 8 of the treatment head 7 causes the liquid in the treatment zone 18 to rotate within the housing 2, as shown by a third arrow C in Fig. 3. Friction causes the liquid touching the liquid contact surface 8 to rotate at the same rotational speed as the treatment head 7 because it opposes relative motion between the two. At the boundary between the liquid in the treatment zone 18 and the subject's skin the liquid has a velocity of zero due to friction. Therefore, liquid particles at the liquid contact surface 8 rotate with the highest rotational speed, which is equal to the rotational speed provided to the treatment head 7 by the driver 10, and the liquid particles at the subject's skin rotate with the lowest rotational speed, zero.

A shear flow is induced in the liquid in the treatment zone 18 of the cavity 5 in which the rotating liquid contact surface 8 urges the flow to increase its rotational speed and the subject's skin urges the flow to decrease its rotational speed. Therefore, liquid layers in between the liquid contact surface 8 and subject's skin rotate at different rotational speeds. This creates a velocity gradient in the liquid in the treatment zone 18 in a direction perpendicular to the liquid contact surface 8, the longitudinal direction as shown by a first set of arrows E in Fig. 4. The closer the liquid layer is to the liquid contact surface 8 the faster its rotational speed.

As the subject positions the treatment end 3 of the bodycare device 1 closer to the subject's skin, the distance between the liquid contact surface 8 and the subject's skin decreases. The decrease in the distance between the liquid contact surface 8 and the subject's skin will cause an increase in the shear force, the force of the liquid resisting rotation imparted to it by the treatment head 7.

Therefore, as the shear force increases the rotational speed of the treatment head 7 will automatically decrease. In this way, by using a sensor (not shown) to detect the rotational speed of the treatment head 7, the distance between the treatment head 7 and the subject's skin will be known and the controller (not shown) can be programmed to increase the rotational speed treatment head 7 by controlling the output of the driver 10 in order to maintain the level of performance and/or have a cut-off speed, or force, to prevent the rotating treatment head 7 contacting the subject's skin.

Alternatively, the sensor (not shown) may be used to optically and/or acoustically detect the distance between the liquid contact surface 8 and the subject's skin or may detect the distance by measuring the pressure variation of the liquid.

The induced shear flow in the liquid creates a velocity differential in the flow of the liquid over detritus on the subject's skin. The velocity gradient, with liquid velocity increasing as the distance from the subject's skin is increased, results in liquid which flows over the top of detritus moving faster than liquid flowing around and/or below it.

As the liquid is moving faster over the upper surface of any detritus on the subject's skin than around and/or below it, a region of low pressure is created above the detritus relative to an area of higher pressure below it. The resultant force is a lift force which is able to remove detritus from the subject's skin. As the liquid flows around detritus drag causes it to be moved along with the liquid flow.

Whilst the primary circular shear flow, shown by the third arrow C in Fig. 3, induced by the rotating treatment head 7 causes detritus to be removed from the subject's skin proximate to the liquid contact surface 8 a secondary flow pattern also arises in the liquid within the treatment zone 18 of the cavity 5, as shown by a fourth arrow D in Fig. 3. This secondary flow is referred to as Batchelor flow.

Batchelor flow arises from friction between the liquid rotating in the cavity 5, the inner face 26 of the peripheral wall 25 of the first portion 19 of the treatment end 3 of the housing 2, and the subject's skin. The velocity gradient in the direction perpendicular to the liquid contact surface 8 has been explained in detail above. However, a second velocity gradient is present in the rotating liquid in the treatment zone 18; an angular velocity gradient in the radial direction, as shown by a second set of arrows F in Fig. 4.

The angular velocity gradient is a result of friction between the liquid particles which contact the inner face 26 of the peripheral wall 25 in a liquid layer. Therefore, the rotational speed of the liquid increases as the distance from the inner face 26 of the peripheral wall 25 increases. This increase in rotational speed is accompanied with a decrease in static pressure which results in a pressure gradient in the radial direction. The pressure is highest in the liquid proximate the peripheral wall 25 and lowest in the liquid flowing proximate the axis of rotation in, the centre of, the cavity 5.

At the top of the flow, proximate the liquid contact surface 8, the rotation of the treatment head 7 provides a net centrifugal force on the liquid which causes an outwardly spiralling flow towards the peripheral wall 25. This centrifugal force is balanced by a centripetal force from the peripheral wall 25 which prevents the liquid escaping.

Further down the inner face 26 of the peripheral wall 25 the liquid flow shears, as explained above, and the velocity of the liquid decreases. This in turn further increases the pressure of the liquid at this point. Therefore, the pressure gradient in the radial direction is compounded by the pressure gradient in the direction perpendicular to the liquid contact surface 8. This results in the highest pressure in the liquid occurring near the periphery of the flow proximate the subject's skin.

At this point, the pressure gradient, which provides the centripetal force, overcomes the centrifugal force provided to the liquid by the rotating treatment head 7.

Therefore, an inward spiralling flow occurs proximate the subject's skin. The velocity gradient of the inward velocity of the liquid in the direction perpendicular to the liquid contact surface 8, the longitudinal direction, is shown by a third set of arrows G in Fig. 4. This inwardly spiralling flow across the subject's skin allows the liquid flow to transfer detritus removed from the subject's skin towards the central axis of the cavity 5 to a collation area 29. Detritus will collect in the collation area 29 in the event that the liquid flow is not strong enough to carry detritus towards the liquid contact surface 8.

The liquid in the column above the subject's skin at the centre of the cavity 5 is moving fastest towards the top, proximate the liquid contact surface 8, and so has a lower pressure than the liquid below it. Therefore, the high pressure liquid at the bottom can flow spiral upwards towards the liquid contact surface 8 where the centrifugal force begins to urge it towards the peripheral wall 25 once again.

Therefore, the lighter detritus can be carried by the liquid flow from the subject's skin upwards towards the liquid contact surface 8. When the liquid reaches the liquid contact surface 8 it is proximate the treatment head aperture 15. The liquid feed 11 draws the liquid carrying detritus from the liquid contact surface 8 through the treatment head aperture 15, along the inner liquid passageway 13, and out of the cavity 5.

The bodycare device 1 can be drawn across the subject's skin to treat a different area. Alternatively, the bodycare device 1 can be removed from the subject's skin and the process can begin again when the bodycare device 1 is repositioned on another area of the subject's skin.

The helical flow pattern established in liquid in the cavity 5 comprises a primary circular flow A in the same direction as the rotation of the treatment head 7 and a secondary circular flow B in the longitudinal direction, perpendicular to the rotation of the treatment head 7, as shown in Fig. 3.

Therefore, as the Batchelor flow prevents liquid from leaking through the space between the treatment end 3 and the subject's skin and provides a re-circulation of the liquid within the treatment zone 18 it is possible, in one embodiment, to operate the bodycare device 1 without the liquid feed 11 constantly supplying liquid to and/or drawing liquid from the liquid contact surface 8 in the cavity 5. That is, the flow controller (not shown) may be used to control the flow of liquid at and/or from the liquid contact surface 8 reducing the amount of liquid required by the bodycare device 1 to effectively treat the subject's skin. The flow controller may be automatic or controlled by the subject.

In an alternative embodiment, it will be understood that the diameter of the second portion 20 of the treatment end 3 of the bodycare device 1 may be equal to the diameter of the first portion 19. Therefore, the appearance of the treatment end 3 of the bodycare device 1 is enhanced. The diameter of the first and second portions 19, 20 of the treatment end 3 may also correspond to the diameter of the housing 2 of the bodycare device 1 which enhances its overall appearance. Furthermore, the outer liquid passageway 12 may be located away from the rotating drive shaft 9.

In another alternative embodiment, the treatment head 7 may be pivotably connected to the drive shaft 9. Therefore, the treatment head 7 may pivot relative to the drive shaft 9 and the liquid contact surface 8 of the treatment head 7 may extend at an acute angle relative to the longitudinal axis of the drive shaft 9. This enables the treatment head 7 to pivot so that the liquid contact surface 8 is always substantially parallel to the user's skin. The treatment head 7 may be pivoted by the pressure differences present in the liquid acting on the liquid contact surface 8, manually by the user, or automatically controlled by a sensor (not shown).

In an embodiment comprising the water reservoir (not shown) in the handle portion 4 of the bodycare device 1, the outer and inner liquid passageways 12, 13 may fluidly connect the liquid contact surface 8 to the water reservoir so that the liquid can be recirculated in the bodycare device 1 to further reduce the amount of liquid required for the bodycare device 1 to provide effective cleaning. Furthermore, the water reservoir may comprise a filter (not shown) configured to remove detritus from the liquid so that clean liquid is supplied to the cavity 5 to act on the subject's skin at all times.

In another embodiment of the bodycare device 1 , it will be understood that the peripheral wall 25 may extend at an acute angle relative to the end wall 21. Furthermore, it will be understood that the distance the peripheral wall 25 extends from the end wall 21 may vary around the circumference such that the plane of the opening 6 extends at an acute angle relative to the end wall 21.

Furthermore, in an alternative embodiment of the bodycare device 1 it will be appreciated that the treatment head aperture 15 may be located in an alternative position in the treatment head 7. For example, the treatment head aperture 15 may be located at a point in the mid-section 16 that is not the origin of the circular liquid contact surface 8. There may be more than one treatment head aperture 15. The treatment head apertures 15 may be arranged such that the cross-section of the treatment head 7 is symmetrical.

It will also be understood that the liquid contact surface 8 may be modified to help control and manipulate the flow created in the liquid. For example, the liquid contact surface 8 may comprise a rough surface to increase the frictional force between the liquid contact surface 8 and the liquid which induces a greater shear force in the liquid flow. In an alternative embodiment, the treatment head 7 may comprise at least one protrusion (not shown). The protrusion may extend from the liquid contact surface 8. The protrusion may help to encourage the liquid to flow in the helical flow pattern by increasing the surface area of the liquid contact surface 8 and therefore, the drag force. The distance which the protrusion extends from the liquid contact surface 8 may be less than or equal to half (1/2) the distance between the liquid contact surface 8 and the subject's skin when the bodycare device 1 is in use.

The width of the protrusion (not shown) may be less than or equal to 1000 μιη. The width of the protrusion may be greater than or equal to 100 μιη. The protrusion may have a triangular cross-section. The triangular cross-section may be a right angled triangle with its hypotenuse facing in the direction of rotation. However, it will be understood that the protrusion may have alternative cross-sections, such as, but not limited to, semi-circular and rectangular.

In an alternative embodiment, the treatment head 7 may comprise multiple protrusions (not shown) arranged in a rotationally symmetrical configuration. The spacing between adjacent protrusions may be proportional to the width of the protrusions.

Although in the embodiment described above the gap 28 and outer liquid passageway 12 have been described as part of the liquid inlet passageway, it will be understood that the direction of flow may be reversed and that the gap 28 may act as a liquid outlet and the outer liquid passageway 12 may act as a liquid outlet passageway. In the same way, the treatment head aperture 15 and inner liquid passageway 13 have been described as part of the liquid outlet passageway. However, the liquid flow direction may be reversed and the treatment head aperture 15 may act as a liquid inlet and the inner liquid passageway 13 may act as a liquid inlet passageway.

It will be understood that in one embodiment of the bodycare device 1 the liquid feed 11 may not be configured to remove liquid from the liquid contact surface 8 via a liquid conduit. In another embodiment, the inner liquid passageway 13 may be omitted and the gap 28 and outer liquid passageway 12 may divided in two to act as both the liquid supply passageway and the liquid removal passageway.

Hence, the treatment end 3, especially the first portion 19 comprises a liquid outlet, such as in an embodiment the treatment head aperture, and a liquid inlet, such as in an embodiment the gap 28 between the peripheral edge 14 and the inner face 26 )of the peripheral wall around the circumference of the treatment head). The term "inlet" or "outlet" may each independently also refer to a plurality of "inlets" and "outlets", respectively. The treatment head may at least partly reside in the cavity. Further, the treatment head is at least partly comprised by the housing.

In another embodiment, a sensor (not shown) may detect the distance between the subject's skin and the liquid contact surface 8 of the treatment head 7. The sensor is able to match the distance between the subject's skin and the liquid contact surface 8 to the rotational speed of the treatment head 7.

The rotational speed of the treatment head 7 may be inversely proportional to the distance between the liquid contact surface 8 and the subject's skin. This enables the treatment head 7 of the bodycare device 1 to provide a constant performance over a range of distances from the subject's skin. Alternatively, the sensor (not shown) may operate, as a safety feature, over a small range near the subject's skin to prevent the treatment head 7 from rotating when the liquid contact surface 8 gets too close to or touches the skin.

It will be understood that the liquid used the bodycare device 1 may be, for example, but not limited to, water. Furthermore, it will be understood that the liquid may be water mixed with a treatment product for cleansing or treating the skin. The liquid and treatment product may be prepared before hand and the liquid feed 11 may provide the mixture to liquid contact surface 8.

Alternatively, the bodycare device 1 may comprise a treatment product reservoir (not shown) and may mix the liquid and treatment product in the bodycare device 1 before the mixture is provided at the liquid contact surface 8 by the liquid feed 11.

In one embodiment, the bodycare device 1 injects treatment particles and/or micro-bubbles into the liquid to aid and improve the treatment of the subject's skin.

Although in the above described embodiments the treatment head 7 is rotatable relative to the treatment end 3 of the housing 2, it will be understood that in another embodiment the treatment end 3 may be rotatably mounted to the handle portion 4. In such an embodiment the treatment end 3 of the housing 2 is rotatable about its longitudinal axis with the treatment head 7. That is, the driver 10 is configured to rotate the treatment end 3 of the housing 2 together with the treatment head 7.

Although in the above described embodiments the driver 10 is configured to impart a rotational motion on the treatment head 7, it will be understood that alternative motions may be imparted on the treatment head 7 to generate a shear flow in liquid at the liquid contact surface 8 of the treatment head 7. For example, in one embodiment the treatment head 7 may be a belt (not shown) extended over two rotating shafts which extend parallel to the plane of the opening 6. The belt rotates over the shafts in one direction causing a linear shear flow between the belt and the subject's skin.

It will be appreciated that the term "comprising" does not exclude other elements or steps and that the indefinite article "a" or "an" does not exclude a plurality. A single processor may fulfil the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to an advantage. Any reference signs in the claims should not be construed as limiting the scope of the claims.

Although claims have been formulated in this application to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel features or any novel combinations of features disclosed herein either explicitly or implicitly or any generalisation thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the parent invention. The applicants hereby give notice that new claims may be formulated to such features and/or combinations of features during the prosecution of the present application or of any further application derived therefrom.