Patent Application
20190209239
The invention relates to a cutting element for use with a hair cutting device for cutting (e.g. shaving) hair on a body of a subject, and a hair cutting device comprising the same.
A type of shaving device has been proposed in WO 2014/143670 that makes use of laser light. In particular, a laser light source is provided that is configured to generate laser light having a wavelength selected to target a predetermined chromophore to effectively cut a hair shaft. A fibre optic is located on a shaving portion of the device that is positioned to receive the laser light from the laser light source at a proximal end, conduct the laser light from the proximal end toward a distal end, and emit the light out of a cutting region of the fibre optic and toward hair when the cutting region is brought in contact with the hair.
An alternative type of laser shaving device has been proposed in US 2015/359592. The laser shaving device according to this document utilizes a laser beam in open air which is directed substantially parallel to the skin of the user. Hairs passing through the laser beam are cut via a melting process. In order to prevent the laser light to enter into the skin a spacer or distancing element is used to space the skin away from the laser beam travelling in open air.
To achieve a clean cut through a hair, the cutting element of the shaving device (i.e. the fibre optic in the case of the device in WO 2014/143670) needs to be brought very close to, or into contact with, a hair to be cut at a particular position for sufficient time. Since both the fibre optic of the cutting element and the hair to be cut are generally cylindrical in shape, there exists a tendency for the hair to slide across the surface of the cutting element, which can cause the cutting location of the hair to move, result in an inadequate cut.
In order to improve the quality of a cut through a hair and, hence, to improve the cutting ability of the shaving device, the position of the cutting element relative to the hair to be cut should ideally not move while hair is being cut.
Therefore, there is a need for an improved cutting element and hair cutting device that have an improved cutting quality.
According to a first aspect, there is provided a cutting element for use in a hair cutting device, the cutting element comprising an optical waveguide having a sidewall, wherein a portion of the sidewall forms a cutting face for contacting hair; and a hair support structure configured to restrict lateral movement of a hair in contact with the cutting face, relative to the optical waveguide. By restricting lateral movement of the hair relative to the cutting element, the hair may be more cleanly cut, as light coupling out from the cutting face of the optical waveguide will couple into the hair at the same position throughout the cutting process. Consequently, the cutting process may be completed more quickly, which may in turn result in an improved hair cutting or shaving experience for the user.
The hair support structure comprises a plurality of movement restrictors extending from the cutting face. Each movement restrictor may be shaped substantially in a shape selected from a group comprising: conical, cubic, cylindrical, teardrop-shaped and bulbous. Movement restrictors of particular shapes may be advantageous for restricting the movement of hair of particular types and sizes. Bulbous movement restrictors may capture or trap hairs to restrict movement of the hairs during cutting.
Each movement restrictor comprises a ridge protruding from the cutting face of the optical waveguide, the ridges being arranged substantially parallel to one another. Each ridge may comprise a structure shaped substantially in a shape selected from group comprising: a cuboid, a triangular prism and a half cylinder.
A separation between adjacent movement restrictors may be between around 20 micrometres and 500 micrometres. In some embodiments, the separation between adjacent movement restrictors may be between around 50 micrometres and 400 micrometres. The separation may be selected based on the thickness (i.e. diameter) and/or type of hair to be cut.
In use, the hair support structure may be arranged to engage skin of the user from which extends the hair to be cut. Thus, in addition to restricting movement of hairs relative to the optical waveguide, the movement restrictors serve to manipulate skin from which the hairs are growing. In particular, the movement restrictors may push down on the skin surrounding the hairs, thereby revealing more of each strand of hair so that a closer shave can be achieved.
In some embodiments, the hair support structure may be coupled to the optical waveguide using adhesive. In other embodiments, the hair support structure may be configured to be connected to the optical waveguide by an attachment assembly. The hair support structure may be removably connectable to the cutting element, such that it can be replaced, for example when a different support structure is needed, or when the hair support structure is damaged and needs to be disposed of.
The optical waveguide may, in some embodiments, comprise an optical fibre.
According to a second aspect, there is provided a hair support structure for use with a cutting element, the cutting element comprising an optical waveguide having a sidewall, wherein a portion of the sidewall forms a cutting face for contacting hair, the hair support structure comprising a plurality of movement restrictors which movement restrictors comprise a ridge protruding from the cutting face of the optical waveguide. These ridges are arranged substantially parallel to one another such that the hair support structure is configured to restrict lateral movement of a hair in contact with the cutting face, relative to the optical waveguide.
In some embodiments, the hair support structure may comprise an attachment assembly for removably attaching the hair support structure to a cutting element or to a hair cutting device including a cutting element. The attachment assembly may comprise a clip for clipping the hair support structure onto a cutting element or a hair cutting device. Thus, the hair support structure may be removable from the cutting element, and replaced with a different hair support structure. In some embodiments, the cutting element and the hair support structure may be formed as a single unit which may be removable from a hair cutting device.
According to a third aspect, there is provided a hair cutting device for cutting hair on a body of a subject, the hair cutting device comprising a light source for generating laser light at one or more specific wavelengths corresponding to wavelengths absorbed by one or more chromophores in hair; and a cutting element coupled to the light source to receive laser light. The cutting element may comprise a cutting element as described above.
In some embodiments, the hair support structure may be removably attachable to the cutting element.
Other advantageous features will become apparent from the following description.
For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:
As noted above, the present invention provides an improvement in the cutting ability and quality of a laser light-based shaving device, for example as described in WO 2014/143670. In particular, it has been recognised that by restricting the relative movement of a hair and the cutting element during cutting, the hair can be cut more cleanly and effectively, reducing the need for a user of the shaving device to repeatedly use the shaving device over the same area of his or her skin and, consequently, reducing the risk of pain or irritation of the skin.
It will be appreciated that the invention is applicable to shaving devices (e.g. razors or electric shavers), and any other type of device that is used to cut hair (e.g. hair clippers), even if those devices do not necessary aim to provide a ‘clean shave’ (i.e. to remove hair at the level of the skin).
The hair cutting device 2 comprises a cutting element 4 that enables hair to be cut as the hair cutting device 2 is moved over the skin of a subject. The cutting element 4 is an optical waveguide 4 that is arranged on the hair cutting device 2 so that the optical axis of the optical waveguide 4 (i.e. the line along which light typically propagates through the optical waveguide 4) is generally perpendicular to the direction in which the hair cutting device 2 is moved so that hairs contact the sidewall of the optical waveguide 4 (the sidewall corresponding to the long edge of the optical waveguide 4) as the hair cutting device 2 is moved across the skin of the subject. In some embodiments, the optical waveguide 4 is an optical fibre, although those skilled in the art will be aware of other types of optical waveguide that can be used according to the invention, such as a slab waveguide, a strip waveguide or a photonic crystal waveguide. An optical fibre comprises a core, and in some embodiments also comprises a cladding, which may or may not fully encompass the core (e.g. part of the core may be exposed).
A light source 6 is provided in the hair cutting device 2 that generates laser light at one or more specific wavelengths. The light source 6 is optically coupled to the optical waveguide 4 so that the laser light generated by the light source 6 is coupled into the optical waveguide 4 (and specifically coupled into an end of the optical waveguide 4 so that the laser light propagates through the optical waveguide 4).
The light source 6 is configured to generate laser light at one or more specific wavelengths that can be used to cut or burn through hair. In particular, each wavelength corresponds to the wavelength of light absorbed by a chromophore that is found in hair. As is known, a chromophore is the part of a molecule that provides the molecule with its colour. Thus, the laser light will be absorbed by the chromophore and converted into heat which will melt or burn the hair or otherwise destroy the bonds in the molecules of the hair, and it is this melting or burning that provides the cutting action of the hair cutting device 2.
Suitable chromophores that can be targeted by the laser light generated by the light source 6 include, but are not limited to, melanin, keratin and water. Suitable wavelengths of laser light that can be used include, but are not limited to, wavelengths selected from the range 380 nm (nanometres) to 500 nm and 2500 nm to 3500 nm. Those skilled in the art will be aware of the wavelengths of light that are absorbed by these chromophores, and thus also the specific wavelengths of light that the light source 6 should generate for this purpose, and further details are not provided herein.
In some embodiments the light source 6 can be configured to generate laser light at a plurality of wavelengths (either simultaneously or sequentially), with each wavelength being selected to target a different type of chromophore. This can improve the cutting action of the optical waveguide 4 since multiple types of molecules in the hair may be burnt using the laser light. Alternatively, multiple light sources 6 can be provided that each generate laser light at a respective wavelength, and each light source 6 can be coupled to a respective optical waveguide 4 to provide multiple cutting elements 4 in the device 2.
The hair cutting device 2 also comprises a control unit 8 that controls the operation of the hair cutting device 2, and in particular is connected to the light source 6 to control the activation and deactivation of the light source 6 (and in some embodiments control the wavelength and/or intensity of the light generated by the light source 6). The control unit 8 may activate and deactivate the light source 6 in response to an input from a user of the hair cutting device 2. The control unit 8 can comprise one or more processors, processing units, multi-core processors or modules that are configured or programmed to control the hair cutting device 2.
As noted above,
The graph in
As is known, the optical waveguide 4 acts as a waveguide for the light coupled from the light source 6 through the occurrence of total internal reflection, since the refractive index of air is lower than that of the optical waveguide 4. However, if an object that has a refractive index higher than the optical waveguide 4 is put into contact with the optical waveguide 4, then the total internal reflection is ‘frustrated’ and light can couple from the optical waveguide 4 into that object. Thus, in order for light to be coupled into a hair from the optical waveguide 4 (to provide the cutting action according to the invention), the optical waveguide 4 should preferably have the same or a lower refractive index than hair at the point at which the hair contacts the optical waveguide 4. Thus, the optical waveguide 4 should preferably have the same or a lower refractive index than hair at least at the cutting face 14 portion of the optical waveguide 4. Preferably the refractive index of the optical waveguide 4 at the cutting face 14 is the same as that of hair since that provides the best coupling of light from the optical waveguide 4 to the hair. Light may still be able to couple from the optical waveguide 4 into an object (e.g. a hair) brought into contact with the cutting face 14 of the optical waveguide even if the refractive index of the optical waveguide is higher than that of the object, due to a high numerical aperture in the cutting face.
Thus, in some embodiments, the refractive index of the optical waveguide 4 at least at the cutting face 14 is equal to or lower than 1.56. More preferably the refractive index of the optical waveguide 4 at least at the cutting face 14 is equal to or lower than 1.55. Even more preferably, the refractive index of the optical waveguide 14 at least at the cutting face 14 is equal to or lower than 1.54, since this refractive index is below the refractive indices identified in
In some embodiments, a lower bound for the refractive index of the optical waveguide 4 at the cutting face 14 can be 1.48, 1.51, 1.53 or 1.54.
A range of values from which the refractive index of the optical waveguide 4 is selected can be formed from any combination of the upper and lower refractive index bounds set out in the preceding paragraphs.
The optical waveguide/fibre 4 can be made from any suitable material or combination of materials. For example optical waveguides/fibres can be composed of or comprise silica, fluoride glass, phosphate glass, chalcogenide glass, crown glass (such as BK7) and/or crystals (such as yttrium aluminium garnet (YAG) or sapphire).
As noted above, the optical waveguide/fibre 4 and strands of hair to be cut by the cutting device are generally cylindrical in shape, and the optical waveguide and a strand of hair are typically oriented such that they are approximately perpendicular to one another when cutting is taking place. Therefore, when the optical waveguide 4 and the strand of hair come into contact with one another, there is a chance that the hair will move along the surface of the optical waveguide such that the position at which the hair is being cut by the optical waveguide changes during the cutting procedure. Therefore, it has been recognised that supporting hair to restrict its movement relative to the cutting element during cutting helps to achieve a cleaner and more effective cut.
In
In each of the embodiments shown in
The core 16 may have a uniform refractive index (i.e. the same refractive index throughout the core 16), or it may be a graded index fibre, which means that the refractive index decreases with increasing distance from the optical axis.
In each of
The cutting element 4 shown in the embodiment of
It will be appreciated that the movement restrictors may have shapes other that those discussed above. The movement restrictors may be positioned on the cutting face 14 of the cutting element 4 in a spaced apart configuration, with the spacing between adjacent restrictors chosen, in some examples, based on the size (e.g. diameter) of the hair to be cut. For example, in some embodiments, the movement restrictors may be separated by a distance slightly exceeding the diameter of an average hair. In this way, a hair is likely to fit into the space between adjacent restrictors, but further lateral movement with respect to the cutting element 4 is restricted, or prevent altogether.
In some embodiments, the hair support structure 22 may comprise structures which function in a similar manner to the movement restrictors discussed above, but which are formed as ridges extending from the cutting face.
In the embodiment of
The movement restrictors and/or the ridges of any of the hair support structures described herein may be formed from a material suitable for contacting the skin of a user in a shaving environment. For example, a material may be chosen which is easy to clean, which moves over skin easily with a relatively low amount of friction, which is non-allergenic, which non-corrosive and/or which is suitable for use in a wet environment. In some embodiments the hair support structure 22 may be formed at least in part from metal, such as stainless steel, from a plastics material or from a polymer.
As noted above, it may be advantageous for the movement restrictors and the ridges of the hair support structure 22 to be formed from a material which is enables ends of the movement restrictors to be temporarily laterally displaced when moved into contact with an object. However it may also be advantageous for the hair support structure 22 to be formed from a material strong enough such that in use, the movement restrictors apply pressure onto a user's skin, so as to manipulate the skin from which the hairs to be cut are growing. In this way, the hair support structure 22 may push hairs out the skin to cause an improved closeness in the shaving or hair cutting activity.
The arrangements shown in
The hair support structure 22 may be coupled to the cutting element 4, for example using adhesive. In some embodiments, the hair support structure 22 may be attached to the cutting face 14, while in other embodiments, the structure 22 may be attached to another part of the cutting element 4, remote from the cutting face. By attaching the hair support structure 22 to the cutting element 4, rather than forming the structure 22 as part of the optical waveguide, the cutting face remains intact, such that light propagating through the optical waveguide is able to couple out from the cutting face in a consistent and predictable manner. Changing the structure of the cutting face 14 itself may affect the coupling of light from the coupling element 4 into a hair 18.
In some embodiments, the hair support structure 22 may be removably attachable to the cutting element 4 or to the hair cutting device 2.
In some embodiments, the cutting face 14 comprises a surface of the cutting element 4, such as, for example, an outer surface of a cladding of an optical fibre. In some embodiments, a portion of the cladding of the optical fibre is removed, such that the cutting face 14 comprises a surface of the core of the optical fibre 4. In either of these scenarios, the cutting face is uninterrupted, with no intended recesses, indentations or protrusions, other than the hair support structure 22 coupled thereto.
Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor or other unit 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 advantage.
Any reference signs in the claims should not be construed as limiting the scope.
| Number | Date | Country | Kind |
|---|---|---|---|
| 16184989.8 | Aug 2016 | EP | regional |
| 16202470.7 | Dec 2016 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2017/070907 | 8/18/2017 | WO | 00 |
