KITCHEN APPLIANCE, DECORATIVE ARTICLE THEREFOR, AND METHOD OF MANUFACTURING A DECORATIVE SURFACE

Abstract

There is provided a method of manufacturing a decorative surface, comprising the steps of: coating a substrate with an opaque coating using a vapour deposition process; and etching the coating to expose the substrate selectively thereby to manufacture a decorative surface.

Claims

1. A method of manufacturing a decorative surface, comprising: coating a substrate with an opaque coating using a vapour deposition process; and etching the coating to expose the substrate selectively thereby to manufacture a decorative surface.

2. The method according to claim 1, wherein the decorative surface comprises a pattern that allows light to be transmitted therethrough.

3. The method according to claim 1, wherein the coating is metallic, preferably wherein the coating comprises aluminium; more preferably wherein the coating is an elemental coating.

4. The method according to claim 1, wherein the coating has a thickness of at most 0.5 μm, preferably wherein the thickness of the coating is between 0.3 μm and 0.5 μm.

5. The method according to claim 1, wherein the coating is reflective, preferably wherein the coating has a reflectance of at least 80%, more preferably at least 90%, for light at a wavelength within the range 300 to 700 nm; yet more preferably wherein the coating is mirror-like.

6. The method according to claim 1, wherein the coating has at least one of the following properties: a Vickers hardness of 600 MPa or less, preferably between 160 and 350 MPa; and a density of 2.7 g/cm.sup.3 or less.

7. The method according to claim 1, wherein etching comprises using a laser; preferably wherein etching comprises using a laser having at least one of the following properties: a power output at peak of at least 50 watts, more preferably at least 75 watts; being capable of emitting light having a wavelength for which the substrate is substantially transparent, more preferably wherein the wavelength is 10 μm or lower, still more preferably wherein the wavelength is approximately 1.06 μm; and being a CO.sub.2 laser.

8. (canceled)

9. The method according to claim 1, wherein the vapour deposition process is a physical vapour deposition process.

10. The method according to claim 1, wherein the decorative surface consists of food safe materials, preferably wherein said materials are physically and chemically stable at least at temperatures between 0 degrees and 100 degrees Celsius.

11. The method according to claim 1, further comprising at least one of the steps(s) of: applying a lacquer to the coating prior to etching; and applying a protective coating to the decorative surface following etching, preferably wherein the protective coating is UV-resistant.

12. The method according to claim 1, further comprising the step(s) of applying a base coating to the substrate prior to coating with an opaque coating; optionally cleaning the substrate, preferably ultrasonically, prior to applying a base layer; and optionally cleaning the base coating, preferably electrostatically, prior to coating with an opaque coating.

13. The method according to claim 1, wherein the substrate is a light transmissive substrate; optionally wherein the method further comprises the step of applying a tint to at least part of the light transmissive substrate.

14. The method according to claim 1, wherein the substrate comprises an electrically insulating material, preferably a polymer material, more preferably wherein the method further comprises moulding a polymer to form the substrate, yet more preferably wherein said moulding is injection moulding, even more preferably wherein the polymer is a polycarbonate polymer.

15. The method according to claim 1, wherein the decorative surface is formed directly on a decorative article; preferably wherein the decorative article is a three-dimensional object.

16. (canceled)

17. A decorative article comprising: a substrate; and an opaque coating, applied to the substrate via a vapour deposition process; wherein the coating exposes, preferably by etching, the substrate selectively, thereby preferably to form a decorative pattern.

18. The decorative article according to claim 17, wherein the decorative article is suitable for handling by a user; and/or wherein the decorative article is suitable for use as at least part of a housing for a kitchen appliance; and/or wherein the decorative article is a component for a kitchen appliance.

19-20. (canceled)

21. The decorative article according to claim 17, wherein the coating comprises a pattern that allows light to be transmitted therethrough, the pattern preferably being formed by the selective etching of the coating; preferably wherein the decorative article comprises at least one edge and wherein the pattern is located away from said at least one edge.

22. (canceled)

23. The decorative article according to claim 21, wherein the decorative article is capable of being illuminated by a light source; preferably wherein the decorative article further comprises a light source arranged such that light from the light source is visible via the pattern; more preferably wherein the light source is enclosed within the decorative article such that light from the light source is visible only via the pattern; still more preferably wherein the light source is configurable to convey information related to the condition of the kitchen appliance; preferably wherein the pattern is provided on a part of the decorative article which is configured to face towards a user in normal use; more preferably wherein the decorative surface is a circular face of the decorative article; still more preferably wherein the pattern is generally annular.

24. (canceled)

25. The decorative article according to claim 17, wherein the decorative article is a control knob; preferably wherein the knob comprises a protective collar.

26. A kitchen appliance comprising: a decorative article according to claim 17; preferably wherein the kitchen appliance further comprises a housing; more preferably wherein the opaque coating of the decorative article and at least an outer part of the housing of the kitchen appliance are formed of materials which are substantially similar in appearance; preferably wherein said materials are the same.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0055] One or more aspects will now be described, by way of example only and with reference to the accompanying drawings having like-reference numerals, in which:

[0056] FIG. 1 is an exploded perspective view of a prior-art knob;

[0057] FIG. 2 is a flow-chart showing a method of manufacture according to an embodiment of the invention;

[0058] FIG. 3a is a schematic drawing in plan showing a knob according to an embodiment of the invention;

[0059] FIG. 3b is a schematic, side-on drawing of the knob of FIG. 3a;

[0060] FIG. 3c is a schematic, perspective drawing of the knob of FIG. 3a; and,

[0061] FIG. 4 is a schematic, frontal view of a food processing appliance including the knob of FIG. 3a.

DETAILED DESCRIPTION OF THE FIGURES

[0062] A flow chart of a method of manufacture for a single-piece control knob including a decorative surface, generally labelled 100, is shown in FIG. 2. The method includes coating a substrate via a vapour deposition process, and etching the coating to expose the substrate selectively.

[0063] In more detail, a substrate is firstly obtained using a transparent or translucent material in a moulding step 110. The moulding step 110 may be, for example, an injection moulding step. The substrate is then ultrasonically cleaned in an ultrasonic cleaning step 120 to remove dirt. A base coat 130 is then applied to enhance the adhesion of further coatings.

[0064] This transparent material used in step 110 may be a plastic material such as polycarbonate, which is desirable as it easy to mould and food-safe. Alternatively the material may be a material such as glass or another relatively transparent, light-transmissive material compared to the coating, and step 110 may comprise another way of obtaining the substrate other than moulding (e.g., casting, forming, machining, or carving).

[0065] An optional further cleaning step is then performed at step 140, comprising performing electrostatic cleaning to remove microscale impurities such as dust.

[0066] The substrate is then plated (i.e. coated) on the outer surface using a PVD (Physical Vapour Deposition) process 150 in order to apply a thin film metallic coating. As the substrate is non-conductive, this process may be referred to as a non-conductive vacuum metallisation (NCVM) step. To protect the coating applied in the PVD process 150, a mid-stage lacquer is applied at step 160.

[0067] The PVD process 150 may be advantageous as the resulting shiny finish layer can be very thin compared to that achieved through electro-deposition on a non-conductive substrate, as there is no need to apply a conductive layer first. PVD 150 also results in a thinner, more even and consistent coating than that achievable through e.g., spraying or painting. Other forms of vapour deposition may be used, such as, for example, chemical vapour deposition (CVD); however PVD is preferred as it avoids the need for e.g., chemical reactions to occur in the forming of the coating, meaning that an elemental (i.e., single element) coating can be achieved. Elemental coatings are desirable as they are typically more chemically stable. Lower substrate temperatures can also be advantageously used in PVD processes compared to those required for CVD processes.

[0068] As the coating achieved using the PVD process 150 is relatively thin (less than 1 μm, and preferably less than 0.5 μm, and more preferably still 0.3-5 μm) it can be etched safely by a laser. An aluminium coating may be used as the coating in this step, as it ensures that a shiny finish is achieved, and further enables lasing as it is a much softer substance compared to conventional coatings. The coating preferably has a hardness of less than around ˜600 MPa Vickers, and more preferably still in the range 160-350 MPa Vickers. Aluminium is also much less dense than conventional coatings, making it easier to lase. Aluminium also has a lower melting, boiling point and heat of vaporisation than conventional coatings using a coating substance having such thermal characteristics may therefore be advantageous.

[0069] To ensure that the coating used in the PVD process 150 is sufficiently shiny, the coating material should have a reflectance of 80% or more, and more preferably 90% or more, of light in the visible spectrum (e.g., at a wavelength in the range 300-700 nm). More preferably, at least 80% of light at all wavelengths across the visible spectrum is reflected. Aluminium is an example of a suitable material which has this property. To ensure a mirror-like finish at least the majority of reflection should be so-called specular reflection (i.e., “mirror-like” reflection along an appropriate reflected angle rather than diffusion at many different angles).

[0070] Whilst aluminium coating is used here in the PVD process 150, another coating of a similar maximum thickness and/or hardness and/or density, such that it may be easily lased, may also be used. Whilst a shiny coating is desirable, another visible-light-opaque coating may be used depending on the circumstances, though shiny coatings are particularly desirable in kitchen appliances due to the ease with which dirt may be detected on them.

[0071] Coating on an outer surface of the transparent substrate (i.e., where the substrate is a concave element like the knob of FIG. 3b, on the surface opposite to the direction in which the substrate curves) is desirable as this surface faces the user during use. However, the coating may in an alternative be applied on an inner surface (i.e., for a concave element such as a curved front surface of a knob, the surface towards which the element curves). Coating on the inner surface, however, is less desirable as the user will only see the shiny finish through the transparent substrate, which reduces the effect of making dirt easily identifiable. Alternatively the whole surface of the substrate may be coated, in which case the coating will need to be etched on more than one side to allow light to shine through it.

[0072] To produce a light transmissive portion on the decorative surface for light to shine through (i.e. the clear annular ‘halo’ on a control knob), the plated finish is selectively etched away by laser in the area to be illuminated (i.e. the light transmissive portion) in a lasing step 170. The laser used in this lasing step 170 is preferably a laser of sufficient power to, at peak, evaporate the coating used, with the beam strength and duration selected so as not to damage the underlying substrate. For example, for etching an aluminium coating a CO.sub.2 laser may be used having a peak emission power of more than approximately 50 watts, and more preferably more than approximately 75 watts. The wavelength of the laser should preferably be lower than around 10 μm, for example it may be 1.06 μm, a wavelength particularly suitable for etching metals as it is more readily absorbed by them.

[0073] Using a visible-light laser, or at least a laser for which the substrate is substantially transparent, helps prevent absorption of the laser light by the substrate thus preventing damage during etching. For example, polymers such as polycarbonate are substantially transmissive of light at a wavelength of 1.06 μm.

[0074] While lasing provides a particularly advantageous etching method due to it being non-contact, cheap, easily automated and not involving environmentally-harmful substances, it will be appreciated that other etching methods, for example physical scraping or chemical etching, could instead be used in an alternative.

[0075] Finally, the outer surface of the substrate is UV coated in a UV coating step 180 to add durability to the finish and reduce any transition between the plated and the etched areas. The UV coating 180 protects the substrate and coating from being degraded by UV light and also forms a final protective lacquer helping to prevent e.g., scratching.

[0076] The base coating 130, lacquer 160, and/or UV coating 180 are preferably transparent to visible light including laser light (or at least do not substantially absorb the laser light). As food processing in cooking appliances, particularly those incorporating heating elements, involves heated substances, the coatings and substrate used in the process 100 should preferably be physically stable (i.e. not melt or readily deform) within at least the range 0-100 degrees Celsius. They should also preferably be chemically stable within the 0-100 degrees range, and not react with each other or decompose chemically within this temperature range. Materials used should preferably also be food safe and, for example, not include BPA or other potentially toxic materials.

[0077] The process 100 may generally be implemented in a factory setting, where the substrate is processed on a conveyor line moving past a plurality of stations. All or some of the described steps may be automated—for example, automatic injection moulding of the substrate may take place before the substrate is placed on a conveyor line, the physical vapour deposition 150 may take place automatically via a specially configured chamber, and the laser etching step 170 may be performed by a suitably programmed lasing device, such as a robot arm including a laser. The other cleaning and coating steps may be performed by suitably configured robot arms (or other such devices).

[0078] FIGS. 3a-3c show an exemplary decorative article in the form of a knob 200 including a decorative surface achieved through the process 100.

[0079] The knob 200 comprises a coated portion 210, which is opaque, and an etched portion 220 in which the transparent substrate is exposed and from which light may be transmitted. The knob thereby includes a pattern which light may be transmitted therethrough. The etched portion 220 may be ring-shaped or another suitable shape, though a ring-shape is particularly suitable for a circular knob where the whole circumference may be used by the user.

[0080] The light within the knob 200 is provided by an LED or similar light source powered from the appliance on which it is used. Where desired, the transparent substrate of the knob 200 may be tinted such that light is emitted from the knob having a different colour to the light source. For example, the substrate of the knob 200 may be tinted red in places to indicate a particular option (e.g., “Pulse setting” where a rotary tool 320 of the appliance 300 is only activated to rotate for a short duration) is selected by turning the knob to the part of the circumference of the knob tinted red. This tinting may be provided by a coating or may be integral to the substrate.

[0081] The knob 200 is preferably mounted on a spring-loaded carriage so that, when it is depressed against the bias of the spring, or otherwise moved axially, a micro-switch or other relay is triggered sending a signal to a central processing unit of the appliance 300 to which it is attached that to issue instructions to it. The instructions may be dependent on the orientation of the knob. Alternatively the knob 200 may be fixed axially and instead only control the appliance with which it is used by rotating e.g., via a potentiometer.

[0082] A collar 230 may be provided, also coated with the same coating as the coated portion 210, to protect the spring-loaded carriage and other internal elements of the knob 200 when the knob 200 is not depressed. The collar 230 may be fixed to the knob 200 to ensure a single-piece construction, or it may be provided separately on the appliance 300.

[0083] FIG. 4 shows a kitchen appliance (or a food processing appliance) 300 incorporating the knob 200. The kitchen appliance 300 comprises a user interface 310, a rotary tool 320, and a container 330 which is attached to the appliance 300 and in which the rotary tool 320 rotates to process food. Options may be selected using the knob 200 on a user interface 310 of the appliance 300 either by simply turning the knob 200 to the corresponding setting, or by turning the knob 200 to the corresponding setting and depressing it to select the appropriate option.

[0084] Depending on the option selected, the appliance 300 can respond to the option selected using the knob 200 by causing the rotary tool 320 to rotate within the container 330 to process food or beverages within, and/or cause heating and/or cooling elements to carry out heating and/or cooling of the contents of the container 330. Feedback regarding options and processing can then displayed to the user via the user interface 310.

[0085] The coated surface of the knob is generally the same (at least in appearance) as the housing of the main body of the kitchen appliance, such that the knob blends in with the rest of the housing of the kitchen appliance.

[0086] Optionally, the light source may be configured such that it shines through only part of the annular light-transmissive pattern, which allows different tinted parts of the pattern to be lit up as the knob is rotated (e.g. to indicate the selection of different options).

[0087] Whilst the invention has been discussed in terms of manufacturing a control knob for a kitchen appliance, it could be used for producing any kind of article including a decorative surface as described, or for producing a suitable etched coating on any suitable substrate, and is not limited to creating a knob.

[0088] It should be understood that the present invention has been described above purely by way of example, and modifications of detail can be made within the scope of the invention.

[0089] Each feature disclosed in the description, and (where appropriate) the claims and drawings may be provided independently or in any appropriate combination.

[0090] Reference numerals appearing in the claims are by way of illustration only and shall have no limiting effect on the scope of the claims.