GB2423463A

GB2423463A - Viewing contents of kitchen appliance

Info

Publication number: GB2423463A
Application number: GB0514127A
Authority: GB
Inventors: John Crooks; Peter Keig
Original assignee: Morphy Richards Ltd; Morphy Richards NI Ltd
Current assignee: Morphy Richards Ltd; Morphy Richards NI Ltd
Priority date: 2005-07-09
Filing date: 2005-07-09
Publication date: 2006-08-30
Anticipated expiration: 2025-07-09
Also published as: GB2423463B; GB0514127D0; GB2441722A; CN1806732A; WO2007007019A1; CN101247748A; GB0800420D0

Abstract

A kitchen appliance 200 comprising a vessel 201. A light source 209 is disposed substantially at the vessel 201. A wall of the vessel comprises a two-way mirror. When the light source 209 is not emitting light, the wall substantially reflects ambient light, giving a reflective, non-transparent appearance to the wall. When the light source 209 is emitting light, the wall substantially transmits light from the light source, effectively making the wall substantially transparent and allowing a user to see into the vessel 201. The appliance may be a kettle as shown, a toaster, an oven, a deep fat fryer or a food processor or blender.

Description

KITCHEN APPLIANCE

Field of the Invention

The present invention relates to kitchen appliances.

Background to the Invention

Kitchen appliances are used for the preparation of foods. Examples of kitchen appliances include electric kettles for boiling water, ovens for cooking or heating food, food processors and blenders for processing and mixing foods, deep fat fryers for frying food, and toasters for toasting food.

A common feature of these types of kitchen appliance is that they comprise some means to contain food; an electric kettle comprises a vessel capable of holding a fluid such as water, an oven comprises a chamber in which food can be is cooked, a food processor and a deep fat fryer each comprise a vessel in which food to be processed or fried is placed. By food, it is meant any form of nourishment including solid foodstuffs, liquid foodstuffs and water.

A problem with such kitchen appliances is that the means to contain food may not be transparent, thereby preventing a user from easily seeing whether the food is cooked or processed sufficiently. Where transparent means to contain food are used, these can quickly become dirty and unsightly owing to deposits that cannot be easily cleaned away. For example, lime scale from hard water can be deposited in electric kettles, and burned fat can be deposited on deep fat fryers. The problem will be explained in more detail with reference to electric kettles, although the same basic problem exists for other kitchen appliances.

Electric kettles comprise a vessel capable of holding a fluid such as water, a heating element disposed in the vessel, and control electronics to allow a user to activate the heating element. The control electronics typically also comprise means to deactivate the heating element when the fluid is at the required temperature. Electric kettles provide a quick and simple means for boiling water.

Conventional electric kettles comprise a metallic or plastics vessel. A user must rely on the sound of the water boiling, the sight of water vapour being emitted from the spout or the temperature of the vessel to ascertain whether or not the heating element is functioning. Some conventional kettles include a light on the outside of the vessel to indicate to the user whether the kettle is operating or not. L0

Other types of known kettle comprise a light source disposed within the vessel to illuminate features such as a water level indicator. Again, the illumination is provided to indicate to the user whether the kettle is operating or not.

An example of a known kettle is illustrated schematically in Figure 1. Figure 1 shows a kettle 100 comprising a vessel 101. The vessel comprises a spout 102 configured to assist in pouring water and in some kettles, for filling the kettle 100. The kettle further comprises a handle 103, a lid 104 configured to close the vessel 101. A lower portion 105 of the vessel 101 houses a heating element (not shown) capable of heating water contained in the vessel 101. In some prior art kettles, the heating elements are enclosed in a housing, in other prior art kettles the elements are exposed directly to the water. The kettle 100 further comprises a power switch 106 to allow a user to turn the kettle on, thereby allowing the heating elements to heat up. Some kettles comprise a water level indicator 107 that allows a user to see the level of water in the vessel. The kettle 100 further comprises a housing 108 for control electronics. Control electronics are used to control whether electric current is passed to the heating elements or not. Control electronics usually comprise means to cut the electric current to the heating elements when the water in the vessel has reached the required temperature.

In the example shown, the switch 108, the handle 103 and the water level indicator are all mounted on the housing 108 for the control electronics, which is in turn mounted on the vessel 101. The housing 108 further comprises an illumination source (not shown) configured to illuminate the water level indicator 107 when the heating elements are active, that is to say when electric current is flowing to the heating elements.

Other types of known kettle have a vessel comprising a transparent material that has a low thermal expansion coefficient and hence a good resistance to thermal shock. Transparent vessles have the advantage that the user can see the water boiling. Any type of transparent material may be used for the vessel walls, provided it has sufficient resistance to thermal and mechanical shock, and is sufficiently chemically inert so as not to react with boiling water. Examples of such materials include certain plastics and certain glasses or glass-ceramics.

Borosilicate glass compositions such as Pyrex possess the required properties.

A disadvantage of kettles with transparent vessels is that dirt can build up or the vessel can degrade to become opaque. Furthermore, in some regions, the water is hard', that is to say it contains magnesium and/or calcium ions in such quantities that unsightly deposits of scale can be formed on or around the heating element. Where the kettle has a transparent vessel, these unsightly deposits are deleterious to the appearance of the kettle. Similar deposits from foodstuffs can build up in deep fat fryers, toaster, ovens, food processors and other kitchen appliances.

Summary of the Invention

The inventors have realised that there is a need for a kitchen appliance that allows a user to see whether the kitchen appliance is functioning or not, but does not normally show deposits that may have formed inside the vessel of the kitchen appliance.

According to a first aspect, there is provided a kitchen appliance comprising: a vessel a light source disposed substantially at said vessel, said light source being configured to illuminate an interior of said vessel; characterized in that a wall of said vessel comprises a two-way mirror.

Preferably, said light source is disposed substantially at an outer surface of said vessel.

Alternatively, said light source is disposed substantially within said interior of said vessel.

Preferably, said wall is configured to substantially transmit light emitted from said light source when said light source is emitting light; and said wall is configured to substantially reflect ambient light when said light source is not emitting light.

Preferably, said wall is formed from a partially mirrored glass-ceramic.

Alternatively, said wall is formed from a partially mirrored glass.

Preferably, said wall is formed from a borosilicate glass composition; and said wall comprises a reflective coating disposed at a surface of said vessel.

Preferably, said reflective coating is disposed at an outer surface of said vessel.

Preferably, said reflective coating is formed from a material selected from: * titanium * silver * aluminum * copper * gold Preferably, said light source is selected from the following: * cold cathode light source; * filament lamp * light emitting diodes * flourescent light source * halogen light source Preferably, the kitchen appliance comprises an electric kettle; and said vessel is capable of holding water.

Preferably, the kitchen appliance comprises: an electric heating element; control electronics configured to allow electric current to flow to said electric heating element as required by a user, said control electronics also configured to allow electric current to flow to said light source.

Preferably, said light source is configured to be activated simultaneously with said electric heating element.

Preferably, said control electronics comprises means to automatically cut a flow of electric current to said heating element and to said light source when a temperature within said vessel is at a predetermined temperature.

Alternatively, said kitchen appliance is configured to heat a product.

Preferably, said kitchen appliance is an toaster; and said vessel comprises a chamber configured to hold food during a toasting operation.

Brief Description of the Drawings

For a better understanding of the invention and to show how the same may be carried into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which: Fig. I illustrates schematically a side elevation view of a prior art kettle.

Fig. 2 illustrates schematically a side elevation view of the kitchen appliance according to the first specific embodiment with an illuminated light source.

Fig. 3 illustrates schematically a cross-section through a wall of vessel, and the way in which it reflects and transmits light.

Fig. 4 illustrates schematically a side elevation view of the kitchen appliance according to the first specific embodiment with the light source not illuminated.

Detailed Description

There will now be described by way of example a specific mode contemplated by the inventors. In the following description numerous specific details are set forth in order to provide a thorough understanding. It will be apparent however, to one skilled in the art, that the present invention may be practiced without limitation to these specific details. In other instances, well- known methods and structures have not been described in detail so as not to

unnecessarily obscure the description.

The general principles are described in the first specific embodiment with reference to an electric kettle by way of example. It will be apparent that the same or similar concepts can be applied to other types of kitchen appliance.

Referring to Fig. 2 herein, there is illustrated schematically a side elevation view of the kitchen appliance according to the first specific embodiment with an illuminated light source. The kitchen appliance according to the first specific embodiment is an electric kettle. The kettle 200 comprises a vessel 201, the vessel capable of holding a fluid such as water. The vessel 201 comprises a spout 202 to assist a user in pouring a fluid, and a lid 203 to substantially close the vessel 201. The kettle 201 further comprises a lower portion 204, which is disposed at the base of the vessel 201 and may or may not be formed integrally with the vessel 201. The lower portion 204 comprises a heating element 205, the heating element 205 being capable of heating up when electric current is passed through it, thereby heating any fluid contained in the vessel 201. For certain types of cordless kettle, the lower portion may also include means for connecting to a power source on a base station (not shown) as is known for prior art cordless kettles. Where a kettle is not of the cordless type, the kettle further comprises a connection point (not shown) for connecting the kettle 200 to a power supply.

The kettle 200 further comprises a housing 206 disposed at a wall of the vessel 201. The housing 206 comprises control electronics (not shown), a switch 207, the switch 207 being configured to allow a user to turn the kettle 200 on or off. The housing 206 further comprises a handle 208 disposed extending away s from the vessel 201, the handle 208 being configured to allow a user to pick up the kettle 200 for filling it or pouring water without having to touch the hot vessel 201 walls.

The housing 206 comprises a light source 209 disposed at the housing 206 and substantially at a surface of the vessel 201. The light source 209 is disposed at an outer surface of the vessel, and is configured to illuminate the interior of the vessel 201 when the light source 209 is operating. Alternatively, the light source 209 may be disposed substantially within the vessel in order to illuminate the interior of the vessel.

Any suitable light source may be used, including cold cathode light sources, filament lamp, light emitting diodes or flourescent light sources. Cold cathode fluorescent lamp (CCFL) technology is particularly suitable. A CCFL is constructed from a sealed glass tube equipped with electrodes at both ends. The glass tube is filled with an inert gas and a small amount of mercury and it has an inner coating of a phosphor. A phosphor refers to any chemical substance that is capable of emitting light when irradiated with particles of electromagnetic radiation. When high voltage current is applied to the electrodes, the resulting arc causes the gas to ionize which results in the creation of ultra violet (UV) light that in turn excites the phosphor. The wavelength of light emitted by the CCFL is determined by the composition of the inner phosphor coating.

CCFL light sources have the following features: * Increased brightness in comparison to prior art lamps when compared on an electrical power consumption basis.

* High efficiency transformation of electrical energy to light.

* Increased reliability in comparison to prior art light sources.

* An extremely long working lifetime in comparison to prior art light sources.

* Lower power consumption than most prior art light sources.

Whilst other light sources, such as filament lamps or light emitting diodes (LEDs) may be used in this application, it is the features listed above that make CCFL light sources particularly suitable. In particular, the long working life means that the light source will rarely require replacing during the lifetime of the kettle 200.

The wall of the vessel 201 comprises a transparent material having a reflective coating disposed at a surface of the wall. Referring to Fig. 3 herein, there is illustrated schematically a cross-section through a wall of the vessel, and the way in which it reflects and transmits light.

The transparent wall 301 of the vessel 201 comprises a transparent material that is resistant to thermal shock. Borosilicate glass compositions, such as Pyrex or Duran , have been found to be particularly suitable. Borosilicate glasses typically have a composition in the region of 81 % Si02, 13% B203, 4% Na20 + K20 and 2% Al203.

Transparency is required to allow the wall 301 to transmit light from the light source 209 from within the vessel 202. Resistance to thermal shock is required as the vessel 201 is required to contain boiling water. If the vessel 201 is filled with cold water after having just contained boiling water, the speed of cooling could lead to high thermal stresses in a material having a high thermal expansion coefficient.

Other materials, such as different glass compositions, certain glass ceramics and certain plastics may also be used, provided they have sufficient transparency to transmit light from the light source 209 from within the vessel 201 and sufficient resistance to thermal shock.

The transparent wall 301 has an outer surface 302 and an inner surface 303. The outer surface 302 of the transparent wall 301 comprises a reflective coating 304. This coating 304 is configured to reflect incident light in the same way as a coating on a mirror. Unlike the coating on the mirror, the reflective coating 304 on the wall 301 is applied in a sparse layer, known as a half-silvered surface. The half silvered surface is configured to reflect approximately half the incident light that strikes its surface, and transmit the other half of the incident light.

It will be apparent that the reflective coating 304 would work equally well if it were applied to the inner surface 303 of the wall 301 instead of the outer surface 302 of the waIl 301.

Any suitable material may be used for the reflective coating 304 of the wall 301. A suitable material is one that has a high reflectivity for visible light, and can be deposited at the surface of the wall 301, and has sufficient scratch resistance.

Suitable materials for the coating 304 include metals such as gold, silver, aluminium, copper and titanium. Metals are preferred as they tend to have a high reflectivity for visible light. Titanium is used in this application. It has been found using scratch resistance tests that a titanium reflective coating 304 has sufficient scratch resistance to withstand normal use of the kettle without easily scratching away from the outer surface 302 of the waIl 301. Any scratches would show up on the wall as a region of lower reflectivity and higher light transmission.

It is possible that other materials may be used even where they do not have the same scratch resistance as titanium, provided they have adequate reflectivity for visible light. In this case, they can be protected with a transparent protective coating.

The wall 301 and surface coating 304 in combination form a two-way mirror, which is configured to substantially reflect a fraction of incident light and substantially transmit the remaining fraction of incident light. This allows the two- way mirror to function either as a mirror or a window, depending on the relative light levels either side of the two-way mirror.

When ambient light 305 from a source 306 outside the vessel 201 strikes the reflective coating 304 at the outer surface 302 of the transparent wall 301, a fraction of the incident ambient light 305 is reflected as reflected ambient light 307. The other fraction of the ambient light 305 is transmitted through the transparent wall 301 as transmitted light 308.

When light 309 from a source 209 within the vessel 201 strikes the inner surface 303 of the wall, it is substantially transmitted through the wall 301. The refracted light 310 is transmitted through the wall 301, and a small portion of the light 309 from the light source 209 is reflected 311 back into the vessel 201.

When the refracted light 310 exits the wall 301, it is refracted again and exits as transmitted light 312.

Where there is no light source within the vessel 201, or the light source 209 within the vessel 201 is not illuminated, the intensity of the reflected ambient light 307 is far greater than the intensity of the transmitted light 312 from inside the vessel 201. The vessel 201 therefore appears to be mirrored and has an appearance similar to that of chrome. It is not apparent to a user that the vessel wall 301 comprises a substantially transparent material as the user cannot see through the transparent wall 301 owing to the intensity of the reflected light. 308.

This hides any lime scale or dirt that has built up within the vessel 201 of the kettle 200.

When the transmitted light 312 arises from the light source 209 within the vessel 201, the intensity of the transmitted light 312 is far greater than the intensity of the reflected ambient light 307. Due to the difference in intensities between the transmitted light 312 and the reflected ambient light 307, the wall 301 appears transparent to the user, and so the user can see inside the vessel 201 to ascertain whether the kettle is functioning or not. Furthermore, the light source 209 also provides illumination to the surroundings.

The kettle 200 illustrated in Fig. 2 is shown with the light source 209 illuminated, thereby making the vessel 201 appear to be transparent, because the intensity of the transmitted light 312 is far greater than the intensity of the reflected ambient light 307. This allows the user to see the contents of the vessel 201, in particular the water 210 and whether it is boiling or not.

Referring to Fig. 4 herein, there is illustrated schematically a side elevation view of the kettle according to the first specific embodiment with the light source not illuminated. The intensity of the reflected ambient light 307 is far greater than the intensity of the transmitted light, as the light source 209 is not illuminated.

The surface of the vessel 201 therefore appears to be mirrored, and so has an appearance similar to that of chrome. The vessel 201 therefore appears non- transparent and reflective, as the user cannot see through the wall 301 of the vessel 301 and the contents of the vessel 201 are hidden from the user.

The switch 207 of the kettle 200 is configured to allow electric current to flow to both the heating element 205 and the light source 209. In this way, when a user activates the switch, both the heating elements and the light source receive electric current. When the switch is activated, the appearance of the vessel 201 switches from a mirrored, non-transparent appearance, as shown in Fig. 4, to a transparent appearance, as shown in Fig. 2. It is therefore apparent to the user that the kettle has been switched on.

The kettle is equipped with an automatic cut-out that switches off the electric current to the heating element 205 and the light source 209 when the water 210 in the vessel 201 has reached a predetermined temperature (usually 1000). When electric current is switched off automatically by the cut-out circuit, the switch 207 returns to its "off' position, and the appearance of the vessel 201 switches from a transparent appearance, as shown in Fig. 2, to a non- transparent, mirrored appearance, as shown in Fig. 4.

In alternative embodiments, the technology can be used with other types of kitchen appliance. For example, an electric toaster can be equipped with a two- way mirror wall and a light source, the light source being configured to illuminate when the heating elements in the toaster are activated. Where the kitchen appliance is a toaster, the vessel of the toaster is the chamber in which the food is toasted.

Where the kitchen appliance is a deep fat fryer, the vessel of the deep fat fryer is the vessel in which hot oil is contained.

Where the kitchen appliance is an oven or a microwave oven, the vessel of the oven is the chamber in which foodstuffs are placed for cooking or heating. In particular, an oven comprises a door, to the chamber, and the door comprises a two-way mirror. A light source is disposed substantially at the chamber. When the oven is not in use, the door has a mirrored appearance similar to that of chrome. When the oven is in use, the light source emits light, and the oven door appears transparent to a user, allowing the user to see inside the oven.

Where the kitchen appliance is a food processor or a blender, the vessel of the kitchen appliance is the container in which food is positioned for processing.

For all of the above examples, when the appliance is not in use, the vessel appears to have a reflective non-transparent appearance. When the vessel is in use, the light source is illuminated and a wall of the vessel transmits light from the light source, thereby allowing a user to see into the vessel.

Claims

Claims: 1. A kitchen appliance comprising: a vessel a light source

disposed substantially at said vessel, said light source being configured to illuminate an interior of said vessel; characterized in that a wall of said vessel comprises a two-way mirror.
2. A kitchen appliance as claimed in claim 1 wherein said light source is disposed substantially at an outer surface of said vessel.
3. A kitchen appliance as claimed in claim I wherein said light source is disposed substantially within said interior of said vessel.
4. A kitchen appliance as claimed in any preceding claim wherein said wall is configured to substantially transmit light emitted from said light source when said light source is emitting light; and said wall is configured to substantially reflect ambient light when said light source is not emitting light.
5. A kitchen appliance as claimed in any of claims 1 to 4 wherein said wall is formed from a partially mirrored glass-ceramic.
6. A kitchen appliance as claimed in any of claims I to 4 wherein said wall is formed from a partially mirrored glass.
7. A kitchen appliance as claimed in claims 6 wherein said wall is formed from a borosilicate glass composition; and said wall comprises a reflective coating disposed at a surface of said vessel.
8. A kitchen appliance as claimed in claim 7 wherein said reflective coating is disposed at an outer surface of said vessel.
9. A kitchen appliance as claimed in claim 7 or claim 8 wherein said reflective coating is formed from a material selected from: * titanium * silver * aluminum * copper * gold
10. A kitchen appliance as claimed in any preceding claim wherein said light source is selected from the following: * cold cathode light source; * filament lamp * light emitting diodes * flourescent light source * halogen light source
11. A kitchen appliance as claimed in any preceding claim wherein the kitchen appliance comprises an electric kettle; and said vessel is capable of holding water.
12. A kitchen appliance as claimed in any claim 11 comprising: an electric heating element; control electronics configured to allow electric current to flow to said electric heating element as required by a user, said control electronics also configured to allow electric current to flow to said light source.
13. A kitchen appliance as claimed in claim 12 wherein said light source is configured to be activated simultaneously with said electric heating element.
14. A kitchen appliance as claimed in claim 13 wherein said control electronics comprises means to automatically cut a flow of electric current to said heating element and to said light source when a temperature within said vessel is at a predetermined temperature.
15. A toaster as claimed in claim 14, wherein said vessel comprises a chamber configured to hold food during a toasting operation.

15. A kitchen appliance as claimed in any of claims I to 10 wherein said kitchen appliance is configured to heat a product.

16. A kitchen appliance as claimed in claim 15 wherein said kitchen appliance is an toaster; and said vessel comprises a chamber configured to hold food during a toasting operation.

Amendments to the claims have been filed as follows Claims: 1. An electric kitchen appliance comprising: a vessel a heating element for heating inside said vessel; a visible light source disposed substantially at said vessel, said light source being configured to illuminate an interior of said vessel with visible light; characterized in that a wall of said vessel comprises a two-way mirror wherein said wall is configured to substantially transmit light emitted from said light source when said light source is emitting light; and said wall is configured to substantially reflect ambient light when said light source is not emitting light; - - wherein said light source is configured to be activated simultaneously with said electric heating element, such that when the appliance is in use, said light source is illuminated, and said wall of the vessel transmits light from the light source, thereby allowing a user to see into the vessel, and when the appliance is not in use, the vessel appears to have a reflective non-transparent appearance.

2. An electric kitchen appliance as claimed in claim I wherein said light source is disposed substantially at an outer surface of said vessel.

3. An electric kitchen appliance as claimed in claim I wherein said light source is disposed substantially within said interior of said vessel.

4. An electric kitchen appliance as claimed in any of claims I to 3 wherein said wall is formed from a partially mirrored glass-ceramic.

5. An electric kitchen appliance as claimed in any of claims 1 to 3 wherein said wall is formed from a partially mirrored glass.

6. An electric kitchen appliance as claimed in claim 5 wherein said wall is formed from a borosilicate glass composition; and said wall comprises a reflective coating disposed at a surface of said vessel.

7. An electric kitchen appliance as claimed in claim 6 wherein said reflective coating is disposed at an outer surface of said vessel.

8. An electric kitchen appliance as claimed in claim 6 or claim 7 wherein said reflective coating is formed from a material selected from the set: titanium; silver; aluminum; copper; gold.

9. An electric kitchen appliance as claimed in any preceding claim wherein said light source is selected from the following set: a cold cathode light source; a filament lamp; light emitting diodes; a flourescent light source; a halogen light source.

10. An electric kitchen appliance as claimed in any preceding claim wherein the kitchen appliance comprises an electric kettle; and said vessel is capable of holding water.

11. An electric kitchen appliance as claimed in any preceding claim: comprising: an electric heating element; control electronics configured to allow electric current to flow to said electric heating element as required by a user, said control electronics also configured to allow electric current to flow to said light source.

12. An electric kitchen appliance as claimed in any one of the preceding claims, wherein said control electronics comprises means to automatically cut a flow of electric current to said heating element and to said light source when a temperature within said vessel is at a predetermined temperature.

13. An electric kitchen appliance as claimed in any one of the preceding claims, wherein said kitchen appliance is configured to heat a product.

14. An electric kitchen appliance as claimed in claim 13 wherein said kitchen appliance is a toaster.