During the process of cooking, it is important that foodstuffs and/or substances used in the preparation of foodstuffs contained in an item of cookware are at a correct temperature, not only to ensure that the foodstuffs are cooked properly, but also, to ensure that the foodstuffs are cooked to a high standard of quality with regards to both taste and healthiness.

An example of a cooking process where the temperature of the contents of the item of cookware is important is when frying food. A problem faced when frying foods with conventional items of cookware is that the items of cookware provide no means for the person cooking to know the temperature of the contents of the item of cookware. When frying food, oils and/or fats are usually heated up in the item of cookware to a desired temperature before the foodstuffs are included. It is therefore desirable to know the temperature of the contents of the item of cookware, not only during the cooking process, but also prior to cooking the foodstuffs. If the temperature of the oils and/or fats used in the frying process is too high, the oils and/or fats tend to stick to the foodstuffs.

This affects the taste of the food, and is also unhealthy.

Furthermore, during a frying process, fat molecules break up and oxidise at high temperatures, reducing the re-usability of the oils and/or fats, and causing possible digestive problem to the consumer.

It is well known to provided a thermometer e. g. clipped in an item of cookware in direct contact with the contents of the vessel, such as for example only, a sugar thermometer so that the temperature of the contents of the vessel can be monitored. Such thermometers are difficult to use and read and particularly do not lend themselves for use for example in frying.

It is also known to provide an integral temperature indicating means on a lid of a cooking vessel. However such means do not sense the temperature of the contents of a vessel and are thus of limited use.

It has been proposed to provide on an item of cookware, a temperature indicating means so that the temperature of the item of cookware can be monitored and controlled.

For example, in US-A-5441344 there is disclosed a frying pan which has a temperature indicating LCD panel mounted in a handle of the pan. A thermocouple is provided to transmit an electrical signal from a base of the pan to the LCD panel. However, the provision of an LCD panel is an expensive solution, and there are difficulties in calibrating such a panel as the thermocouple is positioned directly above the source of heat which is applied to the base of the pan.

A simpler proposition is put forward in GB-A-1110480 which uses a reversible thermal indicating substance provided on a handle supporting member of the item of cookware. However, at least at the time this proposal was made (1965) there would not have been available thermal indicating substances which could be applied to the handle supporting member which is in direct thermal contact with the wall of the vessel, and which would reliably indicate the temperature of the contents of the vessel.

This prior proposal recognises that thermal indicating substances which were then available were subject to damage at cooking temperatures and seeks to solve this problem by providing the substance in a recess of the handle supporting member and covering the substance with a protective transparent cover, which is an inadequate solution.

Even modem thermo chromic substances provided on a handle supporting part of an item of cookware have been found not readily to be able to indicate the temperature of the contents of the vessel. This is largely due to heat rapidly being conducted to the handle supporting member when the heat is applied to the vessel. Thus such substances may indicate the temperature of the handle supporting part but not of the contents of the vessel.

According to a first aspect of the present invention there is provided an item of cookware having a vessel, the vessel including at least a base and a side wall, the base and side wall together providing a hollow in which foodstuff is in use, cooked, and the item further including a handle supported by a handle supporting member, which handle supporting member is attached to and extends outwardly of the side wall of the vessel, and wherein there is a thermochromic means mounted on the handle in the vicinity of the handle supporting member, there being insulating means maintaining the thermochromic means out of direct contact with the handle supporting member, the heat resistivity of the insulating means being such that the thermochromic means indicates, by changing appearance, when the temperature of the contents of the vessel rises above a predetermined temperature during cooking.

Thus by providing the thermochromic means in the vicinity of the handle supporting member, but insulated relative thereto, the thermochromic means is able more reliably to indicate the temperature of the contents of the vessel, because when heat is applied to the vessel, this heat will be conducted more slowly to the thermochromic means via the insulating means so that the temperature of the vessel contents will be closer to the temperature of the vessel when the thermochromic means changes appearance, e. g. colour.

Thus when performing fiying for example, a cook may be made aware when the temperature of oil in the vessel is at an appropriate temperature to start cooking, and may reduce the cooking temperature to avoid overheating of the cooking oil, when the thermochromic substance changes appearance. Thus a person cooking the foodstuff is able to control the amount of heat provided by a heat source to the item of cookware so that the temperature of the contents of the vessel may be maintained generally at an appropriate temperature.

The thermochromic means may be a substance which exhibits more than one colour change as the temperature of the contents of the vessel increases, or a plurality of thermochromic substances may be provided each exhibiting a change of appearance at a different temperature.

In each case the insulating means may be provided by material of the handle being interposed between the handle supporting member and the thermochromic means, the thickness of the material being such as to provide the required heat resistivity, and/or a layer of an insulating material may be provided between the thermochromic means and the handle supporting member e. g. between the handle and the thermochromic means. Such layer of insulation may be selected from a range of available layers to achieve a required heat resistivity suitable for the particular size and type of item of cookware.

The layer of insulation may be for example only, a non-metallic material, although may be a metallic material which has a thermal conductivity less than that of the handle supporting member. For examples only, which the handle supporting member is of aluminium, the insulating layer may be a layer of stainless steel.

In one embodiment, the thermochromic means and any layer of insulation, may be provided in a recess of the handle immediately above the handle supporting member, so as to be readily visible by the cook.

It is usual for items of cookware which are suitable for use on gas cooking rings and the like and in which the handle is made of synthetic material, to include around the synthetic handle in the region of the vessel, a flame guard to protect the synthetic handle from flames. Such a flame guard is typically of metal.

In accordance with the present invention preferably the thermochromic means is out of thermal contact with the flame guard so that flames impinging upon the flame guard will not affect the thermochromic means. As the flame guard typically extends along the handle for a distance greater than the length of the handle supporting member, the flame guard typically includes an opening and the thermochromic means is mounted on the underlying handle and is visible to the cook through the opening.

The handle supporting member may be welded, riveted, bolted or otherwise attached to the vessel wall or may be attached to the vessel wall by being integrally provided therewith, as desired.

According to a second aspect of the present invention there is provided a method of manufacturing an item of cookware according to the first aspect of the invention, the method including determining the heat resistivity of the insulating means for the item of cookware so that the thermochromic means indicates, by changing appearance, when the temperature of the contents of the vessel rises above a predetermined temperature during cooking.

The invention will now be described, by way of example only, with reference to the accompanying drawings in which:- Figure 1 is an illustration of a perspective view of a item of cookware in accordance with the invention; and Figure 2 is an illustrative cross sectional view through part of the item of figure 1.

RefelTing now to Figure 1 there is shown an item of cookware 10, which in this example is a fiying pan, having a vessel 12, the vessel 12 including a base 11 and a side wall 15 providing a hollow H. Foodstuffs and/or substances used in the preparation of foodstuffs (not shown) may be contained within the hollow of the vessel 12 during a cooking process. The item 10 further has a handle 14 which is secured to the vessel side wall 15 on a handle supporting member 13 as indicated in figure 2, and a flame guard 16, surrounding the handle 14, which is made in this example of a synthetic material such as phenolic resin, to protect the handle 14 from flames rising around the side wall 15 e. g. from a gas ring beneath.

Referring now to Figure 2 it can be seen that the handle supporting member 13 is attached to the vessel side wall 15 by welding W. This is particularly convenient where the vessel wall 15 and the handle supporting member 13 are made from the same or closely similar metals. In another example though the vessel wall 15 and the handle supporting member 13 may be attached by fastener means such as one or more bolts, rivets or the like.

In each case, heat which is applied to the base 11 during cooking is conducted by the base 11 and side wall 15 to the handle supporting member 13.

By virtue of the vessel 12 being made of good conducting material, e. g. aluminium, the handle supporting member 13 will assume generally the same temperature as that of the vessel 12, and thus may be of a very different temperature to the contents of the item 10 of cookware in the vessel 12 although the contents of the vessel 12 may have a local cooling effect on parts of the base 11 and or side wall 15 which is in context with the contents.

Thus by determining and/or by indicating the temperature of the handle supporting member 13, one does not achieve a true indication of the temperature of the contents of the vessel 12.

The handle 14 is supporte on the handle supporting member 13. This is achieved as the handle 14 has a hollow 18 into which the handle supporting member 13 is received. Fastener means, such as bolt B or a push in type fastening means is provided to retain the handle 14 on the handle supporting member 13.

In accordance with the present invention we provide a thermochromic temperature indicating means being a temperature dependent substance 20 which is positioned in the vicinity of but out of direct contact with the handle supporting member 13. The substance 20 is positioned at an upper surface 21 in a recess R of the handle 14, and is insulated from the handle supporting member 13 by both a layer 22 of the handle 14 material and an insulating layer 23 which in this example is a plate of stainless steel on which the thermochromic substance 20 is provided.

To achieve a desired amount of heat resistivity for a particular cookware item 10 construction, so that the thermochromic substance 20 assumes a colour appropriate to the temperature of the contents of the cookware item 10 rather than the temperature of the vessel 12, the thickness of the layer 22 of the handle material between the thermochromic substance 20 and the handle supporting means 13 needs carefully to be chosen, as does the thickness and heat conductivity of the insulating layer 23. Thus the heat resistivity needs to be calibrated for a particular cookware item 10 to ensure that applied heat conductivity to the thermochromic substance 20 is slowed.

Thus during initial heating at least when heat will be conducted to the handle supporting member 13 from the base 11 and side wall 15 of the vessel 12, as the temperature of the contents of vessel 12 is increasing, the thermochromic substance 20 will not react to the heat of the vessel 12 and handle supporting member 13. However as heating continues and the temperature of the contents of the vessel 12 reaches the temperature of the vessel 12 generally, the thermochromic substance 20 will become increasingly subjected to the general vessel 12 temperature and is arrange, by suitable calibration of the heat resistivity of the insulating layer 23 and handle material layer 22, to indicate the temperature of the vessel 12 contents by changing colour at a predetermined temperature. Alternatively, the substance 20 may otherwise change appearance.

As indicated in figure 2, where a flame guard 16 is provided, the thermochromic substance 20 needs to be maintained out of contact with the flame guard 16 so that the effect of any flames on the flame guard 16 does not affect the thermochromic substance 20. Thus in this example where the flame guard 16 extends along the handle 14 over the length of the handle supporting member 13, the flame guard 16 is provided with an opening 24 through which the thermochromic substance 20 on the handle 14 is visible.

The thermochromic substance 20 may be a simple dot of or graphical representation provided by the heat reactive paint which reversibly changes colour at a predetermined temperature e. g. to indicate that the contents of the vessel 12 have reached cooking temperature, or a kind of thermochromic substance 20 which exhibits different colours as the temperature rises.

If desired a plurality of dots or different kinds of thermochromic substances such as heat reactive paints may be provided.

In this latter case, each of the dots of paint 20 may change colour when the sensed temperature rises above a certain value, and the value at which each individual dot of paint changes colour may vary for each one, such that as the temperature to which the thermochromic substances changes colour rises different dots may change colour to indicate rising temperature within the vessel 12. In yet another arrangement, a plurality of different dots or the like of the same kind of thermochromic substance 20 may be provided, but with a varying amount of insulation between the individual dots and the handle supporting member 13. By arranging the dots in a suitable pattern, e. g. a linear array, increasing temperature of the contents of the vessel 12 may readily be indicated by individual of the dots of the pattern or gamay changing colour.

If desired, instead of providing both a layer 22 of handle 14 material and a layer 23 of insulation or at least material having a lesser conductivity than that of the handle supporting member 13, to achieve a desired insulation, an insulating means may be provided by handle material 22 only, or by other insulating means between the handle supporting member 13 and the thermochromic means 20. The handle 14 need not be made of a synthetic material, but could be made of metal, usually which is less heat conductive than the material of the vessel 12 and handle supporting member.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilise for realising the invention in diverse forms thereof.