GB2202117A

GB2202117A - Microwave correction oven

Info

Publication number: GB2202117A
Application number: GB08705596A
Authority: GB
Inventors: Gary Whittaker; Gordon Andrews
Original assignee: TI New World Ltd
Current assignee: TI New World Ltd
Priority date: 1987-03-10
Filing date: 1987-03-10
Publication date: 1988-09-14
Anticipated expiration: 2007-03-10
Also published as: EP0283182A1; GB2202117B; GB8705596D0

Description

1 J Microwave Ovens 2202117 This invention relates to microwave ovens and

more particularly to so- called combination micrcwave ovens which incorporate a source of convection hot air in addition to the source of microwave energy.

Combination microwave ovens are known in which hot air derived either from an electrical heater or from a gas burner is used in conjunction with the microwave energy in order to cook food placed in the oven. The hot air is conveniently circulated in the oven by means of a fan therein. Such combination microwave ovens are claimed to cook food better than straightforward microwave ovens. However, in use of such a combination microwave oven, it is necessary for any particular food item being cooked to preset the level of the microwave energy to be used. to preset the temperature or the gas mark setting of the hot air source and also to preset the time the cooking operation is to take. When it is realised that these settings will vary dependent upon the type of food being cooked then it will be appreciated that the initial setting up of a combination microwave oven can be very complex and it is virtually impossible to relate the required settings to the instructions that'are normally given in recipes designed for use with- conventional (non-microwave) ovens.

i 1 1 1 2.

It is an object of the present invention to provide a combination microwave oven which is easier to set up and in which in a pref erred f orm the set-up procedure can be more easily related to conventional food recipes.

According to the present invention there is provided a microwave oven comprising a source of microwave energy, a source of hot air, and control means for setting the effective temperature of said source of hot air, means being provided for automatically setting the level of the microwave energy in dependence upon the setting of said control means.

Advantageously, timer means will be provided f or pre-setting the cook time of a cooking operation, the means for automatically setting the level of microwave energy being arranged to vary the setting of the microwave energy during said cook time in dependence upon the setting of said control means.

In a preferred form of microwave oven according to the present invention, means is provided for subdividing the preset cook time into a plurality of time periods, and in which the means for automatically setting the level of microwave energy is arranged to automatically set the level of microwave energy in each of said time periods, the level of microwave energy in at least one of said time periods being dependent upon 1 3.

11 the setting of said control means.

Advantageously, the cook time will be sub-divided into four time periods, a first time period corresponding to the first 20% of the preset cook timep a second time period corresponding to the next 30% of the preset cook time, a third time period corresponding to the next 30% of the preset cook time and a fourth time period corresponding to the next 20% of the preset cook time.

Conveniently it may be arranged that in some of said time periods the level of microwave energy is set independent of the setting of said control means. and in the other of said time periods the level of microwave energy is set in dependence upon the setting of said control means.

In an especially preferred microwave oven, during the first time period the level of microwave energy is set to 85% of maximum, during the second time period the level of microwave energy is set to between 20% and 70% of said maximum dependent upon the setting of said control means. during the third time period the level of microwave energy is set to between 10% and 40% of said maximum dependent upon the setting of said control means, and during the fourth time period the level of microwave energy is set to 10% of said maximum.

The source of hot air may comprise an electric 1 4.

heater, in which case the control means may comprise a temperature thermostat control, or it may comprise a gas burner, in which case the control means may comprise a gas mark thermostat control.

A fan may also be provided for circulating the hot air.

An exemplary embodiment of the invention will now be described in the form of a gas microwave combination oven which includes an oven cavity having a conventional microwave energy source, a gas burner located in the rear of the floor of the oven cavity and also a circulating fan located in the rear wall of the oven cavity for circulating the hot air derived f rom the gas burner. The combination oven will be provided with a gas mark control for thermostatically controlling the gas burner and thus the temperature of the oven cavity. and also a timer whereby the "cook time" of the combination oven may be set. 20 It is preferably arranged that the gas mark control takes the form of an electronic control which consists of "UP" and nDOWNn buttons for setting the required temperature. The means for automatically setting the level of the microwave energy will comprise a microprocessor which incorporates a software program which takes account of the setting of the gas mark z 1 5.

control and also the preset "cook time" in order to set the level of the microwave energy.

Preferably the microprocessor is programmed to sub-divide the ncook-timew into four time periods corresponding to Mr 30%y 30% and 20% of the cook time. respectively, as shown in the attached drawingy and is also programmed to set the level of the microwave energy in each of the four time periods as follows:

lst. (20%) Period: set to 85% of maximum; 2nd. (30%) Period: set to between 20% and 70% of maximum dependent upon the setting of the gas mark control; 3rd. (30%) Period: set to between 10% and 40% of maximum dependent upon the setting of the gas mark control; 4th. (20%) Period: set to 10% of maximum.

It will be appreciated that the number of time periods that the wcook-timew is sub-divided into and also the microwave energy levels that are set for each of the time periods are exemplary only and other than four time periods and different microwave energy levels may be used as required.

It has been found that by coordinating the temperature and microwave energy over the 'cook-time', a foods cooked- finished result can be achieved that is is i 1 6.

comparable to convent ionally. cooked methods. but in considerably less time. This is achieved by arranging that the correct internal and external food temperatures are reached simultaneously. the resultant effect being achieved without undue overheating of the food so that food spatter and smoking is minimised. The coordination of temperature and microwave energy also minimises operator error and confusion in that it can be adapted to conventional food recipes by using a simple time adjustment procedure (eg cook in half the time). The final 10% microwave energy time period is used to prevent overcooking, and allows a degree of operator adjustment to compensate for any meal serving delay.

It is also envisaged that the microprocessor control will be expanded to introduce "weight-volume food type" program information into the controller memory, so that it can be used in the "fully automatic cook" and 'microwave only defrost' modes.

7.

claims 1. A microwave oven comprising a source of microwave energy, a source of hot air,, and control means for setting the effective temperature of said source of hot air,, means being provided for automatically setting the level of the microwave energy in dependence upon the setting of said control means.

2. A microwave oven as claimed in claim 1. comprising timer means for,presetting the cook time of a cooking operation, in which the means for automatically setting the level of microwave energy is arranged to vary the setting of the level of the microwave energy during said cook time in dependence upon the setting of said control means.

3. A microwave oven as claimed in claim 2, in which means is provided for subdividing the preset cook time into a plurality of time periodst and in which the means for automatically setting the level of microwave energy is arranged to automatically set the level of microwave energy in each of said time periods,. the level of microwave energy in at least one of said time periods being dependent upon the setting of said control means.

4. A microwave oven as claimed in claim 3, in which the preset cook time is subdivided into four time k_ 8.

periods.

5. A microwave oven as claimed in claim 4. in which a first time period corresponds to the first 20% of the preset cook time, a second time period corresponds to the next 30% of the preset cook time, a third time period corresponds to the next 30% of the preset cook time, and a further time period corresponds to the next 20% of the preset cook time.

6. A microwave oven as claimed in claim 5. in which in some of said time periods the level of microwave energy is set independent of the setting of said control means, and in the other of said time periods the level of microwave energy is set in dependence upon the setting of said control means.

7. A microwave oven as claimed in claim 6. in which during the first time period the level of microwave energy is set to 85% of maximum. during the second time period the level of microwave energy is set to between 20% and 70% of said maximum dependent upon the setting of said control means, during the third time period the level of microwave energy is set to between 10% and 40% of said maximum dependent upon the setting of said control means, and during the fourth time period the level of microwave energy is set to 10% of said maximum.

8. A microwave oven as claimed in any preceding d 4 P V.) 9.

claim, in which the source of hot air comprises an electric heater.

9. A microwave oven as claimed in claim 8 in which the control means comprises a temperature thermostat control.

10. A microwave oven as claimed in any of claims 1 to 7, in which the source of hot air comprises a gas burner.

11. A microwave oven as claimed in claim 10, in which the control means comprises a gas mark thermostat control.

12. A microwave oven as claimed in any preceding claim, comprising a fan for circulating hot air.

13. A microwave oven substantially as hereinbefore described.

14. A microwave oven substantially as hereinbefore described with reference to the accompanying drawing.

Published 1988 at The Patent Ofnee, State House, 86171 High Holboim, London WC1R 4TP. Puither copies may be obtained from The Patent Omce. Sales Branch- St Vs" rrAv nminotnn Rent RRS ZW) Printed hv MultiDlex teobnlaUeS ltd. St Marv Crav. Eent. Con. 1187.