JP2539194B2 - Microwave oven and cooking method - Google Patents

Description

FIELD OF THE INVENTION The present invention relates to microwave ovens and methods of cooking food.

BACKGROUND OF THE INVENTION Applicant's European Patent Application Publication No. 0122710 discloses a microwave oven which simultaneously heats the cavity with thermal power provided by a circulation of hot air forced through the oven cavity by a fan. Gives microwave power. A temperature sensor (which senses the temperature of the hot air) and timing means monitor temperature / time changes. If the cold oven reaches a certain maximum temperature of hot air (eg 250 ° C) within a certain time (eg 30 minutes) from the start of cooking, the oven will automatically switch off to finish the cooking process. To do. Most foods other than large meat or pans will be cooked within this time by this method. For large meats and pans where the maximum temperature is reached after a certain time, the microwave power supply is increased when the maximum temperature is reached in order to complete the cooking of these heavy foods. The thermal power supply is reduced. Due to such heavy food, the hot air temperature will drop by the time after a certain amount of time has passed, but the curve has a small (negative) slope, which is up to any set level. It means that the end of cooking, as judged by the decrease in temperature, can be ambiguous.

The present invention relates to a modified method of cooking such heavy foods which does not reach a predetermined maximum temperature within a predetermined time, the purpose of which is to increase the slope of the temperature / time curve in the final stage of cooking. It is to make the switch-off time clearer.

SUMMARY OF THE INVENTION In accordance with the present invention, a microwave oven comprises a microwave generator for providing microwave power to a cavity of the oven and a heat heating means for providing heat power in the form of forced flow of hot air through the cavity. , A selector means for selecting a first cooking program suitable for baked foods, a second cooking program suitable for meats other than poultry, and a third cooking program suitable for poultry, and the temperature of the hot air stream And a control means responsive to the selector means and the temperature sensing means, the control means having the sensed temperature reaching a predetermined level by the simultaneous generation of microwave power and thermal power. Sometimes the power supply to the microwave generator and the heating means is switched off and if the first program is selected the cooking process is terminated, If the 2nd or 3rd program is selected, microwave power is applied without heat power in the final cooking stage to end the cooking process, and the temperature sensed in the final stage is the microwave. It falls to a certain switch-off temperature at which the supply of wave power is stopped.

When cooking poultry, the final stage preferably begins when the sensed temperature reaches a predetermined level and ends when the sensed temperature reaches a predetermined switch-off temperature. In the final stage, the microwave power is preferably increased relative to the level of microwave power being generated before the sensed temperature reaches a predetermined level. Preferably, the microwave power level is more than doubled 3 when the sensed temperature reaches a predetermined level.
The heat power supply is stopped at this time,
And hot air is not given in the final cooking stage.

The temperature sensing means preferably senses the temperature of the hot air stream at a location just downstream of the electrical resistance heating element,
Air is circulated by the fan.

When cooking beef other than poultry, there is an intermediate step that preferably begins when the sensed temperature reaches a predetermined level and continues until the sensed temperature drops to an intermediate threshold where the final stage begins. Exists. In the intermediate stage, the amount of thermal power is preferably reduced and the amount of microwave power compared to the level of thermal power and microwave power obtained before the detected temperature reached the predetermined level. Is preferably increased.

When cooking poultry, the sensed temperature will take longer to reach a given level than for non-poultry meat. This time difference can be used conveniently,
Temperature / time changes detected by the oven can be used to detect whether the food being cooked is poultry or non-poultry meat. If the temperature / time change indicates that the chicken is being cooked, the oven will immediately enter the final cooking stage when the perceived temperature reaches a predetermined level, at which point hot air will be provided. Absent. Alternatively, if the temperature / time change indicates that meat other than poultry is being cooked, the oven will begin an intermediate stage and be sensed when the sensed temperature reaches a predetermined level. The final cooking stage is started when the temperature reaches an intermediate threshold.

Preferably, the oven has the ability to extend the cooking process by a predetermined percentage of the time it takes, the extension being done at a higher microwave and thermal power level than when switched off. The predetermined percentage is between 15% and 25%, preferably 20%.

Description of Examples A first microwave oven closely related to the present invention is similar to that described in Applicant's European Patent Application No. 0122710, but with microwave and thermal power operation. The governing control means has been modified so that meat other than poultry is cooked according to the graph of FIG. 1 and poultry is cooked according to the graph of FIG. Foods other than meat are cooked in the manner described in the cited European patent application.

The oven has temperature sensing means, which includes a thermistor located in the hot air stream just downstream of the electrical resistance heating element. The electrical resistance element is located in a compartment behind the back wall of the oven cavity, as described in the cited European patent application.

Referring to FIG. 1, animal meats other than poultry are simultaneously squeezed with microwave power and forced hot air during an initial stage 10 in which the sensed temperature rises uniformly over time. If the sensed temperature reaches a predetermined level T1, the microwave power level is more than doubled 3 in the intermediate stage 12.
The thermal power level is halved and the thermal power level is halved, during which the temperature of the hot air drops until it reaches a predetermined intermediate threshold temperature level T2. At temperature T2, the final cooking stage 14 begins. During the final cooking step 14, the microwave power level is maintained at a value greater than or equal to 2 times and less than 3 times, but no thermal power is generated. Therefore, the temperature / time change drops more rapidly during this final cooking step 14. When the sensed temperature reaches the predetermined switch-off temperature TS, the generation of microwave power is stopped, indicating the end of the cooking process at time ts. The steepness of the curve in the final cooking stage 14 gives a clear cut-off point at the switch-off temperature TS.

During the initial stage 10, the power level into the cavity is 20
With 0 watts of microwave power and 1130 watts of hot air, each power level during intermediate stage 12 is 500
Watts and 550 watts. During the final stage 14, the microwave power level is maintained at 500 watts but no hot air is applied. Temperature T1 is about 250 ° C, temperature T2 is about 200
° C.

The temperature / time curve for poultry is shown in FIG. During the initial stage 10, microwave power and hot air power are simultaneously applied to the oven cavity and the sensed temperature reaches a predetermined level T1. This takes longer than animal meat other than poultry to reach this predetermined temperature level T1. When the temperature T1 is reached, the microwave oven switches to its final cooking stage 14, during which the microwave power level is increased more than 2 times but less than 3 times, but no hot air is applied. Therefore, the temperature during the final stage 14 /
The time curve drops fairly sharply, giving a clear cut-off at a given switch-off temperature TS, and the cooking ends at time ts. The power level between steps 10 and 14 in FIG. 2 corresponds to the power level in steps 10 and 14 in FIG.

It will be appreciated that for poultry and non-poultry meat, the behavior after the perceived temperature reaches a predetermined level T1 is dominated by the perceived decrease in temperature rather than time. As a result of not producing hot air during the final cooking step 14, the temperature / time curve drops sharply, producing a distinct cut-off point at a given switch-off temperature TS.

The microwave oven embodiment can be cooked in an automatic mode without the user having to pre-select a particular cooking program. The cooking program actually used in a particular case depends on a temperature / time curve,
In particular, it will depend on the time to reach the threshold temperature T1, as mentioned in the above mentioned European patent application.

Some users prefer to have more control over the cooking process, and a second microwave oven was developed to meet this need. The second microwave oven operates semi-automatically and the user preselects a suitable program for the type of food to be cooked, but the manner in which the selected program proceeds depends on temperature / time changes.

FIG. 3 shows the control panel of the second oven.
The panel has a display 20 for displaying the date and time, as well as a pad 22 for setting the date and time. Below the display 20, there is a pad 2 labeled "Automatic fast"
4, Pads 26 labeled "manual high speed turbo" (this is not directly related to the invention, and pads 28 labeled "Microwave Cooking / Thawing" are provided on either side of them. Pads 30, 32 marked "Down" and "Up"
There is. Large touchpad marked "Start" 34
And the pads 36 and 38 marked "door open" and "reset / off" complete the display panel.

The second oven is also similar in circuit component to that disclosed in the applicant's European patent application published in No. 0122710, the microwave power being applied to the oven cavity at the same time as the heat power, Is provided by hot air forced to be circulated by a fan through the cavity. Temperature sensors and timing means in the hot air stream monitor temperature / time changes. The microprocessor controls the magnitude and duration of the microwave power supply and the magnitude and duration of the thermal power depending on the temperature / time variation.

However, the oven can follow a selected one of six cooking programs suitable for the food being cooked.
For example, if the user wants to cook a baked food product, such as a batter food product, touch the pad 24, which causes the microprocessor to control microwave power and thermal power according to the cooking procedure appropriate for the baked food product. If the frozen food is to be thawed and cooked, the pad 24 is touched twice. If red meat is cooked, pad 24 is 3
Touched twice, and if chicken is cooked, pad 24 is touched four times. If a complete serving is cooked, pad 24 is touched 5 times, and if already cooked food is to be heated, pad 24 is touched 6 times.

Once the pad 24 has been touched as many times as is appropriate for the food being cooked, the oven will perform the proper cooking procedure and will complete the cooking procedure when switched off due to temperature / time variations. If the food appears to be uncooked when switched off, the user can press the "start" pad 34 again, at which time the pad 34 will have a "preliminary time".
Acting as a pad, it automatically extends the cooking procedure by 20% of the cooking time from the start of cooking to the switch off.

Pad 38 is a reset / cancel pad, which serves to cancel any previously selected cooking procedure entered by pad 24. Pads 30 and 32, labeled "down" and "up", allow for modest or elaborate cooking, respectively. For example, if pad 24 is touched 3 times and pad 30 is touched to select a red meat cooking program, then the cooked meat will be less than if pad 30 was not touched. Similarly, if pad 32 is touched instead of 30, the meat will be made well-done.

FIG. 4 shows the temperature / time variation according to a typical cooking procedure in the second oven. Curve 40 is the temperature / time change for a typical baked food, which is the pad
Obtained by touching 24 once. The oven automatically switches off when the threshold temperature T1 is reached, which occurs at time C. Curve 42 shows the temperature / time variation for the frozen food that is first thawed and cooked, the cooking ending when the predetermined temperature T3 is reached, which occurs at switch-off E. Curve 44 is the temperature / time change for red meat, at which time cooking is complete. Curve 46 is the temperature / time variation for poultry, at which time cooking is complete. Curve 48 is for food to be reheated, which lasts until time A. Curve 46 is caused by the presence of a final cooking stage such as stage 14 of FIG. 2 and curve 44 is the stage of FIG.
It is caused by the presence of intermediate cooking stages and final stages corresponding to 12 and 14. It will be appreciated that curve 44 begins the intermediate stage at a temperature below that at which curve 46 begins its final stage. This is an automatic oven (Figs. 1 and 2
Figure) and the semi-automatic oven (Figure 4) as is the only significant difference.

In each case, if the spare time is selected after the selected cooking procedure has been completed, the microprocessor will read the last mode in which it was active and the total time taken, and only cook another 20% of that time. Program the oven to do so automatically. Thus, if the oven is switched off at time C for 20 minutes after the baked food has been cooked, the subsequent selection of the preparatory time will cause the oven to continue the cooking procedure for an additional 4 minutes.

Pads to choose the right program for baked food
If 24 is touched once, the second microwave oven will follow the cooking procedure shown in the flow chart of Figures 5a and 5b. The portion of the procedure shown at 50 is the selection of a "bake" program, with the option for a modest or elaborate bake, and touching pad 34 to initiate cooking. If the temperature detected by the thermistor in the compartment behind is 80 ° C or higher, 52
Automatic cooling of the oven cavity is accomplished by passing cooling air from the magnetron blower and the convection blower through the oven cavity, as shown in FIG.

As cooking progresses, the total cooking time is monitored (5
4), the display 20 shows the selected program and whether the down or up pad has been touched. Once the threshold temperature T1 is reached, microwave and convection power generation ceases (56) and display 20 indicates "cooked" (58).

After the oven door is opened, the display 20 invites the user to select the spare time option. If this is required, the user depresses the start pad 34 again (as shown at 59) and the oven is further switched off for a time equal to 20% of the time from the start of cooking to switching off. Continue both microwave and thermal power at higher levels than just before.

Additional time can be selected (60) if the user so desires.

During the preliminary cooking time, the display 20 shows 20% of the cooking time, as monitored at 54, and the timer counts down to zero.

FIG. 6a corresponds to FIG. 5a but shows a flow chart suitable for a frozen food program. The rest of the program for frozen foods is the same as for baked foods and Figure 6a should be combined with Figure 5b as a complete flow chart for frozen foods.

Similarly, Figure 7a corresponds to Figure 5a, but shows a flow chart suitable for roasting meat. It can be seen that the program has steps 1, 2, and 3 corresponding to curve 44 in FIG. The rest of the program for roast meat is the same as that for baked goods and Figure 7a should be combined with Figure 5b as a complete flow chart for roast meat.

Figure 8a corresponds to Figure 5a but shows a flow chart suitable for poultry. The program is curve 46 in Figure 4.
It can be seen that it has stages 1 and 3 corresponding to. The rest of the program for poultry is the same as for baked goods. And Figure 8a should be combined with Figure 5b as a complete flow chart for poultry. Figures 9a and 10a correspond to Figure 5a but show suitable flow charts for cooking a complete serving and for heating already cooked food, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph of temperature / time as a function of time of temperature of hot air for meat other than poultry cooked in a first microwave oven capable of cooking in automatic mode. Shows changes. FIG. 2 is a graph corresponding to FIG. 1, but showing temperature / time changes for poultry. FIG. 3 shows the control panel of a second microwave oven capable of cooking in a semi-automatic mode. FIG. 4 shows the temperature / time variation for different food products cooked in a second microwave oven. Figures 5a and 5b are a flow chart showing a cooking process for a baked food product that is cooked in a second microwave oven. Figures 6a to 10a are flow charts showing the beginning of the cooking process for five different foods cooked in a second microwave oven. In the figure, 10 is an initial stage of cooking, 12 is an intermediate stage, 14 is a final stage, 20 is a display, 22 is a pad for setting the date and time, 24 is a pad written as "automatic high speed", 26 is "manual high speed turbo". "28" means "microwave cooking /
Pads labeled "Unzip", 30 and 32 are pads labeled "Down" and "Up", 34 are pads labeled "Start", 36 and 38 are "Door Open" and "Reset / Off".
Indicates a pad marked with.

Claims (8)

(57) [Claims] 1. A microwave generator for providing microwave power to a cavity of an oven, heat heating means for providing heat power in the form of forced flow of hot air through the cavity, and a first suitable for baked goods. A memory means for storing the first cooking program, the second cooking program suitable for meat other than poultry, and the third cooking program suitable for poultry, and one of the first, second and third cooking programs Selection means for selecting one of the two, temperature sensing means for sensing the temperature of the hot air stream, and control means responsive to the selector means and the temperature sensing means, the control means having a sensed temperature of microwave power and heat. If the first program is selected by switching off the power supply to the microwave generator and the heat heating means when the predetermined level is reached by simultaneous generation of power, To end the cooking process, or to apply microwave power to end the cooking process without applying heat power during the final cooking step when the second or third program is selected. A microwave oven, wherein the temperature sensed during its final cooking step is reduced to a predetermined switch-off temperature at which the supply of microwave power below a predetermined temperature level is stopped. 2. The last step begins when the sensed temperature reaches a predetermined level and ends when the sensed temperature reaches a predetermined switch-off temperature. The microwave oven according to item 1. 3. A patent, characterized in that during the final stage the microwave power is increased compared to the level of microwave power being generated before the sensed temperature reaches a predetermined level. The microwave oven according to claim 1 or 2. 4. The microwave power level is increased more than 2 times and less than 3 times when the sensed temperature reaches a predetermined level, at which time the thermal power is stopped and the thermal power is reduced during the final cooking step. Microwave oven according to claim 3, characterized in that it is not provided. 5. There is an intermediate stage that begins when the sensed temperature reaches a predetermined level and continues until the sensed temperature drops to an intermediate threshold where the final stage begins. The microwave oven according to claim 1. 6. In the intermediate stage, the thermal power is reduced and the microwave power is reduced as compared to the level of the thermal power and the microwave power obtained before the sensed temperature reaches the predetermined level. Microwave oven according to claim 5, characterized in that it is increased. 7. The oven includes means for extending cooking for a predetermined percentage of the time occupied by the cooking process until switch-off to provide an extension of cooking time beyond switch-off, the oven comprising: Microwave oven according to any of claims 1 to 6, characterized in that the extension is carried out at a higher microwave power and thermal power level than when switched off. 8. The predetermined extension percentage is about 15% to 25% of the time occupied by the cooking process until switch-off.
Microwave oven according to claim 7, characterized in that