KR100339950B1 - Method for controlling a microwave oven, microwave oven and its use for cooking or heating food in accordance with the method - Google Patents

Abstract

Disclosed are a method of controlling a microwave oven, a microwave oven and its use for automatic cooking and heating of food.

Food category information for the type and initial state of the food is provided to the oven for selection of the corresponding preprogrammed control program. The control program is divided into a period of time during which the microwave radiation source, the microwave active crisp plate 4 and the grill element are active at the power level determined by the program. The implementation of the program is monitored by one or more sensors that sense the temperature and / or humidity radiation or other basic radiation from the food.

Description

Method for controlling a microwave oven, microwave oven and its use for cooking or heating food in accordance with the method

The present invention acts as separate heating sources for food and is activated in the form of a container, plate or carrier on which controllable food is placed via the control unit 15 of the microwave oven. A method for controlling the process for cooking or heating food in a microwave oven, using a possible bottom heater 4 and a microwave radiation source 20 of the microwave oven. The invention also relates to the use of such microwave ovens for cooking or heating various kinds of food by automatically controlled processes, as well as to microwave ovens for implementing the methods.

Microwave radiation sources and their associated microwave supply systems distribute microwaves in oven cavities that perform so-called volume heating of food.

The microwave oven may be equipped with an additional heating source of food in the form of so-called microwave activatable crisp or browning plates. An additional heating source may be provided. The crisp plate may be composed of an aluminum plate having a small amount of heat and a good thermal conductor provided thereon with a microwave absorbing layer. Swedish patent application 9003104-8 discloses such a crisppan. The browning plate may be composed of a glass or ceramic plate having a higher calorific value and equipped with a microwave absorbing layer. Generally, the crisp and browning plates are equipped to rotate during cooking or heating.

The microwave oven may also have another heating source in the form of a so-called grill element or similar IR-radiating element, usually mounted on the ceiling of the cavity (see, eg, Swedish patent application 9201786-2).

Microwave ovens equipped with these three types of heating sources can basically be close to volume heaters, bottom heaters and top heaters, in which heat dissipation from the two previous heaters regulates the microwaves supplied to the cavity The top heater is directly controlled in terms of active time and power level. In order to optimize the heating or cooking of a particular type of food, three heating sources must be used in an appropriate manner. That is, they must be activated at adjusted power levels during the proper period of the cooking or heating process. However, the problem is that the active time and power levels vary greatly for different kinds of food. For the average user, this is too complicated and therefore typically the user is not given the opportunity to control the cooking or heating process in this way. Instead, microwave ovens are so configured that there is only one power balance determined by the manufacturer between different heating sources.

In some countries, the power consumption of single-phase connection devices is limited, which means that the microwave radiation source and grill element cannot be activated simultaneously between other materials. In addition, this places special requirements on the use of heating sources depending on the type of food discussed and tends to complicate matters further for the user.

It is therefore an object of the present invention to provide a microwave oven free of any of the drawbacks mentioned above, to favor the utilization of heating sources and at the same time to provide a microwave oven that is more user friendly.

By optimal utilization of heating sources, microwave ovens are generally more useful, such that such microwave ovens must be heated in today's conventional ovens, for example, in order not to lose the crispiness of food and cooking. And for cooking or heating dishes.

According to the invention, this object is achieved by the method of the type mentioned at the outset, and characterized by the following steps.

Providing the food category information about the food to the oven;

Selecting a cooking or heating program separated into one or more time periods, based on the food category information provided;

Activating the heating sources at power levels according to the selected program during each time period;

Calculating a control variable on the basis of the parameter information determined by the food category and one or more parameters obtained from one or more sensors which repeatedly detect the state of the food during each time period;

After the start of the program, reducing the time periods from the maximum value determined by the food category to zero, and

Terminating each time period when time is reduced to zero or when the calculated value of the control variable exceeds the value determined by the food category, and

Terminating the program when all time periods have ended.

The method according to the invention makes the handling of microwave ovens very convenient. The user simply has to enter information on the food category required, for example via the control panel of the oven. Thus the oven can then be activated either automatically or by operating the start button. The oven then selects the appropriate program according to the food category and monitors the cooking or heating process fully automatically.

The food category and food category information herein correspond to cooking or heating programs specifically designed for certain food types, such as potato products, pizza and chicken, and the state of food in ovens, such as fresh or raw frozen and semi-processed frozen products. Means information. The food category information may be provided by inputting a numerical value indicating the type of food and its state, or by inputting a first value indicating a food type and a second value indicating its initial state. In addition, the food category information is input by operating a specific control button for the food category or by operating specific buttons for the type of food and its initial state.

The microwave oven according to the invention comprises a cavity, a microwave radiation source for supplying microwaves to the cavity,

A microwave activatable bottom heater in the form of a container, plate or carrier on which food to be heated or cooked is placed,

A microwave oven comprising a control unit for controlling the floor heater as well as the supply of microwaves to the cavity, and one or more sensors for sensing and providing one or more sensing parameters indicative of the condition of the food to the control unit,

Means for providing food category information about food to the control unit, wherein the microprocessor of the control unit is capable of selecting a cooking or heating program separated into one or more time periods based on the provided food category information and,

Activating the microwave radiation source, ie the bottom heater, at power levels according to the selected program;

Repeatedly calculating the control variable based on parameter values obtained from the one or more sensors and one or more related constants determined by the food category, repeatedly for each time period;

After starting the program, reducing the time periods from the maximum value determined by the food category to zero, and

A function of terminating each time period when the time period is reduced to zero or when the calculated control variable value exceeds a value determined by the food category;

Characterized in that it is programmed to implement a function of terminating the program when all time periods have ended.

In a preferred embodiment of the present invention, a microwave oven is equipped with a top heater, which is a grill element, for example, arranged in the ceiling of a cavity, which is controlled by a selected program.

The design of the microwave oven of the present invention is that most end users use the oven to cook or heat any type of food that is already cooked, for example, a frozen dish or bread and potato product, and the food is a type of food. And based on its initial state, which can be divided into food categories. In addition, optimum utilization of the heating source (i.e. microwave field in the cavity, bottom heating crisp plate, top heating grill element) available in modern ovens is realized, improving the results of cooking and the oven for a wide range of foods or dishes. The user's intimacy with the oven is maintained or further improved by making it available.

According to the present invention, there is provided a microwave oven having a rotating crisp plate installed in an oven cavity, a grill element mounted on the ceiling of the cavity and sensors for sensing substance radiation from food as well as temperature values indicative of food conditions. Use is distinguished by the fact that the food is automatically cooked or heated according to pre-programmed cooking or heating programs that can be selected based on food-category information based on the type of food provided in the oven and its initial state. do. Further characteristic aspects of the microwave oven and the method according to the invention are described in the appended claims.

The invention will be described in more detail below with reference to the preferred and non-limiting embodiments shown in the drawings.

The microwave oven described in FIG. 1 has an outer case 1, an oven door 2 that closes the cavity 3, and a crisp plate 4 mounted in the microwave oven. The crisp plate 4 is made of an aluminum sheet with a small amount of heat, and a bottom surface thereof is equipped with a microwave absorbing layer of rubber ferrite. Preferably, the ferrite material used has a Curie point that stops the absorption of energy from the microwaves, which means that the top temperature of the crisppan that comes into contact with food is stabilized within a temperature range of 130 to 230 ° C. The crisppan will rotate during the cooking or heating process. In addition to Applicants' microwave ovens VIP20 and VIP27 types, Swedish patent application 9003104-8 describes a more detailed structure as well as the rotation mechanism of the crisp plates.

Microwaves are input to the cavity 3 through one or more supply openings 0 (not shown) which are connected to the microwave radiation source 20 (generally the magnetron) of the oven (see FIG. 2) via waveguides.

In the oven described, the magnetron, the associated waveguide system, the power supply unit 19 for operating the magnetron, and the control unit 15 are arranged behind the control panel 5. In a preferred embodiment of the microwave supply system, the use of the system consists of upper and lower supply openings provided in the right sidewall of the cavity, while the rest of the supply system is designed to supply polarized microwaves through these openings. . For more detailed information on the structure of the microwave supply system, see the above mentioned applicant's microwave ovens, as well as Swedish patent 9003012-3.

The grill element (not shown) is mounted to the ceiling of the cavity, for example in the manner described in Swedish Patent Application No. 9201786-2. The grill element may be a so-called "grill tube", a quartz tube or a halogen radiation source. Examples of specific designs are found in Applicant's VIP20 type microwave oven.

The control panel 5 has a display 6 controlled by the control unit 15, which displays plain-text messages or symbols for the selected program, the remaining cooking or heating time. Indicates. That is, information on how cooking or heating is performed and user selections made through the control panel are identified.

The control button 7 is used to select heating through the supply of microwaves to the cavity. The button 8 is used to activate the grill element of the oven and the time required is set by the knob 9. These basic options are the same as those of a conventional oven, and while using the direct acting microwave interaction of the crisppan and grill elements, choosing from preprogrammed cooking or heating programs for any number of specific types of food. An option of the present invention is added. For example, if the heating process includes only microwaves that act directly on the food, the removable crisppan can be replaced with a common rotating bottom plate.

The buttons 10, 11 are each equipped to start and switch off the oven. Keyset 12 is used to enter food category information and to select a programmed cooking or heating program. For example, the buttons may be from top to bottom, a heating button of a frozen pizza, a heating button of a frozen pie, a heating button of a frozen potato product such as chips, and a heating button of portions of a frozen chicken.

Operation of the button requires simultaneous entry of complete food category information, that is, information about the food type and its initial state (eg frozen state). In a variant embodiment of the oven, the buttons are divided into two sets, one set of buttons for input of the type of food and one set of buttons for input of the initial state of the food. In the simplest embodiment of the oven, only one food category is used, which means that only one button is required. All buttons, as well as knobs and displays, are connected to the control unit 15.

The upper side of the oven is provided with ventilation holes 13 which connect to the exhaust channel (not shown) of the cavity, in which there is a space between the ceiling of the cavity and the outer case 1. Humidity sensors and temperature sensors are installed in the exhaust channels to sense the humidity and temperature of the vented air. The sensors are directly related to the condition of the food being cooked in the cavity. In general, the humidity sensor may be a sensor capable of detecting basic radiation, humidity, gas, etc. from food (see Swedish Patent Application No. 9201314-2). Since selecting sensors and placing them in the exhaust channel is for ease of measurement only, it is not described in more detail herein.

In a single phase connection with the mains, the oven has a cord 14 with a plug.

The block diagram of FIG. 2 shows a control unit 15 and a microprocessor and associated program storage 16. User information is input to the control unit via block 17, which represents the control buttons and knob described above. The control unit controls the display 6. Through the driver 18 and the microwave power supply unit 19, the control unit 15 controls the microwave radiation source 20 to control the supply of microwaves to the cavity 3. Through the driver 21, the control unit 15 controls the grill element 22, and IR radiation is supplied to the cavity 3. The information from the cavity is transmitted to the control unit 15 via a humidity sensor 23 and a temperature sensor 24 which sense the humidity and temperature of the air, respectively, for the vented air in the exhaust channel of the cavity. As such, control of the cooking or heating process is performed by complete feedback, minimizing the sensitivity of the cooking or heating process, initiation temperature, and mains voltage to changes in the raw food product food. For more detailed information on these unit structures, see the above mentioned patents as well as the Micpopa oven manufactured by the applicant.

In FIG. 3, a flow chart describing a preprogrammed cooking or heating program consists of three consecutive time periods T1, T2, and T3. Each cycle is assigned a maximum duration determined by the food category.

During each period, once microwaves are supplied, the crisp plate as well as the grill element are activated at the power levels determined by the food category. The power levels for the microwaves and grill element, respectively, during the associated periods are designated PM1, PM2, PM3 and PG1, PG2, PG3, respectively.

Based on the information obtained from the humidity sensor and the temperature sensor, the control variable C is calculated continuously for each of the following periods.

During T1, C = a1. Humidity increase + b1.Temperature.

During T2, C = a2. Humidity increase + b2.

During T3, C = a3. Humidity increase + b3.

Here, a1, a2, a3, and b1, b2, b3 are constants determined by the food category.

During each period, the cycle time is reduced to zero. When the time is reduced to zero or the control variable exceeds the values C1, C2, C3 respectively determined by the food category, the cycle ends and the next cycle begins. When the period T3 ends, the program ends.

The power levels PM1, PM2, PM3, and PG1, PG2, PG3 are optimized for each food category, respectively, and may change during those time periods in another improved oven. Likewise, all constants a, b, c, are optimized for each food category. The supplied microwave power may be distributed between other supply openings to distribute energy between the bottom heating of the crisppan and the microwave heating inside the food. Such a distribution can be realized using a microwave input system of the kind described in Swedish patent application 9302302-6.

The program described in the flowchart of FIG. 3 performs the following steps, where Y means "yes" and N means "no".

S1 start

Set the cycle times T1, T2, and T3 based on the S2 food category.

Cook at S3 microwave power PM1, grill element power PG1 and reduce T1.

S4 T1 = O ?, if Y, go to S6; if N, go to S5

Calculate S5 C to determine if C ≥ C1, return to S3 if N, and proceed to S6 if Y

S6 microwave power PM2, grill element power PG2 cook and reduce T2.

If S7 T2 = O ?, Y, go to S9; if N, go to S8

Calculate S8 C to determine if C≥C2; go to S9 if Y; return to S6 if N.

S9 microwave power PM3 cooks at grill element power PG3 and reduces T3

S10 T3 = O? If Y, go to S12; if N, go to S11

Calculate S11 C to determine if C≥C3, go to S12 if Y, and return to S9 if N

Terminate the S12 program.

Step S13 relates to another possible improvement of the control program, in which case means are provided for providing the control unit 15 with information about the food weight in the microwave oven. For example, this can be done by installing the knob 9 of FIG. 1 so as to also function as a means for setting the weight of the food when the automatic control programs according to the invention are used. Alternatively, the oven may be equipped with a weight sensor 25 (see also FIG. 2) adjacent to a rotating crisp plate of the design described, for example, in patent application 9300291-3.

Based on the weight information W, the microprocessor calculates the predicted durations T1e, T2e, T3e of each time period of the program as follows.

T1e = k1w

T2e = k2w

T3e = k3w

Here, K1, K2, and K3 are constants according to food categories.

Those skilled in the art can understand that they are sufficiently qualified to develop the programs described above within the scope of the present invention. For example, the temperature of the vented air can be sensed when the program is started, and the parameter information used during the execution of the program may then be calibrated in view of the sensed temperature. As such, one program eliminates any effect on the oven being heated at the start stage. Another program introduces a temperature sensor that senses the temperature of the crisppan and can be used to control microwave radiation sources and grill elements. When implementing the method according to the invention, so-called fuzzy logic judgments can be applied. Any changes derived from this may be accomplished within the scope of the appended claims.

1 is a view of the microwave oven of the present invention with the door open.

2 is a block diagram showing supported functional units of an oven while implementing the improved method.

3 is a flow chart illustrating a cooking or heating program programmed to control the microprocessor of the control unit.

※ Explanation of symbols about main part of drawing ※

3: cavity 5: control panel

7: control button

Claims (18)

Microwave radiation of microwave ovens and microwave activatable bottom heaters 4 in the form of containers, plates or carriers which serve as separate heating sources for food and on which controllable food is placed via the control unit 15 of the microwave oven. In the method for controlling the process for cooking or heating food in the microwave oven using the source 20, Providing food category information about the food to the oven; Selecting a cooking or heating program separated into one or more time periods (T1, T2, ...) based on the food category information provided; Activating the heating sources at power levels according to the selected program during each time period; Calculating a control variable (c) based on one or more parameters obtained from one or more sensors that repeatedly detect the condition of the food during each time period and the parameter information determined by the food category; After the start of the program, reducing the time periods from the maximum value determined by the food category to zero, and Terminating each time period when time decreases to zero or when the calculated value of the control variable exceeds the value (c1, c2, ...) determined by the food category, and Ending the program when all time periods have ended. The method of claim 1, wherein the microwave oven further comprises a top heater in the form of a grill element or some other equivalent electric IR radiating element as an additional controllable heating source, activating the top heater according to the selected program. Method further comprising a. The method of claim 1, wherein the program is divided into time periods (T1, T2, ... Tn) in which one or more sensing parameters (x1, x2, ..., xk) are sensed during each time period. During each time period for each sensing parameter, the relevant constants a1, a2, ..., an, b1, b2, ..., bn; k1, ..., kn are given as the parameter information. Selecting. 4. A method according to claim 3, wherein during the time period Tn, the control variable (c) is calculated by the following equation c = an.x1 + bn.x2 + ... + kn.xk. 5. The program according to claim 4, wherein the program consists of two time periods (T1, T2), two sensing parameters (X1, X2) are sensed, and during time period T1, c = a1.x1 + b1. calculating the control variable (c) by x2 and during time period T2 by c = a2.x1 + b2.x2. 2. A method according to claim 1, characterized by using the temperature and humidity increase of the vented air from the oven cavity as sensing parameters. The method of claim 1, wherein the temperature of the ventilated air from the oven cavity is used as a sensing parameter, and the calibration is performed on the parameter information by sensing the initial temperature of the ventilated air. The apparatus of claim 1, wherein the micro oven further comprises means for inputting or sensing the weight of food, based on the information about the constant w and the weight of food w determined by the food category. Calculate the predicted duration Tie of each time period Ti (i is a positive integer) of the cooking or heating program by Tie = ki.w, And use the calculated value of the predicted duration of the time period to further monitor the cooking or heating process. A cavity 3, a microwave radiation source 20 for supplying microwaves to the cavity, A microwave activatable bottom heater 4 in the form of a container, plate or carrier on which the food to be heated or cooked is placed, and Control unit 15 for controlling the floor heater as well as the supply of microwaves to the cavity and one or more sensors 23, 24 for sensing and providing to the control unit one or more sensing parameters indicative of the condition of the food. In a microwave oven comprising: Means 12 for providing food category information about food to the control unit, wherein the microprocessor 16 of the control unit comprises one or more time periods T1, T2, based on the provided food category information. Function to select cooking or heating programs separated by ...), Activating the microwave radiation source, ie the bottom heater, at power levels according to the selected program; Repeatedly calculating the control variable C based on parameter values obtained from the one or more sensors and one or more related constants determined by the food category, repeatedly for each time period; After starting the program, reducing the time periods from the maximum value determined by the food category to zero, and A function of terminating each time period when the time period to zero decreases or when the calculated control variable value exceeds a value (C1, C2, ...) determined by the food category; Microwave oven, characterized in that it is programmed to implement a function of terminating the program when all time periods have ended. 10. An exhaust channel according to claim 9, wherein an exhaust channel for ventilating the cavity is provided, and a temperature sensor 24 and a humidity sensor 23 are provided to the exhaust channel for sensing the temperature and humidity of the vented air respectively as the sensing parameter. And wherein the sensors remain activated during the cooking or heating process. The microprocessor 16 of the control unit 15 obtains the temperature value of the vented air from the temperature sensor 24 when the cooking or heating program is started and takes the temperature into account in consideration of the obtained temperature. Microwave oven, characterized in that it is programmed to adjust. 10. The apparatus according to claim 9, wherein the means for providing food category information (12) provides a parameter corresponding to a cooking or heating program stored in the control unit and based on the type of food and the state of the food when the food is put into the oven. Microwave oven, characterized in that adapted to. 10. The apparatus of claim 9, wherein the means for providing food category information (12) comprises a first means for providing food type parameters and a second means for providing food status parameters, the combination of these parameters being the control unit Microwave oven corresponding to a cooking or heating program stored therein. 10. Microwave oven according to claim 9, characterized by a control panel (5) equipped with a display (6) adapted to display designation, symbols or plain text messages indicative of the selected cooking or heating program. 10. The top heater according to claim 9, wherein a top heater is provided in the form of a grill element or some other equivalent electric IR-radiating element controllable via the control unit 15, wherein the top heater is selected in terms of active time and heating effect. Microwave oven, characterized in that applied to be controlled according to the program. 16. The rotating crisp plate (4) of claim 15, consisting of a metal having low calorie value and good thermal conductivity and having a lower portion disposed on the microwave absorbing layer, the grill element being mounted on the ceiling of the oven cavity, the oven Has a supply opening on any level with the crisp plate 4 and is adapted to supply polarized microwaves to the microwave absorbing layer, the E-vector or H-vector of the polarized microwaves being substantially A microwave oven characterized by being directed in the plane of the microwave absorbing layer. 10. The control unit (15) according to claim 9, wherein the control unit (15) is adapted to use the weight (W) of food as an additional control parameter, the information on the weight of the food being arranged adjacent to the container, plate or carrier (4). Weight sensor 25 or means 9 for inputting the measured value of the weight, the control unit being selected based on the constants K1, K2, ... determined by the weight of the food and the food category. Microwave oven, characterized in that it is adapted to calculate the predicted duration of time periods (T1e, T2e, ...). Rotating crisp plates 4 mounted on the oven cavity and grill elements mounted on the ceiling of the cavity and sensors 23 and 24 for sensing substance radiation from the food as well as temperature values indicative of food conditions. How to use the microwave oven provided, A method of using a microwave oven for automatic cooking and heating of food according to pre-programmed cooking or heating programs provided in the oven and selectable based on food category information based on the type of food and its initial state.