JPH02263016A - Heating cooking device - Google Patents

Abstract

PURPOSE:To make automatic cookery possible in a wide range by allowing the device to detect that reflected visible radiation intensity from a material to be heated is lowered down to a predetermined rate from a maximum value for deciding an optimum cooking finish. CONSTITUTION:When a visible radiation from a light source is irradiated on the surface of heated foods, reflected visible radiation intensity reflected from the food surface is increased to reach LX at the time when food surface temperature is increased to allow oils and fats to flow out from the inside of the foods so as to increase the glossiness of the food surface. In addition, when heating exceeds a time T5 for cooking the foods, the intensity thereof reaches LM to lower the reflected visible radiation intensity from lowering of a reflection factor due to the generation of scorching so as to reach LE from LM. A stage for equalizing the surface temperature of the foods before the production of the scorching, namely, the reflected visible radiation intensity is found at the time t4 or t5 to make it a reference value to measure the maximum value LM of the reflected visible radiation intensity on and after the setting of the reference value so as to judge a cooking finish by means of the scorching as proper scorching if the level of the reflected visible radiation intensity is lowered down to a specified rate predetermined at every cooked food for the maximum value.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a cooking device that heats an object to be heated until browned, and in particular, to control the surface temperature of the object during heating and the amount of visible light reflected from the surface. The present invention relates to a heating cooking device equipped with a browning detection mechanism that detects the intensity and detects the finish of browning.

2. Description of the Related Art Conventionally, as a heating cooking apparatus having a cooking completion determination means for heating an object to be heated stored in a heating chamber and automatically cooking the food, there is a heating device that automatically cooks the food stored in the heating chamber. A method of measuring the temperature of the air in the heating room rising at the exhaust port, indirectly detecting the temperature of the food to be heated from the exhaust temperature, and controlling the heating when the detected value reaches a preset value; A method of controlling heating by detecting changes in various physical quantities associated with heating of a heated object, such as changes in the humidity of air exhausted from a heating chamber and the concentration of gas;
Furthermore, there is a method that uses an infrared detector to measure the infrared energy emitted from the food as it is heated, and then controls the heating by detecting the surface temperature of the food based on the measured value.

However, although heating cooking devices using such conventional methods can detect finished states such as ``thawing'' and ``warming'' of food, there is a problem in that it is not possible to detect browning caused by heating and control the optimal browning. Ta.

On the other hand, in order to eliminate the drawbacks of the conventional techniques, a heating cooking device has been proposed that detects the browning of the object to be heated and automatically controls the heating.

The principle is described, for example, in Japanese Patent Application Laid-Open No. 55-95037, in which food, which is an object to be heated in a heating chamber, is illuminated with visible light from a light source installed outside the heating chamber. Heating is controlled by measuring changes in the intensity of reflected visible light.

This method is not affected by the shape or quantity of food.
It is also a convenient method because there is no need to set a heating time.

Problems to be Solved by the Invention However, in this prior art, the intensity of reflected visible light reflected from the surface of the object to be heated reaches a certain value that is corrected according to the color and degree of burntness of the object at the initial stage of heating. When this happens, the heating of the object to be heated is stopped or the degree and form of heating is changed, so the state change before the object actually burns, i.e. expansion, deformation, water vapor generation, etc. during the transient stage of heating, There was a problem in that the intensity of reflected visible light fluctuated due to dryness of the surface, reducing the accuracy of detecting browned marks.

Therefore, it has been desired to develop a heating cooking device that combines a means for detecting the temperature of an object to be heated and a means for detecting brownedness.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a heating cooking device that has high detection accuracy and is capable of automatic cooking over a wide range.

Means for Solving the Problems The present invention has been made to solve the above-mentioned problems, and includes a first thermal energy source comprising a heating chamber for storing an object to be heated and a high-frequency oscillator for heating the object to be heated. In a heating cooking apparatus comprising a generating means, a second thermal energy generating means consisting of a gas or electric heater that heats an object to be heated until browned, and a light source that irradiates visible light to an object to be heated, during cooking. A temperature detection means that non-contact detects the surface temperature of the object to be heated, an opening provided on the wall of the heating chamber for receiving optical energy, and a detection means for detecting the intensity of reflected visible light from the object provided near the opening. reflected visible light intensity detection means;
a finish determining means for determining the cooking finish due to browning of the heated object by means of storing and calculating detection signals from the temperature detecting means and the reflected visible light intensity detecting means; and first and second thermal energy generating means. The reflected visible light intensity detecting means starts detecting the reflected visible light intensity based on the temperature detection signal and continues or stops the operation of the first thermal energy generating means. The maximum value of the visible light intensity is stored, and the optimum cooking finish is determined by detecting that the reflected visible light intensity has decreased by a predetermined percentage from the maximum value.

Operation In the present invention, the object to be heated is heated, and the occurrence and progress of browning is detected by a reflected visible light intensity detection means,
When determining the finish of browned cooking, the surface temperature of the object to be heated is detected by a temperature detection means, and the finish is determined based on the detection result of the surface temperature. Therefore, it is possible to prevent variations in finish determination and a decrease in finish detection accuracy due to fluctuations in reflected visible light intensity before browning of the heated object occurs. That is, when heating an object, its surface temperature is measured by a non-contact sensor, such as a pyroelectric infrared detector, and the surface temperature of the object is measured by a non-contact sensor such as a pyroelectric infrared detector. Visible light reflected from the surface of a heated object is scattered,
Once the temperature has passed the stage where it fluctuates abnormally and reaches a point where it starts to burn, the reflected visible light intensity of the object to be heated is measured. Then, the object to be heated continues to be heated, the maximum value of the reflected visible light intensity during heating is measured and memorized, and when the reflected visible light intensity decreases from the maximum value to a preset predetermined ratio, browning is done. The finish is complete. Therefore, since the intensity of reflected visible light is always detected after the heated object reaches a predetermined temperature, errors in determining the cooking finish due to fluctuations in the intensity of reflected visible light at the initial stage of heating are eliminated, and the reliability of browning detection performance is increased. Improved accuracy and reliable automatic cooking can be achieved.

Example An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of a heating cooking device according to the present invention.

In the figure, 1 is a heating chamber made of metal, 2 is an object to be heated such as food for cooking, which is placed on a turntable 3, and is connected to a motor for rotating the turntable via a placing table 4 and a rotating shaft 5. It has a structure in which the object to be heated 2 is uniformly heated by the rotation of 6.

Reference numerals 7a and 7b designate electric heaters as second thermal energy generating means for raising the air temperature in the heating chamber and browning the surface of the object to be heated 2. Reference numeral 8 denotes a high-frequency oscillator for continuously or intermittently high-frequency heating the object 2 to be heated as a first thermal energy generating means. The object to be heated 2 is heated. Side wall surface 11 of heating chamber 1
A light source 12 for irradiating visible light onto the object to be heated 2 is arranged, and the visible light is irradiated through a light-transmitting opening 13 . 14 is a light receiving opening for receiving reflected visible light from the object to be heated 2 provided on the same wall surface of the heating chamber where the light source 12 is provided. The reflected visible light from the object to be heated 2 passes through the light-receiving opening 14 and is received by the photoconductive rod 15 as a detection means, and is transmitted to the light-receiving element 23 as a means for detecting the intensity of reflected visible light through an optical fiber 22 as described later. communicated. On the other hand, above the heating chamber 1, a surface temperature detection means 19 composed of an infrared temperature sensor 16, a chopper 17, and a chimippa rotation motor 18 is arranged. The infrared temperature sensor 16 is installed with its detection surface facing downward.
It is configured to detect infrared energy emitted from an object to be heated 2 placed on a turntable 3 through a small hole 21 formed in a ceiling surface 20 of a heating chamber 1 .

The reflected visible light from the object to be heated 2 is received by the light-receiving opening 14 and the photoconductive rod 15, and then transmitted to the light-receiving element 23 installed in the low-temperature part via the optical fiber 22. The output of the light receiving element is amplified by an amplifier 24, and transmitted as a digital signal by an A/D converter 25 to determination means (hereinafter referred to as a microcomputer) 26 consisting of a microcomputer.

On the other hand, the infrared rays generated from the object to be heated 2 are chopped by the chopper 17 and input to the infrared sensor 16. The infrared sensor 16 outputs a voltage corresponding to the difference between the temperature of the chopper 17 and the temperature of the object to be heated 2. A chopper temperature detection means (not shown) is provided near the chopper 17, and based on the output of the chopper temperature detection means, an analog signal corrected for the differential voltage output from the infrared temperature sensor is sent to the temperature detection circuit 27. send.

The temperature detection signal from the temperature detection circuit 27 is converted into a digital signal by the A/D converter 28 and sent to the microcomputer 26. 29 is a power source as an electric energy supply means; 30
31 is a cooking product selection switch for the user to select a cooking product during cooking, and 31 is a timer section for measuring time, for example, sending a timer signal to the microcomputer 26. 32, the turntable rotation motor 6, electric heaters 7a, 7b, high frequency oscillator 8, and light source 12 are controlled by the microcomputer 26.
, a control means for controlling the chopper rotation motor 18 and the like.

1. Next, in the above configuration, the object to be heated 2 is heated by the high frequency oscillator 8 which is the first thermal energy generating means, and the electric heater 7 which is the second thermal energy generating means.
The temperature rise characteristics of the heated object 2 and the state of change in the intensity of reflected visible light will be described in the case of heating by a and 7b.

FIG. 2 is a characteristic diagram showing the results of measuring the surface temperature of the food by the above-mentioned surface temperature detecting means 19 when a frozen food as the object to be heated 2 is continuously heated from thawing to browning. In this figure, 33 is a temperature characteristic curve. Heating start time t. Temperature T of the heated object at . indicates the temperature of the heated object in a frozen state. Time t. From to t□ is the initial stage of freezing food by high-frequency heating, and the surface temperature of the food to be heated gradually rises until the temperature T□, which is approximately ○
The state 33a of .degree. C. continues, and thawing progresses. When time t2 is reached and temperature T reaches T2, thawing ends.

The temperature raising stage 33b from time t2 to t3 is a "warming" stage by high-frequency heating, and T3 is the food surface temperature at the finishing stage of "warming". In particular, for foods that do not require browning, that is, foods that are subject to ``thawing'' or ``warming,'' the end of cooking can be detected by detecting T2 or T3. The high-frequency heating ends by time t3, and thereafter the heating shifts to the electric heater (temporary temperature fluctuations accompanying the shift are omitted in the figure).

The temperature increase by the electric heaters 7a and 7b from time t3 starts from temperature T3 and then maintains an equilibrium state at time t4 and temperature T4. 33c shows the equilibrium part of the food surface temperature. The reason why the food surface temperature maintains almost equilibrium between time t4 and t5 and temperature T4 and T5 is because the latent heat of evaporation accompanying the evaporation of water from the food surface causes the heat given from the electric heater to lower the temperature of the food. This is because it does not appear as This phenomenon of temperature equilibrium is remarkable in fish that have a high water content.

This equilibrium phenomenon changes from time t5 when the food surface begins to dry, and the food surface temperature also rises rapidly from T5, reaching temperature TG at time t6 with the temperature increase characteristic shown in 33d. As the temperature rises between T5 and t6, the occurrence and progression of scorching of the food begins, and an appropriately browned food is obtained at the temperature T6 for a time of t.

In other words, if the heating is controlled by determining the degree of browning between the food surface temperature T5 and TG, it is possible to automatically control the finish of food cooking with a desired brown color (the food surface temperature at the time of control is T6). ).

Next, a case will be described in which the surface temperature of the food is detected by the surface temperature detection means 19 when only the electric heaters 7a and 7b are used to heat foods that do not require high-frequency heating, such as food such as cookies. Figure 3 shows the characteristic diagram in this case.
The same parts as in Figure 2 are shown with the same symbols. In the figure, 3
4 is a temperature characteristic curve showing changes in the food surface temperature detected by the surface temperature detection means 19. At the heating start time t2', the food surface temperature, which is room temperature, is T2'. When heating by the electric heater is carried out from time t2' to t4'', the food surface temperature reaches T4' from T2' and shows a temperature rise (after T5') similar to the case in Fig. 2, and the food surface temperature TG Heating ends at '.The food surface temperature reaches T5'.
Burning progresses from to T6', and a suitably browned food is obtained at T6'.

FIG. 4 shows a case where the food surface temperature is detected by the surface temperature detection means 19 when the inside of the food is sufficiently heated in advance by high-frequency heating and then transferred to electric heater heating, such as when cooking large foods. It is a characteristic diagram. In the figure, 35 is a temperature characteristic curve showing changes in the food surface temperature detected by the surface temperature detection means 19, in which time tQI+ to 5'' is high-frequency heating, and time t, 11 to t6'' is heating by the electric heater. Heating start time t. 1 in ″
The food surface temperature is To$1, indicating a frozen state. Time t due to high frequency heating. ~t1″′ is the initial stage of thawing, t□
″~t2″ is a thawing stage, and after this stage, time t4″′
reach.

During this time, the food surface temperature was T. The temperature is increased from ``T'' to T2'' to T4''. When high-frequency heating is continued, moisture from inside the food flows out or bumps onto the surface of the food, and water vapor flows into the infrared energy receiving path. As a result, the measured food surface temperature fluctuates greatly. 35a is in this state.

Thereafter, the food surface temperature gradually reaches an equilibrium state.

The surface temperature at this time is about 110 to 120°C. This pulsation stabilizes as moisture decreases and dries, and from time t,'' the food surface temperature gradually increases, and at time t6''.
The surface temperature reaches T6'' at this time t5'''
At ~t6'', scorching occurs on the surface of the food, and at t6'' the cooking ends with just the right amount of browning.

In this way, the change pattern of the food surface temperature detected by the surface temperature detection means 19 exhibits an equilibrium state due to the latent heat of moisture evaporation released by the food, which is the object to be heated 2, so that when this equilibrium state ends, the temperature starts to rise again. By capturing the point in time when You can determine the temperature at which food starts to burn. but,
Since this change pattern alone cannot determine the degree of burntness or control to automatically stop heating when the right degree of burntness is reached, it is necessary to use a finish determining means 26 that detects the degree of burntness.

Next, a description will be given of changes in visible light reflected from the food surface corresponding to changes in the food surface temperature during the above-mentioned cooking.

FIG. 5 is a characteristic diagram showing changes in visible light reflected on the food surface corresponding to changes in the food surface temperature shown in FIG. In the figure, numeral 36 is a characteristic curve showing changes in the intensity of visible light reflected on the food surface. When the surface of the food to be heated is irradiated with visible light from a light source, the intensity of the reflected visible light reflected from the food surface is Ls in the initial state before heating the food, and the time t for heating and thawing the food. -t2, it decreases slightly due to the removal of frost from the surface, reaching Lr and Lu. This state is the initial stage of heating by the electric heater (time t
, ~t4). Until this time t4, there is no decrease in the reflected visible light because it is the stage before the occurrence of brown marks. Then, after time t4 to t5, that is, the stage when the food surface temperature is almost in equilibrium, the food surface becomes dry and tightened, the food surface temperature rises, oil and fats flow out from inside the food to the surface, and the food surface becomes glossier. It's coming. As a result, the intensity of visible light reflected from the food surface increases, reaching Lx. Furthermore, when heating is performed beyond time t, the reflected visible light intensity increases and reaches the maximum value LM, but this time the reflected visible light intensity also decreases due to a decrease in reflectance due to the occurrence of browned marks. L
M mustard E! leading to. There, the stage of equilibration of the food surface temperature before browning occurs, that is, the time t4 or t.
The reflected visible light intensity in step 5 is determined and set as a reference value, and the reflected visible light intensity maximum value LM after this reference value is measured.Meanwhile, the reflected visible light intensity is increased to a predetermined percentage of this maximum value for each cooked product. When the intensity level decreases, it is determined that the cooking has been completed due to the browning, indicating that the cooking has reached just the right degree of browning. That is, in the characteristic curve 36 of FIG.
The reflected visible light intensity decreases from the maximum value Lu as scorching occurs and progresses, and when it reaches La, which is a predetermined percentage (e.g. 80%) of Ly, the heating source is controlled and the cooking process begins. is completed. In this manner, browning cooking can be automatically performed by setting a just preferable reduction rate of reflected visible light at the time of browning with respect to the maximum value LM. Note that the equilibration of the food surface temperature is determined from the temperature increase rate.

FIG. 6 is a characteristic diagram showing changes in reflected visible light intensity when kutsky is browned and cooked using an electric heater. This corresponds to the characteristic diagram illustrating changes in food surface temperature in FIG. 3. In the figure, numeral 37 is a characteristic curve showing changes in the intensity of visible light reflected from the food surface. When the surface of the food to be heated is irradiated with uniform light from a light source, the intensity of reflected visible light reflected from the food surface is L^ in the initial state before the food is heated. When heating is started, the surface condition or shape changes due to elution of butter or the like on the food surface and expansion of the food itself, so the characteristic curve 37 of reflected visible light intensity increases and reaches the maximum value LM. This change occurs during the heating time t, l~3'' and the temperature equilibrium time t31-t5. LB, LC are the reflected visible light intensities at times t3' and t5.Heating is continued further. Then, the temperature of the food rises rapidly, and the intensity of reflected visible light increases accordingly, reaching the maximum value LM.When browning occurs, the reflectance decreases and the intensity of reflected visible light also decreases.Furthermore, heating continues. When the reflected visible light intensity decreases from the maximum value LM to a predetermined preferred rate of browning, it is assumed that just the right amount of browning has been obtained, and the browning cooking ends.In FIG. The level KE of the reflected visible light intensity that has decreased to a certain percentage is the end point of cooking.

In this way, depending on the object to be heated, the change pattern of reflected visible light intensity used to judge the finish due to burntness differs, but in any case, the temperature rises again after the temperature rise rate during the heating stage of the food reaches equilibrium. The maximum value of the reflected visible light intensity is calculated based on the time point, and when the reflected visible light intensity decreases to the set value that is set in advance for each item to be cooked, the browning process is considered complete. The negative effects of fluctuations in the amount of reflected visible light, such as expansion, contraction, and deformation of the food, scattering of reflected visible light due to water vapor generation, and changes in the gloss of the food surface, on the browning detection accuracy are eliminated, and the browning detection accuracy is improved.

Next, FIG. 7 shows a flowchart of the microcomputer control software in the heating cooking apparatus of this embodiment, and FIG. 8 shows an example of a time chart when controlling the heating cooking apparatus. In Fig. 7, the browning is determined by L E / L u (this ratio is Pt
, is abbreviated as . After setting Pt in advance, the reflected visible light intensity from the food is measured and stored in the microcomputer.Then, the measured value is compared with the initial value to find the maximum value Lu, and the reflected visible light intensity is measured and stored in the microcomputer. If the rate of change in visible light intensity is at a predetermined PL value, heating is controlled by controlling the electric power of the electric heater.

Note that the timing to start measuring brownedness is focused on the point at which the food surface temperature reaches an equilibrium state during heating. This equilibrium state is determined by measuring the rate of temperature rise from the temperature rise within a unit time and also using the measured value of the food surface temperature.
This is carried out when the rate of temperature increase after the temperature exceeds 0° C.) slows down and an equilibrium state is reached. The measurement of browning starts when the temperature increase slows down and reaches an equilibrium state, or when the temperature starts to rise again from the equilibrium state. In addition, when the change pattern of the food temperature and reflected visible light intensity is stable, such as when cooking a specific food repeatedly using the menu keys, the measured value of the food temperature may exceed the equilibrium state. Measurement of reflected visible light starts from the moment the temperature reaches a predetermined temperature.

The second thermal energy generating means in the embodiment of the present invention is an electric heater, and in addition to continuous operation, this electric heater may be operated intermittently, or the electric heater may be installed vertically in the heating chamber. In some cases, heating control operations may be added depending on the food, such as alternating operation. In this case, the food surface temperature may vary depending on the operation of the electric heater.

However, it is common to heat continuously until the stage where browned marks occur, and if the method starts measuring reflected visible light when a predetermined temperature is reached, there will be no problem in determining browned marks.

Effects of the Invention As described above, according to the present invention, there is provided a surface temperature detection means for detecting the surface temperature of food, which is an object to be heated, placed in a heating chamber, and a change in the intensity of reflected visible light from the object to be heated. A browning determination means is provided to measure the browning of the food and determine the browning of the food.
Since browning is determined based on information on the surface temperature of the food, the accuracy and performance of browning detection is improved without being affected by changes in the shape of the food or water vapor before browning occurs. It has the advantage of being able to automate, expand the cooking repertoire, and provide an easy-to-use heating cooking device as it can perform everything from thawing to ``warming'' and ``browning'' frozen foods. .

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a heating cooking device equipped with a browning detection mechanism showing an embodiment of the present invention, Figs. 2 to 6 are characteristic diagrams for explaining the present invention, and Fig. 7 shows a control operation. A flowchart for explanation and FIG. 8 is a time chart during control. DESCRIPTION OF SYMBOLS 1... Heating chamber, 2... Heated object, 7a... Electric heater, 8... High frequency oscillator, 12... Light source, 14...
...Light receiving opening, 19...Surface temperature detection means, 23
...Reflected visible light intensity detection means (light receiving element), 26...
- Finishing judgment means (microcomputer), 32... control means.

Claims (5)

[Claims] (1) a heating chamber (1) for storing an object to be heated (2); a first heating chamber for high-frequency heating the object to be heated in the heating chamber;
a second thermal energy generating means (7a) consisting of a gas heater or an electric heater that heats the object to be heated until browned; A surface temperature detection means (19) for detecting, a light source (12) for irradiating visible light onto the object to be heated, and a light receiving opening (19) for receiving light reflected from the surface of the object to be heated. 14), a reflected visible light intensity detection means (23) for detecting the intensity of the reflected visible light from the object to be heated that has passed through the opening, and a signal detected by the reflected visible light intensity detection means. A finish determining means (26) for storing and calculating the signal of the surface temperature detecting means and determining the finished cooking of the object to be heated based on the result of the calculation; A heating cooker comprising: a control means (32) for controlling the operation of each of the first and second thermal energy generating means based on the determination of the above. (2) The finish determining means (26) detects the reflected visible light intensity from the time when the surface temperature of the heated object detected by the surface temperature detecting means (19) reaches a predetermined temperature. Monitoring of the signal detected by the means (23) is started, and the maximum value of the detected signal is stored, and the intensity of the reflected visible light, which decreases as heating progresses, is set in advance with respect to the stored maximum value. When the set predetermined ratio is reached, it is determined that the object to be heated has been finished, and based on this determination, the control means is driven to control the first
The heating cooking apparatus according to claim 1, wherein the heating and cooking apparatus controls the operation of each of the second and second thermal energy generating means. (3) The finish determining means detects the reflected visible light from the time when the rate of increase in the surface temperature of the heated object detected by the surface temperature detecting means (19) becomes equal to or less than a predetermined value. Monitoring of the signal detected by the intensity detecting means (23) is started, and the maximum value of the detected signal is stored, and the reflected visible light intensity, which decreases as heating progresses, becomes smaller than the stored maximum value. When a preset predetermined ratio is reached, it is determined that the object to be heated is finished, and based on this determination, the control means is driven to control the operation of each of the first and second thermal energy generation means. 2. The heating cooking device according to claim 1, wherein the heating cooking device is characterized in that: (4) The finish determining means detects the reflected visible light intensity from the time when the surface temperature of the heated object detected by the surface temperature detecting means (19) reaches a predetermined temperature. (23) starts monitoring the detected signal, stops the operation of the first thermal energy generating means, and stores the maximum value of the detection signal that started the monitoring, and then decreases as heating progresses; When the intensity of the reflected visible light reaches a preset predetermined ratio with respect to the stored maximum value, it is determined that finishing of the heated object is completed, and based on this determination, the control means is driven. 2. The heating cooking apparatus according to claim 1, wherein the operation of the second thermal energy generating means is stopped. (5) The finish determining means (23) starts the reflection from the time when the rate of increase in the surface temperature of the heated object detected by the surface temperature detecting means (19) becomes equal to or less than a predetermined value. Start monitoring the signal detected by the visible light intensity detection means (23), stop the operation of the first thermal energy generation means, store the maximum value of the detection signal that started monitoring, and then proceed with heating. When the intensity of the reflected visible light, which decreases as the intensity of the reflected visible light decreases, reaches a predetermined ratio set in advance with respect to the stored maximum value, it is determined that finishing of the object to be heated is completed, and based on this determination, the control means is controlled. 2. The heating cooking device according to claim 1, wherein the heating cooking device is driven to stop the operation of the second thermal energy generating means.