JPS61259027A - Automatic high-frequency heater - Google Patents

Abstract

PURPOSE:To permit uniform defrosting cooking to be performed in a short time as well as prevent overheating of an object to be heated by a method in which by using a weight sensor and a cooking sensor, an object to be heated is heated sequentially by means of a controller. CONSTITUTION:A command input through a defrosting cooking key 4 on an operating panel 3 is made out by a controller 5, and defrosting of a frozen food as an object 7 to be heated, put in a heating chamber 6, is started by the controller 5. The heating is controlled by supplying electric power to a magnetron as a high-frequency generator 9 through a driver 8. the weight of the object 7 on a tray 11 is detected by a weight sensor 10. By a cooking sensor 12 consisting of a humidity sensor and a gas sensor, steam and gases to be discharged by a fan 13 are detected to detect the ending time of cooking.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to high-frequency heating devices such as microwave ovens.
The present invention relates to an automatic high-frequency heating device that can be used to defrost and cook frozen foods.

BACKGROUND OF THE INVENTION In general, defrosting of frozen foods by microwave heating is completed in an extremely short time, resulting in good quality after defrosting, and has been widely used in practice. Here, we will talk about the so-called thawing cooking method, which involves heating frozen cooked foods and mixed vegetables after thawing them to raise the temperature of the food.

Conventionally, such thawing cooking methods have been limited to heating with a constant high-frequency output from thawing to cooking. Then, using a cooking sensor such as a humidity sensor or a gas sensor, it detects when the heating of the food is completed and automatically ends the cooking. This thawing cooking method requires less heating time, but on the other hand, cold spots tend to appear in the center of the food, and homogeneity is impaired between areas that start melting earlier and areas that melt slower, resulting in a mushy finish. However, there were problems such as problems such as sagging.

In order to improve the above-mentioned problems, a structure has been proposed in which thawing and cooking are automatically performed sequentially (Japanese Patent Application No. 114970/1982). In this system, the first half of defrosting is controlled by a weight sensor, and the second half of cooking is controlled by a gas sensor, and the defrosting is divided into four small modes to improve the defrosting quality.

Problems to be Solved by the Invention However, in such a thawing cooking method, since the first half of thawing is controlled by a weight sensor, there is a problem that the temperature of the food immediately after thawing tends to vary. This point will be explained in detail. If only the weight of the food can be accurately detected by a weight sensor, the dielectric loss of frozen food is constant regardless of the material, and thawing can be completed successfully.

However, since frozen foods are actually placed in a variety of containers, taring must be performed to detect just the weight of the food. To do this, the empty container must first be placed on the tray, zeroed, or tared, and then the food placed in the container, which is extremely troublesome. Therefore, as shown in Figure 6, the total weight W0
The method of calculating the food weight from the correlation between (the weight of the container and the food) and the food weight W is excellent in terms of operability and is widely used.

Each point in Figure 6 represents the total weight W of various frozen foods placed in various containers. Showing the relationship between and food weight W,
It can be seen that there is a strong correlation between the two. There is a relationship W=0.35W0 between the two that can be approximated by a straight line. Based on this, the decompression time T is 'r1=xw (K: constant)
It is calculated by T1=KXO, 35W.
It can be transformed into 0 and T.

It can be seen that the time can be calculated based on the total weight W0.

However, this method has large variations and wrinkles.
The problem arises when the food weight is small compared to the total weight (W·=0.13W0 in the figure). When using this groove, if the thawing time T is determined using the above method, it will naturally lead to overheating and, in extreme cases, carbonization of the food.

The temperature of frozen foods is also important. If thawing is started in a sufficiently frozen state (-16 to -20°C), the thawing quality will be stable, but if it is already just before thawing (-6~- -3℃), then
Thawing for a certain period of time due to weight causes overheating.

In short, defrosting by weight is a method that predicts the finish of defrosting rather than detecting it, so it cannot defrost successfully unless predetermined initial conditions are met.

The present invention solves these conventional problems, and provides an automatic high-frequency heating device with excellent safety that can prevent overheating while suppressing the temperature difference after heating.

Means for Solving the Problems The automatic high-frequency heating apparatus of the present invention includes a weight sensor and a cooking sensor, and a control section uses both sensors to sequentially heat an object to be heated.

Function: The automatic high-frequency heating device of the present invention first performs thawing using a certain high-frequency output, and then reduces the high-frequency output and performs carryover heating. The time of the above thawing cycle is determined by the weight of the object to be heated, and the object to be heated is effectively thawed in a short time. Furthermore, during the thawing process at the beginning, the food to be heated is also monitored by the cooking sensor, and if the food to be heated reaches a predetermined heating state during this thawing process, even if there is still weight thawing time remaining, the cooking sensor will monitor the heated object. Move on to the next carryover heating.

Next, the high frequency output is increased again, and the food to be heated is automatically heated by the cooking sensor until it reaches a predetermined finished state.

By the above-described sequential heating, uniform thawing and cooking can be performed in a short time, and overheating of the object to be heated can be prevented.

EXAMPLE Hereinafter, an automatic high-frequency heating apparatus according to an example of the present invention will be explained with reference to the drawings.

As shown in FIG. 2, the automatic high-frequency heating device according to the present invention includes a main body 1 containing a heating chamber, a door body 2 that freely opens and closes the opening of the heating chamber, and an operation panel 3 that inputs various commands. It is formed by A thawing/cooking key 4 is arranged on the operation panel 3 for instructing thawing/cooking of frozen food.

FIG. 3 is a block diagram showing one embodiment of such an automatic high-frequency heating device. Commands input from the thawing/cooking key 4 on the operation panel 3 are decoded by the control section 5. Then, the control unit 6 starts defrosting and cooking the frozen food, which is the object to be heated 7 placed in the heating chamber 6 . The heating is controlled by being supplied with power via a driver 8 to a magnetron serving as high frequency generating means 9.

The weight sensor 1o detects the weight of the object to be heated 7 on the mounting plate 11. Further, the cooking sensor 12 is realized by a humidity sensor, a gas sensor, or the like, and reacts to steam or gas discharged by the fan 13 to detect when cooking is completed. Reference numeral 14 represents an exhaust guide, and reference numeral 16 represents a motor that rotates the mounting plate 11 to improve uneven heating.

Note that the weight sensor 1o may employ a capacitance method or a strain gauge method to detect the amount of displacement of the mounting plate 11, or a vibration method to measure the natural frequency.

As the cooking sensor 12, the relative humidity sensor "Humiceram" manufactured by Matsushita Electric Industrial Co., Ltd., the absolute humidity sensor 1 Neo Humiceram manufactured by Matsushita Electric Industrial Co., Ltd., and the gas sensor #81 manufactured by Figaro Corporation are used.
3 etc. can be used.

FIG. 4 is a heating pattern for thawing cooking showing an embodiment of the present invention. Figure 4(a) shows the state of the microwave output, and Figure 4(b) shows the temperature rise of each part of the food being heated.
Figure (a) shows the amount of steam generated from food during heating.

Heating consists of three modes. First, in T1, the microwave is heated at full power, and the time is calculated by 'r, = x1w0 (K1: constant) based on the detected total weight W0. In this T1 mode, the temperature of the frozen food is raised all at once until the surface partially reaches 40 to 60"Q. Figure 1 shows the same temperature as the conventional example shown in Figure 6.
-/ Showing one example・T1 as shown in Figure 4 (b) 1
At the end of the mode, the surface temperature is partially 40-6
Raise the temperature to 0℃. At this time, the internal temperature of the food is still -2 to 3°C, and in this state the mode shifts to T2 mode.

In T2 mode, the microwave power is reduced to around 180 watts and carryover heating is performed.

T2 time is same as T1, T2 = 2W0 (K2: constant)
Calculated by In T2 mode, the temperature difference between the surface and the inside is large, so the temperature moves quickly, and the frozen part inside is completely thawed at the end of T2 mode. T
Although the power in the two modes may be half-stopped, the total heating time can be shortened by setting the power to a low output of about 90 to 250 watts as in this embodiment. With this level of output, there is not enough energy to further advance the boiling process, but it is effective in defrosting the inside (see Figure 4 (bl)).

Now, in this way, the T and T2 modes are time-controlled based on the weight of the frozen food detected by the weight sensor. However, as detailed in the section "Problems to be Solved by the Invention", it is possible that the temperature will already reach a very high temperature in the middle of the T1 mode due to differences in containers and variations in the starting source of the food. To prevent this, monitoring by the cooking sensor is performed during the T1 mode.

FIG. 6 is a flowchart of a control program of a microcomputer, which is a control section, showing such an operation. First, when the input of the defrost cooking key is decoded, the system is initialized. Then, the total weight W0 of the food is measured by the weight sensor, and based on this, T1 time and T time are calculated (at T1-, Wo.

T2=2W0).

Next, when the input of the start key is decoded, power supply to the magnetron is started, and the T1 flag is set to R of the microcontroller.
It is set to a predetermined location within AM. This is the start of T1 mode. Each time the clock is counted, the T1 time is subtracted and full power is maintained until the count up. At this time, the humidity change is also monitored by the cooking sensor, and if the predetermined steam amount Δh increases even during T1 time, T1
The flag is set, the T2 flag is set instead, and the T1 mode ends.

FIG. 1 shows the heating pattern when steam is generated during T1 mode. A comparison with Figure 4 shows that some of the food reached a temperature of about 70°C before T and time had elapsed.
The cooking sensor ends up detecting a certain amount of steam Δh (FIG. 1C). So T1
The mode shifts to the next T2 mode at humidity detection time T1'.

Now, returning to FIG. 6 again, the T2 mode and subsequent modes will be explained. When shifting to T2 mode by resetting the T1 flag and setting the T2 flag, first the T2 time is subtracted, and then power on/off processing is performed to control the microwave intermittently. Specifically, this is done by installing a power duty counter, and setting one period to 16 seconds, for example.
If the on-time is 4 seconds, the average power will be reduced to % of full power. The above processing is continued until the T2 time elapses, and as the T2 time elapses, the T27 lag is reset and the T2 mode ends.

By resetting the T7 lag and the T2 flag, the processing of the 7 icon shifts to the T3 mode, that is, the cooking mode using the cooking sensor. Here, the microwave becomes full power again, and heating continues until a certain humidity increase Δh is detected, and when the humidity is detected, the microwave is turned off, and a buzzer or the like is notified, and the cooking ends.

Note that in the T3 mode, a predetermined additional heat may be applied after detecting the humidity. The additional heat time is calculated by 3T3 (K3=constant).

According to the present invention, it is possible to prevent food from being overheated due to differences in containers or starting temperatures of the food, and to achieve good thawing and cooking.

Effects of the Invention As described above, the automatic high-frequency heating device of the present invention is equipped with a weight sensor and a cooking sensor, and first defrosts the food at high output based on the weight of the food, and then performs carryover heating at low output based on the weight. Then, the cooking sensor heats the food to a predetermined state again at high output, and in the thawing mode at the beginning, the food to be heated is also monitored by the cooking sensor. Once this condition is reached, even if there is time left to defrost the weight, the system will move on to the next carryover heating at that point, allowing for thawing with a small temperature difference without localized boiling or low-temperature areas in the center. Cooking can be realized, and significant overheating during the defrosting mode can be prevented due to variations in estimated food weight due to differences in containers, differences in food starting sources, etc. Conventional defrosting for a fixed period of time based on weight can prevent the carbonization of food that occurs in abnormal situations, and can provide a defrosting cooking method that is excellent in both operability and safety.

[Brief explanation of drawings]

Fig. 1 is a time chart showing the heating pattern of an automatic high-frequency heating device in an embodiment of the present invention, Fig. 2 is a perspective view of the same main body, Fig. 3 is a block diagram showing the same configuration, and Fig. 4 is the same heating pattern. FIG. 6 is a control flowchart of a microcomputer as a control unit, and FIG. 6 is a graph showing the relationship between total weight and food weight. 4... Thawing cooking key, 6... Control unit,
6... Heating chamber, 7... Heated object, 9.
...High frequency generating means, 1o... Weight sensor, 12... Cooking sensor. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure (of) /-m - Main body Figure 4 (Figure 5 Waist)

Claims (1)

[Claims] a heating chamber in which an object to be heated is placed; a high frequency generating means coupled to the heating chamber; a control section controlling power supply to the high frequency generating means; a weight sensor detecting the weight of the object to be heated; The controller includes a cooking sensor that detects the heating state of the object to be heated, and a key that instructs thawing and cooking of frozen food, and when the key is operated, the control unit controls the heating state of the object detected using the weight sensor. The food is thawed using a certain high-frequency output based on the weight of the food, and the cooking sensor monitors whether the food to be heated has reached a predetermined heating state, and whether the defrosting time has elapsed or the food has reached a predetermined heating state. When the state is reached, the heating is carried out at a high frequency output that is lower than the high frequency output, and then the high frequency output is increased, and the cooking sensor is used to bring the object to a predetermined heating state. Automatic high frequency heating device.