JPH02118325A - Microwave oven - Google Patents

Abstract

PURPOSE:To eliminate the foodstuff weight data error due to the turning of the foodstuff tray for highly accurate weight measurement which is used as effective information for cooking control by synchronizing the power source frequency with the start of weight measurement. CONSTITUTION:During the cooking, the foodstuff tray 12 is rotated by a drive means 13 to prevent the uneven heating. The foodstuff weight is measured by a weight measuring device 14. The power source frequency is detected by a clock input means 4. The output signals from the clock input means 4 and the weight measuring device 14 are inputted to a microcomputer 15, which performs the overall cooking control. For the rotation drive means 13, a synchronous motor is used which rotates in proportion to the power source frequency. By detecting the rotational speed of the drive means whose rotational speed is dependent on the power source frequency by the clock input means, and by performing the weight measurement with the weight measurement device synchronously with the rotational speed so as to measure the weight for any desired number of times for each rotation of the foodstuff tray, the error due to the rotation of the foodstuff tray can be significantly reduced, allowing a highly accurate measurement of the weight reduction.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a high-frequency heating device equipped with a weight detection device and using a microcomputer.

Conventional technology Conventionally, high-frequency heating devices equipped with a weight detection device determine the cooking end time based on the initial weight of the food measured at the start of cooking, or determine the finished cooking by detecting a decrease in the weight of the food during cooking. Something has been devised to detect it.

Furthermore, as a boat fishing technique, cooking by rotating the table is widely practiced in order to prevent uneven heating caused by uneven high-frequency distribution due to high-frequency standing waves. but,
The disadvantage is that the detected weight value fluctuates with rotation. This fluctuation in the detected weight value is regarded as unnecessary, and the detected weight value is set in 5-gram increments to suppress the fluctuation in the detected value.

Problems to be Solved by the Invention However, although there have been many attempts to detect cooking completion based on weight loss (Utility Model Application No. 51-83050)
Publication No. 153023/1983, Japanese Patent Application Laid-Open No. 1987-153023
No. 50314, Japanese Utility Model Application No. 60-111404, and Japanese Patent Application Laid-Open No. 62-66025), none of them are applicable to the high-frequency heating device of the rotating food table type that has become mainstream in recent years. This is because the weight detecting section detects the weight of the food via the mounting table, so if the mounting table rotates during cooking, a large detection error will occur. Foods come in various shapes and are not necessarily placed in the center of the mounting table, so detection errors will occur no matter what weight detection device is installed, as long as it is a high-frequency heating device that rotates the mounting table. This was a disadvantage in that it was not possible to utilize cooking finish detection technology based on food weight loss detection.

Furthermore, since there is no means to determine if food is placed in an abnormal state, cooking control is performed using incorrect weight data, resulting in problems such as overcooking.

The present invention solves these conventional problems, and provides a weight detection method that analyzes fluctuations in detected weight values due to rotation of a mounting table as effective information and utilizes it for cooking control. Moreover, the weight detection value, which was conventionally considered unnecessary, is used as effective information to control cooking.

Means for Solving the Problems The high-frequency heating apparatus of the present invention has a clock input means, a measurement start determination means for determining the start of weight measurement, and a measurement time management means for managing the weight determination time. It detects weight loss with high precision. Also,
In addition to importing weight data, the obtained data is used to detect the placement state of food and perform control according to that state.

According to the present invention, the rotation speed of the rotation drive means whose rotation speed is determined by the power frequency is detected by the clock input means, the weight is measured by the weight detection device in synchronization with the rotation speed, and the rotation speed of the rotation drive means is determined by the power frequency. By measuring the weight a number of times, it is possible to significantly reduce the error caused by the rotation of the mounting table, and it is possible to detect the weight ff1N with high accuracy.

In addition, the obtained weight data is used to detect the food placement status, and depending on the content, it is determined that the food has been placed abnormally, and cooking is finished, and the food is determined to be placed inappropriately. This outputs a display indicating the following.

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

FIG. 2(a) is a sectional view of a high frequency heating device according to an embodiment of the present invention. A weight detecting means 14 for measuring weight is provided below the rotary driving means 13 for driving the mount 12.

FIG. 1 is a block diagram of a control circuit according to an embodiment. During cooking, the holder 12 is rotated by the rotation drive means 13 to prevent uneven heating. The food weight is detected by the weight detection device 14. The power supply frequency is detected by the clock input means 4, and the output signals of the clock input means 4 and the weight detection device 14 are input to the microcomputer 15, which performs overall cooking control.

The rotational drive means 13 uses a synchronous motor whose rotational speed is proportional to the power supply frequency, and features include small rotational irregularities and a constant rotational speed regardless of the size of the load. The rotation speed of the rotor is generally expressed by the following formula.

(Rotation speed) = 120x f/pf is the power supply frequency p is the number of poles.

Furthermore, the rotation speed of the motor output shaft can be determined by multiplying the rotor rotation speed by the reduction ratio provided by the gear. Therefore, the rotation speed of the mounting table 12 can be known by detecting the power frequency.

In order to synchronize the cycle of weight detection and the rotation cycle of the mounting table, the clock pulse signal from the clock input means 4 is counted by the measurement start determination means 5.

Then, weight measurement is started based on the output from the measurement start determination means 5. The weight measurement time is determined by microcomputer 1.
The measurement time is determined by counting the number of interruptions by the measurement time management means using the internal interrupt time of No. 5. Here, if n-port weight measurement is performed during one rotation of the mounting table, the number of clock pulses counted by the measurement start determining means 5 is expressed by the following equation.

(Number of clock pulses)=tXf/nt where the time f required for one rotation of the mounting table is the power supply frequency.

The signal from the measurement start determining means 5 indicates that the clock pulse is
Output every 1 x f/n times. The measurement time is
By making it sufficiently shorter than t/n, even if the power supply frequency fluctuates, it is possible to suppress the deviation of the measurement start point due to the rotation of the mounting table 12, and it is possible to cancel errors caused by rotation. . Then, if we average the weight data for each rotation and take the difference from the data for the next rotation, we get
Changes in weight can be detected.

Furthermore, weight data is captured using the above method, and the placement state of the food is detected using the data. Since the weight detection means 14 detects the weight of the food via the mounting table 12, when the mounting table 12 rotates during cooking, if the weight measurement starting point changes, the detected weight value also changes. In other words, it can be seen that there is a range in the detected weight values. The range of this detected weight value is used to detect abnormal food placement conditions. For example, when food is placed on the edge of the mounting table 12 or when a large volume of food is placed, the food comes into contact with the wall surface of the heating chamber 18, making it impossible to accurately detect the weight. In this case, since the width of the detected weight value shows an abnormal value, the present invention determines that the loading position is abnormal as shown in Fig. 2, and finishes cooking and confirms that the loading position is abnormal. A display indicating this is output to the display unit 8.

FIG. 3 is a flowchart of the internal interrupt processing of the microcomputer. In Pl, it is determined whether the weight measurement has been completed, and if YES, the process advances to P6, and if NO, the process advances to P2. At P2, the output signal from the weight detection device 14 is taken in, and at P3, the measurement time counter is turned down. P4
Now, as a result of P3, determine whether a certain time has been reached.
If Yes, proceed to P14; if NO, proceed to P5. In P5, it is determined whether the start of weight measurement is permitted, and Ye
If it is s, proceed to the next step, and if it is No, proceed to P6. P6 takes in the power supply clock pulse, and Pl outputs it.

It is determined whether there is a signal from the W level to the Hi level. If Yes, proceed to P8; if No, proceed to the next step.

At P8, the measurement start determination counter is down, and at P9, it is determined whether the counter has become zero as a result of P8. If YES, proceed to PIO, and if NO, proceed to the next step. pto
Then, it is determined that measurement start is permitted. In Pll, judge whether weight measurement is completed or not, if Yes, go to Pl2, NO
If so, move on. At P12, a measurement time counter is initialized to start a new weight measurement, and similarly at P13, a measurement start determination counter is initialized to start counting clock pulses. At Pl4, since the weight measurement time counter has become zero, it is determined that the weight measurement has ended. Then, in P15, it is determined whether the start of weight measurement is permitted, and if Yes, the process advances to P12 to initialize the counter, and if No, the process advances to P6.

FIG. 4 is a flowchart for determining the placement state. Pl
In step 6, it is determined whether the placement state determination has been completed,
If Yes, proceed to the next step; if No, proceed to PIT; in Pl7, it is determined whether the weight measurement has been completed; if Yes, proceed to P1B; if No, proceed to the next step.

In Pl8, it is determined whether the current weight detection data is larger than the maximum value of the weight detection data taken in the past, and if Yes, go to Pl9, N.

If so, proceed to P24. In P2O, since the current weight detection data is the maximum value, it is saved as the maximum data. P2
4, determine whether the current weight detection data is smaller than the minimum value of the past weight detection data, and if Yes, P
If no, proceed to P2O.

In P25, since the current weight detection data is the minimum value, it is saved as the minimum data. In P2O, it is determined whether one rotation, which is the placement state determination period, has been completed.
If Yes, proceed to P21; if No, proceed to the next step. In P21,
The detection width is calculated by taking the difference between the maximum data and minimum data for one revolution of the weight detection value.

In P22, it is determined whether the detection width calculated in P2O is larger than the abnormal value that determines that the placement state is abnormal, and Yes.
If so, go to P26; if No, go to the next step. At P26, the cooking is terminated because the placement state is abnormal. In P27, an abnormal state is displayed.

Effects of the Invention As described above, in the high-frequency heating device of the present invention, by synchronizing the power supply frequency and the start of weight measurement, errors in weight data due to rotation of the mounting table are eliminated, and weight detection can be performed with high precision. Even when the power supply frequency fluctuates, its accuracy is unparalleled and is extremely effective in practice.

Furthermore, in the high-frequency heating device of the present invention, it is possible to synchronize the power supply frequency and the start of weight measurement, and to use the fluctuation of the detected weight value due to the rotation of the mounting table to determine an abnormal loading state. In some cases, by displaying information after cooking has finished, it is possible to convey information to the user, prompting the user to cook in a normal state, and preventing failures such as overcooking due to cooking control using incorrect data. can. This is extremely effective in practice.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a high-frequency heating device according to an embodiment of the present invention, FIG. 2 (al), (b) is the same configuration diagram, FIG. 1 is a flowchart for determining the placement state. 1-2...Input means, 3...Cooking start instruction means, 4...Clock input means, 5...
... Measurement start determination means, 6 ... Measurement time management means, 7 ... Control means, 8 ... Display unit, 9 ... Load control means , 1o... Heating means, 11... Heating object, 12... Placement table, 13... Rotation drive means, 14...
Weight detection means, 15...Microcomputer, 16...Cooking setting means. Name of agent: Patent attorney Shigetaka Awano Haga 1/2 /J (4 Fig.

Claims (3)

[Claims] (1) Input means consisting of a cooking key for setting cooking and numeric keys for setting cooking time and clock, and cooking for selecting and selecting a plurality of predetermined cooking modes using the output signal from the input means as input. A setting means, a cooking start instruction means for instructing the start of cooking, a clock input means for inputting a power supply frequency, a mounting table for placing food, a rotation driving means for rotationally driving the said placing table, and said placing table. a weight detection means for measuring the weight of the above food; a measurement start determination means for determining the start of weight measurement by inputting the output from the clock input means; and a measurement time management means for managing the time for weight measurement; Providing a heating means for heating the food and a load control means for controlling the heating means,
A high-frequency heating device comprising a control means that receives outputs from the cooking setting means, cooking start instruction means, clock input means, weight detection means, and measurement start determination means and sends a signal to the load control means. (2) The rotational drive means is configured to rotate in synchronization with the power supply frequency, and the rotational speed of the rotational drive means and the measurement start determination means are synchronized by the output from the clock input means. (1) The high frequency heating device described. (3) After the start of cooking, data from the weight detection device is captured in multiple pieces per rotation of the mounting table, and if the data is analyzed and it is determined that there is an abnormality in the mounting state, cooking is finished and the display screen 3. The high-frequency heating device according to claim 2, wherein the high-frequency heating device is configured to output a display indicating that there is an abnormality.