JPH0158420B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a high-frequency heating device that can measure the weight of an object to be heated and automatically calculate heating time, output, pattern, etc. according to the weight. be.

Configuration of conventional examples and their problems In conventional high-frequency heating devices, the weight of the object to be heated is measured using a scale, etc., and the heating time and heating output are set based on the weight using a rotary timer or output setting key. Was. Therefore, cumbersome operations such as measurement, timer setting, and heating output setting are required before starting cooking, and improvements in usability have been desired.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional problems, and aims to improve usability by automatically weighing objects to be heated and automatically heating them.

Structure of the Invention In order to achieve the above object, the present invention has a structure including a heating chamber that houses an object to be heated, a high frequency oscillator that supplies high frequency energy to the inside of the heating chamber, and a frequency oscillator whose frequency is increased depending on the weight of the object to be heated. It is equipped with a mounting table having a spring that changes, and a circuit that magnetically transmits the vibration frequency of the mounting table to the outside of the heating chamber to calculate the weight of the object to be heated from the vibration frequency. A circuit is provided to control the output and oscillation time of the high-frequency oscillator, which simplifies the operation of the high-frequency heating device and improves its usability, and also includes a device for measuring the weight of the object to be heated inside the heating chamber. This eliminates measuring work before cooking and enables efficient cooking.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described based on the drawings.

FIG. 1 shows a perspective view of a microwave oven, which is a high-frequency heating device.

1 is a display section that displays the weight of the object to be heated and the heating time; 2 is a setting section that has various keys for selecting the type of cooking, heating output, and starting cooking. 3 is a door that can be opened and closed for taking food in and out of the heating chamber 5, and 4 is a main body.

In FIG. 2, 6 is a magnetron that supplies high frequency waves to the heating chamber 5, and 7 is food as an object to be heated. Reference numeral 8 denotes a mounting table which is a part of a rotatable table on which food can be placed and which vibrates at a frequency corresponding to the weight of the food 7 and uses magnetism to transfer the vibrations to the outside of the heating chamber. Communicate to. 11
is a magnetic field strength detection unit such as a Hall element that detects transmitted vibrations. Reference numerals 9 and 15 apply magnetic force to rotate the mounting table 8, and 9 is a rotary plate, and 15 is a magnet for transmitting the rotational force.

Figure 3 shows the structure of the stand and the vibration frequency detection section. Further, FIG. 4 shows the configuration of the stand in detail.

Reference numeral 8 designates a table for placing the food, 13 designates wheels for rotating and heating the food 7 in order to eliminate uneven heating of the food, and 19 designates an axis of the wheel 13 and a connection for arranging the wheel 13 in a circular manner. It's a ring. Reference numeral 18 denotes a support rotary table that rests on wheels and rotates. Reference numeral 12 denotes a leaf spring, which is fixed in parallel by block material 17. 16 is a leaf spring 12
It is a spring fixing material for fixing the block material 17 and is secured with screws. Reference numeral 20 denotes a mounting base mounting member for fixing the leaf spring 12 and attaching one end of the leaf spring to the mounting base 8. 10 is a magnet which vibrates in the same way as the plate spring 12 vibrates. The magnet is also covered with a material that blocks high frequencies and allows magnetic fields to pass through. Reference numeral 11 denotes a magnetic field strength detection unit that detects the strength of the magnetic field from the magnet 10. When the magnet 10 vibrates, the magnetic field strength detection unit 11 and the magnet 10
By changing the distance from the magnetic field, the magnetic field strength changes and the vibration frequency can be detected. This magnetic field strength detection element includes a Hall element and the like. 14 and 15 are magnets, and by rotating the rotary plate 9 outside the heating chamber, this force is transmitted to the supporting rotary table 18 using the attractive force or repulsive force of the magnets 14 and 15. and food 7 also rotate.

FIG. 5 shows the relationship between the magnet 10 and the magnetic field strength detecting section 11, in which a Hall element is used to detect changes in the magnetic field strength. In the Hall element, as shown in b, the voltage generated between AB changes depending on the current I flowing through the Hall element and the magnetic field H applied thereto. Therefore, by passing a constant current through the Hall element, changes in magnetic field strength can be detected by the voltage generated between AB. Furthermore, by making the bottom plate of the heating chamber 5 of a material that blocks high frequency waves but allows the magnetic field to pass through, the magnetic field strength detection section 11 can detect changes in the strength of the magnetic field without being affected by the high frequency waves.

Figure 6a shows the vibration when a weight is attached to a spring.The elastic constant of the spring is K, and the mass of the weight is m.
In this case, the frequency f is f=1/2π√K/m, and as the mass increases, the frequency decreases. Figure b shows a stand according to an embodiment of the present invention. This structure and operation will be explained. First, the weight of the food 7 is measured on the mounting table 8.
This force is applied to one end of the leaf spring 12 by the mounting table attachment member 20. On the other hand, since the other end of the leaf spring 12 is fixed to the support rotating table 18, the leaf spring 12 bends and vibrates. Then, the magnet 10 can vibrate and transmit the vibration to the magnetic field strength detection section 11 by magnetism. Further, a configuration in which the leaf springs are fixed in parallel is called a Roberval configuration and is well known in the field of scales. This mechanism can reduce the influence of the position of the food on the mounting table.

FIG. 7 shows the relationship between the various parts when the magnet 10 is vibrating. a is the distance L between the magnet 10 and the magnetic field strength detection section 11, and the distance L changes over time due to vibration. b shows the relationship between the distance L and the magnetic field strength of the magnetic field strength detection section 11. From a and b, c shows the change in magnetic field strength due to vibration of the magnet 10 of the magnetic field strength detection unit 11. d is the relationship between the magnetic field strength of the Hall element and the output voltage when a constant current is passed when a Hall element is used as the magnetic field strength detection section 11.
e indicates the output voltage of the Hall element from c and d. Therefore, the same frequency as the vibration of the magnet 10 can be detected by the Hall element.

FIG. 8 shows a circuit for extracting the output of this Hall element as a signal. Point A is the output voltage from the Hall element. At point B, only the alternating current component is transmitted through the capacitor. The voltage at point B is amplified to form the waveform at point C. By inputting the voltage at point C to a comparator, a square wave output like that at point D can be obtained.

FIG. 9 shows the vibration of the spring 12, that is, the magnet 10, and the D
This shows the relationship between the output waveforms at points, and shows that the frequency varies depending on the weight of the food. That is, between a and b, a has a higher vibration frequency, so the weight of the food is smaller.

FIG. 10 is an example of a control circuit for the high frequency heating device of the present invention. A microcomputer 24 performs storage, judgment, calculation, data input/output, etc. 2
5 is an oscillation circuit, which generates a fundamental frequency for measuring the vibration frequency of the magnet 10. 6 is a magnetron that generates high frequency waves, and 23 is a fan motor for cooling the magnetron 6. 21 and 22 are relays and their drive circuits for controlling the output of the magnetron 6.

FIG. 11 shows the operation of weight measurement. a is magnet 1
Pulse extracted from the vibration of 0, b is the oscillation circuit 5
is the output waveform of , and c shows the flow of the measurement method at that time. In other words, the frequency of vibration of the magnet 10 can be found by counting the number of pulses from the oscillation circuit between the falling point P of the pulse from the vibration of the magnet 10 in a and the next falling point Q. .

As described above, food can be measured inside the heating chamber, and the signal can be easily transmitted outside the heating chamber using magnetism, so it is not affected by high frequencies. Furthermore, the measurement accuracy is completely unaffected by variations and errors caused by components on the control circuit.

A microcomputer then calculates the heating output, time pattern, etc. corresponding to the measured weight.

An example of the operation of a microwave oven as an embodiment of the present invention will be described with reference to FIG.

FIG. 12 shows an example of the display section 1 and the setting section 2. The setting section 2 has a cooking menu selection key, and the heating time, output, and pattern are determined based on the selected menu and the measured weight of the food. The operation will be explained using an example of thawing frozen food. When the "unzip" key 26 of the setting section 2 is pressed, Og is displayed as the initial value as shown in FIG. 12a. Next, by placing the frozen food on the mounting table 8 in the heating chamber, the magnet 10 vibrates, and by determining the frequency or period of vibration, the microcomputer 24 calculates the weight, as shown in FIG. 12b. Display the weight as shown. Then, after the weight is displayed, the "cooking start" key 27 is pressed to start heating. Immediately after the start, the microcomputer 24 calculates the heating time T corresponding to the weight of the food, and the display section 1 switches to display the time as shown in FIG. 12c. Thereafter, the remaining time is displayed as shown in FIG. 12d.
Furthermore, the heating output P, heating time T, and heating pattern when defrosting the food at this time are shown in Figures 13a and b.
These are shown in the microcomputer 2.
4, and after pressing the "start cooking" key 27, thawing automatically proceeds, and when a predetermined time has elapsed, high frequency oscillation is stopped and thawing is completed.
In addition, Fig. 13a shows heating for T ₁ second with an output of 600W,
Indicates that the next T ₂ seconds will stop, and the next T ₃ seconds will heat at 200W. Furthermore, FIG. 13b shows that each time is determined from the weight Wg of the food product.

In this way, just by placing the object to be heated in the heating chamber,
Since the weight is measured and the food is cooked automatically, it is easy to use and allows for efficient cooking.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

1. Easy to use because the weight of food can be measured by placing it inside the heating chamber.

2. Since the weight of food is measured by the frequency of the spring, the causes of measurement errors are the elastic constant of the spring and the basic oscillation circuit, and are not affected by the strength of the magnetic field or variations in the detection circuit.

3. Vibration is transmitted by magnetic field, so it is not affected by high frequencies. This allows measurements within the food heating chamber.

4. In conventional weight detection devices, the deformation of a spring due to weight is further converted into an electrical signal using electrical resistance, capacitance, magnetic field strength, etc., and since this electrical signal is an analog quantity, I needed to do a D conversion. However, in the present invention, an analog quantity called weight is converted into a digital quantity called vibration frequency using a spring, so there is no need for a new D-A converter using an electronic circuit or the like.

5. To eliminate uneven heating of food, it is possible to easily implement a method of heating while rotating.

6. There is little influence from the position of food.

[Brief explanation of drawings]

FIG. 1 is an external perspective view of a microwave oven according to an embodiment of the present invention, FIG. 2 is a side sectional view of the same microwave oven, FIG. Fig. 4 is an exploded perspective view of the same mounting stand, Figs. 5 a and b are explanatory diagrams of the vibration detection principle, Figs. 6 a and b are configuration diagrams showing the principle of vibration of the spring, and Figs. 7 a to 7.
e is a characteristic diagram showing the relationship between each part of the weight measurement system, Figure 8 is a waveform shaping circuit diagram of the output voltage from the Hall element, and Figures 9a and b are characteristic diagrams showing the relationship between weight and frequency. , Fig. 10 is a circuit diagram of the same microwave oven, Fig. 11 a, b, and c are characteristic diagrams and flowcharts of reading the same frequency and weight conversion, Fig. 12 A,
13B is a front view and a display state explanatory diagram of the setting section of the same microwave oven, and FIGS. 13a and 13b are characteristic diagrams showing conversion for determining heating conditions for defrosting. 1...display section, 2...setting section, 3...door,
4...Body, 5...Heating chamber, 6...Magnetron, 7...Food (subject to be heated), 8...Placement table, 9
... Rotating plate, 10 ... Magnet, 11 ... Magnetic field strength detection section, 12 ... Leaf spring, 13 ... Wheel, 14 ...
Magnet, 15... Magnet, 16... Spring fixing material, 17
...Block material, 18...Support rotary table, 19...
Connection ring, 20... mounting table mounting material, 21... relay and drive circuit, 22... relay and drive circuit, 23... cooling fan motor, 24... microcomputer, 25... oscillation circuit, 26... thawing Key, 27...Cooking start key.

Claims (1)

[Scope of Claims] 1. A heating chamber that stores an object to be heated, a high-frequency oscillator that supplies high-frequency energy into the heating chamber, a table on which the object to be heated is placed, and a spring body that supports the table. And, by placing the object to be heated,
Means for detecting the frequency of simple harmonic vibration occurring in the mounting table supported by the spring body is provided, the weight of the object to be heated is calculated by detecting the frequency of the mounting table, and the weight of the object corresponding to the calculated weight is A high-frequency heating device characterized by comprising a control circuit that controls the output of a high-frequency oscillator, the time distribution of heating output, and the heating time. 2 The table on which the heated object is placed is held by a plurality of leaf springs whose vibration frequency changes depending on the weight of the heated object to be placed,
2. The high-frequency heating device according to claim 1, further comprising a mechanism in which the plate springs are attached in parallel at intervals and fixed at both ends. 3. The high-frequency heating device according to claim 1, wherein the vibration of the mounting table is converted into a magnetic change and detected. 4. The high-frequency heating device according to claim 1, wherein the mounting table is rotatable. 5. The mounting table is equipped with a rotatable support rotating table supported by three or more wheels, a mounting table for the object to be heated, and a spring member having a plurality of leaf springs mounted in parallel at intervals and fixed at both ends. , the mounting table and the supporting rotary table are connected by the spring material, and the rotational driving force of the placing table is transmitted by attaching a magnet to the turntable and also connecting it to the outside of the heating chamber at a position corresponding to the position of the magnet. 5. The high-frequency heating device according to claim 4, wherein a magnet is attached and the magnet outside the heating chamber is rotated to transmit rotational force to the turntable using magnetic force.