JPH026420B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heating cooking device having a so-called weighing function, which is equipped with a function of measuring the weight of an object to be heated.

When heating food, which is an object to be heated, in a conventional microwave oven, for example, most of the high frequency energy is absorbed by the food, unlike when using a conventional heat source. Therefore, the time required for heating increases significantly as the weight of the food increases.
It is very difficult to set the optimal cooking time, especially when defrosting and heating, because if you heat for longer than the optimal time, for example, raw fish that is to be made into sashimi will end up being overcooked. However, setting the heating time was even more difficult.

From the above point of view, many microwave ovens have been proposed in which the microwave oven is equipped with a scale function and a microwave output control device that operates in conjunction with the scale function.

However, in reality, this type of microwave oven with a weighing function has not been put to practical use at all.

The first reason for this is the problem of the location of the receiving tray on which the food is placed. In other words, in order to measure the weight of food, there must be enough space around the receiving tray to place the food.

From this point of view, the simplest structure may be one in which a load receiving tray is installed on the top surface of the microwave oven main body, and a weighing device is provided in a part of the main body to detect the weight in conjunction with the movement of the load receiving tray. However, when considering the general usage conditions of cooking devices such as microwave ovens, the top surface of the main unit is often used for placing other items, is close to the ceiling, hanging shelves, etc., or is installed at a high location that is difficult to reach. It is stiff and sluggish and is very inconvenient to use.

Another idea is to use the turntable in the heating chamber of the microwave oven in conjunction with the load tray, and install a weighing device that works with the turntable, but in addition to being technically difficult and expensive, Even if this structure is created, when actually trying to measure the weight of food, it is necessary to subtract the weight of the food container (packaging, outer wrapper, bowl, etc.), so only the container must be weighed first. Next, it becomes necessary to perform operations such as adding food and weighing it again, and performing these operations in a narrow heating chamber is not a very convenient structure.

The present invention aims to solve the above-mentioned conventional problems.

The present invention has a structure in which the function of a receiving tray for placing food is provided on a door attached to the front opening of the heating chamber so that it can be opened and closed freely, and is easy to use, has an excellent appearance, and is also technically and cost-effective. To provide a realistically superior heating cooking device.

An embodiment of the present invention will be described below based on the drawings.

In FIG. 1, a door 3 is freely openable and closable in a front opening 2 of a heating chamber 1 of a microwave oven, and is rotatable about a fulcrum 5 of a hinge 4 located at the lower part of the front surface. Furthermore, the door arm 6 of the door 3 is guided by a guide roller 7 rotatably provided on the hinge 4, and is always urged in the closing direction of the door 3 by a door spring 8.

When the door 3 is opened and is in a substantially horizontal position, the stopper part 9 of the door arm 6 comes into contact with the guide roller 7 to prevent the door 3 from being opened further. One end 10 of the hinge 4 is connected to a weight detecting section 11 having a weight detecting element.
1 is further provided on a fixture 12. Fixture 12
is bolted to the bottom plate 13 of the main body. It should be noted that the above-mentioned configuration is exactly the same for the hinge portion on the other side, which is not visible in the figure.

In FIG. 2, parts such as the hinge 4 and the door arm 6 are omitted to make the explanation easier to understand.

This weight detection section 11 is made up of two leaf springs A14 and B.
15 is configured into a parallelogram mechanism applying the generally known Roberval principle, and two leaf springs A14 and B
Strain gauge A, which is a weight detection element, is placed on one side of 15.
16 and B17 are provided. That is, spacers A18 and B19 consisting of rigid blocks and leaf spring A1
4 and B15 form a parallelogram that functions as a roberval mechanism, and strain gauges A16 and B17 that change the electric resistance value in proportion to the strain of this leaf spring A14 are attached to the leaf spring A14 in close contact with each other. It is being The spacer A18 is the fixture 12
One spacer B19 is connected to the door 3 via the hinge 4 as shown in FIG. 1 (in FIG. 2, the hinge 4
).

FIG. 3 shows a detection mechanism section that detects whether the door 3 is opened or closed. As a detector for detecting the open/closed state of the door 3, for example, a micro switch 21 may be used. When the door 3 changes from the closed state shown by the broken line to the open state shown by the solid line, the lever 21a of the micro switch 21 is pushed down and the micro switch 21 is turned on 22 or turned off.
As shown in the figure, the signal is sent to the control device as an electrical signal.
It is transmitted to the CPU (microcomputer).

The functions and effects of the above configuration will be explained below.

The door 3 opens almost horizontally. At this time, the leaf springs A14 and B15 of the weight detection unit 11 support the entire weight of the door 3, the door arm 6, etc., as well as the load of the hinge 4, etc., and also the tension of the door spring 8 determined by the open/close position of the door 3. It is receiving a load of force.

At this time, the microswitch 21 detects that the door 3 is opened, so the CPU 22 stores the output of the weight detection section 11 in this state as an initial value. Next, in this state, when the food 20 to be heated and cooked is placed on the back surface of the door 3, the spring plates A14 and B15 are deflected by the load, and the resulting strain changes are measured by the strain gauges A16 and B17.
It is detected as the difference between the initial electrical resistance value and the initial value. What is important in this case is that when the door 3 is opened, the signal from the micro switch 21 causes the output of the weight detection section 11 to be set to the initial value.
Since the weight of the food 20 is stored in the CPU 22, the CPU 22 calculates the weight of the food 20 as the difference between the output of the weight detection unit 11 at the time the food 20 is placed and the previously stored initial value.
It is calculated by

Also, due to the action of the Roberval mechanism, the deflection of the leaf springs A14 and B15 is reduced even when the food 20 is placed at the position _W1 shown in the figure near the tip of the door 3 or at the position _W2 near the hinge 4. The amounts are the same, and therefore the resistance changes of the strain gauges A16 and B17 are also the same, so there is no error in the detected weight of the food 20 depending on the position before or after the food 20 is placed.

Furthermore, in order to prevent the detected amounts of the strain gauges A16 and B17 from changing depending on the left and right positions on which the food 20 is placed, in this embodiment, the left and right
The weight detection unit 1 with the same configuration is attached to the 4 parts of the two hinges.
1, and a pair of left and right strain gauges A16
The detection output is the sum of the outputs of the strain gauges B17 of the same pair. That is, in this embodiment, the weight of the food 20 can be accurately detected no matter where on the door 3 the food 20 is placed.

Next, an outline of the control circuit will be explained based on the block diagram of FIG.

In FIG. 4, when the door 3 is opened, the micro switch 21, which is a detector, detects that the door 3 is opened, and the output voltage of the bridge 23 in this state is amplified by the differential amplifier 24. After that, the value is converted into a digital value by the A/D converter 25, inputted to the CPU 22 consisting of a microcomputer, and stored as an initial value when the weight is zero. Here, the bridge 23 is composed of strain gauges A16 and B17, and these strain gauges A16 and B17 indicate a resistance value corresponding to the load applied to the weight detection section 11, and naturally the bridge 23 also corresponds to this resistance value. becomes the output voltage.

Next, when the food 20 is placed on the opened door 3, the weight changes the electrical resistance of the strain gauges A16 and B17. The output voltage of the bridge 23 corresponding to the electrical resistance value after this change is determined by the differential amplifier 24.
After being amplified by the A/D converter 25, it is converted into a digital quantity by a microcomputer.
It is input to the CPU 22. The difference between the measured value after placing the food 20 and the initial value memorized when the door 3 was opened corresponds to the weight of the food 20.
The CPU 22 converts it into weight, sets a cooking sequence and cooking time corresponding to the weight, controls the oscillation operation of the magnetron 26, and displays the weight, cooking time, or operating state on the display tube 27.

According to the above embodiment, the pair of weight detection units 11
are installed on the left and right hinges 4 of the door 3, and the weight of the food 20 is measured by detecting the sum of the strain of the pair of strain gauges 16 and 17, that is, the sum of the change in electrical resistance value. It is possible to minimize the weight error that occurs depending on the position where the product is placed. Furthermore, since the initial value is reset each time the weight is measured using a signal from the micro switch 21 that detects the open state of the door 3, the zero points of the bridge 23 and the differential amplifier 24 will always be accurate even if they change over time or temperature. Measuring is possible, more accurate cooking time is displayed, and cooking is performed according to that time, so there are fewer mistakes in cooking. Furthermore, since the door 3 is used as a load receiving tray for the scale, the carrying area is large and the height is moderate, making it very convenient to use.

Also, although not mentioned in the above explanation, the weight detection system of the heating cooking device according to the present invention can naturally have a taring function as well as a general electronic scale, and the operation panel 28 can be equipped with a tare function. A tare key (reset key) is provided, and when this key is pressed, the load placed on the door 3, that is, the value including the tare, is set as the initial value in the CPU 22, and when the food to be measured is placed on this, the tare is set. Only the load of this food placed after pressing the pull key is
Naturally, it is possible to configure the CPU 22 to determine the weight of the food.

In the above embodiment, a weight detection section is provided on each of the left and right hinges, but in another embodiment, a weight detection section may be provided on only one of the hinges. However, in this case, a drawback is that correct weighing cannot be performed unless the object to be weighed is placed at a predetermined position on the door 3. However, it can be said that this embodiment is superior to the above-mentioned embodiments in terms of simple structure.

As described above, according to the present invention, by placing the food on the door, a sufficiently large area for placing the food can be obtained, and because of the positional relationship that it is on the surface of the door through which food is taken in and out, it is possible to place the food on the door surface. It is easy to use because it can be placed on a container to measure its weight and placed directly into the heating chamber, and the work procedure is very natural, especially when taring.

Moreover, since the zero point correction for weight measurement is automatically performed each time the door is opened, it is necessary to measure the weight with the door open due to the basic structure of the present invention, so the zero point correction is performed immediately before weight measurement. Accurate weight measurement can be carried out automatically.

As a result, as shown in the example, by combining it with a CPU consisting of a microcomputer, a display tube, etc., it is easy to automatically set and display the heating time and cooking pattern based on the detected weight. It is possible to realize this in the future.

[Brief explanation of drawings]

Fig. 1 is an external perspective view of the main parts of a microwave oven which is an embodiment of the present invention, Fig. 2 is an explanatory diagram of the operation of the door section, Fig. 3 is an enlarged side view of the main parts, and Fig. 4 is the control of the same. FIG. 2 is a block diagram of the device. DESCRIPTION OF SYMBOLS 1... Heating chamber, 2... Front opening, 3... Door, 4... Hinge, 11... Weight detection part, 14,
15...Plate spring, 16,17...Strain gauge,
20... Food (heated object), 21... Micro switch (detector), 22... CPU (micro computer), 26... Magnetron (heating source).

Claims (1)

[Scope of Claims] 1. A heating chamber that stores an object to be heated, a heat source that heats the inside of the heating chamber, and a front opening of the heating chamber that rotates around a hinge located at the lower front of the heating chamber and is in an open state. a door that can be opened and closed so that the door plane is substantially horizontal; a weight detection unit that supports part or all of the weight of the door for detecting the weight of a heated object placed on the door in an open state; A heating cooking apparatus comprising: a detector for detecting an open state of the door as an electric signal; and a zero point correction of a detection outlet of the weight detecting section is performed based on a detection signal from the detector. 2. The weight detection unit has two leaf springs facing each other in parallel with rigid spacers A and B, and fixes one of the spacers A to the hinge of the door and the other spacer B to a part of the main body. 2. The heating cooking device according to claim 1, wherein the leaf spring is provided with a strain gauge for detecting the amount of strain in the leaf spring, and the weight is detected based on the amount of change in the electrical resistance value of the strain gauge.