JPS58221333A - Heat cooking device - Google Patents

Abstract

PURPOSE:To enable the titled device to be handled easily by a method wherein a door for opening and closing a heating chamber is made to have a balancing function of measuring a food receiving dish so as to control the microwave output of an electronic range having a balancing function. CONSTITUTION:When the food 20 to be heated is placed on the rear surface of the door 3, a strain rod 11 bends by an amount corresponding to the weight of the food as a load and the amount of variation of the strain of the rod 11 is detected as the amount of variation of electrical resistance value of each of strain gauges 16A, 16B, 17A and 17B. Supposing that Vi is a voltage impressed upon a bridge 21, Vo is the output voltage of the bridge 21, W is a load, Ebh<2> is a characteristic value of the strain rod 11, F is a gauge factor of each of the strain gauges and lo is the distance between two points of application of the strain gauges, the equation Vo=(3FW/Ebh<2>)lo.Vi holds and it will be made clear that the output voltage Vo of the bridge 21 has notching to do with the distance between a point at which the load is applied and the points of application of the strain gauges. Then the variations of the output voltages Vo of the bridge 21 are amplified by a differential amplifier, while the amplified values are added by an adder, the added value is applied on an A/D converter and the output of the A/D converter is inputted to CPU comprising a microcomputer so that the weight of the food, the cooking time and the operation condition of the cooking range are displayed on a display tube.

Description

[Detailed description of the invention] The present invention has a function to measure the weight of the object to be heated.

The present invention relates to a heating cooking device having a so-called weighing function.

For example, when heating food in a microwave oven, 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, making it extremely difficult to set the optimal cooking time, especially when defrosting and heating.
If you heat it for longer than the optimal time, you will end up with a mistake, such as the raw fish you plan to make into sashimi will end up boiling.
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 position between the receivers where the food is placed. In other words, K for measuring the weight of food is consignment + 111
There must be enough space around the food to place the food.

From this point of view, the simplest structure may be one in which a receiver 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 receiver. 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 difficult to use and is very inconvenient to use.

Another idea is to use a turntable in the heating chamber of the microwave oven in combination with a receiver and install a weighing device that works with the turntable, but this would be technically difficult and costly. Even if this structure were created, when actually trying to measure the weight of food, it would be necessary to subtract the weight of the food container, the so-called packaging, outer wrapper, teacup, etc., so only the container should be weighed first. Then, it becomes necessary to perform operations such as adding food and weighing it again, and performing these operations in a narrow heating chamber does not provide a structure that is easy to use.

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

The present invention has a structure in which the function of a cargo 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 and has an excellent appearance.
To provide a heating cooking device which is excellent in terms of cost and practicality.

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

In FIG. 1, a front opening 2 of a heating chamber 1 of a microwave oven is shown.
A door 3 is provided so as to be freely openable and closable, and is rotatably provided around a fulcrum 6 of a hinge 4 located at the lower front surface.

Further, 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 open and the door is in a horizontal position, turn the door arm 6
A stopper portion 9 contacts 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, and this weight detecting section 11 is further provided on a fixture 12 . The fixture 12t/'i 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.

Next, the main parts of the configuration will be explained according to FIG.

In Figure 2, the hinge 4. Parts such as the door arm 6 are omitted.

This weight detection unit 11 includes one strain rod 14 and a strain gauge 16A that detects the strain of the strain rod 14 that changes depending on the weight.
, 17A, 16B, and 17B.

The distortion support 14 is fixed to a part of the main body with one end being a fixed end,
The other end is connected to the door 3 via a hinge 4 as a load end, as shown in FIG. 1 (the hinge 4 is omitted in FIG. 2).

FIG. 3 is a principle diagram for explaining the principle of weight detection operation in the present invention including the weight detection section 11, and a and b indicate its structure, and C indicates its electric circuit. 3C is a so-called bridge circuit, and the output voltage vO of the bridge 21 can be expressed by the following equation.

To = (△RI - △R2)XVi/(2R),
, , , (1) However, ΔR1, ΔR2< R, ΔR
+, △R2 are distortion games Rj16A, 16B and 1RyoA,
17B, R represents the specific resistance of the strain gauges 16A to 17B, and Vi represents the voltage applied to the bridge 21. Here, the gauge factor of the strain gauge is Fl, and the amount of strain is ε
Then, from the commonly used strain gauge formula, △R-
The amount of strain at the two attachment points of the strain gauges is 81°ε2, and the amount of resistance change of the strain gauges 16A and 16B is △R1, R1- Ji17A
, 17B is applied to the above equation (2) with the resistance change amount as △R2, △R1-ε, FR...
(3'1△R2-ε2・F-R・・・・・・・・・(4
), and by substituting equations (3) and (4) into equation (1), the following equation can be derived.

Vo=-F(ε1-ε2)×vi/2...
(6) Here, the strain amount ε1 of the strain gauges 161 to 16B and the strain amount ε2 of the strain gauges 17A to 17B are determined. When the shape of the four strained lines 14 is set as shown in Figure 3(a) and the amount of strain 81', ε2 at each gauge part is determined, ε becomes eW.
6. /(K-b-h) ・・・・・・・・・(
6) ε2=eW7J2/(E-b-h) ・
......(A) (where E is Young's modulus of the strained rod 14).

By substituting this equation (6+, (7)) into the above equation (6), the following equation (8) is obtained.

VO,=(3FW/ICt)h2)10-Vi,
, , , , , (8) In equation (8), 7IO indicates the interval between the two attachment points of the strain gauge, and the distance between the load point and the strain gauge attachment point is related to the output voltage of the glitch 21. It means that there is no.

Based on the explanation of the operating principle of the weight detection section based on the above Fig. 3, the operation in the configuration of the above Fig. 1 and ``□'' Fig. 2,
I will explain the effect.

Door 3 is opened almost horizontally. At this time, the weight detection section 11
The distortion bar is the door 3. In addition to the entire weight of the door, such as the door arm 6, it supports the load of the hinge 4, etc., and also receives the tensile force of the door spring 8, which is determined by the opening/closing position of the door 3. When the food 2o to be heated and cooked is placed on the back side of the door 3 in this state, the strain rod is deflected by the load, and as a result, the amount of strain change in bunching is measured by the strain gauge 16A.

This is detected as the amount of change in the electrical resistance values of 16B, 17A, 17B. In this case, what is important is that, as can be seen from the explanation of the operating principle of the weight detection section based on FIG. Even at the position W2 close to the hinge 4, the output voltage of the bridge formed by the strain gauge is the same, so there is no change in the detected weight of the food 2o depending on the position before or after the food 2o is placed.

In addition, in order to prevent the detected amount, ″, from changing depending on the left and right positions on which the food 20 is placed, in this embodiment, the two left and right hinges 4 are provided with weight detection units having exactly the same configuration. The sum of the outputs 11 is used as the detection output.In other words, in this embodiment, the weight of the food 2o can be accurately detected no matter where on the door 3 the food is placed.

Next, an outline of the electric circuit for detection and control will be explained based on the block diagram of FIG. 4. However, for convenience of explanation, regarding the pair of left and right weight detecting sections, each part number on the side not shown in FIG.

Both are distinguished as strain gauges 16A', 16B', 17A', and 17B'.

In FIG. 4, the weight of the food 20 placed on the opened door 3 is measured by a bridge 21 and a strain gauge consisting of a pair of strain gauges 16A, 16B, 17A, 17B of a pair of weight detection units 11 and 11'. At 16.

The output voltage of the glitch 21 composed of 16B', 17A', and 17B' changes, is amplified by the differential amplifiers 22& and 22b, and then added by the adder 22G. The output voltage of the adder 22C is further converted into a digital quantity by an A/D converter, and is input to a CPU 24 consisting of a microcomputer.

This CPU 24 converts the weight, sets the cooking sequence and cooking time corresponding to the weight, controls the start/stop operation of the magnetron 26, and displays the weight, cooking time, or operating status on the display tube 26. .

This series of operations is executed by operating the operation keys 27.

According to the embodiment described above, a pair of weight detecting sections 11 and 11' whose detection output is constant in the front and rear positions are provided on the left and right hinges 4 of the door 3, and the sum of the outputs of the pair of weight detecting sections 11 is detected. Since the weight of the food 2o is weighed by the food 2o, weight errors caused by the position of the food 2o can be minimized no matter where on the door 3 it is placed.Therefore, accurate weighing is possible, more accurate cooking time is displayed, and Since cooking is performed according to the time, there are fewer mistakes in cooking. In addition, since the door 3 is used as a cargo receiving area for the scale, the loading area is large and the height is moderate, making it very convenient to use.

In the above embodiment, one weight detection section 11 is provided in two pairs (4
strain gauges 16A, 17A, 16B.

17B, but a pair (two pieces) of strain gauges 16A,
Even if configured with 17A, 1eB, or 17B, exactly the same characteristics can be obtained with only half the output voltage, and one bridge is configured with four strain gauges, each with a pair of left and right weight detection sections 11 and 11'. and two weight detection parts 1
It is also possible to adopt a configuration in which the detection output is the sum of 1 and 11'.

It is also possible to increase the sensitivity by attaching multiple strain gauges to the same strain point to increase the detected output voltage.

Further, in the above embodiment, the left and right hinges each have a weight detection section, but in another embodiment, the weight detection section may be provided only on one side. 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, heating cooking can be automated in that by placing food on the door, the weight of the food, cooking time, or cooking pattern are automatically detected, displayed, and executed. Furthermore, since there is a sufficiently large area for food to be placed, and because it is located on the surface of the door through which food is taken in and out, it is also possible to subtract the weight of the container, for example, in the case of so-called tare measurement. It is possible to provide a heating cooking device that is very easy to use, such as being able to be placed on the door surface and put into the heating chamber as it is.

[Brief explanation of the drawing]

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, and Fig. 3 (2L
), (b), and (Q) are explanatory diagrams for explaining the principle of weight detection by the weight detection section 11, and FIG. 4 is a block diagram of the detection control circuit. 1...Heating chamber, 2...Front opening, 3
...Door, 4...Scolding power 11...
・Weight detection section, 14... Distortion rod, 16.17.
...Strain gauge, 20 ... Food (object to be heated), 25 ... Magnetron (heat source).

Claims (1)

[Claims] A heating chamber that accommodates an object to be heated, a heating source that heats the inside of the heating chamber, a door that can be opened and closed by rotating around a hinge located at a front lower part of the front opening of the heating chamber, and one of the doors. and a weight detecting section that supports the weight of the whole body, and the weight detecting section has one end of one strained rod fixed as a fixed end to a part of the main body, and the other end as a load end to the hinge part of the door. The door load including the hinge part is supported by a strain rod, and a strain gauge is provided on the strain rod to detect the amount of strain at an even number of points on the strain rod. A heating cooking apparatus configured to detect a proportional difference in the amount of strain at an even number of points based on the amount of change in the electrical resistance value of the even number of strain gauges.