JPH0247365Y2 - - Google Patents

Description

[Detailed description of the invention] <Technical field> The present invention relates to a weight detection device for a microwave oven.More specifically, the present invention relates to a weight detection device for a microwave oven. Regarding something that detects weight.

<Prior Art> Microwave ovens equipped with weight sensors that measure the weight of an object to be heated and control heating based on the measured weight have been rapidly becoming popular in recent years, and are expected to become even more popular in the future. However, the conventional microwave oven with a weight sensor has a drawback that the manufacturing cost is high because there are many parts that constitute the weight sensor and precision in assembling the parts is required.

Therefore, in view of the above drawbacks, a support roller that supports the turntable and rotates on the bottom of the heating chamber is disposed inside the heating chamber, and piezoelectric conversion is applied to the roller rotation locus on the bottom of the heating chamber that generates stress due to the rotation of the support roller. By arranging an element to detect the voltage generated in the piezoelectric transducer when the support roller rotates, and detect the weight of the object to be heated placed on the turntable, A weight detection device for a microwave oven has been proposed that has fewer components and is inexpensive.

Hereinafter, the weight detection device for the microwave oven will be explained based on the drawings.

Figure 3 is a side sectional view of the main parts of the microwave oven, Figure 4 is a top view of the bottom of the heating chamber with the turntable shown in Figure 3 removed, and Figure 5 is an enlarged detailed sectional view of the turntable. .

In the figure, 1 is a heating chamber, 2 is a turntable on which the object to be heated is placed, and 3 is a support roller that supports the turntable 2 and rotates on the bottom of the heating chamber 1. As shown in FIG. an arm 3a, a roller 3b rotatably pivoted to the tip of the arm 3a,
3b, 3b, and is rotated by the rotation of a turntable motor 5 attached to the lower surface of the bottom wall 1a of the heating chamber 1 with a motor attachment angle 4.

That is, a coupling portion 3c of the arm 3a that is detachably fitted to the coupling ring 6 that is pivotally attached to the rotating shaft of the turntable motor 5.
The rotational force of the motor 5 is transmitted to the support roller 3, and the bottom surface of the heating chamber 1 and the rollers 3b, 3b,
3b draws a rotation locus 7 as indicated by a chain line in FIG.

Reference numeral 8 denotes a piezoelectric element disposed on the back side of the rotation locus 7 of the bottom wall 1a of the heating chamber 1, the details of which will be described later based on FIG. 9 is a magnetron that generates high frequency radio waves, 10 is a waveguide that guides the high frequency radio waves into the heating chamber 1, 11 is a cabinet forming the outer shell of the microwave oven, and 12 is a door.

The piezoelectric element 8 is constructed by laminating a base electrode plate 8a, a piezoelectric ceramic 8b, and a vapor-deposited electrode 8c as shown in FIG. A voltage as shown in Figure 7 is induced and output. The peak value V ₁ of this output voltage is detected an appropriate number of times by a detection circuit (not shown) through a filter circuit formed by a resistor R and a capacitor C shown in Fig. 8, and the average value is taken. is proportional to the weight of the object to be heated, as shown in FIG.

FIG. 10 is a circuit diagram for controlling the magnetron 9 in response to the detected weight of the object to be heated.
This circuit detects the output voltage peak value a predetermined number of times, calculates the weight based on the average value, controls the relay 14, controls the magnetron 9, and controls the heating of the heated object. In addition, 15 is a heating start switch, 16 is a fuse, and 17 is a high voltage transformer.

The above-described weight detection device for a microwave oven has a simple structure of the detection section, has a small number of component parts, and is easy to assemble. Furthermore, even though the table on which the object to be heated is placed is a turntable, the output voltage peak value of the piezoelectric element 8 is detected an appropriate number of times and the weight is detected based on the average value, so that uneven loads and center loads can be detected. The difference is small and the weight detection accuracy is high.

However, since the number of piezoelectric elements 8 is one, the weight cannot be detected until the three rollers 3b, 3b, 3b have passed. That is, since it currently takes 20 seconds for the support roller 3 to rotate once, there is a drawback that the weight cannot be detected until 10 seconds or more have elapsed since the support roller 3 started rotating.

<Purpose> The present invention was developed in view of the above-mentioned drawbacks, and by arranging at least the same number of piezoelectric transducers as the number of supporting rollers and at a position where each roller applies pressure almost simultaneously, it is possible to The purpose is to enable accurate weight detection.

<Example> Hereinafter, an example of the present invention will be described based on the drawings. Figure 1 is a top view of the bottom of the heating chamber of the microwave oven according to the present invention with the turntable removed;
The figure is a magnetron control circuit diagram in the present invention.

Note that the same reference numerals are given to the same or equivalent parts as in the conventional example, and the explanation thereof will be omitted.

As shown in FIGS. 1 and 2, the present invention has three piezoelectric elements 8, the same number as the number of supporting rollers 3, and a position where three rollers 3b, 3b, 3b press simultaneously. It was placed in

Therefore, the outputs of the piezoelectric elements 8, 8, and 8 are performed simultaneously, and the variations in each output are absorbed by each output adjustment circuit (not shown), and the outputs with the variations absorbed are amplified and held, and each detection timing is The data are sequentially read into the microcomputer 13 via a circuit (not shown). After reading the output voltage held by each of the output adjustment circuits, the microcomputer 13 sends a signal to the output adjustment circuit to cancel the voltage, and prepares for the next weight measurement.

As a result, since weight detection is performed by 1/3 rotation of the support roller 3, heating based on weight detection can be performed faster than in the conventional example.

In the above embodiment, three piezoelectric elements 8,
The piezoelectric elements 8, 8, 8 are connected so that the outputs of the piezoelectric elements 8, 8 are simultaneous, but the timing is slightly shifted.
If the output voltages are sequentially read under the control of the microcomputer 13, the detection timing circuit becomes unnecessary.

Further, if six piezoelectric elements 8 are arranged at a pitch of 60 degrees, the time required for weight detection can be further reduced to 1/2.

<Effects> In the present invention, a support roller that supports the turntable and rotates on the bottom of the heating chamber is disposed in the heating chamber, and when the support roller rotates, the voltage generated in the piezoelectric transducer is detected, and the turntable is rotated. In a weight detection device configured to detect the weight of an object to be heated placed thereon, the piezoelectric transducer is pressurized by at least the same number of rollers as the support rollers, and each roller of the support rollers applies pressure substantially simultaneously. This device has high practical value as a weight detection device for a microwave oven because it can detect weight in a short time and start cooking quickly by arranging it at a certain position.

[Brief explanation of the drawing]

Figure 1 is a top view of the bottom of the heating chamber of the microwave oven of the present invention with the turntable removed, Figure 2 is a magnetron control circuit diagram of the present invention, and Figure 3 is a side sectional view of the main parts of the microwave oven. , Figure 4 is the third
FIG. 5 is an enlarged detailed cross-sectional view of the conventional turntable section, FIG. 6 is a cross-sectional view of the main part of the piezoelectric element section, and FIG. 7 is a top view of the bottom of the heating chamber with the turntable removed. Figure 6 shows the output voltage waveform diagram of the piezoelectric element, Figure 8 shows the R-C filter circuit diagram of the piezoelectric element output voltage, Figure 9 shows the relationship between the output peak voltage average value and weight, and Figure 10 shows the magnetron. It is a control circuit diagram. Code, 1: heating chamber, 2: turntable, 3:
Support roller, 3b: roller, 7: rotation locus of roller, 8, 8, 8: piezoelectric element.

Claims (1)

[Claims for Utility Model Registration] A support roller that supports a turntable and rotates with the bottom wall of the heating chamber is disposed in the heating chamber, and a voltage generated in the piezoelectric transducer when the support roller rotates is detected. , a weight detection device for a microwave oven configured to detect the weight of an object to be heated placed on the turntable, wherein the number of piezoelectric transducers is at least the same as the number of the support rollers, and the number of the piezoelectric transducers is at least the same as the number of the support rollers; A weight detection device for a microwave oven, characterized in that each roller is disposed at a position where pressure is applied substantially simultaneously.