JPH0248727Y2 - - 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 disadvantage that the manufacturing cost is high because there are many parts that make up the weight sensor and precision in assembling the parts is required.

Therefore, in view of the above-mentioned drawbacks, a support roller that supports the turntable and rotates on the bottom of the heating chamber is disposed inside the heating chamber, and a piezoelectric transducer 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 that has fewer components and is inexpensive has been proposed.

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 a detailed sectional view of the turntable part. .

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 dashed 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 there are variations in the attachment state of the piezoelectric element 8 to the back surface of the bottom wall 1a and the piezoelectric element 8 itself, it is necessary to adjust the variation in order to detect the weight with high accuracy.

<Purpose> The present invention has been made in view of the above, and it is an object of the present invention to enable highly accurate weight detection by providing an output voltage adjustment means for adjusting the output voltage of a piezoelectric transducer.

<Embodiment> Hereinafter, one embodiment of the weight detection device for a microwave oven of the present invention will be described based on the drawings.

FIG. 1 is an electrical circuit diagram showing an embodiment of the output voltage adjusting means of the present invention. In the figure, 18 is a variable resistor VR, which is connected between both poles of the piezoelectric element 8. The variable resistor 18 is disposed in a control panel (not shown) of the microwave oven so that the resistance can be easily adjusted. When the resistance of the variable resistor 18 is changed (from high resistance to low resistance), the relationship between weight and output voltage changes (A → B) as shown in FIG. It can be adjusted to absorb variations in the attachment state or the piezoelectric element 8 itself,
Moreover, since the control panel section allows adjustment, the adjustment process after assembly or the adjustment work during service repair at the customer's site can be performed extremely easily.

Further, since the output voltage adjusting means can be configured simply by adding the variable resistor 18 in parallel to the piezoelectric element 8, it is very advantageous in terms of cost.

It should be noted that the connection position and arrangement location of the variable resistor 18 are not limited to the embodiments described above and illustrated, and it goes without saying that the present invention can be modified and implemented as appropriate without departing from the gist of the invention.

<Effects> The present invention provides a support roller that supports a turntable and rotates the bottom of the heating chamber within 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 the elements,
In the weight detection device for a microwave oven, the weight of an object to be heated placed on the turntable is detected by detecting a voltage generated in the piezoelectric transducer when the support roller rotates. By providing an output voltage adjustment means for adjusting the output voltage of the conversion element, variations in the piezoelectric conversion element can be adjusted and a highly accurate weight detection device can be obtained, which is of high practical value.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram showing one embodiment of the output voltage adjustment means which is the gist of the present invention, and FIG. 2 shows the change in the relationship between the average output voltage voltage and the weight due to the output voltage adjustment means of FIG. 1. FIG. 3 is a side sectional view of the main part of the microwave oven, FIG. 4 is a top view of the bottom of the heating chamber with the turntable in FIG. 3 removed, and FIG. 5 is a diagram showing the turntable. FIG. 6 is an enlarged detailed cross-sectional view of the table portion, FIG. 6 is a cross-sectional view of the main part of the piezoelectric element portion, FIG. 7 is an output voltage waveform diagram of the piezoelectric element shown in FIG. 6, and FIG. 8 is a conventional piezoelectric element output voltage. FIG. 9 is a diagram showing the relationship between the output peak voltage average value and weight, and FIG. 10 is a conventional magnetron control circuit diagram. Code, 1... heating chamber, 2... turntable,
3... Support roller, 3b... Roller, 7... Roller rotation locus, 8... Piezoelectric element, 18... Variable resistor (output voltage adjustment means).

Claims (1)

[Claims for Utility Model Registration] 1. A support roller that supports a turntable and rotates with the bottom wall of the heating chamber is disposed in the heating chamber, and rotation of the roller on the bottom wall of the heating chamber that causes stress due to rotation of the support roller. A piezoelectric transducer is placed in the locus,
A weight detection device for a microwave oven, which detects a voltage generated in the piezoelectric transducer when the support roller rotates, and detects the weight of an object to be heated placed on the turntable,
A weight detection device for a microwave oven, comprising an output voltage adjustment means for adjusting the output voltage of the piezoelectric transducer. 2. The weight detection device for a microwave oven as set forth in claim 1 of the utility model registration claim, characterized in that the output voltage adjustment means can be adjusted from outside the microwave oven main body.