JPH0247366Y2 - - 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 invention detects the voltage generated in a piezoelectric transducer to detect the weight of an object placed on a turntable. Regarding something that detects weight.

<Prior art> Figure 2 is a side cross-sectional view of the main parts of a microwave oven, Figure 3 is a top view of the bottom of the heating chamber with the turntable in Figure 1 removed, and Figure 4 is an enlarged detailed cross-section of the turntable. It is a diagram.

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 the figure, a Y-shaped arm 3a and the arm 3
The roller 3b is rotatably mounted on the tip of the heating chamber 1, 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 mounting angle 4.

That is, the coupling 6 which is pivotally attached to the rotating shaft of the turntable motor 5 and the coupling part 3c of the arm 3a which is detachably fitted to the coupling 6 are fitted, and the rotational force of the motor 5 is transmitted to the support roller 3. The roller 3b traces a locus 7 on the bottom surface of the heating chamber 1 as shown by a dashed line in FIG.

Reference numeral 8 denotes a weight detection mechanism 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 with reference to 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. FIG. 5 is a detailed sectional view of the weight detection mechanism 8, in which a piezoelectric element 18 as a weight detection element is placed in the recess of the holder 14.
Output lead wires 16 and 17 exit through holes 14a and 14b formed in holder 14 to the outside.
The holder 14 is screwed into the case 13 and integrated with the case. Hole 1 in the center of case 13
A knob 21 is inserted into the knob 3a so as to be slidable up and down, and is assembled with the tip protruding by a dimension B from the center hole 15b of a metal cover 15 fixed to the case 13 with a screw 19. As a result, the case 13, holder 14, cover 15, piezoelectric element 18, and knob 21
form an integrated weight detection mechanism 8. A fixture 12 is fixed to the bottom wall 1a of the heating chamber 1 by spot welding, and a weight detection mechanism 8
is attached to the fixture 12 with screws 20. A hole 1b that is sufficiently larger than the tip of the knob 21 is bored in the bottom wall 1a of the heating chamber, and a protrusion 15a is provided on the upper surface of the cover 15 by, for example, a half-bore process in a press process to fit into the hole 1b. ing. The protrusion height of the protrusion 15a is the heating chamber bottom wall 1a.
The bottom wall 1a and the top surface of the protrusion 15a are substantially flush with each other.

The roller 3b rolls on the bottom wall 1a in the direction of arrow A, rides on the protrusion 15a of the cover 15, passes over the knob 21, and presses the piezoelectric element 18, so that a signal corresponding to the weight is obtained. The bottom wall 1a and the protrusion 15a are almost flush with each other, and even if there is a slight difference in level, the difference in level is removed by the knob 21.
Since the difference in level is sufficiently far away, the impact exerted by the roller 3b is attenuated and does not have any effect when the roller 3b reaches the knob 21.

Now, if a liquid such as water or coffee or a sticky liquid such as stew is spilled into the heating chamber 1, the drippings will be in the gap between the knob 21 and the hole 1b in the bottom wall of the heating chamber, or in the knob 2.
1 and the center hole 13a of the case 13, or the liquid may drip onto the surface of the piezoelectric element 18. If moisture adheres to the surface of the element, the piezoelectric ceramic is porous, so it absorbs moisture, or it absorbs vaporization heat from the element, causing a change in output depending on the temperature characteristics of the element. In even more serious cases, it may cause a short circuit between both electrodes, resulting in a situation where no output can be obtained. In addition, after adhering to the sliding parts and penetrating parts of the knob 21, it dries due to heat and becomes sticky and immobilized due to sugar, which prevents the knob 21 from sliding. Therefore, the weight of the food on the turntable 3 is accurately transmitted to the piezoelectric element 18. As a result, weight measurement cannot be performed accurately.

<Purpose> The present invention has been made in view of the above-mentioned drawbacks, and it is an object of the present invention to easily waterproof a weight detection device without affecting weight detection accuracy.

<Example> An example of the present invention will be described below with reference to FIG.

FIG. 1 is a detailed cross-sectional view of the main parts of the weight detecting device of the present invention, and the same parts as in the conventional example are given the same reference numerals and the explanation thereof will be omitted.

In the present invention, a flexible film 22, which is larger than the hole 1b and has an extremely thin thickness, is pasted onto the bottom wall 1a of the heating chamber so as to cover all the holes 1b, the protrusions 15a, and the knobs 21. The material of the film 22 has a heat resistance of 100° or more, for example, and the material of the knob 2
A polyester film having a thickness of about 20 to 60 μm is suitable as it does not hinder the movement of roller 1 and the running of roller 3b. Since this film 22 has sufficient flexibility, the influence on weight detection accuracy is less than a few grams.
Since the roller 3b is separated from the knob 21, the rotation of the roller 3b is not hindered, and the irregular movement when the roller 3b rides on the film is attenuated when the roller 3b reaches the top of the knob 21, so that it does not affect the weight detection accuracy.

This film 22 creates a gap between the bottom wall 1a of the heating chamber and the cover 15, and a gap between the cover protrusion 15a and the knob 2.
The gap 1 is completely sealed to completely prevent water and food dripping into the heating chamber 1 from affecting the weight detection mechanism 8. Furthermore, it also has the effect of reducing the step (dimension B) of the protrusion of the knob 21 from the cover 15a and smoothing the rotation of the roller 3b.

<Effects> In the present invention, a support roller that supports the turntable and rotates the bottom wall of the heating chamber is disposed inside the heating chamber, and is placed facing the hole provided on the roller rotation locus on the bottom wall of the heating chamber to transmit power. A body is provided, and when the support roller rotates, the force of the roller is transmitted to the piezoelectric transducer through the power transmission body, and the voltage generated in the piezoelectric transducer is detected and the piezoelectric transducer is placed on the turntable. In a weight detection device for a microwave oven configured to detect the weight of an object to be heated, the heating chamber is provided with a hole provided on the roller rotation locus in the bottom wall of the heating chamber and a power transmission body provided facing the hole. By pasting a flexible resin film on the bottom wall of the heating chamber, the piezoelectric transducer can be protected from water, and the movement of the power transmission body can be prevented from becoming unsmooth due to water or food. Parts that make up the device (e.g. cover 1)
Not only can the surface treatment in 5) be made inexpensive, but it also has the unique effect of smoothing the rotation of the roller when passing over the power transmission body (knob 21). It is.

[Brief explanation of the drawing]

Figure 1 is a detailed sectional view of the main parts of the microwave oven weight detection device of the present invention, Figure 2 is a side sectional view of the main parts of the microwave oven, and Figure 3 shows the bottom of the heating chamber with the turntable removed. 4 is an enlarged detailed sectional view of the turntable section, and FIG. 5 is a detailed sectional view of the main part of a conventional weight detection device. Symbols, 1a: heating chamber bottom wall, 1b: hole, 3b: roller, 21: power transmission body (knob), 22: film.

Claims (1)

[Scope of Claim for Utility Model Registration] A support roller that supports a turntable and rotates the bottom wall of the heating chamber is disposed within the heating chamber, and is placed facing a hole provided on the roller rotation locus on the bottom wall of the heating chamber. A force transmitting body is provided, and when the support roller rotates, the force of the roller is transmitted to the piezoelectric transducer through the force transmitting body, and the voltage generated in the piezoelectric transducing element is detected and placed on the turntable. A weight detection device for a microwave oven configured to detect the weight of a heated object placed therein includes a hole provided on the roller rotation locus on the bottom wall of the heating chamber, a power transmission body provided facing the hole, and A weight detection device for a microwave oven, characterized in that a flexible resin film is attached to the bottom wall of the heating chamber so as to cover the bottom wall of the heating chamber.