JPH0727596A - Capacitance type weight sensor element and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [Object] The present invention relates to a weight sensor element used in a heating cooker, and an object thereof is to provide a stable element with little variation in sensitivity. A weight sensor element of the present invention includes a pair of flat plates 1 having a circular electrode at the center and at least one of which is non-conductive.
And 5 and the pair of flat plates 1 and 5 are held at a constant interval, the peripheral portion between the flat plates is fixed by an adhesive layer 4 having an L-shaped cross section. With this configuration, even if a predetermined amount or more of the adhesive forming the adhesive layer 4 is supplied and the adhesive layer 4 is molded to have a constant thickness, the excess adhesive is sucked into the L-shaped hollow portion. The diameter of the diaphragm that receives the load does not change. Therefore, it is possible to provide an element having less variation in sensitivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weight sensor used in a cooking device such as a microwave oven, and more particularly to a structure of a sensor element used in a weight detection unit and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5 (a), a sensor element used in this type of weight sensor has a lead-out terminal at a central portion on a rectangular flat plate 1 such as alumina whose corners are cut out. A circular thin-film electrode 3 having a portion 2 and a lead-out lead portion 2'is formed, and two flat plates 1 and 5 having the same shape are vertically arranged so that the circular electrode portions face each other, as shown in FIG. So that the cutout portions of the respective flat plates are aligned with the respective lead-out terminal portions 2 and 6 of the other flat plate, and the peripheral portion thereof is predetermined with an adhesive layer 4 such as sealing glass. Fixed so that it is at a fixed interval,
It was used as a capacitance type weight sensor element. The adhesive layer 4
The take-out lead portion 2'formed in the lower part of was formed of a material such as gold that does not react with the adhesive layer 4 such as sealing glass. Therefore, when external lead wires or the like are connected to the lead-out terminal portions 2 and 6 by soldering, a lead wire or the like is soldered to a part of the lead-out terminal portions 2 and 6 after being reinforced with a baking electrode such as silver. . When used as the weight detection part of a weight sensor such as a microwave oven, a flat bullet-shaped load point is fixed to the center of the upper surface of one flat plate, and the flat plate is deformed by the pressing force applied to the load point. The amount is detected as a change in capacitance formed by the upper and lower circular electrodes. (JP-A-55-27992)

[0003]

However, as described above, the adhesive layer 4 has a predetermined constant spacing.
In the case of the conventional capacitance type weight sensor element that is fixed by the above method, the cross-sectional shape of the adhesive layer is rectangular, so if the amount of adhesive layer supplied exceeds the specified amount, the adhesive layer expands to the left and right. However, the inner diameter of the concentric adhesive layer shrinks.
As a result, the sensitivity as the weight sensor element is determined by the inner diameter of the adhesive layer that fixes the flat plate, and thus is reduced, and the yield is reduced. Also, since the takeout terminal parts are formed in separate rectangular flat plates, it is necessary to turn them upside down when connecting the lead wires with solder, etc., which requires a lot of man-hours and the introduction of automatic machines. It had the problem of being difficult.

An object of the present invention is to provide a structure of a weight sensor element and a simple manufacturing method thereof, which solves the above conventional problems.

[0005]

In order to solve the above-mentioned problems, the weight sensor element of the present invention comprises a pair of flat plates having electrodes in the central portion, at least one of which is non-conductive, and the flat plates having a constant interval. In order to hold the same, the cross-sectional shape provided in the peripheral portion of the flat plate is fixed by an L-shaped adhesive layer.

Further, in the weight sensor element of the present invention, a pair of non-conductive flat plates having an electrode in the central portion are fixed by an adhesive layer so that the peripheral portions thereof are kept at a constant interval, One of the lead-out terminal portions of the pair of electrodes is connected to a conductive layer outside the adhesive layer, and the lead-out terminal portions of the pair of electrodes are formed on the same flat plate.

Further, when manufacturing the weight sensor element having the structure of the present invention, the concentric adhesive layers of the same shape, which are evenly divided and have the same inner diameter and alternately different outer diameters, are formed on a pair of flat plates. After the formation, the pair of adhesive layers may be fixed to each other so that the adhesive layers have an L-shaped cross-sectional shape. Therefore, it becomes a single adhesive layer forming process, and the process is simplified.
Further, on the pair of flat plates, after forming the same shape of the electrode portion and the lead-out terminal portion, when the pair of electrode portions are fixed to face each other, the lead-out terminal portions are connected by a conductive layer, This is a single electrode forming process, which simplifies the process.

[0008]

According to the present invention, even if a predetermined amount or more of the adhesive forming the adhesive layer is supplied and the adhesive layer is adhered so as to have a constant thickness, the cross-sectional shape of the adhesive layer is L-shaped. Since it is sucked into the L-shaped hollow portion by a force such as surface tension, the inner diameter of the adhesive layer does not change, but only the outer shape thereof changes. Therefore, the diameter of the diaphragm that receives the load does not change. For this reason,
Since the sensitivity of the weight sensor element does not change, a stable element can be obtained. Further, since the lead terminals of the upper and lower circular electrodes are formed on the same flat plate, when connecting lead wires or the like to each lead terminal by soldering, it is not necessary to invert the element, which reduces the number of steps. Further, since there is no inversion step, it is easy to introduce an automatic machine.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. The same components as those of the conventional weight sensor element are designated by the same numbers.

(Embodiment 1) FIG. 1 shows an outline 3 according to the present invention.
1 shows a 0 mm square capacitive weight sensor element. This figure shows
1 shows an external view of a capacitive weight sensor element having circular electrodes made of thin film gold having a diameter of about 12 mm according to the present invention. 7,
8 is a cutout portion formed on the alumina flat plate 5 having an upper plate thickness of about 0.6 mm, and 9 and 10 are lower plate thicknesses of about 0.
The notch portions formed on the 6 mm alumina flat plate 1 are shown. The cross section of XX ′ is shown in FIG. 2A, which shows that the cross section of the adhesive layer 4 having a height of about 50 μm is L-shaped. 11 is a width of about 1.
An adhesive layer having a width of 5 mm and an adhesive layer 12 having a width of about 2.0 mm formed on the flat plate 1 are formed so that the widths of the adhesive layers are different from each other. At this time, 13 which determine the inner diameter of the adhesive layer 4 were made to have the same diameter and a diameter of about 24 mm.

With such a structure, that is, the cross section of the adhesive layer is L
Since it is a mold, the adhesive layer is formed in a prescribed amount or more,
Even if two flat plates are stacked to form an adhesive layer having a predetermined thickness, the hollow portion of the L-shaped cross section of the adhesive layer, that is, the outer diameter of the adhesive layer 11 having a narrow width, A force such as surface tension causes the excess adhesive layer to be attracted to the outer portion, and the inner diameter of the adhesive layer 4 hardly changes and is stable. Therefore, the sensitivity as a weight sensor element hardly changes, and a stable element with little variation can be obtained.

A cross section taken along the line YY 'of FIG. 1 is shown in FIG. Reference numeral 6'denotes a lead-out lead portion of the circular electrode formed on the upper flat plate 5, and reference numerals 14 and 15 denote conductive layers for connecting the lead-out lead portion 6'formed on the upper and lower flat plates and the lead-out terminal portion 6, respectively. Shows. Therefore, as shown in FIG. 1, the extraction terminal portion 2 of the circular electrode formed on the lower flat plate 1 is formed on the lower flat plate 1, and the circular electrode formed on the upper flat plate 5 is 6 ′, It is connected to the lead-out terminal portion 6 through 14 and 15 in sequence and is formed on the flat plate 1. Therefore, the lead-out terminal portions 2 and 6 of the respective circular electrodes are formed on the same flat plate 1.

With such a structure, when lead wires or the like are soldered to the lead-out terminal portions 2 and 6 of the respective circular electrodes, they can be carried out from the same surface direction, and the number of manufacturing steps is greatly reduced. It Further, it is not necessary to invert the sensor element, and the introduction of an automatic machine becomes easy.

Although the adhesive layer 4 is circular in the first embodiment, the configuration of the present invention can be adopted even if the adhesive layer 4 has a polygonal shape such as a square shape, and the effect can be obtained. That is, if the adhesive layer 4 has a polygonal shape, the inner dimension thereof is constant, and the outer dimension thereof is alternately increased or decreased to change its width, the same effect as that of the present invention can be obtained. It is clear that it will be done. Further, in the first embodiment, the pair of flat plates are made insulative, but the flat plate on which the extraction terminal portion is not formed may have the structure of the present invention even if it is conductive. That is, a pair of lead terminal portions can be formed on the insulating flat plate, and the effect of the present invention can be obtained.

(Embodiment 2) Furthermore, when manufacturing such a weight sensor element, that is, forming an L-shaped adhesive layer or forming lead-out terminal portions of two circular electrodes on the same flat plate. In this case, the manufacturing process is complicated, for example, two adhesive layer forming steps are required, and two circular electrode forming steps are required.

Another method of manufacturing the adhesive layer of the capacitance type weight sensor element of the present invention used in Example 1 will be described below with reference to FIG. FIG. 1A shows a plurality of divided concentric adhesive layers 4 formed on an alumina flat plate 1 with some corners cut away. As shown in the figure, each of the plurality of divided parts has the same inner diameter, but is formed so that the width of the adhesive layer 4 changes so that the outer diameter alternately increases or decreases. The narrow adhesive layer 16 and the wide adhesive layer 17 are alternately formed. FIG. 2B shows a vertical solid line A of the flat plate 1 shown in FIG.
The figure which reversed about -A 'as a rotating shaft is shown. The same figure (b)
Is overlapped with (a) in the figure, a wide adhesive layer 17 is overlaid on the narrow adhesive layer 16, and a narrow adhesive layer is overlaid on the wide adhesive layer 17. As a result of 16 overlapping, if both are fixed in this state,
The adhesive layer 4 having the L-shaped cross section shown in FIG. 1 is easily formed. Therefore, on a pair of flat plates, evenly divided, and after forming an adhesive layer of the same shape of concentric circles having the same inner diameter and alternately different outer diameter, the pair of adhesive layers, the cross section of the adhesive layer By stacking and fixing the L-shaped adhesive layer, an adhesive layer having an L-shaped cross section can be formed in a single manufacturing process.

According to the conventional manufacturing method, for example,
Since a wide adhesive layer was formed on the lower flat plate, and an adhesive layer with the same inner diameter and a narrow width was manufactured on each of the upper flat plates in separate steps, and they were stacked and manufactured, Two steps were required to produce the layer. For this reason,
When the manufacturing method of the present invention is used, the number of steps is about half that of the conventional method.

(Embodiment 3) A method for manufacturing the electrodes of the capacitance type weight sensor element of the present invention used in Embodiment 1 will be described below.
This will be described with reference to FIG. FIG. 2A shows an electrode formed on an alumina flat plate 19 with both corners of the lower end cut out. Reference numeral 20 denotes a central circular electrode portion, 21 denotes a lead-out terminal portion having a lead-out lead portion 21 ', 22 denotes a lead-out lead portion, and 23 denotes a lead-out terminal portion. Two
1, 21 ′ and 22 are electrically connected to the circular electrode portion 20, respectively. Reference numeral 23 denotes an independent lead terminal portion that is not electrically connected to the circular electrode 20. FIG. 2B shows a flat plate 19 which is the same as the flat plate 19 shown in FIG. 4A but which is inverted with BB ′ shown in FIG. Therefore, when the inverted flat plate shown in FIG. 2B is placed on the flat plate shown in FIG.
The lead-out lead portion 22 "of the lower plate mate with the separate lead-out terminal portion 23 of the lower plate.
If a conductive adhesive 25 is applied to the ends of the lead-out lead portions 22 in advance, the circular electrodes 20 ″ on the upper flat plate are fixed to the lead-out lead portions 2 when the upper and lower flat plates are fixed.
2 "and the conductive adhesives 25" and 24 are connected to the takeout lead terminal portion 23. Therefore, this portion is formed as shown in FIG.
The conductive adhesive can also be used as a baked silver electrode for solder reinforcement, and can be baked and formed at the same time when baking and fixing an adhesive layer such as sealing glass. Therefore, the number of conventional processes does not increase. As described above, since the electrodes of the same shape are formed on the upper and lower flat plates, the lead-out lead portions of the upper and lower circular electrodes are formed on the same flat plate by a single manufacturing process in which the flat plates are simply turned upside down. I can do things.

According to the conventional manufacturing method, for example, the lower electrode is formed on the lower flat plate, the upper electrode is formed on the upper flat plate in different steps, and they are stacked to manufacture. Therefore, two steps were required to form the electrode. Therefore, when the manufacturing method of the present invention is used, the number of steps is about half that of the conventional method.

[0020]

According to the capacitance type weight sensor element of the present invention, the following effects can be obtained.

(1) Since the cross-sectional shape of the adhesive layer is L-shaped, even if the amount of the adhesive layer supplied exceeds the specified amount, the adhesive layer does not expand left and right and is absorbed in the L-shaped hollow portion. Since the inner diameter of the concentric adhesive layer does not change, the sensitivity as a weight sensor element does not change and is stable.

(2) Since the lead portions for taking out the upper and lower circular electrodes are formed in the same flat plate shape, when connecting the lead wires with solder or the like, it is not necessary to turn them upside down, and it is simple and the number of steps is small. Be reduced. Moreover, since there is no inversion, it is easy to introduce an automatic machine.

(3) Since the adhesive layer is divided into even numbers, the inner diameter is the same, and the outer diameter is alternately set to be large and small, the layers are L-shaped in cross section simply by overlapping. An adhesive layer can be formed.

(4) The lead electrodes for the circular electrodes can be formed on the same plane simply by reversing and stacking the flat plates on which the same electrode shape is formed.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a weight sensor element according to an embodiment of the present invention.

FIG. 2 is a sectional view of an essential part of the weight sensor element.

FIG. 3 is a plan view showing a configuration of an adhesive layer of the weight sensor element.

FIG. 4 is a plan view showing a configuration of electrodes of the weight sensor element.

FIG. 5 is a configuration diagram of a conventional weight sensor element.

[Explanation of symbols]

 1 flat plate 2 lead-out terminal portion 4 adhesive layer 5 flat plate 6 lead-out terminal portion

Claims (4)

[Claims] 1. A pair of flat plates having electrodes in the central portion, at least one of which is non-conductive, and an adhesive layer having an L-shaped cross section provided in the peripheral portion of the flat plates for holding the flat plates at a constant interval. And a capacitance type weight sensor element. 2. A pair of non-conductive flat plates having an electrode at the center thereof are fixed at their peripheral portions with an adhesive layer so as to maintain a constant interval, and one lead-out portion of one of the pair of electrodes is secured. A capacitance-type weight sensor element, which is connected to a conductive layer outside the adhesive layer and has lead-out lead portions of the pair of electrodes formed on the same flat plate. 3. A concentric adhesive layer is formed on a pair of flat plates that is evenly divided and has the same inner diameter and alternating outer diameters. Then, the pair of adhesive layers are L-shaped. The method for manufacturing an electrostatic capacitance type weight sensor element according to claim 1, wherein the method is carried out so as to be fixed. 4. A conductive adhesive layer is provided between the lead-out lead portions when the pair of flattened electrode portions and lead-out lead portions are formed on a pair of flat plates and then the pair of electrode portions are fixed by facing each other. 3. The method for manufacturing an electrostatic capacitance type weight sensor element according to claim 2.