JP2000329625A - Capacitance-type load sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a capacitance-type load sensor where the detection sensitivity has been improved by narrowing the interval between electrodes. SOLUTION: The capacitance-type load sensor is provided with first and second electrode bodies 1 and 2 that are arranged opposingly in parallel with a specific gap and a third electrode body 3 that is arranged between the electrode bodies. Especially, the peripheral part of the third electrode body 3 is laminated by insulation films 6 and 7. Then, by allowing the insulation films to function as an insulation spacer for the first and second electrode bodies 1 and 2, the opposing distance between the electrodes is narrowed, capacitance is increased, and at the same time the change in capacitance for a load is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitive load sensor having a small size and high load detection sensitivity.

[0002]

2. Related Background Art A capacitive load sensor is basically composed of a pair of electrode bodies (first and second electrodes) composed of two disk-shaped metal plates opposed to each other with a small gap therebetween. Body) to form a capacitor. The load functions to measure the load based on a change in the distance between the electrode bodies that bends under a load, and a change in the capacitance of the capacitor formed by the pair of electrode bodies. Recently, for example, as shown in FIG. 4, a third electrode body 3 is disposed between the first and second electrode bodies 1 and 2, and a capacitor is formed between the third electrode body 3 and the third electrode body 3, respectively. In some cases, the detection sensitivity has been improved.

[0003] The first and second electrode bodies 1 and 2 are opposed to each other at a predetermined interval with their peripheral edges supported by an annular spacer 4 having a predetermined thickness. Further, as shown in FIG. 5, for example, the third electrode body 3 has a peripheral portion held by a pair of semi-circular insulating spacers 5 and the first and second electrode bodies 1 formed by the spacers 4. , 2 are arranged in a space (in the space) insulated from the respective electrode bodies 1, 2.

The first to third electrode members 1, 2, 3
Is made of a disk-shaped metal material such as iron or stainless steel. The insulating spacer 5 is manufactured using a highly insulating engineering plastic such as POM (polyoxymethylene), PI (polyimide), and PEN (polyethylene naphthalate). In some cases, the engineering plastic is used for the spacer 4. However, the first and second electrode bodies 1 and 2 are electrically connected to form a capacitor formed between the spacer and the third electrode plate 3. When connecting in parallel, it may be manufactured using a metal material such as stainless steel.

[0005]

In order to increase the detection accuracy of this type of capacitance type load sensor, it is necessary to increase the change in capacitance with respect to the pressing force (load) applied to the pair of electrode plates. However, if the amount of deflection of the electrode plate with respect to the load is increased, if the deflection of the electrode plate exceeds its elastic limit, plastic deformation occurs and hinders subsequent measurements, so the amount of deflection is increased. There is a limit to It is also conceivable to set the facing area between the pair of electrodes to be large, but it cannot be denied that the load sensor becomes large.

On the other hand, it is conceivable to reduce the facing distance between the pair of electrodes. Specifically, 3 shown in FIG.
First and second electrodes 1 in a load sensor having a layered structure,
It is conceivable that the distance d facing each of the second and third electrodes 3 is reduced. However, even if the thickness of the flange portion 5a for defining the above-mentioned facing distance d of the insulating spacer 5 attached to the peripheral portion of the third electrode plate 3 is reduced, there is a limit in manufacturing. For this reason, there is a problem in increasing the detection sensitivity by reducing the facing distance d between the electrodes.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and a purpose thereof is to provide a small-sized capacitive load sensor in which the opposing interval between electrodes is narrowed to increase the detection sensitivity. It is in.

[0008]

In order to achieve the above-mentioned object, a capacitive load sensor according to the present invention comprises first and second electrode bodies which are opposed to each other at a predetermined interval, And a third electrode body disposed between the first and second electrode bodies, particularly at a peripheral portion of the third electrode body between the first and second electrode plates. And an insulating film forming an insulating spacer.

That is, by attaching an insulating film to the peripheral portion of the third electrode body and making the insulating film function as an insulating spacer for the first and second electrode bodies, the facing distance between these electrode bodies can be reduced. The thickness of the insulating film is set to be sufficiently small. Preferably, as described in claim 2, the third electrode body is sandwiched from both sides with an insulating film having a circular hole that opens the main surface of the disc-shaped third electrode body, and laminated.
Using the insulating film as an insulating spacer for defining an opposing distance between the electrodes, the third electrode body is used for the first and second electrodes.
It is characterized by being arranged between the electrode bodies. On this occasion,
The first and second electrode bodies are separated from each other by a distance obtained by adding the thickness of two insulating films to the thickness of the third electrode body as a spacer for supporting the peripheral portions of the first and second electrode bodies. What is necessary is just to be an opposing arrangement.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A capacitance type load sensor according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view showing a schematic configuration of a capacitance type load sensor, and FIG. 2 is a sectional view showing an assembly structure thereof. This capacitance type load sensor includes first and second disc-shaped electrode bodies 1 and 2 made of stainless steel or the like, and a disc-shaped first and second electrode body made of stainless steel or the like smaller in diameter than these electrode bodies 1 and 2. 3 electrode bodies 3. The first and second
Supporting the peripheral portions of the electrode bodies 1, 2
Are made of stainless steel or the like, and also function as a connecting body for electrically connecting these electrode bodies 1 and 2 to each other. In particular, the spacer 4 has an outer diameter equal to that of the first and second electrode bodies 1 and 2, and the third electrode body 3 is disposed inside the spacer 4 so that the third electrode body 3 is disposed inside the spacer. It has a substantially annular shape having an inner diameter larger than the outer diameter.

A part of the annular spacer 4 has a third
A notch 4a for leading out a lead body 3a protrudingly formed on the periphery of the electrode body 3 is formed, and the first and second electrode bodies 1 and 2 are provided at a portion opposite to the notch 4a.
2, a lead body 4b common to the projections 2 is formed so as to protrude. The thickness of the spacer 4 is set to be the thickness of the third electrode body 3 plus the thickness of two insulating films 6 and 7 described later.

On the periphery of the spacer 4, insulating films 6, 7 as insulating spacers for the first and second electrode bodies 1, 2 are mounted. These insulating films 6 and 7 are made of PET (polyethylene terephthalate).
A flexible plastic film made of a highly insulative laminated film having an adhesive applied to the surface thereof and having circular holes 6a and 7a slightly smaller in diameter than the third electrode body 3. The main surface of the electrode body 3 is opened (exposed), the electrode body 3 is sandwiched from both sides, and laminated.

The lamination is performed by heating the two insulating films 6 and 7 sandwiching the electrode body 3 by using a hot press while applying pressure from both sides thereof. As a result, the two insulating films 6 and 7 sandwich the third electrode body 3 therebetween, and open the main surface of the electrode body 3 largely by the circular holes 6a and 7a to be attached to the peripheral edge of the electrode body 3. Is done. On the outer peripheral side of the third electrode body 3, the insulating films 6, 7 are adhered to each other and integrated. Thus, the two insulating films 6, 7 attached to the third electrode body 3 in this manner are connected to the third insulating film 6, 7 as shown by the two-dot chain line in the figure.
The outer periphery of the electrode body 3 is cut slightly larger than the outer periphery of the electrode body 3 so that the electrode body 3 can be housed inside the above-described annular spacer 4.

The first and second electrode bodies 1 and 2 have an annular spacer 4 interposed therebetween, and the third electrode body 3 on which the insulating films 6 and 7 are mounted as described above is connected to the spacer 4. And are superposed and joined together by ultrasonic welding or the like as shown in FIG. As a result,
The first and second electrode bodies 1 and 2 are arranged in parallel at an interval defined by the spacer 4. A third electrode body 3 disposed between the electrode bodies 1 and 2 is opposed to each of the electrode bodies 1 and 2 in parallel with each other via the insulating films 6 and 7, and the facing interval is insulated. It is a minute gap defined by the thickness of the films 6,7.

Therefore, according to the capacitive load sensor having such a structure, the distance between the first and second electrode bodies 1 and 2 facing the third electrode body 3 is determined by the thickness of the insulating films 6 and 7. Can be made sufficiently small as a minute gap defined by the following formula, so that the capacitance itself can be increased. Further, the change in the capacitance with respect to the load can be made sufficiently large. In other words, even if the deflection of the first and second electrode bodies 1 and 2 subjected to the load is reduced, the distance between the first and second electrode bodies 1 and 2 facing the third electrode body 3 is sufficiently small. Can be made sufficiently large. Moreover, the capacitance and the amount of change with respect to the load can be increased without increasing the facing area between the electrodes, so that a small load sensor with high detection sensitivity can be realized.

In particular, the thickness of the insulating films 6 and 7 depends on the thickness of the insulating spacer 4 made of a conventional engineering plastic.
Since the thickness of the flange portion 4a is sufficiently thin compared to the thickness of the flange portion 4a and there is almost no possibility that the thickness of the flange portion 4a is limited due to manufacturing restrictions, it is easy to set the thickness to a specification.
Moreover, the load does not directly act on the insulating films 6 and 7 themselves, and the load acting on the first and second electrode bodies 1 and 2 is received by the spacers 4 at the peripheral edges thereof. There is no possibility that the thickness of the insulating films 6 and 7 will change. Accordingly, the opposing intervals between the first and second electrode bodies 1 and 2 and the third electrode body 3 disposed therebetween can be maintained constant over a long period of time by the insulating films 6 and 7. Effects such as improvement in measurement reliability can be obtained.

Further, at the time of manufacture, as described above, the two insulating films 6, 7 are sandwiched with the third electrode body 3 interposed therebetween.
It is only necessary to laminate the first and second electrode bodies 1 and 2 by arranging the first and second electrode bodies 1 and 2 inside the spacer 4, so that the production is simple and the production cost can be reduced. And the like. When the capacitance type load sensor having the above-described structure is housed in a predetermined case 8, for example, as shown in FIG. 3, a load is stably applied to the center of the first and second electrode bodies 1 and 2 from outside. It is preferable to provide pressure bodies 9a and 9b for adding pressure. That is, at the center of the first and second electrode bodies 1 and 2, the tips of the pressurizing bodies 9 a and 9 b formed in a tapered shape are perpendicular to the first and second electrode bodies 1 and 2. Fixed to. The fixing of the pressurizing bodies 9a, 9b to these electrode bodies 1, 2 is performed by spot welding or the like. And upper case 8a and lower case 8b
When accommodating the capacitive load sensor in the case 8 composed of the following, the other ends of the pressurizing bodies 9a and 9b are inserted through the through holes 8aa and 8bb provided in the cases 8a and 8b, respectively. So that a load is applied to the capacitance type load sensor via the pressurizing members 9a and 9b.

The lead member 4 led out of the spacer 4
a and a lead body 3a protruding from the third electrode body 3
Is led out of the case 8 through a lead lead-out gap (not shown) formed at the joint between the upper case 8a and the lower case 8b, and is connected to a measurement circuit (not shown). Thus, according to the capacitive load sensor housed inside the case 8 in this manner, the pressing bodies 9a, 9b
Thus, a load can be stably and accurately applied to the respective center positions of the first and second electrode bodies 1 and 2 so that the measurement accuracy can be sufficiently improved. In addition, since the pressing members 9a and 9b are fixed to the first and second electrode members 1 and 2, respectively, even if a force is applied to the pressing members 9a and 9b from a direction other than the vertical direction, the pressing members 9a and 9b are thereby fixed. Pressing body 9
The a and 9b do not touch the through holes 8aa and 8bb of the cases 8a and 8b to interfere with each other. This has the effect that the measurement accuracy is not impaired and the case 8 is not damaged. Can be played.

The pressing members 9a and 9b are fixed to the first and second electrode members 1 and 2 by spot welding or the like at the time of fixing the first and second electrode members 1 and 2 via the spacer 4. Since it is sufficient to perform the operations in a lump, there is almost no fear that the manufacturing process becomes complicated. Further, since the pressurizing bodies 9a and 9b can be integrated with the first and second electrode bodies 1 and 2 by the above-described welding, effects such as simplification of the assembling work can be achieved. Can be

The present invention is not limited to the above embodiment. For example, the material of the insulating films 6 and 7,
The thickness may be determined according to the specifications. In the embodiment, the electrode leads (leads 4a) of the first and second electrode bodies 1 and 2 are taken out from the spacer 4, but it is needless to say that the electrode leads are taken out from one of the electrode bodies 1 and 2. It is possible. Furthermore, the size (electrode area) and thickness of the electrode bodies 1, 2, and 3 may be determined according to the magnitude of the load to be measured.
In addition, the present invention can be variously modified and implemented without departing from the gist thereof.

[0021]

As described above, according to the present invention, the first and second parallel and oppositely disposed first and second gaps are provided.
Since the insulating film is used as a spacer of the third electrode body disposed between the electrode bodies, the distance between the electrodes can be sufficiently narrowed to increase the capacitance, and the size can be reduced with high measurement sensitivity. A capacitance type load sensor having a simple configuration can be realized. In particular, it is possible to realize a capacitance-type load sensor that improves the detection accuracy without increasing the electrode area.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view for explaining a schematic configuration of a capacitive load sensor according to an embodiment of the present invention and a manufacturing process thereof.

FIG. 2 is a sectional view showing a schematic configuration of the capacitive load sensor shown in FIG.

FIG. 3 is a diagram showing a configuration example when the capacitance type load sensor shown in FIG. 1 is housed in a case.

FIG. 4 is a cross-sectional view showing a schematic configuration of a conventional capacitive load sensor having a three-layer structure.

FIG. 5 shows a third example of the capacitance type load sensor shown in FIG.
The figure which shows the structure of the electrode body of this, and the insulating spacer which supports this 3rd electrode body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st electrode body 2 2nd electrode body 3 3rd electrode body 4 Spacer 6, 7 Insulating film (insulating spacer) 6a, 7a Circular hole 8 Case 9a, 9b Pressing body

Claims (2)

[Claims] 1. A first device, which is opposed to a predetermined distance.
And a second electrode body, and a third electrode body disposed between the first and second electrode bodies, wherein the third electrode body is mounted on a peripheral portion thereof and the first electrode body is mounted on the first electrode body.
A capacitive load sensor comprising an insulating film forming an insulating spacer with the second electrode plate. 2. The insulating film has a circular hole that opens a main surface of a disc-shaped third electrode body, and is laminated by sandwiching the third electrode body from both sides thereof. The capacitance type load sensor according to claim 1, wherein the capacitance type load sensor is attached to a peripheral portion of a body.