JPH047452B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to capacitive scales.

Conventional capacitive scales generally have the following structure.

In the first example, as shown in FIG. 1, a long machine 2 as a first lever and a short machine (not shown) as a second lever are combined on a fulcrum 1, and the end 2a of the long machine 2 as a first lever is assembled.
A coiled spring 3 is connected to the coiled spring 3, and the weight W1 loaded on the long machine 2 is converted into a displacement of the coiled spring 3. This displacement is detected at one point 2b of the long machine 2, and this is detected by the two electrode plates. A capacitance type scale that is linked to one movable electrode plate 4 of the electrode plates constructed of the above, and converts the capacitance generated between the two electrode plates g1 into a weight value to display the weight.

In the second example, as shown in Fig. 2, a long lever 2' as a first lever and a short lever (not shown) as a second lever are combined on a fulcrum 1' to create a long lever 2' as a first lever. A platform scale in which the strain body 5 of the Roberval mechanism is connected to the end 2a', and as a third example, one of the strain bodies 5 of the Roberval mechanism is fixed to a base, and the other is a load receiving plate. However, the scale in the first example has a movable electrode plate 4.
The displacement is not a parallel motion but a scissor opening motion, and the change in capacitance with respect to the load is not linear, making it difficult to achieve accuracy. In particular, in order to guarantee accuracy, the area of the two electrode plates must be increased. This increases the size and weight of the electrode plate.

In the second example, the precision is high, but the structure around the strain-generating body 5 is complicated, the strain-generating body itself is expensive, and the assembly cost is high.

In the third example (not shown), both the substrate and the load receiving plate require rigidity, and the shape of the strain body itself becomes large and heavy, resulting in extremely high cost.

Based on the above-mentioned drawbacks, the present invention aims to provide a new scale that forms an extremely simple strain-generating body without using a coiled spring, can be made lightweight and thin, is easy to assemble, and is inexpensive.

Examples 3-a, 3-b, 4-a, 4-
This will be explained in detail based on Figures b and 5.

Reference numeral 10 denotes a support for a beam-like flexure body to be described later. This support 10 is made of a substantially thick metal material by bending both ends of an elongated plate, cutting off the bent piece 10a into a U-shape, and having a sharp blade portion 1 cut off at the bottom.
0b and ribs 10c are provided on both sides of the bottom surface to make it a reinforced and rigid body.

11 is a beam-like strain body. This beam-like strain body 11
is made of a thick piece of steel with spring properties, formed into an elongated shape, with a narrow part 11a and a stopper hole 11b made slightly narrower at both ends, and turned edges for reinforcement on both sides of the middle part. The elastic body 12 is fixed to the plate 13, which is provided with a portion 11c and stop holes 11d and 11d', and the stop hole 11d has a hanging hole 12a formed by a plate spring.
It is fixed with rivets 14 or screws.

Reference numeral 15 denotes one of the two electrode plates, which is a relatively small movable electrode plate. This movable electrode plate 1
5 is a fixing hole 11 provided in the center of the beam-shaped strain body 11 with a fixing screw 18 through the fixing hole 15b while insulating the center portion 15a with upper and lower insulating plates 16 and 17;
It is fixed at d′.

19 is the other electrode plate, which is a fixed electrode plate. A clearance hole 19a for the set screw 18 is provided in the center of the fixed electrode plate 19, and a set hole 19a is provided at both ends.
b is provided, and this stop hole 19b is provided with an upper and lower insulating plate 2.
One piece 23a of a flexible elastic body 23 made of a plate spring or the like is fixed by fitting it with a rivet 22 or a screw, and a receiving plate 24 is brought into contact with the other piece 23b of this elastic body 23. Align the rivet 2 with the stopper hole 11b of the strain body 11 through the stopper plate 25.
6 or fix it with screws. At this time, the movable electrode plate 15 and the fixed electrode plate 19 are aligned in their centers so that they are parallel to each other, and the two electrode plates 1
5, 19 and the beam-like strain body 11 are integrally formed.

The integrated beam-like strain body 11 can be freely placed on the sharp edge portion 10b provided on the support 10 with the narrow width portions 11a at both ends thereof, and is detachable from the support 10.

27 is a base, 28 is a lever, and 29 is a cover. Base edges 30, which are fulcrums, are arranged at the four corners of the base 27, and a support 10 is fixed at the center, and the two electrode plates 1 are mounted on this support 10.
A beam-like flexure element 11 on which elements 5 and 19 are arranged is mounted. At this time, the hanging hole 1 provided in the elastic body 12
The directions of 2a are directed toward base edges 30, which are fulcrums provided at the four corners of the base 27, respectively.

The four levers 28 have the same shape, and each has a fulcrum engaging portion 28a, a force point engaging portion 28b, and an action point engaging portion 28c, and each fulcrum engaging portion 28a is attached to the base 27. The base edge 30, which is a fulcrum at the four corners provided, is engaged, and the action point engaging portion 28c is engaged with the hanging hole 12a of the elastic body 12.

The cover 29 is a part that is loaded with weight, and like the base 27, there are cover edges 3 at the four corners that are the focus.
1 is fixed, and this cover edge 31 is freely engaged with each force point engaging portion 28b provided on the aforementioned lever 28 via an intermediate edge 32.

When weight is loaded on the cover 29 with the above configuration, this weight is concentrated from four directions on the action point engagement portion 28c of the lever 28 using the lever ratio of the lever 28, and is transmitted through the elastic body 12 to the beam-like strain body. The beam-like strain body 11 is slightly bent from the center in proportion to the weight, using the sharp edge portion 10b provided on the support 10 as a fulcrum. When the beam-shaped flexural body 11 is deflected, the movable electrode plate 15 fixed to the beam-shaped flexural body 11 descends perpendicularly to the fixed electrode plate 19 while remaining parallel to the fixed electrode plate 19. A gap g' is formed between the movable electrode plates 15. At this time, the elastic body 12 absorbs and corrects the positional deviation of the fulcrum engaging portion 28a due to, for example, machining accuracy or mounting of the base edge 30, or dimensional accuracy, and always maintains the lever ratio of the ram 28 constant. . Also elastic body 2
3 is a flexible elastic body 23 that prevents the fixed electrode plate 19 from warping due to the deflection of the beam-like flexural body 11 due to the load.
absorb it and keep it in a flat state at all times. In this way, a gap is established between the fixed electrode plate 19 and the movable electrode plate 15.
The amount of change in capacitance that occurs at g' is converted into weight using an electronic component and displayed as a weight.

As mentioned above, the strain-generating body for detecting weight is usually made of general steel material, and is small and thin, so as mentioned at the beginning, it is possible to provide a compact and thin scale, and the two electrode plates The sensor section composed of 15 and 19 and the beam-like flexure element 11 are integrated, and the integrated beam-like flexure element 11 can be attached to and detached from the support 10, reducing assembly man-hours and improving production. Furthermore, since the elastic bodies 12 and 23 automatically absorb and correct dimensional deviations, excessive deflections, etc. as described above, they have various effects such as being able to provide a scale with higher precision.

[Brief explanation of drawings]

FIG. 1 is a simplified side view of a first example of a conventional configuration. FIG. 2 is a simplified side view of a second example of the conventional configuration. The following are drawings in the present invention.
Figure 3-a is a plan view of the combined support body 10 and beam-like flexure element 11, and Figure 3-b is a view of the combination of support 10 and beam-like strain body 11.
It is a side view with a base 27 and a cover 29 added to the figure. Figure 4-a shows the support body 10 and the beam-like strain body 11.
Fig. 4-b is a side view of Fig. 4-a. FIG. 5 is an exploded perspective view of the main parts. 10...Support body, 10b...Sharp blade portion, 11...
... Beam-like strain body, 15... Movable electrode plate, 19... Fixed electrode plate, 12, 23... Elastic body.

Claims (1)

[Claims] 1. In a capacitive scale, a support, a beam-like flexural body, and two electrode plates are provided, and one movable electrode plate 15 is connected to the beam-like flexure body. The fixed electrode plate 19 is insulated and fixed to the center part, and the other fixed electrode plate 19 is insulated and fixed to both ends of the beam-like strain body through the elastic body 23 so as to be parallel to the one movable electrode plate 15. Capacitive scale. 2. The capacitive scale according to claim 1, wherein the support has sharp blades at both ends, and the support and the beam-like strain body are detachable. 3. The capacitance according to claims 1 and 2, wherein the load is transmitted to the beam-like flexure body through an elastic body 12 fixed to the beam-like flexure body. Type scale.