JPS6370133A - Weight sensor - Google Patents

Abstract

PURPOSE:To obtain a very thin weight sensor of high accuracy, by providing in flexible sections almost flush with plate springs to fix a fixed electrode plate and a mobile electrode plate respectively thereinside. CONSTITUTION:A pair of plate springs 3 and 4 are fixed on upper and lower mounting planes of block-shaped support members 1 and 2 and the plate springs 3 and 4 are provided with flexible sections 3b and 4b and inflexible sections 3c and 4c respectively. A fixed electrode plate 6 is fixed directly at the internal center of one inflexible section 3c through an insulation plate 5, while likewise a mobile electrode plate 7 is fixed directly inside the inflexible section 4c through the insulation plate 5. Moreover, a support frame 8' is fixed on a base and when a heavy object is placed on a tray 11, the tray 11 lowers against the flexible sections 3b and 4b. With this, the mobile electrode plate 7 lowers as compared to the fixed electrode plate 8 to gain a gap (g) proportional to the heavy object and thus the weight thereof is determined from an electrostatic capacitance generating in the gap (g).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sensor used to measure force, gravity IH, pressure, etc., and particularly to a weight sensor in a capacitive scale.

[Prior Art] A conventional fnffi sensor of this type is a capacitive (D-type weight sensor) in which a pair of leaf springs forms a donkey-pal structure scale, and a pair of electrodes are attached to the donkey pal. As a prior art, Japanese Patent Application Laid-Open No. 55-147317
No. 81008 (Fig. 10, Fig. 11), etc. exist, but in these, the mounting channel 21 which is the support member of the leaf spring 20 is The fixed electrode plate 22 and the movable electrode plate 23 constituting the capacitive sensor are separate parts. It can be attached from the shaped channel 21 to the inside (FIGS. 8 and 9) or outside (not shown) of the leaf spring 20.

[Problems to be Solved by the Invention] However, in such conventional technology, since the supporting member of the leaf spring is a channel-shaped molded product 21 having a U-shape,
There is a limit to the dimensional accuracy of the height H' between the leaf spring mounting planes 218 and 21b and the parallelism of the upper and lower mounting planes, and in order to maintain scale accuracy better than that of the window-shaped channel 21. The height between flat springs 21a and 2Ib must be increased, and when weight is applied to load point F, an abnormal force is applied to the mouth-shaped channel 21. This flexural deformation upsets the balance of the donkey pal movement, making it difficult to achieve the desired accuracy.

In addition, a fixed type (the singing board 22 and the movable electrode plate 23 are fixed as separate parts, and the rivets and screws 2 are attached via the mold attachment member 24).
Since it is fixed to the U-shaped channel wheel mentioned above in 5 etc., depending on the tightening strength of this fixed part, the fixed part may be displaced due to distortion during loading, and both electrode plates 22 may be affected by the load. The movement of the force toward the .23 was not accurately 4g, so high precision could not be expected, and it was extremely difficult to make the entire structure thinner.

[Means for Solving the Problems] In order to solve the above problems, the present invention solves the above-mentioned prior art [
Utility Model Application No. 61-81008" has a structure in which an electrode plate is provided on each of the central shield members, that is, a non-flexible part is provided on almost the same plane as the leaf spring, and fixed inside each of the non-flexible parts. The electrode plate and the movable electrode plate are fixed, and the fixed portion of the leaf spring is fixed to the upper and lower mounting planes of a thin block-shaped support member.

[Function] Since the support member 1.2 of the leaf spring 3.4 is cut out of a plate shape and made into a block shape, the height dimension 1-1 of the quadrilateral constituting the donkey pal is uniform, and The parallelism of the mounting plane of the leaf spring is accurate, and no abnormal distortion is caused to this temple when a load is applied.

In addition, since the fixed electrode plate and the movable electrode plate that make up the capacitance sensor are directly fixed opposite each other to the inside of the non-flexible part provided on almost the same surface as the leaf spring, there is no possibility of abnormal distortion in both electrode plates. The movement of the leaf spring is transmitted obediently without being transmitted. Further, the non-14 portion acts as a shield for the capacitance sensor composed of the two 'Fi electrode plates, thereby providing a highly accurate weight sensor with a thin structure.

[Examples] Examples of the present invention will be described in detail below with reference to the drawings.

1.2 is a support member. This support member 1.29 is a plate material that is generally stable in the thickness direction (in this example, 3 to 5
．． It is a block-shaped material that is made by cutting this board material into strips and has a thickness of 1" in height and the parallelism of the upper and lower mounting planes can be easily achieved.

3.4 is a leaf spring. This leaf spring 3.4 forms a pair,
The fixing portions 3a are each formed by punching out a piece of plate spring material.
, 4a and bending portions 3b, 4b are provided, and this leaf spring 3,
A non-first fin part 3C14C is connected to one of the fixing parts 3a and 4a of the temporary spring 3.4 on the same surface as the temporary spring 3.4.

The non-flexible portions 3c, 4c are connected to the non-deflectable fixed portions 3a, 4a of the leaf spring 3.4, and are located on the mounting plane of the block-shaped support member 1.2, so that the flexible portion 3b
, 4b obediently follows the deflection.

In this case, as an example of the pond, the temporary springs 3 and 4 and the non-flexible part 3
If c and 4c are connected as described above, it will be about BIU in terms of viscosity and assembly work, but in consideration of material removal, the plate springs 3 and 4 and the non-flexible part 3c are used.

Cut 4C and make a leaf spring 3.・Even if one end of the non-deflecting portions 3c, 4c is fixed to the non-deflecting fixed portions 3a, 4a of 1 and configured so as to be on the same plane as the leaf spring 3.4, J:ri(
(not shown), and non-flexible portions 3c-, 40' as shown in FIG.
(not visible in the figure) may be attached to the mounting plane of the support members 1 and 2 at one end thereof (eight parts without being cut from the leaf springs 3', 4').

A fixed electrode plate 6 is directly fixed by adhesive or the like via an insulating plate 5 to approximately the center of the inside of one of the non-flexible parts 3C, and the fixed electrode plate 6 is directly fixed to the inside of the other non-flexible part 4C. Similarly, the movable electrode plate 7 is directly fixed via the insulating plate 5, and the fixed parts 3a and 4a of the pair of leaf springs 3 and 4 are respectively attached to the upper and lower mounting planes of the support members 1 and 2. The support frame 8.8' is brought into contact with the leaf spring 3.4 so that the shape of the plate springs 3.
The support members 1.2 and 1.2 are held alternately against each other.
The temporary spring 3.4 and the support frames 8, 8- are fixed at once by welding, caulking, screwing, etc. (welding is used in this embodiment). At this time, the fixed electrode plate 6 and the movable electrode plate 7 is the gap 9
are located opposite each other in the non-flexible parts 3C and 4C, forming a capacitance sensor.

9.10 is a lead wire. The lead wires 9 and 10 are soft lead wires, and are pulled out from one end of the fixed electrode plate 6 and the movable electrode plate 7, respectively, so that no force is applied thereto.
The static capacitance generated between M is electrically extracted.

Reference numeral 11 denotes a receiver (2) on which a heavy object is placed, and one end thereof is fixed to the support frame 8.

With the above structure, when the support frame 8- is fixed to the base (not shown) and an Lffl object is placed on the tray 11, the plate spring 8- is bent by 3°4 with respect to the support frame 8' fixed to the base. Part 3
b, 4b, the plate 11 of the receiver is lowered, and along with this, the movable electrode plate 7 is lowered with respect to the fixed electrode plate 6, and a gap 9 is created in this gap 9, which is proportional to the weight of the object. The capacitance is converted into Φ capacitance as an element of the oscillator, and is displayed digitally on a display unit (not shown).

[Effects of the Invention] As described above, the effect of the present invention is that the mounting member of the leaf spring, which is the basic structure of the Donkey Pal, is a block-shaped support member, so that the height dimension and the parallelism of the mounting plane are The fixed electrode plate 6 and the movable electrode plate 7, which constitute the capacitance sensor, are fixed to a non-flexible part that has very little influence on the flexible part of the leaf spring. Because of this, the change in the deflection part of the leaf spring is transmitted obediently, and the normal deflection is not applied to a part of the capacitance sensor, resulting in high precision with less instrumental error and eccentricity error. Since the electrode plate and the movable electrode plate are attached to the non-flexible part provided on almost the same surface as the leaf spring, it is possible to provide an extremely thin weight sensor.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a part of the weight sensor according to the present invention, Fig. 2 is a plan view, Fig. 3 is a side view, Fig. 4 is a sectional view taken along △-A', and Fig. 5 is a front view. 6 are sectional views taken along line B-B'. FIG. 7 shows another embodiment of the present invention. FIGS. 8 and 9 show a conventional weight sensor. FIG. 10 and FIG. 11 are plan views showing other conventional embodiments;
FIG. 1.2... Supporting member, 3.4... Leaf spring, 3c, 4c... Non-flexible portion, 5... Insulating plate, 6... Fixed electrode plate, 7... Movable electrode plate .

Claims (1)

[Claims] A pair of leaf springs are fixed to the upper and lower mounting planes of the support member to constitute a roberval mechanism, and the leaf springs are provided with a non-flexible part, and a fixed electrode plate is placed inside one non-flexible part, and a fixed electrode plate is provided inside one non-flexible part. A weight sensor, characterized in that a movable electrode plate is fixed to the inner side of the portion so as to face the fixed electrode plate.