JPH10142040A - Weight-measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly attenuate vibrations of a load cell by a compact and simple apparatus when a weight is measured, and enable high-speed highly accurate measurements, by providing the load cell which detects the weight from a shift of a movable part and outputs a weight signal, and a magnetic damper having a cylindrical member of good conductivity and a magnetic circuit generating a magnetic flux. SOLUTION: When an object M to be measured is placed on a measurement saucer 5a, a strain gauge 2 incorporated in a bridge circuit 3 detects a distortion amount corresponding to a change of a movable part 1c of a load cell 1 and outputs a weight signal. The weight signal includes a vibration component consequent to an up-down movement of the cell 1 in addition to a weight of the object M to be measured. A brake force (attenuation force) of a magnetic damper 9 is proportional to a relative moving speed of a cylindrical member 6 and a square of an interlinking magnetic density and, inversely proportional to a resistivity of the member 6. Therefore, the magnetic damper is constituted of a member having a small resistance in a circumferential direction, a permanent magnet 8b is formed of an anisotropic sintered magnet of large coercive force, and a yoke main body 8a and a center yoke 8c are formed of ferromagnetic material of large magnetic permeability, thereby making the apparatus compact and capable of performing high-speed calculations.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weighing device using a load cell, and more particularly to a weighing device which improves the response of a weighing device having a low maximum weighing value of 300 gr or less.

[0002]

2. Description of the Related Art Conventionally, when weighing an object to be weighed, a weighing device incorporating a load cell having a fixed portion fixed to a base and a movable portion to which the object is loaded is used. . This load cell detects the displacement of the movable part with a strain detection element, converts this into an electric signal corresponding to the weight of the object to be weighed, and outputs it.However, a low weighing load cell generally has a small damping constant, It takes time to converge the electric signal, and the response is low.

In order to remove the AC component contained in the output signal from the load cell by free vibration, a low-pass filter is provided in the signal processing circuit, and the weighing device is improved in response by electrically removing the signal. General.

On the other hand, as an electronic balance configured to suppress the free vibration itself of the load cell, an electromagnetic force balance type using a force coil is known. This electronic scale
Since the deviation signal detected by the zero detector is differentiated and applied to the electromagnetic coil of the force coil, a much stronger damping function can be provided than a mechanical type.

[0005]

However, the former low-pass filter has a problem that the response becomes poor when the cutoff frequency is lowered. In response to this, it is conceivable to increase the cutoff frequency of the low-pass filter by increasing the natural frequency of the load cell and shorten the response time when weighing the object. However, in the case of a low weighing device having a maximum weighing value of 300 gr or less, since the natural frequency is low due to a small spring constant, the cutoff frequency of the low-pass filter cannot be increased. There was a problem that an accurate one could not be obtained.

[0006] In the case of the latter electromagnetic force balance type balance, since the weight is detected by the null method, when a current proportional to the displacement is applied to the coil, heat is generated and the resistance value of the coil increases. As the heat is transmitted to the magnet and the magnet temperature rises and the magnetic flux density falls, the electromagnetic force decreases,
In particular, it was necessary to use a magnet with little temperature dependence and to perform temperature correction.

It is noted that many rare earth magnets having a large coercive force have a high temperature dependency (a large temperature coefficient), and an alnico-based magnet having a low temperature dependency has a low magnetic density, so that miniaturization is difficult. There was a problem.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and quickly attenuates the vibration of the load cell at the time of weighing to perform high-speed and high-precision weighing. It is intended to provide.

[0009]

In order to achieve the above object, a weighing device of the present invention has a fixed portion fixedly supported on a base and a movable portion to which the weight of an object to be weighed is added. A load cell that detects the weight of the object to be weighed corresponding to the displacement of the part and outputs a weight signal, and further includes a good conductor attached to the movable part of the load cell and having an axial direction set in the moving direction of the movable part. And a magnetic circuit including a permanent magnet and a magnetic circuit that generates a magnetic flux in a direction crossing the peripheral wall of the cylindrical member.

[0010] According to the above configuration, a cylindrical member having a small electric resistance value made of a good conductor whose axial direction is set to the moving direction of the movable portion is provided in the movable portion of the load cell in the gap of the magnetic circuit having a high magnetic flux density. Since it has a magnetic damper with a large braking force inserted into the load cell, the vertical vibration of the movable part of the load cell during weighing is suppressed with a large braking force,
The responsiveness of the low-weighing weighing device is improved, and the restraining force is zero when the movable portion of the load cell is at rest. Therefore, there is no possibility that the weighing accuracy is reduced. Furthermore, since the magnetic damper has a magnetic circuit including a permanent magnet and does not require an electric circuit, the structure is simplified and energy is only consumed as eddy current loss. Moreover, because of low energy consumption and little heat generation, using a rare-earth magnet with high temperature dependency but high coercive force,
The magnetic damper can be downsized.

In a preferred embodiment, the magnetic circuit of the magnetic damper includes a yoke main body having a peripheral wall facing the outer periphery of the cylindrical member and an end wall at one end of the yoke main body, and the cylindrical member is erected on the end wall. A magnetic path forming member comprising a central yoke opposed to the inner periphery of the magnetic circuit, and the cylindrical member is connected to a movable portion of the load cell via a support positioned outside the magnetic circuit. I have. With this configuration, the structure of the magnetic circuit is simplified. Further, since the support is located outside the magnetic circuit 8, the material of the support 7 can be freely selected without particular consideration of the electric resistance value, magnetic characteristics, and the like.

In a preferred embodiment, the magnetic circuit of the magnetic damper includes a yoke having a peripheral wall facing the outer periphery of the cylindrical member, a central column facing the inner periphery, and an end wall connecting one end of the yoke. And a magnetic path forming member comprising a ring-shaped permanent magnet provided on the outer periphery of the central column portion and magnetized in the radial direction, wherein the cylindrical member includes a support member located outside the magnetic circuit. The load cell is connected to a movable portion of the load cell via the load cell. With this configuration, the magnetic flux in the radial direction by the permanent magnet directly crosses the peripheral wall of the cylindrical member in the radial direction and reaches the peripheral wall, and does not spread in the axial direction. Therefore, the density of the magnetic flux that crosses the cylindrical member in the radial direction increases. As a result, the braking force of the magnetic damper increases, and the responsiveness of the low-weighing weighing device can be improved.

Further, in a preferred embodiment, an A / D converter for converting a weight signal output from the load cell into a digital signal in accordance with the displacement of the movable portion of the load cell, and filtering the digital signal to reduce a vibration component. Digital filtering means for removing.
In this configuration, since a digital filter is used, a weight signal from which a vibration component has not been removed is input to the A / D converter at the preceding stage. However, the movable portion of the load cell is moved by the braking force of the magnetic damper. Is suppressed, the vibration component of the weight signal input to the A / D converter is reduced. Therefore, the input voltage range (dynamic range) of the A / D converter can be expanded, the resolution of the A / D converter can be increased, and the measurement accuracy can be improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration diagram of a weighing device according to the first embodiment of the present invention. The weighing device includes a load cell 1 for detecting the weight of an object M, a magnetic damper 9 including a cylindrical member 6 formed of a good conductor and a magnetic circuit 8, a bridge circuit 3, and a signal processing circuit 4. ing.

The load cell 1 includes a fixed portion 1a fixed to a base F, upper and lower beam portions 1b, and these beam portions 1b.
b, the movable portion 1c supported by the fixed portion 1a via
Notch portions 1d are formed at the connecting portions of the upper and lower beam portions 1b, the fixed portion 1a, and the movable portion 1c, respectively. Strain gauges 2 are attached to the surfaces of the notch portions 1d, respectively. The gauge 2 is connected to a bridge circuit 3, and the output of the bridge circuit 3 is input to a signal processing circuit 4 to calculate a weighing value, and a weighing signal indicating the weighing value is output from the signal processing circuit 4.

As shown in FIG. 3, the signal processing circuit 4
Is the amplifier 14, the ancheerous filter 15, the A / D
It comprises a converter 16 and a digital filter processing section (digital filtering means) 17. The weight signal output from the bridge circuit 3 is amplified by an amplifier 14 and then A / A
Due to the relationship with the sampling frequency of the D converter 16, a certain frequency or more is removed, and the aliasing error is removed.
The signal is converted into a digital signal by the D converter 16. Then, the vibration component of the weight signal is removed by the digital filter processing unit 17, and a weighing signal indicating the weighing value is output.

On the other hand, a column 5b for supporting the weighing dish 5a is fixed to the movable portion 1c of the load cell with bolts B. At the lower end of the column 5b, a seamless copper or aluminum pipe with a small resistivity and a high purity is cut. The cylindrical member 6 formed as described above is coaxially fixed via a support 7. Thus, the cylindrical member 6 has its movable portion 1
It is arranged so as to match the moving direction A of c (the vertical direction in this example). Here, the reason why the seamless pipe is used as the cylindrical member 6 is that the electric resistance in the direction along the peripheral wall is small.

The support 7 is connected to an outer opening (upper opening) of the cylindrical member 6, whereby
It is located outside a magnetic circuit 8 described later. Therefore, the material of the support 7 can be freely selected without particularly considering the electric resistance value or the like. Further, a through hole 13 is formed in the support 7 for suppressing air resistance when the cylindrical member 6 moves. Thus, the cylindrical member 6 is arranged so that the axial direction thereof coincides with the moving direction A (the vertical direction in this example) of the movable portion 1c. Here, the seamless pipe is used because the electric resistance in the direction along the peripheral wall is small.

A magnetic circuit 8 which forms a magnetic damper 9 together with the cylindrical member 6 is fixed to a base F, is made of a ferromagnetic material such as pure iron, and has a peripheral wall 81 and an end wall 82 at one end thereof. And a Nd-F attached to an end wall 82 of the yoke main body 8a.
It is composed of a columnar permanent magnet 8b made of an anisotropic sintered magnet having EB as a main component, and a disk-shaped center yoke 8c coaxially fixed to the permanent magnet 8b. That is, the magnetic circuit 8 includes the permanent magnets 8b and the magnetic path forming members 8a and 8c for forming magnetic paths by the permanent magnets 8b.

The cylindrical member 6 is inserted into a magnetic gap formed between the inner peripheral surface of the yoke main body 8a and the outer peripheral surface of the center yoke 8c. These mechanism units and the measurement circuit units 3 and 4 are covered by a cover 10.
In this state, the peripheral wall 81 of the yoke main body 8a faces the outer periphery of the cylindrical member 6, and the permanent magnet 8b and the center yoke 8
c faces the inner periphery of the cylindrical member 6, and the magnetic flux generated by the magnetic circuit 8 crosses the peripheral wall of the cylindrical member 6.

Hereinafter, the operation of the weighing device will be described. In FIG. 1, when the object M is placed on the weighing dish 5a, the strain gauge 2 is incorporated in the bridge circuit 3 and detects the amount of strain corresponding to the downward displacement of the movable portion 1c of the load cell 1. Then, a weight signal is output through the bridge circuit 3.

The weight signal output from the bridge circuit 3 includes a vibration component accompanying the vertical movement of the load cell 1 in addition to a component corresponding to the weight of the object M. The characteristic A in FIG. 2 is a vibration characteristic when the magnetic damper 9 is not provided. The lower the weight, the greater the influence of the tare weight and the lower the natural frequency, and the longer the time required for convergence. On the other hand, the characteristic B and the characteristic C in FIG. 2 show the vibration characteristic of the weighing device according to the present embodiment, and the characteristic B shifts from the characteristic B to the characteristic C as the braking force of the magnetic damper 9 increases.

The braking force (damping force) of the magnetic damper 9 shown in FIG.
Is proportional to the relative moving speed of the cylindrical member 6 and the square of the magnetic flux density linked thereto, and is inversely proportional to the resistivity of the cylindrical member 6. Therefore, in this embodiment, the cylindrical member 6 is made of pure copper or pure copper. The aluminum seamless pipe is made of a member having a small resistance value in the circumferential direction obtained by cutting the aluminum seamless pipe.
Is a kind of rare earth magnet having a particularly large coercive force, Nd
The yoke body 8a and the center yoke 8c are made of a ferromagnetic material having a high magnetic permeability such as pure iron. According to this configuration, the magnetic damper 9 can be downsized, and a sufficient braking force can be obtained, so that a low-weighing measuring device capable of measuring at a high speed can be obtained.

Since the displacement of the movable portion 1c of the load cell 1 is suppressed by the braking force of the magnetic damper 9, the vibration component included in the weight signal output from the bridge circuit 3 is reduced. The weight signal in which the vibration component is suppressed is shown in FIG.
Through the amplifier 14 and the anti-alias filter 15 of the A /
After being converted into a digital signal by the D converter 16, the vibration component is attenuated by the digital filter processing unit 17. As described above, since the vibration component of the weight signal input to the A / D converter 16 is suppressed, the input voltage range of the A / D converter 16, that is, the dynamic range can be expanded. The resolution of the / D converter 16 can be increased, thereby improving the weighing accuracy.

The magnetic damper 9 generates magnetism by the magnetic circuit 8 including the permanent magnet 8b, and does not require an electric circuit such as a conventional electromagnetic force balance using a force coil. It becomes unnecessary and the structure becomes simple, and energy consumption is small.

Turning now to the description of the second embodiment. As shown in FIG. 4 (a), the magnetic circuit 18 constituting the magnetic damper 9A together with the cylindrical member 6 is fixed to the base F, is made of a ferromagnetic material such as pure iron, and Central pillar 92
And a yoke 18a which is a cylindrical magnetic path forming member having a bottom and an end wall 93 connecting one end of the yoke 18a,
And a ring-shaped permanent magnet 18b mounted on the outer periphery of the central pillar portion 92 of FIG. The permanent magnet 18b is N
It is formed of an anisotropic sintered magnet containing d-Fe-B as a main component and is magnetized in the radial direction. For example, as shown in FIG. The part is an S pole. The cylindrical member 6 is formed by cutting a high-purity copper seamless pipe having a small resistivity and its support 7 is formed of aluminum.

As shown in FIG. 4B, the central column 92 of the yoke 18a has a large-diameter portion (convex portion) 92a on the distal end side and a small-diameter portion 92b on the proximal end side connected to the end wall 93. And the surrounding wall 91
Also, a small-diameter portion (convex portion) 91a on the distal end side and a large-diameter portion 91 on the proximal end side
b. Large diameter portion (convex portion) 92a and small diameter portion (convex portion)
The large-diameter portion 92a has a permanent magnet 18b mounted on the outer periphery of the large-diameter portion 92a. As a result, the permanent magnet 18b of the central column 92 and the small-diameter portion (projection) 91a of the peripheral wall 91 face each other and have substantially the same height. Other configurations are the same as those of the first embodiment.

The inner peripheral surface of the yoke 18a and the central cylindrical portion 9
The cylindrical member 6 is inserted into a magnetic gap formed between the outer circumferential surfaces of the cylindrical member 2 and the cylindrical member 6. In this state, the yoke 18
The small-diameter portion (convex portion) 91a of the peripheral wall 91a faces the outer periphery of the cylindrical member 6, and the permanent magnet 18b is
And the magnetic circuit 18 causes the magnetic flux B0 (solid line) directed from the permanent magnet 18b to the small-diameter portion (convex portion) 91a of the peripheral wall 91 in the radial direction to cross the peripheral wall of the cylindrical member 6. Has become.

According to this configuration, unlike the first embodiment, the magnetic flux B0 generated in the radial direction by the permanent magnet 18b crosses the peripheral wall of the cylindrical member 6 in the radial direction as it is, and
, The leakage magnetic flux B1 (dashed line) that spreads in the axial direction decreases, and the density of the magnetic flux B1 that crosses the cylindrical member 6 in the radial direction increases. as a result,
The braking force of the magnetic damper 9A is further increased, and the responsiveness of the low-weighing weighing device can be improved.

In particular, the permanent magnet 18b sandwiching the cylindrical member 6
And the small-diameter portion (convex portion) 91a of the peripheral wall 91 are opposed to each other and provided at substantially the same height (axial position).
Since 0 is formed exactly in the radial direction and is orthogonal to the cylindrical member 6, the braking force of the magnetic damper 9A is further increased. In addition, since the small-diameter portion (convex portion) 91a protrudes to the inner peripheral side and the permanent magnet 18b also protrudes to the outer peripheral side of the central cylindrical portion 92, the permanent magnet 18b is other than the small-diameter portion (convex portion) 91a in the yoke 18a. Flux B2 to the part
(Two-dot chain line) is reduced. Therefore, the leakage magnetic flux to the outside is small, the influence of the surrounding metal is reduced, and the braking force of the magnetic damper 9A is further increased.

FIG. 5 shows the results of this experiment. (A) shows the case where the magnetic damper 9A is not provided, and (b) shows the case where the magnetic damper 9A of the second embodiment is provided. As shown in FIG. 3B, the weight signal is attenuated in a short time by the braking force of the magnetic damper 9A, and shows a remarkable attenuation effect. According to an experiment, the braking force of the magnetic damper 9A is about 1.3 to 1.5 times larger than that of the magnetic damper 9 of the first embodiment when a permanent magnet having the same volume is used. Has been confirmed.

Unlike this embodiment, it is conceivable that a permanent magnet magnetized in the radial direction is provided on the peripheral wall 91 of the yoke 18a facing the central column 92.
This is disadvantageous because the permanent magnet is increased in size due to an increase in its radial dimension, and since the permanent magnet is located outside the cylindrical member 6, dust easily adheres.

FIGS. 6 and 7 show a third embodiment in which the present invention is applied to a combination weighing device. In FIG. 6, the combination weighing device is supported on a gantry BF. The articles M sent from the supply conveyor 21 are supplied to the supply chute 2
2 through a vibration type dispersion feeder 24. A plurality of vibration feeders 25 are radially arranged in plan view near the outer periphery of the dispersion feeder 24, and the vibration feeder 25 receives the articles M dispersed around by the vibration of the dispersion feeder 24. The vibration feeder 25 vibrates at a predetermined amplitude and a predetermined number of vibrations, so that the article M
Out in the radial direction.

A pool hopper 26 is disposed below the outer end of each of the vibration feeders 25, and one or a plurality (one in this example) of weighing is provided below each pool hopper 26. A hopper 28 is arranged. Article M sent to pool hopper 26 by vibration of vibration feeder 25
Is temporarily pooled in accordance with the weighing operation, and then the discharge gate 27 of the pool hopper 26 is opened and put into the weighing hopper 28. The load cell 1 is provided with each weighing hopper 28
And outputs a weight signal. A combination operation is performed based on these weight signals, a weighing hopper 28 having a combined weight within an allowable range set based on the target weight is selected, the discharge gate 29 of the weighing hopper 28 is opened, and the articles M are collected. Collected by the chute 31 and discharged from the timing gate 32. The discharged articles M are wrapped by a lower wrapping machine (not shown) to become bagged products having a weight within an allowable range.

In this weighing device, a frame F is mounted on a base 33 installed on the gantry BF. The frame F includes a plurality of legs 34 and a torso 35 supported by these legs 34.
The dispersion feeder 24, the vibration feeder 25 and the pool hopper 26 are supported on the upper surface of the upper wall 36 of the body 35, and the box 3 attached to the side is
7, the weighing hopper 28 is supported. Torso 35
The load cell 1 is supported inside.

The body 35 is, as shown in FIG.
The cylindrical inner wall 41 is connected to the disc-shaped lower wall 40 connected to the inner wall 4, and the upper wall 36 is connected to the inner wall 41. A plurality of boxes 37 provided for each weighing hopper 28 are supported over the upper wall 36 and the inner wall 41.

Each box 37 has a U-shaped side wall 43 and a bottom wall 44 in plan view. The upper wall 36 and the inner wall 41 form a storage space S for the load cell 1 inward.
The load cell 1 has a fixing portion 1a having a bolt 4
6 and is supported by the base 33 via the inner wall 41. The movable member 1c of the load cell 1 includes a support member 4
7 are connected by bolts 48.

The support member 47 protrudes below the box 37 through an insertion hole 45 formed in the bottom wall 44 of the box 37, and a horizontal support pin 50 and a contact pin 51 are provided below the protruded lower portion. Fixed. Weighing hopper 28
A pair of right and left mounting brackets 52 are fixed to each other and located in the front and back directions on the paper surface of FIG. 7. Support grooves 53 provided in each mounting bracket 52 are fitted into the support pins 50, and the lower ends of the mounting brackets 52 are fixed. The mounting bracket 52 is supported by the support member 47 by bringing the contact portion 54 into contact with the contact pin 51. The insertion hole 4
5 is closed by a rubber diaphragm 56 provided between the peripheral portion and the support member 47. Thereby, the storage space S in the box 37 is sealed.

A support member 47 fixed to the movable part 1c
A magnetic damper 9A having the same structure as that of the second embodiment
Are arranged upside down with respect to FIG. The cylindrical member 6 of the magnetic damper 9A is fixed on the upper part of the support member 47,
The axial direction is set to the vertical direction which is the movable direction A of the movable portion 1c. The yoke 18 a of the magnetic circuit 18 is fixed to a mounting flange 58 provided on the side wall 43 of the box 37. As a result, a damper is applied to the vibration of the load cell 1. Further, since the magnetic damper 9A is disposed in the closed space S, it is possible to minimize the entry of dust and dirt into the magnetic gap of the magnetic circuit 8.

[0040]

According to the present invention, a cylindrical member made of a good conductor attached to a movable portion of a load cell, and a magnetic circuit that includes a permanent magnet and generates a magnetic flux that crosses the peripheral wall of the cylindrical member. With the magnetic damper configured, the leakage magnetic flux to the outside is small, the influence of the surrounding metal is reduced, and the vertical vibration of the load cell generated when the object to be weighed is placed is reduced by the vibration damping action of the magnetic damper. Since the convergence can be made quickly, a high-speed and high-precision weighing is possible, and a small-sized and simple weighing device can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a weighing device according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining a vibration damping action of the magnetic damper according to the first embodiment.

FIG. 3 is a configuration diagram illustrating a configuration of a signal processing circuit of the present invention.

FIG. 4A is a longitudinal sectional view showing a weighing device according to a second embodiment of the present invention, and FIG. 4B is an enlarged view of a main part thereof.

FIG. 5 is a diagram for explaining a vibration damping action of a magnetic damper according to a second embodiment.

FIG. 6 is a side view showing a combination weighing device according to a third embodiment of the present invention.

FIG. 7 is a longitudinal sectional view showing a main part of the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Load cell, 1a ... Fixed part, 1b ... Beam part, 1c
.. Movable part, 1d notch part, 2 ... strain gauge, 3 ... bridge circuit, 4 ... signal processing circuit, 5a ... weighing plate, 5b ... support, 6 ... cylindrical member, 7 ... support, 8, 18 ... magnetic Circuit, 8a: yoke body (magnetic path forming member), 8b: permanent magnet, 8c: central yoke (magnetic path forming member), 81: peripheral wall,
82: end wall, 9, 9A: magnetic damper, 10: cover, 1
6 ... A / D converter, 17 ... Digital filtering means.

Claims (4)

[Claims] An object has a fixed portion fixedly supported on a base and a movable portion to which the weight of an object is added, detects a weight of the object corresponding to a displacement of the movable portion, and outputs a weight signal. A load cell, a cylindrical member that is attached to the movable portion of the load cell and is made of a good conductor whose axial direction is set to the moving direction of the movable portion, and a magnetic flux that includes a permanent magnet and traverses the peripheral wall of the cylindrical member. And a magnetic damper having a generated magnetic circuit. 2. The magnetic circuit according to claim 1, wherein the magnetic circuit of the magnetic damper includes a yoke main body having a peripheral wall facing the outer periphery of the cylindrical member and an end wall at one end thereof, and a yoke main body supported by the end wall and having a central portion. A magnetic path forming member consisting of a permanent magnet positioned at the end and a central yoke supported by an end wall via the permanent magnet and opposed to the inner periphery of the cylindrical member. A weighing device connected to the movable part of the load cell via a support located outside the circuit; 3. The yoke according to claim 1, wherein the magnetic circuit of the magnetic damper includes a peripheral wall facing the outer periphery of the cylindrical member, a central pillar facing the inner periphery, and an end wall connecting one end of the yoke. And a magnetic path forming member comprising a ring-shaped permanent magnet provided on the outer periphery of the central pillar portion and magnetized in the radial direction, wherein the cylindrical member includes a support member located outside the magnetic circuit. A weighing device connected to the movable portion of the load cell via a weighing device. 4. The method according to claim 1, wherein
Further, an A / A for converting a weight signal output from the load cell into a digital signal in accordance with the displacement of the movable portion of the load cell.
A weighing device comprising a D converter and digital filtering means for filtering a digital signal to remove a vibration component.