JP3251706B2 - Weighing device - Google Patents

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 weighing cell, and more particularly to a weighing device configured to eliminate a weighing error due to a low-frequency vibration component of a floor on which the weighing cell is installed. Things.

[0002]

2. Description of the Related Art As this type of weighing device, a device disclosed in JP-A-59-190627 is conventionally known. In this conventional weighing device, a dummy cell is installed on the same floor as the weighing cell in the vicinity of the weighing cell that weighs the object to be weighed and outputs a weighing signal corresponding to the weight thereof, and a dummy output from the dummy cell is provided. After inverting the signal,
By adding the weighing signals output from the weighing cells, a correction for removing a floor vibration component from the weighing signals is performed.

Since the floor vibration generally has a lower frequency than the vibration generated when the object is placed on the weighing device, if the floor vibration component is to be removed from the weighing signal by a filter, the cutoff frequency of the filter is lowered. Since it is necessary to set, the filtering time becomes long and the weighing speed is reduced. Therefore, as described above, the floor vibration component is separately removed by correction, so that the cutoff frequency of the filter can be set high, thereby realizing high-speed weighing.

[0004]

In the conventional weighing apparatus having the above-described structure, a dummy cell for detecting vibration of the floor is arranged near the weighing cell, and both cells on the floor are installed. When the vibration state of the floor where both cells are installed is different, such as when both cells are installed apart from each other, the correction is performed assuming that the vibration state of the However, even if the floor vibration component is removed from the weighing signal, accurate correction cannot be performed.In some cases, the error may be further increased by the correction.In any case, the occurrence of the weighing error due to the floor vibration can be avoided. There was nothing. Therefore, since the installation location of the dummy cell is limited to the vicinity of the weighing cell, the degree of freedom of the structure is reduced, and if there is not enough space around the weighing cell, it may be difficult to install the dummy cell.

In addition, the weighing signals of a plurality of weighing cells installed on the same floor are combined and operated to select a weighing cell having a combination close to a target value, and an object to be weighed is discharged from the selected weighing cell. In a weighing device including a plurality of weighing cells, such as a combination weighing device, a dummy cell must be arranged near each weighing cell, which complicates the mechanism of the entire device. However, there is also a problem of increasing the size.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and can accurately remove a vibration component contained in a weighing signal to realize high-precision weighing. The restrictions on the location are relaxed to increase the degree of freedom of the structure of the weighing device.Furthermore, when a plurality of weighing cells are provided, such as a combination weighing device, the mechanism of the entire device is simple, small, and An object is to provide a weighing device that can be configured at low cost.

[0007]

To achieve the above object, a weighing device according to claim 1 of the present invention weighs an object to be weighed and outputs a weighing signal corresponding to the weight of the weighing cell; A plurality of dummy cells installed on the same floor as the weighing cell, and a vibration mode of the floor is detected based on a vibration component of a dummy signal output from the plurality of dummy cells,
A floor vibration calculating means for calculating a vertical displacement of the floor at a position where the weighing cell is installed, and a floor vibration for generating a vibration corrected signal obtained by removing a floor vibration component from the weighing signal by the calculated displacement. Correction means.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the load of the dummy cell and the load of the weighing cell in a state where the object to be weighed is not placed, and the load of the dummy cell and the weighing cell are reduced. Cell sensitivity setting means for setting at least a cell sensitivity ratio between the weighing cell and the dummy cell among the weighing cell and the dummy cell, between the weighing cells, and between the dummy cells based on the spring constant, and at least one of the weighing signal and the dummy signal. A cell sensitivity correction means for correcting one of the signals with the cell sensitivity ratio to generate a cell sensitivity corrected signal.

In addition, the weighing device according to a third aspect of the present invention, in addition to the configuration according to the first or second aspect, further includes at least one of a weighing cell, a weighing cell, a dummy cell, and a weighing cell. Weight sensitivity calculating means for calculating a weight sensitivity ratio between the cell and the dummy cell; and weight sensitivity correction means for correcting at least one of the weighing signal and the dummy signal with the weight sensitivity ratio to generate a weight sensitivity corrected signal. It has.

[0010]

According to the configuration of the first aspect of the present invention, the weighing cell weighs the object to be weighed and outputs a weighing signal corresponding to the weight thereof, and the plurality of weighing cells installed on the same floor as the weighing cell. The vibration mode of the floor is detected based on the vibration component of the dummy signal output from the dummy cell, and the vertical displacement of the floor portion where the weighing cell is installed is calculated. The weighing signal is corrected based on the calculated vertical displacement to generate a vibration corrected signal from which the influence of the floor vibration is removed. That is, after detecting the vibration mode of the floor, the vertical displacement in the floor portion where the weighing cell is installed is subtracted from the weighing signal. Therefore, even when the vibration state of the floor portion at the position where the weighing cell and the dummy cell are installed is different, the weighing signal can be accurately corrected, and highly accurate weighing can be realized. In addition, since the restriction on the installation location of the dummy cell is relaxed, the degree of freedom of the structure of the weighing device is increased.

According to the second aspect of the present invention, at least one of the weighing signal and the dummy signal is corrected by the cell sensitivity ratio to generate a cell sensitivity corrected signal, so that the sensitivity of both cells to floor vibration can be reduced. The occurrence of a measurement error due to the difference can be prevented, and the measurement accuracy can be further improved.

Further, according to the third aspect of the present invention, at least one of the weighing signal and the dummy signal is corrected based on the calculated weight sensitivity ratio to generate a weight sensitivity corrected signal. The occurrence of a measurement error due to a change in the sensitivity of both cells can be prevented, and the measurement accuracy can be further improved.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a signal processing system of a combination weighing device according to one embodiment of the present invention.
In the figure, ₁ 1 to 1 _m is meter consists of a mounting portion (weighing hopper) 2 ₁ to 2 _m and the weight detection unit (weighing cell) 3 ₁ to 3 _m of the objects to be weighed, mounting portion the weight of the objects to be weighed X placed on the 2 ₁ to 2 _m were weighed at a weight detection unit 3 ₁ to 3 _m, and outputs an analog weight signal W1~Wm in accordance with the weight. 4 ₁ to 4 _n is the dummy cell, via a frame FR are more disposed to each scale cells 3 ₁ to 3 _m and the same floor F, due to floor vibration analog dummy signals D1
To Dn. Dummy cell 4 ₁ to 4 _n may be mounted on the frame FR of the metering device may be mounted on the frame FR which is provided separately from the metering device.

Reference numeral 5 denotes a multiplexer.
The weighing signals W1 to Wm output from ₁ to 1 _m are amplified and input by the amplifiers 6 _{1 to} 6 _m , and the dummy signals D1 to Dn output from the dummy cells 4 ₁ to 4 _{n are} output. is input is amplified by the amplifier 7 ₁ to _7-n. Reference numeral 8 denotes an A / D converter, which converts the analog weighing signals W1 to Wm and the dummy signals D1 to Dn selectively output from the multiplexer 5 in response to a switching signal c from a CPU, which will be described later, into digital signals.

Reference numeral 9 denotes a CPU constituting the arithmetic unit.
Based on the digital weighing signals W1 to Wm and the dummy signals D1 to Dn input through the / D converter 8, predetermined vibration correction and combination calculation are executed, and the weighing hoppers 2 ₁ to 2 which are the combination closest to the target value are executed. An open signal OS for selectively opening 2 _m is output. In this way, by correcting the low-frequency floor vibration, it is possible to set the cutoff frequency of the filters 10 ₁ to 10 _m described later to be high, thereby realizing high-speed weighing.

FIG. 2 is a block diagram showing the internal structure of the CPU 9. In FIG. 2, reference numerals 10 ₁ to 10 _m and 11 _{1 to} 11 _n are digital filters, respectively. The weighing signals W1 to Wm and the dummy signals D1 to Dn output to the A / D converter 8 and converted into digital signals by the A / D converter 8 are
Through the switching circuit 12 of FIG. 2, by passing through a corresponding filter _{10 1 ~10 m, 11 1 ~11} n , respectively, primarily occurs when carrying the objects to be weighed to the weighing hopper 2 ₁ to 2 _m Removes relatively high frequency vibration components.

Reference numeral 13 denotes a floor vibration calculating means,
Digital dummy signal D1~D passing through the 1 ₁ to 11 _n
The vibration mode of the floor is detected based on the vibration component of n, and the vertical displacement of the position on the floor where the measuring cells ₁₁ to 1 _m are installed is calculated. 14 _{1 to} 14 _m are floor vibration correction means, and filters 10 ₁ to 10 _{m based on} the vertical displacement signals S ₁ to Sm calculated by the floor vibration calculation means 13.
The digital weighing signals W1 to Wm that have passed through are corrected individually, that is, each of the digital weighing signals W
Vertical displacement signals S1 to S based on weight values of 1 to Wm
By subtracting m, in each of the scale cells 1 ₁ to 1 _m, and generates and outputs vibration corrected weight signals BS1~BSm removing the effects of floor vibrations. Thus, by correcting the low frequency floor vibration, the filter 10
High cut-off frequency of ₁ to 10 _m can be set to realize high-speed weighing. The vibration-corrected weighing signals BS1 to BSm are input to the combination calculating means 20, and a plurality of signals BS1 to BS2 which are the combination closest to the target value are obtained.
BSm is selected, the select signal OS to open a metering hopper 2 ₁ to 2 _m, which outputs the signal BS1~BSm is output.

[0018] As described above, the vibration mode based on the vibration component of the dummy signal D1~Dn output from a plurality of dummy cells 4 ₁ to 4 _n installed in the respective weighing cells 1 ₁ to 1 _m and the same floor F to detect, each weighing cell in the floor F 1 ₁ ~
The vertical displacement of the installation position of 1 _m is calculated, and the calculated displacement is subtracted from each of the weighing signals W1 to Wm, so that the corrected weighing signal BS1 in which the influence of the floor vibration is removed is obtained.
~ BSm is output. Here, in this embodiment, since the correction operation is performed digitally, the correction can be performed with higher accuracy than when an analog circuit having variations in the characteristics of individual components and elements is used.

As described above, the mode of the floor vibration is detected,
The method of canceling the vibration component of the weighing cell at an arbitrary position is called the floor vibration cancellation method (hereinafter, multipoint AFV (Anti-F
loor Vibration). When the weighing cells are arranged two-dimensionally on the floor, ie, two-dimensionally, the floor vibrations at three or more points that are not linear on the floor are detected by the dummy cells, and the vibrations of the floor are detected based on the detected vibrations. From the vibration mode, a floor vibration component at a position where an arbitrary weighing cell is installed is obtained, and the floor vibration component is subtracted from the output of the weighing cell installed at that position. On the other hand, when the weighing cells are linearly arranged on the floor, that is, one-dimensionally, the floor vibrations at two or more points on the straight line are detected by the dummy cells, and from the detected vibrations, the above-described planar arrangement is obtained. As in the case, the floor vibration component at the position where an arbitrary weighing cell is installed is obtained, and the floor vibration component is subtracted from the output of the weighing cell installed at that position.

FIG. 3 shows weighing cells 3 _{1 to} 3 _m and dummy cells 4 ₁ to 4 _n (hereinafter referred to as “load cells”) used in the above-described combination weighing device. This type of load cell 3 (4) is provided with strain gauges 32 attached to four notches 31, respectively.
The deformation state (4) is detected as a distortion amount. Further, these four strain gauges 32 constitute a Wheatstone bridge, and the output changes only when the load cell 3 (4) is deformed into a roberval (parallelogram) state as shown by a broken line, and other deformations are performed. In the state, the output does not change. Therefore, load cell 3
(4) Fixed (floor) side 3a (4a) and load (weight) side 3
Since only the component of the Robarbal deformation is detected out of the relative displacement of b (4b), when the combination weighing device is used, only the vertical component is considered for the floor vibration state of each mode. It turns out to be good.

Now, as shown in FIG. 4, it is assumed that the load cell 3 (4) is fixed at the position of the point (x, y) on the XY plane. The behavior in the XY plane consists of rotation about the X axis, rotation about the Y axis, and movement in the axis (Z axis) perpendicular to the XY plane. Other movements are not detected by the load cell 27 used here and are not discussed here.

Here, the motion of the vertical (Z-axis) component generated by the rotational motion about the X-axis is B (t), and the motion of the vertical (Z-axis) component generated by the rotary motion about the Y-axis is A (t). ), Z
Assuming that the axial movement is C (t), the floor vibration component Vp (t) of the load cell output signal at the position of the point P is as follows: Vp (t) = xA (t) + yB (T) + C (t) (1)

By the way, the floor vibration mode can be obtained by calculating A (t), B (t), and C (t) in the equation (1). May be used to detect the floor motion, that is, to solve a three-dimensional linear simultaneous equation. Actually, since the output of each measuring instrument includes an error, detection is performed at three or more points, and A (t), B (t), and C (t) are obtained using the least square method or the like. Is good.
The calculation of the vibration component Vp (t) based on the equation (1) is performed by the floor vibration calculation means 13 in FIG.

In the above embodiment, it is preferable to add the following functions. To extract only the vibration component from the output signal of the vibration detection dummy cell, a filter having a very low cutoff frequency and a long stabilization time is used in parallel with a normal filter. Although this filter is very effective, it is not stable for one metering cycle. Therefore, when the measuring device continuously participates in the combination calculation, the data obtained by correcting the floor vibration is used as an output signal. However, when the measuring device does not continuously participate and the stable time of the above strong filter can be secured. Automatically switch to use this filter result as an output signal.

FIG. 5 is a block diagram showing a configuration of a CPU 9 in a weighing device according to another embodiment of the present invention.
In this figure, the following two points are different from the internal configuration of the CPU 9 of the above embodiment shown in FIG. First the first point, the dummy cell 4 (4 ₁ to 4 _n: 1) Weighing cell 3 in a state in which the load and the objects to be weighed is not placed in the (3 ₁ -
3 _m : load of Fig. 1), weighing cell 3 and dummy cell 4
Cell sensitivity setting means 15 for presetting the cell sensitivity ratio between the weighing cell 3 and the dummy cell 4 based on one of the weighing cells 3 based on the spring constant of The dummy signal D (D1 to Dn) is corrected by the cell sensitivity ratio, and the cell sensitivity corrected signal CS1 is corrected.
To CSn is provided.

The second point is to correct the change in sensitivity to floor vibration due to the difference in load weight, and the weight between the weighing cell 3 and the dummy cell 4 that changes according to the weight of the object to be weighed. Weight sensitivity calculation means 1 for calculating sensitivity ratio
7 and the weight sensitivity ratio calculated by the weight sensitivity calculating means 17, based on one of the weighing cells 3,
The displacement signals S1 to S1 output from the floor vibration detecting means 13
The point that weight sensitivity correction means 18 for correcting Sm to generate weight sensitivity corrected signals WS1 to WSm is provided.

The cell sensitivity is corrected by the cell sensitivity correcting means 16 and the dummy signals D1 to Dn are converted into the weighing signals W1 to Wm.
Of the floor vibration calculating means 1 based on the converted signals (cell sensitivity corrected signals) CS1 to CSn.
In step 3, the floor vibration is calculated. Further, the weight sensitivity correcting means 18
The performs sensitivity correction by the weight of the objects to be weighed which have been loaded into the weighing cell 3 ₁ to 3 _m, the weight sensitivity corrected signals WS
Using 1～WSm, from the floor vibration correcting means 14 ₁ to 14 _m weight signals W1~Wm by subtracting the weight sensitivity corrected signals WS1~WSm a floor vibration components, vibration corrected signal B
S1 to BSm are obtained. Other configurations are the same as those in FIG. 2, and therefore, the same reference numerals are given to the corresponding parts, and detailed description thereof will be omitted.

The equation for sensitivity correction in the case of the embodiment shown in FIG. 5 will be briefly described. The case of FIG. 5 can be represented by the vibration model of FIG. The equations of motion of these weighing cells (weighing side) and dummy cells (floor vibration detection side) are as shown in Expressions (11) and (12). Both formulas (1
In (1) and (12), M0 is the load (mass) of the free end of the dummy cell, M1 is the load (mass) of the free end of the weighing cell when no weighing object is placed, and m is the weighing object. , K0 and k1 are the spring constants of the dummy cell and the weighing cell,
x0, x1 is the displacement of the free end of both cells, x _B is the displacement of the floor F.

[0029]

(Equation 1)

Since the relative displacement between the floor side and the load side is the output of each cell, the above equations (11) and (12) are used.
Can be modified as in Expressions (13) and (14).

[0031]

(Equation 2)

Using the above equations (13) and (14) as the input of the system with the displacement of the floor as the input of the system and the output of the cell as the output of the system, a transfer function as an input / output relationship is obtained. When G1 (jω) and Go (jω) are obtained, Expression (15) is obtained.
And equation (16). Equation (15) and Equation (16)
In the formula, ω ₁ is the natural frequency of the measuring cell, and ω ₀ is the natural frequency of the dummy cell.

[0033]

(Equation 3)

Therefore, the ratio β of the sensitivity between the weighing cell side and the dummy cell side is given by the following equation (17).

[0035]

(Equation 4)

Here, 1≫ (ω / ω _o ) ² and 1≫ (ω / ω
₁ ) ² , that is, when the natural frequency is sufficiently high on both the measurement cell side and the dummy cell side with respect to the frequency to be corrected, Expression (18) is obtained.

[0037]

(Equation 5)

In this equation (18), the part
= 0, that is, the sensitivity ratio of both cells in a state where the object to be weighed is not placed, and the part indicates how much the sensitivity of the weighing cell changes due to the placement of the object to be weighed. That is, it indicates the weight sensitivity ratio of both cells.

The spring constant k of the weighing cell and the dummy cell
Based on 0, k1, the load M0 of the dummy cell, and the load M1 of the weighing cell in a state where the object to be weighed is not placed, the cell sensitivity ratio is determined in advance by a simple expression expressed by the above equation (18). In advance, the cell sensitivity is set by the cell sensitivity setting means 15 in FIG. 5, and the cell sensitivity is corrected by the cell sensitivity correction means 16. On the other hand, by the weight sensitivity calculating means 17,
The weight sensitivity ratio is obtained by a simple equation expressed by the above equation (18), and the weight sensitivity is corrected by the weight sensitivity correction unit 18. At the time of the weight sensitivity correction, the weight sensitivity between the plurality of weighing cells and the dummy cells is corrected based on one weighing cell, so that the weight sensitivity between the weighing cells is also corrected. In this way, the weighing signal can be corrected with extremely high accuracy.

[0040] Unlike the above embodiments, the cell sensitivity correcting means 16 and the weight sensitivity correcting means 18, connected to the output side of the digital filter 10 ₁ to 10 _m of the weighing signal side, one of the dummy cell 4 , The sensitivity of the weighing signals W1 to Wm is corrected, and the dummy signals D1 to Dn are corrected.
The floor vibration correction may be performed after the conversion into the level. However, in that case, the weighing signals W1 to
It is necessary to perform correction again to convert Wm to a level before correction.

Further, by connecting the cell sensitivity correction means 16 to both the weighing signal side and the dummy signal side, it is possible to correct the cell sensitivity not only between the weighing signal and the dummy signal but also between the weighing signal and the dummy signal. Good. In short, the cell sensitivity correction means and the weight sensitivity correction means only need to perform sensitivity correction on at least one of the weighing signal and the dummy signal.

In each of the above embodiments, the digital filters 10 ₁ to 10 _m and 11 _{1 to} 11 _n are used.
As compared with the case of using an analog filter in which the characteristics of individual parts and elements vary as well, errors in the cutoff characteristics are smaller, so that each of the filters 10 ₁ to 10 _m , 1
1 ₁ to 11 _n increases it becomes possible to set the cutoff frequency of, as a result, more responsiveness is improved, metering is faster.

Further, in the embodiment shown in FIG. 5, it is preferable to add the following functions. In order to reduce the error after floor vibration correction, weight sensitivity correction is performed when the object is loaded, but the mass m of the object used in the correction formula is the final result to be obtained. Is an undetermined value. Therefore, first, floor vibration correction was performed without weight sensitivity correction, and the result (mass m of the object to be weighed) was obtained.
Using that value, floor vibration correction with weight sensitivity correction is performed again. This is repeated several times to obtain high weighing accuracy.

When the floor vibration is small, the weighing accuracy may be reduced by correcting the floor vibration due to a calculation error or the like. Therefore, if the vibration component of the output of the dummy cell for vibration detection is equal to or less than a predetermined reference, the floor vibration correction is automatically stopped to prevent deterioration in accuracy.

However, the digital filter 10 ₁
An analog filter may be used instead of or together with 10 _m and 11 ₁ １１11 _n . In this case, the analog filter 19 is connected to a position indicated by a virtual line in FIG.

[0046]

As described above, according to the first aspect of the present invention, by detecting the vibration mode of the floor, the vertical vibration component in the floor portion where the weighing cell is installed, that is, the vertical displacement, is detected. Since the calculation and correction are performed, even if the vibration state of the floor portion at the position where the weighing cell and the dummy cell are installed is different, the weighing signal is accurately corrected, and accurate weighing is performed. Can be realized. Therefore, since the installation location of the dummy cell is not limited to the vicinity of the weighing cell, the degree of freedom of the structure of the weighing device is increased.

Further, even when a large number of weighing cells are provided, such as a combination weighing device, at least three (in the case of a planar arrangement) or two (in the case of a linear arrangement) dummy cells are sufficient. There is no need to arrange cells in a one-to-one relationship. Therefore, the mechanism of the entire apparatus can be simplified and reduced in size, and can be advantageously configured in terms of cost.

According to the second aspect of the invention, the occurrence of a measurement error due to the difference in sensitivity between the weighing cell and the dummy cell with respect to the floor vibration is prevented, and the weighing accuracy is further improved.

Further, according to the third aspect of the invention, the occurrence of a measurement error due to a change in the sensitivity of the two cells due to the load of the object to be weighed is prevented, and the weighing accuracy is further improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a signal processing system of a weighing device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration of a CPU of FIG.

FIG. 3 is a diagram showing a load cell model for explaining the theory of the AFV technology.

FIG. 4 is a diagram showing an arrangement of the load cell.

FIG. 5 is a block diagram showing an internal configuration of a CPU in a weighing device according to another embodiment of the present invention.

FIG. 6 is a diagram showing a vibration model in the case of FIG. 5;

[Explanation of symbols]

1, 1 ₁ to 1 _m : weighing cell, 4, 4 ₁ to 4 _n : dummy cell, 9: CPU, 13: floor vibration calculation means, 14: floor vibration correction means, 15: cell sensitivity setting means, 16: cell sensitivity Correction means, 17: weight sensitivity calculation means, 18: weight sensitivity correction means, W1 to Wm: weighing signal, D1 to Dn: dummy signal, BS1 to BSm: vibration corrected signal, CS1 to CSn
... cell sensitivity corrected signal, WS1 to WSm ... weight sensitivity corrected signal, F ... floor.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hidekatsu Tokumaru 5-7, Minamiueda-cho, Shugakuin, Sakyo-ku, Kyoto-shi, Kyoto (56) References JP-A-59-190627 (JP, A) 69207 (JP, B2) (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01G 23/01

Claims (3)

(57) [Claims] 1. A weighing cell for weighing an object to be weighed and outputting a weighing signal corresponding to the weight thereof, a plurality of dummy cells installed on the same floor as the weighing cell, and a plurality of dummy cells output from the plurality of dummy cells. A floor vibration calculating means for detecting a vibration mode of the floor based on a vibration component of the dummy signal to calculate a vertical displacement of the floor at a position where the measuring cell is installed; and A floor vibration correcting unit configured to generate a vibration corrected signal obtained by removing a floor vibration component from the signal. 2. The method according to claim 1, wherein the load between the dummy cell and the dummy cell is measured based on the load of the dummy cell, the load of the weight cell in a state where the object to be weighed is not placed, and the spring constant of the dummy cell and the weight cell. A cell sensitivity setting means for setting a cell sensitivity ratio between at least the weighing cell and the dummy cell among the cells and between the dummy cells; and correcting the cell sensitivity by correcting at least one of the weighing signal and the dummy signal with the cell sensitivity ratio. A cell sensitivity correction means for generating a completed signal. 3. The weight sensitivity calculation according to claim 1, wherein at least a weight sensitivity ratio between the weighing cell and the dummy cell among the weighing cell and the dummy cell and between the weighing cells is calculated according to the weight of the object to be weighed. A weighing apparatus comprising: means; and weight sensitivity correction means for correcting at least one of the weighing signal and the dummy signal with the weight sensitivity ratio to generate a weight sensitivity corrected signal.