JP2011027424A - Weighing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately eliminate the vibrating component resulting from a rotor, in a weighing device having a configuration where a supplied part to which a measured object is supplied is supported together with the rotor by a load detection means. <P>SOLUTION: In a weighing conveyor 12 for a weight selector 10, a conveyor body 22 as the supplied part is supported together with the rotor such as a motor 40 by a load cell 30 as the load detection means. Consequently, the vibrational component resulting from rotating the rotor appears in a load detection signal Wy(t) output from the load cell 30. The mode for the vibrating component varies with the rotational speed of the rotor and the weight Wo of a measured object 18. Consequently, two or more types of correcting signals, in response to various operating conditions including the rotational speed of the rotor and the weight Wo of the measured object 18 are prepared previously. Then the vibrational component is eliminated by the correcting signals, in response to an actual operating condition. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a weighing device, and in particular, a supply portion to which an object to be weighed is supplied is supported by a load detection unit together with a rotating body, and the object to be weighed is based on a load detection signal obtained from the load detection unit. determination of the weight, to the weighing device.

  An example of this type of weighing device is a weighing conveyor for a weight sorter. That is, in a weighing conveyor for a weight sorter, a conveyor main body as a supplied portion is supported by a load detection means such as a load cell. The conveyor body has rotating bodies such as a motor and a pulley, and the objects to be weighed supplied to the conveyor body are conveyed by the rotation of these rotating bodies. And based on the load detection signal obtained from a load detection means, when the to-be-measured object is conveyed by this conveyor main body, the weight of the to-be-measured object is calculated | required.

  By the way, when the conveyor body is operating, that is, when the rotating body is rotating, the vibration force caused by the rotation of the rotating body, particularly the vibration force caused by the eccentric load of the rotating body is detected by the load detection. acting on the means. As a result, a vibration component having the same period as the rotation period of the rotating body appears in the load detection signal. Needless to say, this vibration component causes a decrease in measurement accuracy. Therefore, it is necessary to remove the vibration component in order to prevent this reduction in measurement accuracy. However, the period of the vibration component is the same as the rotation period of the rotating body as described above. When this is converted into a frequency, it is approximately several [Hz] to several tens [Hz]. If such a low-frequency vibration component is to be removed by a normal filter circuit such as a low-pass filter circuit, an excessive response delay occurs, which is inconvenient. Therefore, conventionally, for example, the technique disclosed in Patent Document 1 has been proposed.

  According to this prior art, an encoder for encoding a rotation angle is attached to a motor as a rotating body. In addition, first, in the prior adjustment operation, the weighing conveyor is driven in a state where the workpiece as the object to be weighed is not placed on the weighing conveyor. At this time, a weighing signal as a load detection signal obtained from the weighing conveyor (balance) is stored in correspondence with the encoder signal from the encoder. This stored measurement signal corresponds to a vibration component caused by the rotation of the rotating body. In the actual operation, the workpiece is conveyed by the weighing conveyor, and the weighing signal stored in advance is subtracted from the weighing signal obtained at this time corresponding to the encoder signal. As a result, a vibration component caused by the rotation of the rotating body is removed, and so-called error correction is performed.

JP 2000-337949 JP

  However, the above-described conventional technique has a problem that the error correction accuracy is lacking for the following reason.

That is, the vibration force caused by the eccentric load of the rotating body is equivalently that the mass point having a mass m0 corresponding to the eccentric load is at a distance r from the center of the rotating body, and the angular velocity is ω. The centrifugal force F0 (= m0 · r · ω ² ) due to the rotation at acts on the load detection means in a sine function (or cosine function) with a period of T (= 2 · π / ω). It is thought to occur. The angular velocity ω here is proportional to the rotational speed of the rotating body. Therefore, when the rotational speed of the rotating body changes, the magnitude of the vibration force (centrifugal force Fe) acting on the load detection means changes, and consequently the amplitude of the vibration component of the load detection signal that is the output of the load detection means changes.

  Further, the measuring unit composed of the load detecting means and the respective parts such as the supplied part including the rotating body supported by the load detecting means is a so-called secondary vibration system. Transfer function G (s) (s; Laplace variable).

<< Formula 1 >>
G (s) = ωn ² / (s ² + 2 · ζ · ωn · s + ωn ² )

In Equation 1, ωn is the natural frequency of the measuring unit, and is expressed as ωn = (k / m) ^1/2 by the mass m of the measuring unit and the spring constant k. Ζ is the damping ratio of the measuring unit.

  The weighing unit having such a transfer function G (s) responds with a phase delay angle φ corresponding to the transfer function G (s) when a vibration force is applied thereto. FIG. 34 shows the relationship among the phase delay angle φ, the angular velocity ω of the rotating body, and the natural frequency ωn of the measuring unit, including the damping ratio ζ of the measuring unit. As can be seen from FIG. 34, for example, assuming that the natural frequency ωn of the measuring unit is constant, the phase delay angle φ changes depending on the angular velocity ω of the rotating body, that is, changes depending on the rotational speed of the rotating body. The change in the phase delay angle φ also appears in the vibration component of the load detection signal.

  On the other hand, even if the rotational speed (angular speed ω) of the rotating body is constant, the phase delay angle φ changes when the natural frequency ωn of the measuring unit changes. Here, the natural frequency ωn of the measuring unit includes the mass m of the measuring unit as an element as described above. The mass m of the weighing unit includes the mass of the object to be weighed. Therefore, when the mass of the object to be weighed changes, the mass m of the weighing unit changes, and consequently the natural frequency ωn changes. Moreover, naturally, the mass m of the measuring unit changes and the natural frequency ωn changes depending on the presence or absence of the object to be weighed. That is, the phase delay angle φ changes depending on the mass of the object to be measured including the presence or absence of the object to be weighed. The change in the phase delay angle φ also appears in the vibration component of the load detection signal, as described above. The change in the phase delay angle φ due to the change in the mass of the object to be measured becomes more significant as the mass of the object to be measured increases.

  Further, the displacement Xst of the measurement unit when a static external force of a certain magnitude acts on the measurement unit, and the displacement of the measurement unit when a vibration force having the same magnitude as the static external force acts on the measurement unit A ratio M (= X / Xst) of X is called an amplitude magnification. The relationship between the amplitude magnification M, the angular velocity ω of the rotating body, and the natural frequency ωn of the measuring unit is expressed by the measuring unit. If the damping ratio ζ is also illustrated, it is as shown in FIG. As can be seen from FIG. 35, for example, assuming that the natural frequency ωn of the measuring unit is constant, the amplitude magnification M changes depending on the rotational speed (angular speed ω) of the rotating body. This means that the amplitude of the vibration component of the load detection signal changes.

  Even if the rotational speed of the rotating body is constant, the amplitude magnification M changes when the natural frequency ωn of the measuring unit changes. Here, as described above, considering that the natural frequency ωn of the weighing unit varies depending on the mass of the object to be weighed, the amplitude magnification M varies depending on the mass of the object to be weighed, and thus the vibration component of the load detection signal. Will change in amplitude. This also becomes more remarkable as the mass of the object to be weighed is larger.

  Thus, the amplitude and phase delay angle of the vibration component of the load detection signal change depending on the rotational speed of the rotating body and the mass (weight) of the object to be weighed. In such a nature, in the above-described prior art, the presence / absence of a workpiece as an object to be weighed, in other words, the weight of the workpiece is different between the prior adjustment operation and the actual operation operation. Moreover, the rotational speed of the rotating body may be different. In other words, mutual operating conditions are different. Therefore, the amplitude and the phase delay angle differ between the vibration component during the adjustment operation and the vibration component during the operation operation. In spite of this, the vibration component during the operation operation is stored as a correction signal, and the correction signal cancels the vibration component during the operation operation. There is a problem that the components cannot be accurately removed and the error correction accuracy is lacking as described above.

  Therefore, an object of the present invention is to provide a weighing device capable of correcting an error due to a vibration component caused by rotation of a rotating body more accurately than in the past.

  In order to achieve this object, according to the present invention, a supply portion to which an object to be measured is supplied is supported by a load detection means together with a rotating body, and based on a load detection signal obtained from the load detection means. In the weighing device for obtaining the weight of the object to be weighed, the load detection signal includes a vibration component caused by the rotation of the rotating body, and the mode of the vibration component includes the rotation speed of the rotating body and the applied load to the load detecting means. It is assumed that it changes depending on the operating conditions including. Under this premise, storage means for storing a plurality of types of correction signals for removing vibration components in various modes under various operating conditions, and storage means for correcting signals according to actual operating conditions And a vibration component removing means for removing the vibration component contained in the load detection signal by subtracting the correction signal read by the read means from the load detection signal.

  That is, according to this invention, the to-be-supplied part to which the to-be-measured object is supplied is supported by the load detection means with the rotary body. Based on the load detection signal obtained from the load detection means, the weight of the object to be weighed is obtained. However, a vibration component resulting from the rotation of the rotating body is superimposed on the load detection signal. The mode of the vibration component, in particular the amplitude and the phase delay angle, varies depending on operating conditions including the rotational speed of the rotating body and the load applied to the load detecting means, in other words, the weight of the object to be weighed. Needless to say, this vibration component causes a decrease in measurement accuracy. In order to prevent this, in the present invention, a plurality of types of correction signals for removing vibration components of various modes under various operating conditions are stored in advance in the storage means, for example, in advance adjustment operation. . Then, in the actual operation operation, a correction signal corresponding to the actual operation condition is read from the storage unit by the reading unit. Further, the read correction signal is subtracted from the load detection signal by the vibration component removing means. Thereby, the vibration component contained in the load detection signal is removed. That is, the vibration component is canceled and corrected by the correction signal in the same manner as the vibration component under actual driving conditions.

  In the present invention, there may be further provided a weighing object detecting means for detecting whether or not the weighing object is supplied to the supply portion, that is, the presence or absence of the weighing object. In this case, the reading means reads out a correction signal corresponding to the actual operating condition from the storage means based on the actual operating condition including the detection result by the measurement object detecting means.

  Further, setting means for manually setting at least a part of actual operating conditions may be further provided. For example, when the standard value of the rotational speed of the rotating body and the standard value of the weight of the object to be weighed are known, these may be set by the setting means. In this case, the reading unit reads out a correction signal corresponding to the actual operating condition from the storage unit based on the actual operating condition including the setting content by the setting unit.

  Further, when there are a plurality of rotating bodies, a plurality of vibration components corresponding to the plurality of rotating bodies are superimposed on the load detection signal. In this case, a plurality of types of correction signals are stored in the storage unit for each rotating body. The reading means reads the correction signal corresponding to the actual operating condition for each rotating body, and the vibration component removing means reads all the correction signals read for each rotating body by the reading means as the load detection signal. It shall be subtracted from. As a result, error correction is performed for each rotating body, that is, the vibration component caused by each rotating body is accurately removed.

  As described above, when the operating condition including the rotational speed of the rotating body and the weight of the object to be measured changes, the mode of the vibration component of the load detection signal changes. According to the present invention, the vibration component under the actual driving condition is changed. The vibration component is canceled and corrected by the correction signal in the same manner as. Therefore, accurate error correction is realized as compared with the above-described prior art in which the modes of the vibration component and the correction signal are different.

It is a figure which shows the external schematic structure of the weight sorter | selector which concerns on one Embodiment of this invention. It is a block diagram which shows the electrical structure of the indicator in the same embodiment. It is an illustration figure which shows the aspect of each vibration component contained in the analog load detection signal in the embodiment. FIG. 4 is an illustrative view showing a manner of each vibration component in FIG. It is an illustration figure which shows the list of the driving conditions in the same embodiment. It is a figure which expands and shows the rotary encoder in the same embodiment. It is a block diagram which shows the notional structure of the zero adjustment circuit in the embodiment. It is an illustration figure which shows the timing of each signal containing the vibration component resulting from the motor in the embodiment. It is an illustration figure which shows notionally the signal for motor correction in the embodiment. It is a block diagram which shows the notional structure of the signal generation circuit for motor correction in the embodiment. It is an illustration figure which shows notionally the signal for motor correction | amendment produced | generated on the driving conditions different from FIG. FIG. 12 is an illustrative view conceptually showing an anti-motor correction signal generated under an operation condition further different from FIG. 11. FIG. 13 is an illustrative view conceptually showing an anti-motor correction signal generated under an operation condition further different from FIG. 12. It is an illustration figure which shows the timing of each signal containing the vibration component resulting from the drive side pulley in the embodiment. It is an illustration figure which shows notionally the signal for a drive side pulley correction | amendment in the embodiment conceptually. It is a block diagram which shows the notional structure of the signal generation circuit for anti-drive side pulley correction | amendment in the embodiment. FIG. 16 is an illustrative view conceptually showing an anti-drive side pulley correction signal generated under an operation condition different from that in FIG. 15. FIG. 18 is an illustrative view conceptually showing an anti-drive-side pulley correction signal generated under an operation condition further different from FIG. 17. FIG. 19 is an illustrative view conceptually showing an anti-drive-side pulley correction signal generated under an operation condition further different from that in FIG. 18. It is an illustration figure which shows the timing of each signal containing the vibration component resulting from the driven pulley in the embodiment. FIG. 4 is an illustrative view conceptually showing a driven pulley correction signal in the same embodiment. FIG. 3 is a block diagram showing a conceptual configuration of a driven pulley correction signal generation circuit in the same embodiment. FIG. 22 is an illustrative view conceptually showing a driven pulley correction signal generated under operating conditions different from those in FIG. 21. FIG. 24 is an illustrative view conceptually showing a driven pulley correction signal generated under an operation condition further different from that in FIG. 23. FIG. 25 is an illustrative view conceptually showing a driven pulley correction signal generated under an operation condition further different from FIG. 24. 3 is an illustrative view conceptually showing a correction signal list in the same embodiment. FIG. It is a block diagram which shows the notional structure of the vibration component removal circuit in the embodiment. It is a block diagram which shows the notional structure of the temporary weight measurement circuit in the embodiment. It is a flowchart which shows the flow of the vibration component correction | amendment task performed by CPU in the same embodiment. It is a flowchart which shows the detail of a certain step of FIG. It is a flowchart which shows the detail of a step different from FIG. 32 is a flowchart showing details of steps different from those in FIG. 33 is a flowchart showing details of steps different from those in FIG. 32. It is an illustration figure which shows the characteristic of the measurement part as a secondary vibration system. It is an illustration figure which shows the characteristic different from FIG.

  An embodiment of the present invention will be described by taking a weight sorter 10 as an example.

  As shown in FIG. 1, the weight sorter 10 according to the present embodiment includes a weighing conveyor 12, a carry-in conveyor 14 provided in the front stage (left side in FIG. 1) of the weighing conveyor 12, and the weighing conveyor 12. And a carry-out conveyor 16 provided at the rear stage (right side in FIG. 1). Then, the objects to be weighed 18 to be sorted by the weight sorter 10 are conveyed from the carry-in conveyor 14 to the weighing conveyor 12 as indicated by an arrow 20 in FIG. 1, and further from the weighing conveyor 12 to the carry-out conveyor 16. It is conveyed to. In this series of transport processes, when the object to be weighed 18 is on the weighing conveyor 12, the weight Wo of the object to be weighed 18 is obtained, and strictly speaking, a weight measurement value Wo [i] described later is obtained. Based on the weight measurement value Wo [i], a selection signal So, which will be described later, is generated for selecting whether the weight Wo of the object to be weighed is good or not, or over / appropriate / light weight. This sorting signal So is sent to a sorting device (not shown) attached to the carry-out conveyor 16, and the sorting device sorts the objects 18 to be measured corresponding to the sorting signal So.

  Incidentally, the weighing conveyor 12 includes a so-called belt-type conveyor body 22. That is, the conveyor body 22 includes an endless belt-like conveyor belt 24 and a pair of pulleys 26 and 28 having the same diameter (same outer diameter) for running the conveyor belt 22. The conveyor body 22 is supported by a robust load cell 30 as load detection means. Specifically, the conveyor body 22 is coupled to the movable end (the right end in FIG. 1) of the load cell 30 via a suitable movable side support member 32. The fixed end (the left end portion in FIG. 1) of the load cell 30 is fixed to an appropriate base portion 36 such as a frame of the housing via an appropriate fixed side support member 34.

  Further, one pulley 26 of the conveyor body 22 is coupled to a motor 40 as a drive source for driving the conveyor body 22 via a timing belt 38 as a driving force transmission means. The motor 40 is also supported by the load cell 30. Specifically, the motor 40 is fixed to an appropriate location on the movable side support member 32. A timing pulley 44 is attached to the rotating shaft 42 of the motor 40, and a timing pulley 46 having the same diameter (the same number of teeth) as that is also attached to the rotating shaft 48 of the one pulley 26. . A timing belt 38 is engaged between the timing pulleys 44 and 46.

  According to this configuration, when the motor 40 operates, the driving force is transmitted to the one pulley 26 via the timing belt 38. Further, the driving force transmitted to the one-side driving pulley 26 is transmitted to the other-side driven pulley 28 via the conveyor belt 24. As a result, the pulleys 26 and 28 rotate, and the conveyor belt 24 travels. Then, the object to be weighed 18 is transported by placing the object to be weighed 18 on the running conveyor belt 24.

  Thus, when the object 18 is being conveyed by the weighing conveyor 12 including the conveyor belt 24, the analog load detection signal Wy (t) (t; time) output from the load cell 30 constituting the weighing conveyor 12 is used. Based on this, the above-described weight measurement value Wo [i] is obtained, and the selection signal So is created. Therefore, the analog load detection signal Wy (t) is sent to the indicator 100 that controls the weight sorter 10 as a whole.

  As shown in FIG. 2, the indicator 100 has an amplifier circuit 102, and an analog load detection signal Wy (t) is input to the amplifier circuit 102. The amplification circuit 102 performs amplification processing on the input analog load detection signal Wy (t), and the analog load detection signal Wy (t) after this amplification processing is input to the low-pass filter circuit 104. The low-pass filter circuit 104 removes a noise component in a relatively high frequency band included in the input analog load detection signal Wy (t), for example, a noise component mainly due to an electrical factor of 100 [Hz] or more. The analog load detection signal Wy (t) after the analog filtering processing by the low-pass filter circuit 104 is input to the A / D conversion circuit 106.

  The A / D conversion circuit 106 samples the input analog load detection signal Wy (t) in accordance with the rising edge of the clock pulse CK supplied from the clock pulse (CK) generation circuit 108 as pulse generation means. Thereby, the analog load detection signal Wy (t) is converted into a load detection signal Wy [i] (i: sampling number) in a digital form. The sampling period by the A / D conversion circuit 106, that is, the period ΔT of the clock pulse CK is, for example, 1 [ms].

The digital load detection signal Wy [i] converted by the A / D conversion circuit 106 is sent to the CPU (Central Processing Unit) via the input / output interface circuit 110.
Processing Unit) 112. The CPU 112 obtains the weight measurement value Wo [i] based on the input digital load detection signal Wy [i], and more specifically, based on a digital load detection signal Wy ′ [i] after a digital filtering process described later. Further, the CPU 112 creates a selection signal So based on the weight measurement value Wo [i]. The sorting signal So is sent to the above-described sorting device via the input / output interface circuit 110.

  The CPU 112 is connected to a memory circuit 114 as a storage unit, and the memory circuit 114 stores a control program for controlling the operation of the CPU 112. Further, the CPU 112 includes an operation key 116 as an instruction input means for inputting various instructions to the CPU 112, a liquid crystal display 118 as an information output means for outputting various information according to the operation of the CPU 112, and the like. They are connected via the input / output interface circuit 110. The operation keys 116 and the display 118 may be integrated with each other, for example, a touch screen.

  Here, when the weight sorter 10 of the present embodiment is operating, in other words, the analog load detection signal Wy (t) when the motor 40 and the three rotating bodies 26 and 28 are rotating are rotating. When paying attention, three vibration components Wa (t), Wb (t) and Wc (t) as shown in an exaggerated manner in FIG. 3 are superimposed on the analog load detection signal Wy (t). Among them, the vibration component Wa (t) shown in (a) is caused by the rotation of the motor 40, and particularly caused by an eccentric load of a rotating member (not shown) of the motor 40. Therefore, the period Ta of the vibration component Wa (t) caused by the motor 40 is the same as the rotation period of the motor 40. When this is converted into the frequency fa, it is about several [Hz] to about several tens [Hz]. is there. The vibration component Wb (t) shown in FIG. 3B is due to the eccentric load of the drive pulley 26, and the period Tb () of the vibration component Wb (t) due to the drive pulley 26 is shown. Alternatively, the frequency fb) is the same as the period Ta (or frequency fa) of the vibration component Wa (t) caused by the motor 40. Further, the vibration component Wc (t) shown in FIG. 3C is caused by the eccentric load of the driven pulley 28, and the period Tc () of the vibration component Wc (t) caused by the driven pulley 28 is shown. Alternatively, the frequency fc) is basically the same as the period Tb (or frequency fb) of the vibration component Wb (t) caused by the driving pulley 26, that is, the vibration component Wa (t) caused by the motor 40. Is the same as the period Ta (or frequency fa).

  However, strictly speaking, the cycle Tc of the vibration component Wc (t) caused by the driven pulley 28 is equal to the cycle Tb of the vibration component Wb (t) caused by the drive pulley 26 (or the vibration component caused by the motor 40). It is not always the same as the cycle Ta) of Wa (t). This is because although the diameters of the pulleys 26 and 28 are the same as described above, there may be some errors in the diameters. Further, when the diameters of the pulleys 26 and 28 are different from each other in this way, the relationship between the phases (initial phases) θb and θc of the respective vibration components Wb (t) and Wc (t) also changes. (Θb−θc) changes. This change in phase difference is also caused by each pulley 26 and 28 slipping between the conveyor belt 24.

  Further, when attention is paid to the relationship between the phase θa of the vibration component Wa (t) caused by the motor 40 and the phase θb of the vibration component Wb (t) caused by the drive pulley 26, this relationship can also change. That is, the timing belt 38 that connects the motor 40 and the driving pulley 26 may be removed as necessary for maintenance or the like. In this case, the timing belt 38 is newly attached. At this time, the relationship between the phases θa and θb is different from that before the timing belt 38 is removed, that is, the phase difference between both (θa−θb). to make the transition. Accordingly, there is also a difference in the relationship (θa−θc) between the phase θa of the vibration component Wa (t) caused by the motor 40 and the phase θc of the vibration component Wc (t) caused by the driven pulley 28. occur.

  Needless to say, these vibration components Wa (t), Wb (t) and Wc (t) cause a decrease in measurement accuracy. Therefore, it is necessary to remove these vibration components Wa (t), Wb (t) and Wc (t). However, the modes of the vibration components Wa (t), Wb (t), and Wc (t), for example, the amplitudes Aa, Ab, and Ac shown in FIG. , Depending on the rotational speeds of the driving pulley 26 and the driven pulley 28, in other words, depending on the running speed (conveyor speed) of the conveyor belt 24. The amplitudes Aa, Ab, and Ac also vary depending on the weight Wo of the object to be weighed 18 including the presence or absence of the object to be weighed 18. Further, in FIG. 4, each curve indicated by a broken line represents a vibration force corresponding to each vibration component Wa (t), Wb (t), and Wc (t). The phase lag angles φa, φb and φc of t), Wb (t) and Wc (t) also depend on the conveyor speed and the weight Wo of the object 18 to be weighed. In order to accurately remove the vibration components Wa (t), Wb (t), and Wc (t) having such properties, the present embodiment is devised as follows.

  That is, the weight sorter 10 according to the present embodiment is operated according to one of the two operating conditions shown in FIG. For example, in the operating condition 1, the object to be weighed 18 of K1 is selected, and the conveyor speed V1 is automatically set. In addition, the to-be-measured object 18 of the kind called K1 shows the weight distribution of a normal distribution form, and has a standard weight (average weight) called W1 on this weight distribution. And in the operating condition 2, the to-be-measured object 18 of the kind called K2 is made into a selection object, and the conveyor speed of V2 is set automatically. The to-be-measured object 18 of the kind called K2 also shows a weight distribution having a generally normal distribution, and has a standard weight of W2 on the weight distribution.

  In any of these operating conditions 1 and 2, the above-described weight measurement value Wo [i] is obtained based on the following equation 2.

<< Formula 2 >>
Wo [i]
= Α · {Wy [i] −Wh−Wz− (Wa [i] + Wb [i] + Wc [i])}
= Α · {Wy [i] −We− (Wa [i] + Wb [i] + Wc [i])}
≒ Wo
where We = Wh + Wz

  In Expression 2, α is a span coefficient as an adjustment coefficient. Wh is a tare component applied to the load cell 30 from the beginning. The tare component Wh includes a load component due to foreign matters such as water droplets and dust adhering to the load cell 30 and the conveyor main body 22 supported by the load cell 30. Further, Wz is a zero shift component that inevitably exists like an offset component of the amplifier circuit 102 or the like. The tare component Wh and the zero shift component Wz are combined into one as the initial load component We. Wa [i], Wb [i] and Wc [i] are digital forms of the respective vibration components Wa (t), Wb (t) and Wc (t).

  As can be seen from Equation 2, if the span coefficient α, the initial load component We, and the vibration components Wa [i], Wb [i], and Wc [i] are found, the digital load detection signal Wy [ By substituting i], the weight measurement value Wo [i] is obtained, that is, the weight Wo of the object to be weighed 18 is obtained. However, the modes of the vibration components Wa [i], Wb [i] and Wc [i], particularly the amplitudes Aa, Ab and Ac and the phase delay angles φa, φb and φc shown in FIG. , Depending on the conveyor speed and the weight Wo of the object to be weighed 18 including the presence or absence of the object to be weighed 18. in short. It depends on which of operating conditions 1 and 2 is set. Also, the periods Ta, Tb, and Tc shown in FIG. 3 are the same as the rotation periods of the motor 40, the driving pulley 26, and the driven pulley 28 as the corresponding rotating bodies, and the phases θa, θb, and θc are Depends on the rotation angles of the motor 40, the driving pulley 26 and the driven pulley 28, respectively.

  Therefore, first, an optical rotary encoder 200 as shown in FIG. 6 is attached to the rotation shaft 42 of the motor 40 in order to detect the rotation angle of the motor 40. Specifically, the rotary encoder 200 includes a disk-shaped rotating disk 202 and two optical sensors 204 and 206. Among these, the rotating disk 202 is made of metal such as aluminum, and is fixed to the rotating shaft 42 of the motor 40 so as to rotate around the rotating shaft 42 of the motor 40. Further, a plurality of through holes 208, 208,... Are provided in the vicinity of the periphery of the rotating disk 202 at equal intervals along the circumferential direction. Further, a substantially concave notch 210 having a width wider than the through hole 208 is provided at one peripheral edge portion of the rotating disk 202. On the other hand, each of the optical sensors 204 and 206 is, for example, a reflection type, that is, a so-called photoreflector. The through holes 208, 208,... Are detected by one optical sensor 204, and the notches are cut by the other optical sensor 206. It is held by a suitable fixing member 210 so that 210 can be detected. That is, one photosensor 204 outputs the same number of rectangular pulses as the through holes 208, 208,... Each time the motor 40 (rotating shaft 42) makes one rotation. A one-rotation divided signal Da indicating that the angle (circumference) is divided by the number of the through holes 208, 208,... Is output. The other optical sensor 206 outputs one rectangular pulse every time the motor 40 makes one rotation, that is, outputs one rotation detection signal Sa indicating that the motor 40 has made one rotation. These signals Da and Sa are given to the above-described indicator 100 as angle detection signals, and in detail, are given to the CPU 112 via the input / output interface circuit 110.

  As shown in FIG. 6, the same rotary encoder 300 is attached to the rotating shaft 48 of the driving pulley 26. The angle detection signals (one rotation division signal and one rotation signal) Db and Sb output from the rotary encoder 300 are also given to the indicator 100. Further, the same rotary encoder 400 is attached to the rotating shaft 50 of the driven pulley 28. The angle detection signals Dc and Sb output from the rotary encoder 400 are also provided to the indicator 100.

  As described above, the rotary encoders 200, 300, and 400 are attached to the motor 40 as the rotating body and the pulleys 26 and 28, and prior adjustment work is performed.

  That is, the adjustment mode is selected by operating the operation key 116 shown in FIG. Thereby, the CPU 112 enters the adjustment mode. Then, the timing belt 38 is removed. The removed timing belt 38 is placed at an appropriate location on the conveyor body 22 as a component of the tare, that is, is supported by the load cell 30. Instead of the removed timing belt 38, an alternative having the same weight as the timing belt 38 may be placed on the conveyor body 22.

  Here, when the motor 40 is in a stopped state and the object to be weighed 18 is not placed on the conveyor body 22, the above Equation 2 is expressed as the following Equation 3.

<< Formula 3 >>
Wy [i] = We
Ｗ Wo = 0, Wa [i] = 0, Wb [i] = 0, Wc [i] = 0

  In this state, a zero adjustment command is input by operating the operation key 116. Then, the CPU 112 stores the digital load detection signal Wy [i] at this time in the memory circuit 114 as the initial load component We. Strictly speaking, the digital load detection signal Wy ′ [i] after the digital filtering process described below is stored as the initial load component We.

  In order to realize this digital filtering processing, the CPU 114 constitutes a zero adjustment circuit 500 shown in FIG. The zero adjustment circuit 500 includes a digital filter circuit 502, and the digital load detection signal Wy [i] is input to the digital filter circuit 502. The digital filter circuit 502 applies an appropriate digital filtering process such as a moving average process to the input digital load detection signal Wy [i], so that a relatively low frequency included in the digital load detection signal Wy [i] is obtained. A noise component of a band, for example, a noise component of 50 [Hz] to 100 [Hz] including a frequency band of a commercial AC power supply is removed. Then, the signal Wy ′ [i] after the digital filtering process by the digital filter circuit 502 is stored in the memory circuit 114 as the initial load component We.

  Subsequently, the operating condition 1 is set by operating the operation key 116, and then the motor 40 is operated. As described above, since the timing belt 38 is removed, only the motor 40 rotates at a speed corresponding to the conveyor speed of V1, and the pulleys 26 and 28 do not rotate. Therefore, the digital load detection signal Wy [i] at this time includes only the initial load component We and the vibration component Wa [i] caused by the motor 40. Therefore, the previously stored initial load component We is subtracted from the digital load detection signal Wy [i]. As a result, the vibration component Wa [i] due to the motor 40 is extracted. Based on the extracted vibration component Wa [i], a correction signal Wa [pa] for removing the vibration component Wa [i] is generated.

  Specifically, when the vibration component Wa [i] caused by the motor 40 is illustrated with the one-rotation detection signal Sa, the one-rotation divided signal Da, and the clock pulse CK for the motor 40, for example, as in FIG. As shown in FIG. 8, the single rotation detection signal Sa in FIG. 8A becomes H (high) level when the notch 210 shown in FIG. 6 is detected by the optical sensor 206 for detecting the notch 210. Otherwise, it is a binary signal that is L (low) level. The one-rotation divided signal Da in (b) becomes H level each time the through holes 208, 208,... Are detected by the photosensors 204 for detection. It is a binary signal that sometimes becomes L level. The period Tsa in which the one rotation detection signal Sa is at the H level includes a certain H level period Tda of the one rotation division signal Da. Further, the H level period Tsa of the one rotation detection signal Sa is longer than the H level period Tda of the one rotation division signal Da (Tsa> Tda). These signals Sa and Da are given to the CPU 112 as described above. Furthermore, since the clock pulse CK in (c) is a short-cycle signal having a period ΔT of 1 [ms], it appears many times in each period of the one-rotation detection signal Sa and one-rotation divided signal Sp, It appears many times during the H level periods Tsa and Tda. The vibration component Wa [i] of (d) is in a digital form as described above, but here, it is expressed in an analog form for convenience of explanation.

  The CPU 112 starts from the time ta when the rising edge of the clock pulse CK first arrives in the H level period Tda of the one rotation division signal Da included in the H level period Ta of the one rotation detection signal Sa. In the H level period Tda of the one-rotation divided signal Da included in the H level period Ta, the period up to the time ta ′ when the rising edge of the clock pulse CK first arrives is recognized as the period Ta of the vibration component Wa [i]. . Further, the CPU 112 delimits the period Ta every time the rising edge of the clock pulse CK first arrives in each H level period Tda of the one-rotation divided signal Da, and separates Pa intervals pa of 0 to Pa−1. Set. The number Pa of the section pa is the same as the number of the through holes 208, 208,.

  Then, the CPU 112 resamples the vibration component Wa [i] in synchronization with the rising edge of the clock pulse CK for each section pa, and removes the vibration component Wa [i] in the section pa from the average value. The correction signal Wa [pa] for this purpose. This correction signal Wa [pa] is a signal for motor correction for removing the vibration component Wa [i] caused by the motor 40. Specifically, in the operating condition 1, the object to be weighed 18 is not placed. As shown in FIG. 9, it is stored in a predetermined register (storage area) 600 in the memory circuit 114 as an anti-motor correction signal Wa01 [pa] for when in a state. The counter-motor correction signal Wa10 [pa] is generated over a plurality of cycles, and the counter-motor correction signal Wa01 [pa] over the plurality of cycles is averaged for each section pa and stored in the register 600. May be.

  In order to generate the anti-motor correction signal Wa01 [pa], the CPU 112 configures an anti-motor correction signal generation circuit 510 shown in FIG. 10 in terms of software. In other words, the motor correction signal generation circuit 510 uses the digital filter circuit 502 shown in FIG. 7, and the digital load detection signal Wy [i] is input to the digital filter circuit 502. Then, the signal Wy ′ [i] after the digital filtering processing by the digital filter circuit 502 is input to the adding circuit 512. The initial load component We previously stored is input to the adder circuit 512, and the adder circuit 512 subtracts the initial load component We from the digital load detection signal Wy ′ [i]. Thereby, the vibration component Wa [i] due to the motor 40 is extracted. Further, the vibration component Wa [i] is input to the resampling circuit 514. In addition to this, the re-sampling circuit 514 receives the one-rotation detection signal Sa, the one-rotation divided signal Da, and the clock pulse CK for the motor 40, and the re-sampling circuit 514 performs correction in the manner described above. A signal Wa [pa] is generated. The correction signal Wa [pa] is stored in the register 600 in the memory circuit 114 as the anti-motor correction signal Wa01 [pa] shown in FIG.

  Subsequently, the operating condition 2 is set by operating the operation key 116. Then, the motor 40 rotates at a speed corresponding to the conveyor speed of V2. Each pulley 26 and 28 still does not rotate. Accordingly, the digital load detection signal Wy [i] at this time includes only the initial load component We and the vibration component Wa [i] caused by the motor 40 as described above. However, the vibration component Wa [i] is an aspect when the weighing object 18 is not placed under the operating condition 2. Therefore, the digital load detection signal Wy [i] at this time is processed by the signal generation circuit 510 for correcting the motor shown in FIG. 10, so that the object 18 is placed under the operating condition 2. An anti-motor correction signal Wa02 [pa] for when there is no state is generated. The anti-motor correction signal Wa02 [pa] is stored in another register 602 in the memory circuit 114 as shown in FIG. Note that the motor correction signal Wa02 [pa] may also be averaged for each section pa over a plurality of cycles. The same applies to the other two types of anti-motor correction signals Wa1 [pa] and Wa2 [pa] described later.

  Thereafter, the motor 40 is temporarily stopped. Then, an article (not shown) having the same kind as the kind K1 of the operating condition 1 and the same weight as the standard weight W1 is placed in a suitable place on the conveyor body 22 as a dummy of the object 18 to be weighed. Is done. Then, a zero adjustment command is input again by operating the operation key 116. Then, the CPU 114 reconfigures the zero adjustment circuit 500 shown in FIG. The digital load detection signal Wy ′ [i] processed by the zero adjustment circuit 500 is stored in the memory circuit 114 as the initial load component We. That is, the initial load component We including the weight W1 of the dummy article is stored again.

  Then, the operating condition 1 is set by operating the operation key 116, and the motor 40 is operated. The digital load detection signal Wy [i] at this time also includes only the initial load component We and the vibration component Wa [i] caused by the motor 40. The vibration component Wa [i] In the operating condition 1, it is an aspect when the object to be weighed 18 having the standard weight Wo (= W1) is placed. Therefore, the digital load detection signal Wy [i] at this time is processed by the signal generation circuit 510 for correcting the motor shown in FIG. As a result, the motor correction signal Wa1 [pa] for when the object 18 having the standard weight Wo is placed under the operating condition 1 is generated. The anti-motor correction signal Wa1 [pa] is stored in another register 604 in the memory circuit 114 as shown in FIG.

  Thereafter, the motor 40 is stopped again. Then, instead of the dummy article for the operating condition 1 placed on the conveyor body 22, the dummy article for the operating condition 2, more specifically, the same kind as the kind K2 of the operating condition 2, and the standard weight An article (not shown) having the same weight as W2 is placed on the conveyor body 22. Then, a zero adjustment command is input again by operating the operation key 116. Thereby, the initial load component We including the weight W2 of the dummy article for the operating condition 2 is stored again.

  Then, the operation condition 2 is set by operating the operation key 116, and the motor 40 is operated. The digital load detection signal Wy [i] at this time also includes only the initial load component We and the vibration component Wa [i] caused by the motor 40. The vibration component Wa [i] In the operating condition 2, the measurement object 18 having the standard weight Wo (= W2) is placed. Therefore, the digital load detection signal Wy [i] at this time is processed by the signal generation circuit 510 for correcting motor for motor shown in FIG. An anti-motor correction signal Wa2 [pa] for when the object 18 is placed is generated. The anti-motor correction signal Wa2 [pa] is stored in a further register 606 in the memory circuit 114 as shown in FIG.

  After the four types of motor correction signals Wa01 [pa], Wa02 [pa], Wa1 [pa] and Wa2 [pa] are obtained in this way, the motor 40 is stopped. Then, the dummy article for operating condition 2 placed on the conveyor body 22 is removed from the conveyor body 22. In addition, the timing belt 38 is attached and returned to the original state. This time, the conveyor belt 24 is removed. The removed conveyor belt 24 is placed at an appropriate location on the conveyor body 22 as a component of the tare. Instead of the removed conveyor belt 24, an alternative having the same weight as the conveyor belt 24 may be placed on the conveyor body 22.

  In this state, a zero adjustment command is input again by operating the operation key 116. Thereby, the initial load component We is stored again. That is, the initial load component We when the object to be weighed 18 (including the dummy article) is not placed on the conveyor body 22 is stored again.

  Then, the operating condition 1 is set by operating the operation key 116, and the motor 40 is operated. Then, the motor 40 and the driving pulley 26 rotate at a speed corresponding to the conveyor speed of V1. The driven pulley 28 does not rotate. Accordingly, the digital load detection signal Wy [i] at this time includes an initial load component We, a vibration component Wa [i] caused by the motor 40, and a vibration component Wb [i] caused by the driving pulley 26. It will be included. Therefore, the initial load component We and the vibration component Wa [i] caused by the motor 40 are subtracted from the digital load detection signal Wy [i]. As a result, the vibration component Wb [i] due to the driving pulley 26 is extracted. Based on the extracted vibration component Wb [i], a correction signal Wb [pb] for removing the vibration component Wb [i] is generated.

  Specifically, the vibration component Wb [i] due to the driving pulley 26 is illustrated by entwining the one rotation detection signal Sb, the one rotation division signal Db, and the clock pulse CK for the driving pulley 26. Then, like FIG. 8 mentioned above, it becomes like FIG. 14, for example. In the same manner as described with reference to FIG. 8, the CPU 112 corrects the correction signal Wb [pb] for removing the vibration component Wb [i] caused by the driving pulley 26 for each section pb. Is generated. This correction signal Wb [pb] is a signal for correcting the pulley on the driving side for removing the vibration component Wb [i] caused by the driving pulley 26. More specifically, the driving object 18 is loaded under the operating condition 1. As shown in FIG. 15, it is stored in a further register 610 in the memory circuit 114 as a driving-side pulley correction signal Wb01 [pb] for when it is not placed. In addition, as for this anti-driving side pulley correction signal Wb01 [pb], an average value for each section pb over a plurality of cycles may be stored in the register 610.

  In order to generate the driving pulley correction signal Wb01 [pb], the CPU 112 configures the driving pulley correction signal generation circuit 520 shown in FIG. That is, the driving pulley correction signal generation circuit 520 also uses the digital filter circuit 502 shown in FIG. 7, and the digital load detection signal Wy [i] is input to the digital filter circuit 502. . The signal Wy ′ [i] after the digital filtering process by the digital filter circuit 502 is input to the same adder circuit 512 as shown in FIG. The initial load component We is input to the adder circuit 512, and the adder circuit 512 subtracts the initial load component We from the digital load detection signal Wy ′ [i]. As a result, a vibration signal Wy ″ [i] including the vibration component Wa [i] attributed to the motor 40 and the vibration component Wb [i] attributed to the driving pulley 26 is generated. Wy ″ [i] is input to another adder circuit 522 at the subsequent stage of the adder circuit 512. In addition to the vibration signal Wy ″ [i], the adder circuit 522 in the subsequent stage receives the signal for motor correction Wa [pa] corresponding to the current situation from the readout circuit 524, that is, in the operating condition 1. An anti-motor correction signal Wa01 [pa] for when the object to be weighed 18 is not placed is input The reading circuit 524 detects one rotation of the motor 40 supplied thereto. The motor correction signal Wa01 [pa] is read from the register 600 shown in Fig. 9 in accordance with the timing of the signal Sa, the one-rotation divided signal Da, and the clock pulse CK. The motor correction signal Wa01 [pa] is subtracted from the vibration signal Wy ″ [i]. As a result, only the vibration component Wb [i] due to the drive pulley 26 is extracted. Further, this vibration component Wb [i] is input to the same resampling circuit 514 as shown in FIG. In addition to the vibration component Wb [i], the re-sampling circuit 514 receives the one-rotation detection signal Sb, the one-rotation divided signal Db, and the clock pulse CK for the driving pulley 26. Generates the counter-drive-side pulley correction signal Wb [pb] in the same manner as when generating the counter-motor correction signal Wa [pa]. Then, as shown in FIG. 15, the driving-side pulley correction signal Wb [pb] is a correction signal Wb01 [when the object 18 is not placed under the operating condition 1. pb] is stored in the register 610.

  Subsequently, the operating condition 2 is set by operating the operation key 116. Then, the motor 40 and the driving pulley 26 rotate at a speed corresponding to the conveyor speed of V2. Note that the driven pulley 28 still does not rotate. Therefore, the digital load detection signal Wy [i] at this time also includes the initial load component We, the vibration component Wa [i] caused by the motor 40, and the vibration component Wb [i] caused by the drive pulley 26. Will be included. However, each of the vibration components Wa [i] and Wb [i] is an aspect when the weighing object 18 is not placed under the operating condition 2. Therefore, the digital load detection signal Wy [i] at this time is processed by the anti-driving side pulley correction signal generation circuit 520 shown in FIG. A driving-side pulley correction signal Wb02 [pb] is generated for a state in which it is not. However, when generating the driving-side pulley correction signal Wb02 [pb], the readout circuit 524 reads out the motor correction signal Wa02 [pa] from the register 602 shown in FIG. The generated anti-drive-side pulley correction signal Wb02 [pb] is stored in another register 612 in the memory circuit 114 as shown in FIG. In addition, as for this anti-drive side pulley correction signal Wb02 [pb], an averaged signal for each section pb over a plurality of cycles may be stored. The same applies to the other two types of driving-side pulley correction signals Wb1 [pb] and Wb2 [pb] described later.

  Thereafter, the motor 40 is stopped again. Then, the dummy article for the operating condition 1 described above is placed at an appropriate location on the conveyor body 22. Then, a zero adjustment command is input again by operating the operation key 116. Thereby, the initial load component We including the weight W1 of the dummy article for the operating condition 1 is stored again.

  Then, the operating condition 1 is set by operating the operation key 116, and the motor 40 is operated. The digital load detection signal Wy [i] at this time also includes an initial load component We, a vibration component Wa [i] caused by the motor 40, and a vibration component Wb [i] caused by the driving pulley 26. However, each of the vibration components Wa [i] and Wb [i] has a mode in which the object to be weighed 18 having a standard weight Wo is placed under the operating condition 1. Become. The digital load detection signal Wy [i] is processed by the anti-driving pulley correction signal circuit 520 shown in FIG. As a result, the driving-side pulley correction signal Wb1 [pb] for when the object 18 having the standard weight Wo is placed under the operating condition 1 is generated. Note that in generating the driving-side pulley correction signal Wb1 [pb], the reading circuit 524 reads the motor-correcting signal Wa1 [pa] from the register 604 illustrated in FIG. The generated anti-driving pulley correction signal Wb1 [pb] is stored in another register 614 in the memory circuit 114 as shown in FIG.

  Thereafter, the motor 40 is stopped again. Then, instead of the dummy article for operation condition 1 placed on the conveyor body 22, the dummy article for operation condition 2 described above is placed on the conveyor body 22. Then, a zero adjustment command is input again by operating the operation key 116. Thereby, the initial load component We including the weight W2 of the dummy article for the operating condition 2 is stored again.

  Then, the operation condition 2 is set by operating the operation key 116, and the motor 40 is operated. The digital load detection signal Wy [i] at this time also includes an initial load component We, a vibration component Wa [i] caused by the motor 40, and a vibration component Wb [i] caused by the driving pulley 26. However, each of the vibration components Wa [i] and Wb [i] is an aspect when the weighing object 18 having a standard weight Wo is placed under the operating condition 2. Become. This digital load detection signal Wy [i] is processed by the anti-driving pulley correction signal circuit 520 shown in FIG. As a result, the driving-side pulley correction signal Wb2 [pb] for when the object 18 having the standard weight Wo is placed under the operating condition 2 is generated. Note that in generating the driving-side pulley correction signal Wb2 [pb], the reading circuit 524 reads the motor-correcting signal Wa2 [pa] from the register 606 shown in FIG. Then, the generated driving-side pulley correction signal Wb2 [pb] is stored in yet another register 616 in the memory circuit 114, as shown in FIG.

  After the four types of driving-side pulley correction signals Wb01 [pb], Wb02 [pb], Wb1 [pb] and Wb2 [pb] are thus obtained, the motor 40 is stopped again. Then, the dummy article for operating condition 2 placed on the conveyor body 22 is removed from the conveyor body 22. At the same time, the conveyor belt 24 is attached and returned to the original state.

  In this state, a zero adjustment command is input again by operating the operation key 116. Thereby, the initial load component We is stored again.

  Then, the operating condition 1 is set by operating the operation key 116, and the motor 40 is operated. Then, all the rotating bodies of the motor 40 and the pulleys 26 and 28 rotate at a speed corresponding to the conveyor speed of V1. Accordingly, the digital load detection signal Wy [i] at this time includes the initial load component We, the vibration component Wa [i] caused by the motor 40, the vibration component Wb [i] caused by the drive pulley 26, and the driven The vibration component Wc [i] resulting from the side pulley 28 is included. Therefore, the initial load component We, the vibration component Wa [i] caused by the motor 40, and the vibration component Wb [i] caused by the driving pulley 26 are subtracted from the digital load detection signal Wy [i]. . As a result, the vibration component Wc [i] due to the driven pulley 28 is extracted. Based on the extracted vibration component Wb [i], a correction signal Wb [pb] for removing the vibration component Wb [i] is generated.

  Specifically, the vibration component Wc [i] caused by the driven pulley 28 is illustrated by entwining the one rotation detection signal Sc, the one rotation divided signal Dc, and the clock pulse CK for the driven pulley 28. Then, like FIG. 8 mentioned above, it becomes like FIG. 20, for example. The CPU 112 performs a correction signal Wc [pc] for removing the vibration component Wc [i] caused by the driven pulley 28 for each section pc in the same manner as described with reference to FIG. Is generated. The correction signal Wc [pc] is a signal for correcting the driven pulley for removing the vibration component Wc [i] caused by the driven pulley 28c. Is stored in yet another register 620 in the memory circuit 114, as shown in FIG. 21, as a counter-driven pulley correction signal Wc01 [pc]. In addition, as for this counter-side pulley correction signal Wc01 [pc], an average value for each section pc over a plurality of periods may be stored in the register 620.

  In order to generate this driven pulley correction signal Wc01 [pc], the CPU 112 configures the driven pulley correction signal generation circuit 530 shown in FIG. That is, the driven pulley correction signal generation circuit 530 also uses the digital filter circuit 502 shown in FIG. 7, and the digital load detection signal Wy [i] is input to the digital filter circuit 502. . The signal Wy ′ [i] after the digital filtering process by the digital filter circuit 502 is input to the same adder circuit 512 as shown in FIG. The initial load component We is input to the adder circuit 512, and the adder circuit 512 subtracts the initial load component We from the digital load detection signal Wy ′ [i]. As a result, a vibration signal composed of a vibration component Wa [i] attributed to the motor 40, a vibration component Wb [i] attributed to the driving pulley 26, and a vibration component Wc [i] attributed to the driven pulley 28. Wy ″ [i] is generated. Further, the vibration signal Wy ″ [i] is input to the adder circuit 522 at the subsequent stage as shown in FIG. The adder circuit 522 in the subsequent stage is supplied from the same readout circuit 524 as shown in FIG. 16 with respect to the motor correction signal Wa [pa] corresponding to the current situation, that is, in the operating condition 1, the object 18 to be weighed. Is input to the motor correction signal Wa01 [pa] when the motor is not mounted. In addition, the driving circuit pulley correction signal Wb01 [pb] corresponding to the current situation is input to the adding circuit 522 from another reading circuit 532. In addition, the other readout circuit 532 is similar to the readout circuit 524 in accordance with the timings of the one-rotation detection signal Sb, the one-rotation division signal Db, and the clock pulse CK for the driving pulley 26 supplied thereto. The counter-drive-side pulley correction signal Wb01 [pb] is read from the register 610 shown in FIG. Then, the subsequent addition circuit 522 subtracts the anti-motor correction signal Wa01 [pa] and the anti-driving pulley correction signal Wb01 [pb] from the vibration signal Wy ″ [i]. Only the resulting vibration component Wc [i] is extracted, and this vibration component Wc [i] is input to the same resampling circuit 514 as shown in FIG. In addition to the vibration component Wc [i], the one-rotation detection signal Sc, the one-rotation divided signal Dc, and the clock pulse CK for the driven pulley 28 are input, and the re-sampling circuit 514 The driven pulley correction signal Wc [pc] is generated in the same manner as when Wa [pa] is generated, and the driven pulley correction signal Wc [pc]. As shown in FIG. 21, in the operating condition 1, as the correction signal Wc01 for when in the state in which the objects to be weighed 18 is not placed [pc], it is stored in the register 620.

  Subsequently, the operating condition 2 is set by operating the operation key 116. Then, the motor 40 and the pulleys 26 and 28 rotate at a speed corresponding to the conveyor speed of V2. Therefore, the digital load detection signal Wy [i] at this time also includes the initial load component We, the vibration component Wa [i] caused by the motor 40, and the vibration component Wb [i] caused by the drive pulley 26. The vibration component Wc [i] resulting from the driven pulley 28 is included. However, each of the vibration components Wa [i], Wb [i], and Wc [i] is an aspect when the weighing object 18 is not placed under the operating condition 2. Therefore, the digital load detection signal Wy [i] at this time is processed by the driven pulley correction signal generation circuit 530 shown in FIG. 22 so that the object 18 is placed under the operating condition 2. A driven-side pulley correction signal Wc02 [pc] is generated for the non-operating state. However, when generating the driven pulley correction signal Wc02 [pc], the read circuit 524 reads the anti-motor correction signal Wa02 [pa] from the register 602 shown in FIG. At the same time, the other readout circuit 532 reads out the driving pulley correction signal Wb02 [pb] from the register 612 shown in FIG. Then, the generated driven pulley correction signal Wc02 [pc] is stored in yet another register 622 in the memory circuit 114 as shown in FIG. Note that the driven pulley correction signal Wc02 [pc] may also be averaged for each section pc over a plurality of cycles. The same applies to the other two types of the following driven pulley correction signals Wc1 [pc] and Wc2 [pc].

  Thereafter, the motor 40 is stopped again. Then, the dummy article for the operating condition 1 described above is placed at an appropriate location on the conveyor body 22. Then, a zero adjustment command is input again by operating the operation key 116. Thereby, the initial load component We including the weight W1 of the dummy article for the operating condition 1 is stored again.

  Then, the operating condition 1 is set by operating the operation key 116, and the motor 40 is operated. The digital load detection signal Wy [i] at this time also includes an initial load component We, a vibration component Wa [i] caused by the motor 40, a vibration component Wb [i] caused by the driving pulley 26, and a driven side. The vibration component Wc [i] caused by the pulley 28 is included, and each vibration component Wa [i], Wb [i], and Wc [i] This is a mode when the object to be weighed 18 having Wo is placed. The digital load detection signal Wy [i] is processed by the driven pulley correction signal circuit 530 shown in FIG. As a result, the driven-side pulley correction signal Wc1 [pc] for when the object 18 having the standard weight Wo is placed under the operating condition 1 is generated. Note that when generating the driven pulley correction signal Wc1 [pc], the reading circuit 524 reads the anti-motor correction signal Wa1 [pa] from the register 604 shown in FIG. At the same time, the other readout circuit 532 reads out the driving-side pulley correction signal Wb1 [pb] from the register 614 shown in FIG. The generated driven pulley correction signal Wc1 [pc] is stored in a further register 624 in the memory circuit 114 as shown in FIG.

  Thereafter, the motor 40 is stopped again. Then, instead of the dummy article for operation condition 1 placed on the conveyor body 22, the dummy article for operation condition 2 described above is placed on the conveyor body 22. Then, a zero adjustment command is input again by operating the operation key 116. Thereby, the initial load component We including the weight W2 of the dummy article for the operating condition 2 is stored again.

  Then, the operation condition 2 is set by operating the operation key 116, and the motor 40 is operated. The digital load detection signal Wy [i] at this time also includes an initial load component We, a vibration component Wa [i] caused by the motor 40, a vibration component Wb [i] caused by the driving pulley 26, and a driven side. The vibration component Wc [i] caused by the pulley 28 is included, and each vibration component Wa [i], Wb [i], and Wc [i] This is a mode when the object to be weighed 18 having Wo is placed. The digital load detection signal Wy [i] is processed by the anti-drive pulley correction signal circuit 520 shown in FIG. As a result, the driven pulley correction signal Wc2 [pc] is generated under the operating condition 2 when the workpiece 18 having the standard weight Wo is placed. Note that, in generating the counter-driven pulley correction signal Wc2 [pc], the read circuit 524 reads the counter-motor correction signal Wa2 [pa] from the register 606 shown in FIG. At the same time, the other readout circuit 532 reads out the driving-side pulley correction signal Wb2 [pb] from the register 616 shown in FIG. The generated driven pulley correction signal Wc2 [pc] is stored in another register 626 in the memory circuit 114 as shown in FIG.

  After the four types of correction signals Wc01 [pc], Wc02 [pc], Wc1 [pc] and Wc2 [pc] for the driven pulley 28 are thus obtained, the motor 40 is stopped again. Then, the dummy article for operating condition 2 placed on the conveyor body 22 is removed from the conveyor body 22.

  The four types of anti-motor correction signals Wa01 [pa], Wa02 [pa], Wa1 [pa] and Wa2 [pa] obtained in the above manner, and the four types of anti-motor correction signals Wb01 [pb]. , Wb02 [pb], Wb1 [pb] and Wb2 [pb], and four types of driven pulley correction signals Wc01 [pc], Wc02 [pc], Wc1 [pc] and Wc2 [pc] The data is stored in the memory circuit 114 in a state gathered in the correction signal list 700 as shown in FIG. That is, in the operating condition 1, the correction signals Wa01 [pa], Wb01 [pb] and Wc01 [pc] for when the object 18 is not placed are grouped into a group G01. Then, under the operating condition 1, the correction signals Wa1 [pa], Wb1 [pb], and Wc1 [pc] when the object 18 is placed are grouped into a group G1. Further, in the operating condition 2, the correction signals Wa02 [pa], Wb02 [pb] and Wc02 [pc] for when the object 18 is not placed are grouped into a group G02. In the operating condition 2, the correction signals Wa2 [pa], Wb2 [pb], and Wc2 [pc] for when the object 18 is placed are grouped into a group G2.

  Next, an object to be weighed 18 having a known weight Wo, for example, a weight, is placed on the conveyor body 22 while the motor 40 is stopped. At this time, the above-described formula 2 is expressed as the following formula 4.

<< Formula 4 >>
Wo = α · {Wy [i] −We}
［Wo [i] = Wo, Wa [i] = 0, Wb [i] = 0, Wc [i] = 0

  In this state, a span adjustment command is input by operating the operation key 116. Then, the CPU 112 obtains the span coefficient α so that Expression 4 is satisfied. That is, span adjustment is performed. In this span adjustment, the signal Wy ′ [i] after the digital filtering process by the digital filter circuit 502 shown in FIG. 7 is used instead of the digital load detection signal Wy [i]. The span coefficient α obtained by the span adjustment is also stored in the memory circuit 114.

  This completes the prior adjustment work in the adjustment mode. The operation mode is selected by operating the operation key 116. Then, the CPU 112 enters an operation mode. And the actual operation driving | operation by this operation mode is performed.

  At the time of this operation, as described above, the weight measurement value Wo [i] is obtained based on Equation 2. For this purpose, the CPU 112 configures a vibration component removal circuit 800 shown in FIG. 27 in terms of software.

  That is, the vibration component removal circuit 800 also uses the digital filter circuit 502 shown in FIG. 7, and the digital load detection signal Wy [i] is input to the digital filter circuit 502. The signal Wy ′ [i] after the digital filtering process by the digital filter circuit 502 is input to the same adder circuit 512 as shown in FIG. The adder circuit 512 subtracts the initial load component Wi from the digital load detection signal Wy ′ [i], so that the vibration component Wa [i] caused by the motor 40 and the vibration component Wb [i] caused by the drive pulley 26 are obtained. And a vibration component Wc [i] caused by the driven pulley 28. The vibration component Wy ″ [i] is generated. Further, this vibration component is the same as the subsequent addition circuit shown in FIG. The adder circuit 522 at the subsequent stage is supplied with the signal for correcting motor Wa [pa] corresponding to the current situation from the same readout circuit 524 as shown in FIG. Thus, a counter-drive-side pulley correction signal Wb [pb] corresponding to the current situation is input from the same readout circuit 532 as shown in Fig. 22. Further, from another readout circuit 802, the current Situation The other driven-side pulley correction signal Wc [pc] is input, and the other readout circuit 802 is supplied with the one-rotation detection signal Sc and the one-rotation divided signal Dc for the driven pulley 28 supplied thereto. The clock correction signal Wc [pc] corresponding to the current situation is read in accordance with each timing of the clock pulse CK, and the present situation described here will be described in detail later. The addition circuit 522 subtracts these correction signals Wa [pa], Wb [pb] and Wc [pc] from the vibration signal Wy ″ [i]. As a result, a signal from which all the vibration components Wa [i], Wb [i] and Wc [i] are removed, that is, a weight signal Wo ′ [i] corresponding to only the weight Wo of the object to be weighed 18 is generated. The The weight signal Wo ′ [i] is input to the multiplication circuit 804, where it is multiplied by the span coefficient α described above. As a result, a weight measurement value Wo [i] representing the weight Wo of the object to be weighed 18 is generated.

  Now, the current situation referred to here means which of the four groups G01, G1, G02, and G2 described above is currently selected. This determination is based on which of the above-described setting conditions 1 and 2 is set and whether or not the object to be weighed 18 is placed on the conveyor body 22. Further, the determination as to whether or not the object to be weighed 18 is placed is made by comparing the provisional weight measurement value Wo ″ [i] obtained by the provisional weight measurement circuit 900 shown in FIG. 28 with a predetermined threshold value Wt. Specifically, the provisional weight measurement circuit 900 has a configuration in which the addition circuit 522 and the readout circuits 524, 532, and 802 are omitted from the vibration component removal circuit 800 of FIG. According to the circuit 900, the temporary weight measurement value Wo ″ [i] including the vibration components Wa [i], Wb [i], and Wc [i] is obtained. That is, the provisional weight measurement value Wo ″ [i] is obtained based on the following formula 5.

<< Formula 5 >>
Wo ″ [i] = α · {Wy ′ [i] −We}

  When the temporary weight measurement value Wo ″ [i] is smaller than the threshold value Wt (Wo ″ [i] <Wt), it is determined that the object to be weighed 18 is not placed. On the other hand, when the temporary weight measurement value Wo ″ [i] is equal to or greater than the threshold value Wt (Wo ″ [i] ≧ Wt), it is determined that the object to be weighed 18 is placed. The threshold value Wt is greater than 0 (zero) and sufficiently smaller than the standard weights W1 and W2 of the respective operating conditions 1 and 2 (0 <Wt <W1, 0 <Wt <W2). The

  Here, for example, it is assumed that the operating condition 1 is set and the object to be weighed 18 is not placed. In this case, the group G01 is selected. Then, the readout circuits 524, 532, and 802 send the correction signals Wa01 [pa], Wb01 [pb], and Wc01 [pc] belonging to the group G01 to the respective registers 600, 610, and the respective storage locations. Read from 620. Then, the read correction signals Wa01 [pa], Wb01 [pb], and Wc01 [pc] are input to the subsequent addition circuit 522 as appropriate for the current situation.

  For example, when the operating condition 1 is set and the object 18 is placed, the group G1 is selected. In this case, the readout circuits 524, 532, and 802 receive the correction signals Wa1 [pa], Wb1 [pb], and Wc1 [pc] belonging to the group G1 in the registers 604, 614, which are storage locations, respectively. And 624. Then, the read correction signals Wa1 [pa], Wb1 [pb], and Wc1 [pc] are input to the subsequent addition circuit 522 as appropriate for the current situation.

  Furthermore, for example, when the operating condition 2 is set and the object to be weighed 18 is not placed, the group G02 is selected. In this case, the readout circuits 524, 532, and 802 send the correction signals Wa02 [pa], Wb02 [pb], and Wc02 [pc] belonging to the group G02 to the registers 602, 612, which are their storage locations. And 622. The read correction signals Wa02 [pa], Wb02 [pb], and Wc02 [pc] are input to the subsequent addition circuit 522 as appropriate for the current situation.

  When the operating condition 2 is set and the object 18 is placed, the group G2 is selected. In this case, the readout circuits 524, 532, and 802 send the correction signals Wa2 [pa], Wb2 [pb], and Wc2 [pc] belonging to the group G2 to the registers 606, 616 that are the respective storage locations. And 626. Then, the read correction signals Wa2 [pa], Wb2 [pb], and Wc2 [pc] are input to the subsequent addition circuit 522 as appropriate for the current situation.

  By obtaining the weight measurement value Wo [i] in such a manner, the weighing object including the presence or absence of the weighing object 18 regardless of which of the operating conditions 1 and 2 is set. Regardless of the weight Wo of 18, the precise weight measurement value in which the vibration components Wa [i], Wb [i] and Wc [i] due to the motor 40 and all the rotating bodies 26 and 28 are removed. Wo [i] is required. That is, accurate error correction is realized. And in order to implement | achieve this exact error correction, CPU112 performs the vibration component correction | amendment task shown in FIG. 29 with each subroutine shown in FIGS. 30-33 according to the control program mentioned above. It is assumed that the correction signal list 700 shown in FIG. 26 has already been prepared in executing the vibration component correction task including each subroutine.

  That is, when receiving the rising edge of the clock pulse CK, the CPU 112 proceeds to step S1 in FIG. In step S1, a digital load detection signal Wy [i] is acquired. Further, the CPU 112 proceeds to step S3, and applies a digital filtering process to the digital load detection signal Wy [i]. As a result, the digital load detection signal Wy ′ [i] after the digital filtering process is obtained. Then, the CPU 112 proceeds to step S5, and performs group selection processing for selecting any of the groups G01, G02, G1, and G2 described above. This step S5 will be described in detail later with reference to FIG.

  After execution of step S5, the CPU 112 proceeds to step S7 and determines whether or not the motor 40 is operating. Here, for example, when the motor 40 is not operating, the CPU 112 proceeds to step S9 and performs initial setting. Specifically, “0” is set in each of three flags Fa, Fb, and Fc described later. And after execution of this step S9, CPU112 once complete | finishes the said vibration component correction task.

  On the other hand, when the motor 40 is operating in step S7, the CPU 112 proceeds to step S11. In step S11, a counter-motor correction preparation process for preparing a counter-motor correction signal Wa [pa] corresponding to the current situation is performed. This step S11 will be described in detail later with reference to FIG.

  After executing step S11, the CPU 112 proceeds to step S13. In step S13, a counter-drive pulley correction preparation process for preparing the counter-drive pulley correction signal Wb [pb] corresponding to the current situation is performed. This step S13 will also be described later with reference to FIG.

  Further, the CPU 112 proceeds to step S15. In step S15, a driven pulley correction preparation process for preparing a driven pulley correction signal Wc [pc] corresponding to the current situation is performed. This step S15 will also be described later with reference to FIG.

  Then, the CPU 17 proceeds to step S17 and substitutes the correction signals Wa [pa], Wb [pb] and Wc [pc] prepared in the above-described steps S11, S13 and S15 into the equation 2, that is, The weight measurement value Wo [i] is obtained by the vibration component removal circuit 800 shown in FIG. The weight measurement value Wo [i] represents an accurate weight Wo of the object to be weighed 18 from which the influence of each vibration component Wa [i], Wb [i], and Wc [i] is eliminated.

  Further, the CPU 112 proceeds to step S19, and creates the above-described sorting signal So based on the weight measurement value Wo [i]. Specifically, the weight measurement value Wo [i] is compared with a preset sorting reference value, and the sorting signal So representing the comparison result is created. Then, the CPU 112 proceeds to step S21, transmits this sorting signal So to the sorting device, and ends the vibration component correction task.

  In step S5 described above, the CPU 112 executes group selection processing as a subroutine shown in FIG.

  That is, the CPU 112 proceeds to step S51, and obtains a temporary weight measurement value Wo ″ [i] based on the above-described equation 5, that is, by the temporary weight measurement circuit 900 shown in FIG. 28. Then, the process proceeds to step S53. The provisional weight measurement value Wo ″ [i] is compared with the threshold value Wt described above. Here, for example, when the provisional weight measurement value Wo ″ [i] is smaller than the threshold value Wt (Wo ″ [i] <Wt), the CPU 112 proceeds to step S55. In step S55, the CPU 112 further determines whether or not the operating condition 1 is set, in other words, which of the two operating conditions 1 and 2 is set.

  In this step S55, for example, when the operating condition 1 is set, the CPU 112 proceeds to step S57 and selects the group G01. Then, with the execution of step S57, the group selection process ends. On the other hand, when the operating condition 2 is set, the CPU 112 proceeds from step S55 to step S59. In step S59, a group G02 is selected, and the group selection process ends.

  In step S53 described above, when the temporary weight measurement value Wo ″ [i] is equal to or larger than the threshold value Wt (Wo ″ [i] ≧ Wt), the CPU 112 proceeds to step S61. In step S61, the CPU 112 further determines whether or not the operating condition 1 is set, in short, which of the two operating conditions 1 and 2 is set.

  In this step S61, for example, when the operating condition 1 is set, the CPU 112 proceeds to step S63 and selects the group G1. Then, with the execution of step S63, the group selection process is terminated. On the other hand, when the operating condition 2 is set, the CPU 112 proceeds from step S61 to step S65. In step S65, a group G2 is selected, and the group selection process ends.

  Next, in step S11 of the vibration component correction task shown in FIG. 29, the CPU 112 executes anti-motor correction preparation processing as a subroutine shown in FIG.

  That is, the CPU 112 proceeds to step S101, and determines whether or not the signal level of the one-rotation detection signal Sa described above for the motor 40 is H level. Here, for example, when the signal level of the one-rotation detection signal Sa is H level, the CPU 112 proceeds to step S103. In step S103, it is further determined whether or not the signal level of the one-rotation divided signal Da is H level. For example, when the signal level of the one-rotation divided signal Da is H level, the process proceeds to step S105.

  In step S105, the CPU 112 determines whether or not “0” is set in the above-described flag Fa. The flag Fa is an index indicating whether or not the rising of the one-rotation divided signal Da is detected. When the flag Fa is “0”, it indicates that the rising of the one-rotation divided signal Da is not detected. In other words, it represents that the state is waiting for the rising of the one-rotation divided signal Da to arrive. When the flag Fa is “1”, it indicates that the rising edge of the one-rotation divided signal Da is detected, and strictly speaking, it indicates that it is immediately after the rising edge of the one-rotation divided signal Da is detected. . Here, when the flag Fa is “0”, that is, when waiting for the rising of the one-rotation divided signal Da to arrive, the CPU 112 proceeds to step S107. In step S107, “1” is set in the flag Fa, and the process proceeds to step S109.

  In step S109, the CPU 112 sets (that is, resets) “0” to the count value pa of the counter for counting the section pa described above. In step S111, “0” is set to the count value Ca of the counter for counting the rising edges of the clock pulse CK. Then, the process proceeds to step S113, and the anti-motor correction signal Wa [pa] corresponding to the current situation is read. Specifically, for example, when the group G01 is currently selected, the anti-motor correction signal Wa01 [pa] is read from the register 600 shown in FIG. Separately from this, when the group G02 is selected, the anti-motor correction signal Wa02 [pa] is read from the register 602 shown in FIG. Further, when the group G1 is selected, the anti-motor correction signal Wa1 [pa] is read from the register 604 shown in FIG. When the group G2 is selected, the motor correction signal Wa2 [pa] is read from the register 606 shown in FIG.

  After executing step S113, the CPU 112 proceeds to step S115. In step S115, the count value pa of the counter for counting the interval pa is updated. That is, the count value pa is incremented by “1”. Then, the process proceeds to step S117.

  In step S103 described above, when the signal level of the one-rotation divided signal Da is not H level, that is, when the signal level of the one-rotation divided signal Da is L level, the CPU 112 skips steps S105 to S115. The process directly proceeds to step S117. Further, when “1” is set in the flag Fa in step S105, that is, immediately after the rising of the one-rotation divided signal Da is detected, the process directly proceeds to step S117.

  In step S117, the CPU 112 updates the count value Ca of the counter for counting the rising edges of the clock pulse CK, that is, increments the count value Ca by “1”. In step S119, the incremented count value Xa is compared with a preset reference value Qa. The reference value Qa is a determination criterion for determining whether or not the H-level period Tda of the one-rotation divided signal Da has elapsed since the rising of the one-rotation divided signal Da has been detected. When this is converted into a period Tqa, it is set to be slightly longer than the H-level period Tda of the one-rotation divided signal Da as shown in FIG. In this step S119, for example, when the current count value Ca is equal to or greater than the reference value Qa (Ca ≧ Qa), the CPU 112 detects the rising of the one-rotation divided signal Da and detects the one-rotation divided signal Da. It is determined that the H level period Tda has elapsed, and the process proceeds to step S121. In step S121, the flag Fa is set to “0”, and the anti-motor correction preparation process ends. On the other hand, if the current count value Ca is less than the reference value Qa (Ca <Qa), the CPU 112 ends the anti-motor correction preparation process without proceeding from step S119 to step S121.

  Steps S119 and S121 are provided in this way because the rising edge of the one-rotation divided signal Da has arrived again due to the rising edge of the clock pulse CK that comes immediately after the rising edge of the one-rotation divided signal Da is detected. This is to prevent being detected as a thing, that is, being erroneously detected. That is, the detection of the rising of the one-rotation divided signal Da is not permitted for a certain period Tqa immediately after the rising of the one-rotation divided signal Da is truly detected. By providing the non-permission period Tqa, erroneous detection of the rising of the one-rotation divided signal Da is prevented.

  Further, in step S101 described above, when the signal level of the one-rotation detection signal Sa is not H level, that is, when the signal level of the one-rotation detection signal Sa is L level, the CPU 112 proceeds to step S123. In step S123, as in step S103 described above, it is determined whether or not the signal level of the one-rotation divided signal Da is H level.

  In step S123, for example, when the signal level of the one rotation division signal Da is H level, the CPU 112 proceeds to step S125. In step S125, as in step S105 described above, it is determined whether or not “0” is set in the flag Fa. If “0” is set in the flag Fa, the CPU 112 proceeds to step S127. In step S127, “1” is set in the flag Fa, and the process proceeds to step S111.

  On the other hand, when the signal level of the one-rotation divided signal Da is L level in step S123, the CPU 112 proceeds to step S117 described above. Further, when “1” is set in the flag Fa in step S125, the process directly proceeds to step S117.

  In step S13 of the vibration component correction task shown in FIG. 29, the CPU 112 executes a counter-drive side pulley correction preparation process as a subroutine shown in FIG. Note that each step S201 to step S227 of the pair driving side pulley correction preparation process shown in FIG. 32 corresponds to each step S101 to step S127 of the pair motor correction preparation process shown in FIG. That is, FIG. 32 shows that Sa, Da, Fa, pa, Ca, Wa [pa] (Wa01 [pa], Wa02 [pa], Wa1 [pa], Wa2 [pa]) and Qa in FIG. Sb, Db, Fb, pb, Cb, Wb [pb] (Wb01 [pb], Wb02 [pb], Wb1 [pb], Wb2 [pb]) and Qb (see FIG. 14). Therefore, a detailed description of FIG. 32 is omitted.

  In step S15 of the vibration component correction task shown in FIG. 29, the CPU 112 executes a driven pulley correction preparation process as a subroutine shown in FIG. 33 correspond to the steps S101 to S127 of the anti-motor correction preparation process shown in FIG. 31, respectively. That is, FIG. 33 shows that Sa, Da, Fa, pa, Ca, Wa [pa] (Wa01 [pa], Wa02 [pa], Wa1 [pa], Wa2 [pa]) and Qa in FIG. Sc, Dc, Fc, pc, Cc, Wc [pc] (Wc01 [pc], Wc02 [pc], Wc1 [pc], Wc2 [pc]) and Qc (see FIG. 20). Therefore, detailed description of FIG. 33 is also omitted.

  As described above, according to the present embodiment, according to which of the operating conditions 1 and 2 is set and the weight Wo of the object to be weighed 18 including the presence or absence of the object to be weighed 18 The vibration components Wa [i], Wb [i], and Wc [i] are canceled and corrected by appropriate correction signals Wa [pa], Wb [pb], and Wc [pc]. Therefore, accurate error correction can always be realized as compared with the above-described prior art in which the vibration component is canceled and corrected by one type of correction signal.

  Further, according to the present embodiment, the vibration components Wa [i], Wb [i], and Wc [i] are mutually converted by the individual correction signals Wa [pa], Wb [pb], and Wc [pc]. It is corrected independently. Accordingly, the vibration components Wa [i], Wb [i], and Wc [i] are generated according to the rotational state of the rotating body of the motor 40 and the pulleys 26 and 28 that are the generation sources of the vibration components Wa [i], Wb [i], and Wc [i]. Even if the modes of Wb [i] and Wc [i], in particular, the phases θa, θb and θc and the periods Ta, Tb and Tc change, the vibration components Wa [i] and Wb follow the changes. [I] and Wc [i] can be accurately corrected. On the other hand, in the prior art, the correction component generated based only on the vibration component caused by one rotating body called the motor is to collectively correct the vibration component caused by the rotating body other than the motor. Therefore, it lacks accuracy. Also from this fact, according to the present embodiment, it is possible to realize an accurate error correction as compared with the prior art.

  In addition, although this embodiment demonstrated the case where this invention was applied to the weighing conveyor 12 for the weight sorter 10, it does not restrict to this. For example, the weighing conveyor 12 is not limited to a belt type, but may be a roller type or a chain type. Moreover, each pulley 26 and 28 itself may incorporate a motor. That is, the present invention functions effectively as long as the weighing device has a configuration in which the rotating body such as the motor 40 and the pulleys 26 and 28 is supported by the load detecting means such as the load cell 30. Furthermore, a certain amount of the objects to be weighed is discharged from a conveyor scale that calculates the weight (transported amount) of the rose-shaped objects to be continuously transported by the belt conveyor, or from a storage tank that contains subdividable objects to be weighed. In other weighing devices such as the loss-in-weight type quantitative supply device, the rotating body such as a motor is supported by the load detection means, but the present invention can naturally be applied to these.

  Further, the load cell 30 (strain body) has been exemplified by the Robertal type, but other types such as a column type or a ring type may be employed. And load detection means other than the load cell 30, for example, electromagnetic balance type or electrostatic capacity type load detection means may be employed.

  Further, as the optical sensors 204 and 206 shown in FIG. 6, a reflection type is given as an example, but a transmissive type photo interrupter may be adopted. In place of these optical sensors 204 and 206, other sensors such as a magnetic sensor and a color sensor may be employed. However, it is needless to say that in this case, it is necessary to appropriately determine the mode (respective through holes 208, 208,..., Notches 210) of the rotating disk 202 according to the type of the sensor.

  In an extreme case, only the one rotation detection signals Sa, Sb, and Sc are captured for the motor 40 and each of the rotating bodies 26 and 28, and the period Ta of the one rotation detection signals Sa, Sb, and Sc. The rotation angle of each rotating body may be detected by dividing Tb and Tc by a short-cycle signal such as a clock pulse CK. That is, the one-rotation divided signals Da, Db, and Dc may be unnecessary.

  And in this embodiment, in order to detect the presence or absence of the to-be-measured object 18, the temporary weight measurement value Wo "[i] was calculated | required based on the above-mentioned Formula 5, in other words, the temporary weight measurement shown in FIG. Although the circuit 900 is used, instead of this, a dedicated sensor only for detecting the presence or absence of the object 18 to be measured, for example, an appropriate sensor such as an optical sensor may be provided.

  In addition, in the extreme, the presence / absence of the object 18 need not be detected. In this case, correction signals Wa [pa] (Wa1 [pa] and Wa2 [pa]) and Wb only when the weighing object 18 exists (is placed) for each of the operating conditions 1 and 2. [Pb] (Wb1 [pb] and Wb2 [pb]), Wc [pc] (Wc1 [pc] and Wc2 [pc]) are prepared, and any operation is performed regardless of the presence or absence of the object to be weighed 18. Based on only whether conditions 1 and 2 are set, appropriate correction signals Wa [pa], Wb [pb], and Wc [pc] are applied. That is, accurate error correction is performed only when the object to be weighed 18 exists, and accuracy may be unquestioned when the object to be weighed 18 does not exist.

  Further, which operating conditions 1 and 2 are set is usually determined from the operation content of the operation key 26, but is not limited to this. For example, the conveyor speed is measured and the actual measurement is performed. You may judge from a result. Further, the determination may be made from the above-described provisional weight measurement value Wo ″ [i].

  Of course, the present invention can be applied not only to the two operating conditions 1 and 2, but also when three or more operating conditions are assumed.

DESCRIPTION OF SYMBOLS 10 Weight sorter 12 Weighing conveyor 18 Object to be weighed 22 Conveyor main body 24 Conveyor belt 26 Drive side pulley 28 Driven side pulley 30 Load cell 40 Motor 112 CPU
114 Memory circuit

Claims (4)

In a weighing device in which a portion to be weighed is supported by a load detection unit together with a rotating body and obtains the weight of the item to be weighed based on a load detection signal obtained from the load detection unit.
The load detection signal includes a vibration component caused by the rotation of the rotating body,
The aspect of the vibration component varies depending on operating conditions including the rotational speed of the rotating body and the load applied to the load detecting means,
Storage means for preliminarily storing a plurality of types of correction signals for removing the vibration components in various modes under various driving conditions;
Reading means for reading out the correction signal corresponding to the actual operating condition from the storage means;
Vibration component removing means for removing the vibration component contained in the load detection signal by subtracting the correction signal read out by the reading means from the load detection signal;
A weighing apparatus comprising: A weighing object detecting means for detecting whether or not the weighing object is supplied to the supplied part;
The readout means reads out the correction signal based on the actual operating condition including the detection result by the measurement object detection means.
The weighing device according to claim 1. It further comprises setting means for manually setting at least a part of the actual operating conditions,
The reading means reads the correction signal based on the actual operating condition including the setting content by the setting means.
The weighing device according to claim 1 or 2. A plurality of the rotating bodies,
The storage means stores the plurality of types of correction signals for the plurality of rotating bodies,
The reading means reads the correction signal for each of the plurality of rotating bodies,
The vibration component removing unit subtracts all the correction signals read by the reading unit for each of the plurality of rotating bodies from the load detection signal.
The weighing device according to any one of claims 1 to 3.

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