JPH0339619A - Combination scale with automatic zero-point adjusting device - Google Patents

Abstract

PURPOSE:To make a zero-point adjustment in a short time by subtracting a stored value other than a weight storage means corresponding to an article storage part in the group of an arithmetic means to which an article is discharged from the arithmetic means in the group and adding the subtraction value to the stored value of the zero-point storage means in the group. CONSTITUTION:A CPU 26 controls a driving circuit 36 which supplies a control signal to a gate driving circuit 20 so as to open and close the supply gates 14a and 14b of a supply tank 14 and discharge gates 6a and 6b of a weighing tank and also supplies a control signal to a conveyor driving circuit 34 so as to put a conveyor in operation. Further, a timer 30 supplies a signal indicating the timing of the supply of an article from the supply tank 14 to the corresponding weighing tank. Then the weight signal of a load cell 8 is digitized by an A/D converter 24 and its weight value Wm is stored. The zero-point weight of an m-th zero-point weight storage area is subtracted from said weight value Wm to calculate tare-subtracted weight Wx. Then the stored value of an m-th weighing tank is subtracted from the weight Wx and the subtraction value is added to the stored value in the zero-point weight storage area.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a combination weigher equipped with an automatic zero point adjustment device,
In particular, it relates to a combination weighing scale having a weighing tank or a plurality of article storage parts.

[Prior Art] Conventionally, a combination weigher in which a weighing tank includes a plurality of article storage sections,
It is publicly known from Japanese Patent Application Laid-Open No. 59-10815 and the like. In such a combination weigher, a plurality of weighing tanks are provided, and each of these weighing tanks is provided with two article storage sections. In each weighing tank, when an article is supplied to one of the two empty article storage sections, the output of one weighing means provided in that weighing tank is applied to the one article storage section. When an article is also supplied to the other article storage section, the stored value of the weight storage means corresponding to the one article storage section is subtracted from the output of the weighing means at that time. Then, the weight of the article in the other article storage tank is calculated, and this is stored in a weight storage means provided corresponding to the other article storage tank. Then, the stored values of each weight storage means are combined and calculated, a combination whose total value is equal to or close to the target weight is selected, and the articles are removed from the article storage tank containing the articles that constitute the selected combination. It is something to be discharged.

Even in a combination scale where the weighing tank is equipped with a plurality of article storage sections, the zero point of the weighing means fluctuates due to drift due to temperature changes and product residue adhering to the article storage sections, so the zero point adjustment is necessary. There is a need. Regarding this zero point adjustment device, for example, Japanese Patent Application Laid-Open No. 6:1-:10722, No. 63-1
No. 68515 and No. 63-168516. That is, when articles in two article storage sections of the weighing tank are discharged at the same time, the output of the weighing means at that time is stored in the zero point storage means, and thereafter, the stored value of the zero point storage means is subtracted from the output of the weighing means. It is something to do.

[Problems to be Solved by the Invention] However, in order to adjust the zero point with the above-mentioned zero point adjustment device, it is necessary for two article storage sections of the same measuring tank to discharge articles at the same time. However, the probability that an article will be ejected from two article accommodating sections of the same weighing tank at the same time is lower than the probability that an article will be ejected from either of the two article accommodating sections. Moreover, since zero point adjustment is not performed very often, for example, a command is given to perform zero point adjustment every certain period of time. The number of tanks that emit 2 is very small, so there is a high possibility that there will be measuring tanks in which the zero point adjustment is not performed for a considerable period of time even though the zero point adjustment command has been given many times. There was a problem. In addition, in order to make it easier for the articles in each article storage section to be uniformly selected, an attempt was made to supply articles to each article storage section at a weight that was approximately equal to the weight determined in consideration of the target weight, but when a certain weighing tank If one of the article storage sections stores an article that is considerably heavier than the weight specified above, the probability that the article in this article storage section will be included in a combination that is equal to or close to the total weight or target weight is very small. Become. In such a case, there is a problem in that zero point adjustment cannot be performed for this weighing tank unless this heavy item is removed manually.

The present invention was made in order to solve the above problems, and an object of the present invention is to provide a combination scale that can automatically adjust the zero point when an article is discharged from one of the article storage sections. shall be.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides at least two
A weighing tank including one weighing means, a calculation means for subtracting the zero point weight stored in the zero point storage means from the output of the weighing means, and a weighing tank having one weighing means, and a calculation means corresponding to each article storing section. A plurality of weight storage means are provided, and the weight of the article in the article storage section corresponding to each of these weight storage means is calculated and stored by subtracting the stored value of the other weight storage means from the output of the calculation means. With weight memory control means,
A target weight value whose total value is predetermined from among these combinations is obtained by various combinations of the stored values of each weight storage means of each group that is a target of one combination. In a combination weigher that selects a combination equal to or close to , and discharges the article from each article storage section that stores the articles constituting the selected combination, the output of the calculation means of the set to which the article storage section that discharged the article belongs. Zero point storage control means for subtracting the stored value of a weight storage means other than the weight storage means corresponding to the article storage section from which the set of articles was discharged from and adding the subtracted value to the stored value of the zero point storage means for that set. , be prepared.

In addition, instead of the above configuration, the zero point memory control means may be configured such that the weight storage means other than the weight storage means corresponding to the article storage section from which the article has been discharged is based on the output of the weighing means means of the group to which the article storage section from which the article has been discharged belongs. It is also possible to subtract the value stored in the weight storage means of the set and store the subtracted value in the zero point storage means of the set.

[Function] According to the present invention, as shown in FIG. 1, for example, if there are 82 article storage sections A and ignoring the influence of drift,
The weight W tar@ of the weighing tank is stored in the zero point storage means. Here, as shown in FIG. 5A, if an article is stored in the article storage section A and its weight is WA, then the weighing means is W L a r. produces an output of +WA, and the calculation means outputs W
produces an output of A. This is supplied to the weight storage control means, and the stored value of the storage means B, which is another weight storage means (currently, 0 since the article storage section B is empty), is subtracted from WA, and the subtracted value WA is Weight storage means A corresponding to A
Next, as shown in FIG. 2B, when an article of 1 weight WIS is supplied to the article storage section B, the output of the weighing means is W t a r e + W s + W B
The output of the calculation means is WA+W.0The weight storage control means subtracts the stored value WA of the other weight storage means A from WA+W6 to calculate WIS, and stores this in the weight storage means B. Make me remember.

In this way, the weights of the articles stored in the corresponding article accommodating portions are stored in the weight storage means of each set, and a combination calculation is performed. When an article is discharged from section A, residue adheres to article storage section A and its weight is Wc, then the output of the weighing means is Wtare+Wa+WC, and the output of the calculation means Ha, W.

+Wc, respectively, and the zero point storage control means subtracts the stored value WB of the weight storage means B corresponding to the article storage section B from which no article has been ejected from the output W, +Wc of the calculation means, and calculates the weight Wc of the residue. is calculated, and this is stored as the value W L a r in the zero point storage means. , and set the stored value of the zero point storage means to WL, , +Wc.6 Next, W is added to the article storage section A.
When o articles are stored, the output of the weighing means is Wt,
, +W, +Wc+WD, but W□,
, +Wc are stored, the output of the calculation means is W,
+WD, and the weight storage control means uses the output W6 of the calculation means.
The value W3 stored in the weight storage means B is subtracted from +WD, and this value is stored in the weight storage means A. Therefore, even if residue adheres to the article storage section, it is possible to eliminate weighing errors caused by fluctuations in the zero point. Further, the zero point memory control means controls the output W t a r of the weighing means.

+W, s When the stored value W of the weight storage means B is subtracted from +wc, the subtracted value becomes Wtara+Wc, which becomes a new zero point value. Therefore, this may be stored in the zero point storage means.Although the above explanation only deals with the residual liquid, the same applies when the output of the weighing means drifts due to temperature changes and the point 5 fluctuates. The zero point can be adjusted by

[Example] As shown in FIG. 2, this example has a measuring tank 2,
This is partitioned into two article storage sections 2a and 2b by a partition wall 4. These article storage sections 2a and 2b are provided with discharge gates 6a and 6b, respectively, so that articles can be individually discharged from the article storage sections 2a and 2b. Further, each of such weighing tanks 2 is provided with one load cell 8 as a weighing means, for example. These weighing tanks 2 are arranged in n units along the length direction of the support frame 10 in a negative row so that each load cell 8 is located inside the support frame 10. Further, below these weighing tanks 2, a conveyor 12 is provided along the arrangement direction of the weighing tanks la2 so as to carry out the articles discharged from these tanks.

A supply tank 14 is arranged above each measurement II@2. That is, a total of n supply tanks 14 are provided. These supply tanks 14 have a supply gate 14a for supplying articles to the article storage section 2a and a supply gate 14b for supplying articles to the article storage section 2b. Each supply tank 1 is attached to an upper plate 16 projecting upward from the upper part of the support frame 10 to above each supply tank 14.
This is done manually through each input port 18 drilled corresponding to the number 4.

Each gate of these pair of measuring tank 2 and supply tank 14.

That is, discharge gates 6a, 6b, supply gates 14a, 1
Gate drive circuits 20 for opening and closing the gates 4b are provided within the support frame 10 in correspondence with each pair.

fi 42 22 shown in the figure is a control unit which inputs weighing signals from each load cell 8 and controls each article storage section 2a based on these signals.
, 2b, selects a combination whose total weight is equal to or close to the target weight based on this calculated weight, and stores the items in the article storage section containing the items constituting the selected combination. It opens the discharge gate and supplies articles to the article storage sections 2a and 2b from which the articles have been discharged, and is configured as shown in FIG. 3, for example.

That is, this control section 22 has an A/D converter 24 that converts the weighing signal from each load cell 8 into a digital weight value, and this digital weight value is supplied to the CPU 26.

Although not shown in the figure, the weighing signal of each load cell 8 is first supplied to the multiplexer, and then sequentially supplied to the A/D converter 24.

The CPU 26 includes a FROM 28 that stores a program to be executed by the CPU 26, a timer 30 that notifies the CPU 26 each time an article is supplied to the weighing tank 2, and each time a zero point adjustment is performed.
A RAM 32 is provided which is used for temporarily storing data when the PU 26 performs calculations.

In addition, as shown in FIG.
a weight storage area M that stores the weight of the articles stored in b;
Mna to Mna and MIb to Mnb are provided. Furthermore, in the RAM 32, corresponding to each load cell 8,
Zero point weight storage areas 2□ to ZPn are provided. These zero point weight storage areas 2. To Z pn, the weight of the weighing tank 2 to which the corresponding load cell 8 is connected, the weight of the residue adhering to the article accommodating parts 2a and 2b, the output fluctuation due to the drift of the load cell 8, etc. are subtracted from the output of the load cell 8. The zero point weight for this is stored. Also, R.A.
M 32 is also provided with an article storage section for supplying articles and a counter area m used for scanning the load cell 8 for zero point adjustment.

The CPU 26 also supplies a control signal to the gate drive circuit 20 in order to open and close each supply gate 14a, 14b and discharge gate 6a, 6b, and supplies a control signal to the conveyor drive circuit 34 in order to operate the conveyor 12. It controls a drive circuit 36 that supplies .

The operation of the combination weigher constructed in this way will be explained based on the flowchart shown in FIG. Now, articles are stored in some of the article storage sections 2a and 2b of each weighing tank 2, and the weights of these articles are stored in the corresponding weight storage areas, and the weights of these articles are stored in the corresponding weight storage areas. Area 2□ to ZP
It is assumed that the zero point weight of the corresponding load cell 8 is stored in n.

In this state, first, it is determined whether a signal notifying that it is time to supply the article from the supply tank 14 to the article storage section of the corresponding measuring tank 2 is supplied from the timer 30 (step S2). If this answer is No, it is determined whether a signal notifying that the 1-combination scale is to be stopped is supplied from a keyboard (not shown) attached to the CPU 26 (step S4). ,
Return to step S2. That is, the loop of steps S2 and S4 is repeated.

While repeating this loop, when the supply timing is reached and the answer to step S2 becomes YES, the value of the counter area m for scanning each weighing tank 2 and load cell 8 is 1.
(Step S8).

Then, it is determined whether the article storage section 2a of the m-th weighing tank 2 is empty (step 510). This is, for example, the weight storage area M corresponding to the article storage section 2a of the m-th weighing tank 2.
This can be done by determining whether the value of □ is O. If the answer is YES, the article is supplied to the article storage section 2a (step S12).

That is, a control signal is supplied to the drive circuit 36 to open the supply gate 14a of the m-th supply tank 14. Next, m
The digital weight value W obtained by digitally converting the weight signal of the load cell 8 by the A/D converter 24 is stored (
step 514), followed by a digital weight value W
, by subtracting the zero point weight of the m-th zero point weight storage area Z, from , to calculate the tare weight W (step 516).
Then, the weight storage section M, which also corresponds to the article storage section 2b of the m-th weighing tank 2, determines whether the article storage section 2b of the m-th weighing tank 2 is empty (step 318). value is 0
This can be done by determining whether This answer is YES
S, as shown in FIG. 1(a), the tare weight W8 represents the weight of the article stored in the article storage section 2a of the m-th measuring tank 2, so the weight storage section M , , (step 520).

If the answer to step S18 is No, that is, if the article is stored in the article storage section 2b side, the tare weight Wll of the article stored in the article storage sections 2a, 2b of the m-th measuring tank 2 is Since the total weight of W is memorized, the tare weight W
Goods storage from M! The weight of the article stored in the article storage section 2a is calculated by subtracting the value stored in the weight storage section Mfib that stores the weight of the article stored in the article storage section 2b.

(step 522), and following step S2G or S22, the value of the counter area m is incremented by 1 in order to scan the next measuring tank 2 (step 524), and it is determined whether scanning has been completed for all measuring tanks 2. In order to do this, it is determined whether the value of this counter area m is equal to a value 1 greater than the total number n of measuring tanks 2 (step 526). If the answer is No, the process returns to step S10.

On the other hand, if the answer to step S10 is No and the article is not stored in the article storage section 2a of the m-th measuring tank 2, m
It is determined whether an article is stored in the article storage section 2b of the th measuring tank 2 (step 528).

If the answer is NO, both steps 5lO1S28 are closed, so the article storage sections 2a and 2 of the m-th measuring tank 2
Since articles are stored in both containers b, step S24 is executed in order to scan the next weighing tank 2.

If the answer to step S2B is YES, the article is stored in the article accommodating section 2b of the m-th measuring tank 2, so the article is supplied to the article accommodating section 2b of the m-th measuring tank 2 (Step 330), Read the weight value W obtained by digitizing the weight signal of the m-th load cell 8 (step 532);
Then, the zero point weight in the msth zero point weight storage area zP is subtracted from the digital weight value W1 to calculate the tare weight W8 (step 534). Next, since step S10 is NO and step 528 is YES, articles are stored in both article storage sections 2a and 2b of the m-th measuring tank 2. Therefore, as shown in FIG. 1(b), since the tare weight W represents the total weight of the articles in the article accommodating sections 2a and 2b, the weight of the articles in the article accommodating section 2a is memorized from now on. The stored value of the weight storage area M□ is subtracted and stored in the 1 weight storage area M,b (Step 5
36), and steps S24 and S2B are executed to scan the primary weighing tank 2.

When the answer to step S26 becomes YES and the scanning of all the measurements 42 is completed, a combination calculation is performed (step S5
38), this combination calculation involves variously combining the stored values of each weight storage area in which one weight value is stored, and selecting from among these combinations the one whose total value is equal to or closest to the target weight value. , since this calculation method is well known, detailed explanation will be omitted.

Following this, a control signal is supplied to the drive circuit 36 such that the discharge gates 6a and 6b'elSN< of the article storage sections 2a and 2b containing the selected article are stored, and the weight of the selected article is also calculated. The stored value in the weight storage area is reset (step 340).

Next, it is determined whether a signal notifying that it is the zero point adjustment timing is being supplied from the timer 30 (step 542). If the answer is no, step S4 is executed, and if this answer is also no, the process returns to step S2.

Therefore, the zero point adjustment is not performed every time an article is fed or discharged, but once every several times. If the answer to step S42 is YES, the value of the counter area m for scanning each weighing tank 2 is set to 1 (step 544), and the article storage section 2 of the m-th weighing tank 2 is
It is determined whether the article has been discharged from a (step S46
).

This can also be done by determining whether the value of the weight storage area Msa corresponding to the article storage section 2a of the m-th weighing tank 2 is O. If the answer is YES.

The digital weight value W, obtained by digitizing the weighing signal of the m-th load cell 8, is read (step 548), and the m-th zero point weight storage area ZP is read from the digital weight value W.
Calculate the tare weight W by subtracting the zero point weight of s (
Step 5SO), this tare weight W8 is shown in Figure 1 (C
) If a residue adheres to the article storage section 2a, the weight of this residual liquid is the sum of the weight of the article accommodated in the article storage section 2b. In order to calculate this residual weight and add it to the zero point weight, the stored value of the weight storage area ub that stores the weight of the article in the article storage section 2b of the m-th measuring tank 2 from the tare weight W is calculated. is subtracted, and the subtracted value is added to the stored value in the zero point weight storage area ZP+m (step 552). Note that even if the stored value in the m-th weight storage area Mmb is O, that is, the m-th weighing Even if the articles are simultaneously discharged from the article accommodating portion 2b of the tank 2, by performing step S52, it is possible to detect the outside of the residue and add this to the zero point weight. In addition, if the residue that has been attached until now is discharged at the same time as the item is discharged, the change in the zero point can be adjusted in the same way, just by having a negative sign of the value to which the zero point weight is added. can. Furthermore, even if there is no residue attached and the output of the load cell 8 is fluctuating due to temperature changes, the zero point can be corrected in the same way, and even if extra residue and output fluctuations of the load cell 8 occur simultaneously, Fluctuations in the zero point can be corrected.

Then, in order to adjust the zero point of the next load cell 8, the value of the counter area m is incremented by 1 (step 554), and in order to judge whether scanning has been completed for all the load cells 8, the value of the counter area m is incremented by 1 for all the load cells 8. (step 556), and the answer is No.

Return to step S46.

On the other hand, if the answer to step S46 is NO and the article has not been discharged from the article storage section 2a of the m-th weighing tank 2, it is determined whether the article has been discharged from the article storage section 2b of the m-th weighing tank 2. (Step SSa).

This determination can also be made by determining whether the stored value in the weight storage area Mob corresponding to the article storage section 2b of the 1m-th weighing tank 2 is 0. If the answer is NO, it means that the article has not been discharged from the article storage section 2b, and it is already known that the answer to step S46 is No and that the article has not been discharged from the article storage section 2a. Since no articles have been discharged from any of the article storage sections 2a, 2b of the m-th weighing 41!2, and zero point adjustment cannot be performed, step S54 is executed in order to scan the next load cell 8.

If the answer to step S58 is YES, the digital weight value W obtained by digitizing the weighing signal of the m-th load cell 8 is read (step 560), and the m-th zero point weight storage area zo is read from the digital weight value W. Subtract the zero point weight to calculate tare weight W (step 562)
, and the tare weight W. A weight storage area M that stores the weight of the article in the article storage section 2a of the m-th measuring tank 2 from
Subtract the memorized value of □ and store the subtracted value in zero point weight storage area 2.
A (step 564), step S
60. The reason for executing S62 and S64 is that step S
48, S50, and S52, the explanation will be omitted. Then, in order to scan the next load cell 8, step S54 is executed. When the scanning of each load cell 8 is completed in this way, step S5
The answer to step 6 is YES, execute step S4, and perform the following steps.
Works similarly.

In the above embodiment, the article storage sections 2a and 2b were formed by partitioning the weighing tank 2 to which the load cell 8 was combined by the partition wall 4, but for example, if two weighing tanks were combined and one A weighing tank may be constructed by combining load cells. Further, in the above embodiment, the number of article storage sections is two, but the number can be further increased. Further, in the above embodiments, a supply tank is provided, but depending on the case, this may be unnecessary and the articles may be manually supplied directly to each article storage section of the measuring tank. In the above, the articles are fed manually, but the articles may be automatically fed to each supply tank using a conventionally known distributed feeder, linear feeder, or the like. In the above embodiment, the ff point adjustment was performed when the article was discharged and the timer 30 generated a signal indicating that it was time to adjust the zero point, but it could also be done every time the article is discharged. Furthermore, in the above embodiment, the zero point adjustment was performed by subtracting the weight of the articles in the remaining article storage sections of the same weighing tank from the tare weight W8, and adding the subtracted value to the zero point weight. However, the weights of the articles in the remaining article storage sections of the same weighing tank may be subtracted from the digital weight value W before taring, and the subtracted value may be stored in the zero-point weight storage area as the zero-point weight.

[Effects of the Invention] As described above, according to the present invention, when an article is discharged from any of the article accommodating sections of the weighing tank, the weighing signal of the weighing means at that time and the remaining article accommodating section are The weight at one point is adjusted based on the difference between the weight and the weight of the items stored in the storage area. Generally, the probability that articles will be ejected from the number of articles in any one of the weighing tanks or the container is higher than the probability that articles will be ejected simultaneously from a plurality of article storage sections of rB measuring tanks. Therefore, according to the present invention, there is a very high probability that zero point adjustment can be carried out for all weighing means provided in each weighing tank within a short period of time. Moreover, even though each article storage section of each weighing tank is supplied with an article having a weight approximately equal to the weight determined in consideration of the target weight, only one of the article storage sections of the weighing tanks is supplied with an article of a large weight. Even if the article is not discharged from one of the article storage sections, if the weight of the article in the remaining article storage section of the same weighing tank is approximately equal to the predetermined weight, the product will be removed from this remaining article storage section. The probability that the article will be ejected is very high, so zero point adjustment can be carried out even in such a case.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the principle of the present invention, Fig. 2 is a diagram showing the mechanism of an embodiment of the invention, Fig. 3 is a block diagram of the embodiment, and Fig. 4 is a RAM used in the embodiment. FIG. 5 is a flowchart of the same embodiment. 2... Measuring tank, 21.2b... Article storage section, 8
...Load cell (weighing means), 26...cpu
(Calculation means, weight memory control means, zero point memory control means)
. MIM to M. , Mlb to M, b... weight storage means, 2 to ZPn... zero point weight storage means.

Claims (2)

[Claims] (1) A weighing tank having at least two article storage sections and one weighing means, a calculation means for subtracting the zero point weight stored in the zero point storage means from the output of the weighing means, and each of the above articles. A plurality of weight storage means provided corresponding to each storage section, and the weight of the article in the article storage section corresponding to each of these weight storage means are calculated by subtracting the stored values of the other weight storage means from the output of the calculation means. A weight storage control means for calculating and storing the calculated values constitutes one set, and there are a plurality of such sets, and the stored values of the respective weight storage means of each set to be combined are variously combined. A combination scale that selects a combination whose total value is equal to or close to a predetermined target weight value from among the combinations and discharges the articles from each of the article storage sections that accommodate the articles constituting the selected combination, Subtracting the stored value of a weight storage means other than the weight storage means corresponding to the article storage section that discharged the article from the output of the calculation means of the group to which the article storage section that discharged the article belongs, and calculate the subtracted value. A combination weigher having an automatic zero point adjustment device, characterized in that it comprises zero point storage control means for adding the value stored in the zero point storage means of the set. (2) In the combination weigher having the automatic zero point adjustment device according to claim 1, the zero point memory control means, instead of the configuration according to claim 1, performs weighing of the group to which the article storage section from which the article has been discharged belongs. The storage value of a weight storage means other than the weight storage means corresponding to the article storage section that discharged the article of the group is subtracted from the output of the means, and the subtracted value is stored in the zero point storage means of the group. A combination weigher having an automatic zero point adjustment device, characterized in that: