JPH07113575B2 - Electronic counting scale - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electronic counting scale that calculates and displays the number of samples by dividing the weight of an unknown number of samples by the unit weight of the sample to be measured. .

<Prior Art> In an electronic counting scale, generally, the estimated value of the unit weight (weight per piece) of a sample has a great influence on the accuracy of the counting result. Therefore, in the conventional electronic counting scale, various ideas have been made for this unit weight estimation method, but basically, it can be classified into the following two methods.

One is a method in which the number of samples such as 10, 40, and 100 is limited in advance, and the load value when the sample is placed on a plate is divided by the known number.

The other one is to first place a small number of known samples such as 5 on the plate and calculate the unit weight in the same manner, then add the samples as appropriate, and calculate each time before adding. Estimate the total number on the plate by dividing the additional weight by the unit weight to find the additional number and adding them sequentially, divide the total weight on the plate by the estimated number,
This is a method of updating the unit weight.

<Problems to be Solved by the Invention> According to the former conventional method, when the number of samplings for unit weight estimation becomes large, it is troublesome to count the number,
Further, there is a defect that counting errors may occur.

The latter method has a problem that there is no guarantee that all the estimations for each addition of the sample are correct, and eventually that the finally obtained estimated value of the unit weight is also correct.

Here, in estimating the unit weight, it is needless to say that a quantitative and clear handling cannot be performed unless the coefficient of variation of the weight of the sample to be counted is used. An algorithm that can guarantee the unit weight estimation based on the latter method has already been proposed by a method using the degree of variation in sample weight (Japanese Patent Laid-Open No. 60-31023).

The present invention further improves on this proposal and can give a quantitatively clear guarantee based on the stochastic treatment of counting errors, and is easy and practical without any complexity. The purpose of the present invention is to provide an electronic counting scale capable of obtaining an accurate unit weight estimation value.

<Means for Solving Problems> The first aspect of the present invention is as shown in FIG.
From the load detection unit a that detects the load placed on the plate, the unit weight memory b that stores the unit weight μ of the sample to be counted, the detection value W by the load detection unit a, and the content μ of the unit weight memory b. , An additional number calculating means c for calculating the number of samples added on the plate
And a total number memory d for additionally storing the calculation result k by the additional number calculating means c, and a content T of the total number memory d.
In a counting balance equipped with a unit weight calculating means e for calculating the unit weight μ of the sample from the detection value W detected by the load detection unit a and updating the content μ of the unit weight memory b, information relating to the coefficient of variation of the sample is set. a variation coefficient setting means f for, using the probability setting unit u for setting a probability P _0, the setting contents CV and P ₀ the variation coefficient setting means f and probability setting unit u, further the content T of the total number memory d , The allowable additional number calculating means g for calculating the maximum allowable number K capable of calculating the next additional number with the probability P ₀ or more without counting error, and the calculated allowable number K and the additional number calculating means c. The comparison means h for comparing the additional number k is provided, and only when the calculated additional number k is equal to or larger than the allowable number K based on the comparison result, the additional number k is added.
Is additionally stored in the total number memory d, and the unit weight calculating means e calculates and updates the unit weight μ.

A second aspect of the present invention is a counting balance equipped with the same load detection unit a, unit weight memory b, additional number calculating unit c, total number memory d, and unit weight calculating unit e as described above, and similarly changes in the sample. A coefficient of variation setting means f for setting information relating to the coefficient and a probability setting means u for setting the probability P ₀ are provided, and a preset initial number K ₀ on the plate and the following depending on the additional number N of samples, each time the maximum that can calculate a counting error without adding the number k _i at preset the probability P ₀ or more at the time of sample additional allowable number k _i (i = 1, 2, N) is calculated and stored, and the additional number k _i calculated by the additional number calculation unit c at each addition and the corresponding allowable number K _i in the allowable additional number calculation storage unit q. Comparing means r for comparing with Comprising a notification means s the result of the comparison, the allowable additional number calculation storage unit q is both eyes before sample addition of one less, variation coefficient setting means f and probability setting unit each setting condition CV and P ₀ of u, and Is characterized by being configured to sequentially calculate each allowable number K _i from K ₁ .

<Operation> In general, the weight w when n samples are taken out from the population M (μ, σ ² ) having a normal distribution of the average weight μ and the standard deviation σ is Becomes Where ξ ₁ is a random variable and its density function is Is.

On the other hand, when the unit weight of the sample is estimated from the weight w, from equation (1), Becomes

Next, if k samples are taken out and their weight is W, Becomes Here, ξ ₂ is a random variable independent of ξ ₁ .

Estimating the number using Becomes Therefore, the coefficient error ξ at this time is Becomes Since ξ is expressed as a linear combination of ξ ₁ and ξ ₂ ,
From the known theorem, Becomes That is, ξ is a normal random variable, the average value of ξ is 0, and the standard deviation of ξ is Is.

Therefore, when the number is estimated as an integer by rounding to four, the probability P that is correctly obtained is Becomes here, And put It can be expressed as.

From the above, a probability value P ₀ that is sufficiently close to 1 is set in advance, β is obtained from the equation (13) so that P ≧ P _0, and n If is known, it is possible to calculate the maximum allowable number K that can accurately (without counting error) be obtained with the probability P ₀ or more from the expression (12).

In the first invention, the permissible additional number calculation means g is configured so that the content T of the total number memory d (corresponding to n in the equation (12)), the setting content CV (= σ / μ) of the variation coefficient setting means f, and the probability setting. The above-mentioned K is calculated from the setting content P ₀ of the means u, and the comparison means h monitors that the operator has added K or less, so that a correct count can be made regarding the number of additions with probability P ₀ or more. Can be guaranteed.

In the second invention, when the initial number K ₀ to be placed on the plate is determined, the allowable number K ₁ at the time of the first addition can be calculated by setting n in the equation (12) to K _0. an additional number k ₁ times th K ₁
Assuming that it is equal to, the second additional permissible number K ₂ is similarly set by setting n in equation (12) as K ₀ + K _1, and more generally, the i-th permissible number K _i Is n in equation (12) Therefore, K ₁ , K ₂ , ... K _N is calculated and stored in advance without using the contents of the total number memory d. At this time, by comparing the K _i and the corresponding K _i by the comparison unit r and notifying the result by the notification unit s, it is possible to determine whether the additional number k _i satisfies the above-mentioned premise to the operator. Inform.

<Examples> Examples of the present invention will be described below with reference to the drawings.

FIG. 3 is a block diagram showing the configuration of the embodiment of the present invention. The load detection unit 1 is a load sensor engaging with the dish 1a and A-D.
It has a built-in converter etc. and can output digital data corresponding to the load on the plate 1a.

The data from the load detector 1 is CPU21, ROM22 and RAM2.
It is incorporated into the microcomputer 2 equipped with 3 etc. moment by moment. The microcomputer 2 is provided with a keyboard 3 mainly including a numeric keypad for inputting the coefficient of variation CV and the like.
Further, a display 4 for digitally displaying the number of samples, and a warning lamp 5 that lights up when an additional number k described later exceeds an allowable number K are connected.

In RAM23, in addition to the work area, the calculated unit weight μ
Area is set as a unit weight memory for storing, a total number memory for additionally storing the calculated value of the additional number, and the like.

FIG. 4 is a flow chart showing the contents of the unit weight estimation routine of the program written in the ROM 22, and the operation will be described below with reference to this figure.

Prior to the measurement, the coefficient of variation CV of the individual weight of the sample to be measured is entered from the keyboard 3 (ST1). This coefficient of variation CV is obtained by extracting an appropriate m number of samples, and using the standard deviation σ and the average weight of the individual weights w _i , It can be calculated by and the result is keyboard 3
You can enter from.

Next, K ₀ pre-set samples, for example 5,
Place only on dish 1a (ST2). From the load data at this time, the sample weight W on the dish 1a is determined by a known method and stored in the RAM 23 (ST3). Then this weight W
Is divided by K ₀ to calculate the first piece weight μ (ST
4) At the same time as being stored in the unit weight memory in the RAM 23, K ₀ is stored in the total number memory (ST5). The contents of the total number memory are displayed on the display 4.

Then, using the content T of the total number memory and the coefficient of variation CV previously input, the maximum additional number that does not cause a counting error with a probability P ₀ or more sufficiently close to 1 set in advance,
That is, the allowable number K is calculated and stored in the RAM 23 (ST
6). Although calculation method of this K are as described above, in practice, equation (13) P is to previously obtain the β becomes P ₀ which is set in advance, on the basis from the β (12) where k Can be calculated, and K can be obtained by rounding down.

Next, when the operator adds a sample to the dish 1a (ST7), the total sample weight W on the dish 1a is determined and stored from the load data at that time, and the difference from the previously stored weight W _a , That is, the additional weight W _a is calculated (ST8). This additional weight W _a is divided by the content μ of the unit weight memory and rounded to calculate the additional number k (ST9). Then, this k is compared with the allowable number K obtained in ST6 (ST10), and when k exceeds K, the warning lamp 5 is turned on (ST11) to notify the operator of that fact. Based on this, the operator selects the appropriate number of samples based on the dish 1a.
When removed from the top (ST12), the process returns to ST8 and the additional number is recalculated.

If k is less than or equal to K, after k is added and stored in the total number memory (ST13), the total sample weight W on the dish 1a at that time is divided by the content T of the total number memory after addition to obtain a unit value. Calculate the weight μ and update the contents of the unit weight memory (ST14). Then, until the sampling for unit weight estimation is completed, the same routine is repeated by returning to ST6 and subsequent steps, calculating and storing the allowable number K at the time of the next addition.

As described above, the allowable additional number K, which is the maximum additional number that does not cause a counting error with the probability P ₀ or more, is calculated each time the sample is placed on the dish 1a, and only when the additional number k is K or less. Then, the unit weight μ is updated based on the added number k.

In the above embodiment, the probability P ₀ close to 1 is set, and the allowable number at the time of the next addition is calculated based on the probability P _0. Ensuring that the unit weight μ obtained after total sampling by addition is accurate under a certain probability P _P is the probability P ₁ , P ₂ ... P The product of _N , that is But, Is to be satisfied. Therefore, in order to finally guarantee the correctness of the unit weight μ with the probability of P _P or more, in the case where it is determined that the sampling is completed by adding the sample N times, the above-mentioned P ₀ is It is necessary to ask in advance by.

As for the probability P ₀ based on the equation (16), the probability P _P to be used for the final guarantee is set in advance, and the final number of additions N
It is also possible to configure the microcomputer 2 to automatically calculate by inputting with the keyboard 3 or the like.

In the above, the case where the allowable number when adding each sample is sequentially calculated during sampling using the number (content T of the total number memory) placed on the dish 1a up to the previous time has been described.
Next, an example in which the allowable number of each addition is calculated N times before sampling will be described.

FIG. 5 is a block diagram showing the configuration of the example, and FIG. 6 is a flow chart showing the contents of the unit weight estimation routine of the program written in the ROM 22.

The difference between the example of FIG. 5 and the example of FIG. 3 in terms of hardware is that instead of the warning light 5, the excess / deficiency number of the additional number k _i with respect to the allowable number K _i is digitally displayed. Since the excess / deficiency number indicator 6 is provided, the other common members are denoted by the same reference numerals as those in FIG. 3, and the description thereof will be omitted.
In the RAM 23, an area for storing the permissible number K _i is set in addition to the unit weight memory and the total number memory similar to the above-described example.

The operation will be described below with reference to FIG.

Prior to measurement, first enter the coefficient of variation CV of the sample (ST
twenty one). As a result, using the default initial placement number K _{0 and} this CV, the maximum addition number that does not cause a counting error at the time of the first addition with a probability P ₀ sufficiently close to 1 set in advance, that is, the allowable number K ₁ is calculated and stored (ST2
2). This K ₁ is derived from β that satisfies P ₀ in Eq. (13).
It can be calculated by setting n in the equation to K ₀ .

Next, according to the predetermined number of sampling times N, the allowable number at each addition from the second time to the Nth time
Let K _{i be the same} as K ₂ from n in equation (12). And store each (ST23, ST24, ST25, ST2
6). That is, the additional number k _i from the first time to the (N-1) th time
We assume that all are equal to the corresponding K _i .

After calculating the above K _i , place K ₀ samples on the dish 1a (ST
27), the sample weight W is determined and stored (ST28), and the first unit weight μ is calculated (ST29). The μ and K ₀ are stored in the unit weight memory and the total number memory, respectively (ST30).

In this state, addition of the sample is started, but each time the sample is added, the additional number _Ki is calculated from the additional weight Wa and the unit weight μ,
The difference Δ with respect to the corresponding allowable number K _i is calculated (ST31, S
T32, ST33, ST34, ST35). When k _i is less than K _i , the fact is displayed on the excess / deficiency number display 6 in the form of, for example, “AddΔ”, and when k _i exceeds K _i , a message indicating that is displayed. Sub |
△ | "is displayed (ST36, ST37, ST39). When the operator adds or removes the sample on the dish 1a based on the display (ST38, ST40), the process returns to ST33 and k _i Is recalculated.

When the additional number k _i matches the corresponding allowable number K _i , the k _i
Is additionally stored in the total number memory, and the unit weight μ is calculated by newly dividing the sample weight W on the dish 1a by the content T of the total number memory, and the content of the unit weight memory is updated (ST36. , ST41, ST42).

The above operation is performed for each addition of each sample, and the number of additions is N
Until reaching the number of times, each time k _i and K _i match, for example, “Next” is displayed on the excess / deficiency number display 6 to prompt the addition of the next sample, and the sampling is terminated when the number of times reaches N. (ST
43, ST44, S45).

Also in this example, the probability P ₀ can be configured to be automatically calculated by the microcomputer 2 based on the above-described equation (16).

Also, excess and deficiency of k _i for K _i are in addition to be displayed in number as in the above example, simply insufficient excess, provided a lamp indicating a match or the like may be configured to light up one of the appropriate .

Further, in the above-described example, the unit weight μ is not updated unless k _i matches K _i . However, when workability is emphasized, the following configuration may be adopted.

That is, after each allowable number K _i is determined, a predetermined number smaller than each K _i , for example, a number smaller by 5 ▲ K ^′ _i ▼ = K _i
-5 ( _{i = 1,2, ... N} ) is calculated in advance, and if the number k _{i of} additions satisfies ▲ K ^' _i ▼ ≦ k _i ≦ K _i (17), go to ST41 and below. And proceed. According to this method, logically Although not always satisfied, the guarantee is made based on the probability approximated to P _P , which is not a big problem in practical use.

In each of the above-described examples, the coefficient of variation CV of the sample is not an amount that can be estimated very strictly in practice, so M discrete coefficients CV ₁ , CV ₂ , ...
Set _M (0 <CV ₁ <CV ₂ … <CV _M ), compare the input coefficient of variation CV with these, and CV _i-1 <CV ≤ CV _i … (19) or 0 < When CV ≤ CV ₁ (20) or CV _M <CV (21), use CV _i or CV ₁ or CV _M as the coefficient of variation of this sample and use it in the calculation of equation (12). Good.
In this case, in the example shown in FIG. 6, Ko and N are constant.
Since the permissible number sequence {K _i } can be calculated if the CV is determined, the permissible number sequence {K _ij } is calculated and stored in advance for each CV _i , and (19), (20), Or (21)
The corresponding {K _ij } can be immediately adopted as the allowable number sequence depending on the result of { _{circle around (1)} }. The number of CV _i , the difference between them, etc. may be determined according to the capacity of the ROM.

Furthermore, generally Tankasanechi smaller ones as the variation coefficient of (sample average weight) is large, since there is a tendency that larger ones as variation coefficient of the unit weight is small, as described above CV _i
And the unit weight value for each CV _i is set, and the corresponding CV _i is determined by the calculated value of the first unit weight after placing the initial mounting number K ₀ on the dish 1a. The coefficient of variation of can also be used.

Furthermore, the coefficient of variation of the sample may be obtained by this electronic counting scale. Ie keyboard 3
It is configured so that the coefficient of variation measurement mode can be selected by some key operation of, and in this mode,
For example, the samples may be placed one by one on the plate 1a, the load data may be stored in the RAM 23 each time, and when the number of samples reaches m, the coefficient of variation CV may be obtained by using the equation (14) described above. .

As hardware, it goes without saying that a personal computer or the like may be connected to the built-in microcomputer 2 so that appropriate routines can be shared.

<Effects of the Invention> As described above, according to the present invention, the information regarding the coefficient of variation of the sample and the probability are set in advance, and the additional number can be calculated without causing a counting error based on the probability. Since the allowable number that can be calculated is calculated and the unit weight is configured not to be updated when the additional number exceeds the allowable number, a quantitative and clear guarantee is provided for the estimated unit weight. It is possible to obtain an electronic counting scale that can guarantee the counting result and can greatly improve the reliability. Further, even in the actual work, there is no complexity such as counting the sample, and the electronic counting scale is easy to handle and accurate.

[Brief description of drawings]

FIG. 1 is a basic schematic diagram showing the configuration of the first invention, FIG. 2 is a basic schematic diagram showing the configuration of the second invention, and FIG. 3 is a block diagram showing the configuration of an embodiment of the first invention. FIG. 4 is a flow chart showing the contents of the unit weight estimation routine of the program written in the ROM 22, FIG. 5 is a block diagram showing the configuration of the embodiment of the second invention, and FIG. 6 is written in the ROM 22. It is a flowchart which shows the content of the unit weight estimation routine of a program. 1 …… Load detection unit 1a …… Plate 2 …… Microcomputer 21 …… CPU 22 …… ROM 23 …… RAM 3 …… Keyboard 4 …… Display 5 …… Warning lamp 6 …… Overs and shorts indicator

Claims (4)

[Claims] 1. A load detector for detecting a load placed on a plate, and a unit weight memory for storing the unit weight of a sample to be counted.
From the value detected by the load detection unit and the content of the unit weight memory, an additional number calculation means for calculating the number of samples added on the plate, and a total number memory for additionally storing the calculation result by the additional number calculation means, In a counting scale equipped with a unit weight calculating means for calculating the unit weight of the sample from the contents of the total number memory and the value detected by the load detection unit, and the information relating to the coefficient of variation of the sample in the counting scale equipped with unit weight calculating means. a variation coefficient setting means for setting a probability setting means for setting a probability P _0, calculated using these settings and contents of the total number memory, the counting error without these additional number above probability P ₀ or more An allowable additional number calculating means for calculating the maximum allowable number and a comparing means for comparing the calculated allowable number with the additional number calculated by the additional number calculating means, and based on the comparison result. Only when the calculated additional number is less than or equal to the allowable number, the additional number is added and stored in the total number memory, and the unit weight is calculated / updated by the unit weight calculating means. An electronic counting scale characterized by. 2. The probability setting means sets a probability P ₀ to be set in accordance with a preset number P of samples added for unit weight calculation based on a separately set probability P _P.
The electronic counting scale according to claim 1, wherein the product of N pieces is configured to be automatically calculated and set so as not to be smaller than the probability P _P. 3. A load detector for detecting a load placed on a plate, and a unit weight memory for storing the unit weight of a sample to be counted.
From the value detected by the load detection unit and the content of the unit weight memory, an additional number calculation means for calculating the number of samples added on the plate, and a total number memory for additionally storing the calculation result by the additional number calculation means, In a counting scale equipped with a unit weight calculating means for updating the unit weight of the sample from the contents of the total number memory and the value detected by the load detection unit, the information relating to the coefficient of variation of the sample , A probability setting means for setting the probability P ₀ , and a preset initial number K ₀ on the plate
And the maximum allowable number K ₁ , K ₂ , ... K _N capable of calculating the additional number without counting error at the probability P ₀ at the time of adding each sample, according to the number N of additional samples after that. Allowable additional number calculation storage means for storing, comparing means for comparing the additional number calculated by the additional number calculation means at each addition with the corresponding allowable number in the additional number calculation storage means, and the comparison result A notification means, the allowable additional number calculation storage means, each at least before the first sample addition, each setting content of the variation coefficient setting means and probability setting means, and An electronic counting scale, characterized in that each of the allowable numbers K _i is sequentially calculated from K ₁ and stored by using. 4. Based on the comparison result by the comparison means,
The notifying means displays the excess / deficiency number of the calculation result k _i by the additional number calculating means at the time of adding each sample with respect to the corresponding allowable number K _{i, and the} allowable number K ₁ in the allowable additional number calculation storage means. , K ₂ , ... K _N , a number K ₁ ′, K ₂ ′, ... K _N ′, which is smaller than the permissible number K ₁ , K ₂ , ... K _N by a predetermined number, is calculated, and the comparison means is calculated. Is
The calculation result k _i by the above-mentioned additional number calculation means at the time of adding each sample is compared and determined whether K _i ′ ≦ k _i ≦ K _i is satisfied, and the additional number k _i is determined only when it is satisfied. The electronic counting scale according to claim 3, wherein the electronic counting scale is configured to add and store in the total number memory and to calculate and update the unit weight by the unit weight calculating means.