JPH0550691B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electronic balance, and more particularly to an electronic balance having a built-in weight for span calibration.

<Conventional technology> Due to the temperature dependence and other characteristics of the parts used in high-precision electronic balances, it is necessary to calibrate them from time to time to maintain their accuracy. A coefficient is used to convert the output of the load detection unit into mass based on the output when the weight is loaded on the load detection unit and the known mass stored in the memory within the balance. It has become common to have a so-called span calibration function that updates the span coefficient.

In this type of electronic balance, it is necessary to write the true mass value of the above-mentioned built-in weight into the memory, and conventionally, one of the following two methods has been adopted as a method for this.

One is to precisely adjust the mass of the built-in weights to be incorporated into electronic balances so that they all match the predetermined nominal mass at the time of manufacture, and the memory of all electronic balances has the above nominal mass in common. This is a method of writing mass.

The other method is to separately measure the true mass of each built-in weight and determine its nominal mass without precisely adjusting the mass of each built-in weight, as already proposed in JP-A-57-113325. In this method, the mass difference (instrumental error) for the weight is determined, and the instrumental error of the built-in weight is written in the memory of the electronic balance.

<Problems to be Solved by the Invention> By the way, among the above-mentioned conventional methods, in the former method, especially in high-resolution electronic balances, it is necessary to adjust the mass of the built-in weight on the order of mg or less. There is a problem in that it impairs productivity in the manufacturing and mass adjustment operations and becomes a major factor in increasing the cost of electronic balances.

In addition, with the latter method, it is easy to manufacture built-in weights, but it is necessary to attach all built-in weights to another balance in advance. Since it is necessary to write the instrumental error data of the weights without any errors, it is necessary to manage the large number of weights attached to the instrument and write the instrumental error data individually to the memory of each electronic balance to be installed. However, even this method has not been able to substantially eliminate the cost increase of electronic balances.

The present invention has been made in view of these circumstances, and it does not require the use of built-in weights whose mass has been precisely adjusted, but instead measures the mass of each weight individually in advance using a separate balance. The purpose of the present invention is to provide an electronic balance that can obtain high calibration accuracy without the need for incorporating the data into the memory of each partner electronic balance.

<Means for Solving the Problems> The configuration for achieving the above object will be explained with reference to the basic conceptual diagram shown in FIG. A load detection section 1 that outputs a signal, a memory 4 that stores a plurality of calculation modes, and a mode selection means 5 that selects an arbitrary mode from among the plurality of calculation modes.
, an arithmetic processing means 3 for arithmetic processing the output of the load detection section 1 according to the arithmetic mode selected by the mode selection means 5, and a built-in weight 2 for span calibration having an arbitrary error with respect to the nominal mass; It is characterized by having an addition/subtraction mechanism 6 and having a plurality of calculation modes stored in the memory 4 as the following three modes A, B, and C.

Mode A: From the output of the load detection unit 1 when an external reference weight with a predetermined nominal mass is loaded and when the built-in weight 2 is loaded, the true mass value of the built-in weight 2 or the difference between the built-in weight 2 and the above nominal mass or A mode that calculates and stores the ratio.

Mode B: A mode in which the output of the load detection section 1 is converted into mass using the stored span coefficient, and a measured value is determined and displayed.

Mode C: Calculate the span coefficient using the output of the load detection section 1 when the built-in weight 2 is loaded, the above nominal mass value, and the true mass value of the built-in weight 2 found in mode A or the above difference or ratio. This mode updates the span coefficient used in mode B.

<Function> When manufacturing a balance, mode A is selected with the built-in weight 2 having an arbitrary mass difference from the nominal mass and whose true mass unknown. In this mode A, when an external reference weight with a known mass having a nominal mass is loaded, the load detection unit
For example, the span coefficient of the balance can be determined from the output of the balance and its known mass. By using the span coefficient, etc., the true value of the built-in weight 2 can be determined by the function of the balance itself. It becomes possible to determine the mass or the difference or ratio to the nominal mass and write this value into the memory of the balance.

In other words, if you use the built-in weight 2 that has not been mass-adjusted, and without measuring each of its masses in advance using a separate balance, after installing the built-in weight 2 with an unknown mass, the weighing function of the balance itself is used to measure and store the mass data of the built-in weight 2.

When using the balance, select Mode B for normal measurements and Mode C for span calibration.

In mode A, the true mass value of the built-in weight 2 or the difference or ratio with respect to the nominal mass is determined, so select mode C to update the span coefficient as in conventional electronic balances of this type, and then select mode C to update the span coefficient.
is selected to calculate and display the mass of the sample to be measured from the output of the load detection section 1 and the span coefficient when the sample is loaded.

<Example> FIG. 2 is a configuration diagram of an embodiment of the present invention.

The load detection unit 11 generates an electric signal corresponding to the load when the built-in weight 13 is loaded by an external load on the weighing pan 11a or by a weight adjustment mechanism 12 consisting of a cam 12a, a lever 12b, etc. - It is supplied to the control unit 15 via the D converter 14.

The control unit 15 is composed of a microcomputer, and includes a CPU 15a that executes various calculations and programs and controls each peripheral device, a memory 15b that includes an area for storing programs and various calculation results described later, and external peripheral devices. An interface circuit 1 for connecting the control unit 15 and the control unit 15
5c etc. Connected to the control unit 15 are an operation key group 16 including a numeric keypad and a selection key for selecting three modes (to be described later), and a display 17 that displays weighing values based on commands from the control unit 15. There is.

Next, the operation of the embodiment of the present invention will be described.

FIG. 3 is a flowchart showing the entire data processing program written in the memory 15b of the embodiment of the present invention. The program is composed of three mode execution routines A, B, and C, and the routine corresponding to the mode selected by operating the operation key group 16 is executed. That is, when mode A is selected, the span coefficient K and built-in weight 13
The instrumental difference calculation routine that calculates the instrumental difference of is mode B.
When mode C is selected, the measurement routine calculates the mass on the weighing pan 11a using the stored span coefficient K and displays it as a measured value, and when mode C is selected, the built-in weight 13 is loaded and a new span is calculated. coefficient
A span calibration routine is executed to determine K' and update the previously stored span coefficient K to that value.

FIG. 4 is a flowchart showing the instrumental error calculation routine. This routine is a routine selected when calibrating the balance during upgrades or when calibrating using a standard weight that the user has on hand.

In this routine, first, the zero point is checked with no load on the weighing pan 11a (ST1
1) If there is a deviation, the calibration operation will not begin and a warning will be displayed to notify that fact (ST12, ST13). If the zero point is normal, the output X ₀ of the load detection section 11 at the time of no load is stored, and the external reference weight is loaded onto the weighing pan 11a (ST14). This reference weight must be a weight to which the instrumental error e is accurately set to the reading limit of this electronic balance with respect to the nominal mass _Wr .

When such an external reference weight is placed (ST1
5) Checks for overload, and if overload occurs for some reason, cancels calibration and displays a warning (ST16, ST17,
ST18). If the external reference weight has an instrumental error e, its value is input using the numeric keys of the operation key group 16 (ST19).

When the external reference weight is placed on the weighing pan 11a, if there is no overload, the output _X1 of the load detection section 11 in that state is stored (ST20),
Based on the difference X ₂ between that X ₁ and the output X ₀ under no load, the nominal mass W _r of this external reference weight, and the instrumental error e,
The span coefficient K is calculated as follows: K=(W _r +e)/X ₂ (1) (ST21). After that, when the external reference weight is removed from the weighing pan 11a, the zero point is checked again (ST22, ST23), and if it is off, the calibration is stopped and a warning is displayed (ST24, ST23).
ST25). If the zero point is not shifted, the output X ₀ ′ (≒X ₀ ) of the load detection section 11 at that time is memorized (ST26), the built-in weight 13 is waited for to be loaded, and the built-in weight 13 is transferred to the weight addition/removal mechanism 12. When the load is applied to the load, the output _X3 of the load detection section 11 at that time of load is stored (ST27, ST28). Then, from the difference X ₄ between X ₃ and the output X ₀ ' with no load, the span coefficient K calculated in ST21, and the output difference X ₂ with the external reference weight loaded and the output X 0 ' with no load, the built-in weight 1
Mass difference (instrumental error) ΔW with respect to the nominal mass W _r of 3
is calculated by ΔW=K·(X ₄ −X ₂ ) (2) and stored in the memory 15b (ST29), and the instrumental error calculation routine is ended.

Here, the instrumental error ΔW is calculated from equations (1) and (2) as follows: ΔW = (W _r +e)/X ₂ (X ₂ − X ₄ ) = X ₄ /X ₂ (W _r +e) − (W _r +e). On the other hand, if the true mass value of the built-in weight 13 is A, then A=X ₄ /X ₂ (W _r +e) (3), and A≡(W _r +e)−ΔW.

Furthermore, if the ratio between the nominal mass W _r and the true mass A of the built-in weight 13 is R, then A=R·W _r =X ₄ /X ₂ ·W _r +e/W _r ·W _r .

In _other words, _{R =} The ratio R between _r and the true mass value A of the built-in weight 13 can be easily derived from a well-known formula, and instead of the instrumental error ΔW determined by formula (2) above, ( Calculate and store the true mass value A of the built-in weight 13 using formula (3), and calculate and store the ratio R of the true mass value A of the built-in weight 13 to the nominal mass W _r from formula (4). You can get exactly the same result by programming

FIG. 5 is a flowchart showing the measurement routine. This routine is a routine that is used during normal measurements.

In this routine, a warning is displayed if the zero point is deviated, and if it is correct, a measurement operation is executed (ST30, ST31, ST32). Then, when the object to be measured is placed on the weighing plate 11a (ST3
3) The output X _w of the load detection unit 11 due to the load is collected (ST34), and the value is converted into a mass value W by the span coefficient K stored in the memory 15b, W=K・X _w ...( 5) is converted (ST35), and if the tare weight _Wt is stored, that value is subtracted and tare weight subtraction processing is performed to determine the weighing value _W0 (ST36),
It is displayed on the display 17 (ST37).

FIG. 6 is a flowchart showing the span calibration routine. This routine is a routine selected at the time of so-called span calibration, in which the span coefficient k is updated using the built-in weight 13. That is, first, the zero point under no load is checked, and if it deviates, a warning is displayed, and only if it does not deviate, a calibration operation begins (ST38, ST39, ST40). When the calibration operation starts, the output X ₀ of the load detection section 11 under no load and the output X ₃ of the built-in weight 13 under load are memorized (ST41, ST42, ST43), and the difference between X ₃ and X ₀ is stored.
Using X ₄ , the nominal mass W _r , and the instrumental error ΔW of the built-in weight 13 determined by the instrumental error calculation routine, the span coefficient K' is calculated as follows: K' = (W _r + ΔW)/X ₄ ...(6) Therefore, it is calculated (ST44), and the span coefficient K stored up to that point is updated to the value K' {ST45), and in the subsequent measurement routine, the mass is calculated using the updated span coefficient K. .

Here, if the true mass value A of the built-in weight 13 is stored in place of the instrumental error ΔW in ST29, and if the ratio R is stored, the calculation in ST44 will be as follows: K'=M/X ₄ …(7) and K′=R·W _r /X ₄ …(8).

In the above embodiment, in the instrumental error calculation routine, before calculating the instrumental error ΔW of the built-in weight 13, the span coefficient K is calculated using the external reference weight, and the span coefficient K is calculated using the equation (2) using that value. Although we have described the case of finding the difference ΔW, it is also possible to directly find the instrumental difference ΔW using equation (2)′ below without using the span coefficient.

ΔW=(W _r +e)・(X ₄ /X ₂ −1) …(2)′ In this case, there is no need to calculate the span coefficient K in the instrumental error calculation routine, and ST21 and ST2 in
9, ST2 shown in FIG. 7a and b, respectively.
1' and ST29' may be inserted. Also,
It goes without saying that under the condition that the external reference weight is one whose instrumental error with respect to the nominal mass is within the reading limit, the numeric keypad for inputting the instrumental error among the operation keys is unnecessary.

<Effects of the Invention> As explained above, according to the present invention, by simply preparing only one external reference weight with a predetermined nominal mass and a known mass, when the external reference weight is loaded, , has a calculation mode that calculates and stores the true mass value of the built-in weight or the difference or ratio to the nominal mass from the output of the load detection section when the built-in weight is loaded. Sometimes, it is not necessary to accurately adjust the mass to a predetermined mass as a built-in weight to be built into a balance, and even if such a built-in weight is used, it is necessary to use another balance to accurately adjust the weight. In addition to measuring, the measured instrumental error is
There is no need to individually write to the memory of the electronic balance to be installed; after installing a weight of unknown mass, simply select the instrumental error calculation mode using the built-in electronic balance's weighing function. Since it is possible to automatically measure the true mass value or instrumental error of the built-in weight and write it into memory, the manufacturing cost of built-in weights can be reduced, and moreover, it is possible to reduce the manufacturing cost of built-in weights. This eliminates the need for the effort required to manage built-in weights and write data individually to the memory, which is required when measuring each instrumental error and writing the instrumental error data one by one to the memory of the electronic balance to be installed. It has become possible to significantly reduce the cost of built-in electronic balances.

[Brief explanation of drawings]

Figure 1 is a basic conceptual diagram showing the configuration of the present invention;
The figure is a block diagram of an embodiment of the present invention, and FIG. 3 is a flowchart showing the entire data processing program.
4, 5, and 6 are flowcharts showing details of each routine, and FIG. 7 is a main part of a flowchart of an instrumental difference calculation routine according to another embodiment of the present invention. DESCRIPTION OF SYMBOLS 11... Load detection part, 11a... Weighing plate, 12... Weight addition/removal mechanism, 13... Built-in weight, 15... Control part, 15
a...CPU, 15b...memory, 16...operation key group,
17...Display device.

Claims (1)

[Claims] 1. A load detection section that outputs an electrical signal corresponding to the applied load, a memory that stores a plurality of calculation modes, and a mode selection means that selects any one of the plurality of calculation modes. , a calculation processing means for calculating the output of the load detection section according to the calculation mode selected by the mode selection means, a built-in weight for span calibration having an arbitrary error with respect to the nominal mass, and a mechanism for adding and subtracting the weight. An electronic balance characterized in that the plurality of calculation modes are the following three modes A, B, and C. Mode A: The true mass value of the built-in weight or the difference or ratio of the built-in weight to the nominal mass is calculated from the output of the load detection section when an external reference weight of a predetermined nominal mass is loaded and when the built-in weight is loaded. Mode to calculate and memorize. Mode B: A mode in which the output of the load detection section is converted into mass using the stored span coefficient, and a measured value is determined and displayed. Mode C: Calculate the span coefficient using the output of the load detection section when the built-in weight is loaded, the nominal mass value, and the true mass value of the built-in weight determined in mode A, or the difference or ratio above. A mode in which the span coefficient used in mode B is updated. 2. When executing the above mode A, calculate the span coefficient of the balance from the output of the load detection section and the nominal mass when the external reference weight is loaded,
The electronic balance according to claim 1, wherein the electronic balance is configured to use the value to calculate the true mass value of the built-in weight or the difference or ratio. 3. When the external reference weight in the mode A has an instrumental error with respect to the nominal mass, the difference between the mass of the external reference weight and the nominal mass can be corrected by inputting the instrumental error, and the difference between the mass of the external reference weight and the nominal mass can be corrected. 3. The electronic balance according to claim 1, wherein the electronic balance is configured to calculate the true mass value or the difference or ratio.