JPS6013224A - Electronic balance - Google Patents

Abstract

PURPOSE:To obtain high calibrating accuracy without using a highly accurate weight as an enclosed weight, by performing operating process in accordance with a specified operating mode, which is selected by a mode selecting means. CONSTITUTION:Data processing programs are constituted, by 3 mode-executing routines A, B and C. The corresponding routine is executed by the operation of an operating key group 16. Namely, when the mode A is selected, an instrument- error computing routine, which computes a span coefficient K and the instrument error of an enclosed weight 13, is executed. When a mode B is selected, a measuring routine, which obtains the mass on a scale pan 11a by using the memorized span coefficient K and displays the measured value, is executed. When the mode C is selected, a span calibrating routine, which loads the enclosed weight 13, newly obtains a span coefficient K', and updates the memorized span coefficient K into said new coefficient K', is executed. Thus high calibrating accuracy can be obtained without using a highly accurate weight for the enclosed weight.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of industrial application The present invention relates to an electronic balance, and more particularly to an electronic balance with a built-in weight for span calibration. (b) Prior art High precision electronic balance Due to the temperature dependence and other characteristics of the parts used, calibration is required from time to time to maintain accuracy. Therefore, when a weight with a known mass is built in and the weight is loaded on the load detection section, It is common to have a so-called span calibration function that updates a coefficient (span coefficient) for converting the load detection section output into mass based on the output of the load detection section and its known mass.

In conventional electronic balances of this type, the built-in weight described above must be precisely adjusted to match the nominal mass, or
As already proposed in Japanese Patent Application Laid-Open No. 57-113325, the error in the mass of the built-in weight with respect to the nominal mass is measured in advance so that there may be some error in the mass of the built-in weight with respect to the nominal mass. (Instrument setting), the value was stored in the electronic balance. In the former method, productivity was lost in the production of built-in weights, which became a major factor in increasing the cost of electronic balances. In addition, with the latter method, it is easy to manufacture the built-in weight, but the error of the built-in weight must be measured in advance with another balance, which is time-consuming and requires a lot of effort. Management is difficult, and in the end, even this method has not been able to substantially eliminate the cost increase of electronic balances.

(c) Purpose The present invention has been made in view of the above, and uses a comparatively low-cost rough weighing steel instead of using a high-precision built-in weight, and does not measure its mass in advance with a separate balance. In other words, the purpose of the present invention is to provide an electronic balance that can obtain high calibration accuracy without having to mount an instrument.

(d) Structure The structure of the present invention will be explained based on the functional block diagram shown in FIG.

When an external load or built-in weight 2 is loaded, the load detection section 1 outputs an electric signal corresponding to the load and supplies it to the arithmetic processing means 3. The mass of the built-in weight 2 has an arbitrary error with respect to the nominal mass, and there is no need to measure this error in advance. The calculation processing means 3 performs calculation processing on the output signal from the load detection section 1 according to the calculation mode selected by the mode selection means 5 from among the three calculation modes A, B, and C stored in the memory 4. Mode A is applied when an external reference weight with a predetermined nominal mass is applied as an external load, and when an internal reference weight 2 is applied as an external load.
In this mode, the difference with respect to the nominal mass of the built-in weight 2 is calculated and stored from the output of the load detection section 1 when a load is applied.

In mode B, when an external load is applied to the load detection section 1,
This is a mode in which the output of the load detection section 1 is converted into mass using the stored span coefficient and displayed as a measured value. Mode C is a mode in which the span coefficient is calculated using the output signal when the built-in weight 2 is loaded on the load detection unit 1, the nominal mass, and the difference determined in mode A, and the span coefficient used in mode B is updated. It is.

(e) Examples Embodiments of the present invention will be described below based on the drawings.

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

The load detection unit 11 detects an external load on the weighing plate 11a or a weight adjustment mechanism 1 consisting of a cam 12a, a lever 12b, etc.
2, when the built-in weight 13 is loaded, an electric signal corresponding to the load is generated and supplied to the control section 15 via the AD converter 14.

The control unit 15 is composed of a microcomputer,
A CPU 15a that executes various calculations and programs and controls each peripheral device, a memory 15b that has an area for storing programs and various calculation results described later, and an interface circuit that connects the control unit 15 with external peripheral devices. It is composed of 15C etc. Connected to the control unit 15 are a group of operation keys 16 including a numeric keypad and selection keys 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, we will discuss the effect. FIG. 3 shows a memory 15 according to an embodiment of the present invention.
2 is a flowchart showing the entire data processing program written in FIG. Program 3, A, B, C
The routine consists of two mode execution routines, 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 instrumental error calculation routine calculates the instrumental error of the built-in weight 13 based on the span coefficient, and when mode B is selected, the mass on the weighing pan 11a is calculated using the stored span coefficient K. When the measurement routine that displays the measured value for the first time, selects mode C again, the span coefficient loads the built-in weight 13, adds ' to the span coefficient, and updates the previously stored span coefficient K to that value. Each calibration routine is executed.

Next, details of various routines corresponding to these modes A, B, and C will be explained.

FIG. 4 is a flowchart showing the instrumental error calculation routine. This routine is the routine selected during factory calibration at the time of manufacture or calibration using the user's standard weight.

First, the zero point is checked when no load is applied to the weighing pan 11a (STI I), and if it is off, the calibration operation will not begin and a warning will be displayed to notify you (STII).

5T12). If the zero point is normal, the output XO of the load detection section 110 at the time of no load is stored, and the system waits for the reference weight to be placed on the weighing pan 11a (ST14). This reference weight must have an error of less than the reading limit of this electronic balance with respect to the nominal mass Wr, or must be a weight with an instrumental error e accurately up to the value of the reading limit. When a reference weight is placed (ST15), an overload check is performed, and if it is overloaded for some reason, the calibration is stopped and a warning is displayed (ST16).
．． 5T17, 5T18). If there is an instrumental error e in the reference weight, enter that value using the numeric keys in the operation key group 16 (ST19).

Then, the output XI of the load detection section 11 when the reference weight is placed is stored (ST20), and the span coefficient is determined by the difference X2 between Xl and the output Xo under no load, the nominal mass Wr of the reference weight, and the instrumental error e. K = (W r +
e)/X2-(l) (S'
l'21). After that, when the reference weight is lowered, the zero point is checked again (ST22゜5T23), and if it is off, the calibration is stopped and a warning is displayed (ST24, 5T25).
). If the zero point is not shifted, remember the load detection unit 11 output Xo'(#Xo) at that time 5T26
), waits for the built-in weight 13 to be loaded, and when the built-in weight 13 is loaded by the weight addition/removal mechanism 12, the output X3 of the load detection section 11 at that time of loading is stored (ST27°5T28). Then, the difference X4 between that Xa and the output XO' under no load,
Based on the span coefficient calculated in 5T21 and the output difference x2 when the reference weight is loaded and when no load is applied, the built-in weight 13
The mass difference (instrumental difference) ΔW with respect to the nominal mass Wr is calculated by ΔW=K·(X 4−

FIG. 5 is a flowchart showing the measurement routine. This routine is the routine selected during normal measurement. If the zero point is off, a warning will be displayed, and if it is correct, the measurement operation will be executed (Sr10.Sr11.Sr
12). In this routine, when the object to be measured is placed on the weighing plate 11a (ST33), the load detection unit 11 due to the load
The output Xw is sampled (ST34), and its value is stored in the memory 15.
The mass W is given by the Snowgun coefficient K stored in b.
It is converted by W = K - Vessel 17
is displayed (ST37).

FIG. 6 is a flowchart showing the span calibration routine. This routine is a routine selected during span calibration that updates the span coefficient K using the built-in weight 13. 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 (ST3B, 5T39, 5T40). When the calibration operation starts, the output XO of the load detection section 11 at no load and the output X3 of the built-in weight 13 at load are memorized (ST41, 5T4
2゜Sr13), the difference X4 between Xa and Xo, the nominal mass Wr, and the built-in weight 13 determined by the instrumental error calculation routine.
Due to the instrumental error ΔW of
ΔW ) / X 4-c4) is calculated by (ST
44. ), the span coefficient K stored up to that point is updated to the value '' (ST45), and in the subsequent measurement routine, the mass is calculated using the updated span coefficient K.

In addition, in the above embodiment, in the instrumental error calculation routine,
We have described a case in which the span coefficient K is calculated before calculating the instrumental error ΔW of the built-in weight 13, and that value is used to calculate the instrumental error ΔW using equation (2). 2)
It is also possible to directly calculate the instrumental error ΔW using the equation '.

ΔW= (Wr+e)/(X4/X2-1)-12
)' In this case, there is no need to calculate the span coefficient K in the instrumental error calculation routine, and instead of 5T21 and 5T29 in Figure 4, 5T21' shown in Figures 7(a) and (b), respectively.
and 5T29' may be inserted.

Furthermore, it goes without saying that under the condition that the reference weight is used with an instrumental error within the reading limit, the numeric keypad for inputting the instrumental error among the group of operation keys becomes unnecessary.

(f) Effects As explained above, according to the present invention, a high-precision weight is not required as a built-in weight for span calibration, and the cost of an electronic balance can be significantly reduced. This cost reduction becomes more pronounced as the electronic balance becomes more precise. In addition, the built-in weight's instrumental error is measured and calibrated during manufacturing and inspection, eliminating the need for pre-measurement and management using a separate large bottle, and the above-mentioned cost reduction is substantial. becomes. Furthermore, according to the present invention, even if the difference between the mass of the reference weight or the nominal mass and the mass of the built-in weight is considerably large, high span calibration accuracy can be obtained, so that the built-in weight is no longer simply dimensional. There is no need to measure its mass at all, just by processing it into a predetermined size. Also,
Even when the user performs mass control using a standard weight on hand, the same instrumental error calculation routine as used during manufacturing can be selected, so that the user can effectively utilize the standard weight.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram showing the configuration of the present invention, FIG. 2 is a configuration diagram of an embodiment of the present invention, FIG. 3 is a flowchart showing the entire data processing program, and FIGS. FIG. 6 is a flowchart 1-1 showing details of each routine. FIG. 7 is a main part of a flowchart of an instrumental error calculation routine according to another embodiment of the present invention. 11-Load detection section 11a--Weighing plate 12--Weight addition/removal mechanism 13-Built-in weight 15--Control section 15 a-CP U15b--Memory 16-Group of operation keys 17-Display device Patent applicant Shimadzu Corporation Agent Patent Attorney Nishi 1) New Figure 6 Figure 7 (a) (b)

Claims (3)

[Claims] (1) A load MI* output section that outputs an electrical signal corresponding to the applied load, a plurality of calculation modes stored in the memory, and a mode selection means that selects any mode from among the plurality of calculation modes. , an arithmetic processing means for arithmetic processing the output of the load detection section according to the arithmetic mode selected by the mode selection means, and a built-in weight for span calibration having an arbitrary error with respect to the nominal mass; An electronic balance characterized by having three calculation modes, A, B, and C below. Mode A: A mode in which the difference between the built-in weight and the nominal mass is calculated and stored from the load detection section output when an external reference weight of a predetermined nominal mass is loaded and when the built-in weight is loaded. 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: A mode in which a span coefficient is calculated using the output of the load detection section when the built-in weight is loaded, the nominal mass, and the difference determined in Mode A, and the span coefficient used in Mode B is updated. (2) When executing mode A, the span coefficient is calculated from the output of the load detection section when the external reference weight is loaded, and the difference between the built-in weights is calculated using that value. An electronic balance according to claim 1, characterized in that: (3) When the external reference weight in mode A has an instrumental error with respect to the nominal mass, by inputting the instrumental error, the difference between the mass of the external reference weight and the nominal mass is corrected, and the built-in The electronic balance according to claim 1 or 2, characterized in that the electronic balance is configured to calculate the difference in weights.