JP2000121423A - Electronic force balance having judging mechanism of calibration propriety/impropriety - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a calibrating work from being actually operated in an improper state while the calibrating work is apparently operated in a proper way. SOLUTION: In this electronic force balance having a built-in weight for calibration, a calibrating operation is constituted so that the outer zero point of span components can be monitored, and the calibrating operation is constituted so that two modes, that is, an adjustment mode and abnormal calibration mode can be set. In this case, a zero point W0n and a span coefficient SCn set in the adjustment mode are stored as data W0a and a span coefficient SCa to be used at the time of the constituting operation in the normal mode. At the item of the constituting operation in the normal mode, a zero point W0x and a span SCx are calculated from those zero point W0a and span coefficient SCa, and compared with a zero point allowable range E0 and a span allowable range Es inputted by an inputting means, and when at least either of them is beyond the allowable range, alarm is issued by an alarming means 12, and otherwise, they are updated to those W0x and SCx, and the calibrating operation is ended.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weighing apparatus for detecting an abnormality during calibration and improving the reliability of the calibration itself.

[0002]

2. Description of the Related Art For example, a high-precision electronic balance, such as an electromagnetic balance type weighing device called an electronic balance, is affected by changes over time in an internal mechanism, a change in an environment around the device, and the like, and the accuracy is reduced. Therefore, it is necessary to perform calibration appropriately to secure the accuracy as a weighing device. For this reason, many electronic balances currently used contain a calibration weight (hereinafter referred to as “internal weight”).

In an electronic balance having a built-in weight, for example, an accurate mass of the built-in weight is measured at a manufacturing stage of the electronic scale, and the measured value is stored in a storage means as a true value of the built-in weight, and the built-in weight measured at the time of calibration is measured. The electronic balance is calibrated by comparing the measured value with the true value.

However, the mass of the built-in weight may be different from the true value due to wear, oxidation, adhesion of dust, etc. of the built-in weight, and proper calibration cannot be performed as it is. There is. In view of this point, the following technology has been proposed. That is, in this proposal, an allowable value for the difference between the measured value of the built-in weight at the time of calibration and the stored true value of the built-in weight is set in advance, and the difference between the measured value and the true value is within this allowed value. Is determined, and if it is within the allowable value, the span coefficient is calculated by calibration, and the previous span coefficient is replaced with the newly calculated span coefficient. If the measured value exceeds the allowable value, it is determined that the built-in weight has become inappropriate for calibration due to wear, oxidation, or the like, and a warning is issued.

[0005]

Although the above-mentioned technique exhibits a certain effect in a certain time range, the object of calibration is limited to the span, and the variation of the zero point is not subject to calibration. Therefore, the following problem may occur. For example, vibration or shock during transportation or use of an electronic balance (hereinafter described as an example of an “electronic balance”) may affect the performance of the electronic balance. Zero points outside the span also need to be checked.

The above point will be described in more detail with reference to FIG. 4. First, Case 1 on the left side of the figure shows a case where an electronic balance is used at the time of adjustment in a manufacturing stage and this adjustment state is maintained. In this case, there is a weighing range A between the zero point 0 (a) at the time of calibration and the weighing Max (a).
And Max (a) are in the range where the performance has been confirmed. On the other hand, if the zero point is displaced to, for example, 0 (b) as in Case 2 and the weighing is displaced to Max (b) in response to this, a part of the weighing range A will deviate to a range where the performance has not been confirmed. That is, if the displacement of the true zero point exceeds the allowable value, a weighing range in which performance cannot be guaranteed even if the span is calibrated will occur.

In the prior art, when the measured value of the internal weight is within an allowable value with respect to the true value, a new span coefficient is calculated and replaced with the previously calculated span coefficient. , The next measurement of the load of the internal weight is performed. In this case, when the change of the built-in weight such as abrasion and oxidation is small and the difference between the true value and the measured value of the built-in weight falls within the allowable value, the calibration is performed and the span coefficient is replaced. In other words, the weight of the built-in weight is calculated as the weighing value using the latest span coefficient each time calibration is performed.In fact, even if the current weight of the built-in weight greatly changes due to changes over time from the first measurement of the `` true value '' However, this cannot be checked, and a situation may occur in which a weighed value whose accuracy is not actually guaranteed is recognized as a correct numerical value.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems. In other words, means for measuring the load of the calibration weight (hereinafter described as an example of the "internal weight"), means for storing the true value of the internal weight, and comparing the weighed value and the true value of the internal weight during calibration Means for performing a calibration operation in an adjustment mode and a means for performing a calibration operation in a normal mode, and the inspection target at the time of the calibration operation is data relating to a zero point and a span. Means for setting a zero point and a span coefficient in calibration in the adjustment mode, and storing the zero point and the span coefficient in a storage means as a reference value of the zero point and the span coefficient of the electronic balance; Means are provided for storing as normal mode calibration data, and means for setting and storing zero point and span allowable values based on the zero point and span coefficient. Means for obtaining a zero and span metric using the zero and span coefficients stored as data, and comparing the zero or span metric with the zero and span tolerances. The zero point and the span coefficient are updated when the zero point and the span of the weighing value are within the allowable value by the comparing means, and at least one of the zero point and the span is out of the allowable value. In this case, the electronic balance has a function of judging whether or not the calibration is appropriate, wherein the electronic balance is configured not to update the zero point and the span coefficient.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The electronic balance enters into a calibration operation automatically or manually by detecting a change in the environment of the electronic balance by various sensors. When the calibration operation is started, the zero point data is first taken in before the calibration weight is loaded. Next, using the built-in or external calibration weight, the measured value of the calibration weight is acquired. When the adjustment mode is entered, the span coefficient is calculated and stored from the zero point data at the time of calibration, the measured value of the calibration weight, and the true value of the calibration weight.

On the other hand, when the calibration in the normal mode is performed, the allowable value of the zero point and the allowable value of the span are set in advance.
Using the set zero point and span coefficient, the acquired zero point and calibration weight values are converted into weighing values (actually displayed values). Also, the span is calculated from the zero point and the value of the calibration weight converted into the weighed value.

Next, it is determined whether the above-mentioned zero point is within a preset allowable value and whether the span is within a preset allowable value. Gives a warning. On the other hand, if both values are within the allowable values, the values are updated to the calibrated zero point and span coefficient.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. First, FIG. 1 shows an electronic balance, which is one of the electronic balances, in which the present invention is implemented, and a calibration weight is a built-in weight stored in the electronic balance. The weight is applied to the load detection mechanism.

In this electronic balance, the steps of adding and removing the built-in weight and measuring the load are the same as those of a conventional electronic balance having a built-in weight. The electronic balance automatically enters a calibration operation by a manual calibration operation command or when the sensor 3 detects a certain amount of change (temperature change, humidity change, etc.) of the environment in which the electronic balance is placed. The calibration operation signal is transmitted from the CPU 1 to the motor 5 via the motor drive circuit 4, and the weight adding / removing mechanism 7 is operated by the motor 5 to apply the load of the built-in weight 6 to the load detecting mechanism 8. The detection result is converted into a digital signal via the A / D converter 9 by the CPU.
1 and the load of the internal weight 6 is calculated. The load data of the built-in weight at the time of calibration is a value that is not directly related to the user of the electronic balance, and is not normally displayed on the display unit 11.

Reference numeral 10 denotes a calibration operation command unit, which is configured to receive a manual signal from the input means 2 or a detection signal from the sensor 3 and issue a command signal for starting a calibration operation to the CPU 1. . 12 is a warning means,
When at least one of the zero point and the span measured in the calibration work exceeds a predetermined allowable value, the warning means that the calibration work is disabled and a warning is issued.

Reference numeral 13 denotes a memory mechanism, which is a storage means for storing a zero point, a span coefficient, and the like corresponding to a work mode at the time of calibration. Reference numeral 14 denotes means for selecting whether to perform the calibration work in the adjustment mode or the normal mode at the time of calibration.

The operation of the present invention will be described below mainly with reference to FIGS. First, a calibration operation command is issued automatically by a manual calibration operation command of the input means 2 or automatically when a change in a physical quantity such as temperature or humidity by the sensor 3 exceeds a preset value (S1). The balance enters the calibration mode. When the calibration mode is entered, the zero point data W0 is stored in the storage means before the calibration weight is applied to the load detection mechanism 8. As the calibration weight, one of a case where the built-in weight 6 shown in FIG. 1 is used and a case where an external calibration weight is used instead of the built-in weight 6 are selected (S3).

When the internal weight is used, the true value CW of the internal weight is extracted from the storage means to the arithmetic unit of the CPU 1 (S4), and the internal weight 6 is loaded on the load detecting mechanism 8 in this state (S5). Similarly, when the calibration weight is an external weight, the true value CW of the external weight is extracted from the storage means (S
4 '), the calibration weight is placed on a weighing dish, and the external weight is applied to the load detection mechanism 8 (S5').

Subsequently, in FIG. 3, the measured data WF of the calibration weight is obtained and stored in the storage means (S6).
At this stage, the calibration operation selects one of the adjustment mode (hereinafter, indicated by reference numeral Pa) and the normal mode (hereinafter, indicated by reference numeral Pn) (S7). The adjustment is performed when the electronic balance is manufactured. Therefore, the adjustment mode is performed at the stage of manufacturing the electronic balance. Therefore, when the electronic balance is used, the calibration of the adjustment mode is not normally performed. However, if readjustment is necessary even in the use stage, it is possible to instruct the input means 2 or the like to select this adjustment mode.

After explaining the meaning of both modes, the calibration operation in the adjustment mode will be described first. First, the zero point data W0 at the time of no load is stored as the zero point (reference zero point) W0a at the time of the calibration work in the adjustment mode, and the zero point data W0, the measurement data WF when the calibration weight is loaded, From the true value CW of the calibration weight, a span coefficient (reference span coefficient) SCa is obtained from the following equation (1) (S
8). SCa = CW / (WF-W0) (1) Further, these zero point W0a and span coefficient SCa are stored as reference values of the electronic balance and are copied as values W0n and SCn used at the time of normal mode calibration. And stored (S9). Incidentally, the reference zero point and span coefficient set in the adjustment mode are not changed unless the calibration of the adjustment mode is newly performed, and are held as reference values in the setting of the allowable value described later. . In addition, since the load of the internal weight or the external weight applied in S3 (S3 ′) to S5 (S5 ′), including the calibration in the normal mode described later, is naturally removed after the completion of the calibration, FIG. Not directly shown in the flow.

On the other hand, in the case of the calibration in the normal mode, the reference values W0a, SC
First, based on a, the allowable value E0 of the zero point and the allowable value Es of the span are set (S10). This setting may be performed, for example, using the input means 2 shown in FIG. 1 or may be previously set and stored in the memory of the electronic balance. Next, using the calibration data stored and set in the adjustment mode, that is, the zero point data W0 captured in (S2) and the load data WF of the calibration weight captured in (S6), using the zero point W0a and the span coefficient SCa. The weights W0x and WFx are converted into the weighing values W0x and WFx according to the following equations (2) and (3). Further, as shown in the equation (4), finally the calibration operation is performed based on the weighing value W0x of the zero point and the weighing value WFx of the calibration weight. Of the calibration weight WSx is obtained (S11). W0x = (W0−W0a) × SCa (2) WFx = (WF−W0a) × SCa (3) WSx = WFx−W0x (4)

Subsequently, it is determined whether the weighing value W0x of the zero point is within the allowable value E0 (S12), and if it exceeds the allowable value, a warning is issued (S13). Similarly, it is determined whether the span is within the allowable value Es of the span (S14). If the span exceeds the allowable value, S1 is determined.
As in the case of 2, a warning is issued (S13).

On the other hand, when both the zero point and the span are within the allowable values, the calibration data W0n and SCn relating to the zero point and the span are updated and the calibration is completed (S15).

In normal load measurement, the weighed value of the object is displayed based on the zero point W0n and the span coefficient Scn set by the calibration. That is, the weight data W of the sample loaded on the load detector 8 is obtained (S16), and a weighing value is calculated from the load data by the following equation (6) (S17).
This is displayed on the display unit 11 (S18). W = (W−W0n) × SCn (6)

[0024]

As described above in detail with the embodiments, since the present invention targets both the span component and the zero point for calibration, in the prior art in which the calibration operation is started by a change in the span component, the calibration weight is not used. If the mass changes within the allowable value, the calibration operation is performed and the span coefficient is updated, and an incorrect calibration is performed over time by repeating this several times. In contrast to this, the present invention also monitors the zero point fluctuation, and the zero point and the span are fixed as a reference value unless a new calibration of the adjustment mode is performed. Since the allowable values of the point and the span are set, the calibration operation is not performed when any one of the zero point side and the span side exceeds the allowable value. As a result, improper calibration that appears to be performed correctly on the surface is not performed, and high measurement accuracy can be always maintained by the calibration.

[Brief description of the drawings]

FIG. 1 is a block diagram of an electronic balance showing a configuration example of the present invention.

FIG. 2 is a part of a flowchart showing an operation state of the present invention.

FIG. 3 is a flowchart that follows the flowchart shown in FIG. 2;

FIG. 4 is a conceptual diagram showing a relationship between a change in a zero point and a performance check of a weighing range of a weighing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Central processing unit (CPU) 2 Input means 3 Sensor 5 Motor 6 Built-in weight 7 Built-in weight adding and removing mechanism 8 Load detection mechanism 12 Warning means 13 Memory mechanism

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yasuhiro Takano 1-243 Asahi, Kitamoto-shi, Saitama A & D Development & Technology Center

Claims (2)

[Claims] 1. An electronic apparatus comprising: means for measuring the load of a calibration weight; means for storing the true value of the calibration weight; and means for comparing the measured value and the true value of the calibration weight at the time of calibration. In the balance, the calibration operation is provided with means for performing a calibration operation in the adjustment mode and means for performing a calibration operation in the normal mode,
And the inspection object at the time of the calibration operation is data relating to the zero point and the span, the zero point and the span coefficient are configured to be set in the calibration in the adjustment mode, and the zero point and the span coefficient are set to the zero point and the span of the electronic balance. Means for storing in a storage means as a reference value of a span coefficient, means for storing as calibration data in a normal mode, and means for setting and storing allowable values of a zero point and a span based on the zero point and the span coefficient. The calibration in the normal mode is configured to obtain the weighed value of the zero point and the span using the zero point and the span coefficient stored as the calibration data, and the weighed value of the zero point or the span and the zero Means are provided for comparing the points and spans with the tolerances. If the zeros and spans of these measurements are within the tolerances, the zeros and It has a function of determining whether or not the calibration is appropriate, characterized in that the pan coefficient is updated and the zero point and the span coefficient are not updated when at least one of the zero point and the span is outside the allowable value. Electronic scales. 2. The electronic balance according to claim 1, wherein a warning is issued when at least one of the zero point and the span is out of an allowable value.