JP2002214033A - Electronic balance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electronic balance which makes it possible to judge (confirm) whether data are reliable from output data (weighed value) displayed on a display unit and output data (weighed value) printed out by a printer. SOLUTION: A temperature sensor is provided at a part close to a load sensor and it is judged whether its detected temperature rises previously set certain temperature above the temperature obtained when the sensitivity is calibrated last; when so, additional information, e.g. a '×' mark is added to the weighed value (10.246 g). It is evident that the weighed value is measured in a sensitivity variation state and an unreliable weighed value (output data).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic balance, and more particularly to an electronic balance having a sensitivity calibration function. In addition,
The present invention is applicable not only to so-called electronic balances such as an electromagnetic force balance type, but also to a so-called electronic balance such as a load cell type or a tuning fork type using a strain gauge, or a capacitance type, and also to an electric weighing device using other types. Applicable, the term electronic balance also includes electronic balances.

[0002]

2. Description of the Related Art In general, an electronic balance takes in digital data of load data (output signal) from a load sensor every moment and averages the finite n pieces of data by a moving average or the like. Alternatively, the weight value is converted into a mass value by arithmetic processing such as multiplication by a span coefficient, the measured value is determined, and the measured value is displayed on a display device or printed out on a printer.

An electronic balance, particularly a high-precision electronic balance, has a ratio between the weighing and the reading limit of 1 / 1.6 million to 1: 1.
/ 2 million (0.5 PPM). But,
Electronic components and other components have relatively large temperature dependence and aging. For example, among the components, the permanent magnet has a temperature dependency of 200 to 400 PPM / ° C., and aging 1
Has 0 PPM / month. Therefore, even if various measures in measurement and strict adjustment during manufacturing are performed, the temperature dependency of the span is limited to 1 to 2 PPM / ° C, and the ambient temperature during measurement is only 1 ° C. Even if it is changed, an error corresponding to the reading limit of 2 to 4 counts occurs when the measurement near the weighing is performed. Therefore, such an electronic balance has a drawback that reliable measurement cannot be performed unless the room temperature is controlled to be constant.

For this purpose, the electronic balance is provided with a calibration function. In the calibration, an external weight for sensitivity calibration with a known mass or a built-in weight of the balance is loaded on the load detection unit, and the weighing in that state is performed. Check that the displayed value matches the calibration weight.
This operation is performed by updating a calibration coefficient or the like, and this operation is generally called sensitivity calibration or span calibration. By the way, such sensitivity calibration is performed not only at the time of installation of the electronic balance but also at any time as necessary or in order to eliminate the sensitivity change due to the aging of the components of the electronic balance, etc. If there is, or periodically after the time elapses,
Often done on the user side.

[0005]

In an electronic balance of this type having a sensitivity calibration function, a weight value is determined by converting the output signal of the load sensor into a mass value using a calibration coefficient and determining the weight value. Since the weighed value is configured to be displayed on a display unit or printed out by a printer, reliable calibration can be performed by frequently performing sensitivity calibration. However, there is the following problem.

In other words, even if the ambient environment at the time of measurement, for example, the temperature has changed by a certain amount or more since the previous calibration of the sensitivity and the sensitivity of the electronic balance has changed, the display or printer converts the sensitivity into a mass value. Since only the weighed value as output data is displayed or printed out,
From the weighing value displayed on the display unit or printed out by the printer, the weighing value maintains the sensitivity at the time of the previous calibration at the time of measurement and the reliability of the normal state of accuracy that satisfies the balance's specifications It is not possible to discriminate (determine) at all whether the measured value data has a certain weight value or the unreliable measured value data in a state where the sensitivity has changed from that at the time of the previous sensitivity calibration.

Therefore, there is a possibility that an unreliable weighing value (output data) displayed or printed out on a display or a printer in a state where the sensitivity has changed may be adopted as reliable normal state data. Although it does not cause much trouble for the purpose of use that only needs to be able to measure the approximate weighing value, it is a problem when high precision measurement is required,
There is a problem that some objects to be weighed (for example, chemicals) can be fatal.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and is based on output data (weighing values) displayed or printed out on a display or a printer, the data being used at the time of the previous sensitivity calibration. Is the reliable output data (weighing value) in the normal state with the accuracy that satisfies the specifications of the balance when the sensitivity has not changed, or the reliability has not changed when the sensitivity has changed since the previous calibration. An object of the present invention is to provide an electronic balance capable of distinguishing (determining) whether it is output data (weighing value).

[0009]

In order to solve the above problems, in the electronic balance of the present invention, a means for judging whether the sensitivity has changed since the previous calibration of the sensitivity, and a method for determining whether the sensitivity has changed a certain amount. Means for generating additional information. The determination of the sensitivity change from the previous calibration time can be made based on whether the temperature has changed by a certain temperature or more from the temperature at the previous calibration time and / or has passed a certain time or more from the previous calibration time. It is preferable that the additional information is added to the weighed value obtained by the arithmetic processing.

[0010] The additional information includes reliable normal output data (metric value) in a state where the sensitivity at the time of the previous calibration is maintained and unreliable output data (metric value) in a state where the sensitivity has changed. For example, in the case of a color display or a color printer, both data are displayed in different colors (for example, reliable normal data is displayed in black, and unreliable data in the sensitivity change state is displayed in red. ) Or before or after the weighing value, add a code or symbol to identify both data (for example, display or print by adding an E or x before the unreliable weighing value of the sensitivity change state). out)
It is done by things.

According to this configuration, if the sensitivity has changed since the previous calibration, the additional information is added to the output data (weighing value) displayed or printed out on the display or the printer as the measurement data. Therefore, with the additional information, for example, color or code, the weighing value maintains the sensitivity at the time of the previous calibration at the time of measurement, and the reliable weighing of the normal state with the accuracy that satisfies the specification of the balance. It is possible to distinguish (determine) whether the data is value data or unreliable weighing data in the state where the sensitivity has changed from the time of the previous sensitivity calibration. For measurements that require accuracy, the reliability in the state where the sensitivity has changed Since there is no need to employ data without any data, more accurate and reliable data can be obtained.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an electronic balance according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of the electronic balance of the present invention. The load detector 1 detects the load on the weighing pan 1a by the load sensor 1b, outputs an analog electric signal corresponding to the load, and the signal is input to the A / D converter 2 and converted into a digital signal. Then, it is input to the control unit 3.

The control section 3 is mainly composed of a microcomputer, and executes various calculations and programs, and controls each peripheral device, such as a CPU 3a, a ROM 3b, and a RAM.
3c, an input / output interface 3d, etc.
In addition to the A / D converter 2, the display 4 for displaying the weighing value, the printer 5, and the output data (the weighing value data, etc.) of the calculation results of the control unit 3 are transferred to an external device such as a computer. The output port 6, the mode changeover switch 7 and the like are connected. The digital conversion input from the load detection unit 1 is converted into mass in the control unit 3 and displayed on the display 4 or printed out by the printer 5 as described later.

In the ROM 3b, a program for adding additional information to a measured value, which will be described later, and the like are written in addition to a normal measurement program and a sensitivity calibration program. The RAM 3b is provided with a storage area for digital conversion data (load data) from the load detection unit 1, a storage area for sensitivity calibration coefficients (or span coefficients), and the like.

The load detecting section 1 is provided with a temperature sensor 8 close to the load sensor 1b.
Detects a temperature near the temperature sensor and outputs an analog electric signal corresponding to the detected temperature. The signal is introduced into the A / D converter 2 via the changeover switch SW, converted into a digital signal, and then input to the control unit 3.

The switch SW converts an input signal to the A / D converter 2 into an output signal from the load detector 1 and an output signal from the temperature sensor 8 at a predetermined interval based on a command from the controller 3. To switch alternately. Although not shown in FIG. 1, the electronic balance is loaded with a calibration weight and the weight on the load detection unit 1 for performing sensitivity calibration based on a command from a sensitivity calibration program from the control unit 3. Alternatively, a sensitivity calibration means including a weight adding / removing mechanism for removing the load is provided.

FIG. 2 is a flowchart showing a data processing program written in the ROM 3b according to one embodiment of the present invention.

First, a command is issued to the switch SW and switched to the t side to make the input signal to the A / D converter 2 a signal from the temperature sensor 8 and fetch the digitally converted temperature data t (ST1, ST2). ). The temperature data t is R
The temperature T to which the previous sensitivity (span) calibration stored in the AM 3c is stored is compared with the temperature T that is set in advance.
When there is no difference (for example, 0.5 ° C.) or more, the switch SW is switched to the d side to make the input signal to the A / D converter 2 a signal from the load detection unit 1 and the digital conversion data w
(ST3, ST4, ST5). Then, using the calibration (conversion) coefficient K at the time of the previous calibration stored in the RAM 3c, the data w is converted into the mass W as follows, W = K · w, the weighing value is determined, and the mode is switched. In the case of the display mode in which the switch 7 is not set to the external output mode to the printer or the external device, there is no external data output command.
Is displayed (ST6, ST7, ST8), and in the external output mode for outputting data to the printer, there is an external data output command. Print out (ST
6, ST7, ST9). Further, when the external output mode is an external data output mode for outputting data to a computer or the like, the data is transferred to an external device via the output port 6. Usually, such a measurement routine is executed.

If the temperature in the vicinity of the load sensor 1b changes by more than the above-mentioned temperature T due to a change in room temperature or the like, the temperature data t from the temperature sensor 8 is displayed at a constant cycle, in this example, every display of the measured value. Because it is reading, RAM3
Temperature data t at the time of previous sensitivity calibration stored in b
o, a preset temperature T (for example, 0.
If it is not less than 5 ° C.), a routine for adding additional information immediately after ST3 to ST10 is executed.

In this routine, the switch SW is switched to the d side, an input signal to the A / D converter 2 is used as a signal from the load detection unit 1, and the digital conversion data w is fetched.
Using the calibration (conversion) coefficient K stored in the RAM 3c, the data w is converted into the mass W as follows, W = K · w, a weighing value is determined, and additional information is added to the weighing value. Do (S
T10, ST11, ST12, ST13).

Since there is no external data command in the display mode in which the external output mode to the printer or the external device is not set by the mode change switch 7, the display weight value W
For example, as shown in the display example of FIG. 4, the display weight value W (10.246 g) is displayed with an X mark (ST7, ST8), and the data is output to the printer. In the case of the external data output mode, since there is an external data output command, the data is output to the printer 5, and the weight value W is printed with additional information (ST7,
ST9). When the external output mode is an external data output mode for outputting data to a computer or the like,
Similarly, the output (weighing value) data to which the additional information is added is transferred to the external device via the output port 6.

FIGS. 5, 6, and 7 show examples of the display on the display unit 4 and the printout (printing) of the printer 5. FIG. 5 shows a fixed temperature with respect to the temperature at the time of the previous sensitivity (span) calibration. The changed unreliable weighing value is underlined so that it can be distinguished from a reliable weighing value (normal weighing value) that does not change over a certain temperature, and FIG.
Fig. 7 shows an arrow indicating that the normal weighing value and the temperature at the time of the previous sensitivity (span) calibration have changed by more than a certain temperature, and the sensitivity has changed. This makes it possible to distinguish from the unreliable weighing value.

As described above, since the additional information is added to the weighing value (output data) in which the temperature has changed by a certain temperature or more from the temperature at the time of the previous sensitivity (span) calibration and the sensitivity change state is not reliable, the display is displayed. If you look at the printed output data (weighing value), whether the output data (weighing value) is in a reliable normal state or in the unreliable sensitivity change state Can be confirmed (discriminated), and accurate and reliable data can be obtained.

In the case where it is sufficient to obtain the approximate weighing value without requiring accurate weighing, the weighing value data to which the additional information is added may be used as the data. , The mode changeover switch 7 is used to switch to the sensitivity calibration mode. As a result, the sensitivity calibration program written in the ROM 3b is started, and a calibration weight (not shown) is loaded on the load sensor 1b, and the data w1 due to the load of the calibration weight, the data wo when there is no load, and the calibration weight are stored. The conversion coefficient K (or span coefficient S) is calculated by the following equation: K = P / (w-wo) (or S = (w-wo) / P), and the conversion coefficient K is stored in the RAM 3b until then. The sensitivity calibration coefficient calculated in the previous sensitivity calibration is rewritten and the conversion coefficient K is updated. After the sensitivity calibration, the same sample is placed on the weighing dish 1a and re-measured, so that accurate weighing can be performed. At the time of sensitivity calibration, the temperature at that time is detected by the temperature sensor 8, and the temperature is also stored in the RAM 3b and becomes a new reference temperature.

Next, as another embodiment of the present invention, an example will be described in which, in addition to the addition of additional information due to a constant temperature change, additional information can be added after a certain time has elapsed.

In this case, ST3 'shown in FIG. 3 may be inserted between ST3 and ST4 in the flowchart of the embodiment of FIG. With this, it is added when the temperature changes by more than a predetermined temperature from the temperature at the time of the previous sensitivity calibration, or when the time exceeds a predetermined time from the time of the previous sensitivity calibration, whichever comes first, whichever comes first. A routine for adding information is executed. Even if the additional information by time is executed, the process proceeds from ST3 'to ST10 and the temperature t at that time is stored as to. Therefore, immediately after the additional information by time is added, the additional information by the temperature change is immediately obtained. There is no waste that the addition of is performed. In this case, the means for measuring the elapsed time does not need to be separately equipped with hardware such as a clock function, and can be easily known from the number of revolutions of the program.

In the embodiment, a display,
Or, the weighing value of the printout is marked with an x mark or underline, but if it is a color display or color printer,
The additional information may be used to change the display color or printing color between the reliable normal measurement value and the unreliable sensitivity change measurement value. Any data can be used as long as it can distinguish certain data from unreliable data. In the embodiment, the temperature data from the temperature sensor and the load data from the load detection unit are alternately taken into the control unit. However, both data may be taken in parallel and simultaneously.

Further, in the embodiment, the sensitivity calibration is performed at any time by operating the mode changeover switch. However, a weight for sensitivity calibration is built in, and a certain temperature change or a certain time has elapsed since the previous calibration. When the elapsed time, etc., a calibration command is automatically generated, the built-in weight is loaded on the load detector, and the sensitivity calibration coefficient is updated from the output at that time and the pre-stored built-in weight mass. If the electronic balance has an automatic sensitivity calibration function, and the measurement is in progress even after a certain temperature change or a certain period of time, etc., continue the measurement and wait for the end of the measurement to perform the automatic sensitivity calibration. The present invention is also applicable to Japanese Patent No. 1980439 (Japanese Patent Publication No. 3-49052) according to the applicant of the present invention.

Since the present invention is constructed as described above, the ambient temperature at the time of measurement changes so that reliable measurement cannot be performed, and when the sensitivity changes, additional information is added to the measured value. Since the displayed value and the printed weighing value are added, the weighing value maintains the sensitivity at the time of the previous calibration at the time of measurement, and is in a normal state with an accuracy that satisfies the balance specifications. It is possible to distinguish (determine) whether the data is reliable weighing data or unreliable weighing data whose sensitivity has changed since the previous calibration of the sensitivity, and unreliable data whose sensitivity has changed Therefore, accurate and reliable data can be obtained.

Further, if the additional information is generated even when the sensitivity changes after a certain period of time has passed since the previous calibration of the sensitivity, the display value and the printed-out weighing value can be obtained even in the case of aging. Thus, it is possible to confirm (discriminate) whether the data is reliable or not, which is even more effective.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an electronic balance according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a data processing program according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a main part of a data processing program according to another embodiment of the present invention.

FIG. 4 is a diagram illustrating a display example of a weighing value.

FIG. 5 is a diagram showing another display example of a weighing value.

FIG. 6 is a diagram illustrating a printout example of a weighing value.

FIG. 7 is a diagram illustrating another example of a printout of a measured value.

[Explanation of symbols]

1: load detection unit 1a: weighing pan 1a 1b: load sensor 2: A / D converter 3: control unit 3a: CPU 3b: ROM 3c: RAM 3d: input / output interface 4: display unit 5: printer 6: Output port 7: Mode switch 8: Temperature sensor 8 SW: Switch

Claims (4)

[Claims] 1. An electronic balance having a sensitivity calibration function for processing load data from a load sensor to obtain a weighing value, comprising: means for judging whether or not the sensitivity has changed since the previous calibration of the sensitivity; Means for generating additional information when there is a problem. 2. An electronic balance having a sensitivity calibration function for processing load data from a load sensor to obtain a weighing value, wherein a temperature sensor is provided in proximity to the load sensor, and a temperature detected by the temperature sensor is provided. An electronic balance, comprising: means for judging whether the temperature has changed by a certain temperature or more from the temperature at the time of the previous sensitivity calibration; and means for generating additional information when the temperature has changed by a certain temperature or more. 3. An electronic balance provided with a sensitivity calibration function for processing load data from a load sensor to obtain a weighing value, and measuring an elapsed time from a previous sensitivity calibration time, and measuring the measured value for a predetermined time. An electronic balance, comprising: means for judging whether the operation has been performed; and means for generating additional information when a predetermined time has elapsed. 4. The electronic balance according to claim 1, wherein the additional information is added to a weighing value.