JPS6110729A - Electronic balance - Google Patents

Abstract

PURPOSE:To perform span calibration readily, by displaying the value of calibrating mass to be loaded on a display, making it possible to correct the value arbitrarily, loading the mass having said value, and computing the span coefficient based on the output of a load detecting part and the displayed value. CONSTITUTION:A load detecting part 1 detects a load on a pan. The detected value is inputted to a control part 4 through an amplifier 2 and an A/D converter 3. The control part 4 has a CPU41, a ROM42, RAMs 43 and 44 and input and output ports 45. When a span is calibrated, the central value, the average value, the actually used value that is closest to the average value or the most frequent value in the group of the mass values, which are used in all the past span calibrations or in the span calibrations at the specified recent times, is displayed on a display 5. The mass having the displayed value is loaded. The span coefficient is computed based on the output of the load detecting part 1 and the displayed value of the display 5. The value displayed on the display 5 can be arbitrarily corrected.

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 having a span calibration function.

(b) Prior Art Conventionally, span calibration of electronic balances has been carried out by loading a calibration weight whose mass has been adjusted sufficiently accurately. In other words, the weights used for calibration are 100g, 500g, 1k, etc., so that they can be used with any balance.
It was fine-tuned to have a good mass of so-called "one piece" such as g. Therefore, the manufacturing cost was inevitably high, and it was impossible due to the price to sell it together with an electronic balance as a standard accessory. .

Furthermore, there are two methods for performing span calibration: one using hardware and the other using software. Span calibration using hardware involves turning the span adjustment volume and adjusting the IIM so that the displayed value matches the load mass, but with this method, it is not always necessary to use a well-defined calibration mass. However, the disadvantage is that turning the volume inevitably moves the zero point, making the calibration process extremely complicated. On the other hand, software that performs span calibration conventionally loads a weight corresponding to the calibration mass stored as a constant in memory, calculates and stores the span coefficient, but in this case the zero point is automatically corrected. Although it is possible and the calibration work is easy, the calibration weight that can be used is limited to the mass stored in the memory, and it is necessary to use a weight with a well-defined mass such as the full scale value of the electronic balance. However, as mentioned above, expensive calibration weights were required.

(C) Purpose The present invention has been made in view of the above, and is capable of performing span calibration using software, and can be performed arbitrarily as long as the exact mass is known, without using expensive calibration weights. The purpose of the present invention is to provide an electronic balance that can perform span calibration using a weight having a mass of .

(d) Configuration The present invention is characterized by:
The following (a) to (d) are the calibration mass values to be loaded.
displaying at least one numerical value on a display, and
The displayed numerical value can be corrected arbitrarily, and by applying the mass of the displayed numerical value, the span coefficient can be calculated from the output of the load detection section and the displayed value. be.

(a) Median value or average value, or the practical value or mode closest to the average value of mass value groups used in all past or recent span calibrations (b) Immediately before Mass value actually used during span calibration (c) Full scale value of the electronic balance (d) Group of mass values used during all past or recent span calibrations, whichever is closer to the most recent value The median, average, or mode of a group of numerical values obtained by weighting the numerical values of
E) Embodiments Examples of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

A load detection section 1 detects the load on the plate, and the detected value is amplified by an amplifier 2, digitized by an A-D converter 3, and input to a control section 4.

The control unit 4 is composed of a microcomputer, and includes C and PU4 that execute programs and control each peripheral device, which will be described later.
1. ROM 42 in which the program is written, A mentioned above
- RAM 43 with an area for storing digital conversion data from the D converter 3 and various calculation results. It has a nonvolatile RAM 44 that stores the calculated span coefficient and a plurality of calibration mass values used in the past, and an input/output port 45, which are connected to each other by a pass line.

Connected to the control unit 4 are a digital display 5 for displaying measured values, etc., and a tare erase key 6 for giving a tare erase instruction in a normal measurement state. Further, a jumper wire 7 is connected to the input/output board 45 of the control unit 4, and this jumper wire 7 is cut when the electronic balance is handed over from the manufacturer to the user. Later, it is configured to give an input of "θ".

Next, we will discuss the effect. FIG. 2 is a flowchart showing the program written in the ROM 42.

This program starts when you turn on the power, and first,
Check the connection status of the jumper wire 7 of the input/output boat 45,
Determine whether it is used by the manufacturer or by the user (STI). ST2 if used by the manufacturer
is executed and handed over to the user, ST2 is jumped.

In ST2, registers dsp (1) and dsp (2) set in the nonvolatile RAM 44
...The full scale value of the electronic balance is stored in each dsp(n). This is to prevent meaningless or difficult-to-correct values such as zero from being included in the calibration mass values used during the last n span calibrations required in ST8, which will be described later.

Now, in a normal weight measurement state, the process proceeds from ST3 to ST4 and below, reads the digitally converted data from the load detection section 1 (ST4), averages the data to stabilize the displayed value, and stores it in the non-volatile RAM 44. The weighing value is determined by performing calculations such as conversion using the span coefficient and tare erasure processing (5T5), and is displayed on the digital display 5 (ST6).

On the other hand, if span calibration is instructed by, for example, holding down the tare erase key 6 for 3 seconds or more, the steps from ST3 to ST
7 and below, a span calibration routine is executed. In the span calibration routine, first, data from the load detection section 1 under no load, that is, zero load data Wz is taken in, and an average value Wz is calculated from N pieces of data and stored (ST7).

Next, the calibration mass value dsp(1) stored in the nonvolatile RAM 44 and used during the last n span calibrations,
dsp (2) . . . Among the dsp (n), the mode Dsp is displayed on the digital display 5 (ST8).

For example, for an electronic balance with a full scale weight of 1 dazzle and a minimum scale of 0.1 g, where n is 5, the calibration masses used in the last 5 times are 1000.0 g, 1000.1 g, '99
9.8g.

If it is 1000.1g, 1000.1g,
1000.1 g will be displayed. If this displayed value Dsp matches the mass value of a handheld weight with a known mass that you are about to use for span calibration, for example, by holding down the tare erase key 6 for more than 3 seconds in this state, the numerical value correction is completed. When given an instruction to that effect, 5T1
Proceed to 4 or below (ST9). If the displayed value Dsp is different from the mass value of the weight, press the tare erase key 6 for less than 3 seconds to proceed to 5 TIO or less and correct the displayed value Dsp. If the displayed value Dsp is smaller than the mass value of the weight, for example, by pressing the tare erase key 6 again for 3 seconds or more, and if it is larger, by pressing it for less than 3 seconds, the displayed value Dsp will increase by 1 count or 1, respectively. Countdown (STIO, 5TII, 5T12) In the above example, 1000.1 g is displayed, but ST1
When 1 is executed, 1000.2 g is displayed, and when 5T12 is executed, 1000.0 g is displayed. When the displayed value Dsp has been corrected to match the mass value of the weight actually used for span calibration by 5 TIO or less, an instruction to the effect that the numerical correction is complete is given by, for example, holding down the tare erase key 6 for more than 6 seconds. If given, the process advances to 5T14 and below (ST13). If the displayed value when the numerical correction completion instruction is given by this 5T13 or ST9 is D'sp, then that value D'sp is stored as dsp (1), and the previous dsp (1)... dsp (
n-1) respectively, and the oldest data d
Discard sp(n) (ST14). As described above, the calibration mass values used for the last n span calibrations are always stored in the nonvolatile RAM 44, and the most frequently used value Dsp among them is displayed first in ST8. . Therefore, as the span calibration work is repeated, correction operations for 5TIO to 5T13 become almost unnecessary, which is extremely efficient.

Now, after instructing the completion of correction using ST9 or 5T13, when the calibration weight is placed on the pan, the digital conversion data from the load detection section 1 at that time is collected and the load value is calculated using the currently held span coefficient. Convert to STI 5. S
TI 6), it is determined whether the value is within ±1% of the displayed value Dsp (ST17). This reduces the possibility of entering span calibration with incorrect values corrected.

When a calibration weight having a mass matching the displayed value Dsp is placed, M pieces of digital conversion data Ws from the load detection unit 1 at that time are collected, and the average value Ws is calculated and stored (ST18). .

Next, from the average value Ws, the average value Wz of the zero load data mentioned above, and the displayed value Dsp, that is, the mass value of the calibration weight, the span coefficient S is calculated using the following formula and stored in the nonvolatile RAM 44. (ST19).

S = Dsp/ (Ws - Wz) Also RAM43
Store Wz in the zero register Z provided in the
Zero point correction is performed in conjunction with span calibration (ST20). Then, the span calibration completion is displayed (ST21), and the ST
4. Move to the weighing routine below. Note that the conversion of the digital conversion data W from the load detection section 1 into the load value P in ST5 is as follows: P=(W-Z)x3.

In the correction routine for the displayed value of 5 TIO or less in the above flowchart, as shown in FIG.
Count amplifier or after 1 countdown (STI
O1, or 5T102), determine whether the value D's p is within the range of ±10% of the full scale value, for example 5T103), and display the Dsp only when it is within this range 5T104) If the configuration is configured to display an error if it is outside the range (ST105), there is a risk that span calibration cannot be performed with a calibration mass that is too large (deviating from the full scale value), resulting in a large error in the obtained span coefficient. The range of ±10% mentioned above is
It should be determined according to the performance of the electronic balance in question.

In the embodiments of the present invention described above, operations for inputting various instructions during span calibration were performed only by operating the tare erase key 6, but it goes without saying that a dedicated key etc. may be provided separately. By using keys such as a tare erase key that are included in ordinary electronic balances, there is no need to add special hardware equipment.

Further, although an example has been shown in which the display value Dsp of the first calibration mass value is the mode of the most recent n calibration mass values, it may also be the median value, average value, etc. of the n calibration mass values. Furthermore, the calibration mass value used immediately before may be used, or the full scale value of the electronic balance may be displayed as Dsp. Furthermore, dsp (1) ... dsp (n) used during the last n calibrations
The latest numerical value (dsp(1)) is weighted, for example, n pieces of dsp(1), n-1 pieces of dsp(2), etc.
Considering that there is one dSp(n), fi+(n-1)+...
+1=Ln(n+1) mode, average, center,
)-value etc. may be used as Dsp. In this case, it is possible to expect further improvement in correction efficiency than in the above embodiment.

Also, when finding the mode, instead of using the most recent n values,
Although it may be configured to calculate from all past calibration mass values, a problem may arise due to the storage capacity of the nonvolatile RAM 44.

In addition, in order to jump ST2, a jumper wire 7 is provided and the jumper wire 7 is disconnected, but instead of this, STI is executed only when the power is turned on with the tare erase key 6 pressed. It may be configured so that

(F) Effects As explained above, according to the present invention, span calibration can be performed using software, and even if the exact mass is known, instead of being limited to a well-defined calibration mass as in the past. Then, span calibration can be performed using a weight of any mass, making it easy to perform calibration work without having to perform complicated work such as zero point adjustment.
Weights for span calibration can now be manufactured at extremely low cost, and can now be sold as standard accessories for electronic balances, for example. In addition, if the display value Dsp can be corrected using a key attached to a normal electronic balance, such as a tare erase key, there is no need to provide a numeric keypad or dedicated keys, which increases hardware costs. It will never be.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a flowchart showing a program written in the ROM 42, and FIG. 3 is a flowchart of the main part of the program of another embodiment of the invention. l...Load detection unit 3...A-D converter 4...Control unit 5...Digital display unit 6...Tare erase key 7...Jumper wire 41...CPU 42...・ROM 43...RAM 44...Nonvolatile RAM 45...I/O board

Claims (3)

[Claims] (1) Output of the load detection section when a known mass is loaded,
In an electronic balance equipped with a span calibration program that calculates and stores a span coefficient from the known mass value, when span calibration is instructed, the following (a) to At least one of (d)
The above span calibration program is executed by displaying one numerical value on the display and allowing the displayed numerical value to be corrected arbitrarily, and by loading an arbitrary mass according to the displayed numerical value. An electronic balance characterized in that it is configured to obtain. (a) Median value, average value, or the practical numerical value or mode closest to the average value of the mass value group used in all past or recent span calibrations a predetermined number of times. (b) The mass value actually used at the time of the most recent span calibration (c) The full scale value of the electronic balance (d) The mass value group used for all past or recent span calibrations The median, average, or mode of a group of numerical values obtained by weighting the numerical value closest to the numerical value of (2) Claim 1 characterized in that the span calibration program is configured to be executed only when the corrected numerical value is within a predetermined range with respect to a preset numerical value. Electronic balance as described in section. (3) Claims 1 or 2 are characterized in that the above correction is configured to be executed by operating an input means provided in a normal electronic balance, such as a tare erase key.
Electronic balance as described in section.