JPH071195B2 - Electronic balance with built-in calibration weight - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to an electronic balance having a built-in calibration weight.

<Prior Art> Regarding an electronic balance having a built-in calibration weight, the present applicant has already found that the weight of a balance with a weighing capacity of 300 g is 30%.
Without using a weight whose mass is precisely adjusted to 0.0000 g,
An electronic balance has been proposed in which a so-called coarsely adjusted weight having an arbitrary mass is used as a built-in weight, and the mass is stored in a memory so that it can be accurately calibrated by calculation (Japanese Patent Laid-Open No. 60-13224). Issue, Japanese Patent Application No. 1-226480
issue).

Also, when such a coarse weight is adopted as the built-in weight, a proposal is made for an electronic balance that is calibrated so that when the built-in weight is loaded, the display is the same as if a precisely adjusted weight was loaded. (Actual Kaisho
63-193329).

<Problems to be solved by the invention> By the way, as the built-in weight, a weight having a mass that is not accurately adjusted and has a mass (for example, 1/2 or 1/3 of the weighing capacity) significantly different from the balance weighing capacity is used. Used in the above
When using the technologies of 60-13224 and No. 63-193329, the sensitivity of the display of the balance in that state is configured when the same display as when using an accurate weight is configured at the time of calibration. , Temporarily, for example, twice to three times the actual
However, there is a problem in that a very large measurement error occurs if the sample is erroneously measured in the same state.

The present invention has been made to solve such a problem, and even if the built-in calibration weight is significantly lightened with respect to the weighing capacity of the balance, it is possible to continue to make an error due to tare weighting in the calibration state. The purpose is to provide an electronic balance without the risk of making measurements.

<Means for Solving the Problems> A configuration for achieving the above object will be described with reference to the basic conceptual diagram shown in FIG. 1. The present invention is based on conversion using a calibration coefficient in a coefficient memory a. By the calculation by means b,
The output from the force detector c is converted into the mass and displayed on the display d, and the built-in calibration weight f that can be loaded / disengaged with respect to the force detector c by the weight addition / removal mechanism e and the built-in weight f. The mass W ₀ or the mass β of the mass W ₀ relative to the weighing capacity of the balance in question, the calibration mass memory g, the output of the force detector c when the built-in weight f is loaded, and the contents of the calibration mass memory g. In the balance equipped with the coefficient updating means h for calculating and updating the content of the coefficient memory a, the mass W ₀ of the built-in weight f is set to a value different from the weighing capacity of the balance, and when the built-in weight f is loaded, Using the mass measurement result and the contents of the calibration mass memory g, a calculation means i for calculating the span change amount δ when a mass equal to the weighing capacity of the balance is loaded, and its value when calculating the span change amount δ. with δ Characterized by providing the display control unit j to display a symbol representing the pan change in indicator d.

<Operation> When the built-in weight f is loaded during span calibration or span check, even if the weight mass W ₀ is significantly different from the weighing capacity of the balance, the span variation δ when the weighing capacity is loaded is Although calculated and displayed on the display device d, at the same time, a symbol indicating that the display represents a span change is displayed.

If a weight mass W ₀ of 1/2 of the weighing capacity is adopted, the display sensitivity will be greatly increased in the display state of the span change δ. By displaying with the symbol that it is being displayed,
A display that is completely different from the display during normal measurement is displayed, and it is possible to prevent erroneous measurement from occurring.

<Embodiment> FIG. 2 is a block diagram of an embodiment of the present invention.

The force detector 1 is composed of a dish 11 and a force sensor 12 such as an electromagnetic force generator that engages with the dish 11, and when a force acting on the dish 11 or a built-in weight 2 is loaded, a corresponding electric signal is generated. The generated output signal is taken into the control unit 5 via the amplifier 3 and the AD converter 4.

The built-in weight 2 has, for example, a shaft 62a of the cam 62 via an external knob (not shown) via a weight adjusting mechanism 6 including a lever 61 and a cam 62 for inclining the lever 61.
The force detector 1 can be loaded or unloaded at any time by rotating the force detector 1 or the like. The built-in weight 2 is a roughly adjusted weight, and its mass W ₀ is accurately measured in advance.

The control unit 5 is mainly composed of a microcomputer, and has a CPU 51 and R ₀ M5 in which a program described later is written.
2, a RAM 53 in which an area for storing digital conversion data from the force detector 1 and a work area are set, a non-volatile RAM 54 for storing the mass W ₀ of the built-in weight 2 and a span coefficient α described later, And an input / output port 55 for exchanging signals with external devices.

The control unit 5 includes a display 7 for displaying a mass measurement value of the sample placed on the plate 11 or a span change amount δ described later and a symbol indicating that the span change is being displayed.
The mode selection switch 8 is connected. By operating the mode selection switch 8, it is possible to select any one of the normal mode, the span calibration mode, and the span confirmation mode as described later.

FIG. 3 is a flow chart showing the contents of the program written in R ₀ M53, and the operation of the embodiment of the present invention will be described below with reference to this figure.

When the normal mode is selected, it proceeds to ST3 via ST1 and ST2, and the digital conversion data W from the force detector 1
_X , span coefficient α in nonvolatile RAM 54, and tare weight α
Calculate the measured display value D from W _T using the following equation (1),
Display on the display 7 (ST4).

D = αW _X −αW _T (1) Set the indicator 7 in the state where the measured display value D is displayed to the 4th position.
It is shown in FIG.

Note that the tare data W _T is stored in the RAM 53, and when the tare erase switch (not shown in FIG. 2) is operated in this state, the tare data W _T is stored in the same manner as a conventional normal electronic balance. The force detection data W _X in the state is stored in the RAM 53 as tare data W _T (ST5, ST6).

When the calibration mode is selected by the mode selection switch 8,
After proceeding from ST1 to ST7 to set a flag, first, the digital conversion data W _T of the output of the force detector 1 in the unloaded state is taken in and stored (ST8).

Next, rotate the cam 62 manually (or electrically) to lower the lever 61 and put the built-in weight 2 into the load state. Then, proceed from ST2 to ST9 to ST10, and the force detection data W in that load state. Store _R in RAM53. Then, the data W _R , the data W _T in the no-load state, and the nonvolatile RAM 54
Using the weight value W ₀ in the formula, a calibration coefficient α is calculated from the following equation (2), and α stored in the nonvolatile RAM 54 is updated (ST11).

Then, the ratio β of the weight value H of this balance or a reference value close to the weight value (hereinafter referred to as the weight reference value H) and the calibration weight mass W ₀ β, β = H / W ₀ ... ( 3) is used to calculate the weighing standard value H from the equation (4) shown below.
Calculate a span change amount δ when a weight with the same mass as is loaded (ST12).

δ = βα (W _R −W _T ) −H (4) Note that β may be stored in the non-volatile RAM 54 in advance, or may be calculated for each span calibration. When β is stored in the non-volatile RAM 54, the weight reference value H is constant, and therefore the weight mass W ₀ need not be stored in particular.

Now, δ at the time of this span calibration should be 0.000 g because it is immediately after the span coefficient α is updated. Thus, for example the weighing balance is to be set to 300.000g weighing reference value H as 340.000G, when the internal weight mass W ₀ and 98.000G, and W _R -W _T was 112,000 counts Then, the span coefficient α is 8.75 × 10 ^-4 , β
≈3.06122, but at this time δ≈0.000 g.

Then, after calculating the span change amount δ, the flag is defeated in ST13, the process proceeds to ST15 and below, and the span change amount δ is displayed on the display unit 7. At this time, the display unit 7 displays A symbol indicating that the span change amount is displayed together with the value of, for example, "SPAN" is also displayed (ST16). This display state is shown in FIG. From this display, the operator knows that the span has been correctly calibrated.

When performing the span confirmation, the span confirmation mode is selected by the mode selection switch 8 and the built-in weight 2 is loaded.

In this case, proceed from ST1 to ST2 to ST9 to ST14
In force detection data W _R , tare data W _T and non-volatile RAM5
From the span coefficients α and β within 4, the span change amount δ is calculated using the equation (4) described above. If there is a span change, the value of δ will not be 0.000g. Then, the magnitude of δ is compared with a preset allowable value in ST15, and if it is within the allowable value range, the process proceeds to ST16 and the symbol “SPAN” is displayed as shown in FIG. 4 (c). At the same time, the value of δ is displayed on the display 7.

With this display, even if the built-in weight 2 has a weight of 98g, which is significantly smaller than the standard weight of 300g,
It is possible to display the same span error as if the span was checked using a 300 g weight, and from this display, it is possible to judge whether or not span calibration is necessary by checking the value of δ according to the purpose of use and required accuracy. It can be performed. An ordinary electronic balance uses a built-in weight having the same mass as the weighing standard value of 300 g, and is displayed as, for example, 299.997 g.

When confirming this span or calibrating the span, ST15
If the value of δ is equal to or greater than the preset allowable value, such as 0.010 g or more, proceed to ST17 for safety and change to the value of δ as shown in FIG. 4 (d). Display as follows.

According to the embodiment of the present invention as described above, in the state where the built-in weight 2 is loaded and the span change amount δ is displayed, the value of δ and the display of “SPAN” are combined on the display unit 7. Since it is performed and the display mode is completely different from the display in the normal measurement state, the sample is not erroneously measured in that state. Further, when ST15 is provided and the value of δ becomes larger than a certain value, the value is not displayed so that mistakes can be prevented more effectively.

Further, in the display state of δ, the symbol may also be displayed together, and the value of δ may be held so that the display value is not changed even if a load acts on the plate 11, and in this case, The operator should notice the mistake because the displayed value does not change even if the symbol is overlooked and a sample is placed, and at the same time, the operator should be aware that the symbol is displayed and it is not a malfunction.

Here, it goes without saying that any symbol can be adopted as the symbol as long as it is clearly understood that δ is displayed in addition to “SPAN”.

In addition, the mass W ₀ or β of the built-in weight 2 is stored in the nonvolatile RAM 54.
As a method of storing the data in the balance, the balance itself has a flow chart shown in FIG. 5, so that the balance itself can measure and store its mass W ₀ .

That is, first, an external weight copper whose mass is accurately measured is prepared and placed on the dish 11 (ST101). Data W _T when the force detection data W and unloaded at this time, and the span factor alpha and a weighing reference value H, α = H / (W -W T) is calculated by ‥‥ (5) (ST102) .

Next, unload the outer weight and load the built-in weight 2 (ST10
3). If the data at this time is W _R , the calculation of W ₀ = (W _R −W _T ) ... (6) or β = (W−W _T ) / (W _R −W _T ) ... (7) (ST104) and set W ₀ or β to nonvolatile RAM 54
It is stored in (ST104).

Note that W ₀ or β may be measured separately and only the measured value may be written in the nonvolatile RAM 54.

<Effects of the Invention> As described above, according to the present invention, a calibration mass memory that stores the mass of the built-in weight or the ratio of the mass to the weight of the balance, and the output of the force detector when the built-in weight is loaded. In a balance that has the function to calculate and update the calibration coefficient from the contents of the calibration mass memory, set the mass of the built-in weight to a value different from the weighing capacity of the balance, and when the built-in weight is loaded, the mass measurement result and the calibration mass memory Using the contents, in addition to the calculation means for calculating the span change amount δ when a mass equal to the weighing capacity of the balance is loaded, when calculating the span change amount δ, this value together with the value δ gives the span change amount. Since a display control means for displaying a symbol indicating that it is displayed on the display is provided, a low-cost built-in weight that is significantly lighter than the balance capacity is used. Also, during span check or span calibration,
The span change amount δ can be displayed in the same way as when using a built-in weight having a mass equivalent to the weighing capacity, and not only is the span check result clearly displayed and easy to understand, but its The value of δ is displayed on the display together with a symbol indicating that the displayed value indicates the amount of change in the span, so during the span check and the span calibration state, forget this and tare. There is no risk of making incorrect measurements.

[Brief description of drawings]

FIG. 1 is a basic conceptual 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 flow chart showing the contents of the program written in the R ₀ M52, and FIG. FIG. 5 is an explanatory diagram of each display mode example of the display device 7, and FIG. 5 is a flowchart showing an example of a program for obtaining the ratio β of the built-in weight mass W ₀ or the mass to the balance weight. 1 …… Force detector 11 …… Plate 12 …… Force sensor 2 …… Built-in weight 5 …… Microcomputer 51 …… CPU 52 …… R ₀ M 53 …… RAM 54 …… Nonvolatile RAM 6 …… Weight addition / removal Mechanism 7 ... Display 8 ... Mode selection switch

Claims (1)

[Claims] 1. An output from a force detector is converted into a mass and displayed on a display by calculation by a converting means using a calibration coefficient in a coefficient memory, and a weight adding / removing mechanism is used for the force detector. Built-in calibration weight that can be loaded / disengaged freely,
From the contents of the calibration mass memory that stores the mass W _{0 of the} built-in weight or the ratio β of the mass W ₀ to the weighing capacity of the balance, the output of the force detector when the built-in weight is loaded, and the calibration mass memory. In a balance equipped with coefficient updating means for calculating a calibration coefficient and updating the contents of the coefficient memory, the mass W _{0 of the} built-in weight is set to a value different from the weighing capacity of the balance, and when the built-in weight is loaded, Using the mass measurement result and the contents of the calibration mass memory, the calculation means for calculating the span change amount δ when a mass equal to the weighing capacity of the balance is loaded, and the value δ for calculating the span change amount δ. An electronic balance with a built-in calibration weight is also provided with display control means for displaying a symbol indicating a span change on the display.