JPS61162719A - Electronic balance scale - Google Patents

Abstract

PURPOSE:To eliminate the need for adjustment of a calibrating weight itself, by memorizing the value of the calibrating weight including instrumental error into an electronic balance scale to correct the instrumental error thereof. CONSTITUTION:When calibrating an electronic balance scale, first, a signal without the calibrating weight applied as load is converted into a digital signal Q0 with an A/D converter 2 to be stored into a RAM9 as digital data. Then, the calibrating weight with the value known as T0 is applied as load and a digital signal herein obtained is stored into the RAM9 as digital signal QN. A correction value is set from said data Q0 and QN and the value T0 previously inputted. For example, when a load is applied on a load measuring mechanism 1 of the balance scale, the data outputted through the A/D converter 2 is corrected to be outputted on a display 4.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electronic balance, and more particularly to an electronic balance capable of correcting instrumental errors in calibration weights during calibration.

<Prior Art and its Problems> For example, even in the case of an electromagnetic force recovery type electronic balance, it is necessary to periodically calibrate the electronic balance so that the indicated value of the electronic balance can be accurately indicated. Calibration is carried out using calibration weights in the following manner.

FIG. 1 is a system block diagram of a conventional electronic balance. An example in which calibration is performed using a calibration weight having a mass M (g) will be described below. However, the instrumental error of the calibration weight shall be ±N%. Reference numeral 1 in the figure is a load measuring mechanism incorporating a servo loose that balances the electromagnetic force with respect to the applied load. The signal emitted from this servo system is transferred to a converter 2 such as an A/D converter.
The digital signal is input to the control section 3 as a digital signal, and is calculated based on requested processing conditions such as tare cancellation memory, averaging, etc., and the result is output to the display section 4.

In this device, first, when no load is applied to the calibration weight, digital data Po is output from the load measuring mechanism 1 to the control section 3. Next, when the calibration weight is applied as a load, the load measuring mechanism 1 outputs digital data PN. In the control unit 3, this data PM and 0
The difference PN-Po from the data Po during loading is the mass M (g
) is processed as digital data. Here, the digital data of the instrumental error of the calibration weight is the digital data of M (g). Here, the instrumental error of a weight is the value obtained by subtracting the true mass from the indicated mass of the weight, so the instrumental error should be as close to 0 as possible, and the calibration weight should be adjusted as far as possible.
It is necessary to match M (g).

However, it is virtually impossible to eliminate the instrumental error of the calibration weight, and since the instrumental error of the calibration weight itself changes due to aging, it is necessary to take measures to deal with this. That is, in order to bring the mass of the calibration weight close to M (g), it is necessary to fine-tune the calibration weight or readjust it in response to changes over time. Naturally, this work must be carried out as a preliminary step to calibrating the balance, but fine-tuning the calibration weight is a very precise work that imposes a heavy burden on the operator.

<Object of the present invention> The present invention was constructed in view of the above-mentioned needs, and provides an electronic balance that has a function of correcting the instrumental error of the calibration weight and can eliminate the need for adjusting the calibration weight. The purpose is to provide.

<Example> Examples of the present invention will be described below.

In Fig. 2, numeral 1 is a load measuring mechanism, 2 is a fitted converter, 3 is a control section, 4 is a display that displays the signal output from the control section 3, and 5 is a calibration weight to be subjected to comparison calculations. This is an input device for inputting a value To (described later). Further, 7 is a CPU (central processing unit f*), 8 is a read-only memory (ROM), 9 is a random access memory (RAM), and 10 is an MNOS, a MAO
8, non-volatile memory such as FAMO8.

In the apparatus having the above configuration, first, the value TO of the calibration weight taking into account the instrumental error is inputted from the input device 5.

An n series of switches is suitable as this input device. For example, if there are 5 consecutive letters, 2' = 32, and 32 letters can be set.

The value TO input as described above is output to the display device 4 and displayed, and is also stored in the non-volatile memo IJ 10. In this state, the electronic balance can be calibrated. In other words, when calibrating an electronic balance, first calculate the signal when no calibration weight is applied as a load.
The Φ converter 2 generates a digital signal QO, and this data is stored in the RAM 9 as digital data. next,
The value is T.

A known calibration weight is added as a load, and the digital signal at that time is stored in the 5RAM 9 as a digital signal QN.

The following correction values are set from the above data QO, QN and the calibration weight value TO inputted in advance.

Here, QN -QO is the value of the calibration weight displayed by the balance, and To is the true value of this calibration weight, so the above equation (2) is an expression based on the instrumental error of this balance. This is a correction value that corrects the error. For example, when a load is applied to the load measuring mechanism l of this balance, the Ql outputted through the AID converter 2 and obtained by this process is
is a value corrected to the correct fR bone of the load, and outputs this Q+ to the display 4.

The contents are saved even if the power is turned off because they are stored in physical memory. Therefore, there is no need to perform instrumental error correction of the calibration weight or calibrate the balance again when the power is turned on. Also, regarding the aging change in the instrumental error of the calibration weight, calibrate the aging calibration weight with a weight with a clear instrumental error and find out the value T1.
Further, by calibrating the balance using a calibration weight of value T+, the correction values IQ, N' -Q, are obtained.

You can freely respond to your requests. By the way, 0, N
/ is a digital signal of the balance when a calibration weight having a value of T1 is applied as a load.

Effect> According to the present invention, by storing the value of the calibration weight including the instrumental error in the electronic balance, the instrumental error of the calibration weight can be corrected.
The mass of the weight itself does not necessarily need to be set to a constant value (M), and as a result, adjustment of the calibration weight itself, especially adjustment for aging, becomes unnecessary.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional electronic balance, and FIG. 2 is a circuit diagram of an electronic balance showing an embodiment of the present invention. l os/Load measurement mechanism 3...Control unit 4...Display device 5...Input device 10...Non-volatile memory Figure 1 Figure 2 Procedure amendment February 2, 1986

Claims (1)

[Claims] 1. In a device in which the data of the load applied to the load measuring mechanism is calculated in the control unit and the calculation result is displayed on the display device, the value of the calibration weight taking into account the instrumental error is stored in the control unit. A memory mechanism that stores the values stored in the memory mechanism, a memory mechanism that inputs the results of balance calibration using a calibration weight whose values are stored in this memory mechanism, and a memory mechanism that inputs the results of balance calibration using the values of the calibration weights and the balance calibration results. An electronic balance characterized in that it is equipped with a calculation mechanism that calculates a correction value for correcting display errors. 2. If the value of the calibration weight taking into account the instrumental error is T_O, the digital signal when this calibration weight is applied as a weight to the load measuring mechanism is Q_N, and the digital signal when no load is applied is Q_O, then the above 2. The electronic balance according to claim 1, wherein the arithmetic mechanism is configured to set the correction value as T_O/(Q_N-Q_O). 3. The electronic balance according to claim 1 or 2, characterized in that the memory mechanism for storing the value of the calibration weight and the correction value taking into account instrumental error is constituted by a non-volatile memory.