JPH0228516A - Reference point correcting device - Google Patents

Abstract

PURPOSE:To eliminate a measurement error by dividing a difference of reference values outputted from the 1st subtracting circuit by the value of an elapsing time difference and multiplying a change degree of the reference values which is stored in a storage circuit for the change degree of the reference values by the value of the elapsing time difference. CONSTITUTION:A temperature value A1 which is obtained from a temperature sensor 17 and held 18, is stored in the storage circuit 19 for the former temperatures, and the temperature value A2 obtained from the sensor 17 after elapsing a specified time is held 18, and the temperature difference A2-A1 is outputted from the subtracting circuit 21. If outputs from a metering device 12 without any object placed on the metering plate at the temperatures A1, A2 are expressed as Z1, Z2, the difference between Z2 held 13 for a zero-point and Z1 stored 14 for the former zero-point, that is, Z2-Z1 is outputted from the subtracting circuit 16. Next, (Z2-Z1)/(A2-A1) is outputted from a dividing circuit 22, and this value is set 23 and outputted to an adding circuit 26 through a multiplying circuit 26. In the circuit 26, outputs from the zero-point hold circuit 13 and the circuit 25 are added, and this value is subtracted 27 from the output value of the metering device 12 which is the value in case the object to be measured is placed on the weighing plate 11, then outputted to a display circuit 28 as a signal to indicate the weight.

Description

[Detailed Description of the Invention] The present invention! It relates to a reference point correction device for a measuring device that measures each position such as flow length, length, etc.

In measuring devices that measure weight, flow rate, length, etc. with high precision, the reference point (for example, zero point) often fluctuates over time, causing deterioration in measurement accuracy.

For this reason, conventionally, the zero point is measured at regular intervals, the reference point is updated and stored in the zero point memory circuit 1, and the zero point is subtracted from the measurement signal (weighing signal) of the measuring instrument (for example, a scale) 2 by the subtraction circuit 3. ing.

However, in this method, when the zero point changes with temperature change as shown in FIG. , A”C1A between A2 and A3
``An error EE n occurs at ℃. Therefore, in order to reduce such F14 difference, it is necessary to measure and update the zero point for every small temperature change as much as possible. In a measuring device that continuously measures an object, the continuous supply of the object to be measured is often interrupted for zero point measurement, which hinders high-speed measurement.

It is an object of the present invention to correct the above-mentioned drawbacks and provide a reference point correction device in which almost no W4 difference occurs even if the measurement of the reference point is not performed in small increments as described above.

Hereinafter, one embodiment of the present invention will be described based on the drawings. For convenience of explanation, the measured value measured under a constant load condition will correspond to the reference point, and the measured value measured under no load condition will be corresponded to the zero point.Hereafter, this zero point will be used. explain.

FIG. 3 is a block diagram showing an embodiment of the present invention applied to a meter I device.

In Fig. 3, 11 is a weighing plate for placing the object to be measured, 12 is a measuring device, and 13 is a device that memorizes the zero point of the measuring device 12 when measuring the zero point with the weighing plate empty, and holds the zero point signal. This is a zero point hold circuit. 14 is a mouth point memory circuit that stores the zero point signal held in the zero point hold circuit 13 when the switch 15 is closed; and 16 is a zero point signal held in the zero point hold circuit 13 that is stored in the mouth point memory circuit 14. This is a subtraction circuit that subtracts the mouth weight.

17 is a temperature sensor that outputs a signal corresponding to the ambient temperature of the measuring instrument 12, and 18 is a temperature hold circuit that holds the temperature signal from the temperature sensor 17. 19 is switch 2
A mouth temperature memory circuit 21 stores the temperature signal held in the temperature hold circuit 18 when the switch 0 is closed in synchronization with the switch 15; a mouth temperature memory circuit 21 stores the temperature signal held in the temperature hold circuit 18; This is a subtraction circuit that subtracts the stored mouth temperature.

22 is a division function that calculates the zero point change degree per 1°C by dividing the difference between the new zero point output from the subtraction circuit 16 and the mouth temperature by the difference between the new temperature output from the subtraction circuit 21 and the mouth temperature. It is a circuit. 23, switch 24 is switch 15 and 2o
25 is a zero point change storage circuit that stores the output signal (zero point change degree) of the divider circuit 22 when it is closed before it is synchronously closed; This is a multiplication circuit that multiplies the temperature by the difference between the temperature in Niigata and the mouth temperature output from the subtraction circuit 21.

26 is an addition circuit that adds the output value of the multiplication circuit 25 to the zero point held in the zero point hold circuit 13, and 27 is a zero point correction by subtracting the output value of the addition circuit 26 from the measurement signal output from the measuring instrument 12. A subtraction circuit 28 is a display circuit that displays the weight of the object to be measured based on the output signal of the subtraction circuit 27.

Switches 15, 20, 24 each receive a timing signal T
It is closed by I, T2, and Ts. FIG. 4 shows the relationship between the timing signals Ts, T2, Ts and the intervening timing signal To.

Next, the operation of zero point correction according to the above embodiment will be explained.

The zero point change degree is set in the zero point change degree storage circuit 23 as follows.

That is, first, the weighing pan 11 is emptied, and the measuring instrument 12 at this time is
For example, the output value (zero point) of the timing To shown in FIG.
, and the zero point hold circuit 13 holds it. Assume that the zero point changes as the temperature changes, as shown in FIG. 5, and that the temperature at the time of zero point measurement is 81° C. and the output value (zero point) of the measuring instrument 12 is 71. switch 1
5 and 20 are temporarily closed synchronously, the zero point Z1 held in the zero point hold circuit 13 is stored in the mouth point memory circuit 14, and the zero point Z1 held in the zero point hold circuit 13 is stored in the mouth point memory circuit 14, and the zero point Z1 held in the temperature hold circuit 18 is The temperature value A1°C is stored in the mouth temperature storage circuit 19.

Next, after a predetermined period of time has elapsed, the weighing pan 11 is emptied again, and the output value (zero point) from the measuring instrument 12 is held in the zero point hold circuit 13. As shown in Figure 5, the temperature at this time is A2
Assuming that the output value (zero point) of the measuring instrument 12 is 72 degrees Celsius, the temperature value A2 degrees Celsius from the temperature sensor 17 is held in the temperature hold circuit 18 at this time. Therefore, the subtraction circuit 16 outputs the difference Z2-Zs between the zero point z2 held in the zero point hold circuit 13 and the mouth point 21 stored in the mouth point storage circuit 14. On the other hand, the subtraction circuit 21 outputs the difference A2-Ax between the temperature A2°C held in the temperature hold circuit 18 and the mouth temperature A1°C.
2 calculates (Zz-Xs)/(A2-Al).

When the switch 24 is temporarily closed by the timing signal T3, the division times! 22(7) ffl force 1 (Zt −Z
t)/(A2-As) is zero point change degree storage circuit 2
3 is stored. Timing signals Ts and T2 are output immediately after timing signal T3, and switches 15 and 2
0 is temporarily closed in synchronization, the zero point Z2 held in the zero point hold circuit 13 is stored in the mouth point storage circuit 14 instead of 71, and the temperature value A2 held in the temperature hold circuit 18 is stored in the mouth temperature storage circuit. 19 instead of A1.

The zero point change degree (Zt-Zt)/(A2-At) obtained by measuring the new zero point (z2) in this way is set in the zero point change degree storage circuit 23 and output to the multiplication circuit 25. Then, in the subsequent measurement of the object to be measured, while the temperature does not change from the temperature A2 at the time of measurement at zero point z2, A2°C is held in the temperature hold circuit 18, and A2°C is also stored in the mouth temperature storage circuit 19. Therefore, the output value of the subtraction circuit 21 is A2-At = 0, so the output value of the multiplication circuit 25 is ((Zt - Zt)/(A2-A
1))×0-0. Therefore, the output value of the adder circuit 26 is the output value z2 of the zero point hold circuit 13 and the multiplier circuit 25 (
F) ffl force 1i (value added by l = 22 + 0 = 22. Then, this value Z2 is subtracted by the subtraction circuit 27 from the output value of the scale 12 when the object to be measured is placed on the weighing pan 11. It is output to the display circuit 28 as a signal representing IM.

If the temperature rises from A2°C to A''C, the temperature hold circuit 18 outputs A', so the subtraction circuit 21 outputs (A' - A2) to the multiplication circuit 25.
Output to. Therefore, the multiplier circuit 25 or 134t ((
Zt-Zx )/<A2-Al))X (A'-
A2) is output. As shown in Figure 5, (Zt-Z
x )/(A2-As) represents the slope of the straight line connecting point P and point Q, so ((Za-Zl)/
(A2-AI))
It represents the length RV of the straight line connecting the vertical line passing through ' and the intersection (2).

Therefore, the addition circuit 26 outputs an addition result 2' obtained by adding the length RV to the output value z2 of the zero point hold circuit 13. For this reason, in the past, the previously measured zero point z2 was output as the zero point, but Z2, which follows the actual change in the zero point, is
' will be output as a zero point.

Also, when the temperature drops below A2°C, for example, A"°C,
Since the reduction circuit 21 takes a negative value (A"-A2), the output value of the multiplier circuit 25 ((Zt-Zt)/(A2-
At > ) X (A"=A2) is a negative value,
The adder circuit 26 outputs a value of 2'', which is lower than z2.

In this way, according to this circuit, the slope of the zero point change is set by the two zero point measurements, the previous one and the one before the previous one, and the zero point that follows the temperature change and has a small difference in W+ is output from the correction circuit 26.

Then, if the next zero point measurement is performed and the zero point is 73 at A3°C, the zero point change degree storage circuit 23k is
l: C (Za - Zz) / (A3 - A2) is stored, A3°C is stored in the mouth temperature storage circuit 19, and a multiplication circuit follows the temperature change based on the slope of the straight line connecting R and W. The output value of 25 is added to Za by an adder circuit 26.

In the above embodiment, the case where the zero point correction is performed based on temperature change has been described, but if the zero point changes over time, the correction may be performed based on the number of measurements. That is, in this case, as shown in FIG. 6, a counter 3 for counting the number of weight measurements is used.
1 is stored in the old number storage circuit 33 via the switch 32, the output Bj of the counter 31 from the previous zero point measurement is stored in the old number storage circuit 33, and the output Bj of the counter 31 from the previous zero point measurement is stored in the old number storage circuit 33. Difference with output B2 (82-81
) is output from the subtraction circuit 21. Assuming that the zero point of the previous measurement is Zx and the zero point of the previous measurement is 72, the division circuit 22 outputs (Zt-Zt)/(B2-Bs), and this value is set in the zero point change degree storage circuit 23, and the zero point of the previous measurement is B2 is stored in the number of times storage circuit 33.

Therefore, in subsequent weighing measurements, the zero point change degree storage circuit 23
The value set in Z2 is multiplied by the value obtained by dividing the number of subsequent weighing measurements by 82 and added to Z2 by the addition circuit 26.

In the above embodiment, a case has been described in which the zero point correction is performed using the zero point change degree, but if the zero point correction is performed using the zero point change degree, even more accurate zero point correction can be achieved.

FIG. 8 is a block diagram showing the case of such zero point correction,
FIG. 9 shows timing signals To, Tt, Tt, Ts,
The relationship of T4 is shown. In Figure 8, subtraction circuit 16 and division circuit 2
2, the switch 24, the zero point change degree storage circuit 23, the subtraction circuit 41 having the same configuration and the same function as the multiplication circuit 25, the division circuit 842, the switch 43, the zero point change degree storage circuit 44, the multiplication circuit 1! By providing I45, zero point correction can be performed using the degree of change in zero point change. Since these details are clear from the above description, detailed description thereof will be omitted.

In the above embodiment, the case of a weight measuring device was explained, but it goes without saying that the present invention can also be applied to a device for measuring length, flow rate, etc.

As explained above, in the reference point correction device of the present invention, the reference point is corrected by automatically changing it according to the temperature change or the number of measurements. : Measurement errors can be eliminated without performing am determination in small steps.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a conventional zero point correction device, Fig. 2 is a graph showing an example of zero point fluctuation due to temperature, Fig. 3 is a block diagram showing an embodiment of the present invention, and Fig. 4 is a timing signal. FIG. 5 is a time chart showing a club for explaining the principle of zero point correction according to an embodiment of the present invention, and FIG.
The figure is a block diagram showing another embodiment of the present invention, and FIG. 7 is a graph for explaining the principle of sensitivity correction in the embodiment shown in FIG. FIG. 8 is a block diagram showing still another embodiment of the present invention, and FIG. 9 is a time chart showing timing signals. 1...Zero point memory circuit, 2...Measuring instrument,
3...Subtraction circuit, 11...1 scale, 1
2...Weighing! , 13... Zero point hold circuit, 14... Mouth point memory circuit, 15...
...Switch, 16...Subtraction circuit, 17-
-----Temperature sensor, 18...Temperature hold circuit, 19...Mouth temperature storage circuit, 20...
...Switch, 21---- Subtraction circuit, 22...
. . . Division circuit, 23 . . . ° Zero point change degree storage circuit, 24 . . . Switch, 25 . . . Multiplication circuit, 26 . . . Addition circuit, 27 ...Subtraction circuit, 28...Display circuit, 31...
Counter, 32...Switch, 33...
・Old number of times memory circuit. Patent Applicant Anritsu Corporation Agent Patent Attorney Makoto Hayakawa

Claims (1)

[Scope of Claims] A reference value storage circuit that stores measured values when an object to be measured is measured under a constant load condition; a first subtraction circuit that calculates a difference between the measured value of the object under load and a measured value; a division circuit that divides the difference between the reference values output from the first subtraction circuit by an elapsed time difference value; a reference value variation storage circuit that stores the output value of the division circuit; a multiplication circuit that multiplies the reference value variation stored in the reference value variation storage circuit by an elapsed time difference value; A reference point correction device comprising: an addition circuit that adds to a reference value stored in a reference value storage circuit; and a second subtraction circuit that corrects the reference value by subtracting an output value of the addition circuit from the measured value.