JPH0219415B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic sensitivity correction device for a measuring device that measures various quantities such as weight, length, and flow rate.

A measuring device, such as a weight measuring device, generally includes a weighing pan 1 on which an object to be weighed is placed, a weighing device 2 that outputs a weighing signal, and an A/D converter that converts the output of the weighing device 2 into a digital signal, as shown in FIG. A D converter 3, a zero point hold circuit 4 that holds the output value of the weighing instrument 2 when the weighing pan 1 is empty, and a weighing output of the weighing instrument 2 when the object to be weighed W is placed on the weighing pan 1. It is equipped with a subtracter 5 for subtracting the zero point hold value held in the zero point hold circuit 4 from The weight of the object to be weighed is measured by subtracting the zero point hold value (tare weight) from the output of the measuring instrument when the object is placed on the weighing pan 1 using a subtractor 5. In such a weight measuring device, since measurement sensitivity changes with the passage of time or temperature change, an automatic sensitivity correction device 6 is provided to detect and set the measurement sensitivity arbitrarily.

In FIG. 1, reference numeral 6 indicates a conventional automatic sensitivity correction device. That is, the conventional automatic sensitivity correction device 6 includes a reference amount setter 7 for setting the true weight and a multiplication factor value (measured value) by dividing the reference weight output from the reference amount setting device 7 by the output value of the subtractor 5. a sensitivity hold circuit 9 that holds the multiplication factor value output from the divider 8, and a sensitivity hold circuit that holds the output value of the subtracter 5 when the object to be measured is placed on the weighing pan 1. 9 by a held multiplication factor and a multiplier 10 for outputting the result as a measured value. To newly set the multiplication factor for sensitivity correction, as in the case of weighing the object to be weighed, after emptying the weighing pan 1 and holding the zero point,
The reference weight 11 is placed on the empty weighing pan 1 by the reference weight drive device 12, and the measured value from the measuring instrument 2 is subtracted by the hold value of the zero point hold circuit 4 using the subtractor 5. Obtain the weight Wo′ of
The divider 8 divides the reference weight value Wo output from the reference amount setter 7 by the actual measurement value Wo' of the subtracter 5 (multiplying rate) Wo/Wo', which is calculated by the sensitivity hold circuit 9.
Holds on. Then, the multiplication factor set in this way is applied to the subtractor 5 when measuring the weight of the object to be measured.
By multiplying the output value by the multiplier 10, a sensitivity-corrected weight value output is obtained.

However, in the conventional automatic sensitivity correction device, the object to be weighed must be removed and emptied from the weighing pan 1 each time the sensitivity is set, making the sensitivity setting very complicated and time consuming.

In particular, in recent years, objects to be weighed are sequentially supplied to a large number of weighing hoppers, the weight of the objects in each weighing hopper is measured using a weighing device installed in each weighing hopper, and the weight of an arbitrary combination of each measurement value is calculated. Combination weighing machines that select the combination that is closest to the target weight are becoming popular, but in devices like this that have a large number of weighing devices, each weighing hopper must be emptied each time the sensitivity is set, and combination weighing must be interrupted each time. This has been a major hindrance to the high-speed operation of combination weighing machines.

SUMMARY OF THE INVENTION An object of the present invention is to correct the above-mentioned drawbacks and provide an automatic sensitivity correction device that can perform sensitivity setting without removing the object to be measured from the measurement position.

Embodiments of the present invention will be described below based on the drawings.

FIG. 2 shows a block diagram of a weight measuring device equipped with an automatic sensitivity correction device according to an embodiment of the present invention.

In Figure 2, 1 is a weighing pan, 2 is a scale, and 3 is a weighing pan.
1 is an A/D converter, 4 is a zero point hold circuit, 5 is a subtracter, 11 is a reference weight, and 12 is a reference weight driver, which are the same as those shown in FIG.

The automatic sensitivity correction device 20 includes a measured value hold circuit 21 that holds the output value of the subtracter 5 when the object W to be weighed is placed on the weighing pan 1 (timing TM1).
When the reference weight 11 is further added to the weighing pan 1 by the reference weight drive device 12 (timing
a subtracter 22 that subtracts the hold value of the measured value hold circuit 21 from the output value of the subtracter 5 of TM2);
, a reference amount setter 23 that sets the true weight of the reference weight 11, and a divider 24 that divides the reference weight output from the reference amount setter 23 by the output value of the subtracter 22 and outputs a multiplication factor. , a sensitivity hold circuit 25 that holds the multiplication rate from the divider 24, and a multiplier that multiplies the output value of the sensitivity hold circuit 25 by the output value of the subtracter 5 when only the object W to be weighed is placed on the weighing pan 1. 26.

Next, the operation of the above embodiment will be explained.

To weigh the object, place the object on the weighing pan 1.
The hold value (tare weight) held in the zero point hold circuit 4 is subtracted by the subtractor 5 from the measurement signal of the measuring instrument 2 which has passed through the A/D converter 3 when the weight is placed on the
A multiplier 26 multiplies the output value of the subtracter 5 by the multiplication factor held in the sensitivity hold circuit 25 and outputs the result.

However, when setting a new sensitivity,
With the object to be weighed W placed on the weighing pan 1, the output value of the subtracter 5 (i.e., the weighing measurement value W' obtained by subtracting the zero point hold value) is held in the measurement value hold circuit 21 in response to the timing signal TM1, and then the reference weight is Operate the drive device 12 to move the reference weight 11 to the weighing pan 1.
, and at timing TM2, the measured value is held from the output value W _T ′ of the subtracter 5 (weighing measurement value W ′ + Wo′ obtained by subtracting the zero point hold value from the combined value of both the object to be measured W and the reference weight 11). The value obtained by subtracting the value W′ held in the circuit 21 (W′+
Outputs Wo′−W′=Wo′). The divider 24 divides the reference weight value Wo output from the reference amount setter 23 by the output value Wo' of the subtracter 22 to obtain a multiplication rate Wo/
Wo' is output, and the sensitivity hold circuit 25 holds the new multiplication factor Wo/Wo'. When the sensitivity setting is completed in this way, the reference weight 11 is removed by the reference weight drive device 12, the normal weighing operation is resumed, and the sensitivity hold is applied to the measured value output from the subtractor 5 in subsequent measurements. The circuit 25 is multiplied by the newly set multiplication factor.

In this way, the automatic sensitivity correction device 2 of the above embodiment
According to 0, if the reference weight 11 is additionally placed on the weighing pan 1 while the object to be weighed remains on the weighing pan 1, the divider 24 outputs the multiplication factor Wo/Wo' and the sensitivity is set. Become.

In the above embodiment, the measured value hold circuit 21 and the subtracter 22 of the automatic sensitivity correction device 20 are replaced by the subtracter 5.
Although it is connected to the output of the A/D converter 3, it may be connected to the output of the A/D converter 3 as shown in FIG. Even in this case, the reference weight 1 is output from the subtracter 22.
Since the metric measurement value Wo' of 1 is obtained, the result is the same as in the case of FIG.

In addition, although the above embodiment describes an example in which the present invention is applied to a weight measuring device, the present invention is not limited to simply a weight measuring device; for example,
The present invention can be similarly applied to devices for measuring other quantities such as length or flow rate, and when sensitivity correction is performed using various quantity standards such as reference length or reference flow rate.

As is clear from the above explanation, the automatic sensitivity correction device of the present invention stores a measurement signal when an object to be measured is loaded, and stores a measured value when the object to be measured and various quantity standards are combined. Since the sensitivity is calculated based on the result of subtraction with the value and the reference amount of various quantity standards, the sensitivity can be corrected while the measuring device is loaded with the object to be measured. Therefore, there is no need to remove each object to be measured for sensitivity correction, and it is possible to perform correction operations quickly and easily while continuing measurement operations. This is particularly effective for devices using measuring instruments. Also, in general, measuring equipment
In many cases, actual measured values cannot be obtained as a linear relationship in a wide measurement range, but even in such cases, the device of the present invention provides a relationship between two nearby points (the measurement point of the object to be measured and the reference value at this measurement point). Since the sensitivity is calculated at the measurement point (added measurement point), accurate sensitivity can be obtained.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a weight measuring device to which a conventional automatic sensitivity correction device is applied, Fig. 2 is a block diagram showing a weight measuring device to which an automatic sensitivity correction device according to an embodiment of the present invention is applied, and Fig. 3 FIG. 2 is a block diagram showing a weight measuring device to which an automatic sensitivity correction device according to another embodiment of the present invention is applied. 1...Weighing pan, 2...Measuring instrument, 3...A/D converter, 4...Zero point hold circuit, 5...Subtractor,
6... Automatic sensitivity correction device, 7... Reference amount setting device,
8...Divider, 9...Sensitivity hold circuit, 10...
... Multiplier, 11 ... Reference weight, 12 ... Reference weight drive device, 20 ... Sensitivity automatic correction device, 21 ...
Measured value hold circuit, 22... Subtractor, 23...
Reference amount setter, 24...divider, 25...sensitivity hold circuit, 26...multiplier.

Claims (1)

[Scope of Claims] 1. Measured value storage means for storing measured values W' output from the measuring means corresponding to various quantities of an arbitrary measured object, and a reference quantity for storing a reference quantity Wo of various quantity standards. storage means; and the arbitrary measured value stored in the measured value storage means from a measurement value W _T ' obtained by measuring the total amount of the arbitrary measured object and the various quantity standards by the measuring means. calculation means for calculating a measurement sensitivity value by subtracting a measured value W' of an object and dividing a reference quantity (Wo) stored in the reference quantity storage means by the subtracted value; and storing the measurement excess value. and a multiplication means for multiplying the measurement values output from the measurement means corresponding to various quantities of the object to be measured by the measurement sensitivity value stored in the sensitivity storage means. Automatic sensitivity correction device.