JPH0216457B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic correction device that automatically corrects the zero point and sensitivity of various measuring devices such as weight, length, flow rate, etc.

In a conventional measuring device, for example, a weight measuring device, the zero point is manually adjusted, then a reference weight (for example, 1 kg) is placed on the measuring pan, and the pointer or digital indication is manually adjusted so that it is 1 kg. I was making corrections. Then, as the range increased, corrections had to be made again accordingly.
That is, when attempting to measure 10 kg or more in the above manner, it was necessary to place 10 kg as a reference weight on the measurement pan, make corrections, and then measure the weight of the object to be measured.

In view of the above-mentioned points, this invention automatically corrects the measuring device by simply inputting a reference value, that is, in the case of a weight measuring device, by simply placing the reference weight on the measuring pan. This is how it was done. The invention will be explained below with reference to the drawings.

The drawing is a block diagram showing one embodiment of the present invention, and shows a weight measuring device.

In this figure, reference numeral 1 denotes a measuring plate on which a reference weight or an object to be measured is placed. 2 is a transducer that measures the amount of vertical displacement of the measuring plate 1 (proportional to the weight)
Outputs the voltage value according to. 3 is an AD converter,
The analog value of transducer 2 is converted into a digital value. 4 is a zero point hold circuit, and measuring plate 1
Hold timing when nothing is placed on
At TM ₁ , the output value of AD converter 3 is held. 5 is a subtracter that calculates the output value of AD converter 3 and
Subtraction with the hold value of the zero point hold circuit 4 is performed. 6 is a multiplier, and the multiplication rate (input value voltage A
The ratio between the subtracter 5 and the voltage B which is the output value) α=B/A can be varied, and the output of the subtracter 5 is multiplied by an appropriate value α and output. 7 is an output terminal. 8 is a reference value generation circuit, and if it is a 1Kg range,
Generates “1000”. A comparator 9 calculates the ratio between the output of the multiplier 6 and the reference value from the reference value generation circuit 8 and outputs the ratio. 10 is a sensitivity hold circuit, which indicates the hold timing when the reference weight is placed on the measuring plate 1.
At TM ₂ , hold the output value of comparator 9,
This value controls the multiplication rate of the multiplier 6.

Next, the basic operating principle will be explained.

First, at hold timing TM ₁ when nothing is placed on the measuring pan 1, the weight of the measuring pan 1 or the sum of the weights of the measuring pan 1 and the container when an empty container is placed on the transducer. 2 is output as an analog value, and the value is inputted to the zero point hold circuit 4 as a digital value by the AD converter 3. This digital value is the so-called tare weight, and is expressed as _M1 . In this way, the tare weight _M1 is held in the zero point hold circuit 4 at the hold timing _TM1 .

Next, at hold timing _TM2 , an object having a reference weight _Ws , such as a weight, is placed on the measuring pan 1. If the output value of the AD converter 3 at this time is _M2 , the subtracter 5 performs the calculation ( _M2 - _M1 ) and outputs this value, that is, a value corresponding to the reference weight. On the other hand, the reference value generation circuit 8 has a reference weight
The value of W _{s is set according to W s .} If the multiplication rate of the multiplier 6 is 1, that is,
The output value of the subtractor 5 appears as it is at the output terminal 7, but this output value enters the comparator 9 and is calculated as the reference weight.
It is compared with W _s to determine the ratio between the two, that is, the multiplication factor α, and this is held in the sensitivity hold circuit 10. Thereafter, at measurement timing _TM3 , the multiplier 6 operates at the multiplication rate α.

To explain with a specific example, in the case of the reference weight _Ws of 1 kg, the set value of the reference value generation circuit 8 is set to "1000". Assuming that the output value of the subtracter 5 is "2000" and the multiplication rate α of the multiplier 6 is "1", then
The output value of the output terminal 7 is "2000", so the output value of the comparator 9, that is, the multiplication factor α is "1/2", and this is the output value of the sensitivity hold circuit 10.
is held at TM ₂ , and at the subsequent measurement timing TM ₃ , the multiplication rate α of the multiplier 6 is “1/2”.
It works as.

At measurement timing _TM3 , the weight of the object to be measured is accurately output to the output terminal 7 simply by placing the object on the measurement plate 1. Note that the displayed portion is omitted in the figure.

When measuring objects with different weights, for example, on the order of 10 kg, the reference weight W _s may be corrected in advance to 10 kg and then measured.

The above is the operating principle of this invention. Next, other embodiments of this invention will be described. The multiplier 6 has a multiplication rate α that changes depending on the voltage at the input terminal 6a. Comparator 9 compares voltage B at output terminal 7 with output voltage C from reference value generation circuit 8, and outputs a positive voltage when voltage B is small and a negative voltage when it is large.
The sensitivity hold circuit 10 includes an integrating circuit,
The output voltage of the comparator 9 is integrated at the rising edge of the hold timing _TM2 , and the value is held at the falling edge and applied to the input terminal 6a of the multiplier 6. Now 1Kg
In the case of the reference weight _Ws , it is assumed that the voltage C is "1000" and the voltage B is "2000". hold timing
At the rising edge of _TM2 , the sensitivity hold circuit 10 is released from holding and performs an integrating operation. At this time, voltage B
>voltage C, the comparator 9 is outputting a negative voltage, so the output voltage of the integrating circuit decreases, and the multiplication factor α of the multiplier 6 decreases accordingly. When voltage B becomes equal to voltage C, comparator 9
becomes a zero signal, and the output of the integrating circuit stops changing. Next, at the fall of the hold timing _TM2 , the output of the integrating circuit is held, and the multiplication factor α of the multiplier 6 maintains its value. After the sensitivity calibration is completed in this way, the operation is similar to the measurement described above.

Although the above embodiment has been explained using a weight measuring device as an example, it goes without saying that the present invention can be applied to various other measuring devices such as length, flow rate, temperature, etc. Further, the present invention is not limited to digital values, but may be analog values.

As explained above, the present invention includes a reference value generation circuit that generates a reference value, an output value obtained at the output terminal when the reference amount acts on a transducer, and a reference amount from the reference value generation circuit. A comparator that continues to output a negative or positive output depending on the magnitude of the output value of the output terminal with respect to the reference amount until the two match, and a comparator that integrates the negative or positive output of this comparator. It consists of a sensitivity hold circuit that changes a multiplication rate, holds a multiplication rate obtained when the output value of the output terminal with respect to the reference amount matches the reference value, and operates the multiplier at the multiplication rate at the measurement timing. Therefore, not only can the measuring device be corrected by simply inputting the reference amount to the transducer before measurement and inputting the reference value corresponding to this reference amount to the comparator, but the comparator can also perform multiplication using the multiplier. The multiplier precision can be ignored since the output is compared with the reference value. Further, since the sensitivity hold circuit integrates the output of the comparator to determine the multiplication rate, the measured values of the measuring device are averaged, which has the advantage of improving sensitivity adjustment accuracy.

[Brief explanation of drawings]

The drawing is a block diagram showing one embodiment of the present invention. In the figure, 1 is a measurement pan, 2 is a transducer, and 3
is an AD converter, 4 is a zero point hold circuit, 5 is a subtracter, 6 is a multiplier, 7 is an output terminal, 8 is a reference value generation circuit, 9 is a comparator, and 10 is a sensitivity hold circuit.

Claims (1)

[Claims] 1 In a measuring device that outputs a measured quantity from a transducer to an output terminal through a multiplier with a variable multiplication rate, there is a reference value generation circuit that generates a reference value, and a reference value generation circuit that generates a reference value, and when the reference quantity acts on the transducer, The output value obtained at the terminal is compared with the reference value corresponding to the reference amount from the reference value generation circuit, and a negative or positive value is generated depending on the magnitude of the output value of the output terminal with respect to the reference amount until the two match. A comparator that continues to output an output, and a multiplication factor obtained when the output value of the output terminal with respect to the reference amount matches the reference value by integrating the negative or positive output of this comparator and changing the multiplication factor. and a sensitivity hold circuit that holds the multiplier and operates the multiplier at the multiplication rate at the measurement timing.