JPH0124578Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a belt scale totalizer.

Conventionally, as shown in FIG. 1, for example, this type of totalizer detects the instantaneous weight applied to a certain section of a weighing conveyor 2 carrying an object to be weighed 1 using a pressure sensor 3 such as a load cell, and converts it into a load-voltage converter. At the same time, the analog switch receives an analog signal (of voltage or current) proportional to the instantaneous weight output from the pulse generator 4, and receives a pulse signal output from the pulse generator 5 according to the amount of belt movement of the weighing conveyor 2. The instantaneous transport amount is determined by a multiplication circuit 6 using The integrated value is obtained by inputting the signal to a V/F conversion circuit 7 which converts it into a pulse signal with a proportional frequency to form a pulse, and counting this pulse with a counter circuit 8.

However, since the circuit elements that make up a conventional totalizer, such as the multiplier circuit 6 and the V/F conversion circuit 7, mainly perform analog processing, they are affected by external environmental conditions, especially temperature changes, causing voltage and current drift. As a result, an error occurred in the instantaneous weight.
In addition, the power supplied to the power supply circuit 9 is usually shared with other devices in the environment in which the belt scale device is installed, and there are fluctuations in the voltage supplied from the power supply circuit 9 to each circuit, resulting in instantaneous fluctuations. As a result of the error in weight, a considerable error may occur in the integrated value obtained by the counter circuit 8.

In order to accurately measure the instantaneous weight on the conveyor, the number of divisions is increased to reduce the weight value per unit pulse, that is, the number of pulses generated in the V/F conversion circuit 7 is increased based on the output of the scaler circuit 10. However, each time the scale is changed, the pulse height must be corrected according to the weight unit, and this delicate precision directly affects the integrated value.

As described above, conventional totalizers have many drawbacks due to analog processing and problems when aiming for high accuracy. Therefore, the inventor of the present invention conducted repeated research and attempted to switch from the conventional circuit system centered on analog processing to a circuit system centered on digital processing. We have devised a totalizer for belt scales that instantly calculates the integrated value using a calculation circuit, so that the integrated value is not affected by external conditions and allows highly accurate weighing. Its configuration consists of an analog-to-digital conversion circuit that converts an analog signal, which is output in proportion to the instantaneous weight applied over a certain section of the weighing conveyor carrying the object to be weighed, into a digital signal, and an output from this analog-to-digital conversion circuit. a multiplier circuit that multiplies the maximum capacity (scale) data of the flow rate set in advance; a weighting circuit that assigns predetermined weight data to the output of this multiplier circuit; The present invention is characterized by comprising an accumulation circuit that accumulates the outputs of the weighting circuit using the generated pulse signal as a starting signal.

The present invention is based on the above-mentioned totalizer, and in a narrow sense, it is to provide a zero point adjustment device that is compatible with this totalizer, and in a broader sense, it is to provide a belt scale totalizer that is equipped with a zero point adjustment device that is compatible with this totalizer. The purpose is

To summarize the present invention, there is provided a belt movement amount monitoring means for setting the number of pulse signals that can be transmitted for an integer number of rotations of the belt and monitoring until the number of pulse signals inputted when the belt is running idle reaches the number of pulse signals; an accumulating circuit that accumulates the output of the analog-to-digital conversion circuit using the pulse signal as a starting signal until the belt movement amount monitoring means outputs a monitoring completion signal; zero-point weight calculation means for calculating the zero-point weight per pulse signal by having a division circuit that divides the cumulative result of by the set number of pulse signals; and the analog-to-digital conversion based on the output of the zero-point weight calculation means. This totalizer for a belt scale is equipped with a zero point adjustment device, the basic feature of which is a zero point adjustment means for subtracting the zero point weight from the instantaneous weight from the circuit.

Hereinafter, embodiments of the present invention will be described in more detail in terms of the overall structure including the embodiments.

In FIG. 2, the totalizer 20 of one embodiment includes:
The input terminal 21 includes an instantaneous weight input terminal 21 and a belt movement pulse input terminal 22, and the input terminal 21 receives and inputs an analog signal (for example, a voltage signal) proportional to the instantaneous weight applied over a certain section of the weighing conveyor that conveys the object to be weighed. Terminal 22 receives a pulse signal generated in response to the amount of belt movement of the weighing conveyor.

23 converts the analog signal from the instantaneous weight input terminal 21 into a digital signal (for example, a binary code signal).
analog-to-digital conversion circuit for converting into
is a multiplier circuit that multiplies the digital signal from the analog-to-digital conversion circuit 23 by the maximum capacity data of the flow rate set in the scale factor setting device 25, which consists of a switch, and the scale factor is the scale factor in this example. Capacity per hour (t/h
or Kg/h).

Reference numeral 26 denotes a weighting circuit that applies a predetermined weight W to the output of the multiplication circuit 24 to facilitate subsequent calculations; in this example, the multiplication circuit 24
This is a division circuit that divides the output of by a constant K.
Therefore, the constant K corresponds to W=1/K in relation to the weight W.

Reference numeral 27 denotes an accumulation circuit that accumulates the output of the weighting circuit 26 using the pulse signal P ₁ as a starting signal, and the pulse signal P ₁ is a pulse signal received at the belt movement amount pulse input terminal 22 . Reference numeral 28 is a display circuit that converts the accumulation result (binary code format) of the accumulation circuit 27 into a decimal number and displays the total weight of the objects to be weighed conveyed by the conveyor.

Both 29 and 30 are circuits for correcting digital signals from the analog-digital conversion circuit 23, and the arithmetic circuit 29 is for adjusting the zero point of the instantaneous weight measured using zero point data stored in advance in the memory 31. The circuit 30 is for adjusting the instantaneous weight span using span data stored in advance in the memory 32, and the details thereof will be described later. In addition, there is a switch 3 with 3 units and 3 output terminals.
Reference numeral 3 designates a mode changeover switch, which is switched to terminal M in the normal integration mode, switched to terminal Z in the zero point adjustment mode, and switched to terminal S in the span adjustment mode.

To explain the basic integration operation of the totalizer 20 using a specific example, it is assumed that the belt length of the weighing conveyor is 10 m, the belt speed is 10 m/min, and 6000 pulse signals are generated over the entire belt length.
2500 is set in the zero point adjustment memory 31, and a span factor 1.0000 (reference value) is set in the span adjustment memory 32. In addition, the maximum capacity of the scale is 36t/h, and the scale factor setting device 25
is set to 36, and the value of K of the weighting circuit 26 is preselected to 3,600,000. The analog-digital conversion circuit 23 outputs 2500 when the instantaneous weight is zero, and outputs 12500 when the instantaneous weight is maximum (both are binary codes, but for simplicity, they are shown in decimal format),
The arithmetic circuit 29 subtracts 2,500 from this output signal to give an output range of 0 to 10,000. Since the span factor is 1.0000, the output of the arithmetic circuit 30 as a multiplication circuit is 0 to 10000, and output signals in this range are input to the multiplication circuit 24. The multiplier circuit 24 multiplies the output of the arithmetic circuit 30 by 36, giving an output range of 0 to 360,000, and the output of the weighting circuit 26, which has chosen K to be 360,000, is 0 to 360,000/
3600000 becomes 0-0.1.

Now, assuming that the belt is being conveyed with the maximum instantaneous weight and the maximum belt speed, 100 movement pulse signals per unit length of the belt are output per second, received by the input terminal 22, and switched to the M of the changeover switch 33. It is input to the accumulation circuit 27 via the terminal. The weighting circuit 26 outputs 0.1, and each time the pulse signal P ₁ is input to the accumulation circuit 27, that 0.1 is added to the previous accumulated value. 100 pulses/second x 3600 in 1 hour
0.1 is accumulated 360,000 times from second to second, and the accumulated result is 36,000, and the display circuit 28 shows the conveyance amount.
36000Kg (36t) is displayed.

In the above embodiment, since one accumulation takes 1/100 second, the accumulation can be accomplished almost instantaneously, and the weighting circuit 27
If the value of the weight W (=1/K) in 6 is made sufficiently small (increasing the number of divisions, that is, reducing the instantaneous weight per pulse signal), it is possible to greatly increase the integration accuracy according to this small value. can.

Next, the zero point adjustment device, which is a feature of the present invention, will be explained.

The zero point adjustment device uses an analog-to-digital conversion circuit 23 when an error occurs in the zero point of the scale due to the instantaneous weight detection unit or the attachment of the object to be measured to the belt.
The output is not the correct measured value and if it is integrated as it is, an error will occur in the integrated value.This device is provided to prevent this.The zero point adjustment device described below uses a separate circuit means to adjust the zero point It does not take the form of obtaining data, and is built into the totalizer of this embodiment in a relatively simple form, and is equipped with an accumulating circuit 39 similar to the accumulating circuit 27 according to the above embodiment to perform zero point adjustment (hereinafter referred to as "zero point adjustment"). The aim is to obtain high-precision data (sometimes referred to as "key").

This zero point adjustment device has three means, one of which is a belt pulse setter 33 that sets the number of pulses per revolution of the belt, and a belt rotation speed setter 34 that sets an integer value for how many revolutions the belt should make. , a pulse number calculating circuit 35 which multiplies the outputs of these setting devices 33 and 34 to calculate the number of pulse signals that can be transmitted for the calibrated belt length; A gate circuit 37 that controls the passage of input pulse signals, and a counter 38 that counts the pulse signals from the gate circuit.
and the output of the counter 38 and the pulse number calculation circuit 3
5 and if they match, the gate circuit 37
The belt movement amount monitoring means is comprised of a comparison circuit 40 that provides a monitoring completion signal to the belt movement amount. The second means includes an accumulation circuit 39 that accumulates the output of the analog-to-digital converter circuit 23 using the pulse signal as a starting signal until the monitoring completion signal is output; Accumulation circuit 39
The accumulation (integration) result is sent to the pulse number calculation circuit 35.
This is a zero point weight calculation means for calculating the zero point weight for each pulse signal. The third means is to subtract the zero point weight from the instantaneous weight output from the memory 31 which stores the data of the zero point weight per pulse signal obtained by the division circuit 41 and the analog-digital conversion circuit 23. This is a zero point adjustment means consisting of a subtraction circuit 29.

The function is to set the weighing conveyor to run empty, set the belt rotation speed (integer) for zero adjustment in the belt rotation speed setting device 33, and set the number of emitted pulses for one revolution of the belt to the belt rotation speed setting device 33. Set it on the pulse setter 34. Once the data is set, the arithmetic circuit 35 calculates the number of pulses corresponding to the belt length targeted for zero adjustment. Switch the mode selector switch 33 to the Z terminal side and press the calibration push button 36.
When turned on, the gate circuit 37 opens, and the counter 38 counts the pulse signals per unit length of belt movement input to the pulse input terminal 22.
At the same time, the pulse signal that has passed through the gate circuit 37 is given to the accumulation circuit 39 via the Z terminal of the third-stage mode changeover switch 33-3, and is passed from the analog-digital conversion circuit 23 to the first-stage switch 33.
The instantaneous empty weight input to the accumulating circuit 39 via the -1 Z terminal is accumulated.

The contents of the counter 38 are compared point by point with the output of the arithmetic circuit 35 in a comparator circuit 40, and when they match, a match signal is output from the comparator circuit 40 to the gate circuit 37, and the gate circuit 37 is closed. counter 3
The counting of 8 and the processing of the accumulation circuit 39 are stopped. In the accumulating circuit 39, an integrated value of the instantaneous weight zero point output corresponding to the number of pulse signals corresponding to the set belt length is created. This integrated value is divided by the circuit 4
1 by the output of the arithmetic circuit 35 (the number of pulse signals corresponding to the belt length), the zero point output per pulse signal is obtained. This zero point output value is displayed on the display 42, and manual zero adjustment (Manual;
ML), it becomes a zero factor index, which is read and set in a zero factor setter 43 consisting of a switch, and then provided to the memory 31 via a zero adjustment switch 44. In the case of automatic zero adjustment (Auto; A), the output of the divider circuit 41 is transferred to the memory 3 via the A terminal of the zero adjustment switch 44.
1 is directly rewritten and used as the zero point data for the subsequent integration process.

To give a concrete example, the number of pulses per revolution of the belt is
6000, if the zero adjustment is done with 3 rotations of the belt, set 6000 to the belt pulse setter 33, then set the belt rotation speed setter 3 to 6000.
Set 3 to 4. The output of the arithmetic circuit 35 is 18000
Therefore, when the mode changeover switch 33 is switched to the Z terminal side and the calibration push button 36 is turned on, the gate circuit 3
7 opens and the counter 38 starts counting. At the same time, the accumulation circuit 39 converts the analog-to-digital converter 2
Accumulate the output of step 3 (of course, the accumulated contents are cleared before starting the accumulation). counter 38
When the number reaches 18000, the gate circuit 37 is closed and counting and accumulation are stopped. If the content of the accumulator circuit 39 at this time is 45018000, the arithmetic circuit 41 is
Execute 45018000/18000 and output 2501. By storing this zero point data 2501 in the memory 31, accurate instantaneous weight can be obtained by subtracting the memory contents 2501 from the output from the analog-to-digital conversion circuit 23 in the subtraction circuit 29 when in the integration mode (M). That is.

Note that here, the correct zero point output from the analog-digital conversion circuit 23 is set to 2500,
Even when the zero point output is determined to be 0, a similar zero adjustment can be performed by operating the accumulator circuit 39 and the arithmetic circuit 41 including the positive and negative signs.

Next, the span adjustment circuit will be explained.

The span adjustment circuit converts the analog-to-digital conversion circuit 2 when an error occurs in the span of the instantaneous weight detection section.
If the output of No. 3 does not become a predetermined correct measured value and is integrated as it is, an error will occur in the integrated value, so this is provided to prevent this. The span adjustment circuit described below does not require a separate circuit means to obtain data on the span factor to be corrected, but is built into the totalizer of this embodiment in a relatively simple form, and is implemented as described above. An accumulating circuit 50 similar to the accumulating circuit 27 according to the example is provided so that correction data for span adjustment can be obtained with high precision.

That is, the belt rotation speed for performing span adjustment is set in the belt rotation speed setting device 34, and the number of pulses to be emitted per revolution of the belt is set in the belt pulse setting device 3.
Set to 3. The arithmetic circuit 35 calculates the total number of pulses corresponding to the belt length subject to span adjustment. On the other hand, in order to set the reference instantaneous weight in advance, place the test chain on the belt or add the instantaneous weight directly to the instantaneous weight detection part with a test weight, and set the reference instantaneous weight obtained by this. Belt 1
The circumferential length is set in the belt circumferential length setting device 46.
After each data is set, the arithmetic circuit 47 multiplies the reference instantaneous weight data and one belt circumference data to obtain an integrated value of one belt circumference. In the next arithmetic circuit 48, this integrated value is multiplied by the belt rotation speed data from the belt rotation speed setting device 34.
This multiplication result becomes a reference integrated value for span adjustment and is applied to the span factor calculation circuit 49.

Switch the mode selector switch 33 to the S terminal side,
When the calibration push button 36 is turned on, the gate circuit 37 is opened, and the pulse signal of the belt movement amount input to the pulse input terminal 22 is counted by the counter 38. At the same time, the pulse signal passing through the gate circuit 37 is transferred to the third stage mode changeover switch 33-3.
is applied to an accumulation circuit 50 through the S terminal of the weighting circuit 26 to accumulate the basic instantaneous weights from the weighting circuit 26.

The contents of the counter 38 are compared point by point with the output of the arithmetic circuit 35 in a comparator circuit 40, and when they match, a match signal is output from the comparator circuit 40 to the gate circuit 37, and the gate circuit 37 is closed. counter 3
The counting of 8 and the processing of the accumulation circuit 50 are stopped. The accumulator circuit 50 includes a span factor at the time of calibration.
An integrated value influenced by SP (set in memory 32) is created. This integrated value SWI can also be displayed on the display circuit 28 via a gate circuit 51 that allows this data to pass in the span mode.

The integrated value SWI of the accumulating circuit 50 is determined by the reference integrated value WST from the arithmetic circuit 48 and the span factor SP during calibration in the arithmetic circuit 49.
A WST/SWI calculation is performed and a new span factor is calculated. The calculation result is displayed on the display circuit 42. When performing manual span adjustment, the displayed content becomes an index of the span factor and is set in the span factor setting device 52, which is composed of a switch, and the span factor is set in the memory 3 via the span changeover switch 53.
given to 2. When automatically setting the span adjustment data, the output of the arithmetic circuit 49 is directly rewritten in the memory 32 to new span data via the A terminal of the span changeover switch 53.

To give a concrete example, the number of pulses per revolution of the belt is
6000, the span shall be adjusted by three rotations of the belt,
One circumference of the belt is 10m, the reference instantaneous weight is 60Kg/m,
The capacity of the scale is 36t/h. Set the belt pulse setter 33 to 6000, the belt rotation speed setter 34 to 3, the belt 1 circumference setter 46 to 10, and the reference weight setter 45 to 60. The memory 32 is set to 1.0.

The output of the arithmetic circuit 35 is 6000×3=18000.
On the other hand, the output of the arithmetic circuit 47 is 60×10=600,
The output of the calculation circuit 48 is 600 x 3 = 1800 (Kg) (belt pulse 100Hz, output of the calculation circuit 35 is 18000)
18000/100 x 60 = 3 (minutes) (standard integrated value for 3 minutes for a capacity of 36t/h).

Set the mode selector switch 33 to S and press the calibration push button 3.
6, the gate circuit 37 opens, the counter 38 starts counting, and at the same time the accumulating circuit 50 accumulates the instantaneous weight (of course, the previous contents are cleared before accumulating). When the counter 38 reaches 18000, the gate circuit 37 closes and stops counting and accumulation.If the content of the accumulator circuit 50 at this time is 1800, the arithmetic circuit 49 outputs 1.0 from 1.0×1800/1800; is 1900, from 1.0×1800/1900
0.9473... is output, and subsequent span adjustment is performed by storing this value in the memory 32.

By the way, in the embodiment shown in Fig. 2, the data necessary for calibration (zero adjustment, span adjustment), namely the number of pulses per circumference of the belt, the number of rotations of the belt (integer), the length of one circumference of the belt, and A belt pulse setter 33, a belt rotation speed setter 34, a belt 1 circumference length setter 46, and a reference weight setter 45 are provided to independently set reference instantaneous weights of the test chain and test weight. Conventionally, the data necessary for calibrating zero point, span, etc. was calculated from the number of pulses per revolution of the belt and the number of rotations of the belt, the total length of the belt (number of pulses) to stop the calibration operation, and the data from the test chain or test weight. The standard integrated value was manually calculated from the standard instantaneous weight, belt circumference, and belt rotation speed, and was used as setting data.
This eliminates the inconvenience of having to perform manual calculation again when one parameter is changed, and also automates the data setting using internal calculations. In addition, by making it possible to set each data independently as in this example, it is possible to use a general-purpose totalizer that is not affected by the conditions on the weighing conveyor side, such as the belt length or the specifications of the pulse generator, without having to use a totalizer exclusively for that weighing conveyor. It has become a thing with a sexual nature.

In the embodiment shown in FIG. 2 above, a certain block has been explained as hardware as a functional circuit for calculation, accumulation, etc., but in this way, a functional circuit block can be replaced by one or several chips of electronic control means ( Of course, it is also possible to replace it with software (programs) on a microcomputer, for example. Although the disclosure of a specific program will be omitted, this type of program can be constructed relatively easily by those skilled in the art based on the disclosure of the present invention.

Furthermore, regarding the above embodiment, in the output signal of the analog-to-digital conversion circuit 23, the previous output value is stored and compared with the current output value, and when the difference is greater than a predetermined value (the fluctuation is (when the difference is too large), a circuit for issuing a warning or a circuit for correction may be provided depending on the difference. As the correction circuit, an interpolation calculation circuit is provided, for example, a circuit that calculates (previous output value + current output value)/2 and outputs the calculation result to the multiplication circuit 24 side of maximum capacity data.

As explained in detail above, according to the present invention, the zero point adjustment is configured in a circuit system centered on digital processing, and is compatible with a high-precision totalizer that integrates the instantaneous weight divided into subdivisions using the pulse signal of belt movement as a starting signal. By incorporating the device, errors in integrated values due to changes in zero point weight can be effectively prevented.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional example, and FIG. 2 is a block diagram showing an embodiment of the present invention. 1...Object to be weighed, 2...Weighing conveyor, 4...
Load-voltage converter, 5...Pulse generator, 2
3...Analog-digital conversion circuit, 24...
Maximum capacity data multiplication circuit, 26... Weighting circuit, 27, 39... Accumulation circuit, P ₁ , P ₂ ... Pulse signal serving as an accumulation activation signal, 29... Subtraction circuit, 31... Memory, 33...Belt pulse setting device, 34...Belt rotation speed setting device, 35...Multiplication circuit, 37...Gate circuit, 38...Counter,
40... Comparison circuit, 41... Division circuit.

Claims (1)

[Scope of utility model registration request] An analog signal proportional to the instantaneous weight of the object to be weighed transported by the belt transport device is received and converted into a digital signal by an analog-to-digital conversion circuit, and at the same time, an analog signal is transmitted in accordance with the belt movement amount of the belt transport device. In a belt scale totalizer that receives a pulse signal and uses the pulse signal as a starting signal, an accumulator circuit accumulates the output from the analog-to-digital converter circuit to determine the total weight relative to the conveyed amount. Belt movement amount monitoring means sets the number of pulse signals that can be transmitted during rotation and monitors until the number of pulse signals input when the belt is running idle reaches the number of pulse signals, and this belt movement amount monitoring means completes monitoring. An accumulation circuit that accumulates the output of the analog-to-digital conversion circuit using the pulse signal as a starting signal until the signal is output, and when the monitoring completion signal is output, the accumulation result of the accumulation circuit is used as the setting pulse. Zero point weight calculation means for calculating the zero point weight per pulse signal by having a division circuit that divides by the number of signals;
A totalizer for a belt scale equipped with a zero point adjustment device, characterized in that it is provided with zero point adjustment means for subtracting the zero point weight from the instantaneous weight from a digital conversion circuit.