Metering device

Abstract

A weighing device comprises: a conveying unit capable of conveying articles; a weighing unit connected to the conveying unit and outputting an original signal related to weight; and a weighing control unit, which outputs a weighing value of the article by processing the original signal, wherein the weighing control unit determines whether to adjust the zero point based on a determination signal obtained by applying a first filter to the original signal, and if it is determined that the zero point should be adjusted, the weighing control unit generates an adjustment signal and adjusts the zero point based on the adjustment signal, wherein the adjustment signal is obtained by applying a second filter of a higher order than the first filter to the original signal or the determination signal.

Description

Technical Field

[0001] The present disclosure relates to metering devices. Background Art

[0002] As an example of a weighing device, there can be cited a device that weighs the weight of articles (weighted objects) conveyed by a conveyor. Patent Gazette No. 4781982 discloses a weighing device that includes: a weighing unit that outputs a weighing signal associated with the weight of articles sequentially dropped at a predetermined drop interval; a signal processing unit that performs filter processing to remove high-frequency components from the weighing signal using a first filter and a second filter having different filter characteristics; and a weighing value calculation unit that calculates a weighing value based on the weighing signal after the filter processing.

[0003] The measuring device also has a 0-point correction unit that calculates and corrects the 0-point (zero point) that becomes the reference of the measuring value based on the measuring signal after the filter processing. The filter used in the filter processing is selected according to the delivery interval of the items, and the filter condition of the second filter is set to be variable according to the delivery interval. In the patent publication No. 4781982, the filter processing for adjusting the zero point is reliably performed on the measuring signal even at a short delivery interval. Summary of the invention

[0004] In the metering device described in the patent publication No. 4781982, the metering signal is filtered during the period corresponding to the delivery interval. When the zero point is adjusted within such an interval, in order to improve the adjustment accuracy of the zero point, it is considered to implement as many orders of filtering as possible on the original signal (i.e., filtering for as long as possible). Here, generally, the longer the filtering process is, the lower the responsiveness to the original signal. Therefore, when sudden noise (such as noise generated by the collision of the operator with the metering device, the occurrence of an earthquake, etc.) enters the original signal, the noise is sometimes used for the adjustment of the zero point. In this case, the adjusted zero point may deviate from the true zero point due to the implementation of the zero point adjustment.

[0005] An object of one aspect of the present disclosure is to provide a measuring device capable of performing zero point adjustment with high accuracy.

[0006] One aspect of the present disclosure relates to a weighing device comprising: a conveying unit capable of conveying articles; a weighing unit connected to the conveying unit and outputting an original signal related to weight; and a weighing control unit that outputs a weighing value of the article by processing the original signal, the weighing control unit determining whether to adjust the zero point based on a determination signal obtained by applying a first filter to the original signal, and if it is determined that the zero point should be adjusted, the weighing control unit generates an adjustment signal and adjusts the zero point based on the adjustment signal, the adjustment signal being obtained by applying a second filter of a higher order than the first filter to the original signal or the determination signal.

[0007] According to the metering device, the metering control unit first determines whether to adjust the zero point based on the judgment signal obtained by applying the first filter with a smaller order than the second filter (i.e., a filter with higher responsiveness than the second filter) to the original signal. As a result, the metering control unit can accurately determine whether the original signal contains sudden noise. Then, in the case of determining to adjust the zero point, the metering control unit generates an adjustment signal obtained by applying the second filter with a higher order than the first filter to the original signal or the judgment signal. As a result, the zero point can be adjusted based on the adjustment signal from which the noise has been properly removed. Therefore, the above-mentioned metering device can accurately adjust the zero point.

[0008] Alternatively, when the peak value included in the judgment signal exceeds a predetermined threshold value, the metering control unit determines that the zero point is not to be adjusted and does not adjust the zero point from the judgment until a predetermined time has passed. In this case, the zero point can be adjusted after eliminating the cause of the sudden noise. Therefore, the zero point can be adjusted with higher accuracy.

[0009] Alternatively, when the peak value included in the judgment signal exceeds a predetermined threshold value, the metering control unit determines not to adjust the zero point, and generates another judgment signal obtained by applying the first filter to another original signal output after the judgment signal is acquired. In this case, the zero point can be adjusted without using the original signal that may include sudden noise. Therefore, the zero point can be adjusted with higher accuracy.

[0010] Alternatively, the measurement control unit determines the occurrence timing of a peak value exceeding a predetermined threshold value among the peak values ​​included in the determination signal, deletes data generated in a predetermined period including the occurrence timing from the adjustment signal, and performs zero point adjustment based on the adjustment signal after the data is deleted. In this case, the zero point can be adjusted based on the adjustment signal from which sudden noise has been removed in advance. Therefore, the zero point can be adjusted with higher accuracy.

[0011] The first filter may not include a low-pass filter. In this case, since the time for applying the first filter to the original signal can be shortened, the determination signal can be reliably generated even when the period during which the original signal for adjusting the zero point can be acquired is short.

[0012] The time for applying the second filter to the original signal may also be longer than the time for applying the first filter to the original signal. In addition, at least one of the first filter and the second filter may also be formed by combining a plurality of digital filters. In these cases, the zero point can be adjusted with higher accuracy.

[0013] According to one aspect of the present disclosure, it is possible to provide a measuring device capable of performing zero point adjustment with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the structure of a measuring device according to an embodiment.

[0015] Figure 2 This is a diagram showing a part of the functional structure of the operation unit.

[0016] Figure 3 This is a flowchart for explaining the method of adjusting the zero point.

[0017] Figure 4 (a) and (b) are graphs showing examples of determination signals.

[0018] Figure 5 This is a graph showing an example of an adjustment signal.

[0019] Figure 6 It is a graph showing the adjustment signal in the reference example.

[0020] Figure 7 This is a schematic diagram of the structure of a measuring device according to a first modification.

[0021] Figure 8 This is a schematic diagram of the structure of a measuring device according to a second modification. DETAILED DESCRIPTION

[0022] Hereinafter, an embodiment of one aspect of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that the same reference numerals are given to the same or corresponding parts in each figure, and repeated description is omitted.

[0023] Figure 1 This is a schematic diagram of the structure of the measuring device according to this embodiment. Figure 1 The metering device 1 shown is Figure 1The measuring device 1 is a device for measuring while conveying the object to be measured in the direction of the arrow in FIG. 1 (hereinafter referred to as the "conveying direction"). The measuring device 1 is, for example, a device arranged at the end of a production line. The object to be measured is, for example, an article P in a long strip shape extending along the conveying direction. The measuring device 1 includes a conveying unit 2, a stand 3, a measuring unit 4, and an operating unit 6.

[0024] The conveying section 2 is a conveyor that conveys articles P in a conveying direction, and includes a first conveyor section 2a, a second conveyor section 2b, and a third conveyor section 2c. The first conveyor section 2a, the second conveyor section 2b, and the third conveyor section 2c each include a rotating body such as a roller, a motor, and a conveyor belt. The first conveyor section 2a, the second conveyor section 2b, and the third conveyor section 2c are sequentially arranged from the upstream side in the conveying direction. That is, the second conveyor section 2b is located between the first conveyor section 2a and the third conveyor section 2c in the conveying direction. The first conveyor section 2a is a conveyor that feeds articles P to the second conveyor section 2b. The first conveyor section 2a may include, for example, a metal detector not shown. The second conveyor section 2b is a conveyor that feeds articles P conveyed from the first conveyor section 2a to the third conveyor section 2c. The third conveyor section 2c is a conveyor that sends articles P out from the second conveyor section 2b. The third conveyor section 2c includes, for example, a dispenser (not shown) that dispenses articles P whose weight is out of an appropriate range.

[0025] The weighing unit 4 is installed on the second conveyor section 2b. Therefore, the articles P conveyed by the conveying section 2 are weighed on the second conveyor section 2b. In addition, sensors S1 and S2 for detecting the presence of articles P are respectively provided on the upstream side and the downstream side of the second conveyor section 2b. Thus, it is possible to easily determine whether the entire article P is located on the second conveyor section 2b. In other words, it is possible to easily determine whether the article P is not conveyed on the second conveyor section 2b (so-called idle operation) based on the detection results of the sensors S1 and S2.

[0026] The stand 3 is a member for accommodating the measuring unit 4 and is fixed to the floor F below the conveying unit 2. The stand 3 includes a main body 3a for accommodating the measuring unit 4 and a plurality of legs 3b located between the main body 3a and the floor F. Figure 1 In FIG. 1 , the main body 3 a is shown by a dotted line.

[0027] The measuring unit 4 is a component connected to the conveying unit 2 and outputs a signal related to the weight. The measuring unit 4 is located, for example, on the upstream side of the conveying unit 2. The measuring unit 4 includes a strain body 11 that is compressed and stretched according to the load and a measuring unit 12 that measures the articles P located on the second conveyor unit 2b. The strain body 11 includes a movable steel body 11a that supports the second conveyor unit 2b and a fixed steel body 11b that is fixed to the stand 3. The movable steel body 11a and the fixed steel body 11b are, for example, components that extend in the vertical direction. One end of the movable steel body 11a is connected to the upstream end of the second conveyor unit 2b, and the other end of the movable steel body 11a is connected to the measuring unit 12. One end of the fixed steel body 11b is connected to the measuring unit 12, and the other end of the fixed steel body 11b is connected to the main body 3a of the stand 3. Although not shown in the figure, in the measuring unit 12, a plurality of strain gauges attached to the strain body 11 are connected to a Wheatstone bridge circuit.

[0028] The metering unit 12 of the metering section 4 extracts an electrical signal corresponding to the load transmitted from the strain body 11 from the above-mentioned Wheatstone bridge circuit. The electrical signal is an analog signal representing the metering result of the metering unit 12. The analog signal includes, for example, a first analog signal for measuring the article P and a second analog signal for adjusting the zero point. The first analog signal and the second analog signal are respectively extracted during the operation of the conveying section 2. In addition, the first analog signal is extracted when the article P is completely arranged on the second conveyor section 2b. On the other hand, the second analog signal is extracted when the article P is not arranged on the second conveyor section 2b. In other words, the second analog signal is extracted during the idle operation of the conveying section 2. When the metering device 1 is arranged on a production line for manufacturing the article P, the second analog signal can also be extracted during the manufacturing process of the article P and when the article P is not arranged on the second conveyor section 2b.

[0029] When the analog signal generated by the weighing unit 4 is output to the operating unit 6 or the like, there is a tendency that the network load in the weighing device 1 is large. Therefore, in the present embodiment, the weighing unit 4 has an A / D conversion unit for converting the analog signal into a digital signal, and outputs the digital signal as an original signal related to the weight to the operating unit 6 or the like. Thus, the network load in the weighing device 1 can be reduced. Therefore, in the present embodiment, the weighing unit 4 outputs a first digital original signal based on the first analog signal and a second digital original signal based on the second analog signal as original signals.

[0030] The operation unit 6 is a member for operating the conveying unit 2 and the weighing unit 4 and is provided vertically, for example, near the second conveyor unit 2 b. The operation unit 6 includes a display interface 7 and a control unit 8.

[0031] The display interface 7 is a component (display unit) that displays an image based on the display information output from the control unit 8. The display interface 7 displays, for example, a measurement value representing the measurement result of the weight of the article P, a waveform after filtering of the above-mentioned electrical signal, the conveying speed of the conveying unit 2, the size of the article P along the conveying direction, the conveying frequency of the article P, the measuring interval of the article P, etc. In the present embodiment, the display interface 7 has a touch panel 7a that functions as an external input unit. Thus, once the display interface 7 receives input from the operator (user), input information representing the input content is output to the control unit 8. The input information is, for example, data related to the conveying speed of the conveying unit 2, the size of the article P along the conveying direction, the type of the article P, the conveying frequency of the article P, etc. The conveying frequency of the article P is set, for example, based on the capacity of the production machine located upstream of the weighing device 1.

[0032] The measured value of the article P is data obtained based on data (described in detail later) sent from the measuring unit 4 to the operating unit 6. The measured value is calculated by a known method. In addition, the measured interval of the article P is calculated by the control unit 8 based on the conveying speed of the conveying unit 2, the above-mentioned size of the article P, and the conveying frequency of the article P.

[0033] The control unit 8 is a controller for controlling each component included in the weighing device 1, and is built into the operation unit 6. The control unit 8 is composed of a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory). For example, the control unit 8 outputs an action signal for controlling the conveying speed of the conveying unit 2 specified via the display interface 7 to the conveying unit 2. In addition, for example, when a dispenser is set in the third conveyor unit 2c and the control unit 8 determines that the weight of the article P is out of a preset appropriate range, the control unit 8 outputs an action signal to the dispenser to divert the article P (exclude it from the production line). The control unit 8 is a processing unit that not only controls each component included in the weighing device 1, but also receives / calculates / sends various signals and records / reads various signals. As an example of the calculation of various signals performed by the control unit 8, the derivation of the weighing result of the article P can be cited. Therefore, the control unit 8 has, for example, a part for outputting a control signal of the conveying unit 2, a part for calculating the measurement value of the item P based on the electrical signal generated by the measuring unit 4, a part for adjusting the zero point based on the electrical signal generated by the measuring unit 4, a part (storage unit) for storing various signals and various information, etc.

[0034] Next, use Figure 2 A part of the functional configuration of the control unit 8 will be described. Figure 2 FIG. 2 is a diagram showing a part of the functional structure of the operation unit. Figure 2As shown in FIG. 1 , the measurement control unit 21 included in the operation unit 6 is a part of the control unit 8, and is a part that processes the original signal to output the measurement value related to the article P on the conveying unit 2. In addition, the measurement control unit 21 is also a part that performs zero point adjustment by processing the original signal. The measurement control unit 21 includes a signal receiving unit 22, a filter unit 23, a measurement processing unit 24, a determination unit 25, and a zero point adjustment unit 26.

[0035] The signal receiving unit 22 receives the signal output from the measuring unit 4. In the present embodiment, the signal receiving unit 22 receives the first digital original signal and the second digital original signal output from the measuring unit 4.

[0036] The filter unit 23 removes noise from the signal received by the signal receiving unit 22 by performing a filtering process on the signal. The filter unit 23 outputs the signal after the noise is removed. The filter unit 23 may also perform a plurality of filtering processes (multi-order filtering processes) showing mutually different characteristics on the above-mentioned signal. For example, the filter unit 23 has a low-pass filter that attenuates frequency components exceeding a predetermined frequency, a notch filter (band-stop filter) that attenuates the noise of the frequency of the rotating body included in the conveying unit 2, and a variable filter that can change the attenuation amount of each frequency band according to the weight of the article P as a digital filter.

[0037] The filter unit 23 has one or more filters. The filter can be composed of any one of the above-mentioned digital filters, or can be composed of a combination of the above-mentioned digital filters. The combination of the above-mentioned digital filters can be performed automatically or manually. The selection of each filter included in the filter unit 23 can be performed automatically by the control unit 8, or can be performed manually by the user via the display interface 7.

[0038] In the present embodiment, the filter unit 23 has a metering filter and a zero-point adjustment filter. At least one of the metering filter and the zero-point adjustment filter is formed by combining a plurality of digital filters. In other words, at least one of the filtering process of the metering filter and the filtering process of the zero-point adjustment filter is implemented by a multi-order (Japanese expression: multi-stage) filter. The zero-point adjustment filter has a first filter and a second filter of a multi-order than the first filter. Therefore, the time for applying the second filter to the signal is longer than the time for applying the first filter to the signal. The first filter is composed of a digital filter other than a low-pass filter. One of the first filter and the second filter can be the same as the metering filter. In addition, at least one of the first filter and the second filter can also include all the digital filters included in the metering filter. The selection of the metering filter and the selection of the zero-point adjustment filter can be performed automatically or manually.

[0039] The weighing filter is a filter used when weighing the weight of the article P, and is applied to the first digital original signal. A signal is generated by filtering the first digital original signal using the weighing filter. The calculated signal has a signal waveform that is arranged to calculate the weight of the article P. Therefore, the calculated signal can be said to be a signal corresponding to the weight of the article P.

[0040] The first filter and the second filter included in the zero point adjustment filter are filters used when adjusting the zero point, respectively, and are applied to the second digital original signal. A determination signal is generated by applying the first filter to the second digital original signal. The determination signal has a signal waveform that has been sorted to determine whether the second digital original signal can be used for zero point adjustment. On the other hand, the adjustment signal is generated by applying at least the second filter to the second digital original signal. In this embodiment, the adjustment signal is generated by applying the first filter and the second filter to the second digital original signal. That is, in this embodiment, the adjustment signal is generated by applying the second filter to the determination signal. The adjustment signal has a signal waveform that has been sorted for adjusting the zero point.

[0041] Compared with the signal waveform of the adjustment signal, the signal waveform of the determination signal tends to have fixed noise (fixed (steady-state) noise) remaining. On the other hand, since the second filter has poorer responsiveness than the first filter, there is an offset in the signal waveform of the adjustment signal caused by noise that is generated suddenly (sudden noise, pulse (impact) noise). Fixed noise is, for example, noise generated by the drive of the conveyor 2, noise generated by the drive of a device different from the metering device 1, etc. Sudden noise is, for example, noise generated by an unexpected collision of the operator with the metering device 1, noise caused by unexpected floor vibration, noise generated by the swing of the passing time of sensors S1 and S2, etc. In the case where the metering device 1 is arranged on a production line for manufacturing the article P, noise generated during the maintenance process of other devices included in the production line is also a kind of sudden noise. Compared with fixed noise, sudden noise occurs in a short time and often has large vibrations.

[0042] The weighing processing unit 24 weighs the weight of the article P using the calculated signal output from the filter unit 23. The weighing processing unit 24 outputs the weighed weight of the article P to other parts of the control unit 8. The control unit 8 determines whether the weight of the article P is out of a preset appropriate range. As described above, the control unit 8 outputs an action signal to, for example, a dispenser based on the determination result.

[0043] The determination unit 25 determines whether to adjust the zero point based on the determination signal output from the filter unit 23. The determination unit 25 determines, for example, whether the peak value included in the determination signal exceeds a specified threshold value. More specifically, the determination unit 25 determines, for example, whether the determination value (maximum value - minimum value) obtained by subtracting the minimum value from the maximum value of the data group included in the determination signal exceeds a specified threshold value. In the case where the determination value does not exceed the specified threshold value, the determination unit 25 determines to adjust the zero point. On the other hand, in the case where the above-mentioned determination value exceeds the specified threshold value, the determination unit 25 determines not to adjust the zero point. In this case, the metering control unit 21 does not adjust the zero point from the determination until a specified time has passed. The specified time is, for example, more than 1 second and less than 5 seconds.

[0044] The zero point adjustment unit 26 adjusts the zero point of the weighing device 1 based on the adjustment signal output from the filter unit 23. The zero point adjustment unit 26 adjusts the zero point along a period set based on the detection results of the sensors S1 and S2, for example. The zero point adjustment unit 26 may adjust the zero point during the idle operation of the conveyor unit 2, or may adjust the zero point during the operation of the conveyor unit 2 and when the article P is being conveyed by the conveyor unit 2.

[0045] Next, refer to Figure 3 An example of a zero point adjustment method of the measuring device 1 according to the present embodiment will be described. Figure 3 This is a flowchart for explaining the zero point adjustment method.

[0046] First, when the conveyor unit 2 is in operation and the second conveyor unit 2b is not conveying articles P (so-called idle operation), the second analog signal is output from the measuring unit 12 (first step ST1). In the first step ST1, first, the idle operation state of the conveyor unit 2 is identified based on the detection results of the sensors S1 and S2. Then, the second analog signal, which is an electrical signal obtained by the measuring unit 4 during the idle operation of the conveyor unit 2, is output.

[0047] Next, a second digital original signal is generated from the second analog signal (second step ST2 ). In the second step ST2 , the A / D converter of the measuring unit 4 converts the second analog signal into a second digital original signal.

[0048] Next, a determination signal is generated from the second digital original signal (third step ST3 ). In the third step ST3 , the filter unit 23 of the measurement control unit 21 generates the determination signal by applying the first filter to the second digital original signal. Figure 4 (a) and (b) are graphs showing examples of judgment signals. Figure 4 In the graphs shown in (a) and (b) of FIG. 1 , the horizontal axis represents time and the vertical axis represents count value. Figure 4 (a) shows the determination signal DS1 and Figure 4The determination signal DS2 shown in (b) is generated based on the second digital original signal output at different timings. A portion of the determination signal DS1 includes a peak 31 caused by fixed noise, and the maximum value of the peak 31 is less than the threshold Th. On the other hand, a portion of the determination signal DS2 includes a peak 32 caused by sudden noise, and the maximum value of the peak 32 exceeds the threshold Th. The predetermined threshold Th is a value that is predetermined and can be changed via the display interface 7 or the like.

[0049] Next, it is determined whether to adjust the zero point based on the determination signal (fourth step ST4). In the fourth step ST4, for example, when there is no value exceeding a predetermined threshold value in the data group included in the determination signal, the determination unit 25 of the measurement control unit 21 determines to use the second digital original signal to adjust the zero point. On the other hand, for example, when there is a value exceeding a predetermined threshold value in the data group included in the determination signal, the determination unit 25 determines not to use the second digital original signal to adjust the zero point. Therefore, for example, when using Figure 4 In the case of the determination signal DS1 shown in (a), the determination unit 25 determines to adjust the zero point. Figure 4 In the case of the determination signal DS2 shown in (b), the determination unit 25 determines not to adjust the zero point.

[0050] Next, when it is determined in step 4 ST4 that the zero point is to be adjusted (step 4 ST4 : Yes), an adjustment signal is generated based on the determination signal (step 5 ST5 ). In step 5 ST5 , the filter unit 23 generates the adjustment signal by applying the second filter to the determination signal. Figure 5 This is a graph showing an example of an adjustment signal. Figure 5 The adjustment signal AS1 shown is obtained by applying the second filter to the determination signal DS1. Therefore, compared with the determination signal DS1, the adjustment signal AS1 has its peak removed and is smoothed.

[0051] Next, the zero point is adjusted using the adjustment signal (sixth step ST6). In the sixth step ST6, the zero point adjustment unit 26 adjusts the zero point after appropriately converting the count value of the adjustment signal AS1. It should be noted that, if it is determined in the fourth step ST4 that the zero point is not to be adjusted (fourth step ST4: No), the fifth step ST5 and the sixth step ST6 are not performed.

[0052] The effects of the measuring device 1 according to the present embodiment described above will be described by comparing with the reference example described below. In the reference example, whether to adjust the zero point is not determined based on the determination signal. Therefore, when the determination signal DS2 is obtained, the zero point is adjusted using the adjustment signal generated based on the determination signal DS2. Figure 6 It is a graph showing the adjustment signal in the reference example. Figure 6 The adjustment signal AS2 shown is a signal obtained by applying the second filter to the determination signal DS2. Since the responsiveness of the second filter is lower than that of the first filter, it is difficult to completely remove the component of the burst noise from the adjustment signal AS2. Therefore, compared with the peak 32 of the determination signal DS2, the adjustment signal AS2 includes a smooth peak 41. At the peak 41, the difference between its maximum value and the amplitude of the region R included nearby is small. In this case, the data group included in the region R is sometimes used for zero point adjustment. Therefore, when the zero point is adjusted based on the original signal including the burst noise, the zero point may be misaligned.

[0053] In contrast, in the present embodiment, the metering control unit 21 first determines whether to adjust the zero point based on the determination signal DS1 obtained by applying a first filter having a smaller order than the second filter (i.e., a filter having a higher responsiveness than the second filter) to the second digital original signal. Thus, the metering control unit 21 can determine with high accuracy whether the second digital original signal includes sudden noise. In addition, the metering control unit 21 can exclude the second digital original signal including sudden noise with high accuracy when adjusting the zero point. Then, when determining that the zero point is to be adjusted, the metering control unit 21 generates an adjustment signal AS1 obtained by applying a second filter having a higher order than the first filter to the original signal. Thus, the zero point adjustment unit 26 can adjust the zero point based on the adjustment signal AS1 from which the noise is properly removed. Therefore, the metering device 1 can adjust the zero point with high accuracy.

[0054] In one embodiment, when the peak value included in the determination signal exceeds the threshold value Th, the zero point adjustment unit 26 of the measurement control unit 21 determines not to adjust the zero point and does not adjust the zero point until a predetermined time has passed since the determination. In this case, the measurement device 1 can adjust the zero point after eliminating the cause of the sudden noise. Therefore, the measurement device 1 can adjust the zero point with higher accuracy.

[0055] In one embodiment, the first filter does not include a low-pass filter. Therefore, since the time for applying the first filter to the second digital original signal can be shortened, the determination signal can be reliably generated even when the period during which the original signal for adjusting the zero point can be acquired is short.

[0056] In one embodiment, the second filter is applied to the second digital original signal for a longer time than the first filter is applied to the second digital original signal. In addition, in this embodiment, at least one of the first filter and the second filter can also be formed by combining multiple digital filters. In these cases, the zero point can be adjusted with higher accuracy.

[0057] The following describes various modifications of the above-mentioned embodiment. In each of the following modifications, descriptions of the parts that overlap with the above-mentioned embodiment are omitted. Therefore, the following mainly describes the parts that are different from the above-mentioned embodiment.

[0058] Figure 7 : is a schematic diagram of the structure of the metering device involved in the first variant. Figure 7 As shown, the weighing device 1A is a device for weighing the weight of the long article P1 along the conveying direction, and has a first weighing section 4A and a second weighing section 5. The first weighing section 4A is located on the upstream side of the second conveyor section 2b. The second weighing section 5 is located on the downstream side of the second conveyor section 2b, and has a strain body 51 and a weighing unit 52. Similar to the strain body 11, the strain body 51 has a movable steel body 51a supporting the second conveyor section 2b and a fixed steel body 51b fixed to the frame 3.

[0059] When the conveying unit 2 is in operation and the article P1 is not being conveyed by the conveying unit 2, the filter unit 23 (see Figure 2 ) For example, the first filter included in the zero point adjustment filter is applied to the original signal output from the first metering unit 4A and the original signal output from the second metering unit 5, respectively. Here, the first filter applied to the original signal output from the first metering unit 4A and the first filter applied to the original signal output from the second metering unit 5 can be the same as or different from each other. Next, the judgment signal obtained by filtering the original signal output from the first metering unit 4A and the judgment signal obtained by filtering the original signal output from the second metering unit 5 are summed. The judgment unit 25 of the metering control unit 21 determines whether to adjust the zero point based on the summed judgment signal obtained thereby. In the case where it is determined that the zero point is to be adjusted, the zero point is adjusted based on the summed adjustment signal obtained by applying the second filter to the above-mentioned summed judgment signal.

[0060] Alternatively, the filter unit 23 of the control unit 8 may generate the total determination signal by applying the first filter included in the zero point adjustment filter to the total original signal of the original signal output from the first measuring unit 4A and the original signal output from the second measuring unit 5 .

[0061] The weighing device 1A according to the first modification example also has the same effects as those of the above-described embodiment. In addition, according to the first modification example, the weight of the long article P1 can be measured with high accuracy in the conveying direction.

[0062] Figure 8 : is a schematic diagram of the measuring device involved in the second variant. Figure 8 As shown, an AFV (Anti Floor Vibration) unit 61 (interference vibration detection unit) is provided on the fixed steel body 11b of the metering device 1B. The AFV unit 61 is a component that detects the interference vibration of the metering device 1 including the metering unit 12. The AFV unit 61 detects the vibration transmitted from the floor F to the metering device 1B, the vibration of the conveying unit 2, etc. The AFV unit 61 detects the interference vibration and outputs a vibration signal corresponding to the interference vibration. The vibration signal output from the AFV unit 61 is an analog signal. By filtering the vibration signal, a correction signal caused by the interference vibration is generated.

[0063] The reference value of the correction signal may also be adjusted based on a vibration signal obtained during the operation of the conveying unit 2 and when the article P is not being conveyed by the conveying unit 2. At this time, similarly to the adjustment of the zero point shown in the above embodiment, first, it is determined whether the vibration signal is suitable as a signal for adjusting the above reference value. For example, the determination unit 25 determines whether to adjust the reference value based on a reference value determination signal obtained by applying a determination filter included in the filter unit 23 to the vibration signal. In the case where it is determined that the reference value is to be adjusted, the reference value of the correction signal may also be adjusted based on a signal obtained by applying a correction filter to the reference value determination signal.

[0064] The correction filter is of multiple orders than the determination filter. Therefore, the time for applying the correction filter to the signal is longer than the time for applying the determination filter to the signal. The determination filter may also be composed of a digital filter other than a low-pass filter. One of the determination filter and the correction filter may also be the same as the measurement filter. In addition, at least one of the determination filter and the correction filter may also include all the digital filters included in the measurement filter. The selection of the determination filter and the selection of the correction filter may be performed automatically or manually, respectively. The determination filter may be the same as or different from the first filter included in the zero-point adjustment filter. In addition, the correction filter may be the same as or different from the second filter included in the zero-point adjustment filter.

[0065] In the second modified example, the control unit 8 calculates the weight of the article P based on the calculation signal output from the filter unit 23 and the correction signal. Specifically, the control unit 8 subtracts the correction signal from the calculation signal to generate a calculation signal after correcting the error of the calculation signal caused by the disturbance vibration. Here, the characteristics of the calculation signal and the characteristics of the correction signal are different from each other. Therefore, the control unit 8 adds a predetermined coefficient to the correction signal in advance for adjustment. The control unit 8 calculates the weight of the article P based on the corrected calculation signal, and outputs the weight information indicating the weight of the article P to the display interface 7.

[0066] Even in the above-mentioned second variant, the same effects as those of the above-mentioned embodiment are achieved. In addition, by calculating the weight of the item P using a calculation signal after correcting the error of the calculation signal caused by the interfering vibration, the weight of the item P can be measured with high precision. Furthermore, by applying a determination filter to the vibration signal, a signal for determining whether to adjust the reference value of the correction signal is first obtained. Then, the signal is used to determine whether to actually adjust the reference value. Thus, it is determined with high precision whether the vibration signal includes sudden noise. In addition, when adjusting the reference value of the correction signal, the vibration signal including sudden noise can be excluded with high precision. In summary, the adjustment of the reference value of the correction signal can be implemented based on a signal from which the noise has been properly removed.

[0067] The above describes the embodiment of the metering device involved in one aspect of the present disclosure and its various variations, but one aspect of the present disclosure is not limited to the above embodiment and the above variations. For example, the above first variation and the above second variation may be combined with each other. In this case, based on the total vibration signal, it can be determined whether to adjust the reference value of the correction signal, and the reference value of the correction signal can be adjusted.

[0068] In the above-mentioned embodiment and the above-mentioned variation, the metering unit has an A / D conversion unit for converting an analog signal into a digital signal, and outputs a first digital original signal based on the first analog signal and a second digital original signal based on the second analog signal as original signals, but it is not limited to this. For example, it is also possible that the metering unit does not have an A / D conversion unit, and instead, the control unit has an A / D conversion unit. In this case, the original signal output from the metering unit can be the first analog signal and the second analog signal. For example, the original signal is subjected to analog / digital conversion by the metering control unit. In this case, for example, it is also possible that an A / D conversion filter is included in the digital filter included in the filter unit, and the A / D conversion filter is applied to the original signal. Here, the first filter of the filter for zero point adjustment may also include an A / D conversion filter. Alternatively, the first filter may also be an A / D conversion filter.

[0069] In the above-mentioned embodiment and the above-mentioned modification, the adjustment signal is generated by applying the second filter to the determination signal, but the present invention is not limited thereto. The adjustment signal may also be generated by applying at least the second filter to the original signal output from the metering unit. In this case, the second filter may also include a part or all of the digital filter included in the first filter.

[0070] In the above-mentioned embodiment and the above-mentioned variation, the adjustment signal is generated after it is determined in the fourth step that the zero point is adjusted, but it is not limited to this. For example, the adjustment signal can also be generated before the fourth step. In this case, the generation of the adjustment signal can be implemented at the same time as the generation of the determination signal, or it can be implemented in the process of determining whether to adjust the zero point. Therefore, since the fourth step can be implemented in the process of generating the adjustment signal, the time required for adjusting the zero point can be shortened.

[0071] In the above-mentioned embodiment and the above-mentioned modification, when the determination unit determines that the zero point is not to be adjusted, the metering control unit does not adjust the zero point from the determination until a predetermined time has passed, but the present invention is not limited thereto. For example, when it is determined that the zero point is not to be adjusted, the determination unit may generate another determination signal obtained by applying the first filter to another original signal output after the determination signal is acquired. In this case, the zero point adjustment unit can also adjust the zero point without using the original signal that may include sudden noise. Therefore, the adjustment of the zero point can be performed with higher accuracy.

[0072] In the above-mentioned embodiment and the above-mentioned variation, when the maximum value of the peak value included in the determination signal exceeds the prescribed threshold value, the determination signal and the original signal used to generate the determination signal are not used to adjust the zero point, but it is not limited to this. For example, the signal from which the above-mentioned peak value and the data near it are removed can also be used to implement the adjustment of the zero point. In this case, the metering control unit can also determine the occurrence time of the peak value that exceeds the prescribed threshold value among the peak values ​​included in the determination signal, delete the data generated during the prescribed period including the occurrence time from the adjustment signal, and implement the adjustment of the zero point based on the adjustment signal after deleting the data. Thus, the zero point can be adjusted according to the adjustment signal from which the sudden noise is removed in advance. Therefore, the adjustment of the zero point can be implemented with higher accuracy. It should be noted that the occurrence time of the peak value is, for example, equivalent to the time when the maximum value of the peak value is obtained. In addition, the prescribed period is equivalent to the period from 5 seconds before to 5 seconds after the above-mentioned occurrence time. That is, the prescribed period is a range of 10 seconds centered on the above-mentioned occurrence time.

[0073] In the above-mentioned embodiment and the above-mentioned modification, the zero point is adjusted based on one adjustment signal, but the present invention is not limited thereto. For example, the zero point may be adjusted based on a plurality of adjustment signals. In this case, for example, a plurality of adjustment signals obtained at different times may be combined. Thus, even when the frequency of conveying items is high, the weighing device can adjust the zero point.

[0074] In the above-mentioned embodiment and the above-mentioned modification, the deformation of the measuring unit is measured, but the present invention is not limited to this. For example, a force balance type or tuning fork type measuring unit may also be used.

Claims

1. A measuring device comprising: A conveying unit capable of conveying items; a weighing unit connected to the conveying unit and outputting an original signal related to the weight, wherein the original signal includes a first original signal for weighing the article obtained when the article is completely arranged in the conveying unit and a second original signal for adjusting the zero point obtained during the idle operation of the conveying unit; and The weighing control unit processes the original signal to output the weighing value of the article. The metering control unit determines whether to adjust the zero point based on a determination signal obtained by applying a first filter to the second original signal. If it is determined that the zero point is to be adjusted, the metering control unit generates an adjustment signal, and performs the adjustment of the zero point based on the adjustment signal. The adjustment signal is obtained by applying a second filter having a higher order than the first filter to the second original signal or the determination signal. When a peak value included in the determination signal exceeds a predetermined threshold value, the measurement control unit determines that the zero point is not to be adjusted, and does not adjust the zero point until a predetermined time has passed since the determination.

2. The metering device according to claim 1, wherein: When a peak value included in the determination signal exceeds a predetermined threshold value, the measurement control unit determines not to adjust the zero point and generates another determination signal obtained by applying the first filter to another second original signal output after acquiring the determination signal.

3. The metering device according to claim 1, wherein: The measurement control unit determines the occurrence timing of a peak value exceeding a predetermined threshold value among the peak values ​​included in the determination signal, deletes data generated in a predetermined period including the occurrence timing from the adjustment signal, and performs the zero point adjustment based on the adjustment signal after deleting the data.

4. The metering device according to any one of claims 1 to 3, wherein: The first filter does not include a low pass filter.

5. The metering device according to any one of claims 1 to 3, wherein: The second filter is applied to the second original signal for a longer time than the first filter is applied to the second original signal.

6. The metering device according to any one of claims 1 to 3, wherein: At least one of the first filter and the second filter is formed by combining a plurality of digital filters.

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