JP2008268068A - Weighing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a weighing apparatus capable of weighing at a high speed with high accuracy, by eliminating continual low period vibration component of a roller and belt, or the like, of a weighing conveyer and without causing delays. <P>SOLUTION: The weighing apparatus comprises a vibration period calculation means 31 for calculating the period of continual low period vibration of a conveying means, and generating a trigger corresponding to the period, a waveform condition storage means 32 for calculating and storing waveform generation conditions including a phase and amplitude, in order to generate a vibration corrected waveform approximating a waveform of a weighing signal without load output by a weighing means, when a conveying means does not convey articles from a basic waveform function formed of the period calculated by the vibration period calculation means; a corrected waveform generation means 33 for generating a correction signal for correcting the weighing signal from the conditions for generating the vibration waveform stored in the waveform condition storage means, on the basis of the trigger generated by the vibration period calculation means; and a correction means 34 for calculating the weighing value of the articles from the difference between the weighing signal output from the weighing means and the correction signal output from the corrected waveform generation means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a weighing device that measures the weight of an article to be conveyed, and more particularly, to a weighing device having a function of removing a steady vibration component included in a measured value output from a weighing means.

  A weighing device that measures the weight of an article in the state of conveying the article is often used in a weight sorter or the like in a form in which a weighing conveyor is inserted in the article conveyance line, and is usually located between the front conveyor and the rear conveyor. The weighing conveyor is supported by the weighing machine. Each time the article passes on the weighing conveyor, the weight of the article is loaded on the measuring instrument together with the weighing conveyor weight, and the weight of the weighing conveyor is subtracted from the output signal of the weighing instrument. The weight can be measured.

  Since such weighing devices are generally installed and installed in the production line, floor vibrations caused by other production facilities, low-cycle vibration components due to the rollers and belts of the weighing conveyor, etc. are output as the noise components. The measurement accuracy is deteriorated by superimposing on. For this reason, the noise component is removed from the output signal of the meter by the LPF until the limit of the weighing capability, but the low-frequency vibration component having a frequency lower than the cutoff frequency of the LPF set to the limit of the metering capability is determined by the LPF. Could not be removed.

Therefore, as a method for removing the low-frequency vibration component of the stationary floor vibration, the output signal of the strain sensor, which is one of the measuring instruments, is received as the source signal, and the stationary signal is continuous and periodic from the source signal. After extracting the signal component, the signal period is detected, the phase of this signal period is adjusted to be in phase or opposite to the phase of the source signal, and the phase-adjusted stationary signal component is adjusted to the source signal. There is a distortion sensor signal processing device that removes a stationary signal component from the source signal by subtracting or adding (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2006-300868

However, this distortion sensor signal processing device extracts the stationary signal component because it extracts the stationary signal component that has continuity and periodicity from the source signal and then detects the signal cycle and adjusts the phase. This requires a delay time to affect the weighing capacity. For example, this delay time usually takes 1 / (the frequency of the steady signal component) seconds, so the steady low-frequency vibration component of the roller may be several Hz, and the delay time will take several hundred msec.・ There was a problem that we could not measure with high accuracy.

  The present invention has been made to solve such problems of the prior art, and is capable of measuring high-speed and high-accuracy by removing stationary low-period vibration components such as rollers and belts of a weighing conveyor without delay. An object of the present invention is to provide a weighing device that can be used.

  In order to achieve the above object, a weighing device according to a first aspect of the present invention comprises a conveying means that conveys articles (P) that are sequentially loaded at a predetermined charging interval, and measures the articles together with the conveying means. A weighing means for outputting a weighing signal related to the weight of the article, a vibration period calculating means for calculating a constant low-cycle vibration period of the conveying means, and generating a trigger corresponding to the period, Basically composed of a period calculated by the vibration period calculating means with a vibration correction waveform approximating the waveform of a low-period vibration component superimposed on an unloaded weighing signal output from the weighing means in the absence of an article in the conveying means A waveform condition storage means for calculating and storing a waveform generation condition including a phase and an amplitude to be generated from the waveform function, and storing in the waveform condition storage means with reference to a trigger generated from the vibration period calculation means A correction waveform generating means for generating a correction signal for correcting the measurement signal from the waveform generation conditions, and a difference between the measurement signal output from the measurement means and the correction signal output from the correction waveform generation means And a correction means for calculating a measurement value of the article.

  According to such a configuration, the vibration correction waveform that approximates the vibration waveform formed in the period of the steady low-period vibration of the conveying means and the waveform of the low-period vibration component superimposed on the no-load measurement signal. Triggers corresponding to the period of steady low-frequency vibrations that the carrier means has, since the waveform generation conditions including phase and amplitude are calculated and stored in order to generate from the basic waveform function with the period calculated by the vibration period calculation means Based on the waveform generation conditions, a correction signal for correcting the weighing signal is generated, and the weighing value of the article is calculated from the difference between the weighing signal output from the weighing means and the correction signal. The correction accuracy can be prevented from deteriorating, and a steady low-period vibration component can be removed without delay and measured with high accuracy.

According to a second aspect of the present invention, in the weighing apparatus according to the first aspect, the waveform condition storage means sets a condition for generating a vibration correction waveform based on a waveform function selected from a plurality of waveform functions. It is calculated and stored.
According to such a configuration, the correction signal is generated by a waveform function selected from among a plurality of waveform functions, so that a correction signal suitable for the operating environment can be generated.

  According to a third aspect of the present invention, in the weighing apparatus according to the first aspect, the waveform condition storage means includes a plurality of waveform functions having the no-load measurement signal and a period calculated by the vibration period calculation means. A condition for generating a vibration correction waveform based on the waveform function set by the learning means, having a learning means for taking a correlation and selecting and setting a waveform function having the highest correlation among the plurality of waveform functions Is calculated and stored.

  According to such a configuration, a condition for generating a vibration correction waveform formed by learning with an unloaded weighing signal and a steady low-period vibration period of the conveying means is the most preferable among a plurality of waveform functions. Since a highly correlated function is set, a correction signal for removing low-frequency vibration components can be generated more accurately, and steady low-frequency vibration components can be removed without delay and measurement can be performed with high accuracy. Can do.

According to a fourth aspect of the present invention, in the weighing device according to the first to third aspects, the vibration period calculating means calculates a period of low-period vibration based on a preset conveying speed of the conveying means. It is characterized by.
According to such a configuration, the vibration period of the low-period vibration can be easily obtained without requiring complicated processing.

The weighing device according to claim 5 is the weighing device according to any one of claims 1 to 3, wherein the vibration period calculation means includes signal analysis means for analyzing a measurement signal to calculate a period, and the no-load measurement signal. Is analyzed by the signal analysis means to calculate the period of the low-frequency vibration.
According to such a configuration, since the vibration period is calculated by analyzing the measurement signal, the vibration period of the low-frequency vibration can be obtained more accurately.

A weighing device according to a sixth aspect of the present invention is the weighing device according to the first to third aspects, further comprising a vibration period detecting unit that is provided in the conveying unit and detects a vibration period of the conveying unit, and the vibration period calculating unit includes: The low-cycle vibration cycle is calculated based on a signal output from the vibration cycle detection means.
According to a seventh aspect of the present invention, in the weighing device according to the sixth aspect, the vibration period detecting means counts pulses from a rotary encoder provided on a rotation shaft of the conveying means to generate low-period vibration. The period is calculated.

  According to such a configuration, since the vibration period detecting means is provided in the conveying means which is the main cause of vibration and the vibration is directly detected, a more accurate vibration period can be obtained.

  According to the first aspect of the present invention, there is a deviation between the vibration waveform formed in the steady low-period vibration cycle of the conveying means and the low-cycle vibration component waveform superimposed on the unloaded weighing signal. To calculate and store a condition for generating a vibration correction waveform that minimizes the condition, and to correct the measurement signal from the condition based on a trigger corresponding to the period of the steady low-cycle vibration of the transport means Correction signal is generated, and the measurement value of the article is calculated from the difference between the measurement signal output from the weighing means and the correction signal, so that deterioration of the correction accuracy due to the phase shift can be prevented, and a steady low-period vibration component Can be accurately measured by removing without delay.

  According to the second aspect of the present invention, the correction signal is generated by the waveform function selected from the plurality of waveform functions, so that the correction signal suitable for the operating environment can be generated.

  According to the invention of claim 3, among a plurality of waveform functions, a condition for generating a vibration correction waveform formed with a constant low-period vibration period of the unloaded weighing signal and the conveying means by learning is obtained. Since the function with the highest correlation is set, it is possible to generate a correction signal for removing the low-frequency vibration component, and it is possible to accurately measure by removing the steady low-frequency vibration component without delay. it can.

  According to the fourth aspect of the present invention, since the vibration period is calculated based on the preset conveyance speed of the conveyance means, the vibration period can be easily obtained without requiring complicated processing.

  According to the invention of claim 5, since the vibration period is calculated by analyzing the measurement signal, the vibration period can be obtained more accurately.

  According to the sixth aspect of the present invention, since the vibration frequency detecting means for detecting the vibration period of the conveying means is provided in the conveying means to calculate the vibration frequency of the conveying means, the vibration from the conveying which is the main cause of the vibration is directly detected. Since it detects, a more exact vibration period can be calculated | required.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[First embodiment]
FIG. 1 is a diagram showing a first embodiment of a weighing device according to the present invention, and is configured as a part of a system for performing weight selection.

  As shown in FIG. 1, the system according to the present embodiment includes a transport unit 10 including a front conveyor 11, a weighing conveyor 12 (transport means), and a rear conveyor 13. An article P is upstream of the front conveyor 11 on the upstream side. Sequentially supplied and placed. The weighing conveyor 12 individually transports the articles P sequentially fed from the front conveyor 11 at a predetermined charging interval, and carries them out to the rear conveyor 13. In addition, a sorting device (not shown) is attached to the rear conveyor 13 so that, for example, a transport destination of a good product with a normal weight and a defective product with excessive or insufficient weight is sorted according to the measurement result of the weighing device. It has become.

  The conveyors 11 to 13 of the transport unit 10 transport the article P by an endless transport belt wound around rollers disposed in the front and rear of the transport direction, and are synchronized by a transport drive mechanism (not shown in detail). Then, the roller is driven to rotate, and the articles P are sequentially fed from the front conveyor 11 to the weighing conveyor 12 (conveying means) at predetermined charging intervals, and are carried out from the weighing conveyor 12 to the subsequent conveyor 13.

  An input detection that sequentially detects the articles P to be input to the weighing conveyor 12 at the position where the articles P are delivered and input from the upstream conveyor 11 to the measuring conveyor 12, that is, in the vicinity of the adjacent portions of both conveyors 11 and 12. A sensor 15 (article detection means) is installed, and the input detection sensor 15 determines whether or not the article P exists on the weighing conveyor 12.

  The weighing conveyor 12 is supported by a weighing table 21 that constitutes a part of the weighing instrument 20 (weighing means), and the weight of the weighing conveyor 12 and the weight of the article P put on the weighing conveyor 12 are measured by the weighing instrument. 20 is loaded. The measuring instrument 20 measures the weight of the input article P detected by the input detection sensor 15 together with the weight of the weighing conveyor 12 serving as a tare, and a weighing signal wg corresponding to the weight of the article P and the weighing conveyor 12 (the article's weight). (Weighing signals related to weight) are output. The measuring device 20 is constituted by, for example, a known strain gauge load cell, but may be a differential transformer type or electromagnetic balance type balance.

  The signal processing means 30 takes in the weighing signal wg output from the measuring instrument 20 and performs filtering by a low-pass filter (not shown) in order to remove high frequency components from the measuring signal output from the measuring instrument 20. ing. The weighing signal wf filtered by the low-pass filter is input to the correction unit to create a weighing value signal from which the low-frequency vibration component is removed, and the weighing value signal from which the low-frequency vibration component is removed is based on the weighing value signal. The measurement value of the article P is output to Then, the measurement value is output to the operation display unit 42 of the weight selection system, and the measurement value of the weight of the article P is also output to the determination unit 41. And in the determination part 41, it is determined whether the measured value of the articles | goods P is in an allowable weight range, and the said distribution apparatus by the side of the back | latter stage conveyor 13 act | operates according to the determination result.

  The signal processing unit 30 includes a vibration period calculation unit 31, a waveform condition storage unit 32, and a correction waveform generation unit 33 in addition to the correction unit 34.

  The vibration period calculation means 31 calculates a steady low-period vibration period of the weighing conveyor 12 and generates a trigger corresponding to the period. In this embodiment, paying attention to the fact that the low-cycle vibration is caused by the rollers of the weighing conveyor 12, the time (2πr / V) that the rollers of the weighing conveyor 12 make one rotation is determined from the belt speed V and the roller radius r of the weighing conveyor. It calculates | requires and calculates as a vibration period of a low period vibration, The trigger which shows a period is output. The belt speed V and the roller radius r of the weighing conveyor are determined when installed on the normal production line. However, if the belt speed V or the like is changed after installation on the production line, the operation display unit 42 Settings can be changed.

  The waveform condition storage means 32 is a waveform of a low-period vibration component superimposed on an unloaded weighing signal wf ′ that has been filtered with respect to the weighing signal wg output from the weighing instrument 20 when the article P is not on the weighing conveyor. A trigger for outputting a vibration correction waveform approximated to wz by adjusting the phase and amplitude from a basic waveform function having a period calculated by the vibration period calculation means 31 and outputting the vibration correction waveform by the vibration period calculation means 31 The waveform generation conditions for re-creating from the starting point are calculated and stored. That is, the phase and amplitude are changed from the basic waveform function that is the basic waveform starting from the trigger, the amplitude almost matches the waveform wz of the low-period vibration component, the phase difference from the basic waveform starting from the trigger, and the waveform The function type, cycle, number of triggers, and the like are stored as waveform generation conditions for the vibration correction waveform.

  Further, the waveform condition storage means 32 displays an operation from a plurality of waveform functions such as a sine wave, a triangular wave, and an impulse response waveform so that a vibration correction waveform suitable for the operating environment installed in the production line can be generated. Selection can be performed by the unit 42.

  For example, the vibration correction waveform when a sine wave is selected as the waveform function is as shown in FIG. The basic waveform of the sine wave shown in FIG. 3B can be obtained using the trigger output from the vibration period calculating means 31 shown in FIG. 3A as the starting point of the vibration waveform. On the other hand, if the waveform wz of the low-period vibration component superimposed on the no-load measurement signal at this time is shown in FIG. 3D, the waveform wz of the low-period vibration component superimposed on the no-load measurement signal The approximate vibration correction waveform is as shown in FIG. 3C, and the stored amplitude, phase difference, and period are A, θ, and T, respectively.

Note that the waveform condition storage means 32 that calculates and stores the condition of the vibration correction waveform in a state where the article P is not present on the weighing conveyor 12 without determining the measurement value of the article P is performed in the learning mode. Is called. And this learning mode is instruct | indicated by the operation display part 42, and the calculation and the memory | storage of the conditions of a vibration waveform are performed. Further, for example, as shown in FIG. 2, a measurement signal switching unit 35 may be provided so that the measurement signal is input to the waveform condition storage unit only in the learning mode.
In addition to the case where the operation display unit 42 instructs the learning mode, for example, the period when the article P does not exist on the weighing conveyor 12 is detected by the input detection sensor 15, and the article P is detected during a predetermined period. If no is present, the learning mode may be determined, and the waveform generation condition of the vibration correction waveform may be calculated and stored.

  The correction waveform generation unit 33 corrects the measurement signal from the waveform generation condition for generating the vibration correction waveform stored in the waveform condition storage unit 32 with the trigger output from the vibration period calculation unit 31 as a reference. A correction signal wc is generated. For example, the vibration waveform when the waveform function is selected as a sine wave is as shown in FIG. A sine wave shown in FIG. 4B is based on the stored amplitude A, phase difference θ, and period T with the trigger output from the vibration period calculating means 31 shown in FIG. 4A as the starting point of the vibration waveform. Is generated as the correction signal wc.

  The correction means 34 takes the difference between the measurement signal wf from which the high-frequency component has been removed by the low-pass filter and the correction signal wc generated by the correction waveform generation means 33, so that the noise of the high-frequency component and the steady low-frequency component can be reduced. A removed weighing value signal is created, this weighing value signal is converted into a weight, and a subtraction process for subtracting the weighing value of the weighing conveyor 12 from the weighing value converted into the weight by an internal subtractor (not shown) is performed, A metric value of the weight of the article P is calculated. The weighing value of the weighing conveyor 12 subtracted here is the weighing signal wf ′ from which the high-frequency component has been removed by the low-pass filter from the unloaded weighing signal wg ′ output from the weighing instrument 20 without the article P on the weighing conveyor 12. This is a measured value converted to weight by taking a difference from the correction signal wc.

The measurement configuration of the present embodiment has been described above. The determination unit 41 and the signal processing unit 33 include a CPU, a ROM, a RAM, and an input / output interface circuit, and are configured by program modules executed by the CPU. May be.
In addition, there is an unloaded weighing signal output from the weighing unit and a weighing signal input to the correction unit 34 in a state where the article P is not present on the weighing conveyor 12 used when calculating the conditions for generating the vibration correction waveform. The weighing signal wf from which the high-frequency component has been removed by the low-pass filter is used, but the weighing signal wg output from the measuring instrument 20 before the high-frequency component is removed by the low-pass filter is used, and the difference is corrected by the correction means. After taking, a high-frequency component may be removed by a low-pass filter to create a measurement value signal, and the measurement value may be calculated by converting to a weight.

  Next, in order to generate a vibration correction waveform that approximates the waveform wz of the low-period vibration component superimposed on the unloaded measurement signal from the basic waveform function starting from the trigger, how to obtain the phase and amplitude A case where a sine wave is selected as a function will be described.

When the sine wave correction signal wc is created based on the period calculated by the vibration period calculation means, the waveform function C (k) that becomes the correction signal wc is expressed as in equation (1).
C (k) = A · sin ((2π · Ts · k) / T + θ) (1)
A: amplitude, θ: phase difference, T: period of low-period vibration, Ts: sampling period,
k = 0,1,2, ... (Number of samplings when k = 0 when the period of the rotating body is detected)

  On the other hand, the waveform wz of the low-period vibration component superimposed on the unloaded weighing signal is shown in FIG. 3 with the trigger output from the vibration period calculating means 31 as the starting point of the vibration waveform as shown in FIG. The amplitude and phase are different from the basic waveform of the sine wave shown in (b). Therefore, if the phase and amplitude are determined so that the waveform function C (k) matches a sine wave as shown in FIG. 3D, the waveform function C (k) is superimposed on the unloaded weighing signal. It can be approximated to the waveform wz of the periodic vibration component.

  As for the amplitude of the waveform function C (k), the peak value is detected when the waveform wz of the low-period vibration component is sampled at intervals of Ts starting from the trigger output from the vibration period calculation means 31. The amplitude A1 of the waveform wz of the low-period vibration component obtained by subtracting the first negative peak value (negative value) from the positive peak value to ½ is defined as A of the waveform function C (k). .

The phase of the waveform function C (k) detects a peak value when the waveform wz of the low-period vibration component is sampled at intervals of Ts starting from the trigger output from the vibration period calculation means 31. It can be obtained from the time tp until the first positive peak value is detected. That is, here, since the relationship of (2π · tp) / T + θ1 = π / 2 holds, the phase θ1 can be obtained by the equation (2).
θ1 = π / 2− (2π · tp) / T (2)
Furthermore, since the time tp until the first positive peak value is detected is obtained by multiplying the sampling period Ts by the number of sampling times kp, the expression (2) becomes the expression (3).
θ1 = π / 2− (2π · Ts · k) / T (3)
Then, θ1 obtained by the equation (3) is set as θ of the waveform function C (k).

  The amplitude A and the phase θ of the waveform function C (k) are obtained from the amplitude A1 and the phase θ1 of the waveform wz of the low-period vibration component that is initially obtained from the trigger output from the vibration period calculation means 31. When the amplitude and period of the waveform wz of the low-period vibration component fluctuate, the average value of the amplitude and the average value of the phase for a predetermined period may be calculated and used as the amplitude A and the phase θ of the waveform function C (k). .

  Further, the amplitude A and the phase θ of the waveform function C (k) are individually obtained from the amplitude peak of the waveform wz, but the waveform function X (k of the low-period vibration component is obtained by functionalizing the waveform wz of the low-period vibration component. ), The amplitude A is obtained from the waveform function X (k), the amplitude A is set to the waveform function C (k), the phase of the waveform function C (k) is changed, and the waveform function X (k) The phase when the waveform functions C (k) coincide may be obtained. Alternatively, after obtaining the phase difference between the waveform function X (k) and the waveform function C (k) and matching the phases of the waveform function X (k) and the waveform function C (k), the amplitude of the waveform function C (k) is changed. Thus, the amplitude when the waveform function X (k) and the waveform function C (k) match may be obtained.

  In the weighing device and the weight selection system of the present embodiment configured as described above, the vibration correction waveform that approximates the vibration waveform and the waveform of the low-period vibration component superimposed on the no-load measurement signal is obtained by the vibration period calculation means. Calculates and stores waveform generation conditions including phase and amplitude for generation from the basic waveform function with the calculated period, and stores the waveform based on the trigger corresponding to the period of the steady low-frequency vibration of the transport means A correction signal for correcting the weighing signal is generated from the generation conditions, and the weighing value of the article is calculated from the difference between the weighing signal output from the weighing means and the correction signal. It can be removed without delay and weighed with high accuracy.

  In this embodiment, since the time for which the roller of the weighing conveyor rotates once is calculated from the belt speed and the radius of the roller of the weighing conveyor, it is calculated as the vibration cycle of the low cycle vibration, and the trigger indicating the cycle is output. Thus, the vibration period can be easily obtained without requiring complicated processing.

[Second Embodiment]
FIG. 5 is a diagram showing a second embodiment of the weighing device of the present invention, and is configured as a part of a system for performing weight selection. The present embodiment is the same as the first embodiment except for the configuration and operation relating to the vibration period calculation means and the waveform condition storage means, and therefore the same configuration as the first embodiment is shown in FIG. Differences will be described using the same reference numerals.

  In the present embodiment, the stationary low-cycle vibration period of the conveying means 10 is detected from the measurement signal output from the measurement means. In order to detect the low-period vibration period from the measurement signal, FIG. 5, the vibration period calculation means 51 has a signal analysis means 54, which calculates the period of the low frequency vibration based on the period of the low frequency vibration analyzed by the signal analysis means 54 and outputs a trigger. It has become.

  The waveform condition storage means 51 correlates the unloaded weighing signal and a plurality of waveform functions having the period calculated by the vibration period calculating means, and selects the waveform function having the highest correlation among the plurality of waveform functions. A learning unit 53 for calculating is provided, and a condition for generating a vibration correction waveform is calculated and stored based on the waveform function calculated by the learning unit 53.

  The signal analysis means 54 detects the peak value of the alternating current component of the weighing signal wf obtained by filtering the weighing signal output from the weighing instrument 20 with a low-pass filter, calculates the vibration period, and triggers based on the detected peak value. Is output. For example, as shown in FIG. 6A, a trigger is output as shown in FIG. 6B with reference to the negative peak value.

  The learning unit 53 is performed when the learning mode is instructed from the operation display unit 42, and the low-frequency vibration is generated with respect to the unloaded weighing signal wg output from the weighing instrument 20 in a state where the article P is not on the weighing conveyor 12. The vibration signal wb in the frequency band is extracted by filtering with a band pass filter. The extracted vibration signal wb is correlated with a plurality of waveform functions, and the waveform function having the highest correlation among the plurality of waveform functions is selected and set. For example, the plurality of waveform functions for correlating are sine waves having the same period and the same phase amplitude as the signal wb, and the sine of the amplitude that minimizes the difference from the amplitude of the signal wb when the amplitude is varied. The wave is selected and set as the waveform function having the highest correlation among the waveform functions.

  As shown in FIG. 6, the waveform condition storage means 51 calculates the phase difference θ from the trigger signal output from the vibration period calculation means 52 based on the waveform function (FIG. 6C) set by the learning means 53. It is obtained and stored together with the waveform function C (k) and amplitude A set by the learning means 53.

  In the present embodiment, the signal analyzing unit 54 outputs a trigger based on a signal obtained by filtering the weighing signal from the measuring instrument 20, but is output from the measuring instrument 20 in the learning mode. If the weighing signal is filtered by a bandpass filter in the low-frequency vibration frequency band and the trigger is output at the determined vibration period interval, it will not be affected by other noises. A trigger corresponding to a steady low-period vibration can be generated.

  In the present embodiment configured as described above, a plurality of waveform generation conditions for generating a vibration correction waveform formed with a constant low-cycle vibration cycle of the unloaded weighing signal and the conveying means by learning are set. Since the function with the highest correlation among the waveform functions is set, a correction signal for removing the low-frequency vibration component can be generated more accurately, and the steady low-frequency vibration component can be removed without delay. Can be measured with high accuracy.

[Third embodiment]
FIG. 7 is a diagram showing a third embodiment of the weighing device of the present invention, and is configured as a part of a system for performing weight selection. Since the present embodiment is the same as the first embodiment except for the configuration and operation related to the vibration period calculation means, the same reference numerals as those shown in FIG. 1 are used for the same configurations as the first embodiment. Differences will be described with reference to FIG.

  In this embodiment, it is the structure which detects directly the period of the regular low cycle vibration which a conveyance means has from the conveyance part 10, and in order to detect directly from the conveyance part 10, as shown in FIG. A vibration period detecting means 62 is provided on the rotating body. The vibration cycle calculation means 61 receives the detection signal from the dynamic cycle detection means, calculates the period of the low cycle vibration, and outputs a trigger.

  For example, the vibration cycle detecting means 62 is a rotary encoder provided on the rotating shaft of the roller of the weighing conveyor, and the vibration cycle calculating means 61 is output from the rotary encoder by the rotation of the rotating shaft of the roller of the weighing conveyor. The number of pulses (FIG. 8 (1)) is counted, and the period of low-period vibration generated by the rotation of the rollers of the weighing conveyor is calculated from the time when the number of pulses reaches the number of pulses of one rotation of the rotary encoder. A trigger (FIG. 8 (2)) is output every time the rotary encoder makes one rotation.

In this embodiment, the low-cycle vibration cycle is calculated by the rotary encoder provided on the roller of the weighing conveyor. However, the vibration cycle detection unit that detects the low-cycle vibration of the transport unit is, for example, a rotating shaft. Alternatively, the rotation period of the rotating shaft may be detected by detecting a mark, a hole, a notch or the like made on the disk provided on the rotating shaft with a photo sensor or the like. Further, the rotating shaft is not limited to the rotating shaft of the roller, but may be a rotating shaft such as a drive motor or a transmission.
Further, the vibration period detecting means for detecting the low period vibration of the conveying means is not limited to the rotating shaft, but may be any periodic signal related to the period of the low periodic vibration source. For example, a mark is attached to the conveying belt of the weighing conveyor. For example, the conveying speed may be detected by detecting the mark and converted into the period of the low-frequency vibration source.

  In the present embodiment configured as described above, since the vibration means for detecting the vibration period of the conveying means is provided in the conveying means, the vibration of the conveying means which is the main cause of vibration is directly detected, and more Since the correction can be made from an accurate vibration cycle, the measurement accuracy is improved.

  As described above, the correction signal for removing the steady low-period vibration of the conveying unit is generated, and the weighing value of the article is calculated from the difference between the weighing signal output from the weighing unit and the correction signal. Therefore, it is useful for all weighing devices equipped with a conveying means.

1 is a block diagram showing a schematic configuration of a weighing device according to a first embodiment of the present invention. It is a block diagram which shows the other schematic structure of the signal processing means in the measuring apparatus which concerns on the 1st Embodiment of this invention. It is a timing chart which shows the waveform of the cycle of a low cycle vibration, the waveform function, and the waveform of an unloaded measuring signal in the measuring device concerning a 1st embodiment of the present invention. It is a timing chart which shows the period and correction signal of the low period vibration in the measuring device concerning a 1st embodiment of the present invention. It is a block diagram which shows schematic structure of the weighing | measuring device which concerns on the 2nd Embodiment of this invention. It is a timing chart which shows the period of a low period vibration, the waveform function, and the waveform of an unloaded measurement signal in the measuring device concerning a 2nd embodiment of the present invention. It is a block diagram which shows schematic structure of the weighing | measuring device which concerns on the 3rd Embodiment of this invention. It is a timing chart which shows the period of a low cycle vibration, the waveform function, and the waveform of an unloaded measuring signal in the measuring device concerning a 3rd embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Conveyance part 11 Pre-stage conveyor 12 Weighing conveyor (conveyance means)
13 Subsequent conveyor 15 Input detection sensor (article detection means)
20 Weighing device (measuring means)
DESCRIPTION OF SYMBOLS 21 Weighing table 30 Signal processing means 31, 51, 61 Vibration period calculation means 32, 52 Waveform condition storage means 33 Correction waveform generation means 34 Correction means 35 Weighing signal switching means 37 Zero set means (zero point correction means)
39 Display / Operation Unit 40 Filter Setting Unit (Zero Point Correction Unit)
41 Determination Unit 42 Display / Operation Unit 53 Signal Analysis Unit 54 Learning Unit 62 Vibration Period Detection Unit

Claims (7)

Transport means (10) for transporting articles (P) that are sequentially placed at a predetermined throw-in interval;
Weighing means (20) for weighing the article together with the conveying means to output a weighing signal related to the weight of the article;
Vibration period calculating means (31, 51, 61) for calculating a period of steady low-period vibration possessed by the conveying means and generating a trigger corresponding to the period;
A vibration correction waveform that approximates the waveform of a low-period vibration component superimposed on an unloaded weighing signal output from the weighing means when there is no article in the conveying means is a cycle calculated by the vibration period calculating means. Waveform condition storage means (32, 52) for calculating and storing a waveform generation condition including a phase and amplitude for generation from a basic waveform function;
Correction waveform generation means (33) for generating a correction signal for correcting the measurement signal from the waveform generation conditions stored in the waveform condition storage means with reference to the trigger generated from the vibration period calculation means;
A weighing apparatus comprising: a correction unit (34) that calculates a weighing value of the article based on a difference between a weighing signal output from the weighing unit and a correction signal output from the correction waveform generation unit.   The waveform condition storage means (32) calculates and stores a condition for generating a vibration correction waveform based on a waveform function selected from a plurality of waveform functions. Weighing equipment. The waveform condition storage means (52) correlates the unloaded weighing signal with a plurality of waveform functions having the period calculated by the vibration period calculation calculating means, and is the most correlated among the plurality of waveform functions. Learning means (53) for selecting and setting a high waveform function,
2. The weighing apparatus according to claim 1, wherein a condition for generating a vibration correction waveform is calculated and stored based on the waveform function set by the learning means.   The weighing apparatus according to any one of claims 1 to 3, wherein the vibration period calculating means (31) calculates a period of low-period vibration based on a preset conveying speed of the conveying means. .   The vibration period calculating means (51) has signal analysis means for calculating a period by analyzing a measurement signal, and analyzing the unloaded measurement signal by the signal analysis means (54) to obtain a period of low-period vibration. The weighing device according to claim 1, wherein the weighing device is calculated. Provided with a vibration period detecting means (62) provided in the conveying means for detecting a vibration period of the conveying means;
The weighing apparatus according to any one of claims 1 to 3, wherein the vibration period calculating means (61) calculates a period of low-period vibration based on a signal output from the vibration period detecting means.   The weighing apparatus according to claim 6, wherein the vibration period detecting means (62) calculates a period of low-period vibration by counting pulses from a rotary encoder provided on a rotating shaft of the transport means. .

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