JP5658594B2 - Weighing device - Google Patents

Description

  The present invention relates to a weighing device that measures quality by weighing an object to be weighed such as meat, fish, processed food, and medicine.

  2. Description of the Related Art Conventionally, in a production line for foods, etc., articles that are incorporated into the production line are sequentially carried in from the front stage, weighed while transporting the carried-in articles, and are removed from the production line by carrying out or sorting to the subsequent stage. A weighing device is used. This type of weighing device has a configuration of an electromagnetic balance type balance, and includes a weighing table, position detecting means for detecting displacement of the weighing table from a predetermined position due to a load change, and a force against the load. An electromagnetic coil to be applied to the weighing platform, a control voltage output device for receiving a detection signal from the position detecting means and outputting a control voltage according to the load, and driving the electromagnetic coil with a current according to the control voltage, And a current conversion circuit that suppresses displacement from the position, and even when there is a sudden input, a technique is known in which the current flowing in the electromagnetic coil is changed quickly following the control voltage. (For example, refer to Patent Document 1).

  Since such a weighing device is installed in a production line, floor vibrations caused by other production equipment, low-cycle vibration components due to the rollers and belts of the weighing conveyor, etc., become noise components in the output signal of the weighing instrument. Superimposing constantly is a factor that deteriorates the weighing accuracy. At present, low frequency components are removed by lowering the cut-off frequency of the LPF. In this case, however, there is a problem that the measurement time becomes longer due to the deterioration of responsiveness and the production capacity is lowered.

  Also, in the weighing device, zero set is performed according to the article insertion interval to correct the zero point deviation due to temperature and article residue during operation, but it is sufficient to remove low frequency components as well as weighing. Since the LPF is used, there is a problem that the time required for zero setting becomes long and the measuring ability is lowered, and it is difficult to perform zero setting when the article input interval is short.

  Thus, a measuring device is known that generates an antiphase component of a vibration component and removes periodic vibration by a synchronous sensor (see, for example, Patent Document 1).

JP 2008-268068 A

  However, the conventional weighing device as disclosed in Patent Document 1 has a problem that only periodic vibrations can be removed and a separate synchronization sensor is required.

  Therefore, the present invention was made to solve the conventional problems as described above, and can remove low-frequency vibration components without affecting responsiveness, and can accurately measure and zero-set at high speed. An object of the present invention is to provide a weighing device that can be used.

The weighing device according to the present invention detects a displacement from a predetermined position of the weighing table due to a load change caused by a load change caused by a weighing object and a conveying unit that conveys the objects to be weighed sequentially on the weighing table under a predetermined conveying condition. Position detection means for outputting a displacement detection signal, an electromagnetic coil for applying a force opposite to the load to the weighing table, and a displacement detection signal from the position detection means, and suppressing displacement of the weighing table from a predetermined position A drive control means for driving and controlling the electromagnetic coil, a weighing signal output means for outputting a weighing signal corresponding to a current value flowing through the electromagnetic coil, and a displacement detection signal from the position detection means. Extraction means for extracting the remaining external vibration component, phase correction means for performing phase correction on the extracted external vibration component, and a predetermined sensitivity ratio with respect to the phase-corrected external vibration component Amplitude correction means for correcting the amplitude and the weighing signal output from the weighing signal output means, the amplitude-corrected external vibration component is added in the opposite phase or subtracted in the same phase, and the external vibration component from the weighing signal. Signal synthesizing means, a sensitivity ratio storing means for storing in advance a plurality of sensitivity ratios used by the amplitude correcting means, and a weighing signal from the signal synthesizing means when there is no object to be weighed on the weighing platform. Sensitivity ratio setting means for selecting a sensitivity ratio that minimizes the extraneous vibration component remaining in the weighing signal from the signal synthesizing means from among a plurality of sensitivity ratios stored in the sensitivity ratio storage means, and setting and updating the sensitivity ratio setting means in the amplitude correction means If, determine the metering means, the quality of the metering means by comparing the weight value and the acceptability criteria as calculated by the objects to be weighed to calculate the weight value of the weighing signal receiving objects to be weighed from the signal synthesizing means A quality determining means for, characterized by comprising a.

  With this configuration, the external vibration component remaining in the displacement detection signal is extracted from the displacement detection signal from the position detection means by the extraction means, and the phase and amplitude are extracted from the extracted external vibration component by the phase correction means and the amplitude correction means. The signal is added to the weighing signal output from the weighing signal output means in the opposite phase or subtracted in the same phase by the signal synthesizing means to remove the extraneous vibration component from the weighing signal. For this reason, since the external vibration component is extracted at the same time as the weighing signal is acquired, there is no delay time for calculating the external vibration component as in the conventional case, and the low frequency vibration component is not affected without affecting the response. Can be removed. Further, since the external vibration component is extracted simultaneously with the acquisition of the weighing signal, it can be measured and zero-set with high accuracy at high speed.

Therefore, the low frequency vibration component can be removed without affecting the responsiveness, and measurement and zero setting can be performed at high speed with high accuracy. Further, since the optimum sensitivity ratio is selected from the sensitivity ratio storage means by the sensitivity ratio setting means and set in the amplitude correction means, the extraneous vibration component remaining in the weighing signal from the signal synthesis means can be minimized.

  Further, the measuring device according to the present invention is characterized in that a plurality of the extraction means, the phase correction means, and the amplitude correction means are provided for each of a plurality of different bands.

  With this configuration, a plurality of external vibration components having different bands can be removed by the signal synthesis unit.

  The present invention can provide a weighing device that can remove a low-frequency vibration component without affecting responsiveness, and can perform weighing and zero-setting at high speed with high accuracy.

It is a perspective view which shows the outline | summary of the weighing | measuring device which concerns on one embodiment of this invention. It is a block diagram which shows the internal structure of the weighing | measuring device which concerns on one embodiment of this invention. It is a side view which shows the conveyance part of the weighing | measuring device which concerns on one embodiment of this invention. It is a figure which shows the principal part of the weighing means and the control means of the weighing | measuring apparatus which concerns on one embodiment of this invention. It is a figure which shows the suitable example of the principal part of the weighing means and control means of the weighing | measuring device which concerns on one embodiment of this invention. (A) is a figure which shows the load change and external vibration component of the weighing means at the time of the to-be-measured object passage of the weighing | measuring device based on one embodiment of this invention, (b) is a figure which shows a weighing signal and an external vibration component. (C) is a figure which shows the extracted external vibration component.

  Hereinafter, embodiments of a weighing device according to the present invention will be described with reference to the drawings.

  1 to 4 show an embodiment of a weighing device according to the present invention.

  As shown in FIGS. 1 to 4, the weighing device 1 includes a device main body 2, a transport unit 3, and a carry-in sensor 4. A sorting unit 5 is connected to the subsequent stage of the weighing device 1.

  The weighing device 1 is installed on the downstream side of the belt conveyor 14 constituting a part of the production line, and is to be weighed for meat, fish, processed foods, pharmaceuticals, etc. that are sequentially carried in the direction of arrow A at predetermined intervals. The weight of the object W is measured, and the obtained measurement value is output as a measurement result. Furthermore, it compares with the reference value of the upper limit and the lower limit of the preset weight, respectively, determines whether or not the obtained measurement value is within the range of the reference value, makes the one in the range a non-defective product, and out of the range It may be determined whether the product is defective or not, or the weight rank is determined corresponding to a plurality of reference values. In addition, the measurement result, the pass / fail determination result, and the weight rank determination result are displayed on the display unit 10 and are output to the selection unit 5 connected to the subsequent stage of the weighing device 1. The sorting unit 5 distributes the objects to be weighed W according to the measurement result output from the weighing device 1, the pass / fail determination result, and the weight rank determination result.

  The apparatus main body 2 includes a weighing unit 21, a general control unit 7, a display unit 10, a setting unit 11, and a housing 2a that houses these units.

  The conveyance unit 3 is configured to convey the object W to be weighed in from the belt conveyor 14 in the direction of arrow A under predetermined conveyance conditions. The object to be weighed W is conveyed by being accelerated or decelerated so as to have an optimum speed for measurement by the run-up conveyor 31, further conveyed by the weighing conveyor 32, and the weight is measured by the weighing means 21 while being conveyed. It has become so. The weighing conveyor 32 is configured to convey an object to be weighed according to predetermined conveyance conditions. In addition, the object to be weighed W is further transported to the sorting unit 5 in the subsequent stage after the weighing and is distributed.

  The transport unit 3 includes a running conveyor 31 and a weighing conveyor 32. The run-up conveyor 31 performs the run-up of the object to be weighed W before the object to be weighed W conveyed from the preceding belt conveyor 14 moves to the weighing conveyor 32, and includes two rollers 31a and 31c, And an endless conveying belt 31b wound around the roller. The weighing conveyor 32 is supported by the upper part of the weighing means 21 for weighing the workpiece W, and is composed of two rollers 32a and 32c and an endless conveying belt 32b wound around these rollers. Yes.

  The carry-in sensor 4 is configured by a transmission photoelectric sensor including a pair of light projecting units 4 a and light receiving units 4 b, and is disposed between the run-up conveyor 31 and the weighing conveyor 32. Specifically, the light projecting unit 4a is disposed on the apparatus main body 2 side of the transport belt 32b, and the light receiving unit 4b is disposed on the other side of the transport belt 32b so as to face the light projecting unit 4a. When the object to be weighed W passes between the light projecting part 4a and the light receiving part 4b, the light receiving part 4b is shielded by the object to be weighed, so that it is detected that the carry-in of the object to be weighed W is started. It has become. The detected carry-in start signal is output to the general control unit 7 in the apparatus main body 2.

  The weighing means 21 is a load sensor that supports the weighing conveyor 32 and outputs a weighing signal based on the load of the object to be weighed, has a configuration of an electromagnetic balance type balance, and the object to be weighed W is conveyed by the weighing conveyor 32. During this time, the load applied to the weighing means 21 is measured.

  Specifically, as shown in FIG. 4, the weighing means 21 includes a suspension plate 85 that moves up and down together with the weighing conveyor 32, a parallel spring 86 that suspends the suspension plate 85, and one end fixed to the suspension plate 85. 82, a fulcrum 81 that supports the cage 82, a position sensor 83 that detects the position of the other end of the cage 82 and outputs a displacement detection signal, and a magnet 88 that applies a force to the other end of the cage 82 The coil application unit 92 is controlled by servo control such as PID control based on the displacement detection signal from the position sensor 83 so that the pole 82 is balanced based on the displacement detection signal from the position sensor 83. And a servo control unit 91 for performing the operation. Note that one end of the parallel spring 86 is fixed to the suspension plate 85, but the other end is fixed to a common base 87 with the fulcrum 81 and the electromagnetic coil 84, thereby constituting a Roverval mechanism. .

  In the electromagnetic balance type balance as the weighing means 21, the balance of the cage 82 is balanced when there is no load, and when the object W is placed on the weighing conveyor 32, the balance around the fulcrum 81 is lost, and The inclination is detected by the position sensor 83, and a current is passed through the electromagnetic coil 84 so that the inclination is zero, so that the current is proportional to the weight of the object W. The value can be converted to grams. That is, the load generated by the mass of the object W to be measured and the force generated by the current flowing through the magnet 88 and the electromagnetic coil 84 are balanced, and the current value flowing through the electromagnetic coil 84 at this time is measured as the weight of the object W to be inspected. .

  The comprehensive control unit 7 includes a signal processing unit 71, a weighing unit 72, a storage unit 73, a control unit 74, a quality determination unit 76, and a mode switching unit 77.

  The signal processing means 71 receives the weighing signal from the weighing means 21 and performs signal processing based on predetermined signal processing conditions to output a signal-processed weighing signal, and converts an analog signal into a digital signal. An A / D converter is provided. Specifically, the signal processing means 71 has signal-processed only the low-frequency component of the weighing signal using a filter selected from a plurality of low-pass filters of different types and characteristics with respect to the weighing signal from the weighing means 21. Is passed as a weighing signal. The signal processing means 71 may select one low-pass filter or a combination of a plurality of low-pass filters. As this low-pass filter, there are a FIR (Finite Impulse Response) filter and an IIR (Infinite Impulse Response) filter. Here, the FIR filter is a finite impulse response filter that outputs an output for a predetermined time (finite time) when an impulse response waveform is input, and the IIR filter outputs an attenuation waveform of the impulse response waveform infinitely. This is an infinite impulse response filter.

  Here, the FIR filter constitutes a low-pass filter that passes a predetermined low-frequency component with respect to the weighing signal converted into a digital signal by the A / D converter, and uses a simple averaging process or a Kochi window function. Weighted averaging processing is performed. The IIR filter is an analog filter that directly receives a weighing signal (analog weighing signal) from the weighing means 21 and outputs a processed signal to the A / D converter using hardware whose characteristics can be changed, such as a switched capacitor filter. Or a digital filter that receives a digital weighing signal (not shown) from the A / D converter.

  Specifically, as shown in FIG. 4, the signal processing means 71 is detected with a current detection resistor 93 connected in series to the electromagnetic coil 84 in order to detect the current flowing through the electromagnetic coil 84 of the weighing means 21. An amplifier 94 for amplifying the amplified signal, an A / D converter 96 for digitally converting the amplified signal, and a filter 97 for filtering the digitally converted signal.

  The weighing means 72 calculates (measured in grams) the measured value of the object W based on the signal-processed weighing signal output from the signal processing means 71. Further, in the weighing means 72, a predetermined reference time Tk has elapsed after the carry-in sensor 4 detects that the object to be weighed W has been carried into the weighing conveyor 32, and the weighing signal from which the weighing signal has been output from the weighing means 21. A measurement value is calculated for the object W. Individual weights calculated by the weighing means 72 are stored in the storage means 73 as calculation data.

The weighing unit 72 performs weighing when a preset reference time Tk has elapsed after the carry-in sensor 4 detects that the workpiece W has been carried into the weighing conveyor 32. Here, the reference time Tk is detected by the loading sensor 4 that the object to be weighed W has started to be loaded onto the weighing conveyor 32, and then the weighing object W is completely transferred to the weighing conveyor 32, and further from the weighing means 21. This means the time required for the output weighing signal to stabilize. Specifically, the reference time Tk is the speed of the weighing conveyor 32 (m / min), the length of the weighing conveyor 32 in the direction of arrow B (mm), and the length of the weighing object W in the direction of arrow B, which is the conveyance direction. (Mm), the size of the workpiece W, the processing capacity of the line, and other conditions. Further, as shown in FIG. 3, the reference time Tk has elapsed, the objects to be weighed W is moved by L ₁ reaches the mass measuring position P _S from the loading start detection position P _O, metering is performed.

  In the weighing means 72, inspection conditions (parameters) such as the measurement range, measurement capability, and inspection accuracy are selected according to the type (particularly size) of the object to be weighed W. Depending on the type of the weighing object W, for example, the measurement range is selected from 6 g to 600 g, and the measurement capability is selected at a maximum of 150 pieces / min. In this case, the reference time Tk per object W is set to a minimum of 400 msec, and the reference time Tk may be 400 msec or more. It is set according to capacity, production and other conditions. Since the reference time Tk is measured in a shorter time as it is closer to 400 msec, the inspection efficiency is increased, and as the distance is longer, the inspection time is longer, but the weighing accuracy is increased because it is stably conveyed on the weighing conveyor 32. Become.

  Further, according to the type of the object to be weighed W, for example, the measurement range is selected from 1 g to 300 g, and the measurement capability is selected at a maximum of 600 pieces / min. If the measurement capacity is 600 pieces / min at the maximum, the measurement time per piece of the object to be weighed W is set to a minimum of 100 msec, and the size of the object to be weighed W, the processing capacity of the line, production, etc. It is set according to the conditions. Since the reference time Tk is measured in a shorter time as it is closer to 100 msec, the inspection efficiency is increased. As the distance is longer, the inspection time is longer, but the weighing accuracy is increased because the weighing conveyor 32 is stably conveyed. In this way, in the weighing means 72, the inspection conditions (parameters) such as the range and capability are selected according to the type of the object to be weighed W.

  The storage means 73 is composed of a storage medium and the like, and the condition parameters including the predetermined transport condition of the object W to be weighed by the weighing conveyor 32 and the predetermined signal processing condition in the signal processing means 71 are the types of the object W to be weighed. It corresponds to memorize. The storage unit 73 stores a conveyance speed and LPF (Low Pass Filter) characteristics corresponding to each type number assigned to each type of the object to be weighed W. Further, the storage means 73 stores a non-defective range for determining the quality of the object W to be weighed. The conveyance speed is the speed of the conveyance unit 3 that conveys the workpiece W, the LPF characteristic indicates what characteristic the low-pass filter is, and the non-defective range is the non-defective product range. This is the range of the weight of the weighing object W. The stored information is stored in advance by a setting operation from the setting unit 11 or connection with an external device. The storage means 73 stores various data such as measurement values and non-defective product determination results.

  The control means 74 reads out a predetermined transport condition and a predetermined signal processing condition from the storage means 73 in accordance with the type of the object to be weighed W, and controls the weighing conveyor 32 and the signal processing means 71, respectively. Further, the transport unit 3 and the signal processing unit 71 are controlled by sequentially switching condition parameters corresponding to a plurality of types stored in the storage unit 73. Further, the control means 74 is configured to drive and control the rotational speed (rpm) of a motor (not shown) so as to control the transport speed of the workpiece W by the transport unit 3.

  The pass / fail judgment means 76 is for judging pass / fail of the object to be weighed W. The pass / fail judgment means 76 is constituted by a judgment circuit and the like, and compares the weight value calculated by the weighing means 72 with the pass / fail judgment criteria to determine the pass / fail of the object W It comes to judge. Specifically, the quality determination unit 76, when receiving the weight signal of the object W output from the weighing unit 72, reads the upper limit value Ga and the lower limit value Gb of the weight stored in advance in the storage unit 73, The calculated weight of the object to be weighed is compared with the upper limit value Ga and the lower limit value Gb, respectively, and whether the weight of the object to be weighed W is within the allowable range determined by the upper limit value Ga and the lower limit value Gb. It is to judge whether.

  The determination result determined by the quality determination unit 76 is output to the display unit 10 and displayed as a non-defective product or a defective product. The determination result is output to the sorting unit 5 connected to the subsequent stage of the weighing device 1 so that the object to be weighed W is sorted as a non-defective product or a defective product. Further, the determination result is output to the storage means 73, and the determination result for each object W is stored.

  The mode switching unit 77 issues a command to the control unit 74 and switches the operation mode of the weighing device 1 between the operation mode and the setting mode. Here, the operation mode is a normal operation mode in which the weighing apparatus 1 performs weighing, weight calculation, and pass / fail judgment of the object to be weighed. The setting mode refers to various parameters for operation in the operation mode. This is an operation mode for confirming whether or not the operation of the operation mode can be performed normally. The mode switching unit 77 switches the operation mode to the setting mode according to an input operation from the setting unit 11 or switches the operation mode to the setting mode at the start of operation of the apparatus.

  The overall control unit 7 includes a BPF 103, a phase correction unit 104, an amplitude correction unit 105, and a signal synthesis unit 108.

  The BPF 103 extracts an extraneous vibration component remaining in the displacement detection signal from the displacement detection signal from the position sensor 83, and is composed of a band pass filter. Since the displacement detection signal from the position sensor 83 remains due to the limit of the control performance of the servo control unit 91 and the like, the vibration component can be detected from the output signal of the position sensor 83.

  The phase correction unit 104 performs phase correction on the external vibration component extracted by the BPF 103. Since there is a phase difference between the weighing signal and the output signal of the position sensor 83 due to the servo control, the phase correction unit 104 takes into account the phase characteristics of the servo control in the vibration component band from the displacement detection signal. The phase of the extracted external vibration component is corrected.

  The amplitude correction unit 105 corrects the amplitude of the external vibration component whose phase has been corrected by the phase correction unit 104 with a predetermined sensitivity ratio. As described above, the phase correction unit 104 and the amplitude correction unit 105 respectively adjust the phase and amplitude of the signal for removing the extraneous vibration component included in the weighing signal from the signal processing unit 71 in the subsequent signal synthesis unit 108. It is like that.

  The signal synthesizing unit 108 adds or subtracts the external vibration component whose amplitude is corrected by the amplitude correcting unit 105 to the weighing signal output from the signal processing unit 71 in the opposite phase or in the same phase. The extraneous vibration component is removed from the weighing signal output from the.

  Further, as shown in FIG. 4, the general control unit 7 receives a sensitivity ratio storage unit 107 that previously stores a plurality of sensitivity ratios used by the amplitude correction unit 105 and a weighing signal from the signal synthesis unit 108, and receives a weighing signal from the signal synthesis unit 108. A sensitivity ratio setting unit 106 that selects a sensitivity ratio that minimizes the extraneous vibration component remaining in the weighing signal from the signal synthesis unit 108 from among a plurality of sensitivity ratios 107 stored, and sets and updates the amplitude correction unit 105 in the sensitivity ratio setting unit 106; Yes. The sensitivity ratio setting unit 106 sets and updates the sensitivity ratio of the amplitude correction unit 105 when there is no workpiece W on the weighing conveyor 32. The presence / absence of the object W to be weighed on the weighing conveyor 32 is determined based on, for example, a detection signal from the carry-in sensor 4, a weighing signal from the weighing means 21, or a displacement detection signal from the position sensor 83.

  In FIG. 4, one BPF 103, one phase correction unit 104, and one amplitude correction unit 105 are provided. However, as shown in FIG. 5, the BPF 103, the phase correction unit 104, and the amplitude correction unit 105 It is preferable that a plurality of external vibration components having different bands can be removed by the signal synthesizing unit 108, so that a plurality of external vibration components having different bands are provided.

  As shown in FIG. 1, the display unit 10 is provided at the upper end of the apparatus main body 2 on the transport unit 3 side, and is configured by a display device such as a liquid crystal display. When the operation mode of the weighing device 1 is the operation mode, the display means 10 displays the operation state of the weighing device 1, the measured value of the object W, and the pass / fail judgment result, and the operation mode of the weighing device 1 is the setting mode. In this case, display related to parameter setting and operation confirmation is performed. The display unit 10 may be configured as a touch panel in which displayed numbers, characters, and the like are input by a touch operation, and may be configured to be integrated with the setting unit 11.

  The sorting unit 5 is connected to the subsequent stage of the weighing device 1 and includes a sorting mechanism unit 5a and a conveyor belt 5b. The sorting mechanism unit 5a is configured by, for example, an extrusion type sorting mechanism. The sorting mechanism unit 5a only needs to be able to sort good products and defective products, and may be configured by a sorting mechanism such as a flipper mechanism, a dropout mechanism, or an air jet mechanism. The sorting mechanism unit 5a is configured to transfer the workpiece belt W to the workpiece W determined to be defective while the workpiece W transported from the upstream weighing conveyor 32 is being transported in the arrow B direction by the transport belt 5b. 5b is pushed out in the lateral direction and jet air is sprayed, and the defective object W is discharged from the conveying belt 5b and is distinguished from the non-defective object W by sorting. Yes. The conveyor belt 5b is composed of a roller 5c, a roller (not shown) disposed opposite to the roller 5c, and an endless conveyor belt wound around these rollers. The weighing object W is conveyed downstream at a predetermined speed.

  Next, the operation of the weighing device 1 according to the present embodiment will be described.

  The object to be weighed W is conveyed by being accelerated or decelerated so as to have an optimum speed for measurement by the running conveyor 31, and the weight is weighed by the weighing means 21 while being conveyed by the weighing conveyor 32. The weighing signal from the weighing means 21 is signal-processed by the signal processing means 71 on the basis of predetermined signal processing conditions to be a signal-processed weighing signal, and the weighing means 72 is to be weighed based on this signal-processed weighing signal. The measured value of the object W is calculated (gram conversion). Here, as shown in FIG. 6A, the load applied to the weighing conveyor 32 includes a load La caused by an object W, floor vibration caused by other production equipment, and external vibration caused by a roller or belt of the belt conveyor 14. The load Lb due to is mixed. Further, as shown in FIG. 6B, the weighing signal from the weighing means 21 is a mixture of a signal Sa corresponding to the change in the load La caused by the object W and a signal Sb corresponding to the load Lb caused by the external vibration. It will be. For this reason, if the weighing value of the workpiece W is calculated by the weighing means 72 based on the weighing signal from the weighing means 21, the measured value includes an error.

  Therefore, in the weighing device 1 of the present embodiment, the external vibration component remaining in the displacement detection signal is extracted from the displacement detection signal from the position sensor 83 by the BPF 103, and the phase correction unit 104 is applied to the extracted external vibration component. The phase correction is performed on the external vibration component subjected to the phase correction by the amplitude correction unit 105 with a predetermined sensitivity ratio, and the phase and amplitude are adjusted by the phase correction unit 104 and the amplitude correction unit 105, respectively. In the signal synthesizer 108, the external vibration component is removed from the weighing signal output by the signal processing means 71 by adding or subtracting the signal in the opposite phase to the weighing signal output by the signal processing means 71 in the signal synthesis unit 108. To do. Here, in FIG. 6C, the signal Sb indicates the external vibration component extracted by the BPF 103, and the signal Sb ′ indicates a signal whose phase and amplitude are adjusted by the phase correction unit 104 and the amplitude correction unit 105. ing.

  As described above, the weighing device 1 according to the present embodiment extracts the extraneous vibration component remaining in the displacement detection signal from the displacement detection signal from the position sensor 83 by the BPF 103, and extracts the extracted extraneous vibration component. The phase correction unit 104 performs phase correction, the amplitude correction unit 105 performs amplitude correction with a predetermined sensitivity ratio on the phase-corrected external vibration component, and the phase correction unit 104 and the amplitude correction unit 105 perform phase and amplitude correction. In the signal synthesizer 108, the signals adjusted by the signal processing unit 71 are added or subtracted in the opposite phase from the weighing signal output from the signal processing unit 71. It is configured to remove extraneous vibration components.

  With this configuration, the external vibration component remaining in the displacement detection signal is extracted from the displacement detection signal from the position sensor 83 by the BPF 103, and the phase correction unit 104 and the amplitude correction unit 105 perform phase and phase correction on the extracted external vibration component. The amplitude is corrected, and this signal is added to the weighing signal output from the signal processing means 71 in the opposite phase or subtracted in the same phase by the signal synthesis unit 108 to remove the extraneous vibration component from the weighing signal. For this reason, since the external vibration component is extracted at the same time as the weighing signal is acquired, there is no delay time for calculating the external vibration component as in the conventional case, and the low frequency vibration component is not affected without affecting the response. Can be removed. Further, since the external vibration component is extracted simultaneously with the acquisition of the weighing signal, it can be measured and zero-set with high accuracy at high speed.

  Therefore, the low frequency vibration component can be removed without affecting the responsiveness, and measurement and zero setting can be performed at high speed with high accuracy.

  The weighing device 1 according to the present embodiment includes a sensitivity ratio storage unit 107 that stores in advance a plurality of sensitivity ratios used by the amplitude correction unit 105, and a signal synthesis unit when there is no object W to be weighed on the weighing conveyor 32. The sensitivity ratio that receives the weighing signal from 108 and stores the plurality of sensitivity ratios stored in the sensitivity ratio storage unit 107 selects the sensitivity ratio that minimizes the extraneous vibration component remaining in the weighing signal from the signal synthesis unit 108 and sets it in the amplitude correction unit 105. And a sensitivity ratio setting unit 106 to be updated.

  With this configuration, since the optimum sensitivity ratio is selected from the sensitivity ratio storage unit 107 by the sensitivity ratio setting unit 106 and set in the amplitude correction unit 105, the external vibration component remaining in the weighing signal from the signal synthesis unit 108 is minimized. Can be

  In the weighing device 1 according to the present embodiment, a plurality of BPFs 103, phase correction units 104, and amplitude correction units 105 are provided for each of a plurality of different bands.

  With this configuration, the signal synthesizer 108 can remove a plurality of external vibration components having different bands.

  As described above, the weighing device according to the present invention has the effect that it can remove low-frequency vibration components without affecting the responsiveness, and can accurately weigh and zero-set at high speed, so that meat, fish It is useful as a weighing device that measures the quality of objects to be weighed such as processed foods and pharmaceuticals.

1 Weighing device 3 Conveying unit (conveying means)
7 General control unit 14 Belt conveyor (conveyance means)
21 Weighing means 32 Weighing conveyor (weighing table)
71 Signal processing means (weighing signal output means)
72 Measuring means 73 Storage means 74 Control means 76 Pass / fail judgment means 77 Mode switching means 81 Support point 82 Sao 83 Position sensor (position detection means)
84 Electromagnetic coil 85 Suspension plate 86 Parallel spring 87 Common base 88 Magnet 91 Servo control unit (drive control means)
92 Coil application unit (drive control means)
93 current detection resistor 94 amplifier 96 A / D converter 97 filter 101 amplifier 102 A / D converter 103 BPF (extraction means)
104 Phase correction unit (phase correction means)
105 Amplitude correction unit (amplitude correction means)
106 Sensitivity ratio setting section (sensitivity ratio setting means)
107 Sensitivity ratio storage unit (sensitivity ratio storage means)
108 Signal Synthesizer (Signal Synthesizer)
W Object to be weighed

Claims (2)

Conveying means (14) for conveying the objects to be weighed (W) sequentially put on the weighing table (32) under predetermined conveying conditions;
Position detecting means (83) for detecting a displacement from a predetermined position of the weighing table due to a load change caused by an object to be measured and outputting a displacement detection signal;
An electromagnetic coil (84) for applying a force opposite to the load to the weighing platform;
Drive control means (91, 92) for receiving a displacement detection signal from the position detection means and drivingly controlling the electromagnetic coil so as to suppress displacement of the weighing platform from a predetermined position;
A weighing signal output means (71) for outputting a weighing signal according to a value of a current flowing through the electromagnetic coil;
Extraction means (103) for extracting an external vibration component remaining in the displacement detection signal from the displacement detection signal from the position detection means;
Phase correction means (104) for performing phase correction on the extracted external vibration component;
Amplitude correction means (105) for correcting the amplitude of the phase-corrected external vibration component by a predetermined sensitivity ratio;
A signal synthesis means (108) for adding the external vibration component whose amplitude is corrected to the weighing signal output from the weighing signal output means or subtracting the external vibration component in the opposite phase and removing the extraneous vibration component from the weighing signal. When,
Sensitivity ratio storage means (107) for previously storing a plurality of sensitivity ratios used by the amplitude correction means;
External vibration remaining in the weighing signal from the signal synthesizing means out of the sensitivity ratios received by the sensitivity ratio storage means when there are no objects to be weighed on the weighing platform. A sensitivity ratio setting means (106) for selecting a sensitivity ratio with the smallest component and setting and updating the sensitivity ratio in the amplitude correction means;
Weighing means (72) for receiving a weighing signal from the signal synthesizing means and calculating a weighing value of the object to be weighed;
A weighing apparatus comprising: a quality determination means (76) for determining the quality of the object to be weighed by comparing the measurement value calculated by the weighing means with a quality determination criterion. The weighing device according to claim 1 , wherein a plurality of the extraction unit, the phase correction unit, and the amplitude correction unit are provided for each of a plurality of different bands .

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