JP2011212969A - Method and device for determining variable factor of paper in printing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for determining variable factors of paper in a printing machine configured to enable a user to grasp the cause when a printing failure or paper break of printing paper occurs in the printing machine.SOLUTION: Printing-condition signals such as a print speed signal and a tension signal or the like by a paper feed roller 2 or the like are configured to impart tension to printing paper P running on a printing part 1 and to specify printing conditions for stable running. The printing-condition signals are inputted to a signal processing device 10 so as to transform the signals into power spectra by executing the FFT. An edge sensor 6 arranged on the exit side of the printing part 1 captures displacement of both ends of the printing paper P. A data processing device 12 is inputted with the end information and calculates a change in paper width and a meandering state so as to transform the data into power spectra by executing the FFT. When each variation cycle obtained from the power spectra of the end-information signal of the printing paper matches the variation cycle of any one of the printing-condition signals with each other, it is determined as a variation in factors of the printing machine. In the case other than that, it is determined as a variation in factors of the printing paper.

Description

  The present invention relates to a variation of paper in a printing press that can capture the behavior during operation of the printing press and determine the cause of the printing fault in order to grasp the cause when the printing failure occurs in the printing press. The present invention relates to a factor determination method and a variation factor determination device.

  For example, in a multi-color rotary printing press, cyan, magenta, yellow, and black inks are sequentially transferred from respective roller inks to a traveling printing sheet to perform desired printing. At this time, it is necessary to transfer each ink to a predetermined position on the printing paper with high accuracy. Examples of printing failures include misalignment in the left and right direction at normal speed, roughness of the printing surface, the presence of wrinkles on the printing paper, and paper breaks. The roughness of the seal surface is considered to be a defect that occurs in the paper making process. However, misregistration and wrinkle breakage are considered to be caused not only by defective printing paper produced in the paper making process but also by the operating conditions of the printing press.

  However, in the current situation, when a printing defect occurs, it cannot be determined whether it is due to the printing paper itself or due to the printing machine. For this reason, the situation is unknown, and sufficient measures cannot be taken.

  By the way, a paper breakage detection device for a rotary printing press has been proposed as one that can quickly detect the occurrence of a paper break and stop the printing press when a paper break occurs in the printing press (Patent Literature). 1). This paper breakage detecting device is provided with optical detectors at both ends of the paper on the plate cylinder exit side of the rotary printing press, and detects the paper breakage by measuring the paper width of the roll paper. That is, when the optical detector includes a projector and a light receiver, both ends of the paper block a part between the light projector and the light receiver, so that a part of the light reaches the light receiver. At this time, if the paper width is constant, the sum of the amounts of light captured by the light receivers at both ends is constant even when the paper meanders. When a paper break occurs, the sum of the amounts of received light increases, so that the occurrence of a paper break can be detected.

  Patent Document 2 discloses a paper width measuring device that calculates the amount of contraction and the amount of meandering of paper traveling on a paper machine. This paper width measuring device is provided with a light source and a detector at both ends of the paper traveling on the paper machine, and captures the light shone from the light source and reflected at the edge of the paper, thereby causing the amount of paper shrinkage and meandering. The amount is calculated.

JP 7-329283 A JP 2003-336186 A

  The paper breakage detection device disclosed in Patent Document 1 only detects that a paper breakage has occurred in the running paper, and therefore cannot be used to elucidate the cause of the paper breakage.

  In addition, since the paper width measuring device disclosed in Patent Document 2 calculates the shrinkage amount and the meandering amount from the change in the paper width, installing this in the printing machine causes a break due to the change in the paper width. It can be used to determine whether there is a risk of paper. For example, since the change amount of the paper width when the paper break occurs can be quantitatively grasped, it can be determined that there is a possibility of paper break when a change of a certain amount or more occurs.

  However, any of them can detect a change in paper width, but cannot elucidate the cause of the printing failure in the printing press.

  By the way, in order to prevent printing defects from occurring in products delivered to the printing company that is the user, the present applicant has made efforts to elucidate the cause of the printing defects and has conducted various experiments. . As a result, it has been possible to determine whether the printing failure is in the printing paper itself or in the printing machine.

  Therefore, the present invention can contribute to the investigation of the cause when a printing failure occurs, and the paper variation factor determination method and the variation factor determination device in the printing press that can quickly take measures at that time. The purpose is to provide.

  As a technical means for achieving the above object, the paper variation factor determination method in the printing press according to the present invention grasps the behavior of the printing paper traveling on the printing press and determines the cause of the change in the behavior. In the method for determining the variation factor of the paper in the printing machine to be judged, the temporal profile of the displacement in the width direction of the printing paper traveling on the printing machine, the temporal profile of the paper width change, the temporal profile of the meander, and the temporal condition of the printing condition signal By comparing the profiles, the time-dependent profile of displacement at both ends, the time-dependent profile of the paper width change, the behavior of the meandering-time profile change, and the behavior of the time-dependent profiles of various printing conditions It is characterized by determining a variation factor of the behavior of the running printing paper.

  According to a second aspect of the present invention, there is provided a paper fluctuation factor determination method for a printing press that grasps the behavior of printing paper traveling on the printing press and determines the cause of the change in behavior. In the variation factor determination method, the displacement of the both ends in the width direction of the printing paper traveling on the printing machine, the paper width change, and the time-lapse signal of meandering are subjected to fast Fourier transform, The meandering power spectrum is calculated, the time signal of the printing condition signal is fast Fourier transformed, the powering condition signal power spectrum is calculated, the power spectrum of the displacement at both ends, the paper width change power spectrum, the meandering power spectrum, Compare the fluctuation period with the power spectrum of the printing condition signal, the power spectrum of the displacement at both ends and the power spectrum of paper width change, meandering When the power spectrum fluctuation period coincides with the power spectrum fluctuation period of the various printing conditions, it is determined that the fluctuation is caused by a printing press, and the other periodic components are determined as paper fluctuation. It is said.

  According to a third aspect of the present invention, there is provided a method for determining a variation factor of paper in a printing machine, wherein the various printing condition signals relating to the printing conditions are control of printing speed, paper feed tension, infeed tension, outlet tension, and dancer roll. It is one or a plurality of output signals.

  Further, the paper variation factor determination apparatus in the printing press according to the present invention grasps the behavior of the printing paper traveling on the printing press and determines the cause of the change in the behavior. In the apparatus, an end detection device that is installed on an exit side or both an entrance side and an exit side of a printing unit of a printing press and detects displacement of both end portions in the width direction of the traveling printing paper, and the end detection The edge information detected by the apparatus is input, a data processing device that calculates both end displacement data, paper width change data, and meander data of the running printing paper, and various printing condition signals related to the printing conditions of the printing press. Print condition signal processing device that is input and calculates print condition data, print condition data sent from the print condition signal processing device, both end displacement data and paper width change data calculated by the data processing device Display means for receiving and displaying meandering data, and the data processing device calculates the displacement of both ends, paper width change and meandering data with respect to the edge information, and the printing condition signal processing device In addition, the power spectrum of the printing condition is calculated by performing fast Fourier transform on the displacement of both ends, the change in paper width, the meandering, and the printing condition signal, and the time-dependent profile and the power spectrum of the respective data are displayed on the display means. Then, the time-dependent profile of the displacement in the width direction of the printing paper traveling on the printing machine, the time-lapse profile of the paper width change, the time-lapse profile of the meandering, and the time-lapse profile of the printing condition signal are compared. Time-lapse profile, paper width change time-lapse profile, meandering time-lapse profile change behavior, and time-lapse profile of various printing conditions By associating a comparison of the behavior it is characterized by determining the variation factors of the behavior of the printing paper traveling press.

  The display means displays the time profile of the print condition related to the print condition, the time profile of the displacement at both ends, the time profile of the paper width change, and the time profile of the meander, so that these can be compared. If it is recognized that the value deviates significantly from the steady state value, it is determined that there is a risk of the printing paper being run out of paper, and measures such as stopping the printing press are taken.

  By the way, the applicant of the present invention supplies various printing papers to a single multi-color rotary printing press, obtains the respective edge information of the printing paper for the traveling paper, and obtains the both ends obtained from the edge information. The part displacement data, the paper width change data, the meander data, and the various printing condition data were compared. The printing paper used for the multi-color rotary printing press was used as a countermeasure product for non-defective products, general products, and papers that had previously failed printing. When the time-lapse profile and the fluctuation cycle were compared with each other, fluctuations in the paper width were recognized at almost a constant cycle for any printing paper. This can be determined that the cause of the fluctuation of the edge of the traveling printing paper is not caused by the printing paper but is caused by the operation of the printing press. That is, since any printing paper is fluctuated at a constant cycle, it can be determined that the cause of this fluctuation is not caused by the paper but is unique to the printing press. Furthermore, it was found that the fluctuation period of the paper width coincides with the fluctuation period of the infeed tension data in the printing condition data. From this, the infeed tension fluctuates periodically and coincides with the period. It is recognized that the paper width fluctuates. Periodic fluctuations in the printing condition data are caused by the printing press, and when this fluctuation coincides with displacement of both ends of the paper, change in paper width, and occurrence of meandering, It can be determined that it is caused by driving. Such a change in paper width caused by the operation of the printing press is considered to be a cause of misregistration, wrinkles, and paper breaks.

  On the other hand, if edge displacement, paper width change, or meandering occurs regardless of changes in the temporal profile of the printing condition data or the fluctuation cycle, it can be determined that it has occurred due to the printing paper itself. is there.

  According to a fifth aspect of the present invention, there is provided a paper fluctuation factor determination device for a printing press that grasps the behavior of printing paper traveling on the printing press and determines the cause of the change in behavior. In the variation factor determination device, the edge detection device that is installed on both the exit side or the entrance side and the exit side of the printing unit of the printing press and detects the displacement of the positions of both ends in the width direction of the traveling printing paper, A data processing device that receives edge information detected by the edge detection device and calculates both end portion displacement data, paper width change data, and meander data of the running printing paper, and various types of printing related to printing conditions of the printing press A printing condition signal processing device that receives a condition signal and calculates printing condition data, printing condition data sent from the printing condition signal processing device, both end displacement data and paper width change calculated by the data processing device And the display means for receiving and displaying the data and the meandering data, and the data processing device calculates the displacement of both ends, the paper width change, and the meandering data with respect to the end information, and the printing condition signal The processing device calculates a power spectrum of the printing condition by performing a fast Fourier transform on the displacement at both ends, a change in paper width, meandering, and a printing condition signal, and displays the time profile and power of each data on the display means. Display the spectrum, compare the fluctuation spectrum of the power spectrum of the displacement at both ends, the power spectrum of the paper width change, the power spectrum of the meandering, and the power spectrum of the printing condition signal, and change the power spectrum of the displacement at both ends and the paper width change In the power spectrum of the various printing conditions in the fluctuation cycle of the power spectrum of the meandering power spectrum. A case that matches the period determined to vary according to the printing machine factors, and any other periodic components characterized by determining the variation of the paper factors.

  According to a sixth aspect of the present invention, there is provided the paper variation factor determination apparatus in the printing press, wherein the various printing condition signals relating to the printing conditions include a printing speed, a paper feed tension, an infeed tension, an outlet tension, and a dancer roll output signal. One or more of them.

  For accurate registration, it is necessary to apply tension to the printing paper in the printing section and run it at a constant speed, especially in color printing sections such as multi-color rotary printing presses. Printing speed and tension are controlled. For this reason, the tension and the printing speed of the printing paper before and after the printing unit are detected so that the running in the printing unit is stabilized. This type of tension is controlled by a paper feed tension controlled by a winding paper brake device on which the printing paper is wound, or by an infeed roller for stabilizing the tension of the running paper in the printing unit on the entrance side of the printing unit. There are in-feed tension, an output signal of the exit tension on the exit side of the printing unit, and the like.

  In addition, in order to perform accurate registration in a multi-color rotary printing press, it is important to accurately adjust the position of the printing paper in the left-right direction. Usually, this position adjustment is arranged at the exit of the printing section. Dancer rolls are used. The dancer roll is controlled based on the dancer roll control output signal.

  In the present invention, in particular, these tensions and control signals are used as printing condition signals, and these printing condition signals are used for determining the fluctuation factors. These printing condition signals are data specific to the printing press. By comparing these data with the displacement data of both ends of the traveling paper related to the printing paper, the paper width change data, and the meander data, printing defects and paper breaks are detected. This is used to determine the cause of the problem.

  According to the paper variation factor determination method and the variation factor determination apparatus in the printing press according to the present invention, when printing failure or sheet breakage occurs during operation of the printing press, the cause is caused by the printing paper. Or whether it is caused by the printing press. For this reason, it is possible to quickly cope with printing defects and paper breaks that have occurred, and to take immediate countermeasures, shorten the stoppage time of the printing press, and increase the efficiency of operation.

  According to the paper variation factor determination method in the printing press according to the third aspect of the invention or the paper variation factor determination apparatus in the printing press according to the sixth aspect of the invention, for the operation control of the existing printing press. Since it is possible to use data acquired by various detection devices installed in the printer, this variation factor determination device can be installed at low cost in existing printing equipment.

It is a block diagram for demonstrating the schematic structure of the paper variation factor determination apparatus in the printing machine which concerns on this invention. It is a figure which shows an example of the time-dependent profile of the various data signals captured by the variation factor determination apparatus which concerns on this invention. It is a figure which shows an example of the time-lapse profile of the various data signals made thin by the variation factor determination apparatus which concerns on this invention. It is a figure which shows an example of the power spectrum which performed the fast Fourier transformation to the time-dependent change shown in FIG. It is a block diagram for demonstrating the structure of other embodiment of the paper variation factor determination apparatus in the printing machine which concerns on this invention.

  Hereinafter, a paper variation factor determination device in a printing press according to the present invention will be described in detail based on the preferred embodiments shown in the drawings. In this embodiment, a multi-color rotary printing press will be described as an example, but other types and types of printing presses may be used.

  FIG. 1 is a block diagram illustrating a schematic configuration of a paper variation factor determination device in a printing press according to the present invention. The printing unit 1 of the rotary printing press includes a pair of cyan roll 1a, magenta roll 1b, yellow roll 1c, and black roll 1d for transferring cyan, magenta, yellow, and black inks to the printing paper P. The printing paper P is color-printed by running while being sandwiched between the pair of rolls 1a to 1d. The printing paper P is supplied while being unwound from the take-up R, and the unwinding printing paper P is fed with a paper feed tension by the paper feed roll 2 and guided to travel. An infeed roll 3 is disposed on the inlet side of the printing unit 1 to stabilize the tension at the printing unit inlet. An exit tension detection roll 4 for detecting exit tension is disposed on the exit side of the printing unit 1. A dancer roll 5 that controls meandering of the printing paper P during travel is disposed downstream of the exit tension detection roll 4. An edge sensor 6 is provided on the downstream side of the dancer roll 5 as an end detection device so as to be desired at both ends in the width direction of the printing paper P. The edge sensor 6 detects the displacement of both ends of the printing paper P, and is preferably an optical detector including a light projecting unit and a light receiving unit, and may be either a light transmission type or a light reflection type. Absent. The edge detection signal from the edge sensor 6 detects the change in the width of the printing paper P and the presence or absence of the meandering of the printing paper P.

  Each of the paper feed roll 2, the infeed roll 3, and the outlet tension detection roll 4 is provided with a detecting means such as a load cell, and the tension related to the printing conditions is detected. Further, the dancer roll 5 outputs a control signal for adjusting the meandering. These printing condition signals are sent to the printing condition signal processing device 10 by a general-purpose computer or the like via the sheet feeding tension information line 2a, the infeed tension information line 3a, the outlet tension information line 4a, and the dancer roll control information line 5a, respectively. Printing condition data subjected to profiling over time and fast Fourier transform (FFT) is calculated and converted into a power spectrum. As a display means connected to the printing condition signal processing apparatus 10, a time profile of the printing condition signal and its power spectrum are displayed on the monitor 11. In addition, an information signal related to the printing speed is input to the printing condition signal processing device 10 via the printing speed information line 7a, and this temporal profile and power spectrum are also included.

  Further, end information regarding both ends detected by the edge sensor 6 is sent to the data processing device 12 via the end information line 6a. Based on the input edge information, the data processor 12 obtains displacements at both ends of the printing paper, changes in paper width, and meandering of the printing paper. These data are sent to the printing condition signal processing device 10, and the printing condition signal processing device 10 changes the positions and widths of both ends of the printing paper, the time-lapse profile of the printing paper meander, and FFT processing. Displacement at both ends, paper width change and meandering power spectrum are calculated. The calculated displacement data, paper width change data, and power spectrum of the meandering data are displayed on the monitor 11 together with the time-lapse profile of the displacement and paper width of the both ends of the printing paper and the meandering of the printing paper. Note that a printer (not shown) is connected to the printing condition signal processing device 10 so that the signals and data displayed on the monitor 11 can be printed.

  The determination of the variation factor by the paper variation factor determination apparatus in the printing press configured as described above will be described below with reference to FIGS.

  FIG. 2 shows an example of temporal profiles of the paper width change signal 21a and both-end displacement signal 22a during travel of the printing paper 1 captured by the edge sensor 6 and the infeed tension signal 24a of the rotary printing press. .

  In FIG. 2, when the infeed tension 24a decreases, the both end displacement signal 22a and the paper width change signal 21a increase. Therefore, the change in the paper width at this time is based on the change in the infeed tension, and it can be determined that there is a factor in the rotary printing press.

  FIG. 3 shows a paper width change signal 21a and both end displacement signals 22a when the printing paper 1 captured by the edge sensor 6 travels, a printing speed signal 23a of a rotary printing press, the infeed tension signal 24a, and a dancer roll control signal. An example of each time-dependent change of 25a is shown. FIG. 4 shows a power spectrum obtained by performing a fast Fourier transform (FFT) on each signal shown in FIG. 3, and includes a power spectrum 21b of change in paper width, a power spectrum 22b of displacement at both ends, and a power spectrum of printing speed. 23b, a power spectrum 24b of infeed tension, and a power spectrum 25b of dancer roll control are shown.

In FIG. 4, at the frequency S ₃ where the amplitude of the power spectrum 24b of in-feed tension has increased, the amplitude of the power spectrum 21b of change in paper width also increases. Therefore, the change in the paper width at this time is based on the change in the infeed tension, and it can be determined that there is a factor in the rotary printing press.

On the other hand, at the frequencies S ₁ and S ₂ at which the amplitudes of the power spectrum 21b of the paper width change and the power spectrum 22b of the paper edge displacement increase, no increase in the frequency of the power spectrum related to the printing condition is observed. For this reason, the change in the paper width and the displacement of the paper edge that occur in these cases are irrelevant to the operation of the rotary printing press, and it can be determined that there is a factor in the printing paper.

  That is, if the power spectrum of the displacement at both ends, the power spectrum of the paper width change, and the fluctuation period of the meandering power spectrum are the same as the fluctuation period of the power spectrum of the printing conditions of the printing press, If the power spectrum of the displacement at both ends, the power spectrum of the paper width change, and the power spectrum of the meandering fluctuate independently, it can be determined that there is a factor in the printing paper.

  FIG. 5 shows another embodiment of the paper variation factor determination device in the printing press according to the present invention, and schematically shows a plan view of the printing unit 1. In this embodiment, an edge sensor 8 similar to the edge sensor 6 is also arranged on the entrance side of the printing unit 1. The edge sensor 7 on the entrance side also captures the edge information of the printing paper P and sends it to the data processing device 12 via the edge information line 8a. Based on the information on both ends, it is possible to determine whether the variation factor such as the paper width is in the printing machine or the printing paper, as described above.

  In this embodiment, it has been described that the printing condition signal uses the paper feed roll 2 and the infeed roll 3, the tension of the exit tension detection roll 4, the control signal output from the dancer roll 5, and the paper feed speed signal. However, as long as it defines the printing conditions of the printing press, signals relating to other printing conditions can be used. For example, the printing paper absorbs the dampening water supply amount signal corresponding to the dampening water supply amount sprayed for the non-image area, the opening signal of the dampening water supply solenoid valve, and the dampening water. A push-in amount signal of an anti-fan out roll provided for suppressing fan-out that increases the paper width, a control signal thereof, and the like can also be used as a printing condition signal. In other words, any signal can be used for factors that may affect the printing paper traveling on the printing press.

  According to the paper variation factor determination method and the variation factor determination device in the printing press according to the present invention, it is possible to grasp the cause of a printing defect or a paper break in the printing press. This contributes to the efficiency of the operation of the printing press.

P Printing paper R Winding 1 Printing section 2 Paper feed roll 3 Infeed roll 4 Tension detection roll 5 Dancer roll 6 Edge sensor (edge detection device)
7 Edge sensor (edge detection device)
10 Print condition signal processor
11 Monitor (display means)
12 Data processing equipment

Claims (6)

In the method for determining the variation factor of paper in the printing press, which understands the behavior of the printing paper running on the printing press and determines the cause of the change in behavior,
Compare the temporal profile of displacement at both ends in the width direction of the printing paper running on the printing press, the temporal profile of the paper width change, the temporal profile of the meander, and the temporal profile of the printing condition signal,
By comparing and responding to the displacement time profile of both ends, the paper width change time profile, the meandering time profile change behavior and the time profile behavior of various printing conditions, the printing paper running on the printing press A method for determining a variation factor of paper in a printing press, characterized by determining a variation factor of behavior. In the method for determining the variation factor of paper in the printing press, which understands the behavior of the printing paper running on the printing press and determines the cause of the change in behavior,
Displacement at both ends in the width direction of the printing paper running on the printing machine, paper width change, and meandering time signal are fast Fourier transformed to calculate power spectrum of displacement at both ends, paper width change power spectrum, and meander power spectrum. And
The time signal of the printing condition signal is fast Fourier transformed to calculate the power spectrum of the printing condition signal,
Comparing the fluctuation spectrum of the power spectrum of the printing condition signal, the power spectrum of the meandering power spectrum, the power spectrum of the paper width change and the power spectrum of the meandering,
Among the fluctuation spectrum of the power spectrum of the displacement at both ends and the power spectrum of the paper width change, the fluctuation spectrum of the meandering power spectrum, it is determined that the fluctuation is caused by a printing press factor when it coincides with the fluctuation period of the power spectrum of the various printing conditions. A method for determining a paper fluctuation factor in a printing press, wherein the other periodic components are determined as a paper factor fluctuation.   The various printing condition signals related to the printing conditions are one or more of printing speed, paper feed tension, infeed tension, outlet tension, and dancer roll control output signals. A method of determining a variation factor of paper in the printing machine according to claim 2. In the paper variation factor determination device in the printing press, which understands the behavior of the printing paper running on the printing press and determines the cause of the change in behavior,
An end detection device that is installed on both the exit side or the entrance side and the exit side of the printing unit of the printing press, and detects the displacement of the positions of both ends in the width direction of the traveling printing paper;
A data processing device that receives the edge information detected by the edge detection device and calculates both-end displacement data, paper width change data, and meander data of the running printing paper;
A printing condition signal processing device that receives various printing condition signals related to printing conditions of the printing press and calculates printing condition data;
The printing condition data sent from the printing condition signal processing device, and the display means for receiving and displaying both end portion displacement data, paper width change data and meander data calculated by the data processing device,
In the data processing apparatus, the both end portion displacement and paper width change, meander data are calculated with respect to the end portion information,
In the printing condition signal processing apparatus, the both end portion displacement and paper width change, meandering, and the printing condition signal are subjected to fast Fourier transform to calculate the power spectrum of the printing condition,
Displaying the time profile and power spectrum of the respective data on the display means,
Compare the temporal profile of displacement at both ends in the width direction of the printing paper running on the printing press, the temporal profile of the paper width change, the temporal profile of the meander, and the temporal profile of the printing condition signal,
By comparing and responding to the displacement time profile of both ends, the paper width change time profile, the meandering time profile change behavior and the time profile behavior of various printing conditions, the printing paper running on the printing press A paper variation factor determination apparatus in a printing press, characterized by determining a behavior variation factor. In the paper variation factor determination device in the printing press, which understands the behavior of the printing paper running on the printing press and determines the cause of the change in behavior,
An end detection device that is installed on both the exit side or the entrance side and the exit side of the printing unit of the printing press, and detects the displacement of the positions of both ends in the width direction of the traveling printing paper;
A data processing device that receives the edge information detected by the edge detection device and calculates both-end displacement data, paper width change data, and meander data of the running printing paper;
A printing condition signal processing device that receives various printing condition signals related to printing conditions of the printing press and calculates printing condition data;
The printing condition data sent from the printing condition signal processing device, and the display means for receiving and displaying both end portion displacement data, paper width change data and meander data calculated by the data processing device,
In the data processing apparatus, the both end portion displacement and paper width change, meander data are calculated with respect to the end portion information,
In the printing condition signal processing apparatus, the both end portion displacement and paper width change, meandering, and the printing condition signal are subjected to fast Fourier transform to calculate the power spectrum of the printing condition,
Displaying the time profile and power spectrum of the respective data on the display means,
Comparing the fluctuation spectrum of the power spectrum of the printing condition signal, the power spectrum of the meandering power spectrum, the power spectrum of the paper width change and the power spectrum of the meandering,
Among the fluctuation spectrum of the power spectrum of the displacement at both ends and the power spectrum of the paper width change, the fluctuation spectrum of the meandering power spectrum, it is determined that the fluctuation is caused by a printing press factor when it coincides with the fluctuation period of the power spectrum of the various printing conditions. A paper variation factor determination apparatus in a printing press, characterized in that other periodic components are determined as variations in a paper factor.   5. The various printing condition signals related to the printing conditions are one or a plurality of control output signals of a printing speed, a paper feed tension, an infeed tension, an outlet tension, and a dancer roll. A paper variation factor determination device for a printing press according to claim 5.

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