JP2016023049A - Meander frequency specifying device and meander correcting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology capable of performing correction control with higher correction accuracy in a conveyance mechanism for conveying a conveyed body of a long belt shape.SOLUTION: A meander frequency specifying device is used with a conveyance mechanism 20 for conveying the conveyed body of a long belt shape in the longitudinal direction thereof from an upstream side to a downstream side in a conveyance passage. The meander frequency specifying device include: a tension difference detecting part 15 for detecting the tension difference S15 between both ends of the conveyed body in the width direction; a frequency characteristic acquiring part 16 for acquiring a frequency spectrum S16 of the tension difference S15; and a meander frequency specifying part 17 for acquiring the meander frequency S17 by comparing the frequency spectrum S16 and a threshold function. Thereby, the meander frequency of the conveyed body generated in the conveyance mechanism 20 can be specified, and correction control with higher correction accuracy can be performed in the conveyance mechanism 20.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a technique for specifying a meandering frequency or a meandering amount in a width direction of a transported body in a transporting mechanism for transporting a long belt-shaped transported body.

  2. Description of the Related Art Conventionally, an image recording apparatus that has a transport mechanism that transports a long strip-shaped recording medium and records an image on the recording medium transported by the transport mechanism is known. This type of image recording apparatus includes, for example, an image recording apparatus that discharges ink from a plurality of heads and records an image on a recording medium as a transported body, and a wiring or the like for a long belt-shaped flexible substrate. A substrate processing apparatus for exposing a pattern is included.

  In this type of transport mechanism, it is known that a recording medium that is a transported body periodically meanders in the width direction. Therefore, the image recording apparatus is provided with a correction mechanism that corrects the position of the recording medium in the width direction (meander correction) in order to prevent the position of the transported body in the width direction from deviating from the image recording unit. There is. A conventional image recording apparatus having a correction mechanism is described in Patent Document 1, for example.

  In the image recording apparatus described in Patent Document 1, a detection unit that detects an end position of a recording medium and a position in the width direction of the recording medium are corrected on the upstream side in the transport direction of a plurality of recording heads that are image recording units. A tilting roller pair is provided. This suppresses the displacement of the position in the width direction of the recording medium with respect to the recording head (paragraph 0039 to paragraph 0041, FIG. 1).

JP 2012-62135 A

  However, in the transport mechanism provided in the conventional image recording apparatus, the detection unit that detects the end position of the transported body detects not only the displacement in the width direction of the transported body but also the edge shape of the transported body. . Therefore, even if correction control is performed based only on the end position of the transported body, there is a possibility that new meandering due to the edge shape may occur. Thus, when correction control is performed based only on the end position, there arises a problem that it is difficult to improve the correction accuracy.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique for performing correction control with higher correction accuracy in a transport mechanism for transporting a long strip-shaped transport target.

  In order to solve the above-mentioned problem, the first invention of the present application is a meandering frequency specifying device used together with a transport mechanism for transporting a long belt-shaped object to be transported in the longitudinal direction from the upstream side to the downstream side of the transport path, A tension difference detection unit that detects a tension difference between both ends in the width direction of the transported body transported by the transport mechanism, and a frequency characteristic acquisition that acquires a frequency spectrum of the tension difference detected by the tension difference detection unit And a meandering frequency specifying unit for obtaining a meandering frequency by comparing the frequency spectrum obtained by the frequency characteristic obtaining unit with a threshold function.

  A second invention of the present application is the meandering frequency specifying device according to the first invention, wherein the threshold function is a function of frequency, and the threshold function takes a minimum value at a reference frequency and moves away from the reference frequency. It is a function whose value is the same or larger.

  A third invention of the present application is a meandering amount specifying device that is used together with a transport mechanism that transports a long belt-shaped object to be transported in the longitudinal direction from the upstream side to the downstream side of the transport path. The meandering frequency specifying device of the invention, a displacement detecting unit for detecting a displacement of the transported body in the width direction, the displacement detected by the displacement detecting unit, and the meandering frequency acquired by the meandering frequency specifying unit And a meandering amount specifying unit for calculating a meandering amount of the transported body in the tension difference detecting unit.

  A fourth invention of the present application is the meandering amount specifying device according to the third invention, wherein the displacement detection unit is an edge sensor that detects a displacement of an end of the transported body in the width direction.

  A fifth invention of the present application is a transport device for transporting a long strip-shaped transported body, wherein the meandering amount specifying device of the third or fourth invention and the transported body from the upstream side to the downstream side of the transport path. A correction mechanism that corrects the position in the width direction of the object to be conveyed conveyed by the conveyance mechanism, and a correction control unit that controls the correction mechanism. The displacement detection unit is disposed in the vicinity of the correction mechanism, and the correction control unit controls the correction mechanism based on the meandering amount calculated by the meandering amount specifying unit.

  According to a sixth aspect of the present invention, there is provided an image recording apparatus for recording an image by ejecting liquid droplets toward a recording medium which is a long belt-shaped transported body, wherein the transporting apparatus of the fifth invention and the transported body And a plurality of head portions that discharge droplets toward the transported body transported by the transport mechanism.

  A seventh invention of the present application is an image recording apparatus for recording an image by ejecting liquid droplets toward a recording medium which is a long belt-shaped conveyance object, and the meandering amount specifying device of the third or fourth invention And a transport mechanism for transporting the transported body in the longitudinal direction from the upstream side to the downstream side of the transport path, and a plurality of discharge ports arranged along the width direction of the transported body, and transported by the transport mechanism A plurality of head units that discharge droplets toward the transported body, and a head control unit that controls ejection of droplets from the head unit, wherein the head control unit includes the meandering amount Based on the meandering amount calculated by the specifying unit, the ejection port for ejecting the droplet is selected.

  An eighth invention of the present application is a meandering frequency specifying method for specifying a meandering frequency of a long belt-like object to be conveyed in the longitudinal direction from the upstream side to the downstream side of the conveying path, and a) A tension difference detecting step for detecting a tension difference at both ends in the width direction, b) a frequency characteristic acquiring step for acquiring a frequency spectrum of the tension difference detected in the step a), c) acquired by the step b). And a meander frequency acquisition step of acquiring a meander frequency by comparing the frequency spectrum with a threshold function.

  A ninth invention of the present application is a meandering amount specifying method for specifying the meandering amount of the conveyed object using the meandering frequency specifying method of the eighth invention, wherein the steps a) to c) and d) are described above. Based on the displacement detection step of detecting the displacement of the transported body in the width direction, e) the displacement detected in the step d), and the meandering frequency acquired in the step c). And a meandering amount specifying step for calculating the meandering amount of the body.

  A tenth aspect of the present invention is a meandering correction method for the conveyed object using the meandering amount specifying method according to the ninth aspect, and is calculated by the steps a) to e) and f) the step e). And a meandering correction step of correcting the position of the transported body in the width direction based on the meandering amount.

  According to the first to tenth aspects of the present invention, the meandering frequency of the conveyed object generated in the conveying mechanism can be specified. Therefore, correction control with higher correction accuracy can be performed.

  In particular, according to the third and ninth inventions of the present application, it is possible to specify the meandering amount of the transported body generated in the transport mechanism. Therefore, correction control with higher correction accuracy can be performed.

1 is a diagram conceptually illustrating a configuration of an image recording apparatus according to a first embodiment. It is the figure which showed the structure of the correction mechanism which concerns on 1st Embodiment. It is the block diagram which showed the control system in the image recording device which concerns on 1st Embodiment. It is the flowchart which showed the flow of the meandering correction process which concerns on 1st Embodiment. It is the figure which showed an example of the frequency spectrum and threshold value function which concern on 1st Embodiment. It is the block diagram which showed the control system in the image recording apparatus which concerns on a modification. It is the flowchart which showed the flow of the meandering correction process of the image recording device which concerns on a modification. It is the figure which showed an example of the frequency spectrum and threshold value function which concern on a modification. It is the figure which showed an example of the frequency spectrum and threshold value function which concern on a modification. It is the figure which showed an example of the frequency spectrum and threshold value function which concern on a modification. It is the figure which showed an example of the frequency spectrum and threshold value function which concern on a modification.

  Embodiments of the present invention will be described below with reference to the drawings.

<1. First Embodiment>
<1-1. Configuration of Image Recording Device>
FIG. 1 is a diagram conceptually showing the configuration of the image recording apparatus 1 according to the first embodiment of the present invention. FIG. 2 is a diagram illustrating the configuration of the correction mechanism 41. FIG. 3 is a block diagram showing a control system in the image recording apparatus 1.

  The image recording apparatus 1 is an inkjet that records a color image on a printing paper 9 by ejecting ink from a plurality of head portions 31 onto the printing paper 9 while conveying the printing paper 9 that is a long belt-like recording medium. This is a printing apparatus of the type. That is, the image recording apparatus 1 is a processing apparatus that performs an image recording process on the printing paper 9 that is a long belt-shaped transported body.

  As shown in FIG. 1, the image recording apparatus 1 includes a transport mechanism 20, an image recording unit 30, a correction unit 40, a tension measurement unit 50, a drying unit 60, an inspection unit 70, and a control unit 10.

  The transport mechanism 20 is a mechanism for transporting the printing paper 9 in the longitudinal direction. The transport mechanism 20 according to the present embodiment includes an unwinding unit 21, a plurality of rollers 22, and a winding unit 23. The printing paper 9 is unwound from the unwinding unit 21 and is transported to the winding unit 23 along a transport path constituted by a plurality of rollers 22. Each roller 22 guides the printing paper 9 to the downstream side of the transport path by rotating about the horizontal axis. Further, when the plurality of rollers 22 are in contact with and press against the printing paper 9, tension is applied to the printing paper 9. As a result, the transport mechanism 20 applies tension to the printing paper 9 at a position facing the image recording unit 30. The conveyed printing paper 9 is collected to the winding unit 23.

  The image recording unit 30 faces the printing paper 9 conveyed by the conveyance mechanism 20 and discharges ink to the printing paper 9. That is, the image recording unit 30 is a processing unit that performs an image recording process on the printing paper 9.

  The image recording unit 30 of the present embodiment has four head units 31. The four head portions 31 are arranged in parallel to each other at intervals along the transport direction. These head portions 31 have a plurality of ejection openings arranged in parallel with the width direction of the printing paper 9 (horizontal direction orthogonal to the longitudinal direction). That is, the head unit 31 has a plurality of ejection openings arranged along the width direction of the printing paper 9.

  Each head unit 31 has K (black), C (cyan), M (magenta), and Y (yellow) color components of a color image to be recorded from a plurality of ejection openings toward the upper surface of the printing paper 9. Each color ink droplet is ejected. As a result, a color image is recorded on the upper surface of the printing paper 9.

  The correction unit 40 is a mechanism for correcting the position of the printing paper 9 in the width direction. The correction unit 40 includes a correction mechanism 41 and a reference sensor 42. The correction unit 40 is disposed on the upstream side of the image recording unit 30.

  The correction mechanism 41 corrects the position in the width direction of the printing paper 9 conveyed by the conveyance mechanism 20. As illustrated in FIG. 2, the correction mechanism 41 includes a pair of swing rollers 412 between two pairs of fixed rollers 411. The pair of swing rollers 412 swings in the width direction around the pivot 413 based on a drive signal from the control unit 10. Thereby, the printing paper 9 can be displaced in the width direction. However, the correction mechanism 41 of the present invention is not limited to the structure shown in FIG. For example, the printing paper 9 may be displaced in the width direction by sliding the roller in the width direction.

  The reference sensor 42 is a displacement detection unit for detecting displacement in the width direction of the printing paper 9. The reference sensor 42 is disposed in the vicinity of the correction mechanism 41. When the position in the width direction of the printing paper 9 is shifted from the standard position, the edge position of the printing paper 9 with respect to the reference sensor 42 changes. The reference sensor 42 detects the position shift amount in the width direction of the printing paper 9 by detecting the edge position.

  In the present embodiment, an optical edge sensor is used as the reference sensor 42. The reference sensor may be another type of edge sensor such as a contact sensor or an ultrasonic sensor. The reference sensor 42 of the present embodiment detects the displacement of the end portion in the width direction of the printing paper 9 and outputs the detection result to the meandering amount specifying unit 16 described later of the control unit 10.

  Returning to FIG. 1, the tension measuring unit 50 is a mechanism for detecting the tension at both ends in the width direction of the printing paper 9 conveyed by the conveying mechanism 20. The tension measuring unit 50 is disposed on the upstream side of the image recording unit 30 and on the downstream side of the correcting unit 40.

  The tension measuring unit 50 includes a first tension sensor 51 and a second tension sensor 52. The first tension sensor 51 and the second tension sensor 52 are provided on a tension detection roller 221 disposed in the vicinity of the image recording unit 30. Note that the tension detection roller 221 also has a function for transporting the printing paper 9 in the same manner as the roller 22.

  The first tension sensor 51 is disposed in the vicinity of one end of the tension detection roller 221 in the width direction. The second tension sensor 52 is disposed near the other end of the tension detection roller 221. The first tension sensor 51 and the second tension sensor 52 detect the tension at each end in the width direction of the printing paper 9 at the contact point of the tension detection roller 221 by, for example, a load cell. Further, the detection result of the first tension sensor 51 and the detection result of the second tension sensor 52 are used to detect a tension difference (tension difference S15 in FIG. 3) at both ends in the width direction of the printing paper 9.

  The drying unit 60 is disposed on the downstream side of the image recording unit 30. The drying unit 60 dries the printing paper 9 on which an image is recorded by the image recording unit 30. The drying unit 60 includes a heat roller 61 having a built-in heater and a plurality of rollers 22. Further, the heat roller 61 is rotationally driven while being in contact with the printing paper 9, and conveys the printing paper 9 downstream while heating it. As a result, the printing paper 9 is dried.

  The inspection unit 70 is disposed on the downstream side of the drying unit 60. The inspection unit 70 has a camera for acquiring an image of the printing surface of the printing paper 9. Accordingly, the inspection unit 70 inspects the image recording result based on the image acquired by the camera, such as whether the printing surface of the printing paper 9 is smudged or missing.

  The control unit 10 comprehensively controls each unit in the image recording apparatus 1. As conceptually shown in FIG. 1, the control unit 10 is configured by a computer having an arithmetic processing unit 11 such as a CPU, a memory 12 such as a RAM, and a storage unit 13 such as a hard disk drive. Further, as shown in FIG. 3, the control unit 10 includes a transport mechanism 20, each head unit 31, a correction mechanism 41, a reference sensor 42, a first tension sensor 51, a second tension sensor 52, a heat roller 61, and an inspection unit 70. Are electrically connected to each other.

  The control unit 10 temporarily reads the computer program and data stored in the storage unit 13 into the memory 12, and the arithmetic processing unit 11 performs arithmetic processing based on the computer program and data, whereby the image recording apparatus The operation of each part in 1 is controlled. Thereby, the printing process in the image recording apparatus 1 and the meandering correction process described later are executed. The function of the control unit 10 may be realized by software, or may be realized by hardware such as an electronic circuit.

  As shown in FIG. 3, the control unit 10 includes, as functional units realized on software, a head control unit 14, a tension difference detection unit 15, a frequency characteristic acquisition unit 16, a meander frequency specifying unit 17, a meandering amount. A specifying unit 18 and a correction control unit 19 are included. The functions of these units are realized by the arithmetic processing unit 11, the memory 12, and the storage unit 13, respectively.

  The head control unit 14 controls the ejection of ink droplets from the respective ejection ports of each head unit 31. Specifically, the head control unit 14 outputs to each head unit 31 a droplet discharge command signal S14 indicating which droplet size is discharged from which discharge port based on the image data of the image to be recorded. To do. As a result, ink droplets are ejected from the respective ejection openings of the head units 31 at an appropriate timing and with an appropriate droplet size, and a desired image is recorded on the printing paper 9.

  The tension difference detection unit 15 is based on the first tension value S51 detected by the first tension sensor 51 of the tension measurement unit 50 and the second tension value S52 detected by the second tension sensor 52. A tension difference S15 at both ends in the width direction of the printing paper 9 is detected. Then, the tension difference detection unit 15 outputs the detected tension difference S15 to the frequency characteristic acquisition unit 16.

  The frequency characteristic acquisition unit 16 acquires the frequency spectrum S16 of the tension difference S15 detected by the tension difference detection unit 15, and outputs this to the meandering frequency specifying unit 17.

  The meandering frequency specifying unit 17 compares the frequency spectrum S16 acquired by the frequency characteristic acquiring unit 16 with a threshold function S170 described later, acquires the meandering frequency S17, and outputs this to the meandering amount specifying unit 18. The threshold function S170 and the method for obtaining the meander frequency S17 in the meander frequency specifying unit 17 will be described later.

  The meandering amount specifying unit 18 determines the printing paper 9 in the tension difference detecting unit 15 based on the displacement S42 of the edge position of the printing paper 9 detected by the reference sensor 42 and the meandering frequency S17 acquired by the meandering frequency specifying unit 17. A meandering amount S18 is calculated. Further, the meandering amount specifying unit 18 outputs the calculated meandering amount S18 to the correction control unit 19.

  The correction control unit 19 controls the correction mechanism 41 based on the meandering amount S18 calculated by the meandering amount specifying unit 18. That is, the correction control unit 19 is based on the first tension value S51 and the second tension value S52 that are detection results of the tension measurement unit 50 and the displacement S42 that is the detection result of the reference sensor 42 that is a displacement detection unit. A correction command signal S19 is output to the correction mechanism 41. The operation of the correction mechanism 41 is controlled by a correction command signal S19.

<1-2. About meandering correction of printing paper>
Next, meandering correction of the printing paper 9 in the image recording apparatus 1 described above will be described with reference to FIGS. 4 and 5. FIG. 4 is a flowchart showing the flow of the meandering correction process in the image recording apparatus 1. FIG. 5 is a diagram showing an example of the frequency spectrum S16 and the threshold function S170 in the image recording apparatus 1.

  When the image recording apparatus 1 drives the transport mechanism 20 and starts transporting the printing paper 9, control of the correction mechanism 41 by the correction control unit 19 is also started at the same time.

  When the conveyance of the printing paper 9 is started and the control of the correction mechanism 41 by the correction control unit 19 is started, the reference sensor 42 detects the displacement S42 in the width direction of the edge position of the printing paper 9, and the control unit 10 (Step ST101). In the present embodiment, the reference sensor 42 outputs the detected displacement S42 to the meandering amount specifying unit 18.

  Here, when the feedback control of the correction mechanism 41 is performed based only on the detection result of the reference sensor 42, the printing paper 9 has a meandering position in the width direction having a certain periodicity such as hunting. Further, since the reference sensor 42 detects the displacement S42 of the edge position of the printing paper 9, if the edge position of the printing paper 9 itself has periodic meandering, the correction mechanism 41 is opposite to the meandering of the edge position. May cause phase meandering. Therefore, in this embodiment, the correction mechanism 41 is controlled based on both the detection result of the reference sensor 42 and the detection result of the tension measuring unit 50 as well as the detection result of the reference sensor 42, thereby Suppresses meandering more. That is, the positional deviation in the width direction of the printing paper 9 is further suppressed.

  In parallel with the above-described step ST101, the tension difference detecting unit 15 acquires the first tension value S51 and the second tension value S52 from the tension measuring unit 50, and the first tension value S51 and the second tension value S52. The difference is calculated and output as a tension difference S15 (step ST102). And the frequency characteristic acquisition part 16 frequency-analyzes tension | tensile_strength difference S15, and acquires frequency spectrum S16 (step ST103). As shown in FIG. 5, a plurality of peaks appear in the frequency spectrum S16. These peaks include the frequency component of the meander component of the printing paper 9 to be corrected, the frequency component of the vibration of components such as the rollers constituting the image recording apparatus 1, and the like.

  Next, the meander frequency specifying unit 17 detects the meander component peak from the frequency spectrum S16 by comparing the frequency spectrum S16 with the threshold function S170, and obtains the meander frequency S17 (step ST104). Specifically, the meandering frequency specifying unit 17 acquires, as the meandering frequency S17, a peak frequency having a value larger than the threshold function S170 in the frequency spectrum S16.

  As shown in FIG. 5, the threshold function S170 is a function of frequency in the same manner as the frequency spectrum S16. The threshold function S170 of the present embodiment takes the minimum value Pmin [gf ^ 2] at the reference frequency fmin [Hz], and the value becomes the same or larger as the distance from the reference frequency fmin [Hz] increases. Further, the threshold function S170 takes a maximum value Pmax [gf ^ 2] above the cutoff frequency fmax [Hz]. Since the threshold function S170 has such a shape, a peak around the reference frequency fmin [Hz] can be efficiently detected from the frequency spectrum S16.

  Each parameter of the threshold function S170 is set based on, for example, experimental results. As an example of an experiment, ink droplets are ejected from a predetermined nozzle, and a linear image extending in the longitudinal direction of the printing paper 9 is recorded. Thereafter, each parameter such as the reference frequency fmin [Hz] may be calculated from the meandering characteristic of the straight line.

  When the peak frequency cannot be detected, the minimum value Pmin is lowered so that the peak frequency can be detected. Thereby, meander frequency S17 can be acquired more reliably. If a plurality of peak frequencies are detected as a result of lowering the minimum value Pmin as described above, they may all be detected as the meander frequency S17. If the peak frequency is not detected even when the minimum value Pmin is lowered to a predetermined value, it is assumed that no meandering has occurred, and the meandering frequency S17 is not detected.

  Note that the frequency spectrum S16 illustrated in FIG. 5 has a peak at 0 [Hz], which is an offset of the tension difference between the left and right sides of the tension detection roller 221. Therefore, the meandering frequency specifying unit 17 excludes the vicinity of 0 [Hz] in the frequency spectrum S16 and acquires the meandering frequency S17.

  In the image recording apparatus 1, the peak of the frequency spectrum S16 appears in a certain range of frequency bands. Since this frequency band is determined by the apparatus configuration of the image recording apparatus 1, the reference frequency fmin [Hz] is set in advance in consideration of the frequency band of the meandering frequency estimated from the apparatus configuration.

  Subsequently, the meandering amount specifying unit 18 calculates the meandering amount S18 of the printing paper 9 in the tension difference detecting unit 15 based on the displacement S42 detected in Step ST101 and the meandering frequency S17 acquired in Step ST104 (Step S104). ST105). In the present embodiment, only the component having a frequency in the vicinity of the meandering frequency S17 is extracted from the displacement S42 to obtain the meander amount S18. Note that the meandering amount S18 may be calculated by separating a component having a frequency in the vicinity of the meandering frequency S17 and other components from the displacement S42 and weighting each component.

  Then, the correction control unit 19 outputs a correction command signal S19 to the correction mechanism 41 based on the meandering amount S18. Thereby, the correction mechanism 41 adjusts the position in the width direction of the printing paper 9 based on the meandering amount S18 (step ST106). In this way, the correction mechanism 41 can more accurately grasp the meandering amount S18 to be corrected, thereby efficiently suppressing periodic meandering in the width direction of the printing paper 9. Therefore, the positional deviation in the width direction of the printing paper 9 can be efficiently suppressed.

  In the image recording apparatus 1 described above, the meandering frequency S17 of the printing paper 9 generated in the transport mechanism 20 can be specified as described above. Thereby, the meandering amount S18 of the printing paper 9 generated in the transport mechanism 20 can be specified. Therefore, correction control with higher correction accuracy can be performed in the image recording apparatus 1.

  In the present embodiment, the tension difference between both ends of the printing paper 9 in the width direction is detected by the tension measuring unit 50 disposed closer to the image recording unit 30 than the correcting unit 40. Usually, since it is difficult to reduce the size of the correction mechanism 41 in the correction unit 40, it is difficult to arrange the correction unit 40 in the vicinity of the image recording unit 30 that is a processing unit. For this reason, the displacement S42 detected by the reference sensor 42 cannot necessarily reflect the meandering amount in the image recording unit 30. Therefore, the roller 22 in the vicinity of the image recording unit 30 is a tension detection roller 221 provided with a tension measuring unit 50. Thus, the meandering correction of the printing paper 9 can be performed in consideration of the meandering characteristics at a position closer to the image recording unit 30 as the processing unit.

  Further, by controlling the correction mechanism 41 using not only the detection result of the reference sensor 42 which is a displacement detection unit but also the detection result of the tension measurement unit 50, it is caused by the edge shape of the printing paper 9 and the characteristics of the correction unit 40. Can be suppressed. Therefore, meandering of the printing paper 9 in the vicinity of the image recording unit 30 can be suppressed. Therefore, the shift in the width direction of the image recording position in the vicinity of the image recording unit 30 can be efficiently suppressed.

  When the image recording unit 30 as a processing unit has a plurality of head units 31 arranged at intervals along the transport direction as in the present embodiment, the printing paper 9 has meandering in the vicinity of the image recording unit 30. In addition, there is a possibility that the printing accuracy may be reduced due to the deviation of the amplitude and phase of meandering between the head portions 31. Therefore, the present invention that can efficiently suppress the deviation in the width direction of the image recording position in the vicinity of the image recording unit 30 is particularly useful.

  In this embodiment, as shown in FIG. 1, the distance of the conveyance path between the correction unit 40 and the tension measurement unit 50 is greater than the distance of the conveyance path between the tension measurement unit 50 and the image recording unit 30. Too long. As described above, when the correction unit 40 is separated from the image recording unit 30 as the processing unit, the meandering characteristic of the printing paper 9 near the image recording unit 30 is detected by the displacement detected by the reference sensor 42 provided in the correction unit 40. It is difficult to guess from only. Therefore, by disposing the tension measuring unit 50 in the vicinity of the image recording unit 30, the positional deviation in the width direction of the printing paper 9 in the vicinity of the image recording unit 30 can be more efficiently suppressed.

<2. Modification>
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to said embodiment, For example, it may deform | transform as follows.

<2-1. Meander correction by the head>
FIG. 6 is a block diagram showing a control system in the image recording apparatus 1A according to the modification. FIG. 7 is a flowchart showing the flow of the meandering correction process of the image recording apparatus 1A in the example of FIG. In FIG. 6, the same reference numerals are given to the same components as those in the above embodiment.

  6 and 7, the image recording apparatus 1A does not have a correction mechanism. In the image recording apparatus 1A of the example of FIGS. 6 and 7, the control unit 10 detects the first tension value S51 and the second tension value S52 detected by the first tension sensor 51 and the second tension sensor 52 of the tension measuring unit 50. Then, based on the displacement S42 of the edge position of the printing paper detected by the reference sensor 42, the meandering amount S18 is calculated. In the image recording apparatus 1 </ b> A, the meandering of the printing paper itself is not suppressed using the correction mechanism, but each head unit 31 appropriately selects an ejection port for ejecting ink droplets in accordance with the meandering of the printing paper.

  As shown in FIG. 7, in the image recording apparatus 1A, when the conveyance of the printing paper is started and the control of the correction mechanism 41 by the correction control unit 19 is started, the reference sensor 42 is moved in the width direction of the edge position of the printing paper. Is detected and output to the meandering amount specifying unit 18 of the control unit 10 (step ST201).

  On the other hand, when conveyance of the printing paper 9 is started, in parallel with step ST201, the tension difference detection unit 15 calculates the difference between the first tension value S51 and the second tension value S52 and outputs the difference as the tension difference S15. (Step ST202). And the frequency characteristic acquisition part 16 frequency-analyzes tension | tensile_strength difference S15, and acquires frequency spectrum S16 (step ST203).

  Next, the meander frequency specifying unit 17 detects the peak of the meander component from the frequency spectrum S16 by comparing the frequency spectrum S16 with a threshold function, and acquires the meander frequency S17 (step ST204).

  Subsequently, the meandering amount specifying unit 18 calculates the meandering amount S18 of the printing paper 9 in the tension difference detecting unit 15 based on the displacement S42 detected in step ST201 and the meandering frequency S17 acquired in step ST204 (step). ST105). In this modification, only a component having a frequency in the vicinity of the meandering frequency S17 is extracted from the displacement S42 to obtain the meandering amount S18. Note that the meandering amount S18 may be calculated by separating a component having a frequency in the vicinity of the meandering frequency S17 and other components from the displacement S42 and weighting each component.

  Then, the head controller 14 calculates droplet discharge information indicating which droplet size is discharged from which discharge port based on the image data and the meandering amount S18 input from the outside (step ST206). That is, the head control unit 14 selects an ejection port for ejecting ink droplets based on image data input from the outside and the meandering amount S18.

  The head control unit 14 first converts image data input from the outside into basic droplet discharge information indicating which droplet size is discharged from which discharge port. Thereafter, in step ST206, the head control unit 14 calculates a deviation amount in the width direction of the printing paper when ink is ejected from each ejection port from the meandering amount S18 input from the meandering amount specifying unit 18. Then, the head controller 14 corrects the basic droplet discharge information so that the landing positions of the ink droplets discharged from the respective discharge ports are shifted by a distance corresponding to the shift amount, and calculates the droplet discharge information.

  The head control unit 14 outputs a droplet discharge command signal S14 to each head unit 31 based on the droplet discharge information. As a result, ink droplets are ejected from the respective ejection openings of the respective head units 31 at an appropriate timing and at an appropriate droplet size, and a desired image is recorded on the printing paper.

  In the example of FIGS. 6 and 7, the head controller 14 corrects the ejection position of the ink droplets from each head unit 31 according to the meandering in the width direction of the printing paper by accurately grasping the meandering amount S18 to be corrected. To do. Therefore, it is possible to efficiently suppress the displacement of the image recorded on the printing paper.

<2-2. Other variations>
8 to 11 are diagrams illustrating examples of the frequency spectrum S16 and the threshold function in an image recording apparatus according to another modification. The threshold function S170 of the above embodiment is represented by a cubic function when the frequency is between 0 [Hz] and fmax [Hz], but the present invention is not limited to this.

  In the example of FIG. 8, the threshold function S170a takes the minimum value Pmin [gf ^ 2] in the peripheral frequency band of fmin [Hz], and takes the maximum value Pmax [gf ^ 2] in the other frequency bands. It is. Thus, even if the threshold function is a bandpass filter, the meandering frequency S17 can be detected.

  In the example of FIG. 9, the threshold function S170b decreases linearly from 0 [Hz] toward the reference frequency fmin [Hz], and linearly increases from the reference frequency fmin [Hz] toward the cutoff frequency fmax [Hz]. Become bigger. As described above, the threshold function may be a function represented by a linear function.

  In the example of FIG. 10, the threshold function S170c is a quadratic function that takes the minimum value Pmin [gf ^ 2] at the reference frequency fmin [Hz] in the interval from 0 [Hz] to the cutoff frequency fmax [Hz]. Further, the threshold function S170c takes the maximum value Pmax [gf ^ 2] in the section of the cutoff frequency fmax [Hz] or higher. Thus, the threshold function may be a function represented by a quadratic function.

  In the example of FIG. 11, the threshold function S170d takes the maximum value Pmax [gf ^ 2] at 0 [Hz] and the cutoff frequency fmax [Hz] in the section from 0 [Hz] to the cutoff frequency fmax [Hz]. It is a sine wave having a minimum value Pmin [gf ^ 2] at a reference frequency fmin [Hz]. Further, the threshold function S170d takes the maximum value Pmax [gf ^ 2] in the section of the cutoff frequency fmax [Hz] or higher. As described above, the threshold function may be a function represented by a sine wave.

  Each of the threshold functions S170, 170b to S170d in the above embodiment and the examples in FIGS. 9 to 11 takes the minimum value Pmin [gf ^ 2] at the reference frequency fmin [Hz] and departs from the reference frequency fmin [Hz]. As the value increases, the value becomes the same or larger. Therefore, a peak around the reference frequency fmin [Hz] can be efficiently detected from the frequency spectrum S16.

  Further, the threshold functions S170, S170c, and S170d in the above embodiment, the example in FIG. 10, and the example in FIG. 11 all take the minimum value Pmin [gf ^ 2] at the reference frequency fmin [Hz], and the reference frequency fmin. As the distance from [Hz] increases, the value becomes the same or larger. Further, in these threshold functions S170, S170c, and S170d, in the vicinity of the reference frequency fmin [Hz], the inclination of the tangent line decreases as the reference frequency fmin [Hz] is approached. Thereby, the peak around the reference frequency fmin [Hz] can be detected more efficiently from the frequency spectrum S16.

  In the above embodiment, the displacement detection unit is an edge sensor that detects the displacement in the width direction of the edge position of the transported body, but the present invention is not limited to this. The displacement detection unit may be another type of displacement detection mechanism such as a sensor that detects a displacement in the width direction of a mark previously attached to the transported object. That is, the displacement detection part should just detect the displacement in the width direction of the specific site | part of a to-be-conveyed body.

  The present invention can also be applied to apparatuses other than the above-described image recording apparatus that records an image on a conveyed object. For example, a recording apparatus that records an image on a sheet-like recording medium other than general paper (for example, a resin film or the like) may be used. Moreover, the exposure processing apparatus which exposes patterns, such as wiring, with respect to a elongate strip-shaped flexible substrate may be sufficient. Furthermore, other processing apparatuses that perform processing on a sheet-like transported body, such as a coating apparatus that applies a processing liquid to the transported body and a processing apparatus that performs laser processing on the transported body. Also good.

  Moreover, you may combine suitably each element which appeared in said embodiment and modification in the range which does not produce inconsistency.

DESCRIPTION OF SYMBOLS 1,1A Image recording device 9 Printing paper 10 Control part 14 Head control part 15 Tension difference detection part 16 Frequency characteristic acquisition part 17 Meander frequency specific | specification part 18 Meander amount specific | specification part 19 Correction control part 20 Conveyance mechanism 21 Unwinding part 22 Roller 23 Winding unit 30 Image recording unit 31 Head unit 40 Correction unit 41 Correction mechanism 42 Reference sensor 50 Tension measurement unit 51 First tension sensor 52 Second tension sensor 221 Tension detection roller Pmax maximum value Pmin minimum value S104 step S14 droplet discharge command Signal S15 Tension difference S16 Frequency spectrum S17 Meander frequency S170, S170a, S170b, S170c, S170d Threshold function S18 Meander amount S19 Correction command signal S42 Displacement S51 First tension value S52 Second tension value fmax Cut off frequency fmin Reference frequency

Claims (10)

A meandering frequency specifying device used together with a transport mechanism for transporting a long belt-shaped object to be transported in the longitudinal direction from the upstream side to the downstream side of the transport path,
A tension difference detection unit that detects a tension difference between both ends in the width direction of the transported body transported by the transport mechanism;
A frequency characteristic acquisition unit that acquires a frequency spectrum of the tension difference detected by the tension difference detection unit;
A meander frequency specifying unit for acquiring a meander frequency by comparing the frequency spectrum acquired by the frequency characteristic acquisition unit with a threshold function;
A meandering frequency specifying device. The meandering frequency specifying device according to claim 1,
The threshold function is a function of frequency;
The meandering frequency specifying device, wherein the threshold function is a function that takes a minimum value at a reference frequency and increases or decreases as the distance from the reference frequency increases. A meandering amount specifying device used together with a transport mechanism for transporting a long belt-shaped object to be transported in the longitudinal direction from the upstream side to the downstream side of the transport path,
The meandering frequency specifying device according to claim 1 or 2,
A displacement detector for detecting displacement in the width direction of the conveyed object;
Based on the displacement detected by the displacement detector and the meander frequency acquired by the meander frequency specifying unit, a meandering amount specifying unit for calculating the meandering amount of the transported body in the tension difference detecting unit;
A meandering amount specifying device. The meandering amount specifying device according to claim 3,
The meandering amount specifying device, wherein the displacement detection unit is an edge sensor that detects a displacement of an end of the transported body in the width direction. A transport device for transporting a long belt-shaped transported body,
The meandering amount specifying device according to claim 3 or 4,
A transport mechanism for transporting the transported body in the longitudinal direction from the upstream side to the downstream side of the transport path;
A correction mechanism for correcting the position in the width direction of the transported body transported by the transport mechanism;
A correction control unit for controlling the correction mechanism;
Have
The displacement detector is disposed in the vicinity of the correction mechanism,
The correction control unit is a transport device that controls the correction mechanism based on the meandering amount calculated by the meandering amount specifying unit. An image recording apparatus for recording an image by ejecting liquid droplets toward a recording medium that is a long belt-shaped conveyance object,
A transport apparatus according to claim 5;
An image recording apparatus having a plurality of discharge ports arranged along the width direction of the transported body, and having a plurality of head units that discharge droplets toward the transported body transported by the transport mechanism. An image recording apparatus for recording an image by ejecting droplets toward a recording medium that is a long belt-shaped transported body,
The meandering amount specifying device according to claim 3 or 4,
A transport mechanism for transporting the transported body in the longitudinal direction from the upstream side to the downstream side of the transport path;
A plurality of ejection openings arranged along the width direction of the transported body, and a plurality of head units that discharge droplets toward the transported body transported by the transport mechanism;
A head control unit that controls ejection of liquid droplets from the head unit;
Have
The image recording apparatus, wherein the head control unit selects the ejection port that ejects the droplet based on the meandering amount calculated by the meandering amount specifying unit. A meandering frequency specifying method for specifying the meandering frequency of a long belt-like object to be conveyed in the longitudinal direction from the upstream side to the downstream side of the conveying path,
a) a tension difference detection step of detecting a tension difference between both ends of the transported body in the width direction;
b) a frequency characteristic acquisition step of acquiring a frequency spectrum of the tension difference detected in the step a);
c) a meander frequency obtaining step of obtaining a meander frequency by comparing the frequency spectrum obtained in step b) with a threshold function;
A meandering frequency specifying method. A meandering amount specifying method for specifying a meandering amount of the conveyed object using the meandering frequency specifying method according to claim 8,
The steps a) to c);
d) a displacement detection step of detecting displacement in the width direction of the transported body;
e) a meandering amount specifying step of calculating a meandering amount of the conveyed object based on the displacement detected in the step d) and the meandering frequency acquired in the step c);
A meandering amount specifying method. A meandering correction method for the conveyed object using the meandering amount specifying method according to claim 9,
The step a) to the step e);
f) a meandering correction step of correcting the position of the transported body in the width direction based on the meandering amount calculated in the step e);
A meandering correction method.

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