JP6437829B2 - Printing position correction method and printing apparatus using the same - Google Patents

Description

  The present invention relates to a print position correction method for printing on a long print medium while correcting the print position from the side edge of the print medium, and a printing apparatus using the same.

  2. Description of the Related Art Conventionally, for example, in an inkjet printing apparatus, an ink droplet is ejected from an inkjet head while an image is printed on a continuous paper while the continuous paper is conveyed. When transporting a print medium such as continuous paper, the side edge position of the continuous paper may fluctuate in a direction orthogonal to the transport direction. In such a state, there arises a disadvantage that the printing start position from the side edge of the continuous paper fluctuates. Therefore, a printing position correction method is provided in which a side edge detection unit that detects the side edge position of continuous paper is arranged so that, when the side edge position of the continuous paper moves, the image printing position is shifted based on the position information. (For example, refer to Patent Document 1). Thereby, even if the side edge position of continuous paper moves, the printing start position can be made constant from the side edge.

  In order to shift the printing start position of the image according to the shift of the side edge position of the continuous paper, first, the arrangement position information of the side edge detection unit is stored as a reference value when the ink jet printing apparatus is assembled. In addition, the positional relationship with the inkjet head which prints with respect to a continuous paper is arrange | positioned accurately at the side edge detection part. Then, the continuous paper is conveyed before product printing, and the side edge position is detected by the side edge detection unit. Since the position where the side edge has moved is known from the side edge position detected at this time and the reference value, the print start position at the side edge by the inkjet head is determined based on the moved position. Thus, even if the side edge of the continuous paper moves, the printing position correction can be performed so that the printing start position from the side edge of the continuous paper is fixed. The reference value stored at the time of assembling the device is fixed during operation of the device.

JP 2002-99178 A (FIG. 2)

However, the conventional example having such a configuration has the following problems.
That is, the conventional method is based on the premise that the position of the side edge detection unit is not displaced, but the position of the side edge detection unit may be shifted. For example, since there is a risk that paper dust generated during the conveyance of continuous paper may adhere to the side edge detection unit and the detection accuracy may decrease, it is common to clean the side edge detection unit during regular maintenance. . At that time, the side edge detection unit may be unintentionally touched, which may cause a deviation in the arrangement position in the width direction of the continuous paper. When such a shift in the arrangement position of the side edge detection unit occurs, the reference value is shifted, so that it is not possible to accurately perform the print position correction to fix the print start position from the side edge of the continuous paper, and the print quality Cause a decline.

  In order to avoid such problems, the following measures can be considered. That is, before cleaning the side edge detector, the continuous paper is arranged and the side edge position is detected by the side edge detector, and after cleaning, the side edge position of the continuous paper is detected again by the side edge detector. And the difference of the side end position before and behind cleaning is calculated | required, and a reference value is correct | amended based on this. However, since there is no guarantee that the side edge position of the continuous paper is not displaced before and after cleaning, this measure is not practical.

  The present invention has been made in view of such circumstances, and the print start position from the side edge of the print medium is fixed by updating the reference value according to the displacement of the arrangement position of the side edge detection unit. It is an object of the present invention to provide a printing position correction method and a printing apparatus using the printing position correction method that can accurately perform printing position correction.

In order to achieve such an object, the present invention has the following configuration.
That is, the invention according to claim 1 is arranged along the transport unit when printing is performed by the print unit with the print medium while transporting the long print medium along the transport unit, A printing position where the control unit corrects the printing position from the side edge position of the print medium by the printing unit based on the side edge position information from the side edge detection unit that detects the side edge position of the printing medium. A correction method, a reference for storing, as a reference value, arrangement position information of the side edge detection unit for determining a distance between a print region end perpendicular to the transport direction of the print medium and a side end of the print medium The value storage process and the side edge position information of the print medium are detected as the displacement side edge position information by the side edge detection unit while the print medium is conveyed before the arrangement position of the side edge detection unit is displaced. Over-displacement front end position information detection After the displacement, the side edge position information of the print medium is detected as the after-displacement side edge position information by the side edge detection unit in a state where the print medium is conveyed after the arrangement position of the side edge detection unit is displaced. Side edge position information detection process, a reference value update process for updating the reference value by adding a difference between the pre-displacement side end position information and the post-displacement side end position information to the reference value; and the printing unit And a correction process for correcting the printing position based on the updated reference value when printing is performed.

  [Operation / Effect] According to the first aspect of the present invention, first, the arrangement position information of the side edge detector is stored as a reference value (reference value storage process). Next, before the disposition position of the side end detection unit is displaced, the side end position information is detected as the pre-displacement side end position information by the side end detection unit while transporting the print medium (pre-displacement side end position information detection process). Then, after the arrangement position of the side end detection unit is displaced, similarly, the side end position information is detected by the side end detection unit as post-displacement side end position information (post-displacement side end position information detection process). Thereafter, the difference between the pre-displacement side end position information and the post-displacement side end position information is added to the reference value, and the reference value is updated (reference value update process). When printing by the printing unit, the control unit corrects the printing position based on the updated reference value. As for the reference value, the positional deviation of the side edge detection unit is corrected. Therefore, even if the arrangement position of the side edge detection unit is displaced, the reference value is updated according to the deviation of the arrangement position of the side edge detection unit, so the printing position from which the printing start position from the side edge of the print medium is made constant Correction can be performed accurately.

Further, in the present invention, the pre-displacement side end position information detection process and the post-displacement side end position information detection process carry the print medium for a predetermined time, and the average value of the side end position information within the predetermined time. It is preferable to use the pre-displacement side end position information and the post-displacement side end position information (claim 2).

  Since there is a temporal variation in the detection result of the side edge position, by using the average value of the side edge position information of the printing medium conveyed within a predetermined time as the displacement side edge position information and the displacement side edge position information, It is possible to suppress a deterioration in accuracy of the side end position due to the variation. Therefore, it is possible to suppress deterioration in accuracy of print position correction.

  Further, in the present invention, the average value is calculated within a range within an integral multiple of a period of a frequency at which a frequency component is extracted with respect to a difference between tensions at both ends when the print medium is conveyed. (Claim 3).

  The fluctuation cycle of the side end position is related to the frequency component in the difference between the tensions at both ends during conveyance of the print medium. In other words, since the side edge position indicates that it fluctuates at that frequency, the fluctuation period of the side edge position is obtained by calculating the average value of the side edge position information within a range that is an integral multiple of the frequency of the peak frequency. The influence of can be suppressed. Therefore, it can suppress that the precision of the average value of a side end position falls.

  According to a fourth aspect of the present invention, there is provided a printing apparatus that performs printing while correcting the printing position from the side edge position when printing on a long print medium, and transports the printing medium. A transport unit, a printing unit that performs printing on the print medium that is transported through the transport unit, and a side end position information that is disposed along the transport unit and detects a side end position of the print medium. Storing position information of the side edge detection unit for determining the interval between the output side edge detection unit, the print region edge perpendicular to the print medium conveyance direction, and the side edge of the print medium as a reference value The side value position information of the print medium detected by the side edge detection unit in a state in which the print medium is conveyed before the arrangement position of the reference value storage unit and the side edge detection unit is displaced. A pre-displacement side end position information storage unit storing end position information; After the disposition position of the detection unit is displaced, in a state where the print medium is transported, the side end position information of the print medium detected by the side end detection unit is stored as the rear end position information after displacement. While adding the difference between the position information storage unit, the pre-displacement side end position information and the post-displacement side end position information to the reference value, the reference value is updated, and at the time of printing by the printing unit, And a control unit that corrects the printing position based on the updated reference value.

  [Operation / Effect] According to the invention described in claim 4, the arrangement position information of the side edge detection unit is stored in the reference value storage unit as a reference value, and printing is performed before the arrangement position of the side edge detection unit is displaced. The side end position information is detected by the side end detection unit while the medium is conveyed by the conveyance unit, and this is stored in the pre-displacement side end position information storage unit as the pre-displacement side end position information. Further, after the arrangement position of the side end detection unit is displaced, the side end position information is detected by the side end detection unit, and this is stored in the post-displacement side end position information storage unit as post-displacement side end position information. The control unit adds the difference between the pre-displacement side end position information and the post-displacement side end position information to the reference value, and updates the reference value in the reference value storage unit. When printing by the printing unit, the control unit corrects the printing position based on the updated reference value. As for the reference value, the positional deviation of the side edge detection unit is corrected. Therefore, even if the arrangement position of the side edge detection unit is displaced, the reference value is updated according to the deviation of the arrangement position of the side edge detection unit, so the printing position from which the printing start position from the side edge of the print medium is made constant Correction can be performed accurately.

  According to the printing position correction method of the present invention, first, the arrangement position information of the side edge detection unit is stored as a reference value (reference value storage process). Next, before the disposition position of the side end detection unit is displaced, the side end position information is detected as the pre-displacement side end position information by the side end detection unit while transporting the print medium (pre-displacement side end position information detection process). Then, after the arrangement position of the side end detection unit is displaced, similarly, the side end position information is detected by the side end detection unit as post-displacement side end position information (post-displacement side end position information detection process). Thereafter, the difference between the pre-displacement side end position information and the post-displacement side end position information is added to the reference value, and the reference value is updated (reference value update process). When printing by the printing unit, the control unit corrects the printing position based on the updated reference value. As for the reference value, the positional deviation of the side edge detection unit is corrected. Therefore, even if the arrangement position of the side edge detection unit is displaced, the reference value is updated according to the deviation of the arrangement position of the side edge detection unit, so that the print position from which the printing start position from the side edge of continuous paper is made constant Correction can be performed accurately.

It is a schematic structure figure showing the whole ink-jet printer concerning an example. It is a top view of the periphery of an inkjet head. It is a figure where it uses for description of the printing position correction | amendment by a side edge detection part. It is a graph which shows the change of the amount of meandering before and after a periodic maintenance. It is a graph of the side edge position detected by the side edge detection part. It is a graph which shows the difference of tension. It is a graph which shows the frequency analysis result of the difference of tension. It is a flowchart which shows the operation | movement of the printing process in an inkjet printing system.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram illustrating an entire inkjet printing apparatus according to an embodiment, and FIG. 2 is a plan view of the periphery of a printing unit.

  The ink jet printing system 1 according to the embodiment includes an ink jet printing apparatus 3, a paper feed unit 5, and a paper discharge unit 7.

  The ink jet printing apparatus 3 performs printing on a sheet-like continuous paper WP. The paper supply unit 5 holds a roll of continuous paper WP so as to be rotatable about a horizontal axis, and unwinds the continuous paper WP from the roll of continuous paper WP and supplies it to the inkjet printing apparatus 3. The paper discharge unit 7 winds the continuous paper WP printed by the inkjet printer 3 around the horizontal axis. When the supply side of the continuous paper WP is the upstream side and the discharge side of the continuous paper WP is the downstream side, the supply unit 5 is disposed on the upstream side of the ink jet printing apparatus 3, and the paper discharge unit 7 is downstream of the ink jet printing apparatus 3. Arranged on the side.

  The ink jet printing apparatus 3 corresponds to the “printing apparatus” in the present invention.

  The ink jet printing apparatus 3 includes a driving roller 9 for taking in the continuous paper WP from the paper supply unit 5 on the upstream side. The continuous paper WP unwound from the paper supply unit 5 by the drive roller 9 is conveyed toward the downstream paper discharge unit 7 along a rotatable conveyance roller 11 and the like. A driving roller 13 is disposed on the upstream side of the paper discharge unit 7. The drive roller 13 sends out the continuous paper WP that has been printed and inspected to the paper discharge unit 7. Tension sensors 14L and 14R are attached to both ends of the transport roller 11 arranged at the most upstream position, respectively. These tension sensors 14L and 14R detect respective tensions on the left and right sides of the continuous paper WP.

  The inkjet printing apparatus 3 is configured by dividing a plurality of units according to functions and connecting the plurality of units. In the present embodiment, the ink jet printing apparatus 3 includes five units 3a to 3e including an entrance unit 3a, a first print unit 3b, a second print unit 3c, a drying unit 3d, and an exit unit 3e. ing.

  The entrance unit 3a is provided with a driving roller 9, an edge position control unit 15, and a driving roller 17. The first printing unit 3b is provided with inkjet heads 19a and 19b that eject ink droplets. The second printing unit 3c is provided with inkjet heads 19c and 19d that eject ink droplets. The drying unit 3d is provided with a heat drum 21 that contacts the continuous paper WP and heats and dries the ink droplets. The exit unit 3e is provided with an inspection unit 23 and a driving roller 13.

  In the present embodiment, the inkjet printing apparatus 3 is constituted by five units 3a to 3e, but the present invention is not limited to such a form. The inkjet heads 19a to 19d described above correspond to the “printing unit” in the present invention.

  The continuous paper WP is conveyed in the order of the driving roller 9, the edge position control unit 15, the driving roller 17, the inkjet heads 19 a to 19 e, the heat drum 21, the inspection unit 23, and the driving roller 13. The edge position control unit 15 automatically adjusts when the continuous paper WP meanders and controls the continuous paper WP to be conveyed to a correct position. The drive roller 17 rotates at a constant speed and becomes a reference for the rotation speed of the other drive rollers 9 and 13 and the heat drum 21.

  A nip roller 25 is rotatably provided on each of the drive rollers 9, 13, and 17 described above. The nip roller 25 provides a conveying force for the continuous paper WP. The pressing force by the nip roller 25 is applied by, for example, an air cylinder (not shown). The nip roller 25 is made of an elastic body such as rubber, for example.

  The inkjet heads 19 a to 19 d are arranged along a conveyance unit 27 formed along the plurality of conveyance rollers 11. Each of the inkjet heads 19a to 19d ejects, for example, black (K), cyan (C), magenta (M), and yellow (Y) ink droplets in order from the upstream side. Therefore, the inkjet printing apparatus 3 can perform four-color printing.

  The heat drum 21 heats and dries the ink droplets adhering to the continuous paper WP by the inkjet heads 19a to 19d. The heat drum 21 incorporates a heater and is driven to rotate. The inspecting unit 23 inspects the printed portion for dirt or missing. The inspected continuous paper WP is wound around the paper discharge unit 7 in a roll shape.

  One side edge detection unit 29 is arranged at a position corresponding to the upstream side of each of the inkjet heads 19 a to 19 d described above and along the transport unit 27. The side edge detection unit 29 has a function of detecting a side edge position (an edge in a direction orthogonal to the transport direction) of the continuous paper WP. Each side edge detection part 29 is attached to the side plate 31 to which each inkjet head 19a-19d is attached. Each side edge detection unit 29 is attached with a positional relationship with each corresponding inkjet head 19a to 19d with high accuracy. However, since the side edge detection accuracy of the continuous paper WP decreases when the paper dust of the continuous paper WP adheres, each side edge detection unit 29 needs to perform regular maintenance. At this time, when the operator touches the side edge detection unit 29, the position may be unintentionally displaced with respect to the width direction of the continuous paper WP (direction perpendicular to the transport direction). The side edge detection unit 29 is used to determine the distance between the edge of the printing area orthogonal to the conveyance direction of the continuous paper WP and the side edge of the continuous paper WP.

  The side edge detection unit 29 includes, for example, a light projecting unit and a light receiving unit that are spaced apart above and below the side edge of the continuous paper WP, and detects the position without contacting the side edge of the continuous paper WP. It is preferable that it is a non-contact transmission optical sensor capable of

  Here, a specific example of print position correction for performing printing by determining the distance between the side edge of the continuous paper WP and the edge of the print area will be described with reference to FIG. FIG. 3 is a diagram for explaining the printing position correction by the side edge detection unit. Here, as an example, the inkjet head 19a will be described as an example, but the same applies to the other inkjet heads 19b to 19d.

  First, the arrangement position information of the side edge detection unit 29 is stored as a reference value. The timing for storing the reference value is, for example, before printing the printed material as a product, such as when the apparatus is assembled or when the apparatus is carried into the user. This arrangement position information is defined by the positional relationship between the side edge detector 29 and the inkjet head 19a. For example, as shown on the left in FIG. 3, the arrangement position information in a state where the base of the side edge detection unit 29 is in close contact with the side plate 31 and correctly attached is set to “0”, and this is set as the reference value PS. When the side edge position of the continuous paper WP is detected by the side edge detection unit 29, the continuous paper WP is determined based on the detected position and the positional relationship between the known side edge detection unit 29 and the inkjet head 19a. The nozzle Nz of the ink jet head 19a (the blackened portion in FIG. 3) is determined such that the gap SP is between the edge of the printing area PA and the side edge of the continuous paper WP, and the printing area PA on the continuous paper WP is determined. Printing is performed while correcting the printing position. For example, as shown on the right in FIG. 3, when the side edge position of the continuous paper WP moves to the left side in the transport direction in plan view, the detection position by the side edge detector 29 moves according to the amount of movement. Accordingly, the print position correction is performed so as to shift the nozzle Nz (the blacked portion in FIG. 3) to be printed at the end of the print area PA. As a result, the interval SP between the edge of the printing area PA of the continuous paper WP and the side edge of the continuous paper WP is made constant.

  Reference is now made to FIG. FIG. 4 is a graph showing changes in the meandering amount before and after the regular maintenance.

  When the side edge detection unit 29 is cleaned by regular maintenance, the attachment position of the side edge detection unit 29 may be unintentionally shifted in the width direction orthogonal to the conveyance direction of the continuous paper WP. The upper graph in FIG. 4 is obtained by detecting the side edge of the continuous paper WP before the regular maintenance, and the lower graph in FIG. 4 is the periodic maintenance in a state where the side edge of the continuous paper WP is not displaced. Later, the side edge of the continuous paper WP is detected again. In addition, since the detection value of the side edge position varies, the measurement is performed while the continuous paper WP is conveyed by about 10 to 20 m. As described above, before and after the periodic maintenance, the side edge position of the continuous paper WP does not move, but the position of the side edge detection unit 29 is shifted, that is, the deviation of the reference value PS causes the continuous paper WP. It can be seen that the position of the side edge is detected with a shift.

  The above-described print position correction can be normally performed only when the reference value PS of the side edge detection unit 29 is not displaced, and as shown in FIG. In the case of displacement, the printing position cannot be normally corrected only by the above procedure. Therefore, the side edge position of the continuous paper WP is detected before the regular maintenance, the side edge position is stored as the pre-displacement side edge position information PBI, and the side edge position of the continuous paper WP is detected after the regular maintenance is completed. Then, the position is stored as post-displacement side end position information PAI. Then, the difference is added to the reference value PS to update the reference value PS.

  Here, with reference to FIG. 5 to FIG. 7, a method for determining a preferable average value of the fluctuating side end position will be described. 5 is a graph of the side end position detected by the side end detection unit, FIG. 6 is a graph showing the tension difference, and FIG. 7 is a graph showing the frequency analysis result of the tension difference. is there.

  When the continuous paper WP is conveyed, the side end position changes as shown in FIG. Since the side end position varies as described above, it is preferable to obtain an average value within a predetermined time instead of an instantaneous value. However, depending on the range in which the average value is calculated, only one of the maximum value and the minimum value may be included, and the accuracy of the average value of the side end position may deteriorate. Therefore, for example, it is preferable that the continuous paper WP is transported by about 10 m or 20 m and the average value of the side end positions is obtained within the transport time.

  By the way, when the difference between the tensions detected by the tension sensors 14L and 14R is obtained together with the measurement of the side end position, the difference fluctuates so as to be interlocked with the movement of the side end position as shown in FIG. Therefore, when the frequency analysis of the difference between the tensions is performed, a graph as shown in FIG. 7 is obtained. In this graph, peaks appear at two locations (0.36 Hz and 0.47 Hz), which approximate the fluctuation frequency of the movement of the side end position. Therefore, when calculating the average value of the side edge position within a predetermined time that is an integer multiple of the period of any of these peak frequencies, the average value within the range including at least the local maximum value and the local minimum value. Therefore, it is possible to suppress the influence of the fluctuation cycle of the side end position and to suppress the decrease in the accuracy of the average value of the side end position.

  Returning now to FIG. The above-described ink jet printing apparatus 3, the paper feed unit 5, and the paper discharge unit 7 are collectively controlled by the main control unit 41. The main control unit 41 includes a control unit 43, a reference value storage unit 45, a pre-displacement side end position information storage unit 47, a post-displacement side end position information storage unit 49, and a frequency analysis unit 51.

  The control unit 43 controls the rotational driving of the drive rollers 9, 13, and 17, performs temperature control of the heat drum 21, and controls inspection by the inspection unit 23. In addition, the control unit 43 stores the arrangement position information of each side edge detection unit 29 in the reference value storage unit 45 as the reference value PS. Further, the pre-displacement side end position information PBI is stored in the pre-displacement side end position information storage unit 47 before periodic maintenance or the like before the displacement of each side end position detection unit 29, and after each side end position detection unit 29 is displaced. After the periodic maintenance or the like, the post-displacement side end position information PAI is stored in the post-displacement position information storage unit 39. Further, the control unit 43 takes a tension signal from the tension sensors 14L and 14R, and based on the frequency component peak obtained by the frequency analysis unit 51 based on the difference between the tensions, a range for obtaining the average value of the side end positions is obtained. decide. The control unit 43 obtains the pre-displacement side end position information PBI and the post-displacement side end position information PAI within the determined range, adds these differences to the reference value PS, and updates the reference value PS. At the time of printing, printing is performed by ejecting ink droplets from the inkjet heads 19a to 19d while correcting the printing position at the side edge based on the reference value PS.

  Next, with reference to FIG. 8, a printing process accompanied by a printing position correction process in the inkjet printing system 1 described above will be described. FIG. 8 is a flowchart showing the operation of the printing process in the inkjet printing system.

Step S1 (reference value storage process)
The reference value PS is stored in the reference value storage unit 45 before performing the printing process of the printed matter that is the product.

Step S2 (correction process)
After the side edge detection unit 29 detects the side edge position of the continuous paper WP, the control unit 43 corrects the print position at the side edge of the continuous paper WP based on the side edge position and the reference value PS. I do.

Step S3
For example, the process branches depending on whether or not the regular maintenance is performed. If so, the process proceeds to step S4. If not, the process returns to step S2 to perform the printing process.

Step S4 (displacement side end position information detection process)
Before performing regular maintenance, the control unit 43 stores the pre-displacement side end position information PBI in the pre-displacement side end position information storage unit 47. At that time, as described above, it is preferable that the frequency analysis is performed on the variation of the side end position, the average value is appropriately obtained, and this is used as the pre-displacement side end position information PBI.

  Note that step S4 may be executed before step S2.

Step S5
Perform regular maintenance. At this time, the arrangement position of the side edge detection unit 29 may be displaced in the width direction of the continuous paper WP.

Step S6 (displacement side end position information detection process)
After performing the periodic maintenance, the control unit 43 stores the post-displacement side end position information PAI in the post-displacement side end position information storage unit 49. In that case, as described above, it is preferable to perform frequency analysis on the variation of the side end position, appropriately obtain an average value, and use this as the post-displacement side end position information PAI.

Step S7 (reference value update process)
The control unit 43 adds the difference between the pre-displacement side end position information PBI and the post-displacement side end position information PAI to the reference value PS, updates the reference value PS, and stores it in the reference value storage unit 45 as a new reference value PS. Let

Step S8
The control unit 43 branches the process according to the presence or absence of the printing process. If there is a printing process, the process returns to step S2 to perform the printing process. At this time, the printing position correction is performed based on the updated reference value PS. On the other hand, if there is no printing process, the process ends.

  According to the present embodiment apparatus, the arrangement position information of the side edge detection unit 29 is stored in the reference value storage unit 45 as the reference value PS, and the continuous paper WP is conveyed before the arrangement position of the side edge detection unit 29 is displaced. 27, the side end position information is detected by the side end detection unit 29 while being conveyed, and is stored in the pre-displacement side end position information storage unit 47 as the pre-displacement side end position information PAI. Further, after the arrangement position of the side end detection unit 29 is displaced, the side end position information is detected by the side end detection unit 29, and this is stored in the post-displacement side end position information storage unit 49 as the post-displacement side end position information PAI. To do. The control unit 43 adds the difference between the pre-displacement side end position information PBI and the post-displacement side end position information PAI to the reference value PS, and updates the reference value PS in the reference value storage unit 45. At the time of printing by the inkjet head 19a (to 19d), the control unit 43 corrects the printing position based on the updated reference value PS. In the reference value PS, the positional deviation of the side edge detection unit 29 is corrected. Therefore, even if the arrangement position of the side edge detection unit 29 is displaced, the reference value PS is updated according to the deviation of the arrangement position of the side edge detection unit 29, so the print start position from the side edge of the continuous paper WP is constant. Printing position correction can be accurately performed.

  Further, since the detection result of the side edge position of the continuous paper WP has a temporal variation, it is possible to obtain a variation by using the pre-displacement side end position information PBI and the post-displacement side end position information PAI based on an average value within a predetermined time. The resulting deterioration in the accuracy of the side end position can be suppressed. Therefore, it is possible to suppress deterioration in accuracy of print position correction.

  In addition, the fluctuation cycle of the side edge position of the continuous paper WP is related to the frequency component in the difference between the tensions on both side edges when the continuous paper WP is conveyed. That is, since the side edge position indicates that the frequency fluctuates at that frequency, the average value of the side edge position information is obtained within a range that is an integral multiple of the period of the peak frequency, whereby the side edge of the continuous paper WP is obtained. The influence of the position fluctuation cycle can be suppressed. Therefore, it can suppress that the precision of the average value of a side end position falls.

  The present invention is not limited to the above embodiment, and can be modified as follows.

  (1) In the above-described embodiment, the ink jet printing apparatus 3 has been described as an example of the printing apparatus. However, the present invention is not limited to the inkjet printing apparatus 3 and can be applied to other types such as a laser type.

  (2) In the above-described embodiment, when the average value of the side edge positions of the continuous paper WP is obtained, the average value within a predetermined time or the integer multiple of the period of the peak frequency based on the result of the frequency analysis of the tension fluctuation. The average value is obtained in the range. However, these are not essential to the present invention, and an average value may be obtained in an arbitrary range if a slight decrease in accuracy can be allowed.

  (3) In the above-described embodiment, a non-contact transmission type optical sensor is adopted as the side edge detection unit 29. However, any type of sensor that can detect the side edge position of the print medium, such as a reflection type optical sensor. It may be a sensor.

  (4) In the above-described embodiments, the continuous paper WP has been described as an example of the print medium. However, the present invention is not limited to this print medium. For example, the present invention can be applied to a printing medium such as a film.

WP: Continuous paper 1 ... Inkjet printing system 3 ... Inkjet printer 5 ... Paper feed unit 7 ... Paper discharge unit 14L, 14R ... Tension sensors 19a to 19d ... Inkjet head 27 ... Conveying unit 29 ... Side edge detection unit PS ... Reference value SP ... interval PA ... printing area Nz ... nozzle PBI ... pre-displacement side end position information PAI ... post-displacement side end position information 41 ... main control unit 43 ... control unit 45 ... reference value storage unit 47 ... pre-displacement side end position information storage unit 49 ... Displacement side edge position information storage unit 51 ... Frequency analysis unit

Claims (4)

A side end that is disposed along the transport unit and detects a side end position of the print medium when the print unit performs printing with the print medium while transporting the long print medium along the transport unit. A printing position correction method for performing printing while correcting a printing position from a side edge position of the printing medium by the printing unit based on side edge position information from a detection unit,
A reference value storage process for storing, as a reference value, arrangement position information of the side edge detection unit for determining an interval between a print region end perpendicular to the conveyance direction of the print medium and a side edge of the print medium;
The pre-displacement side end position for detecting the side end position information of the print medium as the pre-displacement side end position information by the side end detection unit in a state where the print medium is conveyed before the arrangement position of the side end detection unit is displaced. Information detection process;
A displacement rear side end that detects side edge position information of the printing medium as displacement side edge position information by the side edge detection unit in a state where the printing medium is conveyed after the arrangement position of the side edge detection unit is displaced. The location information detection process;
A reference value update process for updating the reference value by adding a difference between the displacement front end position information and the displacement rear end position information to the reference value;
A correction process for correcting the printing position based on the updated reference value when printing by the printing unit;
A printing position correction method comprising: The printing position correction method according to claim 1,
In the pre-displacement side end position information detection process and the post-displacement side end position information detection process, the print medium is transported for a predetermined time, and the pre- displacement side end position information is determined by an average value of the side end position information within the predetermined time. And a displacement-side edge position information. The printing position correction method according to claim 2,
The average value is calculated within a range within an integral multiple of a period of a frequency at which a frequency component is extracted for a difference between tensions at both ends at the time of transporting the print medium, and the peak frequency is printed. Correction method. A printing device that performs printing while correcting the printing position from the side edge position when printing on a long print medium,
A transport unit for transporting the print medium;
A printing unit that performs printing on the print medium being conveyed through the conveyance unit;
A side edge detection unit that is arranged along the transport unit, detects a side edge position of the print medium, and outputs side edge position information;
A reference value storage unit that stores, as a reference value, arrangement position information of the side edge detection unit for determining an interval between a print region end perpendicular to the conveyance direction of the print medium and a side end of the print medium;
Displacement that stores side edge position information of the print medium detected by the side edge detection unit as pre-displacement side edge position information in a state in which the print medium is conveyed before the arrangement position of the side edge detection unit is displaced. A front end position information storage unit;
Displacement for storing side edge position information of the print medium detected by the side edge detection unit as post-displacement side edge position information in a state where the print medium is conveyed after the arrangement position of the side edge detection unit is displaced A rear end position information storage unit;
The reference value is updated by adding the difference between the pre-displacement side end position information and the post-displacement side end position information to the reference value, and at the time of printing by the printing unit, the updated reference value A control unit for correcting the printing position based on
A printing apparatus comprising:

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