Discharge position correction method, and printing device

Abstract

[Problem] To reduce positional deviation of droplets discharged from a head. [Solution] In an adjustment pattern printing step S10 of this discharge position correction method, a processing unit 42 positions a head 20 at each of a plurality of target positions P that are at intervals of a prescribed distance d in an X direction from a reference position O of a mounting surface 10a, and discharges droplets while relatively moving the head 20 in a Y direction (main scanning direction), thereby printing a plurality of adjustment patterns R arranged in the X direction on a medium M. In a deviation amount detection step S20, the processing unit 42 detects the deviation amount in the X direction for each of the plurality of target positions P, on the basis of the positional relationship between adjustment patterns R that neighbor each other in the X direction. In a correction amount calculation step S30, for each of the plurality of target positions P, the processing unit 42 calculates a correction amount in the X direction for the discharge position, on the basis of the deviation amount detected in the deviation amount detection step S20.

Description

Ejection position correction method and printing device

[0001] The present invention relates to a method for correcting ejection positions and a printing apparatus.

[0002] Known printing devices that print on media include inkjet printing devices that eject droplets from a head onto the media (see, for example, Patent Document 1). Such printing devices include, for example, a table on which the media can be placed and a head that ejects droplets toward the surface of the media while moving back and forth in a main scanning direction over the table. This printing device ejects droplets while moving the head in the main scanning direction, then moves the head a predetermined distance in a sub-scanning direction that intersects the main scanning direction, and then again moves back and forth in the main scanning direction and ejects droplets. By repeating this operation, an image is formed across the entire media, one or more rows at a time.

[0003] Japanese Patent Application Laid-Open No. 2017-109360

[0004] In the printing device described above, the head is supported on a table, and so when the head is moved in the sub-scanning direction, the tilt of the head relative to the table may change, which may cause the position of the droplets ejected from the head to shift.

[0005] The present invention has been made in view of the above, and has as its object to reduce positional deviation of droplets ejected from a head of a printing device.

[0006] a head having a plurality of nozzles arranged opposite to the mounting surface and configured to eject droplets from the plurality of nozzles toward the mounting surface; a relative movement mechanism that moves the table and the head relatively in a main scanning direction and a sub-scanning direction along the mounting surface; and a control unit that controls the relative movement between the table and the head by the relative movement mechanism and the ejection of the droplets by the head to perform a printing operation on the medium, the ejection position correction method comprising: (1) a printing device including: a table having a mounting surface for a medium; The method includes a deviation amount detection step of detecting a deviation amount in the sub-scanning direction for each of the plurality of target positions based on a positional relationship between the adjustment patterns adjacent to each other in the sub-scanning direction, and a correction amount calculation step of calculating a correction amount in the sub-scanning direction for the ejection position for each of the plurality of target positions based on the deviation amount.

[0007] (2) In the ejection position correction method of (1), the table has a plurality of top plate members connected in the sub-scanning direction, and the plurality of target positions are arranged so as to straddle the connecting portions of the top plate members in the sub-scanning direction.

[0008] (3) In the ejection position correction method of (1) or (2), the adjustment pattern includes an adjustment portion arranged upstream in the sub-scanning direction, and a reference portion arranged downstream in the sub-scanning direction at the predetermined distance from the adjustment portion.

[0009] (4) In the ejection position correction method of (3), the adjustment portion and the reference portion are straight lines parallel to the main scanning direction.

[0010] (5) In the ejection position correction method of (3) or (4), the adjustment portion and the reference portion have different lengths in the main scanning direction.

[0011] (6) A printing device according to the present invention is a printing device comprising: a table having a mounting surface for a medium; a head having a plurality of nozzles arranged opposite to the mounting surface and discharging droplets from the plurality of nozzles toward the mounting surface; a relative movement mechanism for relatively moving the table and the head in a main scanning direction and a sub-scanning direction along the mounting surface; and a control unit for controlling the relative movement between the table and the head by the relative movement mechanism and the discharging of the droplets by the head to perform a printing operation on the medium, wherein the control unit comprises: a storage unit for storing a deviation amount in the sub-scanning direction of a discharge position at which the head discharges the droplets relative to the mounting surface; and a processing unit for calculating a correction amount in the sub-scanning direction of the discharge position based on the deviation amount, and correcting the discharge position based on the correction amount to perform the printing operation, wherein the deviation amount is a printing device in which the head is positioned at each of a plurality of target positions spaced a predetermined distance apart in the sub-scanning direction from a reference position on the mounting surface, and the head is moved relatively in the main scanning direction while ejecting the droplets to print a plurality of adjustment patterns arranged in the sub-scanning direction on the medium, and the positional relationship between adjacent adjustment patterns is detected based on the positional relationship between the adjustment patterns.

[0012] According to the present invention, it is possible to reduce positional deviation of droplets ejected from the head of a printing device.

[0013] FIG. 1 is a diagram (perspective view) showing an example of the schematic configuration of a printing device according to this embodiment. FIG. 2 is a diagram (plan view) showing an example of the schematic configuration of a printing device according to this embodiment. FIG. 3 is a diagram (side view seen from the Y1 side) showing an example of the schematic configuration of a printing device according to this embodiment. FIG. 4 is a diagram (front view seen from the X1 side) showing an example of the schematic configuration of a printing device according to this embodiment. FIG. 5 is a flowchart showing an example of a method for correcting ejection position according to this embodiment. FIG. 6 is a diagram schematically showing an example of an operation for printing an adjustment pattern on a medium. FIG. 7 is a diagram showing an example of an adjustment pattern formed on a medium. FIG. 8 is a diagram showing an example of a deviation amount table stored in a storage unit. FIG. 9 is a diagram schematically showing an example of a printing operation.

[0014] Hereinafter, an embodiment of a method for correcting ejection position and a printing apparatus according to the present invention will be described with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments. Furthermore, the components in the following embodiments include those that are easily replaceable by those skilled in the art, or those that are substantially the same.

[0015] In this embodiment, directions in the drawings are explained using an XYZ coordinate system. In this XYZ coordinate system, a plane parallel to the floor on which the printing device 100 is placed is referred to as the XY plane. In this XY plane, the main scanning direction, which is the movement direction of the head 20, is referred to as the Y direction, and the direction perpendicular to the Y direction on the XY plane is referred to as the X direction. The direction perpendicular to the XY plane (height direction) is referred to as the Z direction. One side of the X direction (the left side in FIG. 2) may be referred to as the X1 side, and the other side (the right side in FIG. 2) as the X2 side. The X1 side is the front side of the printing device 100, and the X2 side is the rear side. One side of the Y direction (the upper side in FIG. 2) may be referred to as the Y1 side, and the other side (the lower side in FIG. 2) as the Y2 side. The Z direction may also be referred to as the lower side and the upper side.

[0016] 1 to 4 are diagrams showing an example of the schematic configuration of a printing apparatus 100 according to this embodiment. FIG. 1 is a perspective view, FIG. 2 is a plan view, FIG. 3 is a side view seen from the Y1 side, and FIG. 4 is a front view seen from the X1 side. As shown in FIGS. 1 to 4, in this embodiment, the printing apparatus 100 will be described as an image forming apparatus that forms an image on a medium M such as a film or plate material. As shown in FIG. 1, the printing apparatus 100 includes a table 10, a head 20, a head movement mechanism 30 (relative movement mechanism), and a control unit 40.

[0017] 1 , the table 10 supports the media M and the head moving mechanism 30. The table 10 has a mounting surface 10a on which the media M is placed. The table 10 has a plurality of top plate members 11 and a support portion 12.

[0018] The top panel member 11 is a rectangular plate. The top panel members 11 are arranged in a connected state in the X direction. The table 10 is configured such that the length of the table 10 is in the X direction by connecting the multiple top panel members 11 in the X direction. The support surfaces 11a of the multiple top panel members 11 are arranged flush with each other to form the support surface 10a of the table 10. The table 10 has at least one connection portion 14 of the top panel member 11 between one end and the other end in the X direction.

[0019] 3 , the top panel members 11 have positioning portions 13 on opposing surfaces 11f that face each other in the X direction. The positioning portions 13 have, for example, a recessed portion 13a provided on one of the top panel members 11 and a protruding portion 13b provided on the other top panel member 11. The positioning portions 13 position the top panel members 11 relative to each other in the Y and Z directions by inserting the protruding portion 13b into the recessed portion 13a. Furthermore, by positioning the top panel members 11 relative to each other by the positioning portions 13, components that are provided across multiple top panel members 11, such as X guide portions 36a and 36b (described below) provided on the top panel members 11, are also positioned relative to each other.

[0020] As shown in FIGS. 1 to 3 , the support portion 12 supports the tabletop member 11. The support portion 12 has a plurality of legs 12a and 12b. The legs 12a and 12b are arranged side by side in the X direction along both Y-direction edges of the tabletop member 11. The legs 12a are supported by a floor F. The legs 12b are supported by connecting members 12c that connect the legs 12a to each other. The legs 12b may be fixed to the connecting members 12c by welding, or may be fastened to the connecting members 12c with fastening members such as bolts. Note that the connecting members 12c may be omitted, and the legs 12b may be directly supported by the floor F.

[0021] As shown in FIG. 4 , the head 20 has a nozzle surface 21 facing the mounting surface 10 a. The nozzle surface 21 is, for example, planar. The nozzle surface 21 faces the mounting surface 10 a of the table 10 with a gap G in the Z direction. As shown within the dashed-line frame in FIG. 4 , the nozzle surface 21 is provided with a plurality of nozzles n that eject ink (droplets). Note that the dashed-line frame schematically illustrates the arrangement of the nozzles n when the nozzle surface 21 is viewed from below in the Z direction. The plurality of nozzles n are arranged at intervals in the X and Y directions, forming nozzle rows in the X and Y directions. Note that the nozzle arrangement shown in the figure is merely an example and can be changed as appropriate. Examples of ink include ultraviolet-curable ink. Types of ultraviolet-curable ink include white ink, colored inks such as cyan (C), magenta (M), yellow (Y), and black (K), and transparent ink, depending on the color of the image to be formed on the medium M. The head 20 is electrically connected to the control unit 40, and its drive is controlled by the control unit 40. The head 20 is connected to an ink supply device (not shown), and receives a supply of ink from the ink supply device. The head 20 is movable in the Y direction (main scanning direction) together with the carriage 22. The head 20 ejects ink toward the mounting surface 10a while moving back and forth along the Y direction. In a configuration in which ultraviolet-curable ink is ejected from the head 20, the carriage 22 is equipped with an ultraviolet irradiation device (not shown) that irradiates ultraviolet light onto the ultraviolet-curable ink.

[0022] The head moving mechanism 30 is supported by the table 10 and moves the head 20 in the X and Y directions along the mounting surface 10a of the table 10. The head moving mechanism 30 moves the head 20 in the X and Y directions relative to the table 10, thereby moving the table 10 and the head 20 relatively. The head moving mechanism 30 has a main scanning moving unit 31 and a sub-scanning moving unit 32.

[0023] The main scanning movement unit 31 has a Y bar 33 and a Y slider 34. The Y bar 33 is arranged parallel to the Y direction. The Y bar 33 guides the carriage 22 in the Y direction. The Y bar 33 is supported by the sub-scanning movement unit 32. The Y slider 34 is provided on the carriage 22 and slides in the Y direction along the Y bar 33. As shown in FIG. 1 , the main scanning movement unit 31 has a Y drive unit 35. The Y drive unit 35 moves the Y slider 34 in the Y direction. The Y drive unit 35 has a drive source such as a motor, and a transmission mechanism such as a belt that transmits the drive force of the drive source to the Y slider 34.

[0024] As shown in FIG. 2 , the sub-scanning movement unit 32 has an X guide 36 and an X slider 37. The X guides 36 are provided on both side surfaces 11e of the tabletop member 11 in the Y direction. The X guides 36 extend in the X direction and are arranged to straddle both sides of multiple tabletop members 11 in the X direction. Specifically, an X guide portion 36a arranged on both side surfaces 11e of one tabletop member 11 is connected to an X guide portion 36b arranged on both side surfaces 11e of another tabletop member 11 in the X direction. The X slider 37 is provided on the carriage 22 and slides in the X direction along the X guide 36. As shown in FIG. 1 , the sub-scanning movement unit 32 has an X drive unit 38. The X drive unit 38 moves the X slider 37 in the X direction. The X drive unit 38 has a drive source such as a motor and a transmission mechanism such as a belt that transmits the drive force of the drive source to the X slider 37.

[0025] The control unit 40 comprehensively controls the operation of the printing device 100. The control unit 40 controls the relative movement between the table 10 and the head 20 and the ejection of droplets by the head 20, thereby performing a printing operation in which droplets are ejected toward the medium M placed on the placement surface 10a. The control unit 40 has a communication unit 41, a processing unit 42, and a memory unit 43.

[0026] The communication unit 41 performs wired or wireless communication with external devices and includes an interface such as a network interface card.

[0027] The processing unit 42 performs various types of information processing. The processing unit 42 includes a processor such as a CPU (Central Processing Unit) that functions as a controller that executes various types of processing, and a memory such as a ROM (Read Only Memory) or a RAM (Random Access Memory) that functions as a memory that stores various types of information.

[0028] The processing unit 42 performs processing related to the operation of the head 20. The processing by the processing unit 42 causes ink to be ejected from the nozzles n of the head 20. The processing by the processing unit 42 also causes ultraviolet light to be emitted from the ultraviolet light irradiation device.

[0029] The processing unit 42 performs processing related to the operation of the head moving mechanism 30. Through the processing of the processing unit 42, the Y slider 34 is driven by the Y drive unit 35, and the carriage 22 moves in the Y direction, which is the main scanning direction. Through the processing of the processing unit 42, the X slider 37 is driven by the X drive unit 38, and the main scanning movement unit 31 and the carriage 22 move in the X direction, which is the sub-scanning direction. For example, a program or the like that defines the movement speed, movement direction, movement timing, etc. of the Y slider 34 and the X slider 37 can be created in advance and stored in the storage unit 43, and the movement of the Y slider 34 and the X slider 37 can be controlled by the head moving mechanism 30 executing the program.

[0030] The storage unit 43 stores information such as various programs and data. In this embodiment, the storage unit 43 stores the amount of deviation of an adjustment pattern, which will be described later. The storage unit 43 includes storage such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

[0031] In the control unit 40, the processor in the processing unit 42 reads out various programs and loads them into memory, thereby executing information processing corresponding to the functions of the above-mentioned units. Examples of the various programs include programs received by the communication unit 41, programs stored in the storage unit 43, and programs recorded on an external recording medium. The control unit 40 functions as an information processing device (computer) that executes various information processes. Note that the various programs may be executed by an information processing device other than the control unit 40, or the control unit 40 and the other information processing device may cooperate to execute the various programs.

[0032] In the printing device 100, the head 20 is supported on a table 10. The table 10 is configured by connecting multiple top plate members 11. In this configuration, when the head 20 is moved in the X direction, the inclination of the head 20 (nozzle surface 21) relative to the table 10 may change depending on the position of the head 20 in the X direction. In this case, droplets ejected from the head 20 may deviate from their appropriate positions on the medium M. When causing the printing device 100 to perform a printing operation, the processing unit 42 of the control unit 40 performs an ejection position correction method that corrects the ejection position of the head 20 in the X direction (sub-scanning direction).

[0033] 5 is a flowchart showing an example of a method for correcting ejection positions according to this embodiment. The method for correcting ejection positions includes an adjustment pattern printing step S10, a deviation amount detection step S20, a correction amount calculation step S30, and a correction step S40.

[0034] In the adjustment pattern printing step S10, the processing unit 42 causes the printing device 100 to print the adjustment pattern R on the medium M. FIG. 6 is a diagram schematically illustrating an example of the operation of printing the adjustment pattern R on the medium M. During the adjustment pattern printing step S10, the medium M is placed on the placement surface 10a, as shown in FIG. 6. The processing unit 42 controls the head movement mechanism 30 of the printing device 100 to relatively move the head 20 from the X2 side to the X1 side in the X direction, and position it at each of the ejection positions Q (Q1, Q2, ..., QN (N is a natural number)). In other words, when printing the adjustment pattern R, the upstream side of the movement direction of the head 20 in the X direction is the X2 side, and the downstream side is the X1 side. The ejection positions Q (Q1, Q2, ..., QN (N is a natural number)) are positions corresponding to each of multiple target positions P (P1, P2, ..., PN (N is a natural number)) spaced apart by a predetermined distance d in the X direction from the reference position O on the mounting surface 10a.

[0035] The target position P can be set, for example, as an X coordinate with the reference position O on the mounting surface 10a as the origin. The multiple target positions P are set so as to straddle the connection portion 14 of the table 10 in the X direction. In the illustrated example, the connection portion 14 of the table 10 is located between the target positions P6 and P7. When the table 10 is composed of multiple tabletop members 11, the inclination of the head 20 tends to change across the connection portion 14. Therefore, by arranging the multiple target positions P so as to straddle the connection portion 14 of the table 10 in the X direction, it becomes easier to accommodate changes in the inclination of the head 20. At each target position P, the processing unit 42 ejects droplets while moving the head 20 relatively in the Y direction. In the illustrated example, the processing unit 42 moves the head 20 to ejection positions Q1 to Q12 corresponding to the target positions P1 to P12. The processing unit causes the head 20 to eject droplets at each of the ejection positions Q1 to Q11, and does not eject droplets at the final ejection position Q12.

[0036] This operation prints multiple alignment patterns R (R1, R2, ... RN (N is a natural number)) in lines aligned in the X direction on the medium M. In the example shown, adjustment patterns R R1 to R11 (N=11) are printed.

[0037] FIG. 7 is a diagram showing an example of an adjustment pattern R formed on the medium M. The X, Y, and Z directions shown in FIG. 7 indicate the directions when the medium M is placed on the placement surface 10a. As shown in FIG. 7, each adjustment pattern R includes an adjustment portion Ra and a reference portion Rb. The adjustment portion Ra is located on the X2 side of the reference portion Rb. It is located upstream in the X direction. The reference portion Rb is located downstream in the X direction, spaced a predetermined distance d from the adjustment portion Ra. As described above, nozzle rows are formed in the X and Y directions on the nozzle surface 21 of the head 20 (see the dashed-line frame in FIG. 4). The adjustment portion Ra and the reference portion Rb can be formed by nozzle rows NY1 and NY2 in the Y direction, spaced apart in the X direction. For example, the adjustment portion Ra can be formed by the nozzle row NY1, and the reference portion Rb can be formed by the nozzle row NY2, which is located on the X1 side (downstream) of the nozzle row NY1. The distance between the nozzle row NY1 and the nozzle row NY2 corresponds to a predetermined distance d. Note that the nozzle row forming the adjustment portion Ra and the reference portion Rb is not limited to one row, but may be multiple nozzle rows. Furthermore, the nozzle row is not limited to ejecting droplets from all nozzles n, but may eject droplets from some of the nozzles n.

[0038] In this embodiment, the adjustment portion Ra and the reference portion Rb may be, for example, straight lines extending parallel to each other along the Y direction. The adjustment portion Ra and the reference portion Rb have different lengths in the Y direction. In this embodiment, the reference portion Rb is longer in the Y direction than the adjustment portion Ra. The adjustment portion Ra may also be longer in the Y direction than the reference portion Rb. The adjustment portion Ra and the reference portion Rb may have different colors. Note that the adjustment portion Ra and the reference portion Rb are not limited to straight lines and may have other shapes such as curves, dashed lines, or planar figures. In FIG. 7 , to make it easier to distinguish between the adjustment portion Ra and the reference portion Rb, the adjustment portion Ra is indicated by a solid line and the reference portion Rb is indicated by a dashed line.

[0039] In the adjustment pattern R, the adjustment portion Ra and the reference portion Rb are spaced a predetermined distance d in the X direction. Each adjustment pattern R is formed by moving the head 20 by the predetermined distance d in the X direction. Therefore, the second and subsequent adjustment patterns R are formed so that the target position of the adjustment portion Ra overlaps the reference portion Rb of the previously formed adjustment pattern R. Note that the adjustment portion Ra of adjustment pattern R1 corresponding to reference position P1 and the reference portion Rb of adjustment pattern R11 corresponding to reference position P12 do not overlap with other adjustment patterns R.

[0040] If there is no change in the tilt of the head 20 relative to the table 10, the adjustment portion Ra of each adjustment pattern R and the reference portion Rb of the adjustment pattern R formed immediately before are ejected at the same position in the X direction and overlap when viewed from the Z direction. In the example of Fig. 7, as shown in detection portion A, the adjustment portions Ra of adjustment patterns R6 to R11 overlap with the reference portions Rb of adjustment patterns R5 to R10 formed immediately before, respectively, and no misalignment occurs in the X direction.

[0041] On the other hand, when the tilt of the head 20 relative to the table 10 changes, the adjustment portion Ra of each adjustment pattern R may not overlap with the reference portion Rb of the previously formed adjustment pattern R, and may be shifted in the X direction (toward the X1 or X2 direction). In the example of Figure 7, as shown in detection portion B, the adjustment portions Ra of adjustment patterns R3 and R4 are shifted toward the X2 side relative to the reference portion Rb of the previously formed adjustment patterns R2 and R3. As shown in detection portion C, the adjustment portions Ra of adjustment patterns R2 and R5 are shifted toward the X1 side relative to the reference portion Rb of the previously formed adjustment patterns R1 and R4, respectively. Note that the shift between the adjustment portion Ra and the reference portion Rb occurs in μm units, and is exaggerated in Figure 7.

[0042] In the deviation amount detection step S20, the processing unit 42 calculates the deviation amount in the X direction of the ejection position Q of the head 20 based on the multiple adjustment patterns R printed on the medium M. The processing unit 42 calculates the deviation amount in the X direction for each of the multiple adjustment patterns R relative to the target position P based on the positional relationship between adjacent adjustment patterns R in the X direction among the multiple adjustment patterns R. For example, the deviation toward the X1 side can be a positive value, and the deviation toward the X2 side can be a negative value. In the example of FIG. 7 , the deviation amount of detection portion A is 0, the deviation amount of detection portion B is a negative value, and the deviation amount of detection portion C is a positive value.

[0043] An imaging device 23 such as a camera or scanner can be provided on the carriage 22 or the like of the printing device 100. When detecting the amount of misalignment, the processing unit 42 acquires an image of the adjustment pattern R formed on the medium M by the imaging device 23. The processing unit 42 can detect the amount of misalignment by performing image processing or the like on the acquired image. The processing unit 42 stores the detected amount of misalignment in the memory unit 43 in association with the target position P. As a result, a misalignment amount table in which each target position P is associated with the amount of misalignment is stored in the memory unit 43.

[0044] FIG. 8 is a diagram showing an example of a deviation amount table stored in the memory unit 43. As shown in FIG. 8, the deviation amount table records the deviation amount detected for each target position P1 to P12 using the corresponding adjustment patterns R1 to R2. The deviation amount is a value obtained by subtracting the X-coordinate of the reference portion Rb of the previously formed adjustment pattern R from the X-coordinate of the adjustment portion Ra of each adjustment pattern R, and can be measured in units of μm, for example. As described above, the adjustment portion Ra of adjustment pattern R1 corresponding to target position P1 and the reference portion Rb of adjustment pattern R11 corresponding to target position P12 do not overlap with other adjustment patterns R. Therefore, the deviation amount recorded for target positions P1 and P12 is zero. This setting improves the accuracy of linear interpolation.

[0045] In the correction amount calculation step S30, the processing unit 42 calculates the correction amount of the ejection position Q based on the deviation amount stored in the memory unit 43. The processing unit 42 calculates the correction amount of the ejection position Q in the X direction of the head 20 for each of the multiple target positions P based on the relationship between the target position P and the deviation amount stored in the memory unit 43. Here, the correction amount is the amount of change by which the ejection position Q of the head 20 is changed to the X1 side or the X2 side.

[0046] 8, the deviation amount for the target positions P6 to P11 is 0. That is, at the ejection positions Q6 to Q11 corresponding to the target positions P6 to P11, the droplets ejected from the head 20 land at the appropriate positions. The processing unit 42 determines the correction amount for the ejection positions Q6 to Q11 to be 0.

[0047] In the example of Figure 8, the deviation amounts of target positions P2 and P5 are positive (+) values. That is, droplets ejected from the head 20 at ejection positions Q2 and Q5 corresponding to target positions P2 and P5 land at positions that are shifted toward the X1 side. In this case, the processing unit 42 calculates the correction amounts for shifting ejection positions Q2 and Q5 toward the X2 side. For example, the processing unit 42 can calculate the correction amount for ejection position Q2 as -5 and the correction amount for ejection position Q5 as -4.

[0048] In the example of Figure 8, the deviation amounts of target positions P3 and P4 are negative. That is, at ejection positions Q3 and Q4 corresponding to target positions P3 and P4, droplets ejected from the head 20 land at positions that are shifted toward the X2 side. In this case, the processing unit 42 calculates the correction amount for shifting ejection positions Q3 and Q4 toward the X1 side. For example, the processing unit 42 can calculate the correction amount for ejection position Q3 as +3 and the correction amount for ejection position Q4 as +7.

[0049] The processing unit 42 associates the correction amount calculated as described above with the target position P and stores it in the storage unit 43 .

[0050] After performing the correction amount calculation step S30, the processing unit 42 may perform the adjustment pattern printing step S10 again so as to form the adjustment pattern R at the corrected ejection position Q' corrected by the correction amount. The processing unit 42 may also perform the deviation amount detection step S20 and the correction amount calculation step S30 again based on the reprinted adjustment pattern R. In this case, the processing unit 42 can update the correction amount based on the calculation result calculated in the correction amount calculation step S30 again.

[0051] FIG. 9 is a diagram schematically illustrating an example of a printing operation. FIG. 9 illustrates a printing operation corresponding to the deviation amount table in FIG. 8 . As described above, the deviation amount is in μm units, and FIG. 9 exaggerates the correction of the ejection position Q. As shown in FIG. 9 , in the correction step S40, the processing unit 42 corrects the ejection position Q corresponding to multiple target positions P based on the calculated correction amount, and then performs the printing operation. The X coordinate of the corrected ejection position Q' is the value obtained by adding the correction amount to the X coordinate of the ejection position Q before correction (the same as the X coordinate of the target position P). For ejection positions Q2 to Q5, the processing unit 42 positions the head 20 at the corrected ejection position Q' using the head movement mechanism 30. The processing unit 42 causes the head 20 to eject droplets S while moving the head 20 in the Y direction using the head movement mechanism 30. As a result, the droplets S are ejected at the corrected ejection position Q', allowing the droplets S to land at the appropriate positions.

[0052] As described above, the ejection position correction method according to this embodiment includes, for example, the following steps. (1) The ejection position correction method according to this embodiment is a method for correcting the ejection position of the head 20 in the printing device 100. The printing device 100 includes a table 10, a head 20, a head movement mechanism 30 (relative movement mechanism), and a control unit 40. The table 10 has a mounting surface 10a (11a, 11a) on which the medium M is placed. The head 20 has a plurality of nozzles n arranged opposite the mounting surface 10a, and ejects droplets from the plurality of nozzles n toward the mounting surface 10a. The head movement mechanism 30 moves the table 10 and the head 20 relatively in the Y direction (main scanning direction) and the X direction (sub-scanning direction) along the mounting surface 10a. The control unit 40 controls the relative movement of the table 10 and the head 20 by the head movement mechanism 30 and the ejection of droplets by the head 20 to perform a printing operation on the medium M. The ejection position correction method includes an adjustment pattern printing step S10 (pattern printing step), a misalignment amount detection step S20, and a correction amount calculation step S30. In the adjustment pattern printing step S10, the processing unit 42 of the control unit 40 prints multiple adjustment patterns R aligned in the X direction (sub-scanning direction) on the medium M placed on the mounting surface 10a. Specifically, the processing unit 42 positions the head 20 at each of multiple target positions P spaced a predetermined distance d apart in the X direction from a reference position O on the mounting surface 10a, and ejects droplets while moving the head 20 relatively in the Y direction (main scanning direction), thereby printing the multiple adjustment patterns R on the medium M. In the misalignment amount detection step S20, the processing unit 42 detects the amount of misalignment in the X direction for each of the multiple target positions P based on the positional relationship between adjacent adjustment patterns R in the X direction. In the correction amount calculation step S30, the processing unit 42 calculates the correction amount of the ejection position in the X direction for each of the plurality of target positions P based on the amount of deviation detected in the deviation amount detection step S20.

[0053] The ejection position correction method of this embodiment can reduce misalignment of droplets ejected from the head 20. In the ejection position correction method of this embodiment, multiple adjustment patterns R aligned in the X direction are printed on the medium M, and the amount of misalignment in the X direction for each of the multiple adjustment patterns R relative to the target position P is detected based on the positional relationship between adjacent adjustment patterns R in the X direction. A correction amount for the ejection position in the X direction is calculated for each of the multiple target positions P based on the misalignment amount, and the ejection position Q during the printing operation is corrected based on the calculated correction amount. In other words, this embodiment is a simple method of printing the adjustment patterns R on the medium M, which can detect misalignment of the ejection position Q and calculate the correction amount. The control unit 40 then controls the printing operation of the printing device 100 based on the calculated correction amount, thereby improving print quality.

[0054] (2) In the ejection position correction method according to this embodiment, the table 10 has a plurality of top plate members 11 connected in the X direction, and the plurality of target positions P can be arranged so as to straddle the connection portions 14 between the top plate members 11 in the X direction.

[0055] When the table 10 is configured by connecting multiple top plate members 11, the inclination of the head 20 relative to the table 10 tends to change at the connection portions 14 between the top plate members 11. By arranging the multiple target positions P so that they straddle the connection portions 14 between the top plate members 11 in the X direction, the adjustment pattern R is formed so that it straddles the connection portions 14. This makes it easier for the adjustment pattern R to reflect changes in the inclination of the head 20, and the accuracy of detecting the amount of deviation of the ejection position Q can be improved.

[0056] (3) In the ejection position correction method according to this embodiment, the adjustment pattern R includes an adjustment portion Ra disposed on the upstream side (X1 side) in the X direction, and a reference portion Rb disposed on the downstream side (X2 side) in the X direction at a predetermined distance d from the adjustment portion Ra. (i) The processing unit 42 can detect, as the amount of deviation at each target position P, the amount of deviation in the X direction between the adjustment portion Ra of the adjustment pattern R formed at each target position P and the reference portion Rb of the adjustment pattern R formed at the adjacent target position P upstream in the X direction.

[0057] Each adjustment pattern R is formed by moving the head 20 in the X direction by a predetermined distance d. The adjustment portion Ra of the second or subsequent adjustment pattern R formed in the X direction is formed so as to overlap the reference portion Rb of the previously formed adjustment pattern R, but if the head 20 is tilted, a misalignment will occur between the two. By detecting the amount of this misalignment, the ejection position Q can be easily corrected.

[0058] (4) In the ejection position correction method according to this embodiment, the adjustment portion Ra and the reference portion Rb can be straight lines parallel to the main scanning direction.

[0059] By forming the adjustment portion Ra and the reference portion Rb as straight lines, it becomes easier to detect the amount of deviation of the ejection position Q while suppressing the amount of droplets consumed when forming the adjustment portion Ra and the reference portion Rb.

[0060] (5) In the ejection position correction method according to this embodiment, the adjustment portion Ra and the reference portion Rb have different lengths in the Y direction.

[0061] This configuration makes it easier for the worker to distinguish between the adjustment portion Ra and the reference portion Rb.

[0062] The printing device 100 according to this embodiment has, for example, the following configuration. (6) The printing device 100 includes a table 10, a head 20, a head movement mechanism 30 (relative movement mechanism), and a control unit 40. The table 10 has a mounting surface 10a (11a, 11a) on which the medium M is placed. The head 20 has a plurality of nozzles n disposed opposite the mounting surface 10a, and ejects droplets from the plurality of nozzles n toward the mounting surface 10a. The head movement mechanism 30 moves the table 10 and the head 20 relatively in the Y direction and the X direction along the mounting surface 10a. The control unit 40 controls the relative movement of the table 10 and the head 20 by the head movement mechanism 30 and the ejection of droplets by the head 20 to perform a printing operation on the medium M. The control unit 40 includes a memory unit 43 and a processing unit 42. The memory unit 43 stores the amount of deviation in the X direction of the ejection position Q at which the head 20 ejects droplets relative to the mounting surface 10a. The processing unit 42 calculates the amount of correction in the X direction of the ejection position Q based on the amount of deviation stored in the memory unit 43, and performs a printing operation by correcting the ejection position Q based on the correction amount. The amount of deviation is detected based on the positional relationship between adjacent adjustment patterns R among multiple adjustment patterns R lined up in the X direction that are printed on the medium M by positioning the head 20 at each of multiple target positions P spaced a predetermined distance d apart in the X direction from a reference position O on the mounting surface 10a and ejecting droplets while moving the head 20 relatively in the Y direction.

[0063] The printing device 100 of this embodiment can reduce misalignment of droplets ejected from the head 20. The printing device 100 of this embodiment prints multiple adjustment patterns R aligned in the X direction on the medium M, detects the amount of misalignment in the X direction for each of the multiple adjustment patterns R relative to the target position P based on the positional relationship between adjacent adjustment patterns R in the X direction, calculates a correction amount for the ejection position Q in the X direction for each of the multiple target positions P based on the misalignment amount, and corrects the ejection position Q during the printing operation based on the calculated correction amount. That is, in this embodiment, a simple method of printing the adjustment patterns R on the medium M can detect misalignment of the ejection position Q and calculate the correction amount. The control unit 40 then controls the printing operation of the printing device 100 based on the calculated correction amount, thereby improving print quality.

[0064] The technical scope of the present invention is not limited to the above-described embodiment, and appropriate modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, a configuration in which the table 10 and the head 20 are moved relative to each other by moving the head 20 relative to the table 10 has been described as an example, but the present invention is not limited to this configuration. For example, a configuration in which the table 10 and the head 20 are moved relative to each other by moving the table 10 relative to the head 20 may also be used.

[0065] In the above embodiment, the configuration in which the multiple target positions P are arranged to straddle the connection portions 14 of the tabletop members 11 in the X direction has been described as an example, but the configuration is not limited to this. The multiple target positions P may be arranged so as not to straddle the connection portions 14 of the tabletop members 11. Furthermore, the table 10 may be configured not to have multiple tabletop members 11.

[0066] A, B, C...detection portion, F...floor portion, M...media, O...reference position, P, P1 to P12...target position, R, R1 to R11...adjustment pattern, Ra...adjustment portion, Rb...reference portion, Q, Q1 to Q11...ejection position, S...droplet, 10...table, 10a, 11a...mounting surface, 11...top plate member, 11e...side surface, 11f...opposing surface, 12...support portion, 12a, 12b...leg portion, 12c...connecting member, 13...positioning portion, 13a...recess, 13b...protrusion, 14...connecting portion, 20... Head, 21... nozzle surface, 22... carriage, 23... imaging device, 30... head moving mechanism, 31... main scanning moving section, 32... sub-scanning moving section, 33... Y bar, 34... Y slider, 35... Y driving section, 36... X guide, 36a, 36b... X guide portion, 37... X slider, 38... X driving section, 40... control section, 41... communication section, 42... processing section, 43... storage section, 100... printing device

Claims

1. A printing device comprising: a table having a mounting surface for a medium; a head having a plurality of nozzles arranged opposite the mounting surface and discharging droplets from the plurality of nozzles toward the mounting surface; a relative movement mechanism that moves the table and the head relatively in a main scanning direction and a sub-scanning direction along the mounting surface; and a control unit that controls the relative movement between the table and the head by the relative movement mechanism and the discharging of the droplets by the head to perform a printing operation on the medium, the method comprising: a pattern printing step of positioning the head at each of a plurality of target positions spaced a predetermined distance apart in the sub-scanning direction from a reference position on the mounting surface, and discharging the droplets while moving the head relatively in the main scanning direction, thereby printing a plurality of adjustment patterns lined up in the sub-scanning direction on the medium; and a deviation amount detection step of detecting a deviation amount in the sub-scanning direction for each of the plurality of target positions based on the positional relationship between adjacent adjustment patterns in the sub-scanning direction. a correction amount calculation step of calculating a correction amount of the ejection position in the sub-scanning direction for each of the plurality of target positions based on the deviation amount.

2. The ejection position correction method according to claim 1, wherein the table has a plurality of top plate members connected in the sub-scanning direction, and the plurality of target positions are arranged so as to straddle the connecting portions of the top plate members in the sub-scanning direction.

3. The ejection position correction method according to claim 1, wherein the adjustment pattern includes an adjustment portion located upstream in the sub-scanning direction and a reference portion located downstream in the sub-scanning direction at the specified distance from the adjustment portion.

4. The ejection position correction method according to claim 3, wherein the adjustment portion and the reference portion are straight lines parallel to the main scanning direction.

5. The ejection position correction method according to claim 4, wherein the adjustment portion and the reference portion have different lengths in the main scanning direction.

6. A printing device comprising: a table having a media placement surface; a head having a plurality of nozzles arranged opposite to the placement surface and ejecting droplets from the plurality of nozzles toward the placement surface; a relative movement mechanism for relatively moving the table and the head in a main scanning direction and a sub-scanning direction along the placement surface; and a control unit for controlling the relative movement between the table and the head by the relative movement mechanism and the ejection of droplets by the head to perform a printing operation on the media, wherein the control unit comprises: a storage unit for storing an amount of deviation in the sub-scanning direction of an ejection position at which the head ejects the droplets relative to the placement surface; and a processing unit for calculating an amount of correction of the ejection position in the sub-scanning direction based on the amount of deviation, and correcting the ejection position based on the correction amount to perform the printing operation, wherein the amount of deviation is a printing device in which the head is positioned at each of a plurality of target positions spaced a predetermined distance apart in the sub-scanning direction from a reference position on the mounting surface, and the head is moved relatively in the main scanning direction while ejecting the droplets to print a plurality of adjustment patterns arranged in the sub-scanning direction on the medium, and the positional relationship between adjacent adjustment patterns is detected based on the positional relationship between the adjustment patterns.

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