Printing device

Abstract

To provide a printing device that is configured so that impact position deviation of a droplet caused by positional shift of one discharge head with respect to the other discharge head can be prevented at low cost.SOLUTION: A printing device comprises a plurality of individual photographing devices provided for each combination of one discharge head with the other discharge head which are adjacently arranged in a crossing direction. Some nozzles of a plurality of nozzles in the one discharge head and some nozzles of the plurality of nozzles in the other discharge head arranged adjacent to the one discharge head in a conveying direction are arranged to overlap with each other when viewed along the conveying direction in a predetermined overlapping area. The individual photographing device photographs a partial printing area that is an area to which liquid droplets are discharged from the some nozzles in the overlapping area of the one discharge head and from the some nozzles in the overlapping area of the other discharge head, of all printing areas in a medium to be printed after liquid droplets are discharged from the nozzles in the plurality of discharge heads.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to printing devices, such as inkjet printers. [Background technology]

[0002] Conventionally, it is known to read a head alignment adjustment test chart printed on paper with a reading sensor, and determine the amount of deviation in the sub-scanning direction of a unit recording head of a recording head array based on the reading results (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-268452 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in order to accurately determine the amount of misalignment of the ejection head, a high resolution is required for the reading sensor. However, if such a high resolution reading sensor is to be arranged over the entire printing paper, the size (area) of the reading sensor becomes large, which poses a problem that it is difficult to avoid an increase in costs.

[0005] Therefore, an object of the present disclosure is to provide a printing device that can suppress, at low cost, deviations in the landing positions of droplets caused by deviations in the position of one ejection head relative to another ejection head. [Means for solving the problem]

[0006] The printing device disclosed herein comprises a plurality of ejection heads each having a nozzle row composed of a plurality of nozzles that eject droplets onto a print medium, a transport device that transports the print medium in a transport direction, a position adjustment device that adjusts the position of each of the ejection heads in a cross direction that intersects the transport direction, and a plurality of individual imaging devices provided for each combination of one of the ejection heads and another of the ejection heads that are adjacent to the one of the ejection heads in the cross direction, wherein some of the plurality of nozzles in one of the ejection heads and some of the plurality of nozzles in another of the ejection heads adjacent to the one of the ejection heads in the transport direction are arranged so as to overlap when viewed along the transport direction in a predetermined overlapping region, and the individual imaging devices image a partial printing region, which is a region where droplets are ejected from some of the nozzles in the overlapping region of the one of the ejection heads and some of the nozzles in the overlapping region of the other of the ejection heads, out of the entire printing region of the print medium after the droplets have been ejected from the nozzles in the plurality of ejection heads.

[0007] According to the present disclosure, a test pattern can be formed by ejecting droplets onto a print medium using an ejection head. Then, the amount of misalignment between one ejection head and another ejection head in the intersecting direction can be calculated based on the imaging results of a partial print area in the test pattern. Furthermore, the relative positions of the one ejection head and another ejection head in the intersecting direction can be adjusted using a position adjustment device based on the calculated amount of misalignment. This effectively suppresses deviations in the landing positions of droplets due to misalignment of another ejection head relative to the first ejection head. Additionally, in the present disclosure, the target imaged by each individual imaging device is a partial print area, rather than the entire print area, on the print medium. This allows the imaging elements of the individual imaging devices to be smaller than when the entire print area is imaged simultaneously, thereby achieving lower costs. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a printing device that can suppress, at low cost, deviations in the landing positions of droplets caused by deviations in the position of one ejection head relative to another ejection head. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram illustrating a printing apparatus according to an embodiment. [Figure 2] FIG. 2 is a block diagram illustrating example components of the printing device of FIG. 1. [Figure 3] FIG. 2 is a diagram showing a nozzle row in the ejection head. [Figure 4] 2 is a diagram showing the configuration of the head bar in FIG. 1 and a full printing area and a partial printing area on a printing medium. FIG. [Figure 5] 5 is a bottom view showing nozzles in an overlapping region of ejection heads in the head bar of FIG. 4. FIG. [Figure 6] 3 is a schematic diagram showing the positional relationship between a first ultraviolet irradiation device, an individual image capturing device, and an entire area image capturing device. FIG. [Figure 7] FIG. 7A is a schematic plan view showing the positional relationship between two ultraviolet irradiation devices as the first ultraviolet irradiation device, and FIG. 7B is a schematic side view corresponding to FIG. 7A. [Figure 8] FIG. 2 is a schematic plan view showing a plurality of individual ultraviolet irradiation devices. [Figure 9] 10 is a schematic plan view showing a pair of cooling units provided to sandwich an individual imaging device from both sides in the intersecting direction. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] A printing device according to an embodiment of the present disclosure will be described below with reference to the drawings. The printing device described below is merely one embodiment of the present disclosure. Therefore, the present disclosure is not limited to the following embodiment, and additions, deletions, and modifications are possible within the scope of the present disclosure.

[0011] (First embodiment) FIG. 1 is a schematic diagram showing a printing device 100 according to one embodiment. An example of the printing device 100 according to this embodiment is a line head type. In FIG. 1, directions that are perpendicular to each other are referred to as a first direction Df and a second direction Ds. In this embodiment, the first direction Df corresponds to the transport direction of the print medium W, and the second direction Ds corresponds to the intersecting direction that is perpendicular to the transport direction. Hereinafter, Df will be referred to as the transport direction, and Ds will be referred to as the intersecting direction.

[0012] As shown in FIG. 1, the printing apparatus 100 according to this embodiment includes a housing 1, a head bar group 70, a pair of transport rollers 60, a platen 61, multiple storage tanks 62, multiple tubes 63, a transport path CP for transporting the print medium W, a first ultraviolet irradiation device 40 for pre-curing (see FIGS. 2 and 6 below), and a second ultraviolet irradiation device 41 for full curing (see FIGS. 2 and 6). The head bar group 70, the pair of transport rollers 60, the platen 61, the multiple storage tanks 62, the multiple tubes 63, the first ultraviolet irradiation device 40, and the second ultraviolet irradiation device 41 are provided within the housing 1. A portion of the transport path CP is provided within the housing 1, and the remainder is exposed from within the housing 1 to the outside. However, the components other than the first ultraviolet irradiation device 40 and the second ultraviolet irradiation device 41 can be installed inside or outside the housing 1 as appropriate. In this embodiment, the transport roller 60 and the transport motor 29 (see FIG. 2 below) correspond to a transport device, and the first ultraviolet irradiation device 40 corresponds to an ultraviolet irradiation device.

[0013] The head bar group 70 has a plurality of head bars 71, for example five head bars 71. The head bars 71 are provided corresponding to the ink colors. The head bars 71 are arranged side by side at approximately equal intervals in the transport direction Df. The head bar 71 is a base extending in the intersecting direction Ds, and supports a plurality of ejection heads 10 (FIGS. 2 and 3), which will be described later.

[0014] The platen 61 supports from below the print medium W. For example, the platen 61 has a predetermined thickness and is made of a rectangular plate material with the transport direction Df as its longitudinal direction.

[0015] The pair of transport rollers 60 extend in the cross direction Ds. The dimension of the transport roller 60 in the cross direction Ds is larger than the dimension of the print medium W in the cross direction Ds. One of the pair of transport rollers 60 is connected to the transport motor 29 (FIG. 2) and is arranged on one side (e.g., the front) of the platen 61 in the transport direction Df. The other of the pair of transport rollers 60 is arranged on the other side (e.g., the rear) of the platen 61 in the transport direction Df. When the transport motor 29 is driven, the transport roller 60 rotates, thereby transporting the print medium W on the platen 61 in the transport direction Df. In this embodiment, the print medium W is transported from the front to the rear.

[0016] Ink is stored in the storage tanks 62. A storage tank 62 is provided for each type of ink. For example, five storage tanks 62 are provided, each storing black, yellow, cyan, magenta, and white ink. A color image is printed by ejecting ink droplets of the four colors of black, yellow, cyan, and magenta onto the print medium W. A base is formed by ejecting white ink droplets onto the print medium W.

[0017] The tube 63 is provided corresponding to the storage tank 62. The tube 63 connects the storage tank 62 to the plurality of ejection heads 10 provided on the head bar 71.

[0018] 1, an individual image capturing device 45 (FIGS. 2 and 4) and a first ultraviolet irradiation device 40 (FIG. 2) are provided in an area Ra downstream in the conveying direction Df from a head bar 71 located at the most downstream side in the conveying direction Df. The second ultraviolet irradiation device 41 is provided downstream of the first ultraviolet irradiation device 40 on the conveying path CP. The individual image capturing device 45 will be described in detail later.

[0019] FIG. 2 is a block diagram showing exemplary components of the printing device 100 of FIG. 1. As shown in FIG. 2, the printing device 100 includes an operation key 4, a display unit 5, a controller unit 19, a reading device 26, a transport motor 29, a motor driver IC 30, a head driver IC 31, irradiation device driver ICs 32 and 33, position adjustment driver ICs 34 and 35, and imaging device driver ICs 36 and 37. The printing device 100 also includes a first ultraviolet irradiation device 40, a second ultraviolet irradiation device 41, multiple position adjustment devices 43, multiple head bar position adjustment devices 44, multiple individual imaging devices 45, and an entire area imaging device 46. The position adjustment device 43 is provided corresponding to the ejection head 10, and the head bar position adjustment device 44 is provided corresponding to the head bar 71.

[0020] The operation keys 4 accept operation inputs from the user. The display unit 5 is configured, for example, as a touch panel, and displays predetermined information. Part of the display unit 5 also functions as an operation key. The controller unit 19 realizes the printing function based on inputs from the operation keys 4 or external inputs via a communication interface (not shown), and also controls the display of the display unit 5.

[0021] The controller unit 19 has a control device 20 configured by a CPU, storage units (ROM 21, RAM 22, EEPROM 23, HDD 24), and an ASIC 25. The control device 20 is connected to the storage units and controls the driver ICs 30 to 37, the display unit 5, and the reading device 26.

[0022] The control device 20 performs various functions by executing predetermined processing programs stored in the ROM 21. The control device 20 may be implemented as a single processor in the controller unit 19, or may be implemented as multiple processors cooperating with each other. The processing programs are read by the reading device 26 from a computer-readable recording medium KB such as a magneto-optical disk or a USB flash memory, and stored in the ROM 21. The RAM 22 stores image data received from the outside and calculation results of the control device 20. The EEPROM 23 stores various initial setting information input by the user. The HDD 24 stores various information.

[0023] Each of the driver ICs 30 to 37 is connected to the ASIC 25. When the control device 20 receives a print job from a user, it outputs a print command to the ASIC 25 based on a processing program. The ASIC 25 controls each of the driver ICs 30 to 37 based on the print command. The control device 20 moves the platen 61 in the transport direction Df by controlling the transport motor 29 with the motor driver IC 30. As a result, the print medium W supported by the platen 61 is transported in the transport direction Df.

[0024] The control device 20 converts image data acquired from an external device or the like into ejection data for ejecting ink droplets onto the print medium W. The control device 20 causes the head driver IC 31 to eject ink droplets from the ejection head 10 based on the converted ejection data. The control device 20 also causes the irradiation device driver IC 32 to irradiate ultraviolet light from the light-emitting diode chip provided in the first ultraviolet irradiation device 40. The ink droplets that have landed on the print medium W are temporarily cured by the ultraviolet light from the first ultraviolet irradiation device 40. The control device 20 also causes the irradiation device driver IC 33 to irradiate ultraviolet light from the light-emitting diode chip provided in the second ultraviolet irradiation device 41. The ink droplets that have landed on the print medium W are temporarily cured by the ultraviolet light from the first ultraviolet irradiation device 40 as described above, and then are finally cured by the ultraviolet light from the second ultraviolet irradiation device 41.

[0025] The control device 20 drives the position adjustment device 43 using the position adjustment driver IC 34 to move the discharge head 10 in the transverse direction Ds. A head bar position adjustment device 44 is provided for each head bar 71 to adjust the position of the corresponding head bar 71. The control device 20 drives the head bar position adjustment device 44 using the position adjustment driver IC 35 to move the head bar 71 in the transverse direction Ds. This allows the position of the head bar 71 in the transverse direction Ds to be adjusted. The position adjustment device 43 includes an electric motor (not shown) and a mechanism (not shown) such as a ball screw or rack and pinion that connects the electric motor to the discharge head 10. The head bar position adjustment device 44 also includes an electric motor (not shown) and a mechanism (not shown) such as a ball screw or rack and pinion that connects the electric motor to the head bar 71.

[0026] The control device 20 controls the individual imaging device 45 using the imaging device driver IC 36. As a result, the individual imaging device 45 captures an image of a partial printing area RP2 (FIG. 4) on the print medium W, which will be described later. The control device 20 also controls the entire area imaging device 46 using the imaging device driver IC 37. As a result, the entire area imaging device 46 captures an image of the entire printing area RP1 (FIG. 4) on the print medium W, which will be described later. The image of the partial printing area RP2 captured by the individual imaging device 45 and the image of the entire printing area RP1 captured by the entire area imaging device 46 are stored in the memory unit. The control device 20 reads out the image of the partial printing area RP2 and the image of the entire printing area RP1 from the memory unit.

[0027] The printing device 100 may be provided with a rotation device that rotates the head bar 71 around an axis perpendicular to the platen 61, and a rotation device that rotates the ejection head 10 around an axis perpendicular to the platen 61. This allows the angle of the head bar 71 and the angle of the ejection head 10 to be adjusted.

[0028] FIG. 3 is a diagram showing a nozzle row NL in the ejection head 10. As shown in FIG. 3, the ejection head 10 is provided with a plurality of nozzles 121. The nozzles 121 are arranged regularly in the ejection head 10. Specifically, the nozzles 121 are arranged at approximately equal intervals in both the transport direction Df and the intersecting direction Ds. A plurality of nozzles Nz are arranged side by side in the nozzle row direction Dn to form the nozzle row NL. In other words, the nozzle row NL extends in the nozzle row direction Dn. The nozzle row direction Dn is a direction parallel to the transport direction Df. A plurality of nozzle rows NL are provided, and the nozzle rows NL are arranged at approximately equal intervals in the intersecting direction Ds.

[0029] Fig. 4 is a diagram showing the configuration of the head bar 71 in Fig. 1 and the entire print area RP1 and partial print area RP2 on the print medium W. Fig. 5 is a bottom view showing the nozzles Nza in the overlap area RL of the ejection heads 10 in the head bar 71 in Fig. 4.

[0030] 4, the head bar 71 is provided with five ejection heads 10 as an example of the plurality of ejection heads 10. However, the number of ejection heads 10 provided on the head bar 71 is not limited to five and can be set as appropriate. In the printing device 100 of this embodiment, an inkjet head that ejects, for example, ultraviolet-curable ink droplets as droplets is used as the ejection head 10.

[0031] In the head bar 71, a plurality of ejection heads 10 are arranged in the intersecting direction Ds and are aligned in the transport direction Df. Specifically, three of the five ejection heads 10 are arranged upstream (front) in the transport direction Df, and the remaining two ejection heads 10 are arranged downstream (rear) in the transport direction Df. The upstream ejection heads 10 include ejection heads 111, 113, and 115. The downstream ejection heads 10 include ejection heads 112 and 114. The upstream ejection heads 10 are arranged at approximately equal intervals. The downstream ejection heads 10 are arranged at approximately equal intervals and are shifted a predetermined distance in the intersecting direction Ds from the upstream ejection heads 10. That is, the multiple ejection heads 10 in the head bar 71 are arranged in a staggered pattern in the intersecting direction Ds.

[0032] The following describes the overlapping region RL of the ejection head 10. The following describes the overlapping region RL of the ejection head 112 as an example of one ejection head 10 and the ejection head 113 as an example of another ejection head 10 as an example.

[0033] 5, some nozzles Nza of the multiple nozzles Nz in the discharge head 112 and some nozzles Nza of the multiple nozzles Nz in the discharge head 113 adjacent to the discharge head 112 as viewed along the intersecting direction Ds are arranged so as to overlap in a predetermined overlapping region RL as viewed along the transport direction Df. That is, one nozzle Nza in the discharge head 113 is arranged upstream (forward) in the transport direction Df with respect to one nozzle Nza in the discharge head 112. In this case, the position of one nozzle Nza in the discharge head 113 (i.e., the position of the region occupied by one nozzle Nza) may partially or completely overlap in the transport direction Df with the position of one nozzle Nza in the discharge head 112 (i.e., the position of the region occupied by one nozzle Nza).

[0034] Some of the nozzles Nza in the overlapping region RL of the ejection head 112 are four or more. In Fig. 5, the number of nozzles Nza in the ejection head 112 is four. Also, some of the nozzles Nza in the overlapping region RL of the ejection head 113 are four or more. In Fig. 5, the number of nozzles Nza in the ejection head 113 is four. Note that similar nozzles Nza are provided in the overlapping region RL of ejection heads 10 other than the ejection heads 112 and 113 given as examples.

[0035] In FIG. 4, ink droplets are ejected onto the entire printing region RP1 on the print-receiving medium W by the nozzles Nz of the multiple ejection heads 10 in all or some of the multiple head bars 71. Furthermore, ink droplets are ejected onto the partial printing region RP2 of the entire printing region RP1 on the print-receiving medium W by the nozzles Nza of the overlapping region RL in all or some of the multiple head bars 71 (i.e., the nozzles Nza of the overlapping region RL of two ejection heads 10 adjacent in the transport direction Df). As a result, the image printed on the partial printing region RP2 on the print-receiving medium W is, for example, strip-shaped. Note that when forming a test pattern (described later), ink droplets are ejected onto at least the partial printing region RP2. That is, this does not exclude the possibility that ink droplets are ejected onto not only the partial printing region RP2 but also the region of the entire printing region RP1 excluding the partial printing region RP2 when forming the test pattern. In this embodiment, when forming the test pattern, ink droplets are ejected onto not only the partial printing region RP2 but also the region of the entire printing region RP1 excluding the partial printing region RP2. As a result, the test pattern is formed in the entire printing area RP1.

[0036] Each of the individual imaging devices 45 is disposed downstream in the transport direction Df of the plurality of ejection heads 10. More specifically, each of the individual imaging devices 45 is disposed downstream in the transport direction Df of each ejection head 10 in the head bar 71 located at the most downstream side in the transport direction Df, as shown in FIG.

[0037] An individual imaging device 45 is provided for each combination of one ejection head 10 and another ejection head 10 adjacent to each other in the intersecting direction Ds. That is, two individual imaging devices 45 are provided for each ejection head 10 in the head bar 71, excluding the ejection heads 10 arranged at one end and the other end in the intersecting direction Ds. In other words, the individual imaging devices 45 are arranged corresponding to the overlapping region RL. More specifically, the individual imaging devices 45 are arranged downstream of the overlapping region RL in the transport direction Df so as to be at the same position as the corresponding overlapping region RL in the intersecting direction Ds. Furthermore, the individual imaging devices 45 are arranged above or below the transported print medium W. However, when the individual imaging devices 45 are arranged below the print medium W, the print medium W is made transparent (preferably colorless and transparent), as described below.

[0038] The individual imaging devices 45 capture an image of a corresponding partial printing area RP2 of the entire printing area RP1 on the printing medium W after ink droplets have been ejected from the nozzles Nz of the multiple ejection heads 10 in each head bar 71. The imaging range of the individual imaging devices 45 in the intersecting direction Ds is equal to or greater than the size of the partial printing area RP2 in the intersecting direction Ds.

[0039] As shown in FIG. 6 in the second embodiment described below, the entire area imaging device 46 is arranged downstream of each individual imaging device 45 in the transport direction Df. The entire area imaging device 46 is provided, for example, outside the housing 1. The entire area imaging device 46 is provided above or below the transported print medium W. The entire area imaging device 46 images the entire print area RP1 on the print medium W. The imaging range of the entire area imaging device 46 in the cross direction Ds is equal to or greater than the size of the entire print area RP1 in the cross direction Ds.

[0040] The following describes the flow of processing by the control device 20. First, the control device 20 uses the position adjustment device 43 to adjust the relative positions in the intersecting direction Ds between one ejection head 10 and another ejection head 10 adjacent to each other in the intersecting direction Ds to predetermined positions.

[0041] In this state, the control device 20 forms a test pattern on the print medium W. In this case, ink droplets are ejected onto the partial print region RP2 of the print medium W by the nozzles Nza in the overlap region RL (i.e., the nozzles Nza in the overlap region RL of the two ejection heads 10 adjacent to each other in the transport direction Df). As a result, for example, a band-shaped test pattern is formed in the partial print region RP2 of the print medium W. Furthermore, ink droplets are also ejected onto an area of ​​the entire print region RP1 on the print medium W excluding the partial print region RP2 by the nozzles Nz other than the nozzles Nza of each ejection head 10. As a result, a predetermined test pattern is formed in an area of ​​the entire print region RP1 excluding the partial print region RP2. Note that test patterns corresponding to all overlap regions RL may be formed, or test patterns corresponding to a portion of all overlap regions RL may be formed.

[0042] Next, the control device 20 causes each individual imaging device 45 to capture an image of the corresponding partial printing area RP2. The control device 20 then reads out the image of the partial printing area RP2 (image of the test pattern) as the imaging result stored in the storage unit. The control device 20 calculates a first amount of deviation in the intersecting direction Ds between one ejection head 10 and another ejection head 10 based on the read-out image of the partial printing area RP2. In this case, for example, the control device 20 can calculate the first amount of deviation based on the dimension in the intersecting direction Ds of the test pattern formed by the nozzles Nza in the overlapping area RL of two ejection heads 10 adjacent to each other in the transport direction Df. Note that the process of calculating the first amount of deviation is performed, for example, before the print medium W transported in the transport direction Df reaches the imaging range of the entire area imaging device 46.

[0043] Next, the control device 20 causes the entire area imaging device 46 to capture an image of the entire print area RP1 of the print medium W. Then, the control device 20 reads out the image of the entire print area RP1 (image of the test pattern) stored in the memory unit as the captured image. Based on the read image of the entire print area RP1, the control device 20 calculates a second amount of deviation in the intersecting direction Ds between one head bar 71 and another head bar 71 adjacent to the one head bar 71 in the transport direction Df. In this case, for example, the control device 20 can calculate the second amount of deviation based on the dimension of the test pattern in the entire print area RP1 in the intersecting direction Ds.

[0044] Next, the control device 20 adjusts the relative position of the one ejection head 10 and the other ejection heads 10 in the intersecting direction Ds using the position adjustment device 43 based on the calculated first deviation amount. Then, the control device 20 adjusts the relative position of the one head bar 71 and the other head bar 71 in the intersecting direction Ds using the head bar position adjustment device 44 based on the calculated second deviation amount. Note that in an embodiment where a rotation device that rotates the head bar 71 and a rotation device that rotates the ejection heads 10 are provided, the angular deviation of the head bar 71 and the angular deviation of the ejection heads 10 may be adjusted based on the imaging results of the test pattern.

[0045] The relative position of one ejection head 10 and another ejection head 10 in the intersecting direction Ds is the position of the other ejection head 10 relative to the one ejection head 10 in the intersecting direction Ds, or the position of the one ejection head 10 relative to the other ejection head 10 in the intersecting direction Ds. Also, the relative position of one head bar 71 and another head bar 71 in the intersecting direction Ds is the position of the other head bar 71 relative to the one head bar 71 in the intersecting direction Ds, or the position of the one head bar 71 relative to the other head bar 71 in the intersecting direction Ds.

[0046] In this case, the control device 20 may move only one ejection head 10 in the intersecting direction Ds relative to the other ejection heads 10, or may move only the other ejection heads 10 in the intersecting direction Ds relative to the one ejection head 10. Alternatively, the control device 20 may move one ejection head 10 in the intersecting direction Ds relative to the other ejection heads 10, and also move the other ejection heads 10 in the intersecting direction Ds relative to the one ejection head 10. Furthermore, the control device 20 may move only one head bar 71 in the intersecting direction Ds relative to the other head bar 71, or may move only the other head bar 71 in the intersecting direction Ds relative to the one head bar 71. Alternatively, the control device 20 may move one head bar 71 in the intersecting direction Ds relative to the other head bar 71, and also move the other head bar 71 in the intersecting direction Ds relative to the one head bar 71.

[0047] Furthermore, the control device 20 may execute a process to shift the ejection timing of one nozzle Nz in each ejection head 10 relative to the ejection timing of another nozzle Nz aligned with the nozzle Nz in the transport direction Df. In this case, the deviation in the landing position of ink droplets in the transport direction Df can be corrected.

[0048] After the above process is completed, the control device 20 may execute the test pattern formation process again.

[0049] As described above, the printing device 100 of this embodiment can form a test pattern by ejecting ink droplets onto the print medium W using the ejection head 10. Then, based on the imaging results of the partial print region RP2 in the test pattern, the first amount of deviation between one ejection head 10 and the other ejection heads 10 in the intersecting direction Ds can be calculated. Furthermore, based on the calculated first amount of deviation, the relative positions of the one ejection head 10 and the other ejection heads 10 in the intersecting direction Ds can be adjusted by the position adjustment device 43. This sufficiently reduces deviations in the landing positions of ink droplets due to misalignment of the other ejection heads 10 relative to the first ejection head 10. In addition, the object imaged by each individual imaging device 45 is limited to the partial print region Rp2 rather than the entire print region RP1 on the print medium W. This allows the imaging elements of the individual imaging devices 45 to be smaller than when the entire print region RP1 is imaged at once, thereby achieving lower costs.

[0050] Furthermore, in this embodiment, each individual imaging device 45 is disposed downstream in the transport direction Df of each ejection head 10 in the head bar 71 located at the most downstream side in the transport direction Df. This allows the print medium W after printing to be sent downstream and imaged by each individual imaging device 45. This ensures a smooth process from the end of printing to the image capture.

[0051] Furthermore, in this embodiment, an entire area imaging device 46 is provided downstream of each individual imaging device 45 in the transport direction Df. This makes it possible to calculate a second deviation amount in the intersecting direction Ds between one head bar 71 and another head bar 71 adjacent to the one head bar 71 in the transport direction Df using the imaging result by the entire area imaging device 46. Note that in this embodiment, the inter-color position may be adjusted by moving the individual ejection heads 10 rather than moving the head bar 71 using the entire area imaging device 46.

[0052] Furthermore, in this embodiment, the relative positional deviation between one ejection head 10 and another ejection head 10 in the intersecting direction Ds can be eliminated based on the calculated first deviation amount, and the relative positional deviation between one head bar 71 and another head bar 71 can be eliminated based on the calculated second deviation amount. This can sufficiently suppress deviations in the landing positions of ink droplets caused by positional deviations of the ejection heads 10 and the head bars 71. Also, in this embodiment, the control device 20 executes a process to shift the ejection timing of one nozzle Nz in each ejection head 10 relative to the ejection timing of another nozzle Nz aligned with the one nozzle Nz in the transport direction Df. By shifting the ejection timing in this manner, deviations in the landing positions of ink droplets in the transport direction Df are also corrected.

[0053] (Second embodiment) A second embodiment of the present disclosure will now be described. Fig. 6 is a schematic diagram showing the positional relationship between a first ultraviolet irradiation device 40, an individual image capturing device 45, and an entire area image capturing device 46.

[0054] As described above, the first ultraviolet irradiation device 40 irradiates ultraviolet rays to temporarily cure the ink droplets ejected onto the print medium W. Thereafter, the print medium W is transported along the transport path CP, and then the second ultraviolet irradiation device 41 irradiates ultraviolet rays to completely cure the ink droplets ejected onto the print medium W.

[0055] In the pre-curing process, the ink droplets are not completely solidified, but only the surface can be cured, for example. Furthermore, in the main curing process, the intensity (energy) of the ultraviolet light is increased compared to the pre-curing process to harden the entire ink droplets, improving durability such as water resistance, abrasion resistance, and light resistance. In this way, by hardening the ink droplets in two stages, the pre-curing process and the main curing process, the ink droplets are hardened in a moderately wet and spread state, and the ink droplets have improved adhesion to the print medium W, which can improve image quality. In this embodiment, the print medium W is transparent. Preferably, the print medium W is colorless and transparent.

[0056] As shown in FIG. 6, the first ultraviolet irradiation device 40 is provided in an area Ra downstream in the conveyance direction Df of the head bar 71 located at the most downstream side in the conveyance direction Df. The first ultraviolet irradiation device 40 is provided on one side in the direction intersecting the conveyance path CP. The first ultraviolet irradiation device 40 extends in the intersecting direction Ds. The size (dimension) of the irradiation range of ultraviolet light irradiated by the first ultraviolet irradiation device 40 in the intersecting direction Ds is equal to or greater than the dimension of the entire print area RP1 of the print medium W in the intersecting direction Ds. This allows ink droplets ejected into the entire print area RP1 of the print medium W to be suitably temporarily cured by the first ultraviolet irradiation device 40. In this embodiment, the entire area imaging device 46 is provided below the print medium W. The individual imaging device 45 is provided on the other side in the direction intersecting the conveyance path CP so as to face the first ultraviolet irradiation device 40.

[0057] The individual image capturing device 45 has a film 45b that passes ultraviolet light from the first ultraviolet irradiation device 40 but blocks visible light. The individual image capturing device 45 also has a light entrance section 45c on which the film 45b is provided and a shutter section 45a that can be opened and closed to prevent foreign matter from adhering to the light entrance section 45c. The shutter section 45a opens and closes in response to instructions from the control device 20 based on the exposure time at the light entrance section 45c. In this configuration, the individual image capturing device 45 captures images at the timing when ultraviolet light is emitted by the first ultraviolet irradiation device 40. In this case, the control device 20 may send an instruction to the first ultraviolet irradiation device 40 to emit light and an instruction to the individual image capturing device 45 at the same time.

[0058] As described above, according to this embodiment, the individual image capturing device 45 captures images at the timing when ultraviolet light is emitted by the first ultraviolet irradiation device 40. This eliminates the need to separately provide a flash means required when capturing images with the individual image capturing device 45, thereby simplifying the configuration.

[0059] In this embodiment, the individual image capturing device 45 is provided on the other side in the direction intersecting the transport path CP so as to face the first ultraviolet irradiation device 40. This makes it possible for the individual image capturing device 45 to capture an image from the side opposite to the printing surface of the transparent print medium W.

[0060] Furthermore, in this embodiment, the individual image capturing device 45 has a film 45b that passes ultraviolet light from the first ultraviolet irradiation device 40 but blocks visible light. This allows visible light to be blocked by the film 45b, thereby increasing the ultraviolet light receiving sensitivity of the individual image capturing device 45.

[0061] In this embodiment, the individual image capturing device 45 has a shutter 45a that can be opened and closed to prevent foreign matter from adhering to the light entrance portion 45c. As a result, closing the shutter 45a suppresses the adhesion of foreign matter such as ink droplet mist to the light entrance portion 45c. This further increases the ultraviolet light receiving sensitivity of the individual image capturing device 45.

[0062] Furthermore, in this embodiment, the shutter section 45a opens and closes based on the exposure time at the light entrance section 45c in response to an instruction from the control device 20. In this way, the exposure time can be adjusted by the shutter section 45a.

[0063] (Third embodiment) A third embodiment of the present disclosure will be described. Fig. 7A is a schematic plan view showing the positional relationship of two ultraviolet irradiation devices 141 and 142 as the first ultraviolet irradiation device 40, and Fig. 7B is a schematic side view corresponding to Fig. 7A.

[0064] As shown in FIGS. 7A and 7B, the first ultraviolet irradiation device 40 includes two ultraviolet irradiation devices 141 and 142. The ultraviolet irradiation device 142 is disposed adjacent to the ultraviolet irradiation device 141 in the transport direction Df and is disposed downstream of the ultraviolet irradiation device 141 in the transport direction Df. The ultraviolet irradiation devices 141 and 142 extend in the intersecting direction Ds. The size (dimension) of the irradiation range of ultraviolet light emitted by the ultraviolet irradiation devices 141 and 142 in the intersecting direction Ds is equal to or greater than the dimension of the entire printing region RP1 of the printing medium W in the intersecting direction Ds. Note that, although not shown, in this embodiment, the entire region imaging device 46 may be provided above the printing medium W. In this embodiment, the ultraviolet irradiation device 141 corresponds to the first ultraviolet irradiation device, and the ultraviolet irradiation device 142 corresponds to the second ultraviolet irradiation device.

[0065] The individual image capturing device 45 is disposed on one side in the direction intersecting the transport path CP, adjacent to the first ultraviolet irradiation device 40 in the transport direction Df. More specifically, the individual image capturing device 45 is provided above the transported print medium W, and is provided between the ultraviolet irradiation device 141 and the ultraviolet irradiation device 142 in the transport direction Df. In this embodiment, the print medium W may or may not have a transparent color.

[0066] A first optical axis changing device 80 is connected to the ultraviolet irradiation device 141. The first optical axis changing device 80 includes, for example, an electric motor and an actuator that converts power from the electric motor into a rotational movement of the ultraviolet irradiation device 141. The first optical axis changing device 80 changes the optical axis La of the ultraviolet light irradiated by the ultraviolet irradiation device 141. In this case, for example, the first optical axis changing device 80 may rotate the ultraviolet irradiation device 141 about an axis perpendicular to the transport direction Df so as to change the position of the optical axis La in the transport direction Df.

[0067] A second optical axis changing device 81 is connected to the ultraviolet irradiation device 142. The second optical axis changing device 81 includes, for example, an electric motor and an actuator that converts power from the electric motor into a rotational movement of the ultraviolet irradiation device 142. The second optical axis changing device 81 changes the optical axis La of the ultraviolet light irradiated by the ultraviolet irradiation device 142. In this case, for example, the second optical axis changing device 81 may rotate the ultraviolet irradiation device 142 about an axis perpendicular to the transport direction Df so as to change the position of the optical axis La in the transport direction Df.

[0068] In such a configuration, the control device 20 may make the amount of ultraviolet light emitted by the ultraviolet irradiation device 141 different from the amount of ultraviolet light emitted by the ultraviolet irradiation device 142. In this case, the control device 20 may make the amount of ultraviolet light emitted by the ultraviolet irradiation device 141 greater than the amount of ultraviolet light emitted by the ultraviolet irradiation device 142. Alternatively, the control device 20 may make the amount of ultraviolet light emitted by the ultraviolet irradiation device 141 less than the amount of ultraviolet light emitted by the ultraviolet irradiation device 142. However, this does not exclude the case where the amount of ultraviolet light emitted by the ultraviolet irradiation device 141 and the amount of ultraviolet light emitted by the ultraviolet irradiation device 142 are the same.

[0069] FIG. 8 is a schematic plan view showing a plurality of individual ultraviolet irradiation devices 143 as the ultraviolet irradiation device 142. As shown in FIG.

[0070] 7, a plurality of individual ultraviolet irradiation devices 143 may be provided as shown in Fig. 8. An individual ultraviolet irradiation device 143 is provided for each individual imaging device 45. That is, an individual ultraviolet irradiation device 143 is provided corresponding to each individual imaging device 45. An individual ultraviolet irradiation device 143 is disposed downstream of the individual imaging device 45 in the conveying direction Df so as to be at the same position as the corresponding individual imaging device 45 in the cross direction Ds.

[0071] However, instead of providing the individual ultraviolet irradiation devices 143 that are dispersed as the ultraviolet irradiation devices 142, individual ultraviolet irradiation devices similar to the individual ultraviolet irradiation devices 143 may be provided as the ultraviolet irradiation devices 141.

[0072] FIG. 9 is a schematic plan view showing a pair of cooling sections 85 provided to sandwich the individual imaging device 45 from both sides in the cross direction Ds.

[0073] 9, a pair of cooling units 85 are provided in the intersecting direction Ds to sandwich the individual image capturing device 45 from both sides. The cooling units 85 are provided between the ultraviolet irradiation devices 141 and 142 in the transport direction Df. Examples of the cooling units 85 include a heat sink and a pipe through which cooling water circulates.

[0074] As described above, according to this embodiment, the individual image capturing device 45 is provided above the transported print medium W, and is disposed adjacent to the first ultraviolet irradiation device 40 in the transport direction Df on one side of the direction intersecting the transport path CP. This eliminates the need to make the print medium W transparent, thereby broadening the range of applicability of the print medium W.

[0075] In the present embodiment, the individual image capturing device 45 is provided between the ultraviolet irradiation device 141 and the ultraviolet irradiation device 142 in the conveying direction Df. This makes the image capturing result by the individual image capturing device 45 clearer than in an embodiment in which there is only one ultraviolet irradiation device.

[0076] Furthermore, in this embodiment, a plurality of individual ultraviolet irradiation devices 143 are provided as the ultraviolet irradiation device 142 for each individual image capturing device 45. By providing an individual ultraviolet irradiation device 143 for each individual image capturing device 45 in this way, the amount of light required to obtain a flash effect during image capturing can be reduced compared to when one ultraviolet irradiation device is provided for all individual image capturing devices 45. This allows the individual ultraviolet irradiation devices 143 to be made smaller and less expensive.

[0077] Furthermore, in this embodiment, the control device 20 may cause the ultraviolet ray emission amount of the ultraviolet ray irradiation device 141 to differ from the ultraviolet ray emission amount of the ultraviolet ray irradiation device 142. In this case, by making a difference between the emission amount of the ultraviolet ray irradiation device 141 arranged upstream in the transport direction Df and the emission amount of the ultraviolet ray irradiation device 142 arranged downstream, it is possible to perform curing of ink droplets and image capture under optimal conditions. For example, by increasing the emission amount of the ultraviolet ray irradiation device 141, it is possible to capture an image of a test pattern using ink droplets with a high degree of curing. On the other hand, by increasing the emission amount of the ultraviolet ray irradiation device 142, it is possible to image a test pattern using ink droplets with a low degree of curing, and then proceed with curing of the ink droplets.

[0078] In this embodiment, the first optical axis changing device 80 is connected to the ultraviolet irradiation device 141, and the second optical axis changing device 81 is connected to the ultraviolet irradiation device 142. In this configuration, by changing the optical axis La to intensively irradiate the ultraviolet light, the curing of the ink droplets can be accelerated, thereby enabling the imaging of a clearer test pattern. In addition, by changing the optical axis La to intensively irradiate the ultraviolet light, it is also possible to suppress the reflection of light onto the nozzle surface of the ejection head 10. Furthermore, by irradiating the ultraviolet light uniformly, uneven curing of the ink droplets can be suppressed, enabling the imaging of a clearer test pattern that has been uniformly cured.

[0079] Furthermore, in this embodiment, a pair of cooling units 85 are provided in the intersecting direction Ds to sandwich the individual image capturing device 45 from both sides. In this case, it is possible to suppress the heat rise of the individual image capturing device 45 and to cool the ultraviolet irradiation devices 141 and 142. Furthermore, the arrangement of the cooling units 85 allows for effective use of space.

[0080] Although several modified examples have been described above, the following modified examples can also be adopted without departing from the gist of the present disclosure.

[0081] In the above embodiment, the individual image capturing device 45 captures an image at the timing when the first ultraviolet irradiation device 40 emits ultraviolet light, but this is not limited to this. The individual image capturing device 45 may capture an image at the timing when the second ultraviolet irradiation device 41 emits ultraviolet light. This eliminates the need to separately provide a flash means required when capturing an image with the individual image capturing device 45, thereby simplifying the configuration.

[0082] Furthermore, in the above embodiment, multiple head bars 71 are provided, but this is not limited to this, and there may be only one head bar 71. Alternatively, there may be only multiple ejection heads 10 without providing the head bar 71 itself. Furthermore, although ten ejection heads 10 are provided, the number of ejection heads 10 may be any number other than ten.

[0083] Furthermore, in the above embodiment, a color image is printed by ejecting ink droplets of four colors, black, yellow, cyan, and magenta, onto the print medium W, and a base is formed by ejecting white ink droplets onto the print medium W, but this is not limited to this. A configuration for ejecting other inks, such as clear ink, onto the print medium W in addition to the above inks may be added to the printing device 100. [Explanation of symbols]

[0084] 10 Discharge head 20 Control device 33 Transport motor 40 First ultraviolet irradiation device 41 Second ultraviolet irradiation device 43 Position adjustment device 44 Head bar position adjustment device 45 Individual imaging device 45a Shutter section 45b film 45c Light entrance part 46 Whole-area imaging device 60 Conveyor roller 71 Head Bar 80 First optical axis changing device 81 Second optical axis changing device 85 Cooling section 100 Printing device 141,142 Ultraviolet irradiation equipment 143 Individual UV irradiation device CP transport path Df Conveying direction Ds cross direction La optical axis NL nozzle row Nz nozzle RL overlap area RP1 Full print area RP2 partial print area W Printing medium

Claims

1. a plurality of ejection heads each having a nozzle row made up of a plurality of nozzles that eject droplets onto a print medium; a conveying device that conveys the print medium in a conveying direction; a position adjustment device for adjusting the position of each of the ejection heads in a direction intersecting the transport direction; a plurality of individual imaging devices provided for each combination of one of the ejection heads and another of the ejection heads adjacent to each other in the intersecting direction, some of the nozzles in one of the ejection heads and some of the nozzles in another of the ejection heads adjacent to the one of the ejection heads in the transport direction are arranged to overlap in a predetermined overlapping region when viewed along the transport direction, A printing device in which the individual imaging device images a partial printing area, which is an area where droplets are ejected from some of the nozzles in the overlapping area of ​​one ejection head and some of the nozzles in the overlapping area of ​​the other ejection head, out of the entire printing area on the printing medium after the droplets have been ejected from the nozzles of the multiple ejection heads.

2. The printing device according to claim 1 , wherein each of the individual image capturing devices is disposed downstream of the plurality of ejection heads in the transport direction.

3. The printing apparatus according to claim 2 , further comprising an entire area imaging device that is arranged downstream of each of the individual imaging devices in the transport direction and that images the entire print area of ​​the print medium.

4. a control device; a head bar in which the plurality of ejection heads are aligned in the intersecting direction and a plurality of head bars are arranged in the transport direction; and a head bar position adjustment device provided for each of the head bars and configured to adjust the position of the head bar, The control device a process of ejecting the droplets onto the print medium from the nozzles of the plurality of ejection heads to form a test pattern; a process of imaging each of the partial printing areas by each of the individual imaging devices; a process of calculating a first deviation amount between the one ejection head and the other ejection head in the intersecting direction based on the imaging results of each of the individual imaging devices; a process of imaging the entire print area using the entire area imaging device; a process of calculating a second deviation amount between one of the head bars and another of the head bars adjacent to the one of the head bars in the conveying direction based on an imaging result by the whole area imaging device; a process of adjusting the relative position of the one ejection head and the other ejection head in the intersecting direction by the position adjustment device based on the calculated first deviation amount; a process of adjusting the relative position between the one head bar and the other head bar by the head bar position adjustment device based on the calculated second deviation amount; The printing apparatus according to claim 3 , further comprising: a process for shifting the ejection timing of one of the nozzles in each of the ejection heads relative to the ejection timing of another of the nozzles aligned with the one nozzle in the transport direction.

5. the ejection head ejects ultraviolet-curable ink droplets as the droplets, The printing apparatus further includes a transport path for transporting the print medium, and an ultraviolet irradiation device provided on one side of the transport path in a direction intersecting the transport path and for curing the ink droplets, The printing apparatus according to claim 1 , wherein the individual image capturing device is provided on the other side of the direction intersecting the transport path so as to face the ultraviolet irradiation device, and captures images at timings when the ultraviolet irradiation device emits ultraviolet light.

6. The printing device according to claim 5 , wherein the print medium has a transparent color.

7. The printing device of claim 5 , wherein the individual imaging devices have a film that passes the ultraviolet light and blocks visible light.

8. 8. The printing apparatus according to claim 7, wherein said individual image capturing device has a light entrance section provided with said film and an openable / closable shutter section for preventing foreign matter from adhering to said light entrance section.

9. The printing device according to claim 8 , wherein the shutter section opens and closes based on an exposure time of the light entrance section.

10. the ejection head ejects ultraviolet-curable ink droplets as the droplets, The printing apparatus further includes a transport path for transporting the print medium, and an ultraviolet irradiation device provided on one side of the transport path in a direction intersecting the transport path and for curing the ink droplets, The printing apparatus according to claim 1 , wherein the individual image capturing device is disposed adjacent to the ultraviolet irradiation device on one side in a direction intersecting the transport path.

11. the ultraviolet irradiation device includes a first ultraviolet irradiation device and a second ultraviolet irradiation device disposed downstream of the first ultraviolet irradiation device in the transport direction, The printing apparatus according to claim 10 , wherein the individual image capturing device is disposed between the first ultraviolet irradiation device and the second ultraviolet irradiation device in the transport direction.

12. The printing device according to claim 11 , wherein one of the first ultraviolet irradiation device and the second ultraviolet irradiation device includes a plurality of individual ultraviolet irradiation devices corresponding to the plurality of individual image capturing devices, respectively.

13. The printing device according to claim 11 , wherein an amount of ultraviolet light emitted by the first ultraviolet light irradiation device is different from an amount of ultraviolet light emitted by the second ultraviolet light irradiation device.

14. a first optical axis changing device that changes the optical axis of the ultraviolet light irradiated by the first ultraviolet light irradiation device; The printing apparatus according to claim 11 , further comprising: a second optical axis changing device that changes the optical axis of the ultraviolet light irradiated by the second ultraviolet irradiation device.

15. The printing device according to claim 10 , further comprising a pair of cooling units provided to sandwich the individual image capturing device from both sides in the intersecting direction.

Images