Printing system and printing method

Abstract

A printing system and a printing method are provided. A printing system according to one embodiment includes a print head that can eject a first ink of a first color and having a curing property and a second ink of a second color and having a curing property onto a medium, a control unit that controls ejection of the inks, a curing unit, and a detection unit. The curing unit cures the first and second inks that are ejected onto the medium at different timings. The control unit controls the print head so as to form a first pattern by the first ink. The control unit controls the print head so as to eject the second ink to a second region including a first region in which a result of curing the first ink of the first pattern is formed, with respect to the medium on which the result is formed. The curing unit cures the second ink of the second region after a predetermined time elapses from the ejection of the second ink. The detection unit detects a printing result by the first and second inks that is cured by the curing unit.

Description

Technical Field

[0001] This invention relates to a printing system and a printing method. Background Technology

[0002] Patent Document 1 describes a technique that aims to improve the graininess of bright areas at low cost and without degrading image quality by spraying colored ink onto the concave portion formed by the transparent ink after the transparent ink has been sprayed and cured.

[0003] However, when the test pattern is printed using the technology described in Patent Document 1, various patterns can form on the shape of the colored ink due to various main causes such as droplet flight bending and poor ejection. Therefore, it is difficult to distinguish the quality of the printing result and the main causes. Furthermore, this problem becomes even more pronounced when the test pattern is an adjustment pattern used to adjust the spray position of colors with poor visual confirmation.

[0004] Therefore, there is a desire to develop a technique for adjusting patterns that can accurately detect and adjust the position of ink sprayed onto a medium, even when the ink is a color that is difficult to visually identify.

[0005] Patent document 1: Japanese Patent Application Publication No. 2017-124548. Summary of the Invention

[0006] One aspect of the printing system disclosed herein includes: a printhead capable of ejecting a first ink and a second ink onto a medium, the first ink being a first-colored and curable liquid, and the second ink being a second-colored and curable liquid; a control unit controlling the ejection of the first ink and the second ink by the printhead; a curing unit curing the first ink and the second ink ejected onto the medium at different timings; and a detection unit detecting the printing result achieved by the first ink and the second ink after curing by the curing unit. The control unit performs the following processing: controlling the printhead to form a first pattern with the first ink, and controlling the printhead to eject the second ink onto a second region including a first region where the first pattern is formed, for the medium on which the first ink that formed the first pattern has been cured (i.e., a first product). The curing unit cures the second ink in the second region after a predetermined time has elapsed since the second ink was ejected.

[0007] One aspect of this disclosure relates to a printing method for printing a first pattern using a printing system equipped with a printhead capable of ejecting a first ink and a second ink onto a medium. The first ink is a first-colored and curable liquid, and the second ink is a second-colored and curable liquid. In this printing method, the printhead is controlled to form the first pattern using the first ink, causing the first ink of the formed first pattern to cure. For the medium on which a first product, a solidified product of the first ink of the first pattern, is formed, the printhead is controlled to eject the second ink onto a second region including a first region on which the first product is formed. The second ink in the second region cures after a predetermined time elapsed from the ejection of the second ink. The cured printing result achieved by the first ink and the second ink is then inspected. Attached Figure Description

[0008] Figure 1 This is a schematic diagram illustrating a structural example of a printing system according to an embodiment.

[0009] Figure 2 To be Figure 1 A schematic diagram illustrating an example of a recording head in a printing system, depicted in a way that unfolds on a plane.

[0010] Figure 3 To indicate in Figure 1 A schematic diagram illustrating an example of an adjustment pattern being printed in a printing system.

[0011] Figure 4 To indicate Figure 3 A schematic diagram of the X-direction section at the position indicated by the single-dotted line in the Y-direction pattern of the adjustment pattern shown.

[0012] Figure 5 To indicate formation Figure 3 The diagram shows the process of adjusting the pattern.

[0013] Figure 6 To indicate the use of the inspection department of the printing system Figure 3 and Figure 4 The diagram shows the detection of the Y-direction pattern.

[0014] Figure 7 To indicate inclusion Figure 1 A flowchart illustrating an example of a spray position adjustment method in a printing system. Detailed Implementation

[0015] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, the drawings are merely examples for illustrating embodiments of the present invention. Also, not all structural elements described in the embodiments of the present invention are necessarily essential structural requirements of the present invention.

[0016] Implementation use Figure 1 An example of the structure of the printing system involved in this embodiment will be described. Figure 1 This is a schematic diagram illustrating one structural example of the printing system.

[0017] Figure 1 The printing system 1 shown includes a control unit 10, an unwinding shaft 20, a transport unit 30, a rewinding shaft 40, a printing unit 50, and a detection unit 70. The printing system 1 can be described as a printing apparatus mainly composed of the unwinding shaft 20, the transport unit 30, the rewinding shaft 40, the printing unit 50, and the control unit 10 that controls them.

[0018] The control unit 10 controls the operation of each part of the printing system 1. The control unit 10, for controlling the printing system 1, can also be called a controller. The control unit 10 only needs to control at least the ink ejection and curing performed by the print head, but it can also control other parts such as the detection unit 70.

[0019] The control unit 10 can be configured, for example, to include a processing unit such as a CPU or GPU, a working memory, and a storage device for storing control programs or parameters. CPU is an abbreviation for Central Processing Unit. GPU is an abbreviation for Graphics Processing Unit. The control unit 10 can also be configured as a System on Chip (SoC). As can be seen from these examples, the control unit 10 can be configured to store control programs in an executable state. However, the control unit 10 can also be configured as a circuit structure such as an FPGA (field-programmable gate array) to store control programs, or as a dedicated circuit. The aforementioned program can include, as described below, a program for controlling the ink ejection and irradiation for ink curing, as well as a program for detecting the pattern or adjusting the ejection position.

[0020] In addition to the detection unit 70, the printing system 1 may also have a detector group (not shown) to detect the condition within the printing system 1, and the control unit 10 may control each part based on the detection results.

[0021] The unwinding shaft 20 unwinds the substrate 100, which is the medium to be printed. The transport section 30 transports the unwound substrate 100. The printing section 50 prints on the substrate 100 transported by the transport section 30. The rewinding shaft 40 rewinds the printed matter 1000, which is the substrate 100 after printing. During the printing of the adjustment pattern, the detection section 70 optically reads the printed matter 1000 wound before the rewinding shaft 40 and detects the adjustment pattern formed on the printed matter 1000.

[0022] In printing system 1, a strip of substrate 100, wound in a roll on unwinding shaft 20 and rewinding shaft 40, is placed along the transport path Pc. The substrate 100 is conveyed in the transport direction Ds in a rotating roller 35 disposed between the unwinding shaft 20 and the rewinding shaft 40, while receiving image printing.

[0023] The substrate 100 can be broadly categorized into paper-based and film-based materials. Specific examples include high-quality paper, high-gloss paper, coated paper, and coated paper, while film-based materials include synthetic paper, PET (polyethylene terephthalate), and PP (polypropylene). Furthermore, the color of the substrate 100 is not limited.

[0024] The printing system 1, when divided by function, consists of three areas: an unwinding area 2, a processing area 3, and a rewinding area 4. The unwinding area 2 is the area where the substrate 100 is unwound from the unwinding shaft 20. The processing area 3 is the area where liquid is sprayed from the substrate 100 unwound from the unwinding area 2. The resulting product formed by the liquid sprayed in the processing area 3 can also be called an image layer. The rewinding area 4 is the area where the printed material 1000 with the image layer formed in the processing area 3 is wound onto the rewinding shaft 40. Furthermore, in the following description, the side of the substrate 100 where the image layer is formed is referred to as the surface, and the opposite side is referred to as the back side.

[0025] The unwinding area 2 includes: an unwinding shaft 20 that winds one end of a substrate 100; and a driven roller 21 that winds the substrate 100 pulled out from the unwinding shaft 20. The unwinding shaft 20 winds and supports one end of the substrate 100 with the surface of the substrate 100 facing outwards. Furthermore, by causing the unwinding shaft 20 to... Figure 1 The substrate 100, which is wound on the unwinding shaft 20, is unwound to the processing area 3 via the driven roller 21 by rotating clockwise.

[0026] The driven roller 21 contacts the substrate 100 and is driven to rotate in the conveying direction Ds of the substrate 100 due to frictional force between itself and the conveyed substrate 100. The substrate 100 is wound onto the unwinding shaft 20 via a core tube 22 that is detachable relative to the unwinding shaft 20. When the substrate 100 on the unwinding shaft 20 is used up, a new core tube 22 with the cylindrical substrate 100 wound on it is installed on the unwinding shaft 20.

[0027] Processing area 3 includes a conveying section 30 and a printing section 50 for printing on the substrate 100 conveyed by the conveying section 30. The conveying section 30 is provided with a front drive roller 31, a rotating roller 35 that supports the substrate 100 in a cylindrical shape, and a rear drive roller 32. The printing section 50 is provided with recording heads 51 and 52 and UV irradiators 61, 62, and 63 as printing heads.

[0028] In processing area 3, the substrate 100 unwound from unwinding area 2 is supported by a rotating roller 35, and is appropriately processed by recording heads 51, 52 and UV irradiators 61, 62, 63 arranged along the outer peripheral surface of the rotating roller 35. Through this processing, an image layer is formed on the substrate 100 in processing area 3.

[0029] A front drive roller 31 is provided on the upstream side of the processing area 3 to convey the substrate 100 toward the rotating drum 35. A rear drive roller 32 is provided on the downstream side of the processing area 3 to convey the substrate 100 toward the take-up shaft 40. The substrate 100, which is conveyed from the front drive roller 31 to the rear drive roller 32, is supported on the rotating drum 35.

[0030] The front drive roller 31 is cylindrical or cylindrical with multiple tiny protrusions formed by spraying on its outer peripheral surface, and it winds the substrate 100 unwound from the unwinding area 2 from the back side. Furthermore, by causing the front drive roller 31 to... Figure 1 The substrate 100, which is unwound from the unwinding area 2, is transported downstream of the transport path Pc by rotating clockwise.

[0031] A clamping roller 31n is provided opposite to the front drive roller 31. The clamping roller 31n abuts against the surface of the substrate 100 when a force is applied to the front drive roller 31, and clamps the substrate 100 between itself and the front drive roller 31. This ensures the friction between the front drive roller 31 and the substrate 100, and enables reliable conveying of the substrate 100 by the front drive roller 31.

[0032] The rotating roller 35 is a cylindrical roller that is supported in a rotatable manner, and it winds the substrate 100, which is being conveyed from the front drive roller 31 to the rear drive roller 32, from the back side. While supporting the substrate 100 from the back side, the rotating roller 35 is driven to rotate in the conveying direction Ds of the substrate 100 due to the frictional force between itself and the conveyed substrate 100.

[0033] In the processing area 3, driven rollers 33 and 34 are provided on both sides of the conveying direction Ds of the area where the substrate 100 is wound onto the rotating roller 35, which change the travel direction of the substrate 100.

[0034] The driven roller 33 wraps the surface of the substrate 100 between the front drive roller 31 and the rotating drum 35 in the conveying direction Ds, and folds the substrate 100 back in the direction of travel toward the rotating drum 35.

[0035] The driven roller 34 wraps the surface of the substrate 100 between the rotating roller 35 and the rear drive roller 32 in the conveying direction Ds, and folds the substrate 100 back in the direction of travel. By folding the substrate 100 back relative to the rotating roller 35 on the upstream and downstream sides in the conveying direction Ds, it is possible to ensure that the substrate 100 is wrapped around the rotating roller 35 for a longer period of time.

[0036] The rear drive roller 32 is cylindrical or cylindrical with multiple tiny protrusions formed by spraying on its outer circumferential surface, and it winds the substrate 100, which is conveyed from the rotating drum 35 via the driven roller 34, from the back side. By causing the rear drive roller 32 to... Figure 1 The substrate 100 is conveyed to the winding area 4 by rotating clockwise. A clamping roller 32n is provided opposite to the rear drive roller 32.

[0037] The clamping roller 32n abuts against the surface of the substrate 100 while being forced towards the rear drive roller 32, and clamps the substrate 100 between itself and the rear drive roller 32. This ensures the friction between the rear drive roller 32 and the substrate 100, thereby enabling reliable conveying of the substrate 100 by the rear drive roller 32.

[0038] Thus, the substrate 100, conveyed from the front drive roller 31 to the rear drive roller 32, is supported on the outer peripheral surface of the rotating drum 35. Furthermore, in the processing area 3, multiple recording heads 51, each corresponding to a different color, are provided for printing color images onto the surface of the substrate 100 supported on the rotating drum 35. Figure 1 The example given shows five recording heads 51 arranged in the transport direction Ds, but it is not limited to five. In addition, two or more recording heads 51 of any color, such as black, can also be provided.

[0039] Each recording head 51 is positioned opposite the surface of the substrate 100, which is wound on the rotating drum 35, with a plurality of gaps between them, and ink of a corresponding color is ejected from the nozzles of the recording head 51 onto the substrate 100 in an inkjet manner. In the printing system 1, a UV-curable ink that is cured by irradiation with ultraviolet light is used as the ink to form an image layer on the substrate 100. Hereinafter, the UV-curable ink will also be referred to as UV ink.

[0040] Furthermore, UV ink is a type of photocurable ink that contains a UV-curing resin. When exposed to ultraviolet light, it cures through a photopolymerization reaction within the UV-curing resin. However, the ink used in printing system 1 is not limited to UV ink; it can also be a liquid that reacts with active energy rays other than ultraviolet light, such as light or electron beams of other wavelengths. That is, printing system 1 can also be configured as other types of printing systems in which such a liquid is sprayed onto a medium and cured using the active energy rays, thereby fixing the liquid onto the medium.

[0041] In processing area 3, UV irradiators 61 and 62 are provided to cure and fix the ink onto the substrate 100. Ink curing is performed in two stages: pre-curing and final curing. A pre-curing UV irradiator 61 is positioned between each of the multiple recording heads 51. The UV irradiator 61 pre-cures the ink by irradiating it with a relatively weak intensity of ultraviolet light, to the point that the ink's wetting and spreading mechanism is sufficiently slow compared to the case without ultraviolet irradiation. This suppresses color mixing, such as the mixing of different colored inks. However, ink curing can be performed in three or more stages, or it can be performed all at once, except during the printing of the pattern adjustment described later. Additionally, a white UV irradiator 61, for example, which sometimes sprays a larger amount of ink as a substrate, can also be used for final curing.

[0042] A UV irradiator 62 for formal curing is provided downstream of the multiple recording heads 51 in the transport direction Ds. The UV irradiator 62 irradiates the ink with ultraviolet light of a stronger intensity than that of the UV irradiator 61, thereby formally curing the ink to the point where the wetting and spreading of the ink stops. The color image formed by the multiple recording heads 51 is formally cured and fixed onto the substrate 100 by the UV irradiator 62.

[0043] A recording head 52 is provided downstream of the UV irradiator 62 in the transport direction Ds. This recording head 52 is positioned with a slight gap relative to the surface of the substrate 100 wound on the rotating roller 35, and sprays UV ink without colorant from a nozzle onto the substrate 100 in an inkjet manner. Hereinafter, the UV ink without colorant will also be referred to as transparent ink. That is, transparent ink is further sprayed onto the image layer formed by the recording head 51.

[0044] A UV irradiator 63 is provided downstream of the recording head 52 in the transport direction Ds. This UV irradiator 63 cures the transparent ink ejected from the recording head 52 by irradiating it with ultraviolet light of a stronger intensity than that of the UV irradiator 61. This allows the transparent ink to be fixed onto the surface of the substrate 100.

[0045] As described above, in the printing system 1, the printing unit 50 includes a printing head comprising recording heads 51 and 52 and UV irradiators 61 to 63. Recording head 51 is an example of a recording head capable of spraying a colored, curable liquid, i.e., colored ink, onto the substrate 100. Furthermore, recording head 52 is an example of a recording head capable of spraying a colorless, curable liquid, i.e., transparent ink, onto the substrate 100. Alternatively, recording heads 51 and 52 may be referred to as printing heads themselves. Thus, the printing unit 50 in this embodiment includes a recording head capable of spraying curable ink onto the substrate 100 for each of multiple colors. In other words, the printing unit 50 includes a recording head capable of spraying a first ink, which is a first color and a curable liquid, and a second ink, which is a second color and a curable liquid, onto the substrate 100.

[0046] Furthermore, UV irradiators 61 to 63 are examples of curing units that cure ink sprayed onto the substrate 100. This curing unit is configured to cure the first and second inks sprayed onto the substrate 100 at different timings. The curing unit can also have its curing controlled by the control unit 10, as exemplified below.

[0047] Thus, in processing zone 3, ink is appropriately sprayed and cured onto the substrate 100 that is wound on the outer periphery of the rotating roller 35. The cured substrate 100, i.e., the printed material 1000, is then conveyed to the take-up zone 4 via the rear drive roller 32.

[0048] In addition to a take-up shaft 40 that winds the other end of the substrate 100, the take-up area 4 also has a driven roller 41 that winds the substrate 100 from the back side between the take-up shaft 40 and the rear drive roller 32. The take-up shaft 40 winds up and supports the other end of the substrate 100 with the surface of the substrate 100 facing outward.

[0049] That is, when the reel 40 is in Figure 1 During clockwise rotation, the substrate 100, conveyed from the rear drive roller 32, is wound onto the take-up shaft 40 via the driven roller 41. The substrate 100 is wound onto the take-up shaft 40 via a core tube 42 that is detachable from the take-up shaft 40. Therefore, when the substrate 100 wound on the take-up shaft 40 becomes fully wound, the substrate 100 can be unloaded together with the core tube 42.

[0050] like Figure 1 As shown, the detection unit 70 is provided in the winding area 4 to optically read and detect the printing result on the surface of the printed material 1000 before it is wound onto the winding shaft 40. This printing result includes the printing of an adjustment pattern formed by a first ink and a second ink. This adjustment pattern is a pattern used to adjust the spray position of the first ink (a curable ink of the first color) on the substrate 100; it can also be called a test pattern for the first ink. In other words, the detection unit 70 detects the printing result of the adjustment pattern for the first ink, printed by the first ink and the second ink after curing by the curing unit. Alternatively, the detection unit 70 may also be provided in the processing area 3 at the rear of the UV irradiator 63.

[0051] Here, the detection unit 70 can be configured and arranged, for example, such that, while moving relative to the printing result along the reading direction, it optically reads and detects at least the printing result of the adjusted pattern. The ejection position refers to the ejection position on the substrate 100. Furthermore, the reading direction includes... Figure 1 In the case of the printing system 1 of the printing section 50 of the illustrated row type, it refers to the direction that is consistent with the transport direction of the substrate 100. In addition, the transport direction of the substrate 100, that is, the transport direction in which the substrate is transported, can also be called the substrate transport direction.

[0052] Additionally, printing system 1 can be connected to a computer (not shown) via wired or wireless means, which outputs printing data to printing system 1 for printing images. Upon receiving the printing data, printing system 1 prints on substrate 100.

[0053] Next, use Figure 2 An example of a printhead in printing system 1 will be described. Figure 2This is a schematic diagram depicting an example of the print head, namely an example of the printing section 50, in a way that it is unfolded on a plane.

[0054] Figure 2 The printing unit 50 shown in the example is equipped with a white recording head 51w, a UV irradiator 61w for formal or pre-curing white ink, a blue-green recording head 51c, a UV irradiator 61c for pre-curing, a magenta recording head 51m, a UV irradiator 61m for pre-curing, a black recording head 51b, a UV irradiator 61b for pre-curing, a yellow recording head 51y, a UV irradiator 62 for formal curing, a recording head 52 for transparent ink, and a UV irradiator 63 for formal curing transparent ink, starting from the upstream side of the substrate transport direction indicated by the arrow.

[0055] On each recording head 51w, 51c, 51m, 51b, 51y, and 52, there are multiple nozzles that eject ink of corresponding colors arranged in a direction perpendicular to the substrate transport direction; a nozzle array arranged in a direction perpendicular to the substrate transport direction; and a chip unit having a nozzle array. Additionally, in Figure 2 The text lists examples where each chip unit in each recording head 51w, 51c, 51m, 51b, 51y, and 52 has two rows of nozzles, and the chip units are arranged in a zigzag pattern. However, this arrangement is merely for increasing ejection density; both the nozzle rows and chip units can be arranged in one row or more than three rows. Furthermore, although in... Figure 2 Examples of colored inks, including white, blue-green, magenta, black, and yellow, are provided, but the colors used and their quantities are not limited to these. Furthermore, the order in which the various colors of the colored inks are arranged is not limited. Figure 2 the order shown in the example.

[0056] Next, use Figures 3 to 6 An example of an adjustment pattern printed in printing system 1 and the detection of the adjustment pattern by detection unit 70 will be described. Figure 3 A schematic diagram illustrating an example of this adjustment pattern. Figure 4 for Figure 3 The X-direction section at the position indicated by the dashed line in the grid-like Y-direction pattern with a length component in the Y-direction shown in the adjustment pattern. In other words, Figure 4 This is a schematic diagram showing a cross-section with the Y direction as the normal direction at the position indicated by the single-dotted line in the Y-direction pattern. Figure 5 To indicate formation Figure 3 and Figure 4 This is a schematic diagram illustrating the process of adjusting the pattern. Figure 5For simplicity, only one line of the Y-direction pattern is extracted and its formation process is schematically shown. Figure 6 To indicate that the testing department has 70 pairs Figure 3 and Figure 4 This is a schematic diagram illustrating the detection of the Y-direction pattern.

[0057] The control unit 10 controls the ejection of colored ink, or the ejection of both colored and transparent ink, performed by the printing unit 50. Furthermore, the control unit 10 also controls the curing unit and the detection unit 70. In particular, when printing the aforementioned adjustment pattern onto the substrate 100 as a medium, the control unit 10 performs the following control: While examples are given here including patterns for adjusting the ejection positions in both the X and Y directions, this is not a limitation; a pattern including only one direction may also be used.

[0058] First, the control unit 10 controls the recording head of the printing unit 50 for the first ink in a manner that forms a first pattern using the first ink. The first color, which is the color of the first ink, can be set to white or transparent, but is not limited to these. In particular, it is set to a color with a small color difference from the substrate 100 and poor visual confirmation.

[0059] The control unit 10 forms a first finished product on the substrate 100 by curing the first ink of the first pattern. The finished product may also be referred to as a cured finished product.

[0060] Next, the control unit 10 performs control such that it ejects second ink from the recording head for second ink in the printing unit 50 in such a way that the second ink completely coats a second area, including the first area where the first product is formed, on the substrate 100 on which the first product is formed. Furthermore, although "completely coated" means uniformly coated, some unevenness may still exist.

[0061] As described above, the curing section is configured to allow the first ink and the second ink sprayed onto the substrate 100 to cure at different times. This structure, for example, can be achieved through... Figure 2 This is achieved by arranging UV irradiators at multiple locations as shown. Furthermore, during the printing of the pattern, the control unit 10 causes the second ink in the second region to cure after a predetermined time elapsed since the second ink was ejected.

[0062] Regarding the printing of such adjusted patterns, examples are given where the substrate 100 is white, the first color is white, and the second color is black. The control unit 10 controls the recording head 51w to generate the first pattern using white ink, and cures it using a UV irradiator 61w that emits white ink. Examples include... Figure 3As illustrated, the first pattern is illustrated by an example consisting of multiple straight grid lines 83x arranged side by side and multiple straight grid lines 83y arranged side by side. Grid line 83y is a grid line having a length component in the reading direction. Grid line 83x is a grid line having a length component in the direction perpendicular to the reading direction.

[0063] Furthermore, the term "grid line" in this application refers to a dashed line formed by line segments of predetermined length or by intervals between multiple line segments. The size of each line segment and interval is only required to be such that the combination of line segments and intervals can be identified as a dashed line. Moreover, the size of each line segment and interval does not need to be fixed within the dashed line as it is with a single-dotted line.

[0064] Furthermore, the "length component" in this application specification refers to the component of the width and length of the grid line that corresponds to the length of the longer side. For example, "having a length component in the reading direction" means that the reading direction is approximately parallel to the direction of the longer side of the grid line. Of course, the same applies when the grid line is a dashed line; it means that the direction of the longer side, formed by adding the segments and intervals that constitute the dashed line, is approximately parallel to the reading direction.

[0065] Thus, as the first result, a structure is formed on the substrate 100. Figure 3 The first pattern is formed by multiple grid lines 83x and 83y. Additionally, in Figure 3 In the text, the blank arrow mark indicates the reading direction, i.e. the scanning direction, which is the direction of reading performed afterward in the detection unit 70, but the reading direction can also be the opposite direction.

[0066] Next, the control unit 10 controls the recording head 51b by coating a second region, including the first region where the first product is formed, with black ink on the substrate 100 on which the first product is formed. Thus, the substrate 100, which is formed with a second region 82x including multiple grid lines 83x and a second region 82y including multiple grid lines 83y, is coated with black ink. However, compared to... Figure 3 The situation shown in the illustration is different. At the moment the black ink is sprayed, the second regions 82x and 82y cover the grid lines 83x and 83y respectively, making the grid lines 83x and 83y invisible to the naked eye.

[0067] Furthermore, during the application of this coating, the control unit 10 can also control the recording head 51b by simultaneously forming straight grid lines 81x and 81y with black ink at positions connected to or separated from the grid lines 83x and 83y, for reference. The grid lines 81x and 81y can be formed parallel to the straight X-direction grid lines 83x and Y-direction grid lines 83y formed with white ink, respectively. For example, the grid line 81x is used to determine the spray position of the X-direction grid line 83x based on its relative position to the X-direction grid line 83x. Similarly, the grid line 81y is used to determine the spray position of the Y-direction grid line 83y based on its relative position to the Y-direction grid line 83y. The spacing of the grid lines 81 is not limited to... Figure 3 The positions are evenly spaced as shown. Furthermore, the positions configured in the X direction are not limited to the Y-direction grid lines 83y. Similarly, the positions configured in the Y direction are not limited to the X-direction grid lines 83x.

[0068] Next, the control unit 10 controls the UV irradiator 61b in such a way that the black ink cures after a predetermined time has elapsed since it was ejected. Alternatively, the object of curing control here can be at least one of the UV irradiators 62 and 63 instead of the UV irradiator 61b, or at least one of the UV irradiators 62 and 63 in addition to the UV irradiator 61b.

[0069] As described above, the curing control described above can also be as follows: Figure 2 As shown, UV irradiation can be performed using only any one of the UV irradiators, such as the UV irradiator 61b, which is located further back than the recording head 51w and the recording head 51b. Furthermore, the curing control described above can also be implemented by additionally considering the control of any one of the following: the transport speed of the substrate 100, the timing of UV irradiation, and the irradiation amount.

[0070] The aforementioned predetermined time is the time it takes for the black ink to flow from the grid lines 83x and 83y, exposing them. This time can be appropriately set based on the ink viscosity, the thickness of the grid lines 83x and 83y, etc. By storing this predetermined time as a setting value in a storage device (not shown), it can be used as a reference when adjusting the pattern printing. This predetermined time can be obtained, for example, by performing a test print beforehand using a predetermined type of ink and a predetermined thickness of grid lines 83y, and measuring the time taken until the black ink sprayed onto the cured grid lines 83y flows and exposes them.

[0071] Furthermore, when revealing grid lines 83x and 83y, it is not necessary to reveal all grid lines for the reasons explained later.

[0072] Here, as Figure 4 As illustrated, the grid lines 83y exposed by the flow of black ink form upwardly convex arc-shaped grid lines on a plane perpendicular to the Y direction, which is the reading direction. Although not shown, grid lines 83x form upwardly convex arc-shaped grid lines on a plane perpendicular to the X direction. Furthermore, through curing after exposure, a second region 82y, which is a fully coated area of ​​black ink, is formed on the substrate 100 around the grid lines 83y, and similarly, a second region 82x, which is a solid coated area of ​​black ink, is formed around the grid lines 83x. In addition, through this curing, grid lines 81x and 81y are also formed on the substrate 100. As a result, a grid with grid lines 81x and 81y formed on the substrate 100 is formed. Figure 3 Printed material 1000 with the adjustment pattern shown.

[0073] The grid lines 83y formed in this way are exposed on the surface by the flow of black ink sprayed onto the grid lines. Furthermore, by using the flowed black ink as a base, the color difference between the exposed part and the base is ensured, thereby enabling high-precision detection of the spray position.

[0074] At the portion adjacent to the exposed portion of the grid line 83y that is thus exposed and formed, such as Figure 5 As illustrated in 80d, an area with a higher amount of black ink is formed, and the hue of the black ink changes beyond the adjacent portion. Specifically, the concentration of black ink is higher in the adjacent portion compared to the solid black ink application area outside the adjacent portion. That is, the hue of the black ink in the second region 82y changes in the portion adjacent to the exposed portion of the grid line 83y and beyond the adjacent portion, thus making it possible to distinguish the exposed grid line 83y from the second region 82y. Furthermore, the adjacent portion and the non-adjacent portion can also be referred to as the boundary portion and the non-boundary portion, respectively.

[0075] In addition, Figure 4 Examples of grid lines 83y with semi-circular cross-sectional shapes are given, but their shapes are not limited to these and vary depending on the amount of white ink droplets, viscosity, and curing control. For example, each grid line 83y can have a circular arc cross-sectional shape or a portion of a non-circular arc that approximates an ellipse. Furthermore, the thickness of each grid line 83y, which is the object of testing, also varies depending on the flow until the black ink cures. Additionally, the shape and thickness of grid line 83x are the same as those of grid line 83y.

[0076] Next, use Figure 5 ,about Figure 3 The process of forming the adjustment pattern shown is to... Figure 4 The following explanation uses the Y-direction pattern as an example. First, as illustrated in state 80a, white ink is sprayed onto the substrate 100 to form grid lines 83y. Next, as illustrated in state 80b, the sprayed white ink is irradiated with UV light using a UV irradiator 61w and cured. Next, as illustrated in state 80c, black ink is sprayed to completely coat a second area 82y, including the area of ​​cured white ink.

[0077] Subsequently, as time passes, as illustrated in state 80d, the black ink in the second region 82y flows in the direction marked by the arrow, thus exposing the grid lines 83y of the cured white ink. After a predetermined time has elapsed since the black ink was ejected, UV irradiation is applied using a UV irradiator 61b or the like, thereby curing the black ink. In this way, a layer is formed... Figure 4 The Y-direction pattern is illustrated in the figure. The X-direction pattern is also formed on the substrate 100 simultaneously and in the same manner as the Y-direction pattern.

[0078] The detection performed by the detection unit 70 on the adjustment pattern including the grid lines 83y as described above will be described. The detection unit 70 may, for example, include an irradiation unit for irradiating light and a light-receiving unit for receiving reflected light reflected from the grid lines. Furthermore, the irradiation unit may also be as described in... Figure 6 As schematically indicated by multiple arrows, light is incident at an angle not equal to 0° relative to the substrate 100 with the grid lines 83y formed. Furthermore, in Figure 6 In the text, the hollow arrow mark also indicates the reading direction.

[0079] Thus, when illuminated by the detection unit 70, as described above, the intensity of reflected light received by the light-receiving unit differs at the exposed portion of the grid line 83y and at the adjacent and non-adjacent portions of the second region 82y with respect to the grid line 83y. Specifically, in this embodiment, the thickness of the second region 82y changes depending on the presence or absence of the grid line 83y, thereby changing its color. For example, if the second region 82y is black, the adjacent portions of the grid line 83y can be visually confirmed as a darker black than the sprayed color from any angle. Therefore, the exposed grid line 83y can be detected as a grid line by the detection unit 70 regardless of the angle from which it is detected.

[0080] Thus, in this embodiment, by creating an adjustment pattern through different curing times for the white and black inks, even if the white grid lines 83y are formed first, a second region that functions as a base can then be formed, thereby enabling the detection of the white ink's spray position. Furthermore, in the grid lines formed by the above method, since there are tonal differences not only between the exposed portion of the grid line 83y and the second region, but also between adjacent and non-adjacent portions, the spray position can be detected with high precision even if the exposed portion is small. Moreover, while the thickness of the sprayed grid line 83y and the ultimately exposed grid line 83y is not particularly limited, the thickness of the exposed grid line 83y, or the thickness of the exposed grid line 83y and its adjacent portions, only needs to be of a thickness that functions as an adjustment pattern for adjusting the spray position. The same applies to the grid line 83x.

[0081] As explained above, in this embodiment, the grid line 83y is included in the adjustment pattern in a manner that allows for high-precision detection of the spray position regardless of the device structure of the detection unit 70 or the observation angle of the inspector performing the verification. Therefore, according to this embodiment, an adjustment pattern can be used to accurately detect and adjust the spray position of inks of colors that are difficult to visually confirm on the substrate 100. Furthermore, in this embodiment, for inks with curable properties, the detection accuracy of the spray position of liquids such as white ink, which have poor visual confirmability, can be improved through a simple structure that studies the spray sequence and curing sequence of inks of other colors.

[0082] In addition, such as Figure 1 As illustrated, the detection unit 70 can be an in-line sensor, i.e., it is disposed along the path that transports the substrate 100. In this case, of course, for the purpose of detecting the adjustment pattern, the detection unit 70 is disposed at a position where the printed material 1000 after printing by the print head can be detected. The detection unit 70 can be, for example, an in-line sensor with a sensor group arranged in a direction perpendicular to the transport path.

[0083] also, Figure 1 The illustrated printing system 1 is a system in which a printhead is mounted as part of a line-type printing apparatus. Furthermore, in this printhead, nozzles that eject ink of various colors are arranged only across the width of the printing area of ​​the substrate 100 in a direction perpendicular to the transport direction of the substrate 100. Thus, when the printing system 1 includes a line-type printing apparatus, the detection unit 70 can be positioned on the transport path of the substrate 100, allowing for detection in a shorter time compared to situations where this is not the case.

[0084] Moreover, such as Figure 2As illustrated in the printing section 50, the print head may have a structure in which the nozzle for ejecting the first ink is located upstream of the nozzle for ejecting the second ink on the path for conveying the substrate 100. For example, as Figure 2 As exemplified by the white ink, the recording head 51w equipped with a nozzle that ejects white ink can also be located at the upstream end in the transport direction. Since white ink is often used as a base when forming an image layer from colored ink, it is preferable to position the recording head 51w upstream even in scenarios where the image desired by the user is being printed. Therefore, by arranging the recording head equipped with nozzles for white ink (example of the first ink) and a second ink as described above, it is possible to easily perform the curing sequence as in this embodiment simply by changing the position of the ink for printing pattern adjustments or without reversing the paper feed of the substrate 100. Furthermore, the order in which the recording heads equipped with nozzles that eject colored inks other than white ink are arranged in the transport direction is not limited. In addition, since transparent ink is often used for forming the uppermost layer of finishing processes such as gloss, it is preferable to position the recording head 52 downstream even in scenarios where the image desired by the user is being printed.

[0085] Regarding the effects of this embodiment using such a printhead structure, comparative examples will be provided for explanation. In the comparative examples, similar to the examples described above, a combination of a first color being white and a second color being black is used, and a printhead structure composed of... Figure 2 The printing section 50 shows the configuration of the recording head. White is an example of a color with low visual certainty, and black is an example of a color with high visual certainty. In the comparative example, in order to print as... Figure 3 The pattern shown is adjusted so that a base layer is formed on the substrate 100 with black ink, and then grid lines are formed on the base layer with white ink.

[0086] However, in the comparative example, due to the arrangement of the recording heads, such as the recording head 51w equipped with a nozzle that ejects white ink, being positioned at the upstream end of the transport direction, it is impossible to form such an adjustment pattern in a normal printing process. Therefore, in the comparative example, it is necessary to interchange the position of the recording head 51w with the black recording head 51b, or with a recording head of another color positioned downstream of the recording head 51b. Alternatively, in the comparative example, it is necessary to first form a base layer on the substrate 100 with black ink, then perform reverse feeding by transporting the substrate 100 in the opposite direction of the transport direction, and form grid lines on the base layer with white ink. In either method, in the comparative example, a considerable amount of time is required until the adjustment pattern is printed. Moreover, in the comparative example, when a structure is adopted in which a detection unit such as a line scanner is located downstream of all the recording heads for detecting the adjustment pattern, a considerable amount of time is required from the start of the adjustment pattern formation to the end of the detection. In contrast, in this embodiment, printing is possible without changing the ink position or reversing the substrate 100 simply to adjust the printing pattern, as described above. Figure 3 The adjustment pattern shown.

[0087] In this embodiment, although a second region is subsequently formed, the colored liquid, which acts as a base, flows along the shape of the previously solidified grid lines. Therefore, after flowing, the grid lines become raised compared to the second region. Thus, in this embodiment, detection can be performed regardless of the viewing angle, by recognizing that the hue at the spray location differs from that at a non-spray location. This allows for high-precision detection of the spray location regardless of the device structure of the detection unit 70 or the viewing angle of the inspector performing the confirmation.

[0088] The above examples illustrate that the substrate 100 is white, the first color is white, and the second color is black, but these color combinations are not limited to the examples. For instance, if the substrate 100 is a colored medium and both the first and second colors are colored, and the color difference between the substrate 100 and the first color is less than the color difference between the substrate 100 and the second color, the accuracy of the pattern detection, i.e., the detection of the first pattern, can be improved.

[0089] Furthermore, there are cases where either or both of the medium and the first color are colorless and transparent. In such cases, the second color can be set to a color with a lower reflectivity of the light irradiated from the detection unit 70 compared to the first color. For example, if the substrate 100 is a colored medium, the first color is colorless, and the second color is colored, the second color can be set to a color with lower reflectivity. As a result, more light irradiated from the detection unit 70 is reflected on the exposed portion of the first color, while most of the light irradiated from the detection unit 70 is absorbed on the exposed portion of the second color, thus weakening the reflected light. Consequently, the second area becomes darker, and the portion of the grid lines exposed becomes brighter, enabling detection based on the brightness difference. Therefore, when either or both of the medium and the first color are colorless and transparent, by setting the second color to a color with lower reflectivity compared to the first color, the accuracy of pattern detection can be improved.

[0090] Furthermore, when either or both of the medium and the first color are colorless and transparent, it is difficult to detect the spray position when the incident light passes through the medium. Therefore, it is preferable to detect the reflected light by making the incident light incident from an angle that is not 0° relative to the adjustment pattern.

[0091] In addition, Figures 3 to 6 The example given is that the adjustment pattern includes not only grid lines 83y in the Y direction, which are difficult to detect in the reading direction, but also grid lines 83x. However, even if grid lines in either direction are included, the grid lines can be detected in the detection unit 70.

[0092] Next, use Figure 7 An example of a spray position adjustment method, including the printing method in printing system 1, will be briefly described. Figure 7 This is a flowchart illustrating an example of a spray position adjustment method for a printing method in printing system 1.

[0093] In this spray position adjustment method, the printing system 1 includes: a printing process for printing an adjustment pattern for adjusting the spray position of the first ink onto the substrate 100, and an adjustment process for adjusting the spray position according to the printed adjustment pattern.

[0094] First, the control unit 10 of the printing system 1 controls the print head exemplified by the printing unit 50 in a manner that forms a first pattern from the first ink (step S1). Next, the control unit 10 cures the first ink of the formed first pattern (step S2). In the example above, the control unit 10 causes white ink to be ejected from the recording head 51w and cured using a UV irradiator 61w.

[0095] Next, the control unit 10 controls the print head in such a way that it coats a second region, including the first region where the first product is formed, with a second ink on the substrate 100 on which the first product is formed using a first pattern (step S3). Then, the control unit 10 causes the second ink in the second region to cure after a predetermined time has elapsed since the second ink was ejected (step S4). In the example above, the control unit 10 causes black ink to be ejected from the recording head 51b and then cures it by passing it through a UV irradiator 61b or the like after a predetermined time has elapsed since the ejection.

[0096] Next, the control unit 10 controls the detection unit 70 to detect the printing result. Here, the detection unit 70 sets the Y direction as the reading direction and moves relative to the printing result along the reading direction, while optically reading and detecting the printing result of the adjustment pattern composed of the cured first ink and the cured second ink onto the medium (step S5).

[0097] Finally, based on the detection result of the adjustment pattern containing the first pattern composed of the first ink detected by the detection unit 70, the control unit 10 adjusts the spray position of the first ink (step S6) and ends the process.

[0098] The adjustment of the spray position in step S6 can be implemented using existing technology. This adjustment will be briefly explained. For example, if the detected white grid line has shifted in the X direction, the control unit 10 changes the combination of nozzles that sprayed ink at the corresponding spray position to a combination of adjacent nozzles, based on the spray position of the grid line. For example, if the detected white grid line has shifted in the Y direction, the control unit 10 changes the timing of the ink ejected from the nozzles that sprayed ink at the corresponding spray position, based on the spray position of the grid line, and adjusts it in a way that eliminates the shift.

[0099] In addition, such adjustments can be implemented by including colored baselines, such as grid lines 81x and 81y, in the adjustment pattern, and eliminating the offset based on the offset of the white grid lines from the baselines.

[0100] Other application examples Furthermore, the present invention is not limited to the above-described embodiments, but can be appropriately modified without departing from the spirit of the invention. For example, although in this embodiment, an ink with poor visual confirmability is used to form an adjustment pattern for the purpose of improving the detection accuracy of inks with poor visual confirmability, it can also be applied to inks with good visual confirmability. Additionally, although transparent inks are described as inks without coloring materials, any ink that allows light to pass through and reflect to a certain extent in a manner that enables the effects of the present invention may contain trace amounts of coloring materials. Furthermore, the UV irradiator for formal curing only needs to be capable of UV irradiation at a stronger intensity than that for pre-curing. Furthermore, the curing of the ink is not limited to the example of curing UV ink by irradiating it with UV light; thermosetting inks may also be cured by heating.

[0101] Furthermore, although this embodiment describes a printing system with a line-type printing apparatus, this disclosure can also be applied to printing systems with a serial-type printing apparatus. In the serial-type case, the reading direction is perpendicular to the transport direction. Moreover, this embodiment can be widely applied to inkjet technology-using devices such as copiers, fax machines, and multifunction printers with these functions. Furthermore, the detection unit 70 exemplified is not limited to the example of being positioned along the path of media transport; it can also be installed on other devices. That is, the printing system 1 can also have the printing apparatus and the detection unit 70 as separate devices. Furthermore, the printing system 1 can also be a printing apparatus with a scanning function; in this case, after the adjustment pattern is printed, the user can place the printed material on a document tray or an automatic document transport device and scan it to perform adjustment pattern detection.

[0102] Furthermore, the aforementioned program includes a set of commands (or software code) for causing the computer to perform one or more functions described in the embodiments when read by the computer. The program may also be stored on a non-transitory computer-readable medium or a physical storage medium. By way of example, and not limitation, a computer-readable medium or a physical storage medium includes random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD), or other memory technologies. Furthermore, by way of example, and not limitation, a computer-readable medium or a physical storage medium includes CD-ROM, digital versatile disc (DVD), Blu-ray disc, or other optical disc storage, magnetic tape cassette, magnetic tape, disk storage, or other magnetic storage devices. The program may also be transmitted on a temporary computer-readable medium or a communication medium. By way of non-limiting example, a temporary computer-readable medium or communication medium includes electrical, optical, acoustic, or other forms of propagation signals.

[0103] Although the present invention has been described above with reference to the embodiments described above, the present invention is not limited to the structure of the above embodiments, but obviously also includes various modifications, alterations and combinations that can be made by those skilled in the art within the scope of the claims of this application.

[0104] Symbol Explanation 1…Printing system; 2…Unwinding area; 3…Processing area; 4…Rewinding area; 10…Control unit; 20…Unwinding shaft; 21…Driven roller; 22…Core tube; 30…Conveying unit; 31…Front drive roller; 31n…Clamping roller; 32…Rear drive roller; 32n…Clamping roller; 33, 34…Driven rollers; 35…Rotating cylinder; 40…Rewinding shaft; 41…Driven roller; 42…Core tube; 50…Printing unit; 51, 51b, 51c, 51m, 51w, 51y, 52…Recording head; 61, 61b, 61c, 61m, 61w, 62, 63…UV irradiator; 70…Detection unit; 81x, 81y…Grid lines; 82x, 82y…Second area; 83x, 83y…Grid lines; 100…Substrate; 1000…Printed material.

Claims

1. A printing system comprising: A printhead capable of spraying a first ink and a second ink onto a medium, wherein the first ink is a first-color, curable liquid and the second ink is a second-color, curable liquid; A control unit that controls the ejection of the first ink and the second ink by the printhead; A curing section that cures the first ink and the second ink sprayed onto the medium at different timings; The testing unit inspects the printing results achieved by the first ink and the second ink after curing using the curing unit. The control unit performs the following processing: The print head is controlled in such a way that a first pattern is formed by the first ink, and The print head is controlled to spray the second ink into a second region, including a first region where the first ink forming the first pattern has been cured, onto the medium on which the first ink has been formed. The curing section causes the second ink in the second region to cure after a predetermined time has elapsed since it was ejected.

2. The printing system as claimed in claim 1, wherein, The medium is a colored medium. Both the first color and the second color are colored. The color difference between the medium and the first color is less than the color difference between the medium and the second color.

3. The printing system as claimed in claim 1, wherein, When at least one of the medium and the first color is colorless. The second color is a color with lower reflectivity compared to the first color.

4. The printing system as claimed in claim 1 or 2, wherein, The printing system is a system in which the printhead is mounted as part of a line printing apparatus. The printhead has a structure in which the nozzle that ejects the first ink is located upstream on the path for conveying the medium, compared to the nozzle that ejects the second ink.

5. The printing system as claimed in claim 1 or 2, wherein, The detection unit, It is positioned on the path for transporting the medium, and While moving relative to the printing result along the reading direction, the printing result is optically read and detected.

6. The printing system as claimed in claim 1 or 2, wherein, The printing result is the result of printing an adjustment pattern that is used to adjust the spray position of the first ink on the medium.

7. A printing method comprising printing a first pattern using a printing system having a printhead capable of ejecting a first ink and a second ink onto a medium, wherein the first ink is a first color and a curable liquid, and the second ink is a second color and a curable liquid, wherein in the printing method, The print head is controlled in such a way that the first pattern is formed by the first ink. The first ink in the formed first pattern is cured. The print head is controlled to spray the second ink into a second region, including a first region where the first ink forming the first pattern has been cured, onto the medium on which the first ink has been formed. The second ink in the second region is cured after a predetermined time has elapsed since it was ejected. The printing results achieved by the first ink and the second ink after curing are tested.

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