Printing system and printing method

Abstract

This invention provides a printing system and a printing method. One aspect of the printing system disclosed herein includes: a print head capable of ejecting transparent ink and colored ink onto a medium, wherein the transparent ink is a colorless and curable liquid, and the colored ink is a colored liquid; a control unit for controlling the ejection of the transparent ink and the colored ink; and a detection unit. The detection unit, while moving relative to the printing result along a reading direction, optically reads and detects the printing result of an adjustment pattern used to adjust at least the spray position of the transparent ink on the medium. When the adjustment pattern is printed, the control unit controls the print head such that the transparent ink forms grid lines with a length component in the reading direction at the position overlapping with the substrate layer. The grid lines are grid lines having a plurality of arc-shaped structures with an upwardly convex surface shape in the cross-section formed in the reading direction.

Description

Technical Field

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

[0002] Patent Document 1 describes a technique for easily and accurately detecting test patterns formed by transparent ink, which has poor visual confirmability, by spraying transparent ink onto a substrate with minute irregularities on its surface and detecting the spraying position information of the transparent ink.

[0003] However, when printing an adjustment pattern for adjusting the spray position onto a commonly used medium using a transparent ink that cures under UV (Ultra Violet) light, the accuracy of detecting this adjustment pattern is poor, making it difficult to accurately determine the spray position. While the technology described in Patent Document 1 improves the accuracy of detecting the spray position of the transparent ink onto the medium, it requires preparing a medium with uneven surfaces, thus increasing the time and cost of adjustment.

[0004] Therefore, it is desirable to develop a technique that can detect the adjustment pattern of the spray position of transparent ink on the medium without incurring extra effort and cost for adjustment.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2005-224989. Summary of the Invention

[0006] One aspect of the printing system disclosed herein includes: a print head capable of ejecting transparent ink and colored ink onto a medium, wherein the transparent ink is a colorless and curable liquid, and the colored ink is a colored liquid; a control unit for controlling the ejection of the transparent ink and the colored ink by the print head; and a detection unit that, while moving relative to the printing result along a reading direction, optically reads and detects the printing result of an adjustment pattern for adjusting the spray position of the transparent ink on the medium, wherein the control unit, when printing the adjustment pattern onto the medium, controls the print head such that the transparent ink forms grid lines having a length component in the reading direction at positions overlapping with the substrate layer, wherein the grid lines are grid lines having a plurality of arc-shaped structures with upwardly convex surface shapes in the reading direction. One aspect of this disclosure relates to a printing method comprising a printing system having a printhead capable of ejecting transparent ink and colored ink onto a medium, and a method for printing an adjustment pattern for adjusting at least the ejection position of the transparent ink on the medium, wherein the transparent ink is a colorless and curable liquid, and the colored ink is a colored liquid, wherein the printhead is controlled such that the transparent ink forms grid lines having a length component in a first direction at a position overlapping with the substrate layer, and while the first direction is set as a reading direction and the printhead moves relative to the printing result along the reading direction, the printing result of the adjustment pattern is optically read and detected, wherein the grid lines are grid lines having a plurality of arc-shaped structures with an upwardly convex surface shape in the reading direction. Attached Figure Description

[0007] Figure 1 This is a block diagram illustrating a structural example of a printing system according to an embodiment.

[0008] Figure 2 This is a schematic diagram depicting an example of a recording head in a printing system, shown unfolded on a plane.

[0009] Figure 3 To indicate in Figure 1 A schematic diagram illustrating an example of an adjustment pattern being printed in a printing system.

[0010] Figure 4 To indicate Figure 3 The diagram shows a cross-section at the position indicated by the single-dot grid line in the adjustment pattern.

[0011] Figure 5 To indicate the use of the inspection department of the printing system Figure 3 and Figure 4 The diagram shows the detection process using the adjusted pattern.

[0012] Figure 6 This is a schematic diagram illustrating the adjustment pattern used in the printing system involved in the comparative example.

[0013] Figure 7 To indicate Figure 6 The diagram shows a cross-section at the position indicated by the single-dot grid line in the adjustment pattern.

[0014] Figure 8 To illustrate the detection unit of the printing system involved in the comparative example Figure 6 and Figure 7 The diagram shows the detection process using the adjusted pattern.

[0015] Figure 9To indicate inclusion Figure 1 A flowchart illustrating an example of a spray position adjustment method, including printing methods in a printing system. Detailed Implementation

[0016] 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. Additionally, not all structural elements described in the embodiments of the present invention are necessarily essential structural requirements of the present invention.

[0017] 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 this structural example.

[0018] 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.

[0019] The control unit 10 controls the operation of each part of the printing system 1. Since the control unit 10 is used to control the printing system 1, it can also be called a controller. Although the control unit 10 only needs to control at least the ejection of transparent and colored inks by the print head, it can also control other parts such as the detection unit 70.

[0020] 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 implementing control related to ink ejection and irradiation, as well as a program for adjusting pattern detection or its detection and adjustment of the ejection position.

[0021] In addition to the detection unit 70, the printing system 1 may also have a detector group (not shown), and the status within the printing system 1 may be monitored by the detector group, and the control unit 10 may control each part based on the detection results.

[0022] 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 performs printing 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 before it is rewound onto the rewinding shaft 40 and detects the adjustment pattern formed on the printed matter 1000.

[0023] 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 while being placed on a rotating roller 35 between the unwinding shaft 20 and the rewinding shaft 40, and an image is printed on it.

[0024] The substrate 100 can be broadly categorized into paper and film types. Specific examples include high-quality paper, high-gloss paper, coated paper, and coated paper; and synthetic paper, PET (Polyethylene terephthalate), and PP (polypropylene). Furthermore, there are no restrictions on the color of the substrate 100.

[0025] 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 onto 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, on which the image layer has been formed in the processing area 3, is wound onto the rewinding shaft 40. Furthermore, in the following description, the side of the substrate 100 on which the image layer is formed is referred to as the surface, and the opposite side is referred to as the back side.

[0026] 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 1The 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.

[0027] 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 on 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.

[0028] Processing area 3 includes a conveying section 30 and a printing section 50 for printing on a substrate 100 conveyed by the conveying section 30. The conveying section 30 is equipped with a front drive roller 31, a cylindrical rotating roller 35 that supports the substrate 100, and a rear drive roller 32. The printing section 50 is equipped with recording heads 51 and 52 and UV irradiators 61, 62, and 63 as printing heads.

[0029] 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.

[0030] 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 conveyed from the front drive roller 31 to the rear drive roller 32 is supported on the rotating drum 35.

[0031] The front drive roller 31 is cylindrical or cylindrical in shape 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 conveyed downstream of the conveying path Pc by rotating clockwise.

[0032] A clamping roller 31n is disposed 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, thereby enabling reliable conveying of the substrate 100 by the front drive roller 31.

[0033] 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. The rotating roller 35 supports the substrate 100 from the back side and 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.

[0034] 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.

[0035] 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.

[0036] The driven roller 34 winds 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, the winding of the substrate 100 onto the rotating roller 35 can be ensured for a longer period of time.

[0037] 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.

[0038] 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.

[0039] 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 roller 35. Furthermore, in the processing area 3, multiple recording heads 51, each corresponding to a different color, are provided for printing color images on the surface of the substrate 100 supported on the rotating roller 35. Although in Figure 1 The example given is five recording heads 51 arranged in the transport direction Ds, but it is not limited to five. Two or more recording heads 51 of any color, such as black, may also be provided.

[0040] 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 the corresponding color is ejected from the nozzles of the recording head 51 onto the substrate 100 by inkjet spraying. In the printing system 1, a UV-curable ink that cures by irradiation with ultraviolet light is used as the ink, and an image layer is formed on the substrate 100. Hereinafter, the UV-curable ink will also be referred to as UV ink.

[0041] 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. In other words, printing system 1 can also be configured as other types of printing systems that spray the liquid into a medium and cure it through the active energy rays, thereby fixing the liquid onto the medium.

[0042] In processing area 3, UV irradiators 61 and 62 are provided to cure the ink and fix it 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 becomes sufficiently slow compared to the case without UV irradiation. This suppresses color mixing caused by the mixing of different colored inks. However, ink curing can be performed either in a single operation or in three or more stages. Additionally, a white UV irradiator 61, for example, used for later stages where a larger amount of ink is ejected as a substrate, can also be used for final curing.

[0043] A UV irradiator 62 for formal curing is provided on the downstream side 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.

[0044] 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 colorless UV ink from a nozzle onto the substrate 100 in an inkjet manner. Hereinafter, the colorless UV ink will also be referred to as transparent ink. In other words, transparent ink is further sprayed onto the image layer formed by the recording head 51.

[0045] A UV irradiator 63 is provided downstream of the recording head 52 in the transport direction Ds. This UV irradiator 63 uses ultraviolet light of a stronger intensity than that of the UV irradiator 61 to formally cure the transparent ink ejected from the recording head 52. This allows the transparent ink to be fixed onto the surface of the substrate 100.

[0046] 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 colored ink, which is a colored and curable liquid, onto the substrate 100. Recording head 52 is an example of a recording head capable of spraying transparent ink, which is a colorless and curable liquid, onto the substrate 100. Alternatively, recording heads 51 and 52 may be referred to individually as printing heads.

[0047] Thus, in processing zone 3, ink is appropriately sprayed and cured on 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 conveyed to the take-up zone 4 by 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] In other words, 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 relative to the take-up shaft 40. Therefore, when the substrate 100 wound on the take-up shaft 40 becomes a full roll, the substrate 100 can be unloaded together with the core tube 42.

[0050] like Figure 1As shown, the detection unit 70 is configured to optically read and detect the printing result on the surface of the printed material 1000 before it is wound onto the take-up reel 40 in the take-up area 4. This printing result includes the result of printing an adjustment pattern. Alternatively, the detection unit 70 may be located in the processing area 3 further back than the UV irradiator 63.

[0051] In particular, the detection unit 70 optically reads and detects at least the printing result of the adjustment pattern while moving relative to the printing result along the reading direction. Here, the adjustment pattern is a pattern used to adjust the spray position of transparent ink on the substrate 100, and can also be called a test pattern. The spray position refers to the spray position on the substrate 100. Furthermore, the reading direction refers to the direction in which the ink is sprayed onto the substrate 100. Figure 1 In the case of the printing system 1 of the printing section 50 of the illustrated row type, the direction is consistent with the transport direction of the substrate 100. In addition, the transport direction of the substrate 100, that is, the transport direction for transporting the substrate, can also be called the substrate transport direction.

[0052] Furthermore, printing system 1 can be connected to a computer (not shown) via wired or wireless means, which is used to output printing data of the printed image to printing system 1. 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 2 This 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. Furthermore, in Figure 2The example given is that 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 staggered pattern. However, this arrangement is merely for increasing ejection density; the nozzle rows and chip units can be arranged in one row or more than three rows. Furthermore, in... Figure 2 While examples of white, blue-green, magenta, black, and yellow inks are listed as colored inks, the colors used and their quantities are not limited to these. Furthermore, the order in which each color of the colored ink is arranged is not limited. Figure 2 the order shown in the example.

[0056] Next, use Figures 3 to 5 An example of an adjustment pattern printed in the printing system 1 and the detection of the adjustment pattern by the detection unit 70 will be described. Figure 3 A schematic diagram illustrating an example of this adjustment pattern. Figure 4 To indicate Figure 3 The diagram shows a cross-section at the position indicated by the single-dot grid line in the adjustment pattern, i.e., the cross-section in the reading direction. Figure 5 To indicate the use of the detection unit 70 for Figure 3 and Figure 4 The diagram shows a scenario where the pattern is adjusted for detection.

[0057] When the control unit 10 prints the adjustment pattern as described above onto the substrate 100, which serves as the medium, it performs the following control.

[0058] First, the control unit 10 controls the printing unit 50 in a manner that forms the base layer 82 with colored ink. Additionally, in Figure 3 In the diagram, the blank arrow marks indicate the reading direction, i.e., the scanning direction, which is the direction of reading performed afterward in the detection unit 70. However, the reading direction can also be the opposite direction. The colored ink can be any color ink or multiple colors of ink. At this time, the control unit 10 can also control the printing unit 50 in such a way that, at a position separated from the spray position of the transparent ink (described later), a grid line 81 is formed by a colored ink of the same color for reference, parallel to the grid line formed by the transparent ink. The grid line 81 is used, for example, to obtain the spray position of the transparent grid line 83 based on its relative position to the transparent grid line 83. The spacing of the grid line 81 is not limited to... Figure 3 The spacing is as shown, and the positions configured in the X direction are not limited to the transparent grid lines 83.

[0059] Next, the control unit 10 controls the printing unit 50 in such a way that transparent ink forms grid lines 83 with a length component in the reading direction at the position overlapping with the substrate layer 82. The grid lines 83 formed here will be referred to as transparent grid lines 83.

[0060] Furthermore, in this application specification, "grid line" refers to a dashed line formed by line segments of predetermined length or by intervals between multiple line segments. The size of each of the multiple line segments and intervals is only required to allow the line segments and intervals to be combined and identified as a dashed line. Moreover, the size of each line segment and interval does not necessarily have to be fixed within the dashed line as it is with single-point grid lines.

[0061] Furthermore, the "length component" in this application 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, the intention being to make the length formed by the combination of the line segments constituting the dashed line and the intervals such that the direction of the longer side is approximately parallel to the reading direction.

[0062] Here, as Figure 4 As illustrated, the transparent grid lines 83 formed using transparent ink are dashed grid lines that are repeatedly formed in the reading direction by structures 83s with an upwardly convex arc-shaped cross-section. Furthermore, the aforementioned cross-section refers to the cross-section in the reading direction. Additionally, in Figure 4 and Figure 5 In the text, the hollow arrow mark also indicates the reading direction.

[0063] exist Figure 4 Although examples of repeatedly configured structures 83s with a semi-circular cross-sectional shape are given, their shapes are not limited to this. For example, each repeatedly configured structure 83s can be a structure with a circular arc cross-sectional shape, or it can be a structure with a portion of a non-circular arc that approximates an ellipse cross-sectional shape.

[0064] In addition, although Figure 4 The example given is a dashed line shape with a fixed interval, formed by using transparent ink to create a transparent grid line 83, which has multiple ejection areas in the reading direction. However, the interval can also be non-fixed and is not limited. Furthermore, the transparent grid line 83 is not limited to a dashed line shape. In the above description, as various examples have been given, the transparent grid line 83 can be any grid line that forms multiple arc-shaped structures with an upwardly convex surface shape in the reading direction.

[0065] The detection of such transparent grid lines 83 by the detection unit 70 will be described. The detection unit 70 may include, for example, an irradiation unit for irradiating light and a light-receiving unit for receiving the reflected light reflected from the grid lines. Furthermore, the irradiation unit... Figure 4 as well as Figure 5 As illustrated by multiple arrows, light is incident on the substrate 100 with the transparent grid lines 83 from an angle that is not directly above it. In other words, light is incident on the substrate 100 with the transparent grid lines 83 at an angle that is not 0°.

[0066] If the transparent grid line 83 receives illumination light from the detection unit 70 in this manner, the intensity of reflected light in the light-receiving part will differ depending on the shape of the structure 83s, thus preventing it from becoming fixed. Therefore, such a transparent grid line 83 can be detected by the detection unit 70 as a grid line. Specifically, this is because when light is incident at an angle other than 0° relative to the substrate 100 where the transparent grid line 83 is formed, the intensity of reflected light will differ between the light reflected from the surface of the structure 83s and the light transmitted and reflected on the substrate. If the incident angle is set to 0° and light reflection occurs, almost no light is reflected from the surface of the structure 83s, resulting in the detection of light reflected from the substrate, thus degrading the accuracy of the detection.

[0067] Of course, the transparent grid line 83 does not need to be detected as a dashed line by the detection unit 70; it can function as an adjustment pattern even if some or all of it is detected as a straight line. Furthermore, the thickness of the transparent grid line 83 is not particularly limited, as long as it is a thickness that functions as an adjustment pattern for adjusting the spray position.

[0068] In addition, Figure 4 The example given is a transparent grid line 83 formed by separating at least a portion of adjacent structures 83s from each other in the reading direction. However, even if all adjacent structures 83s are eventually connected to form the transparent grid line 83, it is sufficient as long as it has an upwardly convex structure. Even in such a case, the detection unit 70 can detect part or all of the transparent grid line 83 as a straight line.

[0069] As can be seen from the above description, according to this embodiment, it is possible to detect the adjustment pattern for adjusting the landing position of transparent ink on the substrate 100 without spending extra effort and cost on preparing a substrate with unevenness or the like for adjustment.

[0070] In addition, Figures 3 to 5The example given is that the adjustment pattern only contains transparent grid lines 83 in the Y direction, which are difficult to detect in the reading direction. However, even if transparent grid lines composed of straight lines in the X direction are also included, the detection unit 70 can detect both transparent grid lines.

[0071] In addition, such as Figure 1 As illustrated, the detection unit 70 can be an in-line sensor, i.e., it is positioned 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 positioned at a location where the printed material 1000 after printing by the print head can be detected. The detection unit 70 can, for example, be a line sensor with a sensor group arranged in a direction perpendicular to the transport path.

[0072] also, Figure 1 The illustrated printing system 1 is a system in which a printhead is mounted as part of a line printing apparatus. 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 printing apparatus, since the detection unit 70 can be positioned on the transport path of the substrate 100, detection can be performed in a shorter time compared to cases where this is not the case.

[0073] Furthermore, by setting the color of the substrate layer 82 to a dark color, the detection unit 70 can more easily distinguish and detect the difference between areas where transparent ink has been sprayed and areas where no transparent ink has been sprayed, compared to cases where this is not the case. Therefore, the detection accuracy of the transparent grid lines 83 relative to the substrate layer 82 can be improved. For example, the color of the substrate layer 82 can be set to black.

[0074] Next, to supplement the effects based on this implementation method, we will use... Figures 6 to 8 The comparative examples will be explained. Figure 6 This is a schematic diagram illustrating the adjustment pattern printed in the printing system involved in the comparative example. Figure 7 To indicate Figure 6 The diagram shows a cross-section at the position indicated by the single-dot grid line in the adjustment pattern. Figure 8 To illustrate the use of the detection unit of the printing system involved in the comparative example to... Figure 6 and Figure 7 This is a schematic diagram illustrating the detection process using an adjusted pattern. Additionally, in... Figures 6 to 8 In the text, the hollow arrow mark also indicates the reading direction.

[0075] In the comparative example, as well as Figure 6As shown, printing is performed by forming a base layer 92 with colored ink. At this time, printing can also be performed in the following manner: similar to grid lines 81, at a position separated from the spray position of the transparent ink described later, grid lines 91 are formed by colored ink of the same color for reference, in a manner parallel to the grid lines formed by the transparent ink.

[0076] Furthermore, in the comparative example, printing was performed by forming straight grid lines 93 extending in the reading direction at the location where transparent ink overlaps with the substrate layer 92. These grid lines 93 will be referred to as transparent grid lines 93. Unlike transparent grid lines 83, transparent grid lines 93 are connected in a straight line. That is, as shown... Figure 7 As illustrated, the transparent grid line 93 is a grid line whose surface shape becomes flat in the reading direction.

[0077] The same detection performed by detection unit 70a as that of the detection unit 70 with such transparent grid lines 83 will be described. The irradiation section of detection unit 70a is as follows: Figure 7 as well as Figure 8 As schematically indicated by multiple arrows, light is incident from an angle not directly above the substrate on which the transparent grid lines 93 are formed. However, unlike the transparent grid lines 83, the transparent grid lines 93, even when illuminated by the detection unit 70a, have a flat surface, so the reflected light received by the light-receiving part remains constant, thus no difference occurs in the reading direction. Therefore, such transparent grid lines 93 are difficult for the detection unit 70a to detect as grid lines. Thus, in the comparative example, when an adjustment pattern for adjusting the spray position relative to a commonly used substrate 100 is printed using a transparent ink that is cured by UV light, the detection accuracy is poor, making it difficult to accurately obtain the spray position.

[0078] In contrast, in this embodiment, since the adjustment pattern includes transparent grid lines 83 with height differences in the reading direction as described above, detection can be performed without incurring additional effort and cost for adjustment, such as preparing a substrate with uneven surfaces.

[0079] Next, use Figure 9 A brief explanation is given of an example of the spray position adjustment method, including the printing method in printing system 1. Figure 9 This is a flowchart illustrating an example of a spray position adjustment method for a printing method in printing system 1.

[0080] 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 transparent ink onto the substrate 100; and an adjustment process for adjusting the spray position according to the printed adjustment pattern.

[0081] First, the control unit 10 of the printing system 1 controls the print head exemplified by the printing unit 50 by forming a base layer with colored ink (step S1). Next, the control unit 10 controls the print head by forming transparent grid lines with a length component in a first direction at the position overlapping with the base layer with transparent ink (step S2). The first direction mentioned above is in... Figures 3 to 5 The middle finger points in the Y direction. As described above, this transparent grid is a grid with multiple structures whose cross-sectional surface shape is an upwardly convex arc shape formed in the reading direction. Figures 3 to 5 The example is illustrated using transparent grid lines 83.

[0082] Next, by controlling the detection unit 70 with the control unit 10, the detection unit 70 moves relative to the printing result along the reading direction with the first direction as the reading direction, and optically reads and detects the printing result of the adjustment pattern onto the medium (step S3).

[0083] Finally, the control unit 10 adjusts the spraying position of the transparent ink based on the detection result of the adjustment pattern including the transparent grid lines detected by the detection unit 70 (step S4), and ends the process.

[0084] The adjustment of the spray position in step S4 can be implemented using existing technology. This adjustment will be briefly explained. For example, if the detected transparent 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 transparent grid line. For example, if the detected transparent 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 the timing to eliminate the shift.

[0085] Furthermore, such adjustments can be implemented by including a colored baseline, as illustrated by grid line 81, in the adjustment pattern, and eliminating the offset based on the offset of the transparent grid line from the baseline.

[0086] Furthermore, as described above, by pre-printing not only the transparent grid lines 83 in the Y direction but also the transparent grid lines in the X direction, the control unit 10 can adjust the landing positions in both the X and Y directions based on the detection results of the transparent grid lines in both directions performed by the detection unit 70. As described above, Figures 3 to 5 The transparent grid lines in the X direction mentioned above do not need to be repeating grid lines with a structured 83s; they can be simple straight lines.

[0087] Other application examples Furthermore, the present invention is not limited to the embodiments described above, and can be appropriately modified without departing from the spirit of the invention. For example, the UV irradiator for formal curing can be used as long as it can provide UV irradiation with a stronger intensity than the UV irradiator for pre-curing. Additionally, the curing of the ink is not limited to the example of curing UV ink by irradiating it with UV light; it can also be cured by heating thermosetting inks. Furthermore, 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.

[0088] Furthermore, while 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. Additionally, the detection unit 70 exemplified is not limited to examples located along the path of the transport medium; it can also be located in 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 matter on a document tray or an automatic document transport device and scan it to detect the adjustment pattern.

[0089] Furthermore, although this embodiment describes the case where the base layer is formed by a colored and curable liquid, i.e., colored ink, the base layer does not necessarily need to be formed by a curable ink. This point is added. The detection unit 70 receives reflected light from the irradiation unit and reflected by the structure 83s via a light-receiving unit to detect the surface state of the structure 83s. At this time, due to the shape of the structure 83s, the reflected light is not constant. Specifically, part of the irradiation light is reflected on the surface of the structure 83s, and part passes through the structure 83s and is reflected on the base layer. Due to this difference in path, the intensity of light received by the detection unit 70 will vary, resulting in areas where the base layer appears darker and areas where it appears thinner. In other words, regardless of whether the base layer is curable, the detection unit 70 can detect the position of the transparent grid lines 83 by forming the structure 83s on a colored base. Moreover, if the medium itself is colored, it is not necessary to form the base layer by spraying ink.

[0090] 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 in 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 via 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.

[0091] 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.

[0092] 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 section; 51, 51b, 51c, 51m, 51y, 51w, 52…Recording head; 61, 61b, 61c, 61m, 61w, 62, 63…UV irradiator; 70, 70a…Detection section; 81…Grid line; 82…Base layer; 83…Transparent grid line; 91…Grid line; 92…Base layer; 93…Transparent grid line; 100…Substrate; 1000…Printed material.

Claims

1. A printing system comprising: A printhead capable of spraying transparent ink and colored ink onto a medium, wherein the transparent ink is a colorless liquid with curable properties, and the colored ink is a colored liquid; A control unit that controls the ejection of the transparent ink and the colored ink by the printhead; The detection unit, while moving relative to the printing result along the reading direction, optically reads and detects the printing result of at least the adjustment pattern used to adjust the spraying position of the transparent ink on the medium. When the adjustment pattern is printed onto the medium, the control unit controls the print head by forming grid lines with a length component in the reading direction at the position where the transparent ink overlaps with the substrate layer. The grid line is a grid line formed in the reading direction by multiple structures with an upwardly convex arc shape on their cross-section.

2. The printing system as claimed in claim 1, wherein, The grid is formed by separating at least a portion of the adjacent structures in the reading direction.

3. The printing system as described in claim 1 or 2, wherein, The detection unit includes an irradiation unit and a light-receiving unit. The irradiation unit irradiates light, and the light-receiving unit receives reflected light that has been reflected off the grid lines. The irradiation section directs light into the medium on which the grid lines are formed at an angle not equal to 0°.

4. The printing system as claimed in claim 1 or 2, wherein, The detection unit is positioned on the path through which the medium is transported.

5. The printing system as claimed in claim 1 or 2, wherein, The base layer is a dark color.

6. The printing system of claim 5, wherein, The base layer is black.

7. 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.

8. A printing method comprising a printing system for printing an adjustment pattern, the printing system comprising a print head capable of ejecting transparent ink and colored ink onto a medium, the adjustment pattern being used at least to adjust the ejection position of the transparent ink on the medium, the transparent ink being a colorless and curable liquid, and the colored ink being a colored liquid. In the printing method, the print head is controlled in such a way that the transparent ink forms grid lines with a length component in a first direction at the location overlapping with the substrate layer. While setting the first direction as the reading direction and moving relative to the printing result along the reading direction, the printing result of the adjusted pattern is optically read and detected. The grid line is a grid line formed in the reading direction by multiple structures with an upwardly convex arc shape on their cross-section.

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