Inkjet printing method and inkjet printing device

Abstract

To provide an inkjet printing method and an inkjet printing device which can reduce or suppress accidental streaky defect corresponding to a moving direction of a printing head.SOLUTION: An inkjet printing method according to one embodiment described in the disclosure, which prints an image on a printing medium by a scanning method, includes steps of: extracting one or a plurality of image constituting portions from image data on images; sequentially feeding printing media in n-times at a predetermined interval in a sub-scanning direction, where a direction of a nozzle row in a printing head having the nozzle row in which a plurality of nozzles are arranged is defined as the sub-scanning direction, and a direction which is nearly perpendicular to the sub-scanning direction is defined as a main-scanning direction; and making the printing head scan over a printing path area in the main-scanning direction, in accordance with the number of times in which the printing media are fed out, where when the image constituting portions exist in a scannable printing path area where the printing head passes on the printing media and when the whole of the image constituting portions exist in the printing path area, the printing head prints the whole of the image constituting portions by discharging ink in the scanning.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to an inkjet printing method and an inkjet printing apparatus. [Background technology]

[0002] In recent years, various inkjet printing methods and inkjet printing devices have been developed.

[0003] Patent Document 1 (JP 2011-240530 A) describes a gloss forming process in which an ultraviolet-curable ink is ejected onto a recording medium to form a glossy region on the outermost layer, and the gloss forming process is carried out by setting the dot diameter of the ultraviolet-curable ink on the outermost layer to 2 times the distance between the centers of adjacent dots of the ultraviolet-curable ink. 1 / 2 The ink-jet recording method is a step of forming the glossy region in at least a partial region of the recording medium, the glossy region being a distance equal to or greater than twice the distance of the ink-jet recording medium.

[0004] Patent Document 2 (JP 2006-015691 A) describes a printing method using an inkjet printer that uses UV-curable ink, in which a picture and / or letters consisting of an arrangement of multiple UV-curable ink dots is printed on the surface of a recording medium using an inkjet printer that uses UV-curable ink, and then the media surface on which the picture and / or letters have been printed is covered with a clear coat layer made of a transparent or translucent clear ink whose main component is a resin that has the same refractive index as, or is approximately the same within an error range of ±0.5, as the resin that is the main component of the ink contained in the multiple UV-curable ink dots.

[0005] Patent Document 3 (JP 2021-062531 A) describes an inkjet printing method for forming a decorative printing layer having a three-dimensional texture on a printed surface, the inkjet printing method including a step of printing dots of a curable ink that cures under predetermined conditions based on dot pattern data indicating the printing positions of the printed dots on the printed surface, and a step of curing the printed dots, wherein the dot pattern data indicates that in a first region, the distance between adjacent dots is a distance at which the adjacent dots before curing can be maintained independently without bonding to each other, and that in a second region different from the first region, the distance between adjacent dots is a distance at which the adjacent dots before curing will bond to each other. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2011-240530 A [Patent Document 2] JP 2006-015691 A [Patent Document 3] Patent Publication No. 2021-062531 Summary of the Invention [Problem to be solved by the invention]

[0007] In conventional inkjet printing methods that print images on print media using a scanning method, the print media is fed at a predetermined interval, and then the print head scans it as it passes through the print pass area. At this time, if the image to be printed is present within the print pass area, even if only a portion of the image is present within the print pass area, that portion of the image is printed during the scan.

[0008] For example, as shown in Fig. 1, in scan 1, part of component 1 of an image is present within printing pass area 1. In this case, part of component 1 within printing pass area 1 is printed by scan 1, and then all of component 1 and part of component 2 within printing pass area 2 are printed by subsequent scan 2. With such a conventional printing method, as shown in Fig. 1, there are cases where unintended streak-like defects occur in the image that correspond to the movement direction of the print head.

[0009] The present disclosure provides an inkjet printing method and inkjet printing apparatus that can reduce or suppress unintended streaking defects corresponding to the direction of print head movement. [Means for solving the problem]

[0010] According to one embodiment of the present disclosure, there is provided an inkjet printing method for printing an image on a print medium by a scanning method, comprising the steps of: Extracting one or more image components from image data of the image; When the direction of the nozzle row in a print head having a nozzle row in which a plurality of nozzles are arranged is defined as the sub-scanning direction and the direction approximately perpendicular to the sub-scanning direction is defined as the main scanning direction, the print medium is sequentially fed n times at predetermined intervals in the sub-scanning direction, and the print head scans over a printing pass area in the main scanning direction corresponding to the number of times the print medium has been fed, An inkjet printing method is provided that includes scanning, where when an image component is present in a scannable printing path area where a print head passes over a printing medium, if the entire image component is present within the printing path area, ink is ejected in the scan to print the entire image component.

[0011] According to another embodiment of the present disclosure, there is provided an inkjet printing device for printing an image on a print medium in a scanning manner, comprising: A print head having a nozzle row in which a plurality of nozzles are arranged; a feed unit that sequentially feeds the print medium n times at predetermined intervals in the sub-scanning direction, where the direction of the nozzle row in the print head is the sub-scanning direction and the direction substantially perpendicular to the sub-scanning direction is the main scanning direction; A receiving unit that receives a signal of one or more image components extracted from image data of the image; A scan control unit that scans the print head in a main scanning direction across a print path area in response to the number of times the print medium has been fed by the feed unit, An inkjet printing device is provided which is equipped with a scan control unit which, when a component of an image received by the receiving unit is present in a scannable printing path area where a print head passes over a printing medium, causes ink to be ejected during scanning to print the entire component of the image if the entire component of the image is present within the printing path area. Effect of the Invention

[0012] According to the present disclosure, it is possible to provide an inkjet printing method and inkjet printing apparatus that can reduce or suppress unintended streak defects that correspond to the movement direction of the print head.

[0013] The above description should not be considered as a disclosure of all embodiments of the present invention and all advantages associated with the present invention. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram of an image obtained when scanning and printing using a conventional scan-type inkjet printing method and printing device. [Diagram 2] FIG. 2 is a schematic diagram of an image obtained when scanning and printing using the scan-type inkjet printing method and printing apparatus according to one embodiment of the present disclosure. [Diagram 3] FIG. 3 is a schematic diagram of a print head. [Figure 4]FIG. 4(a) is a photograph of an image printed using a conventional scan-type inkjet printing method and printing device, and FIG. 4(b) is a photograph of an image printed using a scan-type inkjet printing method and printing device according to one embodiment of the present disclosure. [Diagram 5] FIG. 5 is a flow chart illustrating the contents of an inkjet printing method according to one embodiment of the present disclosure. [Figure 6] FIG. 6 is a schematic diagram of an image printed using an inkjet printing method according to an embodiment of the present disclosure, and is a schematic diagram of a printing method configured to randomly print components of an image in each printing pass area. [Figure 7] FIG. 7 is a diagram showing image components extracted from image data by the blob labeling method. [Figure 8] Figure 8 is a diagram showing how to extract components of an image from image data, where Figure 8(a) is a diagram showing the results when components of an image are extracted from image data using the blob labeling method, and Figure 8(b) is a diagram showing the results when a pre-specified area is extracted from image data. [Figure 9] FIG. 9 is a diagram showing image components extracted from image data by an edge detection method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, for the purpose of illustrating typical embodiments of the present invention, a more detailed description will be given with reference to the drawings as necessary, but the present invention is not limited to these embodiments.

[0016] In this disclosure, "constituent part of an image" refers to one or more parts of an image printed on a print medium that can be identified as a single unit. For example, in FIG. 7, the image on the left side to be printed on a print medium can be divided into 12 image blocks as shown on the right side, and each of these 12 divided images corresponds to a constituent part of the image. Here, a "constituent part" can also be called a "chunk."

[0017] In the present disclosure, the term "printing pass area" refers to an area where the print head can pass over the printing medium and print. For example, according to FIG. 1, the print head can move in the main scanning direction, and in scan 1, the area indicated by the number 1 above the feeding direction of the printing medium corresponds to the printing pass area, and in scan 2, the area indicated by the number 2 on the printing medium corresponds to the printing pass area. Here, the term "main scanning direction" refers to the direction of the nozzle row in a print head having a nozzle row in which multiple nozzles are arranged as shown in FIG. 3, or, when the feeding direction of the printing medium (±y direction) as shown in FIG. 1 is taken as the sub-scanning direction, the direction approximately perpendicular to this sub-scanning direction (for example, the ±x direction in FIG. 1).

[0018] In this disclosure, the term "approximately" means that it includes variations that occur due to manufacturing errors and the like, and means that a variation of about ±20% is permitted.

[0019] In the present disclosure, "scan" refers to an operation of ejecting or not ejecting ink when the print head moves. For example, according to FIG. 2, in scan 1, the print head may move in the main scanning direction, but does not eject ink. On the other hand, in scan 2, the print head may eject ink onto the location of component 1 while moving in the main scanning direction, but does not eject ink onto the location of component 2. Note that, for example, in the case of scan 1 in FIG. 2, when it is not necessary to eject ink at all, scan 1 may be skipped, that is, the print head may not need to move in scan 1. Such an operation of skipping a scan is also included in the "scan" of the present disclosure.

[0020] In this disclosure, "three-dimensional printing" refers to a printing method in which components of an image are printed to be raised to a predetermined height from the printing medium. In this disclosure, "three-dimensional printing" generally includes printing methods called 2.5-dimensional printing and 3-dimensional printing.

[0021] In the present disclosure, "glossy printing" refers to a printing method in which a component of an image is printed so as to have gloss. Here, the gloss can be evaluated, for example, by the average value of the 60-degree glossiness at any three points measured using a portable glossmeter GMX-202 manufactured by Murakami Color Research Institute in accordance with JIS Z8741. The 60-degree glossiness can be, for example, 30 or more, 40 or more, 50 or more, or 60 or more, and can be 100 or less, or less than 100.

[0022] In the present disclosure, "transparent" refers to an average transmittance of about 80% or more, preferably about 85% or more, or about 90% or more, in the visible light region (wavelength 400 nm to 700 nm) measured in accordance with JIS K 7375. There is no particular limit to the upper limit of the average transmittance, but it can be, for example, less than about 100%, about 99% or less, or about 98% or less.

[0023] In the present disclosure, the term "semi-transparent" refers to an average transmittance in the visible light region (wavelength 400 nm to 700 nm) measured in accordance with JIS K 7375 of less than about 80%, desirably about 75% or less, and is intended to not completely conceal the base.

[0024] Hereinafter, the inkjet printing method and inkjet printing apparatus of the present disclosure will be described with reference to the drawings as necessary. In the present disclosure, the inkjet printing method and inkjet printing apparatus may be simply referred to as a "printing method" and a "printing apparatus".

[0025] The inkjet printing method disclosed herein is a method for printing an image on a print medium by a scanning method, and includes at least the following steps (1) and (2): (1) A process of extracting one or more components of an image from image data of the image (sometimes simply referred to as an "extraction process"). (2) a step of sequentially feeding a print medium n times at predetermined intervals in a print head having a nozzle row in which a plurality of nozzles are arranged, where the direction of the nozzle row is defined as a sub-scanning direction and a direction substantially perpendicular to the sub-scanning direction is defined as a main scanning direction, and the print head scans a printing pass area in the main scanning direction corresponding to the number of times the print medium has been fed, A scanning process (sometimes simply referred to as the "scanning process") in which, when an image component is present in a scannable printing path area where the print head passes over the printing medium, and the entire image component is present within the printing path area, ink is ejected during scanning to print the entire image component.

[0026] Here, according to the flowchart of Fig. 5, the above-mentioned extraction process corresponds to step S100, and the above-mentioned scanning process corresponds to steps S110 to S150. "k" in component k of the flowchart refers to the number of the extracted component (e.g., "1" in component 1 of Fig. 1, etc.), and "i" in scan i of the flowchart refers to the number of the scan (e.g., "1" in scan 1 of Fig. 1, etc.).

[0027] In a conventional inkjet printing method, for example, as shown in Fig. 1, when part of component 1 of an image is present within printing pass area 1, scan 1 prints part of component 1 within printing pass area 1, and the subsequent scan 2 prints all of component 1 and part of component 2 within printing pass area 2. As a result, as shown in Fig. 1, unintended streak-like defects (sometimes called "banding") that correspond to the movement direction of the print head tend to occur in the image to be printed.

[0028] On the other hand, in the inkjet printing method of the present disclosure, even if an image to be printed exists within the printing pass area during scanning, if a portion of the image cannot be printed in one scan, the portion of the image is not printed, and the entire portion of the image is printed during a scan that can be printed in one go. As a result, the printing method of the present disclosure can suitably improve the defect of unintended streaks in the image to be printed that correspond to the movement direction of the print head.

[0029] The inkjet printing method of the present disclosure is a method for printing an image on a print medium by a scanning method. In this disclosure, the term "scanning method" includes a single-pass method in which the print head is fixed and the print medium is moved to print in one pass, and a multi-pass method in which the print head is moved back and forth to print as shown in Figures 1 and 2. In particular, it is advantageous to employ the inkjet printing method of the present disclosure for the multi-pass method, which is prone to banding.

[0030] There is no particular limit to the material of the printing medium that can be used in the printing method and printing device of the present disclosure, and examples thereof include paper, resin, inorganic materials (e.g., glass, ceramics), metal, and wood. The shape of the printing medium is not limited to a substantially flat shape such as a film, fabric, or board, but may also be a three-dimensional shape having an uneven surface such as a building material (e.g., siding material). An ink receiving layer may be provided on the ink application surface of the printing medium. There is no particular limit to the thickness of the printing medium, and it can be set appropriately depending on the intended use, etc. Here, the "film" in this disclosure also includes a member called a "sheet."

[0031] Inks that can be used in the printing method and printing device of the present disclosure are not particularly limited, and examples thereof include transparent ink, semi-transparent ink, and opaque ink. The transparent ink and semi-transparent ink may be colorless or colored. For colored transparent ink, semi-transparent ink, and opaque ink, typically, colored ink can be used. Examples of colored inks include CMYK inks (cyan ink, magenta ink, yellow ink, and black ink), light cyan ink, light magenta ink, red ink, green ink, and orange ink.

[0032] As the ink, a curable ink can be used. Examples of the curable ink include radiation curable ink and heat curable ink. The curable ink can be cured before the ejected ink spreads on the printing medium, and therefore can be suitably used in three-dimensional printing and the like. Examples of the radiation curable ink include a composition containing a (meth)acrylic monomer and a photopolymerization initiator. Here, in the present disclosure, "(meth)acrylic" means acrylic or methacrylic.

[0033] The print head can be equipped with one or more inks. When the print head is equipped with multiple inks, at least one of the inks can be ejected according to the printing method of the present disclosure. For example, when the print head is equipped with two types of ink, a transparent ink and a colored ink, only the transparent ink or only the colored ink can be ejected according to the printing method of the present disclosure, or both the transparent ink and the colored ink can be ejected according to the printing method of the present disclosure.

[0034] The printing carried out by the printing method of the present disclosure is not particularly limited, and may be at least one selected from the group consisting of two-dimensional printing, three-dimensional printing, and glossy printing. Three-dimensional printing and glossy printing are printing methods that require high expressiveness, and in the case of such printing methods, streaky defects have a large impact. The inkjet printing method of the present disclosure can reduce or suppress such defects even in glossy printing and three-dimensional printing, which are prone to streaky defects (banding) or are easily noticeable.

[0035] The method for extracting components of an image in the extraction step of the present disclosure is not particularly limited, and may include, for example, at least one method selected from the group consisting of a blob labeling method, an edge detection method, a threshold method, and a method for extracting a pre-specified area.

[0036] In the extraction step of the present disclosure, a known blob labeling method can be adopted. The blob labeling method is a method of assigning the same number to pixels with continuous white parts (or black parts) in a binarized image (sometimes referred to as "labeling"), and identifying the image as one or more components. There are two types of processing in the blob labeling method: 4-linked (sometimes referred to as "4-neighborhood"), which labels parts that are continuous vertically and horizontally in a binarized image as the same, and 8-linked (sometimes referred to as "8-neighborhood"), which labels parts that are continuous vertically, horizontally, and diagonally as the same. In the extraction step of the present disclosure, either 4-linked or 8-linked can be adopted, but 4-linked is preferred from the viewpoint of dividing the components (lumps) more finely. For example, image data such as those shown in Figures 7 and 8 can be processed using the blob labeling method, where in Figure 7, 12 components are extracted from the image data, and in Figure 8, 3 components are extracted from the image data, as shown in Figure 8(a).

[0037] In the extraction step of the present disclosure, a known edge detection method can also be adopted. The edge detection method is a method that employs an algorithm to identify a portion where the brightness of an image changes sharply, or more formally, a portion where the brightness of an image changes discontinuously. The edge detection method includes, for example, a search-based method and a method based on a zero-crossing method, and either method may be adopted in the extraction step of the present disclosure. For example, it is preferable to adopt the edge detection method for image data such as that shown in FIG. 9.

[0038] In the extraction process of the present disclosure, a known threshold method can also be adopted. The threshold method is a method in which the target image data is converted into only two colors, black and white, and the image is identified as one or more components from the result. For example, the image data shown in FIG. 7 can be processed by the blob labeling method, but it can also be processed by the threshold method.

[0039] In the extraction step of the present disclosure, a method of extracting a pre-specified area can also be adopted. In other words, in the printing method of the present disclosure, when a streak is intentionally formed in an image (for example, when a streak is formed as part of a design), the streak is intended to be permitted. Specifically, for example, in the case of image data of FIG. 8, according to the blob labeling method, three components are extracted as shown in FIG. 8(a), but as shown in FIG. 8(b), four components may be extracted by intentionally dividing the character on the left side into two. The pre-specified area can be specified, for example, by the creator of the image (for example, a designer), a printing operator (for example, an actual printing worker), AI (artificial intelligence), etc.

[0040] The method of extracting a pre-specified area can be suitably used when the length of a component part of an image is longer than the length of the nozzle row of a print head. Here, the term "component length" refers to the length (y) of the component part of an image in the sub-scanning direction (y direction) obtained by acquiring the maximum and minimum values ​​of the length in the sub-scanning direction (y direction) of the component part of an image, and the term "nozzle row length" refers to the length (y) from the highest point to the lowest point of the nozzles in the nozzle row in the sub-scanning direction (y direction) of a nozzle row in which multiple nozzles are lined up, as shown in FIG. 3.

[0041] In the printing method of the present disclosure, the length of the image components is preferably equal to or less than the length of the nozzle row of the print head. With such a length of the image components, unintended streaking defects corresponding to the movement direction of the print head can be further reduced or suppressed.

[0042] The scanning step of the present disclosure includes at least the step (2) described above. Here, the term "substantially perpendicular" in the present disclosure means that a variation of about ±20 degrees or less, about ±15 degrees or less, about ±10 degrees or less, about ±5 degrees or less, or about ±1 degree or less from the perpendicular (90 degrees) is acceptable.

[0043] There are no particular limitations on the interval and number of times the print medium is fed, and these can be set appropriately depending on, for example, the size of the print medium, the size of the image components, the size of the print head, etc. For example, the feed interval may be set to a constant interval as shown in Fig. 2, or may be different. The number of feeds, n, is an integer number, meaning one or more times.

[0044] Typically, the number of times the print medium is fed may correspond to the number of times the print head scans the print pass area in the main scanning direction. In the present disclosure, as described above, for example, in scan 1 of FIG. 2, when it is not necessary to eject ink at all, the print head may be skipped without moving in scan 1, and such a scan may also be counted as one scan.

[0045] In the scanning process of the present disclosure, when an image component is present in a scannable printing path area where the print head passes over the printing medium, if the entire image component is present within the printing path area, ink is ejected during scanning to print the entire image component. Here, "printing the entire image component" means substantially printing the entire image component. In other words, in addition to ejecting ink to print all pixels (dots) that constitute the image component, even if several pixels out of all pixels cannot be printed by ejecting ink due to nozzle clogging or the like, if the quality is acceptable (for example, if the entire image component after printing can be evaluated as being printed by visual observation), it can be said that the entire image component is printed in such a case.

[0046] The print head may pass through the print pass area at least once in one scan, but typically may pass through the print pass area twice (may make a round trip). For example, according to FIG. 2, the print head may pass through the print pass area in the -x direction and stop at the left end, or may pass through the print pass area in the -x direction and then in the +x direction and stop at the right end. When the print head moves through the print pass area multiple times in one scan, the entire image component may be printed during any one movement of the print head, and no printing may be performed during the remaining movements; the entire image component may be printed each time the print head passes through the print pass area; or a portion of the image component may be printed during any one movement of the print head, and the remainder of the image component may be printed during the remaining movements.

[0047] In some embodiments, the scanning step of the present disclosure is further performed such that when an image component is present in a scannable printing pass area where the print head passes over the printing medium, if the entire image component is not present within the printing pass area, ink is not discharged onto the image component. By employing such a scanning step, banding can be further improved. Here, "not discharging ink onto the image component" means that ink is not substantially discharged onto the image component. In other words, when a part of an image component is present within the printing pass area, other than not discharging ink onto all of the pixels (dots) constituting the component, for example, even if ink is discharged for several pixels due to some influence, if the quality is acceptable (for example, if it can be evaluated that ink is not discharged by visual observation), it can be said that ink is not discharged onto the image component in such a case.

[0048] In some embodiments, the scanning step of the present disclosure is further performed so that, when the entirety of the constituent part of the image can be printed by multiple scans, the entirety of the constituent part of the image is printed in at least one scan. Specifically, according to FIG. 2, for example, the constituent part 1 of the image can be printed by scans 2 to 4. In this case, the constituent part 1 may be printed in any one or any two of scans 2 to 4, or in all of scans 2 to 4. The number of times of printing can be appropriately set according to the printing quality of the constituent part, and the number of times of printing is preferably two or more. The print head generally has a nozzle row (y) in which multiple nozzles are arranged in the y direction as shown in FIG. 3, but, for example, some of the multiple nozzles may become clogged with use. Therefore, if printing is performed multiple times, even if there is a printing defect due to nozzle clogging during the first printing, during the subsequent printing, such a part is printed by a different nozzle of the print head, and as a result, the printing defect may be improved.

[0049] In some embodiments, the scanning step of the present disclosure is further performed such that, when a plurality of components of an image are entirely present within a scannable printing pass area and the components of the image are entirely present within a printing pass area of ​​a subsequent scan, the components of the image are individually and randomly printed in each scan. Specifically, according to FIG. 6, 12 components a to l are extracted from the image data. At this time, for example, four components a to d that are present within the same printing pass area can be printed entirely in scans 7 and 8. In this case, the four components may be printed at once in either scan 7 or 8, or, for example, as shown in FIG. 6, components b and c may be printed in scan 7, and components a and d may be printed in the subsequent scan 8. At this time, at least components a and d may be printed in scan 8, but components b and / or c may be printed in addition to components a and d. As shown in Figure 6, when multiple components are printed randomly, even if there is a printing defect due to nozzle clogging when printing scan 7, when the subsequent scan 8 is printed, it is printed with a nozzle of a print head other than the area where the nozzle clogging occurred, and as a result, printing defects can be reduced or improved compared to when all of the multiple components are printed in scan 7.

[0050] In some embodiments, the printing method of the present disclosure further includes a step of curing the ejected ink after printing (sometimes simply referred to as a "curing step"). When the curing step is employed, a curable ink is used as the ink. There are no particular limitations on the means for curing the curable ink, and for example, a means for irradiating radiation (ultraviolet rays, electron beams, etc.) and / or a heating means can be employed. The conditions for each of these means can be appropriately set depending on the type of curable ink used, etc.

[0051] The printing method of the present disclosure may optionally include one or more additional steps, such as unwinding the print medium, drying, detecting defects, winding the print, and the like.

[0052] The inkjet printing apparatus of the present disclosure is an apparatus capable of carrying out the inkjet printing method described above, and includes at least the following components (a) to (d). With regard to components other than the above components (e.g., a memory for storing various information for operating the apparatus, a display, etc.), known components used in conventional inkjet printing apparatuses can be appropriately adopted: (a) A print head having a nozzle row with multiple nozzles lined up. (b) a sending section that sequentially sends out the print medium n times at predetermined intervals in the sub-scanning direction, where the direction of the nozzle row in the print head is the sub-scanning direction and the direction approximately perpendicular to the sub-scanning direction is the main scanning direction. (c) a receiving unit for receiving a signal of one or more image components extracted from image data of the image; (d) a scan control unit that causes the print head to scan across the print path area in a main scanning direction in response to the number of times the print medium has been fed by the feed unit, A scan control unit that, when a component of an image received by the receiving unit is present in a scannable printing path area where a print head passes over a printing medium, and the entire component of the image is present within the printing path area, causes ink to be ejected during scanning to print the entire component of the image.

[0053] The print head used in the printing device of the present disclosure is not particularly limited, and a known print head can be used. In the printing device of the present disclosure, one or more print heads can be adopted. The print head generally has a nozzle row in which a plurality of nozzles are arranged, as shown in FIG. 3. For example, the nozzle row C (cyan) in FIG. 3 is not divided, but the nozzle row may be divided into two or more, and may be configured so that the ink ejection amount can be adjusted for each divided area. There are no particular limitations on the size, number, pitch interval, arrangement pattern, etc. of the nozzles, and they can be appropriately set according to the printing performance (e.g., print quality, print speed), etc.

[0054] The print head shown in FIG. 3 as an example has nozzle rows configured to eject C (cyan), M (magenta), Y (yellow) and K (black) inks, but the print head is not limited to such a configuration. For example, a nozzle row that ejects a transparent ink or a colored ink such as light cyan, light magenta, red, green and orange can also be used. The print head only needs to have one or more nozzle rows, and there is no particular limit to the number of nozzle rows. When the print head has multiple nozzle rows, the ink ejected from each nozzle row may be the same (for example, two nozzle rows are both nozzle rows for transparent ink) or different (for example, one of the two nozzle rows is a nozzle row for transparent ink and the other is a nozzle row for black ink). As the ink applicable to the print head, the ink in the printing method described above can be similarly used.

[0055] In the present disclosure, as shown in FIG. 3, the length from the highest point to the lowest point of the nozzles in the nozzle row is referred to as the nozzle row length. There is no particular limit to the nozzle row length, and it may be set appropriately depending on the size of the print medium or the printing device. The nozzle row length can generally be, for example, about 30 cm or less, about 20 cm or less, or about 10 cm or less, and can be about 1 cm or more, about 3 cm or more, or about 5 cm or more. It is advantageous for the length of the component part of the image received by the receiving unit described later to be equal to or less than the nozzle row length of the print head, since this can further reduce or suppress unintended streaky defects corresponding to the movement direction of the print head.

[0056] The printing device of the present disclosure includes a delivery unit that sequentially delivers the print medium n times at a predetermined interval in the sub-scanning direction (+y direction). There are no particular limitations on the delivery unit as long as it can perform the delivery operation in the printing method described above, and for example, a known delivery unit used in a conventional inkjet printing device can be used.

[0057] The printing device of the present disclosure includes a receiving unit that receives signals of one or more image components extracted from image data of an image. There are no particular limitations on the receiving unit as long as it is configured to receive signals of the extracted image components and provide information of the image components based on the received signals to a subsequent scan control unit, and for example, a known receiving unit that can receive image data used in conventional inkjet printing devices can be adopted. The receiving unit may be provided separately from the scan control unit in the printing device, or may be integrated with the scan control unit.

[0058] The signal of the image constructing section provided to the receiving section is obtained by performing an extraction process, which may be performed by at least one method selected from the group consisting of the above-mentioned blob labeling method, edge detection method, threshold method, and a method for extracting a pre-specified region.

[0059] The extraction process of the image constituent parts may be performed inside or outside the printing device. When the extraction process is performed inside the printing device, the extraction processing unit that performs the extraction process may be provided separately from the receiving unit described above, or may be integrated with the receiving unit. When the extraction process is performed outside the printing device, the extraction process may be performed using, for example, a personal computer, a tablet, a smartphone (mobile phone), a cloud system, or the like, whose system is constructed so that the extraction process can be performed. The signal of the image constituent parts obtained by the extraction process performed outside the printing device may be provided to the receiving unit via wire or wirelessly.

[0060] The printing device of the present disclosure includes a scan control unit that causes the print head to scan the printing path area in the main scanning direction in accordance with the number of times the print medium is fed by the feed unit. There are no particular limitations on the type of scan control unit as long as it can perform the scanning step in the printing method described above.

[0061] The scan control unit of the present disclosure can control the printing device so that when a component of an image received by the receiving unit is present in a printing pass area, and the entire component of the image is present within the printing pass area, ink is ejected during scanning to print the entire component of the image.

[0062] In some embodiments, the scan control unit of the present disclosure further controls the printing device so that, when a component of an image received by the receiving unit is present in a printing pass area, if the entirety of the component of the image is not present within the printing pass area, ink is not ejected onto the component of the image during scanning. By employing such a scan control unit, banding can be further improved.

[0063] In some embodiments, the scan control unit of the present disclosure further controls the printing device to print the entire image component in at least one scan when the entire image component can be printed in multiple scans. When printing is performed multiple times, even if there is a printing defect due to nozzle clogging in the first printing, in the next printing, such a part is printed by a different nozzle of the print head, and the printing defect can be improved.

[0064] In some embodiments, the scan control unit of the present disclosure further controls the printing device to print the entire image components individually and randomly in each scan when multiple components of the image are present in a scannable printing pass area and the entire components of the image are also present in the printing pass area of ​​a subsequent scan. For example, as shown in FIG. 6, if multiple components present in the same printing pass area are printed randomly, even if a printing defect due to nozzle clogging occurs during printing of scan 7, the nozzle of a print head different from the nozzle where the nozzle clogging occurred is printed during printing of the subsequent scan 8, and as a result, printing defects can be reduced or improved compared to when all of the multiple components are printed by scan 7.

[0065] In some embodiments, the printing device of the present disclosure further includes a curing unit that cures the ink ejected after printing. When the curing unit is employed, a curable ink is used as the ink. The curing unit may be provided separately from the scan control unit in the printing device, or may be integrated with the scan control unit.

[0066] The means for curing the curable ink in the curing section is not particularly limited, and for example, a means for irradiating radiation (ultraviolet rays, electron beams, etc.) and / or a heating means can be used. The conditions for each of these means can be appropriately set depending on the type of curable ink used, etc.

[0067] In some embodiments, the printing device of the present disclosure has a structure capable of moving at least one of the print medium and the print head in the z direction. Here, the "z direction" refers to a direction substantially perpendicular to the x direction and the y direction, respectively, and includes the +z direction and the -z direction. In other words, "capable of moving in the z direction" refers to the possibility of moving in either the +z direction or the -z direction. The "+z direction" and "-z direction" can be defined as the upward direction of the print medium and the downward direction of the print medium when the print medium is placed horizontally on the ground, for example, as the +z direction and the -z direction, respectively.

[0068] By adopting a structure that can be moved in the z direction, for example, during three-dimensional printing, it is possible to reduce or prevent contamination inside the device caused by ink that is ejected onto the printing medium and raised. In addition, when printing a three-dimensional printing medium having an uneven surface, if such a structure is adopted, the print quality can be improved compared to printing with a printing device that does not have such a structure. In three-dimensional printing, it is preferable to move the printing medium in the -z direction, and it is preferable to move the print head in the +z direction. Such movement may be a movement of a predetermined distance at once, or may be moved in stages. In printing a three-dimensional printing medium, it is preferable to move the printing medium and / or the print head in the +z direction and / or the -z direction according to the three-dimensional shape of the printing medium.

[0069] The printing apparatus of the present disclosure may optionally include one or more additional components, such as a print medium unwinding section, a drying section, a defect detection section, a print take-up section, and the like.

[0070] Fig. 4(a) is a photograph of an image printed using a conventional scan-type inkjet printing method and printing device, and Fig. 4(b) is a photograph of an image printed using the scan-type inkjet printing method and printing device of one embodiment of the present disclosure. As is clear from these photographs, when an image is printed using the scan-type inkjet printing method and printing device of the present disclosure, it is possible to suitably improve unintended streak-like defects (banding) that correspond to the movement direction of the print head.

[0071] It will be apparent to those skilled in the art that the above-described embodiments may be modified in various ways without departing from the basic principles of the present invention, and that various improvements and modifications of the present invention may be made without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0072] 1 Printing pass area (printing pass area of ​​scan 1) 2 Printing pass area (printing pass area of ​​scan 2)

Claims

1. An inkjet printing method for printing an image on a print medium by a scanning method, comprising: extracting one or more image features from image data of said image; a print head having a nozzle row in which a plurality of nozzles are arranged, the direction of the nozzle row being a sub-scanning direction, and a direction substantially perpendicular to the sub-scanning direction being a main scanning direction, the print medium is sequentially fed out n times at predetermined intervals in the sub-scanning direction, and the print head scans a printing pass area in the main scanning direction corresponding to the number of times the print medium has been fed out, When a constituent part of the image is present in a scannable printing pass area where the print head passes over the printing medium, if the entire constituent part of the image is present within the printing pass area, ink is ejected during scanning to print the entire constituent part of the image. said scanning; An inkjet printing method comprising:

2. 2. The printing method according to claim 1, wherein, in the scanning, when a component of the image is present in a scannable printing pass area where the print head passes over the printing medium, if the entire component of the image is not present within the printing pass area, ink is not ejected onto the component of the image.

3. 3. The printing method according to claim 1, wherein, in the scanning, when the entire constituent portion of the image can be printed by a plurality of scans, the entire constituent portion of the image is printed in at least one scan.

4. The printing method according to any one of claims 1 to 3, wherein in the scanning, if a plurality of components of the image are entirely present within a scannable printing pass area and the entire components of the image are also entirely present within a printing pass area of ​​a subsequent scan, the entire components of the image are individually printed randomly in each scan.

5. The printing method according to any one of claims 1 to 4, wherein the extraction of the constituent parts of the image is performed by at least one method selected from the group consisting of a blob labeling method, an edge detection method, a threshold method, and a method for extracting a pre-specified area.

6. The printing method according to any one of claims 1 to 5, further comprising obtaining maximum and minimum values ​​of the length of the constituent part of the image in the sub-scanning direction, and determining a length of the constituent part of the image in the sub-scanning direction derived from the maximum and minimum values, the length being equal to or less than a nozzle row length in the sub-scanning direction of a nozzle row of the print head.

7. 7. The printing method according to claim 1, wherein the ink is a curable ink, and the method further comprises curing the ejected ink after printing.

8. The printing method according to any one of claims 1 to 7, wherein the printing is performed by at least one method selected from the group consisting of two-dimensional printing, stereoscopic printing, and glossy printing.

9. An inkjet printing device that prints an image on a print medium by a scanning method, A print head having a nozzle row in which a plurality of nozzles are arranged; a feed unit that sequentially feeds the print medium n times at predetermined intervals in the sub-scanning direction, where the direction of the nozzle row in the print head is a sub-scanning direction and a direction substantially perpendicular to the sub-scanning direction is a main scanning direction; a receiving unit for receiving a signal of one or more components of the image extracted from image data of the image; a scan control unit that causes the print head to scan across a print path area in a main scanning direction in response to the number of times the print medium has been fed by the feed unit, When a constituent portion of an image received by the receiving unit is present in a scannable printing path area where the print head passes over the printing medium, if the entire constituent portion of the image is present within the printing path area, ink is ejected during scanning to print the entire constituent portion of the image. The scan control unit; An inkjet printing apparatus comprising:

10. The printing device according to claim 9, wherein the scan control unit executes scanning such that when a component of an image received by the receiving unit is present in a scannable printing path area where the print head passes over the printing medium, and the entire component of the image is not present within the printing path area, ink is not ejected from the component of the image during scanning.

11. 11. The printing device according to claim 9, wherein, when the entire constituent part of the image can be printed by multiple scans, the scan control unit executes the printing so as to print the entire constituent part of the image in at least one scan.

12. A printing device according to any one of claims 9 to 11, wherein when multiple components of the image are present in their entirety within a scannable printing pass area and the entire components of the image are also present in the printing pass area of ​​a subsequent scan, the scan control unit executes the printing of the entire components of the image individually and randomly in each scan.

13. The printing device according to any one of claims 9 to 12, wherein the process of extracting the constituent parts of the image is performed inside or outside the printing device.

14. The printing device according to any one of claims 9 to 13, wherein the extraction process of the constituent parts of the image is performed by at least one method selected from the group consisting of a blob labeling method, an edge detection method, a threshold method, and a method for extracting a pre-specified area.

15. A printing device according to any one of claims 9 to 14, wherein a maximum value and a minimum value of a length in a sub-scanning direction of a constituent part of an image received by the receiving unit are obtained, and a component length in the sub-scanning direction of the constituent part of the image derived from the maximum value and the minimum value is equal to or less than a nozzle row length in the sub-scanning direction of a nozzle row of the print head.

16. 16. The printing device according to claim 9, wherein the ink is a curable ink, and further comprising a curing unit that cures the ink ejected after printing.

17. The printing device according to any one of claims 9 to 16, further comprising a structure capable of moving at least one of the printing medium and the print head in the z direction.

Images