Digital printing image connection continuous printing method and apparatus that can hide seams

Abstract

A digital printing image connection continuous printing apparatus and method according to an embodiment of the present invention includes: an unwinding roller for unwinding printing fabric; a winding roller for winding the printed fabric; a printing engine disposed between the unwinding roller and the winding roller, including a blanket that is in contact with and rotates with an image imaging plate and a printing roller that is in contact with and rotates with the blanket; and a fabric direction conversion mechanism for converting the transport direction of the printing fabric passing between the blanket and the printing roller into a forward or reverse direction. When the transport direction is forward, the printing engine prints a first segmented image including a first overlapping area on a first fabric of the printing fabric. When the transport direction is reverse, only the first overlapping area printed on the first fabric is located below a second fabric of the printing fabric. When the transport direction is forward, a second segmented image including a second overlapping area is printed on the second fabric to generate a unit image in which the first overlapping area and the second overlapping area overlap.

Description

Technical Field

[0001] This invention relates to an industrial digital printer printing method and apparatus that, after applying an online primer to fabric continuously unwound from an un-winder roll, prints an image on its surface to obtain a printed fabric, and continuously winds the fabric onto a re-winder roll in a roll-to-roll continuous online paper feeding manner.

[0002] The present invention particularly relates to a method and apparatus for continuous printing of digital printed images, which, when the in-line length of the unit image to be obtained printed on the fabric unwound from the unwinding roller is greater than the length of the photo imaging plate of the digital printer, hides the unavoidable stitching line in the connecting part during the process of dividing it into multiple segmented images and operably connecting these segmented images for printing, thereby significantly improving the printing quality. Background Technology

[0003] Small images taken with a mobile phone or digital camera, such as portraits or landscapes taken during travel, are typically printed individually on photographic paper or other standard printing paper using small personal or office printers. However, when printing multiple copies of publications or extremely large images, such as photographs or advertising copy, repeatedly printing large single images, home or office printers are unsuitable, and industrial printing methods such as offset printing, gravure printing, or digital printing must be used.

[0004] Offset printing is a printing method in which a computer-to-plate (CTP) plate, obtained by outputting a printing plate from a computer, is mounted on a printing press for printing. Gravure printing is a method in which a concave surface is formed on a metal (copper plate) surface, ink is placed in the concave area, and ink is transferred to the substrate. Digital printing is a printing method in which images stored in digital file form are directly mounted on a computer-operated printing device for printing without physical printing media such as a CTP plate or copper plate.

[0005] Offset and gravure printing offer excellent print quality and are suitable for mass production, such as publishing. Digital printing technology offers print quality that is no less than that of offset or gravure printing, and is thus known as real-image output. It can directly output digital (e.g., mostly computer-generated) image files onto various media (fabric) of different materials and thicknesses (10-250 micrometers), such as paper, film (PVC, PET, etc.), and aluminum. Therefore, in addition to traditional paper-based printed materials such as flyers and posters, it is ideal for rapidly printing various small and medium-sized flexible packaging containers, including plastic bags, shrink films, labels, in-mold labels or shoulder straps, signs, and point-of-purchase (POP) advertisements (images or sentences that guide product prices or features, promotional information, and event information in supermarkets, stores, or event venues, and are product advertisements provided when purchasing goods or services) to meet the diverse needs of customers, including ultra-large-scale, small-batch advertisements.

[0006] Current digital printing presses typically employ roll-to-roll printing, where the printing fabric is wound into a roll on one side, hung on an unwinding roller, and continuously unwound in one direction, passing through a designated printing engine section. This process repeatedly outputs a predetermined unit length of printed content (images, etc.) along the length of the fabric. Then, the printed fabric is continuously wound into a roll on the other side. In this configuration, during the unwinding and winding of the printed fabric from one side to the other, the supply roller and winding roller can continuously unwind and wind in one direction simultaneously and without interruption (in this case, the fabric typically passes through a predetermined roller group mechanism consisting of multiple directional rollers, tension regulating rollers, drive rollers, transfer (supply) rollers, cooling rollers, etc.). Within a predetermined range of the process through the printing engine section, the fabric's direction of movement can be intermittently changed in both forward and reverse directions by the movable mechanism of the printing engine section.

[0007] The structure of a digital continuous printing press for this roll-to-roll fabric supply method is described in more detail below. For example... Figure 1The central concept of digital printing (especially the core of the printing engine section) illustrates that, in order to obtain a primary image, nano-ink particles of various colors, each with a size of approximately 1-10 nanometers (nm), are sequentially ejected from the nozzle head 2 of a CMYKOVG7 color cartridge 1 onto an image imaging plate 3, which rotates multiple times counterclockwise at a predetermined speed, to form a primary image original. This primary image original is then transferred to the outer peripheral surface of a heated blanket 4, which is in contact with the outer peripheral surface of the image imaging plate 3 and rotates clockwise, thereby forming a thin-film secondary image original 5 (printed image original). This printed image original 5 is then transferred to the surface of a fabric 7 between the blanket 4 and a printing roller 6, which is operatively opened and closed (ON / OFF) and rotated according to a predetermined procedure on the outer peripheral surface of the blanket 4, thus forming a printed fabric 7A. Figure 1 In the figure, reference numeral 8 represents laser exposure used to determine the position of the moving fabric printing reference point, reference numeral 10 represents a printing fabric roller (Roll) with the printing fabric wound on it, and reference numeral 50 represents a printed fabric 7A with the fabric to be printed wound on it.

[0008] In this digital printing press, the ink cartridge 1, which ejects micro-nano-sized nano-ink droplets, and the ink nozzle 2 connected to the ink cartridge 1 are fixed structures in a predetermined fixed position, and their own positions do not change. Multiple nano-ink droplets are precisely ejected from this fixed structure in a predetermined grid direction and precisely programmed onto a rotating imaging plate 3, thereby obtaining an image original.

[0009] Digital printing presses using this roll-to-roll continuous paper feeding method have the following advantages: they can output high-quality digital images generated by a computer without being limited by the material of the printed material; they can produce environmentally friendly printed materials due to the use of water-based inks and biodegradable fabrics; and they can achieve a high-speed output of approximately 25-35 meters per minute. Furthermore, and most importantly, they offer the following advantages: during continuous printing on the fabric, the printing roller 6, which moves in the opposite direction and rotates while in contact with the blanket 4 during the separation of the printing roller 6 from the blanket 4, can repeatedly perform the operational opening and closing connection structure of connecting and separating the blanket 4 over time. The fabric is first divided into predefined unprinted sections, and subsequent images are connected within these unprinted sections for printing. Therefore, even with large-sized images where the length dimension of a unit printed object is greater than the circumference R of the drum (plate), high-speed continuous printing can be achieved by connecting them.

[0010] However, while digital printers using this nano-ink jetting method have the significant advantage of being able to segment and connect large images of varying lengths for continuous production, an unavoidable problem arises: the leading edge of a subsequent segmented image clearly shows a stitching line at the connection point with the end of the previous image, which is connected to the previous segmented image. As a result, the print quality of the finished print is reduced, and even with precise laser exposure 8 used to determine the printing reference point position on the fabric, it is difficult to focus nanoscale pixels using this mechanical positioning structure.

[0011] Figure 2 and Figure 3 For the digital printer to output a unit image with a length L greater than the outer perimeter length R of the digital printer drum, the digital printer must be used. Figure 1 The photograph of the large printed matter P shown (L>R) is a photograph of a real digital printing example in which the printing quality of the final printed matter is reduced due to the presence of the seam line SL at the connection point of each segmented image when such a large unit image is divided into two smaller images (A, B) (A<R, B<R) and these are connected for printing.

[0012] This type of stitching is a problem that inevitably arises because even if the connecting pin is precisely adjusted at the connection point of the two segmented images A and B (the part where the end of the previous image connects to the front of the next image), the forward and reverse rotation direction of the printing roller 6 is changed and the fabric is fed back in order to connect the images in order to print the segmented images with a longer length. Therefore, it is limited to increase the printing density of the connection point mechanically.

[0013] Therefore, in the past, large printed materials P with a unit image length L greater than the outer perimeter length R of the digital printer drum (L>R) were divided into two short images (A, B) (A<R, B<R) using a digital printer. During the process of operatively connecting and printing these A and B images, a new type of digital printing machine image connection continuous printing method was needed to hide the linear stitching line SL that appears at the connection point of these segmented images. The present invention meets this need.

[0014] On the other hand, with the widespread use of digital cameras, especially smartphones equipped with digital cameras, it has become possible to take photos in daily life regardless of time and place. Multiple photos can be stored on digital storage media or cloud servers. For multiple photos, a terminal capable of transmitting these images (digital camera, smartphone, USB flash drive, laptop, etc.) can be connected to a printer, allowing for easy printing whenever needed. Furthermore, various photo processing software (applications) installed on smartphones can be used to connect multiple small images from daily life vertically and / or horizontally to obtain panoramic images. These panoramic images can be obtained by outputting each image onto a single sheet of paper and then properly bonding them together, or by using preprocessing applications to merge multiple images into a single image before outputting them. Of particular note is the technique of outputting (printing) with a stitching line hidden in the connecting part of multiple panoramic images, as described in Korean Patent Publication No. 10-2014-0047446 filed by Pronics Co., Ltd.

[0015] Specifically, Korean Patent Publication No. 10-2014-0047446 discloses a panoramic image output (printing) system, which discloses a panoramic image printing technology. For example, a panoramic image composed of multiple images connected side by side is separated into predetermined sizes according to the printable size of a movable ink ribbon built into the printer. The length information of the boundary surface is set in such a way that predetermined parts of the separated panoramic images overlap. On the other hand, a terminal is provided to determine the printing density and output it based on the length of the overlapping boundary surface. The terminal receives the length information of the boundary surface overlapping with the separated panoramic images and the differential printing density based on the length of the boundary surface, and prints in different densities in sequence according to the length information of the overlapping boundary surface and the differential printing density.

[0016] However, the technology disclosed in Korean Patent Publication No. 10-2014-0047446 utilizes the following technical effect: The basic technical idea is to constantly control the heating time of the heat transfer head to maintain a constant printing density of the image. When the viewing angle is changed to alter (shorten) the heating time of the heat transfer head, the density of the transferred image is reduced (the printing density can be lowered). More specifically, the technical principle of Korean Patent Publication No. 10-2014-0047446 is as follows, as described in this specification... Figure 4 and Figure 5 As shown, Figure 4 As shown in part (A), when the length A of the first boundary surface 301 and the length B of the second boundary surface 311 are set, as follows: Figure 4As shown in section (B), after overlapping the first boundary surface 301 of the first panoramic image and the second boundary surface 311 of the second panoramic image, the printing density is set in an inversely proportional manner according to the overlapping positions of the plurality of boundary surfaces 301, 311, such as... Figure 5 As shown in section (A), in order to gradually reduce the print density along one side of the boundary (towards the right in the figure), as... Figure 5 As shown in part (B), the area with high image density (non-overlapping area) maintains a longer head heating time T0. When the boundary surface is reached and the image density is reduced, the heating time of the heat transfer head is shortened in the direction of the printing ribbon, such that T1 > T2 > T3, so that the panoramic photo 400 is output on the printing paper. This technical structure for controlling the heating time of the heat transfer head is the essential part of Korean Patent Publication No. 10-2014-0047446. Therefore, it will be described in more detail. It utilizes the technical principle that when the amount of heating to the ink ribbon of the heat transfer head is reduced, the printing density of the image can be reduced. In the actual process of constructing the heating part of the heat transfer head, the variable heat generation unit is not directly formed in the heat transfer head so that its heat generation can be directly changed. Instead, the heat transferred to the film ribbon is relatively controlled by controlling the movement speed of the ink ribbon and the printing paper that move in contact with the heat transfer head. In this case, a technical structure for differentially and variablely controlling the driving speed (movement speed) of the ink ribbon and the printing paper is necessary. However, the technology described herein has not explicitly or implicitly proposed what the technical structure for variably controlling the ink band and printing paper is, or how it is constructed. Furthermore, in Korean Patent Publication No. 10-2014-0047446, in order to sequentially print overlapping areas set by an inverse proportional printing density, it is inevitably necessary to backtrack (reverse move) the overlapping area intervals and print them, but no technical structure has been proposed to solve the problem of how to achieve this backtracking (reverse movement) of the overlapping area intervals, particularly regarding the printing image positioning method and image defocusing issues in the overlapping areas.

[0017] For example, Korean Patent Publication No. 10-2014-0047446 is useful for slowly outputting single or relatively small quantities of non-commercial personal or home-use images of everyday subjects, such as images taken with a mobile phone, without time constraints. Moreover, compared to industrial digital printing machines that repeatedly print hundreds to thousands of ultra-large images, such as those approaching 2 meters in length, at a high speed of approximately 25-35 meters per minute, the basic technical structure and industrial application scope of this patent application are different. Therefore, in describing the related technology in Korean Patent Publication No. 10-2014-0047446, simply describing the "inverse proportional gradient printing of overlapping areas" technical structure can be considered as having the same or similar technical concept as this invention. However, in the specific description, the embodiment of its basic printing engine core and the printing method are completely different technologies from the invention of this application. Summary of the Invention

[0018] Technical issues

[0019] The purpose of this invention is to address the aforementioned problems of existing digital printing by proposing a novel printing method that uses a digital printer to obtain a raw image for printing by fixedly ejecting fine nano-ink particles from the fixed nozzle heads of ink cartridges fixed in a predetermined position, and then transferring the image to a printing fabric, thereby preventing the formation of seam lines at the joints when continuously printing large images.

[0020] Solution to the problem

[0021] A digital printing image connection continuous printing apparatus according to an embodiment of the present invention is characterized by comprising: an unwinding roller for unwinding printing fabric; a winding roller for winding the printed fabric; a printing engine disposed between the unwinding roller and the winding roller, comprising a blanket that is in contact with and rotates with an image imaging plate and a printing roller that is in contact with and rotates with the blanket; and a fabric direction conversion mechanism for converting the transport direction of the printing fabric passing between the blanket and the printing roller into a forward or reverse direction. When the transport direction is forward, the printing engine prints a first segmented image including a first overlapping area on a first fabric of the printing fabric. When the transport direction is reverse, only the first overlapping area printed on the first fabric is located below a second fabric of the printing fabric. When the transport direction is forward, a second segmented image including a second overlapping area is printed on the second fabric to generate a unit image in which the first overlapping area and the second overlapping area overlap.

[0022] A method for continuous digital printing of connected images according to an embodiment of the present invention is characterized by comprising: a process of unwinding a printing fabric using an unwinding roller; a process of printing on the printing fabric using a printing engine; a process of a fabric direction conversion mechanism converting the transport direction of the printing fabric between the blanket of the printing engine and the printing roller into a forward or reverse direction; and a process of winding the printed fabric using a winding roller. The printing process on the printing fabric includes: when the transport direction is forward, printing a first segmented image including a first overlapping region on a first fabric of the printing fabric; when the transport direction is reverse, ensuring that only the first overlapping region printed on the first fabric is located below a second fabric of the printing fabric; and when the transport direction is forward, printing a second segmented image including a second overlapping region on the second fabric to generate a unit image in which the first overlapping region and the second overlapping region overlap.

[0023] The effects of the invention

[0024] The digital printing image connection continuous printing method and apparatus of the present invention, formed by the stated purpose and the technical structure for understanding therein, is particularly useful when printing large images P in good quality where the length L of the unit image to be printed is greater than the outer perimeter length R (L > R) of the drum of the digital printer.

[0025] More specifically, in large industrial digital printers that obtain the original image to be printed by ejecting nano-sized fine ink particles from each nozzle head 2 of the ink cartridge, when printing a large image with a unit image length of about 2 meters, the digital printing image connection continuous printing method and apparatus of the present invention, which is divided into two smaller images (A, B) with (A < R, B < R), operably connects the printing of two segmented images (A, B) with (A < R, B < R). By using a complementary and supplementary printing density gradient printing process in the overlapping area of ​​these two segmented images, the linear stitching line SL that previously appeared in the connection part can be hidden, thereby significantly improving the printing quality of existing digital printers. Attached Figure Description

[0026] Figure 1 A diagram illustrating the central concept of digital printing.

[0027] Figure 2 and Figure 3 In the case of a large printed matter P where the length L of a unit image is greater than the outer perimeter R of the digital printer drum (L > R) when using an existing digital printer to output the print, a photograph of a real digital printing example can be obtained by dividing the print into two segmented images A and B and connecting them, revealing the presence of a distinct linear seam line SL in these connecting parts.

[0028] Figure 4As the technology disclosed in Korean Patent Publication No. 10-2014-0047446, Figure 4 Part (A) is an illustrative diagram showing the process of setting the boundary length of a panoramic image. Figure 4 Part (B) is an example diagram showing the image density based on the set boundary length of the panoramic image.

[0029] Figure 5 As the technology disclosed in Korean Patent Publication No. 10-2014-0047446, Figure 5 Part (A) is an example diagram illustrating a variable print gradient based on the print density of the panoramic image boundary. Figure 5 Part (B) is an illustration of a process in which the heating time of the heat transfer head of the printing ribbon can be gradually shortened over time to gradually reduce the printing density as printing proceeds along its printing direction.

[0030] Figure 6 As a simplified illustration of the overall structure of a digital printer, the diagram shows the printing engine core of the digital printer enlarged within the circular dashed lines, and the upper and lower horizontal reciprocating transfer rollers, as one of the structural elements of the fabric orientation conversion mechanism, in the state of being moved to the position for starting printing.

[0031] Figure 7 This diagram illustrates the state at which printing of the first segmented image A begins as the horizontally reciprocating conveyor roller starts to move to the right.

[0032] Figure 8 To show in Figure 7 A diagram showing the state of the printing process.

[0033] Figure 9 To show in Figure 8 A diagram showing the state of further printing.

[0034] Figure 10 As in Figure 9 The diagram shows the state of printing in the fabric, and the diagram shows the steps of continuously moving the fabric to the length of the second segment image B in a non-printed state after the first segment image A has been printed.

[0035] Figure 11 As shown in Figure 10 After the first step, the horizontal reciprocating conveyor rollers begin to move to the left again. This diagram shows the fabric moving in the opposite direction and the printing rollers being separated from the blanket by gaps.

[0036] Figure 12 To show in Figure 11After that, the horizontal reciprocating conveyor roller is moved to the leftmost position as shown in the diagram. At this point, the fabric moves in the direction of the printing roller, which remains in a position separated from the rubber blanket.

[0037] Figure 13 To demonstrate the presence of a specified stitching line at the junction of segmented images compared to existing digital printing technologies ( Figure 13 In section A), the basic technical idea is to construct a defined portion GZ of the segmented image using overlapping connecting parts, and to hide the seam lines through the gradient printing principle of the overlapping connecting parts. Figure 13 (B in the middle).

[0038] Figure 14 To illustrate in more detail the printing movement direction along each segmented image... Figure 13 The diagram shows the technical principle of the gradual distribution of printing density and the gradual structure in the overlapping connection part shown in B.

[0039] Figure 15 To show the basis in Figure 13 B and Figure 14 The disclosed technical concept is that, in the overlapping connection part of the segmented image, along its printing length direction, the printing density consists of a decreasing density part with a linear (linear) rate of change and an increasing density part with a linear (linear) rate of change. In the connection part of the segmented image, the arithmetic sum of the decreasing density value and the increasing density value at any position always complement each other to form 100%. Therefore, even if the linear seam line is hidden, the actual printed product does not have a color density reduction part in its connection part.

[0040] Figure 16 This is a schematic diagram illustrating why, when overlapping printing with a time difference occurs, even if the print distribution amount, i.e., the number of ink droplets, is increased by the same factor of 2, the print density cannot be doubled.

[0041] Figure 17 This is another example illustrating the relationship between the number of printing ink droplets and their attachment location. Figure 17 Part (A) is a diagram illustrating the ideal distribution of printing ink droplets, symbolizing their even distribution across the vacancy spaces in the printing fabric during the process of ejecting nano-sized printing ink droplets and allowing them to adhere to the printing fabric. Figure 17 Part (B) is a schematic diagram showing the random distribution of nanoprinting ink droplets during actual printing.

[0042] Figure 18 To show that in order to improve in Figure 15The problem of reduced color density shown in the figure is illustrated by the present invention, which assigns a variable weighted value to the gradient density of the overlapping section of the segmented image by printing along the printing direction in the overlapping section of the segmented image.

[0043] Figure 19 To show in detail along in Figure 18 The diagram illustrates the concept of variable weighting values ​​for the gradient density of each gradient in the printing direction of the overlapping connection portion of the segmented image according to the present invention.

[0044] Figure 20 This diagram illustrates the structure of the first and second segmented printing sections in the digital printed image connection continuous printing method of the present invention, when actual printing is performed along the printing direction in the overlapping connection section of the segmented images using the concept of variable weighting values ​​for each gradient density, and the gradient printing start and end positions of the overlapping connection section formed by the rear ends and front ends of these first and second segmented printing sections.

[0045] Figure 21 For application Figures 18 to 19 The photograph shows another practical example of the digital printing image connection continuous printing method of the present invention that can hide the seam. P shows the overall unit image (length: L) to be printed. A and B are diagrams of a complementary gradient printing method that is suitable for dividing the unit image P into two segmented images and assigning weighted values ​​of the printing density of the overlapping connection portion applicable to each printing end and printing front end of these segmented images.

[0046] Figure 22 To be briefly shown together Figure 21 The diagram shows the negative gradient printing method of the first segmented image and its overlapping connection part, which is prioritized for printing during the printing process of the unit image, and the workings of the core of the digital printer engine.

[0047] Figure 23 To show in printing Figure 21 The diagram shows the state of the digital printer engine core before the overlapping connection of the second segmented image, which is being printed in the process of the unit image.

[0048] Figure 24 As shown in the connection Figure 22 and Figure 23 The diagram shows a connection between the first and second segmented printed images.

[0049] Figure 25 As a second embodiment of the digital printing image connection continuous printing method of the present invention that can hide the stitching, it shows a schematic diagram of the waveform gradient formed at the beginning and end of the overlapping connection portion.

[0050] Figure 26 This is a schematic diagram illustrating that, in a second embodiment of the digital printing image connection continuous printing method of the present invention, the waveform gradient shape formed by the gradient start portion and the gradient end portion can change according to the degree of compositeness of the printed colors.

[0051] Figure 27 The figure illustrates an example in which, in a second embodiment of the digital printing image connection continuous printing method of the present invention, which can hide the stitching, the waveform gradient shape embodied in the connection part (overlapping area) can be preset into multiple patterns such as straight lines and free curves.

[0052] Figure 28 Parts (A), (B), and (C) are diagrams illustrating the concepts of brightness, saturation, and hue.

[0053] Figure 29 This diagram illustrates an example of the process flow of a continuous printing method for connecting digital printed images that can conceal stitching, in accordance with the present invention.

[0054] Figure 30 Part (A) to Figure 30 Part (E) illustrates an example of whether there are characters and gradient patterns related to the character shape within the overlapping area.

[0055] Figure 31 Part (A) to Figure 31 Part (D) illustrates the gradient pattern when there are differences in brightness and saturation of colors in the overlapping area of ​​the image.

[0056] Figure 32 Part (A) to Figure 32 Part (B) is a diagram showing an example of image classification categories used to determine the length of overlapping regions. Detailed Implementation

[0057] This specification provides a brief explanation of the terminology used and a detailed description of the invention.

[0058] The terminology used in the embodiments of this invention has been selected from general terms that are used as broadly as possible, taking into account their function in this invention. This can be modified according to the intent of those skilled in the art, convention, or the advent of new technologies. Furthermore, in certain cases, terms chosen arbitrarily by the applicant may also be used; in such cases, their meanings are described in detail in the description of the corresponding invention. Therefore, the terminology used in this invention is not simply the name of a term, but should be defined based on its meaning and the overall content of the invention.

[0059] The embodiments of the present invention may have various modifications and multiple embodiments. Specific embodiments are illustrated and described in detail in the accompanying drawings. However, this is not to limit the scope of the invention to specific implementation forms, but should be understood to include all modifications, equivalent technical solutions, or alternative technical solutions included in the inventive concept and scope of description. In the process of describing the embodiments, detailed descriptions of related well-known technologies will be omitted where it is determined that such specific descriptions would obscure the main point of the description.

[0060] The terms "first," "second," etc., can be used to describe multiple structural elements, but structural elements are not limited to these terms. The terms are only used to distinguish between two types of structural elements.

[0061] Unless the context explicitly defines it, the singular includes the plural. In this application, terms such as "comprising" or "having" are used to specify the presence of features, numbers, steps, actions, structural elements, components, or combinations thereof as described in the specification, and do not preclude the presence or additional possibility of one or more other features, numbers, steps, actions, structural elements, components, or combinations thereof.

[0062] In embodiments of the present invention, a "module" or "part" may perform at least one function or operation, and may be embodied in hardware or software or a combination of hardware and software. Furthermore, multiple "modules" or multiple "parts," except for those "modules" or "parts" that need to be embodied in specific hardware, may be integrated into at least one module to embody at least one processor (not shown).

[0063] In embodiments of the invention, when a part is "connected" to other parts, this includes both "direct connection" and "indirect connection" with other devices in between. Furthermore, when a part "includes" other structural elements, unless specifically objected to, it means that other structural elements may also be included, rather than excluded.

[0064] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily implement the present invention. However, the present invention can be embodied in many different forms and is not limited to the embodiments described herein. Moreover, in the drawings, parts unrelated to the description have been omitted for the purpose of clarifying the present invention, and similar reference numerals are used for similar parts throughout the description.

[0065] Figures 6 to 12The accompanying drawings are illustrations of an example of a printing process in which the following steps are sequentially described in both the conventional and the present invention. When printing a digital image on the printing fabric 7 unwound from the unwinding roller 10 (fabric roller), if the length of the unit image to be obtained in the online direction is greater than the circumference R of the image imaging plate 3 of the digital printer, it is divided into multiple (2) images and these 2 divided images are operatively connected for printing.

[0066] first, Figure 6 As a diagram that briefly illustrates the overall structure of a digital printer, it shows the core part C of the printing engine enlarged within the dashed circle. As a structural element of the fabric orientation conversion mechanism, it shows the state at which a pair of horizontal fabric reciprocating rollers HR1 and HR2, which move simultaneously to the left and right along the horizontal guide rail GR, move to the position for starting printing (the left end of the guide rail GR).

[0067] like Figure 6 As shown, the fabric 7 continuously unwound from the unwinding roller 10 passes sequentially through the first forward and reverse drive roller R1, the upper reciprocating transfer roller HR1, and the second forward and reverse drive roller R2, and is supplied between the blanket 4 and the printing roller 6 (the above describes the unprinted portion of the fabric transport path). Furthermore, during the contact and rotation of the printing roller 6 and the blanket 4, a predetermined printed image 5 is transferred onto the surface of the blanket 4 through the fabric between the blanket 4 and the printing roller 6 and printed. After this process, the fabric passes through the third forward and reverse drive roller R3, the lower reciprocating transfer roller HR2, and the fourth forward and reverse drive roller R4, and is wound onto the rewinding roller 50 (printed fabric winding roller) (the above describes the printed portion of the printed fabric transport path).

[0068] In the digital printer engine with the above structure, as the upper and lower pair of horizontal reciprocating fabric transfer rollers HR1 and HR2 move reciprocally left and right along the guide rail GR at predetermined time intervals, the forward and reverse driving directions of the forward and reverse drive rollers (R1 to R4) will be reversed. During the period when the horizontal reciprocating fabric transfer rollers HR1 and HR2 move to the right in the figure, the fabric movement direction is forward (the direction of printing). Conversely, during the period when the horizontal reciprocating fabric transfer rollers HR1 and HR2 move to the left in the figure, the fabric movement direction is reverse. Printing is terminated during the process of the fabric moving in the reverse direction. Hereinafter, with reference to other figures, it will be explained again that when the fabric movement direction is reversed, the position determination work of connecting the beginning of the second segmented image to the end of the first segmented image is performed. The undescribed reference numeral 20 is a structural part (e.g., a pre-processing part) that properly processes the printing of the fabric; in other figures, reference numeral 20 is omitted.

[0069] When the length L of the unit image printed on the fabric 7 in the online direction and the circumference R of the image imaging plate 3 are related, for example, when the latter is an integer multiple of the former (R = n × L, where n is a natural number), the printing roller 6 can be driven in one direction without changing the fabric transport direction. When the latter is not an integer multiple of the former, in order to prevent overlapping printing with other images or to prevent fabric waste due to unprinted portions, the specified length of overlapping printing of the fabric is formed by unprinted portions, and the unprinted portions are returned in the opposite direction and their positions are modified to connect to their subsequent printing positions for continuous printing. Furthermore, when the online direction length L of the unit image printed on the fabric 7 unwound from the unwinding roller 10 is greater than the circumferential length R of the image imaging plate 3 of the digital printer (L > R), the desired unit image is divided into multiple (2) images, which are then operably connected and printed with staggered intervals. In this case, the transport direction of the fabric 7 is intermittently reversed to match the connection position, and subsequent segmented images are connected to previously segmented images and printed. This invention is particularly applicable to the case where the size (length) of the unit image to be printed is greater than the circumferential length R of the image imaging plate 3. Hereinafter, reference will be made to... Figures 7 to 12 This describes the process of dividing a unit image printed on fabric into multiple images (a first segmented image printed first and a second segmented image printed subsequently) and then interleaving them to connect them for printing, when the online direction length L of the unit image printed on the fabric is greater than the circumference length R of the image imaging plate of the digital printer.

[0070] Figures 7 to 9 The diagrams shown are illustrated sequentially, illustrating the process of printing the first segmented image in a printed image. Figure 7 To illustrate the state of a pair of horizontally reciprocating conveyor rollers HR1 and HR2 moving along guide rail GR from the leftmost position in the diagram ( Figure 7 The image begins to move to the right side of the image from its initial state, thus creating a state where printing begins from the front (starting) part of the first segmented image. Figure 8 To show in Figure 7 A diagram showing the state of the material being printed. Figure 9 To show in Figure 8 A diagram showing the state of further printing.

[0071] With these Figures 7 to 9The steps shown are performed as follows: a first segmented image is obtained on the cylindrical image imaging plate 3; then, the blanket 4 remains in contact with the outer circumference of the image imaging plate 3, the former rotating clockwise and the latter counterclockwise. After the first segmented image applied to the image imaging plate 3 is transferred to the blanket 4, it is transferred to the fabric during a clamping and conveying operation based on the cooperation of the printing roller 6. Through this process, the first segmented image is printed on the fabric.

[0072] Figure 10 As in Figure 9 The diagram shows the state after which printing will take place. The length of the second segmented image is after the fabric passes through the printing roller 6 in a non-printing state and completes the printing of the first segmented image. This non-printing overrun movement will continue until the position where the pair of horizontal reciprocating conveyor rollers HR1 and HR2 end their movement in the right direction (reaching the right end position). During the period of this non-printing overrun movement of the second segmented image length, the process of generating the subsequent second segmented image on the plate 3 is carried out.

[0073] Figure 11 and Figure 12 To show Figure 10 The diagram shows the process after the steps shown, where the horizontal reciprocating conveyor rollers HR1 and HR2 begin to move to the left again. From this point onward, the fabric 7 moves in the opposite direction, and in this case, the printing roller 6 is separated from the blanket 4 by the interval G.

[0074] Figure 12 To show in Figure 11 Subsequently, the horizontal reciprocating conveyor rollers HR1 and HR2 are moved to the leftmost position of the guide rail GR. As the horizontal reciprocating conveyor rollers HR1 and HR2 move to the left, the driving directions of the forward and reverse drive rollers (R1 to R4) all reverse. As a result, the unprinted area of ​​the overlapping second segmented image is returned (reversely moved) and moved to the position connected to the first segmented image. On the other hand, during this continuous reverse movement of the fabric, the second segmented image output to the plate 3 is transferred to the blanket 4.

[0075] At the point when the printed fabric is returned, the printing roller 6 contacts the blanket 4 again. Through this process, the printed fabric moves in the reverse direction, reaching the position connecting the first segmented image at the beginning of the non-printing section. Then, the printing roller 6 returns to its contact position with the blanket 4 in a pressing state. Simultaneously, the driving direction of the forward and reverse drive rollers (R1 to R4) changes back to forward. Thus, the fabric moves in the forward direction, and the second segmented image is connected to the first segmented image and continuously printed. Afterwards, the driving mode of the digital printer structural elements when printing the second segmented image is the same as described above. Figure 7 The same applies thereafter. Longer online image connections for continuous printing in roll-to-roll digital printing can be achieved by repeatedly performing this cycle.

[0076] As described above, the printing roller 6, which rotates and is repeatedly and operably connected to the blanket 4 at predetermined time intervals, maintains a contact position with the blanket 4 in a pressing state and a separation position separated from the blanket 4 with a gap G. The horizontal reciprocating transfer rollers HR1 and HR2, which change the forward and reverse movement direction of the fabric and provide the transfer force or tension adjustment of the fabric, and the forward and reverse drive movements of multiple forward and reverse drive rollers are organically combined through a preset predetermined transfer program. This allows for the implementation of a continuous printing method that connects multiple segmented images using a roll-to-roll digital printer.

[0077] Figure 13 To demonstrate how to address the presence of specified stitching lines at the junctions of segmented images in existing digital printing technologies. Figure 13 Figure A shows the basic technical idea of ​​hiding the suture line by using the gradient printing principle of the overlapping connection part to form a defined portion GZ of two segmented images. Figure 13 B in the middle, Figure 14 To illustrate in more detail the printing direction along each segmented image Figure 13 The diagram shows the technical principle of the gradual distribution of printing density and the gradual structure in the overlapping connection part shown in B.

[0078] Figure 13 To address the issue of existing printing methods that use roll-to-roll digital printers, where the connection of segmented images is based on line points at specific locations, resulting in a stitched line SL at the connection point, Figure 13 A), as a method for connecting segmented images with an overlapping connection portion GZ of a specified width, is a schematic diagram in which the stitching line is hidden in the overlapping connection portion interval by means of a linear inverse proportional gradient printing principle. Figure 13 (B) in the text. And, as in... Figure 14 As shown, the printing direction of each segmented image and the presence of the overlapping connection GZ are illustrated, along with the complementary gradient distribution pattern, gradient start position, and gradient end position in the overlapping connection. The complementary relationship of the gradient distribution pattern means that at any position in the overlapping connection, the arithmetic sum of the negative gradient printing density value on the first segmented image side and the positive gradient density value on the second segmented image side is the same as the density value of the original image in the overlapping region. To achieve this relationship, the printing density value will be linearly changed so that the negative gradient printing density value and the positive gradient density value achieve a linear complementary relationship.

[0079] like Figure 13 and Figure 14As shown, compared to existing digital printing image connection continuous printing methods ( Figure 13 In step A), the unit image P to be printed is divided into two segmented images P(A) and P(B), and then connected for printing. Without a width in the printing length direction, the images are connected at the connecting point by typical line points, thus creating a clearly visible seam line SL at the connecting point. This printing method involves an overlapping area with a specified width. Figure 13 In section B), to solve this problem, the defined intervals of the two segmented images P(A) and P(B) are connected by overlapping portions. The defined width W1 of the rear length direction of the printing direction of the first segmented image A is the same as the defined width W2 of the front length direction of the printing direction of the second segmented image B (W1 = W2), and the images of these portions are identical, forming an overlapping surface contact gradient region GZ. The first segmented image P(A) is printed using a negative gradient method where the printing density decreases linearly along the length direction in the surface contact gradient region GZ. The second segmented image P(B) is printed using a positive gradient method where the printing density increases linearly along the length direction in the surface contact gradient region GZ.

[0080] Print density refers to the amount of ink produced by the inkjet nozzle ( Figure 1 (See attached figure 2) The printing density is changed by reducing the number of nano-sized ink droplets ejected. Negative gradient printing with reduced density is achieved by gradually reducing the number of ink droplets ejected through the inkjet nozzle along the printing direction, although the fabric feed speed is the same. Conversely, positive gradient printing is achieved by gradually increasing the number of ink droplets ejected through the inkjet nozzle along the printing direction, although the fabric feed speed is the same.

[0081] However, as mentioned above, applying a negative gradient method where the printing density decreases linearly (as a function of a linear equation) and a positive gradient method where the printing density increases linearly (as a function of a linear equation) to the overlapping region of two segmented images results in... Figure 2 , Figure 3 As shown, although the sharp and distinct linear sutures disappear, instead, as... Figure 15 As shown, this relates to the problem of color density reduction sections (color density reduction lines) of a specified width forming in the overlapping connection region of two segmented images P(A) and P(B). These color density reduction sections differ from existing sharp and dense linear seams; they are also relatively wide seams, thus requiring a solution.

[0082] The degree varies depending on the type of color or the content of the printed image, but through careful study, the inventors have come to understand the reasons for the occurrence of novel problems as such a concentration reduction in many cases.

[0083] In other words, the reason why most colors can be naturally reproduced during the printing process, even when using only four limited ink colors—Cyan, Magenta, Yellow, and Black—is as follows: Printing is done using a finely lattice structure of halftone dots for each color. The number of ink droplets on each dot is adjusted according to the desired density of these colors. Furthermore, the dots are evenly distributed and printed in the spaces between them to prevent overlap of pixels (halftone dots) of each color. When the halftone dots of different pigments are printed in the same position and overlap, the multi-color printed image cannot be properly reproduced.

[0084] In the field of digital printing presses to which this invention pertains, ink particles of 1-10 nanometer size, ejected from the inkjet nozzle 2, are formed in a constant manner to prevent each color from overlapping. They are applied to a photo imaging plate along a predetermined homogeneous mesh pattern. Each pigment completes a process of printing the photo imaging plate (drum) from start to finish with one pigment, followed by a process of printing the photo imaging plate (drum) from start to finish with another pigment, thus determining the overall combination of the printed mesh and thereby applying a complete image to the photo imaging plate (drum).

[0085] However, for printed fabrics, when using a forward / reverse drive method to overlap printing on a predetermined area that has been pre-printed in a priority cycle with a new printing cycle, subsequent cycles are needed to print the empty mesh spaces between the pigments (pixels) printed in the priority cycle. For extremely small pixels (1-10 nanometers in size), the mechanical positioning of the fabric makes it practically impossible to align these meshes. To illustrate this further, in the case of printing a 100% concentration yellow monochrome, even if it is printed with 100% yellow in one cycle and then first printed with 50% yellow, followed by another subsequent cycle (re-determining the position of the printing fabric) to overlap it with 50% yellow, the overall result is that 100% yellow concentration cannot be achieved because the pixels in the subsequent cycles cannot be accurately printed in the remaining spaces printed in the priority cycle. This is due to the change in the position of the printing fabric.

[0086] Figure 16 and Figure 17 For illustration purposes, Figure 16This is a diagram illustrating why, when two overlapping prints with a time difference are performed, the print density cannot be doubled even if the number of ink droplets is doubled in both cases. That is, Figure 16 For example, assuming four ink droplets are sprayed to the left, when four more ink droplets are added to the fabric, thus doubling the overall print density with eight ink droplets, if the position of the fabric sprayed when adding the four additional ink droplets is different from the first print (i.e., not precisely positioned at the same location), then as follows: Figure 16 Part (A) to Figure 16 As shown in section (D), the ink droplets do not adhere to the space of the fabric, but rather randomly overlap and adhere to the ink droplets ejected in the first spray. Therefore, it can be concluded that the printing density is not arithmetically proportional to the number of ink droplets ejected. This is an unavoidable phenomenon that occurs because, compared to the extremely small ink droplets with a size of 1-10 nanometers, it is difficult to determine the position of the fabric at the 1-10 nanometer level through physical units or operations.

[0087] and, Figure 17 This is shown from the perspective of further increasing the size of the printed original. Figure 16 The research and its results. Figure 17 In the case of printing using a negative gradient method where the printing density gradually decreases in the printing direction (arrow direction) shown on the left, the upper portions (1), (2), and (3) can exhibit a regular printed film mesh pattern that can be obtained by reducing the number of ink droplets ejected while the printing fabric is fixed. The lower portions (4), (5), and (6) can exhibit a negative gradient method implemented after changing and repositioning the fabric. Even with a negative gradient of the same proportion as the upper case, a uniform printed ink mesh pattern can be obtained. The inventors understand that for this reason... Figure 15 The overlapping connection of two segmented images P(A) and P(B) results in a color density reduction section (color density reduction line) of a specified width.

[0088] Simply put, the more ink droplets ejected, the higher the print density. As mentioned above, in the field of digital printing to which this invention pertains, the content described is not precisely a technical issue. The inventors, through numerous experiments and research, have discovered the following reasons.

[0089] In printing using ink droplets, when both the nozzle and the printing fabric are placed in fixed positions and printing is performed, the amount of ink droplets ejected and the concentration of the printed product have a homogeneous correlation (e.g., a proportional relationship). However, in the case of this invention, an image is divided into two parts, front and back, with images of equal width at the rear and front ends of the divided images, and these parts are overlapped and printed with a time difference. If either the nozzle or the printing fabric is moved to a different position, the homogeneous proportional relationship between the amount of ink droplets ejected and the concentration of the printed product cannot be achieved. This is because when the overlapping area is repeatedly printed with a time difference, it is difficult to position the printing fabric for the second printing at the same position as the first printing. The technical field applicable to this invention is the ejection of ink droplets with a size of 1-10 nanometers (1 nanometer = 10). -9 Digital printing, which involves ejecting extremely small ink particles (meters), uses ink jet nozzles to eject ink droplets from a fixed position. The printed fabric is then printed by changing its supply direction and being returned at specified intervals, so that the overlapping areas of the printed fabric are not constantly printed.

[0090] In this invention, the process of deriving this problem (solving the problem) is extremely important. The process of identifying the problem and understanding its causes to date is explained again below.

[0091] This invention is formed by overlapping an overlapping region GZ, where the rear end width of a first segmented image A (printed preferentially) and the front end width of a second segmented image B (printed subsequently) are identically superimposed. The first segmented image A is formed using a negative gradient (Minus Gradation) method, where the ink concentration (the number of ejected ink droplets) decreases as printing proceeds along the length direction within the overlapping region GZ. The second segmented image B is formed using a positive gradient (Plus Gradation) method, where the ink concentration (the number of ejected ink droplets) increases as printing proceeds along the length direction within the overlapping region GZ. In a gradient printing process, the first segmented image A is printed using a negative gradient method where the ink density in the overlapping region GZ decreases linearly from 100% to 0% as printing proceeds along the length. The second segmented image B is printed using a positive gradient method where the ink density in the overlapping region GZ increases linearly from 0% to 100% as printing proceeds along the length. The arithmetic (additive) sum of the gradient densities at the same positions between these images reaches 100%, thus failing to achieve the intended primary color density (resulting in a failure). Figure 15 The color density reduction area (color density reduction line) at the center of the overlapping connection shown in the diagram. This is an unavoidable phenomenon that occurs because it is impossible to accurately position the fabric where the second segmented image B is printed at the same position as the fabric where the first segmented image is printed.

[0092] Therefore, in the method of printing by altering the gradient between segmented images in the manner of overlapping printing on a specified width of fabric, even though existing sharp linear stitching lines can be avoided, a new problem of reduced color density, which is another problem, inevitably occurs. In order to solve this problem, the inventors have invented a scheme that assigns a weighted value to the gradient density (an additional increase in the number of ink droplets ejected) to complete the present invention.

[0093] The invention is characterized by sharing an overlapping region GZ formed by the identical overlap of images of a pre-printed first segmented image A with a predetermined width in the longitudinal direction on the rear side and a subsequently printed second segmented image B with a predetermined width in the longitudinal direction on the front side. The first segmented image A is printed using a negative gradient printing method where ink density decreases as printing proceeds along the longitudinal direction in the overlapping region GZ, and the second segmented image B is printed using a positive gradient printing method where ink density increases as printing proceeds along the longitudinal direction in the overlapping region GZ. However, the first segmented image A does not linearly decrease in ink density from 100% to 0% in the overlapping region GZ as printing proceeds along the longitudinal direction; instead, additional density is added along the printing direction. The printing process involves a non-linear (non-linear) negative gradient method, where the ink concentration in the overlapping region GZ increases linearly from 0% to 100% along the length direction. Similarly, the second segmented image B is not printed by adding an additional concentration (also adding the number of ink droplets) along the printing direction, i.e., a non-linear (non-linear) positive gradient method. As a result, compared to the original image, the arithmetic sum of the concentrations of these two decreasing and increasing concentrations (the arithmetic addition of the number of ink droplets) exceeds 100% at any point in the entire overlapping region GZ during printing, preferably exceeding 110% to 170%.

[0094] Figure 18 To show alternative Figure 13 and Figure 14 Part (B) is a schematic diagram showing the application of decreasing and increasing gradients in the overlapping region GZ, which is the core of the digital printing image connection continuous printing method of the present invention, and the application of non-linear gradients with an additional concentration value δ on the linear change of concentration ε. Figure 18 In the diagram, the vertical red lines mark the starting positions of the overlapping regions GZ of the first segmented image PA and the second segmented image PB, i.e., the starting lines GZS1 and GZS2 for the applicable gradient. The vertical green lines mark the ending positions of the gradient in the overlapping regions GZ of the first segmented image PA and the second segmented image PB, i.e., the ending lines GZE1 and GZE2 for the applicable gradient. Furthermore, as... Figure 13 and Figure 14 As shown on the right, in Figure 18 As can be seen from the diagram, the gradient color density changes in the overlapping regions GZ of the first segmented image PA and the second segmented image PB are patterned together with positive (+) and negative (-) symbols and displayed on a convex curve on the hypotenuse of a right triangle. Figure 19 The reference numeral CL in the accompanying drawings is one of the defining features of the invention.

[0095] By illustrating in detail the printing direction in the overlapping connection portion of the segmented image according to this invention, the variable weighting value of each gradient density value is assigned a concept. Figure 19 A more specific explanation follows.

[0096] Figure 19 Parts (A) and (B) respectively detail the changes in gradient printing density values ​​and their weighted values ​​in the overlapping regions GZ of the first segmented image PA and the second segmented image PB. In these figures, the hypotenuses SL1 and SL2 of the triangles represent linear gradient density ε lines based on the concept of a negative gradient where the ink density in the overlapping region GZ decreases linearly (linearly) from 100% to 0% as the first segmented image PA and the second segmented image PB are printed along their length direction. (This is in the implementation of the above...) Figure 13 , Figure 14 (The concept applicable to the disclosed printing process) is that, as the first segmented image PA and the second segmented image PA are printed along their length direction, the upper convex curve CL1 and the lower convex curve CL2 covering the hypotenuses SL1 and SL2 of the triangle are additionally added with variable ink concentrations δ1 and δ2 in their overlapping area GZ.

[0097] Numerous experiments and research results have confirmed that when the variation curve of the added ink concentration δ is curvilinear rather than linear, it significantly improves the problem of color concentration reduction areas (color concentration reduction lines) forming on the overlapping joints of the final printed material. Specifically, the optimal result is obtained when the lines CL1 and CL2 of the added ink concentration δ1 and δ2 have a nonlinear curve variation that gradually increases and gradually decreases along the printing direction on the linear gradient concentration ε1 and ε2 variation line. Mathematically, preferably, 110% < ε1 + δ1 + ε2 + δ2 < 170%.

[0098] Wherein, ε1 is the density value relative to the original image, which is the ink density value at the specified position in the first segmented image that decreases linearly (linearly) from 100% to 0% by a negative gradient line SL1 in the overlapping region GZ, expressed as a percentage; δ1 is the density value relative to the original image, which is the ink density value added to the ε1 value expressed as a percentage; ε2 is the density value relative to the original image, which is the ink density value at the specified position in the second segmented image that increases linearly (linearly) from 0% to 100% by a positive gradient line SL2 in the overlapping region GZ, expressed as a percentage; and δ2 is the density value relative to the original image, which is the ink density value added to the ε2 value expressed as a percentage.

[0099] The preferred value of ε1+δ1+ε2+δ2, expressed as a variable area range of 110% < ε1+δ1+ε2+δ2 < 170%, is as follows: For the assigned (additional) concentration weighting value δ, the number or form of the printed image colors is arbitrary (the types of original printed images are diverse), taking into account the variability in the form of the images to be printed. For example, preferably, a higher weighting value is assigned when the overlapping area image is closer to monochrome, and a lower weighting value is assigned when the overlapping area image is multicolored and has a more complex form. When considering this variability, a verticality of 110% < ε1+δ1+ε2+δ2 < 170% is derived.

[0100] On the other hand, Figure 18 Preferably, this invention applies to multiple unit images with relatively long lengths. Based on experimental results, the dimensions of the printing length direction widths W1 and W2 of the overlapping GZ are determined to be within the range of 5% to 50% of the overall printing length of the first segmented image PA or the second segmented image PB, preferably, at least 5 mm. Preferably, the printing length direction width of this overlapping region GZ is determined based on the following criteria: a larger width is set when the overlapping region GZ image is closer to monochrome, and a smaller width is used when the overlapping region image is multicolored and has a more complex shape.

[0101] Figure 20 As a diagram illustrating the continuous printing method for connecting digital printed images that can conceal the stitching lines applicable to the present invention, it shows the printing start position and printing end position of the overlapping connection portion of the first segmented printing portion and the second segmented printing portion using actual printed images.

[0102] Figure 20In the figure, P represents the overall unit image to be printed, and A and B represent the overlapping connection (C; D; GZ) where the unit image P is divided into two segmented images and applied to each printing end C and printing front end D. In the reference numerals, GZS1 and GZS2 indicate the positions where the gradient begins in each overlapping area (C; D; GZ) of the first segmented image A and the second segmented image B, that is, the starting lines for applying the gradient, and GZE1 and GZE2 indicate the positions where the gradient ends in each overlapping area (C; D; GZ) of the first segmented image A and the second segmented image B, that is, the lines where the gradient ends.

[0103] and Figure 20 same, Figure 21 This figure illustrates another actual printed image of a process using a digitally printed image that can conceal stitches, to connect continuous printing methods applicable to this invention. Figure 21 In the illustration, the content of unit image P is clearly defined by the black horizontal lines dividing the two figures (A) at the top and the old table and wine glass (B) at the bottom. Based on these horizontal lines, these can be considered as the first and second segmented images, respectively. In this case, the difference in brightness is significant, and the image content is precisely divided. Therefore, even if a stitching line is formed on the horizontal lines, it will not be visually apparent. However, when the length of the second segmented image on the lower side is greater than the circumference of the image plate, as shown in the figure, the overlapping area GZ of the overlapping printed segmented images can only be placed at the bottleneck position. Therefore, the applicable gradient pattern reference is as described above.

[0104] Figure 22 To show in printing Figure 21 The diagram shows the process of printing the first segmented image P(A) first, prioritizing printing, and the non-linear negative gradient printing pattern in its overlapping region GZ, as well as the working diagram of the digital printer engine core. Figure 23 To show in printing Figure 21 During the process of the unit image shown, it begins in Figure 22 A diagram showing the state of the digital printer engine core before nonlinear positive gradient printing in the overlapping region GZ of the second segmented image P(B) printed subsequently.

[0105] and, Figure 24 As shown in the connection Figure 22 and Figure 23 The figure shows the application of [method / technique] in the overlapping region GZ between the first segmented image P(A) and the second segmented image P(B). Figure 18 , Figure 19The diagram illustrates a nonlinear (i.e., weighted value assignment) complementary gradient method that stably hides suture lines and reduced print density areas in overlapping regions of segmented images, as well as a digital printing image connection continuous printing method.

[0106] Figure 25 As a second embodiment of the digital printing image connection continuous printing method of the present invention that can hide seams, compared with the embodiment described above where the gradient start and end of the overlapping connection portion is linear, the second embodiment is proposed for the following purpose: for waveform gradients, the printing density is changed along both width directions, thereby further reducing the gradient changes that can be perceived by the human eye, and as a result, the seam hiding effect can be further improved. In the case of linear gradient printing, compared with the possibility of staining due to overlap errors caused by fabric material and printing characteristics, the waveform gradient method connects the image in a way that visually disperses the stains and allows the colors of the image connection portion to connect as naturally as possible.

[0107] Figure 26 This diagram illustrates a preferred embodiment of the continuous printing method for connecting digital printed images that can conceal seams according to the present invention, where the waveform gradient pattern at the start and end of the gradient changes according to the degree of compositeness of the printed colors. Preferably, the more types of printed image colors there are in the overlapping connection portion, the closer the waveform pattern is to a straight line (e.g., in the case of 1), and the closer it is to a single color (e.g., in the case of 8), increasing the number of waveforms with alternating valleys and peaks.

[0108] Figure 27 In the second embodiment of the digital printing image connection continuous printing method of the present invention, which can hide the seam, the waveform gradient shape manifested in the connection part (overlapping area) can be a combination of multiple straight lines (types 1, 2, 3), free curves (types 5, 6, 7), etc., although not shown, it can also be a combination of straight lines and curves. The shape of this gradient pattern in the width direction of the printed fabric of the overlapping connection part can be determined by color analysis of the overlapping area image to be printed. The appropriate gradient shape based on the color analysis is automatically and semi-automatically selected through a process of comparing with preset database information.

[0109] On the other hand, the determination of gradient patterns requires a basic understanding of brightness, saturation, and hue, which will be briefly explained below. Figure 28 Parts (A), (B), and (C) are diagrams illustrating the concepts of brightness, saturation, and hue.

[0110] Brightness, along with color and saturation, is one of the three important attributes of color. Generally, low brightness is perceived as "dark," and high brightness as "bright." For example, it can be represented as "dark gray" or "light gray." As one of the sensory elements for distinguishing colors, besides reflectance, it represents the perceived brightness of the eye through color (the wavelength of light), such as... Figure 28 As shown in section (A), in the Munsell color system for representing object colors, black is 0, white is 10, and the gray levels are numbered and displayed sequentially, resulting in a total of 11 levels from 0 to 10 for brightness. Since colors are usually observed in contrast to other colors rather than seen alone, the brightness of a color can appear different depending on the relative colors. For example, even the same gray paper will appear lighter on black paper than on white paper. This phenomenon is called brightness contrast.

[0111] like Figure 28 As shown in section (B), saturation is an indicator of the lightness or darkness of a color. A color that is pure, clean, and close to its primary color, without any added color, is considered to have high saturation. For example, the red of a canna lily and the red of a red bean have similar brightness, but the canna lily's color is much clearer, thus its saturation is higher than that of the red bean. The closer a color is to a color in the spectrum, the higher its saturation; the color with the highest saturation among these colors is called the "pure color." White and black are called "achromatic colors" because they have no saturation.

[0112] And, as Figure 28 As shown in section (C), hue, as a concept combining the three attributes of color—brightness, saturation, and intensity—refers to the environment in which the brightness, darkness, strength, and shade of a color change according to the degree of brightness and saturation. Its English name is also called tone. For example, based on degree, a color's lightness or darkness is called a "light tone" or "dark tone," and based on clarity and turbidity, it is called a "clean tone" or "turbid tone." In a narrow sense, hue refers to the color created by mixing pure color with gray. In this case, hue is used as "light blue tone" or "dark blue tone," where light blue is a hue created by mixing pure color with white, and dark blue is a hue created by mixing pure color with black. Typically, hue is a "mid-tone."

[0113] The exquisite color reproduction of images in this type of printing is achieved through a raster image processor (RIP). A raster image processor, as output software for images used in word processors, database management programs, Photoshop, and other programs, is a device consisting of a computer chip and software that includes a microprocessor that converts vector graphics, text, or both into bitmap images. Color printing of physical objects can be performed using a raster image processor. It allows for free enlargement and reduction of data and achieves faster output speeds. It supports multiple fonts and offers various functions such as split-screen output. The main functions supported by raster image processor software include preventing damage to the original image based on the product, and providing functions such as tone adjustment, ink volume adjustment, and dot gain adjustment.

[0114] Figure 29 This diagram illustrates an example of the process flow of a continuous printing method for connecting digital printed images that can conceal stitching, in accordance with the present invention.

[0115] like Figure 29 As shown, the image connection continuous printing method of the present invention is performed as follows: when the printer 16 receives the image of the printing object from the terminal 12, it performs image separation surface color analysis 13. Based on the color analysis results, it determines the gradient shape 14 of the image separation surface and sets 15 the gradient overlap length of the image separation surface. The more colors and the more complex the shape of the image, the smaller the width will be used.

[0116] Figure 29 The following process flow diagram is used to print the determined gradient pattern through the test printer 16. The test printing results are used to read the overlapping images to study the printing quality 17, which examines whether there are stitching lines or stains. If the results are unsatisfactory, the process returns to setting the gradient shape on the image separation surface 14 and re-determines the gradient shape on the image separation surface. The overlap length is then reset 15 to prevent the generation of stitching lines. After the test process 17, when the quality is satisfactory, digital printing continues.

[0117] In the above processing, in the gradient pattern setting and gradient overlap length setting based on the color analysis of the image separation surface, the automatic analysis results of the brightness, saturation, number of hues and hue levels (differences in brightness and saturation levels) of the overlapping area image processed by the raster image processor are compared with the preset gradient pattern and overlap length database information and automatically set. When studying the printing quality 17, the setting of new patterns caused by poor quality is carried out semi-automatically with the addition of human judgment.

[0118] The process of determining this gradient pattern and overlap length (the process of determining the pattern determination variable) will be explained in more detail below, taking waveform gradient as the object of the second embodiment of the present invention. First, as the gradient pattern determination variable, the case with text (characters) in the overlap area and the case with only color and no characters will be explained.

[0119] 1. Does the overlapping area contain characters and their associated gradient patterns?

[0120] like Figure 30 Part (A) to Figure 30 As shown in section (E), the presence of text and its associated gradient within the overlapping area can be categorized into five cases. For example... Figure 30 As shown in section (A), overlapping printing is performed using a waveform gradient of all background images within the overlapping area that do not contain text or images, such as... Figure 30 As shown in section (B), when characters are present on all monochrome background images, a gradient is applied in a way that avoids the characters and forms a waveform on the background of the unit image, such as... Figure 30 Part (C) and Figure 30 As shown in section (D), when the background image is white, printing is performed on its white areas without a gradient. Furthermore, as... Figure 30 As shown in section (E), when the background color of the overlapping area is white, the method of generating overlapping lines to avoid the overlap of words is applicable, and only the overlapping lines are printed without wave gradient.

[0121] 2. Gradient forms when there are differences in brightness and saturation of colors

[0122] like Figure 31 Part (A) to Figure 31 As shown in section (E), the gradient forms when there are differences in the brightness and saturation of colors can be divided into four cases.

[0123] like Figure 31 As shown in section (A), an image with a boundary line having a brightness difference of more than 2 stages is subjected to waveform gradation along its boundary line. Figure 31 As shown in section (B), images with boundary lines exhibiting tonal differences within the same color are overprinted using a waveform gradient along their tonal boundary lines. Figure 31As shown in section (C), when the background image has clear boundary lines of two or more colors in straight or curved shapes, the overlapping area is printed using a straight or curved waveform gradient along its boundary lines. Furthermore, for photographic images, when the tonal difference is large or the number of colors is large, the waveform is increased inversely to the number of colors (the larger the tonal difference and the more colors, the smaller the waveform change) and a gradient is applied for overlapping printing.

[0124] On the other hand, as another variable determining the gradient pattern, the length of the overlapping area is specified, that is, the gradient overlap length is set as follows.

[0125] like Figure 32 As shown in section (A), all monochrome background images or photographic images are overprinted using waveform gradients. For monochrome images larger than 5mm, the longer the overlap length, the shorter the overlap length for more complex patterns or photographic images.

[0126] like Figure 32 As shown in section (B), in images with boundary lines exhibiting brightness differences of more than one stage, or in backgrounds with high brightness and near-white color, a linear overlapping gradient is applied along the boundary line. The higher the brightness, the shorter the overlap length; conversely, the lower the brightness and saturation, the longer the overlap length. Furthermore, as... Figure 32 As shown in section (C), when the background color is white, there is no gradient overlap interval. When there are words, the method of generating overlapping lines to make the words avoid overlapping is applicable. In the absence of gradient, only overlapping lines are printed.

[0127] The image classification categories exemplified above, used to illustrate and explain the principle of determining the gradient pattern of the overlapping area image to which the hidable stitching of the present invention's digital printing image connection continuous printing method applies, are merely illustrative examples for demonstrating and explaining the principle of the invention, and are not limited to such image classifications and their gradient pattern determination categories. The combinations of image classification categories (pattern determination variables) used to determine the gradient pattern of the overlapping area can be diverse and can be precisely distinguished as preset judgment data. When the hidable stitching of the present invention's digital printing image connection continuous printing method is applied, improvements in printing quality can be based on how precisely various combinations of image classification categories (pattern determination variables) used to determine the gradient pattern of the overlapping area are constructed.

[0128] The preferred embodiments of the present invention have been shown and described above, but the present invention is not limited to the specific embodiments described. Various modifications can be made by those skilled in the art without departing from the spirit of the invention as claimed in the claims. Such modifications should not be understood individually from the technical concept or vision of the present invention.

Claims

1. A digital printing image connection continuous printing apparatus, characterized in that, include: Unwinding rollers, unwinding printed fabric; A winding roller is used to wind the printed fabric after printing. A printing engine, disposed between the unwinding roller and the winding roller, includes a blanket that rotates in contact with an imaging plate and a printing roller that rotates in contact with the blanket; and The fabric orientation conversion mechanism converts the transport direction of the printing fabric passing between the blanket and the printing roller into either forward or reverse direction. When the transfer direction is positive, the printing engine prints a first segmented image including a first overlapping region on the first fabric of the printing fabric. When the transfer direction is negative, the first overlapping region printed on the first fabric is located below the second fabric of the printing fabric. When the transfer direction is positive, a second segmented image including a second overlapping region is printed on the second fabric to generate a unit image in which the first overlapping region overlaps with the second overlapping region.

2. The digital printing image connection continuous printing apparatus according to claim 1, characterized in that, When the printing of the first segmented image is completed, the fabric orientation conversion mechanism changes the conveying direction from the forward direction to the reverse direction, and moves the first fabric in the reverse direction until the starting position of the first overlapping area is located between the rubber blanket and the printing roller. When the movement is completed, the conveying direction is changed from the reverse direction to the forward direction.

3. The digital printing image connection continuous printing apparatus according to claim 1, characterized in that, The first overlapping region and the second overlapping region have the same size but different printing densities.

4. The digital printing image connection continuous printing apparatus according to claim 1, characterized in that, The first overlapping area is printed using a negative gradient process where the printing density decreases in an anti-correlated manner as the printing is performed. The second overlapping area is printed using a positive gradient printing method where the printing density increases logarithmically as the printing is performed.

5. The digital printing image connection continuous printing apparatus according to claim 1, characterized in that, Compared to the print density of the region in the first segmented image excluding the first overlapping region or the region in the second segmented image excluding the second overlapping region, the print density of the region where the first overlapping region overlaps with the second overlapping region is 110% to 170%.

6. A method for continuous printing of digital printing images, characterized in that, include: The process of unwinding printed fabric using unwinding rollers; The process of printing on the printed fabric using a printing engine; The fabric orientation conversion mechanism converts the transfer direction of the printing fabric between the blanket and the printing roller of the printing engine into a forward or reverse direction; and The process of winding the printed fabric onto a winding roller. The printing process on the fabric includes: When the conveying direction is positive, the process of printing a first segmented image including a first overlapping region on the first fabric of the printed fabric; When the transfer direction is the opposite, the process of ensuring that only the first overlapping area printed on the first fabric is located below the second fabric of the printed fabric; and When the transfer direction is positive, the process of printing a second segmented image including a second overlapping region on the second fabric to generate a unit image in which the first overlapping region overlaps with the second overlapping region.

7. The method for continuous printing of digital printed images according to claim 6, characterized in that, The process of changing the transfer direction of the printed fabric to forward or reverse includes: When the printing of the first segmented image is completed, the process of changing the transfer direction from the forward direction to the reverse direction is performed. The process of moving the first fabric in the opposite direction until the starting position of the first overlapping area is located between the blanket and the printing roller; and When the movement is completed, the process of changing the moving direction from the reverse direction to the forward direction.

8. The method for continuous printing of digital printed images according to claim 6, characterized in that, The first overlapping region and the second overlapping region have the same size but different printing densities.

9. The method for continuous printing of digital printed images according to claim 6, characterized in that, The first overlapping area is printed using a negative gradient process where the printing density decreases in an anti-correlated manner as the printing is performed. The second overlapping area is printed using a positive gradient printing method where the printing density increases logarithmically as the printing is performed.

10. The method for continuous printing of digital printed images according to claim 6, characterized in that, Compared to the print density of the region in the first segmented image excluding the first overlapping region or the region in the second segmented image excluding the second overlapping region, the print density of the region where the first overlapping region overlaps with the second overlapping region is 110% to 170%.

Images