Printing apparatus, printing method, printing program, and printing system

Abstract

The present invention provides a printing apparatus, printing method, printing program, and printing system capable of suppressing dot defects caused by faulty nozzles. [Solution] The printing apparatus includes a control device that performs a mask determination process which includes: a first generation process that generates a first partial mask with a predetermined pattern that minimizes the proportion of the faulty nozzles in the nozzle row, for a plurality of nozzles from a faulty nozzle to a nozzle end nozzle located at the nozzle row end closest to the faulty nozzle; a second generation process that generates a second partial mask for the nozzles in the nozzle row excluding the plurality of nozzles from a faulty nozzle to a nozzle end nozzle located at the nozzle row end closest to the faulty nozzle, by arranging one or more masks that form the same pattern as the first partial mask in order from the nozzle closest to the faulty nozzle; and a third generation process that generates a mask based on the first partial mask and the second partial mask.

Description

Technical Field

[0001] The present disclosure relates to, for example, a printing apparatus such as an inkjet printer, a printing method, a printing program, and a printing system.

Background Art

[0002] Conventionally, there is known a liquid droplet ejection apparatus that prints an image on a print medium by alternately repeating an ejection process of ejecting ink droplets onto the print medium to print dots based on image data and a conveyance process of conveying the print medium (Patent Document 1).

[0003] In the liquid droplet ejection apparatus, at least a part of a first scanning range on the print medium scanned by the ejection head in a first printing process is made to overlap with at least a part of a second scanning range on the print medium scanned by the ejection head in a second printing process. In this case, the plurality of nozzles constituting the nozzle array are divided into three parts: an upstream portion in the conveyance direction, a downstream portion located further downstream than the upstream portion, and a central portion located between the upstream portion and the downstream portion. The printing rate of the nozzles in the central portion is 50%, the printing rate of the nozzles in the upstream portion changes linearly at a predetermined reduction rate from 50% to 0% toward one side of the conveyance direction according to the position in the conveyance direction, and the printing rate of the nozzles in the downstream portion changes linearly at a predetermined reduction rate from 50% to 0% toward the other side of the conveyance direction according to the position in the conveyance direction.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, if a defective nozzle occurs in a droplet ejection device, the defective nozzle may not be able to properly land droplets in the area where it is supposed to eject, potentially resulting in dot defects. Therefore, in order to suppress dot defects caused by defective nozzles in the conventional droplet ejection device described above, it is conceivable to compensate for the image by increasing the printing rate of another normal nozzle corresponding to the position of the defective nozzle in a different ejection step from the ejection step to which the defective nozzle belongs among the multiple ejection steps corresponding to a unit area. However, with the above method, if there is a deviation in the amount of transported material to be printed or a deviation in the landing position of droplets ejected by the other nozzle, the image cannot be compensated for, resulting in dot defects and, consequently, linear banding caused by such dot defects.

[0006] Therefore, the present disclosure aims to provide a printing apparatus, printing method, printing program, and printing system capable of suppressing dot defects caused by faulty nozzles. [Means for solving the problem]

[0007] The printing apparatus of this disclosure comprises a discharge head having a nozzle row in which a plurality of nozzles for discharging droplets onto a printing medium transported in a predetermined transport direction based on image data are arranged along a predetermined nozzle row direction, and a control device, wherein the control device performs a printing process in which a first print pass and a second print pass performed after the first print pass partially overlap each other in the transport direction, a discharge failure detection process for detecting a defective nozzle from among the plurality of nozzles in the nozzle row, and a mask determination process for determining a mask relating to the distribution ratio of droplet discharge amounts in the first print pass and the second print pass for the plurality of nozzles in the nozzle row according to the defective nozzle, and the mask determination process The process includes: a first generation process that generates a first partial mask with a predetermined pattern for a plurality of nozzles in the nozzle row, from the defective nozzle to the end nozzle located at the nozzle row end closer to the defective nozzle, so that the proportion of the defective nozzle is minimized; a second generation process that generates a second partial mask for the nozzles in the nozzle row, excluding the plurality of nozzles from the defective nozzle to the end nozzle located at the nozzle row end closer to the defective nozzle, by arranging one or more masks that have the same pattern as the first partial mask in order from the nozzle closest to the defective nozzle; and a third generation process that generates the mask based on the first partial mask and the second partial mask.

[0008] According to this disclosure, a mask is generated based on a first partial mask with a predetermined pattern that minimizes the proportion of defective nozzles, and a second partial mask which has one or more masks with the same pattern as the first partial mask. Therefore, even if a defective nozzle occurs in the nozzle row and there is a deviation in the amount of material to be printed or a deviation in the landing position of droplets ejected by a nozzle other than the defective nozzle, dot defects are suppressed or prevented. Thus, linear banding caused by dot defects is also suppressed or prevented. [Effects of the Invention]

[0009] According to this disclosure, it is possible to provide a printing apparatus, printing method, printing program, and printing system that can suppress dot defects caused by faulty nozzles. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a plan view showing the configuration of a printing apparatus according to one embodiment. [Figure 2] Figure 2 is a block diagram showing the configuration of the control system of the printing apparatus shown in Figure 1. [Figure 3] Figure 3 shows the nozzle array in the discharge head shown in Figure 1. [Figure 4] Figure 4 is a schematic diagram showing the configuration for performing the dispensing failure detection process. [Figure 5] Figure 5A is a conceptual diagram showing an example of the distribution ratio of ink droplet ejection volume based on the mask in each print pass in single-ring printing, Figure 5B shows the numbers of defective nozzles in the nozzle row, and Figure 5C is a conceptual diagram showing an example of the distribution ratio of ink droplet ejection volume based on the mask, modified from Figure 5A. [Figure 6] Figures 6A and 6B are conceptual diagrams showing examples of the distribution ratio of discharge volume. [Figure 7] Figures 7A and 7B are conceptual diagrams showing examples of the distribution ratio of discharge volume. [Figure 8] Figures 8A and 8B are conceptual diagrams showing examples of the distribution ratio of discharge volume. [Figure 9] Figure 9A is a conceptual diagram showing an example of a distribution ratio with three bell-shaped patterns, Figure 9B is a conceptual diagram showing an example of a distribution ratio with two bell-shaped patterns, Figure 9C is a conceptual diagram showing an example of a distribution ratio with one bell-shaped pattern, and Figure 9D is a conceptual diagram showing an example of a distribution ratio with three bell-shaped patterns. [Figure 10] Figure 10A shows that the number of a defective nozzle in the nozzle row direction is denoted as m, and Figure 10B is a graph showing the number of usable nozzles corresponding to the number of defective nozzles for each number of mountain-shaped patterns. [Figure 11]Figure 11A is a graph showing that the number m of the nozzle with a discharging defect is in the first range, and Figure 11B is a diagram showing the mountain-shaped pattern adopted when the number m in Figure 11A is in the first range. [Figure 12] Figure 12A is a graph showing that the number m of the nozzle with a discharging defect falls within the second range, and Figure 12B shows the mountain-shaped pattern adopted when the number m in Figure 12A falls within the second range. [Figure 13] Figure 13A is a graph showing that the number m of the dispensing nozzle is in the third range, and Figure 13B is a diagram showing the mountain-shaped pattern adopted when the number m in Figure 13A is in the third range. [Figure 14] Figure 14A is a graph showing that the number m of the faulty nozzle is in the fourth range, and Figure 14B shows the mountain-shaped pattern adopted when the number m in Figure 14A is in the fourth range. [Figure 15] Figure 15A is a graph showing that the number m of the discharging nozzle is in the fifth range, and Figure 15B shows the mountain-shaped pattern adopted when the number m in Figure 15A is in the fifth range. [Figure 16] Figure 16A is a graph showing that the number m of the discharging nozzle is in the 6th range, and Figure 16B is a diagram showing the mountain-shaped pattern adopted when the number m in Figure 16A is in the 6th range. [Figure 17] Figure 17A is a graph showing that the number m of the discharging nozzle is in the 7th range, and Figure 17B shows the mountain-shaped pattern adopted when the number m in Figure 17A is in the 7th range. [Figure 18] Figure 18A is a graph showing that the number m of the dispensing nozzle is in the 8th range, and Figure 18B is a diagram showing the mountain-shaped pattern adopted when the number m in Figure 18A is in the 8th range. [Figure 19] Figure 19 illustrates the number of mountain-shaped patterns used when the number m of the defective nozzle is, for example, 110. [Figure 20]FIG. 20A is a conceptual diagram showing 1500-pin print data, FIG. 20B is a conceptual diagram showing the required number of print passes when printing based on the print data of FIG. 20A with m=110 and one peak adopted, and FIG. 20C is a conceptual diagram showing the required number of print passes when printing based on the print data of FIG. 20A with m=110 and three peaks adopted. [Figure 21] FIG. 21 is a diagram showing an example in which a plurality of ejection-defective nozzles are detected in a nozzle array. [Figure 22] FIG. 22 is a flowchart showing an example of a processing flow in a printing apparatus. [Figure 23] FIG. 23 is a flowchart showing an example of a subroutine related to mask determination processing in FIG. 22. [Figure 24] FIG. 24 is a flowchart showing an example of a subroutine related to mask determination processing that follows FIG. 23. [Figure 25] FIG. 25 is a flowchart showing an example of a processing flow in a printing apparatus. [Figure 26] FIG. 26 is a block diagram showing a printing system including a printing apparatus and a processing apparatus. [Modes for Carrying Out the Invention]

[0011] Hereinafter, a printing apparatus according to an embodiment of the present disclosure will be described with reference to the drawings. The printing apparatus described below is merely one embodiment of the present disclosure. Accordingly, the present disclosure is not limited to the following embodiments, and additions, deletions, and modifications can be made without departing from the gist of the present disclosure. Note that, in the following, the same or corresponding elements are denoted by the same reference numerals throughout all the drawings, and redundant descriptions are omitted unless otherwise specified.

[0012] Figure 1 is a plan view showing the configuration of a printing apparatus 100 according to one embodiment. Figure 2 is a block diagram showing the configuration of the control system of the printing apparatus 100 in Figure 1. Figure 3 is a diagram showing the nozzle row NL in the ejection head 23 in Figure 1. In Figures 1 and 3, mutually orthogonal directions are referred to as the first direction D1 and the second direction D2. In this embodiment, for example, the first direction D1 is the direction of movement of the carriage 41 described later. The second direction D2 is the direction of transport of the printing medium W. In the following description, D1 will be referred to as the direction of movement and D2 as the transport direction. However, the above directions are illustrative and not limiting.

[0013] The printing device 100 is, for example, a serial head type inkjet printer. Based on the print data, the printing device 100 alternately repeats a pass process in which ink droplets are ejected while moving the inkjet head (hereinafter referred to as the head) 20 in the movement direction D1, and a transport process in which the printing medium W is transported in the transport direction D2. As a result, a predetermined image is printed on the printing medium W. Examples of the printing medium W include printing paper, cloth, and sheet-fed film.

[0014] The printing apparatus 100 comprises a plurality of ejection heads 20, a platen 11, a plurality of tanks 12, a transport device 30, a moving device 40, a receiving section 54, a cap 57, and a housing 101.

[0015] The ejection head 20 prints an image onto the printing medium W using predetermined ink droplets based on the print data. Examples of multiple ejection heads 20 include ejection head 21, ejection head 22, and ejection head 23. However, ejection heads 21 and 22 are not essential in the printing apparatus 100. The ejection heads 21, 22, and 23 are arranged in parallel in the order of ejection head 21, ejection head 22, and ejection head 23 from one side in the transport direction D2. For example, ejection head 21 prints on the printing medium W with white ink, ejection head 22 prints on the printing medium W with spot color ink, and ejection head 23 prints on the printing medium W with color ink.

[0016] The platen 11 supports the printing medium W. The platen 11 defines the distance between the printing medium W it supports and the nozzle surface of the ejection head 20 positioned opposite the printing medium W. The platen 11 moves back and forth, for example, in the transport direction D2. As a result, the printing medium W supported by the platen 11 is transported in the transport direction D2.

[0017] Each tank 12 stores ink. Tanks 12 are connected to the discharge head 20 via the flow path described below to supply ink to the discharge head 20. The number of tanks 12 is equal to or greater than the number of ink types. For example, tank 12 has four first tanks 12a each storing four types of color ink, one or more second tanks 12b each storing white ink, and one or more third tanks 12c each storing spot color ink. Examples of color inks include cyan ink, magenta ink, yellow ink, and black ink. Examples of spot color inks include orange ink, green ink, and red ink. Note that if discharge heads 21 and 22 are not provided, the second tanks 12b and third tanks 12c are not necessary.

[0018] The first tank 12a is connected to the ejection head 23 via the first channel 13a. Color ink is supplied from the first tank 12a to the ejection head 23 via the first channel 13a. The second tank 12b is connected to the ejection head 21 via the second channel 13b. White ink is supplied from the second tank 12b to the ejection head 21 via the second channel 13b. The third tank 12c is connected to the ejection head 22 via the third channel 13c. Special color ink is supplied from the third tank 12c to the ejection head 22 via the third channel 13c.

[0019] The conveying device 30 includes, for example, a drive unit including a ball screw or rack and pinion (not shown) and a conveying motor 32. The drive unit is connected to the conveying motor 32. The rotational movement of the conveying motor 32 causes the platen 11 to move in the conveying direction D2 by the drive unit, and the printing medium W is conveyed in the conveying direction D2.

[0020] The moving device 40 includes a carriage 41, a pair of guide rails 42, a moving motor 43, and an endless belt 44. The pair of guide rails 42 extend in the direction of movement D1 above the platen 11 so as to sandwich the carriage 41 in the conveying direction D2. The carriage 41 supports each discharge head 20. The carriage 41 is supported by the pair of guide rails 42 so as to be movable in the direction of movement D1. The endless belt 44 extends in the direction of movement D1 and is attached to the carriage 41 and is attached to the moving motor 43 via a pulley 45. The rotation of the moving motor 43 operates the endless belt 44, causing the carriage 41 to reciprocate along the guide rails 42 in the direction of movement D1, which is perpendicular to the conveying direction D2. As a result, each discharge head 20 reciprocates in the direction of movement D1.

[0021] The receiving portion 54 is positioned on one end of the guide rail 42 in the direction of movement D1 such that it overlaps with the movement area along the direction of movement D1 of the carriage 41. The receiving portion 54 receives ink droplets discharged from the discharge head 20 by a flushing process performed by the carriage 41, which positions the discharge head 20 above the receiving portion 54. The ink droplets discharged to the receiving portion 54 are drained through a pipe (not shown) connected to the receiving portion 54.

[0022] The cap 57 is positioned on the other end of the guide rail 42 in the direction of movement D1 such that it overlaps with the movement area along the direction of movement D1 of the carriage 41. The cap 57 covers the nozzle surface of the discharge head 20 and receives ink droplets discharged from the discharge head 20 during the purging process. The ink droplets discharged to the cap 57 are drained through a pipe (not shown) connected to the cap 57.

[0023] As shown in Figure 2, the printing apparatus 100 further includes a control device 50, a head drive circuit 26, a transport drive circuit 33, a movement drive circuit 46, a maintenance drive circuit 47, a maintenance device 55, a display unit 14, and an input unit 15.

[0024] The control device 50 has an interface 51, an arithmetic unit 52, and a storage unit 53. The control device 50 corresponds to the computer, printing means, ejection defect detection means, mask determination processing means, first generation processing means, second generation processing means, and third generation processing means of this disclosure. The interface 51 receives various data such as image data from an external device 200, such as a personal computer or a reader. The image data is raster data showing an image to be printed on the printing medium W, and includes information indicating various printing conditions, including the type of the printing medium W. The control device 50 may consist of a single device, or multiple devices may be distributed and configured to cooperate in the operation of the printing device 100.

[0025] The arithmetic unit 52 includes at least one circuit, such as a processor like a CPU and an integrated circuit like an ASIC. The arithmetic unit 52 controls each part by executing a printing program and performs various processes such as printing.

[0026] The storage unit 53 is a memory accessible from the arithmetic unit 52 and includes RAM and ROM. The RAM temporarily stores various types of data, such as data received from an external device 200, such as image data, and data converted by the arithmetic unit 52. The ROM stores print programs and predetermined data for various data processing. The print program executed in the printing device 100 is stored in the storage unit 53 via the external device 200 from a storage medium, such as a CD-ROM, that can be read by the external device 200 acting as a reader. Alternatively, the print program may be downloaded from the internet or the like and stored in the storage unit 53.

[0027] The ejection head 20 is, for example, a piezoelectric element and has a drive element 25 provided for each nozzle. The head drive circuit 26 is electrically connected to the drive element 25. The head drive circuit 26 generates a drive signal in response to instructions from the control device 50 and outputs it to the drive element 25. In response to the drive signal, the drive element 25 applies ejection pressure to the ink in a pressure chamber (not shown in the figure) to eject ink droplets from the nozzle. As a result, ink droplets are ejected from the nozzle.

[0028] The transport drive circuit 33 is electrically connected to the transport motor 32. The transport drive circuit 33 generates a drive signal in response to instructions from the control device 50 and outputs it to the transport motor 32. The transport motor 32 drives the drive unit in response to the drive signal. As a result, the platen 11 moves in the transport direction D2.

[0029] The mobile drive circuit 46 is electrically connected to the mobile motor 43. The mobile drive circuit 46 generates a drive signal in response to instructions from the control device 50 and outputs it to the mobile motor 43. The mobile motor 43 drives the endless belt 44 in response to the drive signal. As a result, the carriage 41 moves back and forth along the guide rail 42 in the direction of movement D1.

[0030] The maintenance device 55 has a pump motor 56 connected to a pump (not shown) in addition to the cap 57 described above. The maintenance drive circuit 47 is electrically connected to the pump motor 56. The maintenance drive circuit 47 generates a drive signal in response to instructions from the control device 50 and outputs it to the pump motor 56. The pump motor 56 drives the pump in response to the drive signal. As a result, a purging process is performed in which ink is discharged from the nozzle 121 of the discharge head 20 by driving the pump motor 56 to discharge the pump while the nozzle surface of the discharge head 20 is covered with the cap 57.

[0031] The display unit 14 is, for example, a display, which displays images related to image data according to instructions from the control device 50. The input unit 15 is, for example, a button, which is operated by the user. The input unit 15 may be a touch panel integrated with the display unit 14.

[0032] As shown in Figure 3, the ejection head 23 has multiple nozzle rows NL in which multiple nozzles 121 are arranged at predetermined intervals in a predetermined nozzle row direction Dn, ejecting ink droplets onto the printing medium W being transported in the transport direction D2 based on image data. The nozzle row direction Dn is, for example, a direction parallel to the transport direction D2. The multiple nozzle rows NL consist of, for example, nozzle row NL1, nozzle row NL2, nozzle row NL3, and nozzle row NL4.

[0033] Each nozzle row NL is arranged at a predetermined interval in the direction of movement D1. A nozzle row NL includes a first nozzle row and a second nozzle row. The first nozzle row is a nozzle row NL corresponding to the first color of the ink droplet, and is one of nozzle rows NL1, NL2, NL3, and NL4. The second nozzle row is a nozzle row NL corresponding to the second color of the ink droplet, and is a different nozzle row NL from the first nozzle row among nozzle rows NL1, NL2, NL3, and NL4. In this embodiment, the nozzle 121 of nozzle row NL1 ejects, for example, a droplet of cyan ink. The nozzle 121 of nozzle row NL2 ejects, for example, a droplet of magenta ink. The nozzle 121 of nozzle row NL3 ejects, for example, a droplet of yellow ink. The nozzle 121 of nozzle row NL4 ejects, for example, a droplet of black ink.

[0034] Figure 4 is a schematic diagram showing the configuration for performing the ejection failure detection process. As shown in Figure 4, an electrode 54a is provided facing the ejection head 23. The electrode 54a is positioned, for example, on a receiving portion 54. In this configuration, the control device 50 ejects ink droplets from the ejection head 23 while a potential difference is created between the ejection head 23 and the electrode 54a. At this time, a charge corresponding to the inherent charge amount of the ink droplet is induced in the ejection head 23 and the electrode 54a, respectively. As a result, a current corresponding to the difference between the charge amount induced in the ejection head 23 and the charge amount induced in the electrode 54a flows between the ejection head 23 and the electrode 54a. This current is detected by an ammeter 54b. Based on the current detected by the ammeter 54b, the control device 50 performs an ejection failure detection process to detect a defective nozzle Nf (Figure 5B below) from among the multiple nozzles 121 of the nozzle row NL. Such an ejection failure detection process may be performed only on the nozzles 121 of the nozzle row NL being used among the multiple nozzle rows NL of the ejection head 23. In this embodiment, a nozzle Nf with a faulty ejection function refers to a nozzle 121 that is clogged and unable to eject ink due to an increase in ink viscosity, a nozzle 121 that ejects less ink than the specified amount, or a nozzle 121 whose ejected ink droplets land on the printing medium W at a position different from the specified position.

[0035] Figure 5A is a conceptual diagram showing an example of the distribution ratio of ink droplet ejection volume based on the mask in each print pass in single-ring printing, Figure 5B shows the nozzle number of the defective nozzle Nf in the nozzle row, and Figure 5C is a conceptual diagram showing an example of the distribution ratio of ink droplet ejection volume based on the mask, modified from Figure 5A.

[0036] In this embodiment, as shown in Figure 5A, the control device 50 performs a printing process that performs single-ring printing in which the first print pass and the second print pass performed after the first print pass partially overlap each other in the transport direction D2 (or nozzle row direction Dn). Furthermore, in single-ring printing, the control device 50 causes the second print pass and the third print pass performed after the second print pass to partially overlap each other in the transport direction D2. In this way, the control device 50 performs double single-ring printing, which is single-ring printing in which a portion of one print pass (e.g., the second print pass) overlaps with both the preceding print pass (e.g., the first print pass) and the following print pass (e.g., the third print pass) with respect to that one print pass. The double single-ring printing is also performed from the fourth print pass onward.

[0037] In this embodiment, the control device 50 generates a mask for a plurality of nozzles 121 in the nozzle row NL, relating to the proportion of ink droplet ejection amounts in the first and second print passes. In Figure 5A, the mask is generated corresponding to one print pass such that the pattern of the proportion of ink droplet ejection amounts in each print pass is a mountain-shaped pattern Dg, which is a gradient of different proportions. That is, the mountain-shaped pattern Dg is configured such that the proportion of ejection amounts gradually differs in the nozzle row direction Dn. Specifically, in the mountain-shaped pattern Dg, the proportion of ejection amount from the nozzle located in the center of the nozzle row direction Dn among the nozzles constituting one print pass is the largest. In addition, in the mountain-shaped pattern Dg, with respect to the nozzle located in the center, the proportion of ejection amount of each nozzle gradually decreases toward the nozzle located at one end of the nozzle row direction Dn among the nozzles constituting the print pass, and the proportion of ejection amount of each nozzle gradually decreases toward the nozzle located at the other end of the nozzle row direction Dn. In the following explanation, single-ring printing performed based on a mask relating to the mountain-shaped pattern Dg as the distribution ratio pattern may be referred to as gradient single-ring printing.

[0038] In the singling region, which is the area where one print path and the other print path overlap, the sum of the proportion of the ejection volume handled by the nozzles in one print path and the proportion of the ejection volume handled by the nozzles in the other print path at the same position in the nozzle row direction Dn as the nozzles in the one print path is 100%. In other words, in the singling region, the proportion of the ejection volume handled by one print path and the proportion of the ejection volume handled by the other print path are complementary.

[0039] Here, the control device 50 performs a mask determination process to determine a mask relating to the distribution ratio of ink droplet ejection amounts in the first and second print passes for multiple nozzles 121 in the nozzle row NL, according to the nozzle number of the defective nozzle Nf (in other words, its position in the nozzle row direction Dn). As a result, the mask before the execution of the mask determination process is changed according to the defective nozzle Nf. For example, suppose that when the number of nozzles 121 constituting the nozzle row NL is 420, the 280th nozzle from one end in the nozzle row direction Dn (the upper end in Figure 5B; the same applies hereafter) is detected as a defective nozzle Nf, as shown in Figure 5B. In this case, the mask relating to the distribution ratio in Figure 5A is changed to a mask consisting of three partial masks relating to three mountain-shaped patterns Dg, as shown in Figure 5C. Note that each nozzle 121 in the nozzle row NL is assigned an integer nozzle number starting from 1, starting from the nozzle 121 located at one end in the nozzle row direction Dn.

[0040] The details of the mask determination process will be explained with reference to Figures 5B and 5C. In the mask determination process, the control device 50, in principle, executes the following first generation process, second generation process, and third generation process.

[0041] In the first generation process, the control device 50 identifies multiple nozzles 121 in the nozzle row NL, from the defective nozzle Nf shown in Figure 5B to the end nozzle Ne located at the nozzle row end NLe closest to the defective nozzle Nf. In this case, a total of 140 nozzles 121 (hereinafter referred to as the first nozzle group) are identified, from the 281st nozzle 121 following the defective nozzle Nf, which is the 280th nozzle 121, to the 420th nozzle 121. The control device 50 then generates a first partial mask of a predetermined pattern relating to the mountain-shaped pattern Dg shown in Figure 5C, which minimizes the proportion of the defective nozzle Nf that is used (for example, 0%). As a result, the control device 50 designates the defective nozzle Nf as an unused nozzle Nn.

[0042] In the second generation process, the control device 50 identifies nozzles 121 from the nozzle row NL, excluding multiple nozzles 121 from the defective nozzle Nf to the nozzle row end nozzle Ne located at the nozzle row end NLe closer to the defective nozzle Nf. In this case, the same number of nozzles 121 identified in the first generation process (i.e., 140 nozzles) are identified, totaling 140 nozzles 121 from the 280th defective nozzle Nf to the 141st nozzle 121 (hereinafter referred to as the second nozzle group). In addition, the same number of nozzles 121 identified in the first generation process (i.e., 140 nozzles) are identified, totaling 140 nozzles 121 from the 140th nozzle 121 to the 1st nozzle 121 (hereinafter referred to as the third nozzle group). Then, as shown in Figure 5C, the control device 50 generates a second partial mask for the second nozzle group and the third nozzle group, including the identified nozzle 121, by arranging one or more masks that form the same pattern as the first partial mask of a predetermined pattern relating to the mountain-shaped pattern Dg, starting from the nozzle 121 in the second nozzle group that is closer to the nozzle Nf with the discharge defect.

[0043] In the third generation process, the control device 50 generates the mask based on the first partial mask and the second partial mask. As a result, a mask is generated corresponding to one print pass, which is a combination of the first partial mask and the second partial mask, which has two masks (i.e., a mask relating to the second nozzle group and a mask relating to the third nozzle group). In this embodiment, there are cases in which a total of two partial masks are generated, namely the first partial mask and one second partial mask (first case), and cases in which a total of three partial masks are generated, namely the first partial mask and two second partial masks (second case). In both the first and second cases, the first partial mask in one print pass and the partial mask in the other print pass corresponding to the first partial mask have a complementary relationship such that the sum of their respective contributions to the discharge amount is 100%. Also, in both the first and second cases, the second partial mask in one print pass and the partial mask in the other print pass corresponding to the second partial mask have a complementary relationship such that the sum of their respective contributions to the discharge amount is 100%.

[0044] Next, we will explain, with reference to several examples, the proportion of the discharge volume that can be adopted in the mask determination process of this embodiment. Figures 6A and 6B are conceptual diagrams showing examples of the proportion of the discharge volume. Figures 7A and 7B are conceptual diagrams showing another example of the proportion of the discharge volume. Figures 8A and 8B are conceptual diagrams showing yet another example of the proportion of the discharge volume.

[0045] The distribution ratio of the discharge volume shown in Figure 6A is the same as the distribution ratio of the discharge volume shown in Figure 5A above. In Figure 6A, the distribution ratio of the discharge volume at the position between the first print pass and the third print pass (i.e., the valley) is 0%. On the other hand, in the nozzle row direction Dn, the distribution ratio of the discharge volume at the same position as the valley in the second print pass is 100%.

[0046] The distribution pattern shown in Figure 6B is composed of a combination of two partial distribution patterns. In this case, the two partial distribution patterns include a strip-shaped pattern Dc that is constant at a predetermined value across the nozzle row direction Dn, and a mountain-shaped pattern Dg. The distribution in the strip-shaped pattern Dc is, for example, 30%. Therefore, the distribution of the discharge amount at the position between the first print pass and the third print pass (i.e., the valley) is 30%. Also, the distribution at the maximum part of the mountain-shaped pattern Dg is, for example, 40%. Therefore, the total distribution value at the position where the mountain-shaped pattern Dg is at its maximum (i.e., the sum of the distribution of the strip-shaped pattern Dc and the distribution of the mountain-shaped pattern Dg at that position) is 70%. Furthermore, as described above, in the singling region, the distribution in one print pass and the distribution in the other print pass are complementary, and the sum of both distributions is 100%. Therefore, the sum of the 30% share at the position between the first and third print passes (i.e., the valley) and the 70% share in the second print pass at the same position as the valley in the nozzle row direction Dn is 100%.

[0047] Next, an example of the distribution ratio of the ejection amount when there is a defective nozzle Nf is as follows. The distribution ratio pattern shown in Figure 7A, like Figure 5C above, includes three mountain-shaped patterns Dg assigned to each of the first to third nozzle groups. In the singleing region in Figure 7A, the distribution ratio of the defective nozzle Nf in one print pass is 0%, and the distribution ratio of nozzle 121 in the other print pass at the same position as the defective nozzle Nf in the nozzle row direction Dn is 100%.

[0048] The distribution pattern shown in Figure 7B includes three strip-shaped patterns Dc and three mountain-shaped patterns Dg assigned to each of the first to third nozzle groups. The distribution ratios in the strip-shaped patterns Dc and the distribution ratios at the maximum part of the mountain-shaped patterns Dg are the same as in Figure 6B. In the singleing region in Figure 7B, the distribution ratio of the defective nozzle Nf in one print pass is 0%, and the distribution ratio of the nozzle 121 in the other print pass at the same position as the defective nozzle Nf in the nozzle row direction Dn is 70%.

[0049] The distribution pattern shown in Figure 8A includes three strip-shaped patterns Dc and three mountain-shaped patterns Dg assigned to each of the first to third nozzle groups. The distribution ratio for the strip-shaped patterns Dc is, for example, 5%. The distribution ratio at the maximum part of the mountain-shaped patterns Dg is, for example, 90%. Therefore, the sum of the distribution ratios at the position where the mountain-shaped patterns Dg are maximum (i.e., the sum of the distribution ratios of the strip-shaped patterns Dc and the mountain-shaped patterns Dg at that position) is 95%. In the singleing region in Figure 8A, the distribution ratio of the defective nozzle Nf in one print path is 0%, and the distribution ratio of nozzle 121 in the other print path at the same position as the defective nozzle Nf in the nozzle row direction Dn is 95%.

[0050] The distribution pattern shown in Figure 8B includes three strip-shaped patterns Dc assigned to each of the first to third nozzle groups, and three mountain-shaped patterns Dg having a convex pattern Dc1. The distribution ratios for the strip-shaped patterns Dc and the distribution ratios for the mountain-shaped patterns Dg excluding their maximum portions are the same as in Figure 7B. The convex pattern Dc1 is located at the maximum portion of the mountain-shaped patterns Dg, and its distribution ratio is 30%. Therefore, the total distribution ratio at the location where the convex pattern Dc1 exists (i.e., the sum of the distribution ratio of the strip-shaped patterns Dc at that location and the distribution ratio of the mountain-shaped patterns Dg including the convex pattern Dc1) is 100%. In the singleing region shown in Figure 8B, the proportion of defective nozzles Nf in one print pass is 0%, while the proportion of nozzles 121 in the other print pass at the same position as the defective nozzles Nf in the nozzle row direction Dn is 100%.

[0051] Next, we will explain, with examples, the number of bell-shaped patterns Dg for the distribution ratio determined according to the nozzle number (position in the nozzle row direction Dn) of the defective nozzle Nf. Figure 9A is a conceptual diagram showing an example of a distribution ratio having three bell-shaped patterns Dg, Figure 9B is a conceptual diagram showing an example of a distribution ratio having two bell-shaped patterns Dg, Figure 9C is a conceptual diagram showing an example of a distribution ratio having one bell-shaped pattern Dg, and Figure 9D is a conceptual diagram showing another example of a distribution ratio having three bell-shaped patterns Dg.

[0052] The example in Figure 9A is the same as the example in Figure 5C described above. That is, if the 280th nozzle 121 is a defective nozzle Nf, the pattern for the distribution ratio includes three mountain-shaped patterns Dg.

[0053] As shown in the example in Figure 9B, if the 215th nozzle 121 is a defective nozzle Nf, the distribution pattern includes two mountain-shaped patterns Dg, namely, a mountain-shaped pattern Dg corresponding to the first nozzle group and a mountain-shaped pattern Dg corresponding to the second nozzle group. The first nozzle group includes a total of 206 nozzles 121, from the 215th defective nozzle Nf to the 420th nozzle 121, which is the row end nozzle Ne. The second nozzle group has the same number of nozzles as the first nozzle group, as described above, and includes a total of 206 nozzles 121, from the 214th nozzle 121 to the 9th nozzle. Therefore, the mountain-shaped pattern Dg is not assigned to the 8 nozzles 121, from the 8th nozzle 121 to the 1st nozzle 121. In other words, the mask as the second partial mask is not applied to these 8 nozzles 121. In this case, the control device 50 designates the nozzles 121 to which the mask is not applied as unused nozzles Nn.

[0054] As shown in the example in Figure 9C, if the 400th nozzle 121 is a defective nozzle Nf, the control device 50 exceptionally does not perform the first and second generation processes described above. In this case, one mountain-shaped pattern Dg is assigned to a total of 400 nozzles 121, from the 1st nozzle 121 to the 400th defective nozzle Nf. Therefore, the mountain-shaped pattern Dg is not assigned to a total of 20 nozzles 121, from the 401st nozzle 121 to the 420th nozzle 121. In other words, the mask is not applied to these 20 nozzles 121. In this case, the control device 50 designates the nozzles 121 to which the mask is not applied as unused nozzles Nn.

[0055] As shown in the example in Figure 9D, if the 160th nozzle 121 is a defective nozzle Nf, the distribution pattern includes three mountain-shaped patterns Dg, namely, a mountain-shaped pattern Dg corresponding to the first nozzle group, a mountain-shaped pattern Dg corresponding to the second nozzle group, and a mountain-shaped pattern Dg corresponding to the third nozzle group. Here, if the first and second generation processes described above are performed according to the principle, the nozzle groups to which the mountain-shaped patterns Dg can be assigned are limited to two: the first nozzle group and the second nozzle group, which has the same number of nozzles as the first nozzle group. In this case, the first nozzle group consists of a total of 160 nozzles 121, from the 160th defective nozzle Nf to the 1st nozzle 121. The second nozzle group consists of a total of 160 nozzles 121, from the 161st nozzle 121 to the 320th nozzle 121. Therefore, in gradient single-printing, a total of 100 nozzles 121, from the 321st nozzle 121 to the 420th nozzle 121, which cannot be assigned the same mountain-shaped pattern Dg as the first and second nozzle groups, will be unused. As a result, the number of print passes will increase, increasing the printing time, and the risk of ejection failure will increase due to the solidification of ink in the unused nozzles 121. Therefore, exceptionally, the first and second generation processes described above will not be executed. Thus, as shown in Figure 9D, the mountain-shaped pattern Dg is assigned to a nozzle group containing a total of 130 nozzles 121 from the 161st defective nozzle Nf to the 290th nozzle 121, and to a nozzle group having the same number of nozzles 121 as the nozzle group, which contains a total of 130 nozzles 121 from the 291st nozzle 121 to the 420th nozzle 121. In addition, a nozzle group having the same number of nozzles as the two nozzle groups is provided, and a mountain-shaped pattern Dg is assigned to a total of 130 nozzles 121, from the 160th defective nozzle Nf to the 31st nozzle 121. In this case, a total of 30 nozzles 121, from the 30th nozzle 121 to the 1st nozzle 121, are unused, reducing the number of unused nozzles Nn compared to the 100 in the previous case.

[0056] Next, we will explain in detail below a specific method for determining the number of mountain-shaped patterns Dg according to the nozzle number of the defective nozzle Nf in the nozzle row direction Dn.

[0057] Figure 10A shows that the nozzle number of a defective nozzle Nf is m, and Figure 10B is a graph showing the number of usable nozzles corresponding to the number of defective nozzles Nf for each number of mountain-shaped patterns Dg. Figure 11A is a graph showing that the number m of the defective nozzle Nf is in the first range, and Figure 11B is a diagram showing the mountain-shaped pattern Dg adopted when the number m in Figure 11A is in the first range. Figure 12A is a graph showing that the number m of the defective nozzle Nf is in the second range, and Figure 12B is a diagram showing the mountain-shaped pattern Dg adopted when the number m in Figure 12A is in the second range. Figure 13A is a graph showing that the number m of the defective nozzle Nf is in the third range, and Figure 13B is a diagram showing the mountain-shaped pattern Dg adopted when the number m in Figure 13A is in the third range. Figure 14A is a graph showing that the number m of the defective nozzle Nf is in the fourth range, and Figure 14B shows the mountain-shaped pattern Dg that is adopted when the number m in Figure 14A is in the fourth range.

[0058] Figure 15A is a graph showing that the number m of the defective nozzle Nf is in the 5th range, and Figure 15B is a diagram showing the mountain-shaped pattern Dg adopted when the number m in Figure 15A is in the 5th range. Figure 16A is a graph showing that the number m of the defective nozzle Nf is in the 6th range, and Figure 16B is a diagram showing the mountain-shaped pattern Dg adopted when the number m in Figure 16A is in the 6th range. Figure 17A is a graph showing that the number m of the defective nozzle Nf is in the 7th range, and Figure 17B is a diagram showing the mountain-shaped pattern Dg adopted when the number m in Figure 17A is in the 7th range. Figure 18A is a graph showing that the number m of the defective nozzle Nf is in the 8th range, and Figure 18B is a diagram showing the mountain-shaped pattern Dg adopted when the number m in Figure 18A is in the 8th range.

[0059] In Figure 10B, the correspondence between the nozzle number of a faulty nozzle Nf and the number of usable nozzles when one mountain-shaped pattern Dg is used is shown by a straight line, the correspondence between the nozzle number of a faulty nozzle Nf and the number of usable nozzles when two mountain-shaped patterns Dg are used is shown by a dashed line, and the correspondence between the nozzle number of a faulty nozzle Nf and the number of usable nozzles when three mountain-shaped patterns Dg are used is shown by a dotted line. In Figure 10B and the figures described below, "one mountain" means that there is one mountain-shaped pattern Dg, "two mountains" means that there are two mountain-shaped patterns Dg, and "three mountains" means that there are three mountain-shaped patterns Dg. In the following explanation, one mountain-shaped pattern Dg will be referred to as "one mountain," two mountain-shaped patterns Dg will be referred to as "two mountains," and three mountain-shaped patterns Dg will be referred to as "three mountains."

[0060] As shown in Figure 10A, let the nozzle number of the defective nozzle Nf be m. In this case, the control device 50 selects the one-peak, two-peak, and three-peak configuration in Figure 10B that has the most usable nozzles, according to the nozzle number m. For example, if the nozzle number of the defective nozzle Nf is 50, the one-peak configuration is selected; if the nozzle number of the defective nozzle Nf is 150, the three-peak configuration is selected; and if the nozzle number of the defective nozzle Nf is 210, the two-peak configuration is selected.

[0061] Below, we formulate the nozzle number m of the defective nozzle Nf and describe the mountain-shaped pattern Dg adopted according to the formulated nozzle number m.

[0062] As shown in Figure 11A, when the nozzle number m of the defective nozzle Nf is in the first range, that is, when the first equation m ≤ (n+1) / 4 is satisfied, one peak is adopted as shown in Figure 11B. Hereafter, the peak-shaped pattern Dg in Figure 11B will be called the first pattern. The above n is the total number of nozzles 121 in one nozzle row NL, for example, 420. For example, when the total number of nozzles 121 is 420, the nozzle number m that satisfies the first equation belongs to the region Rb in Figure 11A and will be 105 or less.

[0063] When one peak is adopted as shown in FIG. 11B, exceptionally, the controller 50 does not execute the above-described first generation processing and second generation processing. In this case, one mountain-shaped pattern Dg is assigned to a total of (n-m+1) nozzles 121 from the row end nozzle Ne farther from the ejection failure nozzle Nf to the ejection failure nozzle Nf. Accordingly, {n-(n-m+1)} nozzles 121 become unused nozzles Nn.

[0064] Next, as shown in FIG. 12A, when the nozzle number m of the ejection failure nozzle Nf is in the second range, that is, when the second expression of (n+1) / 4<m≦(3n+3) / 7 and the third expression of m≦n / 3 are satisfied, three peaks are adopted as shown in FIG. 12B. Hereinafter, the mountain-shaped pattern Dg in FIG. 12B is referred to as a second pattern. For example, when the total number of nozzles 121 is 420, the nozzle number m that satisfies the second expression and the third expression belongs to the region Rb in FIG. 12A, and is more than 105, that is, 106 or more and 140 or less.

[0065] When three peaks are adopted as shown in FIG. 12B, the controller 50 executes the above-described first generation processing and second generation processing. In this case, one mountain-shaped pattern Dg is assigned to a total of m nozzles 121 from the ejection failure nozzle Nf to the row end nozzle Ne closer to the ejection failure nozzle Nf. Further, one mountain-shaped pattern Dg is respectively assigned to up to m nozzles 121 counted from the nozzle 121 of the next number of the ejection failure nozzle Nf, and to up to m nozzles 121 counted from the nozzle 121 of the next number of the said nozzles 121. Accordingly, {n-(m×3)} nozzles 121 become unused nozzles Nn.

[0066] Next, as shown in Figure 13A, when the nozzle number m of the ejection defective nozzle Nf is in the third range, that is, when the second expression of (n+1) / 4<m≦(3n+3) / 7 and the fourth expression of n / 3<m are satisfied, three peaks are adopted as shown in Figure 13B. For example, when the total number of the nozzles 121 is 420, the nozzle numbers m that satisfy the second expression and the fourth expression belong to the region Rb in Figure 13A, which are greater than No. 140, that is, No. 141 or more and No. 180 or less.

[0067] Here, when the nozzle number m satisfies the second expression and the fourth expression, the control device 50 does not execute the first generation processing and the second generation processing, similarly to the above-described Figure 9D. In this case, when the nozzle number m is an odd number, by the same method as described above in Figure 9D, the nozzles 121 in the nozzle array NL are divided into three nozzle groups each composed of a total of {(n-m+1) / 2} nozzles 121. The mountain-shaped pattern Dg in Figure 13B when the nozzle number m is an odd number is referred to as a third pattern. One mountain-shaped pattern Dg is assigned to each of the nozzles 121 in each nozzle group. At this time, [n-{(n-m+1) / 2×3}] nozzles 121 become unused nozzles Nn. On the other hand, when the nozzle number m is an even number, by the same method as described above in Figure 9D, the nozzles 121 in the nozzle array NL are divided into three nozzle groups each composed of a total of {(n-m) / 2} nozzles 121. The mountain-shaped pattern Dg in Figure 13B when the nozzle number m is an even number is referred to as a fourth pattern. One mountain-shaped pattern Dg is assigned to each of the nozzles 121 in each nozzle group. At this time, [n-{(n-m) / 2×3}] nozzles 121 become unused nozzles Nn.

[0068] Next, as shown in Figure 14A, when the nozzle number m of the ejection defective nozzle Nf is in the fourth range, that is, when the fifth expression of (3n+3) / 7<m≦(4n+7) / 7 and the sixth expression of m≦n / 2 are satisfied, two peaks are adopted as shown in Figure 14B. Hereinafter, the mountain-shaped pattern Dg in Figure 14B is referred to as a fifth pattern. For example, when the total number of the nozzles 121 is 420, the nozzle numbers m that satisfy the fifth expression and the sixth expression belong to the region Rb in Figure 13A, which are greater than No. 180, that is, No. 181 or more and No. 210 or less.

[0069] When two peaks are employed as shown in FIG. 14B, the controller 50 executes the above-described first generation processing and second generation processing. In this case, one mountain-shaped pattern Dg is assigned to a total of m nozzles 121 from the ejection-defective nozzle Nf to the row end nozzle Ne closer to the ejection-defective nozzle Nf. Further, one mountain-shaped pattern Dg is assigned to m nozzles 121 counted from the nozzle 121 with the next number after the ejection-defective nozzle Nf. Accordingly, {n-(m×2)} nozzles 121 become unused nozzles Nn.

[0070] Next, as shown in FIG. 15A, when the nozzle number m of the ejection-defective nozzle Nf is in the fifth range, that is, when the fifth expression (3n+3) / 7<m≦(4n+7) / 7 and the seventh expression n / 2<m are satisfied, two peaks are employed as shown in FIG. 15B. Hereinafter, the mountain-shaped pattern Dg in FIG. 15B is referred to as a sixth pattern. For example, when the total number of nozzles 121 is 420, the nozzle numbers m satisfying the fifth expression and the seventh expression belong to the region Rb in FIG. 15A, and are greater than 210, that is, 211 or more and 241 or less.

[0071] When two peaks are employed as shown in FIG. 15B, the controller 50 executes the first generation processing and the second generation processing, similarly to FIG. 9B described above. In this case, one mountain-shaped pattern Dg is assigned to a total of (n-m+1) nozzles 121 from the ejection-defective nozzle Nf to the row end nozzle Ne closer to the ejection-defective nozzle Nf. Further, one mountain-shaped pattern Dg is assigned to (n-m+1) nozzles 121 counted from the nozzle 121 with the previous number before the ejection-defective nozzle Nf. Accordingly, [n-{(n-m+1)×2}] nozzles 121 become unused nozzles Nn.

[0072] Next, as shown in FIG. 16A, when the nozzle number m of the ejection defective nozzle Nf is in the sixth range, that is, when the eighth formula of (4n+7) / 7<m≦(3n+3) / 4 and the ninth formula of m≦2n / 3 are satisfied, three peaks are adopted as shown in FIG. 16B. For example, when the total number of the nozzles 121 is 420, the nozzle numbers m satisfying the eighth formula and the ninth formula belong to the region Rb in FIG. 16A, which are greater than No. 241, that is, No. 242 or more and No. 280 or less.

[0073] Here, when the nozzle number m satisfies the eighth formula and the ninth formula, the control device 50 does not execute the first generation process and the second generation process. In this case, when the nozzle number m is an odd number, the nozzles 121 in the nozzle array NL are divided into three nozzle groups each composed of {(m-1) / 2} nozzles 121 with the ejection defective nozzle Nf as a reference. The mountain-shaped pattern Dg in FIG. 16B when the nozzle number m is an odd number is referred to as the seventh pattern. One mountain-shaped pattern Dg is assigned to each of the nozzles 121 in each nozzle group. At this time, [n-{(m-1) / 2×3}] nozzles 121 become unused nozzles Nn. On the other hand, when the nozzle number m is an even number, the nozzles 121 in the nozzle array NL are divided into three nozzle groups each composed of (m / 2) nozzles 121 with the ejection defective nozzle Nf as a reference. The mountain-shaped pattern Dg in FIG. 16B when the nozzle number m is an even number is referred to as the eighth pattern. One mountain-shaped pattern Dg is assigned to each of the nozzles 121 in each nozzle group. At this time, {n-(m / 2×3)} nozzles 121 become unused nozzles Nn.

[0074] Next, as shown in FIG. 17A, when the nozzle number m of the ejection defective nozzle Nf is in the seventh range, that is, when the eighth formula of (4n+7) / 7<m≦(3n+3) / 4 and the tenth formula of 2n / 3<m are satisfied, three peaks are adopted as shown in FIG. 17B. Hereinafter, the mountain-shaped pattern Dg in FIG. 17B is referred to as the tenth pattern. For example, when the total number of the nozzles 121 is 420, the nozzle numbers m satisfying the eighth formula and the tenth formula belong to the region Rb in FIG. 17A, which are greater than No. 280, that is, No. 281 or more and No. 315 or less.

[0075] When three peaks are employed as shown in FIG. 17B, the controller 50 executes the above-described first generation processing and second generation processing. In this case, one mountain-shaped pattern Dg is assigned to a total of (n-m+1) nozzles 121 from the ejection defective nozzle Nf to the row end nozzle Ne closer to the ejection defective nozzle Nf. Further, one mountain-shaped pattern Dg is assigned to each of up to (n-m+1) nozzles 121 counted from the nozzle 121 with the number immediately preceding the ejection defective nozzle Nf, and up to (n-m+1) nozzles 121 counted from the nozzle 121 with the number next to the said nozzle 121. Accordingly, [n-{(n-m+1)×3}] nozzles 121 become unused nozzles Nn.

[0076] Next, as shown in FIG. 18A, when the nozzle number m of the ejection defective nozzle Nf falls within the eighth range, that is, when the eleventh expression of (3n+1) / 4<m is satisfied, one peak is employed as shown in FIG. 18B. Hereinafter, the mountain-shaped pattern Dg in FIG. 18B is referred to as the ninth pattern. For example, when the total number of the nozzles 121 is 420, the nozzle number m that satisfies the eleventh expression belongs to the region Rb in FIG. 11A, and is greater than 315, that is, 316 or higher.

[0077] When one peak is employed as shown in FIG. 18B, as an exception, the controller 50 does not execute the above-described first generation processing and second generation processing. In this case, one mountain-shaped pattern Dg is assigned to a total of m nozzles 121 from the row end nozzle Ne farther from the ejection defective nozzle Nf to the ejection defective nozzle Nf. Accordingly, (n-m) nozzles 121 become unused nozzles Nn.

[0078] Figure 19 is a diagram illustrating the number of mountain-shaped patterns Dg adopted when the nozzle number m of a defective nozzle Nf is, for example, 110. Figure 20A is a conceptual diagram showing print data for 1500 pins, Figure 20B is a conceptual diagram showing the number of print passes required when printing based on the print data in Figure 20A, where m=110 and one mountain is adopted, and Figure 20C is a conceptual diagram showing the number of print passes required when printing based on the print data in Figure 20A, where m=110 and three mountains are adopted.

[0079] As shown in Figure 19, when the nozzle number m of the defective nozzle Nf is, for example, 110, the number of usable nozzles when using a single-peak nozzle is 311, and the number of usable nozzles when using a triple-peak nozzle is 330. Here, as shown in Figure 20A, when printing is performed using 420 nozzles 121 in the nozzle row NL based on 1500-pin print data, printing is possible in 11 print passes when using a single-peak nozzle, as shown in Figure 20B. On the other hand, when printing is performed using the nozzles 121 based on 1500-pin print data, printing is possible in 11 print passes even when using a triple-peak nozzle, as shown in Figure 20C. That is, the number of print passes required when using a single-peak nozzle is the same as the number of print passes required when using a triple-peak nozzle. In this case, when the control device 50 generates a mask with the sum of the first and second partial masks as the first number, and the number of print passes when printing an image based on image data is the same as the number of print passes when printing with the sum being greater than the first number (the second number), the control device 50 considers the sum to be the first number. In other words, of the single peak shown in Figure 20B and the three peaks shown in Figure 20C, one peak is selected. The first number is 1 in the example of Figure 20B, which is the number of first partial masks related to the single peak. The second number is 3 in the example of Figure 20C, which is the sum of 1 (the number of first partial masks related to the three peaks) and 2 (the number of second partial masks related to the three peaks).

[0080] Figure 21 shows an example in which multiple defective nozzles Nf were detected in nozzle row NL.

[0081] In Figure 21, the nozzle 121 located in the center of the nozzle row NL is defined as the central nozzle Nc. For example, if the number of nozzles 121 constituting the nozzle row NL is 420, the central nozzle Nc can be the 210th nozzle 121 and the 211th nozzle 121. Here, as shown in Figure 21, in the nozzle row NL, multiple defective nozzles Nf may be detected, such as the first defective nozzle Nf1 and the second defective nozzle Nf2. The first defective nozzle Nf1 is closer to the central nozzle Nc than the second defective nozzle Nf2 in the nozzle row direction Dn. The second defective nozzle Nf2 is located at the end Re, which is closer to the end nozzle Ne than the central nozzle Nc in the nozzle row direction Dn. The nozzles 121 located at the end Re include any number of nozzles 121 positioned toward the central nozzle Nc with respect to the end nozzle Ne.

[0082] The control device 50 performs a mask determination process when it detects a first defective nozzle Nf1 and a second defective nozzle Nf2 as defective nozzles Nf, and when either the first defective nozzle Nf1 or the second defective nozzle Nf2 (the second defective nozzle Nf2 in the example in Figure 21) is located at the end Re, which is closer to the end nozzle Ne than the central nozzle Nc.

[0083] Figure 22 is a flowchart showing an example of the processing flow in the printing device 100. Figure 23 is a flowchart showing an example of a subroutine related to the mask determination process in Figure 22. Figure 24 is a flowchart showing an example of a subroutine related to the mask determination process following Figure 23.

[0084] As shown in Figure 22, the control device 50 first determines whether or not it has received a print job from an external device 200 or the like (step S1). If no print job has been received in step S1 (No in step S1), the control device 50 waits until it receives the print job.

[0085] On the other hand, if a print job is received (Yes in step S1), the control device 50 performs color conversion, halftone processing, and interlacing processing on the image data included in the print job to generate print data, and starts a printing process to print an image by ejecting ink droplets from the ejection head 20 onto the printing medium W based on the print data (step S2). The printing process includes a normal printing mode for printing an image onto the printing medium W and a save mode for printing an image onto the printing medium W with a lower image density than in the normal printing mode. Color conversion processing is the process of converting the RGB values ​​for each pixel included in the RGB image data to CMYK values. Halftone processing is the process of converting the image data after color conversion processing into dot data. Interlacing processing is the process of dividing the dot data after halftone processing into nozzle row direction Dn, and generating print data related to partial images for ejecting ink droplets to the ejection head 20 between the start of movement of the carriage 41 in the movement direction D1 and the stop of movement.

[0086] Next, the control device 50 performs a ejection failure detection process between one print pass and another print pass in the printing process (step S3). Then, the control device 50 determines whether or not an ejection failure nozzle Nf has been detected in the ejection failure detection process (step S4). If an ejection failure nozzle Nf is detected (Yes in step S4), the control device 50 determines whether or not there are multiple detected ejection failure nozzles Nf (step S5). On the other hand, if no ejection failure nozzle Nf is detected (No in step S4), the control device 50 performs the process of step S20 described below.

[0087] In step S5, if the process involves multiple defective nozzles Nf, including a first defective nozzle Nf1 and a second defective nozzle Nf2 (Yes in step S5), the control device 50 determines whether the multiple defective nozzles Nf are in different colored nozzle rows NL and are located in the same position in the second direction D2 (step S6). Here, being in the same position in the second direction D2 means that the nozzle numbers, which are numbers assigned to the nozzles, match. If the nozzle numbers are different, they are located in different positions in the second direction D2.

[0088] In the process of step S6, if multiple defective nozzles Nf are located in nozzle rows NL of different colors and are not in the same position in the second direction D2, that is, if they are in the same nozzle row NL (No in step S6), the control device 50 determines whether one of the multiple defective nozzles Nf is located at the end Re of one of the nozzle rows NL (step S7).

[0089] In the process of step S7, if one of the multiple defective nozzles Nf is not located at the end Re of a nozzle row NL (No in step S7), the control device 50 determines whether either the first defective nozzle Nf1 or the second defective nozzle Nf2 is included in the first nozzle row when printing without using the first nozzle row, that is, whether either the first defective nozzle Nf1 or the second defective nozzle Nf2 corresponds to a color that is not used (step S8).

[0090] If, in step S8, either the first defective nozzle Nf1 or the second defective nozzle Nf2 is not included in the first nozzle row (No in step S8), the control device 50 determines whether the print rate on the printing medium W is less than a predetermined value (step S9). The print rate is the ratio of the area on which an image is printed to the area on the printing medium W that is printable. If the print rate on the printing medium W is less than a predetermined value (Yes in step S9), the control device 50 executes the process in step S16 described below.

[0091] In contrast, if there are no multiple defective nozzles Nf, i.e., only one (No in step S5), if multiple defective nozzles Nf are in nozzle rows NL of different colors and are in the same position in the second direction D2 (Yes in step S6), if one of the multiple defective nozzles Nf is located at the end Re of one nozzle row NL (Yes in step S7), if either the first defective nozzle Nf1 or the second defective nozzle Nf2 is included in the first nozzle row (Yes in step S8), or if the print rate on the printing medium W is greater than or equal to a predetermined value (No in step S9), the control device 50 stops the printing process (step S10) and executes the mask determination process described below to determine the masks for the first to tenth patterns described above (step S11).

[0092] Next, the control device 50 determines whether the printing process is in save mode (step S12). If the printing process is not in save mode (No in step S12), the control device 50 determines whether the remaining amount of any of the inks stored in each tank 12 is below a threshold (step S13).

[0093] If the remaining amount of ink stored in each tank 12 is not below a threshold (No in step S13), the control device 50 calculates the remaining printing time (step S14). In this case, the remaining printing time is the time required to complete printing, calculated based on the completed and uncompleted print passes. Next, the control device 50 performs a determination process to determine whether the purge processing time is less than the remaining printing time (step S15). In this case, the purge processing time may be calculated based on the time required for the carriage 41 supporting the ejection head 20 to move to the position of the cap 57 and the time required for the purge process, or it may be stored in the storage unit 53 in advance. If the purge processing time is less than the remaining printing time (Yes in step S15), the control device 50 performs the purge process (step S16). After that, the control device 50 returns to the process of step S3 described above.

[0094] On the other hand, if the printing process is in save mode (Yes in step S12), if the remaining amount of ink stored in any of the tanks 12 is below a threshold (Yes in step S13), or if the purging process time is equal to or greater than the remaining printing time (No in step S15), the control device 50 generates sorted data by rearranging the dot data based on the mask generated in the mask determination process (step S17).

[0095] The control device 50 then divides the rearranged data into nozzle row directions Dn and performs a re-interlacing process to regenerate print data related to partial images for ejecting ink droplets to the ejection head 20 between the time the carriage 41 starts moving in the movement direction D1 and when it stops moving (step S18). After that, the control device 50 resumes the printing process (step S19). The control device 50 then determines whether or not printing for the print job has finished (step S20). If printing for the print job has finished (Yes in step S20), the control device 50 terminates the process, and if printing for the print job has not finished (No in step S20), the control device 50 continues the printing.

[0096] Next, as shown in Figure 23, in the mask determination process of step S11, the control device 50 first obtains the number of nozzles n in the nozzle row NL from the storage unit 53 (step S31).

[0097] Next, the control device 50 obtains the nozzle number m of the defective nozzle Nf (step S32). Then, the control device 50 determines whether m ≤ (n+1) / 4 (step S33). If m ≤ (n+1) / 4 (Yes in step S33), the control device 50 adopts the first pattern described above (step S34).

[0098] On the other hand, if m≦(n+1) / 4 is not satisfied (No in step S33), the controller 50 determines whether (n+1) / 4<m≦(3n+3) / 7 is satisfied (step S35). If (n+1) / 4<m≦(3n+3) / 7 is satisfied (Yes in step S35), the controller 50 determines whether m≦n / 3 is satisfied (step S36).

[0099] If m≦n / 3 is satisfied (Yes in step S36), the controller 50 adopts the aforementioned second pattern (step S37). On the other hand, if m≦n / 3 is not satisfied (No in step S36), the controller 50 determines whether m is an odd number (step S38).

[0100] If m is an odd number (Yes in step S38), the controller 50 adopts the aforementioned third pattern (step S39). On the other hand, if m is an even number (No in step S38), the controller 50 adopts the aforementioned fourth pattern (step S40).

[0101] In the process of the above step S35, if (n+1) / 4<m≦(3n+3) / 7 is not satisfied (No in step S35), as shown in FIG. 24, the controller 50 determines whether (3n+3) / 7<m≦(4n+7) / 7 is satisfied (step S41).

[0102] If (3n+3) / 7<m≦(4n+7) / 7 is satisfied (Yes in step S41), the controller 50 determines whether m≦n / 2 is satisfied (step S42). If m≦n / 2 is satisfied (Yes in step S42), the controller 50 adopts the aforementioned fifth pattern (step S43). On the other hand, if m≦n / 2 is not satisfied (No in step S42), the controller 50 adopts the aforementioned sixth pattern (step S44).

[0103] In the process of the above step S41, if (3n+3) / 7<m≦(4n+7) / 7 is not satisfied (No in step S41), the controller 50 determines whether (4n+7) / 7<m≦(3n+3) / 4 is satisfied (step S45).

[0104] When (4n+7) / 7<m≦(3n+3) / 4 (Yes in step S45), the control device 50 determines whether m≦2n / 3 (step S46). When m≦2n / 3 (Yes in step S46), the control device 50 determines whether m is an odd number (step S47).

[0105] When the above m is an odd number (Yes in step S47), the control device 50 adopts the aforementioned seventh pattern (step S48). On the other hand, when m is an even number (No in step S47), the control device 50 adopts the aforementioned eighth pattern (step S49).

[0106] In the process of step S45 described above, when (4n+7) / 7<m≦(3n+3) / 4 is not satisfied (No in step S45), the control device 50 adopts the aforementioned ninth pattern (step S50). Further, in the process of step S46 described above, when m≦2n / 3 is not satisfied (No in step S46), the control device 50 adopts the aforementioned tenth pattern (step S51).

[0107] As described above, according to the present embodiment, a mask is generated based on a first partial mask of a predetermined pattern that minimizes the sharing ratio of the defective ejection nozzle Nf, and a second partial mask in which one or a plurality of masks forming the same pattern as the first partial mask are arranged. Therefore, even when a defective ejection nozzle Nf occurs in the nozzle array NL, and a deviation in the conveyance amount of the print medium W or a deviation in the landing position of ink droplets ejected by another nozzle 121 other than the defective ejection nozzle Nf occurs, the occurrence of dot missing is suppressed or prevented. Accordingly, the occurrence of linear banding caused by dot missing is also suppressed or prevented.

[0108] Furthermore, in this embodiment, the control device 50 designates the defective nozzle Nf and the nozzle 121 to which the mask is not applied as unused nozzles Nn. In this case, since ink droplets are not ejected from the defective nozzle Nf, it is possible to avoid a decrease in image quality caused by a misalignment of the landing position of the ink droplets that may occur if ink droplets are ejected from the defective nozzle Nf. Also, since ink droplets are not ejected from the nozzle 121 to which the mask is not applied, it is possible to avoid the ejection of ink droplets that are not needed for printing.

[0109] Furthermore, in this embodiment, the control device 50 uses the sum of the first and second partial masks as the first number when generating a mask, and the number of print passes when printing an image based on image data is the same as the number of print passes when printing with the sum being greater than the first number (the second number), in which case the sum is used as the first number. In this case, when the sum of the first and second partial masks is the first number, the sing area is smaller than when the sum is the second number, thus achieving relatively high image quality.

[0110] Furthermore, in this embodiment, the control device 50 performs a mask determination process when there are not multiple defective nozzles Nf, and when a first defective nozzle Nf1 and a second defective nozzle Nf2 are detected as defective nozzles Nf, and the first defective nozzle Nf1 and the second defective nozzle Nf2 are nozzle rows NL of different colors and are in the same position in the second direction D2. As a result, printing can be performed by performing re-interlacing based on the mask determined in the mask determination process. Therefore, purging can be avoided in the above cases, and thus ink consumption can be reduced.

[0111] Furthermore, in this embodiment, the control device 50 performs a mask determination process when a first defective nozzle Nf1 and a second defective nozzle Nf2 are detected as defective nozzles Nf, and when either the first defective nozzle Nf1 or the second defective nozzle Nf2 is located at an end Re, which is closer to the end nozzle Ne than the central nozzle Nc. As a result, printing can be performed by performing a re-interlacing process based on the mask determined in the mask determination process. Therefore, purging can be avoided in the above case, and thus ink consumption can be reduced.

[0112] Furthermore, in this embodiment, when printing without using the first nozzle row, the control device 50 performs a mask determination process if either the first defective nozzle Nf1 or the second defective nozzle Nf2 is included in the first nozzle row. For example, when the printing medium W is glossy paper and the first nozzle row corresponds to black ink, and when printing is in monochrome mode and the first nozzle row corresponds to at least one of cyan ink, magenta ink, and yellow ink, re-interlacing processing can be performed based on the mask determined in the mask determination process to perform printing. Therefore, purging can be avoided in the above cases, and thus ink consumption can be reduced.

[0113] Furthermore, in this embodiment, the control device 50 performs a mask determination process when the printing rate on the printing medium W is equal to or greater than a predetermined value. This allows printing to be performed by re-interlacing based on the mask determined in the mask determination process. Therefore, since purging can be avoided in the above case, ink consumption can be reduced.

[0114] Furthermore, in this embodiment, when the print process is in save mode, the control device 50 generates rearranged data by rearranging the dot data based on the mask generated in the mask determination process, and performs re-interlacing based on this rearranged data. As a result, printing can be performed by performing re-interlacing based on the mask determined in the mask determination process, thus avoiding the purging process being performed in save mode.

[0115] Furthermore, in this embodiment, the control device 50 performs re-interlacing when the remaining amount of ink stored in the tank 12 is below a threshold. Therefore, purging can be avoided when the remaining amount of ink stored in the tank 12 is below a threshold, thus reducing ink consumption.

[0116] Furthermore, in this embodiment, the control device 50 executes the purging process when the purging time is less than the remaining printing time. This avoids the problem of increased processing time caused by performing the purging process when the purging time is greater than or equal to the remaining printing time.

[0117] Although this embodiment has been described above, if multiple defective nozzles Nf exist in different nozzle rows NL, and each defective nozzle Nf has the same nozzle number (for example, the 140th nozzle corresponding to cyan ink and the 140th nozzle corresponding to magenta ink), the purging process can be avoided and the issue can be addressed by mask determination processing.

[0118] This disclosure is not limited to the embodiments described above, and modifications can be made without departing from the gist of this disclosure. For example, the following:

[0119] Figure 25 is a flowchart showing another example of the processing flow in the printing device 100.

[0120] As shown in Figure 25, the control device 50 first determines whether or not it has received a print job from an external device 200 or the like (step S61). If no print job has been received in step S61 (No in step S61), the control device 50 waits until it receives the print job.

[0121] On the other hand, if a print job is received (Yes in step S61), the control device 50 performs color conversion, halftone processing, and interlacing processing on the image data included in the print job to generate print data, and then starts printing the image by ejecting ink droplets from the ejection head 20 onto the printing medium W based on the print data (step S62).

[0122] Next, the control device 50 performs a ejection failure detection process between one print pass and another print pass in the printing process (step S63). Then, the control device 50 determines whether or not an ejection failure nozzle Nf has been detected in the ejection failure detection process (step S64). If an ejection failure nozzle Nf is detected (Yes in step S64), the control device 50 determines whether or not there are multiple detected ejection failure nozzles Nf (step S65). On the other hand, if no ejection failure nozzle Nf is detected (No in step S64), the control device 50 performs the process in step S84 described below.

[0123] If, in the process of step S65, the multiple defective nozzles Nf include a first defective nozzle Nf1 and a second defective nozzle Nf2 (Yes in step S65), the control device 50 determines whether the multiple defective nozzles Nf are in different nozzle rows NL and are in the same position in the second direction D2 (step S66).

[0124] In the process of step S66, if multiple defective nozzles Nf are in nozzle rows NL of different colors and are not in the same position in the second direction D2 (No in step S66), the control device 50 determines whether one of the multiple defective nozzles Nf is located at the end Re of one nozzle row NL (step S67).

[0125] In step S67, if one of the multiple defective nozzles Nf is not located at the end Re of a nozzle row NL (No in step S67), the control device 50 determines whether either the first defective nozzle Nf1 or the second defective nozzle Nf2 is included in the first nozzle row when printing without using the first nozzle row, that is, whether either the first defective nozzle Nf1 or the second defective nozzle Nf2 corresponds to a color that is not used (step S68).

[0126] If, in step S68, either the first defective nozzle Nf1 or the second defective nozzle Nf2 is not included in the first nozzle row (No in step S68), the control device 50 determines whether the print rate on the printing medium W is less than a predetermined value (step S69). If the print rate on the printing medium W is less than a predetermined value (Yes in step S69), the control device 50 executes the process in step S76 described below.

[0127] In contrast, if there are no multiple defective nozzles Nf, i.e., only one (No in step S65), if multiple defective nozzles Nf are in nozzle rows NL of different colors and are in the same position in the second direction D2 (Yes in step S66), if one of the multiple defective nozzles Nf is located at the end Re of one nozzle row NL (Yes in step S67), if either the first defective nozzle Nf1 or the second defective nozzle Nf2 is included in the first nozzle row (Yes in step S68), and if the print rate on the printing medium W is greater than or equal to a predetermined value (No in step S69), the control device 50 stops the printing process (step S70) and executes the mask determination process described above to determine the masks for the first to tenth patterns described above (step S71).

[0128] Next, the control device 50 determines whether the printing process is in save mode (step S72). If the printing process is not in save mode (No in step S72), the control device 50 determines whether there is any remaining ink in each tank 12 that is below a threshold (step S73).

[0129] If there is no remaining amount below the threshold (No in step S73), the control device 50 calculates the remaining printing time (step S74). Next, the control device 50 performs a determination process to determine whether the purge processing time is less than the remaining printing time (step S75). If the purge processing time is less than the remaining printing time (Yes in step S75), the control device 50 performs the purge process (step S76). After that, the control device 50 returns to the process in step S63 described above.

[0130] On the other hand, if the printing process is in save mode (Yes in step S72), if there is remaining material below a threshold (Yes in step S73), or if the purging process time is equal to or greater than the remaining printing time (No in step S75), the control device 50 generates sorted data by rearranging the dot data based on the mask generated in the mask determination process (step S77).

[0131] Then, the control device 50 divides the rearranged data into nozzle row directions Dn and performs a re-interlacing process to regenerate print data related to partial images for ejecting ink droplets to the ejection head 20 between the time the carriage 41 starts moving in the movement direction D1 and the time the movement stops (step S78).

[0132] Next, the control device 50 calculates the time required for printing based on the print data generated by the re-interlacing process, or the printing speed based on that time (step S79). The control device 50 then displays information such as the time required for printing based on the print data generated by the re-interlacing process, or the printing speed based on that time, on the display unit 14, and also displays a message on the display unit 14 prompting the replacement of the ejection head 20 based on the information regarding the time required for printing (step S80).

[0133] Next, the control device 50 determines whether the user has selected to replace the discharge head 20 using the input unit 15 (step S81). If the user has selected to replace the discharge head 20 (Yes in step S81), the control device 50 performs initial head processing, such as returning the discharge head 20 to the home position (step S82).

[0134] On the other hand, if the user has not selected to replace the ejection head 20 (No in step S81), and after the processing in step S82, the control device 50 resumes the printing process (step S83). The control device 50 then determines whether or not the printing of the print job has been completed (step S84). If the printing of the print job has been completed (Yes in step S84), the control device 50 terminates the process; if the printing of the print job has not been completed (No in step S84), the control device 50 continues the printing.

[0135] As described above, in this embodiment, the control device 50 displays information such as the time required for printing or the printing speed based on that time on the display unit 14. This allows the user to consider whether or not it is necessary to replace the ejection head 20 by referring to the information.

[0136] Furthermore, in this embodiment, the control device 50 displays a prompt on the display unit 14 to replace the ejection head 20 based on information regarding the time required for printing. This allows the user to select whether or not to replace the ejection head 20 based on the display.

[0137] Figure 26 is a block diagram showing a printing system 300 comprising a printing device 100 and a processing device 240.

[0138] As shown in Figure 26, the printing system 300 comprises the printing device 100 and the processing device 240 described above. The printing device 100 has the same configuration as described above and includes a control device 50 and an ejection head 20, etc. The processing device 240 includes a control device 250. The control device 250 of the processing device 240 communicates with the control device 50 of the printing device 100. The control device 50 corresponds to the first control device of this disclosure, and the control device 250 corresponds to the second control device of this disclosure.

[0139] In this embodiment, the control device 250 performs the color conversion process, halftone processing, interlacing process, mask determination process including the first to third generation processes, and reinterlacing process including the generation process of rearranged data. As a result, the control device 50 of the printing device 100 does not need to perform the color conversion process, halftone processing, interlacing process, mask determination process, and reinterlacing process, thereby reducing the processing load on the control device 50.

[0140] Furthermore, in the above embodiment, the ejection failure detection process was performed using the electrode 54a, but the ejection failure detection process can be performed by various known methods. For example, a nozzle Nf with an ejection failure can be detected based on the residual vibration of the drive element 25 after the ejection of ink droplets by the nozzle 121. Alternatively, a laser beam can be irradiated onto the ink droplets after ejection, and the nozzle Nf with an ejection failure can be detected based on the received light signal caused by the laser beam.

[0141] Furthermore, in the above embodiment, the nozzle Nf with ejection defects was identified as an unused nozzle Nn, but the invention is not limited to this, and the nozzle Nf with ejection defects may be used for ejecting ink droplets.

[0142] Furthermore, in the above embodiment, when generating a mask with the sum of the first partial mask and the second partial mask as the first number, if the number of print passes when printing an image based on image data is the same as the number of print passes when printing with the sum being greater than the first number (the second number), then the sum is considered the first number. However, it is not limited to this, and the sum may be considered the second number when the number of print passes in one of the above cases is the same as the number of print passes in the other case.

[0143] Furthermore, in the above embodiment, the purging process was performed when the purging time was less than the remaining printing time, but this is not limited to that. The purging process may also be performed when the purging time is equal to or greater than the remaining printing time.

[0144] Furthermore, in the above embodiment, the control device 50 displays information such as the time required for printing based on the print data generated by the re-interlacing process, or the printing speed based on that time, on the display unit 14, and also displays a message on the display unit 14 prompting the replacement of the ejection head 20 based on the information regarding the time required for printing, etc., but is not limited to this. The control device 50 may simply display information such as the time required for printing based on the print data generated by the re-interlacing process, or the printing speed based on that time, on the display unit 14. Alternatively, the control device 50 may simply display a message on the display unit 14 prompting the replacement of the ejection head 20 based on the information regarding the time required for printing, etc. [Explanation of Symbols]

[0145] 12 tanks 14 Display section 20 Discharge heads 41 Carriage 50 Control device 55 Maintenance equipment 100 Printing equipment 121 Nozzles 240 Processing Units 250 Control devices 300 Printing Systems Dn Nozzle row direction D1 Movement direction D2 Conveying direction Nc central nozzle Ne row end nozzle Nf dispensing failure nozzle Nf1 First dispensing faulty nozzle Nf2 Second dispensing faulty nozzle NL nozzle row NLe Nozzle Row End Re Nozzle row end W Printing medium

Claims

1. A discharge head having a nozzle row in which multiple nozzles are arranged along a predetermined nozzle row direction for discharging droplets onto a printing medium that is transported in a predetermined transport direction based on image data, A control device is provided, The control device is A printing process that performs singling printing in which a first print pass and a second print pass performed after the first print pass partially overlap each other in the transport direction, Discharge failure detection process for detecting a defective nozzle from among the plurality of nozzles in the nozzle row, Depending on the defective nozzle, a mask determination process is performed to determine a mask relating to the proportion of droplet discharge amounts in the first print pass and the second print pass for the plurality of nozzles in the nozzle row. The aforementioned mask determination process is: In the nozzle row, a first generation process generates a first partial mask of a predetermined pattern that minimizes the proportion of the defective nozzles in the nozzle row, for a plurality of nozzles from the defective nozzle to the end nozzle located at the nozzle row end closer to the defective nozzle. A second generation process generates a second partial mask in which one or more masks having the same pattern as the first partial mask are arranged in order from the nozzle closest to the nozzle closest to the nozzle, excluding a plurality of nozzles from the nozzle row with a discharge defect to the nozzles at the end of the nozzle row that are closer to the nozzle with a discharge defect. A printing apparatus comprising: a third generation process for generating the mask based on the first partial mask and the second partial mask.

2. The printing apparatus according to claim 1, wherein the control device does not use the nozzles to which the mask is not applied and the nozzles with ejection defects among the plurality of nozzles in the nozzle row.

3. The printing apparatus according to claim 1, wherein the control device sets the sum of the first partial mask and the second partial mask as the first number when generating the mask and setting the sum of the first partial mask and the second partial mask as the first number, and the number of print passes when printing the image based on the image data is the same as the number of print passes when generating the mask and setting the sum of the first partial mask and the second partial mask as the first number, which is greater than the first number, and the sum of the first partial mask and the second partial mask is the first number.

4. The discharge head has a plurality of nozzle rows, The nozzle row includes a first nozzle row containing a first nozzle for dispensing a liquid of a first color, and a second nozzle row containing a second nozzle for dispensing a liquid of a second color different from the first color. The printing apparatus according to claim 1, wherein the control device executes the mask determination process when there are not multiple defective nozzles, and when a first defective nozzle and a second defective nozzle are detected as defective nozzles and the first defective nozzle and the second defective nozzle are in the first nozzle row.

5. The printing apparatus according to claim 1, wherein the control device detects a first defective nozzle and a second defective nozzle as defective nozzles, and executes the mask determination process when either the first defective nozzle or the second defective nozzle is located at an end of the nozzle row, closer to the end nozzle than the central nozzle located in the center of the nozzle row.

6. The nozzle row includes a first nozzle row corresponding to a first color of the droplet and a second nozzle row corresponding to a second color of the droplet. The printing apparatus according to claim 1, wherein the control device detects a first defective nozzle and a second defective nozzle as defective nozzles, and when printing is performed without using the first nozzle row, either the first defective nozzle or the second defective nozzle is included in the first nozzle row.

7. The printing apparatus according to claim 1, wherein the control device executes the mask determination process when the printing rate on the printing medium is equal to or greater than a predetermined value.

8. The carriage supports the discharge head and moves in a direction intersecting the conveying direction, The printing process includes a normal printing mode for printing an image onto the printing medium and a save mode for printing the image onto the printing medium with a lower density than in the normal printing mode. The control device is A color conversion process that performs color conversion on image data, Halftone processing, which converts the image data after the color conversion process into dot data, Further, interlacing is performed, which divides the dot data after the halftone processing in the direction of the nozzle row and generates a partial image for ejecting droplets from the ejection head between the start of movement of the carriage in the direction of movement and the stop of movement, and The printing apparatus according to claim 1, wherein, when the printing mode is the save mode, it generates rearranged data by rearranging the dot data based on the mask, then divides the rearranged data in the direction of the nozzle row, and performs a reinterlacing process to regenerate partial images for ejecting droplets to the ejection head between the time the carriage starts moving in the direction of movement and the time the movement stops.

9. Equipped with a tank for storing liquid, The printing apparatus according to claim 8, wherein the control device performs the re-interlacing process when the remaining amount of liquid stored in the tank is less than a threshold.

10. The device includes a maintenance device that performs a purging process to discharge droplets from the nozzle, The control device performs a calculation process to calculate the remaining printing time required until printing is completed based on the executed print paths, A determination process is further performed to determine whether the purging time required for the purging process is less than the remaining printing time, and The printing apparatus according to claim 1, wherein the purging process is performed when the purging time is less than the remaining printing time.

11. Equipped with a display unit, The printing apparatus according to claim 8, wherein the control device causes the display unit to display information regarding the time required for printing based on the print data generated by the re-interlacing process.

12. The printing apparatus according to claim 11, wherein the control device displays a prompt to replace the ejection head based on information regarding the time required for printing.

13. A printing method using a printing apparatus having a discharge head having a nozzle row in which a plurality of nozzles for discharging droplets onto a printing medium that is transported in a predetermined transport direction based on image data are arranged along a predetermined nozzle row direction, Single-ring printing is performed such that the first print pass and the second print pass, which is performed after the first print pass, partially overlap each other in the transport direction. The nozzles having a discharge defect are detected from among the plurality of nozzles in the nozzle row. Depending on the defective nozzle, a mask determination process is performed to determine a mask relating to the distribution ratio of droplet discharge amounts in the first print pass and the second print pass for the plurality of nozzles in the nozzle row. In the mask determination process described above, In the nozzle row, a first partial mask of a predetermined pattern is generated for a plurality of nozzles from the defective nozzle to the end nozzle located at the nozzle row end closer to the defective nozzle, such that the proportion of the defective nozzle is minimized. A second partial mask is generated by arranging one or more masks having the same pattern as the first partial mask in order from the nozzle closest to the nozzle closest to the nozzle, excluding a plurality of nozzles in the nozzle row from the nozzle with a discharge defect to the nozzle end nozzle located at the nozzle row end closest to the nozzle with a discharge defect. A printing method for generating the mask based on the first partial mask and the second partial mask.

14. A printing program to be executed by a computer in a printing apparatus having a discharge head having a nozzle row in which a plurality of nozzles for discharging droplets onto a printing medium that is transported in a predetermined transport direction based on image data are arranged along a predetermined nozzle row direction, The aforementioned computer, The printing means performs singling printing in which the first print pass and the second print pass performed after the first print pass partially overlap each other in the transport direction. Discharge failure detection means for detecting a defective nozzle from among the plurality of nozzles in the nozzle row, and In accordance with the defective nozzle, the mask determination processing means functions as a mask determination processing means that performs a mask determination processing to determine the distribution ratio of droplet discharge amounts in the first print pass and the second print pass for the plurality of nozzles in the nozzle row, and The mask determination processing means, A first generation processing means generates a first partial mask of a predetermined pattern for a plurality of nozzles in the nozzle row, from the defective nozzle to the end nozzle located at the nozzle row end closer to the defective nozzle, such that the proportion of the defective nozzle is minimized. A second generation processing means generates a second partial mask in which one or more masks having the same pattern as the first partial mask are arranged in order from the nozzle closest to the nozzle closest to the nozzle, excluding a plurality of nozzles in the nozzle row from the nozzle with a discharge defect to the nozzle end nozzle located at the nozzle row end closest to the nozzle with a discharge defect, and A printing program that functions as a third generation processing means for generating the mask based on the first partial mask and the second partial mask.

15. A printing system comprising a printing device and a processing device that communicates with the printing device, The aforementioned printing apparatus, A discharge head having a nozzle row in which multiple nozzles are arranged along a predetermined nozzle row direction for discharging droplets onto a printing medium that is transported in a predetermined transport direction based on image data, A first control device is provided, The first control device is A printing process that performs singling printing in which a first print pass and a second print pass performed after the first print pass partially overlap each other in the transport direction, The process involves detecting a nozzle with a discharge defect from among the plurality of nozzles in the nozzle row, and then performing a discharge defect detection process. The aforementioned processing apparatus includes a second control device, The second control device is Depending on the defective nozzle, a mask determination process is performed to determine a mask relating to the distribution ratio of droplet discharge amounts in the first print pass and the second print pass for the plurality of nozzles in the nozzle row. The aforementioned mask determination process is: In the nozzle row, a first generation process generates a first partial mask of a predetermined pattern that minimizes the proportion of the defective nozzles in the nozzle row, for a plurality of nozzles from the defective nozzle to the end nozzle located at the nozzle row end closer to the defective nozzle. A second generation process generates a second partial mask in which one or more masks having the same pattern as the first partial mask are arranged in order from the nozzle closest to the nozzle closest to the nozzle, excluding a plurality of nozzles from the nozzle row with a discharge defect to the nozzles at the end of the nozzle row that are closer to the nozzle with a discharge defect. A printing system comprising: a third generation process for generating the mask based on the first partial mask and the second partial mask.

Images