Printing apparatus, printing control method, storage medium, and computer program product

Abstract

The invention provides a printing apparatus, a printing control method, a storage medium, and a computer program product. In a case where a stop operation for causing the printing unit not to perform scanning for a predetermined time or more is inserted after printing of the image on the printing medium is started, the control unit controls the printing unit and the conveying unit to perform a first scan in at least one scan before the stop operation and to perform a second scan in at least one scan before the stop operation. And performing a second scan in at least one scan which is restarted after a predetermined time elapses from the stop, the first scan being a scan which scans the printing element array without printing the printing area that has not yet been printed, and the second scan being a scan which performs printing of a remaining portion of the printing area that has not been printed in the first scan.

Description

Technical Field

[0001] The present disclosure relates to controlling a printing apparatus for printing an image on a printing medium through a multi-pass printing method. Background Art

[0002] There is an inkjet printing apparatus that adopts a multi-pass printing method, in which an image is printed on a predetermined printing area on a printing medium by scanning a print head multiple times. During the multi-pass printing, the printing operation sometimes stops from one scan to the next scan. The printing operation stops for various reasons, such as erasing and sucking ink attached to the ejection port surface of the print head, managing the temperature of the print head, and cutting the printing medium. In the event of such a stoppage, the color and gloss of the area printed before and after the stoppage may become different from other areas and may be visually recognized as uneven.

[0003] In order to solve the unevenness due to the stoppage, Japanese Patent Laid-Open No. 2004-174825 (Patent Document 1) discloses a technique of completing multi-pass printing before the stoppage occurs and then restarting normal multi-pass printing after a predetermined stoppage time has elapsed.

[0004] Here, the technology of Patent Document 1 requires one or more additional scans in order to temporarily complete multi-pass printing. Specifically, for multi-pass printing with n passes, (n-1) additional scans are required. In other words, the throughput decreases more seriously as the number of passes increases. Summary of the invention

[0005] An object of the present disclosure is to prevent or reduce a reduction in throughput of multi-pass printing, and also to prevent or reduce the occurrence of unevenness on areas printed before and after stopping.

[0006] According to an embodiment of the present disclosure, a printing device includes: a printing unit including a printing element array and configured to scan the printing element array in a first direction, the printing element array being an array of a plurality of printing elements for applying ink to a printing medium; a conveying unit configured to convey the printing medium in a second direction intersecting the first direction; and a control unit configured to control the printing unit and the conveying unit to repeatedly cause the printing unit to scan a unit area on the printing medium a plurality of times and cause the conveying unit to convey over a distance shorter than the length of the arrangement range of the printing element array in the first direction. In a case where a stop operation for causing the printing unit not to scan for a predetermined time or longer is inserted after starting printing of an image on the printing medium, the control unit controls the printing unit and the conveying unit to perform a first scan in at least one scan before the stop operation and to perform a second scan in at least one scan started again after a predetermined time has passed from the stop operation, the first scan being a scan for scanning the printing element array without printing a printing area that has not been printed, and the second scan being a scan for printing the remaining portion of the printing area that has not been printed in the first scan.

[0007] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a stereogram of an inkjet printing device;

[0009] Figure 2 is a diagram schematically showing a cross section of an inkjet printing apparatus;

[0010] Figure 3 is a diagram showing an example of an ejection port array of a print head;

[0011] Figure 4 is a diagram showing a configuration of a control system in an inkjet printing apparatus;

[0012] Figure 5 is a diagram used to illustrate multi-pass printing;

[0013] Figure 6 is a diagram showing an example of a mask pattern to be used in a normal print scan;

[0014] Fig. 7A and Figure 7B is a diagram used to illustrate the appearance of density non-uniformity at the time of stopping;

[0015] FIG. 8A to FIG. 8C is a schematic diagram for explaining the factors causing the occurrence of density inhomogeneity;

[0016] 9A to 9C is a schematic diagram for explaining the factors causing the occurrence of density inhomogeneity;

[0017] Fig. 10A and Fig. 10B is a diagram showing an example of a mask pattern to be used before and after stopping;

[0018] Fig.11 is a table for explaining the printing control in the first embodiment;

[0019] Fig.12 is a flowchart showing the flow of print control in the first embodiment;

[0020] Fig.13 is a diagram for explaining an image formed by printing scanning before and after stopping;

[0021] Fig.14 is a diagram showing known image printing as a comparative example;

[0022] FIG. 15A to FIG. 15F is a diagram showing an example of a mask pattern used in the second embodiment;

[0023] Fig.16 is a table for explaining the printing control in the second embodiment;

[0024] Fig.17 is a flowchart showing the flow of print control in the second embodiment;

[0025] Fig.18 is a diagram for explaining image printing in the second embodiment;

[0026] Fig.19 is a diagram showing an example of a mask pattern used in the third embodiment;

[0027] Fig. 20 is a table for explaining the printing control in the third embodiment;

[0028] Fig.21 is a flowchart showing the flow of print control in the third embodiment;

[0029] Fig. 22 is a diagram for explaining image printing in the third embodiment;

[0030] Fig.23 is a diagram showing an example of a mask pattern used in the fourth embodiment;

[0031] Fig.24 is a table for explaining the printing control in the fourth embodiment;

[0032] Fig.25is a flowchart showing the flow of print control in the fourth embodiment; and

[0033] Fig.26 It is a diagram for explaining image printing in the fourth embodiment. DETAILED DESCRIPTION

[0034] Hereinafter, with reference to the accompanying drawings, the present disclosure describes some exemplary embodiments in detail. The configurations shown in the following embodiments are merely exemplary, and some embodiments of the present disclosure are not limited to the schematically shown configurations.

[0035] <First Embodiment>

[0036] A first embodiment of the present disclosure will be described below with reference to the drawings.

[0037] (1) Configuration of inkjet printing equipment

[0038] Figure 1 1 is a perspective view schematically showing the configuration of an inkjet printing apparatus (hereinafter referred to as a printing apparatus 100 ) according to the present embodiment. Figure 2 1 is a cross-sectional view along the YZ plane, which schematically shows the carriage unit 102 and the conveying unit of the printing apparatus 100. Note that Figure 1 A state in which the top cover is opened is shown to explain the mechanism inside the printing apparatus 100 .

[0039] like Figure 1 and Figure 2 As shown, the printing apparatus 100 includes a carriage unit 102, a guide shaft 108, a print head 109, a platen 104, an encoder 107, a conveying roller 103, an auxiliary roller 105, a spool 106, a winding spool 112, a heater 110, and the like.

[0040] The carriage unit 102 is composed of Figure 1 and Figure 2 The carriage unit 102 is supported by a guide shaft 108 extending in the X direction as the main scanning direction so as to be movable in the X direction. The carriage unit 102 reciprocates in the main scanning direction by a moving mechanism including a carriage motor and a carriage belt. A print head 109 is mounted on the carriage unit 102. A flexible printed circuit board 119 is attached to the print head 109, and a drive pulse for performing an inkjet operation and a heating temperature adjustment signal are supplied to the print head 109 through the flexible printed circuit board 119. The other end of the flexible printed circuit board 119 is connected to a main control unit 400 ( Figure 4 ).

[0041] The print head 109 moves together with the carriage unit 102 in the main scanning direction, and ejects ink according to a print signal during the movement, thereby performing printing on the print medium P.

[0042] The print medium P is conveyed in a conveying direction (direction X) intersecting (in this example, perpendicularly intersecting) the main scanning direction (direction X). Figure 1 and Figure 2 The printing medium P is transported in the +Y direction (in the Y direction). The printing medium P is transported by the transport roller 103 and the auxiliary roller 105, which are a pair of rollers operated by a transport motor not shown. In the transport operation (sub-scanning), the printing device 100 rotates the transport roller 103 while pressing the printing medium P with the auxiliary roller 105, thereby transporting the printing medium P held on the reel 106 by a predetermined transport amount in the +Y direction. As a result, the printing medium P is guided to the printing position on the platen 104 (i.e., inside the area scanned by the print head 109). The platen 104 is used to stably support the printing medium P.

[0043] The printing apparatus 100 in this embodiment is a so-called serial type printing apparatus The serial type printing apparatus 100 alternately repeats a conveying operation of conveying the printing medium P in the conveying direction and a printing operation of scanning the print head 109 in the main scanning direction.

[0044] In response to a command for starting printing being input from a host device connected to the printing device 100, the printing medium P is fed to the printing position under the control of the main control unit 400. Then, the printing data for a single scan (i.e., the printing data for a single band) is accumulated in the buffer, after which the carriage unit 102 is scanned to perform a printing operation. Note that the printing operation involving scanning the carriage unit 102 will be referred to herein as "print scanning".

[0045] In the print scan, ink is ejected from the ejection ports of the print head 109 according to the print data at a timing based on the position signal obtained from the encoder 107. As a result, an image is printed on a print area having a bandwidth corresponding to the range of the ejection port arrangement. Thereafter, the print medium P is conveyed by a predetermined amount, and the next print scan is performed. In the present embodiment, in one example, the inkjet operation is performed at a print scan speed of 30 inches per second and a print resolution of 1200 dpi (1 / 1200 inch interval). Note that this is merely an example, and the present embodiment is not limited to these values.

[0046] Here, the printing apparatus 100 in the present embodiment performs so-called multi-pass printing in which the print head 109 is scanned a plurality of times to print an image for the same printing area on the print medium P. The multi-pass printing will be described in detail later.

[0047] A curing region is provided at a downstream (+Y) position relative to the print head 109 in the conveying direction. A heater 110 is provided at the curing region. The heater 110 dries the liquid ink applied to the print medium P by heating. For example, a sheath heater or a halogen heater or the like is used as the heater 110. A heater cover 111 covers the heater 110 and is used to efficiently irradiate the print medium P with the heat of the heater 110 and protect the heater 110.

[0048] The heating temperature at the above-mentioned curing area is set in consideration of the film-forming property and productivity of the water-soluble resin fine particles and the heat resistance of the print medium P. As a method of heating at the curing area, heating by warm air sent from above or heating by a heater that transfers heat by contact from the lower side of the print medium P, etc. is used. In the present embodiment, heating at the curing area by the heating unit occurs at one position, but may occur at two or more positions as long as the temperature measured on the print medium P by a radiation thermometer (not shown) does not exceed the set value of the heating temperature.

[0049] The print medium P printed by the print head 109 and heated by the heater 110 is wound by the take-up reel 112 to form a medium 113 wound into a roll.

[0050] Note that in the above description, an example is presented in which the moving mechanism for the carriage unit 102 includes a carriage motor and a carriage belt, etc., but the present embodiment is not limited to this example. Other driving methods may be used, such as a driving method in which, for example, a lead screw extending in the X direction and rotationally driven by a carriage motor is provided instead of the carriage belt, and a thread in the lead screw and an engaging portion provided in the carriage unit 102 engage with each other to drive the carriage unit 102.

[0051] In addition, when stationary, the ejection port face of the print head 109 is usually covered. Therefore, before printing, it is necessary to release the cover and prepare the carriage unit 102 to be scanned.

[0052] (2) Print head configuration

[0053] Figure 3 An example of the ejection port face of the print head 109 is shown. Specifically, the print head 109 includes ejection port arrays 31K, 31C, 31M, and 31Y that eject black ink (K), cyan ink (C), magenta ink (M), and yellow ink (Y) as inks containing colorants, respectively. Since these inks contain colorants, they will also be referred to as "colorant inks" or "color inks" in the following description.

[0054] The print head 109 also includes an ejection port array 31RCT that ejects a reactive liquid ink (RCT) that does not contain a colorant. The reactive liquid ink that does not contain a colorant contains a reactive component that reacts with a colorant contained in the colorant ink, and reacts in response to contacting the colorant ink on the print medium P, thereby preventing or reducing bleeding of the colorant ink.

[0055] In the print head 109, the ejection port arrays 31K, 31C, 31M, 31Y, and 31RCT are arranged in a Figure 3 31A and 31B are arranged side by side in this order from left to right in the X direction of the nozzle array 31K. In each of these nozzle arrays 31K, 31C, 31M, 31Y and 31RCT, 1280 nozzles 30 ejecting corresponding inks are arranged in the Y direction (array direction) at a density of 1200 dpi. The volume (ejection amount) of ink droplets to be ejected from a single nozzle 30 is about 4.5 pl.

[0056] Each of the ejection port arrays 31K, 31C, 31M, 31Y, and 31RCT is connected to an ink cartridge for storing the corresponding ink, and is supplied with ink from the ink cartridge. Incidentally, the print head 109 and the ink cartridge may be formed integrally with each other, and configured to be separable from each other. In addition, each of the above-mentioned colorant inks may contain water-soluble resin fine particles that become a film by being heated to improve the scratch resistance of the image to be printed on the print medium P.

[0057] The printing element that generates ejection energy to eject ink is located at each outlet of the print head. In this embodiment, the printing element and the ejection outlet will be referred to as an ejection outlet including the printing element and the ejection outlet. Note that the print head 109 used in the printing device 100 of the present disclosure is not limited to Figure 3 The density, arrangement and diameter of the ejection ports, the amount of ink to be ejected from the ejection ports, the type of ink, etc. may be changed appropriately.

[0058] (3) Control configuration of printing equipment

[0059] Figure 4 4 is a block diagram showing a control configuration of the printing apparatus 100 in the present embodiment. The main control unit 400 of the printing apparatus 100 has a central processing unit (CPU) 401, a read-only memory (ROM) 402, a random access memory (RAM) 403, an input / output port 404, a memory 405, etc. Drive circuits 406, 407, 408, and 409, an interface circuit 413, an operation panel 150, etc. are connected to the main control unit 400 via the input / output port 404.

[0060] The CPU 401 calls a program stored in the memory 405 or the ROM 402 into a work area in the RAM 403 and executes the program. The ROM 402 permanently holds programs such as a boot program and a basic input output system (BIOS), and data, etc. The RAM 403 includes a work area that temporarily holds a program loaded from the memory 405 or the ROM 402 and is used by the CPU 401 for processing.

[0061] The memory 405 is a storage device such as a hard disk drive (HDD), a solid state drive (SSD), or a flash memory, etc. The memory 405 stores programs, various data required to execute the programs and mask patterns described later, etc., as well as print job data and print log data of the printing apparatus 100, etc.

[0062] The drive circuit 406 is connected to a conveying motor (line feed (LF) motor) 410. The drive circuit 407 is connected to a carriage motor (CR (carriage) motor) 411. The drive circuit 408 is connected to the print head 109. The drive circuit 409 is connected to the heater 110. In addition to the above, the actuator in the cutting unit for cutting the print medium P and the drive circuits of other drive units are connected to the main control unit 400. The drive circuits 406, 407, 408, 409...drive the conveying motor, the carriage motor, the print head 109, the heater 110, the actuator, etc. according to the control signal from the CPU 401.

[0063] The operation panel 150 includes a touch panel display and buttons, etc., and displays display information input from the CPU 401. The display information includes, for example, the status of the printing apparatus 100 and information related to the print medium P, etc. In addition, the operation panel 150 accepts an operation for starting and stopping a printing operation from a user, and inputs an operation signal into the CPU 401.

[0064] In addition, the main control unit 400 is connected to a host device 414 through an interface circuit 413. The host device 414 is a computer such as a personal computer (PC), a smart phone, or a server device, and sends a print job to the printing device 100. After receiving the print job, the main control unit 400 stores the print job in the memory 405 or the RAM 403, and performs a printing operation according to the print job. The main control unit 400 sends the status of the printing device 100 and information related to the print medium P, etc. to the host device 414, and causes the host device 414 to display them on its display unit.

[0065] (4) <Multi-pass printing method>

[0066] As described above, the printing apparatus 100 in the present embodiment prints an image by a so-called multi-pass printing method in which the same printing area on the printing medium P is scanned for printing multiple times using each of the inks K, C, M, Y, and RCT to complete image printing. The multi-pass printing method will now be described below.

[0067] Figure 5 It is a diagram for explaining the multi-pass printing method. Figure 5 An example in which the number of passes is six is ​​shown. In the six-pass printing, each ejection port array 31 of the print head 109 is divided into six ejection port groups (ejection port groups A1 to A6) in the Y direction. For the print area 500 on the print medium P, each section ejects ink once, so that a total of six print scans are performed to complete the image. The length of each ejection port group in the ejection port groups A1 to A6 in the Y direction corresponds to the width of the print area 500 in the Y direction.

[0068] Note that, in reality, the print medium P is conveyed downstream in the Y direction (Y(+) direction) between a print scan of the print head 109 and its next scan. Figure 5 In the figure, the print head 109 moves upstream in the Y direction (Y(-) direction) for the same explanation.

[0069] In the first print scan (first pass), the positional relationship is such that the print area 500 and the ejection port group A1 on the print medium P face each other. The print head 109 in this positional relationship is scanned in the X direction. During the scan, each of the ejection port groups A1 to A6 of the print head 109 ejects ink according to the print data of the first print scan. As a result, focusing on the print area 500, the ink droplets ejected from the ejection port group A1 land and form an image. Note that the print data is generated for each ink type.

[0070] After the first print scan, the print medium P is conveyed in the Y direction over a distance corresponding to a single orifice group, ie, the width of the print area 500. As a result of this conveying operation, the positional relationship becomes such that the orifice group A2 faces the print area 500.

[0071] In the second printing scan (second pass), ink droplets ejected from the ejection port group A2 land on the printing area 500. After the second printing scan, the printing medium P is conveyed over a distance corresponding to a single ejection port group in the Y direction. As a result of this conveying operation, the positional relationship becomes such that the ejection port group A3 faces the printing area 500.

[0072] Subsequently, in the third to sixth print scans, the ejection operation of the print head 109 and the conveyance operation of the print medium P are alternately performed in a similar manner. As a result, ink droplets ejected from the ejection port groups A3 to A6 land on the print area 500. This completes 6-pass printing on the print area 500.

[0073] (5) Mask pattern

[0074] Figure 6 FIG. 1 is a diagram showing a general mask pattern used to generate print data. Figure 6 In the mask pattern shown, each pixel depicted in black represents a pixel for which ink ejection is permitted (hereinafter referred to as a "print-permitted pixel"), while each pixel shown as a blank dot represents a pixel for which ink ejection is not permitted (hereinafter referred to as a "print-prohibited pixel"). Applying such a mask pattern to a pixel to which ink is set to be ejected according to binary data will result in ink ejection to the print-permitted pixel and no ink ejection to the print-prohibited pixel.

[0075] Notice, Figure 6 Six types of mask patterns 601 to 606 are shown, and the unit areas of these six types of mask patterns 601 to 606 each have a size of 4 pixels (Y direction) × 8 pixels (X direction). Mask pattern 601 is applied to ejection port group A1, mask pattern 602 is applied to ejection port group A2, and mask pattern 603 is applied to ejection port group A3. Similarly, mask patterns 604 to 606 are applied to ejection port groups A4 to A6, respectively. These mask patterns 601 to 606 are repeatedly applied in the X direction and the Y direction to perform distribution processing on the entire binary data corresponding to the print area. As a result, print data is generated.

[0076] Figure 6 The number of pixels present in each unit area shown is 4 pixels×8 pixels=32 pixels, and there are a total of 48 print-permitted pixels (black) in the six types of mask patterns 601 to 606. Here, the ratio of the number of print-permitted pixels to the number of pixels in the mask pattern is referred to as a "printing rate". Thus, Figure 6 The total printing rate of the mask pattern shown is 150 (= 48 / 32×100) %.

[0077] Here, focusing on the mask pattern to be used in the print scan of the print area 500 of interest, six print-permitted pixels are arranged in the mask pattern 601 for the first print scan (ejection port group A1), and five print-permitted pixels are arranged in the mask pattern 606 for the sixth print scan (ejection port group A6). Thus, the printing rate of each of the mask patterns for the first print scan and the sixth print scan is approximately 20% (=6 / 32×100).

[0078] Furthermore, eight print-permitted pixels are arranged in each of the mask pattern 602 for the second print scan (second pass) (ejection orifice group A2) and the mask pattern 605 for the fifth print scan (fifth pass) (ejection orifice group A5). Thus, the printing rate of each of the mask patterns for the second print scan and the fifth print scan is approximately 25% (=8 / 32×100).

[0079] Finally, 11 print-permitted pixels are arranged in each of the mask pattern 603 for the third print scan (third pass) (ejection port group A3) and the mask pattern 604 for the fourth print scan (fourth pass) (ejection port group A4). Thus, the printing rate of each of the mask patterns for the third print scan and the fourth print scan is approximately 30% (=11 / 32×100).

[0080] In short, when using Figure 6 In the case of the mask pattern 600 shown, in the first to sixth passes, the amount of ink to be ejected is the largest in the third and fourth passes and the smallest in the first and sixth passes. That is, the printing rate is the smallest at the ejection port group at the end in the conveying direction and the largest at the ejection port group at the center.

[0081] (6) Ink composition

[0082] (Brief description of ink composition)

[0083] The details of the inks forming the ink set used in this embodiment will now be described. In the following, "part" and "%" are based on mass unless otherwise specified.

[0084] (6-1) Composition of ink

[0085] Now, the composition of each ink will be described in detail below.

[0086] The color inks (C, M, Y and K), the transparent ink (Em) and the reaction liquid ink (RCT) used in this embodiment each contain a water-soluble organic solvent. Considering the wettability and moisture retention of the ejection orifice surface of the print head 109, the water-soluble organic solvent is preferably a water-soluble organic solvent having a boiling point of 150° C. or more and 300° C. or less.

[0087] Ketone compounds such as acetone and cyclohexanone, propylene glycol derivatives such as tetraglyme, and heterocyclic compounds having a lactam structure represented by N-methylpyrrolidone and 2-pyrrolidone are particularly preferred from the viewpoint of the film-forming auxiliary function of the resin fine particles and the expansion and dissolution in the print medium P formed with the resin layer. From the viewpoint of ejection performance, the content of the water-soluble organic solvent is preferably 3 wt % or more and 30 wt % or less.

[0088] Specific examples of the water-soluble organic solvent include: alkyl alcohols having one to four carbon atoms, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, and tert-butanol; amides, such as dimethylformamide and dimethylacetamide; ketones or ketone alcohols, such as acetone and diacetone alcohol; ethers, such as tetrahydrofuran and dioxane; polyalkylene glycols, such as polyethylene glycol and polypropylene glycol; ethylene glycol; alkylene glycols having an alkylene group containing two to six carbon atoms, such as propylene glycol, butanediol, and the like. glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexanediol and diethylene glycol, etc.; lower alkyl ether acetates, such as polyethylene glycol monomethyl ether acetate, etc.; glycerol; and lower alkyl ethers of polyols, such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether and triethylene glycol monomethyl (or ethyl) ether, etc.; polyols, such as trimethylolpropane and trimethylolethane, etc.; N-methyl-2-pyrrolidone; 2-pyrrolidone; and 1,3-dimethyl-2-imidazolidinone, etc.

[0089] The water-soluble organic solvents listed above can be used alone or as a mixture. It is desirable to use deionized water as water. The content of the water-soluble organic solvent in the reaction liquid ink (RCT) is not particularly limited. In addition to the above-mentioned components, in order to impart the desired physical properties, a surfactant, a defoamer, a preservative, an antifungal agent, etc. can be appropriately added to each colorant ink (C, M, Y and K).

[0090] The color inks (C, M, Y and K) and the reaction liquid ink (RCT) used in this embodiment each contain a surfactant. The surfactant is used as a penetrant to improve the permeability of the ink into the print medium P dedicated to inkjet printing. The greater the amount of surfactant added, the stronger the property of reducing the surface tension of the ink, and the more the wettability and permeability of the ink on and into the print medium P are improved.

[0091] In this embodiment, a small amount of acetylene glycol EO adduct is added as a surfactant to adjust the surface tension of each ink to less than 30 dyn / cm, and to adjust the difference in surface tension between the inks to less than 2 dyn / cm. More specifically, the surface tension of all inks is set to about 22 to 24 dyn / cm. The surface tension is measured using a fully automatic surface tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.). The measuring device is not limited to the measuring device exemplarily mentioned above, as long as the surface tension of each ink can be measured.

[0092] Meanwhile, the pH of each ink in the present embodiment is stable on the alkaline side, and the value is 8.5 to 9.5. From the viewpoint of preventing the dissolution and degradation of the components contacting the ink inside the printing device 100 and the print head 109 and reducing the solubility of the dispersed resin in the ink, etc., the pH of each ink is preferably 7.0 or more and 10.0 or less. The pH is measured using a pH meter F-52 manufactured by HORIBA, Ltd. Note that the measuring device is not limited to the measuring device exemplarily mentioned above, as long as the pH of each ink can be measured.

[0093] (6-2) Reaction solution

[0094] In this embodiment, in order to solve problems such as bleeding and beading, a reaction liquid for insolubilizing a part or all of the solid components of the color material ink is used.

[0095] The reaction liquid is intended to insolubilize dissolved dyes and dispersed pigments and resins, etc. Thus, examples thereof include solutions containing polyvalent metal ions (e.g., magnesium nitrate, magnesium chloride, aluminum sulfate, and ferric chloride, etc.). As one type of coagulation effect using such cations, a system using a cationic polymer coagulant having a low molecular weight for the purpose of neutralizing the charge of water-soluble resin fine particles and insolubilizing anionic soluble substances can also be used.

[0096] In addition, as another reaction system, there is an insolubilization system with a reaction liquid that utilizes a difference in pH. As mentioned above, most of the color inks in the color inks generally used in inkjet printing are stable on the alkaline side due to the characteristics of their colorants, etc. Color inks with a pH of about 7 to 10 are general, and from an industrial perspective and in consideration of the influence of the external environment, etc., the pH is mainly set to about 8.5 to 9.5. In order to have the aggregation and solidification of the color ink of this system, an acidic solution can be added to change their pH, thereby destroying the stable state and aggregating the dispersed components. In order to achieve such an effect, an acidic solution can be used as a reaction liquid.

[0097] (6-3) Water-soluble resin fine particles

[0098] The colorant ink and transparent ink (Em) used in this embodiment contain water-soluble resin fine particles. "Water-soluble resin fine particles" refer to polymer fine particles that exist in a dispersed state in water. Specific examples include: fine particles of acrylic resin synthesized by emulsion polymerization of monomers such as (meth) alkyl acrylate or (meth) alkyl amide of acrylic acid; fine particles of styrene-acrylic resin synthesized by emulsion polymerization of monomers such as (meth) alkyl acrylate or (meth) alkyl amide of acrylic acid and styrene; fine particles of polyethylene resin; fine particles of polypropylene resin; fine particles of polyurethane resin; and fine particles of styrene-butadiene resin, etc. In addition, the water-soluble resin fine particles may be: core-shell type resin fine particles, which are resin fine particles formed by a core and a shell part each having a different polymer composition from each other; or resin fine particles obtained by preparing acrylic fine particles synthesized in advance as seed particles for controlling the particle size, and then allowing emulsion polymerization to be performed around the acrylic fine particles, etc. Furthermore, the water-soluble resin fine particles may be hybrid resin fine particles obtained by chemically combining different types of resin fine particles such as acrylic resin fine particles and urethane resin fine particles.

[0099] (6-4) Composition of ink

[0100] The details of the inks forming the ink set used in this embodiment will now be described. In the following, "parts" and "%" are based on mass unless otherwise specified.

[0101] (6-4-1) Black ink

[0102] (i) Preparation of dispersion

[0103] First, an anionic polymer P-1 (styrene / butyl acrylate / acrylic acid copolymer (polymerization ratio (weight ratio) = 30 / 40 / 30), acid value = 202, weight average molecular weight = 6500) was prepared. The anionic polymer P-1 was neutralized with a potassium hydroxide aqueous solution and diluted with deionized water to prepare a homogeneous 10% by mass dispersion of water-soluble resin fine particles.

[0104] Then, 600 g of the above-mentioned water-soluble resin fine particle dispersion, 100 g of carbon black and 300 g of deionized water were mixed, mechanically stirred for a predetermined time, and centrifuged to remove non-dispersed matter including coarse particles, thereby obtaining a black dispersion. The obtained black dispersion has a pigment concentration of 10% by mass.

[0105] (ii) Preparation of ink

[0106] In the ink preparation, the above-mentioned black dispersion was used. The following components were added to the black dispersion to a predetermined concentration. In addition, these components were fully mixed and stirred, and then filtered under pressure through a microfilter (manufactured by FUJIFILM Corporation) with a pore size of 2.5 μm to prepare a pigment ink with a pigment concentration of 2% by mass.

[0107]

[0108]

[0109] (6-4-2) Cyan ink

[0110] (i) Preparation of dispersion

[0111] First, an AB type block polymer having an acid value of 250 and a number average molecular weight of 3000 was produced in a conventional manner using benzyl acrylate and methacrylic acid as raw materials, neutralized with an aqueous potassium hydroxide solution, and diluted with deionized water to prepare a homogeneous 50 mass % water-soluble resin fine particle dispersion.

[0112] Then, 200 g of the above-mentioned water-soluble resin fine particle dispersion, 100 g of CI Pigment Blue 15:3 and 700 g of deionized water were mixed, mechanically stirred for a predetermined time, and centrifuged to remove non-dispersed matter including coarse particles, thereby obtaining a cyan dispersion. The obtained cyan dispersion had a pigment concentration of 10% by mass.

[0113] (ii) Preparation of ink

[0114] In the ink preparation, the above-mentioned cyan dispersion was used. The following components were added to the cyan dispersion to a predetermined concentration. In addition, these components were fully mixed and stirred, and then filtered under pressure through a microfilter (manufactured by Fujifilm Corporation) with a pore size of 2.5 μm to prepare a pigment ink with a pigment concentration of 2% by mass.

[0115]

[0116] (6-4-3) Magenta ink

[0117] (i) Preparation of dispersion

[0118] First, an AB type block polymer having an acid value of 300 and a number average molecular weight of 2500 was produced in a conventional manner using benzyl acrylate and methacrylic acid as raw materials, neutralized with an aqueous potassium hydroxide solution, and diluted with deionized water to prepare a homogeneous 50 mass % water-soluble resin fine particle dispersion.

[0119] Then, 100 g of the above-mentioned water-soluble resin fine particle dispersion, 100 g of CI Pigment Red 122 and 800 g of deionized water were mixed, mechanically stirred for a predetermined time, and centrifuged to remove non-dispersed matter including coarse particles, thereby obtaining a magenta dispersion. The obtained magenta dispersion had a pigment concentration of 10% by mass.

[0120] (ii) Preparation of ink

[0121] In the ink preparation, the above-mentioned magenta dispersion was used. The following components were added to the magenta dispersion to a predetermined concentration. In addition, these components were fully mixed and stirred, and then filtered under pressure through a microfilter (manufactured by FUJIFILM Corporation) with a pore size of 2.5 μm to prepare a pigment ink with a pigment concentration of 3% by mass.

[0122]

[0123] (6-4-4) Yellow ink

[0124] (i) Preparation of dispersion

[0125] First, the anionic polymer P-1 was neutralized with an aqueous potassium hydroxide solution and diluted with deionized water to prepare a homogeneous 10 mass % dispersion of water-soluble resin fine particles.

[0126] Then, 300 g of the above-mentioned water-soluble resin fine particle dispersion, 100 g of CI Pigment Yellow 74 and 600 g of deionized water were mixed, mechanically stirred for a predetermined time, and centrifuged to remove non-dispersed matter including coarse particles, thereby obtaining a yellow dispersion. The obtained yellow dispersion has a pigment concentration of 10% by mass.

[0127] (ii) Preparation of ink

[0128] The following ingredients were mixed and stirred sufficiently to be dissolved and dispersed, and then filtered under pressure through a microfilter (manufactured by FUJIFILM Corporation) having a pore size of 1.0 μm to prepare a pigment ink having a pigment concentration of 4% by mass.

[0129]

[0130] (6-4-5) Transparent ink

[0131] Ink preparation

[0132] The following ingredients were mixed and stirred sufficiently to be dissolved and dispersed, and then filtered under pressure through a microfilter (manufactured by FUJIFILM Corporation) having a pore size of 1.0 μm.

[0133]

[0134]

[0135] (6-4-6) Reaction solution

[0136] The reaction liquid used in this embodiment contains a reactive component that reacts with a pigment contained in the ink to aggregate or gel the pigment. Specifically, in the case where the reaction liquid is mixed with an ink containing a pigment stably dispersed in an aqueous medium by the action of an ionic group on a printing medium or the like, the reactive component may destroy the stability of the dispersion in the ink. In particular, glutaric acid is used in this embodiment.

[0137] Note that glutaric acid does not necessarily have to be used. In this embodiment, any of various organic acids and polyvalent metal salts can be used as the reactive component of the reaction solution as long as it is water-soluble. The content of the organic acid or polyvalent metal salt relative to the total mass of the composition contained in the reaction solution is preferably 0.1 mass % or more and 90.0 mass % or less, and more preferably 1.0 mass % or more and 70.0 mass % or less.

[0138] Ink preparation

[0139] In this example, glutaric acid (manufactured by FUJIFILM Wako Pure Chemical Corporation) was used, and the following components were mixed to prepare a reaction liquid.

[0140]

[0141] (7) Printing media

[0142] In this embodiment, a low-permeability printing medium that is not easily permeable to water is used. A low-permeability printing medium refers to a medium that does not absorb water at all or absorbs only a very small amount of water. Thus, in the case of using an aqueous ink that does not contain an organic solvent, the ink will be repelled, making it difficult to form an image. On the other hand, a low-permeability printing medium has excellent water resistance and weather resistance, and is suitable as a medium for printed materials to be used outdoors. Typically, a printing medium having a water contact angle of 45° or more and preferably 60° or more at 25°C is used.

[0143] Examples of low-permeability printing media include: printing media including a substrate having a plastic layer formed on the outermost surface of the substrate; printing media including a substrate without an ink receiving layer formed on the substrate; and sheets, films, or banners made of glass, YUPO, or plastic, etc. Examples of coated plastics include: polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene, etc. These low-permeability printing media have excellent water resistance, light resistance, and scratch resistance, and are therefore generally used in the case of printing printed materials to be displayed outdoors.

[0144] As an example method for evaluating the permeability of a print medium, the Bristow method described in "Paper and Paperboard-Liquid Absorption Test Method" No. 51 in the Japanese TAPPI Paper and Pulp Test Method can be used. In the Bristow method, a predetermined amount of ink is injected into a container having an opening slit of a predetermined size, and the ink is brought into contact with a print medium cut into strips and wound on a disk through the slit, the disk is rotated while the position of the container is fixed, and the area (length) of the ink ribbon transferred to the print medium is measured. Based on this area of ​​the ink ribbon, the transfer amount per unit area in 1 second (ml·m-2) can be calculated. In this embodiment, when the amount of ink transferred (water absorption) in 30msec 1 / 2 in the above-mentioned Bristow method is less than 10ml·m-2, the print medium is considered to be a low-permeability print medium. Therefore, the print medium can be a non-permeable print medium.

[0145] In the present embodiment, as the low-permeability printing medium, Scotchcal Graphic Film (IJ1220-10) which is a vinyl chloride film with an adhesive manufactured by 3M is used.

[0146] (8) Print control

[0147] (8-1) Stopping the Printing Operation

[0148] The printing operation may stop for a predetermined time between a print scan and the next print scan. There are some reasons for the stoppage, and the following are representative reasons.

[0149] The first reason is a stop of about several seconds for wiping ink attached to the ejection port surface of the head by a mechanism moving a cloth or a wiper. The second reason is a stop of ten to several tens of seconds for remedying bad ink ejection by sucking ink from the ejection port of the head by a suction mechanism. In addition to the above, there are stops for lowering the temperature of the head in the case where the head is overheated, stops for cutting the print medium, and the like.

[0150] (8-2) Problem of stopping printing operation

[0151] In a case where the printing operation is stopped, color and gloss may change at an area printed in a print scan after the printing operation is restarted, and unevenness may occur at the area.

[0152] Fig. 7A and Figure 7B It is a diagram for explaining the occurrence of unevenness at the time of stopping. Fig. 7A and Figure 7B Multi-pass printing with a pass number of six is ​​shown. Fig. 7A The positions of the ejection port array 31 in the four print scans before stopping and the image 710 printed by the print scans before stopping are shown. The print scan immediately before stopping will be referred to as the i-th print scan. The first, second, third, and subsequent print scans before the i-th print scan will be referred to as the (i-1)-th print scan, the (i-2)-th print scan, the (i-3)-th print scan, ... print scans, respectively. Areas 711 to 719 indicate the printing status of the print area printed in the print scans until the i-th print scan by shades of gray.

[0153] Through the print scans up to the (i-3)th print scan, ink droplets land on areas 711 to 716.

[0154] Through the (i-2)th printing scan, ink droplets land on areas 712 to 717.

[0155] Through the (i-1)th printing scan, ink droplets land on areas 713 to 718.

[0156] Through the i-th printing scan, ink droplets land on areas 714 to 719.

[0157] Areas 711 to 714 each represent an area that is printed six times. Area 715 represents an area that is printed five times. Area 716 represents an area that is printed four times. Area 717 represents an area that is printed three times. Area 718 represents an area that is printed twice. Area 719 represents an area that is printed once. In other words, the images at areas 711 to 714 are completed. The images at areas 715 to 719 are not completed.

[0158] After the i-th printing scan, the printing operation stops and restarts after a predetermined stop time has elapsed. Figure 7B The state in which the (i+1)th to (i+6)th print scans have been performed after the restart is shown.

[0159] Through the (i+1)th printing scan, ink droplets land on areas 715 to 719 and area 720.

[0160] Through the (i+2)th printing scan, ink droplets land on areas 716 to 720 and area 721.

[0161] Through the (i+3)th printing scan, ink droplets land on areas 717 to 721 and area 722.

[0162] Through the (i+4)th printing scan, ink droplets land on areas 718 to 722 and area 723.

[0163] Through the (i+5)th printing scan, ink droplets land on areas 719 to 723 and area 724.

[0164] Through the (i+6)th printing scan, ink droplets land on areas 720 to 724 and area 725.

[0165] As described above, the region 730 including the regions 715 to 719 is a region where the 6-pass multi-pass printing is not completed before stopping and thus the image is not completed. Unevenness occurs in this region 730 .

[0166] According to the research of the present inventors, it was found that the degree of unevenness varies depending on the position in the area 730 that was in the middle of printing before stopping. Specifically, in the area 730 that was in the middle of printing before stopping, the degree of unevenness tends to be higher in the area with fewer printing times (less printing passes). In particular, it was found that obvious unevenness appeared in the area 719 that was printed only once (printed only by the first pass) before stopping.

[0167] A possible cause of this is bleeding of ink droplets.

[0168] FIG. 8A to FIG. 8C This is a diagram for explaining the phenomenon of ink droplet bleeding in printing performed by normal operation without stopping. Fig. 8A A state is shown in which ink droplets 800 have landed on the print medium P as a result of the first printing. Figure 8B The state is shown immediately after the ink droplet 801 is printed adjacent to the ink droplet 800 in the next pass. Figure 8C 801 is a diagram showing a state after a predetermined time has passed since the ink droplet 801 was printed in the next pass. FIG. 8A to FIG. 8C As shown, the ink droplets 800 in the first pass are usually printed in an isolated manner; however, in the printing of the next pass, the ink droplets 800 in the first pass and the ink droplets 801 in the next pass contact each other. As a result, bleeding occurs to a certain extent after a predetermined time has passed.

[0169] on the other hand, 9A to 9CThis is a diagram for explaining bleeding of ink droplets when printing is stopped after the first printing (after the first-pass printing) and then printing is started again. Fig.9A 1 shows the state of ink droplets 900 that have landed on the print medium P by the first printing. Then, in the case where the printing operation is stopped and restarted after a predetermined time has passed, as shown in FIG. Fig. 9B As shown, ink droplets 901 in the next pass (second pass) are printed adjacent to ink droplets 900. During the stop period, the water in ink droplets 900 in the first pass is dried, causing the viscosity to increase. Fig. 9C The state of ink droplets 900 and 901 after a predetermined time has passed since the printing of ink droplet 901 in the next pass (second pass) is shown. In the case where a stop occurs, the degree of bleeding is low even after a predetermined time has passed. This is probably because the stop increases the viscosity of ink droplet 900 in the first pass.

[0170] There will be no stopping situation ( Figure 8C ) and the case of stopping ( Fig. 9C ), there are differences in the degree of bleeding of ink droplets, which will be visually perceived as differences in color or gloss and cause unevenness. This phenomenon tends to occur particularly when the printing operation is stopped in a state where ink droplets are printed in an isolated manner or in a state where ink droplets are in contact with each other but the size of the ink droplets is relatively small. In the area that is in the middle of printing during the stop, stop unevenness tends to appear at the portion with the printing rate where this state occurs. In general, although there may be some differences in modes with different numbers of passes, stop unevenness also tends to appear at an area with a specific printing rate in the area that is in the middle of printing during the stop. In the 6-pass printing mode of the present embodiment, the area that is in the middle of printing during the stop is an area that has passed the first pass of printing during the stop.

[0171] In addition, when the stop time is short, the ink droplets are only slightly dried, so that the unevenness is relatively slight. In the case of a long stop time, the ink droplets are excessively dried, so that the degree of unevenness is high.

[0172] (8-3) Print control for stopping

[0173] As described above, the longer the stop time, the more likely unevenness will occur. Thus, during multiple types of stops, a stop may occur in which the stop time is longer than the predetermined time. In this case, it is preferred to perform the printing control for stopping in the present embodiment. For example, when the stop time is 10 seconds or longer, the printing control for stopping in the present embodiment is performed. Note that the stop time based on which the printing control in the present embodiment is applied is not limited to 10 seconds or longer, and can be a shorter or longer stop time. In addition, the stop time based on which the printing control for stopping in the present embodiment is applied can be determined in consideration of conditions. Examples of conditions include factors that affect the drying of ink such as ambient temperature and humidity, the type of printing medium (hygroscopicity, etc.), the ejection conditions of the head (changes in the amount of ink droplets and the ejection speed), and the ratio of the print data of the image to be printed, etc.

[0174] (8-4) Mask pattern

[0175] Next, the mask pattern used in the print control for stopping in this embodiment will be described. Figure 6 The mask pattern 600 shown (hereinafter referred to as "normal mask 600") is used for normal printing scans except for the printing scans before and after the stop. Note that in this embodiment, the mask pattern to be used in the normal printing scan is not limited to Figure 6 The normal mask 600 shown in FIG. 1 and may be any mask pattern. In addition, the total print rate is Figure 6 The ratio is 150%, but other printing ratios are possible.

[0176] (8-4-1) Stopping the front mask pattern

[0177] Fig. 10A 1 is a diagram showing an example of a pre-stop mask pattern 1000 to be used in a print scan (i-th print scan) immediately before the stop. The pre-stop mask pattern 1000 includes a mask pattern 1001 in which print-permitted pixels are not set for the ejection port group A1 used for printing of the print area of ​​interest in the first pass. That is, printing is not set for a print area that has not been printed yet (a print area that has been printed less than once) (print rate = 0%).

[0178] The mask patterns 1002 to 1006 of the ejection orifice groups A2 to A6 used for printing the print area of ​​interest in the second to sixth passes are respectively similar to the mask patterns 602 to 606 used for the ejection orifice groups A2 to A6 in the normal mask 600. That is, in the case where the print area of ​​interest has been printed once or more than once, the print area will be printed to achieve the same printing rate as in the mask pattern 600 used in the normal printing scan.

[0179] Note that in mask pattern 1000, the printing rate of mask pattern 1001 to be used for nozzle group A1 is 0%; the printing rate of mask pattern 1002 to be used for nozzle group A2 is approximately 25%; the printing rate of mask pattern 1003 to be used for nozzle group A3 is approximately 30%; the printing rate of mask pattern 1004 to be used for nozzle group A4 is approximately 30%; the printing rate of mask pattern 1005 to be used for nozzle group A5 is approximately 25%; and the printing rate of mask pattern 1006 to be used for nozzle group A6 is approximately 20%.

[0180] (8-4-2) Restart the rear mask pattern

[0181] After the stop time has passed, the printing operation is restarted. The print scan after the restart (the (i+1)th print scan) is performed on the same print area as in the print scan before the stop (the i-th print scan).

[0182] Fig. 10B 1 is a diagram showing an example of a post-restart mask pattern 1010 to be used in a print scan after the restart (the (i+1)th print scan). In the post-restart mask pattern 1010, printing is not set for the ejection port groups A2 to A6 for which print enable pixels were set in the pre-stop mask pattern 1000 (print rate = 0%), and print enable pixels are set only for the ejection port group A1 that was set not to print before the stop. The mask pattern 1011 of the ejection port group A1 is the same as the mask pattern 601 of the first pass (the ejection port group A1) in the normal mask 600. That is, the print area that was not printed in the print scan before the stop will be printed after the restart to supplement the no-printing that occurred immediately before the restart.

[0183] Note that, in the post-resumption mask pattern 1010 , the printing rate of the mask pattern 1001 of the ejection orifice group A1 is approximately 20%, and the printing rates of the mask patterns 1002 to 1006 of the ejection orifice groups A2 to A6 are 0%.

[0184] That is, the two print scans before and after the stop (the i-th print scan and the (i+1)-th print scan) achieve the same print rate as the normal print scan for the nozzle groups A1 to A6. The total print rate of the mask pattern 1001 and the mask pattern 1011 for the nozzle group A1 is about 20%; the total print rate of the mask pattern 1002 and the mask pattern 1012 for the nozzle group A2 is about 25%; the total print rate of the mask pattern 1003 and the mask pattern 1013 for the nozzle group A3 is about 30%; the total print rate of the mask pattern 1004 and the mask pattern 1014 for the nozzle group A4 is about 30%; the total print rate of the mask pattern 1005 and the mask pattern 1015 for the nozzle group A5 is about 25%; and the total print rate of the mask pattern 1006 and the mask pattern 1016 for the nozzle group A6 is about 20%. Therefore, the print rate in the two print scans before and after the stop is the same as that in the normal print scan. Figure 6 The printing rate of the normal mask 600 shown is consistent.

[0185] (8-5) Printing control using mask patterns

[0186] Reference Fig.11 Printing control using a pre-stop mask pattern 1000 and a post-resume mask pattern 1010 is described. Fig.11 The relationship between the number of print scans from the start of the print operation and the mask pattern to be applied, whether the print medium is to be conveyed after the print scan, and the scan direction is shown. In this embodiment, the print scan immediately before the stop is the i-th print scan.

[0187] In the first print scan to the (i-1)th print scan, use Figure 6 The normal mask 600 shown is used, and the print medium is conveyed after each print scan. In addition, the bidirectional printing in which the first print scan is in the forward direction and the next print scan is in the backward direction as the opposite direction is repeated.

[0188] A stop occurs between the i-th print scan and the (i+1)-th print scan. The i-th print scan is the print scan immediately before the stop, and the (i+1)-th print scan is the first print scan after the stop time has passed and then restarts.

[0189] In the i-th print scan, use Fig. 10A The pre-stop mask pattern 1000 is shown. Therefore, the ejection port group A1 is set not to print, so that an image will not be printed on the area facing the ejection port group A1 on the print medium P during scanning. The ejection port groups A2 to A6 will print images according to the pre-stop mask pattern 1000. In addition, control is performed so as not to convey the print medium after the i-th print scan.

[0190] In the (i+1)th print scan, use Fig. 10B The post-restart mask pattern 1010 is shown. Therefore, the orifice groups A2 to A6 are set not to print, so that no image will be printed on the area facing the orifice groups A2 to A6 on the print medium P during scanning. On the other hand, the orifice group A1 set not to print in the i-th print scan prints an image according to the post-restart mask pattern 1010. Furthermore, after the (i+1)-th print scan, the print medium is conveyed.

[0191] In addition, in this embodiment, the i-th printing scan and the (i+1)-th printing scan are in the same printing scan direction. Fig.11 As shown in the table, the i-th print scan immediately before the stop and the (i+1)-th print scan immediately after the restart are, for example, forward scans. This is to prevent complication of control of additional print scans for switching the forward-backward arrangement in the print data. Therefore, after the i-th print scan is completed, the main control unit 400 of the printing device 100 returns the carriage unit 102 to the opposite position in the X direction (main scanning direction) before, after, or during the stop. Then, the main control unit 400 performs the added (i+1)-th print scan in the same scanning direction as the i-th print scan.

[0192] In subsequent print scans ((i+2)th print scan, (i+3)th print scan, ... print scan), the normal mask 600 is used, and the print medium is conveyed after each print scan. The scanning direction is alternately switched between the backward direction and the forward direction.

[0193] Fig.12 4 is a flowchart showing the flow of print control performed in the present embodiment. The CPU 401 calls a program stored in the ROM 402 or the memory 405 of the main control unit 400 of the printing device 100, loads the program into the RAM 403, and executes the program to realize the processing shown in the flowchart. The CPU 401 starts the processing in response to receiving a print job from the host device 414. Each symbol "S" in the following description represents a step.

[0194] In S1201, the CPU 401 determines whether there is a stop request. If there is no stop request (No in S1201), the CPU 401 proceeds to S1202. If there is a stop request (Yes in S1201), the CPU 401 proceeds to S1205.

[0195] In S1202, the CPU 401 performs a normal print scan. In the normal print scan, the CPU 401 generates print data for a single scan by using the normal mask 600, and outputs it to the drive circuit 408. Under the control of the CPU 401, when the carriage unit 102 performs a single scan, the drive circuit 408 drives the print head 109 to perform printing on the print area facing the print head 109 on the print medium P. The print head 109 is controlled by the drive circuit 408 to eject ink from a plurality of ink ejection outlets to perform printing for a single scan in synchronization with the carriage operation.

[0196] In S1203, the CPU 401 conveys the print medium P. In the conveying operation, the CPU 401 controls the drive circuit 406 to drive the conveying motor (LF motor) 410 to convey the print medium P by a predetermined movement amount in the Y direction. The movement amount is 1 / n of the length of the ejection port array in the print head 109 in its array direction, where n is the number of passes in multi-pass printing.

[0197] In S1204, CPU 401 determines whether the printing of a single page is completed. If there is subsequent print data, CPU 401 determines that printing is not completed ("No" in S1204), and returns to S1201. If there is no subsequent print data, CPU 401 determines that printing is completed ("Yes" in S1204), and terminates the flowchart.

[0198] In S1205, the CPU 401 switches to stop the pre-mask pattern 1000, and generates print data for the i-th print scan.

[0199] In S1206, the CPU 401 performs the i-th print scan. In the i-th print scan, using the mask pattern 1001, printing is not set for the ejection port group A1 facing the print area that has not been printed in the print area facing the ejection port array. That is, no print permission pixel is set. Therefore, an image will not be printed on the print area that has not been printed. Mask patterns 1002 to 1006 are applied to the ejection port groups A2 to A6, respectively. The mask patterns 1002 to 1006 have printing rates corresponding to the mask patterns 602 to 606 to be used for the ejection port groups A2 to A6 in the normal mask 600, respectively. Therefore, printing similar to the normal print scan will be performed. The CPU 401 controls so that the print medium P is not conveyed after the i-th print scan.

[0200] In S1207, the CPU 401 stops the printing operation until a predetermined stop time has elapsed. Incidentally, in the case where an operation other than the printing operation is performed during the stop time, the CPU 401 executes the operation.

[0201] In S1208, the CPU 401 switches to the restarting rear mask pattern 1010 and generates print data for the (i+1)th print scan. The switching to the restarting rear mask pattern 1010 and the generation of print data in S1208 can be completed before the predetermined stop time passes, and the print data can be stored in the buffer (memory 405).

[0202] In S1209, the CPU 401 performs the (i+1)th print scan according to the print data generated in S1208. In the (i+1)th print scan, the ejection port group A1 facing the print area that was not printed in the i-th print scan (the print scan before stopping) is printed using the mask pattern 1011. The mask pattern 1011 has the same printing rate as the mask pattern 601 to be used for the ejection port group A1 in the normal mask 600. Thus, printing similar to the normal print scan will be performed. In addition, in the (i+1)th print scan, the ejection port groups A2 to A6 facing the print areas of the second to sixth passes in the print area facing the ejection port array are set not to print using the mask patterns 1012 to 1016.

[0203] In S1210, the CPU 401 conveys the print medium P by a predetermined movement amount in the Y direction. Thereafter, the CPU 401 proceeds to S1204 and determines whether the printing of a single page is completed. If there is no subsequent print data, the CPU 401 determines that the printing is completed and terminates the flowchart.

[0204] Fig.13 The position of the nozzle array 31 in the print scan before and after the stop and the change of the formed image are shown. Note that the position of the nozzle array 31 indicates the position relative to the print area. Fig.13 , image 1300 represents a stacked image formed by the print scan performed until just before the stop (i-th print scan). The print scans until the (i-1)th print scan are performed using the normal mask 600, and the mask pattern 1000 before the stop is used in the i-th print scan. Thus, in the i-th print scan, the area 1301 facing the ejection port group A1 is not printed (printed zero times). By the print scans until the i-th print scan, the area 1302 is printed twice, the area 1303 is printed three times, the area 1304 is printed four times, the area 1305 is printed five times, and the area 1306 is printed six times.

[0205] In the (i+1)th printing scan which is the first printing scan after the restart, the post-restart mask pattern 1010 is used. Thus, in the (i+1)th printing scan, the areas 1302 to 1306 facing the ejection port groups A2 to A6 are not printed, and the ejection port group A1 is subjected to the first pass printing. That is, the area 1301 which was not printed in the printing scan before the stop (the i-th printing scan) is first printed, and the other areas 1302 to 1306 are not printed.

[0206] The second print scan and subsequent print scans (the (i+2)th print scan and subsequent print scans) after the restart are performed using the normal mask 600 . Fig.13 The image 1320 in 1300 represents a stacked image formed by the (i+2)th to (i+7)th printing scans. The total number of times each of the printing areas 1301 to 1306 is printed in the images 1300, 1310, and 1320 is six, indicating that multi-pass printing has been completed.

[0207] As described above, the printing device 100 in the present embodiment makes it possible to scan the unprinted printing area without printing in the printing scan immediately before the stop, and print the unprinted printing area before the stop in the printing scan after the restart, so as to achieve the printing rate of the normal printing scan. Thus, the first pass printing that will end with obvious unevenness due to the stop is performed after the restart, and thereafter the printing operation returns to the normal printing scan. This makes the drying state of the ink droplets close to the state in the normal printing scan, thereby preventing or reducing the density unevenness due to the stop.

[0208] Furthermore, in the print scan before stopping, the area other than the print area which has not been printed yet is printed using the same mask pattern as that applied in the normal print scan, and is not printed after restarting. Therefore, like other print areas, the print area is printed at a print rate similar to that in the normal print scan, and therefore the print area is printed without a change in image quality.

[0209] The throughput by the print control in the present embodiment will be described by comparison with the conventional technology.

[0210] Fig.14 With Fig.13A similar manner illustrates the known print control disclosed in Japanese Patent Laid-Open No. 2000-15868. In this known print control method, multiple passes of printing are completed before a stop occurs. Thus, before the stop, the i-th, (i-1)-th, (i-2)-th, (i-3)-th, and (i-4)-th print scans are required as additional print scans. For example, in the case of 6-pass printing as in the present embodiment, five additional print scans are required. Typically, for n-pass printing, (n-1) additional print scans are required.

[0211] In contrast, in the print control of this embodiment, if Fig.13 As shown, the next print scan after the restart (the (i+1)th print scan) is the only additional print scan. Therefore, the image is completed with fewer scans than in the conventional technology. This prevents a reduction in throughput. This effect will be particularly good when the number of passes is large. A very large effect can be achieved by using multi-pass printing involving tens to hundreds of passes, which can be adopted in a multi-layer printing system that typically uses white ink.

[0212] Note that in this embodiment, an example of printing on a non-absorbent medium as a print medium is presented. Alternatively, the print control in this embodiment may be applied to a general absorbent print medium such as plain paper. An absorbent print medium such as plain paper may also experience an uneven appearance with a similar tendency to that of a non-absorbent print medium. In this case, performing the print control in this embodiment will bring about a similar effect.

[0213] <Second Embodiment>

[0214] Next, a second embodiment of the present disclosure will be described. The printing control in the second embodiment is similar to the printing control in the first embodiment in that areas that will not be printed are set before and after the stop, but the ranges of these areas are different. Note that the configuration of the printing device 100 in the second embodiment is similar to that in the first embodiment, so repeated description is omitted.

[0215] In the first embodiment, an example of preventing or reducing the occurrence of noticeable unevenness in an area printed once before stopping in 6-pass printing is presented exemplarily. Here, in the case where an image is completed with a larger number of passes or due to differences in the physical properties of ink or other conditions, in addition to the area printed once, unevenness may also similarly occur in the areas printed twice and three times. Examples of conditions include the ratio of print data of the image to be printed, factors affecting the drying of ink such as ambient temperature and humidity, the type of print medium, and the ejection conditions of the head (changes in the amount of ink droplets and the ejection speed), etc. In this case, it may be preferable not to print these areas in the multiple print scans before stopping, and to print these areas after restarting.

[0216] In the second embodiment, the area that will not be printed before stopping is made wider than in the first embodiment. In the specific example, a mask pattern that does not print an area having a width corresponding to three of the six divided ejection orifice groups A1 to A6 is used. Then, after the restart, a mask pattern that prints is used only for the area that was not printed before stopping.

[0217] Fig.15A , Fig. 15B and Fig. 15C Mask patterns 1501, 1502, and 1503 to be used in three printing scans before stopping are respectively shown. Fig.15A The illustrated pre-stop mask pattern 1501 is a mask pattern to be used in the third print scan ((i-2)th print scan) before stop, and is a mask pattern for setting non-printing for the ejection port group A1. Fig. 15B The illustrated pre-stop mask pattern 1502 is a mask pattern to be used in the second print scan (i-1th print scan) before the stop, and is a mask pattern for setting non-printing for the ejection port groups A1 and A2. Fig. 15C The mask pattern 1503 before stopping shown is a mask pattern to be used in the printing scan (i-th printing scan) immediately before stopping, and is a mask pattern for setting non-printing for the nozzle groups A1, A2, and A3. Among these mask patterns 1501, 1502, and 1503, the mask patterns other than the mask patterns for the nozzle groups set not to print are the same as Figure 6 The mask pattern in the normal mask 600 is shown to be similar.

[0218] Fig.15D , Fig.15E and Fig.15F Mask patterns 1504, 1505, and 1506 to be used in three printing scans after the restart are respectively shown. Fig.15D The post-restart mask pattern 1504 shown is a mask pattern to be used in the first print scan (the (i+1)th print scan) after the restart. Figure 6 The same print permission pixels as the print permission pixels of the ejection orifice group A1 in the normal mask 600 are allocated to the ejection orifice group A3. The other ejection orifice groups A1, A2, A4, A5, and A6 are set not to perform printing. Fig.15E The illustrated post-restart mask pattern 1505 is a mask pattern to be used in the second print scan after the restart (the (i+2)th print scan), in which the same print enable pixels as those of the ejection orifice groups A1 and A2 in the normal mask 600 are respectively allocated to the ejection orifice groups A2 and A3. The other ejection orifice groups A1, A4, A5, and A6 are set not to perform printing. Fig.15F The illustrated post-restart mask pattern 1506 is a mask pattern to be used in the third print scan after the restart (the (i+3)th print scan), in which the same print enable pixels as those of the ejection opening groups A1 to A3 for the first to third passes in the normal mask 600 are respectively allocated to the ejection opening groups A1 to A3. The other ejection opening groups A4 to A6 are set not to perform printing.

[0219] Notice, FIG. 15A to FIG. 15F The mask pattern shown is an example, and the present embodiment is not limited to this example. For the print scan after restarting, the same mask pattern as the mask pattern in the normal mask does not necessarily have to be used for the area that was not printed in the print scan before stopping, as long as the print rate is supplemented to the print rate in the normal print scan. However, it is not expected to generate a difference in image quality between the print area before and after stopping and the print area printed in the normal print scan.

[0220] In this regard, the post-restart mask patterns 1504 to 1506 in the present disclosure achieve the required printing rate for each of the three print scans after the restart, that is, the same printing rate as the printing rate achieved by using the mask patterns 601 to 603 for the first to third passes in the normal mask 600. In addition, the mask pattern causes the printing rate of the area that was not printed in the print scan before the stop to change in a similar order to the normal print scan. Specifically, for the print area that was not printed before the stop, like the normal mask, a mask pattern with a small printing rate is used in the first pass, and gradually changes to a mask pattern with a larger printing rate. In this way, ink droplets land on the print area before and after the stop one by one in a similar order to other print areas. This makes it possible to maintain a color and gloss similar to other print areas.

[0221] Now refer to Fig.16 Printing control using mask patterns 1501 to 1506 is described. Fig.16 The relationship between the number of print scans from the start of the print operation and the mask pattern to be applied, whether the print medium is to be conveyed after the print scan, and the print scan direction is shown. In the second embodiment, the print scan immediately before the stop is the i-th print scan.

[0222] In the first print scan to the (i-3)th print scan, the normal mask 600 is used, and the print medium is conveyed after each print scan. In addition, bidirectional printing is repeated in which the first print scan is in the forward direction and the next print scan is in the backward direction as the opposite direction.

[0223] The (i-2)th print scan, which is the third print scan before stopping, is assigned the pre-stop mask pattern 1501 and is performed as a forward scan in the opposite direction to the (i-3)th print scan. The print medium is conveyed after the print scan.

[0224] The (i-1)th print scan, which is the second print scan before stopping, is assigned the pre-stop mask pattern 1502 and is performed as a backward scan in the opposite direction to the (i-2)th print scan. The print medium is conveyed after the print scan.

[0225] The i-th print scan, which is the print scan immediately before the stop, is assigned the pre-stop mask pattern 1503 and is performed as a forward scan in the opposite direction to the (i-1)-th print scan. This configuration causes the print medium not to be conveyed after the i-th print scan.

[0226] A stop occurs between the i-th print scan and the (i+1)-th print scan. Incidentally, during this stop or before the first print scan (the (i+1)-th print scan) after the restart, the carriage unit 102 returns to the reverse position in the X direction. This is to prevent complication of control for switching the additional print scan for the forward-backward arrangement in the print data, as in the first embodiment.

[0227] The (i+1)th print scan, which is the first print scan after the restart, is assigned the post-restart mask pattern 1504. As for the print scan direction, forward scanning is performed in the same direction as the i-th print scan. This configuration makes it possible not to convey the print medium after the (i+1)th print scan.

[0228] The (i+2)th print scan, which is the second print scan after the restart, is assigned the post-restart mask pattern 1505. As for the scanning direction, the backward scan is performed in the opposite direction to the (i+1)th print scan. This configuration makes it possible not to convey the print medium after the (i+2)th print scan.

[0229] The (i+3)th print scan, which is the third print scan after the restart, is assigned the post-restart mask pattern 1506. As for the scanning direction, forward scanning is performed in the opposite direction to the (i+2)th print scan. The print medium is conveyed after the (i+3)th print scan.

[0230] In subsequent print scans ((i+4)th print scan, (i+5)th print scan, ... print scan), the normal mask 600 is used, and the print medium is conveyed after each print scan. The scanning direction is alternately switched between the backward direction and the forward direction.

[0231] Fig.17 is a flowchart showing the flow of print control performed in the second embodiment.

[0232] In S1701, the CPU 401 determines whether there is a stop request. If there is no stop request (No in S1701), the CPU 401 proceeds to S1702. If there is a stop request (Yes in S1702), the CPU 401 proceeds to S1705.

[0233] Here, S1702 and S1703 are normal printing operations and are the same as those in the first embodiment ( Fig.12 ) is similar to S1202 and S1203, and therefore its description is omitted.

[0234] In S1704, CPU 401 determines whether the printing of a single page is completed. If there is subsequent print data, CPU 401 determines that printing is not completed ("No" in S1704), and returns to S1701. If there is no subsequent print data, CPU 401 determines that printing is completed ("Yes" in S1704), and terminates the flowchart.

[0235] In S1705, the CPU 401 switches to stop the pre-mask pattern 1501, and generates print data for the (i-2)th print scan.

[0236] In S1706, the CPU 401 performs the (i-2)th print scan. In the (i-2)th print scan, the mask is used to set no printing for the nozzle group A1 facing the print area that has not been printed in the print area facing the nozzle array. That is, no print permission pixel is set. Therefore, no image will be printed on the print area that has not been printed. For the nozzle groups A2 to A6, the mask is used to set no printing permission pixel. Figure 6 The mask patterns 602 to 606 for the ejection orifice groups A2 to A6 in the illustrated normal mask 600 are compared with mask patterns having similar printing rates. Thus, the area facing the ejection orifice groups A2 to A6 is printed similarly to a normal printing scan.

[0237] In S1707, the CPU 401 conveys the print medium.

[0238] In S1708, the CPU 401 switches to the pre-stop mask pattern 1502. The CPU 401 generates print data for the (i-1)th print scan by using the pre-stop mask pattern 1502.

[0239] In S1709, the CPU 401 performs the (i-1)th print scan. In the (i-1)th print scan, the mask pattern 1502 is used to set no printing for the nozzle groups A1 and A2 facing the print area that has not been printed in the print area facing the nozzle array. Therefore, no image will be printed on the print area that has not been printed. For the nozzle groups A3 to A6, the same mask pattern is used. Figure 6 The mask patterns 603 to 606 for the ejection orifice groups A3 to A6 in the illustrated normal mask 600 are compared with mask patterns having similar printing rates. Thus, the area facing the ejection orifice groups A3 to A6 is printed similarly to a normal printing scan.

[0240] In S1710, the CPU 401 conveys the print medium.

[0241] In S1711, the CPU 401 switches to the pre-stop mask pattern 1503. The CPU 401 generates print data for the i-th print scan by using the pre-stop mask pattern 1503.

[0242] In S1712, the CPU 401 performs the i-th print scan. In the i-th print scan, the mask pattern 1503 is used to set no printing for the nozzle groups A1, A2, and A3 facing the print area that has not been printed in the print area facing the nozzle array. Therefore, no image will be printed on the print area that has not been printed. For the nozzle groups A4 to A6, the mask pattern 1503 is used to set no printing. Figure 6 The mask patterns 604 to 606 of the ejection port groups A4 to A6 in the normal mask 600 shown are compared with mask patterns having similar printing rates. Thus, the area facing the ejection port groups A4 to A6 is printed similarly to the normal printing scan. Note that the CPU 401 controls so that the printing medium P is not conveyed after the i-th printing scan.

[0243] In S1713, the CPU 401 stops the printing operation until a predetermined stop time has elapsed. In the case where an operation other than the printing operation is performed during the stop time, the CPU 401 executes the operation.

[0244] In S1714, the CPU 401 switches to the restarting rear mask pattern 1504 and generates print data for the (i+1)th print scan. The switching to the restarting rear mask pattern 1504 and the generation of print data in S1714 can be completed before the predetermined stop time passes, and the print data can be stored in the buffer (memory 405).

[0245] In S1715, the CPU 401 performs the (i+1)th print scan according to the print data generated in S1714. In the (i+1)th print scan, print permission pixels are set in the nozzle group A3 among the nozzle groups A1 to A3 facing the print area that was not printed in the i-th print scan (the print scan before stopping). The mask pattern for the nozzle group A3 has a printing rate corresponding to the mask pattern 601 for the nozzle group A1 in the normal mask 600. Thus, printing similar to the first pass in the normal print scan is performed on the print area facing the nozzle group A3. In addition, the nozzle groups other than the nozzle group A3 (i.e., the nozzle groups A1, A2, A4, A5, and A6) are set not to print. Note that after the (i+1)th print scan, the print medium P is not conveyed.

[0246] In S1716, the CPU 401 switches to the restart post-mask pattern 1505, and generates print data for the (i+2)th print scan.

[0247] In S1717, the CPU 401 performs the (i+2)th print scan according to the print data generated in S1716. In the (i+2)th print scan, print permission pixels are set in the ejection port groups A2 and A3 of the ejection port groups A1 to A3 facing the print area that was not printed in the i-th print scan (the print scan before stopping). The mask pattern for the ejection port group A3 has a print rate corresponding to the mask pattern 602 for the ejection port group A2 in the normal mask 600. The mask pattern for the ejection port group A2 has a print rate corresponding to the mask pattern 601 for the ejection port group A1 in the normal mask 600.

[0248] Thus, the printing area facing the ejection port group A3 is printed similarly to the second pass in the normal printing scan, and the printing area facing the ejection port group A2 is printed similarly to the first pass in the normal printing scan. In addition, the ejection port groups other than the ejection port groups A2 and A3 (i.e., the ejection port groups A1, A4, A5, and A6) are set not to print. Note that after the (i+2)th printing scan, the printing medium P is not conveyed.

[0249] In S1718, the CPU 401 switches to the restart post-mask pattern 1506, and generates print data for the (i+3)th print scan.

[0250] In S1719, the CPU 401 performs the (i+3)th print scan according to the print data generated in S1718. In the (i+3)th print scan, print permission pixels are set in the ejection port groups A1 to A3 facing the print area that was not printed in the i-th print scan (the print scan before stopping). The mask pattern for the ejection port group A3 has a print rate corresponding to the mask pattern 603 for the ejection port group A3 in the normal mask 600. The mask pattern for the ejection port group A2 has a print rate corresponding to the mask pattern 602 for the ejection port group A2 in the normal mask 600. The mask pattern for the ejection port group A1 has a print rate corresponding to the mask pattern 601 for the ejection port group A1 in the normal mask 600.

[0251] Thus, the printing area facing the nozzle group A3 performs printing similar to the third pass in the normal printing scan. In addition, the printing area facing the nozzle group A2 performs printing similar to the second pass in the normal printing scan. In addition, the printing area facing the nozzle group A1 performs printing similar to the first pass in the normal printing scan. In addition, the nozzle groups other than the nozzle groups A1, A2, and A3 (i.e., the nozzle groups A4, A5, and A6) are set not to perform printing.

[0252] In S1720, the CPU 401 conveys the print medium. Then, the CPU 401 proceeds to S1704.

[0253] In S1704, as described above, the CPU 401 determines whether printing is completed. If there is subsequent print data, the CPU 401 determines that printing is not completed ("No" in S1704), and returns to S1701. If there is no subsequent print data, the CPU 401 determines that printing is completed ("Yes" in S1704), and terminates the flowchart.

[0254] Fig.18 The change of the position of the ejection port array 31 and the formed image in the print scan before and after the stop in the print control of the second embodiment is shown. Note that the position of the ejection port array 31 indicates the position relative to the print area.

[0255] exist Fig.18, image 1800 represents a stacked image formed by the print scans performed until just before the stop (i-th print scan). Using the normal mask 600, the print scans until the (i-3)th print scan are performed, and the pre-stop mask patterns 1501, 1502, and 1503 are used in three ((i-2)th, (i-1)th, and i-th) print scans, respectively. In addition, before each print scan, the print medium is conveyed. Therefore, in the print scans until the i-th print scan, the areas 1801, 1802, and 1803 facing the ejection port groups A1 to A3 are not printed.

[0256] Specifically, in the (i-3)th printing scan (printing scan using the normal mask 600), the ejection port array 31 faces areas 1804 to 1809. Area 1804 is printed for the first time, area 1805 is printed for the second time, area 1806 is printed for the third time, area 1807 is printed for the fourth time, area 1808 is printed for the fifth time, and area 1809 is printed for the sixth time.

[0257] In the (i-2)th printing scan (printing scan using the pre-stop mask pattern 1501), the ejection port array 31 faces the areas 1803 to 1808. In addition, the area 1803 is not printed, the area 1804 is printed for the second time, the area 1805 is printed for the third time, the area 1806 is printed for the fourth time, the area 1807 is printed for the fifth time, and the area 1808 is printed for the sixth time.

[0258] In the (i-1)th printing scan (printing scan using the pre-stop mask pattern 1502), the ejection port array 31 faces the areas 1802 to 1807. In addition, the areas 1802 and 1803 are not printed, the area 1804 is printed for the third time, the area 1805 is printed for the fourth time, the area 1806 is printed for the fifth time, and the area 1807 is printed for the sixth time.

[0259] In the i-th printing scan (printing scan using the pre-stop mask pattern 1503), the ejection port array 31 faces the areas 1801 to 1806. In addition, the areas 1801, 1802, and 1803 are not printed, the area 1804 is printed for the fourth time, the area 1805 is printed for the fifth time, and the area 1806 is printed for the sixth time.

[0260] Three print scans are added after the restart to print the area that was not printed before the stop.

[0261] Fig.18The image 1810 in represents an image formed in the first print scan after the restart (the (i+1)th print scan). In the (i+1)th print scan, as in the last print scan before the stop (the i-th print scan), the ejection port array 31 faces the areas 1801 to 1806. In addition, in the (i+1)th print scan, the post-restart mask pattern 1504 is used so that the areas 1801, 1802, 1804, 1805, and 1806 facing the ejection port groups A1, A2, A4, A5, and A6 are not printed. The area 1803 is printed for the first time.

[0262] also, Fig.18 The image 1820 in represents an image formed in the second print scan after the restart (the (i+2)th print scan). In the (i+2)th print scan, as in the last print scan before the stop (the i-th print scan), the ejection port array 31 faces the areas 1801 to 1806. In addition, in the (i+2)th print scan, the post-restart mask pattern 1505 is used so that the areas 1801, 1804, 1805, and 1806 facing the ejection port groups A1, A4, A5, and A6 are not printed. The area 1802 is printed for the first time, and the area 1803 is printed for the second time.

[0263] Fig.18 The image 1830 in represents an image formed in the third print scan after the restart (the (i+3)th print scan). In the (i+3)th print scan, as in the last print scan before the stop (the i-th print scan), the ejection port array 31 faces the areas 1801 to 1806. In addition, in the (i+3)th print scan, the post-restart mask pattern 1506 is used so that the areas 1804, 1805, and 1806 facing the ejection port groups A4, A5, and A6 are not printed. The area 1801 is printed for the first time, the area 1802 is printed for the second time, and the area 1803 is printed for the third time.

[0264] In other words, in the three print scans added after the restart (the (i+1)th print scan to the (i+3)th print scan), the areas 1801 to 1803 that were not printed in the three print scans before the stop (the (i-2)th print scan to the i-th print scan) are printed in sequence, and the other areas 1804 to 1806 are not printed. In addition, the printing medium is not conveyed before the three print scans after the restart. Therefore, each of the print areas 1801 to 1803 that were not printed before the stop is printed appropriately. In addition, in the print scan after the restart, the print area that was not printed in the print scan before the stop is printed in the same order as the first to third passes in the normal print scan and at the same printing rate. In this way, ink droplets land on the print areas before and after the stop one after another in a similar order to that on other print areas. This prevents or reduces changes in color or gloss.

[0265] Using the normal mask 600, the fourth print scan and subsequent print scans (the (i+2)th print scan and subsequent print scans) after the restart are performed. Fig.18 The image 1840 in represents a stacked image formed by the (i+4)th print scan to the (i+9)th print scan. The total number of times each of the print areas 1801 to 1806 is printed in the images 1800, 1810, 1820, 1830, and 1840 is six, indicating that multi-pass printing has been completed.

[0266] As described above, in the second embodiment, in the three print scans before stopping, the print area that has not been printed is scanned without printing, and in the three print scans after restarting, the print area that has not been printed before stopping is printed to achieve the printing rate of the normal print scan. This prevents the occurrence of unevenness over a wider area than in the first embodiment.

[0267] On the other hand, compared with the first embodiment, the number of additional print scans is increased from one to three. Therefore, the effect of reducing the decrease in throughput is not great. However, in the case of the conventional technology (Japanese Patent Laid-Open No. 2000-15868), five additional print scans are required for 6-pass printing. Thus, compared with the conventional technology, a high throughput can be maintained.

[0268] Next, the effect of the present embodiment in the case where the number of passes is large will be described. As the number of passes in multi-pass printing increases, the number of ink droplets to be printed for each print scan tends to decrease. This is considered to increase the area on the way to printing where ink droplets will be printed in an isolated manner. For example, in 6-pass printing, many ink droplets are printed in an isolated manner in the first pass. Now, consider 18-pass printing. The number of passes is three times the number of passes in 6-pass printing. Thus, in terms of the ratio of ink droplets, the first to third passes print the same number of ink droplets as the first pass in 6-pass printing. That is, in 18-pass printing, the same number of ink droplets as the first pass in 6-pass printing are considered to be printed in an isolated manner through the first to third passes.

[0269] As described above, in the case where a stop occurs, unevenness tends to occur in an area where ink droplets are printed in an isolated manner. Thus, in 18-pass printing, unevenness is considered to be more likely to occur in an area printed by the first to third passes before the stop. In the case of printing with a larger number of passes as described above, as in the second embodiment, it is considered to be more effective to perform print control involving setting a nozzle group that will not print in a plurality of print scans before the stop, and adding a print scan that will supplement the print scan without printing after the restart.

[0270] In summary, in the multiple print scans before stopping, the pre-stop mask pattern having the ejection port group that does not perform printing can be used. In addition, the number of print scans can be determined according to the ratio to the number of passes in the multi-pass printing. In addition, after the restart, the area that was not printed before the stop is printed with the same number of print scans as the print scan using the pre-stop mask pattern to achieve a printing rate similar to that of a normal mask. In addition, after the restart, the area that was not printed before the stop is preferably printed to achieve a printing rate in a similar order to that of a normal mask.

[0271] Note that during normal printing, the efficiency of drying of ink droplets varies according to the number of passes, and therefore, how unevenness appears may be somewhat different. In this case, the number of print scans using the pre-stop mask pattern can be adjusted based on the ratio to the number of passes according to how unevenness actually appears.

[0272] <Modification>

[0273] In the above embodiment, some mask patterns are not printed, but within a certain range of achieving the effect of the present disclosure, some print-permitted pixels may also be included. Specifically, in at least one print scan before stopping, a print area that has not been printed or has been printed less than a predetermined number of times is printed at the first print rate B. In this case, in at least one print scan after restarting, the print area printed at the first print rate B is printed at the second print rate C that supplements the first print rate B to achieve the print rate A in the normal print scan. Note that the second print rate C is greater than the first print rate B.

[0274] Specifically, in the print scans before and after the stop, for the print area that has not been printed or has been printed less than a predetermined number of times, a pre-stop mask pattern and a post-resume mask pattern whose print ratio satisfies the relationship in the following equation and inequality (1) are used.

[0275] A = B + C, and B < C … (1)

[0276] Note that the printing rate B is smaller than a predetermined printing rate, and preferably smaller than 1%.

[0277] <Third Embodiment>

[0278] Next, a third embodiment of the present disclosure will be described. In the third embodiment, a configuration that is partially different from the first embodiment in terms of a method of conveying a print medium but is capable of achieving a similar effect will be presented. The print control in the third embodiment is similar to that in the first embodiment in that an area not to be printed is set before and after the stop, but is different in the mask pattern at this time and the conveying direction of the print medium P. Note that the configuration of the printing device 100 in the third embodiment is similar to that in the first embodiment, and therefore repeated description is omitted.

[0279] In the third embodiment, Fig.19 The illustrated mask pattern is used as a pre-stop mask pattern 1900. The pre-stop mask pattern 1900 is the pre-stop mask pattern 1000 in the first embodiment, in which the patterns of the ejection orifice groups A2 to A6 are shifted by a single pass and are respectively assigned to the ejection orifice groups A1 to A5.

[0280] Next, we will use Fig. 20 The relationship between the print scans before and after the stop and the conveyance of the print medium in this embodiment is described. In the first embodiment, after the i-th print scan immediately before the stop, the print medium is not conveyed. In this embodiment, after the (i-1)-th print scan immediately before the i-th print scan, the print medium is not conveyed. Fig.21 A flowchart showing the printing operation in this embodiment is shown. Note that Fig.21 The flowchart in the first embodiment Fig.12Similar processes are denoted by the same reference numerals and will be described below. Fig.12 Flowcharts of different treatments.

[0281] In the third embodiment, if it is determined in S1201 that there is a stop request, the CPU 401 proceeds to S2101. In S2101, the CPU 401 performs the (i-1)th print scan. Then, the CPU 401 switches to the stop front mask pattern without conveying the print medium in S1205, and performs the i-th print scan in S1206. As a result, the previously described print operation is performed. After the i-th print scan in S1206, the CPU 401 conveys the print medium in S2102. Then, in S1207, the CPU 401 stops the print operation.

[0282] Will use Fig. 22 Printing with the configuration described above is briefly described. Fig. 22 1 and 2 show the positions of the ejection port array 31 in the print scan before and after the stop. Fig.13 As shown in FIG. 1 , the print medium P is conveyed after the (i-1)th print scan, so that the position of the nozzle array 31 is moved in the i-th print scan. On the other hand, in the third embodiment, the print medium P is not conveyed after the (i-1)th print scan, so that the i-th print scan occurs at the same position of the nozzle array 31 as the (i-1)th print scan. Here, since the pre-stop mask pattern is changed as described above, although the print medium P is not conveyed, the same printing as in the first embodiment is performed on the print medium P. Therefore, as shown in FIG. Fig. 22 As shown, the stacked image 2201 formed by the print scans up to the i-th print scan is the same as the stacked image 1300 formed by the print scans up to the i-th print scan in the first embodiment.

[0283] Furthermore, although the print medium P is not conveyed after the i-th scan in the first embodiment, the print medium P is conveyed after the i-th scan in the third embodiment. Therefore, in the (i+1)th print scan which is the first print scan after the restart and subsequent print scans, the mask pattern and the position of the ejection port array 31 are similar to those in the first embodiment. Fig. 22 As shown, in the (i+1)th print scan, Fig.13 An image 2202 similar to image 1310 in FIG. 1 is printed on the stacked image 2201 . Fig. 22 The image 2203 in FIG. 2 represents a stacked image formed by the (i+2)th print scan to the (i+7)th print scan, and is Fig.13 Similar to image 1320 in FIG.

[0284] Therefore, the mask pattern 1900 and the method of conveying the printing medium P presented in the third embodiment can be used to achieve the same effects as those of the first embodiment.

[0285] <Fourth Embodiment>

[0286] Next, a fourth embodiment of the present disclosure will be described. In the fourth embodiment, a configuration in which no additional scanning is required after the stop in the first embodiment will be presented. The printing control in the fourth embodiment is similar to the printing control in the first embodiment in that an area not to be printed is set before and after the stop operation, but is different in the mask pattern after the restart and the conveying direction of the printing medium P.

[0287] In the fourth embodiment, Fig.23 The mask pattern 2310 shown is used as a post-restart mask pattern. The pattern for the ejection port group A2 in the mask pattern 2310 is used for normal printing. Figure 6 The mask pattern 600 is a print pattern in which patterns 601 and 602 for orifice groups A1 and A2 are combined. By printing using the mask pattern 2310, the print area for orifice group A2 is printed at a print rate equivalent to the first and second passes combined in normal printing.

[0288] Next, we will use Fig.24 The relationship between the printing scan and the conveyance of the printing medium before and after the stop in this embodiment is described. Fig.11 As shown in FIG. 1 , the print medium is not conveyed after the i-th print scan immediately before the stop (“No”), but in the present embodiment, the print medium is conveyed after the print scan (“Yes”). In addition, the scanning direction of the print scan after the restart from the stop (the (i+1)-th print scan) is the forward direction in the first embodiment, but is the backward direction in the present embodiment. Therefore, normal print scans and normal print medium conveyance are performed before and after the stop. Fig.25 A flowchart showing the printing operation in this embodiment is shown. Note that Fig.25 The flowchart in the first embodiment Fig.12 Similar processes are denoted by the same reference numerals and will be described below. Fig.12 Flowcharts of different treatments.

[0289] In the fourth embodiment, if it is determined in S1201 that there is a stop request, the CPU 401 proceeds to S1205. In S1205, the CPU 401 switches to the mask pattern 2310 before stopping, and generates the print data of the i-th print scan. Then, the CPU 401 performs the i-th print scan in S1206, and conveys the print medium in S2501. Then, in S1207, the CPU 401 stops the printing operation. The processing in S1207 and the processing thereafter are similar to those in the first embodiment.

[0290] Will use Fig.26 Printing with the above configuration is briefly described. Fig.26 The position of the ejection port array 31 in the print scans before and after the stop is shown. The image 2601 represents a stacked image formed by the print scans performed until just before the stop (the i-th print scan), and is similar to the image 1300 printed by the print scans performed until just before the stop (the i-th print scan) in the first embodiment. In the first embodiment, as Fig.13 As shown, the print medium P is not conveyed after the i-th printing scan, so that the position of the ejection port array 31 in the (i+1)-th scan is the same as that in the i-th scan.

[0291] On the other hand, in the fourth embodiment, the print medium P is conveyed after the i-th print scan so that the position of the ejection port array 31 in the (i+1)-th print scan is different from that in the i-th print scan. Here, as described above, the mask pattern after restarting has been changed to Fig.23 The mask pattern 2310 shown. Thus, the print pattern at the position of the second pass in the mask pattern 2310 after restarting is a print pattern that combines the first pass pattern 601 and the second pass pattern 602 in the mask pattern 600 used for normal printing. Thus, although the print medium is conveyed after stopping, the print pattern of the first pass that was not printed in the i-th print scan can be supplemented. Therefore, printing is performed on the print medium while maintaining a print rate similar to that in the first embodiment, without having to perform an additional print scan after the stop operation required in the first embodiment. As a result, as shown in image 2603, the stacked image formed by the (i+1)th print scan and the subsequent print scans is the same as the stacked image 1320 in the first embodiment. Therefore, the same effect as the first embodiment is achieved.

[0292] Note that, in the above, the print pixels of the first pass that were not printed before stopping are added to the second pass of the print scan after the stop operation (after restarting), but the present disclosure is not limited to this configuration. For example, a mask pattern may be used in which the print pixels of the first pass that were not printed before stopping are added to the print pixels of another pass corresponding to the region of interest, or the print pixels of the first pass that were not printed before stopping are separated and added to multiple passes.

[0293] The embodiments according to the present disclosure have been described above with reference to the accompanying drawings. However, the present disclosure is not limited to these examples. Fig.11 or Fig.16 The present disclosure is not limited to the inkjet printing device for the print control shown in the embodiment, but is also applicable to an image processing device that generates data for performing the print control in each of the above-mentioned embodiments and supplies the generated data to the printing device. In addition, the present disclosure is applicable to a program for causing a computer to execute the print control in each of the embodiments and a storage medium storing the program.

[0294] Furthermore, the present disclosure is applicable to various printing apparatuses such as a thermal jet inkjet printing apparatus and a so-called piezoelectric inkjet printing apparatus that ejects ink using a piezoelectric element, for example.

[0295] Additionally, it is obvious that those skilled in the art can obtain various modifications and corrections within the scope of the technical concept disclosed in the present application, and it should be understood that these modifications and corrections naturally belong to the technical scope of the present invention.

[0296] Other embodiments

[0297] The embodiments of the present invention may also be implemented by providing software (program) for performing the functions of the above-described embodiments to a system or device via a network or various storage media, and a computer or a central processing unit (CPU) or a microprocessing unit (MPU) of the system or device reads and executes the program.

[0298] According to the present disclosure, it is possible to prevent or reduce a reduction in throughput of multi-pass printing, and also to prevent or reduce the occurrence of unevenness in areas printed before and after stopping.

[0299] While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the present disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A printing device, comprising: a printing unit including a printing element array and configured to scan the printing element array in a first direction, the printing element array being an array of a plurality of printing elements for applying ink onto a printing medium; a conveying unit configured to convey the printing medium in a second direction intersecting the first direction; as well as a control unit configured to control the printing unit and the conveying unit to repeatedly cause the printing unit to scan a unit area on the printing medium a plurality of times and to cause the conveying unit to convey the printing medium over a distance shorter than a length of an arrangement range of the printing element array in the first direction, Wherein, after starting to print an image on the printing medium and inserting a stop operation for preventing the printing unit from scanning for a predetermined time or longer, the control unit controls the printing unit and the conveying unit to perform a first scan in at least one scan before the stop operation and to perform a second scan in at least one scan started again after a predetermined time has passed from the stop, wherein the first scan is a scan of the printing element array without printing a printing area that has not yet been printed, and the second scan is a scan for printing the remaining part of the printing area that has not been printed in the first scan.

2. The printing device according to claim 1, wherein: The control unit controls the printing unit and the conveying unit to print the area except the unprinted printing area at the same printing rate as the mask pattern used in the normal scanning in the first scanning and not to print the area in the second scanning.

3. The printing device according to claim 1, wherein: The control unit controls the printing unit and the conveying unit so as not to convey the printing medium before each of the second scans.

4. The printing device according to claim 1, wherein: The control unit controls the printing unit and the conveying unit to perform the first scanning and the second scanning if the stop time is longer than a predetermined time.

5. The printing device according to claim 1, wherein: The first scanning direction in the second scanning is the same as the last scanning direction in the first scanning.

6. The printing device according to claim 1, wherein: The first scan is a single scan immediately before the stop.

7. The printing device according to claim 1, wherein: In a case where the first scan is performed in a plurality of scans before the stop, the number of times the first scan and the second scan are performed is determined based on a corresponding ratio to the number of passes of the multi-pass printing.

8. The printing device according to claim 1, wherein: A printing rate of a mask pattern used in a normal scan for a printing element group at an end portion in a conveyance direction of the print medium is smaller than a printing rate of a mask pattern for a printing element group at a center portion in the conveyance direction.

9. The printing device according to claim 1, wherein: When the first scanning is performed in the plurality of scannings before the stop, each print area of ​​the print area not printed in the first scanning is printed in sequence from the first scanning in the normal scanning in the second scanning.

10. A printing device comprising: a printing unit including a printing element array and configured to scan the printing element array in a first direction, the printing element array being an array of a plurality of printing elements for applying ink onto a printing medium; a conveying unit configured to convey the printing medium in a second direction intersecting the first direction; as well as a control unit configured to control the printing unit and the conveying unit to repeatedly cause the printing unit to scan a unit area on the printing medium a plurality of times and to cause the conveying unit to convey the printing medium over a distance shorter than a length of an arrangement range of the printing element array in the first direction, Wherein, after starting to print an image on the printing medium and inserting a stop operation for preventing the printing unit from scanning for a predetermined time or longer, the control unit controls the printing unit and the conveying unit to perform a first scan in at least one scan before the stop operation and to perform a second scan in at least one scan started again after a predetermined time has passed from the stop, wherein the first scan is a scan of a printing area that has been printed less than a predetermined number of times at a first printing rate, and the second scan is a scan of a printing area that has been printed at the first printing rate in the first scan at a second printing rate, wherein the second printing rate is greater than the first printing rate and supplements the first printing rate to achieve the remaining printing rate.

11. The printing apparatus according to claim 10, wherein The first printing rate is less than a predetermined printing rate.

12. A printing control method for repeatedly performing printing scanning and conveying, wherein in the printing scanning, a printing element array is scanned multiple times in a first direction for a unit area on a printing medium, the printing element array being an array of a plurality of printing elements for applying ink to the printing medium, and in the conveying, the printing medium is conveyed in a second direction intersecting the first direction and over a distance shorter than a length of an arrangement range of the printing element array in the first direction, the printing control method comprising: In the case where a stop operation for not performing the print scan for a predetermined time or longer is inserted after starting printing of an image on the print medium, performing a first scan in at least one scan before the stop operation, the first scan being a scan of scanning the printing element array without printing a printing area that has not yet been printed; as well as In at least one scanning that is restarted after a predetermined time has elapsed from the stop, a second scanning is performed, the second scanning being a scanning for printing a remaining portion of the print area that was not printed in the first scanning.

13. A printing control method for repeatedly performing printing scanning and conveying, wherein in the printing scanning, a printing element array is scanned multiple times in a first direction for a unit area on a printing medium, the printing element array being an array of a plurality of printing elements for applying ink to the printing medium, and in the conveying, the printing medium is conveyed in a second direction intersecting the first direction and over a distance shorter than a length of an arrangement range of the printing element array in the first direction, the printing control method comprising: In the case where a stop operation for not performing the print scan for a predetermined time or longer is inserted after starting printing of an image on the print medium, performing a first scan in at least one scan before the stopping operation, the first scan being a scan of printing a printing area that has been printed less than a predetermined number of times at a first printing rate; as well as A second scan is performed in at least one scan that is restarted after a predetermined time has passed since the stop, wherein the second scan is a scan of the print area printed at the first print rate in the first scan at a second print rate, wherein the second print rate is greater than the first print rate and supplements the first print rate to achieve the remaining print rate.

14. A non-transitory computer-readable storage medium storing one or more programs including instructions, which, when executed by one or more processors of a computer, cause the computer to execute a printing control method, the printing control method being used to repeatedly perform printing scanning and conveying, wherein in the printing scanning, a printing element array is scanned multiple times in a first direction for a unit area on a printing medium, the printing element array being an array of multiple printing elements for applying ink to the printing medium, and in the conveying, the printing medium is conveyed in a second direction intersecting the first direction and over a distance shorter than a length of an arrangement range of the printing element array in the first direction, the printing control method comprising: In the case where a stop operation for not performing the print scan for a predetermined time or longer is inserted after starting printing of an image on the print medium, performing a first scan in at least one scan before the stop operation, the first scan being a scan of scanning the printing element array without printing a printing area that has not yet been printed; as well as In at least one scanning that is restarted after a predetermined time has elapsed from the stop, a second scanning is performed, the second scanning being a scanning for printing a remaining portion of the print area that was not printed in the first scanning.

15. A non-transitory computer-readable storage medium storing one or more programs including instructions, which, when executed by one or more processors of a computer, cause the computer to execute a printing control method, the printing control method being used to repeatedly perform printing scanning and conveying, wherein in the printing scanning, a printing element array is scanned multiple times in a first direction for a unit area on a printing medium, the printing element array being an array of multiple printing elements for applying ink to the printing medium, and in the conveying, the printing medium is conveyed in a second direction intersecting the first direction and over a distance shorter than a length of an arrangement range of the printing element array in the first direction, the printing control method comprising: In the case where a stop operation for not performing the print scan for a predetermined time or longer is inserted after starting printing of an image on the print medium, performing a first scan in at least one scan before the stopping operation, the first scan being a scan of printing a printing area that has been printed less than a predetermined number of times at a first printing rate; as well as A second scan is performed in at least one scan that is restarted after a predetermined time has passed since the stop, wherein the second scan is a scan of the print area printed at the first print rate in the first scan at a second print rate, wherein the second print rate is greater than the first print rate and supplements the first print rate to achieve the remaining print rate.

16. A printing device comprising: a printing unit including a printing element array and configured to scan the printing element array in a first direction, the printing element array being an array of a plurality of printing elements for applying ink onto a printing medium; a conveying unit configured to convey the printing medium in a second direction intersecting the first direction; as well as a control unit configured to control the printing unit and the conveying unit to repeatedly cause the printing unit to scan each of the plurality of unit areas on the printing medium, and to cause the conveying unit to convey the printing medium over a distance shorter than the length of the arrangement range of the printing element array in the first direction, and to complete printing of an image on each of the unit areas in N scans, wherein N ≥ 3, Wherein, after starting to print an image on the printing medium, in a case where a stop operation is inserted to stop the printing unit from scanning for a predetermined time or longer, the control unit controls the printing unit and the conveying unit so that at the end of the scan immediately before the stop operation, there is at least one unfinished unit area that has been printed less than N times, and the duty cycle of printing of all the unfinished unit areas is lower than a first threshold or higher than a second threshold.

17. A computer program product comprising a program for causing one or more processors of a computer to execute the method according to claim 12.

18. A computer program product comprising a program for causing one or more processors of a computer to execute the method according to claim 13.

Images