JP6995503B2 - Inkjet printer - Google Patents

Description

The present invention relates to an inkjet printer.

Conventionally, a so-called multi-pass printing technique for printing a single printing area a plurality of times has been known. In multi-pass printing, in order to obtain a finer image, printing is performed a plurality of times for one print area to increase the resolution of the image. Patent Document 1 discloses an inkjet printer configured to print a smoother image in multi-pass printing.

JP-A-2017-355790

By the way, even in the case of multi-pass printing as described above, the density limit of the printed image is within the range of the resolution that can be realized by the inkjet printer. As long as it is within the range of the image resolution that can be processed, the inkjet printer can perform printing at the set resolution by a method such as the multi-pass printing described above. However, depending on the type of image to be printed and the type of recording medium, printing in which ink dots are arranged at a higher density than the resolution of an inkjet printer may be desired.

The inventor of the present application has devised a method of superimposing and landing a plurality of ink dots at the same position in response to the above-mentioned needs for high-density printing. For example, it is realized by forming a plurality of print layers extracted at a predetermined extraction rate by stacking them. For example, the number of print layers is three, and an extraction rate of 50% (the entire ink dot of the image is 100%) is set for each of the first print layer, the second print layer, and the third print layer. In this case, ink dots corresponding to 150% of the total ink dots of the image are formed on the recording medium 5. Of that amount, more than 100%, that is, 50%, is formed overlapping with other ink dots. The inventor of the present application has found that a clearer image can be obtained by the above-mentioned method while keeping the image data as it is.

However, the print product obtained by the above method may have the following problems. That is, for example, when high-density printing with a total printing rate of 150% is performed, 50% of ink dots exceeding 100% land on other ink dots, but the ink of 50% is used. The extraction pattern when extracting dots sometimes appeared as a pattern on the print product. This is because only a part of the ink dots constituting the image is duplicated. Alternatively, it is because the number of overlaps is large in some of the ink dots constituting the image.

The present invention has been made in view of this point, and an object of the present invention is to provide an inkjet printer capable of printing high-density images with higher quality.

The inkjet printer according to the present invention includes a recording head including a first ink head and a second ink head, and m extraction units (m is a natural number of 2 or more) from the first extraction unit to the m extraction unit. (1) A control device having m print control units from the print control unit to the mth print control unit is provided. The first ink head includes a plurality of first nozzles for ejecting the first ink toward the recording medium, and forms ink dots of the first ink on the recording medium. The second ink head includes a plurality of second nozzles for ejecting the second ink toward the recording medium, and forms ink dots of the second ink on the recording medium. The first to m-th print control units control the recording head to form m print layers from the first print layer to the m-th print layer on the recording medium. The nth extraction unit (n is all natural numbers of m or less) includes an nth extraction unit of the first ink and an nth extraction unit of the second ink. The nth extraction unit of the first ink receives the data of the ink dots of the first ink, and extracts the nth dot group of the first ink consisting of a part or all of the ink dots of the first ink. At that time, the nth extraction unit of the first ink extracts the nth dot group of the first ink from the ink dots of the first ink by the mask in which the nth mask pattern of the first ink is set. Further, the dot group of each first ink from the first dot group of the first ink to the m dot group of the first ink includes all the ink dots of the first ink, and at least a part of the ink. The dots are configured to overlap. The nth extraction unit of the second ink receives the data of the ink dots of the second ink, and extracts the nth dot group of the second ink consisting of a part or all of the ink dots of the second ink. At that time, the nth extraction unit of the second ink extracts the nth dot group of the second ink from the ink dots of the second ink by the mask in which the nth mask pattern of the second ink is set. Further, the dot group of each second ink from the first dot group of the second ink to the m dot group of the second ink includes all the ink dots of the second ink, and at least a part of the ink. The dots are configured to overlap. Then, the nth print control unit forms an nth print layer composed of ink dots including at least the nth dot group of the first ink and the nth dot group of the second ink.

According to the inkjet printer, ink dots (“dot group”) can be extracted with a mask pattern different for each ink color in the formation of each print layer. Therefore, for example, even if a mask pattern is seen as a pattern in the extraction of the "dot group" of one ink, if a mask of another mask pattern is used in the extraction of the "dot group" of another ink, the entire image can be used. As a result, the occurrence of patterns can be suppressed.

It is a front view of the inkjet printer which concerns on 1st Embodiment. It is a schematic diagram which shows the structure of the lower surface of a carriage. It is a block diagram of a printer. This is an example of the print mode and image quality setting screen. It is a figure which shows an example of the setting screen of an internal parameter in an image quality setting part. It is a figure which shows the 1st dot group which concerns on 1st Embodiment. It is a figure for comparison which shows the 1st dot group when the extraction was performed with a single mask pattern. It is a figure which shows the process until the first dot group shown in FIG. 6 is completed, and is the figure which shows the first time point. It is a figure which shows the next time point of FIG. 8A. It is a figure which shows the next time point of FIG. 8B. It is a figure which shows the next time point of FIG. 8C. It is a figure which shows the internal parameter setting screen of the image quality which concerns on 2nd Embodiment. It is a figure which shows the 1st dot group which concerns on 2nd Embodiment.

Hereinafter, the inkjet printer according to some embodiments will be described with reference to the drawings. It should be noted that the embodiments described here are, of course, not intended to specifically limit the present invention. In addition, members and parts that perform the same action are designated by the same reference numerals, and duplicate explanations will be omitted or simplified as appropriate. In the following description, when the inkjet printer is viewed from the front, the side away from the inkjet printer is referred to as the front, and the side closer to the inkjet printer is referred to as the rear. Further, the reference numeral Y in the drawing indicates the main scanning direction, and the reference numeral X indicates the sub-scanning direction X orthogonal to the main scanning direction Y. Further, the reference numerals F, Rr, L, R, U, and D in the drawing represent front, back, left, right, top, and bottom, respectively. However, these are merely directions for convenience of explanation, and do not limit the installation mode of the inkjet printer.

(First Embodiment)
FIG. 1 is a front view of a large-format inkjet printer (hereinafter referred to as “printer”) 10 according to the first embodiment. The printer 10 sequentially moves the roll-shaped recording medium 5 forward (downstream X2 side of the sub-scanning direction X, see FIG. 2), and the ink heads 40, 50 mounted on the carriage 25 that moves in the main scanning direction Y. , 60, 70 (see FIG. 2) to print an image on the recording medium 5.

The recording medium 5 is an object on which an image is printed. The recording medium 5 is not particularly limited. The recording medium 5 may be, for example, paper such as plain paper or ink jet printing paper, a transparent sheet made of resin or glass, or a sheet made of metal or rubber. It may be.

As shown in FIG. 1, the printer 10 includes a printer main body 10a and legs 11 that support the printer main body 10a. The printer body 10a extends in the main scanning direction Y. The printer main body 10a includes a guide rail 21 and a carriage 25 engaged with the guide rail 21. The guide rail 21 extends in the main scanning direction Y. The guide rail 21 guides the movement of the carriage 25 in the main scanning direction Y. An endless belt 22 is fixed to the carriage 25. The belt 22 is wound around a pulley 23a provided on the right side of the guide rail 21 and a pulley 23b provided on the left side. A carriage motor 24 is attached to the pulley 23a on the right side. The carriage motor 24 is electrically connected to the control device 100. The carriage motor 24 is controlled by the control device 100. When the carriage motor 24 is driven, the pulley 23a rotates and the belt 22 travels. As a result, the carriage 25 moves along the guide rail 21 in the main scanning direction Y. As the carriage 25 moves in the main scanning direction Y in this way, the ink heads 40 to 70 also move in the main scanning direction Y. In the present embodiment, the belt 22, the pulley 23a, the pulley 23b, and the carriage motor 24 are an example of the carriage moving mechanism 20 that moves the carriage 25 and the ink heads 40 to 70 mounted on the carriage 25 in the main scanning direction Y. ..

A platen 12 is arranged below the carriage 25. The platen 12 extends in the main scanning direction Y. The recording medium 5 is placed on the platen 12. Above the platen 12, a pinch roller 31 for pressing the recording medium 5 from above is provided. The pinch roller 31 is arranged behind the carriage 25. The platen 12 is provided with a grit roller 32. The grit roller 32 is arranged below the pinch roller 31. The grit roller 32 is provided at a position facing the pinch roller 31. The grit roller 32 is connected to a feed motor 33 (see FIG. 3). The grit roller 32 is formed so as to be rotatable by receiving the driving force of the feed motor 33. The feed motor 33 is electrically connected to the control device 100. The feed motor 33 is controlled by the control device 100. When the grit roller 32 rotates with the recording medium 5 sandwiched between the pinch roller 31 and the grit roller 32, the recording medium 5 is conveyed in the sub-scanning direction X. In the present embodiment, the pinch roller 31, the grit roller 32, and the feed motor 33 are an example of a transfer mechanism 30 that moves the recording medium 5 in the sub-scanning direction X. The transport mechanism 30 and the carriage moving mechanism 20 form a moving mechanism that relatively moves the recording medium 5 and the carriage 25.

FIG. 2 is a schematic view showing the configuration of a surface (lower surface in this embodiment) of the carriage 25 on the side facing the recording medium 5. As shown in FIG. 2, a first ink head 40, a second ink head 50, a third ink head 60, and a fourth ink head 70 are held on the lower surface of the carriage 25. In the carriage 25, the first ink heads 40 to the fourth ink heads 70 are arranged side by side in the main scanning direction Y.

Each of the four ink heads of the first ink head 40 to the fourth ink head 70 ejects process color ink for forming a color image. In the present embodiment, the first ink head 40 ejects cyan ink. The second ink head 50 ejects magenta ink. The third ink head 60 ejects yellow ink. The fourth ink head 70 ejects black ink. However, the number of ink heads is not limited to four, and the color tone of the process color ink is not limited at all.

As shown in FIG. 2, each of the plurality of ink heads 40, 50, 60, 70 has a plurality of nozzles arranged in the sub-scanning direction X. A plurality of nozzles of each ink head are arranged in a row in the sub-scanning direction X to form a nozzle row. More specifically, the first ink head 40 includes a plurality of nozzles 41 arranged in the sub-scanning direction X, and the plurality of nozzles 41 constitute a nozzle row 42. The second ink head 50 includes a plurality of nozzles 51 arranged in the sub-scanning direction X, and the plurality of nozzles 51 form a nozzle row 52. The third ink head 60 includes a plurality of nozzles 61 arranged in the sub-scanning direction X, and the plurality of nozzles 61 form a nozzle row 62. The fourth ink head 70 includes a plurality of nozzles 71 arranged in the sub-scanning direction X, and the plurality of nozzles 71 form a nozzle row 72. In FIG. 2, 15 nozzles are shown in each of the ink heads 40 to 70, but in reality, a larger number (for example, 300) nozzles are formed. However, the number of nozzles is not limited at all.

The nozzle rows 42 to 72 of the plurality of ink heads 40 to 70 are each divided into a plurality of partial nozzle rows arranged in the sub-scanning direction X. Looking at the first ink head 40, the nozzle row 42 is divided into three partial nozzle rows 42a, 42b, and 42c. Hereinafter, the partial nozzle row indicated by the reference numeral 42a is referred to as a first nozzle row 42a, the partial nozzle row indicated by the reference numeral 42b is referred to as a second nozzle row 42b, and the partial nozzle row indicated by the reference numeral 42c is referred to as a third nozzle row 42c. Then, the first nozzle row 42a is composed of five nozzles 41 provided on the upstream X1 side of the sub-scanning direction X most among the nozzles 41. The second nozzle row 42b is composed of five nozzles 41 provided on the upstream X1 side of the sub-scanning direction X next to the nozzle 41 belonging to the first nozzle row 42a among the nozzles 41. The third nozzle row 42c is composed of five nozzles 41 provided on the downstream side X2 of the sub-scanning direction X. The number of nozzles 41 in the first nozzle row 42a, the second nozzle row 42b, and the third nozzle row 42c is the same (here, five). Therefore, the lengths of the first nozzle row 42a, the second nozzle row 42b, and the third nozzle row 42c in the sub-scanning direction X are the same. The other ink heads 50 to 70 also have a nozzle row configuration similar to that of the first ink head 40. Specifically, in the second ink head 50, the nozzle row 52 is divided into a first nozzle row 52a, a second nozzle row 52b, and a third nozzle row 52c. In the third ink head 60, the nozzle row 62 is divided into a first nozzle row 62a, a second nozzle row 62b, and a third nozzle row 62c. In the fourth ink head 70, the nozzle row 72 is divided into a first nozzle row 72a, a second nozzle row 72b, and a third nozzle row 72c. In all the above nozzle rows, the number of nozzles belonging to them is the same (5). Therefore, the length with respect to the sub-scanning direction X is the same. Further, the first nozzle row 42a of the first ink head, the first nozzle row 52a of the second ink head, the first nozzle row 62a of the third ink head, and the first nozzle row 72a of the fourth ink head are sub-scanned. They are arranged in the same position with respect to the direction X. The same applies to the second nozzle row and the third nozzle row. It should be noted that the division of the nozzle train is for control purposes and does not mean that there is a mechanical difference.

Inside the first ink head 40 to the fourth ink head 70, an actuator (not shown) provided with a piezoelectric element or the like is provided. The actuator is electrically connected to the control device 100. The actuator is controlled by the control device 100. By driving the actuator, a plurality of nozzles 41 of the first ink head 40, a plurality of nozzles 51 of the second ink head 50, a plurality of nozzles 61 of the third ink head 60, and a plurality of nozzles 71 of the fourth ink head 70 are driven. Ink is ejected from the recording medium 5 toward the recording medium 5.

The first ink head 40, the second ink head 50, the third ink head 60, and the fourth ink head 70 are each communicated with an ink cartridge (not shown) by an ink supply path (not shown). The ink cartridge is detachably arranged, for example, at the right end of the printer body 10a. The ink material is not limited in any way, and various materials conventionally used as ink materials for inkjet printers can be used. The ink may be, for example, a solvent-based (solvent-based) pigment ink, a water-based pigment ink, a water-based dye ink, an ultraviolet curable pigment ink that is cured by receiving ultraviolet rays, or the like.

As shown in FIG. 1, the printer 10 includes a heater 35. The heater 35 is provided below the platen 12. The heater 35 is arranged in front of the grit roller 32. The heater 35 heats the platen 12. By heating the platen 12, the ink landing on the recording medium 5 and the recording medium 5 arranged on the platen 12 is heated, and the drying of the ink is promoted. The heater 35 is electrically connected to the control device 100. The heating temperature of the heater 35 is controlled by the control device 100.

As shown in FIG. 1, an operation panel 150 is provided at the right end of the printer main body 10a. The operation panel 150 is provided with a display unit for displaying the device status, an input key operated by the user, and the like. Inside the operation panel 150, a control device 100 that controls various operations of the printer 10 is housed. FIG. 3 is a block diagram of the printer 10 according to the present embodiment. As shown in FIG. 3, the control device 100 can communicate with the feed motor 33, the carriage motor 24, the heater 35, the first ink head 40, the second ink head 50, the third ink head 60, and the fourth ink head 70, respectively. It is connected to and configured to control them. The control device 100 includes a conversion unit 101, a mode selection unit 102, an image quality setting unit 103, a normal print control unit 104, a high-density print control unit 110, and an extraction unit 120.

The configuration of the control device 100 is not particularly limited. The control device 100 is, for example, a microcomputer. The hardware configuration of the microcomputer is not particularly limited, but for example, an interface (I / F) for receiving print data or the like from an external device such as a host computer, and a central processing unit (CPU: central) for executing control program instructions. Processing unit), ROM (read only memory) that stores the program executed by the CPU, RAM (random access memory) that is used as a working area to expand the program, memory that stores the above program and various data, etc. It is equipped with a storage device. The control device 100 does not necessarily have to be provided inside the printer main body 10a. For example, a computer installed outside the printer main body 10a and connected to the printer main body 10a via a wire or wireless communication, or the like. It may be.

The conversion unit 101 is a portion that performs so-called screen processing that converts image data into an ink dot pattern. The image printed by the inkjet printer is configured as an aggregate of ink dots of each process color ink. In the printer 10 according to the present embodiment, the image is converted into an ink dot pattern composed of four colors of cyan, magenta, yellow, and black. The conversion unit 101 may be provided in the printer main body 10a, or may be provided in an external computer or the like. In the following description, the aggregate of ink dots generated by the conversion unit 101 is appropriately referred to as "the entire ink dot", and the aggregate of ink dots of a specific color ink is referred to as, for example, "cyan ink". Ink dots as a whole "etc.

The mode selection unit 102 is a part where a printing method is selected. In the present embodiment, the print mode is divided into a "normal print mode" and a "high density print mode". In the normal print mode, the printer 10 forms the ink dot pattern generated by the conversion unit 101 on the recording medium 5 as it is. The normal print mode is a mode for executing printing normally performed in a known printer. In the high-density printing mode, the printer 10 forms an ink dot pattern on the recording medium 5 in which the ink dots generated by the conversion unit 101 are partially overlapped. In the present embodiment, three printing layers consisting of a part or all of the entire ink dots are printed on the recording medium 5. At that time, the printing density is increased by forming at least a part of the ink dots on top of each other at the same position. Hereinafter, each of the above three print layers will be referred to as a first print layer, a second print layer, and a third print layer from the bottom. The details of the high-density printing mode will be described later. In the mode selection unit 102 according to the present embodiment, the selection of the print mode is performed by the operator via the operation screen displayed on the operation panel 150, the display device of the external computer, or the like, but is not limited thereto. For example, the print mode may be incorporated in the print data in advance and automatically selected by the mode selection unit 102.

The image quality setting unit 103 is a portion where parameters for print image quality in the high-density print mode are set. The image quality setting unit 103 includes an extraction rate setting unit 103a. The extraction rate setting unit 103a sets the ratio of each ink dot group forming the first to third print layers to the entire ink dots generated by the conversion unit 101. In the following, the ink dot group forming the first print layer is referred to as the “first dot group”, the ink dot group forming the second print layer is referred to as the “second dot group”, and the ink dot group forming the third print layer is appropriately described below. Will be referred to as a "third dot group". In the present embodiment, since the print layers are the three layers of the first to third print layers, the first extraction rate (corresponding to the first print layer), the second extraction rate (corresponding to the second print layer), and the third Three extraction rates (corresponding to the third print layer) are set. The extraction rate in this embodiment is common to all ink colors. The details of setting the extraction rate will be described later. In the image quality setting unit 103, other parameters related to the image quality may be adjusted, but they will be omitted in the description of the present embodiment.

The normal print control unit 104 is a portion that controls the print operation in the normal print mode. The normal print control unit 104 is connected to a carriage motor 24, a feed motor 33, a first ink head 40, a second ink head 50, a third ink head 60, and a fourth ink head 70, and is normally controlled by controlling them. Print. Further, the normal print control unit 104 is connected to the heater 35 and controls the temperature of the heater 35 to control the drying of the ink after printing.

The high-density printing control unit 110 is a portion that controls the printing operation in the high-density printing mode. The high-density print control unit 110 is also connected to the carriage motor 24, the feed motor 33, the first ink head 40, the second ink head 50, the third ink head 60, the fourth ink head 70, and the heater 35, and controls them. By doing so, high-density printing is performed. The high-density print control unit 110 includes a first print control unit 110a, a second print control unit 110b, and a third print control unit 110c.

The first print control unit 110a is a portion that controls printing of the first print layer in the high-density print mode. The first print layer is a print layer formed at the lowest layer among the print layers formed in layers in the high-density printing mode. The "first dot group" constituting the first print layer is formed by inks of each color ejected from the nozzles of the first nozzle row arranged on the upstream X1 side of the sub-scanning direction X most among the three nozzle rows. Will be done. Therefore, the first print control unit 110a controls the ejection of cyan ink from the nozzle 41 belonging to the first nozzle row 42a of the first ink head 40. Further, the first print control unit 110a controls the ejection of magenta ink from the nozzle 51 belonging to the first nozzle row 52a of the second ink head 50. Similarly, the first print control unit 110a controls the ejection of yellow ink from the nozzle 61 belonging to the first nozzle row 62a of the third ink head 60. Further, the ejection of black ink from the nozzle 71 belonging to the first nozzle row 72a of the fourth ink head 70 is controlled. The first print control unit 110a controls the movement of the carriage 25 by controlling the drive of the carriage motor 24 in addition to the ink ejection control. The details of the above control will be described later.

The second print control unit 110b is a portion that controls printing of the second print layer in the high-density print mode. The second print layer is a print layer formed immediately above the first print layer among the print layers formed in layers in the high-density printing mode. The "second dot group" constituting the second print layer is formed by inks of each color ejected from the nozzles of the second nozzle row. Specifically, the second print control unit 110b controls the ejection of cyan ink from the nozzle 41 belonging to the second nozzle row 42b of the first ink head 40, and the nozzle belonging to the second nozzle row 52b of the second ink head 50. Controls the ejection of magenta ink from 51. Further, the ejection of yellow ink from the nozzle 61 belonging to the second nozzle row 62b of the third ink head 60 is controlled, and the ejection of black ink from the nozzle 71 belonging to the second nozzle row 72b of the fourth ink head 70 is controlled. do. The second print control unit 110b controls the movement of the carriage 25 by controlling the drive of the carriage motor 24 in addition to the ink ejection control.

The third print control unit 110c is a portion that controls printing of the third print layer in the high-density print mode. The third print layer is a print layer formed immediately above the second print layer, that is, on the uppermost layer among the print layers formed in layers in the high-density printing mode. The ink dots constituting the third print layer are formed by inks of each color ejected from the nozzles of the third nozzle row. Specifically, the third print control unit 110c controls the ejection of cyan ink from the nozzle 41 belonging to the third nozzle row 42c of the first ink head 40, and the nozzle belonging to the third nozzle row 52c of the second ink head 50. Controls the ejection of magenta ink from 51. Further, the ejection of yellow ink from the nozzle 61 belonging to the third nozzle row 62c of the third ink head 60 is controlled, and the ejection of black ink from the nozzle 71 belonging to the third nozzle row 72c of the fourth ink head 70 is controlled. do. The third print control unit 110c controls the movement of the carriage 25 by controlling the drive of the carriage motor 24 in addition to the ink ejection control.

The extraction unit 120 is a portion that receives the ink dot data of each ink generated by the conversion unit 101 and extracts the “first dot group” to the “third dot group” from the ink dots of each ink. The extraction unit 120 according to the present embodiment includes 12 extraction units corresponding to each of the four color inks × three layers of printing. The first extraction unit 121 extracts the "first dot group" to the "third dot group" of the cyan ink. As shown in FIG. 3, the first extraction unit 121 further includes a first extraction unit 121a, a second extraction unit 121b, and a first-3 extraction unit 121c. The 1-1 extraction unit 121a extracts the "first dot group" of the cyan ink from the entire ink dots of the cyan ink. The first-2 extraction unit 121b extracts the "second dot group" of the cyan ink from the entire ink dots of the cyan ink. The first-3 extraction unit 121c extracts the "third dot group" of the cyan ink from the entire ink dots of the cyan ink. The same applies to inks of colors other than cyan ink. The second extraction unit 122 extracts the "first dot group" to the "third dot group" of magenta ink. The 2-1 extraction unit 122a of the second extraction unit 122 extracts the "first dot group" of magenta ink. The 2-2 extraction unit 122b extracts the "second dot group" of magenta ink. The second-third extraction unit 122c extracts the "third dot group" of magenta ink. Similarly, the third extraction unit 123 extracts the "first dot group" to the "third dot group" of the yellow ink. Of the third extraction unit 123, the 3-1 extraction unit 123a extracts the "first dot group" of the yellow ink. The 3-2 extraction unit 123b extracts the "second dot group" of the yellow ink. The 3rd-3rd extraction unit 123c extracts the "third dot group" of the yellow ink. Further, the fourth extraction unit 124 extracts the "first dot group" to the "third dot group" of the black ink. The 4-1 extraction unit 124a of the fourth extraction unit 124 extracts the "first dot group" of the black ink. The second extraction unit 124b extracts the "second dot group" of the black ink. The 4th-3rd extraction unit 124c extracts the "third dot group" of the black ink. The method of extracting each dot group of each color will be described later.

Printing in the normal printing mode (normal printing) is performed as follows. In normal printing, the normal print control unit 104 drives the carriage motor 24 to move the carriage 25 in the main scanning direction Y, and drives the actuator to eject ink from the first ink heads 40 to the fourth ink head 70. Then, the inks of each color are landed on the recording medium 5. Further, the normal print control unit 104 controls the feed motor 33 so that the recording medium 5 is sequentially sent forward F (downstream X2 side of the sub-scanning direction X). The ink on the recording medium 5 sent out to the feed motor 33 is sequentially heated and dried by the heater 35. The normal print control unit 104 moves the carriage 25 once or a plurality of times in the main scanning direction Y, for example, before the recording medium 5 is sent forward once.

By the way, in the above-mentioned normal printing, the formation positions of the ink dots on the recording medium 5 are different from each other. In other words, only one ink dot is formed at the formation position of each ink dot, and the density of the ink dots in that state is the density of the ink dots in the normal printing mode. The density of ink dots can be increased by increasing the resolution of the image data (making the pixels finer), but the limit is within the range of the resolution that can be realized by the printer 10. When the resolution of the image data is set high, the printer 10 prints at the set resolution by a method such as so-called multi-pass printing. However, depending on the type of image to be printed and the type of recording medium, printing in which ink dots are arranged at a higher density than the resolution of the printer 10 may be desired.

The inventor of the present invention has devised a method of superimposing and landing a plurality of ink dots at the same position in response to the above-mentioned needs for high-density printing. For example, the above method is realized by superimposing three print layers extracted at a predetermined extraction rate, as in the present embodiment. For example, when an extraction rate of 50% is set for each of the first print layer, the second print layer, and the third print layer, ink dots corresponding to 150% of the total ink dots are formed on the recording medium 5. .. Of that amount, more than 100%, that is, 50%, is formed overlapping with other ink dots. Each of the "first dot group" forming the first print layer, the "second dot group" forming the second print layer, and the "third dot group" forming the third print layer mask the entire ink dots. Extracted by multiplying.

According to the print product printed by the above method, a high-density image was obtained, but on the other hand, the following problems may occur. That is, the extraction pattern when extracting the overlapping ink dots may appear as a pattern on the print product. In the above example, 50% of the excess amount with respect to 100% may be seen as a pattern on the printed product. This is because only a part of the ink dots constituting the image is duplicated. Alternatively, this is because the number of times of duplication is large in a part of the ink dots constituting the image (for example, when some ink dots are overlapped three times and other ink dots are overlapped twice).

Therefore, the printer 10 according to the present embodiment is provided with an extraction unit for each combination of the ink color and the print layer, and is configured to be able to extract each "dot group" with an independent mask. In the conventional method, for example, the "first dot group" is extracted from the entire ink dots by a predetermined mask. Then, as described above, in that method, the mask pattern at the time of extraction may be seen as a pattern. However, the printer 10 according to the present embodiment can extract ink dots with a mask pattern different for each ink color even in the "first dot group". Therefore, for example, even if a mask pattern is seen as a pattern in the extraction of the "first dot group" of one ink, a mask of another mask pattern may be used in the extraction of the "first dot group" of another ink. For example, it is possible to suppress the occurrence of patterns in the entire image.

In the high-density printing mode, the total extraction rate of the "first dot group", "second dot group", and "third dot group" of each ink is set to exceed 100%. In other words, the ink dots of the "first dot group", "second dot group", and "third dot group" of each ink include all the ink dots of each ink, and at least a part of them overlap. is doing.

The process of high-density printing in this embodiment will be described below. When performing high-density printing, the print mode and image quality are first set. FIG. 4 is an example of a print mode and image quality setting screen according to the present embodiment. The setting screen of FIG. 4 is displayed on the operation panel 150, a display device of a computer, or the like by the mode selection unit 102 and the image quality setting unit 103. The mode selection unit 102 includes a first radio button RB1 on the setting screen of FIG. The first radio button RB1 selects a print mode. As shown in FIG. 4, the first radio button RB1 is configured so that one print mode can be selectively selected from two types of print modes, "normal printing" and "high density printing". In the example shown in FIG. 4, "high density printing" is selected.

The image quality setting unit 103 includes a second radio button RB2 on the setting screen of FIG. As shown in FIG. 4, the second radio button RB2 is configured so that five types of image quality, A, B, C, D, and E, can be selectively selected. In the example shown in FIG. 4, "image quality A" is selected. In the image quality setting unit 103 according to the present embodiment, the parameters of the image quality A to E are set in advance inside the image quality setting unit 103, and the user selects a desired image quality. The image quality A to E are given names representing characteristics of image quality such as "clear" and "soft".

FIG. 5 is a diagram showing an example of an internal parameter setting screen in the image quality setting unit 103. The internal parameter setting screen according to this embodiment is created in an area that the user cannot normally operate. However, this does not exclude embodiments in which the user can manipulate internal parameters. As shown in FIG. 5, the first extraction rate RP1 to the third extraction rate RP3 are set on the internal parameter setting screen. For example, in the image quality A, the first extraction rate is set to 30%, the second extraction rate is set to 50%, and the third extraction rate is set to 50%.

Each "dot group" in the image quality A is extracted from the entire ink dot of each ink. For example, if the number of ink dots of cyan ink is 10,000 in the entire image, the number of ink dots of cyan ink belonging to the "first dot group" is 3000, which is 30% of the ink dots. Similarly, the number of cyan inks in the "second dot group" is 5,000, and the number of cyan inks in the "third dot group" is 5,000. Further, for example, if the number of ink dots of magenta ink is 20,000 in the entire image, the number of ink dots of magenta ink belonging to the "first dot group" is 6000, which is 30% of the number of ink dots. The number of magenta inks in the "second dot group" is 10,000, and the number of magenta inks in the "third dot group" is 10,000. The same applies to yellow ink and black ink. Extraction of these "dot groups" is performed by a mask associated with each combination of the ink color and the "dot group".

Each of the above masks is, for example, a dither mask. The dither mask is a mask that extracts some ink dots by the dither method. The dither method is one of the pseudo-gradation expression algorithms. In the dither method, when the ink value of the image data exceeds a predetermined threshold value in a minute area in the print area, the ink dot in the area is turned on. On the contrary, when the ink value of the image data falls below a predetermined threshold value, the ink dot is turned off. For example, in the simplest binary dithering, image data is divided into an ON region and an OFF region with one threshold value as a boundary. Therefore, the image to which the dither mask is applied by dither dithering becomes a coarse image with a small number of pixels while retaining the characteristics of the original image to some extent. However, the dither method is not limited to binary dithering. For example, the dither method includes a systematic dither method using a matrix to which a threshold value is assigned, and a random dither method in which a threshold value is randomly set in a certain range. The extraction rate is set in the dither mask. The twelve masks of the present embodiment are independent of each other, but with respect to the extraction rate, between the "first dot group" of the four color inks and between the "second dot group" of the four color inks, 4 It is common among the "third dot group" of color inks. This is because the color balance of the original image is not changed in each print layer.

The extraction of ink dots by the dither mask as described above is performed so that no artificial unnaturalness remains in the extraction. That is, according to the dither mask, a certain variation is expected in the positions of the ink dots to be extracted, and biased extraction is unlikely to occur. However, as described above, the pattern may still be visible in the extracted ink dots. According to the printer 10 according to the present embodiment, it is possible to suppress the visual recognition of the ink dot extraction pattern by changing the dither mask pattern for each ink color.

In the printer 10 according to the present embodiment, since the internal parameter setting screen of the image quality setting unit 103 is not normally operated, the image quality set so as to suppress the pattern of the image is prepared in advance. Each extraction unit 121a to 124c of the extraction unit 120 extracts each "dot group" of each color ink based on the selected image quality.

FIG. 6 is a diagram showing a “first dot group” extracted when the image quality A is selected in the second radio button RB2 of FIG. FIG. 7 is a comparative diagram showing a “first dot group” when extraction is performed with a single mask pattern. FIG. 6 and FIG. 7 show 100 points. The above 100 points indicate the positions on the recording medium 5 on which the ink dots of the process color ink are formed in the original image. That is, the above 100 points correspond to 100% of ink dots. Further, for the sake of simplification of the explanation, in the original image, it is assumed that four color ink dots of cyan, magenta, yellow, and black are overlapped at each point of FIGS. 6 and 7. In actual printing, each ink dot does not land at the same position but at a position close to each other, and not all four colors land near the position.

In FIG. 7, the first dot group D1 is composed of 30 points extracted by the dither mask. The first dot group D1 is indicated by a black circle in FIG. 7. The first dot group D1 in FIG. 7 is formed by overlapping the ink dots of the four color inks. The white circles are points that are not extracted as the first dot group D1 (= points where ink is not ejected during printing of the first print layer). Although it is not so extreme in actual ejection, it is possible to see in FIG. 7 that the first dot group D1 draws a pattern flowing from the upper right to the lower left of the figure.

On the other hand, as described above, FIG. 6 is a schematic diagram of the case where the first print layer is printed by the printer 10 according to the present embodiment. In FIG. 6, the reference numeral Dc1 represents "the first dot group of cyan ink". The first dot group Dc1 of the cyan ink is indicated by a hatched circle. Further, the reference numeral Dm1 represents "the first dot group of magenta ink". The first dot group Dm1 of magenta ink is indicated by a triangle. Similarly, the first dot group Dy1 of the yellow ink is represented by a double circle, and the first dot group Dk1 of the black ink is represented by a square. Also in FIG. 6, the points where the plurality of "first dot groups" overlap are represented by black circles and are represented by the reference numeral Do1.

In the present embodiment, each mask pattern for extracting the ink dots of the "first dot group" is set so that the overlap rate in the "first dot group" is minimized. The "overlap rate of the first dot group" is the ratio of the ink dots whose formation positions overlap in the entire ink dots of the "first dot group". The minimum duplication rate is calculated according to the extraction rate. In the present embodiment, when the first extraction rate RP1 is set, the mask pattern of each color is automatically set so that the overlap of positions between the ink dots of the "first dot group" is minimized. The same applies to the "second dot group" and the "third dot group".

8A, 8B, 8C, and 8D are diagrams showing the process until the arrangement of the "first dot group" shown in FIG. 6 is completed. Of these, FIG. 8A represents the first time point, followed by FIGS. 8B, 8C, and 8D. The time point following the time point shown in FIG. 8D is the time point (completed form) in FIG. In FIG. 8A, the first dot group Dc1 of the cyan ink is extracted. However, this is only one example, and extraction may be started from the "first dot group" of another color. In FIG. 8A, the number of points from which the first dot group Dc1 of the cyan ink is extracted is 25 points. This is to divide 100 points into four colors of cyan, magenta, yellow, and black without duplication. As shown in FIG. 8A, the 25 ink dots of the first dot group Dc1 of the cyan ink have a pattern similar to that of FIG. 7.

FIG. 8B is a diagram showing the next time point of FIG. 8A, and is a schematic diagram when the first dot group Dm1 of magenta ink is extracted. The first dot group Dm1 of the magenta ink is extracted from the points where the first dot group Dc1 of the cyan ink was not extracted. The number is 25. The mask pattern of the mask that extracts the first dot group Dm1 of the magenta ink is a mask pattern that preferentially extracts from the points where the first dot group Dc1 of the cyan ink is not extracted. As a result of extracting the first dot group Dm1 of the magenta ink, 25 pieces of the first dot group Dc1 of the cyan ink and 25 pieces of the first dot group Dm1 of the magenta ink are shown in FIG. 8B, respectively. The 25 ink dots of the first dot group Dm1 of magenta ink draw a pattern flowing from the upper left to the lower right of FIG. 8B.

Similar processing is performed in FIGS. 8C and 8D. In FIG. 8C, the first dot group Dy1 of the yellow ink is extracted. In FIG. 8D, the first dot group Dk1 of the black ink is extracted. In any of the figures, the ink dots are extracted so that the ink dots of each color do not overlap with each other. As of FIG. 8D, all 100 points are extracted as the formation points of any "first dot group".

As shown in FIG. 4, the first extraction rate RP1 of the image quality A is 30%. However, the extraction rate of each process color ink at the time shown in FIG. 8D is 25%. Therefore, the remaining 5% of ink dots for each color are further extracted. Since all 100 points already belong to one of the "first dot groups", the extraction for the remaining 5% is a duplicate extraction. The form of duplication is not limited, but in the present embodiment, the remaining 5% is due to duplication of four colors. That is, five points where all four colors overlap are extracted, and the remaining 5% is replenished by the above extraction. At the above five points, a first dot group Do1 formed by overlapping ink dots of four colors is formed. FIG. 6 is a diagram showing a state after replenishment, that is, a completed form of "first dot group" extraction.

As shown in FIG. 6, the first dot groups D1 to Dk1 extracted by the printer 10 according to the present embodiment are less likely to feel a pattern than those shown in FIG. 7. In this way, by avoiding the overlap of the ink dots extracted as the "first dot group" between the inks as much as possible, the pattern property related to the extraction becomes inconspicuous, and the pattern of the image printed on the first print layer is suppressed. Be done.

The duplication rate RO1 (first duplication rate RO1) in the above case is about 17% because 20 (5 x 4 colors) ink dots are duplicated out of a total of 120 (30 x 4 colors). Yes (see Figure 5). When the process color ink has four colors and the first extraction rate RP1 is 30%, the minimum first overlap rate RO1 is uniformly determined to be about 17% as described above. In FIG. 5, the first extraction rate of the image quality B is set to 20%, but when the process color inks are four colors, the total of the "first dot group" of the four colors is only 80%. 1 Overlap rate RO1 is 0%.

Following the extraction of the "first dot group", the extraction of the "second dot group" is performed. There may be various relationships in the overlapping relationship between the "second dot group" and the "first dot group", but in the present embodiment, the extraction of the "second dot group" is the extraction of the "first dot group". It is done independently without considering the result. This is based on the finding that if the pattern of "dot group" extraction is made inconspicuous in each print layer, the pattern of "dot group" extraction is not conspicuous as a whole. The same applies to the "third dot group", and the extraction of the "third dot group" is performed independently for both the extraction of the "first dot group" and the extraction of the "second dot group". The above method is simple as a process while having a pattern suppressing effect, and the load related to the process is relatively small.

However, the extraction method of the "second dot group" and the "third dot group" is not limited to the above method, and for example, the following conditions may be added. That is, for the five points Do1 in which the ink dots are overlapped in the extraction of the "first dot group", a condition that the ink dots are not overlapped in the extraction of the "second dot group" may be added. According to this method, the effect of suppressing the pattern can be further expected. The same applies to the "third dot group", and in the extraction of the "third dot group", the overlapping points are extracted while avoiding both the overlapping points in the points Do1 and the "second dot group".

Hereinafter, in the printer 10 according to the present embodiment, the printing process after the formation positions of the “first dot group” to the “third dot group” are determined will be briefly described. The ink related to the "first dot group" of each ink is ejected from the nozzles 41, 51, 61, 71 of the first nozzle rows 42a, 52a, 62a, 72a of the ink heads 40, 50, 60, 70. As shown in FIG. 2, the four first nozzle rows 42a, 52a, 62a, 72a are provided on the upstream X1 side of the sub-scanning direction X in the nozzle rows 42, 52, 62, 72 to which they belong. ing. Further, the ink related to the "second dot group" of each ink is ejected from the nozzles 41, 51, 61, 71 of the second nozzle rows 42b, 52b, 62b, 72b of the ink heads 40, 50, 60, 70. To. The four second nozzle rows 42b, 52b, 62b, 72b are on the upstream X1 side of the sub-scanning direction X next to the first nozzle rows 42a, 52a, 62a, 72a in the nozzle rows 42, 52, 62, 72 to which they belong. It is provided in. Since the recording medium 5 is conveyed from the rear Rr toward the front F (from the upstream X1 side to the downstream X2 side in the sub-scanning direction X), the first nozzle rows 42a, 52a, 62a, 72a are second. It is always ahead of the nozzle rows 42b, 52b, 62b, 72b in the printing position. Therefore, the ink ejected from the nozzles of the first nozzle row 42a, 52a, 62a, 72a forms a print layer below the ink ejected from the nozzles of the second nozzle rows 42b, 52b, 62b, 72b, respectively. .. Similarly, the ink ejected from the nozzles of the second nozzle rows 42b, 52b, 62b, 72b has a print layer below the ink ejected from the nozzles of the third nozzle rows 42c, 52c, 62c, 72c, respectively. Form. The printer 10 according to the present embodiment intermittently repeats the above-mentioned printing in high-density printing. As a result, the printer 10 according to the present embodiment can perform high-density printing without returning the recording medium 5 to the upstream X1 side of the sub-scanning direction X.

In the present embodiment, the number of printing layers in high-density printing is three, but the number of printing layers is not limited to three. The number of printing layers in high-density printing may be two or four or more. Therefore, the number of divisions of the nozzle row may be two or four or more.

Further, the mask pattern that minimizes the overlap rate in each dot group is not limited to the above-mentioned mask pattern. For example, the ink dots of four colors may be extracted one point at a time in order.

(Second Embodiment)
The second embodiment is configured so that the overlap rate of each "dot group" can be set. In the first embodiment, the overlap rate of each "dot group" is automatically set to the minimum based on the extraction rate. However, the overlap rate "minimum" as described above is not always the optimum condition for all images. For example, in the printer 10 according to the first embodiment, in order to disperse the positions of "dot groups" of each ink as much as possible, an image having a partially different color balance from the original image may be formed. Therefore, in the second embodiment, the overlap rate of each "dot group" can be arbitrarily set. The printer according to the second embodiment is common to the printer 10 according to the first embodiment except for the above. Therefore, in the following description of the second embodiment, the same members as those of the first embodiment are designated by the same reference numerals, and duplicate description will be omitted or simplified.

FIG. 9 is a diagram showing an internal parameter setting screen for image quality according to the present embodiment. Also in the present embodiment, as in the first embodiment, the internal parameter setting screen of FIG. 9 is stored in an area that is not normally operated by the user, and the user selects the set image quality. However, this does not exclude other embodiments that the user can set and operate. The image quality setting screen of FIG. 9 is configured so that the first duplication rate RO1 to the third duplication rate RO3 can be set together with the first extraction rate RP1 to the third extraction rate RP3. The first duplication rate RO1 to the third duplication rate RO3 are set by the duplication rate setting unit 103b provided in the image quality setting unit 103.

For example, looking at the first extraction rate RP1 and the first overlap rate RO1, on the internal parameter setting screen of FIG. 9, after the first extraction rate RP1 is set, the first overlap rate RO1 is displayed in the input box of the first overlap rate. Entered. The first duplication rate RO1 that can be input at this time is equal to or greater than the minimum duplication rate calculated from the first extraction rate RP1. Also in FIG. 9, since the first extraction rate RP1 of the image quality A is 30%, the minimum first duplication rate is 17% as shown in the previous example. In the present embodiment, the value of the input box of the first duplication rate can be changed, and the first duplication rate RO1 can be set to an arbitrary rate of the minimum duplication rate (17% in this case) or more and 100% or less. When the overlap rate is set to 100%, the ink dots are extracted with a single mask as shown in FIG. 7. In FIG. 9, the first overlap rate RO1 = 60% is set.

Similar to the description of the first embodiment, if the above case is described by taking 100 points where all four colors of the process color ink are struck as an example, first, for each ink, the "first dot" of another color is described. 40% of the "first dot group" that does not overlap with the "group" is extracted. This is 12 ink dots for each ink. Therefore, a total of 48 points for the four colors are extracted as formation points of the "first dot group". Then, of the remaining 52 points, 18 points are extracted as points formed by overlapping all the "first dot groups" of the four colors.

The above-mentioned method for extracting "overlapping points" is the simplest method, but other methods may be used. For example, the 18 ink dots that overlap with the "first dot group" of the other three colors of ink are divided into three equal parts of six, and overlap with the ink dots of one of the other three colors. May be configured in. Since there are 6 combinations of 2 colors out of 4 colors, 6 × 6 = 36 points will be extracted by this. Therefore, in this case, a total of 84 points are extracted as the formation points of the "first dot group". FIG. 10 is a diagram showing a "first dot group" finally extracted by the above process. Also in FIG. 10, the same reference numerals and symbols as those in FIG. 6 are used. However, the first dot group Do1 is an ink dot formed by overlapping two color ink dots among the four color process color inks. The "first dot group" of FIG. 10 also has no pattern property as compared with that shown in FIG. 7.

As described above, the printer 10 according to the present embodiment can set a suitable mask pattern by adjusting the overlap ratio of each "dot group". Since the suitable mask pattern of each ink can change depending on the image, it is effective to adjust the overlap rate of each “dot group”. In the present embodiment, it is preferable that a plurality of image quality in which the extraction rate and the overlap rate of each "dot group" are adjusted are prepared in advance in the control device 100. As a matter of course, also in this embodiment, an image quality that minimizes the overlap rate of each "dot group" may be prepared.

The preferred embodiment of the present invention has been described above. However, the above embodiments are merely examples, and the present invention can be implemented in various other embodiments.

For example, in the above-described embodiment, the generation of patterns is suppressed by adjusting the overlap rate between the "dot groups" of each ink color, but the present invention is not limited to this. For example, each mask may simply have a different mask pattern. For example, one mask may be set with one systematic dither mask, another mask pattern may be set with another systematic dither mask, and the like. If the mask pattern of each color is different, it is considered that different patterns are generated in each color, and the patterns cancel each other out as a whole image, and the patterns cannot be confirmed. Alternatively, the masks do not have to be different from each other for the inks of all colors, for example, the same mask may be applied to the first ink and the second ink. Further, the mask pattern of each color may be set independently, and if it is a suitable condition, the same mask pattern may be used for all colors.

Further, in the above-described embodiment, the extraction rate of each ink related to one print layer is common. That is, the color balance of the original image was maintained even in the print layer unit. However, the extraction rate of each ink related to one print layer does not have to be common to all colors. For example, the extraction rate of each ink may be common only in the total extraction rate of all print layers. For example, cyan ink has a first extraction rate of 50%, a second extraction rate of 50%, a third extraction rate of 50% (total 150%), and magenta ink has a first extraction rate of 40%, a second extraction rate of 40%, and a second extraction rate. 3 Extraction rate is set to 70% (total 150%). If the total extraction rate is common to each color ink, the color balance of the original image can be maintained. Furthermore, the total extraction rate does not necessarily have to be the same for each color ink. The present invention does not exclude embodiments in which the tint is adjusted by making the total extraction rate different depending on the color.

In the above-described embodiment, the extraction of "dot groups" in the plurality of print layers is independent of each other. However, the overlapping relationship between a plurality of "dot groups" is not limited to the above. For example, extraction may be performed so as to avoid duplication of ink dots of the same color between one print layer and another print layer. According to such extraction, the print image quality can be further improved. However, since it is not preferable to overlap ink dots of different colors more than a certain amount in the same print layer, it is preferable to balance the two. For that purpose, for example, the extraction position for each color is avoided while avoiding the overlap of the position with the ink dots of the same color on another print layer and the overlap of the positions with the ink dots of other colors on the same print layer. (A method similar to the method for extracting the "first dot group" in the first printing layer of the first embodiment) may be adopted. Further, for example, a method may be adopted in which the extraction position is determined one point at a time (or a plurality of points) while changing the colors to be extracted alternately. The latter is a method in which, for example, the positions are determined in the order of cyan, magenta, yellow, and black by a predetermined number of points, and the same procedure is repeated from cyan again. Further, since the total number of ink dots differs depending on the color, the number of points to be determined at one time may be proportional to the total number of ink dots.

In the above-described embodiment, printing is performed by so-called single-pass printing. Single-pass printing is a printing method that completes printing of one print area in one scan. In the case of high-density printing, the print area exists for each of the plurality of print layers. However, the present invention may be carried out by so-called multipath printing. Multi-pass printing is a printing method that completes printing of one printing area by scanning a plurality of times.

In the above-described embodiment, the nozzle rows 42 to 72 of the ink heads 40 to 70 are each divided into a plurality of partial nozzle rows arranged in the sub-scanning direction X. However, the nozzle rows 42 to 72 of the ink heads 40 to 70 do not necessarily have to be divided, and printing of the plurality of print layers may be performed separately as a separate process.

In the above-described embodiment, the plurality of inks are ejected from different ink heads, but the ink is not limited thereto. One ink head includes a plurality of nozzle rows, and a plurality of inks may be ejected from one ink head. The "recording head" in the present invention includes such a case.

In the above-described embodiment, the method of ejecting ink is a method of changing the volume of the pressure chamber by displacement of the piezoelectric element, a so-called piezo drive method. However, the ink ejection method of the printer according to the present invention may be, for example, various continuous methods such as a binary deflection method or a continuous deflection method, and various on-demand methods such as a thermal method. The ink ejection method according to the present invention is not limited.

In the above embodiment, the carriage 25 is configured to move in the main scanning direction Y, and the recording medium 5 is configured to move in the sub-scanning direction X, but the present invention is not limited to this. The movement of the carriage 25 and the recording medium 5 is relative, and either of them may move in the main scanning direction Y or the sub-scanning direction X. For example, the recording medium 5 may be arranged immovably, and the carriage 25 may be configured to be movable in both the main scanning direction Y and the sub-scanning direction X. Further, both the carriage 25 and the recording medium 5 may be configured to be movable in both directions.

In addition, the techniques disclosed herein can be applied to various types of inkjet printers. In addition to the so-called Roll-to-Roll type printer that conveys the roll-shaped recording medium 5 shown in the above embodiment, it can be similarly applied to, for example, a flatbed type inkjet printer. Further, the printer 10 is not limited to the one used independently as an independent printer, and may be a combination with another device. For example, the printer 10 may be built in another device.

5 Recording medium 10 Printer (inkjet printer)
40 1st ink head 41 Nozzle (1st nozzle)
42a 1st nozzle row 42b 2nd nozzle row 42c 3rd nozzle row 50 2nd ink head 60 3rd ink head 70 4th ink head 100 Control device 110 High density print control unit 110a 1st print control unit 110b 2nd print control Unit 110c Third print control unit 120 Extraction unit 121 First extraction unit 121a First extraction unit (first extraction unit of the first ink)
121b 1-2 extraction unit (second extraction unit of the first ink)
121c 1st-3rd extraction part (3rd extraction part of 1st ink)
122 2nd extraction unit 123 3rd extraction unit 124 4th extraction unit Dc1 Cyan ink 1st dot group Dm1 Magenta ink 1st dot group Dy1 Yellow ink 1st dot group Dk1 Black ink 1st dot group

Claims (7)

A first ink head having a plurality of first nozzles for ejecting the first ink toward the recording medium and forming ink dots of the first ink on the recording medium, and a first ink head.
A second ink head provided with a plurality of second nozzles for ejecting the second ink toward the recording medium and forming ink dots of the second ink on the recording medium, and a second ink head.
With a recording head, including
The m extraction units (m is a natural number of 2 or more) from the first extraction unit to the m extraction unit and the m print layers from the first print layer to the m print layer are controlled by controlling the recording head. A control device having m print control units from the first print control unit to the m-th print control unit formed on the recording medium in an overlapping manner.
Equipped with
The nth extraction unit (n is all natural numbers less than or equal to m) is
An nth extraction unit of the first ink that receives the ink dot data of the first ink and extracts the nth dot group of the first ink consisting of a part or all of the ink dots of the first ink.
It is provided with an n-second extraction unit of a second ink that receives data of ink dots of the second ink and extracts an n-dot group of the second ink composed of a part or all of the ink dots of the second ink.
The nth extraction unit of the first ink extracts the nth dot group of the first ink from the ink dots of the first ink by the mask in which the nth mask pattern of the first ink is set.
The nth extraction unit of the second ink extracts the nth dot group of the second ink from the ink dots of the second ink by the mask in which the nth mask pattern of the second ink is set.
The nth mask pattern of the first ink is a mask pattern that extracts a part of the ink dots of the first ink as the nth dot group of the first ink.
The nth mask pattern of the second ink is such that at least a part of the ink dots in the nth dot group of the second ink is formed at a position different from the nth dot group of the first ink. This is a mask pattern for extracting the nth dot group of the second ink.
The dot group of each first ink from the first dot group of the first ink to the m dot group of the first ink includes all the ink dots of the first ink, and at least a part of the ink dots. Configured to overlap,
The dot group of each second ink from the first dot group of the second ink to the m dot group of the second ink includes all the ink dots of the second ink, and at least a part of the ink dots. Configured to overlap,
The nth print control unit forms an nth print layer composed of ink dots including at least the nth dot group of the first ink and the nth dot group of the second ink .
The qth dot group of the first ink (q is a natural number of m or less) and the q dot group of the second ink include ink dots whose positions overlap, and the r dot group of the first ink (r is q). When the r-dot group of the second ink contains ink dots whose positions overlap each other, the r-dot group of the first ink and the r-dot group of the second ink overlap each other. The ink dots are formed at positions different from the ink dots overlapping in the q-dot group of the first ink and the q-dot group of the second ink.
Inkjet printer. The second p-mask pattern of the second ink (p is a natural number of m or less) extracts the second p-dot group of the second ink so that the overlap of the position with the first p-dot group of the first ink is minimized. Is a mask pattern to do,
The inkjet printer according to claim 1 . The second p-mask pattern of the second ink (p is a natural number of m or less) is the second p-dot of the second ink so that the overlap of the position with the first p-dot group of the first ink has a predetermined overlap ratio. A mask pattern that extracts groups,
The inkjet printer according to claim 1 . In the nth mask pattern of the first ink, the nth extraction rate of the first ink, which is the ratio of the nth dot group of the first ink to the ink dots of the first ink, is set.
In the n-mask pattern of the second ink, the n-th extraction rate of the second ink, which is the ratio of the n-dot group of the second ink to the ink dots of the second ink, is set.
The total from the first extraction rate to the m extraction rate of the first ink and the total from the first extraction rate to the m extraction rate of the second ink are the same.
The inkjet printer according to any one of claims 1 to 3 . The nth extraction rate of the first ink and the nth extraction rate of the second ink are the same extraction rate.
The inkjet printer according to claim 4 . The overlap of positions between the s dot group of the first ink (s is a natural number of m or less) and the t dot group of the first ink (t is a natural number of m or less different from s) is minimized. Extracted,
The second s dot group of the second ink and the t dot group of the second ink are extracted so that the overlap of positions is minimized.
The inkjet printer according to any one of claims 1 to 5 . A sub-scanning direction moving device for moving the recording medium in the sub-scanning direction with respect to the recording head is provided.
The first ink head has the same number of the first nozzles and is arranged in order from the upstream side to the downstream side in the sub-scanning direction from the first nozzle row of the first ink to the m nozzle row of the first ink. Equipped with a row of m first ink nozzles
The second ink head has the same number of the second nozzles as the nozzle rows of the first inks, and is arranged from the first nozzle row of the second inks arranged in order from the upstream side to the downstream side in the sub-scanning direction. Equipped with m nozzle rows of the second ink up to the m nozzle row of the second ink,
The n-th print control unit ejects the first ink from the first nozzle in the n-nozzle row of the first ink and ejects the second ink from the second nozzle in the n-nozzle row of the second ink. After the formation, the sub-scanning direction moving device is controlled to move the recording medium to the downstream side in the sub-scanning direction.
The inkjet printer according to any one of claims 1 to 6 .

Images