JP7073992B2 - Printing equipment, printing method, and image processing equipment - Google Patents

Description

The present invention relates to a printing apparatus, a printing method, and an image processing apparatus.

An inkjet printer as a printing device, for example, moves a print head having a plurality of nozzles arranged in a predetermined nozzle arrangement direction and a printed matter relative to each other in a relative movement direction intersecting the nozzle arrangement direction, and follows the print data. Ink droplets are ejected from the nozzle to form dots on the printed material. The arrangement direction of the nozzles is the direction in which a plurality of nozzles forming a nozzle row are arranged. Further, in order to perform printing at a high speed, the printed matter is conveyed to form a printed image without moving the print head provided with the nozzles arranged over almost the entire area of the printed matter in the width direction intersecting the conveying direction of the printed matter. Line head type inkjet printers are also known. Hereinafter, the line head type inkjet printer is referred to as a line printer. Since the nozzles are arranged almost all over the width direction of the printed matter, some line printers include a print head in which a plurality of head chips having a nozzle row whose nozzle arrangement direction is the width direction of the printed matter are combined.

For example, a head chip in which nozzle rows of cyan (C), magenta (M), yellow (Y), and black (K) are arranged in the transport direction is combined in the transport direction and the width direction of the printed matter. When the nozzles are arranged over the entire width direction, it is necessary to arrange at least two head chips in the transport direction in the print head in order to overlap a part of the nozzles. If each head chip has four rows of nozzles in the transport direction, the print head becomes long in the transport direction, and the landing position of the ink droplets tends to vary. In addition, the printed matter is likely to come into contact with the print head. Therefore, for example, in each head chip, the nozzle row of C and the nozzle row of Y are arranged in the nozzle arrangement direction which is the width direction of the object to be printed, and the nozzle arrangement of M and the nozzle arrangement of K are arranged in the nozzle arrangement direction. It is conceivable to line up in. That is, by arranging the four nozzle rows in two rows and two columns, the number of nozzle rows along the transport direction can be reduced to two rows. For example, Patent Document 1 discloses a head body in which a nozzle row of C and a nozzle row of Y are arranged in the arrangement direction of nozzles, and a nozzle row of M and a nozzle row of K are arranged in the arrangement direction of nozzles. Has been done.

Japanese Unexamined Patent Publication No. 2015-131447

However, in a print head in which the head body described in Patent Document 1 is used as a head chip in the transport direction and the width direction of the object to be printed, it is used when a secondary color is formed by ink droplets ejected from two nozzle rows. There is a problem that streaks and color unevenness along the transport direction are likely to occur depending on the arrangement position of the nozzle rows. When printing a secondary color using two nozzle rows in which the positions of the nozzle rows are shifted in the nozzle arrangement direction in the head chip, it is necessary to eject ink droplets from different head chips. Therefore, the head tips that can be used differ depending on the position in the arrangement direction of the nozzles, and the distance between the nozzles that can be ejected on the same line along the transport direction differs. When the distance between the nozzles is different, the time from the first ink droplet landing on the printed matter to the next ink droplet landing is different. As a result, there may be a difference in the color development of the secondary color depending on the distance between the nozzles, and streaks and color unevenness along the nozzle arrangement direction may occur. The above-mentioned problems also occur in a serial-type inkjet printer using a print head in which similar head chips are combined.

The printing apparatus of the present application is a printing apparatus in which a print head and an object to be printed move relative to each other in a relative movement direction different from the direction in which the nozzles of the nozzle row are arranged, and the print head is a first nozzle row and a second nozzle row. , And the number of the first nozzle row, the second nozzle row, and the third nozzle row is 2 or more, and ink droplets are formed on the same line along the relative movement direction. Of the plurality of nozzle rows for ejecting ink, the distance between the first nozzle row and the second nozzle row in the relative movement direction is constant, and the first nozzle row and the third nozzle row in the relative movement direction are constant. There are a plurality of distances from the ink droplets, and the first ink droplets when printing a secondary color by the first ink droplets ejected from the first nozzle row and the third ink droplets ejected from the third nozzle row. And when the overlapping ratio of the third ink droplets is set to X% and the secondary color is printed by the first ink droplets ejected from the first nozzle row and the second ink droplets ejected from the second nozzle row. When the overlapping ratio of the first ink droplet and the second ink droplet is Y%, the first printing satisfying the condition of X <Y is performed.

In the above printing apparatus, the plurality of dither mask thresholds for determining printing with the third ink droplet complement each other with the plurality of dither mask thresholds for determining printing with the first ink droplet. It is preferable to meet.

In the above printing apparatus, the print head includes a plurality of head chips having the first nozzle row, the second nozzle row, and the third nozzle row, and in the head chip, the first nozzle row and the like. The second nozzle row is arranged in the relative movement direction, and one of the first nozzle row and the second nozzle row and the third nozzle row are arranged in the arrangement direction of the nozzles. It is preferable to have.

In the above printing apparatus, it is preferable that the head chip further has a fourth nozzle row, and the third nozzle row and the fourth nozzle row are arranged in the relative movement direction.

In the above printing apparatus, the length of the print head in the relative moving direction is preferably three times the length of the head chip in the relative moving direction.

In the above printing apparatus, the colors of the first ink droplet, the second ink droplet, and the third ink droplet are different, and is preferably selected from cyan, magenta, and yellow.

It is preferable that the printing apparatus includes a selective printing unit that selectively performs a plurality of printing including the first printing and the second printing satisfying X = Y.

The printing apparatus includes a printed matter type selection unit that accepts selection of the type of printed matter to be used for printing, and the selective printing unit is first limited to the type of printed matter received by the printed matter type selection unit. When the first type is printed and the type of the printed matter received by the printed matter type selection unit is the second type which is easier to dry than the first type, the second type is printed. It is preferable to print.

The printing apparatus includes a temperature sensor that detects a temperature, and the selective printing unit performs the first printing when the temperature detected by the temperature sensor satisfies the first temperature condition, and the first printing is performed. It is preferable to perform the second printing when the second temperature condition higher than the temperature condition of the above is satisfied.

The printing device includes a humidity sensor for detecting humidity, and the selective printing unit performs the first printing when the humidity detected by the humidity sensor satisfies the first humidity condition, and the first printing is performed. It is preferable to perform the second printing when the second humidity condition lower than the humidity condition of the above is satisfied.

The printing method of the present application is a printing method in which the print head and the object to be printed move relative to each other in a relative movement direction different from the arrangement direction of the nozzles in the nozzle row, and the print head is a first nozzle row and a second nozzle row. , And the number of the first nozzle row, the second nozzle row, and the third nozzle row is 2 or more, and ink droplets are formed on the same line along the relative movement direction. Of the plurality of nozzle rows for ejecting ink, the distance between the first nozzle row and the second nozzle row in the relative movement direction is constant, and the first nozzle row and the third nozzle row in the relative movement direction are constant. There are a plurality of distances from the ink droplets, and the first ink droplets when printing a secondary color by the first ink droplets ejected from the first nozzle row and the third ink droplets ejected from the third nozzle row. And when the overlapping ratio of the third ink droplets is set to X% and the secondary color is printed by the first ink droplets ejected from the first nozzle row and the second ink droplets ejected from the second nozzle row. When the overlapping ratio of the first ink droplet and the second ink droplet is Y%, the first printing satisfying the condition of X <Y is performed.

The image processing apparatus of the present application has a first nozzle row, a second nozzle row, and a third nozzle row, and the number of the first nozzle row, the second nozzle row, and the third nozzle row is two or more. Of the plurality of nozzle rows that eject ink droplets on the same line along a relative movement direction different from the nozzle arrangement direction of the nozzle row, the first nozzle row and the second nozzle in the relative movement direction. The print data for a printing device provided with a print head having a constant distance from the row and having a plurality of distances between the first nozzle row and the third nozzle row in the relative movement direction is used as image data. An image processing device that is generated based on the above, and includes a halftone processing unit that performs halftone processing based on the image data, and the halftone processing unit includes a first ink droplet to be ejected from the first nozzle row. The overlapping ratio of the first ink droplets and the third ink droplets when printing the secondary color with the third ink droplets ejected from the third nozzle row is set to X%, and the first ink droplets are ejected from the first nozzle row. When the overlapping ratio of the first ink droplet and the second ink droplet when printing the secondary color by the first ink droplet and the second ink droplet ejected from the second nozzle row is set to Y%, It is characterized in that halftone processing satisfying the condition of X <Y is performed.

The figure which shows typically the structural example of the printing apparatus which concerns on embodiment. The figure which schematically exemplifies the main part of a line printer. The figure which schematically exemplifies a head tip. The figure explaining an example of the dither mask A. The figure explaining an example of the output color data after a color conversion process. The figure explaining an example of print data after halftone processing using dither mask A. The figure explaining an example of the dither mask B. The figure explaining an example of print data after halftone processing using dither mask B. The figure explaining an example of print data after halftone processing using dither mask A. The figure explaining an example of print data after halftone processing using dither mask A'. The figure explaining an example of print data after halftone processing using dither mask B. The figure explaining the first printing. A flowchart illustrating a printing method of the first printing. The figure explaining the second printing. A flowchart illustrating a printing method for selectively performing the first printing and the second printing based on the type of printed matter. A flowchart illustrating a printing method for selectively performing the first printing and the second printing based on the temperature. A flowchart illustrating a printing method for selectively performing the first printing and the second printing based on humidity. The figure which schematically exemplifies the print head which concerns on the modification. The figure which schematically exemplifies the state when the secondary color is printed by the 1st nozzle row and the 3rd nozzle row in the line where the distance between nozzles is short. The figure which schematically exemplifies the state when the secondary color is printed by the 1st nozzle row and the 3rd nozzle row in the line where the distance between nozzles is long. The figure which schematically exemplifies the streak and color unevenness which occur when the secondary color is printed in the 1st nozzle row and the 3rd nozzle row where there are a plurality of distances between nozzles in the prior art.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment)
<Specific example of a printing device including an image processing device>
FIG. 1 schematically shows a configuration example of a printing apparatus according to an embodiment. The printing device 1 shown in FIG. 1 includes an image processing device 3. The printing device 1 shown in FIG. 1 is represented as a printing system (printing device in a broad sense) including components of the present technology, includes at least an inkjet printer 2 in a narrow sense as a sales unit, and includes a host device 100 and the like. You may. Further, the printing device 1 may have a configuration in which the image processing device 3 is independent of the inkjet printer 2, or a configuration in which another device has a part or all of the functions of the image processing device 3. FIG. 1 shows a configuration example of a line printer as the inkjet printer 2. The printing apparatus to which this technique can be applied may include a copying machine, a facsimile, a multifunction device having these functions, and the like. The ink used in the inkjet printer 2 for forming a color image includes, for example, cyan (C), magenta (M), yellow (Y), and black (K) inks. Of course, the inks are also light cyan (Lc), light magenta (Lm), dark yellow (Dy), light black (Lk), red (R), orange (Or), green (G), and for improving image quality. Non-colored ink, etc. may be included.

FIG. 2 schematically illustrates a main part of the inkjet printer 2. FIG. 3 schematically illustrates the head tip 61. In FIGS. 2 and 3, the print head 60 is shown from the side opposite to the nozzle surface where the nozzle 64 is located, but for convenience, the position of the nozzle 64 is shown, and ink droplets 67 of C, M, Y, or K are shown. The ejection nozzle 64 is represented by a color-coded pattern of ink droplets 67.
The inkjet printer 2 has a line head which is a print head 60 in which a plurality of head chips 61 are combined, and the print head 60 does not move when the ink droplet 67 is ejected to form the dot DT0, and the long printed matter ME1 Moves. A printed matter (print substrate) is a material that holds a printed image, and is at least all types of paper / paperboard and processed products described in JIS (Japanese Industrial Standards) P0001: 1998 (paper / paperboard and pulp terms). including. Resin sheets, metal plates, three-dimensional objects, etc. are also included in the printed matter.

In FIG. 2, reference numeral D1 is an arrangement direction of nozzles 64, reference numeral D2 is a relative movement direction between the print head 60 and the printed matter ME1, reference numeral D21 is a paper feed direction, and reference numeral D3 is a width direction of a long printed matter ME1. Shows. The relative moving direction D2 is also referred to as a scanning direction. In the inkjet printer 2, the print head 60 and the printed matter ME1 move relative to each other in a relative moving direction D2 different from the nozzle arrangement direction D1 of the nozzle rows NL1 to NL4. The nozzle row is a row composed of a plurality of nozzles for ejecting ink droplets 67 of the same type, and the nozzle arrangement direction D1 is a direction in which a plurality of nozzles forming one nozzle array are arranged. When the printed matter ME1 moves from the upstream side in the transport direction to the downstream side in the transport direction with respect to the fixed print head 60, the printed matter ME1 is ejected from the nozzle 64 in order from the downstream side in the transport direction to the upstream side in the transport direction. The ink droplet 67 forms a line DL of dot DT0. In the example of FIG. 2, the arrangement direction D1 and the width direction D3 coincide with each other, but the arrangement direction D1 and the width direction D3 may be deviated by approximately 45 ° or the like. These directions D1 and D3 and the paper feed direction D21 (relative movement direction D2) may be different directions, and the present invention may not only be orthogonal to each other but also intersect each other at approximately 45 ° so as not to be orthogonal to each other. include. Of course, the intersection of two directions means that the two directions are out of alignment, including being orthogonal. The print head 60 and the dot DT0 shown in FIGS. For example, the number of head chips 61 included in the print head 60 is not limited to 6 as shown in FIG. 2, and may be 3 or more and 5 or less, or 7 or more. The number of nozzle rows 68 included in the head chip 61 is not limited to four rows, and may be three or less rows or five or more rows. The number of nozzles included in the nozzle row 68 is an example and is not limited to 10.

As shown in FIGS. 2 and 3, the print head 60 includes a plurality of head tips 61 having a first nozzle row NL1, a second nozzle row NL2, a third nozzle row NL3, and a fourth nozzle row NL4. There is. In other words, the print head 60 has two or more first nozzle rows NL1, two or more second nozzle rows NL2, two or more third nozzle rows NL3, and two or more fourth nozzle rows NL4. .. The first nozzle row NL1 ejects the first ink droplet, the second nozzle row NL2 ejects the second ink droplet, the third nozzle row NL3 ejects the third ink droplet, and the fourth nozzle row NL4 ejects the fourth ink droplet. Ink droplets are ejected.

The colors of the first ink droplet, the second ink droplet, and the third ink droplet are different, and are selected from cyan (C), magenta (M), and yellow (Y). In this embodiment, the configuration in which the first ink droplet corresponds to C ink, the second ink droplet corresponds to M ink, and the third ink droplet corresponds to Y ink is exemplified. Further, the fourth ink droplet corresponds to K ink. Hereinafter, when each nozzle row 68 is distinguished by the color of the ink to be ejected, the first nozzle row NL1 is the nozzle row 68C, the second nozzle row NL2 is the nozzle row 68M, and the third nozzle row NL3 is the nozzle row 68Y, the fourth. The nozzle row NL4 is called a nozzle row 68K. Further, the nozzle 64 for ejecting C ink is referred to as nozzle 64C, the nozzle 64 for ejecting M ink is referred to as nozzle 64M, the nozzle 64 for ejecting Y ink is referred to as nozzle 64Y, and the nozzle 64 for ejecting K ink is referred to as nozzle 64K.

In each head tip 61, the first nozzle row NL1 and the second nozzle row NL2 are arranged in the relative moving direction D2. One of the first nozzle row NL1 and the second nozzle row NL2 and the third nozzle row NL3 are arranged in the nozzle arrangement direction D1. In the present embodiment, the first nozzle row NL1 and the third nozzle row NL3 are lined up in the line-up direction D1. According to this configuration, the length of the print head 60 in the relative moving direction D2 can be shortened as compared with the configuration in which the first to third nozzle rows NL1 to NL3 are arranged in the relative moving direction D2. As a result, the landing position of the ink droplet 67 is less likely to vary, and the printed matter ME1 is less likely to come into contact with the print head 60.

In the present embodiment, the third nozzle row NL3 and the fourth nozzle row NL4 are further arranged in the relative moving direction D2. According to this configuration, the length of the print head 60 in the relative moving direction can be shortened as compared with the configuration in which the first to fourth nozzle rows NL1 to NL4 are arranged in the relative moving direction D2.

The print head 60 has a plurality of head chips so that dots DT0 can be formed on the printed matter ME1 by ink droplets 67 ejected from nozzles 64C, 64M, 64Y, 64K over the entire width direction D3 of the printed matter ME1. 61a, 61b, 61c, 61a, 61b, 61c are arranged. Here, the head tips 61a to 61c are collectively referred to as the head tip 61, the nozzle rows 68C, 68M, 68Y, 68K are collectively referred to as the nozzle row 68, and the nozzles 64C, 64M, 64Y, 64K are collectively referred to as the nozzle 64.

Even if the nozzles for ejecting the same type of ink droplets 67 are arranged in a staggered pattern, a plurality of nozzles are arranged in a predetermined arrangement direction different from the relative movement direction, for example, in two rows. Included in this technology. The alignment direction in this case means the alignment direction of the nozzles in each row in the staggered arrangement.

As shown in FIG. 3, a plurality of nozzles 64 are arranged in each nozzle row 68 at intervals of nozzle pitch Np in the arrangement direction D1. While the nozzle pitch Np is very small in order to realize the high-resolution printed image IM1, it is necessary to form the flow path of the ink 66 up to the nozzle 64 on the head chip 61. Therefore, it is not easy to form nozzles 64 at both ends of the head tip 61 in the alignment direction D1 at intervals of the nozzle pitch Np. When nozzles 64 having a nozzle pitch Np interval cannot be formed at both ends of the head tip 61, non-ejection regions A1 are generated at both ends of the head tip 61. Further, since it is necessary to form the flow path of the ink 66 for each color in the arrangement direction D1, it is easy to form the nozzle 64 between the nozzle rows 68C and 68M and the nozzle rows 68Y and 68K at the interval of the nozzle pitch Np. is not. When the nozzles 64 having a nozzle pitch Np interval cannot be formed between the nozzle rows 68C and 68M and the nozzle rows 68Y and 68K, a non-ejection region A2 is generated between them.

When non-ejection regions A1 and A2 without nozzles 64 occur in the head chip 61 in the alignment direction D1, as shown in FIG. 2, in order to arrange the CMYK nozzles 64 on the same line DL, the head chips 61 are relatively moved. It is necessary to arrange at least three in the direction D2. In the present embodiment, the length La of the print head 60 in the relative moving direction D2 is three times the length Lb of the head chip 61 in the relative moving direction D2. As a result, the length La of the print head 60 in the relative moving direction D2 becomes the shortest, the landing position of the ink droplet 67 is less likely to vary, and the printed matter ME1 is less likely to come into contact with the print head 60.
A line capable of landing the first ink droplet ejected from the first nozzle row NL1 and the third ink droplet ejected from the third nozzle row NL3 on the same line DL along the relative moving direction D2. The nozzles can be arranged continuously in the arrangement direction D1.
Further, a line capable of landing the second ink droplet discharged from the second nozzle row NL2 and the third ink droplet discharged from the third nozzle row NL3 on the same line DL along the relative moving direction D2. Can be continuously arranged in the arrangement direction D1 of the nozzles.

Since the print head 60 has non-ejection regions A1 and A2, the distance between the nozzles in the relative movement direction D2 differs depending on the combination of the nozzle rows 68C, 68M, 68Y, 68K according to the print regions AL1 to AL6. Sometimes. For example, among a plurality of nozzle rows 68 that eject ink droplets 67 in the same line DL along the relative movement direction D2, the nozzle row 68C (first nozzle row NL1) and the nozzle row 68M (second nozzle) in the relative movement direction D2. The distance between the nozzles in the row NL2) is a constant distance L0 on all lines DL1 to DL6.

The distance between the nozzles 68C (first nozzle row NL1) and the nozzle row 68Y (third nozzle row NL3) in the relative moving direction D2 has a plurality of distances L1 and L2. Specifically, the distance between the nozzles of the nozzle rows 68C and 68Y in the lines DL1 and DL3 is the distance L1, and the distance between the nozzles of the nozzle rows 68C and 68Y in the line DL2 is the distance L2 (L2> L1). Further, the distance between the nozzles of the nozzle rows 68C and 68Y in the lines DL4 and DL6 is the distance L1, but the ejection order of the ink droplets 67 is opposite to that in the case of the lines DL1 and DL3, and the nozzle rows 68C and 68Y in the line DL5. The distance between the nozzles is the distance L2, but the ejection order of the ink droplets 67 is opposite to that of the line DL2. Further, the distance between the nozzles of the nozzle row 68M (second nozzle row NL2) and the nozzle row 68Y (third nozzle row NL3) also has a plurality of distances L1 and L2. The print areas AL1, AL2, AL3, AL4, AL5, AL6 are print areas having the same ink droplet ejection timing as the lines DL1, DL2, DL3, DL4, DL5, DL6, respectively.

Next, the configuration of the printing apparatus 1 shown in FIG. 1 will be described. The inkjet printer 2 shown in FIG. 1 includes a controller 10, a RAM (Random Access Memory) 20, a non-volatile memory 30, a mechanism unit 50, a card interface (I / F) 71, a communication interface (I / F) 72, and an operation panel 73. , A temperature sensor SE1 for detecting temperature T, a humidity sensor SE2 for detecting humidity H, and the like. The controller 10, the RAM 20, the non-volatile memory 30, each I / F 71, 72, and the operation panel 73 are capable of inputting / outputting information to each other. The temperature sensor SE1 and the humidity sensor SE2 are connected to the controller 10.

The controller 10 has a function of an image processing device 3 including a CPU (Central Processing Unit) 11, a resolution conversion unit 41, a color conversion unit 42, a halftone processing unit 43, a signal transmission unit 44, and the like. The image processing device 3 generates the print data DA3 of the inkjet printer 2 based on the image data. The function of the image processing device 3 may be realized in the host device 100 at least a part or all of them. The controller 10 can be configured by a SoC (System on a Chip) or the like.
The CPU 11 is a device that mainly performs information processing and control in the inkjet printer 2.

The resolution conversion unit 41 converts the input color data DA1 obtained by converting the resolution of the image data obtained from the host device 100, the memory card 90, etc. into the print resolution (for example, 720 × 720 dpi or 360 × 360 dpi) when printing on the printed matter ME1. Generate. The obtained image data is represented by, for example, RGB data having an integer value of 256 gradations of RGB (red, grain, and blue) in each pixel. If the obtained image data is not RGB data, the image data may be converted into RGB data.

The color conversion unit 42 is, for example, CMYK data having an input color data DA1 which is RGB data as a print resolution and having an integer value of 256 gradations of CMYK (cyan, magenta, yellow, and black) in each pixel. Color conversion processing is performed on the output color data DA2. At that time, the color conversion unit 42 converts the input color data DA1 into the output color data DA2 based on the color conversion look-up table LUT in which the gradation value of the RGB data and the gradation value of the CMYK color system data are associated with each other. ..

The halftone processing unit 43 performs halftone processing based on the output color data DA2 as color-converted image data. The halftone processing unit 43 performs predetermined halftone processing such as a dither method, an error diffusion method, or a density pattern method on the gradation value (ink amount data) of each pixel constituting the output color data DA2 to perform gradation. The number of gradations of the value is reduced to generate print data DA3. The print data DA3 is data representing a dot formation state of each pixel corresponding to the print image IM1, and can be, for example, binary data indicating the presence or absence of dot formation of each pixel. Further, the print data DA3 is the third floor capable of dealing with dots of different sizes, such as 0 without dots, 1 for small dot formation, 2 for medium dot formation, and quaternary data corresponding to 3 for large dot formation. Multi-valued data above the key may be used.
The signal transmission unit 44 generates a drive signal SG corresponding to the voltage signal applied to the drive element 63 of the head chip 61 based on the print data DA3, and outputs the drive signal SG to the drive circuit 62. If necessary, the print data DA3 may be rearranged in the order in which dots are formed by the mechanism unit 50.

Each of the above parts 41 to 44 may be configured by an ASIC (Application Specific Integrated Circuit), and the data to be processed may be directly read from the RAM 20 or the processed data may be directly written to the RAM 20.

The mechanism unit 50 is controlled by the controller 10. The mechanism unit 50 includes a paper feed mechanism 53 and the like. The paper feed mechanism 53 conveys the printed matter ME1 in the paper feed direction D21. The print head 60 is equipped with, for example, a head chip 61 that ejects ink droplets 67 of CMYK. The head chip 61 includes a drive circuit 62, a drive element 63, and the like. The drive circuit 62 applies a voltage signal to the drive element 63 according to the drive signal SG input from the controller 10. As the drive element 63, a piezoelectric element that applies pressure to the ink 66 in the pressure chamber communicating with the nozzle 64, a bubble generation element that generates bubbles in the pressure chamber by heat and ejects ink droplets 67 from the nozzle 64, and the like are used. Can be done. Ink 66 is supplied from the ink cartridge 65 to the pressure chamber of the head chip 61. The combination of the ink cartridge 65 and the head chip 61 is provided in each of the CMYK, for example. The ink 66 in the pressure chamber is ejected as ink droplets 67 from the nozzle 64 toward the printed matter ME1 by the driving element 63, and dots DT0 of the ink droplets 67 are formed on the printed matter ME1 such as printing paper. A printed image IM1 formed by a plurality of dots DT0 is formed on the printed matter ME1.

The RAM 20 stores a program PRG2 or the like that enables the printing device 1 to perform functions such as the selective printing unit U1 and the printed matter type selection unit U2.
The non-volatile memory 30 stores the program data PRG1 expanded in the RAM 20, the color conversion look-up table LUT, and the like. As the non-volatile memory 30, a ROM (Read Only Memory), a flash memory, a magnetic recording medium such as a hard disk, or the like is used. Expanding the program data PRG1 means writing to the RAM 20 as a program PRG2 that can be interpreted by the CPU 11.

The card I / F 71 is a circuit for writing data to the memory card 90 and reading data from the memory card 90.
The communication I / F 72 is connected to the communication I / F 172 of the host device 100, and inputs / outputs information to / from the host device 100. A display device 174 or the like may be connected to the host device 100. As the host device 100, a personal computer, a tablet terminal, a digital camera, a digital video camera, a smartphone, or the like can be used.

The operation panel 73 has an output unit 74, an input unit 75, and the like, and the user can input various instructions to the inkjet printer 2. The output unit 74 is composed of, for example, a liquid crystal panel (display unit) that displays information according to various instructions and information indicating the state of the inkjet printer 2. The output unit 74 may output these information by voice. The input unit 75 is composed of operation keys (operation input units) such as cursor keys and decision keys, for example. The input unit 75 may be a touch panel or the like that accepts operations on the display screen.

Here, streaks and color unevenness that occur when printing by the conventional technique is performed by the print head 60 will be described.
FIG. 19 is a diagram schematically illustrating a state in which a secondary color is printed by a first nozzle row and a third nozzle row on the line DL1 in which the distance between the nozzles is short. FIG. 20 is a diagram schematically illustrating a state in which a secondary color is printed by a first nozzle row and a third nozzle row on a line DL2 having a long distance between nozzles. FIG. 21 is a diagram schematically illustrating streaks and color unevenness that occur when a secondary color is printed between a first nozzle row and a third nozzle row, which have a plurality of distances between nozzles in the prior art.

As shown in FIG. 19, in the case of the line DL1 in which the distance between the nozzles is short, the ink droplet 67Y is ejected from the nozzle 64Y of the third nozzle row NL3 (nozzle row 68Y) and lands on a predetermined pixel. The printed matter ME1 is conveyed to the paper feed direction D21 for a distance L1 minutes. Ink droplets 67C are ejected from the nozzle 64C of the first nozzle row NL1 (nozzle row 68C) and land on the same pixel in duplicate. When the distance between the nozzles is short, the time from the landing of the preceding ink droplet 67Y to the landing of the succeeding ink droplet 67C is short. Since the ink droplet 67C lands before the ink droplet 67Y dries, if the ink droplet 67Y and the ink droplet 67C overlap, the inks tend to bleed from each other.

As shown in FIG. 20, in the case of the line DL2 in which the distance between the nozzles is long, the ink droplet 67Y is ejected from the nozzle 64Y of the nozzle row 68Y and lands on a predetermined pixel. The printed matter ME1 is conveyed to the paper feed direction D21 for a distance of L2 minutes. Ink droplets 67C are ejected from the nozzles 64C of the nozzle row 68C and land on the same pixel in duplicate. When the distance between the nozzles is long, it takes a long time from the landing of the preceding ink droplet 67Y to the landing of the succeeding ink droplet 67C. Since the ink droplet 67Y is dried by the time the ink droplet 67C lands, even if the ink droplet 67Y and the ink droplet 67C overlap, the inks are less likely to bleed from each other. As a result, the color development is relatively increased with respect to the case where the distance between the nozzles is short, so that a difference occurs in the color development of the secondary color, and streaks and color unevenness along the relative movement direction D2 as shown in FIG. 21 are visually recognized. It had been.

Therefore, in the printing device 1 of the present embodiment, when printing a secondary color between the first nozzle row NL1 and the third nozzle row NL3, which have a plurality of distances between the nozzles, and the second nozzle row NL2 and the third nozzle. When the secondary color is printed in the row NL3, the first printing is performed to reduce the overlap ratio of the dots on which the ink droplets 67 are overlapped and landed by the halftone processing. As a result, the occurrence of streaks and color unevenness along the relative movement direction D2 in the printed image IM1 is suppressed.

FIG. 4 is a diagram illustrating an example of the dither mask A. FIG. 5 is a diagram illustrating an example of the output color data DA2 after the color conversion process. FIG. 6 is a diagram illustrating an example of print data DA3 after halftone processing using dither mask A. FIG. 7 is a diagram illustrating an example of the dither mask B. FIG. 8 is a diagram illustrating an example of print data DA3 after halftone processing using the dither mask B. The dither masks A and B are shown as masks having 16 grids of 4 rows and 4 columns for convenience of explanation. Further, the output color data DA2 shown in FIG. 5 shows only the pixels overlapping with the dither mask A or the dither mask B.

The dither mask A shown in FIG. 4 is a dither mask for determining the printing of the first ink droplets ejected from the first nozzle row NL1 (nozzle row 68C). The dither mask B shown in FIG. 7 is a dither mask for determining the printing of the third ink droplet to be ejected from the third nozzle row NL3 (nozzle row 68Y).

A plurality of threshold values from 0 to 15 are set in each of the 4 rows and 4 columns of the dither masks A and B. The plurality of thresholds of the dither mask B shown in FIG. 7 satisfy a complementary relationship with the plurality of thresholds of the dither mask A shown in FIG. For example, the minimum threshold value "0" is set for the grid where the first row and the first column of the dither mask A intersect, whereas the grid of the dither mask B has the maximum threshold value. A certain "15" is set. Further, the maximum threshold value "15" is set for the grid where the fourth row and the first column of the dither mask A intersect, whereas the grid of the dither mask B has the minimum threshold value. A certain "0" is set.

The output color data DA2 shown in FIG. 5 is ink amount data formed by the color conversion process of the color conversion unit 42. The ink amount data is data corresponding to the number of dots per unit area. The output color data DA2 of FIG. 5 is represented by ink amount data of 16 gradations of 0 to 15 in 16 pixels of 4 rows and 4 columns for convenience of explanation. In the output color data DA2 of FIG. 5, a gradation value “8” corresponding to 50% of the maximum ink amount is set for all pixels.

The print data DA3 shown in FIG. 6 is dot formation data formed by halftone processing of the halftone processing unit 43 using the dither mask A. The print data DA3 shown in FIG. 8 is dot formation data formed by halftone processing of the halftone processing unit 43 using the dither mask B. 6 and 8 are binary data indicating the presence or absence of dot formation in each pixel, and the pixel with dots is represented by “black” and the pixel without dots is represented by “white”. The halftone processing unit 43 compares the gradation value (ink amount data) shown in each pixel with the threshold value set in the grid of the dither mask corresponding to the pixel for each pixel of the output color data DA2. Determines the presence or absence of dots. The halftone processing unit 43 has dots when the threshold value <gradation value, and no dots when the gradation value ≤ threshold value. In the output color data DA2 shown in FIG. 5, since the gradation value “8” is set for all the pixels, dots are formed in 50% of all the pixels. Hereinafter, the ratio of dots formed is described as, for example, "Duty 50%". Since the dither mask A shown in FIG. 4 and the dither mask B shown in FIG. 7 have a threshold of complementary relationship, the print data DA3 shown in FIG. 6 and the print data DA3 shown in FIG. 8 have dots with dots. And the pixel without dots are inverted.

FIG. 9 is a diagram illustrating an example of print data DA3 after halftone processing using dither mask A. FIG. 10 is a diagram illustrating an example of print data DA3 after halftone processing using the dither mask A'. FIG. 11 is a diagram illustrating an example of print data DA3 after halftone processing using the dither mask B. The dither masks used to generate the print data DA3 shown in FIGS. 9 to 11 are masks having 256 grids of 16 rows and 16 columns. "Dither mask A'" means that the dither mask A is used, for example, in a state where the entire mask is moved by 1/2 in the relative movement direction D2 with respect to the pixels of the output color data DA2. Therefore, when the same output color data DA2 is halftone processed, the print data DA3 (see FIG. 10) generated by the dither mask A'is a dot with respect to the print data DA3 (see FIG. 9) generated by the dither mask A. The positions with and without dots are shifted by 8 columns. Further, since the dither mask A and the dither mask B are set with the threshold value of the complementary relationship, when the dots having a duty of 50% are formed, the pixels with dots and the pixels without dots are inverted as shown in FIGS. 9 and 11. ..

Next, in the first printing, the overlap ratio of the ink droplets when the secondary color is printed by the ink droplets 67 ejected from the two different nozzle rows 68 will be described. Note that overlapping ink droplets means that two different ink droplets land on the same pixel.
The overlap ratio of the first ink droplets and the third ink droplets when printing the secondary color by the first ink droplets ejected from the first nozzle row NL1 and the third ink droplets ejected from the third nozzle row NL3 is X. %, And the overlap of the first ink droplet and the second ink droplet when printing the secondary color by the first ink droplet ejected from the first nozzle row NL1 and the second ink droplet ejected from the second nozzle row NL2. When the ratio is Y%, the first printing is printing that satisfies the condition of X <Y.

FIG. 12 is a diagram illustrating the first printing.
“C + M” of the ink combination shown in FIG. 12 represents a case where blue (B), which is a secondary color, is printed by C ink and M ink. The C ink is the first ink droplet ejected from the first nozzle row NL1, and the M ink is the second ink droplet ejected from the second nozzle row NL2. As described above, the distance between the nozzles of the first nozzle row NL1 and the second nozzle row NL2 is constant at the distance L0 in all the print areas AL1 to AL6. The mask combination "A + A'" indicates that the dither mask A is used for the halftone processing of the C ink and the dither mask A'is used for the halftone processing of the M ink.

The ratio of dot overlap between C ink and M ink will be described.
When the print data DA3 shown in FIG. 9 is generated for printing the C ink with a duty of 50%, the print data DA3 of the C ink is shifted by 8 columns for the printing of the M ink with a duty of 50%. DA3 is generated.
When printing with a total of 100% Duty with 50% Duty C ink and 50% Duty M ink, C ink and M ink land on the same pixel, only C ink land, and only M ink land. There are four patterns in which the ink does not land. Therefore, the probability that the first ink droplet of C ink and the second ink droplet of M ink land on the same pixel is 25%, and the overlapping ratio of dots is Y = 25%. Similarly, when printing with a total duty of 125% with the C ink of Duty 62.5% and the M ink of Duty 62.5%, the overlapping ratio of dots is Y = 37.5%. When printing with a total Duty of 150% with the Duty 75% C ink and the Duty 75% M ink, the dot overlap ratio is Y = 50%.

The ink combination "Y + C" represents a case where green (G), which is a secondary color, is printed by using Y ink and C ink. The Y ink is a third ink droplet discharged from the third nozzle row NL3. As described above, the distance between the nozzles of the first nozzle row NL1 and the third nozzle row NL3 may be two types, the distance L1 and the distance L2, depending on the print areas AL1 to AL6. The mask combination "B + A" indicates that the dither mask B is used for the halftone processing of the Y ink and the dither mask A is used for the halftone processing of the C ink.

The ratio of dot overlap between Y ink and C ink will be described.
When the print data DA3 shown in FIG. 9 is generated for printing the Duty 50% C ink, the print data DA3 shown in FIG. 11 in which the pixel with dots and the pixels without dots are inverted is used for printing the Y ink with Duty 50%. Generated.
When printing with a total of 100% Duty with 50% Duty C ink and 50% Duty Y ink, the C ink and Y ink do not land on the same pixel, so the dot overlap ratio is X =. It is 0%. When printing a total of 125% with the C ink of Duty 62.5% and the Y ink of Duty 62.5%, the dots corresponding to the Duty 12.5%, which increase from the Duty 50%, land on the same pixel. The overlap ratio of X = 12.5%. Similarly, when printing with a total duty of 150% with the C ink having a duty of 75% and the Y ink having a duty of 75%, the overlapping ratio of dots is X = 25%.
By making the threshold of the dither mask B for determining the printing of the Y ink, which is the third ink droplet, and the threshold of the dither mask A for determining the printing of the C ink, which is the first ink droplet, complementary to each other, Y The ratio of overlap between the ink and the C ink can be reduced.

The ink combination "Y + M" represents a case where red (R), which is a secondary color, is printed by Y ink and M ink. The distance between the nozzles of the second nozzle row NL2 and the third nozzle row NL3 may be two types, the distance L1 and the distance L2, depending on the print areas AL1 to AL6. The mask combination "B + A" indicates that the dither mask B is used for the halftone processing of the Y ink and the dither mask A is used for the halftone processing of the M ink.

The overlapping ratio of dots between Y ink and M ink is the same as the overlapping ratio of dots between Y ink and C ink.
By making the threshold of the dither mask B for determining the printing of the Y ink, which is the third ink droplet, and the threshold of the dither mask A for determining the printing of the M ink, which is the second ink droplet, complementary to each other, Y The ratio of overlap between the ink and the M ink can be reduced. Here, the complementary relationship is not limited to the fact that all the threshold values of the dither mask A and the threshold values of the dither mask B are complementary, and also includes those in which some of the threshold values are not complementary.
As described above, the halftone processing unit 43 executes the halftone processing of the first printing that satisfies the condition of XY.

Next, the printing method of the printing apparatus 1 will be described.
<Printing method of the first printing>
FIG. 13 is a flowchart illustrating a printing method of the first printing.

Step S101 is an image acquisition step of acquiring image data. The inkjet printer 2 acquires image data (data in the RGB color space) to be printed on the object to be printed ME1 and stores it in the RAM 20 or the non-volatile memory 30.

Step S102 is a resolution conversion processing step. The controller 10 generates the input color data DA1 in which the resolution of the acquired image data is converted into the print resolution when printing on the printed matter ME1 in the resolution conversion processing step in the resolution conversion unit 41.

Step S103 is a color conversion processing step. The controller 10 performs color conversion processing on the input color data DA1 which is the RGB color space data in the color conversion unit 42, and generates the output color data DA2 which is the image data of the CMYK color space.

Step S104 is a halftone processing step. The controller 10 performs halftone processing on the output color data DA2 for each color of CMYK in the halftone processing unit 43, and generates print data DA3 indicating the presence or absence of dots in each pixel. The halftone processing unit 43 sets Y% as the overlap ratio of dots when the distance between the nozzles of two different nozzle rows, which ejects ink droplets when printing a secondary color, is constant, and two different nozzles. When the overlapping ratio of dots when there are a plurality of distances between nozzles in the nozzle row is set to X%, halftone processing satisfying the condition of X <Y is performed.

Step S105 is a mechanism unit driving step. The controller 10 generates a drive signal SG based on the print data DA3 in the signal transmission unit 44, outputs the drive signal SG to the drive circuit 62, and drives the mechanism unit 50. As a result, the first printing is executed on the printed matter ME1.

The printing device 1 and the printing method of the first printing are secondary color printing using the first nozzle row NL1 and the third nozzle row NL3 having a plurality of distances between the nozzles, and the second nozzle row NL2 and the third. When printing the secondary color using the nozzle row NL3, the dots are larger than when printing the secondary color using the first nozzle row NL1 and the second nozzle row NL2 where the distance between the nozzles is constant. The ratio of overlapping of is reduced, and the difference in color development is less likely to occur. As a result, streaks and color unevenness that occur in secondary color printing using the nozzle rows 68 having a plurality of distances between the nozzles are suppressed.

In the present embodiment, the first ink droplets ejected from the first nozzle row NL1 are C ink, and the third ink droplet ejected from the third nozzle row NL3 is Y ink, so that the cyan ink droplets and the yellow ink. It is possible to suppress streaks and color unevenness that occur when printing green with drops. Further, since the second ink droplets ejected from the second nozzle row NL2 are M inks, it is possible to suppress streaks and color unevenness that occur when red is printed by the magenta ink droplets and the yellow ink droplets.

In the printing method of the first printing, the inkjet printer 2 may be configured not to include the selective printing unit U1, the printed matter type selection unit U2, the temperature sensor SE1 and the humidity sensor SE2.

<Printing method that selectively performs the first printing and the second printing based on the type of printed matter>
FIG. 14 is a diagram illustrating the second printing. FIG. 15 is a flowchart illustrating a printing method in which the first printing and the second printing are selectively performed based on the type of the printed matter. As shown in FIG. 1, the inkjet printer 2 selects a selection printing unit U1 that selectively performs a plurality of printing including a first printing and a second printing, and a type of printed matter ME1 used for printing. It is provided with a printed matter type selection unit U2 for receiving. The selective printing unit U1 and the printed matter type selection unit U2 are included in the CPU 11.

The second printing is a printing method according to the prior art. Since the meanings of "ink color combination", "distance between nozzles", and "mask combination" in the second printing shown in FIG. 14 are the same as those in the first printing, the description thereof will be omitted. In the second printing, the mask combination "A + A'" is also applied to the printing of the secondary color by the ink color combinations of "Y + C" and "Y + M" using the nozzle rows 68 having a plurality of distances between the nozzles. Therefore, what is the dot overlap ratio Y% when the nozzle row 68 having a constant distance between the nozzles is used and the dot overlap ratio X% when the nozzle row having a plurality of nozzle distances is used? , Will be equal.
As described above, the halftone processing unit 43 executes the halftone processing of the second printing satisfying the condition of X = Y.

The selective printing unit U1 selectively performs a plurality of printing including a first printing satisfying X <Y and a second printing satisfying X = Y. When the printed matter ME1 used for printing or the printing environment is printing conditions where streaks and color unevenness are likely to occur, the selective printing unit U1 selects the first printing, so that the nozzles have a plurality of distances between the nozzles. In the secondary color printing using the column 68, it is possible to perform printing in which streaks and color unevenness are suppressed.

Next, a printing method for selectively performing the first printing and the second printing based on the printed matter ME1 will be described with reference to FIG. Of the flows shown in FIG. 15, step S201, step S203, and step S204 are the same as the above-mentioned steps S101, S102, and S103, respectively, and thus the description thereof will be omitted.

Step S202 is a printed matter type selection step for selecting the selected type of printed matter ME1. The controller 10 stores, for example, the type of the printed matter ME1 received by the printed matter type selection unit U2 in the non-volatile memory 30. The printed matter type selection unit U2 specifies, for example, the type of the printed matter ME1 to be used for printing by the user selecting the type of the printed matter displayed on the output unit 74 of the operation panel 73 by the input unit 75. .. As the type of the printed matter ME1, for example, the printed matter "Media1", which is the first type in which the ink droplets are difficult to dry and streaks and color unevenness are likely to occur due to a plurality of distances between the nozzles, and the ink droplets are dried. There is a second type of printed matter "Media 2" that is easy to use and is unlikely to cause streaks or color unevenness even if there are a plurality of distances between the nozzles.

Step S205 is a determination step for determining the type of the printed matter ME1. The controller 10 refers to the non-volatile memory 30 and obtains the type of the selected printed matter ME1. If the type of the printed matter ME1 is "Media1", the process proceeds to step S206, and if the type of the printed matter ME1 is "Media2", the process proceeds to step S207.

Step S206 is a halftone processing step of the first printing. The controller 10 executes the first print halftone process when the type of the printed matter ME1 is "Media1". The halftone processing performed in this step is the same as the halftone processing described in step S104.

Step S207 is a second printing halftone processing step. The controller 10 performs halftone processing on the output color data DA2 for each color of CMYK in the halftone processing unit 43, and generates print data DA3 indicating the presence or absence of dots in each pixel. The halftone processing unit 43 sets Y% as the overlap ratio of dots when the distance between the nozzles of two different nozzle rows 68, which ejects ink droplets 67 when printing a secondary color, is constant, and is different. When the overlapping ratio of dots when there are a plurality of distances between the nozzles of the two nozzle rows is set to X%, halftone processing satisfying the condition of X = Y is performed.

Step S208 is a mechanism unit driving step. The controller 10 generates a drive signal SG based on the print data DA3 in the signal transmission unit 44, outputs the drive signal SG to the drive circuit 62, and drives the mechanism unit 50. When the type of the printed matter ME1 that has received the selection is "Media1", the selective printing unit U1 causes the halftone processing of the first printing to be performed in step S206, so that the first printing is performed on the printed matter ME1. Is executed. Further, when the type of the printed matter ME1 that has received the selection is "Media2", the selective printing unit U1 causes the halftone processing of the second printing to be performed in step S207, so that the printed matter ME1 is second. Printing is executed.

The selective printing unit U1 prints first when "Media1", in which ink droplets are difficult to dry and streaks and color unevenness are likely to occur due to a plurality of distances between nozzles, is selected by the printed matter type selection unit U2. Halftone processing and first printing are performed. As a result, in the printing of the secondary color using the nozzle rows 68 having a plurality of distances between the nozzles, it is possible to perform printing with suppressed streaks and color unevenness.

Although it has been described that the printed matter type selection step is performed after the image acquisition step, the printed matter type selection step may be performed immediately after the start to the determination step.
It has been described that the type of the printed matter ME1 is selected from two types of "Media1" and "Media2", but it may be selected from three or more types.

<Printing method that selectively performs the first printing and the second printing based on the temperature>
FIG. 16 is a flowchart illustrating a printing method in which the first printing and the second printing are selectively performed based on the temperature.
Next, a printing method in which the first printing and the second printing are selectively performed based on the temperature will be described with reference to FIG. Of the flows shown in FIG. 16, step S301, step S303, and step S304 are the same as the above-mentioned steps S101, S102, and S103, respectively, and thus the description thereof will be omitted.

Step S302 is a temperature measuring step for measuring the environmental temperature. The temperature sensor SE1 detects the ambient temperature of the inkjet printer 2. The controller 10 acquires the detected temperature T detected by the temperature sensor SE1 and stores it in, for example, the non-volatile memory 30.

Step S305 is a determination step for determining the temperature condition. The controller 10 refers to the non-volatile memory 30 and determines whether or not the detection temperature T <temperature Tt is satisfied. When the detection temperature T at the time of printing satisfies the first temperature condition, that is, when the detection temperature T is a low temperature condition in which the ink droplets are difficult to dry, the distance between the plurality of nozzles causes streaks and streaks. Color unevenness is likely to occur. When the second temperature condition higher than the first temperature condition is satisfied, that is, when the detected temperature T is a high temperature condition where ink droplets are easily dried, streaks and color unevenness are observed even if there is a distance between a plurality of nozzles. Is unlikely to occur. If the detected temperature T is lower than the temperature Tt, which is the first temperature condition, the process proceeds to step S306, and if the detected temperature T is equal to or higher than the temperature Tt, which is the second temperature condition, the process proceeds to step S307.

Step S306 is a halftone processing step of the first printing. The controller 10 executes the first printing halftone process when the detected temperature T is equal to or higher than the temperature Tt. The halftone processing performed in this step is the same as the halftone processing described in step S104.

Step S307 is a second printing halftone processing step. The controller 10 executes a second print halftone process when the detected temperature T is less than the temperature Tt. The halftone processing performed in this step is the same as the halftone processing described in step S207.

Step S308 is a mechanism unit driving step. The controller 10 generates a drive signal SG based on the print data DA3 in the signal transmission unit 44, outputs the drive signal SG to the drive circuit 62, and drives the mechanism unit 50. When the detected temperature T is lower than the temperature Tt, the selective printing unit U1 causes the halftone processing of the first printing to be performed in step S306, so that the first printing is executed on the printed matter ME1. .. Further, when the detected temperature T is equal to or higher than the temperature Tt, the selective printing unit U1 causes the halftone processing of the second printing to be performed in step S307, so that the second printing is executed on the printed matter ME1. Will be done.

The selective printing unit U1 performs the halftone processing of the first printing and the halftone processing of the first printing when the temperature T of the temperature sensor SE1 is less than the temperature Tt, which is an environmental condition in which streaks and color unevenness are likely to occur due to a plurality of distances between the nozzles. Perform the first print. As a result, in secondary color printing using a nozzle row 68 having a plurality of distances between nozzles under a temperature condition in which ink droplets are difficult to dry, it is possible to perform printing with suppressed streaks and color unevenness.

Although the temperature sensor SE1 has been described as detecting the environmental temperature of the inkjet printer 2, it may be a temperature sensor or the like that detects the temperature of the print head 60. Further, although it has been described that the temperature measurement step is performed after the image acquisition step, the temperature measurement step may be performed immediately after the start to the determination step.

<Printing method that selectively performs the first printing and the second printing based on humidity>
FIG. 17 is a flowchart illustrating a printing method in which the first printing and the second printing are selectively performed based on the humidity.
Next, a printing method in which the first printing and the second printing are selectively performed based on the humidity will be described with reference to FIG. Of the flows shown in FIG. 17, step S401, step S403, and step S404 are the same as the above-mentioned steps S101, S102, and S103, respectively, and thus the description thereof will be omitted.

Step S402 is a humidity measuring step for measuring the environmental humidity. The humidity sensor SE2 detects the environmental humidity of the inkjet printer 2. The controller 10 acquires the detected humidity H detected by the humidity sensor SE2 and stores it in, for example, the non-volatile memory 30.

Step S405 is a determination step for determining the humidity condition. The controller 10 refers to the non-volatile memory 30 and determines whether or not the detected humidity H> humidity Ht is satisfied. When the environmental humidity at the time of printing satisfies the first humidity condition, that is, when the detected humidity H is a high humidity condition where the ink droplets are difficult to dry, the distance between the plurality of nozzles causes streaks and colors. Unevenness is likely to occur. When the second temperature condition lower than the first humidity condition is satisfied, that is, when the detected humidity H is a low humidity condition where ink droplets are easily dried, streaks and color unevenness are observed even if there is a distance between a plurality of nozzles. Is unlikely to occur. When the detected humidity H exceeds the humidity Ht which is the first humidity condition, the process proceeds to step S406, and when the detected humidity H is equal to or less than the temperature Ht which is the second humidity condition, the process proceeds to step S407.

Step S406 is a halftone processing step of the first printing. The controller 10 executes the first printing halftone process when the detected humidity H exceeds the humidity Ht. The halftone processing performed in this step is the same as the halftone processing described in step S104.

Step S407 is a second printing halftone processing step. The controller 10 executes the second printing halftone process when the detected humidity H is equal to or less than the humidity Ht. The halftone processing performed in this step is the same as the halftone processing described in step S207.

Step S408 is a mechanism unit driving step. The controller 10 generates a drive signal SG based on the print data DA3 in the signal transmission unit 44, outputs the drive signal SG to the drive circuit 62, and drives the mechanism unit 50. When the detected humidity H exceeds the humidity Ht, the selective printing unit U1 causes the halftone processing of the first printing to be performed in step S406, so that the first printing is executed on the printed matter ME1. Further, since the selective printing unit U1 causes the halftone processing of the second printing to be performed in step S407 when the detected humidity H is the humidity Ht or less, the second printing is executed on the printed matter ME1. ..

The selective printing unit U1 performs halftone processing for the first printing when the detected humidity H of the humidity sensor SE2 exceeds the humidity Ht, which is an environmental condition in which streaks and color unevenness are likely to occur due to a plurality of distances between the nozzles. And perform the first print. As a result, in secondary color printing using a nozzle row 68 having a plurality of distances between nozzles under a humidity condition in which ink droplets are difficult to dry, it is possible to perform printing with suppressed streaks and color unevenness.

Although it has been described that the humidity measurement step is performed after the image acquisition step, the humidity measurement step may be performed immediately after the start to the determination step.

In the present embodiment, the liprinter is exemplified as the inkjet printer 2, but a serial head type inkjet printer may be used.
Although the inkjet printer 2 has been described as having a temperature sensor SE1 and a humidity sensor SE2, it is provided with a dew point thermometer instead of the temperature sensor SE1 and the humidity sensor SE2, and the selective printing unit U1 prints first according to the dew point temperature. It may be configured to execute.
The selective printing unit U1 has been described as performing the first printing based on the printed matter ME1, the detected temperature T and the detected humidity H, but the selective printing unit has the printed matter ME1, the detected temperature T and the detected humidity H. The first print may be performed based on the combination.
Although the selective printing unit U1 and the printed matter type selection unit U2 have been described as being included in the CPU 11, they may be configured to be included in the host device 100.
Each process according to the present embodiment is not limited to the example executed by the CPU 11, and may be executed by another electronic component such as an ASIC (Application Specific Integrated Circuit). Further, the process according to the present embodiment may be distributed by a plurality of CPUs, or may be executed by the CPU and other electronic components operating in cooperation with each other.

As described above, according to the printing device 1, the printing method, and the image processing device 3 according to the present embodiment, the following effects can be obtained.

The inkjet printer 2 prints secondary colors using a first nozzle row NL1 and a third nozzle row NL3 having a plurality of distances between nozzles, and uses a second nozzle row NL2 and a third nozzle row NL3. When printing the secondary color, the overlap rate of dots is smaller than when printing the secondary color using the first nozzle row NL1 and the second nozzle row NL2 where the distance between the nozzles is constant. , Makes it difficult for differences in color development to occur. As a result, streaks and color unevenness that occur in secondary color printing using the nozzle rows 68 having a plurality of distances between the nozzles are suppressed. Therefore, it is possible to provide the printing device 1 capable of suppressing the occurrence of streaks and color unevenness in the printing of the secondary color using the nozzle rows 68 having a plurality of distances between the nozzles.

The threshold value of the dither mask B for determining the printing of the Y ink, which is the third ink droplet, is the dither mask A, which determines the printing of the C ink, which is the first ink droplet, and the M ink, which is the second ink droplet. It is complementary to the threshold of. This makes it possible to reduce the overlap ratio between the Y ink and the C ink and the overlap ratio between the Y ink and the M ink.

On the head tip 61, the first nozzle row NL1 and the second nozzle row NL2 are arranged in the relative moving direction D2, and the first nozzle row NL1 and the third nozzle row NL3 are arranged in the aligned direction D1. According to this configuration, the length of the print head 60 in the relative moving direction D2 can be shortened as compared with the configuration in which the first to third nozzle rows NL1 to NL3 are arranged in the relative moving direction D2. As a result, the landing position of the ink droplet 67 is less likely to vary, and the printed matter ME1 is less likely to come into contact with the print head 60.

On the head tip 61, the third nozzle row NL3 and the fourth nozzle row NL4 are arranged in the relative moving direction D2. According to this configuration, the length of the print head 60 in the relative moving direction can be shortened as compared with the configuration in which the first to fourth nozzle rows NL1 to NL4 are arranged in the relative moving direction D2.

The length La of the print head 60 in the relative moving direction D2 is three times the length Lb of the head chip 61 in the relative moving direction D2. As a result, the length La of the print head 60 in the relative moving direction D2 becomes the shortest, the landing position of the ink droplet 67 is less likely to vary, and the printed matter ME1 is less likely to come into contact with the print head 60.

C ink is ejected from the first ink droplets ejected from the first nozzle row NL1, M ink is ejected from the second ink droplets ejected from the second nozzle row NL2, and third ink is ejected from the third nozzle row NL3. Y ink is selected for the drops. This makes it possible to suppress streaks and color unevenness that occur when printing green with cyan ink droplets and yellow ink droplets, and when printing red with magenta ink droplets and yellow ink droplets.

The inkjet printer 2 includes a selective printing unit U1 that selectively performs a plurality of printing including a first printing satisfying X <Y and a second printing satisfying X = Y. By selecting the first printing by the selective printing unit U1 under printing conditions where streaks and color unevenness are likely to occur, in secondary color printing using the nozzle rows 68 having a plurality of distances between nozzles, streaks and streaks are generated. Printing with suppressed color unevenness can be performed.

The inkjet printer 2 includes a printed matter type selection unit U2 that accepts selection of the type of printed matter ME1 used for printing. The selective printing unit U1 prints first when "Media1", in which ink droplets are difficult to dry and streaks and color unevenness are likely to occur due to a plurality of distances between nozzles, is selected by the printed matter type selection unit U2. Halftone processing and first printing are performed. As a result, in the printing of the secondary color using the nozzle rows 68 having a plurality of distances between the nozzles, it is possible to perform printing with suppressed streaks and color unevenness.

The inkjet printer 2 includes a temperature sensor SE1 that detects the ambient temperature. The selective printing unit U1 performs halftone processing for the first printing when the detection temperature T of the temperature sensor SE1 is less than the temperature Tt, which is an environmental condition in which streaks and color unevenness are likely to occur due to a plurality of distances between the nozzles. And perform the first print. As a result, in secondary color printing using a nozzle row 68 having a plurality of distances between nozzles under a temperature condition in which ink droplets are difficult to dry, it is possible to perform printing with suppressed streaks and color unevenness.

The inkjet printer 2 includes a humidity sensor SE2 that detects environmental humidity. The selective printing unit U1 performs halftone processing for the first printing when the detected humidity H of the humidity sensor SE2 exceeds the humidity Ht, which is an environmental condition in which streaks and color unevenness are likely to occur due to a plurality of distances between the nozzles. And perform the first print. As a result, in secondary color printing using a nozzle row 68 having a plurality of distances between nozzles under a humidity condition in which ink droplets are difficult to dry, it is possible to perform printing with suppressed streaks and color unevenness.

The printing method of the printing apparatus 1 is to print a secondary color using a first nozzle row NL1 and a third nozzle row NL3 having a plurality of distances between nozzles, and to print a second nozzle row NL2 and a third nozzle row NL3. When printing the used secondary color, the overlap rate of dots is higher than when printing the secondary color using the first nozzle row NL1 and the second nozzle row NL2 where the distance between the nozzles is constant. By reducing the amount, it is difficult to cause a difference in color development. As a result, streaks and color unevenness that occur in secondary color printing using the nozzle rows 68 having a plurality of distances between the nozzles are suppressed. Therefore, it is possible to provide a printing method capable of suppressing the occurrence of streaks and color unevenness in the printing of secondary colors using the nozzle rows 68 having a plurality of distances between the nozzles.

The image processing apparatus 3 used secondary color printing using the first nozzle row NL1 and the third nozzle row NL3 having a plurality of distances between the nozzles, and the second nozzle row NL2 and the third nozzle row NL3. When printing a secondary color, the overlap rate of dots is smaller than when printing a secondary color using the first nozzle row NL1 and the second nozzle row NL2 where the distance between the nozzles is constant. Therefore, halftone processing is performed to make it difficult for differences in color development to occur. As a result, streaks and color unevenness that occur in secondary color printing using the nozzle rows 68 having a plurality of distances between the nozzles are suppressed. Therefore, it is possible to provide an image processing device 3 capable of suppressing the occurrence of streaks and color unevenness in secondary color printing using a nozzle row 68 having a plurality of distances between nozzles.

The present invention is not limited to the above-described embodiment, and various modifications can be made to the above-mentioned one without departing from the spirit of the present invention. A modified example will be described below.

(Modification example)
Next, a modification of the print head will be described with reference to FIG. FIG. 18 is a diagram schematically illustrating a print head according to a modified example. In FIG. 2, the print head 160 is shown from the side opposite to the nozzle surface where the nozzle 64 is located, but for convenience, the position of the nozzle 64 is shown, and a nozzle that ejects ink droplets 67 of C, M, Y, or K is shown. 64 is represented by a color-coded pattern of ink droplets 67. The same components as those in the embodiment are designated by the same numbers, and duplicated explanations will be omitted.

The print head 160 is composed of a first head chip 161a, a second head chip 161b, and a third head chip 161c.
The first head tip 161a has a third nozzle row NL3 (nozzle row 68Y) and a fourth nozzle row NL4 (nozzle row 68K). In the first head chip 161a, the third nozzle row NL3 and the fourth nozzle row NL4 are arranged in the relative moving direction D2.

The second head chip 161b has a first nozzle row NL1 (nozzle row 68C), a second nozzle row NL2 (nozzle row 68M), a third nozzle row NL3, and a fourth nozzle row NL4. In the second head tip 161b, the first nozzle row NL1 and the second nozzle row NL2 are arranged in the relative moving direction D2. The first nozzle row NL1 and the third nozzle row NL3 are arranged in the nozzle arrangement direction D1. The third nozzle row NL3 and the fourth nozzle row NL4 are arranged in the relative moving direction D2.
The third head tip 161c has a first nozzle row NL1 and a second nozzle row NL2. In the third head chip 161c, the first nozzle row NL1 and the second nozzle row NL2 are arranged in the relative moving direction D2.
That is, the print head 160 is composed of two first to fourth nozzle rows NL1, NL2, NL3, and NL4, respectively.

In the second head tip 161b, a non-ejection region A2 is generated between the nozzle rows 68C and 68M and the nozzle rows 68Y and 68K. When a non-ejection region A2 without a nozzle 64 occurs in the head chip 61 in the alignment direction D1, as shown in FIG. 18, in order to arrange the CMYK nozzle 64 on the same line DL, the head chip 61 is moved in the relative movement direction D2. It is necessary to line up at least 3 chips.

Since the print head 60 has a non-ejection region A2, the distance between the nozzles in the relative movement direction D2 may differ depending on the combination of the nozzle rows 68C, 68M, 68Y, 68K according to the print regions AL1 to AL3. be. For example, among a plurality of nozzle rows 68 that eject ink droplets 67 in the same line DL along the relative movement direction D2, the nozzle row 68C (first nozzle row NL1) and the nozzle row 68M (second nozzle) in the relative movement direction D2. The distance between the nozzles in the row NL2) is a constant distance L0 on all lines DL1 to DL3.

The distance between the nozzles 68C (first nozzle row NL1) and the nozzle row 68Y (third nozzle row NL3) in the relative moving direction D2 has a plurality of distances L1 and L2. For example, the distance between the nozzles of the nozzle rows 68C and 68Y in the lines DL1 and DL3 is the distance L1, and the distance between the nozzles of the nozzle rows 68C and 68Y in the line DL2 is the distance L2 (L2> L1).

Conventionally, when a secondary color is printed using a print head 160 having a plurality of distances between nozzles, streaks and color unevenness occur due to a difference in color development of the secondary color. By applying one printing, it is possible to suppress the occurrence of streaks and color unevenness.

The contents derived from the embodiment are described below.

The printing apparatus of the present application is a printing apparatus in which a print head and an object to be printed move relative to each other in a relative movement direction different from the direction in which the nozzles of the nozzle row are arranged, and the print head is a first nozzle row and a second nozzle row. , And the number of the first nozzle row, the second nozzle row, and the third nozzle row is 2 or more, and ink droplets are formed on the same line along the relative movement direction. Of the plurality of nozzle rows for ejecting ink, the distance between the first nozzle row and the second nozzle row in the relative movement direction is constant, and the first nozzle row and the third nozzle row in the relative movement direction are constant. There are a plurality of distances from the ink droplets, and the first ink droplets when printing a secondary color by the first ink droplets ejected from the first nozzle row and the third ink droplets ejected from the third nozzle row. And when the overlapping ratio of the third ink droplets is set to X% and the secondary color is printed by the first ink droplets ejected from the first nozzle row and the second ink droplets ejected from the second nozzle row. When the overlapping ratio of the first ink droplet and the second ink droplet is Y%, the first printing satisfying the condition of X <Y is performed.

According to this configuration, the distance between the first nozzle row and the third nozzle row in the relative moving direction (hereinafter, also referred to as “distance between nozzles”) includes a long distance and a short distance. When the distance between the nozzles is long on the same line along the relative movement direction, the first ink droplet ejected from the first nozzle row lands on the object to be printed, and then the third ink ejected from the third nozzle row. It takes a long time for the droplets to land on the first ink droplets of the printed matter. When the distance between the nozzles is short on the same line along the relative movement direction, the first ink droplets ejected from the first nozzle row land on the object to be printed, and then the third ink ejected from the third nozzle row. It takes a short time for the droplets to land on the first ink droplets of the printed matter. In a region where the distance between the nozzles is long, the first ink droplets are dried by the time the third ink droplets land, so that even if the first ink droplets and the third ink droplets overlap, the inks are less likely to bleed from each other. In a region where the distance between the nozzles is short, the third ink droplets land before the first ink droplets are dried. Therefore, when the first ink droplets and the third ink droplets overlap, the inks tend to bleed from each other. As a result, the color development of the secondary color is different, so that streaks and color unevenness along the relative movement direction are visually recognized.

In the printing apparatus, the overlap ratio of the first ink droplets and the third ink droplets when printing the secondary color by the first ink droplets ejected from the first nozzle row and the third ink droplets ejected from the third nozzle row. Is X%, and the overlap of the first ink droplet and the second ink droplet when printing the secondary color by the first ink droplet ejected from the first nozzle row and the second ink droplet ejected from the second nozzle row. When the ratio is Y%, printing that satisfies the condition of X <Y is performed. That is, when the printing apparatus prints a secondary color using a first nozzle row and a third nozzle row having a plurality of distances between the nozzles, the printing device has a constant distance between the nozzles and the first nozzle row. The overlap ratio of ink droplets is reduced as compared with the case of printing a secondary color using a second nozzle row, so that a difference in color development is less likely to occur. As a result, streaks and color unevenness that occur in secondary color printing using the first and third nozzle rows are suppressed. Therefore, it is possible to provide a printing device capable of suppressing the occurrence of streaks and color unevenness in the printing of secondary colors using the first and third nozzle rows having a plurality of distances between the nozzles.

In the above printing apparatus, the plurality of dither mask thresholds for determining printing with the third ink droplet complement each other with the plurality of dither mask thresholds for determining printing with the first ink droplet. It is preferable to meet.

According to this configuration, the threshold value of the dither mask for determining the printing with the third ink droplet and the threshold value of the dither mask for determining the printing with the first ink droplet are in a complementary relationship. This makes it possible to reduce the overlap ratio between the first ink droplet and the third ink droplet.

In the above printing apparatus, the print head includes a plurality of head chips having the first nozzle row, the second nozzle row, and the third nozzle row, and in the head chip, the first nozzle row and the like. The second nozzle row is arranged in the relative movement direction, and one of the first nozzle row and the second nozzle row and the third nozzle row are arranged in the arrangement direction of the nozzles. It is preferable to have.

According to this configuration, in the head chip, the first nozzle row and the second nozzle row are arranged in the relative movement direction, and one of the first nozzle row and the second nozzle row, the third nozzle row, and the head chip are arranged. Are arranged in the direction of the nozzles. The print head includes a plurality of head chips. In this configuration, the length of the print head in the relative movement direction can be shortened as compared with the configuration in which the first to third nozzle rows are arranged in the relative movement direction. As a result, the landing position of the ink droplets is less likely to vary, and the printed matter is less likely to come into contact with the print head.

In the above printing apparatus, it is preferable that the head chip further has a fourth nozzle row, and the third nozzle row and the fourth nozzle row are arranged in the relative movement direction.

According to this configuration, in the head tip, the third nozzle row and the fourth nozzle row are arranged in the relative movement direction. That is, on the head chip, the first to fourth nozzle rows are arranged in two rows and two rows in the relative moving direction and the nozzle arrangement direction. As a result, the length of the print head in the relative movement direction can be shortened as compared with the configuration in which the first to fourth nozzle rows are arranged in the relative movement direction.

In the above printing apparatus, the length of the print head in the relative moving direction is preferably three times the length of the head chip in the relative moving direction.

According to this configuration, the length of the print head in the relative moving direction is three times the length of the head chip in the relative moving direction. As a result, the length of the print head in the relative movement direction can be minimized, so that the landing position of the ink droplets is less likely to vary, and the printed matter is less likely to come into contact with the print head.

In the above printing apparatus, the colors of the first ink droplet, the second ink droplet, and the third ink droplet are different, and it is preferable to select from cyan, magenta, and yellow.

According to this configuration, the first ink droplet, the second ink droplet, and the third ink droplet are selected from cyan, magenta, and yellow. For example, when the first ink droplet is cyan, the second ink droplet is magenta, and the third ink droplet is yellow, the streaks and color unevenness that occur when printing green by the cyan ink droplet and the yellow ink droplet are suppressed. can do.

It is preferable that the printing apparatus includes a selective printing unit that selectively performs a plurality of printing including the first printing and the second printing satisfying X = Y.

According to this configuration, the printing apparatus includes a selective printing unit that selectively performs a plurality of printing including a first printing satisfying X <Y and a second printing satisfying X = Y. By selecting the first printing by the selective printing unit, printing with suppressed streaks and color unevenness is performed in secondary color printing using the first and third nozzle rows having a plurality of distances between the nozzles. be able to.

The printing apparatus includes a printed matter type selection unit that accepts selection of the type of printed matter to be used for printing, and the selective printing unit is first limited to the type of printed matter received by the printed matter type selection unit. When the first type is printed and the type of the printed matter received by the printed matter type selection unit is the second type which is easier to dry than the first type, the second type is printed. It is preferable to print.

According to this configuration, the printing apparatus includes a printed matter type selection unit that accepts selection of the type of printed matter used for printing. The selective printing unit performs the first printing when the type of the printed matter received by the printed matter type selection unit is the first type, and the type of the printed matter received by the printed matter type selection unit is the second type. If is, the second printing is performed. For example, when the received printed matter is of the first type in which ink droplets are difficult to dry, that is, streaks and color unevenness are likely to occur, the selective printing unit performs the first printing. On the contrary, when the received printed matter is of the second type in which the ink droplets are easily dried, that is, the streaks and color unevenness are less likely to occur, the selective printing unit performs the second printing. As a result, in the printing of the secondary color using the first and third nozzle rows, it is possible to perform printing with suppressed streaks and color unevenness.

The printing apparatus includes a temperature sensor that detects a temperature, and the selective printing unit performs the first printing when the temperature detected by the temperature sensor satisfies the first temperature condition, and the first printing is performed. It is preferable to perform the second printing when the second temperature condition higher than the temperature condition of the above is satisfied.

According to this configuration, the printing device includes a temperature sensor that detects the temperature. The selective printing unit performs the first printing when the first temperature condition is satisfied, and performs the second printing when the second temperature condition higher than the first temperature condition is satisfied. For example, when the first temperature condition that the ink droplets are difficult to dry, that is, streaks and color unevenness are likely to occur is satisfied, the selective printing unit performs the first printing. As a result, it is possible to perform printing in which streaks and color unevenness are suppressed in secondary color printing using the first and third nozzle rows under temperature conditions where streaks and color unevenness are likely to occur.

The printing device includes a humidity sensor for detecting humidity, and the selective printing unit performs the first printing when the humidity detected by the humidity sensor satisfies the first humidity condition, and the first printing is performed. It is preferable to perform the second printing when the second humidity condition lower than the humidity condition of the above is satisfied.

According to this configuration, the printing device is equipped with a humidity sensor that detects humidity. The selective printing unit performs the first printing when the first humidity condition is satisfied, and performs the second printing when the second humidity condition lower than the first humidity condition is satisfied. For example, when the first humidity condition is satisfied in which the ink droplets are difficult to dry, that is, streaks and color unevenness are likely to occur, the selective printing unit performs the first printing. As a result, in the printing of the secondary color using the first and third nozzle rows, it is possible to perform printing with suppressed streaks and color unevenness.

The printing method of the present application is a printing method in which the print head and the object to be printed move relative to each other in a relative movement direction different from the arrangement direction of the nozzles in the nozzle row, and the print head is a first nozzle row and a second nozzle row. , And the number of the first nozzle row, the second nozzle row, and the third nozzle row is 2 or more, and ink droplets are formed on the same line along the relative movement direction. Of the plurality of nozzle rows for ejecting ink, the distance between the first nozzle row and the second nozzle row in the relative movement direction is constant, and the first nozzle row and the third nozzle row in the relative movement direction are constant. There are a plurality of distances from the ink droplets, and the first ink droplets when printing a secondary color by the first ink droplets ejected from the first nozzle row and the third ink droplets ejected from the third nozzle row. And when the overlapping ratio of the third ink droplets is set to X% and the secondary color is printed by the first ink droplets ejected from the first nozzle row and the second ink droplets ejected from the second nozzle row. When the overlapping ratio of the first ink droplet and the second ink droplet is Y%, the first printing satisfying the condition of X <Y is performed.

The printing apparatus to which this printing method is applied has a long distance and a short distance in the distance between the first nozzle row and the third nozzle row (hereinafter, also referred to as “distance between nozzles”) in the relative moving direction. When the distance between the nozzles is long on the same line along the relative movement direction, the first ink droplet ejected from the first nozzle row lands on the object to be printed, and then the third ink ejected from the third nozzle row. It takes a long time for the droplets to land on the printed material in duplicate. When the distance between the nozzles is short on the same line along the relative movement direction, the first ink droplet ejected from the first nozzle row lands on the object to be printed, and then the third ink ejected from the third nozzle row. The time it takes for the droplets to land on the printed material in duplicate is short. In a region where the distance between the nozzles is long, the first ink droplets are dried by the time the third ink droplets land, so that even if the first ink droplets and the third ink droplets overlap, the inks are less likely to bleed from each other. In a region where the distance between the nozzles is short, the third ink droplets land before the first ink droplets are dried. Therefore, when the first ink droplets and the third ink droplets overlap, the inks tend to bleed from each other. As a result, the difference in the color development of the secondary color causes the streaks and color unevenness along the relative movement direction to be visually recognized.

In this printing method, the first ink droplets ejected from the first nozzle row and the third ink droplets ejected from the third nozzle row overlap the first ink droplets and the third ink droplets when printing the secondary color. The ratio is set to X%, and the first ink droplets and the second ink droplets overlap when printing the secondary color by the first ink droplets ejected from the first nozzle row and the second ink droplets ejected from the second nozzle row. When the ratio of is Y%, the first printing satisfying the condition of X <Y is performed. That is, the printing method is that when printing the secondary color using the first nozzle row and the third nozzle row, the distance between the nozzles is constant, and the distance between the nozzles is constant. The overlap ratio of ink droplets is reduced as compared with the case of printing a secondary color using a second nozzle row, so that a difference in color development is less likely to occur. As a result, streaks and color unevenness that occur in secondary color printing using the first and third nozzle rows having a plurality of distances between the nozzles are suppressed. Therefore, it is possible to provide a printing method capable of suppressing the occurrence of streaks and color unevenness in the printing of secondary colors using the first and third nozzle rows having a plurality of distances between the nozzles.

The image processing apparatus of the present application has a first nozzle row, a second nozzle row, and a third nozzle row, and the number of the first nozzle row, the second nozzle row, and the third nozzle row is two or more. Of the plurality of nozzle rows that eject ink droplets on the same line along a relative movement direction different from the nozzle arrangement direction of the nozzle row, the first nozzle row and the second nozzle in the relative movement direction. The print data for a printing device provided with a print head having a constant distance from the row and having a plurality of distances between the first nozzle row and the third nozzle row in the relative movement direction is used as image data. An image processing device that is generated based on the above, and includes a halftone processing unit that performs halftone processing based on the image data, and the halftone processing unit includes a first ink droplet to be ejected from the first nozzle row. The overlapping ratio of the first ink droplets and the third ink droplets when printing the secondary color with the third ink droplets ejected from the third nozzle row is set to X%, and the first ink droplets are ejected from the first nozzle row. When the overlapping ratio of the first ink droplet and the second ink droplet when printing the secondary color by the first ink droplet and the second ink droplet ejected from the second nozzle row is set to Y%, It is characterized in that halftone processing satisfying the condition of X <Y is performed.

The printing device having this image processing device has a long distance and a short distance in the distance between the first nozzle row and the third nozzle row (hereinafter, also referred to as "distance between nozzles") in the relative moving direction. When the distance between the nozzles is long on the same line along the relative movement direction, the first ink droplet ejected from the first nozzle row lands on the object to be printed, and then the third ink ejected from the third nozzle row. It takes a long time for the droplets to land on the printed material in duplicate. When the distance between the nozzles is short on the same line along the relative movement direction, the first ink droplet ejected from the first nozzle row lands on the object to be printed, and then the third ink ejected from the third nozzle row. The time it takes for the droplets to land on the printed material in duplicate is short. In a region where the distance between the nozzles is long, the first ink droplets are dried by the time the third ink droplets land, so that even if the first ink droplets and the third ink droplets overlap, the inks are less likely to bleed from each other. In a region where the distance between the nozzles is short, the third ink droplets land before the first ink droplets are dried. Therefore, when the first ink droplets and the third ink droplets overlap, the inks tend to bleed from each other. As a result, the color development of the secondary color is different, so that streaks and color unevenness along the relative movement direction are visually recognized.

In this image processing apparatus, the first ink droplets and the third ink droplets overlap when printing the secondary color by the first ink droplets ejected from the first nozzle row and the third ink droplets ejected from the third nozzle row. The ratio of the first ink droplets and the second ink droplets when printing the secondary color by the first ink droplets ejected from the first nozzle row and the second ink droplets ejected from the second nozzle row is set to X%. When the duplication ratio is Y%, the processing satisfying the condition of X <Y is performed. That is, the image processing apparatus has a plurality of distances between the nozzles, and when printing a secondary color using the first nozzle row and the third nozzle row, the distance between the nozzles is constant, that is, the first nozzle row. A halftone process is performed in which the overlap ratio of ink droplets is reduced as compared with the case of printing a secondary color using the second nozzle row and the second nozzle row, and the difference in color development is less likely to occur. As a result, streaks and color unevenness that occur in secondary color printing using the first and third nozzle rows having a plurality of distances between the nozzles are suppressed. Therefore, it is possible to provide an image processing device capable of suppressing the occurrence of streaks and color unevenness in the printing of secondary colors using the first and third nozzle rows having a plurality of distances between the nozzles.

1 ... Printing device, 2 ... Inkjet printer, 3 ... Image processing device, 10 ... Controller, 11 ... CPU, 20 ... RAM, 30 ... Non-volatile memory, 41 ... Resolution conversion unit, 42 ... Color conversion unit, 43 ... Halftone Processing unit, 44 ... signal transmission unit, 50 ... mechanism unit, 53 ... paper feed mechanism, 60, 160 ... print head, 61 ... head chip, 64 ... nozzle, 67 ... ink droplets, 68 ... nozzle row, 73 ... operation panel , 100 ... Host device, 161a ... First head chip, 161b ... Second head chip, 161c ... Third head chip, A1, A2 ... Non-ejection area, AL1 ... Printing area, D1 ... Arrangement direction, D2 ... Relative movement direction , IM1 ... Printed image, L1, L2 ... Distance, ME1 ... Printed object, NL1 ... First nozzle row, NL2 ... Second nozzle row, NL3 ... Third nozzle row, NL4 ... Fourth nozzle row, SE1 ... Temperature sensor, SE2 ... Humidity sensor, U1 ... Selective printing unit, U2 ... Printed matter type selection unit.

Claims (12)

A printing device in which the print head and the printed matter move relative to each other in a relative movement direction different from the direction in which the nozzles in the nozzle row are arranged.
The print head has a first nozzle row, a second nozzle row, and a third nozzle row.
The number of the first nozzle row, the second nozzle row, and the third nozzle row is 2 or more.
Of a plurality of nozzle rows that eject ink droplets on the same line along the relative movement direction,
The distance between the first nozzle row and the second nozzle row in the relative moving direction is constant.
There are a plurality of distances between the first nozzle row and the third nozzle row in the relative moving direction.
Percentage of overlap between the first ink droplets and the third ink droplets when printing a secondary color by the first ink droplets ejected from the first nozzle row and the third ink droplets ejected from the third nozzle row. Is X%, and the first ink droplet and the second ink droplet when printing a secondary color by the first ink droplet ejected from the first nozzle row and the second ink droplet ejected from the second nozzle row. A printing apparatus characterized in that the first printing satisfying the condition of X <Y is performed when the overlapping ratio of ink droplets is Y%. The plurality of thresholds of the dither mask for determining printing with the third ink droplet satisfy the complementary relationship with the plurality of thresholds of the dither mask for determining printing with the first ink droplet. The printing apparatus according to claim 1. The print head comprises a first nozzle row, a second nozzle row, and a plurality of head chips having the third nozzle row.
In the head chip, the first nozzle row and the second nozzle row are arranged in the relative movement direction, and one of the first nozzle row and the second nozzle row and the third nozzle row The printing apparatus according to claim 1 or 2, wherein the nozzles are arranged in the arrangement direction of the nozzles. The printing according to claim 3, wherein the head chip further has a fourth nozzle row, and the third nozzle row and the fourth nozzle row are arranged in the relative movement direction. Device. The printing apparatus according to claim 3 or 4, wherein the length of the print head in the relative moving direction is three times the length of the head chip in the relative moving direction. Any of claims 1 to 5, wherein the first ink droplet, the second ink droplet, and the third ink droplet have different colors and are selected from cyan, magenta, and yellow. The printing apparatus according to item 1. One of claims 1 to 6, further comprising a selective printing unit that selectively performs a plurality of printing including the first printing and the second printing satisfying X = Y. The printing device described in. A printed matter type selection unit that accepts selection of the type of printed matter used for printing is provided.
The selective printing unit performs the first printing when the type of the printed matter received by the printed matter type selecting unit is the first type, and the printed matter type selected unit accepts the printed matter. The printing apparatus according to claim 7, wherein the second type of printing is performed when the type is a second type that is easier to dry than the first type. Equipped with a temperature sensor that detects the temperature
The selective printing unit performs the first printing when the temperature detected by the temperature sensor satisfies the first temperature condition, and when the second temperature condition higher than the first temperature condition is satisfied. The printing apparatus according to claim 7, wherein the second printing is performed. Equipped with a humidity sensor that detects humidity,
The selective printing unit performs the first printing when the humidity detected by the humidity sensor satisfies the first humidity condition, and when the second humidity condition lower than the first humidity condition is satisfied, the selective printing unit performs the first printing. The printing apparatus according to claim 7, wherein the second printing is performed. This is a printing method in which the print head and the printed matter move relative to each other in a relative movement direction different from the direction in which the nozzles in the nozzle row are arranged.
The print head has a first nozzle row, a second nozzle row, and a third nozzle row.
The number of the first nozzle row, the second nozzle row, and the third nozzle row is 2 or more.
Of a plurality of nozzle rows that eject ink droplets on the same line along the relative movement direction,
The distance between the first nozzle row and the second nozzle row in the relative moving direction is constant.
There are a plurality of distances between the first nozzle row and the third nozzle row in the relative moving direction.
Percentage of overlap between the first ink droplets and the third ink droplets when printing a secondary color by the first ink droplets ejected from the first nozzle row and the third ink droplets ejected from the third nozzle row. Is X%, and the first ink droplet and the second ink droplet when printing a secondary color by the first ink droplet ejected from the first nozzle row and the second ink droplet ejected from the second nozzle row. A printing method characterized in that the first printing satisfying the condition of X <Y is performed when the overlapping ratio of ink droplets is Y%. It has a first nozzle row, a second nozzle row, and a third nozzle row, and the number of the first nozzle row, the second nozzle row, and the third nozzle row is two or more, and the nozzles in the nozzle row. Of a plurality of nozzle rows that eject ink droplets on the same line along a relative movement direction different from the arrangement direction of, the distance between the first nozzle row and the second nozzle row in the relative movement direction is constant. An image processing device that generates print data for a printing device having a print head having a plurality of distances between the first nozzle row and the third nozzle row in the relative movement direction based on the image data. And
A halftone processing unit that performs halftone processing based on the image data is provided.
The halftone processing unit has the first ink droplets and the first ink droplets when printing a secondary color by the first ink droplets ejected from the first nozzle row and the third ink droplets ejected from the third nozzle row. The overlap ratio of the three ink droplets is set to X%, and the second color is printed by the first ink droplets ejected from the first nozzle row and the second ink droplets ejected from the second nozzle row. An image processing apparatus characterized in that halftone processing satisfying the condition of X <Y is performed when the overlapping ratio of one ink drop and the second ink drop is Y%.

Images