JP2011131610A - Printer and printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance a degree of freedom of designing intervals between nozzle arrays. <P>SOLUTION: A controller can make a dot formation operation and a conveyance operation performed by a plurality of printing modes. If a printing image is composed of dots formed to all pixels, when each printing mode is carried out, each dot train is formed by a predetermined number of nozzles in accordance with the printing mode, dot trains are arranged in a predetermined direction at predetermined intervals in accordance with the printing mode, and also a dot train formed by any of the printing modes has dots formed by nozzles of each nozzle array. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a printing apparatus and a printing method including a plurality of nozzle rows.

  2. Related Art Inkjet printers that perform printing by intermittently discharging ink are known as recording apparatuses that record images on various media such as paper, cloth, and film. An inkjet printer alternately repeats a dot forming operation for ejecting ink from a nozzle that moves in a moving direction (also referred to as a main scanning direction) and a conveying operation for conveying a medium in a conveying direction (also referred to as a sub-scanning direction) The image is printed on.

  In such an ink jet printer, the recording speed can be increased by increasing the number of nozzles that eject ink. However, it is difficult to manufacture the head if the number of nozzles in one nozzle row is increased. Therefore, it has been proposed to increase the number of nozzles by providing a plurality of nozzle rows at different positions in the transport direction (see, for example, Patent Document 1).

International Publication No. 2004/080719 Pamphlet

  When providing a plurality of nozzle rows at different positions in the transport direction, it is desirable that there is a degree of freedom in setting the intervals between the nozzle rows. In addition, it is preferable that the same configuration can support a plurality of print modes.

  An object of the present invention is to increase the degree of freedom in designing the interval between nozzle rows when a plurality of nozzle rows are provided at different positions in the transport direction.

  A main invention for achieving the above object includes: a carriage that includes a plurality of nozzle rows including a plurality of nozzles arranged in a predetermined direction, the plurality of nozzle rows being provided at different positions with respect to the predetermined direction, and a carriage that is movable in the movement direction; A transport mechanism for transporting the medium along the predetermined direction; a dot forming operation for ejecting ink from the nozzles during movement of the carriage to form a dot row along the movement direction on the medium; and And a controller that alternately repeats the transport operation for transporting in the predetermined direction and configures the print image by arranging a plurality of dot rows in the predetermined direction, and the controller is configured to perform the printing in a plurality of print modes. It is possible to perform the dot forming operation and the carrying operation, and the print image is configured by dots formed on all the pixels. When each printing mode is performed, each dot row is formed by a predetermined number of nozzles according to the printing mode, and each dot row is arranged in the predetermined direction at a predetermined interval according to the printing mode. The dot rows formed by the printing mode also have dots formed by the nozzles of each nozzle row.

  Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

It is the 1st perspective view for showing the outline of an ink jet printer. It is a 2nd perspective view for showing the outline | summary of an inkjet printer. It is a block diagram for demonstrating the structure of a printing system. It is explanatory drawing which shows the arrangement | sequence of the nozzle in the lower surface of each head. 5A and 5B are explanatory diagrams of interlaced printing (reference example). 6A and 6B are explanatory diagrams of overlap printing (reference example). It is explanatory drawing of the overlap printing in case the overlap number M is 4 (reference example). FIG. 8A is an explanatory diagram of a configuration of a plurality of nozzle arrays of a comparative example. FIG. 8B is an explanatory diagram of intervals between a plurality of nozzle rows of a comparative example. FIG. 8C is an explanatory diagram of overlap printing by a plurality of nozzle arrays of a comparative example. It is explanatory drawing about arrangement | positioning of the two heads in 1st Embodiment. FIG. 10A and FIG. 10B are explanatory diagrams illustrating how dots are formed in each head when M = 2 in the first embodiment. It is explanatory drawing of the mode of dot formation in the case of M = 2 in 1st Embodiment. 12A to 12C are explanatory diagrams illustrating how dots are formed when the interval between two nozzle rows is changed. FIG. 13A and FIG. 13B are explanatory diagrams showing how dots are formed in each head when M = 4 in the first embodiment. It is explanatory drawing of the mode of the dot formation in the case of M = 4 in 1st Embodiment. FIG. 15A is a table for explaining the three printing modes of the first embodiment. FIG. 15B is a table for explaining the four print modes of the first embodiment. It is explanatory drawing about arrangement | positioning of the four heads in 2nd Embodiment. FIG. 17A and FIG. 17B are explanatory diagrams illustrating how dots are formed in each head when M = 4 in the second embodiment. It is explanatory drawing of the mode of dot formation in the case of M = 4 in 2nd Embodiment. FIG. 19A is a table for explaining the three print modes of the second embodiment. FIG. 19B is a table for explaining the four print modes of the second embodiment.

=== Summary of disclosure ===
At least the following matters will become clear from the description of the present specification and the accompanying drawings.

A plurality of nozzle rows comprising a plurality of nozzles arranged in a predetermined direction, the plurality of nozzle rows being provided at different positions with respect to the predetermined direction, and a carriage movable in the movement direction;
A transport mechanism for transporting the medium along the predetermined direction;
A dot forming operation for ejecting ink from the nozzles during movement of the carriage to form a dot row along the moving direction on the medium and a transport operation for transporting the medium in the predetermined direction are alternately repeated. A controller that configures the print image by arranging a plurality of the dot rows in the predetermined direction,
The controller can perform the dot formation operation and the transport operation in a plurality of printing modes,
When the print image is composed of dots formed on all pixels When each print mode is performed, each dot row is formed by a predetermined number of nozzles according to the print mode, and the print mode is followed. The dot rows are arranged in the predetermined direction at predetermined intervals,
A printing apparatus, wherein a dot row formed by any of the printing modes includes a dot formed by the nozzle of each nozzle row.
According to such a printing apparatus, the freedom degree of design of the space | interval of each nozzle row can be raised.

  In such a printing apparatus, an interval in the transport direction between a nozzle on the upstream side in the transport direction of a nozzle row and a nozzle on the downstream side in the transport direction of another nozzle row may be in the transport direction in the plurality of print modes. It is desirable to be an integer multiple of the least common multiple of each dot pitch. Thereby, it becomes possible to form dots in the dot rows formed by any of the printing modes by the nozzles of each nozzle row.

  The printing apparatus may further include a belt for moving the carriage in the movement direction, and an interval between two nozzle arrays on one of the upstream side and the downstream side in the transport direction with respect to the belt may be smaller than the belt. It is also preferable that the distance between the nozzle row on the upstream side in the transport direction and the nozzle row on the downstream side in the transport direction with respect to the belt is shorter. Since the degree of freedom of design is high, this configuration is particularly effective.

  In such a printing apparatus, in any of the printing modes, it is desirable that the predetermined number is an integer multiple of the number of the nozzle rows. As a result, at least one nozzle that can form each dot row is present in each head.

  In such a printing apparatus, when the print image is configured by dots formed in all the pixels, each nozzle row includes the dot in a fraction of the nozzle row of all the pixels. It is desirable to form. Thereby, it is possible to prevent the influence of the specific nozzle row from being strongly reflected in the print image.

  In such a printing apparatus, it is preferable that the number of ejection permitted nozzles permitted to eject the ink in each nozzle row is the same. As a result, at least one nozzle that can form each dot row is present in each head.

  In this printing apparatus, a value obtained by dividing the predetermined number by the number of the nozzle rows is M ′, the number of the discharge permitted nozzles of each nozzle row is N ′, the dot pitch in the transport direction is D, When the nozzle pitch of the nozzle row is k × D, M ′ is an integer, N ′ / M ′ is an integer, N ′ / M ′ and k are relatively prime, and the transport amount is (N It is desirable that '/ M') × D. Thereby, it becomes possible to form dots in the dot rows formed by any of the printing modes by the nozzles of each nozzle row.

  In this printing apparatus, the carriage is provided with a plurality of heads, each head has a nozzle row for each color, and the plurality of heads are provided at different positions with respect to the predetermined direction. Accordingly, it is preferable that the plurality of nozzles of the same color are provided at different positions with respect to the predetermined direction. Thus, the number of nozzles can be easily increased by using a plurality of heads having the same configuration.

Prepare a plurality of nozzle rows provided at different positions with respect to a predetermined direction,
A dot forming operation in which ink is ejected from a plurality of nozzles arranged in the predetermined direction of each nozzle row while the plurality of nozzle rows are moving in the movement direction, and a dot row along the movement direction is formed on the medium; It is a printing method in which a conveying operation for conveying along the predetermined direction is alternately repeated, and a plurality of the dot rows are arranged in the predetermined direction to form the print image,
When forming dots on all pixels in a certain printing mode,
Each dot row is formed by a predetermined number of nozzles according to the certain printing mode, and each dot row is formed so that there are dots formed by the nozzles of each nozzle row, and the certain printing mode is set. The dot rows are arranged in the predetermined direction at predetermined intervals according to the above,
When forming dots on all pixels in another print mode,
Each dot row is formed by a predetermined number of nozzles according to the different printing mode, and each dot row is formed such that there are dots formed by the nozzles of each nozzle row, so that the different printing A printing method, wherein the dot rows are arranged in the predetermined direction at predetermined intervals according to a mode.
According to such a printing method, the freedom degree of design of the space | interval of each nozzle row can be raised.

=== Configuration of Printing System ===
Next, an embodiment of a printing system will be described with reference to the drawings.

  FIG. 1 is a first perspective view for illustrating an outline of an inkjet printer. FIG. 2 is a second perspective view for illustrating the outline of the ink jet printer. FIG. 3 is a block diagram for explaining the configuration of the printing system.

  The printing system 100 includes a printer 1, a computer 110, a display device 120, an input device (not shown), and the like. The printer 1 is a printing apparatus that prints an image on a medium such as paper, cloth, or film. The computer 110 is communicably connected to the printer 1 and outputs print data corresponding to the image to be printed to the printer 1 in order to cause the printer 1 to print an image.

  A printer driver is installed in the computer 110. The printer driver is a program for causing the display device 120 to display a user interface and converting image data output from the application program into print data. This printer driver is recorded on a recording medium (computer-readable recording medium) such as a flexible disk FD or a CD-ROM. Alternatively, the printer driver can be downloaded to the computer 110 via the Internet. In addition, this program is comprised from the code | cord | chord for implement | achieving various functions.

  The printer 1 of the present embodiment is a large format print for printing an image on a wide roll paper or a relatively large single-sheet printing paper such as JIS standard A-line 0 sheet or B-line 0 sheet. It is a printing device for use. The printer 1 includes a transport unit 20, a carriage unit 30, a head unit 40, a detector group 50, a controller 60, and a drive signal generation unit 70. The printer 1 that has received print data from the computer 110, which is an external device, controls each unit (the conveyance unit 20, the carriage unit 30, and the head unit 40) by the controller 60. The controller 60 controls each unit based on the print data received from the computer 110 and prints an image on paper. The situation in the printer 1 is monitored by a detector group 50, and the detector group 50 outputs a detection result to the controller 60. The controller 60 controls each unit based on the detection result output from the detector group 50.

  The transport unit 20 is for transporting a medium (for example, paper S) in a predetermined direction (hereinafter referred to as a transport direction). The transport unit 20 includes a transport motor 21, a transport roller 22, a driven roller 23, a platen 24, and a roll paper holding unit 25. The conveyance motor 21 rotates the conveyance roller 22. When the transport roller 22 rotates, the roll paper S sandwiched between the transport roller 22 and the driven roller 23 is transported in the transport direction. The platen 24 is for supporting the roll paper being conveyed. The roll paper holding unit 25 is for holding the rolled roll paper S in a rotatable manner. When the roll paper S of the roll paper holding unit 25 is pulled by the conveyance roller 22, the roll paper S is supplied to the platen 24 side.

  The carriage unit 30 is for moving the head in the movement direction. The carriage unit 30 includes a carriage 31, a carriage motor 32, a first pulley 33 and a second pulley 34, a belt 35, an upper guide 36A, and a lower guide 36B. The carriage 31 is guided by the upper guide 36A and the lower guide 36B so as to be movable in the movement direction. When the carriage motor 32 rotates, power is transmitted to the carriage 31 by the first pulley, the second pulley, and the belt 35, and the carriage 31 moves in the moving direction.

  The head unit 40 has a plurality of heads. In the figure, four heads 41A to 41D are provided. In the following description, the first head 41A, the second head 41B, the third head 41C, and the fourth head 41D are arranged in order from the upper head. Since the first head 41A to the fourth head 41D are provided on the carriage 31, when the carriage 31 moves in the movement direction, the first head 41A to the fourth head 41D also move in the movement direction. Then, each head intermittently ejects ink while moving in the moving direction, whereby dot lines (raster lines) along the moving direction are formed on the paper. Each head is provided with a piezo element group 412 and a head control unit 413 for controlling the piezo element group 412. A plurality of nozzles (described later) are formed on the head, and the head controller 413 controls the drive of each piezo element, thereby controlling the ejection of ink from each nozzle.

  The detector group 50 includes a linear encoder 51, a rotary encoder (not shown), and the like. The linear encoder 51 is for detecting the position of the carriage 31 in the moving direction, and includes a detection unit 51A provided on the carriage 31 and a scale 51B provided with a slit. A rotary encoder (not shown) detects the rotation amount of the transport roller 22. Based on the detection result of the rotary encoder, the amount of paper transport is detected.

  The controller 60 is a control unit (control unit) for controlling the printer. The controller 60 has a CPU 61 and a memory 62. The CPU 61 is an arithmetic processing unit for controlling the entire printer. The memory 62 is for securing an area for storing a program of the CPU 61, a work area, and the like, and includes storage elements such as a RAM and an EEPROM. The CPU 61 controls each unit according to a program stored in the memory 62.

<About the nozzle configuration of the head>
FIG. 4 is an explanatory diagram showing the arrangement of nozzles on the lower surface of each head. A black ink nozzle row K, a cyan ink nozzle row C, a magenta ink nozzle row M, and a yellow ink nozzle row Y are formed on the lower surface of each head. Each nozzle row includes a plurality of nozzles (180 in this embodiment) that are ejection openings for ejecting ink of each color.

  The plurality of nozzles in each nozzle row are aligned at a constant interval (nozzle pitch: k · D) along the transport direction. Here, D is the minimum dot pitch in the carrying direction (that is, the interval at the highest resolution of dots formed on the paper S). K is an integer of 1 or more. For example, when the nozzle pitch is 180 dpi (1/180 inch) and the dot pitch in the transport direction is 720 dpi (1/720 inch), k = 4.

  The nozzles in each nozzle row are assigned a smaller number as the nozzles on the downstream side (# 1 to # 180). That is, the nozzle # 1 is located downstream of the nozzle # 180 in the transport direction. Each nozzle is provided with an ink chamber (not shown) and a piezoelectric element. By driving the piezo element, the ink chamber expands and contracts, and ink droplets are ejected from the nozzles.

  In the following description, the nozzle row belonging to the first head 41A is referred to as a “first nozzle row”, and the nozzle row belonging to the second head 41B is referred to as a “second nozzle row”. The nozzle row belonging to 41C is referred to as a “third nozzle row”, and the nozzle row belonging to the fourth head 41D is referred to as a “fourth nozzle row”.

=== Printing method with one head (reference example) ===
First, a printing method when there is one head will be described.

<Interlaced printing>
5A and 5B are explanatory diagrams of interlaced printing. FIG. 5A shows the position of the head (or nozzle row) and the state of dot formation in pass 1 to pass 4, and FIG. 5B shows the position of the head and the state of dot formation in pass 1 to pass 5. .

  On the left side of the figure, the position of the head (or nozzle row) with respect to the paper is shown. For convenience of explanation, only one color nozzle row of the nozzle rows for each color is shown, and the number of nozzles in the nozzle row is also reduced (here, 12). The nozzles indicated by black circles in the figure are nozzles that are allowed to eject ink (discharge permitted nozzles). On the other hand, nozzles indicated by white circles are nozzles that are prohibited from ejecting ink (ejection prohibited nozzles). For convenience of explanation, the head (or nozzle row) is depicted as moving with respect to the paper, but this figure shows the relative position of the head and the paper. The paper is moved in the transport direction.

On the right side of the figure, dots formed on the paper are shown. For convenience of explanation, it is assumed that dots are formed in all pixels here. However, in reality, there are pixels in which dots are not formed depending on the contents of the print image (for example, the sky cloud area or the human In the skin region, etc., there are many pixels where dots are not formed).
Also, for convenience of explanation, each nozzle is shown as having only a few dots (circles in the figure), but in reality, ink droplets are ejected intermittently from nozzles that move in the direction of movement. Therefore, a large number of dots are arranged in the moving direction. This row of dots is also called a raster line. A dot indicated by a black circle is a dot formed in the last pass, and a dot indicated by a white circle is a dot formed in a previous pass. Note that “pass” refers to an operation (dot formation operation) in which ink is ejected from a moving nozzle to form dots. Each pass is alternately performed with an operation (conveying operation) for conveying the paper in the conveying direction.

  “Interlaced printing” means a printing method in which k is 2 or more and a raster line that is not recorded is sandwiched between raster lines that are recorded in one pass. For example, in the printing method in FIGS. 5A and 5B, three raster lines are sandwiched between raster lines formed in one pass.

  In interlace printing, each time the paper is transported in the transport direction by a constant transport amount F, each nozzle records a raster line immediately above the raster line recorded in the immediately preceding pass. In order to perform recording with a constant conveyance amount in this way, (1) the number N (integer) of ejection-permitted nozzles is relatively prime to k, and (2) the conveyance amount F is N · D. It is a condition that it is set.

  In the figure, the nozzle row has 12 nozzles arranged along the transport direction. Since the nozzle pitch k of the nozzle row is 4, in order to satisfy the condition for performing interlaced printing, “N and k are relatively prime”, all the nozzles are not used, and 11 nozzles (nozzle # 1) are used. ~ Nozzle # 11) is used. In addition, since 11 nozzles are used, the paper is carried by a carry amount of 11 · D. As a result, dots are formed on the paper at a dot interval of 720 dpi (= D) using a nozzle row having a nozzle pitch of 180 dpi (4 · D). Since the actual number of nozzles (180) is greater than 11, the actual transport amount (179 · D) is greater than 11 · D.

<Overlap printing (2 passes)>
6A and 6B are explanatory diagrams of overlap printing. 6A shows the position of the head and the state of dot formation in pass 1 to pass 4, and FIG. 6B shows the position of the head and the state of dot formation in pass 1 to pass 8.

  “Overlap printing” means a printing method in which a raster line is formed by a plurality of nozzles. For example, in the printing method in FIGS. 6A and 6B, each raster line is formed by two nozzles.

In overlap printing, each time the paper is transported at a constant transport amount F in the transport direction, each nozzle intermittently forms dots every few dots. In another pass, by forming dots so that the intermittent dots already formed by other nozzles are complemented (filling between the dots), one raster line is formed by a plurality of nozzles. It is formed. When one raster line is formed in M passes in this way, it is defined as “overlap number M”.
6A and 6B, since each nozzle intermittently forms dots every other dot, dots are formed in odd-numbered pixels or even-numbered pixels for each pass. Since one raster line is formed by two nozzles, the overlap number M = 2.

In overlap printing, in order to perform recording with a constant conveyance amount, (1) N / M is an integer, (2) N / M is relatively prime to k, (3) The condition is that the carry amount F is set to (N / M) · D.
In FIG. 6A and FIG. 6B, the nozzle row has 12 nozzles arranged along the transport direction. However, since the nozzle pitch k of the nozzle row is 4, in order to satisfy the condition for performing overlap printing, “N / M and k are relatively prime”, all the nozzles are not used and 10 nozzles are used. Nozzle is used. Further, since ten nozzles are used, the paper is transported at a transport amount of 5 · D. As a result, for example, using a nozzle row with a nozzle pitch of 180 dpi (4 · D), dots are formed on the paper at a dot interval of 720 dpi (= D).

  6A and 6B, in pass 1, each nozzle forms dots on odd pixels, in pass 2, each nozzle forms dots on even pixels, and in pass 3, each nozzle forms dots on odd pixels. In 4, each nozzle forms a dot at an even pixel. That is, in the first four passes, dots are formed in the order of odd pixel-even pixel-odd pixel-even pixel. In the latter four passes (pass 5 to pass 8), dots are formed in the reverse order of the first four passes, and dots are formed in the order of even pixel-odd pixel-even pixel-odd pixel. . The dot formation order after pass 9 is the same as the dot formation order from pass 1.

<Overlap printing (4 passes)>
FIG. 7 is an explanatory diagram of overlap printing when the overlap number M is four. That is, the printing method forms one raster line in four passes. According to this printing method, one raster line is formed by four nozzles.

In this printing method, twelve nozzles serve as ejection permission nozzles, and the paper is carried by a carry amount of 3 · D in the carrying process performed during each pass. When each nozzle forms a dot in each pass, each nozzle forms a dot at a rate of one pixel per four pixels (when dots are formed in all pixels).
Thus, the number of overlaps is not limited to two.

=== Printing Method for Multiple Heads (Comparative Example) ===
Before describing the printing method of the present embodiment in which printing is performed with a plurality of heads, a printing method of a comparative example will be described. Here, in order to simplify the description, it is assumed that the carriage 31 is provided with two heads. Also, for convenience of explanation, only one nozzle row of the nozzle rows for each color is shown, and the number of nozzles in each nozzle row is also reduced (here, 6).

  FIG. 8A is an explanatory diagram of a configuration of a plurality of nozzle arrays of a comparative example. FIG. 8B is an explanatory diagram of intervals between a plurality of nozzle rows of a comparative example. FIG. 8C is an explanatory diagram of overlap printing by a plurality of nozzle arrays of a comparative example.

  In the comparative example, the two nozzle rows (first nozzle row 411A and second nozzle row 411B) are the same color nozzle rows belonging to different heads (the first nozzle row 411A is the nozzle row belonging to the first head 41A). The second nozzle row 411B is a nozzle row belonging to the second head 41B). The first nozzle row 411A and the second nozzle row 411B are actually arranged so as to be shifted in the moving direction, but here, for convenience of explanation, they are arranged side by side in the transport direction (at the same position with respect to the moving direction). Is placed).

  Each of the first nozzle row 411A and the second nozzle row 411B has six nozzles. The nozzle pitch in each nozzle row is 4 · D (k = 4), as in the above-described reference example.

  The head of the comparative example is provided so that the interval between the nozzle rows (specifically, the interval between the nozzle # 6A of the first nozzle row 411A and the nozzle # 1B of the second nozzle row 411B) is 9 · D. . That is, the head of the comparative example is provided so that the interval between the nozzle rows is equal to the sum of the conveyance amount (5 · D) and the nozzle pitch (4 · D). Thereby, the dots formed by the nozzles of the second nozzle row 411B in a certain pass (pass i) and the dots formed by the nozzles of the first nozzle row 411A in the next pass (pass i + 1) have an interval in the transport direction. It will be formed to be 4 · D.

  That is, according to the head of the comparative example, the first nozzle row 411A in pass i + 1 and the second nozzle row 411B in pass i are carried by a predetermined carry amount (5 · D), so that It functions as 12 nozzles arranged at a nozzle pitch of 4 · D (see FIG. 8B).

  In the comparative example, two nozzle rows function as 12 nozzles arranged in a pseudo manner with a nozzle pitch of 4 · D. Therefore, when performing overlap printing with an overlap number M of 2, Ten nozzles of the nozzles are used (10 nozzles become ejection-allowing nozzles and 2 nozzles become ejection-inhibiting nozzles). In addition, since ten nozzles are used, the paper is transported by a transport amount of 5 · D during overlap printing (see FIG. 8C).

In the case of the comparative example, the interval between the two nozzle rows (the interval between the discharge permitted nozzle # 6A of the first nozzle row 411A and the discharge permitted nozzle # 1B of the second nozzle row 411B) needs to be designed to be a specific interval. is there. Specifically, the interval between two nozzle rows needs to be the sum of an integral multiple of the carry amount and the nozzle pitch.
For this reason, in the printing method as in the comparative example, there are large design restrictions on the nozzle row spacing.

=== First Embodiment ===
Also in the description of the first embodiment, it is assumed that two heads are provided on the carriage 31 in order to simplify the description. The case where there are four heads will be described in the second embodiment.

<(1) Arrangement of two heads>
FIG. 9 is an explanatory diagram regarding the arrangement of two heads. As described above, the black ink nozzle row K, the cyan ink nozzle row C, the magenta ink nozzle row M, and the yellow ink nozzle row Y are formed on the lower surface of each head.

  Each head is displaced in the moving direction. For this reason, for a certain color, the nozzle row of the first head 41A and the nozzle row of the second head 41B are arranged at different positions in the movement direction. For this reason, if the nozzle row of the first head 41A and the nozzle row of the second head 41B simultaneously eject ink, the dots formed by the nozzle row of the first head 41A and the nozzle row of the second head 41B are formed. The formed dots are formed at different positions in the moving direction. However, since the carriage 31 can move in the moving direction, the same position in the moving direction can be obtained by shifting the ink discharge timing of the nozzle row of the first head 41A and the ink discharge timing of the nozzle row of the second head 41B. Can form dots. Therefore, in the description to be described later, the nozzle rows of the same color are arranged in the transport direction.

  As shown in the figure, the nozzle # 180 of the nozzle row of the first head 41A and the nozzle # 1 of the nozzle row of the second head 41B are separated by an interval L in the transport direction. This interval L only needs to satisfy the condition of an integral multiple of the printing resolution (dot pitch D in the transport direction). That is, in the present embodiment, there are few design restrictions on the interval between the nozzle rows (the interval between the first head 41A and the second head 41B).

  Next, a printing method using the head arranged in this way will be described.

<(2) When the overlap number M is 2>
First, the case where the overlap number M is 2 will be described. That is, a printing method for forming one raster line in two passes will be described. According to this printing method, one raster line is formed by two nozzles. In particular, according to the present embodiment, as will be apparent from the following description, the dots formed by the first nozzle row 411A and the dots formed by the second nozzle row 411B are included in any raster line. There is.

  In the following description, only the nozzle row of one color among the nozzle rows for each color is shown. In addition, the nozzle row of the first head 41A and the nozzle row of the second head 41B are actually arranged so as to be shifted in the moving direction. However, in the following description, for convenience of explanation, they are arranged side by side in the transport direction. (Arranged at the same position in the moving direction).

First, how dots are formed in each head (or each nozzle row) will be described.
FIG. 10A and FIG. 10B are explanatory diagrams illustrating how dots are formed in each head when M = 2 in the first embodiment. FIG. 10A shows the position of the head and the state of dot formation in pass 1 to pass 4, and FIG. 10B shows the position of the head and the state of dot formation in pass 1 to pass 5.

  In the first embodiment, the discharge permitted nozzles when M = 2 are the nozzles # 1 to # 11 as in the interlaced printing of the reference example of FIGS. 5A and 5B. That is, the number of discharge permission nozzles of each head is eleven. Further, in the first embodiment, the carry amount F when M = 2 is 11 · D, similarly to the interlaced printing in the reference example of FIGS. 5A and 5B.

Each nozzle forms dots intermittently every other dot as in the overlap printing of M = 2 in the reference example of FIGS. 6A and 6B. Therefore, each nozzle has an odd-numbered pixel or an even-numbered pixel for each pass. Dots are formed. That is, each nozzle forms only half of the dots compared to the interlaced printing of the reference example of FIGS. 5A and 5B. For this reason, in the printing method shown in FIGS. 10A and 10B, the number N of ejection permitted nozzles (the number of ejection permitted nozzles of each head) and the carry amount F are the same as those in the reference example in FIGS. As a result, it is impossible to complete a raster line continuously arranged in the transport direction as shown in FIGS. 5A and 5B.
However, according to the printing method shown in FIGS. 10A and 10B, dots can be formed in a checkered pattern by one head. That is, one head can form exactly half of the dots constituting the print image.

Next, how dots are formed by two heads will be described.
FIG. 11 is an explanatory diagram showing how dots are formed when M = 2 in the first embodiment.

  On the left side of the figure, the position of the head (or nozzle row) with respect to the paper is shown. Specifically, it is shown that the first nozzle row 411A and the second nozzle row 411B separated by the distance L move relative to the paper by the carry amount F (actually, the pass and the pass). The paper is transported by a transport amount F with respect to the nozzle row between the two).

  A hatched portion on the right side in the drawing indicates a range in which raster lines are continuously arranged in the transport direction. Specifically, the position of the nozzle # 1 of the first nozzle row 411A in pass 4 (the position of the discharge-permitted nozzle on the most downstream side in the carrying direction of the nozzle row on the upstream side in the carrying direction) and the second nozzle row 411B in the pass 11 A plurality of raster lines are continuously arranged in the transport direction between the nozzle # 11 (the position of the discharge permitted nozzle on the most upstream side in the transport direction of the nozzle row downstream in the transport direction).

In the lower right part of the figure, the state of dot formation in a part of the shaded area (area corresponding to 8 raster lines) is shown. Circles indicate dots formed by ink ejected from the nozzles of the first nozzle row 411A. Triangle marks indicate dots formed by ink ejected from the nozzles of the second nozzle row 411B.
As described above, each head can form dots in a checkered pattern (see FIGS. 10A and 10B). For this reason, if the first nozzle row 411A forms dots so as to complement between the dots formed by the second nozzle row 411B, dots can be formed on all the pixels by the two heads. In addition, in order to form the checkered pattern dot in the same manner in both the first nozzle row 411A and the second nozzle row 411B, it is necessary to set the same number of ejection permission nozzles in each nozzle row.

  12A to 12C are explanatory diagrams illustrating how dots are formed when the interval between two nozzle rows is changed.

  FIG. 12A shows how dots are formed when the interval between two nozzle rows is L. FIG. Here, dots forming a certain raster line are painted black. The black circles are dots formed by the nozzle #i of the first nozzle row 411A in a certain pass (referred to as pass X). The black triangle is assumed to be a dot formed by the nozzle #j of the second nozzle row 411B in another pass (referred to as pass Y). That is, in pass X, the nozzle #i of the first nozzle row 411A forms dots in even pixels, and in the pass Y, the nozzle #j of the second nozzle row 411B forms dots in odd pixels.

FIG. 12B shows how dots are formed when the interval between two nozzle rows is changed to L + D. That is, the interval between the nozzle rows is separated by the dot pitch D compared to the case of FIG. 12A. Also in this drawing, dots formed by the nozzle #i of the first nozzle row 411A in the pass X are indicated by black circles. Further, dots formed by the nozzle #j of the second nozzle row 411B in pass Y are indicated by black triangles.
As shown in FIG. 12B, the black triangles constitute raster lines adjacent to the upstream side in the transport direction of the raster lines constituted by black circles. Further, as shown in the drawing, in pass Y, the nozzle #j of the second nozzle row 411B forms dots in even pixels instead of odd pixels (black triangles are in even pixels). Note that a raster line including a black circle is configured by dots (white triangles in the drawing) formed by another nozzle of the second nozzle row 411B in another pass.

FIG. 12C shows how dots are formed when the interval between two nozzle rows is changed to L + 2D. That is, the interval between the nozzle rows is separated by twice the dot pitch (2D) compared to the case of FIG. 12A. Also in this drawing, dots formed by the nozzle #i of the first nozzle row 411A in the pass X are indicated by black circles. Further, dots formed by the nozzle #j of the second nozzle row 411B in pass Y are indicated by black triangles.
As shown in FIG. 12C, the black triangles constitute two raster lines upstream of the raster line constituted by the black circles in the transport direction. Further, as shown in the drawing, in pass Y, the nozzle #j of the second nozzle row 411B forms dots in odd pixels (black triangles are in odd pixels).

  As shown in FIGS. 12A to 12C, even if the interval between the two nozzle rows is changed, the first nozzle row 411A forms dots so as to complement the dots formed by the second nozzle row 411B. Then, dots can be formed on all the pixels by the two heads. However, the interval L between the two nozzle rows needs to satisfy the condition of an integral multiple of the printing resolution (dot pitch D in the transport direction).

  By the way, for example, when the first nozzle row 411A is in a pass for forming dots in odd pixels, the second nozzle row 411B forms dots in odd pixels according to the interval L between the two nozzle rows, or even pixels In some cases, dots are formed. For example, the second nozzle row 411B in pass Y forms dots at odd pixels in FIG. 12A, but forms dots at even pixels in FIG. 12B. In order to do this, it is necessary to be able to set the ink discharge timing of the first nozzle row 411A and the ink discharge timing of the second nozzle row 411B separately. For this purpose, in this embodiment, a drive signal generation unit is provided for each head (see FIG. 3). Each drive signal generator generates a drive signal for odd pixels when the corresponding nozzle row forms dots in odd pixels, and drives for even pixels when the corresponding nozzle row forms dots in even pixels. Generate a signal.

According to the above printing method, half of the dots constituting each raster line are formed by the first nozzle row 411A, and the remaining half of the dots are formed by the second nozzle row 411B. In other words, in each raster line, the dots formed by the first nozzle row 411A and the dots formed by the second nozzle row 411B are in a ratio of 1: 1.
On the other hand, for example, the first nozzle row 411A forms dots at a rate of 1 pixel per 4 pixels, and the second nozzle row 411B forms dots at a rate of 3 pixels per 4 pixels, thereby configuring each raster line. You can also In other words, in each raster line, the dots formed by the first nozzle row 411A and the dots formed by the second nozzle row 411B can be in a ratio of 1: 3. However, in this case, the mechanical characteristics of the second nozzle row 411B are easily reflected in each raster line, and if the nozzles in the second nozzle row 411B are clogged and there is a defect in the dots, the image quality deteriorates. Is remarkable.

<(3) When the overlap number M is 4>
Next, a case where the overlap number M is 4 will be described. That is, a printing method for forming one raster line in four passes will be described. According to this printing method, one raster line is formed by four nozzles. In particular, according to the present embodiment, in any raster line, there are dots formed by the first nozzle row 411A and dots formed by the second nozzle row 411B.

First, how dots are formed in each head will be described.
13A and 13B are explanatory diagrams illustrating how dots are formed when M = 4 in the first embodiment. 13A shows the position of the head and the state of dot formation in pass 1 to pass 4, and FIG. 13B shows the position of the head and the state of dot formation in pass 1 to pass 8.

  In the first embodiment, the discharge permitted nozzles when M = 4 are nozzle # 1 to nozzle # 10, as in the overlap printing (M = 2) of the reference example of FIGS. 6A and 6B. That is, the number of discharge permission nozzles of each head is ten. In the first embodiment, the carry amount F when M = 4 is 5 · D, similarly to the interlaced printing (M = 2) in the reference example of FIGS. 6A and 6B.

Each nozzle forms dots at a rate of one pixel per four pixels, as in the overlap printing of M = 4 in the reference example of FIG. That is, each nozzle forms only half of the dots compared to the overlap printing of M = 4 in the reference example of FIG. For this reason, in the printing method shown in FIGS. 10A and 10B, the number N of permitted discharge nozzles (the number of permitted discharge nozzles of each head) and the carry amount F are the same as those in the reference example of FIG. As shown in FIGS. 6A and 6B, it is impossible to complete a raster line continuously arranged in the transport direction.
However, according to the printing method shown in FIGS. 13A and 13B, dots can be formed in a checkered pattern by one head. That is, one head can form exactly half of the dots constituting the print image.

Next, how dots are formed by two heads will be described.
FIG. 14 is an explanatory diagram showing how dots are formed in each head when M = 4 in the first embodiment. Similar to FIG. 11, the hatched portion on the right side of the drawing indicates a range in which raster lines are continuously arranged in the transport direction. In the lower right part of the figure, the state of dot formation in a part of the shaded area (area corresponding to eight raster lines) is shown. Circles indicate dots formed by ink ejected from the nozzles of the first nozzle row 411A. Triangle marks indicate dots formed by ink ejected from the nozzles of the second nozzle row 411B.

  As described above, each head can form dots in a checkered pattern (see FIGS. 10A and 10B). For this reason, if the first nozzle row 411A forms dots so as to complement between the dots formed by the second nozzle row 411B, dots can be formed on all the pixels by the two heads. In addition, in order to form the checkered pattern dot in the same manner in both the first nozzle row 411A and the second nozzle row 411B, it is necessary to set the same number of ejection permission nozzles in each nozzle row.

  Although not described in detail, almost the same as in FIGS. 12A to 12C described above, even if the interval between the two nozzle rows is changed, the space between the dots formed by the second nozzle row 411B is complemented. In addition, if the first nozzle row 411A forms dots, dots can be formed on all pixels by two heads. However, the interval L between the two nozzle rows needs to satisfy the condition of an integral multiple of the printing resolution (dot pitch D in the transport direction).

<(4) Printing conditions>
In the case where there is one head as in the reference example, in order to perform recording with a constant conveyance amount, (1) N / M is an integer, and (2) N / M is relatively prime to k. And (3) the transport amount F is set to (N / M) · D. In the case of interlaced printing, it may be considered that the overlap number M is 1.

  Here, a value obtained by dividing the overlap number M by the number of nozzle rows is defined as M ′, and the number of discharge permitted nozzles in each nozzle row is defined as N ′. Then, in the printing conditions of the reference example, if M is replaced with M ′ and N is replaced with N ′, the printing conditions of the present embodiment are met.

That is, the printing conditions of this embodiment are summarized as follows (the printing conditions of the second embodiment described later are also the same).
(Condition 1) N ′ of each nozzle row is the same (Condition 2) M ′ is an integer (Condition 3) N ′ / M ′ is an integer (Condition 4) N ′ / M ′ is (Condition 5) The transport amount F is set to (N ′ / M ′) · D. (Condition 6) L is an integral multiple of the dot pitch D.

By satisfying these conditions, for each raster line, at least one nozzle capable of forming the raster line is present in each head. That is, this makes it possible to form dots on any raster line by the nozzles of each nozzle row.
In order to satisfy the condition 2 (M ′ is an integer), the overlap number M needs to be greater than or equal to the number of heads (the number of nozzle rows).

<(5) Relationship Between Multiple Print Modes and Interval L>
FIG. 15A is a table for explaining the three printing modes of the first embodiment. In the description here, each nozzle row is assumed to be composed of 180 nozzles.

  The print mode refers to a state when dots are formed. Even if the resolution is the same, if the dot formation order is different, the print mode will be different. The printing modes 1 to 3 in the table are different printing modes because the states when forming dots are different. The controller 60 controls each unit in accordance with a program stored in the memory, thereby realizing each of print mode 1 to print mode 3 in the table.

  In order to realize the printing mode 1 to the printing mode 3, it is necessary to satisfy the above conditions 1 to 6 in any printing mode. In particular, in order to satisfy condition 6 (L is an integer multiple of the dot pitch D) in any printing mode, the interval L is the least common multiple of the printing resolution (dot pitch D in the transport direction) of each printing mode. Must be an integer multiple of. Here, since the dot pitch D in print mode 1 is 1/720 inch, the dot pitch D in print mode 2 is 1/720 inch, and the dot pitch in print mode 3 is 1/1440 inch, The interval L between the nozzle rows may be an integral multiple of 1/720 inch. In addition, satisfying the above-described condition 2 in any printing mode means that the number of overlaps M in any printing mode is an integral multiple of the number of heads.

FIG. 15B is a table for explaining the four print modes of the first embodiment. Compared to FIG. 15A, a print mode 4 is added.
In print mode 4, the dot pitch is 1/540 inch. In such a case, the interval L is an integral multiple of 1/180 inch.

=== Printing Method of Second Embodiment ===
Next, a second embodiment in which four heads are provided on the carriage 31 will be described.

<(1) Arrangement of four heads>
FIG. 16 is an explanatory diagram regarding the arrangement of four heads. As described above, the black ink nozzle row K, the cyan ink nozzle row C, the magenta ink nozzle row M, and the yellow ink nozzle row Y are formed on the lower surface of each head.

  As shown in the drawing, the nozzle # 180 of the nozzle row of the first head 41A and the nozzle # 1 of the nozzle row of the second head 41B are separated by a distance L12 in the transport direction. Further, the nozzle # 180 of the nozzle row of the second head 41B and the nozzle # 1 of the nozzle row of the third head 41C are separated by an interval L23 in the transport direction. Further, the nozzle # 180 of the nozzle row of the third head 41C and the nozzle # 1 of the nozzle row of the fourth head 41D are separated by a distance L34 in the transport direction. The interval L12, the interval L23, and the interval L34 only need to satisfy the condition of an integral multiple of the printing resolution (dot pitch D in the transport direction). That is, in this embodiment, there are few design restrictions about the space | interval of a nozzle row.

  Note that the interval L12, the interval L23, and the interval L34 do not need to be the same, and may be different as long as the conditions are satisfied. In particular, the distance L12 and the distance L34 are desirably short from the viewpoint of miniaturization of the printer, but the distance L23 cannot be shortened because of the belt 35 (see FIGS. 1 and 2). For this reason, the interval L12 and the interval L34 are designed to be shorter than the carry amount F, for example, and the interval L23 is designed to be longer than the carry amount F, for example.

  Next, a printing method using the head arranged in this way will be described.

<(2) When the overlap number M is 4>
Here, a case where the overlap number M is 4 will be described. That is, a printing method for forming one raster line in four passes will be described. According to this printing method, one raster line is formed by four nozzles. In particular, according to the present embodiment, as will be apparent from the following description, there are dots formed by each nozzle row in any raster line.

  In the following description, only the nozzle row of one color among the nozzle rows for each color is shown. In addition, the nozzle rows of the same color of each head are actually arranged so as to be shifted in the moving direction, but in the following description, for convenience of explanation, they are arranged side by side in the transport direction (the same regarding the moving direction). Is placed in position).

First, how dots are formed in each head will be described.
FIG. 17A and FIG. 17B are explanatory diagrams illustrating how dots are formed in each head when M = 4 in the second embodiment. 17A shows the position of the head and the state of dot formation in pass 1 to pass 4, and FIG. 17B shows the position of the head and the state of dot formation in pass 1 to pass 5.

  In the second embodiment, the discharge permitted nozzles when M = 4 are the nozzles # 1 to # 11 as in the interlaced printing of the reference example of FIG. That is, the number of discharge permission nozzles of each head is eleven. In the second embodiment, the carry amount F when M = 4 is 11 · D, similarly to the interlaced printing in the reference example of FIG.

Each nozzle forms dots at a rate of one pixel per four pixels, as in the overlap printing of M = 4 in the reference example of FIG. That is, each nozzle forms only ¼ dot compared to the interlaced printing of the reference example of FIGS. 5A and 5B. For this reason, in the printing method shown in FIGS. 17A and 17B, the number N of ejection-permitted nozzles (number of ejection-permitted nozzles in each head) and the carry amount F are the same as those in the reference example in FIGS. 5A and 5B. As a result, it is impossible to complete a raster line continuously arranged in the transport direction as shown in FIG.
However, according to the printing method shown in FIGS. 17A and 17B, one-quarter dot of the entire dots constituting the print image can be formed by one head.

Next, how dots are formed by four heads will be described.
FIG. 18 is an explanatory diagram showing how dots are formed when M = 4 in the second embodiment. Similar to FIG. 11 and FIG. 14, the hatched portion on the right side of the drawing indicates a range in which raster lines are continuously arranged in the transport direction. In the lower right part of the figure, the state of dot formation in a part of the shaded area (area corresponding to eight raster lines) is shown. Circles indicate dots formed by ink ejected from the nozzles of the first nozzle row 411A. Triangle marks indicate dots formed by ink ejected from the nozzles of the second nozzle row 411B. Diamond marks (◇) indicate dots formed by the ink ejected from the nozzles of the third nozzle row 411C. Square marks (□) indicate dots formed by the ink ejected from the nozzles of the fourth nozzle row 411D.

  As described above, each head can form one-fourth of the dots constituting the print image (see FIGS. 17A and 17B). Therefore, if the dots are formed so that the first nozzle row 411A to the fourth nozzle row 411D complement each other, the dots can be formed on all the pixels by the four heads. In addition, in order for the first nozzle row 411A to the fourth nozzle row 411D to form dots in the same manner, it is necessary to set the same number of ejection permitted nozzles in each nozzle row.

  Although not described in detail, dots are formed on all pixels by four heads even if the distance L12, the distance L23, and the distance L34 are changed, as in FIGS. 12A to 12C described above. Can do. However, all of the interval L12, the interval L23, and the interval L34 need to satisfy the condition of an integral multiple of the printing resolution (dot pitch D in the transport direction).

According to the above printing method, in each raster line, the dots formed by the first nozzle row 411A to the fourth nozzle row 411D are in a ratio of 1: 1: 1: 1.
In contrast, for example, the first nozzle row 411A forms dots at a rate of 1 pixel per 8 pixels, the second nozzle row 411B forms dots at a rate of 3 pixels per 8 pixels, and the third nozzle row 411C and the first nozzle row 411C Each raster line can also be configured by forming dots at a ratio of one pixel to four pixels by each of the four nozzle rows 411D. In other words, in each raster line, the dots formed by the first nozzle row 411A to the fourth nozzle row 411D can be in a ratio of 1: 3: 2: 2. However, in this case, the mechanical characteristics of the second nozzle row 411B are easily reflected in each raster line, and if the nozzles in the second nozzle row 411B are clogged and there is a defect in the dots, the image quality deteriorates. Is remarkable.

<(3) Printing conditions>
In addition, although description is abbreviate | omitted here when the number of overlaps is 8, even if it is a case where four heads are used like 2nd Embodiment, the following conditions should just be satisfy | filled.
(Condition 1) N ′ of each nozzle row is the same (Condition 2) M ′ is an integer (Condition 3) N ′ / M ′ is an integer (Condition 4) N ′ / M ′ is (Condition 5) The transport amount F is set to (N ′ / M ′) · D. (Condition 6) L is an integral multiple of the dot pitch D.

<(4) Relationship Between Multiple Printing Modes and Interval L>
FIG. 19A is a table for explaining the three print modes of the second embodiment. In the description here, each nozzle row is assumed to be composed of 180 nozzles.

  In order to realize the printing mode 1 to the printing mode 3, it is necessary to satisfy the above conditions 1 to 6 in any printing mode. In particular, in order to satisfy condition 6 (L is an integer multiple of the dot pitch D) in any printing mode, the interval L is the least common multiple of the printing resolution (dot pitch D in the transport direction) of each printing mode. Must be an integer multiple of. Here, since the dot pitch D in print mode 1 is 1/720 inch, the dot pitch D in print mode 2 is 1/720 inch, and the dot pitch in print mode 3 is 1/1440 inch, The interval L between the nozzle rows may be an integral multiple of 1/720 inch. In addition, satisfying the above-described condition 2 in any printing mode means that the number of overlaps M in any printing mode is an integral multiple of the number of heads. For this reason, since the number of heads is 2 in the first embodiment described above, the minimum value of the overlap number M is 2, but in the second embodiment, the number of heads is 4, so the minimum value of the overlap number M is 4

  FIG. 19B is a table for explaining the four print modes of the second embodiment. Compared to FIG. 19A, a print mode 4 is added. In the printing mode 4, since the dot pitch is 1/540 inch, in this case, the interval L is set to an integral multiple of 1/180 inch.

=== Other Embodiments ===
Although a printer or the like as one embodiment has been described, the above embodiment is for facilitating understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof.

<About nozzle>
In the above-described embodiment, ink is ejected using a piezoelectric element. However, the method for discharging the liquid is not limited to this. For example, other methods such as a method of generating bubbles in the nozzle by heat may be used.

=== Summary ===
(1) According to the above-described embodiment, the printer 1 includes the carriage 31 that is movable in the movement direction, the conveyance unit (corresponding to the conveyance mechanism) that conveys the medium along the predetermined direction, and the raster line (dot line). And a controller 60 that alternately repeats a dot forming operation and a conveying operation (see FIGS. 1 to 3). Since the carriage 31 is provided with a plurality of heads, the carriage 31 is integrally provided with a plurality of nozzle rows. Each nozzle row is composed of a plurality of nozzles arranged in the transport direction (corresponding to a predetermined direction) (see FIG. 4). Further, each nozzle row is provided at a different position in the transport direction (see FIGS. 9, 11, 14, 16, and 18).

  The controller 60 can perform a dot forming operation and a carrying operation in a plurality of printing modes. For example, in the case of the printing mode 1 in FIG. 15A, the controller 60 performs a dot forming operation for forming dots on odd or even pixels and a transport operation for transporting the paper S with a transport amount of 179 · D (178/720 inches). Will be performed alternately.

By the way, in a printing method in which a dot forming a raster line is formed only by a specific nozzle in a certain printing mode, the design restriction on the interval between two nozzle rows becomes large. This is because if there is a change in the interval between two nozzle rows, there may be no nozzle that can form the raster line.
Therefore, it is desirable that at least one nozzle that can form each raster line exists in each head even if the interval between the two nozzle rows is changed. This is because, by doing so, dots can be formed in all pixels even if the interval between two nozzle rows is changed, for example, as shown in FIGS. 12A to 12C.

In the present embodiment, there are dots formed by the nozzles of each nozzle row in the raster lines formed by any printing mode. For example, in the first embodiment, dots (bottom right circles in FIG. 14) formed by the nozzles of the first nozzle row 411A and the second nozzles are formed on any raster line formed by any printing mode. There are dots formed by the nozzles in the row 411B (Δ mark at the lower right in FIG. 14). In the second embodiment, the dots formed by the nozzles of the nozzle rows of the first nozzle row 411A to the fourth nozzle row 411D (on the right side of FIG. 18) on any raster line formed by any printing mode. There are lower circle, triangle, diamond (◇), square (□). In other words, in the present embodiment, the dots formed by the dots of each nozzle row are on each raster line because at least one nozzle capable of forming each raster line exists in each head. Because it is.
Accordingly, if the dots formed by the dots in each nozzle row are arranged in each raster line, the interval between the two nozzle rows can be easily changed.

(2) In the above-described embodiment, nozzle # 180 (corresponding to the nozzle on the upstream side in the transport direction) of a certain nozzle row (for example, the first nozzle row 411A) and nozzles of another nozzle row (for example, the second nozzle row 411B) # 1 (corresponding to a nozzle on the downstream side in the transport direction) with respect to the transport direction (see L in FIG. 9 or see L12, L23, or L34 in FIG. 16) is a dot in the transport direction in a plurality of print modes. It is an integral multiple of the least common multiple of the pitch D. For example, if only print mode 1 to print mode 3 in FIG. 15A is performed, the interval L is an integral multiple of 1/720 inch, but if print mode 4 in FIG. 15B is further performed, the interval L is 1/180. An integer multiple of inches.
As a result, in any printing mode, at least one nozzle that can form each raster line is present in each head. In other words, this makes it possible to form dots with the nozzles of each nozzle row on the raster line formed in any printing mode.

(3) In the above-described embodiment, the power is transmitted from the belt 35 so that the carriage 31 moves (see FIGS. 1 and 2). Since the nozzle row cannot be opposed to the paper in a place where the belt 35 is present, and because the belt 35 is provided at the center of the carriage 31, the first head 41A, the second head 41B, and the third head 41C. The fourth head 41D is separated from the fourth head 41D (see FIG. 16). As a result, for example, the distance L12 between the first nozzle row 411A of the first head 41A and the second nozzle row 411B of the second head 41B (corresponding to two nozzle rows on the downstream side in the transport direction from the belt) is third. The distance between the third nozzle row 411C of the head 41C (corresponding to the nozzle row upstream of the belt in the transport direction) and the second nozzle row 411B of the second head 41B (corresponding to the nozzle row downstream of the belt in the transport direction). It becomes shorter than L23.
In the present embodiment, since the degree of freedom in designing the interval between two nozzle arrays is high, a plurality of heads capable of executing a plurality of print modes can be configured even with such a configuration.

  (4) In the above-described embodiment, in any printing mode, the overlap number M (corresponding to a predetermined number) is an integral multiple of the number of heads (that is, the number of nozzle rows of the same color) (FIG. 15A and FIG. 15). (See FIG. 19A). Thereby, the above-mentioned condition 2 (M ′ is an integer (that is, the value obtained by dividing the overlap number M by the number of nozzle rows is an integer) can be satisfied, and the nozzles that can form each raster line are satisfied. There will be at least one in each head.

(5) In the above-described embodiment, each nozzle row forms a dot in one pixel of the number of nozzle rows among all the pixels. For example, in the case of the first embodiment in which the number of nozzle rows is 2, each nozzle row forms a dot on half of all the pixels constituting the print image. Further, in the case of the second embodiment in which the number of nozzle rows is 4, each nozzle row forms a dot in 1/4 of all the pixels constituting the print image.
Thereby, it is possible to prevent the influence of the specific nozzle row from being strongly reflected in the print image.

  (6) In the above-described embodiment, the number N ′ of ejection permission nozzles is the same in each nozzle row. As a result, the above condition 1 can be satisfied, and at least one nozzle that can form each raster line exists in each head.

  (7) When the above conditions 1 to 5 are satisfied, at least one nozzle that can form each raster line exists in each head, and the dots formed by the dots in each nozzle row are the same. Can be on each raster line.

  (8) In the above-described embodiment, a plurality of heads are provided on the carriage, and each head has a nozzle row for each color. Then, by providing the plurality of heads at different positions with respect to the predetermined direction, the plurality of nozzles of the same color are provided at different positions with respect to the transport direction. Thus, the number of nozzles can be easily increased by using a plurality of heads having the same configuration.

  (9) If all the components of the above-described embodiment are provided, all the effects can be achieved. However, if only the effect of increasing the degree of design freedom is obtained, not all the components of the above-described embodiment are required.

  DESCRIPTION OF SYMBOLS 1 Printer, 20 Conveyance unit, 21 Conveyance motor, 22 Conveyance roller, 23 Driven roller, 24 Platen, 25 Roll paper holding part, 30 Carriage unit, 31 Carriage, 32 Carriage motor, 33 1st pulley, 34 2nd pulley, 35 Belt, 36A upper guide, 36B lower guide, 40 head unit, 41 head, 41A first head, 41B second head, 41C third head, 41D fourth head, 411 nozzle row, 411A first nozzle row, 411B second Nozzle array, 411C 3rd nozzle array, 411D 4th nozzle array, 412 piezo element group, 413 head controller, 50 detector group, 51 linear encoder, 60 controller, 61 CPU, 62 memory, 100 printing system, 110 computer 1 20 Display device.

Claims (10)

A plurality of nozzle rows comprising a plurality of nozzles arranged in a predetermined direction, the plurality of nozzle rows being provided at different positions with respect to the predetermined direction, and a carriage movable in the movement direction;
A transport mechanism for transporting the medium along the predetermined direction;
A dot forming operation for ejecting ink from the nozzles during movement of the carriage to form a dot row along the moving direction on the medium and a transport operation for transporting the medium in the predetermined direction are alternately repeated. A controller that configures the print image by arranging a plurality of the dot rows in the predetermined direction,
The controller can perform the dot formation operation and the transport operation in a plurality of printing modes,
When the print image is composed of dots formed on all pixels,
When each printing mode is performed, each dot row is formed by a predetermined number of nozzles according to the printing mode, and each dot row is arranged in the predetermined direction at a predetermined interval according to the printing mode,
A printing apparatus, wherein a dot row formed by any of the printing modes includes a dot formed by the nozzle of each nozzle row. The printing apparatus according to claim 1,
An interval in the transport direction between a nozzle on the upstream side in the transport direction of a nozzle row and a nozzle on the downstream side in the transport direction of another nozzle row is a least common multiple of each dot pitch in the transport direction in the plurality of printing modes. A printing apparatus characterized by being an integer multiple. The printing apparatus according to claim 2,
A belt for moving the carriage in the moving direction;
The interval between the two nozzle rows on the upstream side or the downstream side in the transport direction with respect to the belt is such that the nozzle row on the upstream side in the transport direction with respect to the belt and the nozzle on the downstream side in the transport direction with respect to the belt. A printing apparatus characterized by being shorter than the interval between the columns. The printing apparatus according to any one of claims 1 to 3,
In any of the printing modes, the predetermined number is an integer multiple of the number of the nozzle rows. The printing apparatus according to any one of claims 1 to 4,
When the print image is composed of dots formed on all pixels, each nozzle row forms the dot on a pixel that is a fraction of the nozzle row among all the pixels. Printing device to do. The printing apparatus according to any one of claims 1 to 5,
The printing apparatus according to claim 1, wherein the number of ejection permitted nozzles permitted to eject the ink is the same in each nozzle row. The printing apparatus according to claim 6,
A value obtained by dividing the predetermined number by the number of the nozzle rows is M ′, the number of the discharge permitted nozzles of each nozzle row is N ′, the dot pitch in the transport direction is D, and the nozzle pitch of each nozzle row is k. When xD,
M ′ is an integer,
N ′ / M ′ is an integer,
N ′ / M ′ and k are relatively prime,
A printing apparatus characterized in that the carry amount is (N ′ / M ′) × D. The printing apparatus according to any one of claims 1 to 7,
The carriage is provided with a plurality of heads,
Each of the heads has a nozzle row for each color,
A plurality of the heads are provided at different positions with respect to the predetermined direction, whereby a plurality of the nozzles of the same color are provided at different positions with respect to the predetermined direction. A plurality of nozzle rows comprising a plurality of nozzles arranged in a predetermined direction, the plurality of nozzle rows being provided at different positions with respect to the predetermined direction, and a carriage movable in the movement direction;
A transport mechanism for transporting the medium along the predetermined direction;
A dot forming operation for ejecting ink from the nozzles during movement of the carriage to form a dot row along the moving direction on the medium and a transport operation for transporting the medium in the predetermined direction are alternately repeated. A controller that configures the print image by arranging a plurality of the dot rows in the predetermined direction,
(1) The controller can perform the dot forming operation and the transport operation in a plurality of printing modes,
When the print image is composed of dots formed on all pixels,
When each printing mode is performed, each dot row is formed by a predetermined number of nozzles according to the printing mode, and each dot row is arranged in the predetermined direction at a predetermined interval according to the printing mode,
In the dot rows formed by any of the printing modes, there are dots formed by the nozzles of each nozzle row,
(2) An interval in the transport direction between a nozzle on the upstream side in the transport direction of a nozzle row and a nozzle on the downstream side in the transport direction of another nozzle row is a dot pitch in the transport direction in the plurality of print modes. An integer multiple of the least common multiple,
(3) further comprising a belt for moving the carriage in the moving direction;
The interval between the two nozzle rows on the upstream side or the downstream side in the transport direction with respect to the belt is such that the nozzle row on the upstream side in the transport direction with respect to the belt and the nozzle on the downstream side in the transport direction with respect to the belt. Shorter than the distance between the columns,
(4) In any of the printing modes, the predetermined number is an integer multiple of the number of the nozzle rows,
(5) When the print image is configured by dots formed on all pixels, each nozzle row forms the dot on a pixel that is a fraction of the nozzle row of all the pixels,
(6) The number of ejection permitted nozzles permitted to eject the ink in each nozzle row is the same,
(7) A value obtained by dividing the predetermined number by the number of the nozzle rows is M ′, the number of the discharge permitted nozzles of each nozzle row is N ′, the dot pitch in the transport direction is D, and the nozzles of each nozzle row When the pitch is k × D,
M ′ is an integer,
N ′ / M ′ is an integer,
N ′ / M ′ and k are relatively prime,
The carry amount is (N ′ / M ′) × D. (8) The carriage is provided with a plurality of heads,
Each of the heads has a nozzle row for each color,
A plurality of the heads are provided at different positions with respect to the predetermined direction, whereby a plurality of the nozzles of the same color are provided at different positions with respect to the predetermined direction (9). Prepare a plurality of nozzle rows provided at different positions with respect to a predetermined direction,
A dot forming operation in which ink is ejected from a plurality of nozzles arranged in the predetermined direction of each nozzle row while the plurality of nozzle rows are moving in the movement direction, and a dot row along the movement direction is formed on the medium; It is a printing method in which a conveying operation for conveying along the predetermined direction is alternately repeated, and a plurality of the dot rows are arranged in the predetermined direction to form the print image,
When forming dots on all pixels in a certain printing mode,
Each dot row is formed by a predetermined number of nozzles according to the certain printing mode, and each dot row is formed so that there are dots formed by the nozzles of each nozzle row, and the certain printing mode is set. The dot rows are arranged in the predetermined direction at predetermined intervals according to the above,
When forming dots on all pixels in another print mode,
Each dot row is formed by a predetermined number of nozzles according to the different printing mode, and each dot row is formed such that there are dots formed by the nozzles of each nozzle row, so that the different printing A printing method, wherein the dot rows are arranged in the predetermined direction at predetermined intervals according to a mode.

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