JP2003237046A - Ink jet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deterioration of an image due to difference of hue of dots printed on a print medium. <P>SOLUTION: A two array head 51 having a nozzle array 61 corresponding to yellow (Y) and a nozzle array 62 corresponding to dark yellow (DY), a two array head 52 having a nozzle array 63 corresponding to magenta (M) and a nozzle array 64 corresponding to light magenta (LM), a two array head 53 having a nozzle array 65 corresponding to cyan (C) and a nozzle array 66 corresponding to light cyan (LC), and a two array head 54 having a nozzle array 67 corresponding to black (K) and a nozzle array 68 corresponding to yellow (Y) are arranged contiguously to each other in the direction substantially orthogonal to the longitudinal direction of the nozzle arrays 61-68. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet printer that prints an image on a print medium that is conveyed.

[0002]

2. Description of the Related Art Ink jet printers print by spraying liquid ink onto paper. Some inkjet printers include a head unit in which a plurality of nozzle rows each including a large number of nozzles are arranged adjacent to each other in a direction orthogonal to the longitudinal direction. Here, the plurality of nozzle rows provided in the head unit can respectively eject inks of different colors. As described above, since the head unit of the printer has the nozzle rows corresponding to the inks of different colors, it is possible to print an image using the inks of multiple colors.

Further, in such a printer, the head unit is capable of reciprocating along the width direction of the paper so that inks of different colors are superposed on each other during the forward movement and the backward movement. It is general that dots are printed on the paper by being ejected onto the paper. At this time, the color order of the nozzle rows from the tip end side when the head unit is moving forward and the color order of the nozzle row from the tip end side when the head unit is moving backward are opposite to each other. Therefore, in both dots printed when the head unit moves forward and backward, the order in which the inks of different colors are superimposed is opposite.

[0004]

However, when the head unit is moved forward and backward, the dots printed with different colors of ink in different orders are
Often does not show exactly the same color. Therefore, in such a case, color unevenness occurs between these dots, and the image printed on the paper deteriorates.

Therefore, a main object of the present invention is to provide an ink jet printer capable of suppressing deterioration of an image due to a difference in hue of dots printed on a print medium. .

[0006]

To achieve the above object, in an ink jet printer according to a first aspect of the invention, three or more nozzle rows each including a large number of nozzles are substantially orthogonal to the longitudinal direction of the nozzle row. Head units arranged on the print medium such that the head units are arranged adjacent to each other with respect to the direction, and the head units reciprocate in a direction substantially orthogonal to the longitudinal direction of the nozzle row while facing the print medium. A driving unit for moving the head unit relative to each other, and only the nozzles included in the nozzle row selected from the three or more nozzle rows belonging to the head unit are used for forward and backward movements by the driving unit. Ink is ejected at any time during movement, and the selected nozzle row is the outermost one among the selected nozzle rows. A pair of first nozzle rows capable of ejecting inks of the same specific color, and an ink of a different color different from the specific color between the pair of first nozzle rows. It is characterized in that two types of one or more possible second nozzle rows are provided.

According to the first aspect of the present invention, when the head unit is moved forward and backward, the plural colors of ink ejected from the nozzles included in the selected nozzle row of the head unit onto the print medium are first described. At least one of the color of the ejected ink and the color of the last ejected ink can be the same. Therefore, even when dots printed by superposing inks of different colors in different orders are adjacent to each other, it is possible to suppress the occurrence of color unevenness between these dots. This suppresses deterioration of the image printed on the print medium due to the difference in the hue of the dots.

In the ink jet printer according to the second aspect, the head units are arranged in the same direction.
A plurality of heads each having one nozzle row are arranged adjacent to each other in a direction substantially orthogonal to the longitudinal direction of the nozzle row, and a pair of the first nozzle rows is included in the plurality of heads. There is one for each of the two outermost heads, and at least one of the pair of first nozzle rows is the outermost nozzle row among all the nozzle rows belonging to the head unit. All the nozzle rows between the nozzle rows are selected as the second nozzle row.

Here, in order to improve the quality of the image printed on the print medium, the color of ink that can be ejected from the head unit may be increased. At this time, if the head unit is integrally molded, it is necessary to newly manufacture a head unit capable of ejecting ink of more colors.

Further, in the head unit, a plurality of two-row heads in which two nozzle rows each including a large number of nozzles are arranged in the same direction are arranged adjacent to each other in a direction orthogonal to the longitudinal direction of the nozzle rows. There was something that was done. Here, for example, when the head unit is a combination of three two-row heads, printing with six color inks can be performed.

Here, a case will be considered in which one nozzle row corresponding to inks of colors other than the above six colors is added to the head unit to change it to one capable of ejecting seven colors of ink. As a method of adding one nozzle row, it is conceivable to newly manufacture a one-row head in which one nozzle row including a large number of nozzles is arranged and add it to a head unit capable of ejecting six colors of ink. To be However, it is often costly to manufacture such a one-row head anew, and an existing two-row head is added to a head unit capable of ejecting ink of six colors, and the added two-row head is added. It may be preferable to use only one of the two nozzle rows of the head.

As described above, according to the second aspect, the head unit is configured by arranging a plurality of heads each having two nozzle rows arranged in the same direction. Therefore, the head unit is designed. Greater freedom.
That is, the head unit capable of ejecting ink of a plurality of colors can be easily manufactured by changing the number of the heads to be combined.

An ink jet printer according to a third aspect of the invention is characterized in that the pair of first nozzle rows is the outermost two nozzle rows of all the nozzle rows belonging to the head unit. is there.

According to the third aspect, since the ink is ejected from all the nozzle rows arranged in the head unit to perform the printing, the waste of the nozzle rows is eliminated, and the printing is efficiently performed using the multicolor ink. be able to.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an inkjet printer according to an embodiment of the present invention. FIG. 2 is a diagram showing a schematic configuration of the print head unit. FIG. 3 is a diagram showing a schematic configuration of a nozzle row arranged in the head block.

The ink jet printer 1 shown in FIG.
Has a transport table 4, a transport roller unit 5, an inkjet printing unit 6, a pressure roller unit 7, a cutting unit 8, and a discharge roller unit 9 in a substantially rectangular parallelepiped housing 30. Further, in the housing 30, a long sheet 2 having a winding portion 2a wound in a roll shape is formed.
Are arranged. The winding portion 2a of the paper 2 is held by a drum 3 which is rotatable around an axis center. Further, as will be described later, the operation of each part of the inkjet printer 1 is performed by the controller 2 arranged in the housing 30.
Controlled by 0.

The transport roller unit 5 includes the controller 2
A pair of drive rollers driven by a motor 25 controlled by 0, for conveying the sheet 2 before being cut by the cutting unit 8. That is, the transport roller unit 5 unwinds the paper 2 from the winding portion 2 a, transports the paper 2 on the transport base 4 to the downstream side, and sequentially passes the inkjet printing unit 6 and the cutting unit 8.

The ink jet printing unit 6 has a print head portion 11 and a suction fan 12. As shown in FIG. 2, the print head unit 11 includes a head block 44.
And a carriage 4 for supporting the head block 44.
5 and the carriage 45 in the main scanning direction (width direction of the paper 2)
And a moving mechanism 49 for reciprocating along. Further, the moving mechanism 49 includes an annular belt 46 for holding the carriage 45, and rollers 47 and 48 around which the annular belt 46 is stretched.

The head block 44 is a flat member, and has two rows of heads 51 to 51 in which two nozzle rows are arranged on the surface (the lower surface in FIG. 2) facing the paper 2.
54 (see FIG. 3) is provided. While the head block 44 is held by the carriage 45,
Since the heads 51 to 54 reciprocate along the direction perpendicular to the sub-scanning direction, the two-row heads 51 to 54 reciprocate between one end and the other end of the paper 2 along the main scanning direction.

Here, the two-row heads 51 to 54 have a structure shown in FIG.
As shown in, two nozzle rows are arranged in the same direction. That is, the two-row head 51 includes the nozzle row 61 corresponding to yellow (Y) and the nozzle row 62 corresponding to dark yellow (DY), and the two-row head 52 includes the nozzle corresponding to magenta (M). The row 63 and the nozzle row 64 corresponding to light magenta (LM) are provided, and the two-row head 53 has the nozzle row 65 corresponding to cyan (C) and the nozzle row 66 corresponding to light cyan (LC). The two-row head 54 has a nozzle row 67 and yellow (Y) corresponding to black (K).
Nozzle array 68 corresponding to

The two-row heads 51 to 54 are arranged adjacent to each other in the direction substantially orthogonal to the longitudinal direction of the nozzle rows 61 to 68 provided therein. Here, the two-row heads 51 to 54 correspond to the two-row heads 51 corresponding to Y and DY, the two-row heads 52 corresponding to M and LM, and the two-row heads C and LC from the front end side of the head block 44 in the forward movement. The two-row heads 53 and the two-row heads 54 corresponding to K and Y are arranged in this order.

Further, the nozzle rows 61 to 68 are a large number of ejection nozzles 61a to 68 capable of ejecting Y, DY, M, LM, C, LC, K and Y color inks, respectively.
a is included. The discharge nozzles 61a to 68a in the nozzle rows 61 to 68 are provided so as to have the same nozzle pitch, and are arranged so as to face each other (linear arrangement). The nozzle row 61
The number and arrangement of the discharge nozzles 61a to 68a included in the discharge nozzles 61 to 68 can be arbitrarily changed.
The 68a may be arranged in a staggered manner (staggered arrangement).

Therefore, the nozzle rows 61 to 68 are configured to color from a large number of ejection nozzles 61a to 68a toward the front surface (the upper surface in FIG. 1) of the conveyed paper 2 based on the signal supplied from the controller 20. A desired color image can be printed by ejecting each ink.

In this way, the head block 44 has eight
The nozzle row 61 and the nozzle row 68, which are the outermost ones of the two nozzle rows 61 to 68 and are capable of ejecting the same Y ink, respectively, and the two nozzle rows 61 and 68, and are different from the Y ink. Nozzle rows 62 to 67 capable of ejecting inks of different colors are provided. That is, a pair of nozzle rows 61, 68 capable of ejecting Y ink.
Is the outermost nozzle row among the eight nozzle rows 61 to 68, and one nozzle row capable of ejecting inks of different colors other than the Y ink is provided between them. .

Here, in the present embodiment, when the head block 44 is moving forward and backward, the nozzle row arranged closest to the tip end thereof (the nozzle row 61 during forward movement).
Alternatively, during the backward movement, ink is not ejected from the nozzle row 68) and printing is performed. That is, when the head block 44 is moving forward and backward, only one of the two nozzle rows 61 and 68 capable of ejecting Y ink (the upstream side in the moving direction of the head block 44) is used. Will be done.

Therefore, when the head block 44 moves forward, DY, M, LM, and
Ink is ejected and dots are printed so as to overlap in the order of C, LC, K, and Y. On the other hand, when the head block 44 is returned, the nozzle rows 61 to 67
Ink is ejected and dots are printed so as to overlap in the order of K, LC, C, LM, M, DY, and Y.

The carriage 45 which supports the head block 44 is reciprocated along the main scanning direction by the moving mechanism 49 as described above. Carriage 45
Are held by an annular belt 46, as shown in FIG. Further, the annular belt 46 is spanned by rollers 47 and 48 which are rotatable around rotary shafts (not shown) fitted and inserted in the respective axial center positions. Where roller 4
7 and 48 are arranged with an interval larger than the width of the sheet 2. Further, the annular belt 46 is arranged so as to be substantially perpendicular to the sub-scanning direction.

Here, the roller 47 is a driving roller which is rotationally driven by a motor (not shown), and the roller 48 is a driven roller which is rotated by the rotation of the roller 47 being transmitted through the annular belt 46. It's Laura. Therefore, when the roller 47 is rotated, the annular belt 46 also rotates in the same direction. Then, when the roller 47 is rotated in one direction by a predetermined angle, the rotation direction is changed, and this time, the roller 47 is rotated in the opposite direction by a predetermined angle, and the rotation direction is changed again. After that, this operation is repeated, and as the roller 47 rotates, the annular belt 46 moves back and forth, so that the carriage 45
Can reciprocate along the main scanning direction between the vicinity of one end and the vicinity of the other end of the paper 2 in the width direction. Here, the predetermined angle of the roller 47 is determined by the carriage 45
It corresponds to the reciprocating distance along the main scanning direction between the vicinity of one end and the vicinity of the other end in the width direction.

The print head section 11 of the ink jet printing unit 6 prints on the paper 2 by ejecting liquid ink dot by dot from the nozzles. The print head unit 11 may be of the piezo jet type, the thermal jet type or any other type. Any one may be adopted.

Further, the suction fan 12 is arranged at a position facing the print head portion 11 with the conveyance path of the sheet 2 interposed therebetween, and the conveyance table 4 is provided through an opening (not shown) formed in the conveyance table 4. It is for adsorbing the upper sheet 2.
Therefore, the paper 2 facing the print head unit 11 is the paper 2
Fan 12 arranged on the back side (bottom surface in FIG. 1) of the
Is sucked into the carrier table 4 and is transported in close contact therewith,
The distance from the print head unit 11 is constant. This is because when the paper 2 is curled, a part of the paper 2 is largely separated from the transport table 4 to suppress the occurrence of a printing defect due to a change in the distance from the print head unit 11. .

The pressure roller unit 7 is for holding the sheet 2 conveyed between the ink jet printing unit 6 and the cutting unit 8. Here, by disposing the pressure roller unit 7 between the inkjet printing unit 6 and the cutting unit 8, it is possible to properly perform the printing of the image by the inkjet printing unit 6 and the cutting of the paper 2 by the cutting unit 8. Becomes

The cutting unit 8 includes a movable blade 8a arranged on the same side as the print head portion 11 with respect to the paper 2, and the paper 2
It has a fixed blade 8b arranged so as to face the movable blade 8a with the blade sandwiched therebetween. The movable blade 8a and the fixed blade 8b are
Both are rectangular blades having a width slightly larger than the width of the paper 2. The movable blade 8a can be moved toward or away from the fixed blade 8b by the motor 27 controlled by the controller 20, and can move the printed sheet 2 conveyed from the upstream side of the conveyance path. , Can be cut along the width direction by the interaction with the fixed blade 8b. By cutting in this way, the printed paper 2 is divided into a predetermined length.

The discharge roller unit 9 is the controller 2
It is a drive roller pair driven by a motor 26 controlled by 0, and conveys the printed paper 2 cut by the cutting unit 8 and discharges it from the discharge port 30a.

The controller 20 performs predetermined processing on the image signal supplied from an input interface (not shown) and supplies a print signal containing image data corresponding to the image to be printed to the ink jet printing unit 6. Further, the controller 20 supplies a drive signal corresponding to a desired carry amount to the carry roller unit 5 and the discharge roller unit 9 at a suitable carry timing, and at the same time, sets the print timing in the inkjet printing unit 6 and the cut timing in the cutting unit 8. Can be controlled.

Next, the arrangement and configuration of dots on the paper 2 printed by the ink jet printer 1 configured as described above will be described with reference to FIGS. FIG. 4 is a diagram showing an arrangement state of printed dots. FIG. 5 is a schematic diagram showing the configuration of printed dots.

In FIG. 4, the head block 4
The dots printed during the forward movement of No. 4 are drawn by white circles (◯), while the dots printed during the backward movement of the head block 44 are drawn by black circles (●). In addition, in FIG.
Discharge nozzles 61a to 68 included in the nozzle rows 61 to 68
The distance between each nozzle of a is drawn as being the same as the dot diameter (raster width) to be printed.

In the ink jet printer 1, the head block 44 moves in the direction from the vicinity of one end of the paper 2 to the vicinity of the other end, or in the direction from the vicinity of the other end of the paper 2 of the head block 44 to the vicinity of one end. An image is printed by alternately repeating the backward movement and the conveyance of the paper 2 in the state where the head block 44 is near one end or the other end of the paper 2. The conveyance amount of the paper 2 in the sub-scanning direction may be a constant conveyance amount, or a plurality of different conveyance amounts may be repeated in an arbitrary order.

Here, as described above, when the head block 44 moves forward, ink is ejected from the ejection nozzles 62a to 68a included in the nozzle rows 62 to 68. At this time, the inks of different colors ejected from the nozzle rows 62 to 68 are DY, M, LM, C, LC, and
The dots are printed by overlapping in the order of K and Y. That is, as shown in FIG. 5A, a layer of DY ink ejected from the nozzle row 62 is first formed on the paper 2, and M ejected from the nozzle row 63 is formed thereon.
Layer of ink is formed, and subsequently, the layers of LM, C, LC, K, and Y ink ejected from the nozzle rows 64, 65, 66, 67, and 68 are sequentially overlapped to form dots. To be done.

On the other hand, when the head block 44 is returned,
Discharge nozzles 61a to 67 included in the nozzle rows 61 to 67
Ink is ejected from a. At this time, the nozzle rows 61 to
Dots are printed by superposing inks of different colors ejected from each of 67 in the order of K, LC, C, LM, M, DY, and Y. That is,
As shown in FIG. 5B, a layer of K ink ejected from the nozzle row 67 is first formed on the sheet 2, and a layer of LC ink ejected from the nozzle row 66 is formed thereon. The nozzle rows 65, 64, 63,
C, LM, M, D discharged from each of 62, 61
The Y and Y ink layers are sequentially overlapped to form dots.

Therefore, as shown in FIG. 4, inks of different colors are superposed on the paper 2 in the order of DY, M, LM, C, LC, K and Y when the head block 44 moves forward. Printed dots (white circle in Fig. 4)
And the inks of different colors when the head block 44 is moved back, K, LC, C, L
A raster composed of dots (black circles in FIG. 4) that are superimposed and printed in the order of M, M, DY, and Y is alternately repeated in the sub-scanning direction.

As described above, both rasters composed of dots printed by superposing inks in different orders on the sheet 2 are alternately repeated in the sub-scanning direction, but DY, M, LM, Dots and K, LC printed in superimposing order of C, LC, K, Y
For each of the dots printed by overlapping in the order of C, LM, M, DY, and Y, the ink ejected last on the paper 2 is the Y ink, which is the same color. That is, for all the dots printed on the paper 2, the color of the ink ejected last on the paper 2 is Y.
Ink. That is, for all the dots, the Y ink layer is arranged at the uppermost stage of the ink layer forming each dot.

In this embodiment, in the head block 44, only the outermost two nozzle rows 61 and 68 of the eight nozzle rows 61 to 68 can eject the same Y ink. Yes, that is, Y
Since only two nozzle rows capable of ejecting one color of ink are provided, and one nozzle row 62 to 67 capable of ejecting an ink of a color different from the Y ink is provided, For example, the head block 44 can be made smaller than in the case where two nozzle rows are provided for all colors.

As described above, according to the ink jet printer 1 of this embodiment, both the dots printed when the head block 44 moves forward and the dots printed when the head block 44 moves backward, that is, the paper 2 is printed. All dots printed above are printed by ejecting the Y ink of the seven color inks last. Therefore, it is possible to suppress the occurrence of color unevenness between the dots printed when the head block 44 moves forward and the dots printed when the head block 44 moves backward. As a result, the deterioration of the image due to the difference in the hue of the dots printed on the paper 2 is suppressed.

Further, since the head block 44 is constructed by combining the two-row heads 51 to 54 in which two nozzle rows are formed, the degree of freedom in designing the head block 44 is increased. That is, the head block 44 capable of ejecting ink of a plurality of colors can be easily manufactured by changing the number of the heads to be combined.

Further, since ink is ejected from all the eight nozzle rows arranged in the head block 44 to perform printing, waste of the nozzle rows can be eliminated and efficient printing can be performed with more color ink. You can

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments, and various design changes can be made within the scope of the claims. Is possible. For example,
In the above-described embodiment, the head block 44 has the nozzle row 61 and the nozzle row 68 capable of ejecting Y ink.
And the case where the nozzle rows 62 to 67 capable of ejecting 6 different colors of ink different from the Y ink are provided between the two nozzle rows 61 and 68. Not limited to this, there is a pair of nozzle rows that are the outermost of the eight nozzle rows and that can eject ink of the same specific color, respectively, and between the pair of nozzle rows that are different from each other and that are different from the specific color. Any type may be used as long as it is provided with six nozzle rows capable of ejecting each color ink.

Therefore, the outermost two nozzles in the eight nozzle rows are
Ink of a specific color different from the ink of Y (e.g., M ink) can be ejected from the one nozzle row 61 and nozzle row 68, and different from the specific color different from the nozzle rows 62 to 67. Ink of a different color (inks of different colors different from M) may be ejectable. That is,
In the arrangement of ink colors in the nozzle rows 61 to 68, the nozzle rows 61 and 68 correspond to the same color,
In addition, the nozzle rows 62 to 67 can be arbitrarily changed as long as they correspond to different colors different from the colors corresponding to the nozzle rows 61 and 68.

Further, in the above-described embodiment, the head block 44 has seven elements of Y, DY, M, LM, C, LC and K.
Although the case where the nozzle rows corresponding to the color inks are provided has been described, the present invention is not limited to this, and inks other than the above seven colors may be used as the seven color inks. The combination of can be changed arbitrarily. Further, the head block 44 does not necessarily have to be provided with nozzle rows corresponding to inks of seven colors, and the number of colors can be arbitrarily changed. Therefore, the color of the ink ejected from the head block 44 may be eight colors or more, or may be six colors or less. However, in the head block 44 of the present embodiment, when the ink color is 6 or less, the ink is not ejected from at least one of the nozzle rows 61 to 68 (is not used), and the nozzle row is wasted. Become.

Further, in the above-described embodiment, the nozzle rows (first nozzle rows) capable of ejecting ink of the same color are the outermost two nozzle rows of the two-row heads 51 to 54.
The heads 51 and 54 are provided one by one, and the outermost nozzle rows 61 and 68 among the eight nozzle rows 61 to 68 are provided.
However, the present invention is not limited to this, and at least one of the nozzle rows (first nozzle rows) capable of ejecting ink of the same color as each other has two row heads 51, 54.
It may be provided in other two-row heads other than,
Outermost nozzle row 6 among the eight nozzle rows 61 to 68
It need not be 1,68. However, when nozzle rows (first nozzle rows) capable of ejecting ink of the same color are not provided in the two-row heads 51 and 54, respectively, they are arranged in at least one of the two-row heads 51 and 54. Since both of the formed two nozzle rows are not used, the head unit can be further downsized by removing the two-row head.

Further, in the above-described embodiment, the case where the head block 44 is configured by combining the two-row heads 51 to 54 has been described, but the present invention is not limited to this, and the head unit is an integral type. It may be one.

Further, in the above-described embodiment, when the head block 44 is moved, printing is performed without ejecting ink from the nozzle row arranged at the tip end side of the head block 44. The case where the colors of the ejected ink are the same has been described, but the present invention is not limited to this, and when the head block 44 moves, ink is not ejected from the nozzle row arranged at the rearmost end side of the head block 44 and printing May be performed. In this case, the color of the ink that is first ejected onto the paper 2 is the same, and the same effect as this embodiment can be obtained.

[0052]

As described above, according to the first aspect, when the head unit moves forward and backward, the nozzles included in the selected nozzle row of the head unit eject onto the print medium. For multiple color inks,
At least one of the color of the ink ejected first and the color of the ink ejected last can be the same. Therefore, even when dots printed by superposing inks of different colors in different orders are adjacent to each other, it is possible to suppress the occurrence of color unevenness between these dots. This suppresses deterioration of the image printed on the print medium due to the difference in the hue of the dots.

According to the second aspect, since the head unit is configured by arranging a plurality of heads having two nozzle rows arranged in the same direction, the degree of freedom in designing the head unit is large. Become. That is, the head unit capable of ejecting ink of a plurality of colors can be easily manufactured by changing the number of the heads to be combined.

According to the third aspect, since the ink is ejected from all the nozzle rows arranged in the head unit to perform the printing, the waste of the nozzle rows is eliminated, and the printing is efficiently performed by using the multicolor ink. be able to.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an inkjet printer according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a schematic configuration of a print head unit.

FIG. 3 is a diagram showing a schematic configuration of a nozzle row arranged in a head block.

FIG. 4 is a diagram showing an arrangement state of printed dots.

FIG. 5 is a schematic diagram showing a configuration of printed dots.

[Explanation of symbols]

1 Inkjet printer 2 paper (print media) 44 Head block (head unit) 49 Moving mechanism (driving means) 51-54 2-row head (head) 61, 68 nozzle row (first nozzle row) 62 to 67 nozzle row (second nozzle row) 61a to 68a Discharge nozzle (nozzle)

Claims (3)

[Claims] 1. A head unit in which three or more nozzle rows each including a large number of nozzles are arranged adjacent to each other in a direction substantially orthogonal to the longitudinal direction of the nozzle row, and the head unit faces a print medium. And a driving unit that moves the head unit relative to the print medium so that the head unit reciprocates in a direction substantially orthogonal to the longitudinal direction of the nozzle row. Ink is ejected only from the nozzles included in the nozzle row selected in the above nozzle row, in both the forward movement and the backward movement by the drive unit. As a nozzle row, a pair of first nozzle rows that are the outermost of the selected nozzle rows and are capable of ejecting ink of the same specific color as each other, and Between the pair of first nozzle rows, two types of one or a plurality of second nozzle rows capable of ejecting inks of different colors different from the specific color are provided. Characteristic ink jet printer. 2. The head unit comprises a plurality of heads having two nozzle rows arranged in the same direction and arranged adjacent to each other in a direction substantially orthogonal to the longitudinal direction of the nozzle rows. There is one pair of the first nozzle rows in each of the outermost two heads of the plurality of heads, and at least one of the pair of the first nozzle rows belongs to the head unit. The outermost nozzle row among the rows, and all the nozzle rows between a pair of the first nozzle rows are selected as the second nozzle rows. Inkjet printer. 3. The ink jet printer according to claim 2, wherein the pair of first nozzle rows is the outermost two nozzle rows of all the nozzle rows belonging to the head unit.