KR101565056B1 - Inkjet printer and printing method therefor - Google Patents

Abstract

An object of the present invention is to suppress the occurrence of band streaks in printing using a print head comprising a plurality of head units to improve print image quality. The printing head 2 is moved in the main scanning direction X and the printing head 2 is moved relative to the printing medium 11 in the sub scanning direction Y to perform printing I do. The print head 2 is formed by joining a head unit HU21 having a nozzle array formed by a plurality of nozzles arranged in a line along the sub scanning direction Y. [ A non-ejection area 203 in which ink droplets are not ejected is provided only between adjacent two head units HU21. The non-ejection region length of the non-ejection region 203 in the sub-scanning direction Y is longer than the adjacent nozzle-to-nozzle distance between two adjacent nozzles.

Description

≪ Desc / Clms Page number 1 > Inkjet printer and printing method Therefor,

The present invention relates to a multi-pass type ink-jet printer for performing printing by a plurality of passes and a printing method therefor.

2. Description of the Related Art Inkjet printers having a printhead having a plurality of nozzles aligned in the main scanning direction are known. One of the image forming methods by such an ink jet printer is an overlap recording method. The overlap recording method is a recording method in which an image on one main scanning line is formed by using different nozzles in a plurality of scanning operations in the main scanning direction.

The inkjet printer has a multi-pass system in which an image is formed by repeating scanning in the main scanning direction with a nozzle corresponding to a plurality of passes.

In the multi-path inkjet printer, the nozzle array of the printhead is divided into the pass columns corresponding to the respective passes, and the corresponding pass is printed by the plurality of nozzles constituting each pass column. The printing area formed by one scanning becomes a band having a band width. As a result, the image is completed at the portion where the scanning of the number of passes is finished. For example, in the case of completing an image by four passes using a print head having four pass columns, the print is completed at a rate of 25% by scanning each time, and scanning is performed four times in total The image is completed by loading (100%),

When the scanning is completed once, the scanning position of the print head moves in the sub-scanning direction (direction orthogonal to the main scanning direction) by the movement of the print head or the print medium. Thus, the printing by the print head advances in the sub-scanning direction by the width of each scan.

At this time, adjacent bands are printed so as to overlap each other so that no gap is formed between the bands. If the overlapping portion printed in this manner is excessively large, the density becomes high and becomes conspicuous like band stripes. On the other hand, if the overlapping portion is too small, a gap tends to be generated due to a deviation in paper feeding. For this reason, a defect occurs in which the print image quality is not stabilized.

As a means for solving such defects, Patent Document 1 discloses that overlapping ink ejection is not performed by two scans of the same dot in the overlapping portion as described above.

Prior art literature

(Patent Literature)

Patent Document 1: JP-A-60-107975 (published on June 13, 1985)

Incidentally, in an ink-jet printer, a composite head constituting one print head by combining a plurality of print heads (head units) may be used. Such a composite head can offset a head unit in order to construct a long printhead at low cost by using a general-purpose small printhead which is easy to obtain as a head unit, or to realize an arrangement structure such as a staggered form .

Fig. 12 shows an example of the configuration of the print head 101 constituted by the above-described composite head. 13 shows a printing state in a plan view when printing is performed using the print head 101. In Fig.

As shown in Fig. 12, the print head 101 is formed by joining two head units HU101 having the same configuration in a linear shape. The head unit HU101 has a plurality of nozzles 102 arranged at equally spaced intervals in the sub scanning direction Y. [ The nozzles 102 in one head unit HU101 are divided into two first pass columns P101 and a second pass column P102 corresponding to the first pass and the second pass, respectively. The nozzle 102 in the other head unit HU101 is divided into two third path columns P103 and a fourth path column P104 corresponding to the third path and the fourth path, respectively.

In the case of printing by the print head 101 configured as described above, 25% printing is performed by the first scan in the main scanning direction X by the first pass column P101 as shown in Fig. 13 And 50% printing is performed by the second scan by the second pass column P102 for the same area. Further, the same area is printed with 75% in the third scan by the third pass P103, 100% in the fourth scan by the fourth pass P104, and the image is completed do. When each scan is completed, the print head 101 or the print medium moves in the sub-scan direction Y. [

In general, ejection of ink droplets by the nozzles at both ends of the print head is not stable. Similarly, in the print head 101 as described above, ejection of the ink droplets by the nozzles 120 at both ends of each head unit HU101 is not stable. For this reason, ink droplets ejected from the nozzles 102 at the adjacent ends between the second pass column P2 and the third pass column P3 may land on the print medium to interfere with each other. In this portion where the ink droplets interfere with each other, a band stripe having a density higher than that of the other portions appears in the print image at the position indicated by chain double-dashed line in Fig.

In order to alleviate such an ink drop interference phenomenon, it is conceivable to mechanically adjust the mounting position of the print head 101 so as to improve the landing precision of ink droplets. Such adjustment includes adjustment of the position of each head unit HU101 in the main scanning direction X and the sub scanning direction Y of the print head 101, for example. In this adjustment, the interval between the respective head units HU101 constituting the print head 101 is adjusted in the conveyance direction (sub-scan direction Y) of the print medium, so that the nozzles at the ends of each head unit HU101 It is important to adjust the interval between the liver. Alternatively, the adjustment may include adjustment of the angle of each head unit HU101 of the print head 101. [ In this adjustment, the intervals between the nozzles at the end portions of the respective head units HU101 are adjusted by adjusting the angles so that the respective head units HU101 are rotated in both directions about the respective predetermined axes.

However, if the distance between the nozzle surface of the print head 101 and the print medium becomes long, the ink drop interference phenomenon can not be alleviated even by the above adjustment, and there is a limit to suppress the occurrence of band stripes.

Further, with respect to the technique described in Patent Document 1, since it is possible to adjust the density of the boundary portion (overlapping portion) between the bands, it is conceivable to apply the technique to mitigate the ink drop interference phenomenon. However, for the following reasons, it is difficult to apply the technique to mitigate the ink drop interference phenomenon.

The ink droplet interference phenomenon depends on the characteristic inherent to the print head constituting the head unit HU101 (discharge characteristics of ink droplets by the nozzle 102 at the end portion), and when the distance between these print heads is close Lt; / RTI > For this reason, in the technique of Patent Document 1 that improves the image quality at the boundary between the bands, it can not cope with the ink drop interference phenomenon caused by the interference of the ink drops between the print heads.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to suppress the occurrence of band streaks in printing using a print head comprising a plurality of head units to improve print image quality.

An ink-jet printer according to the present invention includes: a print head having a plurality of head units each having a nozzle array including a plurality of nozzles arranged along a sub-scanning direction orthogonal to a main scanning direction; And a moving means for moving the print head in the main scanning direction and moving the print head relative to the printing medium in the sub scanning direction for each scanning, In order to solve the above-described problem, an inkjet printer in which a plurality of passes are printed on a medium by a single scan is provided. The print head has a non-ejection area in which the ink droplets are not ejected only between two adjacent head units , And the non-ejection region length of the non-ejection region in the sub-scanning direction is 2 is characterized in that is longer than the inter-distance between adjacent nozzles of the nozzle.

A printing method of an ink jet printer according to the present invention includes a print head having a plurality of head units each having a nozzle row consisting of a plurality of nozzles arranged in a sub scanning direction perpendicular to a main scanning direction, The print head is moved in the main scanning direction and the print head is moved relative to the printing medium in the sub scanning direction for each scanning, A printing method of an inkjet printer which prints a plurality of passes by a single scan, comprising: a non-ejection area which does not eject the ink droplets only between two adjacent head units, The non-ejection region length of the non-ejection region in the sub-scanning direction is shorter than the length of the adjacent two Group is characterized by using the print head adapted to longer than the distance between adjacent nozzles between nozzles.

According to the above arrangement, scanning is repeated while moving the print head with respect to the print medium, whereby the image is completed in the band in which printing by all the pass columns is completed. Further, in the print head, since the non-ejection areas are provided only between two adjacent head units, the non-ejection area between the head units becomes a buffer zone, and ink droplets ejected from the nozzles at the end of the head unit interfere with each other . Therefore, even when the distance between the print head and the print medium is long, it is possible to easily prevent the interference of the ink droplets without mechanically adjusting the mounting position of the print head, as in the prior art.

As long as the length of the non-ejection region is longer than the distance between adjacent nozzles, at least one blank line can be set. Thus, when scanning is performed in the non-ejection area having the non-ejection area length, blank lines (non-recording area) are formed on the band formed by the previous scanning. Therefore, even if the print head is moved in the sub-scan direction with respect to the print medium in each scan similarly to the printing method of the conventional ink-jet printer, the end portion of the band formed by the scanning at this time is displaced from the band end portion of the lower layer formed by the previous scan . Therefore, since the boundaries of the bands do not overlap, the boundaries between the bands are not conspicuous, and the occurrence of banding can be prevented.

The moving means relatively moves the print head with respect to the print medium in the sub scanning direction at a width shorter than the length of the pass column made up of the nozzles corresponding to the pass for each scan, The control means associates the data of the first pixel pattern filtered with the image to be printed in the previous scanning with a part of the nozzles at both ends in the sub scanning direction of each head unit, It is preferable that the data of the second pixel pattern complementary to the pattern is made to correspond to the remaining nozzles at the both end portions.

The printing method of the inkjet printer may further include a step of relatively moving the print head with respect to the print medium in the sub scanning direction at a width shorter than the length of the path of the pass consisting of the nozzles corresponding to the path, With the first pixel pattern in which the pixels to be printed are filtered out in the previous scanning by the both end portions in the sub scanning direction of the first pixel pattern and the second pixel pattern complementing the first pixel pattern in the subsequent scanning .

In the ink-jet printer configured as described above, since the data of the first pixel pattern corresponds to some nozzles at both ends of the head unit, ink droplets are ejected from the nozzles to form pixels in a filtered state. Further, since the data of the second pixel pattern corresponds to the remaining nozzles at both ends of the head unit, ink droplets are ejected from the nozzles in the subsequent scanning so that the pixels filtered in the previous scanning are complemented.

In the printing method as described above, pixels are printed in the first pixel pattern by filtering the pixels to be printed in the previous scanning by the both end portions of the respective head units, thereby forming the pixels in a filtered state. Further, in the subsequent scanning, printing is performed in the second pixel pattern by the both ends, so that the pixels filtered in the previous scanning are complemented.

As a result, a portion of the pixel printed by one scan with a low density is supplemented by the next scan. Therefore, the concentration of the ink droplet does not change abruptly between the bands formed by the respective head units, and it is possible to prevent occurrence of band stripes due to unevenness of the ink density. Therefore, the printing quality can be improved.

Since the ink-jet printer according to the present invention is configured as described above, the print quality can be improved by suppressing the occurrence of band stripes in printing using a print head composed of a plurality of head units.

1 is a plan view showing the configuration of main parts of an inkjet printer according to an embodiment of the present invention.
2 is a side view showing the configuration of the main part of the inkjet printer.
3 is a plan view showing a configuration of a print head in the inkjet printer.
4 (a) to 4 (c) are plan views showing the bonding portions of the printhead and three different structures in the vicinity thereof.
5 is a plan view showing a specific configuration of the print head according to the first embodiment.
6 (a) is a plan view showing a state in which printing is performed on a print medium in a multipass manner by the inkjet printer using the print head according to the first embodiment, and Fig. 6 (b) Sectional view.
7 is a plan view showing a specific configuration of the print head according to the second embodiment.
8 (a) is a plan view showing a state in which printing is performed on a printing medium in a multipass manner by the inkjet printer using the printing head according to the second embodiment, and Fig. 8 (b) Sectional view.
9 is a plan view showing a specific configuration of the print head according to the third embodiment.
10 is a plan view showing a specific configuration of the print head according to the fourth embodiment.
11 is a plan view showing another specific structure of the print head according to the fourth embodiment.
12 is a plan view showing a configuration of a printhead used in a conventional inkjet printer.
13 is a plan view showing a state in which printing is performed on a print medium in a multipass manner using the conventional printhead.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to Figs. 1 to 11. Fig.

[Configuration of inkjet printer]

Fig. 1 is a plan view showing the configuration of an inkjet printer 1, and Fig. 2 is a side view showing the configuration of an inkjet printer 1. Fig. 3 is a plan view showing the configuration of the print head 2. As shown in Fig. 4 (a) to 4 (c) are plan views showing the joining portion of the print head 2 and the structure in the vicinity thereof.

1 and 2, an inkjet printer 1 includes a print head 2, a guide rail 3, a platen 4, a drive roller 5, a driven roller 6, and a control unit 7, . The inkjet printer 1 is a printer that performs printing in a multipass manner.

(Configuration of Print Head)

The print head 2 is a printing head for ejecting ink droplets against the print medium 11 and is driven in the main scanning direction X at the time of scanning along the guide rails 3. [ As shown in Fig. 3, the print head 2 has a plurality of head units HU1, and adjoining head units HU1 are coupled to each other to constitute a composite head.

On the other hand, the configuration of the head unit HU1 constituting the print head 2 is not limited to the above-described configuration, and various configurations can be adopted. The various configurations will be described in the following embodiments.

Although not shown, each head unit HU1 may be coupled by being fixed to a plate-like head coupling member or by being integrally received in a case. The head unit HU1 is not limited to these, but may be combined with various coupling structures.

Each of the head units HU1 has a plurality of nozzles 201 arranged along the sub scanning direction Y and the nozzle arrays 202 are constituted by these nozzles 201. [ The nozzle 201 opens at the ink discharge surface (nozzle surface) and discharges ink droplets to the print medium 11. [ Two adjoining nozzles 201 are formed with a distance between adjacent nozzles d2. The nozzle row 202 includes at least one pass row P made up of a plurality of nozzles 201 corresponding to one pass.

A predetermined number of nozzles 201 at both ends of the head unit HU1 (nozzle array 202) are set as half discharge nozzles 201a. The half discharge nozzle 201a is controlled to discharge by the discharge control section 73 so as to perform 12.5% printing by one scan while the ordinary nozzle 201 performs 25% printing by one scan . More specifically, when the half ejection nozzles 201a of the half (half) ejection nozzles are ejecting ink droplets by the first scanning, the other half ejection nozzles 201a do not eject ink droplets. The half ejection nozzle 201a, which did not eject ink droplets in the first scan in the second scanning, ejects ink droplets, and the other half ejection nozzles 201a do not eject ink droplets.

On the other hand, the degree of printing by one scanning is not limited to half (12.5%) as described above. For example, 2.5% is printed by one end of the head unit HU1 in the first scan and 22.5% is printed by the other end of the head unit HU1 in the second scan, so that 25% Printing may be performed.

The width at which the half discharge nozzle 201a at the end of the head unit HU1 is printed is the same at both ends of the head unit HU1.

A non-ejection region 203 (an area indicated by oblique lines in Fig. 3) in which ink droplets are not ejected (a region indicated by oblique lines in Fig. 3) is formed at a portion where the adjacent head unit HU1 is joined. The non-ejection region 203 is formed by two nozzles 201 (ejection nozzles) on the joining end side in two adjacent head units HU1 out of the nozzles 201 (ejection nozzles) for ejecting ink droplets in the nozzle row 202 As shown in Fig.

The non-ejection region 203 has a length of the non-ejection region length d1 in the sub-scanning direction Y. [ This non-discharge region length d1 is longer than the adjacent nozzle-to-nozzle distance d2, which is the distance between two adjacent nozzles 201. [ At least the ink droplets ejected from the nozzles 201 at the end of the head unit HU1 are ejected from the nozzles 201 at the end of the adjacent head unit HU1, It is set to a distance that does not interfere.

Here, the non-ejection region 203 is configured as follows.

(1) A configuration for forming a gap between the head units

As shown in Fig. 4A, the non-ejection region 203 is formed by joining adjacent two head units HU1 with a gap therebetween. The distance between the head units HU1 is set by the arrangement position of the head unit HU1 to the joining member 204 joining the head unit HU1.

In this configuration, the non-ejecting region length d1 is determined as the interval between the head units HU1. Therefore, by appropriately setting the arrangement position of the head unit HU1, it is possible to easily set the non-discharge area length d1 without changing the configuration of the head unit HU1 itself.

(2) Configuration for setting non-ejection nozzle

As shown in Fig. 4 (b), the non-ejection region 203 is a region in which a predetermined number of nozzles 201 in the vicinity of the joining end portions of adjacent two head units HU1, Non-ejection nozzle 201b. The number of the non-ejecting nozzles 201b at the joining end of one head unit HU1 is not particularly limited, but is determined according to the length of the non-ejecting area length d1. In the example shown in FIG. 4 (b), one non-ejection nozzle 201b is formed at the junction end of one head unit HU1.

Since the non-ejection nozzle 201b corresponds to the blank line data by the ejection control section 73, it does not eject ink droplets even if it has a function of ejecting ink droplets. Therefore, by appropriately changing the non-ejection nozzles 201b corresponding to the blank line data, it is possible to set different non-ejection regions 203 in the print head 2 having the nozzle arrays 202 of the same configuration in accordance with printing conditions and the like have.

(3) a configuration in which a gap is formed between the head units by setting non-ejection nozzles

This configuration is a combination of the configuration shown in FIG. 4B and the configuration shown in FIG. 4A. In such a configuration, for example, by setting the non-ejection nozzles 201b, the non-ejection area 203 is set, and the gap between the head units HU1 is further adjusted. Thus, the non-discharge region length d1, which can not be coped with by the increase in the number of the non-discharge nozzles 201b, can be finely adjusted.

(4) Configuration without forming a nozzle

As shown in Fig. 4 (c), the non-ejection area 203 is formed by not providing the nozzles 201 in two adjoining head units HU1 which are seamlessly joined. This corresponds to the case where the non-ejection nozzle 201b is not provided in the constitution shown in Fig. 4 (b).

In such a configuration, the blank line that can be formed by the non-ejection region 203 is fixed, but as in the configuration shown in Fig. 4 (b), the ejection control section 73 supplies the data of the blank line to the non- 201b, so that the control of the control unit 7 can be simplified. In addition, by setting the non-ejection nozzles 201b in combination with the configuration shown in Fig. 4B, blank lines can be added in accordance with printing conditions.

(Structure of Supporting and Driving Mechanism)

The platen 4 is a support stand provided at a position facing the guide rail on which the print head 2 moves. The platen 4 defines a position of the printing medium 11 and has a mechanism for fixing the printing medium 11 by suction or the like.

The driving roller 5 (moving means) is a roller that rotates by giving a driving force through a driving shaft, and two rollers are arranged at a predetermined interval in the main scanning direction. The driven roller 6 is a roller that rotates in a direction opposite to the driving roller 5 by abutting against the driving roller 5 and two of them are disposed at positions facing the driving roller 5 . The driving roller 5 and the driven roller 6 are driven in the sub scanning direction Y perpendicular to the main scanning direction X in accordance with the rotation of the driving roller 5 by sandwiching the printing medium 11 therebetween The printing medium 11 is conveyed in a reverse direction to the predetermined pitch. This pitch is the width of the sub scanning direction Y (band width described later) of the portion (band) in which the print head 2 is printed by one scan, and is shorter than the length of the pass train P. The pitch is set to be the same in each scan, and it may be set non-uniformly in each scan.

(Configuration of control unit)

The control unit 7 has a main injection control unit 71, a sub-injection control unit 72, and a discharge control unit 73.

The main scanning control unit 71 controls the operation of a motor or the like for driving the print head 2 in order to move the print head 2 in the main scanning direction X. [ In addition, the main scan control unit 71 outputs a scan start signal before scanning start and a scan end signal after scanning end, in order to change a row every scanning.

The sub scanning control unit 72 (moving means) controls the operation of a motor or the like for driving the driving roller 5 in order to convey the print medium 11 in the direction opposite to the sub scanning direction Y. The sub-scan control unit 72 controls the rotation of the motor so that the print medium 11 is conveyed at the pitch conveying amount after each scanning.

The ejection control unit 73 (ejection control means) controls ejection of ink droplets from the nozzles 201 of each pass line P in accordance with the movement of the print head 2 in the main scanning direction X, The discharge control unit 20 performs discharge control to discharge the ink. The discharge control section 73 performs discharge control by switching the path column P for discharging the ink to the next path column P based on the scanning start signal outputted from the main scanning control section 71 .

The ejection control section 73 controls the semi-ejection nozzle 201a to perform ejection only for the sake of ejection of the ink droplets in the two ejection operations. Specifically, the ejection control section 73 divides the print data of the pixel pattern (first pixel pattern) for printing a part (half number) of pixels (dots) by the previous one scanning into the half ejection nozzles (201a). The ejection control section 73 then outputs the print data of the pixel pattern (second pixel pattern) to be printed which compensates for the remaining (half-tone) pixels filtered in the previous scanning in the subsequent scanning to the corresponding half ejection nozzle 201a .

When the print head 2 having the above-described non-ejection region 203 shown in FIG. 4B is used, the ejection control section 73 performs ejection control different from normal ejection control. Specifically, the discharge control section 73 maps the blank line data to the non-ejection nozzle 201b and does not correspond to the blank line data with respect to the nozzle 201 that ejects ink droplets.

(Realization of control unit by software)

Each of the blocks of the control unit 7, particularly, the main injection control unit 71, the sub-injection control unit 72 and the discharge control unit 73 shown in Fig. 2 may be constituted by hardware logic, .

That is, the control unit 7 includes a CPU (Central Processing Unit) that executes a command of a control program realizing the functions of the main injection control unit 71, the sub-injection control unit 72, and the discharge control unit 73, A ROM (Read Only Memory), a RAM (Random Access Memory) for expanding a control program, a storage device (print medium) such as a memory for storing a control program and various data, and the like. An object of the present invention is to provide a print medium in which a program code (an executable program, an intermediate code program, and a source program) of software for realizing the above-described functions is recorded so as to be readable by a computer to the inkjet printer 1, And reading out and executing the program code recorded on the print medium.

As the print medium, for example, a magnetic tape such as a magnetic tape or a cassette tape, a magnetic disk such as a floppy (trademark) disk / hard disk, or an optical disk such as a CD-ROM / MO / BD / DVD / CD- A card system such as an IC card (including a memory card) / optical card, or a semiconductor memory system such as a mask ROM / EPROM / EEPROM / flash ROM.

Further, the ink-jet printer 1 may be configured to be connectable to a communication network, and the program code may be supplied through a communication network. Such a communication network is not particularly limited. For example, the Internet, an intranet, an extranet, a LAN, an ISDN, a VAN, a CATV communication network, a virtual private network, a telephone line network, a mobile communication network, Do. The transmission medium constituting the communication network is not particularly limited and may be wired such as IEEE1394, USB, power line carrier, cable TV line, telephone line and ADSL line, infrared 802.11 wireless, HDR, cellular phone network, satellite line, and terrestrial digital network. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied as an electronic transmission.

(Other configurations of inkjet printers)

The inkjet printer 1 conveys the print medium 11 in the direction opposite to the sub scanning direction Y in order to move the print area on the print medium 11 in the sub scan direction Y, Is not shifted in the sub-scanning direction Y as shown in Fig. However, the present invention is not limited to the above configuration, as long as the print head 2 can move relative to the print medium 11.

For example, the ink-jet printer 1 fixes the print medium 11 without conveying it, and moves the print head 2 in the sub-scan direction Y to move the print head 2 to the print medium 11 ) May be employed. In this configuration, the driving roller 5 and the driven roller 6 are not required, and a mechanism for driving the print head 2 in the sub-scanning direction Y is required. Such a mechanism is, for example, a mechanism for driving the print head 2 in each sub-scanning direction Y for each of the guide rails 3. [ In addition, the sub scan control unit 72 controls the operation of the mechanism in place of the control of the drive roller 5. [

(The color of the ink droplet ejected from each scan)

The ejection color of the ejection nozzles divided in each pass column P, that is, the color of the ink droplets (hereinafter, referred to as 'pass column ejection color') for each pass column P discharged by the nozzle 201, The same or different). Alternatively, in the case of scanning with the print head 2 constituted by arranging the ejection colors ejected by the nozzles 201 for each of the head units HU1 and for the multicolor printing by combining the head units HU1 as many as the number of hues It may be configured to eject ink droplets of all colors.

When the head unit HU1 is prepared for each color and multicolor printing is performed, it is preferable that all the ink droplets of all colors are ejected by scanning the head unit HU1 at one time from the viewpoint of the printing speed. However, from the viewpoint of image quality improvement, it is preferable to eject ink droplets of a single color by one scan (that is, a single pass heat ejecting color or ejection color for each head unit HU1).

Pass column ejection colors or ejection colors for each head unit HU1 are single in one scan so that they are ejected from each pass column P or all the pass columns P of the print head 2 at the time of one scan, The colors of the ink droplets landed on the medium 11 become the same. As a result, the ink droplets of a plurality of colors are prevented from spreading to each other at the time of landing, thereby improving the color development of the printed image. Since the order of colors of the ink droplets to be landed is the same between the bands of the same layer, it is possible to prevent a change in hue between the bands due to the difference in the landing order.

For example, when printing is performed using inks of cyan and magenta, if the ejection color of the first scan is cyan, ink drops of cyan are landed on the print medium 11, One layer is formed. If the ejection color of the second time scan is magenta, magenta ink droplets are further deposited on the print medium 11, so that a second layer of magenta is formed. This is also true when the pass column discharge color in a single scan is single.

As a result, the ink droplets discharged from each pass line P do not spread in the band at the time of adhering, so that the color development of the printed image becomes good. Further, since the degree of bleeding of ink drops deposited on the lower band is not different between the bands of the same layer, there is no change in color between the bands.

On the other hand, when the pass heat discharge color is not uniform, the following defect occurs. First, ink droplets ejected from each pass line P spread at the time of landing. Second, different ink drops between the bands in the same layer are landed in different orders. Because of this, the degree of bleeding of the ink droplets landed on the lower band is different between the bands of the same layer, resulting in a change in color between the bands. Therefore, it is preferable that the pass heat discharge color or the discharge color for each head unit HU1 is unified in one scan so as not to damage the printed image.

[Embodiment 1]

Details of the above-described print head 2 will be described with reference to Figs. 5, 6A and 6B.

(Configuration of Print Head)

Fig. 5 is a plan view showing the configuration of the print head 21. Fig.

The above-described printhead 2 is configured as a printhead 21 as shown in Fig. The print head 21 has two head units HU21, and the head units HU21 are coupled to each other.

Like the head unit HU1 described above, the head unit HU21 has a plurality of nozzles 201 arranged in a line, and the nozzle array 202 is constituted by these nozzles 201. [ A predetermined number of nozzles 201 at both end sides of the nozzle row 202 are set as half discharge nozzles 201a.

In the nozzle array 202, two adjacent nozzles 201 are arranged with a distance of adjacent nozzle-to-nozzle distances d2. The non-ejection area 203 is provided at the junction of the adjacent head unit HU21 in the above-described configuration as shown in any of Figs. 4 (a) to 4 (c). The non-ejection area length d1 of the non-ejection area 203 is longer than the adjacent nozzle-to-nozzle distance d2.

In the head unit HU21 disposed on one end side of the print head 21, the nozzle array 202 is divided into a first pass column P1 and a second pass column P2. The first pass column P1 is disposed on the end side in the head unit HU21 and the second pass column P2 is disposed on the adjacent head unit HU21 side.

On the other hand, in the head unit HU21 disposed on the other end side of the print head 21, the nozzle array 202 is divided into the third pass column P3 and the fourth pass column P4. The third pass column P3 is disposed on the adjacent head unit HU21 side in the head unit HU21 and the fourth pass column P4 is disposed on the end side of the head unit HU21.

On the other hand, the number of nozzles (the ratio of the number of nozzles) of the first pass column P1 and the second pass column P2 is set by printing conditions or the like. Likewise, the number of nozzles of the third pass column P3 and the fourth pass column P4 is set by the printing conditions and the like. Therefore, the number of nozzles in the first pass column P1 and the number of nozzles in the second pass column P2 may not be the same, and the number of nozzles in the third pass column P3 and the fourth pass column P4 may not be the same.

The head unit HU21 has two pass columns P, but may have three or more pass columns P.

Furthermore, although the print head 21 is constructed by combining the head units HU21 of the same kind, the present invention is not limited to this, and the head units HU21 of different types may be combined.

(Printing operation by inkjet printer)

A multipass printing operation of the inkjet printer 1 using the print head 21 configured as above will be described. 6 (a) shows the printing state of the inkjet printer 1 when viewed from the plane, and Fig. 6 (b) shows the same printing state as viewed from the side of the printing medium 11 (Viewed from the direction X).

6A, the print head 21 of each scan is shifted in the main scan direction X so that the relative movement of the print head 21 with respect to the print medium 11 is easy to see. As shown in FIG.

In the following description, when the common reference is made to the first through fourth columns P1 through P4, it is simply referred to as a "pass column P".

The hatched portion in the print head 21 of Fig. 6A is a region where the semi-discharge nozzle 201a is provided. 6 (b), hatched portions are portions where ink droplets are ejected by the half ejection nozzle 201a, and "1" to "5" are ejected by the first to fifth inks, respectively Is a formed portion.

<First Injection>

6 (a) and 6 (b), in the first scan, scanning is performed by a part of the first pass column P1 from the origin of the image, so that ink droplets are ejected on the print medium 11 A band is formed by the width of the nozzle 201. Of these bands, the area in which the ink droplets are ejected by the ordinary nozzle 201 is 25% of the printing degree, and the area where the ink droplets are ejected by the half ejection nozzle 201a is 12.5%.

When the ink droplets are ejected from the half ejection nozzle 201a, the ejection control section 73 performs ejection control based on the print data of the first pixel pattern, so that half of the half ejection nozzles Ink droplets are ejected from the ink chamber 201a. Accordingly, printing is performed in a state in which half of the pixels are filtered, and a band of 12.5% printing accuracy is formed.

<Second Injection>

In the second scanning, the print medium 11 is conveyed in the reverse direction to the sub-scanning direction Y by a predetermined pitch (band width) shorter than the pass line P, In the sub-scan direction Y. The sub- In this state, a part of the second pass column P2 and the first pass column P1 are scanned from the origin of the image. At this time, the half-ejection nozzle 201a on the one end side in the second pass column P2 does not perform the scanning.

By this scanning, a band of the first layer is formed adjacent to the band of the first layer formed by the first scan on the print medium 11, and also on the band of the first layer formed by the first scan Bands are formed (overlapping bands). On the band having the printing accuracy of 12.5% formed by the first scan, the band is formed so that the printing accuracy is 37.5% by the scanning of the nozzle 201. [ On the other hand, bands are formed on the bands having the printing degree of 25% formed by the first scan so that the degree of printing becomes 50% by the scanning of the nozzles 201.

As described above, the printing medium 11 is conveyed at a predetermined pitch shorter than the pass column P, whereby the overlapping portions of the bands are printed with reduced printing accuracy, and the image is completed by the plurality of times of scanning.

<Third Injection>

In the third scanning as well, the print head 21 moves by the pitch in the sub scanning direction Y with respect to the print medium 11 in the same manner as described above. In this state, the semi-discharge nozzle 201a, the non-discharge area 203, the second pass column P2, and the first pass column P1 on the one end side in the third pass column P3 are formed from the origin of the image, Is performed.

By this scanning, a band of the first layer is formed on the print medium 11 in the same manner as described above, adjacent to the band of the first layer formed by the second scan. Further, bands are formed on the band having the printing degree of 12.5% formed by the second scanning so that the printing accuracy is 37.5% by the scanning of the nozzle 201. [ In addition, bands are formed on the bands having the printing accuracy of 25% formed by the second scan so that the printing accuracy is 50% by the scanning of the nozzles 201. [ On the band having the printing degree of 37.5% formed by the second scan, bands are formed so that the degree of printing becomes 50% by scanning with the half discharge nozzle 201a.

When the ink droplets are ejected from the half ejection nozzle 201a, the ejection control section 73 performs ejection control based on the print data of the second pixel pattern, so that half of the remaining half of the ejected ink droplets at the end of the head unit HU21 Ink droplets are ejected from the nozzle 201a. Thus, a band of printing accuracy of 12.5% is formed on the band on which half of the pixels are formed by the first scan, through the band formed by the second scan, so as to complement the pixels scanned by the first scan.

In this manner, the ejection of the ink droplets by the semi-ejection nozzle 201a is performed over the two scans, whereby printing of 25% performed by one scan by the normal nozzle 201 is completed.

Further, on the band having the printing degree of 50% formed by the second scanning, the band not formed by the scanning of the non-ejection region 203 and the portion where the band is not formed by the scanning of the half ejection nozzle 201a and the printing degree of 62.5% There is a portion where a band is formed.

<Fourth injection>

Even in the fourth scan, the print band 21 moves in the same manner as described above. In this state, a part of the fourth pass column P4, the third pass column P3, the non-ejection region 203, the second pass column P2, and the scan by the first pass column P1 from the origin of the image .

By such scanning, the band of the first layer is formed adjacent to the band of the first layer formed by the third scan on the print medium 11, similarly to the above. On the band having the printing accuracy of 12.5% formed by the third scanning, the band is formed so that the printing accuracy is 37.5% by the scanning of the nozzle 201. [ On the band with the printing degree of 25% formed by the third scanning, bands are formed so that the degree of printing becomes 50% by the scanning of the nozzle 201. [ Furthermore, bands are formed on the band having the printing accuracy of 37.5% formed by the third scanning so that the degree of printing becomes 50% by scanning with the semi-discharge nozzle 201a.

On the band with the printing degree of 50% formed by the third scanning, the band is not formed by the scanning of the non-ejection region 203 and the portion where the band is printed by the half ejection nozzle 201a is 62.5% Is formed. On the bands having the printing degree of 50% formed by the second scanning and the third scanning, bands are formed so that the degree of printing is 75% by the scanning of the nozzles 201. Further, bands are formed on the bands having the printing accuracy of 62.5% formed by the third scanning so that the printing accuracy is 87.5% by the scanning of the nozzles 201.

&Lt;

Even in the fifth scan, the print head 21 moves in the same manner as described above. In this state, scanning by the fourth pass column P4, the third pass column P3, the non-ejection region 203, the second pass column P2 and the first pass column P1 is performed from the origin of the image Loses.

By such scanning, the band of the first layer is formed on the print medium 11 in the same manner as described above, adjacent to the band of the first layer formed by the fourth scan. Further, bands are formed on the bands having the printing accuracy of 12.5% formed by the fourth scan so that the printing accuracy is 37.5% by the scanning of the nozzles 201. On the band having the printing degree of 25% formed by the fourth scan, bands are formed so that the degree of printing becomes 50% by the scanning of the nozzle 201. [ Further, bands are formed on the band having the printing accuracy of 37.5% formed by the fourth scan so that the degree of printing becomes 50% by scanning with the semi-discharge nozzle 201a.

On the band with the printing degree of 50% formed by the fourth scan, the band is formed by the scanning of the non-ejection region 203 and the band where the band is not formed by the scanning of the half ejection nozzle 201a, Is formed. On the bands having the printing degree of 50% formed by the third scan and the fourth scanning, bands are formed so that the degree of printing is 75% by the scanning of the nozzles 201.

 On the band having the printing accuracy of 62.5% formed by the fourth scan, the band is formed so that the printing accuracy is 87.5% by the scanning of the nozzle 201. [ Further, bands are formed on the bands having the printing degree of 75% formed by the fourth scan so that the degree of printing becomes 100% by the scanning of the nozzles 201. Further, bands are formed on the band with the printing accuracy of 87.5% formed by the fourth scan so that the printing accuracy becomes 100% by scanning with the semi-discharge nozzle 201a.

(Overview of Embodiment)

<Non-ejection area>

The print head 21 of the present embodiment is formed by joining two head units HU21 and is provided with a non-ejection region 203 in which ink droplets are not ejected at the junction portion of the head unit HU21.

Thus, between the head units HU21, the non-ejection area 203 becomes a buffer zone, and the ink droplets ejected from the nozzle 201 at the end of the head unit HU21 do not interfere with each other. Therefore, even when the distance between the nozzle surface of the print head 21 and the print medium 11 is long, it is easy to adjust the mounting position of the print head 21 mechanically, Interference can be prevented.

<Non-Discharge Zone Length>

As long as the non-discharge region length d1 is longer than the adjacent nozzle-to-nozzle distance d2, at least one blank line can be set. Thus, when scanning is performed in the non-ejection region 203 having the non-ejection region length d1 longer than the adjacent nozzle-to-nozzle distance d2, a blank line (non-recording region) is formed on the band formed by the previous scanning . Therefore, even if the print head 21 is moved by a predetermined pitch width with respect to the print medium 11 in each scan as in the conventional inkjet printer, The band of the lower layer formed by the lower layer is shifted.

Since the boundaries of the first through seventh columns P1 through P4 are sequentially shifted as in the third through fifth scanning shown in Figs. 6A and 6B, for example, The boundaries of the bands formed by the result are also shifted with respect to the boundaries of the bands of the lower layer. As a result, the boundaries of the bands do not overlap, so that the boundaries between the bands are not conspicuous, and the occurrence of banding can be prevented.

<Half discharge nozzle>

The print head 21 has half discharge nozzles 201a at both ends of the head unit HU21. As a result, the portion of the pixel printed with the scanning by the semi-discharge nozzle 201a having a low density is compensated for by the next scan. Therefore, the concentration of the ink droplet does not change abruptly between the bands formed by the respective head units HU21, and it is possible to prevent occurrence of band streaks due to uneven ink density.

If the semi-discharge nozzles 201a are provided at both ends of the first to seventh pass P 1 to P 4, the above effect is further enhanced, but the number of overlapping portions to be printed is increased and the printing speed is lowered. On the other hand, by providing the semi-discharge nozzles 201a at both ends of the head unit HU21, it is possible to minimize the overlapping printing portion, thereby suppressing the decrease in printing speed to a minimum and improving the printing quality.

[Embodiment 2]

Details of the above-described print head 2 will be described with reference to Figs. 7, 8A and 8B.

On the other hand, in the present embodiment, constituent elements having the same functions as those in the above-described embodiment 1 are denoted by the same reference numerals, and the description thereof is appropriately omitted.

(Configuration of Print Head)

Fig. 7 is a plan view showing the configuration of the print head 22. Fig.

The above-described printhead 2 is configured as a printhead 22 as shown in Fig. The print head 22 has four head units HU22, and the head units HU22 are connected to each other.

The head unit HU22 has a plurality of nozzles 201 arranged in a row like the above-described head unit HU1, and the nozzle array 202 is constituted by these nozzles 201. [ A predetermined number of nozzles 201 at both end sides of the nozzle row 202 are set as half discharge nozzles 201a.

In the nozzle array 202, adjacent two nozzles 201 are disposed with a distance of a distance d2 between adjacent nozzles. The non-ejection area 203 is provided at the junction of the adjacent head unit HU22 with the above-described configuration as shown in any of Figs. 4 (a) to 4 (c). The non-ejection area length d1 of the non-ejection area 203 is longer than the adjacent nozzle-to-nozzle distance d2.

The nozzle array 202 of the head unit HU22 disposed at one end of the print head 22 corresponds to the first pass line P1 and the nozzle array 202 of the head unit HU22 And the nozzle array 202 of the adjacent head unit HU22 corresponds to the second pass column P2. The nozzle array 202 of the head unit HU22 disposed at the other end of the print head 22 corresponds to the fourth pass column P4 and the head unit HU22 adjacent to the head unit HU22 ) Corresponds to the third pass column P3.

On the other hand, the head unit HU22 has one pass column P, but may have two or more pass columns P.

The print head 22 is formed by combining head units HU22 of the same kind, but the present invention is not limited to this, and other types of head units may be combined.

(Printing operation by inkjet printer)

A multipass printing operation of the inkjet printer 1 using the print head 22 configured as described above will be described. 8 (a) shows the printing state of the inkjet printer 1 when viewed from the plane, and Fig. 8 (b) shows the same printing state as viewed from the side of the printing medium 11 (Viewed from the direction X).

8 (a), the print head 2 of each scan is shifted in the main scanning direction X so that the relative movement of the print head 2 with respect to the print medium 11 is easy to see, As shown in FIG.

In the following description, when the common reference is made to the first through fourth columns P1 through P4, it is simply referred to as a "pass column P".

The portion indicated by oblique lines in the print head 22 of Fig. 8A is an area where the half discharge nozzle 201a is provided. 8 (b), hatched portions are portions where ink droplets are ejected by the half ejection nozzle 201a, and "1" to "5" are ejected by the first to fifth inks, respectively Is a formed portion.

<First Injection>

As shown in Figs. 8A and 8B, in the first scan, scanning is performed by a part of the first pass column P1 from the origin of the image. At this time, the half-ejection nozzle 201a on the one end side in the first pass train P1 does not perform the scanning.

By this injection, a band is formed on the print medium 11 with the width of the nozzle 201 from which ink droplets are ejected. Of these bands, the area in which the ink droplets are ejected by the ordinary nozzle 201 is 25% of the printing degree, and the area where the ink droplets are ejected by the half ejection nozzle 201a is 12.5%.

When the ink droplets are ejected from the half ejection nozzle 201a, the ejection control section 73 performs ejection control based on the print data of the first field pattern, so that half of the half ejection nozzles Ink droplets are ejected from the ink chamber 201a. Accordingly, printing is performed in a state in which half of the pixels are filtered, and a band of 12.5% printing accuracy is formed.

<Second Injection>

In the second scanning, the print medium 11 is conveyed in the reverse direction to the sub-scanning direction Y by a predetermined pitch (band width) shorter than the pass line P, In the sub scanning direction Y by a band width. In this state, a portion of the second pass column P2, the non-ejection region 203, and the first pass column P1 are scanned from the origin of the image.

By such scanning, a band of the first layer is formed on the print medium 11 in the same manner as described above, adjacent to the band of the first layer formed by the first scan.

On the band having the printing accuracy of 12.5% formed by the first scan, bands are formed so as to have a printing accuracy of 25% by scanning with the semi-discharge nozzle 201a. On the other hand, bands are formed on the bands having the printing degree of 25% formed by the first scan so that the printing accuracy is 50% by the scanning by the nozzles 201.

The ejection control section 73 performs ejection control based on the print data of the second pixel pattern when ejecting the ink droplets from the half ejection nozzle 201a so that half of the remaining half number at the end of the head unit HU22 And ink droplets are ejected from the ejection nozzle 201a. Thus, a band of printing accuracy of 12.5% is formed on the band on which half of the pixels are formed by the first scan, so as to complement the pixels scanned by the first scan.

<Third Injection>

The print head 21 moves by the pitch in the sub scanning direction Y with respect to the print medium 11 in the same manner as described above. In this state, the non-ejection region 203, the second pass column P2, and the first pass column P1 are scanned from the origin of the image.

By this scanning, a band of the first layer is formed on the print medium 11 in the same manner as described above, adjacent to the band of the first layer formed by the second scan.

On the band having the printing accuracy of 12.5% formed by the second scan, bands are formed so that the printing accuracy is 25% by scanning with the half discharge nozzle 201a. A band is formed on the band having the printing degree of 50% formed by the first scan and the second scan so that the printing accuracy is 37.5% and 50% by the scanning of the half discharge nozzle 201a and the nozzle 201 . Further, bands are formed on the band having the printing accuracy of 37.5% formed by the second scan so that the printing accuracy becomes 50% by scanning with the half discharge nozzle 201a.

<Fourth injection>

Even in the fourth scan, the print head 21 moves in the same manner as described above. In this state, a part of the third pass column P3, the non-ejection region 203, the second pass column P2, the non-ejection region 203 and the first pass column P1 are scanned from the origin of the image . At this time, the scanning by the semi-discharge nozzle 201a on the one end side in the third pass train P3 is not performed.

By such scanning, the band of the first layer is formed adjacent to the band of the first layer formed by the third scan on the print medium 11, similarly to the above.

On the band having the printing accuracy of 12.5% formed by the third scanning, bands are formed so that the printing accuracy is 25% by scanning with the half discharge nozzle 201a. On the bands having the print degree of 50% formed by the second scan and the third scan, bands are formed so as to have a printing degree of 37.5% and 50%, respectively, by scanning of the half discharge nozzles 201a and the nozzles 201 do. On the band having the printing accuracy of 37.5% formed by the third scanning, bands are formed so that the degree of printing is 50% by scanning with the half discharge nozzle 201a. Further, bands are formed on the bands having the printing degree of 50% formed by the second scanning and the third scanning so that the printing accuracy is 62.5% and 75%, respectively, by the scanning of the half discharge nozzle 201a and the nozzle 201 do.

&Lt;

Even in the fifth scan, the print head 21 moves in the same manner as described above. In this state, a part of the fourth pass column P4, the non-ejection region 203, the third pass column P3, the non-ejection region 203, the second pass column P2, Scanning by the area 203 and the first pass column P1 is performed.

By such scanning, the band of the first layer is formed on the print medium 11 in the same manner as described above, adjacent to the band of the first layer formed by the fourth scan.

Bands are formed on the bands having the printing degree of 50% formed by the third and fourth scans so as to have a printing degree of 37.5% and 50%, respectively, by the injection of the semi-discharge nozzle 201a and the nozzle 201. [ On the band with the printing accuracy of 37.5% formed by the fourth scan, bands are formed so that the degree of printing becomes 50% by scanning with the semi-discharge nozzle 201a. On the bands having the printing degree of 50% formed by the third scan and the fourth scan, bands are formed with the printing degree of 62.5% and 75% by the scanning of the semi-discharge nozzle 201a and the nozzle 201, respectively. On the band having the printing accuracy of 6.25% formed by the fourth scan, bands are formed so as to have a printing ratio of 75% by scanning with the semi-discharge nozzle 201a. Furthermore, bands are formed on the band having the printing degree of 75% formed by the fourth scan so as to have a printing degree of 87.5% and 100%, respectively, by the injection of the half discharge nozzle 201a and the nozzle 201. [

(Overview of Embodiment)

<Non-ejection area>

The print head 22 of this embodiment is constituted by bonding four head units HU22 and a non-ejection region 203 in which ink droplets are not ejected is provided at the junction portion of the head unit HU22.

Thus, like the print head 21, the non-ejection region 203 becomes a buffer zone between the head units HU22, and the ink droplets ejected from the nozzle 201 at the end of the head unit HU22 interfere with each other Things are gone. Therefore, even when the distance between the nozzle surface of the print head 22 and the print medium 11 is long, the mounting position of the print head 22 is not mechanically adjusted, Can be prevented.

<Non-Discharge Zone Length>

The length of the non-ejection region d1 is longer than the distance d2 between the adjacent nozzles, so that the end portion of the band formed by the scanning at this time is displaced from the end portion of the lower layer formed by the previous scanning as in the print head 21 . Therefore, since the ends of the bands of the respective layers do not become the same line at the time of printing, the boundaries between the bands are not conspicuous, and banding can be eliminated.

<Half discharge nozzle>

The print head 22 has half discharge nozzles 201a at both ends of the head unit HU22. As a result, similarly to the print head 21, a portion where the pixel density is low due to scanning by the half discharge nozzle 201a is compensated by the next scan. Therefore, the density of the ink droplets is not reduced and changed between the bands formed by the respective head units HU21, so that occurrence of band streaks due to unevenness of the ink density can be prevented.

The print head 22 is provided with the half discharge nozzles 201a at both ends of the first pass column P1 to the fourth pass column P4 so that the print quality can be improved However, the printing speed is lowered because the number of overlapping portions to be printed increases. Therefore, the printhead 22 can be suitably used in a case where the print quality is more important than the print speed.

[Embodiment 3]

Details of the above-described print head 2 will be described with reference to Fig.

On the other hand, in the present embodiment, constituent elements having the same functions as those in the above-described embodiment 1 are denoted by the same reference numerals, and the description thereof is appropriately omitted.

Fig. 9 is a plan view showing the configuration of the print head 23. Fig.

The above-described print head 2 is configured as a print head 23 as shown in Fig. The print head 23 has two head units HU21 similar to the above-described print head 21, and is constituted by coupling the head units HU21 to each other.

The print head 23 is different from the print head 21 so that the head unit HU21 is aligned so as to be offset in a direction orthogonal to the sub scanning direction Y. [ The both head units HU21 are in contact with each other but may be separated from each other in the main scanning direction X and / or the sub scanning direction Y. [

Although not shown, both head units HU21 may be arranged in a positional relationship opposite to the head unit HU21 shown in Fig.

Printing is performed as shown in Figs. 6A and 6B even when multipass printing by the inkjet printer 1 is performed using the print head 23 configured as described above. Thus, as in the case of using the print head 21, it is possible to prevent interference of ink droplets with ease, eliminate banding, and prevent occurrence of band stripes due to unevenness in ink density.

[Embodiment 4]

Details of the above-described print head 2 will be described with reference to Figs. 10 and 11. Fig.

On the other hand, in the present embodiment, constituent elements having the same functions as those in the above-described embodiment 2 are denoted by the same reference numerals, and the description thereof is appropriately omitted.

10 is a plan view showing the configuration of the print head 24. As shown in Fig. 11 is a plan view showing the configuration of the print head 25. As shown in Fig.

The above-described printhead 2 is configured as a printhead 24 as shown in Fig. The print head 24 has four head units HU22 similarly to the above-described print head 22 and is constituted by coupling the head units HU22 to each other.

The print head 24 is coupled to the print head 22 in a so-called staggered arrangement (staggered arrangement) in which the print heads 22 are alternately offset in the opposite direction in the direction orthogonal to the sub-scan direction Y. In addition, each of the head units HU22 may be apart from each other in the main scanning direction X and / or the sub-scanning direction Y while adjacent ones are in contact with each other in part.

Although not shown, each head unit HU22 may be disposed in a positional relationship opposite to that of the head unit HU22 shown in Fig.

On the other hand, the above-described print head 2 is configured as a print head 25 as shown in Fig. The print head 25 has four head units HU22 similarly to the print head 22 described above and is constituted by coupling the head units HU22 to each other.

The print heads 25 are coupled to the print head 22 so as to lie in a so-called four-line arrangement, which is offset in the same direction orthogonal to the sub-scan direction Y, In addition, each of the head units HU22 may be apart from each other in the main scanning direction X and / or the sub-scanning direction Y while adjacent ones are in contact with each other in part.

Although not shown, each head unit HU22 may be disposed in a positional relationship opposite to that of the head unit HU22 shown in Fig.

Printing is performed as shown in Figs. 8 (a) and 8 (b) even when multipass printing by the inkjet printer 1 is performed using the print heads 24 and 25 configured as described above. Thus, as in the case of using the print head 22, it is possible to easily prevent the interference of ink droplets, to eliminate the banding, and to prevent occurrence of band stripes due to unevenness of ink density.

(Note)

The inkjet printer 1 includes a head unit HU1, HU21, HU22 having a nozzle array 202 composed of a plurality of nozzles 201 arranged along a sub-scanning direction Y perpendicular to the main scanning direction X, A discharge control section 73 for controlling the discharge of ink droplets in correspondence with the print data to the nozzles 201 and a discharge control section 73 for controlling the print heads 2 and 21 to 25 The driving roller 5 that moves the printing heads 2 and 21 to 25 relative to the printing medium 11 in the sub scanning direction Y for each scanning and the driven roller 6 and a sub-scan control unit 72, and prints a plurality of passes on the print medium 11 by one scan. This inkjet printer 1 has a non-ejection region 203 in which the print heads 2 and 21 to 25 do not eject ink droplets only between adjacent two head units HU1 to HU21 and HU22, The non-ejection region length d1 of the ejection region 203 in the sub-scanning direction Y is longer than the adjacent nozzle-to-nozzle distance d2 between the adjacent two nozzles 201. [

The printing method of the inkjet printer 1 includes a head unit HU1 having a nozzle array 202 composed of a plurality of nozzles 201 arranged along the sub scanning direction Y perpendicular to the main scanning direction X 21 to 25 in which a plurality of print heads 2, 21 to 25 are connected to the nozzles 201, HU 21, HU 22, 21 to 25 are moved relative to the print medium 11 in the sub scanning direction Y at every scanning and the printing medium 11 is transferred to the printing medium 11 in the main scanning direction X, And printing of a plurality of passes is performed by a scanning method. This printing method has a non-ejection region 203 in which ink droplets are not ejected only between adjacent two head units HU1, HU21 and HU22, and a non-ejection region 203 in the sub- The print heads 2 and 21 to 25 configured to make the non-ejection region length d1 longer than the adjacent nozzle-to-nozzle distance d2 between two adjacent nozzles 201 are used.

According to the above arrangement, scanning is repeated while moving the print heads 2, 21 to 25 with respect to the print medium 11, whereby the image is completed in the band in which printing by all the path rows P has been completed. In the print heads 2 and 21 to 25, since the non-ejection areas 203 are provided only between the adjacent two head units HU1, HU21 and HU22, The non-discharge area 203 becomes a buffer zone, and the ink droplets discharged from the nozzles 201 at the ends of the head units HU1, HU21 and HU22 do not interfere with each other. Therefore, even when the distance between the print heads 2 and 21 to 25 and the print medium is long, the mount positions of the print heads 2 and 21 to 25 are not mechanically adjusted, Interference of droplets can be prevented.

In addition, at least one blank line can be set by the length d1 of the non-ejection region being longer than the distance d2 between adjacent nozzles. Thus, when scanning is performed in the non-ejection region 203 having the non-ejection region length d1, a blank line (non-recording region) is formed on the band formed by the previous scanning. Therefore, even if the print heads 2 and 21 to 25 are moved in the sub-scan direction with respect to the print medium 11 by each scan as in the printing method of the conventional ink-jet printer, Is displaced from the band end of the lower layer formed by the previous scanning. Therefore, since the boundaries of the bands do not overlap, the boundaries between the bands are not conspicuous, and the occurrence of banding can be prevented.

In the inkjet printer 1, the driving roller 5, the driven roller 6, and the sub-scan control unit 72 are disposed in the sub-scan direction The discharge control section 73 relatively moves the first pixel pattern Y and the second pixel pattern Y with relatively shorter widths than the length of the path column P made up of the nozzles 201 corresponding to the paths, (Semi-discharge nozzle 201a) at both ends of the sub-scanning direction Y of each of the head units HU1, HU21, and HU22, and the data of the first pixel pattern It is preferable that the data of the second pixel pattern complementary to the residual nozzle 201 (half discharge nozzle 201a) at both ends is made correspondent to the data of the second pixel pattern.

The printing method is a method in which the print heads 2 and 21 to 25 are moved in the sub scanning direction Y with respect to the print medium 11 by the length of the path column P composed of the nozzles 201 corresponding to the paths And the printing is performed in the first pixel pattern in which pixels to be printed in the previous scanning are filtered by both ends of the sub scanning direction Y of each of the head units HU1, HU21 and HU22, It is preferable to print the second pixel pattern complementing the first pixel pattern in the subsequent scanning.

In the inkjet printer 1 configured as described above, the data of the first pixel pattern corresponds to a part of the nozzles 201 (half discharge nozzles 201a) at both ends of the head units HU1, HU21, and HU22 Therefore, ink droplets are ejected from the nozzles 201, thereby forming pixels in a filtered state. Since the data of the second pixel pattern corresponds to the remaining nozzles at both end portions of the head unit, ink droplets are ejected from the nozzles 201 in the subsequent scanning so that the pixels filtered by the previous scanning are complemented.

Further, in the printing method as described above, printing is performed in the first pixel pattern in which the pixels to be printed by the previous scanning are filtered by both end portions of the respective head units HU1, HU21, and HU22, do. In the subsequent scanning, printing is performed in the second pixel pattern by the above-mentioned both ends, so that the pixels which have been scanned in the previous time are formed to be complemented.

As a result, a portion of the pixel printed by one scan with a low density is supplemented by the next scan. Therefore, the concentration of the ink droplet does not change abruptly between the bands formed by the respective head units, and the occurrence of band streaks due to the unevenness of the ink density can be prevented. Therefore, the printing quality can be improved.

Industrial availability

In the inkjet printer employing the multi-pass method, the occurrence of band stripes between the respective bands is prevented, so that the present invention can be suitably used for applications requiring high print quality.

1: Inkjet printers
2: Printhead
3: Guide rail
4: Platen
5: drive roller
6: driven roller
7:
11: Printing medium
201: nozzle
202: nozzle column
203: non-ejection area

Claims (4)

A plurality of head units each having a nozzle array including a plurality of nozzles arranged along a sub-scanning direction perpendicular to a main scanning direction; a discharge control means for controlling to discharge ink droplets by associating print data with the nozzles; And a moving means for moving the print head in the main scanning direction and moving the print head relative to the print medium in the sub scanning direction for each scanning, In an ink-jet printer for printing a path,
Wherein the print head has a non-ejection region that does not eject the ink droplets only between two adjacent head units, and the non-ejection region length of the non-ejection region in the sub- Is greater than the distance between adjacent nozzles between the nozzles,
Wherein at least one blank line is formed by the non-ejection region length, and sub-scanning is performed so that boundary positions between print heads adjacent to each other in the non-ejection region are sequentially shifted. The method according to claim 1,
The moving means relatively moves the print head with respect to the print medium in the sub scanning direction at a width shorter than the length of the pass column made up of the nozzles corresponding to the pass,
Wherein the ejection control means sets the data of the first pixel pattern filtered by the pixels to be printed in correspondence with a part of the nozzles at both ends in the sub scanning direction of each head unit in the previous scanning, Wherein the data of the second pixel pattern complementary to the first pixel pattern is made to correspond to the remaining nozzles at the both end portions. And a plurality of head units each having a nozzle array including a plurality of nozzles arranged in a sub-scanning direction perpendicular to the main scanning direction, wherein the printing head is controlled to eject ink droplets by associating print data with the nozzles, An inkjet printer which moves the printhead in the main scanning direction and moves the printhead relative to the print medium in the sub scanning direction for each scan and prints a plurality of passes by one scan on the print medium, In the printing method of the present invention,
Ejection area of the non-ejection area in the sub-scanning direction is shorter than the length of the non-ejection area in the sub-scanning direction of the adjacent nozzles between adjacent two of the nozzles, Wherein the print head is configured to be longer than an inter-
Wherein at least one blank line is formed by the non-ejection region length, and sub-scanning is performed so that boundary positions between print heads adjacent to each other in the non-ejection region are sequentially shifted. . The method of claim 3,
The print head is relatively moved with a width shorter than the length of the pass column made up of the nozzles corresponding to the pass in the sub scanning direction with respect to the print medium,
The first pixel pattern to be printed is filtered by the both end portions of each head unit in the sub scanning direction, and in the subsequent scanning, a second pixel pattern Wherein the printing is performed by the printing method.

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