JP2009269373A - Image recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image recording apparatus capable of performing appropriate image recording by singling using a recording head with a small number of nozzles at both ends in an auxiliary scanning direction in the serial type ink-jet image recording device. <P>SOLUTION: An image by singling is completed by performing image recording the number of times set according to the difference in the number of nozzles between both end regions with a small number of nozzles and the other region for every region in the auxiliary scanning direction of a recording medium. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ink jet image recording apparatus, and more particularly to an image recording apparatus capable of appropriately performing image recording by shingling using recording heads having different numbers of nozzles at the center and both ends.

2. Description of the Related Art Inkjet image recording is used as various image recording apparatuses such as printers, copying apparatuses, and facsimiles.
Also, in a photo printer that reproduces an image taken by a camera such as a digital camera as a print, it has been proposed to use an inkjet instead of a so-called silver salt photograph printer.

As is well known, image recording by inkjet uses an (inkjet) recording head in which nozzles for ejecting ink droplets are arranged in one direction to record an image. Specifically, while moving the recording head and the recording medium (media) in a direction orthogonal to the nozzle arrangement direction, the ink droplets are modulated by modulating the driving of each nozzle according to the image to be recorded. Is ejected to record an image on a recording medium.
In addition, as one of the image recording by ink jet, the recording head is arranged in the sub-scanning direction (substantially) while the recording medium is intermittently conveyed (sub-scanning) in the predetermined sub-scanning direction. Serial type image recording is known in which an image is recorded by carrying (main scanning) in a main scanning direction orthogonal to the sub-scanning direction while conveyance of the recording medium is stopped.

In such serial type inkjet image recording, shingling as disclosed in Patent Document 1 and Patent Document 2 is known for the purpose of recording a high-quality image.
Singling is a method in which main scanning (image recording) is performed a plurality of times using different regions in the sub-scanning direction of the recording head for each region in the sub-scanning direction of the recording medium. ) Is an image recording method for completing the image.

  As an example, a single main scan (recording) ejects ink droplets in a staggered pattern to record an image of half the predetermined density, and a second main scan completes the predetermined density image. FIG. 8 shows image recording by a ring (twice single ring).

In FIG. 8, the main scanning direction is the x direction and the sub scanning direction is the y direction. In this recording method, in the first main scan, as shown in (A), only half of the nozzles on the upstream side in the sub-scanning direction of the recording head 200 are used, and ink is formed in a staggered pattern having a half density of a predetermined density. Drop a droplet.
Next, the recording medium P is sub-scanned by half the length of the recording head 200 in the main scanning direction (length of the nozzle row), and then the second main scanning is performed. In the second main scan, as shown in (B), the ink liquid is formed in a staggered pattern so as to fill the positions where the droplets were not ejected by the first main scan using the nozzles of the entire area of the recording head. Drop a drop. As a result, the second main scan is performed on the portion where the image is recorded in the first main scan to complete an image with a predetermined density.
Further, after sub-scanning the recording medium P in the same manner, the third main scanning is performed, and the entire area of the recording head 200 is used to drop ink droplets in a staggered pattern at positions where the second droplet is not ejected. By performing droplet ejection and completing an image of a predetermined density in a region where ink droplets were ejected in a staggered pattern only by the second scanning, the sub-scanning and main scanning are repeated in the same manner, An image having a predetermined density is recorded on the recording medium P.

  By performing such shingling, it is possible to prevent deterioration in image quality due to discharge variation due to individual differences of each nozzle by ejecting ink droplets with different nozzles in one region, and adjacent dots (adjacent to each other). In this way, it is possible to prevent bleeding of ink droplets that have landed (prevention of landing interference), increase the density (recording) of an image, etc., and record a high-quality image.

By the way, in the case of image recording by ink jet, it is considered that nozzles for ejecting ink droplets are arranged two-dimensionally in order to realize high density of ink droplet ejection capable of high-quality image recording. Yes.
However, in a recording head having such a two-dimensional nozzle arrangement, the nozzles are not necessarily arranged in a square lattice pattern.

For example, Patent Document 3 discloses that high-speed image recording is realized by increasing the length of the recording head in the sub-scanning direction by joining parallelogram-shaped recording heads.
In general, the recording head is produced using a semiconductor manufacturing technique. However, there is a limit to the size of the recording head that can be manufactured. In order to overcome this, it is conceivable to join a plurality of recording heads. However, simply joining them does not make the nozzle interval in the sub-scanning direction appropriate, and makes the nozzle interval in the sub-scanning direction appropriate. In this case, it is necessary to arrange the recording heads alternately in the main scanning direction.

  On the other hand, in Patent Document 3, the recording head and the nozzle array are formed in a parallelogram shape, and the recording head is joined with the oblique sides of the parallelogram, thereby enabling a recording head with an appropriate nozzle interval. .

JP 9-169109 A JP 2001-47664 A JP 2000-127401 A

However, such a recording head in which the nozzle arrangement is not a square lattice cannot perform the above-described shingling.
For example, the recording head disclosed in Patent Document 3 has a parallelogram-shaped nozzle array as conceptually shown in FIG. Therefore, in the case of performing the two-time single ring as described above, an image with a predetermined density can be recorded in two scans in the central nozzle region α where the nozzles are arranged in a square lattice pattern. However, in the nozzle region β at both ends in the sub-scanning direction in which the nozzle arrangement is a right triangle, the number of nozzles is (about) half, so when the same image recording is performed, the number of nozzles The recording density changes due to the difference. As a result, an image with a predetermined density cannot be recorded, and a desired image quality cannot be obtained.

  An object of the present invention is to solve the above-described problems of the prior art, and is an image recording apparatus using a serial type ink jet, in which both end portions in the sub-scanning direction, such as a recording head having a parallelogram nozzle array, are provided. To provide an image recording apparatus capable of appropriately performing image recording by shingling in an apparatus using a recording head having a small number of nozzles, and thus capable of recording a high-quality image using shingling. is there.

  In order to achieve the above object, the present invention provides a recording head in which nozzles for ejecting ink droplets are arranged, sub-scanning means for intermittently transporting a recording medium in a predetermined sub-scanning direction, and the sub-scanning direction. Main recording means for conveying the recording head in the main scanning direction orthogonal to the recording head, and the recording head has a configuration in which the number of nozzles is smaller in the predetermined area at both ends in the sub-scanning direction than in other areas. And recording a plurality of times of image recording using a nozzle in a different region of the recording head in the sub-scanning direction for each region of the recording medium in the sub-scanning direction, thereby completing an image of a predetermined density. In this case, for each area in the sub-scanning direction of the recording medium, an image is recorded a number of times set according to the difference in the number of nozzles between the predetermined area and the other area, thereby completing the image. Providing a characteristic image recording device To.

In such an image recording apparatus of the present invention, the conveyance length of the recording medium in the sub-scanning direction is set according to the length of the predetermined area in the sub-scanning direction and the length of the nozzle array area in the sub-scanning direction. It is preferable to change.
Further, it is preferable to set the number of times of image recording in an area in which an image is recorded only in the predetermined area according to a difference in the number of nozzles between the predetermined area and the other area. It is preferable to set the number of times of image recording in an area in which an image is recorded between the predetermined area and other areas in accordance with the difference in the number of nozzles.

The present invention relates to a serial type ink jet image recording apparatus using a recording head having a small number of nozzles at both ends in the sub-scanning direction, such as a recording head having a parallelogram nozzle arrangement, and performing shingling. The transport amount in each sub-scan is set according to the difference in the number of nozzles, the difference in the arrangement, the length in the sub-scan direction of the area where the number of nozzles is small, and each area in the sub-scan direction on the recording medium. In addition, an image is recorded with the set number of times of recording (number of times of shingling).
For this reason, according to the present invention, although the recording head having a small number of nozzles at both ends in the sub-scanning direction is used, the entire area of the nozzle forming surface of the recording head is used to appropriately perform image by shingling. Recording can be performed, and accordingly, a high-quality image using shingling can be appropriately created.

  Hereinafter, the image recording apparatus of the present invention will be described in detail based on a preferred embodiment shown in the accompanying drawings.

FIG. 1 conceptually shows an example of the image recording apparatus of the present invention.
An image recording apparatus 10 (hereinafter, referred to as a recording apparatus 10) illustrated in FIG. 1 is an ink jet printer that records an image on a recording medium P by ink jet, and includes a supply unit 12, a transport unit 14, and an image recording unit 16.
The recording apparatus 10 intermittently conveys the recording medium P in a predetermined sub-scanning direction (sub-scanning), and stops the recording head in a direction orthogonal to the sub-scanning direction while the conveyance of the recording medium P is stopped. This is a so-called serial type (shuttle type / carriage type) ink jet recording apparatus that records an image on a recording medium P by conveying (main scanning) a head unit of the (ink jet head).
In addition to the members shown in the drawing, the recording apparatus 10 includes a known guide provided in various image recording apparatuses such as a conveyance guide and conveyance means for the recording medium P, and various sensors for detecting the recording medium P. Members are arranged as needed.

In the recording apparatus 10, the supply unit 12 is a part that supplies the recording medium P to the transport unit 14, and includes a magazine loading unit 24 and a cassette loading unit 26 thereabove.
The magazine loading unit 24 is a part for loading a magazine 38 containing a recording medium roll 48 formed by winding a long recording medium P in a roll shape at a predetermined position.

The magazine 38 is a casing that can be opened and closed, and has flange rotation rollers 42 and 44 and a feed roller pair 46.
The flange rotation rollers 42 and 44 are rollers that are spaced apart from each other in the supply direction (conveyance direction) of the recording medium P. As an example, the flange rotation roller 42 is a drive roller that is rotated by a drive source (not shown), and the flange rotation roller 44 is a driven roller.

The feed roller pair 46 is a conveyance roller pair that conveys the recording medium P, and the two rollers are configured to be able to contact and separate by a known means.
Although not shown, one of the rollers of the feed roller pair 46 has a rotating shaft protruding outside the magazine 38 and a gear fixed to the end. When the magazine 38 is loaded at a predetermined position of the magazine loading unit 24, the gears of the feed roller pair 46 and the gears engaged with the drive source disposed in the magazine loading unit 24 are engaged with each other. As a result, the feed roller pair 46 is rotated by the drive source, and the recording medium P is sent out from the magazine 38 and conveyed to the conveying unit 14, or the recording medium P is drawn into the magazine 38.

The recording medium roll 48 is formed by winding a long recording medium P around a cylindrical core material.
Flange 40 is attached to both end faces of this recording medium roll 48. The flange 40 is a disk-shaped object having a diameter larger than that of the unused recording medium roll 48 and has a convex portion that is fitted into the core of the recording medium roll 48 at the center. The flange 40 is attached to the recording medium roll 48 by inserting the convex portion into the core material of the recording medium roll 48.

The recording medium roll 48 is mounted with the circumferential portion of the flange 40 on the flange rotation rollers 42 and 44 with the flange 40 mounted at both ends, and the front end of the recording medium P is sandwiched between the feed roller pair 46. In the state, it is accommodated in the magazine 38. Therefore, the flange rotation rollers 42 and 44 are positioned apart from each other in the conveyance direction of the recording medium P by a distance that allows the flange 40 to be stably placed.
As described above, the flange rotation roller 42 is a drive roller, and when the magazine 38 is loaded in the magazine loading unit 24, the feed roller pair 46 is engaged with the drive source of the recording apparatus 10. Accordingly, the recording medium roll 48 is rotated by the rotation of the flange rotation roller 42 to send out the recording medium P, and the recording medium P sent out from the recording medium roll 48 is conveyed to the conveying unit 14 by the feed roller pair 46. Is done.

The cassette loading unit 26 is a part for loading the cassette 28 at a predetermined position, and includes a loading table 30 and a feed roller 52.
The cassette 28 is a housing that accommodates a cut sheet-shaped recording medium P cut into a predetermined size and that has an upper surface (or only an opening for discharging the recording medium P) opened. The loading table 30 is a table for mounting and holding the cassette 28 in a predetermined position by a known housing mounting / holding means.

The feed roller 52 is a so-called D roller (half-moon roller) in which a part of the side peripheral surface is cut out to be a flat surface.
The feed roller 52 is disposed at a position where only the circumferential surface comes into contact with the uppermost recording medium P with a certain pressure when the cassette 28 containing the recording medium P is loaded at a predetermined position on the loading table 30. The The cassette 28 is a known means such as a mechanism using a plate material that supports the recording medium P from below and a spring that biases the plate material upward, and the uppermost recording medium P always has a predetermined height. Configured as follows.
Accordingly, when the feed roller 52 rotates, the circumferential surface of the feed roller 52 comes into contact with the uppermost recording medium P of the cassette 28, and this recording medium P is conveyed / discharged from the cassette 28 by pressure and frictional force. Then, the toner is supplied to the conveyance roller pair 70 of the conveyance unit 14.

The conveyance unit 14 is a part that conveys the recording medium P supplied from the supply unit 12 (the magazine loading unit 24 and the cassette loading unit 26) to the image recording unit 16, and includes a cutter 54, a back printing unit 56, and a width guide. 58, a guide roller 62, and eight conveyance roller pairs 64, 66, 68, 70, 72, 74, 76, and 78.
Here, the guide roller 62, the conveyance roller pairs 64, 66 and 68, and the cutter 54 correspond only to the recording medium P supplied from the magazine loading unit 24, and the conveyance roller pair 70 and 72 are from the cassette loading unit 26. Only the supplied recording medium P corresponds, and the other conveyance roller pairs 74, 76 and 78, the back printing unit 56, and the width guide 58 correspond to all the recording media P.

  The long recording medium P supplied from the magazine loading unit 24 is changed by the guide roller 62 from the horizontal direction to the vertical direction, and is conveyed by the conveying roller pairs 64, 66, and 68, and all the recording media P are supplied. It is conveyed to the conveyance roller pair 74 corresponding to the medium P.

Here, a cutter 54 for cutting the recording medium P is disposed between the conveying roller pairs 64 and 66.
For sending out the recording medium P from the magazine 38 and transporting the recording medium P by the transport roller pairs 64 and 66, the length of the recording medium P downstream from the cutting position by the cutter 54 is a length corresponding to the print size. When it is time to stop. Next, the cutter 54 is driven to cut the recording medium P, and the long recording medium P is used as a cut sheet-shaped recording medium P corresponding to the print size.

Further, before the cutting by the cutter 54, the conveying roller pair 68 is stopped, and a loop (bending) of the recording medium P is formed between the conveying roller pairs 66 and 68 as indicated by a dotted line in the drawing. It is formed.
As will be described later, a back print (back print) is recorded on the back surface of the recording medium P by the back print unit 56 while being transported later. Here, as described above, at the time of cutting by the cutter 54, the conveyance of the recording medium P is stopped. Therefore, at this time, if the leading edge of the recording medium P reaches the back print, it is necessary to stop the recording of the pack print.
On the other hand, by forming such a loop of the recording medium P upstream of the back printing unit 56, it is possible to make it unnecessary to stop the pack print recording due to the cutting by the cutter 54. Thus, it is possible to stably print on the back side, and to prevent the impact due to cutting from affecting the recording of the pack print. Further, by forming a loop of the recording medium P upstream of the conveying path (conveying roller pair 74) corresponding to all the recording media P, while the conveyance of the recording medium P for cutting by the cutter 54 is stopped, The recording medium P can be supplied from the magazine loading unit 26 to the conveyance roller pair 74, and highly efficient print output is possible.

  When the cutting by the cutter 54 is completed, the conveyance by the conveyance roller pairs 66 and 68 is started, and the cut sheet-shaped recording medium P cut to the size corresponding to the print is conveyed to the conveyance roller pair 74.

  On the other hand, the cut sheet-shaped recording medium P supplied from the cassette loading unit 26 (cassette 28) by the feed roller 52 is transported by the transport roller pair 70 and 72 and transported to the transport roller pair 74.

The recording medium P conveyed to the conveying roller pair 74 corresponding to all the recording media P is conveyed by the conveying roller pairs 74, 76, and 78 and reaches the width guide 58.
Here, the back printing unit 56 is disposed between the pair of conveying rollers 74 and 76. While the recording medium P is conveyed by the conveyance roller pairs 74 and 76, a back print (back printing) is recorded on the back surface (back surface of the image recording surface) by the back printing unit 56.
The back printing unit 56 is configured using, for example, a dot impact printer or an ink jet printer. Further, the back print information includes an image file name, image correction information, and the like.

The width guide 58 adjusts the position of the recording medium P supplied to the image recording unit 16 (sub-scanning roller pair 80) in the width direction (direction perpendicular to the transport direction = main scanning direction).
The width guide 58 is not particularly limited, and any known sheet-like position adjustment and positioning means can be used.

The recording medium P that has been positioned in the width direction by the width guide 58 is conveyed to the image recording unit 16 by the conveying roller pair 78.
2 is a top view of the image recording unit 16, FIG. 3A is a front view thereof (viewed from the upstream side in the conveyance direction of the recording medium P), and FIG. (Viewed from the same direction as 1) are conceptually shown.
The image recording unit 16 is a part that records (draws) an image on the recording medium P by inkjet, and includes a sub-scanning roller pair 80, a recording unit 82, a platen 84, a belt conveyor 86, a drying unit 88, A conveyance roller pair 90 is included.

As described above, the image recording unit 16 in the illustrated example has a predetermined conveyance length and intermittently sub-scans (conveys) the recording medium P in the sub-scanning direction indicated by the arrow y in the figure, and the head unit 92 described later. Is a so-called serial type ink jet recording means for recording an image by performing main scanning (conveyance) in the main scanning direction indicated by an arrow x in the drawing orthogonal to the sub-scanning direction. The main scanning may be performed in a reciprocating manner or only in one direction.
Here, the image recording unit 16 in the illustrated example does not complete an image with a predetermined density (predetermined image recording density) by one main scanning (image recording), but each region in the sub-scanning direction of the recording medium P. Every time, a so-called shingling image recording is performed in which an image of a predetermined density is completed by a plurality of main scans using different regions in the sub-scanning direction of the recording head 98 (ink ejection surface). Accordingly, the recording density by one main scanning is naturally lower than the predetermined density.

Note that the image recording apparatus of the present invention is not limited to an apparatus that only performs image recording by such shingling, and a normal mode in which an image of a predetermined density is completed by one main scan and a plurality of main scans. And a single ring mode for completing an image of a predetermined density.
In the image recording apparatus of the present invention, the practicable single ring is not limited to one type. For example, the super high image quality mode with the largest number of main scans, the high image quality mode with the second largest number of main scans, Multiple different single ringing modes are set, such as the normal mode with the third largest number of scans and the high-speed mode with the smallest number of main scans, with different numbers of main scans until an image with a predetermined density is completed. , It may be made selectable.

The sub-scanning roller pair 80 intermittently conveys the recording medium P for image recording onto the recording medium P by ink jet, and is a normal conveying roller pair.
Further, the belt conveyor 86 performs the same intermittent conveyance of the recording medium P after the rear end of the recording medium P is separated from the sub-scanning roller pair 80, and also moves the recording medium P that has finished image recording downstream. Similarly, it is a normal belt conveyor that conveys the paper (discharged from the image recording unit 16).
That is, the sub-scanning roller pair 80 and the belt conveyor 86 are sub-scanning (conveying) means in serial type ink jet. Here, in the illustrated example, the transport length of the recording medium P by one sub-scanning does not always have to be the same, and if necessary, the sub-scans at different distances are performed each time. Also good. This will be described in detail later.

The platen 84 is a flat table that holds a recording medium P used for image recording by inkjet at a predetermined recording position (a predetermined distance with respect to the recording head). The sub scanning roller pair 80 conveys the recording medium P to the platen 84.
The platen 84 has holding means for holding the recording medium P on the platen with a weaker force than the conveying force of the sub-scanning roller pair 80 or the belt conveyor 86 using suction, static electricity, or the like as necessary. May be.

  The recording unit 82 performs image recording by inkjet, and includes a head unit 92 having a recording head (inkjet head), a main scanning unit 94, and a control unit 96.

The head unit 92 is a head assembly in which four recording heads 98C, 98M, 98Y, and 98K are held by a holder 102. Hereinafter, the four recording heads 98C, 98M, 98Y, and 98K are collectively referred to as the recording head 98. The recording head 98 will be described later in detail.
In the present invention, the recording head 98 uses a piezo method that utilizes vibration by a piezo element (piezoelectric element), a thermal method that uses the pressure of bubbles generated in ink by a heating element, and a charge applied to ink droplets. All known inkjet recording heads such as an electrostatic system can be used.

The main scanning unit 94 reciprocates (main scans) the head unit 92 (that is, the recording head 98) in the main scanning direction. The main scanning means 94 carries the head unit 92 in the main scanning direction to perform main scanning in which the recording medium P and the recording head 98 are relatively moved.
In the illustrated example, the main scanning unit 94 conveys the head unit 92 by screw transmission, and includes a drive shaft 104, a guide shaft 106, and a rotation drive source 108.

  The drive shaft 104 is a so-called feed screw (screw shaft / lead screw), is arranged extending in the main scanning direction, and is rotated by the rotary drive source 108. As with the drive shaft 104, the guide shaft 106 is a long cylindrical guide member that extends in the main scanning direction.

The head unit 92 is held by both shafts by inserting the drive shaft 104 and the guide shaft 106 through the holder 102 that holds the recording head 98. Here, the insertion portion of the drive shaft 104 of the holder 102 is a screw (nut), and this screw is screwed into the drive shaft 104.
Accordingly, when the rotational drive source 108 rotates the drive shaft 104, the head unit 92 is main-scanned (conveyed) in the main scanning direction.
As will be described in detail later, the recording head 98 has a parallelogram-shaped ejection surface 120 as shown in FIG. 4, and the nozzles 122 are also arranged in a parallelogram. The head unit 92 has a state in which the long side of the parallelogram (that is, the long direction of the nozzle array) of the discharge surface 120 coincides with the sub-scanning direction (arrow y direction) and the discharge surface 120 faces the platen 84. The recording head 98 is held so that

  In the recording apparatus 10 of the present invention, the main scanning method (conveying method) of the head unit 92 is not limited to screw transmission as shown in the illustrated example. For example, a method using a belt or a pulley or a method using electrostatic force For example, a method used in a serial scan type ink jet printer can be used.

  The control means 96 controls the driving of the head unit 92, the sub-scanning roller pair 80, the belt conveyor 86, and the main scanning means 94 (rotation drive source 108).

  As described above, since the recording apparatus 10 is a serial type inkjet printer, in the image recording unit 16, the recording medium P is intermittently sub-scanned by the sub-scanning roller pair 80 and the like, and the recording medium P is conveyed. When the recording medium P is stopped, the head unit 92 is main-scanned by the scanning unit 82, and ink droplets are ejected from the nozzles of the heads according to the image to be recorded. Record the image on the entire surface.

As described above, the recording apparatus 10 performs image recording by shingling.
Here, as shown in the conceptual diagram of FIG. 4, the recording head 98 has a parallelogram-shaped ink droplet ejection surface (nozzle surface) 120, and the nozzle 122 also has a parallelogram shape of the ejection surface 120. They are uniformly arranged in parallel.
As described above, the recording head 98 is arranged with the long sides of the parallelogram aligned with the sub-scanning direction. Therefore, the recording head 98 has fewer nozzles 122 at both ends in the sub-scanning direction than the central portion. Specifically, the number of nozzles in the nozzle region β (predetermined region) corresponding to the short side of the parallelogram on the ejection surface 120 is half the number of nozzles in the same length in the sub-scanning direction of the other nozzle regions α. .

  The image recording apparatus of the present invention performs image recording by shingling using a recording head with a small number of nozzles in a predetermined area at both ends in the sub-scanning direction. For each area in the direction, main scanning is performed a number of times according to the difference in the number of nozzles between the predetermined area and the other areas, and an image with a predetermined density is recorded.

As an example, the recording apparatus 10 performs image recording in which the recording density by two main scans in the nozzle region α is set to a predetermined density of a completed image. Note that the ratio of nozzles used (nozzles used for discharging droplets) is the same in all regions, such as using all nozzles and using 50% of nozzles at one discharge timing.
Accordingly, in each area in the sub-scanning direction on the recording medium P, an area where all scanning is performed in the nozzle area α of the ejection surface 120 (recording head 98) completes an image with a predetermined density in two main scans. In the region including the scan by the nozzle region β on the ejection surface 120, an image having a predetermined density is completed by four main scans. In order to realize this, the conveyance in the sub-scanning depends on the length of the nozzle region β in the sub-scanning direction and the length of the ejection surface 120 (the nozzle array region of the recording head 98) in the sub-scanning direction. The length is also changed as appropriate.
Alternatively, in each region in the sub-scanning direction on the recording medium P, the region scanned by the nozzle region α and the nozzle region β may complete an image with a predetermined density by three main scans.

  That is, in this image recording, as conceptually shown in FIG. 5, the amount of recording by the upstream nozzle region β and the amount of recording by the downstream nozzle region β are reduced by the nozzle region α and the other side. Set the number of times of main scanning (singling) in consideration of the arrangement of nozzles and the number of nozzles so as to make up for the optimum image recording by filling in the nozzle area β (upper side is the lower side and lower side is the upper side). By selecting a nozzle for discharging droplets and recording an image by shingling, an image having a predetermined density is completed.

Therefore, according to the present invention, as shown in Patent Document 3, a proper image is recorded by shingling using a recording head in which the number of nozzles at both ends in the sub-scanning direction is smaller than that in other regions. be able to.
That is, according to the present invention, it is possible to record a high-quality image that has been shingled in such an image recording apparatus that uses a recording head having a different number of nozzles in the sub-scanning direction. Further, in the illustrated example, image recording that is normally performed in two main scans is performed four times with the nozzle 122 in a different region in the sub-scanning direction of the ejection surface 120 (recording head 98), although it is partial. As a result of performing the main scanning, it is possible to improve the image quality as the number of main scanning increases.

  In the present invention, the method of shingling is not limited to the above example, and all known shingling methods can be used.

For example, in the above example, an image is completed on the basis of two main scans (two times single ring), but the present invention is not limited to this, and three main scans (three times single ring). ) On the basis of four main scans (four times single ring) and more main scans, in a region where the number of nozzles is small, the difference in the number of nozzles and the arrangement are larger than the number of basic main scans. Accordingly, an image having a predetermined density may be completed by performing main scanning a set number of times as appropriate.
Ink droplet ejection may be performed by thinning out, or may be performed by all nozzles. In other words, the nozzles that eject ink droplets may or may not be thinned at one ink droplet ejection timing. That is, in the present invention, any ink droplet ejection method using a known shingling method can be used.
In the illustrated example, basically, ink droplets are ejected from all nozzle regions of the ejection surface 120 in all main scans. However, the present invention is not limited to this, and an image with a predetermined density is used. In order to complete the above, if necessary, there may be a nozzle region that does not eject ink droplets in the main scan set appropriately.
Furthermore, nozzles that eject ink droplets may be selected during main scanning in other nozzle regions in accordance with the arrangement positions of nozzles in predetermined regions at both ends in the sub-scanning direction, nozzle density, and the like. For example, in the illustrated example, when an image is recorded in the nozzle area α after the area previously recorded in the nozzle area β, the arrangement of nozzles that eject ink droplets in the nozzle area α is the nozzle You may select the nozzle to be used so that it may become the triangle shape which fills the area | region (beta).

In the illustrated example, the nozzle arrangement direction matches the main scanning direction and the sub-scanning direction, but the present invention is not limited to this.
For example, as shown in FIG. 6, the sub-scanning direction when the recording head having the parallelogram-shaped ejection surface and the nozzle arrangement is inclined with respect to the main / sub-scanning direction and projected in the main scanning direction. The nozzle density may be improved.

Here, when the arrangement of the nozzles is not a regular grid-like arrangement in the main scanning direction / sub-scanning direction (when the nozzle arrangement is irregular), a regular multiple times as described above. In some cases, it is impossible to perform main scanning.
In such a case, a nozzle that ejects ink droplets during main scanning is selected, and the main scanning for one region in the sub-scanning direction on the recording medium P is performed twice, three times, four times, and so on. The number of scans may be changed and dealt with step by step. In addition, by selecting such a method, the number of main scans for one area in the sub-scanning direction on the recording medium P increases, so that the effect of shinging can be expressed more favorably and a high-quality image can be recorded. Can do.

Furthermore, the present invention can suitably use a recording head having a rectangular parallelepiped discharge surface and a small number of nozzles at both ends in the main scanning direction.
An example is shown in FIG.

As shown in FIG. 7A, this recording head has a rectangular ejection surface parallel to the main scanning direction (arrow x direction) and the sub scanning direction (arrow y direction). In the predetermined nozzle region β at both ends, the density of the nozzles decreases stepwise toward the outside in the sub-scanning direction (upward and downstream outward direction).
In the illustrated example, as an example, the nozzle region β is divided into three in the sub-scanning direction, and the innermost region βc is a nozzle region α (nozzle region α other than the nozzle region β) that is the central region in the sub-scanning direction. At the density of 3/4, the middle area βb has the same density as 1/2 and the outer area βa has the density of 1/4, respectively, and the nozzles are arranged.

Using this recording head, for example, as shown conceptually in FIG. 7 (B), when sub-scanning is performed for each half of the nozzle region α (half in the sub-scanning direction) and image recording by shingling is performed. As an example, in the recording medium P, an area in which main scanning is performed only by the nozzle area α completes an image of a predetermined density by two main scannings, and an area including main scanning by the nozzle area β is, for example, Three main scans are performed to complete an image with a predetermined density.
In the main scanning for three times, the nozzle is selected in consideration of the nozzle density, the arrangement, etc., and the optimum image recording is performed, so that the image quality can be improved. Further, as in the previous example, the completion of an image that is normally performed by two main scans is partially performed, but three main scans are performed by region nozzles in different sub-scan directions of the recording head (ejection surface). By completing the image with, high image quality can be achieved.

As described above, an image is recorded on the recording medium P by the recording unit 82 while intermittent sub-scanning is performed by the sub-scanning roller pair 80 and the belt conveyor 86.
The belt conveyor 86 intermittently conveys the recording medium P as sub-scanning means during image recording, but continuously conveys the recording medium P when image recording is completed.
Further, the landed ink is dried by the drying means 88 on the recording medium P on which the image is recorded. The drying method using the drying means is not particularly limited, and may be a known means such as drying with a fan, drying with a heater, or a combination of a fan and a heater.

  The recording medium P transported by the belt conveyor 86 and dried with ink is then transported by the transport roller pair 90 and discharged to the tray 118 as a print.

  The image recording apparatus of the present invention has been described in detail above, but the present invention is not limited to the above-described embodiment, and various improvements and modifications may be made without departing from the spirit of the present invention. Of course.

It is a figure which shows notionally an example of the image recording device of this invention. FIG. 2 is a conceptual plan view of an image recording unit of the image recording apparatus shown in FIG. 1. (A) is a conceptual front view of the image recording unit of the image recording apparatus shown in FIG. 1, and (B) is a side view of the same. FIG. 2 is a diagram conceptually showing a droplet discharge surface of a recording head of the image recording apparatus shown in FIG. 1. It is a conceptual diagram for demonstrating the image recording by the image recording device shown in FIG. It is a conceptual diagram which shows the discharge surface of another example of the recording head which can be used for the image recording apparatus of this invention. (A) is a conceptual diagram showing an ejection surface of another example of a recording head that can be used in the image recording apparatus of the present invention, and (B) is a conceptual diagram for explaining image recording by this recording head. It is a conceptual diagram for demonstrating the conventional single ring. FIG. 3 is a conceptual diagram illustrating an example of a recording head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 (Image) recording device 12 Supply part 14 Conveyance part 16 Image recording part 24 Magazine loading part 26 Cassette loading part 28 Cassette 30 Mounting stand 38 Magazine 40 Flange 46 Feed roller pair 48 Recording medium roll 52 Paper feed roller 54 Cutter 56 Back surface printing Unit 58 Width guide 60 Turn roller 64, 66, 68, 70, 72, 74, 76, 78, 80, 90 Conveying roller pair 82 Recording means 84 Platen 86 Belt conveyor 88 Drying means 92 Head unit 94 Main scanning means 96 Control means 98,200 Recording head 102 Holder 104 Drive shaft 106 Guide shaft 108 Rotation drive source 118 Tray 120 Discharge surface 122 Nozzle

Claims (4)

A recording head in which nozzles for discharging ink droplets are arranged; a sub-scanning means for intermittently transporting a recording medium in a predetermined sub-scanning direction; and the recording head in a main scanning direction orthogonal to the sub-scanning direction. Main scanning means for
The recording head has a configuration in which the number of nozzles is smaller than in other regions in a predetermined region at both ends in the sub-scanning direction,
In addition, when an image having a predetermined density is completed by performing image recording a plurality of times using nozzles in different regions in the sub-scanning direction of the recording head for each region in the sub-scanning direction of the recording medium. Is characterized in that, for each region in the sub-scanning direction of the recording medium, image recording is performed a number of times set according to the difference in the number of nozzles between the predetermined region and another region, thereby completing an image. Image recording device.   The image recording apparatus according to claim 1, wherein a conveyance length of the recording medium in the sub-scanning direction is changed according to a length of the predetermined area in the sub-scanning direction and a length of the nozzle array area in the sub-scanning direction. .   The image recording apparatus according to claim 1, wherein the number of times of image recording in an area in which an image is recorded only in the predetermined area is set according to a difference in the number of nozzles between the predetermined area and another area.   The image according to any one of claims 1 to 3, wherein the number of times of image recording in an area in which an image is recorded is set between the predetermined area and the other area in accordance with a difference in the number of nozzles between the predetermined area and the other area. Recording device.

Images