JPWO2008129919A1 - Inkjet recording apparatus and inkjet recording method - Google Patents

Abstract

High quality without uneven color tone, uneven density, and glossiness even when one band is formed by multiple times of main scanning by the serial method, even when recording is performed by bidirectional movement in the main scanning direction. An ink jet recording apparatus and an ink jet recording method are provided. A recording medium transport mechanism 12 as sub-scanning means, a recording head 6 in which a plurality of nozzles 61 are provided in a row in the sub-scanning direction Y, and a carriage drive mechanism 11 as main scanning means are provided, In the inkjet recording apparatus 1 that forms one band by scanning, the recording head 6 is controlled so as to perform the recording operation in both forward scanning and backward scanning, and at least one of the forward scanning and backward scanning is recorded. In operation, there is provided a control unit 10 that controls ink ejection from the nozzles 61 by not assigning recording data to the nozzles 61 located in a predetermined region at the end of the recording head 6.

Description

  The present invention relates to an ink jet recording apparatus and an ink jet recording method, and more particularly to an ink jet recording apparatus that performs recording so as to form one band by scanning a recording head a plurality of times.

  In general, an ink jet recording apparatus (hereinafter, referred to as “ink jet recording apparatus”) is known as an ink jet recording apparatus that can flexibly meet the demand for a small variety of products. An ink jet recording apparatus records an image on a recording medium by ejecting ink from a nozzle provided on the surface of the recording head facing the recording medium, and landing and fixing on the recording medium. Conventional gravure printing Unlike the image recording means based on the system or flexographic printing system, it does not require a plate making process, and therefore can easily and quickly respond to a small amount of demand. In addition, there is an advantage that color image recording can be easily performed by using multi-color ink with less noise.

  As one example of such an ink jet recording apparatus, in a serial type ink jet recording apparatus that performs recording while scanning the recording head in a direction (main scanning direction) orthogonal to the conveyance direction (sub scanning direction) of the recording medium, the recording head Is formed a plurality of times in the main scanning direction to form one band (a region corresponding to the feed amount of the recording medium in the sub-scanning direction for each scan). In order to increase the recording speed, a bidirectional printing (recording) type apparatus is also known in which the recording head is moved in both directions in the main scanning direction and recording is performed in both the forward path and the backward path.

  However, in the case where one band is formed by a plurality of scans in this way, if the scanning direction for printing each band is different, the ejection order of ink ejected from each recording head, the difference in drying time, etc. As a result, a slight difference appears in the color tone and density, and uneven width (banding unevenness) corresponding to the feed amount of the recording medium in the sub-scanning direction occurs.

  Furthermore, in recent years, as an ink jet recording apparatus compatible with various recording media, for example, a photocurable ink containing a photoinitiator having a predetermined sensitivity to light such as ultraviolet rays is used to land on the recording medium. 2. Description of the Related Art An ink jet recording apparatus using a photocurable ink that cures ink and fixes it onto a recording medium by irradiating the ink with light is known. Inkjet recording apparatuses that perform recording using ink that is cured by irradiating active energy rays, such as an inkjet recording apparatus that uses such photo-curable ink, cause the ink to be instantaneously cured by irradiation of active energy rays. If the irradiation timing is different, there is a problem that the method of curing the ink is different, and the glossiness of the image is not constant. For this reason, there is a problem that the influence on the image quality due to the difference in scanning direction when recording each band is particularly large.

  Therefore, conventionally, as a technique for eliminating such banding unevenness with respect to color tone and density, for example, it has been proposed to perform recording in a plurality of main scans while appropriately performing thinning printing in the same main scan (for example, Patent Document 1 to Patent Document 3).

In addition, a recording pixel for one pixel of input image data is composed of a plurality of pixels, and a mixed color image is recorded, and in this case, recording is performed so that two or more colors of ink do not overlap each pixel (for example, Patent Document 4) or an ink jet printer that forms a belt-like scan print area corresponding to the scan width in the sub-scanning direction, where P is the arrangement pitch between the plurality of multi-nozzle ink jet print heads and W is the scan width, W < A technique for configuring a plurality of multi-nozzle inkjet printheads so as to satisfy the relationship of P <2W (see, for example, Patent Document 5) is also known.
JP-A-5-278232 JP-A-6-22106 Japanese Patent Laid-Open No. 6-24007 JP-A-6-106736 JP-A-8-156286

  However, the techniques described in Patent Literature 1 to Patent Literature 4 make unevenness difficult to see by recording a thinned image in each of a plurality of main scans, and are also described in Patent Literature 5. The technology prevents the occurrence of band spots that are emphasized due to the overlap of scan boundaries by preventing the scan boundaries in each scan print area (band) from overlapping.

  When such a method is used, when recording is performed in two-way movement in the main scanning direction, whether recording is performed in forward scanning or backward scanning at a certain number of scans in all bands. Since the order (the combination in the scanning direction of the recording operation) cannot be matched, there is a problem that the banding unevenness cannot be reduced completely.

  Accordingly, the present invention has been made to solve the above-described problems, and is a case where one band is formed by a plurality of main scans by a serial method, and in a bidirectional movement in the main scan direction. An object of the present invention is to provide an ink jet recording apparatus and an ink jet recording method capable of performing high-quality image recording without unevenness in color tone, unevenness in density, difference in glossiness, and the like when recording.

In order to solve the above problem, the invention described in claim 1 is an inkjet recording apparatus,
Sub-scanning means for moving the recording medium in the sub-scanning direction;
A recording head provided with a plurality of nozzles for ejecting ink on the recording medium in a row along the sub-scanning direction;
An ink jet recording apparatus, comprising: a main scanning unit that reciprocates the recording head in a main scanning direction orthogonal to the sub-scanning direction, and performing recording so as to form one band by scanning the recording head a plurality of times Because
The recording head is controlled to perform a recording operation in both the forward scanning and the backward scanning in the backward path of movement by the main scanning means, and in the recording operation of at least one of the forward scanning and the backward scanning, A control unit is provided that controls ink ejection from the nozzles by not assigning recording data to the nozzles located in a predetermined region at the end of the recording head.

The invention according to claim 2 is the inkjet recording apparatus according to claim 1,
The scanning by the main scanning unit and the scanning by the sub-scanning unit are alternately performed, the length of the nozzle row of the nozzle is L, the number of scans necessary to form one band is n, and the sub-scanning is performed. When the moving amount by which the scanning unit moves the recording medium in the sub-scanning direction for each scanning by the main scanning unit is M, the relationship of M ≦ L / (n + 1) is satisfied.
The predetermined area is an area corresponding to a length corresponding to a moving amount M of the recording medium scanned by the sub-scanning unit.

The invention according to claim 3 is the ink jet recording apparatus according to claim 1 or claim 2,
The main scanning means performs n + 1 times of scanning to form the one band when the number of scans n necessary to form the one band is an even number,
The control unit controls ink ejection from the nozzles by not assigning recording data to the nozzles located at different ends of the recording head in the recording operation of the forward scanning and the recording operation of the backward scanning. It is characterized by.

The invention according to claim 4 is the ink jet recording apparatus according to claim 1 or claim 2,
The main scanning means performs n + 1 times of scanning in order to form the one band when the number of scans n necessary to form the one band is an odd number,
The control unit controls ink ejection from the nozzles by not assigning recording data to the nozzles located at both ends of the recording head in one of the forward scanning and the backward scanning. It is said.

The invention according to claim 5 is the ink jet recording apparatus according to any one of claims 1 to 4, wherein:
The ink contains an active energy ray-curable compound and is characterized by being an active energy ray-curable ink that is cured by irradiation with an active energy ray.

The invention according to claim 6 is the ink jet recording method,
A sub-scanning step of moving the recording medium in the sub-scanning direction;
A main scanning step of reciprocating the recording head in a main scanning direction orthogonal to the sub-scanning direction;
In the main scanning step, one band is formed by ejecting ink onto the recording medium from a plurality of nozzles arranged in a line along the sub-scanning direction of the recording head, and scanning the recording head a plurality of times. A recording step of performing a recording operation so as to form an ink jet recording method comprising:
During the recording step, the recording head performs a recording operation in both forward scanning and backward scanning in the forward path of movement of the recording head, and the recording head in at least one of the forward scanning and the backward scanning The recording data is not assigned to the nozzles located in a predetermined area at the end of the recording medium.

The invention according to claim 7 is the ink jet recording method according to claim 6,
In the sub-scanning step, the main scanning step and the sub-scanning step are alternately performed, the length of the nozzle row of the nozzle is L, the number of scans necessary to form one band is n, Satisfying the relationship of M ≦ L / (n + 1), where M is the amount of movement by which the recording medium is moved in the sub-scanning direction for each scan in the main scanning step,
The predetermined region is a region corresponding to a length corresponding to a moving amount M of each scanning of the recording medium in the sub-scanning step.

The invention according to claim 8 is the ink jet recording method according to claim 6 or claim 7, wherein
In the main scanning step, when the number of scans n required to form the one band is an even number, the scan is performed n + 1 times to form the one band,
In the recording step, recording data is not assigned to the nozzles located at different ends of the recording head in the recording operation of the forward scanning and the recording operation of the backward scanning.

The invention according to claim 9 is the ink jet recording method according to claim 6 or claim 7,
In the main scanning step, when the number of scans n required to form the one band is an odd number, n + 1 times of scanning are performed to form the one band;
In the recording step, recording data is not assigned to the nozzles located at both ends of the recording head in one of the forward scanning and the backward scanning.

The invention according to claim 10 is the ink jet recording method according to any one of claims 6 to 9,
The ink contains an active energy ray-curable compound and is characterized by being an active energy ray-curable ink that is cured by irradiation with an active energy ray.

  According to the invention described in claims 1 and 6, the recording operation is performed in both the forward scan and the backward scan by the main scanning means, and at least one of the forward scan and the backward scan is performed. In the recording operation, the ink ejection from the nozzles is controlled by not assigning the recording data to the nozzles located in the predetermined area at the end of the recording head. Thus, for example, when one band is formed by six scans, the first scan is recorded by the forward scan and the second scan is recorded by the backward scan in any band. Repeatedly, the sixth scan is recorded in the backward scan, and in all bands, the order in which the forward scan or the backward scan is recorded at a certain number of scans (the recording operation is performed). Scanning direction combinations) can be matched, and banding unevenness due to differences in color tone, density, glossiness, etc. due to differences in ink ejection order, drying time, active energy ray irradiation timing, etc. for each band It is possible to prevent such an effect that a high-quality image can be formed.

  According to the invention described in claims 2 and 7, the predetermined area at the end of the recording head corresponds to a length corresponding to the amount of movement of the recording medium scanned by the sub-scanning means. High quality by preventing banding unevenness due to differences in color tone, density, glossiness, etc. due to differences in ink ejection sequence, drying time, active energy ray irradiation timing, etc. for each band It is possible to form an image.

  According to the invention described in claims 3 and 8, when the number of scans n required to form one band is an even number, the printing operation of the forward scanning and the backward scanning are performed. With this recording operation, recording data is not assigned to nozzles located at different ends of the recording head. As a result, the combination of the scanning directions of the recording operation can be matched in any band, and color tone, density, glossiness, etc. due to different ink discharge order, drying time, active energy ray irradiation timing, etc. for each band. It is possible to prevent banding unevenness due to the difference and to form a high-quality image.

  According to the invention described in claims 4 and 9, one of the forward scan and the backward scan when the number of scans n required to form one band is an odd number. In this recording operation, recording data is not assigned to the nozzles located at both ends of the recording head. As a result, the combination of the scanning directions of the recording operation can be matched in any band, and color tone, density, glossiness, etc. due to different ink discharge order, drying time, active energy ray irradiation timing, etc. for each band. It is possible to prevent banding unevenness due to the difference and to form a high-quality image.

  According to the invention described in claims 5 and 10, since the ink is an active energy ray-curable ink, it is possible to perform recording on various recording media. Even when performing image recording using such ink, it is possible to prevent occurrence of banding unevenness due to differences in color tone, density, glossiness, etc. due to differences in the irradiation timing of active energy rays, etc. There is an effect that an image can be formed.

1 is a top view illustrating a configuration of a main part of a first embodiment of an ink jet recording apparatus according to the present invention. FIG. 3 is a diagram illustrating each nozzle region of a recording head of the ink jet recording apparatus according to the first embodiment. FIG. 2 is a main block diagram showing an outline of a control configuration of the first embodiment of the ink jet recording apparatus according to the present invention. FIG. 3 is a schematic diagram illustrating a corresponding nozzle region of a recording head that records each band in the first embodiment. It is a figure showing each nozzle area of a recording head of a conventional ink jet recording apparatus. It is the schematic diagram which showed the nozzle area | region corresponding to the recording head which records each band in the inkjet recording device shown in FIG. 3 is a flowchart illustrating an inkjet recording method according to the first embodiment. FIG. 6 is a diagram illustrating each nozzle region of a recording head of an ink jet recording apparatus according to a second embodiment. It is the schematic diagram which showed the nozzle area | region corresponding to the recording head which records each band in 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 2 Recording medium 6 Recording head 7 Ultraviolet irradiation device 10 Control part 11 Carriage drive mechanism (main scanning means)
12 Recording medium transport mechanism (sub-scanning means)
61 Nozzle 62 Ink ejection surface X Main scanning direction Y Sub scanning direction

  Hereinafter, a first embodiment of an ink jet recording apparatus according to the present invention will be described with reference to FIGS. 1 to 7.

  First, as shown in FIG. 1, in the present embodiment, an ink jet recording apparatus 1 is an ink jet recording apparatus 1 based on a serial printing method. A platen 3 supported from the recording surface is provided.

  A bar-shaped guide rail 4 extending in the width direction of the recording medium 2 is provided above the platen 3. A carriage 5 is supported on the guide rail 4, and the carriage 5 is driven in the width direction of the recording medium 2 (hereinafter “main scanning” along the guide rail 4 by a carriage driving mechanism 11 (see FIG. 3) as main scanning means. (Referred to as direction X)).

  In addition, the inkjet recording apparatus 1 includes a recording medium conveyance mechanism 12 (see FIG. 3) that is configured by a conveyance roller 15 and the like and serves as a sub-scanning unit that feeds the recording medium 2 in a sub-scanning direction Y orthogonal to the main scanning direction X. Is provided. During image recording, main scanning by the carriage drive mechanism 11 and sub-scanning by the recording medium transport mechanism 12 are alternately performed. The recording medium transport mechanism 12 rotates the transport roller 15 to move the carriage. Each time scanning is performed by the drive mechanism 11, the recording medium 2 is conveyed from the upstream side in the sub-scanning direction Y to the downstream side by a predetermined amount in accordance with the operation of the carriage 5.

  As shown in FIG. 1, the carriage 5 corresponds to each color (black (K), cyan (C), magenta (M), and yellow (Y)) used in the ink jet recording apparatus 1 in the present embodiment. Four recording heads 6 are mounted. The recording heads 6 are formed in a substantially rectangular parallelepiped shape, and are arranged side by side so that their longitudinal directions are parallel to each other. The ink used in the inkjet recording apparatus 1 is not limited to this. For example, color inks such as light yellow (LY), light magenta (LM), and light cyan (LC), white ink, and transparent ink are used. You can also In this case, the recording head 6 corresponding to each ink is mounted on the carriage 5.

  As shown in FIG. 2, the surface of the recording head 6 facing the recording medium 2 is an ink ejection surface 62 in which a plurality of nozzles 61 are formed in a row along the longitudinal direction (sub-scanning direction Y) of the recording head 6. Each recording head 6 ejects ink from a nozzle 61.

  In the present embodiment, the inkjet recording apparatus 1 performs so-called multi-pass recording. Multi-pass printing is divided into several blocks of the nozzles 61 constituting the nozzle row, and the division of print data is distributed to these divided nozzles 61, so that the feeding (movement) of the recording medium 2 corresponds to the divided one block. This is an image recording method in which image recording is performed by intermittently transporting a certain amount, and all pixels constituting a certain region (one band) are filled by a plurality of scans (n passes). The nozzle array may be a straight array or a staggered array, but in this embodiment, a straight array is described as an example.

  In the inkjet recording apparatus 1 of the present embodiment, the length of the nozzle row of the nozzles 61 is L, the number of scans necessary to form one band is n, and the main drive by the carriage drive mechanism 11 is performed in the sub-scan. When the moving amount by which the recording medium transport mechanism 12 moves the recording medium 2 in the sub-scanning direction Y is M for each scanning in the scanning, the relationship of M ≦ L / (n + 1) is satisfied.

  Here, the length L of the nozzle row is not limited to the case where it is the length of the nozzle row in one recording head 6. For example, when two or more recording heads that discharge the same kind of ink are arranged in the sub-scanning direction Y, the total length of the nozzle arrays of the plurality of recording heads is the nozzle array. Length L.

  In this embodiment, as will be described later, the number of scans n (one band is formed) required to form one band (an area corresponding to the feed amount of the recording medium 2 in the sub-scanning direction Y for each main scan). The number of scans necessary to fill a pixel is 6 (6 passes), and the area where the nozzle 61 is provided (hereinafter referred to as “nozzle area”) is, for example, as shown in FIG. The area is divided into seven areas (nozzle areas A to G), which is one more than the number of scans n required to record one band. Each nozzle region A to G has a width dimension substantially the same as the width of one band (a region corresponding to the length corresponding to the movement amount M of each scanning of the recording medium 2 by the recording medium transport mechanism 12). In the recording head 6, recording data (a driving signal corresponding to the recording data) is assigned to each nozzle 61 by a control unit 10 (see FIG. 3) described later. From 61, ink ejection control is performed so as not to eject ink.

  In addition, when the length L of the nozzle row is divided by n + 1 and there is a remainder that is not divisible, the nozzle 61 corresponding to the remainder is not used for the printing operation. If a remainder is generated when the nozzle row length L is divided by n + 1, the remainder may not be included in the nozzle row length L.

  Further, as an irradiation device for irradiating ultraviolet rays as active energy rays for curing and fixing the ink ejected and landed on the recording medium 2 on both sides of the recording head 6 provided as a group in the carriage 5. An ultraviolet irradiation device 7 is provided.

  The ultraviolet irradiation device 7 has an ultraviolet light source (not shown) that irradiates ultraviolet rays. As this ultraviolet light source, for example, a high pressure mercury lamp, a low pressure mercury lamp, a metal halide lamp, a semiconductor laser, a cold cathode tube, an excimer lamp, or an LED (Light Emitting Diode) can be applied. It is not limited to what was illustrated to.

  The arrangement of the ultraviolet irradiation device 7 is not limited to this, and the ultraviolet irradiation device 7 may be provided between the recording heads 6. Further, the ultraviolet irradiation device 7 is not limited to being mounted in the carriage 5 and may be provided outside the carriage 5.

  Here, the ink used in this embodiment will be described.

  The ink used in the present embodiment is an ultraviolet curable ink having a property of being cured when irradiated with ultraviolet rays as active energy rays, and includes at least a polymerizable compound (including a known polymerizable compound) as a main component. ), A photoinitiator, and a coloring material. The photocurable ink is roughly classified into a radical polymerization ink containing a radical polymerizable compound as a polymerizable compound and a cationic polymerization ink containing a cationic polymerizable compound. Both inks are included in this embodiment. Each can be applied as an ink to be used. Further, a hybrid ink in which radical polymerization ink and cation polymerization ink are combined may be applied as the ink used in this embodiment. However, since cationic polymerization inks that have little or no inhibitory action on polymerization reaction due to oxygen are superior in functionality and versatility, it is particularly preferable to use cationic polymerization inks. The cationic polymerization ink is a mixture containing at least a cationic polymerizable compound such as an oxetane compound, an epoxy compound, and a vinyl ether compound, a photocationic initiator, and a coloring material.

  As the recording medium 2, recording media made of various materials such as various papers such as plain paper, recycled paper and glossy paper, various fabrics, various non-woven fabrics, resin, metal and glass can be applied. As the form of the recording medium 2, various forms such as a roll form, a cut sheet form, and a plate form can be applied.

  Next, the control configuration of the inkjet recording apparatus 1 according to the present embodiment will be described with reference to FIGS. 3 to 6.

  As shown in FIG. 3, the inkjet recording apparatus 1 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores various control programs, and a RAM (Random Access Memory) that temporarily stores image data and the like. (None of which are shown in the figure) and the like.

  The control unit 10 develops a control program recorded in the ROM in a work area of the RAM and executes it by the CPU.

  The control unit 10 is electrically connected to an image processing unit 13, a head driving unit 14 that drives the recording head 6, a recording head 6, a carriage driving mechanism 11, a recording medium transport mechanism 12, and an ultraviolet irradiation device 7. Yes.

  The image processing unit 13 decodes the encoded input image data sent from the host system 15 via the interface (I / F) 16 to a data format that can be processed by the inkjet recording apparatus 1, and records the recorded data. It is sent to the head drive unit 14. An external device (not shown) is connected to the host system 15 through a network, and the host system 15 and the external device send image data for recording to the ink jet recording apparatus 1 and the overall operation of the ink jet recording apparatus 1. An input for performing control is performed. Further, in the host system 15 and the external device, input for setting a driving frequency for driving the recording head 6 can be performed.

  The control unit 10 controls the head driving unit 14 to control how recording data is allocated to each nozzle of the recording head 6. As a result, an appropriate amount of ink is ejected from the nozzles 61 of the recording heads 6 so that a predetermined image is recorded on the recording medium 2.

  In addition, the control unit 10 controls the carriage driving mechanism 11 to reciprocate the carriage 5 in the main scanning direction X and performs recording so that the recording medium 2 is conveyed in the sub-scanning direction Y in accordance with the operation of the carriage 5. The operation of the medium transport mechanism 12 is controlled.

  Further, the control unit 10 controls the ultraviolet irradiation device 7 to irradiate the ink ejected onto the recording medium 2 with ultraviolet rays.

  In this embodiment, n scans (n is an even number) are required to form one band, and n + 1 scans are performed to form one band.

  Further, in the present embodiment, the control unit 10 performs the recording operation for the recording head 6 and the ultraviolet irradiation so as to perform the recording operation in both the forward scanning in the forward path and the backward scanning in the backward path of the movement in the main scanning direction X by the carriage drive mechanism 11. The device 7 is controlled. Further, in the recording operation of at least one of the forward scanning and the backward scanning, ink is ejected from the nozzles 61 by not assigning recording data to the nozzles 61 located in a predetermined nozzle region at the end of the recording head 6. Is to control.

  Here, the ink discharge control by the control unit 10 will be specifically described with reference to FIG.

  In FIG. 4, the vertical line breaks indicate the recording head 6 shown in FIG. 2, and the recording head 6 is illustrated as being shifted obliquely from the left hand side to the right hand side in FIG. 4. FIG. 2 schematically shows the relative positional relationship of the recording head 6 with respect to the recording medium 2 in each scan when recording is performed while the recording medium 2 is conveyed in the sub-scanning direction Y for each scan.

  In the present embodiment, as shown in FIG. 4, the inkjet recording apparatus 1 has a feed width of the recording medium 2 conveyed in the sub-scanning direction Y by one conveyance by the recording medium conveyance mechanism 12 that is a sub-scanning unit. When a band is used, the number of scans n required to form one band (the number of scans required to fill the pixels constituting one band) is six.

  As described below, the control unit 10 does not assign recording data to some of the nozzles 61. Accordingly, recording is performed without using some of the nozzles 61 for the recording operation, and the recording head 6 is scanned 6 + 1 times (= 7 times) in the main scanning direction X in order to form one band. In addition, the carriage driving mechanism 11, the recording medium conveying mechanism 12, and each recording head 6 are controlled.

  In FIG. 4, areas separated by a solid line are nozzle areas A to G of the recording head 6, and the nozzle area has seven nozzle areas A corresponding to the number of scans (seven times) performed to form one band. It is divided into ~ G.

  Each of the nozzle regions A to G is a region corresponding to a length corresponding to a moving amount (carrying amount) for each scanning of the recording medium 2 by the recording medium carrying mechanism 12 serving as a sub-scanning unit.

  In FIG. 4, the arrows shown in the areas separated by solid lines indicate whether the recording by each nozzle area is performed in the forward path or the backward path in the main scanning direction X, that is, the recording head 6 when recording is performed. This shows the scanning direction (movement direction). Of the areas separated by solid lines, blank areas (areas without arrows) are areas that are not used for the recording operation, and the control unit 10 is located in an area that is not used for the recording operation. By not assigning recording data to the nozzle 61, the ink ejection of the recording head 6 is controlled so that the ink is not ejected from the nozzle 61.

  In the actual recording operation, the position of the recording head 6 in the sub-scanning direction Y is fixed, and the recording medium 2 moves (conveys) by a predetermined amount in the sub-scanning direction Y. However, in FIG. The position of the recording medium 2 is fixed, and the relative position of the recording head 6 to the recording medium 2 is expressed as sequentially moving from the upstream side to the downstream side in the sub-scanning direction Y.

  In the present embodiment, the control unit 10 performs the printing operation on the nozzle region A located on the most upstream side (upper side in FIG. 4) in the sub-scanning direction Y among the nozzle regions A to G of the recording head 6 in the forward scanning. The control unit 10 controls the ink ejection of the recording head 6 so that ink is not ejected from the nozzle 61 by not assigning the recording data to the nozzle 61 located in the nozzle area A. In the backward scanning, among the nozzle areas A to G of the recording head 6, the nozzle area G located on the most downstream side (lower side in FIG. 4) in the sub-scanning direction Y is set as an area that is not used for the recording operation. No. 10 controls ink ejection of the recording head 6 so that ink is not ejected from the nozzle 61 by not assigning recording data to the nozzle 61 located in the nozzle region G. As described above, in the present embodiment, the control unit 10 performs the nozzle 61 (nozzle 61 located in the nozzle region A) positioned at a different end of the recording head 6 in the forward scanning recording operation and the backward scanning recording operation. Alternatively, by not assigning the recording data to the nozzles 61) located in the nozzle region G, the ink ejection from the nozzles 61 is controlled so that the nozzles 61 are not used.

  Specifically, for example, when attention is paid to band i in FIG. 4, the write-out portion of band i is recorded by a recording operation of forward scanning by the nozzle region G (right arrow in FIG. 4). Then, as the recording medium 2 is sequentially conveyed in the sub-scanning direction Y, the nozzle areas A to G that perform recording of the band i are also moved. Hereinafter, the recording of the band i is performed in the backward scanning by the nozzle area F (in FIG. 6 times in the order of the recording operation of the left arrow), the forward scanning by the nozzle region E (right arrow in FIG. 4), the backward scanning by the nozzle region D (left arrow in FIG. 4). Recorded by scanning. Then, in the recording operation of the forward scan (the rightward arrow in FIG. 4) by the nozzle area A which is the seventh scan for the band i, the control unit 10 ejects ink from the nozzles 61 located in the nozzle area A. Control not to let it. As a result, the write-out portion of band i starts in the forward scan, and is recorded in six scans while sequentially repeating the forward scan and the backward scan.

  Further, when attention is paid to the next band ii, the control unit 10 is positioned in the nozzle region G in the printing operation of the backward scanning (the left-pointing arrow in FIG. 4) by the nozzle region G which is the first scanning for the band ii. Control is performed so that ink is not ejected from the nozzles 61. As a result, the writing portion of the band ii is recorded by the recording operation of the forward scanning (the arrow pointing right in FIG. 4) by the nozzle region F. As the recording medium 2 is sequentially conveyed in the sub-scanning direction Y, the nozzle regions A to G that perform recording of the band ii are also moved. Hereinafter, the recording of the band ii is performed by the backward scanning by the nozzle region E (in FIG. Recording operation of leftward arrow), forward scanning by nozzle region D (rightward arrow in FIG. 4), backward scanning by nozzle region C (leftward arrow in FIG. 4), etc. Recorded by scanning. As a result, similarly to the band i, the writing portion of the band ii starts with the forward scan, and is recorded in six scans while sequentially repeating the forward scan and the backward scan.

  In contrast, conventionally, when one band is formed by a plurality of operations, the nozzle area of the recording head is divided into the same number as the number of scans, and the number of scans n required to form one band. In this case, one band was formed by n scans using the nozzles of all nozzle regions.

  That is, for example, when the number of scans n is 6, as shown in FIG. 5, the nozzle area of the recording head 8 is divided into six nozzle areas A to F that are the same as the number of scans, and one band is obtained by six scans. Form. In this case, as shown in FIG. 6, in the band iii, the writing portion starts with the forward scanning, whereas in the band iv, the writing portion starts with the backward scanning, and scanning of the recording operation for forming each band is performed. The combination of directions does not match.

  As described above, if the combinations of the scanning directions of the bands do not match, banding unevenness in which color tone and density unevenness occurs for each band due to a difference in the ink ejection order, drying time, and the like occurs. In particular, in the case of the ink jet recording apparatus 1 that uses ink that is cured by irradiating active energy rays such as ultraviolet rays, the timing of irradiating the active energy rays varies depending on the scanning direction. If the combinations in the scanning direction do not match, there will be a difference in glossiness etc. of the recorded image, and the overall image will not be high quality.

  In this regard, in the present embodiment, the control unit 10 switches the nozzle area that is not used for the recording operation between the recording operation of the forward scanning and the recording operation of the backward scanning, so that the writing portion starts in the outward scanning in any band, Since the forward scanning and the backward scanning are sequentially repeated, printing is performed in six scans. Therefore, the combinations of the scanning directions of the recording operations for forming each band match, and the tone, density unevenness, and gloss for each band. It is possible to prevent the occurrence of banding unevenness that causes variations in feeling.

  Next, the ink jet recording method in the present embodiment will be described with reference to FIG.

  When image data input from the host system 15 or an external device (not shown) via the interface (I / F) 16 is sent to the inkjet recording apparatus 1, the sent image data is subjected to decoding processing or the like by the image processing unit 13. Predetermined processing is performed and stored in the RAM or the like of the control unit 10. When all the data necessary for image recording for one scan is obtained, the control unit 10 controls each part of the apparatus so as to shift to a recording operation. Specifically, the control unit 10 controls the recording medium conveyance mechanism 12 so that the recording medium 2 is sequentially conveyed from the upstream side to the downstream side in the sub-scanning direction Y (step S1). The control unit 10 controls the carriage driving mechanism 11 to cause the recording head 6 mounted on the carriage 5 to scan the recording medium 2 along the main scanning direction X. The control unit 10 also controls the head driving unit 13. By controlling the above, each recording head 6 is operated, and a predetermined discharge amount of ink is discharged to a predetermined pixel in the forward path and the backward path in the main scanning direction X. Further, the control unit 10 controls the ultraviolet irradiation device 7 to irradiate the ink ejected onto the recording medium 2 with ultraviolet rays.

  Specifically, the control unit 10 first scans the recording head 6 from the left to the right in the main scanning direction X (forward scanning in the forward path, step S2). At the time of forward scanning in this forward path, the control unit 10 performs control so that recording data is not allocated to the nozzle 61 so that ink is not ejected from the nozzle 61 located in the nozzle region A. Next, the control unit 10 causes the recording head 6 to scan from the right to the left in the main scanning direction X (return scan in the return pass, step S3). During the backward scanning in the backward path, the control unit 10 performs control so that recording data is not assigned to the nozzle 61 so that ink is not ejected from the nozzle 61 located in the nozzle region G. The ink discharged onto the recording medium 2 is irradiated with ultraviolet rays from the ultraviolet irradiation device 7, whereby the ink is cured and fixed, and an image is recorded on the recording medium 2. The control unit 10 always determines whether or not the recording operation necessary for recording all images has been completed (step S4). If the recording operation has not been completed (step S4; NO), the control unit 10 returns to step 2 and performs forward scanning. And the backward scan is repeated alternately. On the other hand, when the recording operation necessary for recording all images is completed (step S4; YES), the control unit 10 ends the process.

  As described above, according to the present embodiment, the number of scans necessary to form one band by performing recording while repeating the forward scan and the backward scan in order, in which the writing portion starts in the forward scan in any band. Since one band is formed by n + 1 times of scanning, the order in which all bands are recorded by forward scanning or backward scanning at a certain number of scanning times (each band is formed). The combination of the recording operations in the scanning direction) matches.

  For this reason, even when bidirectional printing is performed for both the forward pass and the backward pass, and one band is formed by scanning a plurality of times (even number of times), the ink ejection order, the drying time, and the activity for each band. High-quality images can be formed by preventing occurrence of banding unevenness due to differences in color tone, density, glossiness, and the like due to differences in the irradiation timing of energy rays.

  In this embodiment, the case where one band is formed by six scans has been described as an example, but the number of scans necessary to form one band is not limited to this. For example, one band may be formed with a small number of scans such as four scans, or one band may be formed with a larger number of scans.

  Even in such a case, the scanning is performed n + 1 times necessary for forming one band. In addition, the nozzle area of the recording head is also divided into a number corresponding to the number of scans n + 1, and among these, the nozzle area located at the upstream end in the sub-scanning direction Y and the nozzle located at the downstream end in the sub-scanning direction Y The areas are areas that are not used for the printing operation alternately in the forward scanning and the backward scanning.

  In the present embodiment, in the forward scan, the nozzle area A located on the most upstream side (upper side in FIG. 4) in the sub-scanning direction Y among the nozzle areas A to G of the recording head 6 is not used for the recording operation. In the backward scanning, the nozzle region G located on the most downstream side (lower side in FIG. 4) in the sub-scanning direction Y among the nozzle regions A to G of the recording head 6 is not used for the recording operation. For example, the nozzle region G may not be used for the printing operation in the forward scan, and the nozzle region A may not be used for the printing operation in the backward scan.

  In this embodiment, image recording is performed using ink that is cured by irradiation with ultraviolet rays. However, the ink is not necessarily limited to this, and for example, ultraviolet rays, electron beams, X-rays, visible The ink may be cured by irradiating light other than ultraviolet rays such as light rays and electromagnetic waves such as infrared rays. In this case, a polymerizable compound that is polymerized and cured with light other than ultraviolet light and a photoinitiator that initiates a polymerization reaction between the polymerizable compounds with light other than ultraviolet light are applied to the ink. When using a photocurable ink that is cured by light other than ultraviolet light, a light source that emits the light is applied instead of the ultraviolet light source.

  The recording head 6 used in the ink jet recording apparatus 1 according to the present invention may be an on-demand system or a continuous system. In addition, as a discharge method, for example, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shear mode type, a shared wall type, etc.), an electro-thermal conversion method (for example, , Thermal ink jet type, bubble jet (registered trademark) type), electrostatic suction type (for example, electric field control type, slit jet type, etc.) and discharge type (for example, spark jet type, etc.) May be used.

  In addition, it is needless to say that the present invention is not limited to the above embodiment and can be modified as appropriate.

  Next, a second embodiment of the ink jet recording apparatus according to the present invention will be described with reference to FIGS. Note that the second embodiment differs from the first embodiment only in the number of scans necessary to form one band, and therefore, the points that differ from the first embodiment will be described below. To do.

  As in the first embodiment, the ink jet recording apparatus according to this embodiment includes a recording head 9 (see FIG. 8) mounted on a carriage (not shown). The ink jet recording apparatus also includes a carriage drive mechanism (not shown) as main scanning means and a recording medium transport mechanism (not shown) as sub-scanning means, and recording not shown by the recording medium transport mechanism. While the medium is moved in the sub-scanning direction Y, the recording head 9 mounted on the carriage is moved in the main scanning direction X by the carriage driving mechanism, and the recording operation is sequentially performed. The ink ejected from the recording head 9 is irradiated with ultraviolet rays as active energy rays from an ultraviolet irradiation device (not shown).

  In the present embodiment, the ink jet recording apparatus requires n scans (n is an odd number) to form one band, and performs n + 1 scans to form one band. .

  Hereinafter, in the present embodiment, a case where the number of scans n necessary for forming one band is three as described later will be described as an example.

  For example, as shown in FIG. 8, the surface of the recording head 9 facing the recording medium is an ink ejection surface in which a plurality of nozzles 91 are formed in a row along the longitudinal direction (sub-scanning direction Y) of the recording head 9. The recording heads 9 eject ink from the nozzles 91, respectively.

  For example, as shown in FIG. 8, the areas (nozzle areas) where the nozzles 91 are provided are four areas (nozzle areas A to D) that are one more than the number of scans n required to record one band. ). The recording head 9 is configured such that recording data (driving signal corresponding to the recording data) is assigned to each nozzle 91 by a control unit (not shown), thereby preventing ink from being ejected from a certain nozzle area. Ink ejection control is performed.

  Further, the ink jet recording apparatus includes a control unit (not shown) similar to that of the first embodiment.

  In the present embodiment, the control unit controls the recording head 9 and the ultraviolet irradiation device to perform the recording operation in both the forward scanning in the forward path and the backward scanning in the backward path of movement in the main scanning direction X by the carriage driving mechanism. It comes to control. Further, the control unit does not use the nozzle 91 by not assigning the recording data to the nozzles 91 located in the predetermined nozzle regions at both ends of the recording head 9 in one of the forward scanning and the backward scanning. Thus, ink ejection from the nozzle 91 is controlled.

  Here, the ink discharge control by the control unit will be specifically described with reference to FIG.

  9, as described in FIG. 4, for convenience of explanation, the position of the recording medium is fixed, and the relative position of the recording head 9 to the recording medium is downstream from the upstream side in the sub-scanning direction Y. It is the schematic diagram expressed as moving to the side sequentially. In FIG. 9, the vertical line breaks indicate the recording head 9 shown in FIG. 8, and the recording head 9 is obliquely shifted from the left hand side to the right hand side in FIG. 6 schematically shows the relative positional relationship of the recording head 9 with respect to the recording medium in each scan when recording is performed while the recording medium is conveyed in the sub-scanning direction Y.

  In the present embodiment, as shown in FIG. 9, the ink jet recording apparatus has a band for feeding the recording medium 2 conveyed in the sub-scanning direction Y by one conveyance by the recording medium conveyance mechanism that is a sub-scanning means. In this case, the number of scans n necessary to form one band is 3, and the control unit scans the recording head 9 3 + 1 times (= 4 times) in the main scanning direction X to obtain one scan. The carriage drive mechanism, the recording medium transport mechanism, and each recording head 9 are controlled so that a band is formed.

  In FIG. 9, areas separated by solid lines are nozzle areas A to D of the recording head 9, and there are four nozzle areas A corresponding to the number of scans (four times) performed to form one band. It is divided into ~ D.

  In FIG. 9, the arrows shown in the areas separated by solid lines indicate whether the recording by each nozzle area is performed in the forward path or the backward path in the main scanning direction X, that is, the recording head 9 when recording is performed. This shows the moving direction. Of the areas separated by solid lines, blank areas (areas without arrows) are areas that are not used for the recording operation, and the control unit is located in an area that is not used for the recording operation. By not assigning the recording data to the nozzle 91, the ink ejection of the recording head 9 is controlled so that the ink is not ejected from the nozzle 91.

  In the present embodiment, in the backward scan, the control unit, among the nozzle regions A to D of the recording head 9, the nozzle region A located in the most upstream side (upper side in FIG. 9) and the sub-scanning direction Y. The nozzle area D located on the most downstream side (lower side in FIG. 9) is set as an area not used for the recording operation, and the control unit does not discharge ink from the nozzle area A and the nozzle 91 located in the nozzle area D. Ink ejection of the recording head 9 is controlled so that recording data is not assigned to the nozzles 91 located in the area. In the forward scan, all the nozzle areas A to D of the recording head 9 are used for the recording operation, and ink is ejected from all the nozzles 91. As described above, in the present embodiment, the controller performs the nozzles 91 located at both ends of the recording head 9 (the nozzle 91 located in the nozzle area A and the nozzle 91 located in the nozzle area D) in the backward scanning printing operation. ) Is not assigned recording data, the ink ejection from the nozzle 91 is controlled so that the nozzle 91 is not used.

  Specifically, for example, when attention is paid to the band v in FIG. 9, the writing portion of the band v is recorded by the recording operation of the forward scanning by the nozzle region D (right arrow in FIG. 9). As the recording medium 2 is sequentially conveyed in the sub-scanning direction Y, the nozzle areas A to D for recording the band v are also moved. Hereinafter, the recording of the band v is performed by the backward scanning by the nozzle area C (in FIG. 9, Recording is performed by three scans in the order of the recording operation of the left arrow) and the forward scanning by the nozzle region B (right arrow in FIG. 9). Then, in the recording operation of the forward scan (the rightward arrow in FIG. 9) by the nozzle area A, which is the fourth scan for the band v, the control unit does not eject ink from the nozzles 91 located in the nozzle area A. In this way, control is performed so that recording data is not assigned to the nozzle 91. As a result, the band v starts to be written in the forward scan, and is recorded in three scans while sequentially repeating the forward scan and the backward scan.

  Further, paying attention to the next band vi, the control unit is located in the nozzle area D in the printing operation of the backward scanning (the left-pointing arrow in FIG. 9) by the nozzle area G which is the first scanning for the band vi. Control is performed so that ink is not ejected from the nozzle 91 by not assigning recording data to the nozzle 91. As a result, the writing portion of the band vi is recorded by the recording operation of the forward scanning by the nozzle region C (right arrow in FIG. 9). As the recording medium is sequentially conveyed in the sub-scanning direction Y, the nozzle areas A to D for recording the band vi are also moved. Hereinafter, the band vi is recorded by the backward scanning by the nozzle area B (leftward in FIG. 9). The recording operation is performed by three scans in the order of the recording operation of the arrow) and the forward scanning by the nozzle region A (the arrow pointing to the right in FIG. 9). As a result, similarly to the band v, the band vi starts to be written in the forward scan, and is recorded in three scans while sequentially repeating the forward scan and the backward scan.

  Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  Next, the ink jet recording method in this embodiment will be described.

  In the recording operation, the control unit first scans the recording head 9 from the left in the main scanning direction X to the right. At the time of forward scanning in this forward path, the control unit performs control so that ink is ejected from the nozzles 91 located in all the nozzle areas A to D. Next, the control unit scans the recording head 9 from the right to the left in the main scanning direction X. At the time of the backward scanning in the backward path, the control unit does not assign recording data to the nozzles 91 located in the areas so as not to eject ink from the nozzles 91 located in the nozzle area A and the nozzle area D. To control. The ink ejected onto the recording medium is irradiated with ultraviolet rays from an ultraviolet irradiation device, whereby the ink is cured and fixed, and an image is recorded on the recording medium. The control unit always determines whether or not the recording operation necessary for recording all images has been completed. If the recording operation has not been completed, the forward scanning and the backward scanning are alternately repeated. On the other hand, when the recording operation necessary for recording all images is completed, the control unit ends the process.

  As described above, according to the present embodiment, the writing portion starts in the forward scan in any band and is recorded in three scans while sequentially repeating the forward scan and the backward scan. Combinations in the scanning direction of the recording operations for forming the bands are the same. For this reason, even in the case of performing bi-directional printing in which printing is performed for both the forward pass and the return pass, and even when one band is formed by scanning multiple times (odd times), the ink ejection order, drying time, and activity for each band High-quality images can be formed by preventing occurrence of banding unevenness due to differences in color tone, density, glossiness, and the like due to differences in the irradiation timing of energy rays.

  In this embodiment, the case where one band is formed by three scans is taken as an example, but the number of scans necessary to form one band is not limited to this. For example, one band may be formed by five scans or the like.

  Even in such a case, the scanning is performed n + 1 times necessary for forming one band. In addition, the nozzle area of the recording head is also divided into a number corresponding to the number of scans n + 1, and among these, the nozzle area located at the upstream end in the sub-scanning direction Y and the nozzle located at the downstream end in the sub-scanning direction Y The area is an area that is not used for the printing operation in either the forward scan or the backward scan.

  In the present embodiment, ink is not ejected from the nozzles 91 located in the nozzle area A and the nozzle area D during the backward scanning, but in the nozzle area A and the nozzle area D during the forward scanning. Ink may not be ejected from the nozzle 91 located.

  Other than that, the present invention is not limited to the present embodiment, as in the first embodiment.

Claims (10)

Sub-scanning means for moving the recording medium in the sub-scanning direction;
A recording head provided with a plurality of nozzles for ejecting ink on the recording medium in a row along the sub-scanning direction;
An ink jet recording apparatus, comprising: a main scanning unit that reciprocates the recording head in a main scanning direction orthogonal to the sub-scanning direction, and performing recording so as to form one band by scanning the recording head a plurality of times Because
The recording head is controlled to perform a recording operation in both the forward scanning and the backward scanning in the backward path of movement by the main scanning means, and in the recording operation of at least one of the forward scanning and the backward scanning, An ink jet recording apparatus comprising: a control unit that controls ink ejection from a nozzle by not assigning recording data to a nozzle located in a predetermined region at an end of the recording head. The scanning by the main scanning unit and the scanning by the sub-scanning unit are alternately performed, the length of the nozzle row of the nozzle is L, the number of scans necessary to form one band is n, and the sub-scanning is performed. When the moving amount by which the scanning unit moves the recording medium in the sub-scanning direction for each scanning by the main scanning unit is M, the relationship of M ≦ L / (n + 1) is satisfied.
2. The ink jet recording apparatus according to claim 1, wherein the predetermined area is an area corresponding to a length corresponding to a moving amount M of the recording medium scanned by the sub-scanning unit. The main scanning means performs n + 1 times of scanning to form the one band when the number of scans n necessary to form the one band is an even number,
The control unit controls ink ejection from the nozzles by not assigning recording data to the nozzles located at different ends of the recording head in the recording operation of the forward scanning and the recording operation of the backward scanning. An ink jet recording apparatus according to claim 1 or claim 2 characterized by the above-mentioned. The main scanning means performs n + 1 times of scanning in order to form the one band when the number of scans n necessary to form the one band is an odd number,
The control unit controls ink ejection from the nozzles by not assigning recording data to the nozzles located at both ends of the recording head in one of the forward scanning and the backward scanning. An ink jet recording apparatus according to claim 1 or claim 2.   The ink is an active energy ray-curable ink that contains an active energy ray-curable compound and cures when irradiated with an active energy ray. The inkjet recording device according to any one of the items. A sub-scanning step of moving the recording medium in the sub-scanning direction;
A main scanning step of reciprocating the recording head in a main scanning direction orthogonal to the sub-scanning direction;
In the main scanning step, one band is formed by ejecting ink onto the recording medium from a plurality of nozzles arranged in a line along the sub-scanning direction of the recording head, and scanning the recording head a plurality of times. A recording step of performing a recording operation so as to form an ink jet recording method comprising:
During the recording step, the recording head performs a recording operation in both forward scanning and backward scanning in the forward path of movement of the recording head, and the recording head in at least one of the forward scanning and the backward scanning An ink jet recording method, wherein recording data is not assigned to a nozzle located in a predetermined region at an end of the ink jet recording apparatus. In the sub-scanning step, the main scanning step and the sub-scanning step are alternately performed, the length of the nozzle row of the nozzle is L, the number of scans necessary to form one band is n, Satisfying the relationship of M ≦ L / (n + 1), where M is the amount of movement by which the recording medium is moved in the sub-scanning direction for each scan in the main scanning step,
7. The ink jet recording method according to claim 6, wherein the predetermined area is an area corresponding to a length corresponding to a moving amount M for each scanning of the recording medium in the sub-scanning step. In the main scanning step, when the number of scans n required to form the one band is an even number, the scan is performed n + 1 times to form the one band,
7. The recording step according to claim 6, wherein in the recording step, recording data is not allocated to the nozzles located at different ends of the recording head in the recording operation of the forward scanning and the recording operation of the backward scanning. The ink jet recording method according to claim 7. In the main scanning step, when the number of scans n required to form the one band is an odd number, n + 1 times of scanning are performed to form the one band;
8. The recording process according to claim 6, wherein recording data is not allocated to the nozzles located at both ends of the recording head in one of the forward scanning and the backward scanning in the recording step. The inkjet recording method according to item.   The said ink is an active energy ray-curable ink which contains an active energy ray-curable compound and is cured by irradiating with an active energy ray. The inkjet recording method according to any one of the items.