JP7549517B2 - Inkjet recording device - Google Patents

Description

The present invention relates to an inkjet recording device that ejects photocurable ink.

In recent years, inkjet recording devices have become widespread, which are equipped with a mounting table on which a recording medium is placed, a nozzle head having nozzles that eject photocurable ink onto the recording medium placed on the mounting table, and a light irradiator that irradiates light to the photocurable ink ejected from the nozzle onto the recording medium to solidify it.
The light irradiator is integrated with a nozzle head to form a head unit, and photocurable ink is ejected from the nozzle while scanning the head unit over the recording medium, and the ink is irradiated with light from the light irradiator immediately after ejection, thereby fixing a good image on the recording medium. As photocurable ink, ultraviolet-curable ink that can be cured by ultraviolet light is well known, and an ultraviolet irradiator is used in response to this.

Recently, many inkjet printing devices have been devised that are equipped with a table (mounting platform) on which a recording medium is placed. For example, Patent Document 1 discloses an inkjet recording device that forms an image by ejecting photocurable ink in a multi-pass method onto a recording medium placed on the mounting platform. In this inkjet recording device, a light irradiator is integrally assembled on both sides of the print head, and multi-pass printing is performed while moving the nozzle head and light irradiator in the scanning direction. In multi-pass printing, the nozzle head and light irradiator gradually approach the mounting platform from outside the mounting platform and start recording the first pass from one end of the recording medium, and Patent Document 1 is designed to minimize unnecessary light irradiation.

JP 2015-074161 A

However, in an inkjet printing device equipped with such a table, the print head must be moved relative to the table, which inevitably increases the size of the device, limiting the environments in which it can be installed.
In addition, the floor or table on which an inkjet printing device equipped with such a table is installed may reflect the light emitted from the light emitter, and a large amount of reflected light may occur, particularly if the floor or table is made of a material with a relatively high reflectivity.
If this reflected light is incident on the periphery of the nozzles of the print head, it can harden the light-curable ink at the tip of the nozzle, which can cause ejection defects of the light-curable ink.

The present invention was conceived in response to the above circumstances, and aims to provide a more compact inkjet printing device, and further to reduce or prevent reflected light from entering the nozzle from the floor or table on which the inkjet printing device is placed.

In order to achieve the above object, an inkjet printing apparatus according to the present invention comprises:
a print head having a plurality of nozzles that eject ink, the print head ejecting ink from the nozzles while moving in a scanning direction that is substantially perpendicular to the nozzle arrangement direction (sub-scanning direction);
a table on which a medium is placed and which is arranged to be movable relative to a print head in a nozzle arrangement direction; and an inkjet recording device which sets unit areas for forming an image on the recording medium by a plurality of printing passes and ejects ink onto the recording medium based on raster data for each unit area,
an arrangement control means for controlling the arrangement of the print heads relative to the table in the arrangement direction between a position where a start nozzle located at a start end in the arrangement direction faces a unit area located at the start end of the recording medium and a position where a terminal nozzle located at an end end faces a unit area located at the end of the recording medium;
a first print control means for fixing the position of the table relative to the print head in the arrangement direction by a placement control means, and for executing all printing passes set for a unit area located at the start end by a start nozzle, and for executing all printing passes set for a unit area located at the end end by a end nozzle, thereby forming an image in each unit area;
a second print control means for performing a plurality of print passes from a unit area adjacent to the unit area located at the start end to a unit area adjacent to the unit area located at the end end, while moving the table in the arrangement direction by the arrangement control means, to form an image;
The present invention is characterized by comprising:
With this configuration, the relative movement range of the table with respect to the print head can be limited to a position where the unit area located at the starting end faces the starting nozzle, to a position where the unit area located at the end faces the terminal nozzle, making the movement range smaller than before.
By making the range of relative movement of the table with respect to the print head smaller than in the past, the size of the inkjet printing device can be made more compact.

In addition, the inkjet printing apparatus of the present invention is
a print head having a plurality of nozzles that eject ink, the print head ejecting ink from the nozzles while moving in a scanning direction that is substantially perpendicular to the nozzle arrangement direction (sub-scanning direction);
a table on which a recording medium is placed and which is arranged to be movable relative to a print head in a nozzle arrangement direction; and an inkjet recording device which sets unit areas on the recording medium for forming an image by a plurality of printing passes, and ejects ink onto the recording medium based on raster data for each unit area,
an arrangement control means for controlling the arrangement of the print head relative to the table in the arrangement direction between a position where an end nozzle located at one end in the nozzle arrangement direction faces a unit area located at one end of the recording medium, and a position where the end nozzle faces a unit area located at the other end of the recording medium;
a first print control means for fixing the position of the table relative to the print head in the arrangement direction by a placement control means and for causing the end nozzles to execute all printing passes set for a unit area located at one end to form an image;
The apparatus is characterized by comprising a second print control means which forms an image by executing multiple printing passes on each unit area excluding the unit area in which the image is formed by the first print control means while relatively moving the table in the arrangement direction by the arrangement control means.
With this configuration, the table moves relatively between a position where a unit area located at one end faces an end nozzle located at one end and a position where a unit area located at the other end faces an end nozzle located at one end, thereby making it possible to reduce the range of movement of the table compared to conventional methods.
One end can be the start end or the end end. When one end is the start end, the relative movement range of the table is between a position where the unit area located at the start end faces the end nozzle located at the start end and a position where the unit area located at the end face the end nozzle located at the start end. When one end is the end end, the relative movement range of the table is between a position where the unit area located at the end face the end nozzle located at the end end and a position where the unit area located at the start end faces the end nozzle located at the end end.
By thus making the range of relative movement of the table with respect to the print head smaller than in the past, the size of the inkjet printing device can be made more compact.

In addition, the inkjet printing apparatus of the present invention is
The ink is a photocurable ink,
The printer is characterized by having a light irradiator that is integrated into the print head and irradiates the light-curable ink ejected onto the medium with light rays to cure the light-curable ink.
By providing a light irradiator to a print head that has a shorter relative movement distance to the table than before, for example, when executing all printing passes using the nozzle located at the start end for a unit area located at the start end, or when executing all printing passes using the nozzle located at the end end for a unit area located at the end, the print head is not positioned outside the table, and this makes it possible to reduce the amount of light reflected from outside the table or from outside the inkjet printing device more than before. This makes it possible to reduce the amount of unnecessary light incident on the nozzle and reduce the occurrence of poor ejection of photo-curable ink.
As the photocurable ink, for example, an ultraviolet curable ink that is cured by ultraviolet rays in a specific wavelength range can be used, and as the light irradiator, an ultraviolet irradiator that irradiates ultraviolet rays in a specific wavelength range can be used.

In addition, the inkjet printing apparatus of the present invention is
an input unit for inputting information on an end position of the recording medium placed on the table;
The position control means may move the table relative to the print head in advance based on position information from the input means, to perform cueing before the start of printing.
With this configuration, even if the starting end of the table is relatively far from the starting end of the recording medium, the print head unit is moved relative to the table in the nozzle arrangement direction to properly position the recording medium before printing begins. Therefore, for example, when all printing passes are performed using the nozzle located at the starting end for a unit area located at the starting end, it is possible to further prevent unnecessary light rays from entering the nozzle, and to more reliably reduce the amount of light rays entering from outside the table.

In the inkjet printing apparatus of the present invention,
When there is a non-recording area in a printing pass where photo-curable ink is not ejected, the first print control means may perform control to block or turn off the light irradiation from the light irradiator in correspondence with the non-recording area.
By blocking or turning off the light irradiation in non-recording areas, such as recording media having cutouts or recording media arranged at a distance, the amount of light reflected by the table can be reduced, further suppressing the amount of unnecessary light entering the nozzle.

In the inkjet printing apparatus of the present invention,
the light irradiator includes a plurality of light irradiating elements arranged in accordance with the plurality of nozzles;
The first print control means may block or turn off the irradiation of each of the light emitting elements corresponding to the non-recording areas.
This configuration allows for finer light irradiation and further reduces the incidence of unwanted light rays into the nozzle.
The number of ultraviolet irradiation elements arranged in accordance with the nozzle arrangement may be the same as the number of nozzles, but does not have to be the same number, and can be determined appropriately based on, for example, the irradiation intensity of the ultraviolet irradiation elements and the curing characteristics of the photocurable ink.

The relative movement range of the table with respect to the print head can be made smaller than before, which allows the inkjet printing apparatus to be made more compact in size.
In addition, the amount of light reflected from outside the recording medium, such as from the table or the environment outside the device, can be reduced or prevented more than in the past, thereby preventing the photocurable ink from curing in the nozzles and their surroundings.

FIG. 1 is a schematic diagram illustrating an inkjet printing apparatus of the present invention. FIG. 2 is a plan view showing the arrangement of nozzles and light irradiation elements (UV-LEDs). FIG. 2 is a functional block diagram of the inkjet printing device. 4 is a cross-sectional view of the start and end of the table and the print head unit taken along a plane that is approximately perpendicular to the placement surface and parallel to the sub-scanning direction. FIG. FIG. 4 is an explanatory diagram illustrating a printing state at the beginning end of a recording medium. FIG. 4 is an explanatory diagram illustrating a printing state at the trailing edge of a recording medium. 3 is a flowchart showing the operation of the present invention. 1A and 1B are explanatory diagrams illustrating printing of unit areas located at the beginning and end of a recording medium. FIG. 11 is an explanatory diagram illustrating a case where printing is performed on a plurality of recording media arranged at a distance from one another. FIG. 2 is a schematic diagram illustrating another embodiment of the present invention.

1, an inkjet printing apparatus 1 of the present invention is connected, either wired or wirelessly, to a computer device 17 operated by a user, and the inkjet printing apparatus 1 executes printing based on image data, described below, sent from the computer device 17. The inkjet printing apparatus 1 comprises a table 5, a print head unit 7, and guide rails 10. A flat mounting surface 6 is formed on the table 5, and a recording medium is placed on this mounting surface 6. The guide rails 10 hold the print head unit 7 movably in a scanning direction (hereinafter referred to as the main scanning direction), which allows the print head unit 7 to move in the main scanning direction while maintaining a constant distance from the mounting surface 6.
The table 5 is held by a drive mechanism (not shown), which moves the table 5 in a sub-scanning direction perpendicular to the main scanning direction. The position of the table 5 is controlled by a table arrangement control unit (described later), and the arrangement of the table 5 is controlled in accordance with each printing pass in multi-pass printing.

A drive mechanism (not shown) can move the table 5 by a distance D between the position where the starting end 5a of the table 5 faces the print head unit 7 and the position where the ending end 5b of the table 5 faces the print head unit 7. As a result, the movement range L of the table 5 is narrower than in the past. Accordingly, it is necessary to change the printing mode at the beginning and end of multi-pass printing from the conventional one, which will be explained below.

The print head unit 7 is an integral unit consisting of a nozzle head 12 equipped with a plurality of nozzles and an ultraviolet irradiator 15 that irradiates light to cure the ultraviolet curable ink. With this configuration, the ultraviolet irradiator 15 can move in the main scanning direction together with the nozzle head 12, and can irradiate ultraviolet light onto the ultraviolet curable ink ejected onto the recording medium.
Although ultraviolet-curable ink is exemplified as the light-curable ink and the ultraviolet irradiator 15 is exemplified as the light irradiator, the present invention is not limited to this, and for example, ink that cures with a wavelength in the visible light region or a light irradiator that irradiates visible light may be used. The ink and the light irradiator may be changed as appropriate depending on the purpose.

2, the nozzle head 12 has a plurality of nozzles 21 to 26, which are arranged in a line. For example, the nozzle 21 has 16 nozzles 21a to 21d (two rows of eight nozzles), and ejects cyan ultraviolet-curable ink from the nozzle tips of the CMYK colors. The nozzles 21a to 21d are arranged in a row, and the arrangement direction of the nozzles coincides with the sub-scanning direction.
Nozzles 22-24 also have 16 nozzles each, and eject magenta, yellow, and black ultraviolet curable inks from their respective nozzle tips. Nozzles 25a-25d eject white ultraviolet curable ink, and nozzles 26a-26d eject transparent clear ultraviolet curable ink. The arrangement direction of the 16 nozzles in each of nozzles 22-24 also coincides with the sub-scanning direction.
With this nozzle layout, at the beginning of printing, nozzles 21a to 26a (starting nozzles) are closest to the starting end of table 5, and at the end of printing, nozzles 21d to 26d (terminal nozzles) are closest to the end of table 5. Note that, for ease of explanation, the number of nozzles is set to 16 here, but as will be described later, the number of nozzles is not limited to this.

An ultraviolet irradiator 15 is combined adjacent to the nozzle head 12, and the ultraviolet irradiator 15 has a plurality of ultraviolet irradiating light emitting diodes (hereinafter referred to as UV-LEDs) 30v to 30y. Each of the UV-LEDs 30v to 30y irradiates ultraviolet light with sufficient intensity to cure the ultraviolet curable ink. A reflector and a shutter mechanism 32 (not shown) are provided around each of the UV-LEDs 30v to 30y, and the shutter mechanism 32 can block the ultraviolet light emitted from each of the UV-LEDs 30v to 30y. This makes it possible to reliably cut off the ultraviolet light from the UV-LEDs 30v to 30y when ultraviolet light irradiation is not required.
The means for cutting ultraviolet rays is not limited to the above-mentioned shutter, and for example, each of the UV-LEDs 30v to 30y may be turned off. Whether to use the shutter mechanism 32 or to use the on/off control of the UV-LEDs 30v to 30y should be determined in consideration of the characteristics of each. For example, it is possible to employ the shutter mechanism 32 when it is necessary to quickly block ultraviolet rays, and to employ the on/off control of the UV-LEDs 30v to 30y when priority is given to reducing the weight of the print head unit 7.
Further, although the UV-LEDs 30v to 30y are exemplified here as the ultraviolet ray irradiation elements, high pressure mercury lamps, metal halide lamps, cold cathode fluorescent lamps, etc. may also be used.

The UV-LED 30v corresponds to 21a of the nozzles 21a to 21d that eject cyan, 22a of the nozzles 22a to 22d that eject magenta, 23a of the nozzles 23a to 23d that eject yellow, 24a of the nozzles 24a to 24d that eject black, 25a of the nozzles 25a to 25d that eject white, and 26a of the nozzles 26a to 26d that eject clear, and can irradiate ultraviolet light onto the ultraviolet-curable ink ejected from these nozzles 21a to 26a.

Similarly, the UV-LEDs 30w, 30x, and 30y can irradiate ultraviolet rays onto the ultraviolet-curable ink ejected from the nozzles 21b to 26b, 21c to 26c, and 21d to 26d, respectively. With this configuration, for example, a first printing pass can be assigned to the nozzles 21a to 26a and the UV-LED 30v, and a second printing pass following the first printing pass can be assigned to the nozzles 21b to 26b and the UV-LED 30w. Also, a third printing pass following the second printing pass, and a fourth printing pass following the third printing pass can be assigned to the nozzles 21c to 26c and the UV-LED 30x, and the nozzles 21d to 26d and the UV-LED 30y, respectively.
As described above, the print head unit 7 exemplified in this embodiment can execute four printing passes at once, but the number of nozzles and the number of UV-LEDs 30v to 30y can be changed as appropriate. For example, in order to quickly accommodate 8 passes or 16 passes with higher resolution, it is desirable to increase the number of nozzles and LEDs. Also, for example, if it is desired to control the ultraviolet irradiation more precisely, it is possible to increase the number of UV-LEDs 30v to 30y while keeping the number of nozzles the same. For example, while eight UV-LEDs 30v to 30y are provided in the above example, this number can be increased to 16 or even four to allow for more precise control.
In addition, the ink composition is exemplified here as six colors in total, CMYK, white, and a transparent clear color, but may be changed as appropriate.

As shown in FIG. 3, the inkjet printing device 1 includes a data receiving/transmitting unit 38, a multi-pass processing unit 40, a print control unit 50, a start print control unit (first print control means) 51, a center print control unit (second print control means) 52, an end print control unit (first print control means) 53, a head movement control unit 60, a table arrangement control unit (arrangement control means) 62, a nozzle control unit 64, an LED control unit 67, a user input unit (input means) 72, etc.

The data receiving/transmitting unit 38 receives rasterized binary image data and the like sent from the computer device 17 operated by the user, and transmits the received data to other units.
Although the processing performed by the computer device 17 will not be described in detail in this specification, for example, RGB image data created by the user is color-separated on the computer and converted into ink value data indicating the ink values of each color of CMYK. The ink value data is appropriately gamma-corrected and further half-tone-processed using a dither matrix or the like to generate binary image data.

The multi-pass processing unit 40 has a mask selection unit 45, a pass setting unit 46, and a mask storage unit 47, and generates binary print data for each pass.
The mask selection unit 45 selects a pass mask to be applied based on the binary image data from the computer device 17. The mask storage unit 47 stores a plurality of mask patterns with different contents, and the mask selection unit 45 selects and reads out an appropriate one of the plurality of mask patterns stored in the mask storage unit 47.
The pass setting unit 46 generates binary print data, which is raster data for each pass in each unit area, using the mask pattern read out by the mask selection unit 45. Note that here, four passes are shown as an example in which an image in a unit area is completed by four printing passes (hereinafter, referred to as four passes).

The start printing control unit 51, center printing control unit 52, and end printing control unit 53 control the head movement control unit 60, table placement control unit 62, nozzle control unit 64, and LED control unit 67 based on the binary printing data for each pass (hereinafter referred to as pass printing data), and form and fix an image on the recording medium.

The head movement control unit 60 controls the movement of the print head unit 7 in the main scanning direction based on commands from the start-end printing control unit 51 , the center printing control unit 52 , and the end-end printing control unit 53 .
The table positioning control unit 62 moves the table 5 in the sub-scanning direction or holds it so that it does not move, based on commands from the leading edge printing control unit 51, the central area printing control unit 52, and the trailing edge printing control unit 53.
The nozzle control unit 64 controls the driving of the nozzles 21 to 26 based on commands from the start-end printing control unit 51 , the center-end printing control unit 52 , and the end-end printing control unit 53 .
The LED control unit 67 controls the turning on/off of the LEDs 30 v to 30 y and the operation of the shutter mechanism 32 based on commands from the leading edge printing control unit 51 , the central area printing control unit 52 , and the trailing edge printing control unit 53 .

The start edge print control unit 51 controls the drive of each nozzle 21-26 via the nozzle control unit 64 based on the pass print data from the first scan to the fourth scan, and further controls the lighting of LEDs 30v-30y via the LED control unit 67 to fix the image at the start edge of the recording medium M. Details will be described later, but at this time the table placement control unit 62 holds the table 5 so that it does not move.

In the case of four passes, the center printing control unit 52 controls the head movement control unit 60, table placement control unit 62, nozzle control unit 64, and LED control unit 67 based on the pass printing data from the fifth scan to the fourth scan before the final scan, to form and fix an image in the center excluding the beginning and end of the recording medium M.
From the fifth scan onwards, the centre printing control unit 52 moves the table 5 one scan via the table positioning control unit 62 each time the print head unit 7 moves back and forth for a printing operation, and when moving from four scans before the last scan to three scans before, the movement of the table 5 is completed by moving the table 5 one scan in the sub-scanning direction.

The end print control unit 53 controls the drive of the nozzles 21-26 via the nozzle control unit 64 based on the binary print data from the last scan to the third scan before, and controls the lighting of the LEDs 30v-30y via the LED control unit 67 to fix the image at the end of the recording medium M. Details of this will be described later, but at this time the table placement control unit 62 holds the table 5 so that it does not move.

The user input unit 72 includes a pointer, keyboard, etc. (not shown) that is operated by the user, and allows the user to input start-end position information of the recording medium M on the table 5. The start-end position information input by the user is transmitted to the table placement control unit 62, which then moves the table 5 in the sub-scanning direction based on this start-end position information, and aligns the table 5 so that the nozzle head 12 faces the start end of the recording medium M.

4A, when an image for four passes is formed and fixed in unit area M1 located at the beginning of recording medium M, table 5 is held and does not move, so that each of nozzles 21 to 26 ejects ink onto the same unit area based on pass print data, and UV-LEDs 30v to 30y also irradiate ultraviolet rays onto the same unit areas M1 to M4, respectively. The image forming/fixing process for unit areas M1 to M4, for example which nozzle corresponds to which unit area, will be described later with reference to FIG.
When positioning the table 5 using a pointer or the like, it is advisable to position the recording medium M so that a margin is formed so that the UV-LED 30v can reliably harden the ink ejected at the beginning of the recording medium M.

As shown in FIG. 4(b), when an image for four passes is fixed to unit area M24 located at the end of recording medium M, table 5 is held and does not move, so that each of nozzles 21 to 26 ejects ink to the same unit area M21 to 24 based on the pass print data, and UV-LEDs 30v to 30y also irradiate ultraviolet light to the same unit area. The image formation/fixing process for unit areas M21 to M24 will be described later using FIG. 6.

As shown in FIG. 5(a), in the first scan (first scan), ink is ejected from the nozzles 21a-26a closest to the beginning of the table 5 onto a unit area M1 set on the recording medium M to form an image. The ultraviolet-curable ink that has landed on the unit area M1 is cured by the UV-LED 30v and fixed onto the unit area M1.

As shown in FIG. 5(b), when moving from the first scan to the second scan, the table 5 is held, and ink is ejected from the nozzles 21a to 26a onto the unit area M1 based on the second pass print data. At the same time, ink is ejected from the nozzles 21b to 26b onto the unit area M2 adjacent to the unit area M1 based on the first pass print data, forming an image. The ultraviolet-curable ink ejected onto the unit area M2 is cured by the ultraviolet light from the UV-LED 30w, and the image is fixed.

As shown in FIG. 5(c), the table 5 is held when moving from the second scan to the third scan, and ultraviolet curable ink is ejected from nozzles 21a to 26a into unit area M1 based on the third pass pass print data and fixed. At the same time, ink is ejected from nozzles 21b to 26b into unit area M2 based on the second pass pass print data and an image is formed and fixed. At the same time, ultraviolet curable ink is ejected from nozzles 21c to 26c into unit area M3 adjacent to unit area M2 based on the first pass pass print data and an image is formed. The ultraviolet curable ink ejected into unit area M3 is cured by ultraviolet light from UV-LED 30x and the image is fixed.

5D, when moving from the third scan to the fourth scan, the table 5 is held, and ultraviolet curable ink is ejected from the nozzles 21a to 26a to the unit area M1 based on the pass print data for the fourth pass and fixed in place. This completes all printing passes for the unit area M1, completing the image.
At the same time, ink is ejected from nozzles 21b to 26b into unit region M2 based on the third pass pass print data, and an image is formed and fixed. At the same time, ultraviolet curable ink is ejected from nozzles 21c to 26c into unit region M3 based on the second pass pass print data, and an image is formed and fixed. At the same time, ultraviolet curable ink is ejected from nozzles 21d to 26d into unit region M4 adjacent to unit region M3 based on the first pass pass print data, and an image is formed. The ultraviolet curable ink ejected into unit region M4 is cured by ultraviolet light from UV-LED 30y, and the image is fixed.

As shown in FIG. 5(e), when moving from the fourth scan to the fifth scan, the table 5 moves one scan toward the starting end in the sub-scanning direction. For each subsequent scan, the table 5 moves toward the starting end, and ultraviolet-curable ink is ejected from each of the nozzles 21-26 onto the recording medium M according to the pass print data, and is fixed by the UV-LEDs 30v-30y.

6A, four scans before the final scan, an image is formed by ejecting ultraviolet curable ink from nozzles 21b to 26b toward unit area M21 on recording medium M based on the pass print data for the third pass. The ultraviolet curable ink that has landed on unit area M21 is cured by UV-LED 30v and fixed on unit area M21.
At the same time, ultraviolet curable ink is ejected from nozzles 21c to 26c toward unit area M22 based on the pass printing data of the second pass, and ultraviolet curable ink is ejected from nozzles 21d to 26d toward unit area M23 based on the pass printing data of the first pass, thereby forming and fixing an image.

6B, when moving from 4 scans before the final scan to 3 scans before the final scan, the table 5 moves one scan toward the starting end. After this, the table 5 is held and does not move toward the starting end.
UV-curable ink is ejected from the nozzles 21a to 26a to unit area M21 based on the fourth pass print data and fixed. At the same time, ink is ejected from the nozzles 21b to 26b to unit area M22 based on the third pass print data and the image is fixed.
At the same time, ultraviolet curable ink is ejected from nozzles 21c to 26c toward unit area M23 based on the pass printing data of the second pass, and ultraviolet curable ink is ejected and fixed from nozzles 21d to 26d toward unit area M24 based on the pass printing data of the first pass out of four passes.

As shown in FIG. 6C, when moving from 3 scans before the final scan to 2 scans before the final scan, the table 5 is held.
Ink is ejected from the nozzles 21b to 26b onto the unit region M22 based on the print data for the fourth pass, and the image is fixed.
At the same time, ultraviolet curable ink is ejected from nozzles 21c to 26c toward unit area M23 based on the third pass print data, and ultraviolet curable ink is ejected from nozzles 21d to 26d toward unit area M24 based on the second pass print data, and fixed.
The nozzles 21a to 26a facing the unit region M21 stop ejecting ink, and the UV-LED 30v is turned off or blocked by a shutter (not shown).

As shown in FIG. 6D, the table 5 is also held when moving from two scans before the final scan to one scan before the final scan.
UV-curable ink is ejected from nozzles 21c to 26c toward unit region M23 based on the fourth pass print data, and UV-curable ink is ejected and fixed from nozzles 21d to 26d toward unit region M24 based on the third pass print data.
The nozzles 21a to 26a and the nozzles 21b to 26b facing the unit regions M21 and M22 stop being driven, and the UV-LEDs 30v and 30w are turned off or blocked by a shutter (not shown).

6(e), the table 5 is held from the scan before the final scan until the final scan. All printing is completed by ejecting and fixing ultraviolet curable ink from the nozzles 21d to 26d toward the unit area M24 based on the pass print data for the fourth pass.
The nozzles 21a to 26a, nozzles 21b to 26b, and nozzles 21c to 26c facing the unit regions M21, M22, and M23 stop being driven, and the UV-LEDs 30v, 30w, and 30x are turned off or blocked by shutters (not shown).

The operation of the present invention will be described with reference to Fig. 7. RGB image data is generated by the computer device 17 operated by the user (S201), and this RGB image data is converted into binary image data through halftone processing in S203 by a print processing program or the like installed in the computer device 17 (S205). The generated binary image data is sent to the inkjet printing device 1 (S207).
The inkjet printing device 1 receives binary image data via the data receiving/transmitting unit 38 (S301), and generates pass print data for each unit area corresponding to four passes by, for example, selecting a mask pattern in the multi-pass processing unit 40 based on the received binary image data (S303, S305, S307). The generated pass print data is sent to the start portion print control unit 51, the center portion print control unit 52, and the end portion print control unit 53.

The starting end print control unit 51 that receives the pass print data controls the head movement control unit 60, the nozzle control unit 64, and the LED control unit 67 to start forming and fixing an image on the starting end of the recording medium M (S310).
[Print start end]
As shown in FIG. 8, in the first scan, ink is ejected from the nozzles 21a to 26a onto a unit area M1 located at the starting end based on the pass printing data of the first pass, and the ultraviolet-curable ink that has landed on the unit area M1 is cured by the UV-LED 30v and fixed onto the unit area M1 (S312).
When moving to the second scan, the table 5 is held, and ink is ejected from the nozzles 21a to 26a onto the unit area M1 based on the pass print data of the second pass, and ink is ejected from the nozzles 21b to 26b onto the unit area M2 based on the pass print data of the first pass, forming an image. The unit area M2 is irradiated with ultraviolet light from the UV-LED 30w, and the image is fixed.

When moving to the third scan, the table 5 is held and ultraviolet curable ink is ejected from nozzles 21a to 26a onto unit area M1 based on the third pass print data, ink is ejected from nozzles 21b to 26b onto unit area M2 based on the second pass print data, and ultraviolet curable ink is ejected from nozzles 21c to 26c onto unit area M3 based on the first pass print data, forming an image. Ultraviolet light is irradiated onto unit area M3 from UV-LED 30x, and the image is fixed.

When moving to the fourth scan, the table 5 is also held, and ultraviolet curable ink is ejected from the nozzles 21a to 26a onto the unit area M1 based on the pass print data of the fourth pass, and ink is ejected from the nozzles 21b to 26b onto the unit area M2 based on the pass print data of the third pass, forming and fixing the image. In this way, the image of the unit area M1 located at the starting end is completed.
Further, ultraviolet curable ink is ejected from nozzles 21c to 26c into unit region M3 based on the second pass print data, and ultraviolet curable ink is ejected from nozzles 21d to 26d into unit region M4 based on the first pass print data, forming an image. Unit region M4 is irradiated with ultraviolet light from UV-LED 30y to fix the image (S315). Next, printing proceeds to unit region M2 adjacent to unit region M1 located at the starting end and its central portion inside (S320).

[Print center part]
When moving from the fourth scan to the fifth scan, the table 5 moves one scan toward the starting end in the sub-scanning direction (S322). After the fifth scan, the table 5 moves one scan toward the starting end after each scan, and ultraviolet-curable ink is ejected from each of the nozzles 21-26 to the corresponding unit area according to the pass print data for each scan, and the image is fixed by the UV-LEDs 30v-30y (S324).

[Print Ends]
When moving from 4 scans before the final scan to 3 scans before the final scan (S326), the table 5 moves one scan toward the starting end. After this, the table 5 is held and does not move toward the starting end (S328).
Three scans before the final scan, ultraviolet curable ink is ejected from nozzles 21a to 26a onto unit area M21 based on the fourth pass print data, and ink is ejected from nozzles 21b to 26b onto unit area M22 based on the third pass print data, and the image is fixed.
Furthermore, ultraviolet curable ink is ejected from nozzles 21c to 26c toward unit area M23 based on the pass printing data of the second pass, and an image in which ultraviolet curable ink is ejected from nozzles 21d to 26d toward unit area M24 located at the terminal end based on the pass printing data of the first pass out of four passes is fixed (S330, S334).

Two scans before the final scan, ink is ejected from nozzles 21b to 26b into unit area M22 based on the fourth pass print data, ultraviolet curable ink is ejected from nozzles 21c to 26c toward unit area M23 based on the third pass print data, and ultraviolet curable ink is ejected from nozzles 21d to 26d toward unit area M24 based on the second pass print data, fixing the image. Nozzles 21a to 26a facing unit area M21 stop driving, and UV-LED 30v is turned off or blocked by shutter mechanism 32.

One scan before the final scan, ultraviolet curable ink is ejected from nozzles 21c to 26c toward unit area M23 based on the pass print data of the fourth pass, and ultraviolet curable ink is ejected from nozzles 21d to 26d toward unit area M24 based on the pass print data of the third pass, fixing the image. Nozzles 21a to 26a and nozzles 21b to 26b facing unit areas M21 and M22 stop driving, and UV-LED 30w as well as 30v are turned off or blocked by shutter mechanism 32.

In the final scan, ultraviolet curable ink is ejected and fixed from the nozzles 21d to 26d toward the unit region M24 based on the pass print data for the fourth pass, and all printing is completed (S3337).
At this time, the nozzles 21a to 26a, nozzles 21b to 26b, and nozzles 21c to 26c facing the unit regions M21, M22, and M23 are not driven, and the UV-LEDs 30v, 30w, and 30x are turned off or blocked by the shutter mechanism 32.

As described above, the inkjet printing device 1 of the present invention is equipped with a print head unit 7 having a plurality of nozzles 21-26 that eject UV-curable ink and ejecting UV-curable ink from the nozzles while moving in the main scanning direction, a table 5 on which a recording medium M is placed and which is arranged to be movable relative to the print head unit 7 in the sub-scanning direction (the direction in which the nozzles are arranged), and UV-LEDs 30 integrated into the print head unit 7, and sets unit areas on the recording medium M for forming an image by multiple printing passes, and fixes the image by irradiating UV rays onto the UV-curable ink ejected onto the recording medium M based on the pass printing data for each unit area.
Furthermore, the inkjet printing apparatus 1 of the present invention includes a table arrangement control unit 62 that controls the arrangement of the print head unit 7 relative to the table 5 in the sub-scanning direction between a position in the sub-scanning direction where the start nozzles 21a to 26a face a unit area M1 located at the start end of the recording medium M, and a position where the end nozzles 21d to 26d face a unit area M24 located at the end end of the recording medium M;
a start-end print control unit 51 that performs all printing passes set for the unit area M1 using the start-end nozzles 21 a to 26 a to form an image while fixing the position of the table 5 relative to the print head unit 7 by a table arrangement control unit 62;
a central print control unit 52 that performs printing passes from a unit area M2 adjacent to the unit area M1 to a unit area M23 adjacent to the unit area M24 while moving the table 5 relatively to the nozzles 21 to 26 in the sub-scanning direction from the start end side to the end end side for each scan, thereby forming an image;
and a terminal print control unit 53 that performs all printing passes set for the unit area M24 using the terminal nozzles 21d to 26d to form an image while fixing the position of the table 5 relative to the print head unit 7.
As a result, the start end printing control unit 51 causes the start end nozzles 21a-26a to execute all printing passes set for the unit region M1, and the end end printing control unit 53 causes the end end nozzles 21d-26d and the UV-LED 30y to execute all printing passes set for the unit region M24 located at the end, so that the movement range L of the table 5 relative to the print head unit 7 can be narrower than in the past. Also, the amount of ultraviolet light incident from outside the inkjet printing device 1 can be reduced more than in the past.
This makes it possible to suppress the amount of unnecessary ultraviolet light incident on the nozzles 21 to 26, thereby reducing the occurrence of defective ejection of ultraviolet-curable ink from the nozzles 21 to 26. Furthermore, by making the movement range L of the table 5 narrower than in the past, the size of the inkjet printing device 1 can be made more compact, and user convenience can also be improved.

In the above embodiment, the table 5 moves in the sub-scanning direction relative to the print head unit 7, but the print head unit 7 may also move in the sub-scanning direction relative to the table 5.
In this configuration, as in the above embodiment, all printing passes set for a unit area located at the starting end can be executed by the nozzles at the starting end of the nozzle head 12, and all printing passes set for a unit area located at the end can be executed by the nozzles at the terminal end of the nozzle head 12.

In addition, in the above example, a recording medium M is shown in which both ends are formed in a line shape without any unevenness, but the present invention can also be implemented even if the recording medium M has non-recording areas, such as when the ends of the recording medium M have an uneven shape or when multiple recording media M are placed intermittently on the table 5.
As shown in Figures 9(a) to (d), for example, in the case where multiple recording media ML, MR are intermittently placed on the table 5, by at least one of controlling the UV-LEDs on/off in accordance with the arrangement of the recording media ML, MR and blocking the ultraviolet light from the UV-LEDs with a shutter, it is possible to avoid irradiation of the table 5 or the external environment with ultraviolet light and to prevent unnecessary light from entering the nozzle.
In the case where multiple recording media M are arranged on the table 5 at a distance from one another in this manner, even if there is a defect in the recording medium M placed on the table 5, an image can be formed in each unit area ML1 to ML4, MR1 to MR4, for example, in four passes without moving the print head unit 7, and then fixed with ultraviolet light.
It is necessary to ensure a certain degree of irradiation margin when turning the UV-LED on and off or opening and closing the shutter, but it is preferable to make each margin as small as possible within the range where an irradiation intensity sufficient to reliably solidify the ink can be obtained, in order to reduce unnecessary reflection of ultraviolet light.

In the above embodiment, the print head unit 7 is prevented from moving in the sub-scanning direction relative to the table 5 when images are formed and fixed in both unit area M1 located at the starting end of the recording medium M and unit area M24 located at the end using four scans, but it is also possible to prevent the print head unit 7 from moving in the sub-scanning direction relative to the table 5 when an image is formed and fixed in either unit area M1 on the starting end side or unit area M24 on the end side.
Compared to the case where the print head unit 7 is prevented from moving in the sub-scanning direction relative to the table 5 when forming and fixing an image in both unit area M1 and unit area M24, the case where the print head unit 7 is prevented from moving in the sub-scanning direction relative to the table 5 when forming and fixing an image in either unit area M1 or unit area M24 increases the movement range L of the table 5 and therefore the size of the entire apparatus increases, but it makes it possible to further simplify the drive control of each nozzle and the movement control of the table 5. This will be described in detail next.

In the above embodiment, the relative movement range L of the table 5 with respect to the print head unit 7 was from the position where the unit area located at the starting end faces the starting nozzle to the position where the unit area located at the end faces the terminal nozzle 21d, but the present invention is not limited to this form, and either one may be in a printing form similar to conventional multi-pass printing.
10A, for example, printing is started by positioning the print head unit 107 so that all printing passes set for the unit area located at the start end of the recording medium M can be executed by the start nozzle. For unit areas from the unit area adjacent to the unit area located at the start end to the unit area located at the end, in other words, unit areas other than the unit area located at the start end, printing is carried out by moving the table 105 in the sub-scanning direction relative to the print head unit 107 for each printing pass, as in conventional multi-pass printing. For this reason, the last printing pass of the unit area located at the end is performed by the start nozzle, and when the recording medium M is placed to the maximum on the table 105, part of the print head unit 107 may extend beyond the end of the table 105, but the print head unit 107 does not extend beyond the table 105 at the beginning of printing.
In this way, by setting the relative movement range L of the table 105 to the range L2 between the position where the unit area located at the start end of the recording medium M faces the start end nozzle and the position where the unit area located at the end end of the recording medium M faces the start end nozzle, it is possible to make the movement range L of the table 105 smaller than in the past. In addition, it is also possible to reduce the incidence of unnecessary ultraviolet light on the nozzle when printing the unit area located at the start end.
In FIG. 10B, in contrast to the example in FIG. 10A, the print head unit 107 is positioned so that all printing passes set in the unit area located at the end of the recording medium M can be executed by the starting nozzle, and printing is completed. For unit areas adjacent to the unit area located at the end, in other words, unit areas other than the unit area located at the end, printing is performed by moving the table 105 in the sub-scanning direction relative to the print head unit 107 for each printing pass, as in conventional multi-pass printing. For this reason, the first printing pass of the unit area located at the start end is performed by the end nozzle, and when the recording medium M is placed to the maximum on the table 105, a part of the print head unit 107 may extend beyond the start end of the table 105, but the print head unit 107 will not extend beyond the table 105 when printing is completed. This embodiment also makes it possible to reduce the movement range L of the table compared to the conventional embodiment. In addition, it is also possible to reduce the incidence of unnecessary ultraviolet light on the nozzle when printing the unit area located at the end.

In the embodiment described with reference to FIG. 10, the table 5 moves in the sub-scanning direction relative to the print head unit 7, but the print head unit 7 may also move in the sub-scanning direction relative to the table 5.

In the above embodiment, an inkjet printer is provided with a light irradiator and uses ultraviolet light from the light irradiator to cure ultraviolet-curable ink. However, the present invention is not limited to this and can also be applied to an inkjet printing device that forms an image by ejecting ink that is not photocurable onto a recording medium. In this case, the relative movement range of the table with respect to the print head unit can be made smaller than in the past, which has the advantage of providing a more compact inkjet printing device.

REFERENCE SIGNS LIST 1 Inkjet printing device 5 Table 6 Mounting surface 7 Print head unit 10 Guide rail 12 Nozzle head 15 Ultraviolet irradiator (light irradiator)
17 Computer device 21 to 26 Nozzles 21a to 26a Starting nozzles 21d to 26d End nozzles 30 Ultraviolet light emitting diode (light emitting element)
32 Shutter mechanism 40 Multi-pass processing unit 51 Starting end printing control unit (first printing control means)
52 central printing control unit (second printing control means)
53 End Printing Control Unit (First Printing Control Means)
60 Head movement control unit 62 Table arrangement control unit (arrangement control means)
64 Nozzle control unit 67 LED control unit 72 User input unit (input means)
M Recording medium

Claims (6)

a print head having a plurality of nozzles for ejecting ink, the print head ejecting ink from the nozzles while moving in a main scanning direction that is substantially perpendicular to the arrangement direction of the nozzles;
a table on which a recording medium is placed and which is provided so as to be movable relative to the print head in a sub-scanning direction which is the arrangement direction; and an inkjet recording device which sets unit areas for forming an image on the recording medium by a plurality of printing passes and ejects ink onto the recording medium based on raster data for each unit area,
a placement control means for controlling the placement of the print head with respect to the table in the sub-scanning direction between a position where a start end nozzle located at a start end in the arrangement direction faces a unit area located at the start end of the recording medium, and a position where a end end nozzle located at an end end faces a unit area located at the end of the recording medium;
a first print control means for fixing the relative positions of the print head and the table in the sub -scanning direction by the arrangement control means, executing all printing passes set for a unit area located at a start end by the start end nozzle, and executing all printing passes set for a unit area located at an end end by the end end nozzle, thereby forming an image in each unit area;
a second print control means for performing a plurality of print passes from a unit area adjacent to a unit area located at a starting end to a unit area adjacent to a unit area located at a terminal end, while relatively moving the table in the sub-scanning direction by the arrangement control means, to form an image;
Equipped with
the image is formed by overlapping the plurality of printing passes in the same unit area a predetermined number of times, that is, N times,
the print head is divided into N unit nozzle arrays corresponding to the N times in the sub-scanning direction,
the first print control means performs superposition of the N printing passes in the unit area at a start end of the image in the sub-scanning direction, while fixing the relative positions of the print head and the table in the sub-scanning direction, using only a unit nozzle array on the start end side;
an ink jet recording apparatus , wherein after the overlapping of the N printing passes by the unit nozzle array on the starting end side is completed, control is shifted to that of the second print control means. a print head having a plurality of nozzles for ejecting ink, the print head ejecting ink from the nozzles while moving in a main scanning direction that is substantially perpendicular to the arrangement direction of the nozzles;
a table on which a recording medium is placed and which is provided so as to be movable relative to the print head in a sub - scanning direction which is the arrangement direction; and an inkjet recording device which sets unit areas on the recording medium for forming an image on the recording medium by a plurality of printing passes, and ejects ink onto the recording medium based on raster data for each unit area,
a placement control means for controlling a placement of the print head with respect to the table in the sub-scanning direction between a position where an end nozzle located at one end in a nozzle arrangement direction faces a unit area located at one end of a recording medium, and a position where the end nozzle faces a unit area located at the other end of the recording medium;
a first print control means for fixing the relative positions of the print head and the table in the sub -scanning direction by the arrangement control means and for causing the end nozzles to execute all printing passes set for a unit area located at one end to form an image;
a second print control means for forming an image by executing a plurality of print passes on each unit area excluding a unit area in which an image is formed by the first print control means while relatively moving the table in the sub -scanning direction by the arrangement control means;
Equipped with
the image is formed by overlapping the plurality of printing passes in the same unit area a predetermined number of times, that is, N times,
the print head is divided into N unit nozzle arrays corresponding to the N times in the sub-scanning direction,
the first print control means performs superposition of the N printing passes in the unit area at a terminal end of the image in the sub-scanning direction, while fixing the relative positions of the print head and the table in the sub-scanning direction, using only the unit nozzle array at the terminal end;
In a printing pass before starting the printing pass on the terminal side, control is performed by the second print control means . the ink is a photocurable ink,
3. The inkjet recording apparatus according to claim 1, further comprising a light irradiator that is integrally incorporated in the print head and that irradiates light rays to the light-curable ink ejected onto the recording medium in order to cure the light-curable ink. an input unit for inputting information on an end position of the recording medium placed on the table;
4. The ink jet recording apparatus according to claim 3, wherein said position control means moves said table relatively to said print head in advance before starting printing based on position information from said input means to perform cueing. The inkjet storage device according to claim 3, wherein the first print control means, when there is a non-recording area in a printing pass where photocurable ink is not ejected, blocks or turns off the light irradiation from the light irradiator corresponding to the non-recording area. The light irradiator includes a plurality of light irradiating elements arranged in accordance with a plurality of nozzles,
6. The ink jet recording apparatus according to claim 5, wherein the first print control means blocks or turns off the irradiation of each of the light emitting elements corresponding to the non-recording area.

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