JP2011110922A - Printing system, printing control program, and printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deterioration in an image quality by determining the irradiation condition of each temporary curing part on the basis of each color ink ejection amount per unit area obtained on the basis of printing data passed through halftone processing for every different color. <P>SOLUTION: The printing system includes heads 31 each for ejecting an electromagnetic wave curable ink in one color of different colors towards a medium S, the temporary curing parts 41 respectively corresponding to the heads 31 for temporarily curing the electromagnetic wave curable inks by illuminating the electromagnetic wave curable inks ejected from the heads 31 and hit on the medium S with electromagnetic waves, and a controller which determines the irradiation condition of each temporary curing part 41 on the basis of each color ink ejection amount per unit area obtained on the basis of the printing data passed through halftone processing for every different color. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a printing system, a printing control program, and a printing method.

  Conventionally, based on print data that has been halftoned, a head that discharges a plurality of colors of electromagnetic curable ink toward the medium and an electromagnetic curable ink of each color that has landed on the medium are irradiated with electromagnetic waves, respectively. 2. Description of the Related Art A printing technique having a plurality of temporary curing portions that temporarily cure electromagnetic wave curable inks is known.

JP 2008-265285 A

However, the conventional technique has a problem that the image quality is lowered depending on the amount of the electromagnetic wave curable ink ejected to the medium because the irradiation amount of the electromagnetic wave is constant.
The present invention has been made in view of such a conventional problem, and an object thereof is to suppress deterioration in image quality.

The main invention for solving the above-mentioned problems is:
Each head that discharges a different color of electromagnetic curable ink toward the medium one by one,
Each electromagnetically curable ink ejected from each head and landed on the medium is irradiated with electromagnetic waves to temporarily cure the electromagnetic wave curable ink, and each temporary curing portion corresponding to each head;
A controller that determines the irradiation condition of each temporary curing portion based on the ink discharge amount of each color per unit area obtained based on the print data that has been halftone processed for each of the different colors. Is a printing system.

  Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

FIG. 2 is a block diagram illustrating a configuration of a printer 2 according to the first embodiment. 2A is a schematic top view of the printer 2, and FIG. 2B is a schematic side view of the printer 2. FIG. 4 is a schematic view showing a nozzle surface of a head 31 and irradiation surfaces of a temporary curing part 41 and a main curing part 43. FIG. 3 is a block configuration diagram illustrating functions of a computer 3 that is communicably connected to a printer 2. It is a figure which shows the program memorize | stored in the computer. FIG. 6 is a flowchart illustrating a printing process when printing is performed by the printing system 1. It is a figure which shows notionally each cell divided into the grid | lattice form corresponding to the temporary hardening part 41 (C) about the printing surface on the paper S. FIG. It is a graph which shows the relationship between the ink discharge amount per unit area, and the irradiation intensity | strength of an ultraviolet-ray. It is a table | surface which shows the relationship between the irradiation energy amount of the temporary hardening part 41, surface tackiness, and a bleed. It is a flowchart which shows the printing process in the case of printing by the printing system 1 in 2nd Embodiment. It is a conceptual diagram which shows the relationship between raster line ag and image area | region R1-R3 comprised by the several raster line adjacent to each other.

  At least the following will become apparent from the description of the present specification and the accompanying drawings.

That is, each head that discharges an electromagnetic curable ink of a different color toward the medium one by one,
Each electromagnetically curable ink ejected from each head and landed on the medium is irradiated with electromagnetic waves to temporarily cure the electromagnetic wave curable ink, and each temporary curing portion corresponding to each head;
A controller that determines the irradiation condition of each temporary curing portion based on the ink discharge amount of each color per unit area obtained based on the print data that has been halftone processed for each of the different colors. Is a printing system.
According to such a printing system, it is possible to suppress deterioration in image quality.

Such a printing system,
A transport unit that transports the medium in the transport direction;
Each of the temporary curing portions is based on an irradiation condition that is switched according to a printing region in which a printing surface on which an image is formed by landing of the electromagnetic wave curable ink on the medium is divided into a plurality in the transport direction. Irradiate
The controller is configured to determine the irradiation condition of the temporary curing portion in each print region based on the ink discharge amount of each color per unit area in each print region.
According to such a printing system, it is possible to determine an appropriate irradiation condition in each printing region, and it is possible to further suppress deterioration in image quality.

Such a printing system,
Each pre-curing part has a plurality of irradiation parts that are arranged in parallel in the width direction intersecting with the transport direction, irradiate irradiation regions corresponding to each, and can be independently controlled,
The controller is configured to determine irradiation conditions of the irradiation units in the irradiation regions based on ink discharge amounts of the respective colors per unit area in the irradiation regions.
According to such a printing system, it is possible to determine an appropriate irradiation condition in each irradiation region, and to further suppress deterioration in image quality.

Such a printing system,
A transport unit that transports the medium in the transport direction;
Each of the temporary curing portions is an image area configured by having a plurality of rasters generated on the medium by the heads ejecting the electromagnetic wave curable ink once toward the medium, Each of the image areas sequentially identified by replacing the raster adjacent to the upstream side in the transport direction with respect to the image area with the raster located in the most downstream of the transport direction among the rasters constituting the image area. Irradiate based on the irradiation conditions sequentially switched according to
The controller determines the irradiation condition of the temporary curing portion in each of the image regions based on each color ink discharge amount per unit area in each of the image regions that are sequentially specified. It is.
According to such a printing system, the change of the irradiation condition can be moderated and the deterioration of the image quality can be suppressed.

Such a printing system,
The length of the printing region in the transport direction is longer than a length obtained by a product of a speed at which the transport unit transports the medium and a time required for the temporary curing unit to switch the irradiation condition. Printing system.
According to such a printing system, the temporary curing process can be accurately executed based on a predetermined irradiation condition, and further the deterioration of the image quality can be suppressed.

Such a printing system,
A computer and a printing device capable of communicating with the computer;
The computer
The controller;
An interface that transmits halftone processing data for each of the different colors and the irradiation condition to the printing apparatus;
The printing apparatus includes:
Each of the heads;
Each of the temporary curing portions,
A printing system comprising: print data subjected to halftone processing for each different color; and an interface for receiving the irradiation condition from the computer.
According to such a printing system, it is possible to suppress deterioration in image quality.

In addition, each head that discharges the electromagnetic curable inks of different colors toward the medium one by one,
Each electromagnetically curable ink ejected from each head and landed on the medium is irradiated with electromagnetic waves to temporarily cure the electromagnetic wave curable ink, and each temporary curing portion corresponding to each head;
A print control program for causing a computer to realize a function of controlling a printing apparatus comprising:
On the computer,
A function of generating halftone processed print data for each of the different colors;
A function for determining each color ink discharge amount per unit area based on the halftone processed print data;
A function for determining the irradiation condition of each temporary curing portion based on the discharge amount of each color ink per unit area;
Is a print control program characterized by realizing the above.
According to such a print control program, it is possible to suppress deterioration in image quality.

Generating halftone processed print data for each different color;
Obtaining each color ink discharge amount per unit area based on the halftone processed print data;
Irradiating electromagnetic waves on the basis of the discharge amount of each color ink per unit area, respectively determining the irradiation conditions of each temporarily cured portion for temporarily curing the electromagnetic wave curable ink;
Discharging the different color electromagnetic curable ink from the head toward the medium one by one,
The electromagnetic wave curable ink ejected from the heads and landed on the medium is irradiated with electromagnetic waves from the temporary curing units corresponding to the heads under the irradiation conditions to temporarily cure the electromagnetic wave curable ink. And
It is a printing method characterized by having.
According to such a printing method, it is possible to suppress deterioration in image quality.

=== First Embodiment ===
<About printer configuration>
Hereinafter, the printing system 1 of the present embodiment will be described with reference to FIGS. 1, 2A, 2B, and 3. FIG. The printing system 1 includes a printer 2 (corresponding to a “printing apparatus”) and a computer 3.

  FIG. 1 is a block diagram of the overall configuration of the printer 2 of the present embodiment. 2A is a schematic top view of the printer 2, and FIG. 2B is a schematic side view of the printer 2. FIG. 3 is a schematic view showing the nozzle surface of the head 31 and the irradiation surfaces of the temporary curing portion 41 and the main curing portion 43.

  The printer 2 receives a print command (print data) from the computer 3, which is an external device, and controls each unit (conveyance unit 20, head unit 30, ultraviolet irradiation unit 40) by the control unit 60, and images on the paper S. Form. Further, the detector group 50 monitors the situation in the printer 2, and the control unit 60 controls each unit based on the detection result.

  The control unit 60 is a control unit for controlling the printer 2. The interface unit 61 is for transmitting and receiving data between the computer 3 and the printer 2 which are external devices. The CPU 62 is an arithmetic processing unit for controlling the entire printer 2. The memory 63 is for securing an area for storing a program of the CPU 62, a work area, and the like. The CPU 62 controls each unit by a unit control circuit 64 according to a program stored in the memory 63.

  The transport unit 20 (corresponding to a “transport unit”) is for transporting a sheet S as an example of a medium in the transport direction. As illustrated in FIG. 2, the transport unit 20 includes an upstream transport roller 23 </ b> A and a downstream transport roller 23 </ b> B, and a belt 24. When a transport motor (not shown) rotates, the upstream transport roller 23A and the downstream transport roller 23B rotate, and the belt 24 rotates. The paper S fed by a paper feed roller (not shown) is conveyed by the belt 24 to a printable area (area facing the head). When the belt 24 transports the paper S, the paper S moves in the transport direction with respect to the head unit 30. The paper S that has passed through the printable area is discharged to the outside by the belt 24. The sheet S being conveyed is electrostatically attracted or vacuum attracted to the belt 24.

  The head unit 30 has a head 31 for ejecting ink onto the paper S. In the printer 2 shown in FIG. 2, a plurality of heads 31 that eject different inks toward the paper S are provided. A plurality of nozzles that are ink discharge portions are provided on the lower surface of each head 31. Each nozzle is provided with a pressure chamber (not shown) containing ink, and a driving element (for example, a piezo element) for discharging ink by changing the capacity of the pressure chamber. When the drive signal is applied to the drive element, the drive element is deformed, and the pressure chamber expands / contracts along with the deformation, and ink is ejected.

  In the present embodiment, an ultraviolet curable ink as an example of an electromagnetic wave curable ink that is cured by being irradiated with ultraviolet rays as an example of electromagnetic waves is used as the ink. Here, cyan, magenta, yellow, and black colored UV-curable inks (hereinafter also simply referred to as inks) are a mixture of a vehicle, a photopolymerization initiator and a pigment, and an auxiliary agent such as an antifoaming agent or a polymerization inhibitor. To be added. The vehicle is prepared by adjusting the viscosity of a photopolymerization-curing oligomer, monomer or the like with a reactive diluent. The ink includes both water-based ink and oil-based ink.

  The printer 2 can eject four colored inks. A head 31 (C) that discharges cyan ink C, a head 31 (M) that discharges magenta ink M, and a head 31 (Y) that discharges yellow ink Y in order from the upstream side to the downstream side in the transport direction. And a head 31 (K) for ejecting black ink K is provided.

  The head 31 has a length in the width direction of the sheet S in the width direction that intersects the transport direction so that the sheet S can be printed on the entire surface of the sheet S only once under the head 31. Longer than that.

  The ultraviolet irradiation unit 40 is for irradiating the ink discharged by the head 31 toward the paper S with ultraviolet rays to cure the ink. The ultraviolet irradiation unit 40 includes a temporary curing unit 41 for irradiating the ink with ultraviolet rays to temporarily cure the ink, and a main curing unit 43 for irradiating the ink with ultraviolet rays to fully cure the ink.

  The ultraviolet irradiation unit 40 is longer in the width direction than the length of the sheet S in the width direction, and the sheet S can irradiate the entire surface of the sheet S only once under the ultraviolet irradiation unit 40.

The temporary curing unit 41 includes a large number of light emitting diodes (LEDs) as light sources for ultraviolet irradiation. Each LED can easily change the irradiation intensity (mW / cm ² ) by controlling the magnitude of the input current. The main curing unit 43 includes a lamp (metal halide lamp, mercury lamp, etc.) as a light source for ultraviolet irradiation.

  Further, the temporary curing portion 41 irradiates ultraviolet rays having a lower irradiation intensity than the main curing portion 43. As a result, the ultraviolet curable ink ejected from the head 31 is not completely cured by the ultraviolet rays irradiated by the temporary curing portion 41 (temporary curing), and the ultraviolet rays irradiated by the main curing portion 43. Is completely cured (main curing).

  In the printer 2 of the present embodiment, a plurality of temporary curing portions 41 corresponding to each of the plurality of heads 31 for irradiating each of the different inks ejected by the plurality of heads 31 are provided. More specifically, the cyan ink C corresponding to the head 31 (C) that discharges the cyan ink C in order from the upstream side to the downstream side in the transport direction and located downstream from the head 31 (C). Corresponding to the pre-curing portion 41 (C) for irradiating the ink and the head 31 (M) for ejecting the magenta ink M, and for irradiating the magenta ink M located downstream from the head 31 (M). The temporary curing unit 41 (M) corresponds to the head 31 (Y) that discharges the yellow ink Y, and the temporary curing unit 41 (for irradiating the yellow ink Y located downstream from the head 31 (Y). Y) and a provisional curing portion 41 (K) for irradiating the black ink K that corresponds to the head 31 (K) that discharges the black ink K and is located downstream from the head 31 (K). Is provided. Only one main curing portion 43 is provided on the most downstream side in the transport direction.

  In the present embodiment, the irradiation intensity is controlled collectively by using a group of a plurality of LEDs as the irradiation unit 42. Specifically, as illustrated in FIG. 3, the LEDs of the temporary curing unit 41 (C) are grouped into five irradiation units 42 </ b> C <b> 1 to 42 </ b> C <b> 5. Similarly, a large number of LEDs provided in the temporary curing portions 41 (M), 41 (Y), and 41 (K) are grouped into five irradiation portions 42, respectively. Each irradiation part 42C1-42C5, 42M1-42M5, 42Y1-42Y5, 42K1-42K5 can control irradiation intensity each independently, and each irradiates a corresponding irradiation area | region.

  Further, the provisional curing unit 41 can switch and irradiate the irradiation condition every time the paper S is transported by a predetermined distance by the transport unit 20. That is, the printing surface on the paper S on which an image is formed by landing of the ultraviolet curable ink is virtually divided in the transport direction to define a printing area. Accordingly, irradiation is performed by switching the irradiation conditions.

<Schematic configuration of computer>
FIG. 4 is a block configuration diagram illustrating functions of the computer 3 that is communicably connected to the printer 2. As shown in the figure, the computer 3 includes a CPU (Central Processing Unit) 71, a memory 72, a storage unit 73, a recording medium reading unit 74, a communication interface 75, an input unit 76, an output unit 77, and the like.

  The CPU 71 reads a program such as a printer driver program stored in the storage unit 73 into the memory 72 and executes it. The memory 72 is, for example, a DRAM (Dynamic Random Access Memory). The storage unit 73 is, for example, a hard disk drive. The recording medium reading unit 74 is a drive device that reads a program and data recorded on a recording medium 78 such as a CD-ROM (Compact Disc Read Only Memory), and supplies the read program and data to the CPU 71. The communication interface 75 is a network connection device such as a NIC (Network Interface Card), for example, and is connected to the printer 2 via a connector (not shown) to perform communication. Accordingly, when the printer 2 receives print data from the computer 3 side, the printer 2 starts processing for printing based on the print data. Further, the computer 3 receives information on the ultraviolet curable ink of each cartridge from the printer 2 side via the communication interface 75. The input unit 76 is, for example, a keyboard or a mouse. The output unit 77 is, for example, a display.

  FIG. 5 is a diagram showing a program stored in a controller functionally provided in the computer 3. As shown in the figure, an application program 81 and a printer driver program 82 are installed in the controller, and the printer driver program 82 operates under a predetermined operating system (OS). When the printer driver program 82 is read into the memory 72 or the like and is in an activated state calculated by the CPU 71, a part for creating print data is functionally realized.

  The application program 81 here is, for example, a program for image processing or image display, which processes an image captured from a digital camera or the like, processes an image drawn by an operator, This is executed when the image is output to the printer driver program 82 after being displayed.

  The printer driver program 82 receives image data from the application program 81 based on a print command from the application program 81 and converts it into print data to be supplied to the printer 2. The printer driver program 82 includes a resolution conversion module 82a, a color conversion module 82b, a halftone module 82c, a rasterizer 82d, a color conversion lookup table, and an SMB table.

  The resolution conversion module 82a converts the resolution of the color image data formed by the application program 81 into the resolution for printing with the printer 2 (for example, when the printer 2 is 720 dpi × 720 dpi, the image data is 720 dpi × 720 dpi). The process of converting to the resolution of the above. The color conversion module 82b converts the RGB image data into multi-tone data of a plurality of ink colors that can be used by the printer 2 for each pixel while referring to the color conversion lookup table. For example, when the printer 2 has four colors of CMYK, the color-converted multi-gradation data becomes CMYK data represented by CMYK, for example, 256 gradations.

  The halftone module 82c is a part that performs processing for converting the above multi-gradation data (CMYK data) into print data of the number of gradations formed by the printer 2. For example, when the head 31 can sort the ink droplets according to the large, medium, and small ink droplets, a process of converting each pixel into large, medium, small, and none data is performed with reference to the SMB table. Here, the SMB table stores in advance the correspondence of how many large, medium, and small dots are generated with respect to the multi-level gradation value indicated by each pixel data for each color.

  In the halftone process, image data is formed by dispersing individual pixels (dots) by a method such as a dither method or an error diffusion method.

  The rasterizer 82d is a part that performs processing for rearranging the print data after the halftone processing in the order of data to be transferred to the printer 2. The print data after the rasterization process is transmitted to the printer 2 together with data indicating the transport direction feed amount.

<Print processing flow>
FIG. 6 is a flowchart showing a printing process executed by the controller when printing is performed by the printing system 1. Hereinafter, the printing process will be described with reference to FIG.

  First, prior to printing, the operator activates the application program 81 to display desired image data (S601).

  When the operator selects a predetermined print mode, for example, for performing high-definition printing, and then issues a print command, the printer driver program 82 is activated based on the print command. When the printer driver program 82 is activated, first, resolution conversion processing corresponding to printing by the printer 2 is executed on the image data by the resolution conversion module 82a (S602).

  The resolution-converted print data is then converted by the color conversion module 82b from RGB print data to CMYK print data, that is, multi-tone data of each color of cyan print data, magenta print data, yellow print data, and black print data. (S603).

  The color-converted print data is further subjected to halftone processing by the halftone module 82c (S604). In other words, the multi-level gradation values indicated by the pixel data constituting the CMYK print data can be expressed by the printer 2 with reference to the SMB table in small levels (for example, large, medium, small, and none). Converted to a value.

  The halftone processed print data is subjected to processing (rasterization processing) by the rasterizer 82d for rearranging in order of data to be transferred to the printer 2 (S605). That is, the print data is rearranged in the order in which dots are formed on the paper S by discharging ultraviolet curable ink from the head.

  For each provisional curing portion 41, each color ink discharge amount per unit area (for example, per square inch) in each print region, which is irradiated by each irradiation unit 42, is obtained (S606). That is, with respect to the printing surface on the paper S, by dividing each irradiation region in the width direction and by each printing region in the transport direction, cells partitioned in a lattice shape are virtually determined, In addition, the ink discharge amount of each color per unit area in each cell is obtained. FIG. 7 is a diagram conceptually showing each cell partitioned in a lattice shape corresponding to the temporary curing portion 41 (C) on the printing surface on the paper S. As shown in the figure, the irradiation area to be printed on the paper S is divided into grid-like cells by dividing each irradiation area 42 in the width direction and dividing each printing area in the transport direction. . Based on the rasterized print data, each color ink discharge amount per unit area in each cell partitioned in a grid is calculated for each temporary curing unit 41.

The ink discharge amount V (ng) of each color per unit area of each cell is such that the ink droplet amount of large dots is α (ng), the ink droplet amount of medium dots is β (ng), and the ink droplet amount of small dots is γ ( ng), for example, it can be obtained by the following equation (1).
V = α · A + β · B + γ · C (1)
Here, A is the number of large dots per unit area, B is the number of medium dots per unit area, and C is the number of small dots per unit area. In addition, the ink discharge amount per unit area is controlled to be the maximum ink discharge amount V _max at the maximum. That is, the ink ejection amount per unit area in the case of a so-called solid printing is a maximum ink ejection amount V _max Then, based on each color ink ejection amount per unit area of each cell is calculated, the irradiation for each cell Conditions are determined for each provisional curing portion 41 (S607).

  Here, the irradiation condition is an irradiation energy amount (mJ / cm 2) per unit area of the ultraviolet rays irradiated by the irradiation unit 42. This is determined by the product of the irradiation intensity (mW / cm 2) of the temporary curing portion 41 and the irradiation time (s) to each dot. Further, the irradiation time (s) to each dot is obtained by dividing the moving direction length (cm) of the region irradiated with ultraviolet rays on the paper S by the moving speed (cm / s) of the temporary curing portion 41.

In addition, the length (cm) in the conveyance direction of the printing area obtained by dividing the printing surface in the conveyance direction is the speed (cm / s) at which the conveyance unit 20 conveys the paper S, and the provisional curing unit 41 switches the irradiation condition. Each temporary curing unit 41 performs irradiation by switching irradiation conditions so as to be longer than the product of the required time (s). FIG. 8 shows the relationship between the ink discharge amount per unit area and the irradiation intensity of ultraviolet rays. It is a graph. As shown in the figure, the control unit 60 controls the temporary curing unit 41 so that the amount of irradiation energy per unit area of ultraviolet light increases as the ink discharge amount per unit area decreases.

  The rasterized print data and the irradiation conditions are transmitted to the printer 2 (S608). Then, the printer 2 prints an image on the paper S based on the received print data and irradiation conditions (S609).

<Operation of printer 2>
Hereinafter, the printing operation of the printer 2 will be described. Note that various operations of the printer 2 when printing is performed are mainly realized by the control unit 60. In particular, in the present embodiment, it is realized by the CPU 62 processing a program stored in the memory 63. And this program is comprised from the code | cord | chord for performing the various operation | movement demonstrated below.

  When the control unit 60 receives the print data rasterized in step S <b> 605 of FIG. 6, the control unit 60 feeds the sheet S stored in the storage unit 25 onto the belt 24. The sheet S is conveyed by the belt 24 without stopping at a constant speed, and is eventually positioned at a position facing the head 31 (C). At this time, the control unit 60 controls the head 31 (C) and executes a cyan ink ejection operation in which the head 31 (C) ejects cyan ink. Dots are formed on the paper S when the cyan ink ejected from the head 31 (C) lands. Then, the paper S is conveyed by the belt 24 and is located at a position facing the temporary curing unit 41 (C). Next, the control unit 60 controls the temporary curing unit 41 (C) so that the temporary curing unit 41 (C) irradiates the cyan ink dots landed on the paper S with ultraviolet rays (cyan). (Temporary curing process for temporarily curing ink dots). Here, the irradiation units 42C1 to 42C5 of the temporary curing unit 41 (C) control the irradiation intensity of the ultraviolet rays corresponding to the respective cells partitioned on the paper S based on the irradiation conditions determined in S607 of FIG. While irradiating with ultraviolet rays. The sheet S is conveyed by the belt 24 and is positioned at a position facing the head 31 (M).

  Similarly, the control unit 60 controls the head 31 (M) and the temporary curing unit 41 (M) to eject magenta ink from the head 31 (M) to land on the paper S, and the irradiation determined in S607. Based on the conditions, the temporary curing process is executed by irradiating the magenta ink landed on the paper S from the temporary curing unit 41 (M) with ultraviolet rays. Then, the sheet S is conveyed by the belt 24 and is located at a position facing the head 31 (Y). Thereafter, the control unit 60 performs the same process for the yellow ink Y and the black ink K.

  After the discharge and temporary curing processing for all CMYK inks is completed, the control unit 60 controls the main curing unit 43 to irradiate the cyan, magenta, yellow, and black inks that have landed on the paper S with ultraviolet rays. Then, a main curing process is performed to fully cure these inks. After the main curing process, printing of the image on the paper S is completed, and the paper S is discharged from the printer 2 to the outside.

<Effectiveness of this embodiment>
According to the present embodiment, it is possible to suppress deterioration in image quality by determining the irradiation condition of the temporary curing unit 41 based on the discharge amount of each color ink per unit area.

  In general, ultraviolet curable inks cure by radical polymerization when irradiated with ultraviolet rays, but when oxygen adheres to ultraviolet curable inks, oxygen functions as an inhibitor and reduces the rate of chain polymerization. It has been known. Therefore, at locations where the amount of ink discharged per unit area is small, the ink layer is easily affected by oxygen from the upper layer, so that oxygen inhibition tends to occur and the ink layer tends to be hard to cure. In order to cope with such properties of the ultraviolet curable ink, the control unit 60 performs control to increase the irradiation energy amount per unit area as the ink discharge amount of each color per unit area is smaller. As a result, an appropriate amount of ultraviolet rays can be applied to the ultraviolet curable ink that has landed on the paper S, and optimal curing can be performed.

  FIG. 9 is a table showing the relationship between the irradiation energy amount of the precured portion 41, the surface tackiness, and the bleed. As shown in the figure, when the amount of ink discharged per unit area is small, the surface tackiness and bleed state are not good if the amount of irradiation energy is small. However, when the ink discharge amount per unit area is small, the irradiation energy amount is increased. When the ink discharge amount per unit area is small, the irradiation energy amount is increased, and when the ink discharge amount per unit area is large. If the amount of irradiation energy is controlled in accordance with the amount of ink discharged per unit area, such as reducing the amount of irradiation energy, surface tackiness and bleeding are improved.

  In addition, by performing optimal curing, if the surface tackiness is good, the handleability of the product (printed material) after printing is improved. That is, since the print image is appropriately cured, the ultraviolet curable ink that has landed on the paper S does not adhere to another location.

  Furthermore, by performing optimal curing, the gloss of the entire image becomes uniform, and the appearance of the entire image is improved.

  Further, according to the present embodiment, for each provisional curing unit 41, each color ink discharge amount per unit area in each cell divided by each irradiation region and each printing region irradiated by each irradiation unit 42 is obtained and this calculation is performed. Based on the discharge amount of each color ink per unit area of each cell, the irradiation condition for each cell is determined for each provisional curing unit 41, so that each portion of the paper S can be more finely and optimally cured. .

  The length (cm) in the conveyance direction of the printing area obtained by dividing the printing surface in the conveyance direction is the speed (cm / s) at which the conveyance unit 20 conveys the paper S, and the time required for the provisional curing unit 41 to switch irradiation conditions. By switching the irradiation conditions and irradiating each temporary curing unit 41 so as to be longer than the product of (s), switching of the irradiation conditions of the temporary curing unit 41 can follow the conveyance speed (cm / s). Thus, the temporary curing process can be executed accurately. Thereby, it is possible to further suppress the deterioration of the image quality.

=== Second Embodiment ===
In the first embodiment, each irradiation unit 42 of each temporary curing unit 41 irradiates a certain raster line with ultraviolet rays under a certain irradiation condition. However, in the second embodiment, each irradiation unit 42 of each temporary curing unit 41 switches the irradiation condition for a certain raster line according to the movement of the raster line by the conveyance of the paper S, thereby Irradiate. The raster line is a dot row generated on the paper S when each head 31 ejects the ultraviolet curable ink once toward the paper S.

  FIG. 10 is a flowchart illustrating a printing process when printing is performed by the printing system 1 according to the second embodiment. As shown in the figure, S1001 to S1005 perform the same processing as S601 to S605 in FIG.

  Next, the computer 3 identifies each image area (S1006). FIG. 11 is a conceptual diagram illustrating a relationship between raster lines a to g and image regions R1 to R3 configured by a plurality of adjacent raster lines. As shown in the figure, the image region R1 is composed of three raster lines b to d. In the image region R2, the raster e adjacent to the upstream side in the transport direction of the image region R1 is replaced one by one with the raster b located on the most downstream side in the transport direction among the rasters b to d constituting the image region R1. Identified. Similarly, in the image area R3, the raster c adjacent to the upstream side in the transport direction of the image area R2 is replaced one by one with the raster c located on the most downstream side in the transport direction among the rasters c to e constituting the image area R2. Identified. In this way, each image region is specified by sequentially performing the operation of specifying the image region.

  Then, based on the calculated color ink discharge amount per unit area of each image area, the irradiation condition for each image area is determined for each temporary curing unit 41 (S1007, 1008). Further, the rasterized print data and the irradiation conditions are transmitted to the printer 2 (S1009). Then, the printer 2 prints an image on the paper S based on the received print data and irradiation conditions (S1010).

  As described above, according to the second embodiment, one raster adjacent to the upstream side of the image area in the transport direction is replaced with one raster located in the most downstream side in the transport direction among the rasters constituting the image area. By obtaining each color ink discharge amount per unit area in each sequentially specified image area based on rasterized print data, it is possible to moderate changes in irradiation conditions and suppress deterioration in image quality. be able to.

  In the second embodiment, the number of rasters constituting the image area is not limited to three, and may be any number as long as it is two or more, for example, 200. Further, the number of rasters to be replaced when sequentially specifying image areas is not limited to one, and may be any number, for example, twenty.

=== Other Embodiments ===
Although the first embodiment is mainly described with respect to a printing apparatus, disclosure of a printing method and the like is also included. The first embodiment is intended to facilitate understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About the head>
In the first embodiment, the head 31 that ejects ink using a piezoelectric element is used. However, the method for discharging the fluid is not limited to this. For example, other methods such as a method of generating bubbles in the nozzle by heat may be used.

<About UV curable ink, temporary curing portion and main curing portion>
In the first embodiment, ultraviolet curable ink is used as an example of ink ejected from the head unit 30, and ultraviolet light is used as an example of electromagnetic waves emitted from the temporary curing unit 41 and the main curing unit 43. However, the present invention is not limited thereto. It is not something. For example, electromagnetic waves such as an electron beam, X-rays, and visible light may be included in the electromagnetic waves irradiated by the temporary curing unit 41. Further, the main curing unit 43 may irradiate electromagnetic waves such as electron beams, X-rays, and visible light. Further, the ink may be ink that is cured by electromagnetic waves corresponding to these.

<Regarding the control flow of the temporary curing unit 41>
In the first embodiment, for each provisional curing unit 41, each color ink discharge amount per unit area in each cell divided by each irradiation region and each printing region irradiated by each irradiation unit 42 is obtained and calculated. Based on the discharge amount of each color ink per unit area of each cell, the irradiation condition for each cell is determined for each temporary curing portion 41.

  However, the irradiation condition for each cell is not determined, and the irradiation condition may be simply determined for each temporary curing portion 41. According to such an embodiment, the amount of processing information in the computer 3 can be reduced.

  In addition, each color ink discharge amount per unit area in each print region is obtained for each pre-curing unit 41, and the irradiation condition for each print region is determined based on the calculated color ink discharge amount per unit area in each print region. It is good also as determining for every temporary hardening part 41. FIG.

  Further, each color ink discharge amount per unit area in each irradiation region irradiated by each irradiation unit 42 for each provisional curing unit 41 is obtained, and based on each color ink discharge amount per unit area in each calculated irradiation region, It is good also as determining the irradiation conditions in each irradiation area | region for every temporary hardening part 41. FIG.

<About the controller>
In the first embodiment, the controller that executes the processes illustrated in S601 to S607 in FIG. 6 is provided in the computer 3, but the controller may be provided in the printer 2, and in this case, the printer 2 The provided controller may execute each process of S601 to S607.

  In addition, the controller may be provided in the printer 2 and the computer 3 respectively. In this case, the controller provided in the printer 2 and the computer 3 may execute the processes of S601 to S607 in a shared manner.

  Similarly, in the second embodiment, the controller that executes each process shown in S1001 to S1008 in FIG. 10 is provided in the computer 3, but the controller may be provided in the printer 2, in this case, A controller provided in the printer 2 may execute each process of S1001 to S1008.

  The controller may be provided in each of the printer 2 and the computer 3, and in this case, the controller provided in the printer 2 and the computer 3 may execute the processes of S1001 to S1008 in a shared manner.

<Print processing flow>
In the print processing flow shown in FIG. 6, the process of S <b> 608 may be executed before each of the processes of S <b> 601 to S <b> 607.

  Similarly, in the print processing flow shown in FIG. 10, the process of S1009 may be executed before each process of S1001 to S1008.

DESCRIPTION OF SYMBOLS 1 Printing system 2 Printer 3 Computer 20 Conveyance unit 23A Upstream conveyance roller 23B Downstream conveyance roller 24 Belt 30 Head unit 31 Head 40 Irradiation unit 41 Temporary curing part 42 Irradiation part 43 Main curing part 50 Detector group 60 Control part 61 Interface Unit 62 CPU
63 Memory 64 Unit control circuit 71 CPU
72 Memory 73 Storage unit 74 Recording medium reading unit 75 Communication interface 76 Input unit 77 Output unit 78 Recording medium 81 Application program 82 Printer driver program 82a Module 82b Module 82c Halftone module 82d Rasterizer

Claims (8)

Each head that discharges a different color of electromagnetic curable ink toward the medium one by one,
Each electromagnetically curable ink ejected from each head and landed on the medium is irradiated with electromagnetic waves to temporarily cure the electromagnetic wave curable ink, and each temporary curing portion corresponding to each head;
A controller that determines the irradiation condition of each temporary curing portion based on the ink discharge amount of each color per unit area obtained based on the print data that has been halftone processed for each of the different colors. And printing system. The printing system according to claim 1,
A transport unit that transports the medium in the transport direction;
Each of the temporary curing portions is based on an irradiation condition that is switched according to a printing region in which a printing surface on which an image is formed by landing of the electromagnetic wave curable ink on the medium is divided into a plurality in the transport direction. Irradiate
The printing system, wherein the controller determines the irradiation condition of the temporary curing portion in each of the print regions based on an ink discharge amount of each color per unit area in each of the print regions. The printing system according to claim 1 or 2,
Each pre-curing part has a plurality of irradiation parts that are arranged in parallel in the width direction intersecting with the transport direction, irradiate irradiation regions corresponding to each, and can be independently controlled,
The printing system according to claim 1, wherein the controller determines the irradiation condition of each irradiation unit in each irradiation region based on each color ink discharge amount per unit area in each irradiation region. The printing system according to claim 1,
A transport unit that transports the medium in the transport direction;
Each of the temporary curing portions is an image area configured by having a plurality of rasters generated on the medium by the heads ejecting the electromagnetic wave curable ink once toward the medium, Each of the image areas sequentially identified by replacing the raster adjacent to the upstream side in the transport direction with respect to the image area with the raster located in the most downstream of the transport direction among the rasters constituting the image area. Irradiate based on the irradiation conditions sequentially switched according to
The controller determines the irradiation condition of the temporary curing portion in each of the image regions based on each color ink discharge amount per unit area in each of the image regions that are sequentially specified. . The printing system according to claim 2,
The length of the printing region in the transport direction is longer than a length obtained by a product of a speed at which the transport unit transports the medium and a time required for the temporary curing unit to switch the irradiation condition. Printing system to do. A printing system according to any one of claims 1 to 5,
A computer and a printing device capable of communicating with the computer;
The computer
The controller;
An interface that transmits halftone processing data for each of the different colors and the irradiation condition to the printing apparatus;
The printing apparatus includes:
Each of the heads;
Each of the temporary curing portions,
A printing system comprising: print data subjected to halftone processing for each different color and an interface for receiving the irradiation condition from the computer. Each head that discharges a different color of electromagnetic curable ink toward the medium one by one,
Each electromagnetically curable ink ejected from each head and landed on the medium is irradiated with electromagnetic waves to temporarily cure the electromagnetic wave curable ink, and each temporary curing portion corresponding to each head;
A print control program for causing a computer to realize a function of controlling a printing apparatus comprising:
On the computer,
A function of generating halftone processed print data for each of the different colors;
A function for determining each color ink discharge amount per unit area based on the halftone processed print data;
A function for determining the irradiation condition of each temporary curing portion based on the discharge amount of each color ink per unit area;
A print control program characterized by realizing the above. A printing method for printing by a printing apparatus,
Generating halftone processed print data for each different color;
Obtaining each color ink discharge amount per unit area based on the halftone processed print data;
Irradiating electromagnetic waves on the basis of the discharge amount of each color ink per unit area, respectively determining the irradiation conditions of each temporarily cured portion for temporarily curing the electromagnetic wave curable ink;
Discharging the different color electromagnetic curable ink from the head toward the medium one by one,
The electromagnetic wave curable ink ejected from the heads and landed on the medium is irradiated with electromagnetic waves from the temporary curing units corresponding to the heads under the irradiation conditions to temporarily cure the electromagnetic wave curable ink. And
A printing method characterized by comprising:

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