JP2009012312A - Fluid ejection device and fluid ejection control method in fluid ejection device - Google Patents

Abstract

A fluid ejecting apparatus and a fluid ejecting control method in a fluid ejecting apparatus capable of expressing appropriate black when color is superimposed by ejecting a plurality of colors of fluid from a fluid ejecting head to generate black. .
Line heads 12 and 13 constituting a printer are arranged in two rows in the transport direction X, with the width direction orthogonal to the transport direction X of the paper 14 being the longitudinal direction. The five nozzle rows 31 of the line head 12 are arranged in the order of cyan (C), light cyan (LC), magenta (M), light magenta (LM), and yellow (Y). The colors are arranged in the order of Y, LM, M, LC, and C in the reverse color order of the line head 12. For example, when printing black using three colors (CMY), first, ink droplets are ejected from the three color nozzle rows 31 of the line head 12 in the order of CMY, and then from the three color nozzle rows 32 of the line head 13. Ink droplets are ejected in the order of YMC.
[Selection] Figure 2

Description

  The present invention relates to a fluid ejecting apparatus including a fluid ejecting head that ejects a fluid onto a target such as a recording sheet like a recording head included in an ink jet printer, and a fluid ejecting control method in the fluid ejecting apparatus.

  As this type of fluid ejecting apparatus, for example, Patent Document 1 discloses a line-type ink jet printer that includes an ink jet recording head and performs printing by ejecting ink droplets onto a recording sheet as a target.

In Patent Documents 2 and 3, in a serial inkjet printer, as a method of printing black on paper, in addition to a method of ejecting black ink, cyan (C), magenta (M), and yellow (Y) A method is disclosed in which color inks are overlaid on paper and black is produced by color mixture. For example, in Patent Document 2, after black ink is printed, cyan, magenta, and yellow are gradually mixed to obtain a glossy black while suppressing the maximum amount of black ink used. Regardless of the printing method, some line printers print black by mixing three primary colors such as cyan, magenta, and yellow.
JP 2007-76872 A JP 2006-140655 A Japanese Patent Laid-Open No. 9-52390

  However, since conventional printers perform color superposition once with three primary colors such as cyan, magenta, and yellow, black tends to be thin, and depending on the printed matter, black may appear blurred or dark gray. There was a problem that it might be visible. Although the ink ejection amount may be increased, there is a limit to the ink ejection amount per time.

  Of course, in Patent Document 2, since black is printed with black ink and then cyan, magenta, and yellow are gradually mixed, the problem of faint black is unlikely to occur, but the black nozzle is indispensable. There was a problem that had to be done.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an appropriate black when black is produced by performing color superimposition in which a plurality of colors of fluid are ejected from a fluid ejecting head. An object of the present invention is to provide a fluid ejecting apparatus capable of developing and a fluid ejecting control method in the fluid ejecting apparatus.

The present invention is a fluid ejecting apparatus including a fluid ejecting head capable of ejecting a fluid to a target,
At least one fluid ejecting head in which a plurality of nozzle rows capable of ejecting a plurality of colors of fluid capable of expressing black by color mixing are provided in two or more groups in the target transport direction;
Control means for controlling the at least one fluid ejecting head,
When the control means performs color superposition for sequentially ejecting the plurality of colors of fluid to the target position on the target to develop black, the plurality of colors of fluid are sequentially ejected from the two or more nozzle rows. The gist is to perform the color superposition once for each group of the nozzle rows and to control the fluid ejecting head so that the color superposition is performed twice or more in total.

  According to this, by controlling the fluid ejecting head, the control unit sequentially ejects a plurality of colors of fluid from the two or more nozzle arrays to the target, thereby generating a color overlap that causes black to appear per group of nozzle arrays. By performing once, color superposition is performed twice or more in total. Since black is expressed by two or more color overlaps, black with high color strength can be obtained.

  In the fluid ejecting apparatus according to the aspect of the invention, a plurality of the fluid ejecting heads are arranged in the target transport direction, and the fluid ejecting heads are arranged in the order of arrangement in which a plurality of colors of fluids can be ejected sequentially in the target transport direction. When a plurality of nozzle rows are arranged and a group of nozzle rows is provided for each fluid ejecting head, and the control means performs color superposition to eject the plurality of colors of fluid onto the target to express black, It is preferable that the plurality of fluid ejecting heads are controlled so that color superimposition is performed once for each of the fluid ejecting heads, and color overlapping is performed twice or more in total.

  According to this, when the control means controls the fluid ejecting heads, a plurality of colors of fluid are ejected from the plurality of fluid ejecting heads to the target, and a color overlap that expresses black is performed once for each fluid ejecting head. By doing so, color superposition is performed twice or more in total. Black with high color strength is obtained by two or more color overlaps.

  In the fluid ejecting apparatus according to the aspect of the invention, at least one group of the two or more groups is the target transport of the plurality of nozzle rows belonging to one group and the nozzle row belonging to the other group. The arrangement order in the direction is preferably different.

  According to this, the arrangement order of the plurality of nozzle rows provided in the fluid ejecting head is such that at least one set of groups belongs to the plurality of nozzle rows belonging to one group and the other group. It differs from the nozzle row. The black color that appears depends on the order of color overlap, so if you overlap two or more times, you will overlap two or more times with different colors, resulting in black that has almost no color other than black. Or create subtle gradations of black.

  In the fluid ejection device according to the aspect of the invention, it is preferable that two groups of nozzle rows adjacent to each other in the target transport direction among the two or more groups are provided in reverse color order in the target transport direction.

  According to this, two adjacent groups of nozzle rows are provided in the reverse color order in the target transport direction, so that it is possible to change the black color appearing in one color overlap each time. For this reason, it is possible to express black that has almost no other color other than black, or to effectively create a black gradation by overlapping black with different colors twice or more.

In the fluid ejecting apparatus according to the aspect of the invention, it is preferable that the control unit controls the fluid ejecting head so as to change a fluid ejecting amount ejected by color overlap each time.
According to this, since the fluid ejection amount ejected by color superposition is changed each time, the superposition ratio (fluid ratio of each black) when superimposing different colors is changed. Therefore, a fine gradation of black can be created by adjusting the overlapping ratio.

  In the fluid ejecting apparatus according to the aspect of the invention, the control unit adjusts the amount of fluid ejected each time for the color superimposition according to the black gradation value obtained by analyzing the fluid ejecting process data. It is preferable to do.

  According to this, the fluid ejection amount at each time of color superposition is adjusted according to the black tone value obtained by analyzing the fluid ejection processing data. Therefore, it is possible to create a fine black gradation corresponding to the black gradation value in the fluid ejection processing data.

  The present invention is a fluid ejection control method in a fluid ejection apparatus including a fluid ejection head capable of ejecting a fluid to a target, wherein at least one fluid ejection head is provided, and all of the fluid ejection heads are black. When two or more groups of nozzle rows capable of ejecting a plurality of colors of fluid that can be expressed are provided, and black is expressed by performing color superposition for ejecting the plurality of colors of fluid onto a target, the two groups or more A step of sequentially ejecting a plurality of colors of fluid from one group of nozzle rows and performing color superposition once on the target, and a plurality of colors of fluid from one of the two or more groups of nozzle rows. And a step of performing color superimposition once more on the fluids that are sequentially ejected and color-superimposed.

  According to this, two or more groups of nozzle arrays arranged in the target transport direction are used to perform color superposition twice so that a plurality of colors of fluid are sequentially ejected to develop black. Therefore, the same effect as the invention of the fluid ejecting apparatus can be obtained.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
FIG. 1 shows an ink jet recording apparatus as a fluid ejecting apparatus. In FIG. 1, the case of the recording apparatus is omitted.

  As shown in FIG. 1, an ink jet recording apparatus (hereinafter simply referred to as a printer 11) includes a plurality (two in this example) of line heads 12 as fluid ejecting heads capable of printing a range over the entire maximum sheet width. , 13 (recording head).

  The two line heads 12 and 13 are supported by a support member (not shown), and the longitudinal direction is substantially parallel to the width direction Y intersecting the transport direction (X direction in FIG. 1) of the paper 14. Arranged in two rows.

  A platen 15 that defines a gap between the sheet 14 and the line heads 12 and 13 is disposed below the line heads 12 and 13. Further, a cap 16 for capping the nozzle forming surfaces 12A and 13A (see FIG. 2) of the line heads 12 and 13 is opposed to the lower facing positions of the line heads 12 and 13 with the opening 15A facing each other. Each of the maintenance devices 17 provided is provided. When a predetermined time (for example, a value between 5 and 20 seconds) elapses during printing, printing is performed on the cap 16 from all the nozzles of the line heads 12 and 13 when the paper 14 is switched at the time of paper supply / discharge. Performs flushing to eject ink droplets that are not related to discharge the thickened ink in the nozzles that are not used for printing, thereby preventing clogging of the nozzles. Each cap 16 is provided so as to be movable up and down, and is connected to a discharge port of a suction pump (both not shown) through a pipe (tube). Then, a suction force is applied to each cap 16 by driving the pump motor under the capping state in which the cap 16 is in contact with the nozzle forming surfaces 12A and 13A (see FIG. 2) of the line heads 12 and 13. Therefore, cleaning is performed by sucking and removing thickened ink, bubbles, and the like from the nozzle 33 (see FIG. 4) that opens to the nozzle formation surfaces 12A and 13A by the negative pressure.

  As shown in FIG. 1, a paper guide 20 is provided at a position upstream of the platen 15 in the paper conveyance direction X (on the right side in FIG. 1). The paper guide 20 includes a plate-like guide support member 21 and a movable guide member 22 attached to the guide support member 21 so as to be slidable in the width direction Y. In a state in which the fixed guide portion 21A of the guide support member 21 is guided by applying one end in the width direction (upper end in FIG. 1) of the paper 14, the user holds the movable guide portion 22A by hand and slides it in the width direction Y. Thus, the sheet 14 can be aligned in the width direction Y.

  As shown in FIG. 1, a plurality of paper feed rollers 24 provided on the rotary shaft 23 are disposed in the vicinity of the downstream side of the paper guide 20 in the paper conveyance direction X. A hopper (not shown) provided on the paper guide 20 is tilted during paper feeding, and the uppermost sheet of the paper group stacked on the paper guide 20 comes into contact with the paper feeding roller 24. When the paper feed roller 24 is driven to rotate in the contact state, the uppermost sheet 14 is fed in the transport direction X. The rotary shaft 23 of the paper feed roller 24 is connected to a paper feed motor 25 (shown in FIG. 3) so that power can be transmitted. Further, a conveying device 26 that conveys the paper 14 to the line heads 12 and 13 is provided between the paper feed roller 24 and the platen 15. The conveying device 26 includes a pair of driving rollers 26A and a driven roller 26B, and a conveying motor 28 connected via the driving roller 26A and a gear mechanism 27 (wheel train) is driven to thereby connect the rollers 26A and 26B. The paper 14 nipped in the paper is fed in the transport direction X. In addition, a paper discharge device 29 is provided on the downstream side of the platen 15 in the conveyance direction, and a pair of driving rollers 29A and driven rollers 29B constituting the paper discharge device 29 are rotationally driven by the driving force of the conveyance motor 28. Thus, the paper 14 is transported and discharged. In this way, the paper 14 is transported on the platen 15 through the line heads 12 and 13, and ink droplets are ejected from the line heads 12 and 13 to perform printing on the paper 14. The transport device 26 and the paper discharge device 29 can be replaced with a roller drive system, and an electrostatic attraction belt transport device can also be adopted. A configuration in which the conveyance motor 28 is used as a power source for the paper feed roller 24 can also be employed.

  The line heads 12 and 13 are five color inks (in this example, cyan (C), light cyan (LC), magenta (M), light magenta (LM), Three ink cartridges (not shown) each containing yellow (Y) are connected through ink supply tubes for each ink color. Ink is supplied to the line heads 12 and 13 from each ink cartridge through an ink supply tube. As an ink supply method for the ink cartridge, a method using a water head difference or a method using a pressurizing force can be adopted. Examples of the method using the pressurizing force include a method using pressurized air and the like, a method of applying pressure with the magnetizing force of a magnet, and a method of applying pressure with an urging force of an urging means such as a spring.

FIG. 2 is a schematic bottom view of the line head as viewed from the nozzle forming surface side. In FIG. 2, the line head and the paper are drawn shorter in the printer width direction than actual.
Nozzle formation surfaces 12A and 13A, which are the bottom surfaces (lower surfaces) of the line heads 12 and 13, have five nozzle rows 31C, 31LC, and 31M corresponding to five colors (C, LC, M, LM, and Y) of ink. , 31LM, 31Y, 32Y, 32LM, 32M, 32LC, and 32C. Note that the nozzle rows of the line heads 12 and 13 are referred to as nozzle rows 31 and 32, respectively, when the ink color is not particularly conscious. One nozzle row 31 and 32 is composed of a group of a large number (for example, 180) of nozzles 33 (shown in FIG. 4) formed along the width direction Y orthogonal to the conveyance direction X of the paper 14. The nozzles 33 are staggered along the width direction Y as shown in FIG.

  Here, between the line heads 12 and 13, nozzle rows of the same color, that is, cyan nozzle rows 31C and 32C, light cyan nozzle rows 31LC and 32LC, magenta nozzle rows 31M and 32M, and light magenta nozzle rows 31LM and 32LM. The yellow nozzle rows 31Y and 32Y are arranged such that the corresponding nozzles 33 are overlapped when the nozzles 33 constituting each of them are projected in the width direction Y at the same pitch and in the transport direction X. For this reason, the same color ink droplets ejected from the nozzles 33 of the line head 13 can be landed on the ink droplets ejected from the nozzles 33 of the line head 12 and landed on the paper 14.

  As shown in FIG. 2, the five nozzle rows 31 of the line head 12 are, in order from the upstream side in the transport direction X, cyan (C) nozzle row 31C, light cyan (LC) nozzle row 31C, and magenta (M). There are a total of five nozzle rows 31M, a light magenta (LM) nozzle row 31LM, and a yellow (Y) nozzle row 31Y. The five nozzle rows 31 of the line head 13 arranged on the downstream side in the transport direction X with respect to the line head 12 are five nozzle rows 31Y, 31LM, arranged in the color order opposite to that of the line head 12. It consists of 31M, 31LC, 31C. Therefore, in the line head 12, the nozzle rows 31 are arranged in the order of the ink colors “C, LC, M, LM, Y” from the upstream side in the transport direction X. The line head 13 has a color order opposite to the color order of the nozzle rows 31 of the line head 12 from the upstream side in the transport direction X, that is, the color order of the ink colors “Y, LM, M, LC, C”. Each nozzle row 32 is arranged. That is, as shown in FIG. 2, the nozzle rows 31 and 32 of the line heads 12 and 13 are arranged in an order in which the color order is line symmetric in the transport direction X. At the time of paper conveyance, the paper 14 passes directly under a total of ten nozzle rows 31 and 32 arranged in the ink color order of “C, LC, M, LM, Y” and “Y, LM, M, LC, C”. In order to pass, ink is overlaid on the paper 14 in the order defined in this color order. When printing black, a method of ejecting ink droplets of five colors from all the nozzle rows 31 and 32 and a droplet of three colors from the nozzle rows 31 and 32 of “C, M, Y” are ejected. There is a method, and black (composite black) is expressed by mixing five or three colors of ink on the paper 14. In the method of mixing five colors, the number of yellow nozzle rows is only half (specifically, one per head) compared to the number of cyan and magenta nozzle rows, so in the yellow nozzle rows 31Y and 32Y, In addition, the ink ejection amount per nozzle is increased by a predetermined time (for example, twice) compared to each of the cyan and magenta nozzle rows so as to balance the amount of ink to be mixed for each color. The group of nozzle rows refers to a group of nozzle rows used for expressing black by mixing colors. In the five-color superposition method, all five nozzle rows form a group, and in the three-color superposition method, CMY. Three nozzle rows form a group.

  FIG. 3 shows the electrical configuration of the printer. As shown in FIG. 3, the printer 11 is used in a state where it is communicably connected to a host computer 35 (for example, a personal computer). The printer 11 includes a controller 40, a head driver 41, and motor drivers 42 and 43. The controller 40 is connected to the line heads 12 and 13 via a head driver 41, is connected to the paper feed motor 25 via a motor driver 42, and is further connected to the transport motor 28 via a motor driver 43.

  The controller 40 includes a CPU 51, an ASIC 52 (Application Specific IC), a ROM 53, and a RAM 54. The ROM 53 stores various programs that are executed by the CPU 51. In the present embodiment, the ROM 53 stores reference data for determining the control content of the ink discharge control of the line heads 12 and 13, an ink discharge control routine program, and the like. The CPU 51 performs ink ejection control of the line heads 12 and 13 by executing the ink ejection control routine program stored in the ROM 53. The RAM 54 is used as a work memory for the CPU 51 to temporarily store data such as calculation results.

  The host computer 35 has a printer driver 36 built therein. For example, the printer driver 36 performs a process of generating print data from color image data (color image data) displayed on a monitor (not shown) of the host computer 35. As part of the processing, RGB image data is converted into CMY image data with reference to, for example, a color conversion table. The print data is transmitted from the host computer 35 to the printer 11 and stored in a predetermined storage area of the RAM 54 in the controller 40.

FIG. 4 shows the configuration of the print control circuit in the head driver. In FIG. 4, only one row for one color is shown for the nozzle row.
The head driver 41 includes a print drive circuit 60 shown in FIG. The print drive circuit 60 includes a drive signal generation circuit 61 that outputs an ejection drive signal DS composed of one set (for example, two) of voltage pulses having different voltage waveforms, a shift register 62, a latch circuit 63, a level shifter 64, and a switch element 65. , Each ejection drive element 66 is provided. One ejection drive element 66 is provided for each nozzle 33 of the line heads 12 and 13, and in this embodiment, a piezoelectric vibrator is used. Of course, it is sufficient that the ejection drive element 66 is an element that can be used for the line heads 12 and 13 of the ink jet system. In addition to the piezoelectric vibrator, for example, an electrostatic drive element or a thermal system (film boiling) used for the electrostatic drive system. For example, a heater (for example, a heating resistance element) used in the method may be used.

Based on the control signal from the controller 40, the drive signal generation circuit 61 generates and outputs an ejection drive signal DS in synchronization with the ejection timing at which ink is ejected when printing is performed.
Each shift register 62 has dot data SI (for example, any one of 2-bit gradation value data “00”, “01”, “10”, “11”) synchronized with a clock signal CK from an oscillation circuit (not shown). ) Is entered. Each shift register 62 first sets the upper bit data of the dot data sequentially.

  When the upper bit data is set in each shift register 62, the latch circuit 63 latches the data set in the shift register 62 based on the latch signal LAT input at a predetermined timing.

  When the data is “1”, the level shifter 64 boosts the latched data to a predetermined voltage value (for example, several tens of volts), and the switch element 65 is connected by the boosted data. On the other hand, when the data is “0”, each level shifter 64 does not boost the data, and the switch element 65 is disconnected.

  The switch element 65 receives the ejection drive signal DS shown in FIG. 4 from the drive signal generation circuit 61. The ejection drive signal DS includes a first pulse COM1 and a second pulse COM2. The first pulse COM1 of the ejection drive signal DS is applied to each switch element 65 at the timing when the switch element 65 is connected based on the upper bit “1”. When the upper bit data is output, the dot data is then shifted to the lower bit data, and at the timing when the switch element 65 is connected based on the lower bit “1”, the second pulse COM2 is switched to each switch. Applied to the element 65.

  That is, when dot data of “01” is output, only the second pulse C0M2 of the ejection drive signal DS is applied to the ejection drive element 66, and small dot ink is ejected. When the dot data SI of “10” is output, only the first pulse COM1 of the ejection drive signal DS is applied to the ejection drive element 66, and the medium dot ink is ejected. When output, both the first pulse COM1 and the second pulse COM2 are applied to the ejection drive element 66, and large dot ink is ejected. As described above, the voltage pulse selected according to the gradation value of the dot data SI in the ejection drive signal DS is applied to the ejection drive element 66, so that the ejection drive is performed with the intensity according to the applied voltage pulse. The element 66 is driven to discharge, and an ink droplet having a size corresponding to the gradation value is ejected from the nozzle 33. The voltage waveform of the ejection drive signal DS in FIG. 4 is a schematic diagram for explaining a configuration in which ink droplets are divided into large, medium, and small. The voltage waveform of each pulse and the combination thereof are ink characteristics (viscosity, etc.) and lines. Depending on the ejection characteristics of the heads 12 and 13 and the like, the ink droplets may be appropriately changed so as to be divided into appropriate dot sizes. Also, the dot size of the ink droplet is not limited to three types of large, medium, and small, and control that can be divided into two types of large and small, or four or more types of dot sizes can be employed. Further, a fluid ejecting head having a plurality of types of nozzles having different nozzle opening sizes (for example, large and small nozzles) may be employed, and a method of adjusting the dot size of ink droplets by selectively using nozzles having different nozzle opening sizes may be employed. Of course, a method of ejecting ink droplets with only one kind of dot size can also be adopted.

  In the present embodiment, when printing at least black, for example, in the case of the three-color superposition method, the line heads 12 and 13 perform color superimposition of three colors (CMY) twice, once in total, for a total of two times. Is overlaid. According to the arrangement order of the nozzle rows 31 and 32 of the line heads 12 and 13, the color superposition order is performed in the order of “CMY” for the first time, and is performed in the order of “YMC” for the second time. . In addition, since the ink ejection amount can be selected from large, medium, and small, it is also possible to change the ink ejection amount between the first time and the second time. For example, for the purpose of changing the color mixture ratio and producing a black gradation The ink ejection amount for each color is adjusted.

  When printing is executed in the printer 11, the CPU 51 in the controller 40 executes an ink ejection control processing routine, and in particular, executes a black printing processing routine program shown in FIG. 5 for black printing. . FIG. 6 is an explanatory diagram of a process for determining an ink ejection amount that is employed for each color overlap during black printing. Hereinafter, the ink ejection control executed by the CPU 51 will be described with reference to FIGS. 5 and 6. An example of a three-color superimposing method in which three colors (CMY) are overlaid and black is printed will be described.

  Prior to printing, for example, the user operates the input device of the host computer 35 connected to the printer 11 to instruct execution of printing. Upon receiving this print execution instruction, the printer driver 36 converts a color image such as RGB image data or JPEG data into CMY image data. As shown in FIG. 5, the CMY image data is composed of three sheets of cyan image data CD, magenta image data MD, and yellow image data YD. In the present embodiment, the CMY image data corresponds to the fluid ejection processing data.

  The printer driver 36 (that is, the CPU in the host computer 35) executes a black printing processing routine program shown in FIG. 5 that determines the ink ejection amount of the line heads 12 and 13 when printing black. That is, by executing this program, the ink ejection amount at each time of color superposition is determined.

  In step S1, a black area is detected from the CMY image data. The black area is detected by examining CMY gradation values. A dot existing area in which all CMY3 color density values are high, that is, each CMY3 color tone value is a predetermined value or more is detected as a black area.

  In step S2, it is determined whether there is a black area. If a black area is detected, the process proceeds to step S3. On the other hand, if a black area is not detected, this routine is terminated and the routine proceeds to normal processing for printing a color other than black.

In step S3, the tone value of the black dot is acquired.
In step S4, the ink ejection amount for each time is determined with reference to the conversion table BT. Here, the conversion table BT is stored in advance in the ROM 53, and is a table showing the relationship between the black gradation value and each injection amount ratio, and the black gradation value is converted into the first color overlap and the second color. It is table data which can acquire the division ratio in superposition as a return value. Then, the dot gradation value of the black area is divided by the division ratio, and each of the gradation values divided by the division ratio is divided into two pieces of CMY image data having the dot gradation value. Specifically, as shown in FIG. 5, the CMY image data CD, MD, and YD for the black area are used for the line head 12 by referring to the conversion table based on the tone value of the dot of the CMY image data for the black area. Are divided into CMY image data CD1, MD1, YD1, and CMY image data CD2, MD2, YD2 for the line head 13. For example, if the division ratio (%) is 60:40 for the first time and the second time, for example, the gradation value 255 is divided into the gradation value “153” and the gradation value “102”. Thus, the cyan image data CD is divided into cyan image data CD1 having a gradation value of “60%” and cyan image data CD2 having a gradation value of “40%”. Similarly, magenta image data MD is divided into magenta image data MD1 and MD2, and yellow image data YD is divided into yellow image data YD1 and YD2.

  Here, the conversion table BT is a value set based on the following idea, and is created using a value verified in advance in a preliminary experiment. FIG. 7 is a schematic diagram showing a state of ink droplets landed so that three color ink droplets are superimposed on a sheet. The first color is overlaid in the order of CMY, and the second time is overlaid in the order of YMC. If the first and second color overlap order CMY is the same, the black color depends on the color overlap order, so the first black color and the second black color are the same, and this is repeated. However, only the intensity of the black color increases, and the color itself does not change. On the other hand, as shown in FIG. 7, according to this example in which the first color superposition order is different from the second color superposition order, the black color obtained by the first color superposition and the second color superposition are obtained. Since the black color obtained by overlapping is different, two layers of black with different colors are overlapped, and the color of the entire dot is the ratio of the ink amount of each time, that is, the first layer black and the second layer Depends on the ratio of each black ink amount. Therefore, it is possible to adjust the color of the entire dot by changing the ratio of the ink ejection amount between the first time and the second time. A relationship between the color of the entire dot and the ratio between the first ink ejection amount and the second ink ejection amount is obtained through experiments, and the conversion table BT is created based on the obtained data. Note that the mixing ratio of the three colors is common to each time.

  The gradation value of the black dot corresponds to the cyan gradation value corresponding to that dot in the cyan image data CD, the magenta gradation value corresponding to that dot in the magenta image data MD, and that dot in the yellow image. And the yellow gradation value. Each injection amount ratio is acquired from the gradation value of the black dot with reference to the conversion table BT. The gradation values of the three color dots that make up the black dot are divided by the respective injection amount ratios. The cyan image data CD in the black area is divided into two image data CD1 and CD2 each having a gradation value obtained by dividing the C gradation value of the dot by the ratio of each injection amount as the C gradation value of the dot. Further, the magenta image data MD in the black area is divided into two pieces of image data MD1 and MD2 each having each gradation value obtained by dividing the M gradation value of the dot by each injection amount ratio as the M gradation value of the dot. Similarly, the yellow image data YD of the black region is divided into two pieces of image data YD1 and YD2 each having a gradation value obtained by dividing the Y gradation value of the dot by the ratio of each injection amount as the Y gradation value of the dot.

  The image data MD1, MD2, YD1, YD2 are respectively developed on the RAM. Then, halftone data based on the image data CD1, MD1, YD1 is sent to the line head 12, and halftone data based on the image data CD2, MD2, YD2 is sent to the line head 13. The halftone data is data of four gradations corresponding to the large, medium, and small ink droplets used for printing by the line heads 12 and 13 with the gradation values of the image data CD1, CD2, MD1, MD2, YD1, and YD2. 4 gradation data obtained by performing a halftone process for converting to. The line heads 12 and 13 are controlled to be discharged based on the halftone data.

  When the printer driver 36 performs processing, the printer 11 receives the data after halftone processing as print data. On the other hand, when the CPU 51 in the printer 11 adopts a configuration in which the black print processing routine is executed, at least the conversion table BT is stored in the ROM 53, and the image data has two gradation values corresponding to the respective ejection amount ratios. The CPU 51 executes the process of dividing the image data.

  Thus, the dot data SI shown in FIG. 4 is based on the data after the halftone processing of the image data CD1, MD1, YD1 on the line head 12 side, and the image data CD2, MD2, YD2 on the line head 13 side. This is based on the data after halftone processing. Then, as shown in FIG. 6, the ink droplets are overlaid on the paper, and the order of the first color overlap and the second color overlap is reversed. Since the first black color and the second black color are mixed at an ink amount ratio corresponding to the ejection amount ratio determined from the black gradation value, the black scale corresponding to the ink amount ratio is mixed. Tones. In the case of the five-color superposition method, a value is selected such that the three colors are changed to five colors and the ink ejection amount of only yellow is more inversely proportional to the number of nozzle rows by color than the other four colors. Is done.

  Thus, as shown in FIG. 7, cyan (C), magenta (M), and yellow (Y) ink droplets 71 are first superimposed on the paper 14 by the line head 12, and the first color superposition is performed. Black is formed. Next, the line head 13 superimposes the ink droplets 72 in the order of yellow (Y), magenta (M), and cyan (C) to form a composite black by the second color superposition. In the first color overlap, since the final layer is yellow, black with a yellowish color is obtained. In the second color overlap, the final layer is cyan, so a bluish black is obtained. Then, by the second color overlap, the yellowish black due to the first color overlap and the bluish black due to the second color overlap are overlapped and mixed in two layers. As a result, a delicate black gradation can be obtained.

  Further, when the ink ejection amount is changed each time, as shown in FIG. 8, first, cyan (C), magenta (M), and yellow (Y) ink droplets 73 are overlapped by the line head 12 to 1 Composite black is formed by the second color overlap. Next, the line head 13 superimposes ink droplets 74 in the order of yellow (Y), magenta (M), and cyan (C) to form a composite black by the second color superposition. For example, if the ink ejection amount ratio of each time is 60:40, the blackish yellowish color by the first color overlap and the bluish black by the second color overlap are the first time. Since the second ink ejection amount ratio is 60:40, it is possible to create a delicate black gradation according to the ink ejection amount ratio between the lower layer and the upper layer. 7 and 8 are diagrams representing the overlap of the ink droplets. Actually, however, the ink droplets are mixed and mixed to some extent at the moment of landing when they are overlapped, and then the ink droplets are moved to the equilibrium state. Then, the color is further mixed by the diffusion proceeding until the solvent (for example, water) in the ink droplet evaporates and the ink is almost solidified. In this case, before the second layer ink droplets overlap, the first layer ink droplets are dried to some extent and the viscosity is increased, and the time from the landing of the second layer ink droplets to drying is the time required for diffusion. Ink mixing is terminated in a non-equilibrium state, for example because it is much shorter than. For this reason, the ink color of the final layer is likely to appear as a color, but by performing the color overlap twice as in this embodiment, the black color of each time is canceled or a new black gradation is created. Or

  In printing other than the black region, a combination of nozzle rows that can select a color order in which the final color is yellow among the nozzle rows 31 and 32 is employed. In the present embodiment, when printing a color other than black, the nozzle row 31 on the line head 12 side is preferentially used, and printing is performed in the color overlapping order in which the final layer is yellow.

As described above, according to the present embodiment, the following effects can be obtained.
(1) The nozzle rows are arranged so that the same color ink droplets can be landed on the same position on the paper 14 by the plurality of line heads 12, 13. Since ink droplets are sequentially ejected and color overlap is repeated twice, a high-intensity black can be created.

  (2) Since the arrangement order of the nozzle rows 31 and 32 in the transport direction is different between the line heads 12 and 13, the color superposition order in which black is developed at each time of color superposition is different. The black color that appears depends on the order of color overlap, so if you do color overlap twice, you will overlap black with different colors twice, canceling the black color, or subtle gradation of black Can be created. For example, even if the color superposition is repeated twice in the same color superposition order, the black color of the color by the single color superposition is repeated, and the color appears remarkably. On the other hand, in this embodiment in which the color superposition order is changed between the first time and the second time, the color by the first color superposition is different from the color by the second color superposition, and different colors of black are mixed. Therefore, the composite effect is improved and a composite black with little change in color is obtained.

  (3) In particular, the nozzle rows 31 and 32 in the line heads 12 and 13 are provided so that the color order is an array order that is line symmetric in the transport direction X. Therefore, the order of color superposition that causes black to appear at each time of color superposition is reversed, so it is possible to superimpose very different blacks of colors, canceling the black color, and creating subtle gradations of black Will increase.

  (4) Further, since the ink ejection amount is changed at each time of color superimposition, it is possible to adjust the overlapping ratio (ink amount ratio) when blacks with different colors expressed by color superposition are superimposed. Therefore, it is possible to effectively realize the cancellation of the black color and to create more gradations of black.

  (5) Analyzing the black gradation value from the CMY image data, obtaining each injection amount ratio according to the analyzed black gradation value with reference to the conversion table BT, and according to the obtained each injection amount ratio The gradation values were divided into two CMY image data, each of which was divided into gradation values. Then, the two CMY image data are allocated to the drive systems of the line heads 12 and 13, respectively, and the overlapping ratio of each color overlap is adjusted. As a result, it is possible to create black with a subtle gradation according to the black gradation in the image data.

  (6) When printing a color other than black, the nozzle row 31 on the line head 12 side is preferentially used, and printing is performed in a color order in which the final color is yellow. For this reason, even if a color misregistration occurs when printing a color other than black, the final color is yellow, so that the color misregistration can be made inconspicuous.

In addition, embodiment is not limited above, You may change as follows.
(Modification 1) The arrangement order of the nozzle rows 31 and 32 is not limited to being line symmetric in the transport direction X. As shown in FIG. 9, the line heads 12 and 13 may be arranged in the same color order. In this example, nozzle rows 31 and 32 are formed on the nozzle forming surfaces 12A and 13A of the line heads 12 and 13 in the color order of “C, LC, M, LM, Y” from the upstream side in the transport direction X. Yes. In this case, in the three-color superposition method, as shown in FIG. 10, cyan (C), magenta (M), and yellow (Y) ink droplets 75 are first superimposed on the paper 14 by the line head 12. A composite black is formed by the first color overlap. Next, the ink droplets 76 are superposed in the order of cyan (C), magenta (M), and yellow (Y) by the line head 13 to form a composite black by the second color superposition. Since the final layer of the color overlap is yellow in both the first time and the second time, black with a yellowish color is obtained, but black is emphasized by the second color overlap, For example, it is possible to avoid the inconvenience that black is light and dark gray.

  (Modification 2) Further, the arrangement order of the nozzle rows 31 and 32 may be an order in which the color orders are opposite to each other in the transport direction X, and there is a configuration in which the nozzle rows are not line symmetric because the intervals between the nozzle rows are different. Can be adopted. Also in this case, since the order of arrangement of the nozzle rows 31 and 32 is the reverse color order, the color order of the two color overlaps is reversed, and the same effect as in the above embodiment can be obtained. Furthermore, paying attention only to the nozzle rows of a plurality of colors used for developing black by color mixing, it is sufficient if the color order is opposite in the transport direction X. For example, although the arrangement order of the five colors is not the reverse color order, it is sufficient if the arrangement order of the three-color nozzle arrays used when black is expressed by color mixture is the reverse color order in the transport direction X. When there are two groups of nozzle rows of three colors, the arrangement order of “YMC / CMY” or “MCY / YCM” can also be adopted. In this case, if a group other than black is printed using a group in which the final color in the color order is yellow among the two groups, even if there is a color shift, it is difficult to stand out.

  (Modification 3) The number of rows of the recording heads arranged in the transport direction is not limited to two rows, and may be three rows, four rows, five rows or more. For example, the same number of times as the number of columns of the recording head may be set as the maximum number of times of color overlap, and the number of times of color overlap that is equal to or less than the maximum number of times may be selected according to the printing conditions at that time. Further, in the configuration including four groups of nozzle rows, the nozzle rows of at least one pair of adjacent recording heads (that is, at least one group) are symmetrical in the color direction of the nozzle rows in the transport direction X (reverse colors). An order of arrangement such as “CMY / YMC / CMY / YMC” or “CMY / CMY / YMC / YMC” can be adopted.

  (Modification 4) In the above-described embodiment, a recording head having five color nozzle rows is used. However, three color nozzle rows are sufficient. In other words, two rows of recording heads having three nozzle rows of cyan, magenta, and yellow may be arranged in the transport direction, and color superposition may be performed a plurality of times. Further, the present invention is not limited to a configuration in which a plurality of rows of recording heads are arranged in the transport direction X. For example, a nozzle for a plurality of colors (including at least three colors of cyan, magenta, and yellow) that has a single recording head and can express black by mixing colors so that the color can be superimposed multiple times on the nozzle formation surface. A configuration in which two or more groups of rows are provided in the paper conveyance direction can also be employed. Furthermore, one fluid ejecting head is provided with only a part of the three-color nozzle rows capable of expressing black by color mixing, and a plurality of nozzle rows capable of expressing black by color mixing are nozzles of a plurality of fluid ejecting heads. A configuration consisting of rows can also be adopted. Further, as ink colors used for color superimposition for expressing black, an appropriate combination can be selected from ink colors of cyan, light cyan, magenta, light magenta, yellow, dark yellow, gray, and light gray. In addition, when performing color overlapping a plurality of times, the combination of ink colors to be superimposed each time may be different. For example, the first time is a color superimposition of cyan, magenta, and yellow, and the second time is a light superimposition of light cyan, light magenta, and dark yellow. Note that the fluid ejecting head may include a black nozzle row.

  (Modification 5) The printer as the fluid ejecting apparatus is not limited to a line printer, and may be applied to, for example, a serial printer in which printing is performed while the recording head moves (scans) in the paper width direction.

  (Modification 6) In the above-described embodiment, the fluid ejecting apparatus is embodied as an ink jet recording apparatus. However, the present invention is not limited to this, and other fluids other than ink (liquid or functional material particles are dispersed or mixed in the liquid). And a fluid ejecting apparatus that ejects or discharges a liquid, a fluid such as a gel, and a solid that can be ejected by flowing as a fluid. For example, a liquid ejecting apparatus that ejects a liquid material that contains materials such as electrode materials and color materials (pixel materials) used in the manufacture of liquid crystal displays, EL (electroluminescence) displays, and surface-emitting displays in a dispersed or dissolved state, It may be a liquid ejecting apparatus that ejects a bio-organic matter used for biochip production, or a liquid ejecting apparatus that ejects a liquid that is used as a precision pipette and serves as a sample. In addition, transparent resin liquids such as UV curable resin to form liquid injection devices that pinpoint lubricant oil onto precision machines such as watches and cameras, and micro hemispherical lenses (optical lenses) used in optical communication elements. A liquid ejecting apparatus that ejects a liquid onto the substrate, a liquid ejecting apparatus that ejects an etching solution such as acid or alkali to etch the substrate, and a fluid ejecting apparatus that ejects a fluid such as a gel (for example, a physical gel) Further, it may be a granular material ejecting apparatus (for example, a toner jet recording apparatus) that ejects a solid such as a powder (a granular material) such as toner. Also in these, for example, the present invention can be applied at the time of use in an application in which three kinds of fluids colored cyan, magenta, and yellow are mixed on the target to develop black. In the present specification, the term “fluid” is a concept that does not include a fluid consisting only of gas. Examples of the fluid include liquid (inorganic solvent, organic solvent, solution, liquid resin, liquid metal (metal melt), etc. ), Liquids, fluids, powders (including granules and powders), and the like.

The technical idea grasped from the embodiment and the modification will be described below.
(1) In the fluid ejecting apparatus according to any one of Claims 1 to 6, when the control unit causes a color other than black to be developed on the target, among the nozzle groups of the two or more groups, A fluid ejecting apparatus, wherein a group of nozzle rows in which the last nozzle row in the target transport direction is in the color order of the lightest color among the plurality of colors is selected. According to this, color misregistration when printing a color other than black is hardly noticeable.

1 is a perspective view of a printer according to an embodiment. The model bottom view of a line head. FIG. 2 is a block diagram illustrating an electrical configuration of the printer. FIG. 3 is a circuit diagram showing a print control circuit in a head driver. 6 is a flowchart showing a black printing processing routine. Explanatory drawing of the process which determines the ink ejection amount in each time of color superimposition at the time of black printing. The schematic side view which shows the mode of the color overlap at the time of black printing. FIG. 6 is a schematic side view showing a state of color superposition when the ink ejection amount is adjusted each time. The model bottom view of the line head in a modification. The schematic side view which shows the mode of the color superposition at the time of the black printing in a modification.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Printer as fluid ejecting apparatus, 12, 13 ... Line head as fluid ejecting head, 12A, 13A ... Nozzle forming surface, 15 ... Platen, 14 ... Paper as target (medium), 16 ... Cap, 17 ... Maintenance Apparatus, 31, 32 ... Nozzle row, 31C, 31LC, 31M, 31LM, 31Y ... Nozzle row constituting a group of nozzle rows, 32Y, 32LM, 32M, 32LC, 32C ... Nozzle row constituting a group of nozzle rows, 33 DESCRIPTION OF SYMBOLS Nozzle, 20 ... Paper guide, 24 ... Paper feed roller, 25 ... Paper feed motor, 26 ... Conveyor, 28 ... Conveyor motor, 40 ... Controller as control means, 51 ... CPU which comprises a control means.

Claims (7)

A fluid ejecting apparatus including a fluid ejecting head capable of ejecting a fluid to a target,
At least one fluid ejecting head in which a plurality of nozzle rows capable of ejecting a plurality of colors of fluid capable of expressing black by color mixing are provided in two or more groups in the target transport direction;
Control means for controlling the at least one fluid ejecting head,
When the control means performs color superposition for sequentially ejecting the plurality of colors of fluid to the target position on the target to develop black, the plurality of colors of fluid are sequentially ejected from the two or more nozzle rows. The fluid ejecting apparatus according to claim 1, wherein the fluid ejecting head is controlled so that color superimposition is performed twice for a group of the nozzle rows, and the color superimposition is performed twice or more in total. A plurality of the fluid ejecting heads are arranged in the target conveying direction, and each of the fluid ejecting heads includes the plurality of nozzle rows arranged in an arrangement order capable of sequentially ejecting a plurality of colors of fluid in the target conveying direction. A group of nozzle rows is provided for each ejection head, and the control means develops black for each of the fluid ejection heads when black is produced by performing color superposition for ejecting the plurality of colors of fluid onto the target. The fluid ejecting apparatus according to claim 1, wherein the plurality of fluid ejecting heads are controlled so that the color superposition is performed once and the color superposition is performed twice or more in total. At least one group of the two or more groups has a different arrangement order in the target transport direction between a plurality of nozzle rows belonging to one group and the nozzle rows belonging to the other group. The fluid ejecting apparatus according to claim 1, wherein: 4. The fluid ejecting apparatus according to claim 3, wherein two groups of nozzle rows adjacent to each other in the target transport direction among the two or more groups are provided in a reverse color order in the target transport direction. 5. 5. The fluid ejecting apparatus according to claim 1, wherein the control unit controls the fluid ejecting head so as to change a fluid ejecting amount ejected by color superposition each time. The said control means adjusts the fluid ejection amount of each time ejected for the said color superimposition according to the black gradation value obtained by analyzing the fluid ejection processing data. The fluid ejecting apparatus according to 1. A fluid ejection control method in a fluid ejection apparatus including a fluid ejection head capable of ejecting a fluid to a target,
At least one of the fluid ejecting heads is provided, and two or more groups of nozzles capable of ejecting a plurality of colors of fluid capable of expressing black in all of the fluid ejecting heads are provided.
In the case of expressing black by performing color superposition to inject the fluids of the plurality of colors onto the target,
A step of sequentially injecting a plurality of colors of fluid from a nozzle row of one of the two or more groups and performing color superposition once on a target;
A step of sequentially ejecting a plurality of colors of fluid from the nozzle row of the other one of the two or more groups and further performing color superposition once on the color superposed fluid;
A fluid ejection control method for a fluid ejection apparatus, comprising:

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