JP2005297489A - Printer, computer program, printing system, printing method and printing pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a printer capable of printing pictures with suitable density which are printed at ink-discharging parts formed at a plurality of printing heads. <P>SOLUTION: The printer is equipped with at least two groups of the ink-discharging parts which have a plurality of the ink-discharging parts for discharging inks of a plurality of colors, and discharges the ink from the each ink-discharging part to an area assigned to the each ink-discharging part. For the printer capable of printing one picture with the at least two ink-discharging part groups, the inks are discharged from the a plurality of ink-discharging parts to the areas assigned to the ink-discharging parts, thereby the picture is printed based on the density of the designated printing pattern printed for each ink-discharging part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printing apparatus having a plurality of ink ejection units, a computer program, a printing system, a printing method, and a printing pattern.

As a printing apparatus having a plurality of ink ejection units, for example, an ink jet printer having a plurality of nozzle arrays is known (see, for example, Patent Document 1). In such an ink jet printer, ink is ejected from a plurality of nozzle arrays to print one image. In other words, the color of the printed image changes depending on the size and amount ratio of the ink ejected from each nozzle. Therefore, calibration is performed to optimize the amount and size of ink ejected from each nozzle row.
JP 2000-4368 A

  In recent years, inkjet printers have been developed that have at least two print heads with multiple nozzle arrays for ejecting multiple colors of ink for each color, and can print one image by ejecting ink from each nozzle array. Has been. In such a printer, a nozzle row for ejecting the same color ink is provided for each print head. For this reason, it is necessary to calibrate the amount and size of ink ejected from nozzle rows provided in different print heads. In particular, if there is a variation in the amount or size of ink ejected from nozzle arrays that eject ink of the same color from different print heads, the image may be uneven and the image quality may be reduced.

  The present invention has been made in view of such a problem, and a printing apparatus, a computer program, a printing system, and the like capable of printing an image printed by an ink discharge unit provided in a plurality of print heads at an appropriate density, It is an object to provide a printing method and a printing pattern.

  The main invention includes at least two ink ejection unit groups having a plurality of ink ejection units for ejecting a plurality of colors of ink for each color, and each ink ejection unit is arranged in an area allocated to each of the ink ejection units. In a printing apparatus capable of ejecting ink from a portion and printing one image with the at least two ink ejecting portion groups, from the plurality of ink ejecting portions to areas allocated to the respective ink ejecting portions, A printing apparatus that prints the image based on a density of a predetermined print pattern that is ejected and printed for each of the ink ejection portions.

  Other features of the present invention will be clarified by the description of the present specification and the accompanying drawings.

  At least the following will be made clear by the description of the present specification and the accompanying drawings.

It includes at least two ink ejection unit groups having a plurality of ink ejection units for ejecting a plurality of colors of ink for each color, and ink is supplied from each ink ejection unit to the area allocated to each of the ink ejection units. In the printing apparatus capable of ejecting and printing one image with the at least two ink ejecting unit groups, ink is ejected from the plurality of ink ejecting units to an area allocated to each of the ink ejecting units. The printing apparatus is characterized in that the image is printed based on a density of a predetermined print pattern printed for each ink discharge unit.
According to such a printing apparatus, ink is ejected to a region allocated to each ink ejection unit, and an image is printed based on a print pattern printed for each ink ejection unit. In other words, the print pattern is printed by actually ejecting ink from each ink ejection unit to a region where ink is ejected when printing an image. Since the image is printed based on the density of the print pattern formed by ejecting ink in the same region as when the image is actually printed, the image can be printed with a more appropriate density.

In such a printing apparatus, image data for printing the image is converted based on the density of the predetermined print pattern so that a difference between the density of the predetermined print pattern and a reference density is small. It is desirable to print based on the converted image data.
According to such a printing apparatus, an image is printed based on image data converted so that a difference between a density of a predetermined print pattern and a reference density becomes small. It is possible to print at a density almost equal to the density.

In such a printing apparatus, it is preferable that the printing pattern is printed with ink of any one of the plurality of colors.
According to such a printing apparatus, since the print pattern is not printed with ink of all colors, the time for printing the print pattern is reduced, and it is possible to print an image with a good density in a short time. .

In such a printing apparatus, it is preferable that the ink of any one of the colors is a light color ink among the plurality of colors of ink.
In particular, the density of a halftone portion of an image printed mainly with light-colored ink tends to vary. For this reason, as in the above-described printing apparatus, when printing an image, a print pattern to be compared with a reference density is printed with light-colored ink, thereby suppressing density variation at least in a halftone portion. It is possible to print a better image. Further, it is possible to improve the graininess that is easily deteriorated in the halftone portion. Here, the light color ink includes, for example, light cyan ink, light magenta ink, yellow ink, and the like.

In such a printing apparatus, it is preferable that the plurality of ink ejection units can form a plurality of types of dots having different sizes, and the print pattern is printed using the plurality of types of dots.
Since an image to be printed is composed of dots of a plurality of sizes, a print pattern is printed with a plurality of types of dots, and an image is printed based on the density of each print pattern. It is possible to print.

In this printing apparatus, it is preferable that the printer has a density measuring unit capable of measuring the density of the predetermined print pattern, and the density of the predetermined print pattern is measured by the density measuring unit.
According to such a printing apparatus, since the density of the actually printed print pattern is measured by the density measuring unit, it is possible to detect a more accurate density and print an image with a more appropriate density. It is possible. Further, it is possible to measure the density of the printing pattern without removing the medium on which the printing pattern is printed from the printing apparatus that has printed the printing pattern.

In such a printing apparatus, it is preferable that the reference density is a density of a reference print pattern measured by the density measuring unit.
According to such a printing apparatus, the reference density is also measured by the same density measurement unit as the print pattern printed by ejecting ink from each ink ejection unit, so measurement based on sensitivity variations of the density measurement unit, etc. Since no error occurs, the difference between the density of the predetermined print pattern and the reference density can be reduced with higher accuracy.

In such a printing apparatus, it is preferable that the density measurement unit is provided integrally with the at least two ink ejection unit groups.
According to such a printing apparatus, since the relative position between the ink ejection unit and the density measurement unit does not change, the density measurement device position and the print pattern position are recognized, and the density is measured at an appropriate position. Is possible.

In such a printing apparatus, it is preferable that the print pattern is printed on a medium conveyed in a predetermined direction, and the density measurement unit is provided on the downstream side of the predetermined direction with respect to the ink ejection unit group.
According to such a printing apparatus, after the printing pattern is printed, the density can be measured by the density measuring unit without transporting the medium on which the printing pattern is printed in the reverse direction. For this reason, the process at the time of printing a printing pattern and measuring a density | concentration is easy, and it can perform efficiently in a short time.

In such a printing apparatus, the density of the predetermined print pattern may be measured by a density measuring device provided outside.
According to such a printing apparatus, it is possible to realize a printing apparatus capable of printing an image with an appropriate density without providing a density measuring unit in the printing apparatus.

In such a printing apparatus, the reference density may be a density of a reference print pattern measured by the density measuring device.
According to such a printing apparatus, the reference density is also measured by the density measuring device in the same manner as the print pattern formed by the ink ejected from each ink ejection unit. For this reason, it is possible to reduce the difference between the density of the predetermined print pattern and the reference density without providing a density measuring unit in the printing apparatus.

The printing apparatus includes a signal generation unit that generates a drive signal for driving each of the ink ejection unit groups, and a temperature sensor for detecting a temperature, and includes the density of the predetermined print pattern and the reference Characteristic information indicating the characteristics of the ink ejection unit group is obtained based on the density of the ink ejection unit group, and the signal generation unit is configured for each ink ejection unit group based on the characteristic information and the output of the temperature sensor. It is desirable to generate the drive signal.
According to such a printing apparatus, it is possible to generate a drive signal corresponding to each characteristic for each ink ejection unit based on the temperature detected by the temperature sensor and the characteristic information of the ink ejection unit. For this reason, it is possible to suppress the discharge of different amounts of ink from the ink discharge portion due to the difference in temperature, and to stably discharge ink without being affected by the temperature, thereby forming the ink discharged from each ink discharge portion. It is possible to suppress the occurrence of a density difference in the printed image and print a good image.

  In such a printing apparatus, based on the density of the predetermined print pattern and the reference density, characteristic information indicating characteristics of the ink ejection unit group is obtained, and a plurality of predetermined ink ejection units having different characteristic information from each other And density correspondence information for associating the density of each printed image with the reference density for each color of the ink, and storing the density for each ink ejection unit that prints image data to be printed A plurality of storage areas, and based on the characteristic information and the density correspondence information corresponding to the color of ink to be ejected, the density of an image printed by the plurality of ink ejection units, and the reference The image data is converted for each of the stored storage areas so that the difference from the density becomes smaller, and the plurality of inputs are converted based on the converted image data. It is desirable to eject ink from the ejection portion.

  The printing apparatus includes a plurality of ink ejection unit groups, and each ink ejection unit group includes a plurality of ink ejection units for ejecting a plurality of colors of ink for each color. For this reason, it is desirable to uniformly match the density of images printed by a plurality of ink ejection units that eject the same color ink. The printing apparatus associates each ink ejection unit with a predetermined ink ejection unit based on ejection amount information based on the density of the predetermined print pattern printed by each ink ejection unit and a reference density. Then, the density of the print pattern printed by the ink ejection unit and the reference density are associated with each other by the density correspondence information. For this reason, even in an ink discharge section that discharges the same color ink that each of the plurality of ink discharge section groups has, the image printed by each ink discharge section is based on the discharge amount information and the density correspondence information. It is possible to easily convert the image data so that the difference between the density and the reference density becomes small. In particular, the image data is stored in a separate storage area for each of the ink ejection units to be printed, and is converted in a batch for each stored storage area, so that the conversion process is easy. Also, at the stage of generating print data from image data, conversion is performed for each storage area stored at once, that is, conversion processing is not executed in parallel with the printing operation, so conversion processing is executed in a short time It is possible to increase the throughput.

  In this printing apparatus, the image forming apparatus includes a conversion unit that converts a gradation value of image data to be printed for each pixel based on the density of the predetermined print pattern and the reference density, and the predetermined print pattern A density that, when printed, correlates the density of an image printed by using a plurality of predetermined ink ejection units having different densities of the predetermined print pattern to the reference density for each color of the ink. Predetermined ink ejection unit that has correspondence information and prints the predetermined print pattern having a density corresponding to an average value of the density of the predetermined print pattern printed by the plurality of ink ejection units in the density correspondence information. The plurality of ink discharges based on the gradation values converted by the converter based on the correspondence between the density of the image printed using the reference density and the reference density It is desirable to eject ink from the parts.

  The density correspondence information possessed by the printing apparatus includes, for each color of ink ejected from each ink ejection unit, associating the density of an image printed using a plurality of predetermined ink ejection units with the reference density. Yes. In addition, since the density of the print patterns formed by the plurality of predetermined ink discharge units is different from each other, the average of the density of the print patterns printed by the plurality of ink discharge units provided in the printing apparatus is used as one of the predetermined ink discharge units. It is possible to make it correspond as a default ink ejection unit that prints at a density corresponding to the value. Therefore, in the density correspondence information, the density of the image printed using the default ink ejection unit that prints at a density corresponding to the average value of the density of the print pattern printed by the plurality of ink ejection units, and the reference amount By converting the gradation value based on the corresponding relationship with the density, it is possible to suppress variations in the density of the image printed with the ink ejected from each ink ejection unit.

Also, it has at least two ink ejection unit groups having a plurality of ink ejection units for ejecting a plurality of colors of ink for each color, and the plurality of ink ejection units can form a plurality of types of dots having different sizes. In the printing apparatus capable of ejecting ink from each of the ink ejection units to the area allocated to each of the ink ejection units, and printing one image with the at least two ink ejection unit groups, A plurality of inks having a density measuring unit that is integrated with at least two ink ejection unit groups and is provided downstream of the ink ejection unit group in the predetermined direction and capable of measuring the density of a predetermined print pattern. Ink is discharged from the discharge portion to the area allocated to each of the ink discharge portions, and the predetermined printing is performed with the plurality of types of dots for each of the ink discharge portions. The turn is printed on a medium transported in a predetermined direction, and the density of the predetermined print pattern printed by the density measuring unit and the reference print pattern measured by the density measuring unit are measured. In this printing apparatus, the image data for printing the image is converted so that the difference from the density of the image becomes small, and printing is performed based on the converted image data.
According to such a printing apparatus, since all the effects described above are exhibited, the object of the present invention is achieved most effectively.

  In addition, at least two ink ejection unit groups having a plurality of ink ejection units for ejecting a plurality of colors of ink for each color are provided, and each ink ejection unit has a region allocated to each of the ink ejection units. Ink is ejected from the plurality of ink ejecting units to the area allocated to each of the ink ejecting units on a printing apparatus capable of printing one image with the at least two ink ejecting unit groups. In addition, a computer program for realizing the function of printing the image based on the density of a predetermined print pattern printed for each ink ejection unit can be realized.

  A computer main body; and at least two ink discharge unit groups that are connected to the computer main body and have a plurality of ink discharge units for discharging a plurality of colors of ink for each color, and assigned to each of the ink discharge units In a printing system having a printing apparatus that discharges ink from each of the ink discharge portions to a given area and prints one image with the at least two ink discharge portion groups, the plurality of ink discharge portions Also, a printing system is characterized in that the image is printed based on the density of a predetermined print pattern printed on each of the ink ejecting units by ejecting ink to an area allocated to each of the ink ejecting units. It is feasible.

  Further, by using at least two ink ejection unit groups having a plurality of ink ejection units for ejecting a plurality of colors of ink for each color, the ink is ejected to an area allocated to each of the ink ejection units, Ejecting ink from the plurality of ink ejection units capable of printing one image to an area allocated to each of the ink ejection units, and printing a predetermined print pattern for each of the ink ejection units; and printing And a step of printing the image on the basis of the density of the predetermined print pattern, which can be realized.

  In addition, printing is performed by a plurality of ink ejecting units capable of ejecting a plurality of colors of ink provided in at least two ink ejecting unit groups for each color and ejecting the ink to the assigned area to print one image. In the density adjustment printing pattern, the ink is ejected from the plurality of ink ejection sections to the area allocated to each of the ink ejection sections, and printing is performed for each of the ink ejection sections. Printing patterns are also feasible.

=== Overall Configuration of Printing Apparatus ===
FIG. 1 is a perspective view showing an outline of the configuration of an inkjet printer as a printing apparatus according to the present invention, FIG. 2 is an explanatory diagram showing an outline of the configuration of a printing unit included in the inkjet printer, and FIG. It is sectional drawing for doing.

  An ink jet printer (hereinafter referred to as a printer) 20 as a printing apparatus according to the present invention is a printer corresponding to a relatively large printing paper P such as JIS standard A row 0 paper, B row 0 paper, or roll paper. is there. The printer 20 is roughly classified into a printing unit 22 that discharges ink and prints on a printing paper P as a medium, and a printing paper transport unit 21 that transports the printing paper P. Each part will be described below.

=== Print section ===
The printing unit 22 includes a carriage 30 that holds a plurality of print heads 28 serving as an ink ejection unit group, and the carriage 30 is a direction that is substantially orthogonal to the conveyance direction of the printing paper P (hereinafter also referred to as a carriage movement direction or a horizontal direction). ), A pair of upper and lower guide rails 11 for reciprocally guiding, a carriage motor 12 for reciprocating the carriage 30, and a driving belt for transmitting the power of the carriage motor 12 to reciprocate the carriage 30. 13.

  Two guide rails 11 are provided along the carriage movement direction, and are vertically arranged at intervals in the conveyance direction. The guide rails 11 are supported by frames (not shown) serving as bases on both left and right ends. Yes. At this time, in the two guide rails 11, the lower guide rail 11b is disposed in front of the upper guide rail 11a. For this reason, the carriage 30 arranged so as to be bridged between the two guide rails 11a and 11b moves in an inclined state so that the upper part is located rearward.

  The drive belt 13 is a metal belt-like body, and is provided at two intermediate positions between the upper and lower guide rails 11a and 11b with two pulleys 44a and 44b arranged at an interval substantially equal to the length of the guide rails 11a and 11b. It is laid over. One of the pulleys 44 a and 44 b is fixed to the shaft of the carriage motor 12. The drive belt 13 is fixed to the left end edge and the right end edge of the carriage 30, respectively.

  The carriage 30 is provided with 20 print heads 28 for ejecting a plurality of colors of ink. Each print head 28 has a nozzle row as an ink ejection unit in which a plurality of nozzles n that eject ink of the same color are arranged in a row, and is controlled by a drive control unit 330 (see FIG. 6), which will be described later. Ink is ejected from the nozzle n. The arrangement of the print head 28 and the nozzles n will be described later. In addition, a plurality of sub-tanks 3 that temporarily store the ink ejected by each print head 28 are mounted on the 20 print heads 28 mounted on the carriage 30. A main tank 9 for supplying ink to the sub tank 3 is provided outside the movement range of the carriage 30 in the carriage movement direction. In addition, the carriage 30 is provided with a reflective optical sensor 31 for detecting the position of the leading edge of the printing paper, the paper width, and the like on the side facing the printing paper. The reflective optical sensor 31 is also used as a density measuring unit for measuring the density of a printed pattern or the like.

  Further, the carriage 30 includes two-stage sub tank plates 30A and 30B as shown in FIG. A plurality of sub tanks 3 are mounted on the sub tank plates 30A and 30B, respectively. Each sub tank 3 is connected to each print head 28 via a valve 4. The sub tank 3 is connected to the main tank 9 by an ink supply path 14 (FIG. 2). The main tank 9 contains six types of inks of black K, cyan C, light cyan LC, magenta M, light magenta LM, and yellow Y discharged from the print head 28. The temperature sensors 29a, 29b,... 29e will be described later.

  In this embodiment, sub-tanks 3a to 3f for six colors of black K, cyan C, light cyan LC, magenta M, light magenta LM, and yellow Y are provided. These six sub tanks 3a to 3f are connected to the corresponding six main tanks 9a to 9f, respectively. However, the inks that can be used are not limited to six colors, but four color inks (for example, black K, cyan C, magenta M, yellow Y) and seven color inks (for example, black K, light black LK, cyan C). , Light cyan LC, magenta M, light magenta LM, yellow Y), and the like.

  In the printer 20, the carriage 30 is pulled by the drive belt 13 driven by the carriage motor 12 and moves along the guide rail 11 in the carriage movement direction. From the 20 print heads 28 provided in the carriage 30, ink is supplied. Is printed on the printing paper P transported by the printing paper transport unit 21.

=== Arrangement of nozzles and print heads ===
FIG. 4 is a diagram for explaining the arrangement of nozzles on the lower surface of one print head 28. On the lower surface of the print head 28, a nozzle row in which 48 nozzles are arranged in a row in the transport direction of the printing paper P is provided for each ink color to be ejected. The nozzle rows for each ink color, that is, the black nozzle row K, the dark cyan nozzle row C, the light cyan nozzle row LC, the dark magenta nozzle row M, the light magenta nozzle row LM, and the yellow nozzle row Y are arranged in a direction along the guide rail 11. They are arranged side by side at intervals. Each nozzle is provided with a piezo element PE (FIG. 7) as a drive element for ejecting ink from each nozzle.

  FIG. 5 is a view of the carriage 30 as seen from the direction of the arrow A (FIG. 3). Naturally, the left-right direction shown in FIG. 5 is opposite to the left-right direction shown in FIG. The carriage 30 includes a print head group 27 including 20 print heads 28a, 28b,. The 20 print heads 28 are arranged in four rows along the carriage movement direction in which five print head rows are arranged along the conveyance direction of the printing paper P and spaced from each other by five.

  The positions of the nozzles of the print heads 28a, 28b,..., 28t are arranged so as not to coincide with each other in the conveyance direction of the printing paper. For example, as shown in FIG. 5, in the four print heads 28a, 28f, 28k, and 28p located at the uppermost position of each row, the print head 28a located on the rightmost side in FIG. The topmost print head 28k in the row is positioned second from the top, the topmost print head 28f in the second column from the right is third from the top, and the topmost print in the leftmost column is printed. The head 28p is positioned fourth from the top. The distance in the transport direction between the 48th nozzle of the print head 28a located on the uppermost side and the 1st nozzle of the print head 28k located second from the top coincides with the nozzle pitch k · D in each nozzle row. Are arranged to be. Hereinafter, the distances in the transport direction of the second print head 28k and the third print head 28f from the upper side, and the third print head 28f and the fourth print head 28p so as to coincide with the nozzle pitch k · D. Is arranged. Furthermore, the four print heads 28 arranged at the same vertical position in each print head row are also arranged in the same manner as the four print heads 28 located at the uppermost position. Accordingly, the first nozzle of the print head 28a located at the top of the rightmost row to the 48th nozzle of the print head 28t located at the bottom of the leftmost row are arranged at equal pitches in the transport direction. It will be. Hereinafter, if necessary, the uppermost print head 28a is referred to as a first print head, hereinafter 28b in FIG. 5 is referred to as a second print head, 28c is referred to as a third print head,. .

  Temperature sensors 29a, 29b, 29c, 29d, and 29e are attached to the print heads 28a, 28b, 28c, 28d, and 28e of the print head row located at the rightmost position in the print head group 27, respectively. The temperature sensors 29a, 29b, 29c, 29d, and 29e are mounted only on the print heads 28a, 28b, 28c, 28d, and 28e arranged in the transport direction because the temperature change in the transport direction is large and the temperature change in the carriage movement direction. Is expected to be small enough to be ignored. The reason why the temperature change and difference in the sub-scanning direction are expected to increase is as shown in FIG. 3, because the air warmed by the driving print head tends to accumulate upward, so that the print head 28a is connected to the print head 28e. It is because it becomes hotter than it is. The reason why the temperature change in the carriage movement direction is expected to be small is that the carriage 30 continuously reciprocates in the carriage movement direction at high speed during printing. Note that “the temperature change is small enough to be ignored” means that the temperature change is small enough to hardly affect the ink ejection amount.

  A reflection type optical sensor 31 is provided on the upper side of the carriage 30. The reflection type optical sensor 31 is disposed on the downstream side with respect to the print head group 27 in the transport direction in which paper or the like is transported during printing.

=== Printing paper transport unit ===
A printing paper transport unit 21 for transporting the printing paper P is provided on the back side of the two guide rails 11. The printing paper transport unit 21 transports the printing paper P below the lower guide rail 11b and the paper holding unit 15 that rotatably holds the printing paper P above the upper guide rail 11a. A sheet transport holder 16 and a platen 17 along which the print sheet P transported between the sheet holding unit 15 and the sheet transport holder 16 are arranged.

The platen 17 has a flat surface over the entire width of the printing paper P to be conveyed. This plane functions as a support surface that supports the printing paper P conveyed in the conveyance direction along the same direction.
The paper holding unit 15 includes a holder 15a that holds the printing paper P rotatably. The holder 15a has a shaft body 15b that serves as a rotation shaft in a state where the printing paper P is held, and the both ends of the shaft body 15b are for preventing meandering and skewing of the printing paper P to be supplied. Guide disks 15c are provided respectively.
The paper transport holder 16 rotates a transport roller 16a for transporting the print paper P, a clamping roller 16b that is disposed opposite to the transport roller 16a and sandwiches the print paper P between the transport roller 16a, and a transport roller 16a. And a conveyance motor 18 for causing the movement to occur. The shaft of the transport motor 18 is provided with a drive gear 18a, and the shaft of the transport roller 16a is provided with a relay gear 18b that meshes with the drive gear 18a. The power of the transport motor 18 is provided via the drive gear 18a and the relay gear 18b. It is transmitted to the conveyance roller 16a. That is, the printing paper P held by the holder 15a is sandwiched between the transport roller 16a and the sandwiching roller 16b, and is transported along the platen 17 by the transport motor 18.

=== Control Unit of Printer ===
FIG. 6 is a block diagram showing the electrical configuration of the printer.
The printer 20 receives image data input from a single main control unit 310, a plurality of data processing units 320 corresponding to the plurality of print heads 28 on the carriage 30, and a computer connected to the printer 20. An image processing unit 350 that converts print data into print data, a CR motor drive driver 105 for driving the carriage motor 12, a transport motor drive driver 106 for driving the transport motor 18, and the like are provided. Each print head 28 is unitized with the corresponding drive control unit 330 in the carriage 30. The printer 20 is provided with a data processing unit 320 corresponding to each drive control unit 330, and the drive control unit 330 and the corresponding data processing unit 320 are connected by a single flexible cable 340.

  The main control unit 310 is a control circuit that controls the entire printer, and indicates the density of the print pattern printed by the ink ejected from each nozzle row of each print head 28 as a deviation from the reference density. The characteristic information is configured to be accessible to the memory 401 as a storage unit. The characteristic information will be described later.

The data processing unit 320 is a control circuit for performing bidirectional communication between the printer 20 and the carriage 30. The drive control unit 330 is a control circuit that performs control for causing the print head 28 to eject ink as described above, and performs bidirectional communication with the data processing unit 320.
The data processing unit 320 includes a control circuit 400, a differential driver 410, an SRAM 420, and an interface 430.
The drive control unit 330 includes a control circuit 500, a differential driver 510, an SRAM 520, an interface 530, and an original drive signal generation unit 540. The control circuit 500 includes a PTS pulse generation circuit 502 and a mask signal generation circuit 504.
The control circuit 400 and the differential driver 410 constitute a transmission / reception unit (data processing unit) on the main body side. The control circuit 500 and the differential driver 510 constitute a transmission / reception unit (drive control unit) on the carriage side. The PTS pulse generation circuit 502, the mask signal generation circuit 504, and the original drive signal generation unit 540 constitute a head drive control unit.

  A flexible cable 340 connected between the interfaces 430 and 530 transmits a clock signal line for transmitting the clock signal SCLK, a flag signal line pair for transmitting the flag signal FLG, and serially transmitting data DATA. A serial signal line pair. Note that in this specification, the same reference numerals are used as the reference numerals indicating signals and the signal lines (or signal line pairs).

  The image processing unit 350 includes a resolution conversion processing unit 351, a color conversion processing unit 352, a halftone processing unit 353, a rasterization processing unit 354, a raster row conversion processing unit 355, and a plurality of color conversion data tables LUT. doing.

  The resolution conversion processing unit 351 plays a role of converting the resolution of the input image data into print resolution. The resolution-converted image data is still image information composed of three color components of RGB. The color conversion processing unit 352 converts the RGB image data for each pixel into multi-tone data of a plurality of ink colors that can be used by the printer 20 while referring to the color conversion data table LUT. Further, the color conversion processing unit 352 has a density of an image formed by ink ejected from each nozzle row by the same print data in nozzle rows provided in mutually different print heads 28 and ejecting the same color ink. A color calibration process for reducing the difference is executed. The color calibration process will be described later.

  The multi-gradation data subjected to the color calibration process has, for example, 256 gradation values. The halftone processing unit 353 performs so-called halftone processing such as a dither method to generate binary image data in which a halftone image is expressed by binary data. The binary image data is rearranged in the order of data to be transferred to the printer 20 by the rasterization processing unit 354 and the raster row conversion processing unit 355, and is output as final print data PD. The print data PD includes raster data indicating the dot formation state during each movement of the carriage 30 and data indicating the paper conveyance amount.

=== Drive of print head ===
Next, driving of the print head 28 will be described with reference to FIG.
FIG. 7 is a block diagram showing the configuration of the drive signal generation unit provided in the drive control unit (FIG. 6). FIG. 8 shows the original drive signal ODRV and the print signal PRT ( i) is a timing chart of the drive signal DRV (i).
In FIG. 7, the drive control unit 330 includes a plurality of mask signal generation circuits 504, an original drive signal generation unit 540, and a drive signal correction unit 505. The mask signal generation circuit 504 is provided corresponding to a plurality of piezo elements for driving the nozzles n1 to n48 of the print head 28, respectively. In FIG. 7, the number in parentheses at the end of each signal name indicates the number of the nozzle to which the signal is supplied.

  The original drive signal generation unit 540 generates an original drive signal ODRV used in common for the nozzles n1 to n48. The original drive signal ODRV is a signal that includes two pulses of a first pulse W1 and a second pulse W2 within a carriage movement period for one pixel, and is a reference discharge signal for discharging ink from each nozzle. . That is, all the nozzles of each print head 28 eject ink based on the same original drive signal ODRV. Then, when it is detected by the output of the linear encoder or the like that the carriage 30 has reached a predetermined position, the output of the original drive signal ODRV is started. Therefore, when ink is ejected from each nozzle row of each print head 28 to form dot rows as liquid droplet trace rows at the same target position on the printing paper, the positions of these dot rows in the carriage movement direction match. Thus, the output timing of the original drive signal ODRV is adjusted.

  As shown in FIG. 7, the input serial print signal PRT (i) is input to the mask signal generation circuit 504 together with the original drive signal ODRV output from the original drive signal generation unit 540. The serial print signal PRT (i) is a 2-bit serial signal per pixel, and each bit corresponds to the first pulse W1 and the second pulse W2. The mask signal generation circuit 504 is a gate for masking the original drive signal ODRV in accordance with the level of the serial print signal PRT (i). That is, when the serial print signal PRT (i) is 1 level, the mask signal generation circuit 504 passes the corresponding pulse of the original drive signal ODRV as it is and supplies it to the piezo element as the drive signal DRV, while the serial print signal PRT When (i) is 0 level, the corresponding pulse of the original drive signal ODRV is cut off.

  As shown in FIG. 8, the original drive signal ODRV sequentially generates a first pulse W1 and a second pulse W2 in each pixel section T1, T2, and T3. The pixel section has the same meaning as the carriage movement period for one pixel.

  As shown in FIG. 8, when the print signal PRT (i) corresponds to 2-bit pixel data “1, 0”, only the first pulse W1 is output in the first half of one pixel section. Thereby, a small ink droplet is discharged from a nozzle and a small dot (small dot) is formed in a to-be-printed body. When the print signal PRT (i) corresponds to the 2-bit pixel data “0, 1”, only the second pulse W2 is output in the second half of one pixel interval. As a result, medium-sized ink droplets are ejected from the nozzles, and medium-sized dots (medium dots) are formed on the printing medium. When the print signal PRT (i) corresponds to 2-bit pixel data “1, 1”, the first pulse W1 and the second pulse W2 are output in one pixel section. Thereby, a large ink droplet is ejected from the nozzle, and a large dot (large dot) is formed on the printing medium. As described above, the drive signal DRV (i) in one pixel section is shaped to have three different waveforms according to three different values of the print signal PRT (i), and based on these signals. The print head 28 can form dots of three types.

=== Configuration Example of Reflective Optical Sensor ===
FIG. 9 is a schematic diagram for explaining an example of the reflective optical sensor 31. The reflective optical sensor 31 includes a light emitting unit 38 configured by, for example, a light emitting diode, and a regular reflection light receiving unit 40 and a diffuse reflection light receiving unit 41 configured by, for example, a phototransistor.

  The reflection type optical sensor 31 is set so that light emitted from the light emitting unit 38 emits light at a predetermined angle with respect to, for example, printing paper as a medium. It is disposed at a position where a regular reflection component of the reflected light irradiated on the sheet is mainly incident. The diffuse reflection light receiving unit 41 is disposed vertically above the intermediate position between the light emitting unit 38 and the regular reflection light receiving unit 40, that is, the irradiation position of the printing paper P. The light emitting unit 38 and the regular reflection light receiving unit 40 and the diffuse reflection light receiving unit 41 are arranged side by side in the transport direction. The incident light received by the regular reflection light receiving unit 40 and the diffuse reflection light receiving unit 41 is converted into an electrical signal, and as an output value of the reflective optical sensor 31 according to the amount of the received reflected light, The magnitude of the electrical signal is measured. At this time, the light reflected by glossy paper or the like has a large output from the regular reflection light receiving unit 40, and the light reflected by plain paper or the like has a large output from the diffuse reflection light receiving unit 41 to determine the paper type. It is possible. The reflection type optical sensor 31 includes outputs of the light receiving units 40 and 41 when the light emitted from the light emitting unit 38 is reflected by the paper, and outputs of the light receiving units 40 and 41 when the light is reflected by the platen 17. The leading edge position of the paper and the paper width are detected based on the difference. Further, the reflection type optical sensor 31 outputs the light from the light receiving units 40 and 41 when the light emitted from the light emitting unit 38 is reflected at a portion where the paper is not printed, and when the light is reflected at the printed portion. Based on the outputs of the light receiving units 40 and 41, the density of the printed part can be measured. That is, when the density is high, the amount of ink ejected in the predetermined region is large, so that the area occupied by the dots formed by the ejected ink increases. For this reason, since the blank paper portion without dots becomes small, the output of the light receiving units 40 and 41 by reflected light becomes low. On the other hand, when the density is low, the amount of ink ejected in the predetermined region is small, and therefore the area occupied by dots formed by the ejected ink is small. For this reason, since the blank paper portion without dots becomes larger, the output of the light receiving units 40 and 41 by reflected light becomes higher. It is possible to measure the density of the print pattern based on the difference between the outputs of the light receiving units 40 and 41.

  In the above, as shown in the drawing, the light emitting unit 38, the specular reflection light receiving unit 40, and the diffuse reflection light receiving unit 41 are integrated into the reflection type optical sensor 31. Each may be configured as a separate device such as a light receiving device.

  In the above, in order to obtain the amount of reflected light received, the magnitude of the electrical signal is measured after converting the reflected light into an electrical signal. However, the present invention is not limited to this. It is only necessary that the output value of the light receiving sensor corresponding to the amount of reflected light can be measured.

=== Color calibration processing ===
The ink ejected from the nozzles does not necessarily eject the same amount of ink even if driven by the same print data due to individual differences in the nozzles and piezo elements, the type of ink, and the like. Since the printer 20 is controlled based on a theoretical value in design, a nozzle row in which the ink ejection amount is different from the theoretical value, and a nozzle row (hereinafter referred to as a reference nozzle row) that ejects ink according to the theoretical value. Are driven with the same control, images that should be printed at the same density are printed at different densities for each nozzle array, resulting in color unevenness or images with different hues. .
For this reason, among the plurality of nozzle arrays provided in each print head, the difference in the density of images printed by the ink ejected from the nozzle arrays ejecting the same color ink by different print heads is reduced. The color calibration process is executed.

<First Embodiment>
In the first embodiment, when printing a predetermined print pattern as a density adjustment pattern with ink ejected by driving the piezo element PE to a predetermined drive waveform for each nozzle row of each print head, Characteristic information based on the measured value obtained by measuring the density of the printed pattern is stored in the memory 401. An example in which a drive signal is generated based on the characteristic information and an image having an appropriate density can be printed using ink ejected from each print head based on the generated drive signal will be described. In this example, as characteristic information indicating the characteristics of the nozzle array, when ink is ejected based on a predetermined drive signal, the deviation of the density of the print pattern printed with the ejected ink from the reference density is calculated. An example in which the concentration information shown is stored in the memory 401 in association with the temperature that is the output of the temperature sensor 29 will be described. Here, the reference density is a density of a print pattern to be printed when controlled based on a theoretical design value, and is printed by a reference nozzle row and a reference printer. It may be the density when the printed pattern is measured, or the density of a density sample printed in advance.

  The density information of each nozzle row is, for example, an ID value as a deviation of the print pattern density printed for each temperature division based on image data for printing a print pattern of a predetermined density with respect to the reference density This is a density data table in which each temperature segment and ID value are associated with each other for each nozzle row. In the present embodiment, the temperature division is, for example, a first temperature division where the temperature is lower than 22 ° C. (T <22 ° C.), a second temperature division of 22 ° C. to 28 ° C. (22 ° C ≦ T ≦ 28 ° C.), 28 The temperature is divided into three temperature segments of a third temperature segment higher than 28 ° C. (28 ° C. <T).

~~ Example of printing pattern ~~
The print pattern is printed by ejecting ink to an area allocated to each nozzle row by a printing method for printing an image. Here, for convenience of explanation, an example in which one image is printed by the first print head 28a and the second print head 28b will be described. That is, the density data table generated in the present embodiment is used for color calibration executed when one image is printed by the first print head 28a and the second print head 28b. Since the ID value is obtained for each nozzle row, the print pattern is printed for each nozzle row. For this reason, one nozzle row for ejecting the same color ink, for example, yellow ink, provided in the two print heads 28a and 28b will be described. Here, the yellow nozzle row of the first print head 28a is referred to as Ya, and the yellow nozzle row of the second print head 28b is referred to as Yb.

  FIG. 10 is a diagram for explaining a printing pattern having a predetermined density and a printing method thereof. FIG. 10A is a diagram for describing a region where each nozzle row prints when forming an image with nozzle rows ejecting the same color ink of two print heads, for example. FIG. 10B is a diagram for explaining an area allocated to the yellow nozzle row Yb and a print pattern printed on the yellow nozzle row Yb. FIG. 10C is a diagram for explaining a region assigned to the yellow nozzle row Ya and a print pattern printed by the yellow nozzle row Ya.

  When printing an image with the two print heads 28a and 28b, for example, as shown in FIG. 10A, each print is performed so that pixels adjacent to each other in the carriage movement direction and the conveyance direction are formed by different print heads. Assume that the print area of the head is allocated. That is, when the carriage 30 reciprocates, ink is ejected from the nozzles of the yellow nozzle row Yb of the second print head 28b in the forward path to form odd-numbered pixels along the carriage movement direction. Then, the printing paper is transported in the transport direction by a distance corresponding to half of the distance between the nozzles (nozzle pitch) in the transport direction. Next, on the return path in the movement of the carriage 30, ink is ejected from each nozzle of the yellow nozzle row Yb so as to be positioned between the already formed pixels in the carriage movement direction to form even-numbered pixels. To do. After that, the most downstream pixel formed by the yellow nozzle row Yb of the second print head 28b and the most downstream nozzle of the yellow nozzle row Ya of the first print head 28a are in the same position in the transport direction. Transport printing paper. Then, ink is ejected from each nozzle of the yellow nozzle row Ya of the first print head 28a on the forward path of the carriage 30 to form even-numbered pixels along the carriage movement direction. Then, the printing paper is transported in the transport direction by a distance corresponding to half the nozzle pitch. Next, ink is ejected from each nozzle of the yellow nozzle row Ya so as to be positioned between pixels already formed in the carriage movement direction on the return path in the movement of the carriage 30 to form odd-numbered pixels. To do. That is, when printing is performed by such a printing method, the circled area shown in FIG. 10A is an area allocated to the second print head 28b, and the triangle mark area is allocated to the first print head 28a. It becomes an area. Therefore, the area allocated to each print head varies depending on the number of nozzles used, the printing method, and the like.

  As an example of a print pattern used when generating the density data table, a print pattern formed in an area of 100 pixels in which 10 pixels can be arranged vertically and horizontally will be described. In other words, the print pattern is formed in 100 unit pixel areas where individual pixels can be formed in a square area. The density of the print pattern is expressed by the number of dots formed in 100 unit pixel areas. At this time, the print pattern is printed for each nozzle row by ejecting ink to the area assigned to each nozzle row. Therefore, when printing one image with two print heads, printing with a density of 100% is performed. In the pattern, 50 dots are formed. For example, a print pattern in which 50 large dots are formed in 100 unit pixel areas is a print pattern having 100% large dots, and a print pattern in which 25 large dots are formed is 50% large dots. Print pattern. A print pattern in which 25 medium dots are formed in 100 unit pixel areas is a print pattern with 50% medium dots, and a print pattern in which 25 small dots are formed is 50% small dots. Print pattern. That is, the density of 100%, 50%, or the like here is not the actual density of the printed matter, but indicates the formation ratio of dots formed in 100 unit pixel areas. Further, when the dot formation ratio is other than 100%, the 100 unit pixel regions are arranged so that the deviation of the dots is as small as possible.

  FIG. 10B shows a print pattern with a dot formation rate of 100% printed by the yellow nozzle row Yb of the second print head 28b. That is, since printing is performed for each nozzle row, pixels are formed only in the area allocated to the second print head 28b. That is, as a print pattern of the yellow nozzle row Yb, ink is ejected from the print head 28b to the area marked with ○ shown in FIG. Nine print patterns forming the are printed. Nine print patterns are printed for each nozzle row of each print head 28. In this embodiment, the density of the print pattern is 100%, but the density of the print pattern to be printed is not limited to this.

  In addition, the reference density is measured at three temperatures using a printer equipped with a reference print head that ejects ink according to a theoretical design value or a printer that performs color calibration with a reference print head attached. It is the density of the print pattern printed in the environment of the classification. For this reason, as a print pattern, a plurality of print patterns are printed for each region assigned to the nozzle row. For example, in the above example, two types of print patterns, the area shown in FIG. 10B and the area shown in FIG. 10C, are printed for each nozzle row, dot size, and temperature section of the reference print head. .

~~ Example of generation method of density data table ~~
FIG. 11 is a diagram for explaining an example of a method for generating a density data table. First, based on image data for printing a printing pattern of a predetermined density, a predetermined printing pattern of each dot size in each nozzle row for each of the three temperature segments using a reference printer or a reference printing head. Is printed (S101). Here, the reference printer and the reference print head are a reference printer and a reference print head that eject ink according to a theoretical value, which can print a print pattern having a reference density when a predetermined print pattern is printed. A predetermined print pattern printed using the reference printer or the reference print head is hereinafter referred to as a reference print pattern.

  The printed reference print pattern is set in the printer 20 to be controlled based on the characteristic information for each nozzle row and the output of the temperature sensor 29, and is conveyed by the printing paper conveyance unit 21. At this time, the carriage 30 is moved while conveying the printing paper, and when the reflective optical sensor 31 mounted on the carriage 30 and the reference print pattern face each other, the density of the reference print pattern is measured. Measure with Then, the output of the reflective optical sensor 31 is stored as the density of the reference print pattern in correspondence with each print pattern (S102).

  Next, using the same image data as the reference print pattern, the printer 20 prints the print pattern at each nozzle row for each of the three temperature sections (S103). Thereafter, the print paper on which the print pattern is printed is transported by the print paper transport unit 21, the carriage 30 is moved, and the output of the reflective optical sensor 31 is output as the density of the print pattern printed by the printer 20. It stores in correspondence with each print pattern (S104). In the printer 20, the reflective optical sensor 31 is arranged on the downstream side in the paper conveyance direction, so that the density can be measured without conveying the paper in the reverse direction after printing the print pattern.

  And the deviation with respect to the output of the reflection type optical sensor 31 by the reference | standard printing pattern of the output of the reflection type optical sensor 31 by the printing pattern printed with the printer 20 is calculated | required for every printing pattern. At this time, the output of the reflective optical sensor 31 based on the reference print pattern is shown as a deviation with the reference value “50” as an ID value, and this ID value is obtained for each print pattern (S105). A density data table in which the obtained ID value is associated with the temperature classification is generated for each print head and stored in the memory 401 (S106). For example, the ID value is obtained by Expression 1 where IDx to be obtained is IDx, the density of the reference print pattern is V0, and the density of the print pattern printed by the printer 20 is Vs.

IDx = Vs / V0 × 50 (Formula 1)
At this time, the density of the reference print pattern is, for example, 0.5 V for black, 1.5 V for cyan, 1.7 V for light cyan, and 3.0 V for a white background at the output of the reflective optical sensor 31. Magenta is 1.5V, light magenta is 1.7V, and yellow is 2.0V. The higher the density, the lower the output. For this reason, the higher the density, the smaller the ID value. Here, the ID value is obtained by assuming that the output of the reflective optical sensor 31 changes linearly with respect to the density of the print pattern.

FIG. 12 is a diagram illustrating an example of the density data table.
For example, according to the density data table of FIG. 12, the characteristic information when forming large dots in the black nozzle row K of the first print head in an environment of a temperature higher than 28 ° C. is “50”. That is, when the output of the temperature sensor 29a is 28 ° C. or higher, the ink for forming large dots is ejected from the black nozzle row K of the first print head according to the designed theoretical value (ID50). An image having the same density as that printed using the reference printer or the reference print head is printed. Further, when the output of the temperature sensor 29a is 22 ° C. or higher and lower than 28, printing is performed at a density corresponding to 49 (ID49) when the theoretical value 50 is designed, so that the reference printer or the reference print head is printed. An image having the same density as that printed using is printed. When the output of the temperature sensor 29a is less than 22 ° C., printing is performed using a reference printer or a reference print head by printing at a density corresponding to 48 (ID48) when the theoretical value 50 is designed. An image having the same density as that at the time of printing is printed. That is, in this case, even if the nozzle row that discharges the black ink K is driven with the same drive signal, the image printed when the output of the temperature sensor 29a is 28 ° C. or higher is less than 22 ° C. In some cases, the density is higher than the printed image. For this reason, even if the ID values are different, the drive signal is generated so that the difference in the density of the image printed by the ink ejected by the same drive signal is reduced.

~~ Drive signal generation process ~~
Processing for generating a drive signal in the first embodiment will be described along the operation of the printer 20. FIG. 13 is a flowchart for explaining processing for generating a drive signal. Here, the drive signal is generated so as to correspond to the output of the temperature sensor 29 and to reduce the difference in the size of dots formed by the yellow nozzle rows Ya and Yb of the first print head 28a and the second print head 28b. An example will be described.

  When the image data is received together with the print command signal from the computer connected to the printer 20, the main control unit 310 of the printer 20 detects the output of the temperature sensor 29 associated with the print head 28 (S201). Assume that 30 ° C. is detected as the output of the temperature sensor 29a associated with the first print head 28a and 25 ° C. is detected as the output of the temperature sensor 29b associated with the second print head 28b.

  The image processing unit converts the resolution of the input RGB image data into the print resolution by the image processing unit (S202). The resolution-converted data is converted from RGB image data for each pixel into data of, for example, 256 gradations of a plurality of ink colors that can be used by the printer 20 while referring to the color conversion data table LUT (S203). At this time, an ID value corresponding to the output of the temperature sensor 29 in each nozzle row is acquired (S203a), and 256 gradation levels are corrected based on the acquired ID value and the color conversion data table LUT. Color conversion processing is executed (S203b).

  FIG. 14 shows gradation values and dot formation ratios indicating the concept of the formation ratio of large, medium, and small dots that are formed when printing an image having the density indicated by each gradation value in the color conversion data table LUT. It is a standard correspondence figure. In FIG. 14, the horizontal axis indicates the gradation value, and the vertical axis indicates the formation ratio of dots of each size. A reference correspondence diagram of gradation values and dot formation ratios is provided for each ink color. For example, when the image data of a pixel has a gradation value of “128”, the dot is formed based on a ratio of 10% for large dots, 50% for medium dots, and 22% for small dots. Will be.

The correction of the gradation value based on the ID value of each nozzle row is executed as follows.
When color conversion processing is performed on RGB data after resolution conversion corresponding to a predetermined pixel formed by the yellow nozzle row Ya of the first print head 28a, the yellow gradation value for the pixel is converted into the color conversion data table LUT. Then, it is assumed that “128” is set. This gradation value “128” is a gradation value when dots are formed by the nozzle row of ID50. For this reason, the dot that should be originally formed based on the data of the gradation value “128” is the ratio of the dots formed by the nozzle row of ID50 based on the data of the gradation value “128” is large dots. 10%, medium dots are 50%, and small dots are 22%.

  For example, when printing is performed on the basis of the data of the gradation value “128” at the yellow nozzle row Ya of the first print head 28a when the output of the temperature sensor 29a is 30 ° C., the following is performed. Convert. The ID value in the third temperature section of the yellow nozzle row Ya of the first print head 28a is 50 for the large dot (YLid), 48 for the medium dot (YLid), and 48 for the small dot (YSid). ) Is 52. Therefore, the dot formation ratio of the yellow nozzle row Ya of the first print head 28a is converted based on the ID value. For example, the dot formation ratios RL, RM, and RS of the large, medium, and small dots when forming dots based on the data of the gradation value “128” in the yellow nozzle row Ya are expressed by Equations 2 to 4. Desired.

Dot formation ratio of large dots RL = (50 / YLid) × 10 (Expression 2)
Dot formation ratio of medium dots RM = (50 / YMid) × 50 (Equation 3)
Dot formation ratio of small dots RS = (50 / YSid) × 22 (Expression 4)
Then, the dot formation ratio of the converted yellow nozzle row Ya is expressed by Equations 2 to 4, in which the dot formation ratio RL for large dots is 10%, the dot formation ratio RM for medium dots is 48%, and the dot formation ratio for small dots. RS is converted to 23%.

  On the other hand, when the output of the temperature sensor 29b is 25 ° C., the dot formation ratio of the yellow nozzle row Yb of the second print head 28b is 9% with the large dot formation ratio RL according to the above formulas 2 to 4. The dot formation ratio RM is converted to 51% and the dot formation ratio RS of small dots is converted to 23%.

  In this way, by correcting the dot formation ratio for each nozzle row that ejects ink of each color based on the output of the temperature sensor, the ID value of each nozzle row, and the color conversion data table LUT, the ID value It is possible to suppress variation in density of images printed by different nozzle rows, that is, nozzle rows having different ink ejection characteristics.

  The color-converted data is generated into halftone image data binarized by so-called halftone processing based on the converted dot formation ratio in the halftone processing unit (S204). The halftone image data is subjected to rasterization processing and raster row conversion processing that are rearranged in the order of data to be transferred to the printer 20 by the rasterization processing unit and raster row conversion processing unit, and output as final print data PD (S205). . At this time, together with the print data PD, raster data indicating the dot formation state during carriage movement and data indicating the amount of paper transport are output.

  The control circuit 500 generates a PTS signal at a predetermined timing in the PTS pulse generation circuit based on a command from the main control unit 310, synchronizes with the original drive signal generation unit 540, and appropriately performs mask processing based on the print data PD. A drive signal corresponding to each generated nozzle row is output, and the print head 28 is driven to print (S206).

  According to the printer 20 of the present embodiment, the nozzle row that ejects the same color ink of different print heads 28 is driven by the drive signal generated based on the ID value as the characteristic information. Therefore, the nozzle that ejects the same color ink It is possible to make the amount of ink ejected from the columns almost uniform. For this reason, even when printing one image using different print heads 28, since the size of the dots to be formed is almost equal, unevenness of color tone is less likely to occur in the printed image. It is possible to print a clear image. In addition, by obtaining an ID value as discharge amount information of drive signal generation information corresponding to the output of the temperature sensor 29 from the discharge amount data table, a drive signal suitable for the detected temperature can be easily generated. It is.

  In addition, by making the characteristic information density information based on the density of the printed pattern that has been actually printed, it is possible to eject different amounts of ink from the ink ejection unit due to temperature differences based on information that conforms to the actual machine. It is possible to suppress. For this reason, it is possible to realize a printer that is less affected by temperature and that can stably and appropriately eject ink.

  Further, as the density measuring unit for measuring the density of the print pattern, for example, a sensor for detecting paper or a reflective optical sensor 31 mounted on a carriage 30 used as a sensor for detecting paper width can be used. It is possible to reduce the manufacturing cost.

  In the above-described embodiment, the example in which the reflective optical sensor 31 is provided on the downstream side in the paper transport direction with respect to the print head 28 has been described. However, the reflective optical sensor 31 is not necessarily provided on the downstream side. For example, it may be arranged upstream of the print head. In this case, when the print pattern is printed, the print pattern is positioned upstream from the reflective optical sensor 31. For this reason, it is necessary to transport the paper on which the printing pattern is printed in the direction opposite to that during printing. On the other hand, if the reflective optical sensor 31 is the printer 20 of the first embodiment provided on the downstream side in the paper conveyance direction with respect to the print head 28, the paper on which the print pattern is printed is conveyed in the reverse direction. It is possible to measure the concentration without any problems. For this reason, the first embodiment is preferable because it is easy to process when printing a print pattern and measuring the density, and can be executed efficiently in a short time. Furthermore, in the first embodiment, an example in which one reflective optical sensor 31 is provided has been described, but a plurality of reflective optical sensors may be provided. In this case, it is possible to reduce the time spent for the process of measuring the density of the print pattern, but there is a possibility that an error occurs in the measurement value due to the variation among individuals of the reflection type optical sensor. For this reason, the printer of the first embodiment provided with one reflective optical sensor can print a better image.

  In the above embodiment, the print pattern is printed with three different sizes of dots. Therefore, based on the print pattern printed with dots of the same size as the actually printed image. It is possible to print a better image.

  In the first embodiment, the example in which the density of the reference print pattern and the print pattern printed by the printer 20 is measured by the reflective optical sensor 31 included in the printer 20 has been described. The ID value may be obtained by measuring with another density measuring device (for example, X-Rite 938 (trade name: manufactured by X-Rite)) or a reading scanner. In this case, it is not necessary to provide a sensor for density measurement in the printer 20 and the density can be measured without setting the reference print pattern in the printer 20. The first embodiment using the reflective optical sensor 31 is superior in that good correction is possible.

  In the first embodiment, the example in which the dot formation ratio is corrected for each nozzle row based on the characteristic information to generate the drive signal for each nozzle row as a result has been described. However, it is not limited to this. For example, using the average value of the ID values of all the nozzle rows of one print head as the ID value of the print head, based on this ID value, the maximum voltage value, the minimum voltage value, the voltage rise time in the drive signal, and A drive signal to be supplied for each print head may be generated by adjusting the descent time or the like.

Second Embodiment
In the first embodiment, an example in which a print pattern is printed for each dot size for each temperature division when obtaining an ID value as characteristic information has been described. In the second embodiment, one nozzle row has one print pattern. An example in which an ID value is obtained and color calibration is executed based on the ID value will be described.

  Also in the second embodiment, when printing one image with the two print heads 28a and 28b, the pixels adjacent to each other in the carriage movement direction and the conveyance direction are formed with different print heads. Assume that the print area of the print head is allocated. That is, also in the second embodiment, ink is ejected to the allocated area in each nozzle row of each print head 28, and a print pattern with a predetermined density is printed for each nozzle row. The density of the printed pattern is measured by the reflective optical sensor 31 as in the first embodiment. When the density to be printed, that is, the reference density is “50”, an ID value indicating a deviation between the measured value of each print pattern and the value “50” indicating the reference density is set for each ID value. Obtained for each nozzle row. Here, when the measurement result is higher than the reference concentration, the ID value becomes a large value, and when the measurement result is lower than the reference concentration, the ID value becomes a small value. In the second embodiment, since a print pattern is not formed for each temperature classification and for each dot size, one print pattern is printed in each nozzle row, and each has one ID value.

  FIG. 15 is a diagram showing a density data table in the second embodiment. As shown, one ID value is associated with each nozzle row.

  FIG. 16 is a diagram for explaining the concept of the density conversion data table used in the color calibration in the second embodiment.

  FIG. 16 is a density conversion data table as density correspondence information, and a nozzle array having a different density of an image printed based on the same signal as the reference nozzle array, that is, a default nozzle as a default ink ejection unit having a different ID value. Using multiple columns, when printing with a predetermined printing method, images are printed with different dot formation ratios as described above, and the measured density of the printed image and dot formation are printed. The correlation with the ratio is shown. In FIG. 16, the vertical axis indicates the dot formation ratio, and the horizontal axis indicates the density of the printed image. Here, the density of the printed image is the gradation value “255” as the density of the image in which ink is ejected over the entire area assigned to the nozzle row, and the gradation value ““ as the density of the image where no ink is ejected. The gradation value is expressed in 256 levels, “0”. This density conversion data table is provided for each of a plurality of ink colors (K, C, LC, M, LM, Y) that can be used by the printer 20.

  In FIG. 16, the density of the image printed when using the reference nozzle row of the reference ID value (ID50), and the dot formation ratios are printed step by step with the nozzle rows of ID48 and ID51. Three graphs associating the image density with the dot formation ratio of the printed image are shown.

  The ID50 graph prints multiple images with different dot formation ratios step by step using a reference nozzle array, measures the density of the printed image with a density meter, and replaces the measured values with tone values. Is a graph plotted. For example, a graph when printing one image with two print heads can form an image with a dot formation rate of 100%, that is, 100 pixels as an area allocated to a nozzle row within a predetermined area. An image in which 50 pixels are formed in an area is printed using the reference nozzle row, the density of the printed image is measured, the measured value is a dot formation ratio of 100%, and the gradation value “255” indicating the density. Plot at the intersection with If the dot formation rate is 50%, an image in which 25 pixels are formed in an area where 100 pixels as areas assigned to the nozzle array in the predetermined area can be formed is used as the reference nozzle array. The density of the printed image is actually measured, and the actually measured value is plotted at the intersection of the dot formation ratio 50% and the gradation value “128” indicating the density. Then, an image in which the dot formation ratio is changed stepwise is printed using the reference nozzle row, and the measured value of the density of the printed image is plotted to complete the ID50 graph. Similarly, the graphs of ID48 and ID51 are graphs in which measured values are plotted using the default nozzle arrays of ID48 and ID51. For example, an image with a dot formation ratio of 50% printed by the nozzle array of ID48 is printed. When the density is actually measured, the gradation value is “115”. In addition, when an image with a dot formation ratio of 50% is printed with the nozzle row with ID 51 and the density of the printed image is measured, the gradation value is “140”. A plurality of images having different dot formation ratios are printed in this way, and the values obtained by actually measuring the density of the printed images are plotted to create a graph as shown in FIG. In this example, three graphs are shown. However, as many graphs as the number corresponding to ID values that can be set in the nozzle row are formed. A density conversion data table shown in such a graph is stored in the memory 401.

Color calibration is executed as follows based on the ID value of each nozzle row and the density conversion data table.
When the RGB data after resolution conversion corresponding to a predetermined pixel formed by the yellow nozzle row Ya of the first print head 28a is subjected to color conversion processing, the yellow density for the pixel is expressed in the color conversion data table LUT as “ Suppose that it is set to "128". This density “128” is a density when an image is formed by the nozzle row of ID50. Therefore, an image that should be originally formed based on the data of density “128” is an image having a dot formation ratio of 50% formed by the nozzle row of ID 50 based on the data of density “128”.

  On the other hand, the yellow nozzle row Ya of the first print head 28a is ID51. An image having the same density as the gradation value “128” formed in the reference nozzle row in the yellow nozzle row Ya of the first print head 28a corresponds to an image having a dot formation ratio of 40% in the reference nozzle row. Is shown in the graph of FIG. For this reason, the data of the gradation value “128” printed by the nozzle array of ID 51 is converted into the gradation value “110” corresponding to the density of the image with the dot formation ratio of 40% formed by the reference nozzle array. .

  Also, consider a case where dots having a density of “128” similar to this pixel are formed by the yellow nozzle row Yb of the second print head 28b. The yellow nozzle row Yb of the second print head 28b is ID48. In the yellow nozzle row Yb of the second print head 28b, an image having the same density as the gradation value “128” formed in the reference nozzle row corresponds to an image having a dot formation ratio of 58% in the reference nozzle row. Is shown in the graph of FIG. For this reason, the data of the gradation value “128” printed by the nozzle array of ID 48 is converted into the gradation value “135” corresponding to the density of the image with the dot formation ratio of 58% formed by the reference nozzle array. .

  Then, based on the ID value of each nozzle row and the density conversion data table, by generating conversion data in which the density is converted for each nozzle row that ejects ink of each color, nozzle rows having different ID values, that is, ink It is possible to suppress variations in the density of images formed by nozzle rows having different ejection characteristics.

~~ Printing action ~~
Processing for generating print data will be described along the operation of the printer 20. FIG. 17 is a flowchart for explaining processing for generating print data. Here, an example will be described in which print data is generated so as to reduce the difference in density of images formed by the yellow nozzle rows Ya and Yb of the first print head 28a and the second print head 28b.

  First, the printer 20 receives image data together with a print command signal and print information from a computer connected to the printer 20 (S301). The print information is data indicating various conditions relating to printing such as the resolution of an image to be printed, a printing method such as band printing or interlaced printing. That is, the printer 20 acquires this print information, so that in the main printing operation, the amount of print paper that is intermittently conveyed, the number of movements of the carriage 30 for one raster printing, and the movement of each carriage 30 In this case, it is possible to specify a nozzle that can eject ink.

  The image processing unit 350 converts the resolution of the input RGB image data into the print resolution (S302). At this time, each converted data corresponds to each pixel constituting the image to be printed. That is, the converted data corresponds to each pixel of the image to be printed, and the printer 20 can specify the nozzle on which each pixel is formed based on the print information acquired together with the image data. It becomes possible.

The data subjected to the resolution conversion is subjected to data conversion processing by the color conversion processing unit (S303). In the color conversion process, first, with reference to the color conversion data table LUT, color conversion processing is performed for each pixel from 256 RGB gradation data to CMYK 256 gradation data for printing by the printer 20 (S303a). .
The image data subjected to color conversion processing is divided and stored in a memory in which an area is divided for each nozzle row to be printed by the image processing unit 350 (S303b). FIG. 18 is a conceptual diagram showing a memory 401 in which a storage area is divided and stored for each nozzle row on which data is printed. In the memory 401, an area for storing data to be printed by each nozzle row is divided for each nozzle row of each print head 28, and a predetermined area is designated by designating the area divided by the memory address or the like. It is possible to specify the data stored in the area.
The data stored in the storage area associated with each nozzle row is subjected to the color calibration process described above for each storage area (S303c, S303d). At this time, the main control unit 310 acquires an ID value corresponding to each nozzle row (S303c), and data indicating the density of 256 gradations corresponding to the density of ID50 based on the acquired ID value and density conversion data table. In addition, the data is collectively converted for each stored storage area (S303d).

The color-converted data is returned to one data for each color. That is, the data is rearranged so that the data stored separately for each nozzle row becomes the image data arranged for each color before the division (S304).
The rearranged data after the color conversion process is generated into halftone image data binarized by so-called halftone processing in a halftone processing unit (S305). The halftone image data is subjected to rasterization processing and raster row conversion processing to be rearranged in the order of data to be transferred to the printer 20 by the rasterization processing unit and raster row conversion processing unit, and is output as final print data PD (S306). . At this time, the data indicating the sheet conveyance amount is also output together with the print data PD.

  The control circuit 500 generates a PTS signal at a predetermined timing in the PTS pulse generation circuit based on a command from the main control unit 310, synchronizes with the original drive signal generation unit 540, and appropriately performs mask processing based on the print data PD. A drive signal corresponding to each generated nozzle row is output, and the print head 28 is driven to print (S307).

  According to the printer 20 of the second embodiment, the nozzle rows for ejecting the same color ink of different print heads 28 are driven by the print data generated based on the ID value as the characteristic information and the density conversion data table. The densities of images formed by different nozzle arrays that discharge ink of the same color can be made substantially uniform. For this reason, even when printing one image using different print heads 28, the density of the image formed with the same color ink ejected from each print head 28 is substantially equal, and the dots formed Since the sizes are almost equal, unevenness of color and the like hardly occur in the printed image, and it is possible to print a good image.

  Also, when performing color calibration processing, image data is stored in a separate storage area for each nozzle row to be printed, and image data is converted in batches for each stored storage area, making conversion processing easy. And can be executed in a short time.

  In the second embodiment, an example is shown in which density conversion is performed based on the ID value of the nozzle row during the color conversion processing. However, RGB image data is subjected to color conversion processing based on the color conversion data table LUT, When halftone processing is performed on the color-converted data, the data is divided and stored in a memory for each nozzle row to be printed, and large, medium, and small in a predetermined area of the image based on the ID value of each nozzle row The ratio of distributing the dots may be changed. In this case, for example, when the dither method is used as the halftone process, it can be realized by converting the threshold given to each pixel by the dither matrix in accordance with the ID value of the nozzle row.

<Third Embodiment>
In the third embodiment, the processing until the generation of the density conversion data table used in the color conversion processing is the same as that in the second embodiment described above. For this reason, in the third embodiment, processing for converting an image data gradation value and printing an image will be described along the operation of the printer 20. FIG. 19 is a flowchart for explaining a process of printing an image by converting gradation values. Here, an example will be described in which the gradation value of image data printed by the yellow nozzle row Y is converted to print an image.

  First, the printer 20 receives image data together with a print command signal and print information from a computer connected to the printer 20 (S401). The print information is data indicating various conditions relating to printing such as the resolution of an image to be printed, a printing method such as band printing or interlaced printing.

  The image data is converted by the resolution conversion processing unit 351 of the image processing unit 350 from the resolution of the input RGB image data to the printing resolution (S402). At this time, each converted data corresponds to each pixel constituting the image to be printed. That is, the converted data corresponds to each pixel of the image to be printed, and the printer 20 can specify the nozzle on which each pixel is formed based on the print information acquired together with the image data. It becomes possible.

The data subjected to the resolution conversion is subjected to data conversion processing by the color conversion processing unit 352 (S403). In the color conversion process, first, with reference to the color conversion data table LUT, color conversion processing is performed for each pixel from 256 RGB gradation data to CMYK 256 gradation data for printing by the printer 20 (S403a). .
The image processing unit 350 performs color calibration processing on the color-converted image data (S403b). At this time, the main control unit 310 first obtains an ID value for each nozzle row associated with each yellow nozzle row Y from the memory 401, and obtains an average value thereof by calculation processing. The obtained average value of the ID values is converted into a gradation value indicating the density of 256 gradations corresponding to the density of ID50 based on the density conversion data table similar to the second embodiment (S403c). That is, the color conversion processing unit 352 calculates the gradation value of the image data to be printed based on the ejection amount of the ink ejected from each of the nozzle rows as the plurality of ink ejection units and the reference amount of the reference ink. It is the conversion part which converts for every pixel.

The rearranged data after color conversion processing is generated into halftone image data binarized by so-called halftone processing in a halftone processing unit (S404). The halftone image data is subjected to rasterization processing and raster row conversion processing that are rearranged in order of data to be transferred to the printer 20 by the rasterization processing unit and raster row conversion processing unit, and is output as final print data PD (S405). . At this time, the print data PD and the data indicating the paper conveyance amount are also output.
The control circuit 500 generates a PTS signal at a predetermined timing in the PTS pulse generation circuit based on a command from the main control unit 310, synchronizes with the original drive signal generation unit 540, and appropriately performs mask processing based on the print data PD. A drive signal corresponding to each generated nozzle row is output, and the print head 28 is driven to print (S406).

  According to the printer 20 of the present embodiment, the density conversion data table as density correspondence information included in the printer 20 is printed using a plurality of predetermined ink ejection units for each color of ink ejected from each nozzle row. The image density is associated with the image density of the reference amount of ink. In addition, since the plurality of predetermined ink discharge portions have different ink discharge amounts, one of the predetermined ink discharge portions corresponds to the average value of the ink discharge amounts discharged from the plurality of nozzle rows included in the printer 20. It is possible to correspond to a predetermined nozzle array that ejects a certain amount of ink. Therefore, in the density conversion data table, the density of an image printed using a predetermined nozzle array that ejects an amount of ink corresponding to the average value of the ejection amounts of a plurality of nozzle arrays, and the density of an image with a reference amount of ink By converting the tone values based on the correspondence relationship, it is possible to suppress the variation in the density of the image printed by the ink ejected from each nozzle row ejecting the same color ink.

  In addition, according to the printer 20 of the above-described embodiment, ink is ejected to the area allocated to each nozzle row, a print pattern is printed for each nozzle row, and an image is printed based on the printed print pattern. . That is, the print pattern is printed by ejecting ink from each nozzle row to a region where ink is actually ejected when printing an image. Since the image is printed based on the density of the print pattern formed by ejecting ink in the same region as when the image is actually printed, the image can be printed with a more appropriate density. In other words, the image is printed based on the image data converted so that the difference between the density of the print pattern printed by the printer that performs color calibration and the reference density becomes small. It is possible to print at a density almost equal to the reference density.

  In the above-described embodiment, an example has been described in which color calibration is performed by printing a print pattern for each nozzle row. However, the present invention is not limited to this. For example, a print pattern is printed only with a nozzle row that discharges light-colored ink, that is, light cyan, light magenta, yellow, etc., and color calibration is executed only for the nozzle row that discharges light-colored ink. Also good. In this case, the processing is easier than when color calibration is performed for all nozzle rows. In addition, light-colored ink is used in halftone areas where graininess is conspicuous and density unevenness is likely to occur, so it is possible to print a good image with reduced density variation at least in the halftone area. It is.

  In addition, since the printer of the above embodiment has the configuration including the reflection type optical sensor 31 for measuring the density of the print pattern, the density of the actually printed print pattern can be measured on the printer. The density of the printed pattern can be measured without removing the paper on which the pattern is printed from the printer. In addition, since the density of the reference print pattern is also measured by the reflective optical sensor 31 mounted on the printer 20, no measurement error due to sensor sensitivity variation or the like occurs. It is possible to reduce the difference between the density of the printed pattern printed at 20 and the reference density.

=== Other Embodiments ===
The present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

  (1) In the above embodiment, a part of the configuration realized by hardware may be replaced with software, and conversely, a part of the configuration realized by software may be replaced with hardware. Also good.

  (2) The present invention is generally applicable to printing apparatuses that eject ink droplets, and can be applied to various printing apparatuses other than color inkjet printers. For example, the present invention can be applied to an ink jet facsimile machine and a copying machine.

<<< Configuration of printing system >>>
Next, embodiments of a printing system and a computer program, which are examples of embodiments according to the present invention, will be described with reference to the drawings.

  FIG. 20 is an explanatory diagram showing an external configuration of the printing system. The printing system 700 includes a computer main body 702, a display device 704, a printer 706, an input device 708, and a reading device 710. The display device 704 is generally a CRT (Cathode Ray Tube), a plasma display, a liquid crystal display device, or the like, but is not limited thereto. As the printer 706, the printer described above is used. In this embodiment, the input device 708 uses a keyboard 708A and a mouse 708B, but is not limited thereto. In this embodiment, the reading device 710 uses a flexible disk drive device 710A and a CD-ROM drive device 710B. However, the reading device 710 is not limited to this. For example, an MO (Magneto Optical) disk drive device or a DVD (Digital Versatile) is used. Disk) etc. may be used.

  FIG. 21 is a block diagram showing the configuration of the printing system shown in FIG. An internal memory 802 such as a RAM and an external memory such as a hard disk drive unit 804 are further provided in a housing in which the computer main body 702 is housed.

  In the above description, an example in which the printer 706 is connected to the computer main body 702, the display device 704, the input device 708, and the reading device 710 to configure the printing system has been described. However, the present invention is not limited to this. Absent. For example, the printing system may include a computer main body 702 and a printer 706, and the printing system may not include any of the display device 704, the input device 708, and the reading device 710.

  For example, the printer 706 may have a part of each function or mechanism of the computer main body 702, the display device 704, the input device 708, and the reading device 710. As an example, the printer 706 includes an image processing unit that performs image processing, a display unit that performs various displays, a recording medium attachment / detachment unit for attaching / detaching a recording medium that records image data captured by a digital camera or the like. It is good also as a structure to have.

  In addition, the computer program for controlling the printer in the above-described embodiment is stored in the memory of the printer controller, and the printer controller executes the computer program to achieve the printer operation of the above-described embodiment. Good.

  The printing system realized in this way is a system superior to the conventional system as a whole system.

1 is a perspective view showing an outline of a configuration of an ink jet printer as a printing apparatus according to the present invention. FIG. 3 is an explanatory diagram illustrating an outline of a configuration of a printing unit included in an inkjet printer. Sectional drawing for demonstrating a printing part. The figure for demonstrating arrangement | positioning of the nozzle in the lower surface of one printing head. The figure which looked at the carriage from the direction of arrow A (FIG. 3). FIG. 2 is a block diagram illustrating an electrical configuration of the printer. The block diagram which shows the structure of the drive signal generation part provided in the drive control part (FIG. 6). 4 is a timing chart of an original drive signal ODRV, a print signal PRT (i), and a drive signal DRV (i) showing operations of the drive signal generation unit. FIG. 4 is a schematic diagram for explaining an example of a reflective optical sensor 31. FIG. 10A is a diagram for explaining an area to be printed by each nozzle row when forming an image with nozzle rows that eject the same color ink of two print heads, for example. FIG. 10B is a yellow nozzle row Yb. FIG. 10C is a diagram for explaining a print pattern printed in the area assigned to the yellow nozzle row Yb, and FIG. 10C shows a print pattern printed in the area assigned to the yellow nozzle row Ya and the yellow nozzle row Ya The figure for demonstrating. The figure for demonstrating an example of the production | generation method of a density | concentration data table. The figure which shows an example of a density | concentration data table. The flowchart for demonstrating the process which produces | generates a drive signal. FIG. 5 is a reference correspondence diagram of gradation values and dot formation ratios indicating the concept of the formation ratio of large, medium, and small dots that are formed when printing an image having a density indicated by each gradation value in the color conversion data table LUT. The figure which shows the density | concentration data table in 2nd Embodiment. The figure for demonstrating the concept of the density conversion data table used in the color calibration in 2nd Embodiment. 6 is a flowchart for explaining processing for generating print data. The conceptual diagram which shows the memory which divides and memorize | stores a memory area for every nozzle row where data is printed. 10 is a flowchart for explaining a process of printing an image by converting gradation values. FIG. 2 is an explanatory diagram showing an external configuration of a printing system. The block diagram which shows the structure of the printing system shown in FIG.

Explanation of symbols

3, 3a-3f Sub tank, 4 valves, 9, 9a-9f Main tank, 11 Guide rail, 11a Upper guide rail, 11b Lower guide rail, 12 Carriage motor, 13 Drive belt, 14 Ink supply path, 15 Paper Holding unit, 15a holder, 15b shaft, 15c guide disk, 16 paper transport holder, 16a transport roller, 16b clamping roller, 17 platen, 18 transport motor, 18a drive gear, 18b relay gear, 20 printer, 21 printing paper transport unit , 22 printing section, 27 printing head group, 28, 28a to 28t printing head, 29, 29a to 29e temperature sensor, 30 carriage, 30A, 30B sub tank plate, 31 reflective optical sensor, 38 light emitting section, 40 specular reflection light reception , 41 Diffuse reflection light receiving part, 44 a, 44b Pulley, 105 CR motor driver, 106 Conveyor motor driver, 310 Main controller, 320 Data processor, 330 Drive controller, 340 Flexible cable, 350 Image processor, 351 Resolution conversion processor, 352 Color conversion Processing unit, 353 halftone processing unit, 354 rasterization processing unit, 355 raster row conversion processing unit, 400 control circuit, 401 memory, 410 differential driver, 420 SRAM, 430 interface, 500 control circuit, 502 PTS pulse generation circuit, 504 mask Signal generation circuit, 510 differential driver, 520 SRAM, 530 interface, 540 original drive signal generation unit, 700 printing system, 702 computer main unit, 704 display device, 706 printer, 708 input Device, 708A keyboard, 708B mouse, 710 reader, 710A flexible disk drive device, 710B CD-ROM drive device, 802 internal memory, 804 hard disk drive unit, LUT color conversion data table, n nozzle, ODRV original drive signal, P printing paper , PE Piezo element

Claims (19)

Comprising at least two ink ejection unit groups having a plurality of ink ejection units for ejecting a plurality of colors of ink for each color;
In the printing apparatus capable of ejecting ink from each of the ink ejection units to an area allocated to each of the ink ejection units, and printing one image with the at least two ink ejection unit groups,
Ink is ejected from the plurality of ink ejection sections to areas allocated to the respective ink ejection sections, and the image is printed based on the density of a predetermined print pattern printed for each of the ink ejection sections. A printing apparatus characterized by the above. The printing apparatus according to claim 1,
The image data for printing the image is converted based on the density of the predetermined print pattern so that the difference between the density of the predetermined print pattern and the reference density becomes small, and the converted image A printing apparatus that prints based on data. The printing apparatus according to claim 1 or 2,
The printing apparatus is characterized in that the printing pattern is printed with ink of any one of the plurality of colors. The printing apparatus according to claim 3.
The printing apparatus according to claim 1, wherein the ink of any one of the colors is a light color ink among the plurality of colors of ink. The printing apparatus according to any one of claims 1 to 4,
The plurality of ink ejection portions can form a plurality of types of dots having different sizes,
The printing apparatus is characterized in that each of the printing patterns is printed with the plurality of types of dots. The printing apparatus according to any one of claims 1 to 5,
A density measuring unit capable of measuring the density of the predetermined print pattern;
The density of the predetermined print pattern is measured by the density measurement unit. The printing apparatus according to claim 6.
The printing apparatus according to claim 1, wherein the reference density is a density of a reference print pattern measured by the density measuring unit. The printing apparatus according to claim 6 or 7,
The printing apparatus according to claim 1, wherein the density measurement unit is provided integrally with the at least two ink ejection unit groups. The printing apparatus according to any one of claims 6 to 8,
The print pattern is printed on a medium conveyed in a predetermined direction,
The printing apparatus according to claim 1, wherein the density measurement unit is provided on the downstream side in the predetermined direction with respect to the ink ejection unit group. The printing apparatus according to any one of claims 2 to 5,
The density of the predetermined print pattern is measured by a density measuring device provided outside. The printing apparatus according to any one of claims 2 to 5,
The printing apparatus according to claim 1, wherein the reference density is a density of a reference print pattern measured by the density measuring device. The printing apparatus according to any one of claims 2 to 11,
A signal generation unit that generates a drive signal for driving each of the ink ejection unit groups;
A temperature sensor for detecting the temperature,
Based on the density of the predetermined print pattern and the reference density, characteristic information indicating characteristics of the ink ejection unit group is obtained.
The printing apparatus, wherein the signal generation unit generates the drive signal for each of the ink ejection unit groups based on the characteristic information and the output of the temperature sensor. The printing apparatus according to any one of claims 2 to 11,
Based on the density of the predetermined print pattern and the reference density, characteristic information indicating characteristics of the ink ejection unit group is obtained.
Density correspondence information for associating the density of each image printed using a plurality of predetermined ink ejection units having different characteristic information with the reference density for each color of the ink;
Have
A plurality of storage areas for storing each of the ink ejection units for printing image data to be printed;
Based on the characteristic information and the density correspondence information corresponding to the color of the ink to be ejected, the difference between the density of the image printed by the plurality of ink ejection units and the standard density is reduced. In addition, the image data is converted for each of the stored storage areas, and ink is ejected from the plurality of ink ejection units based on the converted image data. The printing apparatus according to any one of claims 2 to 11,
A conversion unit that converts, for each pixel, a gradation value of image data to be printed based on the density of the predetermined print pattern and the reference density;
When the predetermined print pattern is printed, the density of the image printed using a plurality of predetermined ink ejection units having different densities of the predetermined print pattern printed on each of the inks is set to the reference density. Has density correspondence information associated with each color,
Printed by using a predetermined ink ejection unit that prints the predetermined print pattern having a density corresponding to an average value of the density of the predetermined print pattern printed by the plurality of ink ejection units in the density correspondence information. Printing that discharges ink from the plurality of ink discharge units based on the gradation values converted by the conversion unit based on the correspondence between the density of the image and the reference density apparatus. Comprising at least two ink ejection unit groups having a plurality of ink ejection units for ejecting a plurality of colors of ink for each color;
The plurality of ink ejection portions can form a plurality of types of dots having different sizes,
In the printing apparatus capable of ejecting ink from each of the ink ejection units to an area allocated to each of the ink ejection units, and printing one image with the at least two ink ejection unit groups,
A density measuring unit provided integrally with the at least two ink ejecting unit groups on the downstream side in the predetermined direction with respect to the ink ejecting unit group and capable of measuring the density of a predetermined print pattern;
Ink is ejected from the plurality of ink ejection sections to areas assigned to the respective ink ejection sections, and the predetermined print pattern is conveyed in a predetermined direction by the plurality of types of dots for each of the ink ejection sections. Printed on printed media,
The image so that the difference between the density of the printed predetermined print pattern measured by the density measurement unit and the density of the reference print pattern measured by the density measurement unit is small. A printing apparatus that converts image data for printing the image and prints based on the converted image data. Comprising at least two ink ejection unit groups having a plurality of ink ejection units for ejecting a plurality of colors of ink for each color;
In a printing apparatus capable of ejecting ink from each of the ink ejection units to an area allocated to each of the ink ejection units, and printing one image with the at least two ink ejection unit groups,
A function of ejecting ink from the plurality of ink ejection sections to an area allocated to each of the ink ejection sections and printing the image based on a density of a predetermined print pattern printed for each ink ejection section. Computer program for realizing. Connected to the computer body and this computer body,
Comprising at least two ink ejection unit groups having a plurality of ink ejection units for ejecting a plurality of colors of ink for each color;
In a printing system comprising: a printing device capable of ejecting ink from each ink ejection unit to a region allocated to each ink ejection unit and printing one image with the at least two ink ejection unit groups ,
Ink is ejected from the plurality of ink ejection sections to areas allocated to the respective ink ejection sections, and the image is printed based on the density of a predetermined print pattern printed for each of the ink ejection sections. A printing system featuring. Using at least two ink ejection unit groups having a plurality of ink ejection units for ejecting a plurality of colors of ink for each color, one ink is ejected to a region allocated to each of the ink ejection units. Ejecting ink from the plurality of ink ejection units capable of printing an image to a region assigned to each of the ink ejection units, and printing a predetermined print pattern for each of the ink ejection units;
And a step of printing the image on the basis of the density of a predetermined printed pattern. Densities printed by a plurality of ink ejection units capable of ejecting a plurality of colors of ink provided in at least two ink ejection unit groups for each color and ejecting ink to the assigned area to print one image In the adjustment print pattern,
A density adjustment printing pattern, wherein ink is ejected from the plurality of ink ejecting sections to an area allocated to each of the ink ejecting sections, and printing is performed for each ink ejecting section.

Images