JP2015208915A - Inkjet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet printer which can improve determination accuracy when an operator performs the determination of the completion of replacement to a new color when changing a color of an ink which is discharged by an inkjet head.SOLUTION: A target color decision part 91 decides a target color from a color in a common range of a color reproduction range which is formed of a combination of ink colors before a change of an ink color with respect to a kind of a sample patch printing paper sheet, and a color reproduction range which is formed of a combination of ink colors after a change of an ink color with respect to a kind of a determination patch printing paper sheet, and from a color which is printed by using an ink of a color after a change of an ink color in an ink-color change objective ink circulation type printing unit 22 in the combination of the ink colors after the change of the ink color.

Description

  The present invention relates to an ink jet printing apparatus that performs printing by discharging ink from an ink jet head.

  2. Related Art There is known an inkjet printing apparatus capable of full color printing using cyan (C), magenta (M), yellow (Y), and black (K) inks (see, for example, Patent Document 1).

  However, even this inkjet printing apparatus may not be able to express the color desired by the user. Thus, the ink cartridge mounted on the apparatus may be replaced with another color ink cartridge to change the ink color ejected by the inkjet head. Thereby, it can change to the apparatus which can express the color which a user desires. For example, by replacing magenta ink with red (R) ink, red with high saturation can be expressed.

  By the way, when the ink cartridge is replaced as described above, the original ink supplied from the ink cartridge before replacement remains in the printing unit having the inkjet head and the ink path.

  On the other hand, an ink replacement operation for replacing the original ink in the printing unit with a new ink may be performed so that normal printing can be performed after the ink replacement is completed. As the ink replacement operation, for example, printing is performed. The printing-off is printing for consuming ink and causing the ink replacement in the printing unit to proceed. In printing off, a solid image that consumes a lot of ink is printed.

  Further, after the ink cartridge is replaced, the ink cartridge may be used as it is without being replaced. In this case, after the ink cartridge is replaced, the original ink and the new ink are mixed in the printing unit by the consumption of the ink due to the execution of the print job and the supply of the new ink to supplement the consumed ink. Become. Each time a print job is executed, the ratio of new ink in the mixed color ink in the printing unit increases, and eventually the ink in the printing unit is completely replaced with new ink. In the period until the replacement with new ink is completed, the mixed color ink is used for printing.

  When the ink replacement operation is performed, the ink replacement completion determination is performed to determine whether or not to end the ink replacement operation. Even when the ink replacement operation is not performed, for example, determination of completion of ink replacement may be performed in order to notify the user that the ink color change has been completed.

  One method for determining the completion of ink replacement is a method using a scanner. In this method, first, the ink jet printing apparatus prints a determination patch using an ink jet head to be changed in ink color. Next, the inkjet printing apparatus reads the printed patch with a scanner to generate image data, and detects the print color of the patch from the image data. If the detected printing color of the patch is a new ink color, the inkjet printing apparatus determines that the ink replacement has been completed.

  In addition, there is a method in which an operator such as a serviceman makes a visual determination when there is no scanner. In this method, the operator visually compares the printed determination patch and the sample patch, and determines that the ink replacement has been completed if the two colors are the same. Here, the sample patch is printed in advance with the ink of the color after changing the ink color, for example, by another inkjet printing apparatus.

JP 2012-86489 A

  In the above-described method for visual determination by the operator, the type of paper on which the sample patch is printed may differ from the type of paper used for printing the determination patch. Here, the color reproduction range during printing differs depending on the paper type. For this reason, even if the replacement of ink is completed, the color of the patch for determination and the color of the sample patch may not be the same, and the operator may not be able to determine accurately.

  The present invention has been made in view of the above, and when changing the color of the ink ejected by the inkjet head, the determination accuracy when the operator determines the completion of the replacement with the new color ink is improved. It is an object of the present invention to provide an ink jet printing apparatus capable of performing the above.

  In order to achieve the above object, a first feature of an ink jet printing apparatus according to the present invention is that an at least one type of paper is held, a paper feed unit that feeds the held paper, and an ink jet head that ejects ink. And a plurality of printing sections each having an ink path for supplying ink to the inkjet head and discharging ink from the inkjet head onto a sheet fed by the sheet feeding section, and the plurality of printing sections Each having a replaceable ink cartridge that contains ink, and a plurality of ink supply units that supply the ink of the ink cartridge to the printing unit, and one of the plurality of printing units The ink cartridge of the ink supply unit corresponding to the printing unit whose ink color is to be changed contains ink of the color after the ink color change. In the case of replacing the ink cartridge, the ink color before the ink color change for the sample image printing paper type, which is the paper type used for printing the sample image to be used as a sample for determining the completion of the replacement of the ink in the printing unit to be changed. A determination image which is a paper type used for printing a color reproduction range by a combination of ink colors in the plurality of printing sections and a determination image to be printed at the time of completion of ink replacement in the printing section to be changed by the ink color A color within a common range with a color reproduction range by a combination of ink colors in the plurality of printing sections after changing the ink color for a printing paper type, and in a combination of ink colors in the plurality of printing sections after changing the ink color The target color is determined from the color printed using the ink of the color after the ink color is changed in the ink color change target printing unit. The sample image is printed on the sample image printing paper type paper with the target color by a combination of ink colors in the target color determination unit and the plurality of printing units before the ink color change, and the ink color change target When it is determined that the replacement of the ink in the printing unit subject to the ink color change is completed after replacement of the ink cartridge of the ink supply unit corresponding to the printing unit, the replacement of the ink in the printing unit subject to the ink color change is completed. And a print control unit for controlling each of the printing units to print the determination image on the paper of the determination image printing paper type by ink ejection control printed with the target color. is there.

  A second feature of the inkjet printing apparatus according to the present invention is that the target color determination unit changes the ink color in the printing unit that is the ink color change target in a combination of ink colors in the plurality of printing units after the ink color is changed. A target color is a color that is printed by using a later color ink more than other color inks.

  A third feature of the ink jet printing apparatus according to the present invention is that the target color determining unit sets the determination image printing paper type, and the ink color change target of the paper type held by the paper feeding unit. The printing color when printing on the paper of the judgment image printing paper type with the ink of the color after the ink color change in the printing unit is within the color reproduction range by the combination of the ink colors in the plurality of printing units before the ink color change. If there is a paper type to be included, the paper type is selected as the sample image printing paper type and printed on the paper of the determination image printing paper type with the ink of the color after the ink color change in the printing unit to be changed with the ink color The target print color is set as the target color, and among the types of paper held by the paper feed unit, the color of the ink after the ink color change in the print unit to be changed by the ink color is used for the determination. When there is no paper type that includes the print color when printing on the paper of the image printing paper type within the color reproduction range by the combination of ink colors in the plurality of printing units before the ink color change, the paper feeding unit holds Selecting one of the paper types as the sample image printing paper type, and a color reproduction range based on a combination of ink colors in the plurality of printing units before the ink color change for the sample image printing paper type, and the determination A color within a common range with a color reproduction range based on a combination of ink colors in the plurality of printing sections after changing the ink color for the image printing paper type, and the color after the ink color change in the printing section to be changed The target color is the color having the smallest color difference from the printing color when printing on the paper of the judgment image printing paper type.

  According to a fourth aspect of the inkjet printing apparatus of the present invention, the ink supply unit has an ink information acquisition unit that acquires information indicating the color of the ink from the ink cartridge, and the print control unit includes the ink information. If it is determined from the information acquired by the acquisition unit that the ink cartridge of the ink supply unit corresponding to the printing unit to be changed by the ink color has been replaced with an ink cartridge that stores ink of the color after the ink color change, Before starting the supply of ink from the ink cartridge to the printing unit, for the printing unit to be changed in ink color, the ink before ink color change remaining in the printing unit is used and the target color is used. The printing unit is controlled to print a sample image.

  A fifth feature of the ink jet printing apparatus according to the present invention is that the print control unit adjusts an ink amount when the determination image is printed in accordance with an elapsed time from printing the sample image.

  According to the first feature of the inkjet printing apparatus according to the present invention, the target color determination unit includes a color reproduction range based on a combination of ink colors in a plurality of printing units before changing the ink color for the sample image printing paper type, and a determination image. A color within a common range with a color reproduction range by a combination of ink colors in a plurality of print sections after changing the ink color for the print paper type, and an ink color in a combination of ink colors in a plurality of print sections after the ink color change The target color is determined from the color printed using the ink of the color after the ink color change in the printing unit to be changed. As described above, the target color determination unit sets the target color according to the color reproduction range of the sample image printing paper type and the determination image printing paper type. As a result, even when the sample image printing paper type and the determination image printing paper type are different, the color of the determination image can be made the same as the color of the sample image when the ink replacement is completed. As a result, it is possible to improve the determination accuracy when the operator determines completion of replacement with ink of a new color.

  According to the second feature of the ink jet printing apparatus according to the present invention, the target color determining unit is a combination of ink colors in a plurality of printing units after the ink color is changed, and after the ink color is changed in the printing unit to be changed. A target color is a color printed using a larger amount of the ink of the color than the ink of the other colors. As a result, it is possible to facilitate determination of completion of ink replacement by an operator and improve determination accuracy.

  According to the third feature of the ink jet printing apparatus according to the present invention, the target color determination unit includes the ink of the color after the ink color change in the print unit to be changed by the ink color among the paper types held by the paper feed unit. If there is a paper type that includes the print color when printing on the paper of the judgment image print paper type in the color reproduction range by the combination of ink colors in multiple printing sections before the ink color change, the sample image of that paper type Select as the print paper type. Then, the target color determination unit sets the target color as the print color when printing on the paper of the determination image printing paper type with the ink of the color after the ink color change in the printing unit to be changed.

  In addition, the target color determination unit performs printing when printing is performed on the paper of the judgment image printing paper type with the ink of the color after the ink color is changed in the printing unit to be changed by the ink in the paper type held by the paper feeding unit. If there is no paper type that includes the color within the color reproduction range of the combination of ink colors in the multiple printing units before changing the ink color, one of the paper types held by the paper supply unit is used as the sample image printing paper type select. Then, the target color determination unit includes a color reproduction range based on a combination of ink colors in a plurality of printing units before the ink color change for the sample image printing paper type, and a plurality of printing units after the ink color change for the determination image printing paper type. Print color when printing on paper of the judgment image printing paper type with a color within the common range with the color reproduction range by the combination of ink colors and after changing the ink color in the printing part to be changed The target color is the color with the smallest color difference from.

  This makes it easy to determine the completion of ink replacement by the operator by making the target color the color printed on the paper of the paper type of the paper after changing the ink color or the color as close as possible to the target color. It can be improved further.

  According to the fourth feature of the ink jet printing apparatus according to the present invention, the printing control unit determines that the ink cartridge of the ink supply unit corresponding to the printing unit to be changed is the ink color based on the information acquired by the ink information acquiring unit. If it is determined that the ink cartridge containing the changed color ink has been replaced, before the supply of the ink of the replaced ink cartridge to the printing unit is started, the printing unit for which the ink color is to be changed is included in the printing unit. A sample image is printed with the target color using the remaining ink before the ink color change. Accordingly, it is possible to prevent the ink in the printing unit to be changed in ink color from becoming mixed color ink before printing the sample image. As a result, the sample image can be reliably printed with the target color.

  According to the fifth feature of the ink jet printing apparatus according to the present invention, the ink amount at the time of printing the determination image is adjusted according to the elapsed time from the printing of the sample image. A judgment image can be printed with a high density. Thereby, the determination accuracy of the ink replacement completion determination by the operator can be further improved.

1 is a schematic configuration diagram of an inkjet printing apparatus according to a first embodiment. It is a control block diagram of the inkjet printing apparatus shown in FIG. It is a schematic block diagram of the ink circulation type printing unit of the inkjet printing apparatus shown in FIG. (A), (b) is explanatory drawing of a color profile. It is a figure which shows a red reproduction possibility table. It is a figure which shows the color reproduction range by CMYK. It is a figure which shows the color reproduction range by CRYK. It is a figure which shows the color reproduction range by CMYK and CRYK with respect to plain paper. It is a figure which shows the color reproduction range by CRYK with respect to plain paper, and the color reproduction range by CRYK with respect to mat paper. It is a flowchart for demonstrating operation | movement of an ink circulation type printing unit. It is a flowchart for demonstrating ink replenishment control. It is a flowchart for demonstrating pump operation | movement. It is a flowchart for demonstrating the operation | movement which prints a sample patch. It is explanatory drawing of an example of a target color. It is a figure which shows an example of the printing image of the paper on which the sample patch was printed. 6 is a flowchart for explaining the operation of the ink jet printing apparatus when ink replacement determination is performed. It is a figure which shows the change of the printing color of a determination patch. It is a figure which shows an ink amount ratio table.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Throughout the drawings, the same or equivalent parts and components are denoted by the same or equivalent reference numerals. However, it should be noted that the drawings are schematic and different from the actual ones. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the embodiment shown below exemplifies an apparatus or the like for embodying the technical idea of the present invention, and the technical idea of the present invention is the material, shape, structure, and arrangement of each component. Etc. are not specified below. The technical idea of the present invention can be variously modified within the scope of the claims.

(First embodiment)
FIG. 1 is a schematic configuration diagram of an inkjet printing apparatus according to a first embodiment of the present invention. FIG. 2 is a control block diagram of the ink jet printing apparatus shown in FIG. FIG. 3 is a schematic configuration diagram of an ink circulation type printing unit of the ink jet printing apparatus shown in FIG. In the following description, the direction orthogonal to the paper surface of FIG. 1 is the front-rear direction, and the front surface direction is the front. Also, the top, bottom, left, and right of the paper surface in FIG.

  In FIG. 1, a path indicated by a thick line is a transport path through which a sheet as a print medium is transported. Among the transport routes, a route indicated by a solid line is a normal route RC, a route indicated by a one-dot chain line is a reverse route RR, a route indicated by a broken line is a paper discharge route RD, and a route indicated by a two-dot chain line is a paper feed route RS.

  As shown in FIGS. 1 and 2, the inkjet printing apparatus 1 according to the first embodiment includes a paper feeding unit 2, a transport printing unit 3, an upper surface transport unit 4, a paper discharge unit 5, and a reversing unit 6. , An operation panel unit 7, a storage unit 8, a control unit 9, and a housing 10 that houses or holds each unit.

  The paper feeding unit 2 holds at least one type of paper and feeds the held paper P. The paper feed unit 2 is arranged on the most upstream side of the transport path. The paper feed unit 2 includes an external paper feed tray 11, an external paper feed roller 12, a plurality of internal paper feed stands 13, a plurality of internal paper feed rollers 14, a plurality of pairs of vertical transport rollers 15, and a registration roller 16. With.

  The external paper feed tray 11 is for loading paper P used for printing. The external paper feed tray 11 is partly exposed outside the housing 10.

  The external paper feed roller 12 takes out the paper P one by one from the external paper feed tray 11 and conveys it toward the registration rollers 16 along the paper feed path RS. The external paper feed roller 12 is driven by a motor (not shown).

  The internal paper feed tray 13 is for loading paper P used for printing. The internal paper feed tray 13 is disposed inside the housing 10.

  The internal paper feed roller 14 takes out the paper P one by one from the internal paper feed tray 13 and sends it out to the paper feed path RS. The internal paper feed roller 14 is driven by a motor (not shown).

  The vertical conveyance roller 15 conveys the paper P taken out from the internal paper feed tray 13 toward the registration roller 16. The vertical conveyance roller 15 is disposed along the paper feed path RS. The vertical conveying roller 15 is driven by a motor (not shown).

  The registration roller 16 temporarily stops the paper P conveyed from the external paper feed tray 11, the internal paper feed tray 13, and the reversing unit 6, and then transports the paper P toward a belt transport unit 21 described later. The registration roller 16 is disposed on the normal route RC in the vicinity of the junction point between the sheet feeding route RS and the reverse route RR. The registration roller 16 is driven by a motor (not shown).

  The transport printing unit 3 prints an image on the paper P while transporting the paper P fed by the paper feeding unit 2. The conveyance printing unit 3 includes a belt conveyance unit 21 and ink circulation type printing units 22A, 22B, 22C, and 22D.

  The belt conveyance unit 21 conveys the sheet P conveyed from the registration roller 16 by sucking and holding the sheet P on the belt. The belt conveyance unit 21 is driven by a motor (not shown).

  The ink circulation type printing units 22 </ b> A to 22 </ b> D discharge and print ink on the paper P conveyed by the belt conveyance unit 21. The ink circulation type printing units 22A to 22D eject inks of different colors.

  Specifically, the ink circulation printing units 22A, 22B, 22C, and 22D eject black (K), cyan (C), magenta (M), and yellow (Y) inks, respectively. However, the color of the ink ejected from the ink circulation printing units 22A to 22D can be changed by replacing the ink cartridge 32 described later. In the present embodiment, it is assumed that the ink color is changed from magenta to red (R) in the ink circulation printing unit 22C.

  The ink circulation printing units 22A to 22D have the same configuration except that the color of the ink to be ejected is different. For this reason, the alphabetic suffixes (A to D) indicating colors in the codes of the ink circulation printing units 22A to 22D may be omitted and collectively described.

  As shown in FIG. 3, the ink circulation printing unit 22 includes an ink supply unit 26, a printing unit 27, and an ink discharge unit 28.

  The ink supply unit 26 supplies ink to the printing unit 27. The ink supply unit 26 includes an ink cartridge mounting unit 31, an ink cartridge 32, an ink supply pipe 33, an ink supply valve 34, a cartridge atmosphere release pipe 35, and an air filter 36.

  The ink cartridge mounting portion 31 is for mounting the ink cartridge 32. The ink cartridge mounting portion 31 is configured so that the ink cartridge 32 can be attached and detached. The ink cartridge mounting unit 31 is provided with an ink information reading unit 37.

  The ink information reading unit 37 reads ink information from a tag (not shown) of the ink cartridge 32 mounted on the ink cartridge mounting unit 31. The ink information is information indicating the color of ink stored in the ink cartridge 32.

  The ink cartridge 32 contains ink to be supplied to the printing unit 27. The ink cartridge 32 contains the color ink ejected by the ink circulation printing unit 22 to which the ink cartridge 32 is mounted. The ink cartridge 32 can be attached to and detached from the ink cartridge mounting portion 31. A tag (not shown) holding ink information is attached to the ink cartridge 32.

  The ink supply pipe 33 connects the ink cartridge 32 attached to the ink cartridge attachment unit 31 and the downstream tank 51 of the ink circulation unit 39 described later. Ink flows from the ink cartridge 32 toward the downstream tank 51 through the ink supply pipe 33.

  The ink supply valve 34 opens and closes the ink flow path in the ink supply pipe 33. When supplying ink from the ink cartridge 32 to the downstream tank 51, the ink supply valve 34 is opened.

  The cartridge atmosphere release pipe 35 is for releasing the inside of the ink cartridge 32 attached to the ink cartridge attachment portion 31 to the atmosphere. The cartridge atmosphere release pipe 35 has one end connected to the ink cartridge 32 and the other end (open end) communicating with the atmosphere via the air filter 36.

  The air filter 36 prevents the entry of dust or the like in the outside air into the cartridge atmosphere release pipe 35, the upstream atmosphere release pipe 47 and the downstream atmosphere release pipe 52 of the ink circulation section 39 described later. The air filter 36 is connected to the open ends of the cartridge atmosphere release pipe 35, the upstream atmosphere release pipe 47, and the downstream atmosphere release pipe 52.

  The printing unit 27 performs printing by discharging the ink supplied from the ink supply unit 26 onto the paper P. The printing unit 27 includes an inkjet head 38 and an ink circulation unit (corresponding to an ink path in claims) 39.

  The ink jet head 38 ejects ink supplied by the ink circulation unit 39. The ink jet head 38 is disposed above the belt conveyance unit 21. The inkjet head 38 includes a plurality of head modules 41.

  The head module 41 includes an ink chamber that stores ink supplied by the ink circulation unit 39 and a plurality of nozzles (none of which are shown) that discharge ink in the ink chamber.

  The ink circulation unit 39 supplies ink to the inkjet head 38 while circulating the ink. The ink circulation unit 39 includes an upstream tank 46, an upstream atmosphere release pipe 47, an upstream atmosphere release valve 48, a distributor 49, a collector 50, a downstream tank 51, a downstream atmosphere release pipe 52, and a downstream atmosphere release. A valve 53, a pump 54, an ink temperature adjusting unit 55, and ink circulation pipes 56a, 56b, and 56c are provided.

  The upstream tank 46 stores ink to be supplied to the inkjet head 38. The ink in the upstream tank 46 is supplied to the inkjet head 38 via the ink circulation pipe 56 a and the distributor 49. The upstream tank 46 is disposed at a position higher than the inkjet head 38. Ink is supplied from the upstream tank 46 to the inkjet head 38 due to the water head difference based on this positional relationship. The upstream tank 46 is provided with an upstream upper limit sensor 58 and an upstream lower limit sensor 59.

  The upstream upper limit sensor 58 is for detecting whether or not the ink level in the upstream tank 46 has reached the upper limit. The upstream upper limit sensor 58 is disposed at the upper limit height position of the liquid level in the upstream tank 46. The upstream upper limit sensor 58 outputs a signal indicating “ON” when the ink level in the upstream tank 46 is equal to or higher than the upper limit height, and indicates “OFF” when the ink level is lower than the upper limit height. Is output.

  The upstream lower limit sensor 59 is for detecting whether or not the ink level in the upstream tank 46 is below the lower limit height. The upstream lower limit sensor 59 is disposed at the lower limit height position of the liquid level in the upstream tank 46. The upstream lower limit sensor 59 outputs a signal indicating “ON” when the ink level in the upstream tank 46 is equal to or higher than the lower limit height, and indicates “OFF” when it is less than the lower limit height. Is output.

  The upstream atmosphere release pipe 47 is for enabling the inside of the upstream tank 46 to be opened to the atmosphere. One end of the upstream atmosphere release pipe 47 is connected to the upstream tank 46, and the other end (open end) communicates with the atmosphere via the air filter 36.

  The upstream atmosphere release valve 48 opens and closes the air flow path in the upstream atmosphere release pipe 47. When the upstream atmosphere release valve 48 is opened, the upstream tank 46 is opened to the atmosphere.

  The distributor 49 distributes the ink supplied from the upstream tank 46 via the ink circulation pipe 56 a to each head module 41 of the inkjet head 38.

  The collector 50 collects ink that has not been consumed by the inkjet head 38 from each head module 41. The ink collected by the collector 50 flows to the downstream tank 51 via the ink circulation pipe 56b.

  The downstream tank 51 stores the ink supplied from the ink cartridge 32. The downstream tank 51 stores the ink collected from each head module 41 of the inkjet head 38 by the collector 50. The downstream tank 51 is disposed at a position lower than the inkjet head 38. The ink is returned from the inkjet head 38 to the downstream tank 51 by the water head difference based on this positional relationship. The downstream tank 51 is provided with a downstream upper limit sensor 61 and a downstream lower limit sensor 62.

  The downstream upper limit sensor 61 is for detecting whether the liquid level height of the ink in the downstream tank 51 has reached the upper limit height. The downstream upper limit sensor 61 is disposed at the upper limit height position of the liquid level in the downstream tank 51. The downstream upper limit sensor 61 outputs a signal indicating “ON” when the ink level in the downstream tank 51 is equal to or higher than the upper limit height, and indicates “OFF” when the ink level is lower than the upper limit height. Is output.

  The downstream lower limit sensor 62 is for detecting whether or not the ink level in the downstream tank 51 is lower than the lower limit height. The downstream lower limit sensor 62 is disposed at the lower limit height position of the liquid level in the downstream tank 51. The downstream lower limit sensor 62 outputs a signal indicating “ON” when the ink level in the downstream tank 51 is equal to or higher than the lower limit height, and indicates “OFF” when the ink level is lower than the lower limit height. Is output.

  The downstream atmosphere release pipe 52 is for enabling the inside of the downstream tank 51 to be opened to the atmosphere. One end of the downstream atmosphere release pipe 52 is connected to the downstream tank 51, and the other end (open end) communicates with the atmosphere via the air filter 36.

  The downstream atmosphere release valve 53 opens and closes the air flow path in the downstream atmosphere release pipe 52. When the downstream atmosphere release valve 53 is opened, the downstream tank 51 is opened to the atmosphere.

  The pump 54 sends ink from the downstream tank 51 to the upstream tank 46. The pump 54 is provided in the middle of the ink circulation pipe 56c.

  The ink temperature adjustment unit 55 adjusts the ink temperature in the ink circulation unit 39. The ink temperature adjustment unit 55 is provided in the middle of the ink circulation pipe 56c. The ink temperature adjustment unit 55 includes a heater 65 that heats ink and a cooler 66 that cools ink.

  The ink circulation pipe 56 a connects the upstream tank 46 and the distributor 49. Ink flows from the upstream tank 46 toward the distributor 49 in the ink circulation pipe 56a. The ink circulation pipe 56 b connects the collector 50 and the downstream tank 51. Ink flows from the collector 50 toward the downstream tank 51 through the ink circulation pipe 56b. The ink circulation pipe 56 c connects the downstream tank 51 and the upstream tank 46. Ink flows from the downstream tank 51 toward the upstream tank 46 in the ink circulation pipe 56c.

  The ink discharge unit 28 discharges ink from the printing unit 27 and discards it. The ink discharge unit 28 includes an ink discharge pipe 67, an ink discharge valve 68, and a waste liquid tank 69.

  The ink discharge pipe 67 guides the ink discharged from the printing unit 27 to the waste liquid tank 69. One end of the ink discharge pipe 67 is connected to the downstream tank 51, and the other end is connected to the waste liquid tank 69.

  The ink discharge valve 68 opens and closes the ink flow path in the ink discharge pipe 67. When discharging ink from the ink circulation unit 39, the ink discharge valve 68 is opened.

  The waste liquid tank 69 stores ink that is discharged from the ink circulation unit 39 through the ink discharge pipe 67 and discarded.

  The upper surface transport unit 4 transports the paper P transported by the belt transport unit 21 so as to make a U-turn from the right direction to the left direction. The upper surface transport unit 4 includes a plurality of pairs of upper surface transport rollers 71.

  The upper surface transport roller 71 transports the paper P along the transport path. The most downstream upper surface conveyance roller 71 is disposed in the upstream portion of the reversing path RR. The other upper surface conveyance roller 71 is disposed along the normal path RC between the belt conveyance unit 21 and the paper discharge unit 5. The upper surface conveyance roller 71 is driven by a motor (not shown).

  The paper discharge unit 5 discharges the printed paper P. The paper discharge unit 5 includes a switching unit 76, a paper discharge roller 77, and a paper discharge stand 78.

  The switching unit 76 switches the transport path of the paper P between the paper discharge path RD and the reverse path RR. The switching unit 76 is disposed at a branch point between the paper discharge route RD and the reverse route RR. The switching unit 76 is driven by a solenoid (not shown).

  The paper discharge roller 77 conveys the paper P guided to the paper discharge path RD by the switching unit 76 and discharges it to the paper discharge stand 78. The paper discharge roller 77 is disposed between the switching unit 76 and the paper discharge stand 78 along the paper discharge path RD. The paper discharge roller 77 is driven by a motor (not shown).

  The paper discharge stand 78 is for stacking printed paper P discharged by the paper discharge roller 77. The paper discharge stand 78 has a tray shape protruding from the housing 10 and is inclined.

  The reversing unit 6 reverses the single-side printed paper P and conveys it to the registration roller 16 during double-sided printing. The reversing unit 6 includes a reversing roller 81, a switchback unit 82, a refeed roller 83, and a switching gate 84.

  The reverse roller 81 temporarily transports the paper P transported by the upper surface transport roller 71 of the upper surface transport unit 4 to the switchback unit 82 and then transports it to the refeed roller 83. The reverse roller 81 is disposed on the reverse path RR between the most downstream upper surface transport roller 71 and the carry-in port of the switchback unit 82. The reverse roller 81 is driven by a motor (not shown).

  The switchback unit 82 is a space for the reversing roller 81 to carry in the paper P temporarily. The switchback portion 82 is formed at the lower portion of the paper discharge stand 78. The switchback unit 82 is opened near the reversing roller 81 for carrying the paper P therein.

  The re-feed roller 83 conveys the paper P conveyed by the reversing roller 81 to the registration roller 16. The refeed roller 83 is disposed on the reverse path RR between the reverse roller 81 and the registration roller 16. The refeed roller 83 is driven by a motor (not shown).

  The switching gate 84 guides the paper P conveyed by the upper surface conveyance roller 71 to the reverse roller 81. Further, the switching gate 84 guides the paper P carried out from the switchback unit 82 by the reversing roller 81 to the refeed roller 83. The switching gate 84 is disposed in the vicinity of the center of gravity at the three locations of the uppermost conveying roller 71, the reverse roller 81, and the refeed roller 83.

  The operation panel unit 7 displays various input screens and accepts input operations by the user. The operation panel unit 7 includes a display unit 86 and an input unit 87.

  The display unit 86 displays images such as various input screens. The display unit 86 includes a liquid crystal display panel and the like.

  The input unit 87 accepts an input operation by the user and outputs an operation signal corresponding to the operation. The input unit 87 includes various operation keys, a touch panel, and the like.

  The storage unit 8 includes an HDD (Hard Disk Drive) or the like. The storage unit 8 stores various programs.

  The storage unit 8 stores a color profile. The color profile indicates a correspondence relationship when converting the RGB value of each pixel in RGB format image data to be printed into a value corresponding to the ink color used for printing.

  Here, as described above, in the ink jet printing apparatus 1, the ink color may be changed from magenta (M) to red (R) in the ink circulation printing unit 22C. Therefore, the storage unit 8 stores a CMYK color profile and a CRYK color profile for each paper type.

  The color profile for CMYK shows the correspondence between RGB values and CMYK values as shown in FIG. The color profile for CRYK shows the correspondence between RGB values and CRYK values as shown in FIG. In FIGS. 4A and 4B, RGB values are values of 256 gradations, respectively. The values of CMYK and CRYK are values expressed as a ratio to the maximum density of each color.

  The storage unit 8 also stores a red reproducibility table 90 shown in FIG. The red reproducibility table 90 includes, for each paper type used as a sample patch printing paper type (corresponding to the sample image printing paper type in the claims), a determination patch printing paper type (a judgment image printing paper type in the claims) with red ink. This is a table indicating whether or not the red printing color when printed on the paper P can be reproduced with a combination of CMYK ink colors.

  The sample patch printing paper type is a paper type used for printing a sample patch (corresponding to a sample image in claims). The sample patch printing paper type is selected from plain paper, matte paper, glossy paper, and the like. The sample patch is a sample patch for an operator to determine the completion of replacement of ink in the printing unit 27 of the ink circulation type printing unit 22C when the ink color is changed in the ink circulation type printing unit 22C. . The sample patch is a solid image that is printed with a target color determined by a target color determination unit 91 described later, using a combination of CMYK ink colors.

  The determination patch printing paper type is a paper type used for printing a determination patch (corresponding to a determination image in claims). In this embodiment, plain paper is set as the judgment patch printing paper type. In other words, the red reproducibility table 90 can reproduce the red printing color when printing on plain paper with red ink for each paper type used as the sample patch printing paper type, with a combination of CMYK ink colors. Indicates whether or not. The determination patch is a solid image that is printed so that the print color becomes the target color if the ink replacement is completed when the ink replacement is determined in the ink circulation printing unit 22C.

  Here, the color reproduction range will be described.

The color reproduction range varies depending on the combination of ink colors used for printing. Also, the color reproduction range varies depending on the paper type used for printing. FIG. 6 is a diagram showing a color reproduction range by CMYK on the a ^* b ^* plane of the L ^* a ^* b ^* display system. FIG. 7 is a diagram similarly showing a color reproduction range by CRYK. 6 and 7 respectively show the color reproduction range for plain paper and the color reproduction range for matte paper. 6 and 7, the range surrounded by the broken thick line is the color reproduction range for plain paper. Further, a range surrounded by a dashed-dotted thick line is a color reproduction range for mat paper.

  As can be seen from FIGS. 6 and 7, the mat paper has a wider color reproduction range than the plain paper. Also, CRYK is superior in reproducibility of the red (R) color gamut compared to CMYK. On the other hand, CRYK has lower reproducibility of the color gamut of blue (B) and magenta (M) than CMYK.

  Any combination of CMYK and CRYK ink colors can be used as long as the color is within the common range of the CMYK color reproduction range and the CRYK color reproduction range for the same paper type. For example, in the case of plain paper, any color within the color gamut 100 shown in FIG. 8 can be reproduced in either CMYK or CRYK. The color gamut 100 is a common range of the color reproduction range by CMYK for plain paper shown in FIG. 6 and the color reproduction range by CRYK for plain paper shown in FIG.

  On the other hand, the colors in the color gamut 101 shown in FIG. 8 can be reproduced by CMYK but cannot be reproduced by CRYK. The color gamut 101 is a color gamut that is included in the color reproduction range of CMYK for plain paper but is not included in the color reproduction range of CRYK for plain paper. In addition, colors in the color gamut 102 can be reproduced by CRYK, but cannot be reproduced by CMYK. The color gamut 102 is a color gamut that is included in the color reproduction range by CRYK for plain paper but is not included in the color reproduction range by CMYK for plain paper.

  The print color of plain paper with red ink is a color within the color gamut 102 and is indicated by a point Ar in FIG. In other words, the printing color of the plain paper with the red ink cannot be reproduced with a combination of CMYK ink colors for the plain paper. Therefore, in the red reproducibility table 90, when the sample patch printing paper type is plain paper, red cannot be reproduced.

  In the present embodiment, as shown in FIG. 9, the color reproduction range by CMYK for plain paper is included in the color reproduction range by CRYK for matte paper. Therefore, the point Ar is included in the color reproduction range by CRYK for the matte paper. Therefore, in the red reproducibility table 90, red can be reproduced when the sample patch printing paper type is matte paper.

  The storage unit 8 also stores patch image data of a target color in RGB format generated by a target color determination unit 91 described later.

  The control unit 9 performs control processing in the inkjet printing apparatus 1. The control unit 9 includes a CPU, a RAM, a ROM, and the like. The control unit 9 includes a target color determination unit 91, a print control unit 92, and a display control unit 93. Each unit of the control unit 9 is configured by the CPU operating according to a program stored in the storage unit 8 or the like.

  The target color determination unit 91 determines a target color when the ink color is changed in the ink circulation type printing unit 22C. The target color is the print color of the sample patch. The target color is the same as the print color of the determination patch when the ink replacement in the printing unit 27 of the ink circulation type printing unit 22C is completed when the ink color is changed in the ink circulation type printing unit 22C. Is a color.

  The target color determination unit 91 is a color within the common range of the color reproduction range by CMYK for the sample patch printing paper type and the color reproduction range by CRYK for the judgment patch printing paper type, and is red in the combination of CRYK ink colors. A target color is determined from a color printed using ink. Here, in this embodiment, the target color determination unit 91 sets plain paper as the determination patch printing paper type.

  Specifically, the target color determining unit 91 changes the ink color in the ink circulation type printing unit 22 </ b> C among the paper types that the paper feeding unit 2 holds on the external paper feeding tray 11 and the plurality of internal paper feeding trays 13. In the case where there is a paper type that includes the printing color when printing on plain paper with red ink, which is the same ink, in the color reproduction range by CMYK, the paper type is selected as the sample patch printing paper type. Then, the target color determining unit 91 determines the print color when printing on plain paper with red ink as the target color.

  On the other hand, the target color determination unit 91 supplies the paper type held by the paper supply unit 2 when there is no paper type that includes the print color when printing on plain paper with red ink within the color reproduction range by CMYK. One of the paper types held by the paper unit 2 is selected as the sample patch printing paper type. Then, the target color determination unit 91 is a color within the common range of the color reproduction range by CMYK for the selected sample patch printing paper type and the color reproduction range by CRYK for plain paper, and printed on plain paper with red ink. The color having the smallest color difference from the current print color is determined as the target color.

  Here, the color reproduction range by CMYK means a color reproduction range by a combination of ink colors in the ink circulation printing units 22A to 22D before the ink color change in the ink circulation printing unit 22C. The color reproduction range by CRYK means a color reproduction range by a combination of ink colors in the ink circulation printing units 22A to 22D after the ink color change in the ink circulation printing unit 22C.

  When the target color is determined, the target color determination unit 91 generates patch image data of the target color in the RGB format, and stores this in the storage unit 8.

  The print control unit 92 controls operations of paper feed, conveyance, printing, and paper discharge during printing in the inkjet printing apparatus 1. Specifically, the print control unit 92 controls the paper feed unit 2 to feed the paper P to the transport printing unit 3. The print control unit 92 controls the transport printing unit 3 to print an image on the paper P while transporting the fed paper P. Further, the print control unit 92 controls the upper surface transport unit 4 and the reversing unit 6 to transport the paper P. The print control unit 92 controls the paper discharge unit 5 to discharge the paper P.

  When the ink color is changed in the ink circulation type printing unit 22C, the print control unit 92 prints the sample patch on the paper P of the sample patch printing paper type with the target color by the combination of the CMYK ink colors before the ink color change. The sheet feeding unit 2 and the conveyance printing unit 3 are controlled to do so.

  Specifically, when the print control unit 92 determines that the magenta ink cartridge 32 has been replaced with the red ink cartridge 32 from the information acquired by the ink information acquisition unit 37 of the ink circulation printing unit 22C, the printing unit 27 Before starting to supply red ink to the printer, the sample patch is printed with the target color. At this time, the print control unit 92 converts the target color patch image data in the RGB format into the CMYK format using the CMYK color profile corresponding to the sample patch printing paper type. Next, the print control unit 92 converts the patch image data in the CMYK format into drop data. This is the drop data for sample patch printing. The drop data is data indicating the number of ink droplets (the number of drops) ejected to each pixel. Then, the print control unit 92 controls the ink ejection in the ink jet heads 38 of the ink circulation printing units 22A to 22D based on the drop data for sample patch printing, and prints the sample patch.

  Here, in the ink circulation type printing unit 22C, before the supply of the red ink to the printing unit 27 is started, the magenta ink remaining in the printing unit 27 is used for printing the sample patch.

  In addition, the print control unit 92 performs determination patch printing of a determination patch by ink ejection control that is printed with a target color when ink replacement is completed when the ink replacement is completed in the ink circulation printing unit 22C. The paper feed unit 2 and the transport printing unit 3 are controlled so as to print on plain paper as the paper type.

  Specifically, the print control unit 92 converts the patch image data of the target color in the RGB format into the CRYK format using the CRYK color profile corresponding to the plain paper. Next, the print control unit 92 converts the CRYK format patch image data into drop data. This is the drop data for determination patch printing. Then, the print control unit 92 controls the ink ejection in the inkjet heads 38 of the ink circulation printing units 22A to 22D based on the drop data for the determination patch printing, and prints the determination patch on plain paper.

  The display control unit 93 controls the display unit 86 to display an image.

  Next, the operation of the inkjet printing apparatus 1 will be described.

  When printing is performed in the inkjet printing apparatus 1, unprinted paper P is transported to the registration roller 16 from either the external paper feed tray 11 or the plurality of internal paper feed trays 13 of the paper feed unit 2, and the paper is transferred by the registration roller 16. P is conveyed to the belt conveyance unit 21. The paper P is printed by the ink ejected from the ink jet heads 38 of the ink circulation type printing units 22 </ b> A to 22 </ b> D while being transported by the belt transport unit 21. The printed paper P is conveyed from the belt conveyance unit 21 to the upper surface conveyance unit 4, and is conveyed by the upper surface conveyance roller 71 in the upper surface conveyance unit 4.

  Here, in the case of single-sided printing, the paper P is guided from the normal route RC to the paper discharge route RD by the switching unit 76 of the paper discharge unit 5. Then, the paper P is discharged onto a paper discharge stand 78 by a paper discharge roller 77.

  On the other hand, in the case of duplex printing, the paper P is guided from the normal route RC to the reverse route RR by the switching unit 76 of the paper discharge unit 5. The paper P guided to the reversing path RR is guided to the reversing roller 81 by the switching gate 84 in the reversing unit 6, and is carried into the switchback unit 82 by the reversing roller 81. Thereafter, the paper P is unloaded from the switchback unit 82 by the reverse roller 81 and guided to the refeed roller 83 by the switching gate 84. The paper P is conveyed to the registration roller 16 by the refeed roller 83 and is conveyed to the belt conveyance unit 21 by the registration roller 16.

  Here, since the paper P is reversed by the reversing unit 6, the unprinted surface is facing upward. The sheet P is printed on the unprinted surface by the ink ejected from the inkjet head 38 while being conveyed by the belt conveyance unit 21. Then, the double-side printed paper P is transported to the paper discharge unit 5 by the upper surface transport unit 4 and is discharged to the paper discharge stand 78 in the paper discharge unit 5.

  Next, the operation of the ink circulation type printing unit 22 at the time of printing described above will be described with reference to the flowchart of FIG.

  In step S <b> 1 of FIG. 10, the print control unit 92 closes the downstream atmosphere release valve 53. In addition, the printing control unit 92 opens the upstream air release valve 48. Here, in the standby state before printing, the downstream atmosphere release valve 53 is open and the upstream atmosphere release valve 48 is closed.

  Next, in step S2, the print control unit 92 starts ink supply control. The ink supply control will be described later.

  Next, in step S <b> 3, the print control unit 92 starts a pump operation. The pump operation will be described later.

  Next, in step S <b> 4, the print control unit 92 starts a printing operation by the inkjet head 38.

  Next, in step S <b> 5, the print control unit 92 determines whether the printing operation by the inkjet head 38 has been completed. When it is determined that the printing operation has not ended (step S5: NO), the print control unit 92 repeats step S5.

  If it is determined that the printing operation has been completed (step S5: YES), in step S6, the printing control unit 92 ends the pump operation.

  Next, in step S7, the print control unit 92 ends the ink supply control.

  Next, in step S <b> 8, the print control unit 92 closes the upstream atmosphere release valve 48. In addition, the print control unit 92 opens the downstream atmosphere release valve 53. As a result, the operation of the ink circulation type printing unit 22 at the time of printing ends, and a standby state is entered.

  Next, the ink supply control started in step S2 of FIG. 10 described above will be described. The ink replenishment control is performed in order to replenish ink in the printing unit 27 that decreases due to ink ejection by the inkjet head 38. FIG. 11 is a flowchart for explaining the ink supply control.

  In step S11 of FIG. 11, the print control unit 92 determines whether or not the downstream lower limit sensor 62 is off. Here, the liquid level in the upstream tank 46 is maintained near the upper limit height by a pump operation described later. Ink is sent from the downstream tank 51 to the upstream tank 46 by the pump 54. For this reason, when the ink in the printing unit 27 decreases, the liquid level in the downstream tank 51 falls, and the downstream lower limit sensor 62 is turned off before long.

  If it is determined that the downstream lower limit sensor 62 is on (step S11: NO), the print control unit 92 repeats step S11.

  If it is determined that the downstream lower limit sensor 62 is off (step S11: YES), the print control unit 92 opens the ink supply valve 34 in step S12. Thereby, the supply of ink from the ink cartridge 32 to the downstream tank 51 is started.

  Next, in step S <b> 13, the print control unit 92 determines whether or not the downstream upper limit sensor 61 is on. If it is determined that the downstream upper limit sensor 61 is off (step S13: NO), the print control unit 92 repeats step S13.

  When it is determined that the downstream upper limit sensor 61 is on (step S13: YES), the print control unit 92 closes the ink supply valve 34 in step S14. As a result, the supply of ink from the ink cartridge 32 to the downstream tank 51 is stopped. Thereafter, the print control unit 92 returns to step S11.

  The print controller 92 ends the ink supply control of FIG. 11 when the ink supply control is ended in step S7 of FIG. If the ink supply valve 34 is open at this point, the print control unit 92 closes the ink supply valve 34 and ends the ink supply control.

  Next, the pump operation started in step S3 of FIG. 10 described above will be described with reference to the flowchart of FIG.

  In step S21 in FIG. 12, the print control unit 92 determines whether or not the upstream upper limit sensor 58 is off. When it is determined that the upstream upper limit sensor 58 is on (step S21: NO), the print control unit 92 repeats step S21.

  If it is determined that the upstream upper limit sensor 58 is off (step S21: YES), the print control unit 92 starts driving the pump 54 in step S22. As a result, ink starts to be supplied from the downstream tank 51 to the upstream tank 46, and ink circulation by the ink circulation unit 39 starts.

  Next, in step S <b> 23, the print control unit 92 determines whether or not the upstream upper limit sensor 58 is on. If it is determined that the upstream upper limit sensor 58 is off (step S23: NO), the print control unit 92 repeats step S23.

  If it is determined that the upstream upper limit sensor 58 is on (step S23: YES), the print control unit 92 stops the pump 54 in step S24. As a result, the supply of ink from the downstream tank 51 to the upstream tank 46 is stopped, and the ink circulation in the ink circulation unit 39 is stopped.

  Next, in step S25, the print controller 92 determines whether or not a specified time has elapsed since the pump 54 was stopped in step S24. This specified time is a time for waiting for the liquid level in the upstream tank 46 to stabilize. This specified time is, for example, 1 second.

  If it is determined that the specified time has not yet elapsed since the pump 54 was stopped (step S25: NO), the print control unit 92 repeats step S25.

  If it is determined that the specified time has elapsed since the pump 54 was stopped (step S25: YES), the print control unit 92 returns to step S21.

  The print control unit 92 ends the pump operation of FIG. 12 when the pump operation is ended in step S6 of FIG. If the pump 54 is being driven at this time, the print control unit 92 stops the pump 54 and ends the pump operation.

  Next, an operation for printing a sample patch when an ink color change is performed in the ink circulation type printing unit 22C will be described with reference to a flowchart of FIG.

  Here, when the ink color is changed in the ink circulation type printing unit 22 </ b> C, an operator such as a service person performs an operation for notifying the inkjet printing apparatus 1 that the ink color is changed on the input unit 87. Thereafter, the worker performs an operation of replacing the magenta ink cartridge 32 mounted on the ink cartridge mounting portion 31 of the ink circulation type printing unit 22C with the red ink cartridge 32.

  The process of the flowchart of FIG. 13 is started when the inkjet printing apparatus 1 receives an operation for notifying the operator that the ink color is changed.

  In step S31 of FIG. 13, the target color determination unit 91 uses CMYK to determine the print color when printing on plain paper, which is the determination patch print paper type, with red ink among the paper types held by the paper feed unit 2. It is determined whether there is a paper type included in the color reproduction range.

  Specifically, the target color determination unit 91 determines whether there is a paper type that can reproduce red in the red reproduction possibility table 90 among the paper types held by the paper feeding unit 2. . If there is a paper type that can be reproduced in red in the red reproducibility table 90 among the paper types held by the paper feed unit 2, the target color determination unit 91 determines the paper type that the paper feed unit 2 holds. Among them, it is determined that there is a paper type that includes the printing color when printing on plain paper with red ink within the color reproduction range by CMYK.

  If it is determined that among the paper types held by the paper supply unit 2 is a paper type that includes the printing color when printing on plain paper with red ink within the color reproduction range by CMYK (step S31: YES), step In S32, the target color determination unit 91 selects the paper type as the sample patch print paper type.

  Next, in step S33, the print color when printing on plain paper with red ink is determined as the target color. When the target color is determined, the target color determination unit 91 generates patch image data of the target color in the RGB format, and stores this in the storage unit 8.

  For example, it is assumed that matte paper is held in the paper feed unit 2. As described above, the print color of the plain paper with the red ink is included in the color reproduction range of the mat paper with CMYK. Therefore, in this case, the target color determination unit 91 can select the matte paper as the sample patch printing paper type. When the mat paper is selected as the sample patch printing paper type, the target color determination unit 91 determines the printing color of the red ink for the plain paper indicated by the point Ar in FIGS. 8 and 9 as the target color.

  In the inkjet printing apparatus 1, plain paper is set as the determination patch print paper type, and it is assumed that the plain paper is held in the paper feed unit 2.

  Returning to FIG. 13, when it is determined that there is no paper type included in the color reproduction range by CMYK when printing on plain paper with red ink among the paper types held by the paper feed unit 2 (step S31). In step S34, the target color determination unit 91 selects one of the sheet types held by the sheet feeding unit 2 as the sample patch printing sheet type.

  Next, in step S35, the target color determination unit 91 is a color within the common range of the color reproduction range by CMYK for the selected sample patch printing paper type and the color reproduction range by CRYK for plain paper, and is normal with red ink. A color having the smallest color difference from the print color when printed on paper is determined as the target color. When the target color is determined, the target color determination unit 91 generates patch image data of the target color in the RGB format, and stores this in the storage unit 8.

  For example, it is assumed that the paper type held in the paper supply unit 2 is only plain paper. In this case, plain paper is selected as the sample patch printing paper type. As shown in FIG. 8, the printing color with red ink for plain paper indicated by the point Ar is not included in the color reproduction range with CMYK for plain paper. Therefore, in this case, a color that is within the color gamut 100 and has the smallest color difference from the color indicated by the point Ar, such as the color indicated by the point At shown in FIG. 14, is determined as the target color. .

  Returning to FIG. 13, after step S33 or step S35, in step S36, the print control unit 92 determines that the magenta ink cartridge 32 is red based on the ink information from the ink information reading unit 37 of the ink circulation type printing unit 22C. It is determined whether or not the ink cartridge 32 has been replaced. If it is determined that the ink cartridge 32 has not been replaced (step S36: NO), the print control unit 92 repeats step S36.

  If it is determined that the ink cartridge 32 has been replaced (step S36: YES), in step S37, the print control unit 92 prints a sample patch.

  Specifically, the print control unit 92 converts the patch image data of the target color in the RGB format into the CMYK format using the CMYK color profile corresponding to the sample patch printing paper type. Next, the print control unit 92 converts the patch image data in the CMYK format into drop data. This is the drop data for sample patch printing. In addition, the print control unit 92 feeds the paper P of the sample patch printing paper type from the paper feed unit 2. Then, the print control unit 92 causes the sample patches to be printed on the paper P conveyed by the belt conveyance unit 21 by the ink circulation type printing units 22A to 22D. At this time, the print control unit 92 controls the inkjet heads 38 of the ink circulation printing units 22A to 22D based on the drop data for sample patch printing. The paper P on which the sample patch is printed is transported to the paper discharge unit 5 by the upper surface transport unit 4, and is discharged to the paper discharge stand 78 in the paper discharge unit 5.

  Here, when the magenta ink cartridge 32 is replaced with the red ink cartridge 32 in the ink circulation type printing unit 22 </ b> C, the magenta ink remains in the printing unit 27. Specifically, magenta ink remains in each of the ink chamber, the distributor 49, the collector 50, and the ink circulation pipes 56a to 56c of the upstream tank 46, the downstream tank 51, and each head module 41 of the inkjet head 38. ing.

  When printing the sample patch, the print control unit 92 causes the ink circulation printing units 22A to 22D to print the sample patch by the same operation as the operation described in the flowchart of FIG. However, the print controller 92 does not perform the ink replenishment control started in step S2 in the ink circulation printing unit 22C. As a result, the supply of red ink from the ink cartridge 32 is not started, and the sample patch is printed using the magenta ink remaining in the printing unit 27 of the ink circulation type printing unit 22C. That is, a sample patch is printed by a combination of CMYK ink colors.

  An example of the print image of the paper P on which the sample patch is printed is shown in FIG. In the example of FIG. 15, a message 107 is printed together with the sample patch 106. The message 107 includes an operation guide for determining completion of ink replacement in the ink circulation type printing unit 22C. Further, the message 107 includes information indicating the determination patch printing paper type and the ink configuration at the time of printing the determination patch as the determination patch printing conditions. The information indicating the ink configuration is for enabling the operator to manually set the target color when the patch image data of the target color is deleted from the storage unit 8 for some reason. The sheet P on which the sample patch is printed is stored by an administrator of the inkjet printing apparatus 1 or the like.

  By the way, the magenta ink cartridge 32 of the ink circulation printing unit 22C may be replaced with the red ink cartridge 32 while the power of the ink jet printing apparatus 1 is off. In this case, when the power is turned on, the print control unit 92 determines that the magenta ink cartridge 32 has been replaced with the red ink cartridge 32 from the ink information from the ink information reading unit 37 of the ink circulation type printing unit 22C. .

  Next, the target color determination unit 91 determines the target color by the processing in steps S31 to S35 in FIG. 13 described above. Then, the print control unit 92 prints a sample patch before starting to supply red ink to the printing unit 27 of the ink circulation printing unit 22C.

  After printing the sample patch, the ink jet printing apparatus 1 is used as usual. That is, the inkjet printing apparatus 1 performs printing when a print job is input. Specifically, the print control unit 92 expands image data from the print job, and generates drop data based on the image data. At this time, the print control unit 92 uses a color profile for CRYK. Then, the print control unit 92 causes the ink circulation printing units 22 </ b> A to 22 </ b> D to print an image on the paper P conveyed by the belt conveyance unit 21. Here, the print control unit 92 controls the ink-jet heads 38 of the ink circulation printing units 22A to 22D based on the drop data.

  At this time, the print control unit 92 causes the ink circulation printing units 22A to 22D to print images by the same operation as the operation described in the flowchart of FIG. Here, in the ink circulation type printing unit 22C to be changed in ink color, red ink is supplied from the ink cartridge 32 to the printing unit 27 by the ink supply control described with reference to the flowchart of FIG. As a result, the ink in the printing unit 27 is replaced from magenta ink to red ink. In the period until the replacement with the red ink is completed, the mixed-color ink is ejected from the inkjet head 38 of the ink circulation printing unit 22C instead of the red ink.

  In such a situation where the ink jet printing apparatus 1 is used, it is determined whether or not the ink replacement in the printing unit 27 of the ink circulation type printing unit 22C to be changed is completed. This ink replacement determination is performed, for example, by a serviceman to notify the user that the ink color change has been completed. When executing this ink replacement determination, an operator such as a service person performs an operation for instructing the start of the ink replacement determination on the input unit 87.

  The operation of the inkjet printing apparatus 1 when this ink replacement determination is performed will be described with reference to the flowchart of FIG.

  In step S41 of FIG. 16, the print control unit 92 determines whether or not an instruction to start ink replacement determination has been issued. If it is determined that the start of ink replacement determination is not instructed (step S41: NO), the print control unit 92 repeats step S41.

  If it is determined that the start of ink replacement determination has been instructed (step S41: YES), in step S42, the print control unit 92 prints the determination patch.

  Specifically, the print control unit 92 converts the patch image data of the target color in the RGB format into the CRYK format using the CRYK color profile corresponding to the plain paper. Next, the print control unit 92 converts the CRYK format patch image data into drop data. This is the drop data for determination patch printing. Further, the print control unit 92 feeds the paper P, which is plain paper, from the paper feeding unit 2. Then, the print control unit 92 causes the ink circulation printing units 22 </ b> A to 22 </ b> D to print the determination patch on the paper P conveyed by the belt conveyance unit 21. Here, the print control unit 92 controls the inkjet heads 38 of the ink circulation printing units 22A to 22D based on the drop data for determination patch printing. The paper P on which the determination patch is printed is transported to the paper discharge unit 5 by the upper surface transport unit 4 and is discharged to the paper discharge stand 78 by the paper discharge unit 5.

  Further, the display control unit 93 causes the display unit 86 to display an ink replacement determination result reception screen (not shown) that receives an input of the determination result of the ink replacement determination. An ink replacement completion button is displayed on the ink replacement determination result reception screen. The ink replacement completion button is for receiving an input of a determination result that ink replacement in the ink circulation printing unit 22C is completed. In addition, an ink replacement incomplete button is displayed on the ink replacement determination result reception screen. The ink replacement incomplete button is for receiving an input of a determination result that the ink replacement in the ink circulation printing unit 22C is not completed.

  When the determination patch is printed, the operator visually compares the determination patch with the sample patch. Then, if the printing color of the determination patch is the same as the printing color of the sample patch, the operator determines that the ink replacement has been completed. The operator inputs the determination result on the ink replacement determination result reception screen.

  Subsequent to step S42, in step S43, the print control unit 92 determines whether or not the ink replacement has been completed based on the input operation of the determination result by the operator. If it is determined that the ink replacement has not been completed (step S43: NO), the print control unit 92 returns to step S41. If it is determined that the ink replacement has been completed (step S43: YES), the print control unit 92 ends the series of operations.

  Here, as described above, at the time of printing the determination patch, the print control unit 92 generates drop data for determination patch printing from the patch image data of the target color using the color profile for CRYK. . For this reason, if the replacement of the ink in the printing unit 27 with the red ink is completed in the ink circulation type printing unit 22C, the determination patch is printed in the target color.

  On the other hand, when the ink replacement is not completed, the mixed color ink is ejected from the inkjet head 38 of the ink circulation type printing unit 22C instead of the red ink. For this reason, the print color of the determination patch is different from the target color.

  For example, assume that the color represented by the point At shown in FIG. 17 is the target color. When mixed color ink is ejected from the ink circulation printing unit 22C, the printing color of the determination patch is different from the target color, for example, a color represented by a point Ab. As the ink replacement in the printing unit 27 of the ink circulation type printing unit 22C progresses and the ratio of the red ink in the mixed color ink increases, the printing color of the determination patch approaches the target color represented by the point At. When the ink replacement is completed, the print color of the determination patch becomes the target color.

  When the sample patch is printed as described above, the ink in the printing unit 27 of the ink circulation type printing unit 22C may be replaced by an ink replacement operation instead of using the inkjet printing apparatus 1 as usual.

  As the ink replacement operation, for example, printing is performed. The printing out is printing for consuming ink and causing the ink replacement in the printing unit 7 to proceed.

  When printing is performed as an ink replacement operation, the print control unit 92 starts printing after printing the sample patch.

  Specifically, the print control unit 92 sequentially feeds the paper P from the paper feeding unit 2. The print control unit 92 circulates and feeds the fed paper P by the belt conveyance unit 21, the upper surface conveyance unit 4, and the reversing unit 6, and prints images on both sides by the ink circulation type printing unit 22 </ b> C to perform double-sided printing. The printed image is a solid image printed on almost the entire surface of the paper P. The print control unit 92 causes the paper discharge unit 5 to discharge the paper P on which both sides of the printed image are printed.

  In printing off, the printing control unit 92 causes the ink circulation type printing unit 22C to print a printing off image by the operation described with reference to the flowchart of FIG.

  During printing, ink is consumed by ejecting ink from the inkjet head 38, and red ink is supplied from the ink cartridge 32 to the printing unit 27 by the ink supply control described with reference to the flowchart of FIG. Thereby, the replacement from magenta ink to red ink proceeds in the printing unit 27 of the ink circulation type printing unit 22C.

  When the number of printed sheets reaches the specified number, the print control unit 92 executes the above-described determination patch printing. When the determination patch is printed, the operator visually compares the determination patch and the sample patch to determine whether or not the ink replacement is completed. The operator inputs the determination result on the ink replacement determination result reception screen.

  When it is determined that the ink replacement has not been completed, the print control unit 92 resumes printing. Until it is determined that the ink replacement is completed, the specified number of prints and the determination patch are repeated. After it is determined that the ink replacement has been completed, the inkjet printing apparatus 1 is used as usual.

  Further, as the ink replacement operation, an ink discharge / supply operation may be performed. The ink discharging / supplying operation is an operation of discharging ink from the printing unit 27 by the ink discharging unit 28 and supplying ink to the printing unit 27 by the ink supply unit 36.

  The ink discharging operation in this ink discharging / supplying operation is performed as follows. In the ink circulation type printing unit 22C to be changed in ink color, first, the pump operation described in the flowchart of FIG. 12 is started. The upstream atmosphere release valve 48 and the downstream atmosphere release valve 53 are opened. Then, the ink discharge valve 68 is opened. As a result, the discharge of ink from the downstream tank 51 to the waste liquid tank 69 is started. When both the downstream lower limit sensor 62 and the upstream lower limit sensor 59 are turned off, the pump operation ends and the ink discharge valve 68 is closed. Thereby, the discharge of ink stops. In addition, the upstream air release valve 48 is closed, and the ink circulation type printing unit 22C enters a standby state. As a result, the ink discharging operation is completed.

  Following the ink discharge operation, the ink supply operation is performed as follows. First, the downstream atmosphere release valve 53 is closed, and the upstream atmosphere release valve 48 is opened. Next, the pump operation is started. Next, the ink supply valve 34 is opened. Thereby, the supply of ink from the ink cartridge 42 to the downstream tank 51 is started. When both the downstream lower limit sensor 62 and the upstream lower limit sensor 59 are turned on, the ink supply valve 34 is closed and the pump operation is terminated. Thereby, the supply of ink is stopped. Thereafter, the upstream atmosphere release valve 48 is closed, the downstream atmosphere release valve 53 is opened, and the ink circulation printing unit 22C enters a standby state. As a result, the ink supply operation ends.

  In the ink discharge / supply operation, a combination of a series of ink discharge operations and ink supply operations is defined as a break. A determination patch is printed for each separation.

  As described above, in the inkjet printing apparatus 1, the target color determination unit 91 determines the color reproduction range based on the combination of ink colors (CMYK) before changing the ink color with respect to the sample patch print paper type, and the determination patch print paper type (normal Ink circulation type printing unit which is a color within the common range with the color reproduction range by the ink color combination (CRYK) after the ink color change for the paper), and the ink color change target in the ink color combination after the ink color change The target color is determined from the color printed using the ink (red ink) of the color after the ink color change in 22.

  In this way, the target color determination unit 91 sets a target color according to the color reproduction range of the sample patch printing paper type and the determination patch printing paper type. Thereby, even when the sample patch printing paper type and the judgment patch printing paper type are different, the color of the judgment patch can be made the same as the color of the sample patch when the ink replacement is completed. As a result, it is possible to improve the determination accuracy when the operator determines completion of replacement with ink of a new color.

  Specifically, the target color determination unit 91 uses the ink (red ink) of the color after the ink color change in the ink circulation printing unit 22 to be changed to the ink color among the paper types held by the paper supply unit 2. If there is a paper type that includes the print color when printing on the paper of the judgment patch print paper type (plain paper) within the color reproduction range by the ink color combination (CMYK) before the ink color change, the paper type is sampled. Select the patch print paper type. Then, the target color determination unit 91 sets the target color as the print color when printing on the paper of the determination patch print paper type with the ink of the color after the ink color change in the ink circulation type printing unit 22 to be changed.

  In addition, the target color determination unit 91 prints the determination patch with the ink of the color after the ink color change (red ink) in the ink circulation type print unit 22 to be changed in the paper type held by the paper supply unit 2. If there is no paper type that includes the print color when printing on paper of the paper type (plain paper) within the color reproduction range by the ink color combination (CMYK) before the ink color change, the paper held by the paper feed unit 2 One of the types is selected as the sample patch printing paper type. Then, the target color determination unit 91 selects the color reproduction range based on the combination of ink colors (CMYK) before changing the ink color for the sample patch printing paper type and the combination (CRYK) of the ink color after changing the ink color for the determination patch printing paper type. ) Printing when printing on the paper of the judgment patch printing paper type with the ink of the color after the ink color change in the ink circulation type printing unit 22 to be changed by the ink circulation type print unit 22 that is within the common range with the color reproduction range The target color is the color having the smallest color difference from the color.

  This makes it easy to determine the completion of ink replacement by the operator by making the target color the color printed on the paper of the paper type of the patch for the determination patch printing after changing the ink color or the closest possible color. It can be improved further.

  In the inkjet printing apparatus 1, the print control unit 92 uses the ink cartridge 32 of the color (magenta) before the ink color change from the information acquired by the ink information acquisition unit 37 in the ink circulation type print unit 22 to be changed. Is replaced with the ink cartridge 32 of the color (red) after the ink color change, before the supply of the ink of the ink cartridge 32 after replacement to the printing unit 27 is started, The sample patch is printed with the target color using the ink before the ink color change.

  Accordingly, it is possible to prevent the ink in the printing unit 27 of the ink circulation type printing unit 22 to be changed in ink color from being mixed color ink before printing the sample patch. As a result, the sample patch can be reliably printed with the target color.

(Second Embodiment)
Next, a description will be given of a second embodiment in which the processing for printing the determination patch of the first embodiment described above is changed. The structure of the inkjet printing apparatus of the second embodiment is the same as that of the inkjet printing apparatus 1 of the first embodiment.

  In the second embodiment, the storage unit 8 stores an ink amount ratio table 110 shown in FIG. The ink amount ratio table 110 is a table that holds an ink amount ratio corresponding to the elapsed time from the printing time of the sample patch when the determination patch is printed. The ink amount ratio is a ratio to the ink amount when the determination patch is printed immediately after the sample patch is printed. The ink amount ratio becomes smaller as the elapsed time becomes longer. That is, in FIG. 18, 100> Ra> Rb> Rc.

  The print control unit 92 refers to the ink amount ratio table 110 and adjusts the ink amount when the determination patch is printed according to the elapsed time from the printing of the sample patch.

  When printing the determination patch, the print control unit 92 converts the RGB color target color patch image data into the CRYK format using the CRYK color profile corresponding to plain paper. Next, the print control unit 92 converts the CRYK format patch image data into determination patch print drop data. At this time, the print control unit 92 refers to the ink amount ratio table 110 and performs the ink amount by area gradation processing such as dithering so that the ink amount ratio corresponds to the elapsed time from the printing of the current sample patch. Adjust.

  Then, the print control unit 92 controls the ink ejection in the inkjet heads 38 of the ink circulation printing units 22A to 22D based on the drop data for determination patch printing, and prints the determination patch on plain paper.

  The density of the sample patch decreases as time passes after printing due to ink penetration and drying. On the other hand, in the second embodiment, the determination patch is adjusted with the density corresponding to the change with time of the density of the sample patch by adjusting the ink amount when printing the determination patch according to the elapsed time from the printing of the sample patch. Can be printed. Thereby, the determination accuracy of the ink replacement completion determination by the operator can be further improved.

(Other embodiments)
As described above, the present invention has been described according to the first and second embodiments. However, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the first and second embodiments described above, the inkjet printing apparatus having four printing units has been described, but the number of printing units is not limited thereto. The present invention can be applied as long as the ink color is changed in one printing section among the plurality of printing sections.

  In the first and second embodiments described above, according to the sample patch print paper type, the color of the determination patch print paper type is changed with the ink color after the ink color change in the ink circulation type print unit (printing unit) to be changed. Color reproduction range by combining the print color when printing on paper or the ink color before changing the ink color for the sample patch print paper type and the ink color after changing the ink color for the judgment patch print paper type Print color when printing on paper of the judgment patch printing paper type with the color after changing the ink color in the ink circulation printing unit (printing unit) that is within the common range with the range The case where the target color is the color having the smallest color difference from the above has been specifically described.

  However, the present invention is not limited to this, and the target color is a color reproduction range based on a combination of ink colors before changing the ink color for the sample patch printing paper type and a combination of ink colors after changing the ink color for the judgment patch printing paper type. Any color that is in a common range with the range and that is printed using the ink of the color after the ink color change in the print unit that is the target of the ink color change in the combination of the ink colors after the ink color change.

  Then, in the combination of ink colors after the ink color change, the target color may be a color that is printed using more ink of the color after the ink color change in the printing unit that is the ink color change target than the other color inks. preferable. As a result, it is possible to facilitate determination of completion of ink replacement by an operator and improve determination accuracy.

  In the first and second embodiments described above, the print control unit 92 has replaced the magenta ink cartridge 32 with the red ink cartridge 32 from the information acquired by the ink information acquisition unit 37 of the ink circulation type printing unit 22C. When it is determined, the case of executing printing of a sample patch has been described. However, the print control unit 92 may execute printing of the sample patch after receiving an operation of notifying the operator that the ink color change is to be performed and before the replacement with the red ink cartridge 32 is performed. .

  It goes without saying that the present invention includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

DESCRIPTION OF SYMBOLS 1 Inkjet printing apparatus 2 Paper feed part 3 Conveyance printing part 4 Upper surface conveyance part 5 Paper discharge part 6 Inversion part 7 Operation panel part 8 Storage part 9 Control part 22, 22A-22D Ink circulation type printing unit 26 Ink supply part 27 Printing part DESCRIPTION OF SYMBOLS 31 Ink cartridge mounting part 32 Ink cartridge 37 Ink information reading part 38 Inkjet head 39 Ink circulation part 90 Red reproducibility table 91 Target color determination part 92 Print control part 110 Ink amount ratio table

Claims (5)

A paper feed unit for holding at least one type of paper and feeding the held paper;
An inkjet head for ejecting ink, and a plurality of printing units each having an ink path for supplying ink to the inkjet head, and ejecting ink from the inkjet head to print on a sheet fed by the sheet feeding unit; ,
A plurality of ink supply units provided corresponding to the plurality of printing units, each having a replaceable ink cartridge for containing ink, and supplying ink from the ink cartridge to the printing unit;
In the case where the ink cartridge of the ink supply unit corresponding to a printing unit that is one of the plurality of printing units is an ink color change target is replaced with an ink cartridge that stores ink of the color after the ink color change, Ink colors in the plurality of printing sections before the ink color change for the sample image printing paper type, which is a paper type used for printing a sample image to be used as a sample for determining completion of ink replacement in the printing unit to be changed. The color reproduction range by the combination and the ink color after changing the ink color with respect to the judgment image printing paper type, which is the paper type used for printing the judgment image printed when judging the completion of the replacement of the ink in the printing unit to be changed A plurality of colors within a common range with a color reproduction range based on a combination of ink colors in a plurality of printing sections, and the plurality of colors after the ink color is changed A target color determining section for determining a target color from the color to be printed by using the color of ink after ink color change in the ink color change target print portion in combinations of the ink colors in the printing unit,
The sample image is printed on the sample image printing paper type paper with the target color by combining the ink colors in the plurality of printing units before the ink color change, and the ink corresponding to the print unit to be changed with the ink color When the replacement of the ink in the printing unit to be changed by the ink color after the replacement of the ink cartridge in the supply unit is determined, if the replacement of the ink in the printing unit to be changed by the ink color is completed, the target color is changed. An ink jet printing apparatus comprising: the paper feeding unit and a print control unit that controls each of the printing units so as to print the determination image on paper of the determination image printing paper type by ink ejection control to be printed.   The target color determination unit uses more ink of the color after the ink color change in the print unit to be changed in the ink color than the other color inks in the combination of ink colors in the plurality of printing units after the ink color change The inkjet printing apparatus according to claim 1, wherein a target color is set as a target color. The target color determination unit
Set the judgment image printing paper type,
Among the paper types held by the paper feed unit, the print color when printing on the paper of the judgment image printing paper type with the ink of the color after the ink color change in the printing unit to be changed is set to the ink color When there is a paper type included in a color reproduction range by a combination of ink colors in the plurality of printing units before the change, the paper type is selected as the sample image printing paper type, and the ink color change target printing unit The print color when printing on the paper of the judgment image printing paper type with the ink of the color after changing the ink color is set as the target color,
Among the paper types held by the paper feed unit, the print color when printing on the paper of the judgment image printing paper type with the ink of the color after the ink color change in the printing unit to be changed is set to the ink color When there is no paper type included in the color reproduction range by the combination of ink colors in the plurality of printing units before the change, one of the paper types held by the paper feeding unit is selected as the sample image printing paper type And a color reproduction range based on a combination of ink colors in the plurality of printing sections before the ink color change for the sample image printing paper type, and an ink in the plurality of printing sections after the ink color change for the determination image printing paper type The color within the common range with the color reproduction range by the combination of colors, and the color image after the ink color change in the print part to be changed by the ink color Inkjet printing apparatus according to claim 1 in which the color difference between the print color when printed on the determination image printing paper type of the paper using the clock is characterized in that the minimum color and the target color. The ink supply unit includes an ink information acquisition unit that acquires information indicating an ink color from the ink cartridge;
From the information acquired by the ink information acquisition unit, the print control unit applies an ink cartridge in which the ink cartridge of the ink supply unit corresponding to the print unit whose ink color is to be changed contains ink of the color after the ink color change. If it is determined that the ink has been replaced, before the supply of the ink of the ink cartridge after replacement to the printing unit is started, the ink before ink color change remaining in the printing unit for the printing unit whose ink color is to be changed 4. The inkjet printing apparatus according to claim 1, wherein each of the printing units is controlled so as to print the sample image with the target color. The said printing control part adjusts the ink amount at the time of printing the said determination image according to the elapsed time from printing of the said sample image, The any one of Claim 1 thru | or 4 characterized by the above-mentioned. Inkjet printing device.