JP2017105121A - Image formation system and medium classifying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation system and a medium classifying method that suppress a decrease in productivity due to wasting of paper.SOLUTION: An image formation system comprises: an image formation part (18) which forms an image on a medium (S) using two or more colors; a read part (58) which reads the image formed on the medium, the image part being configured to acquire image information on one color for each medium based upon a read result of the image and to acquire image information of two or more colors from read information of each of a plurality of media; an image defect determination part (146) which determines whether there is an image defect for each medium from image information of one color for each medium which is obtained by the read part; and a paper setting part (148) which sets, as waste paper, (i-A)th to (i+A)th media, where a medium determined to have an image defect is an (i)th medium and the number of media between the medium determined to have the image defect and a medium where image information on the same color is acquired is A.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image forming system and a medium sorting method, and more particularly to a medium sorting technique.

  As a handling of waste paper in an image forming system that forms an image on a sheet of paper, a function of counting image defects by reading image defects is known. As a method for identifying waste paper, a method for marking a medium that has been determined to be waste paper is known.

  The term “recycled paper” as used herein refers to printed matter that cannot be used as a product in the printing process. The waste paper may be referred to as waste paper.

  In this specification, the terms printing and image formation can be interchanged as appropriate. The image is a concept including characters, symbols, patterns, or the like. The pattern here may include a pattern used for a specific application such as determination of the presence or absence of an image defect.

  Patent Document 1 describes an image forming system that sorts and discharges printed matter determined to have image defects. In the image forming system described in Patent Document 1, a check pattern is formed at predetermined time intervals, and the presence or absence of an image defect is determined.

  When it is determined that there is an image defect, the printed material between the multiple printed materials with the check pattern formed before and after the printed material on which the check pattern used to determine whether there is an image defect is sorted as a piece of paper. The

  Note that the term “image forming system” in the present specification corresponds to the term “recording apparatus” in Japanese Patent Application Laid-Open No. 2005-151867. The term “check pattern” in this specification corresponds to the term “undischarge monitoring pattern” in Patent Document 1.

  Patent Document 2 describes an image forming system that forms an image on both sides of a medium. The image forming system described in Japanese Patent Laid-Open No. 2004-228561 determines the content of trouble when performing page return processing due to occurrence of trouble and restarts image formation, and forms an image from an appropriate page if necessary. It is.

  The term “medium” in this specification corresponds to the term “recording material” or the term “recording paper” in Patent Document 2. The term “image formation” in this specification corresponds to the term “printing” in Patent Document 2. The term “image forming system” in the present specification corresponds to the term “printing apparatus” in Japanese Patent Application Laid-Open No. 2005-228867.

  Patent Document 3 describes an image forming system in which a check pattern is recorded in an area other than an output image area, the check pattern is read by an inline sensor, and the presence or absence of an image defect is determined.

  Note that the term “image forming system” in the present specification corresponds to the term “recording apparatus” in Japanese Patent Application Laid-Open No. 2003-228688. The term “check pattern” in this specification corresponds to the term “test pattern” in Patent Document 3.

JP2013-252691A JP-A-7-61695 JP 2013-163318 A

  However, when waste paper is generated, it is necessary to manually remove the waste paper. In addition, it is necessary to perform image formation corresponding to the waste paper again. Thus, since the occurrence of scraped paper may lead to a decrease in productivity, it is necessary to take measures to suppress the decrease in productivity due to the occurrence of scraped paper.

  In the image forming system described in Patent Document 1, since the interval of the check pattern formation period is fixed, the number of burnt papers when an image defect is found is fixed. As a result, a non-defective product may be included in a medium that is a waste paper, and wasteful waste paper is generated. The generation of waste paper is likely to reduce productivity.

  Further, in the image forming system described in Patent Document 1, since a check pattern is formed between images on continuous paper, the unit of the image forming range on continuous paper is the size of the cut paper, and the range of the cut paper is enlarged. Concerned.

  Patent Document 2 has no description regarding sorting of misprinted prints when trouble occurs. The printed matter of misprint here is equivalent to a scraped paper. That is, Patent Document 2 does not include a description regarding sorting of scraped paper, or a description regarding suppression of a decrease in productivity due to generation of scraped paper.

  Patent Document 3 has no description regarding sorting of printed matter. That is, Patent Document 3 does not include a description regarding sorting of scraped paper, or a description regarding suppression of a decrease in productivity due to generation of scraped paper.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an image forming system and a medium sorting method capable of suppressing a decrease in productivity due to generation of scraped paper.

  In order to achieve the above object, the following invention aspects are provided.

  An image forming system according to a first aspect includes a medium conveying unit that conveys a medium, an image forming unit that forms an image using two or more colors on the medium conveyed by the medium conveying unit, and an image forming unit that forms an image on the medium. A reading unit that reads the obtained image, acquires image information for one color for each medium based on the reading result of the image, and acquires image information for two or more colors from the read information for each of a plurality of media A reading unit, an image defect determining unit for determining presence / absence of an image defect for each medium from image information for one color for each medium acquired by the reading unit, and a medium determined to have an image defect by the image defect determining unit Is the i-th medium, and A is the number of media between the media from which image information of the same color as that of the medium determined to have an image defect by the image defect determination unit, and i + A from the i-Ath sheet. Do the media up to the first A paper setting portion do it to be configured as an image forming system equipped with.

  According to the first aspect, the number of pieces of scraped paper is optimized, and it is possible to suppress a decrease in productivity due to the occurrence of scraped paper.

  According to a second aspect, in the image forming system according to the first aspect, the image forming unit forms a check pattern for at least one color for each medium for two or more colors according to a predetermined sequence, and a plurality of media The check unit for two or more colors is formed by using the reading unit, the reading unit acquires image information for one color from the reading result of the check pattern for each medium, and the reading result of the check pattern for each of a plurality of media Thus, the image information for two or more colors can be acquired.

  According to the second aspect, it is possible to determine the presence or absence of an image defect for each medium using the check pattern for each color formed on each medium.

  According to the third aspect, in the image forming system of the second aspect, when the image forming unit forms the first color and the second color check pattern in which the visibility of the image defect is lower than that of the first color, It is possible to adopt a configuration in which the check pattern formation frequency using the color is higher than the check pattern formation frequency using the second color.

  According to the third aspect, the frequency of determining the presence / absence of an image defect using a color with high visibility of the image defect is increased, and the possibility that the image defect is found can be improved.

  According to a fourth aspect, in the image forming system according to the second aspect or the third aspect, the image forming unit includes a first color, a second color whose image defects are less visible than the first color, and an image than the second color. When the image is formed using the third color with low defect visibility and the check pattern is formed, the check pattern using the third color can be omitted.

  According to the fourth aspect, it is possible to determine the presence or absence of an image defect using a color with good visibility.

  According to a fifth aspect, in the image forming system according to any one of the first aspect to the fourth aspect, the image forming unit is configured as a scraped paper by the scraped paper setting unit when the scraped paper is set by the scraped paper setting unit. Of the set media, image formation can be resumed in order from the image formed on the top medium.

  According to the fifth aspect, even when the burnt paper is set by the burnt paper setting unit, the image for the burnt paper is replenished, so that no image is lost.

  According to a sixth aspect, in the image forming system according to any one of the first to fifth aspects, the image forming unit includes a head for each color, and the image defect determination unit determines whether there is an image defect from the state of each head. It can be set as the structure which discriminate | determines.

  According to the sixth aspect, it is possible to determine the presence or absence of an image defect for each head.

  Examples of the head of the sixth aspect include an ink jet type liquid discharge head and an electrophotographic type recording head.

  According to a seventh aspect, in the image forming system according to any one of the first aspect to the sixth aspect, the image defect determination unit is configured to detect a medium having an abnormality equal to or greater than a predetermined threshold in the image information. It can be configured to discriminate from a certain medium.

  According to the seventh aspect, it is possible to determine the presence or absence of an image defect according to the number of abnormalities in the image information.

  According to an eighth aspect, in the image forming system according to any one of the first aspect to the seventh aspect, the medium transport unit includes a medium determined to have an image defect by the image defect determination unit, and an image by the image defect determination unit. It can be configured to include a transport path switching unit that switches a transport path with a medium that is determined not to be defective.

  According to the eighth aspect, it is possible to switch between a medium conveyance path determined to have an image defect and a medium conveyance path determined to have no image defect.

  According to a ninth aspect, in the image forming system according to any one of the first aspect to the eighth aspect, the scrap paper setting unit includes a scrap paper storage unit that stores the medium set as the scrap paper. Can do.

  According to the ninth aspect, it is possible to switch between a medium accommodation destination determined to have an image defect and a medium accommodation destination determined to have no image defect.

  According to a tenth aspect, in the image forming system according to any one of the first aspect to the ninth aspect, the image forming unit forms a plurality of types of images according to a predetermined order, and the scraped paper setting unit sets the scraped paper. The image formation can be restarted from the image formed on the top medium among the determined media.

  According to the tenth aspect, the order of image formation is maintained, and it is not necessary to form an image again on a medium set as a waste paper.

  The medium sorting method according to the eleventh aspect includes an image forming process for forming an image using two or more colors on the medium conveyed by the medium conveying unit, and a reading process for reading an image formed on the medium by the image forming process. A reading process for acquiring image information for one color for each medium based on the reading result of the image, and acquiring image information for two or more colors from the reading result for each of a plurality of media, and the reading process. An image defect determination step for determining the presence or absence of an image defect for each medium from image information for one color for each medium, and a medium determined to have an image defect by the image defect determination step is defined as an i-th medium. Let A be the number of media between the media from which image information of the same color as that of the media identified as having image defects is found in the defect discrimination process, and use the media from the i-Ath to i + Ath as burnt paper Configuration And Ruyare paper setting step, a medium sorting method comprising.

  According to the eleventh aspect, the same effect as that of the image forming system of the first aspect can be obtained.

  In the eleventh aspect, matters similar to the matters specified in the second aspect to the tenth aspect can be appropriately combined. In this case, the configuration specified in the image forming system can be grasped as an element of the configuration that bears processing and functions corresponding to this.

  According to the present invention, the number of scraped papers is optimized, and it is possible to suppress a decrease in productivity due to the occurrence of scraped paper.

FIG. 1 is an overall configuration diagram of an ink jet recording apparatus. FIG. 2 is a block diagram showing a schematic configuration of a control system of the ink jet recording apparatus. FIG. 3 is a perspective plan view showing an example of the structure of the liquid discharge head. FIG. 4 is a perspective view of the head module and includes a partial cross-sectional view. FIG. 5 is a perspective plan view of the liquid ejection surface in the head module. FIG. 6 is a cross-sectional view showing the internal structure of the head module. FIG. 7 is an explanatory diagram schematically showing a nozzle check pattern. FIG. 8 is a flowchart showing a part of the procedure for forming the nozzle check pattern. FIG. 9 is a flowchart showing the flow of the procedure for determining the image defect. FIG. 10 is an explanatory diagram schematically showing the setting of the waste paper when it is determined that there is an image defect by the nozzle check pattern using black ink. FIG. 11 is an explanatory diagram schematically showing the burnt paper setting when it is determined that there is an image defect by the nozzle check pattern using cyan ink. FIG. 12 is an explanatory diagram schematically showing the burnt paper setting when it is determined that there is an image defect by the nozzle check pattern using magenta ink. FIG. 13 is a flowchart showing an image forming procedure. FIG. 14 is an explanatory view schematically showing an image forming procedure to which the burnt paper setting according to the second embodiment is applied. FIG. 15 is an explanatory view schematically showing the setting of the waste paper according to the second embodiment. FIG. 16 is an explanatory view schematically showing an image forming procedure according to the first modification. FIG. 17 is an explanatory view schematically showing an image forming procedure according to the second modification. FIG. 18 is an explanatory view schematically showing an image forming procedure according to the third modification.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification, the components already described are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

[Overall configuration of image forming system]
First, the overall configuration of the image forming system will be described. In this embodiment, an ink jet recording apparatus is illustrated as an image forming system. FIG. 1 is an overall configuration diagram of an ink jet recording apparatus.

  An ink jet recording apparatus 10 shown in FIG. 1 is an ink jet recording apparatus that draws an image on a sheet of paper S using an ink jet method using ink.

  The sheet S is an aspect of the medium. The ink jet recording apparatus 10 is an aspect of an image forming system. In this specification, it is possible to replace the term ink and the term liquid as appropriate.

  The ink jet recording apparatus 10 mainly includes a paper feeding unit 12, a processing liquid applying unit 14, a processing liquid drying processing unit 16, a drawing unit 18, an ink drying processing unit 20, and a paper discharge unit 24. Hereinafter, each part will be described in detail.

<Paper Feeder>
The sheet feeding unit 12 includes a sheet feeding table 30, a soccer device 32, a sheet feeding roller pair 34, a feeder board 36, a front pad 38, and a sheet feeding cylinder 40. The feeder board 36 includes a retainer 36A and a guide roller 36B.

  The retainer 36 </ b> A and the guide roller 36 </ b> B are disposed on the transport surface on which the paper S of the feeder board 36 is transported. The front pad 38 is disposed between the feeder board 36 and the paper feed cylinder 40.

  The paper feed cylinder 40 has a cylindrical shape whose longitudinal direction is parallel to the rotation shaft 40B. The paper feed cylinder 40 has a length exceeding the total length of the paper S in the longitudinal direction. The direction of the rotation shaft 40B of the paper feed cylinder 40 is a direction that penetrates the paper surface of FIG.

  Here, the term “parallel” in this specification includes substantial parallel that has the same effect as parallel although two directions intersect.

  In the present specification, the term “orthogonal” means that the substantial orthogonality having the same effect as the case of intersecting at 90 degrees out of the case of intersecting at an angle of more than 90 degrees or less than 90 degrees. included.

  Although the same term in this specification has a difference in the composition used as object, the same term which can obtain the same operation effect as the same is included.

  The paper feed cylinder 40 includes a gripper 40A. The gripper 40A includes a plurality of claws, a claw base, and a gripper shaft. A plurality of claws, claw bases, and gripper shafts are not shown.

  The plurality of claws of the gripper 40 </ b> A are arranged along a direction parallel to the rotation shaft 40 </ b> B of the paper feed cylinder 40. The base ends of the plurality of claws are swingably supported by the gripper shaft. The arrangement interval of the plurality of claws and the length of the area where the plurality of claws are arranged are determined according to the size of the paper S.

  The claw base is a member whose longitudinal direction is parallel to the rotation axis of the paper feed cylinder 40. With respect to the longitudinal direction of the paper feed cylinder 40, the length of the claw base is set to be equal to or longer than the length where a plurality of claws are arranged. The claw base is disposed at a position facing the tip portions of the plurality of claws.

  The sheet feeding unit 12 feeds the sheets S stacked on the sheet feeding table 30 to the processing liquid applying unit 14 one by one. The sheets S stacked on the sheet feed table 30 are pulled up one by one from the top by the soccer device 32 and are fed to the sheet feed roller pair 34.

  The paper S fed to the paper feed roller pair 34 is placed on the feeder board 36 and conveyed by the feeder board 36. The sheet S conveyed by the feeder board 36 is pressed against the conveying surface of the feeder board 36 by the retainer 36A and the guide roller 36B, and the unevenness is corrected.

  The sheet S conveyed by the feeder board 36 is corrected in inclination by the leading end of the sheet S coming into contact with the front pad 38. The paper S conveyed by the feeder board 36 is delivered to the paper feed cylinder 40.

  The leading edge of the paper S delivered to the paper feed cylinder 40 is gripped by the gripper 40 </ b> A of the paper feed cylinder 40. When the paper feed cylinder 40 is rotated, the paper S is conveyed along the outer peripheral surface of the paper feed cylinder 40. The paper S conveyed by the paper feed cylinder 40 is delivered to the processing liquid application unit 14.

<Processing liquid application part>
The treatment liquid application unit 14 includes a treatment liquid cylinder 42 and a treatment liquid application device 44. The treatment liquid cylinder 42 includes a gripper 42A. A configuration similar to that of the gripper 40 </ b> A of the paper feed cylinder 40 can be applied to the gripper 42 </ b> A.

  The processing liquid cylinder 42 shown in FIG. 1 has a diameter twice that of the paper supply cylinder 40. The processing liquid cylinder 42 has a configuration in which the paper S is fixed to the outer peripheral surface 42C on which the paper S is supported. As an example of a configuration in which the sheet S is fixed to the outer peripheral surface 42C of the processing liquid cylinder 42, a configuration in which a plurality of suction holes are provided in the outer peripheral surface 42C of the processing liquid cylinder 42, and a negative pressure is applied to the plurality of suction holes. .

  Except for the above, the processing liquid cylinder 42 can have the same configuration as the paper supply cylinder 40. Reference numeral 42 </ b> B is a rotation shaft of the treatment liquid cylinder 42.

  The treatment liquid application device 44 can apply a roller coating method. A configuration including a processing liquid tank, a metering roller, and a coating roller can be adopted as the roller coating type processing liquid application device 44.

  The processing liquid tank stores the processing liquid supplied from the processing liquid tank via the processing liquid supply system. The measuring roller measures the processing liquid stored in the processing liquid tank. The measuring roller transfers the measured processing liquid to the application roller. The application roller applies the processing liquid to the paper S.

  In addition, the structure of the process liquid application apparatus 44 demonstrated here is an example to the last, and the process liquid application apparatus 44 may apply another system. Further, the treatment liquid application device 44 may employ other configurations.

  Examples of other methods of the treatment liquid applying device 44 include application using a blade, ejection by an ink jet method, spraying by a spray method, and the like.

  When the processing liquid cylinder 42 is rotated with the gripper 42 </ b> A holding the leading edge of the paper S, the paper S is conveyed along the outer peripheral surface of the processing liquid cylinder 42. The processing liquid is applied to the paper S conveyed along the outer peripheral surface of the processing liquid cylinder 42 by the processing liquid applying device 44. The sheet S to which the processing liquid is applied is sent to the processing liquid drying processing unit 16.

  The treatment liquid applied to the paper S has a function of aggregating the color material in the ink discharged onto the paper S by the drawing unit 18 at the subsequent stage or a function of insolubilizing the color material of the ink. By applying the treatment liquid to the paper S and ejecting the ink, high-quality image formation can be performed without causing landing interference even if a general-purpose paper is used.

  The term “ejection” in this specification can be appropriately read as droplet ejection or image formation.

  The sheet S to which the processing liquid is applied by the processing liquid applying unit 14 is delivered to the processing liquid drying processing unit 16.

<Processing liquid drying processing section>
The processing liquid drying processing unit 16 includes a processing liquid drying processing cylinder 46, a paper transport guide 48, and a processing liquid drying processing unit 50. The treatment liquid drying treatment cylinder 46 includes a gripper 46A. A configuration similar to that of the gripper 40A of the paper feed cylinder 40 can be applied to the gripper 46A.

  The processing liquid drying processing cylinder 46 shown in FIG. 1 has a diameter twice as large as the diameter of the paper supply cylinder 40. The treatment liquid drying treatment cylinder 46 is provided with two grippers 46A. The arrangement positions of the two grippers 46 </ b> A are positions shifted by a half circumference on the outer peripheral surface 46 </ b> C of the processing liquid drying processing cylinder 46.

  The processing liquid drying processing cylinder 46 can be configured in the same manner as the sheet feeding cylinder 40 except for the above. Reference numeral 46B denotes a rotation shaft of the treatment liquid drying treatment cylinder 46.

  The paper transport guide 48 is disposed at a position facing the outer peripheral surface 46 </ b> C of the processing liquid drying processing cylinder 46. The paper transport guide 48 is disposed below the processing liquid drying processing cylinder 46.

  The lower side in this specification is the side of the direction having a component in the direction of gravity. The upper side is the side of the direction having a component opposite to the direction of gravity.

  The processing liquid drying processing unit 50 is disposed inside the processing liquid drying processing cylinder 46. The treatment liquid drying processing unit 50 includes a blower that blows air toward the outside of the treatment liquid drying treatment cylinder 46 and a heating unit that heats the wind. For convenience of illustration, reference numerals of the blower unit and the heating unit are omitted.

  The leading edge of the sheet S delivered from the processing liquid application unit 14 to the processing liquid drying processing unit 16 is gripped by the gripper 46A of the processing liquid drying processing cylinder 46.

  The sheet S is supported by the sheet conveyance guide 48 on the surface opposite to the surface coated with the treatment liquid, with the surface coated with the treatment liquid facing the outer peripheral surface 46C of the treatment liquid drying treatment cylinder 46. . By rotating the treatment liquid drying treatment cylinder 46, the paper S is conveyed along the outer peripheral surface 46C of the treatment liquid drying treatment cylinder 46.

  The paper S conveyed by the treatment liquid drying treatment cylinder 46 and supported by the paper conveyance guide 48 is subjected to drying treatment by blowing air heated from the treatment liquid drying treatment unit 50.

  When the drying process is performed on the paper S, the solvent component in the processing liquid applied to the paper S is removed, and a processing liquid layer is formed on the surface of the paper S to which the processing liquid is applied. The paper S that has been dried by the treatment liquid drying processing unit 16 is delivered to the drawing unit 18.

<Drawing part>
The drawing unit 18 includes a drawing cylinder 52, a sheet pressing roller 54, a liquid discharge head 56C, a liquid discharge head 56M, a liquid discharge head 56Y, a liquid discharge head 56K, and an in-line sensor 58. The drawing cylinder 52 includes a gripper 52A.

  The gripper 52 </ b> A is disposed inside a recess 52 </ b> D provided on the outer peripheral surface 52 </ b> C of the drawing cylinder 52. For the gripper 52A, the same configuration as that of the gripper 40A of the paper feed cylinder 40 can be applied except for the arrangement.

  The drawing cylinder 52 is provided with two grippers 52 </ b> A in the same manner as the processing liquid drying processing cylinder 46. The arrangement of the two grippers 52 </ b> A can be the same as that of the treatment liquid drying treatment cylinder 46.

  Similar to the treatment liquid cylinder 42, the drawing cylinder 52 has a configuration in which the paper S is fixed to the outer peripheral surface 52C on which the paper S is supported. The configuration for fixing the paper S of the drawing cylinder 52 can be the same as the configuration for fixing the paper S of the processing liquid cylinder 42.

  For the drawing cylinder 52, the same configuration as that of the sheet feeding cylinder 40 can be applied except for the configuration described above. Reference numeral 52B denotes a rotation axis of the drawing cylinder 52.

  The sheet pressing roller 54 has a cylindrical shape. The longitudinal direction of the sheet pressing roller 54 is parallel to the rotation shaft 52 </ b> B of the drawing cylinder 52. The sheet pressing roller 54 has a length exceeding the entire length of the sheet S in the longitudinal direction.

  The sheet pressing roller 54 is disposed on the downstream side of the delivery position of the sheet S and the upstream side of the liquid ejection head 56C in the conveyance direction of the sheet S in the drawing cylinder 52. In the following description, the transport direction of the paper S may be described as the paper transport direction.

  The liquid discharge head 56C, the liquid discharge head 56M, the liquid discharge head 56Y, and the liquid discharge head 56K include discharge elements that discharge liquid by an inkjet method. The ink jet type liquid discharge head includes what is called an ink jet head.

  Here, the alphabet attached to the code | symbol of the liquid discharge head represents the color. C represents cyan. M represents magenta. Y represents yellow. K represents black.

  The liquid discharge head 56C, the liquid discharge head 56M, the liquid discharge head 56Y, and the liquid discharge head 56K are disposed above the drawing cylinder 52. The liquid discharge head 56C, the liquid discharge head 56M, the liquid discharge head 56Y, and the liquid discharge head 56K are arranged along the transport direction of the paper S, the liquid discharge head 56C, the liquid discharge head 56M, the liquid discharge head 56Y, and the liquid discharge head. Arranged in the order of 56K.

  Details of the liquid discharge head 56C, the liquid discharge head 56M, the liquid discharge head 56Y, and the liquid discharge head 56K will be described later. The liquid discharge head is an aspect of the head. The ejection element is an aspect of the recording element.

  The inline sensor 58 includes an image sensor, a peripheral circuit of the image sensor, and a light source. A solid-state imaging device such as a CCD image sensor or a CMOS image sensor can be applied as the imaging device. Illustration of the image sensor, the peripheral circuit of the image sensor, and the light source is omitted.

  CCD is an abbreviation for Charge Coupled Device. CMOS is an abbreviation for Complementary Metal-Oxide Semiconductor. The in-line sensor 58 is disposed on the downstream side of the liquid discharge head 56K in the paper transport direction.

  The peripheral circuit of the image sensor includes a processing circuit for an output signal of the image sensor. Examples of the processing circuit include a filter circuit, an amplifier circuit, or a waveform shaping circuit that removes noise components from the output signal of the image sensor. Illustration of the filter circuit, the amplifier circuit, or the waveform shaping circuit is omitted.

  A light source is arrange | positioned in the position which can irradiate illumination light to the reading target object of an in-line sensor. An LED or a lamp can be applied as the light source. LED is an abbreviation for light emitting diode.

  The leading edge of the sheet S delivered from the processing liquid drying processing unit 16 to the drawing unit 18 is gripped by the gripper 52A of the drawing cylinder 52. The sheet S whose leading edge is gripped by the gripper 52 </ b> A of the drawing cylinder 52 is conveyed along the outer peripheral surface 52 </ b> C of the drawing cylinder 52 by the rotation of the drawing cylinder 52.

  When the sheet S passes under the sheet pressing roller 54, it is pressed against the outer peripheral surface 52 </ b> C of the drawing cylinder 52. The sheet S that has passed under the sheet pressing roller 54 is directly under the liquid discharge head 56C, the liquid discharge head 56M, the liquid discharge head 56Y, and the liquid discharge head 56K, and the liquid discharge head 56C, the liquid discharge head 56M, and the liquid discharge head. An image is formed by the color ink ejected from each of 56Y and the liquid ejection head 56K.

  In the sheet S on which an image is formed by the liquid ejection head 56C, the liquid ejection head 56M, the liquid ejection head 56Y, and the liquid ejection head 56K, the image is read by the inline sensor 58 in the reading area of the inline sensor 58. Details of image reading by the inline sensor 58 will be described later.

  The sheet S on which the image is read by the inline sensor 58 is delivered from the drawing unit 18 to the ink drying processing unit 20.

  The drawing unit 18 is an aspect of an image forming unit that forms an image using two or more colors on a medium. Drawing by the drawing unit 18 is an aspect of an image forming process for forming an image using two or more colors on a medium. Drawing by the drawing unit 18 may include drawing of a nozzle check pattern. Details of the nozzle check pattern will be described later.

  The inline sensor 58 is an aspect of a reading unit that acquires image information from an image reading result. Acquisition of image information by the in-line sensor 58 may include an aspect of acquiring nozzle check pattern information from the result of reading the nozzle check pattern. Reading of the nozzle check pattern by the in-line sensor 58 and acquisition of image information from the reading result of the nozzle check pattern are one aspect of the reading process.

<Ink drying processing section>
The ink drying processing unit 20 includes a chain gripper 64, an ink drying processing unit 68, and a guide plate 72. The chain gripper 64 includes a first sprocket 64A, a second sprocket 64B, a chain 64C, and a plurality of grippers 64D.

  The chain gripper 64 has a structure in which a pair of endless chains 64C are wound around a pair of first sprocket 64A and a second sprocket 64B. FIG. 1 shows only one of the pair of first sprocket 64A, the second sprocket 64B, and the pair of chains 64C.

  The chain gripper 64 has a structure in which a plurality of grippers 64D are disposed between a pair of chains 64C. The chain gripper 64 has a structure in which a plurality of grippers 64D are arranged at a plurality of positions in the medium conveyance direction. FIG. 1 shows only one gripper 64D among the plurality of grippers 64D arranged between the pair of chains 64C.

  The chain gripper 64 shown in FIG. 1 includes a horizontal conveyance area for conveying the paper S along the horizontal direction and an inclined conveyance area for conveying the paper S obliquely upward.

  The ink drying processing unit 68 is disposed on the transport path of the paper S in the chain gripper 64. A configuration example of the ink drying processing unit 68 includes a configuration including a heat source such as a halogen heater or an infrared heater. Another configuration example of the ink drying processing unit 68 includes a configuration including a fan that blows air heated by a heat source onto the paper S. The ink drying processing unit 68 can include a heat source and a fan.

  Although detailed illustration of the guide plate 72 is omitted, a plate-like member can be applied to the guide plate 72. The guide plate 72 has a length that exceeds the total length of the paper S in a direction orthogonal to the paper transport direction.

  The guide plate 72 is arranged along the conveyance path in the horizontal conveyance area of the paper S by the chain gripper 64. The guide plate 72 is disposed below the conveyance path of the paper S by the chain gripper 64. The guide plate 72 has a length corresponding to the length of the processing area of the ink drying processing unit 68 in the paper transport direction.

  The length corresponding to the length of the processing region of the ink drying processing unit 68 is the length of the guide plate 72 that can support the paper S by the guide plate 72 during the processing of the ink drying processing unit 68.

  For example, with respect to the paper transport direction, a mode in which the length of the processing region of the ink drying processing unit 68 and the length of the guide plate 72 are the same can be cited. The guide plate 72 may have a function of sucking and supporting the paper S.

  The leading edge of the paper S delivered from the drawing unit 18 to the ink drying processing unit 20 is gripped by the gripper 64D. When at least one of the first sprocket 64A and the second sprocket 64B is rotated clockwise in FIG. 1 to travel the chain 64C, the paper S is conveyed along the travel path of the chain 64C.

  When the paper S passes through the processing region of the ink drying processing unit 68, the ink drying processing unit 68 performs ink drying processing on the paper S.

  The paper S that has been subjected to the ink drying process by the ink drying processing unit 68 is conveyed by the chain gripper 64 and sent to the paper discharge unit 24.

  The chain gripper 64 shown in FIG. 1 conveys the sheet S in the diagonally upper left direction in FIG. 1 on the downstream side of the ink drying processing unit 68 in the sheet conveyance direction. A guide plate 73 is disposed on the conveyance path of the inclined conveyance region for conveying the sheet S in the diagonally upward left direction in FIG.

  As the guide plate 73, a member similar to the guide plate 72 can be applied. Description of the structure and function of the guide plate 73 is omitted.

<Output section>
The paper discharge unit 24 includes a paper discharge switching unit 74, a waste paper storage unit 75, and a paper discharge stand 76. A chain gripper 64 is applied to transport the paper S in the paper discharge unit 24.

  The paper discharge switching unit 74 includes a select lever 74A and a select lever swing support portion 74B. The select lever swing support 74B is connected to a motor (not shown).

  The paper discharge switching unit 74 is disposed on the downstream side of the transport path of the paper S that transports the paper S in the paper transport direction in the diagonally upward left direction in FIG. The paper discharge switching unit 74 is disposed on the upstream side of the paper discharge tray 76 in the paper transport direction. The paper discharge switching unit 74 is an aspect of the transport path switching unit.

  The waste paper storage unit 75 stores the waste paper. The waste paper storage unit 75 is disposed below the paper discharge switching unit 74. A tray-like member can be applied to the waste paper container 75.

  The paper discharge table 76 is disposed below the conveyance path of the paper S by the chain gripper 64. The paper discharge stand 76 can include a lifting mechanism (not shown). The paper discharge tray 76 can be raised and lowered according to the increase / decrease of the stacked sheets S to keep the height of the uppermost sheet S constant.

  The paper discharge unit 24 collects the paper S that has undergone a series of image formation processes. The paper discharge unit 24 has a function of sorting the paper SA that has been determined to be broken paper and the paper S that has been determined that normal image formation has been performed. The paper SA determined as a waste paper is illustrated using a two-dot broken line.

  When the paper SA determined to be broken paper is transported, the paper discharge path switching unit 74 switches the transport path of the paper SA to a path for transporting the paper SA to the paper storage unit 75. The select lever 74 </ b> A illustrated by using a two-dot broken line in FIG. 1 is a state when configuring a path for transporting the paper SA to the paper storage unit 75.

  When the paper SA reaches the position of the paper discharge switching unit 74, the gripper 64D releases the paper SA. The paper SA is separated from the paper conveyance path by the chain gripper 64 along the select lever 74A shown in the figure using a two-dot broken line, and is sent to the waste paper container 75.

  On the other hand, when the paper S determined to have been formed normally is transported, the paper discharge switching unit 74 switches the transport path of the paper S to a path for transporting the paper S to the paper discharge tray 76. The select lever 74A illustrated using the solid line in FIG. 1 is in a state when a path for conveying the paper S to the paper discharge tray 76 is configured.

  Even when the paper S reaches the position of the paper discharge switching unit 74, the gripper 64D maintains the grip of the paper S. The sheet S is transported along a transport path of the sheet S by the chain gripper 64 along the select lever 74A shown in the figure using a solid line, and is sent to the sheet discharge table 76.

  When the paper S reaches the position of the paper discharge tray 76, the gripper 64D releases the grip of the paper S. The paper S is stacked on the paper discharge tray 76. In this way, the paper S determined to have been subjected to normal image formation and the paper SA determined to be a waste paper are sorted.

  In FIG. 1, the inkjet recording apparatus 10 including the processing liquid application unit 14 and the processing liquid drying processing unit 16 is illustrated, but an aspect in which the processing liquid application unit 14 and the processing liquid drying processing unit 16 are omitted is also possible. is there.

  1 illustrates the chain gripper 64 as a configuration for transporting the paper S after drawing, but other configurations such as belt transport or impression cylinder transport are applied to the configuration for transporting the paper S after drawing. It is also possible.

[Description of control system]
FIG. 2 is a block diagram illustrating a schematic configuration of a control system of the inkjet recording apparatus 10. As shown in FIG. 2, the inkjet recording apparatus 10 includes a system controller 100. The system controller 100 includes a CPU 100A, a ROM 100B, and a RAM 100C.

  The ROM 100B and the RAM 100C illustrated in FIG. 2 may be provided outside the CPU. CPU is an abbreviation for Central Processing Unit. ROM is an abbreviation for Read Only Memory. RAM is an abbreviation for Random Access Memory.

  The system controller 100 functions as an overall control unit that comprehensively controls each unit of the inkjet recording apparatus 10. Further, the system controller 100 functions as an arithmetic unit that performs various arithmetic processes.

  Furthermore, the system controller 100 functions as a memory controller that controls reading and writing of data in memories such as the ROM 100B and the RAM 100C.

  The inkjet recording apparatus 10 includes a communication unit 102, an image memory 104, a conveyance control unit 110, a paper feed control unit 112, a processing liquid application control unit 114, a processing liquid drying control unit 116, a drawing control unit 118, and a nozzle check pattern data storage unit. 119, an ink drying control unit 120, and a paper discharge control unit 124 are provided.

  The communication unit 102 includes a communication interface (not shown). The communication unit 102 transmits and receives data to and from the host computer 103 connected to the communication interface.

  The image memory 104 functions as a temporary storage unit for various data including image data. The image memory 104 reads and writes data through the system controller 100. Image data captured from the host computer 103 via the communication unit 102 is temporarily stored in the image memory 104.

  The conveyance control unit 110 controls the operation of the conveyance system 11 for the paper S in the inkjet recording apparatus 10. 2 includes the processing liquid cylinder 42, the processing liquid drying processing cylinder 46, the drawing cylinder 52, and the chain gripper 64 shown in FIG.

  The transport system 11 is an aspect of the medium transport unit. At least the drawing cylinder 52 and the chain gripper 64 are components of the medium transport unit.

  The paper feed control unit 112 illustrated in FIG. 2 operates the paper feed unit 12 in response to a command from the system controller 100. The paper feed control unit 112 controls the paper S supply start operation, the paper S supply stop operation, and the like.

  The processing liquid application control unit 114 operates the processing liquid application unit 14 in response to a command from the system controller 100. The treatment liquid application control unit 114 controls the application amount and application timing of the process liquid.

  The processing liquid drying control unit 116 operates the processing liquid drying processing unit 16 in response to a command from the system controller 100. The treatment liquid drying control unit 116 controls the drying temperature, the flow rate of the dry gas, the injection timing of the dry gas, and the like.

  The drawing control unit 118 controls the operation of the drawing unit 18 in response to a command from the system controller 100.

  The drawing control unit 118 includes an image processing unit, a waveform generation unit, a waveform storage unit, and a drive circuit. In FIG. 2, the image processing unit, the waveform generation unit, the waveform storage unit, and the drive circuit are not shown.

  The image processing unit forms dot data from the input image data. The waveform generator generates a drive voltage waveform. The waveform storage unit stores the waveform of the drive voltage. The drive circuit generates a drive voltage having a drive waveform corresponding to the dot data. The drive circuit supplies a drive voltage to the liquid discharge head.

  In the image processing unit, color separation processing for separating input image data into RGB colors, color conversion processing for converting RGB into CMYK, correction processing such as gamma correction or unevenness correction, and gradation for each color pixel A halftone process for converting the value into a gradation value less than the original gradation value is performed.

  As an example of the input image data, raster data represented by digital values from 0 to 255 can be cited. The dot data obtained as a result of the halftone process may be binary, or may be a multi-value that is three or more and less than the gradation value before the halftone process.

  Based on the dot data generated through the processing by the image processing unit, the ejection timing and the ink ejection amount at each pixel position are determined, the ejection timing at each pixel position, the drive voltage corresponding to the ink ejection amount, and each A control signal for determining the ejection timing of the pixel is generated, this drive voltage is supplied to the liquid ejection head, and dots are recorded by the ink ejected from the liquid ejection head.

  The drawing control unit 118 controls the operation of the drawing unit 18 when the nozzle check pattern is formed on the paper S. Specifically, the drawing control unit 118 reads nozzle check pattern data stored in the nozzle check pattern data storage unit 119. The drawing control unit 118 generates a drive voltage for forming a nozzle check pattern. The drawing control unit 118 supplies a drive voltage for forming a nozzle check pattern to the liquid ejection head. Details of the nozzle check pattern formation will be described later.

  The drawing control unit 118 includes a correction processing unit (not shown). The correction processing unit executes a correction process for the abnormal nozzle. When the correction process is performed, a decrease in image quality due to the occurrence of abnormal nozzles is suppressed.

  The ink drying control unit 120 operates the ink drying processing unit 20 in accordance with a command from the system controller 100. The ink drying control unit 120 controls the drying gas temperature, the flow rate of the drying gas, or the ejection timing of the drying gas.

  The paper discharge control unit 124 operates the paper discharge unit 24 in response to a command from the system controller 100. The paper discharge control unit 124 controls the switching of the transport path between the paper S determined to have a normal image formation and the paper SA determined to be a scraped paper. Details of transfer path switching control will be described later.

  The paper discharge control unit 124 controls the operation of the lifting mechanism according to the increase / decrease of the paper S when the paper discharge tray 76 includes a lifting mechanism.

  The inkjet recording apparatus 10 includes a sequence setting unit 126. The sequence setting unit 126 sets a nozzle check pattern formation sequence. The nozzle check pattern formation sequence may adopt a mode set according to image forming conditions, a mode set according to external input information, or the like.

  It is also possible to perform an initial setting of the nozzle check pattern formation sequence when starting up the apparatus, and change the nozzle check pattern formation sequence according to image forming conditions or external input information.

  Further, the nozzle check pattern formation sequence set when the apparatus is started up may be fixed. When the nozzle check pattern formation sequence is set, the nozzle check pattern is formed on each sheet S according to the nozzle check pattern formation sequence.

  The ink jet recording apparatus 10 includes an operation unit 130, a display unit 132, a parameter storage unit 134, and a program storage unit 136.

  The operation unit 130 includes operation members such as operation buttons, a keyboard, or a touch panel. The operation unit 130 may include a plurality of types of operation members. The illustration of the operation member is omitted. Information input via the operation unit 130 is sent to the system controller 100. The system controller 100 executes various processes according to information sent from the operation unit 130.

  The display unit 132 includes a display device such as a liquid crystal panel and a display driver. Illustration of the display device and the display driver is omitted. In response to a command from the system controller 100, the display unit 132 causes the display device to display various information such as various setting information of the device or abnormality information.

  The parameter storage unit 134 stores various parameters used in the inkjet recording apparatus 10. Various parameters stored in the parameter storage unit 134 are read out via the system controller 100 and set in each unit of the apparatus.

  The program storage unit 136 stores a program used for each unit of the inkjet recording apparatus 10. Various programs stored in the program storage unit 136 are read out via the system controller 100 and executed in each unit of the apparatus.

  Although illustration is omitted, the inkjet recording apparatus 10 includes a maintenance processing unit that executes maintenance processing of the drawing unit 18. Maintenance processing of the drawing unit 18 includes recovery processing of the liquid discharge head 56C, the liquid discharge head 56M, the liquid discharge head 56Y, and the liquid discharge head 56K illustrated in FIG.

  The recovery process for the liquid ejection head includes a recovery process for the abnormal ejection nozzle. When the number of ejection abnormal nozzles is equal to or greater than a predetermined reference value, recovery processing for ejection abnormal nozzles is performed.

  The inkjet recording apparatus 10 includes a read information storage unit 140, a read information analysis unit 142, an abnormal nozzle number storage unit 144, an image defect determination unit 146, and a burned paper setting unit 148.

  The reading information storage unit 140 stores image information including reading information of the nozzle check pattern acquired by the inline sensor 58. The image information acquired by the inline sensor 58 is an aspect of image information for two or more colors acquired from a plurality of media.

  The read information analysis unit 142 analyzes the read information stored in the read information storage unit 140. The reading information analysis unit 142 analyzes the reading information to determine the presence or absence of abnormal nozzles, and measures the number of abnormal nozzles.

  The number of abnormal nozzles measured by the reading information analysis unit 142 is stored in the abnormal nozzle number storage unit 144 in association with the sheet S on which the nozzle check pattern is formed and the liquid ejection head.

  The image defect determination unit 146 determines the presence or absence of an image defect for each sheet S from the number of abnormal nozzles stored in the abnormal nozzle number storage unit 144. In the present embodiment, it is determined that there is an image defect when the number of abnormal nozzles is equal to or greater than a predetermined threshold.

  When the paper S determined to have an image defect is generated, the scraped paper setting unit 148 sets the scraped paper. The paper discharge control unit 124 controls the operation of the paper discharge switching unit 74 shown in FIG. 1 using the information on the paper that has been set by the paper setting unit 148. Details of the setting of the waste paper will be described later.

  In FIG. 2, each part is listed for each function. Each part shown in FIG. 2 can be integrated, separated, combined, or omitted as appropriate. Further, each unit shown in FIG. 2 can be configured by appropriately combining hardware and software.

[Liquid discharge head structure]
Next, the structure of the liquid discharge head will be described in detail.

<Overall structure>
FIG. 3 is a perspective plan view showing an example of the structure of the liquid discharge head. The liquid discharge head 56C that discharges cyan ink, the liquid discharge head 56M that discharges magenta ink, the liquid discharge head 56Y that discharges yellow ink, and the liquid discharge head 56K that discharges black ink have the same structure. Can be applied.

  In the case where it is not necessary to distinguish between the liquid discharge head 56C, the liquid discharge head 56M, the liquid discharge head 56Y, and the liquid discharge head 56K, the reference numeral 56 is used to represent the liquid discharge head.

As shown in FIG. 3, the liquid discharge head 56 is a line type head. The line type head has a structure in which a plurality of nozzle portions are arranged over a length exceeding the full width _Lmax of the paper S in a direction orthogonal to the paper transport direction. In FIG. 3, the illustration of the nozzle portion is omitted. The nozzle portion is illustrated in FIG. The nozzle part is a component of the ejection element.

  The direction indicated by reference numeral X in FIG. 3 is a direction orthogonal to the paper transport direction. The direction indicated by using the symbol Y in FIG. 3 is the paper transport direction. Hereinafter, the direction orthogonal to the paper transport direction may be described as the X direction. Further, the paper transport direction may be described as the Y direction.

  The liquid discharge head 56 illustrated in FIG. 3 includes a plurality of head modules 200. The plurality of head modules 200 are arranged in a line along a direction orthogonal to the paper transport direction.

  The plurality of head modules 200 can apply the same configuration. Further, the head module 200 has a structure that can function as a liquid ejection head by itself.

  FIG. 3 shows the liquid ejection head 56 in which a plurality of head modules 200 are arranged as an example along a direction orthogonal to the paper conveyance direction. However, the plurality of head modules 200 are out of phase with respect to the paper conveyance direction. It may be arranged in two rows.

  A plurality of nozzle openings are arranged on the ejection surface 277 of the head module 200 constituting the liquid ejection head 56. In FIG. 3, the illustration of the nozzle openings is omitted. The nozzle opening is shown in FIG.

In the present embodiment, the full-line type liquid discharge head 56 is exemplified, but a short serial type liquid discharge head that does not satisfy the full width L _{max of the} paper S is scanned in a direction orthogonal to the paper transport direction to transport the paper. When one image formation in the direction orthogonal to the direction is performed, and one image formation in the direction orthogonal to the paper conveyance direction is completed, the paper S is conveyed by a certain amount in the paper conveyance direction, and the paper conveyance direction for the next region It is possible to apply a serial method in which image formation is performed in a direction orthogonal to the image and this operation is repeated to form an image on the entire surface of the paper.

<Structure example of head module>
Next, the head module will be described in detail.

  FIG. 4 is a perspective view of the head module and includes a partial cross-sectional view. FIG. 5 is a perspective plan view of the liquid ejection surface in the head module.

  As shown in FIG. 4, the head module 200 includes an ink supply unit. The ink supply unit includes an ink supply chamber 232 and an ink circulation chamber 236.

  The ink supply chamber 232 and the ink circulation chamber 236 are disposed on the side opposite to the ejection surface 277 of the nozzle plate 275. The ink supply chamber 232 is connected to an ink tank (not shown) via a supply line 252. The ink circulation chamber 236 is connected to a collection tank (not shown) via a circulation line 256.

  Although the number of nozzle openings 280 is omitted in FIG. 5, a plurality of nozzle openings 280 are arranged in a two-dimensional arrangement on the ejection surface 277 of the nozzle plate 275 of one head module 200.

  That is, the head module 200 has an end surface on the long side along the V direction having an inclination of angle β with respect to the X direction, and a short side of the short side along the W direction having an inclination of angle α with respect to the Y direction. It has a parallelogram plane shape having end faces, and a plurality of nozzle openings 280 are arranged in a matrix in the row direction along the V direction and the column direction along the W direction.

  The arrangement of the nozzle openings 280 is not limited to the mode illustrated in FIG. 5, and a plurality of nozzle openings 280 are arranged along the row direction along the X direction and the column direction obliquely intersecting the X direction. May be.

  Here, the matrix arrangement of the nozzle openings 280 refers to the nozzle openings 280 in the X-direction projection nozzle row in which the plurality of nozzle openings 280 are projected in the X direction and the plurality of nozzle openings 280 are arranged along the X direction. This is the arrangement of the nozzle openings 280 in which the arrangement distance intervals are uniform.

  In the projection nozzle row in the X direction, the liquid ejection head 56 shown in the present embodiment belongs to the nozzle opening 280 belonging to one head module 200 and to the other head module 200 at a connecting portion between adjacent head modules 200. The nozzle openings 280 are mixed.

  When there is no attachment position error in each head module 200, the nozzle opening 280 belonging to one head module 200 and the nozzle opening 280 belonging to the other head module 200 in the connection area are arranged at the same position. Also, the arrangement of the nozzle openings 280 is uniform.

  In the following description, it is assumed that the head module 200 constituting the liquid ejection head 56 is attached without an error in the attachment position.

<Internal structure of head module>
FIG. 6 is a cross-sectional view showing the internal structure of the head module. The head module 200 includes an ink supply path 214, an individual supply path 216, a pressure chamber 218, a nozzle communication path 220, a circulation individual flow path 226, a circulation common flow path 228, a piezoelectric element 230, and a vibration plate 266.

  The ink supply path 214, the individual supply path 216, the pressure chamber 218, the nozzle communication path 220, the circulation individual flow path 226, and the circulation common flow path 228 are formed in the flow path structure 210. The nozzle part 281 includes a nozzle opening 280 and a nozzle communication path 220.

  The individual supply path 216 is a flow path connecting the pressure chamber 218 and the ink supply path 214. The nozzle communication path 220 is a flow path that connects the pressure chamber 218 and the nozzle opening 280. The circulation individual flow path 226 is a flow path that connects the nozzle communication path 220 and the circulation common flow path 228.

  A diaphragm 266 is provided on the flow path structure 210. A piezoelectric element 230 is disposed on the vibration plate 266 with an adhesive layer 267 interposed therebetween. The piezoelectric element 230 has a laminated structure of a lower electrode 265, a piezoelectric layer 231, and an upper electrode 264. The lower electrode 265 may be referred to as a common electrode, and the upper electrode 264 may be referred to as an individual electrode.

  The upper electrode 264 is an individual electrode patterned corresponding to the shape of each pressure chamber 218, and a piezoelectric element 230 is provided for each pressure chamber 218.

  The ink supply path 214 is connected to the ink supply chamber 232 described with reference to FIG. 4, and ink is supplied from the ink supply path 214 to the pressure chamber 218 via the individual supply path 216. According to the image data, by applying a driving voltage to the upper electrode 264 of the piezoelectric element 230 provided in the corresponding pressure chamber 218, the piezoelectric element 230 and the diaphragm 266 are deformed and the volume of the pressure chamber 218 is changed. Then, ink is ejected from the nozzle opening 280 via the nozzle communication path 220 due to a pressure change accompanying this.

  By controlling the driving of the piezoelectric element 230 corresponding to each nozzle opening 280 according to dot data generated from the image data, ink droplets can be ejected from the nozzle opening 280. Ink droplets are an aspect of liquid. The pressure chamber 218 and the piezoelectric element 230 are components of the ejection element.

  By controlling the ejection timing of the ink droplets from the nozzle openings 280 in accordance with the transport speed of the paper S while transporting the paper S in the paper transport direction at a constant speed, a desired image is formed on the paper S. It is formed.

  Although not shown, the pressure chamber 218 provided corresponding to each nozzle opening 280 has a substantially square planar shape, and the outlet to the nozzle opening 280 is located at one of the diagonal corners. And an individual supply path 216 serving as an inlet for supply ink.

  The shape of the pressure chamber is not limited to a square. The planar shape of the pressure chamber may have various forms such as a square such as a rhombus and a rectangle, a pentagon, a hexagon and other polygons, a circle and an ellipse.

  A circulation outlet (not shown) is formed in the nozzle portion 281 including the nozzle opening 280 and the nozzle communication path 220. The nozzle part 281 is communicated with the circulation individual flow path 226 through a circulation outlet. Of the ink in the nozzle portion 281, ink that is not used for ejection is collected into the circulation common channel 228 via the circulation individual channel 226.

  The circulation common flow path 228 is connected to the ink circulation chamber 236 described with reference to FIG. By constantly collecting the ink through the circulation individual flow path 226 to the circulation common flow path 228, the viscosity increase of the ink in the nozzle portion at the time of non-ejection is prevented.

  The internal structure of the head module 200 is not limited to the structure shown in FIGS. The nozzle openings 280 and the nozzle portions 281 may be arranged in a line in the width direction of the paper S, or in two or more lines.

  In FIG. 6, as an example of the piezoelectric element, a piezoelectric element 230 having a structure separated individually corresponding to each nozzle portion 281 is illustrated. Of course, a structure in which the piezoelectric layer 231 is integrally formed with respect to the plurality of nozzle portions 281, individual electrodes are formed corresponding to the respective nozzle portions 281, and an active region is formed for each nozzle portion 281 is applied. Also good.

  A heater is provided in the pressure chamber 218 as a pressure generating element instead of the piezoelectric element, and a driving voltage is supplied to the heater to generate heat, and ink in the pressure chamber 218 is ejected from the nozzle opening 280 using a film boiling phenomenon. A thermal method may be applied.

[Description of Media Sorting According to First Embodiment]
Next, medium sorting according to the first embodiment will be described. The medium sorting according to the present embodiment is configured to include nozzle check pattern formation, image defect determination, and burnt paper setting processing. Below, each above-mentioned structure is demonstrated in detail.

<Description of check pattern>
FIG. 7 is an explanatory diagram schematically showing a nozzle check pattern. As shown in FIG. 7, a nozzle check pattern 202 is formed in the leading edge side margin area 201 of the paper S. A nozzle check pattern 202 for one color is formed on one sheet S. The nozzle check pattern 202 is an aspect of the check pattern.

  FIG. 7 shows a part of the nozzle check pattern 202 in an enlarged manner. As the nozzle check pattern 202 shown in FIG. 7, a 1 on N off pattern can be applied. In the 1-on N-off pattern, a plurality of dot rows 204 along the paper transport direction are formed at a distance of N + 1 nozzles in the direction orthogonal to the paper transport direction, and the dot rows 204 along the direction orthogonal to the paper transport direction are formed. The stages are arranged in N + 1 stages with the phase in the direction perpendicular to the paper transport direction being shifted with respect to the paper transport direction.

  The dot row 204 constituting the 1 on N off pattern is a line segment having a certain length in the paper transport direction.

  In the formation of the 1 on N off pattern, ink is ejected from the nozzle portion 281 every N + 1 nozzles in the direction orthogonal to the paper transport direction, and a plurality of dot rows 204 for one stage along the paper transport direction are formed. By sequentially switching the nozzles that discharge the nozzles, N + 1 stages are formed in the dot row 204 along the paper transport direction using all the nozzles.

  In the nozzle check pattern 202 shown in FIG. 7, the interval between the dot rows 204 in the direction orthogonal to the paper conveyance direction is four nozzle intervals, and four rows of dot rows along the direction orthogonal to the paper conveyance direction are formed. . The nozzle check pattern 202 is a 1 on 3 off pattern.

  The total length of the nozzle check pattern for one color in the paper conveyance direction is determined according to the reading resolution of the inline sensor 58 shown in FIG. If the reading resolution of the in-line sensor 58 is relatively high, the interval between the dot rows 204 in the direction orthogonal to the paper transport direction can be relatively narrowed, and the total length of the nozzle check pattern in the paper transport direction. Can be made relatively short.

  If the interval between the dot rows 204 in the direction orthogonal to the paper transport direction is relatively wide and the total length of the nozzle check pattern 202 in the paper transport direction is relatively long, the reading resolution of the in-line sensor 58 is relatively low. can do.

  The nozzle check pattern 202 may be formed in a margin area on the rear end side of the paper S. By forming the nozzle check pattern 202 in the margin area of the paper S, a dedicated medium for forming the nozzle check pattern 202 is not necessary.

  FIG. 7 illustrates an example in which the nozzle check pattern 202 for one color is formed on one sheet of paper S. However, there is a margin in the length in the sheet conveyance direction of the leading edge margin area 201 or the trailing edge margin area. In some cases, nozzle check patterns 202 of two or more colors may be formed on one sheet of paper S.

  FIG. 8 is a flowchart showing a part of the procedure for forming the nozzle check pattern. In the following description, FIGS. 1 to 7 are referred to as appropriate.

  The nozzle check pattern formation shown in FIG. 8 includes a sequence setting step S10, a K ink nozzle check pattern formation step S12, a paper presence / absence determination step S14, a C ink nozzle check pattern formation step S16, a paper presence / absence determination step S18, and a K ink nozzle check. It includes a pattern forming step S20, a paper presence / absence determination step S22, an M ink nozzle check pattern formation step S24, and a paper presence / absence determination step S26.

  The K ink in FIG. 8 is a black ink. C ink in FIG. 8 is cyan ink. The M ink in FIG. 8 is magenta ink.

  In the nozzle check pattern formation, first, in the sequence setting step S10, a nozzle check pattern formation sequence is set. In the present embodiment, the nozzle check pattern formation sequence is a sequence in which the nozzle check pattern 202 is formed in the order of black, cyan, black, and magenta, and a sequence in which this color order is repeated is applied thereafter.

  The sequence setting step S10 is executed by the sequence setting unit 126 shown in FIG.

  When the nozzle check pattern formation sequence is set in the sequence setting step S10 of FIG. 8, first, the process proceeds to the K ink nozzle check pattern formation step S12.

  In the K ink nozzle check pattern forming step S12, the nozzle check pattern 202 made of black ink is formed using the liquid discharge head 56K that discharges black ink.

  When the nozzle check pattern 202 using the liquid ejection head 56K is formed, the presence / absence of the next sheet S is determined in the sheet presence / absence determination step S14. If there is no next sheet S, which is NO in the sheet presence / absence determination step S14, nozzle check pattern formation is terminated.

  When there is a next sheet S, which is YES in the sheet presence / absence determination step S14, the process proceeds to the C ink nozzle check pattern formation step S16. The sheet presence / absence determination step S14 is executed by a sheet presence / absence determination unit (not shown). For the determination of the presence or absence of paper, paper detection information by a paper sensor (not shown) is used. The same applies to the paper presence / absence determination step S18, the paper presence / absence determination step S22, and the paper presence / absence determination step S26.

  In the C ink nozzle check pattern forming step S16, the nozzle check pattern 202 is formed using cyan ink by using the liquid discharge head 56C that discharges cyan ink.

  When the nozzle check pattern 202 using the liquid ejection head 56C is formed, the presence / absence of the next sheet S is determined in the sheet presence / absence determination step S18. When there is no next sheet S, which is NO in the sheet presence / absence determination step S18, nozzle check pattern formation is terminated.

  When there is a next sheet S that is YES in the sheet presence / absence determination step S18, the process proceeds to a K ink nozzle check pattern formation step S20. In the K ink nozzle check pattern forming step S20, the nozzle check pattern 202 made of black ink is formed using the liquid discharge head 56K that discharges black ink.

  When the nozzle check pattern 202 using the liquid ejection head 56K is formed, the presence / absence of the next sheet S is determined in the sheet presence / absence determination step S22. When there is no next sheet S, which is NO in the sheet presence / absence determination step S22, nozzle check pattern formation is terminated.

  If there is a next sheet S, which is YES in the sheet presence / absence determination step S22, the process proceeds to the M ink nozzle check pattern formation step S24. In the M ink nozzle check pattern forming step S24, a nozzle check pattern 202 is formed using magenta ink by using the liquid discharge head 56M that discharges magenta ink.

  When the nozzle check pattern 202 using the liquid ejection head 56M is formed, the presence / absence of the next sheet S is determined in the sheet presence / absence determination step S26. When there is no next sheet S, which is NO in the sheet presence / absence determination step S26, nozzle check pattern formation is terminated.

  If YES in the paper presence / absence determination step S26, the process returns to the K ink nozzle check pattern formation step S12. Thereafter, this sequence is repeatedly executed.

  In the nozzle check pattern formation shown in FIG. 8, the nozzle check pattern 202 by black ink is formed on the first sheet S using the liquid ejection head 56K. A nozzle check pattern 202 made of cyan ink is formed on the second sheet S using the liquid ejection head 56C.

  A nozzle check pattern 202 made of black ink is formed on the third sheet S using the liquid ejection head 56K. A nozzle check pattern 202 made of magenta ink is formed on the fourth sheet S using the liquid ejection head 56M. Here, the number of sheets S of paper S is a relative number.

  In other words, in the nozzle check pattern formation shown in FIG. 8, the nozzle check pattern 202 made of black ink is formed once on two sheets of paper S. Further, the nozzle check pattern 202 using cyan ink and the nozzle check pattern 202 using magenta ink are formed once on four sheets of paper.

  The nozzle check pattern 202 using black ink is formed more frequently than the nozzle check pattern 202 using cyan ink and the nozzle check pattern 202 using magenta ink.

  The reason is that black ink has higher visibility than cyan ink and magenta ink, and an ink with higher visibility has a higher possibility of finding an image defect.

  Black is an embodiment of the first color. Cyan is an embodiment of the second color. Magenta is an aspect of the second color.

  The nozzle check pattern formed by the sequence shown in FIG. 10 to FIG. 12 is a check pattern in which the formation frequency of the check pattern using the first color is higher than the formation frequency of the check pattern using the second color. It is an aspect.

  On the other hand, the nozzle check pattern 202 made of yellow ink using the liquid ejection head 56Y is not formed. This is because yellow ink has low visibility compared to other colors, and image defects are less likely to be found than other colors.

  Instead of using the yellow ink nozzle check pattern 202, an image defect can be found with a higher probability by using the nozzle check pattern 202 using another color having higher visibility than the yellow ink.

  Yellow is an embodiment of the third color. The nozzle check pattern formed by the sequence shown in FIGS. 10 to 12 is one mode of the check pattern in which the check pattern using the third color is not formed.

  The nozzle check pattern formation sequence shown in FIG. 8 is an example, and as will be described later, there are many variations in the nozzle check pattern formation sequence. Various sequences can be applied to the nozzle check pattern formation sequence in accordance with various conditions such as image defect determination conditions.

<Description of image defect determination>
FIG. 9 is a flowchart showing the flow of the procedure for determining the image defect. In the following description, FIGS. 1 to 8 will be referred to as appropriate.

  The image defect determination shown in FIG. 9 includes a nozzle check pattern reading step S30, an abnormal nozzle number measuring step S32, an abnormal nozzle number comparing step S34, and a scraped paper setting step S36.

  When the image defect determination is started, reading of the nozzle check pattern 202 is executed for each sheet S using the inline sensor 58 shown in FIGS. 1 and 2 in the nozzle check pattern reading step S30.

  When the nozzle check pattern 202 of two or more colors is formed on one sheet of paper S, reading information of the nozzle check pattern 202 for at least one color may be acquired.

  As described above, the reading information of the nozzle check pattern 202 is stored in the reading information storage unit 140 shown in FIG. When reading information of the nozzle check pattern 202 is acquired in the nozzle check pattern reading step S30, the process proceeds to the abnormal nozzle number measuring step S32.

  In the abnormal nozzle number measuring step S32, the reading data of the nozzle check pattern 202 is analyzed, and the abnormal nozzle number is measured as image information. The abnormal nozzle number measurement step S32 is executed by the read information analysis unit 142 shown in FIG.

  When the reading information of the nozzle check patterns 202 for two or more colors is acquired, the number of abnormal nozzles may be measured for the nozzle check patterns 202 for at least one color.

  The abnormal nozzle in the present embodiment refers to the nozzle portion 281 that cannot form the dot row 204 of the nozzle check pattern 202 shown in FIG. 7, the nozzle portion 281 where the positional deviation of the dot row 204 occurs, and the density of the dot row 204. Can be a nozzle part 281 that satisfies any of the conditions of the nozzle part 281 that falls outside the normal range or the nozzle part 281 where the shape of the dot row 204 falls outside the normal range.

  The abnormal nozzle number measured in the abnormal nozzle number measuring step S32 of FIG. 9 is stored in the abnormal nozzle number storage unit 144 shown in FIG. When the number of abnormal nozzles is measured in the abnormal nozzle number measuring step S32 of FIG. 9, the process proceeds to the comparison step S34.

  In the comparison step S34, it is determined whether or not the number of abnormal nozzles measured in the abnormal nozzle number measuring step S32 is greater than or equal to a preset value. If the number of abnormal nozzles is greater than or equal to the threshold value, which is YES in the comparison step S34, it is determined that there is an image defect. If it is determined in the comparison step S34 that there is an image defect, the process proceeds to a burned paper setting step S36.

  When the number of abnormal nozzles is less than the threshold, which is NO in the comparison step S34, the image defect determination is terminated.

  In the leaked paper setting step S36, information on the paper S determined to have an image defect, information on the liquid ejection head in which the nozzle check pattern 202 is formed on the paper S determined to have an image defect, and a nozzle check pattern formation sequence Paper is set using this information. When the paper leakage is set in the paper leakage setting step S36, the image defect determination is finished.

  The comparison step S34 is executed by the image defect determination unit 146 shown in FIG. The waste paper setting step S36 in FIG. 9 is executed by the waste paper setting unit 148 in FIG.

<Description of burnt paper setting according to the first embodiment>
Next, the waste paper setting according to the first embodiment will be described in detail with reference to FIGS.

  FIG. 10 is an explanatory diagram schematically showing the setting of the waste paper when it is determined that there is an image defect by the nozzle check pattern using black ink. In FIG. 10, the alphabet attached to the lower side of the paper S indicates the color of the nozzle check pattern 202 formed on the paper S.

Further, the subscript “S” representing the sheet indicates the number of sheets. For example, S _i represents the i th sheet S. The same applies to FIGS. 11 and 12.

  The nozzle check pattern formation sequence shown in FIG. 10 is a sequence in which a nozzle check pattern for one head is formed on each sheet S in the order of black, cyan, black, and magenta, which has been described with reference to FIG. Applies. The same applies to FIGS. 11 and 12.

As shown in FIG. 10, a black ink nozzle check pattern 202 is formed on the _i-th sheet Si by the liquid discharge head 56K shown in FIG. When i-th image defects image formed on the sheet S _i of is determined that there is set as the paper S _i Hayare paper.

Between the i th sheet S _i and the same color of the black ink by the nozzle check pattern 202 i-2 th formed paper S _i-2 and i sheet of paper S _i, i There is a _first sheet S _i-1 .

Similarly, between the sheet S _{i + 2} of the sheet S _i of the i-th nozzle check pattern 202 is formed and i + 2 th with the black ink, there is a i + 1 th sheet S _{i + 1.} The sheet S _i−1 and the sheet S _{i + 1} between the sheets S on which the nozzle check pattern 202 is formed with black ink are set as burned sheets.

That is, the i th it is determined that there is an image defect sheet S _i, paper plus 1 sheet of the i th sheet S _i S _{i + 1,} and i th negative first sheet of paper S _i Three sheets S of S _i-1 are set as burned sheets.

The paper S _i-1 and the paper S _{i + 1} are papers that are determined to have no image defects. However, the sheet S _i-1 is a sheet in which the presence or absence of an image defect using the nozzle check pattern 202 with cyan ink is determined.

Further, the sheet S _{i + 1} is a sheet on which the presence or absence of an image defect using the magenta ink nozzle check pattern 202 is determined. The presence or absence of an image defect using the nozzle check pattern 202 with black ink is not determined for the paper S _i-1 and the paper S _{i + 1} .

Then, since it is not determined whether or not the black ink image defect has occurred in the paper S _i-1 and the paper S _{i + 1} , there is a possibility that the black ink image defect has occurred.

That is, the black of the following sheet S _i-1 of the last sheet S _i-2 where it is determined that the normal image is formed by the nozzle check pattern 202 with the black ink, since the sheet is determined that there is an image defect S _i There is a possibility that an image defect of black ink has occurred up to the sheet S _{i + 1} immediately before the first sheet S _{i + 2} in which it is determined that the normal image is formed by the nozzle check pattern 202 with ink.

Therefore, from the sheet S _i-1 immediately after the last sheet S _i-2 determined to have a normal image formed by the nozzle check pattern 202 using black ink, the sheet S _{i and} subsequent ones determined to have image defects. until the first sheet S _i immediately preceding the _{+ 2} sheet S _{i + 1,} which is judged to be normal image is formed by the nozzle check pattern 202 by the black ink is set as do it paper.

The paper S before the _i- 2th paper S _i-2 shown in FIG. 10 is sent to the paper discharge tray 76 shown in FIG. 1 as the paper S on which the normal image is formed. On the other hand, the three sheets from the ( _{i−1) th} sheet S _i−1 to the (i + 1) th sheet S _{i + 1} shown in FIG. 10 are sent to the burned paper storage unit 75 shown in FIG. . The sheet S after the ( _{i + 2) th} sheet S _{i + 2} shown in FIG. 10 is sent to the paper discharge tray 76 shown in FIG. 1 as the sheet S on which the normal image is formed.

When the image formation is resumed, the images formed in order from the image formed on the sheet S _i-1 which is the leading sheet S among the sheets S _i-1 , the sheet S _i , and the sheet S _{i + 1} set as the waste paper. Formation resumes. Further, the number of sheets S set as a blank sheet is added to the number of sheets S on which image formation is performed after image formation is resumed.

  FIG. 11 is an explanatory diagram schematically showing the burnt paper setting when it is determined that the paper on which the nozzle check pattern with cyan ink is formed has an image defect.

As shown in FIG. 11, when the nozzle check pattern 202 with cyan ink is formed on the _i-th sheet S _i determined to have an image defect, the i-th sheet S _i is preceded by one time. The sheet S on which the nozzle check pattern 202 is formed with cyan ink is the i-4th sheet S _i-4 .

Between the i-4th sheet S _{i-4 on which the} nozzle check pattern 202 is formed with cyan ink and the i th sheet S _i on which the nozzle check pattern 202 is formed with cyan ink, i− There are three sheets S: a third sheet S _i-3 , an i-2th sheet S _i-2 , and an i−1th sheet S _i−1 .

Since the three sheets S _i-3 , the sheet S _i-2 , and the sheet S _i-1 are formed with the nozzle check pattern 202 using a color ink other than cyan ink, the nozzle check pattern 202 using cyan ink is formed. The presence or absence of an image defect using is not determined.

Further, the sheet S on which the nozzle check pattern 202 with cyan ink is formed one time after the _i- th sheet S _i is the (i + 4) th sheet S _{i + 4} .

Between the i-th sheet S _{i on which the} nozzle check pattern 202 with cyan ink is formed and the i + 4th sheet S _{i + 4} on which the nozzle check pattern 202 with cyan ink is formed, the (i + 1) th sheet S _{There are} three sheets S, _{i + 1} , i + 2 sheets S _{i + 2} , and i + 3 sheets S _{i + 3} .

Since these three sheets S _{i + 1} , sheet S _{i + 2} , and sheet S _{i + 3} have the nozzle check pattern 202 formed with ink of a color other than cyan ink, image defects using the nozzle check pattern 202 with cyan ink are eliminated. Presence / absence is not determined.

Therefore, when the nozzle check pattern 202 made of cyan ink is formed on the _i-th paper S _i determined to have an image defect, i between the sheets S on which the nozzle check pattern 202 made of cyan ink is formed. -3rd sheet S _i-3 , i-2th sheet S _i-2 , i-1st sheet S _i-1 , i + 1th sheet S _{i + 1} , i + 2th sheet S _{i + 2} , And i + 3th sheet S _{i + 3} , and i-th sheet S _i are set as seven sheets S.

That is, the paper is determined that there is an image defect S _i, and the sheet S in which the nozzle check pattern 202 by the ink of the same color as the nozzle check pattern 202 formed on the discriminated sheet S _i and there is an image defect is formed _i-4 is a sheet between the sheet S _{i + 4} from the paper nozzle check pattern 202 and the nozzle check pattern 202 formed on the discriminated sheet S _i and there is an image defect by inks of different colors are formed S _{i −3} , paper S _i−2 , paper S _i−1 , paper S _{i + 1} , paper S _{i + 2} , and paper S _{i + 3} are set as burned paper.

Here, the sheet S _i-4 nozzle check pattern 202 is formed by the same ink color as the nozzle check pattern 202 formed on the sheet S _i which is determined that there is an image defect and the sheet S _{i + 4,} the image defect The paper is determined not to exist.

When the image formation is resumed, the image formation is resumed in order from the image formed on the paper S _i-3 that is the leading paper S among the papers S _i-3 to S _{i + 3} set as the waste paper. .

  FIG. 12 is an explanatory diagram schematically showing the setting of the waste paper when it is determined that there is an image defect by the nozzle check pattern using magenta ink.

When the nozzle check pattern 202 with magenta ink is formed on the _i-th sheet S _i determined to have an image defect using the liquid ejection head 56M, there is an image defect described with reference to FIG. As in the case where the nozzle check pattern 202 is formed with cyan ink using the liquid discharge head 56C, the _i-th sheet S _i determined as 7 is the seventh sheet from the i-3th sheet to the i + 3rd sheet. The paper S is set as a cut paper.

When the image formation is resumed, the i-th sheet S _i determined to have an image defect is performed as in the case where the nozzle check pattern 202 is formed with cyan ink using the liquid ejection head 56C. Image formation is resumed from the image formed on the top sheet _Si-3 .

In other words, assuming that the number of sheets between the sheets S on which the nozzle check pattern 202 of the same color as the _i-th sheet S _i determined to have an image defect is A is minus of the _i-th sheet S _i . from a sheet of paper _{S i-a, 2 × a} + 1 sheets S until the sheet S _{i + a} plus a th i th sheet S _i is set as the paper do it.

Then, image formation is resumed from an image formed on the first sheet S _i-A among the sheets S from the sheet S _i-A to the sheet S _{i + A} set as the waste paper.

  When the burnt paper is set in this way, the paper on which normal image formation has been performed and the paper set as the burnt paper are sorted. In the present embodiment, the paper on which the normal image is formed and the burned paper are collected separately.

  Causes of image defects include air bubbles mixed in the nozzle portion 281, adhesion of minute dust or the like in the vicinity of the nozzle opening 280, or vibration generated by the paper S transport system during image formation.

  The mixing of bubbles into the nozzle portion 281 can be eliminated by discharging the bubbles by ejection. Further, adhesion of minute dust or the like in the vicinity of the nozzle opening 280 can be eliminated if dust or the like is removed by ejection. Further, the vibration generated by the conveyance system of the paper S during image formation can be eliminated by a change in conditions during image formation.

  That is, the cause of the image defect exemplified above can occur accidentally. As a result, even if an image defect occurs in an arbitrary sheet S, an image defect may not occur in the subsequent sheet S.

  In the sorting method of the sheet S shown in the present embodiment, when an image defect due to such a cause that may occur accidentally occurs, the sheet S that may have an image defect is regarded as a run-off sheet. In addition, the number of burned papers can be minimized.

<Description of image forming procedure>
FIG. 13 is a flowchart showing an image forming procedure. In the following description, FIGS. 1 to 12 will be referred to as appropriate.

  As shown in FIG. 13, the image formation includes an image defect determination step S100, a waste paper setting step S102, a restart image setting step S104, an image formation restart step S106, a next image presence / absence determination step S108, and an image formation continuation start step S110. Consists of including.

  The image defect determination step S100 is as already described with reference to FIG. 9, and description thereof is omitted here. When it is determined that there is an image defect, which is a YES determination in the image defect determination step S100, the process proceeds to a waste paper setting step S102. On the other hand, if it is determined that there is no image defect in the NO determination in the image defect determination step S100, the process proceeds to the next image presence / absence determination step S108.

  The leakage paper setting step S102 is as already described with reference to FIGS. 10 to 12, and description thereof is omitted here. When the waste paper is set in the waste paper setting step S102, the process proceeds to the restart image setting step S104.

  In the restart image setting step S104, the first image when the image formation is restarted is set after the separated sheets are sorted. The initial image setting when image formation is resumed is as already described with reference to FIGS. 10 to 12, and description thereof is omitted here.

  In the restart image setting step S104, when the first image when the image formation is restarted is set, the process proceeds to the image formation restart step S106. In the image formation restart process S106, image formation of the first image set in the restart image setting process S104 is started.

  When image formation is resumed in the image formation resumption process S106, the process proceeds to an image defect determination process S100.

  In the next image presence / absence determination step S108, the presence / absence of the next image is determined. If there is a next image, which is YES in the next image presence / absence determination step S108, the process proceeds to an image formation continuation start step S110. In the image formation continuation start step S110, the next image formation is started.

  When the next image formation is started in the image formation continuation start step S110, the process proceeds to the image defect determination step S100. Thereafter, each step of image formation is executed sequentially from the image defect discrimination step S100. If there is no next image, which is NO in the next image presence / absence determination step S108, the image formation is terminated.

  In this way, when a sheet S that has been determined to have an image defect during image formation occurs, a burnt paper is set, and a sheet on which normal image formation has been performed and a sheet set as a burnt paper are sorted. The When the waste paper is set, the image formation is restarted from the first image of the paper set as the waste paper.

<Description of effects>
According to the image forming system and the paper sorting method configured as described above, it is possible to discriminate a paper on which an image defect has occurred and a paper on which an image defect may have occurred as a broken paper. Yes, the number of scraped papers is optimized, and the decrease in productivity due to the occurrence of scraped paper can be suppressed.

  By automatically collecting the waste paper in a special waste paper storage unit, the removal of the waste paper is more efficient than the manual removal of the waste paper.

  Since the image formation is restarted from the image formed on the leading paper among the papers that have been scraped, it is not necessary to change the image forming sequence even if the paper slips. Further, there is no need for processes such as re-image formation and sorting of the paper S that has been broken.

[Description of Media Sorting According to Second Embodiment]
Next, medium sorting according to the second embodiment will be described. The medium sorting described below is a medium sorting corresponding to variable printing.

  The variable printing is a printing form in which images having different contents are printed according to a predetermined order. As an example of variable printing, printing in the page order of a booklet such as a catalog or a pamphlet can be given. Examples of other variable printing include address printing, card printing such as business cards and name tags, or numbering printing such as tickets. Another application example of variable printing is double-sided printing.

  In variable printing, if a piece of paper is broken, the printing order is changed. In addition, steps such as reprinting of waste paper and sorting of printed matter occur. If it does so, productivity will fall. Therefore, by applying the medium sorting described below, it is possible to suppress a decrease in productivity due to the occurrence of scraped paper.

<Description of variable printing procedure>
FIG. 14 is an explanatory view schematically showing an image forming procedure to which the burnt paper setting according to the second embodiment is applied. FIG. 14 shows a printing procedure for variable printing. The example shown in FIG. 14 is an example of printing a printed material composed of 1 page to 12 pages in descending order from 12 pages to 1 page. A subscript S indicating paper indicates the number of pages.

  As shown in FIG. 14, a nozzle check pattern 202 for one head is formed on one sheet of paper S. On the 12th page, a nozzle check pattern 202 of black ink is formed using the liquid discharge head 56K.

  On page 11, a nozzle check pattern 202 made of magenta ink is formed using the liquid discharge head 56M. On the tenth page, a nozzle check pattern 202 made of black ink is formed using the liquid discharge head 56K.

  On the ninth page, a nozzle check pattern 202 made of cyan ink is formed using the liquid discharge head 56C. In this way, nozzle check patterns 202 are formed in order up to one page.

FIG. 15 is an explanatory view schematically showing the setting of the waste paper according to the second embodiment. FIG. 15 shows a case where it is determined that an image defect has been found on the paper S of j pages. A j-page sheet S _j has a nozzle check pattern 202 formed of black ink using a liquid discharge head 56K.

The sheet S _{j + 2} on which the nozzle check pattern 202 with black ink is formed using the liquid discharge head 56K one time before the j page is the j + 2 page. The sheet S _j-2 on which the nozzle check pattern 202 with black ink is formed using the liquid discharge head 56K after j pages is j-2 page.

  The number A of sheets between the sheets S on which the nozzle check pattern 202 with black ink is formed is one.

Three sheets S, which are j pages of paper S _j , j pages of plus one page of paper S _{j + 1} , and j pages of minus one page of paper S _j−1 , are set as broken sheets. After the waste paper is sorted, image formation is resumed from page j + 1, which is the first page of the waste paper.

<Description of effects>
According to the image forming system and the paper sorting method configured as described above, it is possible to obtain the same functions and effects as in the first embodiment. In addition, since image formation is restarted from the first page of the paper that has become scraped paper, even if scraped paper is generated, image formation in the page order is maintained.

[Description of Modified Example of Image Forming Sequence]
Next, a modified example of the image forming sequence will be described. In the following description, a modified example of the second embodiment will be described, but the following modified example can also be applied to the first embodiment.

<Description of the first modification>
FIG. 16 is an explanatory diagram schematically showing an image forming procedure in the first modification. In the following description, FIGS. 7 and 15 will be referred to as appropriate.

  The image forming procedure shown in FIG. 16 is different from the image forming procedure shown in FIG. 15 in the nozzle check pattern forming sequence. As shown in FIG. 16, the nozzle check pattern 202 is formed on each sheet S in order of black, cyan, and magenta from the 12th page.

  In the image forming procedure shown in FIG. 16, the number A of sheets between the sheets S on which the nozzle check patterns 202 of each color are formed is 2. Therefore, even if an image defect occurs on any page, from the page on which the image defect has occurred. Five sheets S of plus 2 pages and minus 2 pages from the page where the image defect has occurred are set as run sheets.

  The medium sorting according to the first modification is effective when the frequency at which black ink is used is lower than the frequency at which cyan ink is used or the frequency at which magenta ink is used.

<Description of the second modification>
FIG. 17 is an explanatory view schematically showing an image forming procedure according to the second modification. In the following description, FIGS. 7 and 16 will be referred to as appropriate.

  The image forming procedure shown in FIG. 17 is different from the image forming procedure shown in FIG. 16 in that a nozzle check pattern 202 using yellow ink is formed. As shown in FIG. 17, a nozzle check pattern 202 is formed on each sheet S in order of black, cyan, magenta, and yellow from page 12.

  In the image forming procedure shown in FIG. 17, the number A of sheets between the sheets S on which the nozzle check patterns 202 of each color are formed is 3. Therefore, even if an image defect occurs on any page, from the page on which the image defect has occurred. The sheet S for 7 pages, which is plus 3 pages and 7 pages minus 3 pages from the page where the image defect has occurred, is set as the run-off sheet.

  The medium sorting according to the second modification can obtain the same effects as the first modification. Further, the medium sorting according to the second modification is effective when an image in which the image defect of yellow ink affects the quality of the entire image is formed.

<Description of the third modification>
FIG. 18 is an explanatory view schematically showing an image forming procedure according to the third modification. In the following description, FIGS. 7 and 16 will be referred to as appropriate.

  The image forming procedure shown in FIG. 18 is different from the image forming procedure shown in FIG. 16 in that a nozzle check pattern 202 using orange ink, red ink, and green ink is formed.

  A symbol O in FIG. 18 indicates the paper S on which the nozzle check pattern 202 using orange ink is formed. A symbol R in FIG. 18 indicates the paper S on which the nozzle check pattern 202 using red ink is formed. A symbol G in FIG. 18 indicates the paper S on which the nozzle check pattern 202 using green ink is formed.

  The image forming procedure shown in FIG. 18 can be applied to a liquid discharge apparatus including a liquid discharge head using orange ink, a liquid discharge head using red ink, and a liquid discharge head using green ink. .

  That is, the image forming procedure shown in FIG. 18 can be applied to a liquid ejecting apparatus including a liquid ejecting head using a special color ink such as orange, red, or green. Other examples of the spot color ink include white ink and transparent ink.

  Since the setting of the waste paper in the image forming procedure shown in FIG. 18 can be set in the same manner as in the above-described embodiment and the modified example, the description thereof is omitted here.

  In the image forming procedure shown in FIG. 18, since the number of sheets A between the sheets S on which the nozzle check patterns 202 of each color are formed is 5, even if an image defect occurs on any page, the page from which the image defect has occurred The paper S for 11 pages of plus 5 pages and minus 5 pages from the page in which the image defect has occurred is set as the cut sheet.

  In the printing procedure shown in FIGS. 16 to 18, the frequency of forming the black ink nozzle check pattern may be higher than the frequency of forming the nozzle check patterns of other colors.

  In this specification, an inkjet recording apparatus is illustrated as an example of an image forming system, but the image forming system is not limited to an image forming system using a liquid such as ink. For example, the above-described medium sorting can be applied to an electrophotographic image forming system using toner. Note that the image forming system in this specification can be read as an image forming apparatus.

  In this specification, the image forming system using the processing liquid is illustrated as an example of the image forming system, but the above-described medium sorting can be applied to an image forming system that forms an image without using the processing liquid.

  In the embodiment of the present invention described above, the configuration requirements can be appropriately changed, added, and deleted without departing from the spirit of the present invention. The present invention is not limited to the embodiments described above, and many modifications are possible by those having ordinary knowledge in the field within the technical idea of the present invention.

  DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device, 18 ... Drawing part, 56, 56C, 56M, 56Y, 56K ... Liquid discharge head, 58 ... Inline sensor, 74 ... Paper discharge switching part, 75 ... Scrap paper storage part, 100 ... System controller, 118 ... Drawing control unit, 119 ... Nozzle check pattern data storage unit, 126 ... Sequence setting unit, 140 ... Reading information storage unit, 142 ... Reading information analysis unit, 144 ... Abnormal nozzle number storage unit, 146 ... Image defect determination unit, 148 ... Hard paper setting section

Claims (11)

A medium transport unit for transporting the medium;
An image forming unit that forms an image using two or more colors on a medium conveyed by the medium conveying unit;
A reading unit that reads an image formed on a medium by the image forming unit, acquires image information for one color for each medium based on the reading result of the image, and two or more pieces of reading information for each of a plurality of media A reading unit that acquires image information for the colors of
From the image information for one color for each medium acquired by the reading unit, an image defect determination unit for determining the presence or absence of an image defect for each medium;
A medium that has been determined to have an image defect by the image defect determination unit is an i-th medium, and a medium in which image information of the same color as the medium that has been determined to have an image defect by the image defect determination unit has been acquired. A waste paper setting unit for setting the medium from the i-Ath sheet to the i + Ath sheet as a waste paper;
An image forming system. The image forming unit forms a check pattern for at least one color for each medium for two or more colors according to a predetermined sequence, and the check pattern for two or more colors is formed using a plurality of media. Forming,
The reading unit acquires image information for one color from the reading result of the check pattern for each medium, and acquires image information for two or more colors from the reading result of the check pattern for each of a plurality of media. The image forming system according to claim 1.   When the image forming unit forms the check pattern of the first color and the second color having a lower image defect visibility than the first color, the frequency of forming the check pattern using the first color is The image forming system according to claim 2, wherein the image forming system is set to be higher than a check pattern forming frequency using two colors. The image forming unit forms an image using a first color, a second color having a lower image defect visibility than the first color, and a third color having a lower image defect visibility than the second color. And
The image forming system according to claim 2 or 3, wherein when the check pattern is formed, the check pattern using the third color is not formed.   The image forming unit performs image formation in order from the image formed on the first medium among the media set as the waste paper by the good paper setting unit when the perfect paper is set by the good paper setting unit. The image forming system according to claim 1, wherein the image forming system is restarted. The image forming unit includes a head for each color,
The image forming system according to claim 1, wherein the image defect determination unit determines presence / absence of an image defect from a state of each head.   The image forming system according to any one of claims 1 to 6, wherein the image defect determination unit determines that a medium having an abnormality equal to or greater than a predetermined threshold in the image information is a medium having an image defect. .   The medium transport unit includes a transport path switching unit that switches a transport path between a medium determined to have an image defect by the image defect determination unit and a medium determined to have no image defect by the image defect determination unit. The image forming system according to claim 1.   The image forming system according to any one of claims 1 to 8, further comprising a waste paper storage unit that stores a medium set as a waste paper by the waste paper setting unit.   The image forming unit forms a plurality of types of images according to a predetermined order, and restarts image formation from the image formed on the leading medium among the media determined to be scraped paper by the scraped paper setting unit. The image forming system according to any one of claims 1 to 9. An image forming step of forming an image using two or more colors on the medium conveyed by the medium conveying unit;
A reading step of reading an image formed on the medium by the image forming step, acquiring image information for one color for each medium based on the reading result of the image, and two or more from the reading result for each of a plurality of media A reading step of acquiring image information for the colors of
From the image information for one color for each medium acquired by the reading step, an image defect determination step for determining the presence or absence of an image defect for each medium;
A medium that has been determined to have an image defect by the image defect determination step is an i-th medium, and a medium in which image information of the same color as the medium that has been determined to have an image defect by the image defect determination step has been acquired. A waste paper setting step in which the number of media in between is A, and the media from the i-Ath sheet to the i + Ath sheet is set as a waste paper;
Sorting method including:

Images