JP2018187792A - Liquid discharge device and operation method for liquid discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress wasteful repetition of cleaning and to suppress waste of liquid.SOLUTION: A liquid discharge device comprises: a liquid discharge head having a discharge surface formed with nozzles discharging liquid; a cleaning device cleaning the discharge surface; an imaging device imaging an image of the discharge surface; and a control part imaging an image before cleaning and an image after the cleaning by the cleaning device by the imaging device and performing notification processing for urging replacement of the liquid discharge head according to an amount of a change of the image after the cleaning with respect to the image before the cleaning.SELECTED DRAWING: Figure 8B

Description

  The present invention relates to a technique for discharging a liquid such as ink.

  In a liquid ejecting apparatus that ejects a liquid such as ink from a plurality of nozzles formed on the ejection surface of a liquid ejection head, a technique for cleaning the ejection surface has been proposed in order to maintain a good liquid ejection state. Patent Document 1 discloses a cleaning technique that removes deposits such as ink and paper powder adhering to the ejection surface by wiping the ejection surface of the ejection head after ejecting liquid from the nozzle (liquid ejection). Has been. In Patent Document 1, the ejection surface after wiping is imaged with a CCD camera, and the area of ink remaining on the ejection surface is measured from the captured image. Ink remaining on the ejection surface is removed by repeating cleaning by changing the cleaning conditions (liquid discharge pressure, pressing force against the ejection surface of the wiping blade, etc.) according to the measured ink area. .

JP 2011-005357 A

  However, stains that cannot be removed by cleaning such as liquid discharge or wiping may occur on the ejection surface of the liquid ejection head, such as scratches or solidified ink. In Patent Document 1, cleaning is repeated by changing the cleaning conditions according to the area of the residual ink measured only from the image of the ejection surface after wiping. Therefore, if dirt that cannot be removed by cleaning occurs, cleaning is performed. No matter how many times it is repeated, stains remain on the image of the ejection surface after wiping. In addition, when liquid discharge and wiping are repeated, wear of the discharge surface proceeds and a large amount of liquid is wasted. In view of the above circumstances, an object of the present invention is to suppress wasteful repetition of cleaning and suppress waste of liquid.

  In order to solve the above problems, a liquid ejection apparatus according to the present invention captures an image of the ejection surface, a liquid ejection head having an ejection surface on which a nozzle for ejecting liquid is formed, a cleaning device for cleaning the ejection surface, and the like. An imaging device that performs cleaning, an image before cleaning by the cleaning device, and an image after cleaning by the imaging device, and performs notification processing that prompts replacement of the liquid ejection head according to the amount of change in the image after cleaning relative to the image before cleaning A control unit. According to the above aspect, since the notification process for prompting the replacement of the liquid ejection head is performed according to the amount of change in the image of the ejection surface after cleaning with respect to the image of the ejection surface before cleaning imaged by the imaging device, wasteful cleaning is performed. Repetition can be suppressed, and waste of liquid due to cleaning can be suppressed. In addition, according to this aspect, it is possible to determine with high accuracy whether or not dirt that cannot be removed by cleaning, such as scratches on the ejection surface or fixed ink, has occurred depending on the amount of change in the image. Can be notified in advance before repeating cleaning unnecessarily at an appropriate timing.

  In a preferred aspect of the present invention, the control unit performs notification processing that prompts replacement of the liquid ejection head when the amount of change is not equal to or greater than a predetermined threshold value. According to the above aspect, it is possible to easily determine whether or not to end the maintenance process by performing the notification process for urging replacement of the liquid ejection head by simply comparing the amount of change with a predetermined threshold value.

  In order to solve the above problems, a liquid ejection apparatus according to the present invention captures an image of the ejection surface, a liquid ejection head having an ejection surface on which a nozzle for ejecting liquid is formed, a cleaning device for cleaning the ejection surface, and the like. An image pickup device, an image before use of the liquid discharge head and an image after cleaning by the cleaning device are picked up by the image pickup device, and a notification prompting replacement of the liquid discharge head according to a change amount of the image after cleaning with respect to the image before use And a control unit that performs processing. According to the above aspect, since the notification process for prompting the replacement of the liquid discharge head is performed according to the amount of change in the image of the discharge surface after cleaning with respect to the image of the discharge surface before use captured by the imaging device, wasteful cleaning is performed. Repetition can be suppressed, and waste of liquid due to cleaning can be suppressed. In addition, according to this aspect, according to the amount of change, it is possible to determine with high accuracy whether or not dirt that cannot be removed only by cleaning, such as scratches on the ejection surface or fixed ink, has occurred. Can be notified in advance before repeated cleaning at an appropriate timing.

  In a preferred aspect of the present invention, when the amount of change is equal to or greater than a predetermined threshold, the control unit performs a notification process that prompts replacement of the liquid ejection head. According to the above aspect, it is possible to easily determine whether or not to end the maintenance process by performing the notification process for urging replacement of the liquid ejection head by simply comparing the amount of change with a predetermined threshold value.

  In order to solve the above problems, a liquid ejection apparatus according to the present invention captures an image of the ejection surface, a liquid ejection head having an ejection surface on which a nozzle for ejecting liquid is formed, a cleaning device for cleaning the ejection surface, and the like. A first difference that is an amount of change of an image before cleaning with respect to an image before use and an image before cleaning by the imaging device, an image before cleaning by the cleaning device and an image before cleaning by the imaging device. A control unit that performs notification processing that prompts replacement of the liquid ejection head according to a third difference value that is a change amount between the value and a second difference value that is a change amount of the image after cleaning with respect to the image before use. Prepare. According to the above aspect, the first difference value that is the amount of change in the image on the ejection surface before cleaning with respect to the image on the ejection surface before use captured by the imaging device, and the ejection after cleaning on the image on the ejection surface before use. Since the notification process for urging the replacement of the liquid ejection head is performed according to the third difference value that is the change amount from the second difference value that is the change amount of the image on the surface, it is possible to suppress unnecessary repetition of cleaning and prevent the liquid from being cleaned. Can be saved. In addition, according to this aspect, according to the amount of change, it is possible to determine with high accuracy whether or not dirt that cannot be removed only by cleaning, such as scratches on the ejection surface or fixed ink, has occurred. Can be notified in advance before repeated cleaning at an appropriate timing.

  In a preferred aspect of the present invention, when the third difference value is not equal to or greater than a predetermined threshold value, the control unit performs a notification process that prompts replacement of the liquid ejection head. According to the above aspect, it is possible to easily determine whether or not to end the maintenance process by performing the notification process for prompting the replacement of the liquid discharge head by simply comparing the change amount of the image with the predetermined threshold value.

  In a preferred aspect of the present invention, the image for calculating the amount of change is an image of an area including the nozzles on the ejection surface. According to the above aspect, the image for calculating the amount of change is an area of the ejection surface that includes the nozzle, that is, an area that has a large influence on the nozzle (an adverse effect on the ejection performance) when the ejection surface is dirty. Since the amount of change is calculated based on the image, the replacement of the liquid ejection head can be notified in advance at an appropriate timing.

  In a preferred aspect of the present invention, the amount of change in the image is at least one of the amount of change in the luminance of the image on the ejection surface, the amount of change in the color difference of the image on the ejection surface, and the amount of change in the area of the liquid attached to the ejection surface. One. According to the above aspect, whether the dirt on the ejection surface can be removed by cleaning (for example, dirt due to unsolidified ink) or whether the dirt on the ejection surface cannot be removed by cleaning (for example, scratches or dirt due to solidified ink). Is easy to distinguish.

  In order to solve the above problems, the present invention is an operation method of a liquid discharge apparatus including a liquid discharge head having a discharge surface on which a nozzle for discharging a liquid is formed, and images an image before cleaning the discharge surface A notification process that cleans the ejection surface, captures an image after cleaning the ejection surface, calculates the amount of change in the image after cleaning relative to the image before cleaning, and prompts replacement of the liquid ejection head according to the amount of change. Do. According to the above aspect, since the notification process for prompting the replacement of the liquid discharge head is performed according to the amount of change in the image of the discharge surface before and after cleaning, wasteful repetition of cleaning can be suppressed and waste of liquid due to cleaning can be suppressed. . In addition, according to this aspect, according to the amount of change, it is possible to determine with high accuracy whether or not dirt that cannot be removed by cleaning alone, such as ink fixed on the ejection surface, can be determined. Can be notified in advance at an appropriate timing.

  In order to solve the above problems, the present invention provides an operation method of a liquid discharge apparatus including a liquid discharge head having a discharge surface on which a nozzle for discharging a liquid is formed, and before the use of the discharge surface of the liquid discharge head , Clean the ejection surface, take the image after cleaning the ejection surface, calculate the amount of change in the image after cleaning with respect to the image before use, and replace the liquid ejection head according to the amount of change. Prompt notification process. According to the above aspect, the amount of change in the image on the ejection surface after cleaning with respect to the image on the ejection surface before use is calculated, and the notification process for prompting the replacement of the liquid ejection head is performed according to the amount of change, so cleaning waste Can be prevented, and waste of liquid due to cleaning can be suppressed. In addition, according to this aspect, according to the amount of change, it is possible to determine with high accuracy whether or not dirt that cannot be removed only by cleaning, such as scratches on the ejection surface or fixed ink, has occurred. Can be notified in advance at an appropriate timing.

  In order to solve the above problems, the present invention provides an operation method of a liquid discharge apparatus including a liquid discharge head having a discharge surface on which a nozzle for discharging a liquid is formed, and before the use of the discharge surface of the liquid discharge head The first image which is the amount of change of the image before cleaning with respect to the image before use with respect to the image before use. Calculating a difference value, calculating a second difference value that is a change amount of the image after cleaning with respect to the image before use, calculating a third difference value that is a change amount of the second difference value with respect to the first difference value; A notification process that prompts replacement of the liquid discharge head is performed according to the third minute value. According to the above aspect, the first difference value that is the amount of change in the image on the ejection surface before cleaning with respect to the image on the ejection surface before use, and the change in the image on the ejection surface after cleaning with respect to the image on the ejection surface before use. A notification process that calculates a second difference value that is an amount and a third difference value that is an amount of change between the first difference value and the second difference value, and prompts replacement of the liquid ejection head according to the third difference value. Therefore, it is possible to suppress unnecessary repetition of cleaning and to prevent waste of liquid due to cleaning. In addition, according to this aspect, according to the amount of change, it is possible to determine with high accuracy whether or not dirt that cannot be removed only by cleaning, such as scratches on the ejection surface or fixed ink, has occurred. Can be notified in advance at an appropriate timing.

  In a preferred aspect of the present invention, the first difference value is calculated before cleaning the ejection surface, and it is determined whether or not cleaning of the ejection surface is executed according to the first difference value. According to the above aspect, since it is determined whether or not to perform the cleaning of the ejection surface according to the first difference value before the cleaning, it is possible to suppress the ink consumption and the abrasion of the ejection surface due to unnecessary cleaning.

It is a block diagram of the liquid discharge apparatus which concerns on 1st Embodiment. It is a figure for demonstrating the structure of a cleaning apparatus. It is a functional block diagram of a liquid discharge apparatus. It is a figure which shows the specific example of the discharge waveform of a drive signal. It is sectional drawing of a liquid discharge part. It is a top view which shows the discharge surface before cleaning and after cleaning. It is a flowchart of the maintenance process which concerns on 1st Embodiment. It is a figure which shows the image and the variation | change_quantity of a brightness | luminance before and behind cleaning. It is a figure which shows the image and the variation | change_quantity of a brightness | luminance before and behind cleaning. It is a flowchart of the maintenance process which concerns on 2nd Embodiment. It is a figure which shows the variation | change_quantity of the image and brightness | luminance before head use and after cleaning. It is a figure which shows the variation | change_quantity of the image and brightness | luminance before head use and after cleaning. It is a flowchart of the maintenance process which concerns on 3rd Embodiment. It is a figure which shows the variation | change_quantity of the image and brightness | luminance before a head use and before and after cleaning.

<First Embodiment>
FIG. 1 is a partial configuration diagram of a liquid ejection apparatus 10 according to the first embodiment of the present invention. The liquid ejection apparatus 10 according to this embodiment is an ink jet printing apparatus that ejects ink, which is an example of a liquid, onto a medium 12 such as a printing paper. A liquid ejection apparatus 10 shown in FIG. 1 includes a control unit 20, a transport mechanism 22, a carriage 24, a liquid ejection head 26, and a cleaning device 30. Although FIG. 1 illustrates the case where one liquid ejection head 26 is mounted on the carriage 24, the present invention is not limited to this, and a plurality of liquid ejection heads 26 may be mounted on the carriage 24. A liquid container (cartridge) 14 for storing ink is attached to the liquid ejection apparatus 10.

  The liquid container 14 is an ink tank type cartridge composed of a box-shaped container that can be attached to and detached from the main body of the liquid ejection apparatus 10. The liquid container 14 is not limited to a box-shaped container, and may be an ink pack type cartridge including a bag-shaped container. Ink is stored in the liquid container 14. The ink may be a black ink or a color ink. The ink stored in the liquid container 14 is supplied (pressure fed) to the liquid ejection head 26 by a pump (not shown).

  The control unit 20 includes, for example, a control device 202 such as a CPU (Central Processing Unit) or FPGA (Field Programmable Gate Array) and a storage device 203 such as a semiconductor memory, and stores a control program stored in the storage device 203. When executed by the control device 202, each element of the liquid ejection device 10 is comprehensively controlled. As shown in FIG. 1, print data G representing an image to be formed on the medium 12 is supplied to the control unit 20 from an external device (not shown) such as a host computer. The control unit 20 controls each element of the liquid ejection device 10 so that an image designated by the print data G is formed on the medium 12.

  The transport mechanism 22 transports the medium 12 in the Y direction under the control of the control unit 20. The liquid discharge head 26 is mounted on a substantially box-shaped carriage 24 and discharges ink supplied from the liquid container 14 to the medium 12 under the control of the control unit 20. The control unit 20 reciprocates the carriage 24 along the X direction that intersects the Y direction. In parallel with the transport of the medium 12 by the transport mechanism 22 and the reciprocating reciprocation of the carriage 24, the liquid discharge head 26 discharges ink onto the medium 12, thereby forming a desired image on the surface of the medium 12. Note that the liquid container 14 can be mounted on the carriage 24 together with the liquid discharge head 26.

  A nozzle row is arranged on the ejection surface (surface facing the medium 12) 260 of the liquid ejection head 26. The nozzle row is a set of a plurality of nozzles N arranged linearly along the Y direction. From the nozzle N, ink supplied from the liquid container 14 is ejected. Note that the number and arrangement of the nozzle rows are not limited to those illustrated, and two or more nozzle rows may be arranged on the ejection surface 260 of the liquid ejection head 26. For example, the plurality of nozzle rows may be arranged in a staggered arrangement or a staggered arrangement. It can also be an array. A direction perpendicular to the XY plane (a plane parallel to the surface of the medium 12) is expressed as a Z direction.

  FIG. 2 is a diagram for explaining the configuration of the cleaning device 30 of the present embodiment. As shown in FIGS. 1 and 2, the cleaning device (maintenance unit) 30 includes a wiping mechanism 32, a capping mechanism 34, and an imaging mechanism 36 that are controlled by the control unit 20. The cleaning device 30 is disposed, for example, in the non-printing area H that is the home position (standby position) of the liquid ejection head 26 in the X direction. The non-printing area H of the present embodiment includes an imaging area H1 and a cleaning area H2. As a maintenance process for the liquid ejection head 26, the control unit 20 performs an imaging process for the ejection surface 260 when the liquid ejection head 26 is in the imaging area H1, and an ejection surface 260 when the liquid ejection head 26 is in the cleaning area H2. Perform cleaning. In the present embodiment, the case where the imaging mechanism 36 is provided in the cleaning device 30 is illustrated, but the present invention is not limited thereto, and the imaging mechanism 36 may be provided separately from the cleaning device 30. When the image pickup mechanism 36 is provided separately, the image pickup mechanism 36 may be disposed in a non-printing area opposite to the cleaning device 30 with the medium 12 interposed therebetween.

  The wiping mechanism 32 is used when performing wiping for wiping the ejection surface 260 of the liquid ejection head 26 and removing deposits such as ink in the cleaning. The wiping mechanism 32 has a wiper 322 that moves while contacting the ejection surface 260. The wiper 322 is formed by forming an elastic member such as rubber in a blade shape. The shape of the wiper 322 is not limited to the blade shape, and may be a strip shape, for example. The material of the wiper 322 is not limited to the elastic member, and may be a fiber member such as a woven fabric or a non-woven fabric. As shown in FIG. 2, the wiping mechanism 32 is movable in the X direction along the ejection surface 260 of the liquid ejection head 26 by a motor (not shown). Accordingly, the wiping mechanism 32 moves in the X direction along the discharge surface 260 while the tip of the wiper 322 is in contact with the discharge surface 260, so that the discharge surface 260 can be wiped. However, the direction in which the wiping mechanism 32 moves is not limited to the X direction, and may be the Y direction. Further, in the present embodiment, the case where the wiper 322 moves relative to the ejection surface 260 of the liquid ejection head 26 is illustrated, but the present invention is not limited to this, and the wiper 322 and the ejection surface 260 of the liquid ejection head 26 are not limited to this. At least one should just move relatively with respect to the other.

  The capping mechanism 34 is used when capping the ejection surface 260 of the liquid ejection head 26 in the cleaning. The capping mechanism 34 includes a cap 342 that seals the nozzle N on the ejection surface 260. The cap 342 is formed in a box shape having an open negative side in the Z direction. When the opening edge of the cap 342 contacts the discharge surface 260, the nozzle N of the discharge surface 260 is sealed. The cap 342 can be moved by a motor (not shown) to the negative side in the Z direction that contacts the discharge surface 260 or the positive side in the Z direction that is separated from the discharge surface 260. The control unit 20 contacts the ejection surface 260 with the cap 342 and seals the nozzle N.

  The imaging mechanism 36 includes an imaging device 362 and a shutter 364. The imaging device 362 is a camera that images the ejection surface 260 of the liquid ejection head 26. The imaging device 362 is constituted by, for example, a CCD (Charge Coupled Device) camera. As shown in FIGS. 1 and 2, the cleaning device 30 has an opening 302 formed at a position facing the ejection surface 260 of the liquid ejection head 26 when the liquid ejection head 26 is in the imaging region H1. Yes.

  As shown in FIG. 1, the opening 302 is an opening that is long in the Y direction along the nozzle row of the ejection surface 260. The imaging device 362 can be moved to the positive side and the negative side in the Y direction along the longitudinal direction (Y direction) of the opening 302 by a motor (not shown). According to such a configuration, the imaging device 362 captures an image of the ejection surface 260 of the liquid ejection head 26 through the opening 302 while moving in the Y direction along the nozzle row, so that one row of nozzle rows is obtained. An image of the discharge surface 260 can be taken. In the present embodiment, the discharge surface 260 provided with one nozzle row is illustrated, but in the case of the discharge surface 260 in which a plurality of nozzle rows are arranged in the X direction, the liquid discharge head 26 is moved in the X direction. An image of the ejection surface 260 can be captured for each nozzle row by moving the imaging device 362 in the Y direction for each nozzle row while moving the image. Note that an image including a plurality of nozzle arrays on the ejection surface 260 may be captured at a time, and the images may be divided into images for each nozzle array after being captured.

  As shown in FIG. 2, the opening 302 is provided with a shutter 364. The shutter 364 is movable in the cleaning device 30 between a position for closing the opening 302 in the X direction and a position for opening the opening 302. By closing the opening 302 with the shutter 364, ink and dust can be prevented from adhering to the imaging device 362. When the ejection surface 260 is imaged, the opening 302 is opened by the shutter 364. Note that the imaging device 362 may be moved in the X direction without providing the shutter 364. In such a configuration, the imaging device 362 is moved to a standby position that does not face the opening 302 in the X direction, and the imaging device is placed at an imaging position that faces the opening 302 when the ejection surface 260 is imaged. 362 can be moved.

  FIG. 3 is a functional configuration diagram of the liquid ejection apparatus 10. In FIG. 3, the conveyance mechanism 22, the carriage 24, and the like are not shown for convenience. The control unit 20 includes a drive signal generation unit 40, a control unit 50, an image acquisition unit 52, and a data table C. The control device 202 illustrated in FIG. 1 executes the control program, so that the control device 202 functions as the drive signal generation unit 40, the control unit 50, and the image acquisition unit 52. The control unit 50 controls the drive signal generation unit 40. The data table C is stored in the storage device 203 shown in FIG.

  The control unit 50 controls the cleaning device 30. Specifically, the control unit 50 controls the imaging mechanism 36 to capture an image of the ejection surface 260 of the liquid ejection head 26. The liquid ejection head 26 is cleaned by controlling the wiping mechanism 32 and the capping mechanism 34. The image acquisition unit 52 acquires an image of the ejection surface 260 captured by the imaging device 362. The control unit 50 performs image processing on the image of the ejection surface 260 before and after cleaning acquired by the image acquisition unit 52 and calculates the amount of change in the image. In the data table C, an image of the ejection surface 260 captured by the imaging device 362 is stored. When a plurality of nozzle rows are provided, an image of the ejection surface 260 is stored for each nozzle row. Details of the image of the ejection surface 260 and the amount of change will be described later.

  The liquid ejection device 10 includes an operation panel 13. The operation panel 13 is an operation unit that allows various operations by the user, and is provided with a plurality of buttons (not shown). The operation panel 13 is provided with a display unit 132. According to the present embodiment, an image of the ejection surface 260 imaged by the imaging device 362 can be displayed on the display unit 132 by operating the operation panel 13. The operation panel 13 may be configured with a touch panel. When the operation panel 13 is configured by a touch panel, the plurality of buttons are buttons displayed on the touch panel. The control unit 50 performs a display process that prompts the display unit 132 to replace the liquid ejection head 26. Details of the display process will be described later.

  The drive signal generation unit 40 generates a drive signal COM. As shown in FIG. 4, the drive signal COM is a voltage signal including an ejection waveform (drive pulse) W for ejecting ink (droplet) at predetermined intervals. By changing the shape of the discharge waveform W, the discharge weight of the ink discharged from the nozzles N can be changed. The specific waveform shape of the discharge waveform W is arbitrary. Further, a configuration including a plurality of ejection waveforms W in one cycle of the drive signal COM or a configuration using a plurality of drive signals COM having different waveforms may be employed. Data (for example, voltage data) for generating the drive signal COM is stored in the data table C. When generating each drive signal COM, the controller 50 reads data corresponding to the waveform of the drive signal COM from the data table C, and the drive signal generator 40 generates the drive signal COM.

  The liquid discharge head 26 includes a drive unit 262 and a liquid discharge unit 264. The drive unit 262 drives the liquid discharge unit 264 under the control of the control unit 20. The liquid ejection unit 264 ejects ink supplied from the liquid container 14 from the plurality of nozzles N to the medium 12. The liquid ejection unit 264 includes a plurality of ejection units 266 corresponding to different nozzles N. Each ejection unit 266 ejects ink according to the drive signal V supplied from the drive unit 262.

  A drive signal COM generated by the drive signal generation unit 40 and a print signal SI instructing whether or not to eject ink according to the print data G are supplied from the control unit 20 to the drive unit 262. The drive unit 262 generates a drive signal V corresponding to the drive signal COM and the print signal SI for each discharge unit 266 and outputs the drive signal V to the plurality of discharge units 266 in parallel. Specifically, the drive unit 262 supplies the ejection waveform W of the drive signal COM as the drive signal V to the ejection unit 266 in which the print signal SI instructs ejection of ink among the plurality of ejection units 266, and the print signal SI. Supplies a drive signal V having a predetermined reference potential VM to the ejection section 266 that instructs non-ejection of ink.

  FIG. 5 is a cross-sectional view of the liquid ejection unit 264 focusing on any one ejection unit 266. In the liquid discharge unit 264 shown in FIG. 5, the pressure chamber substrate 72, the vibration plate 73, the piezoelectric element 74, and the support body 75 are arranged on one side of the flow path substrate 71 and the nozzle plate 76 is arranged on the other side. It is a structure. The flow path substrate 71, the pressure chamber substrate 72, and the nozzle plate 76 are formed of, for example, a silicon flat plate material, and the support body 75 is formed of, for example, an injection molding of a resin material. The plurality of nozzles N are formed on the nozzle plate 76. In the configuration of FIG. 5, the surface of the nozzle plate 76 that faces the medium 12 constitutes the ejection surface 260 of the liquid ejection head 26.

  In the flow path substrate 71, an opening 712, a branch flow path (restricted flow path) 714, and a communication flow path 716 are formed. The branch flow path 714 and the communication flow path 716 are through holes formed for each nozzle N, and the opening 712 is an opening continuous over a plurality of nozzles N. A space in which the accommodating portion (concave portion) 752 formed in the support body 752 and the opening 712 of the flow path substrate 71 communicate with each other is supplied from the liquid container 14 via the introduction flow path 754 of the support body 75. It functions as a common liquid chamber (reservoir) SR for storing ink.

  An opening 722 is formed for each nozzle N in the pressure chamber substrate 72. The vibration plate 73 is an elastically deformable flat plate that is installed on the surface of the pressure chamber substrate 72 opposite to the flow path substrate 71. A space sandwiched between the diaphragm 73 and the flow path substrate 71 inside each opening 722 of the pressure chamber substrate 72 is a pressure chamber filled with ink supplied from the common liquid chamber SR via the branch flow path 714. (Cavity) Functions as SC. Each pressure chamber SC communicates with the nozzle N via the communication channel 716 of the channel substrate 71. A space formed by the pressure chamber SC, the common liquid chamber SR, the branch flow path 714 that communicates with the pressure chamber SC, the communication flow path 716, and the nozzle N forms an internal space SD of the liquid discharge head 26.

  A piezoelectric element 74 is formed for each nozzle N on the surface of the diaphragm 73 opposite to the pressure chamber substrate 72. Each piezoelectric element 74 is a driving element in which a piezoelectric body 744 is interposed between the first electrode 742 and the second electrode 746. A drive signal V is supplied to one of the first electrode 742 and the second electrode 746, and a predetermined reference potential VM is supplied to the other. When the diaphragm 73 is vibrated by the deformation of the piezoelectric element 74 by the supply of the drive signal V, the pressure in the pressure chamber SC varies and the ink in the pressure chamber SC is ejected from the nozzle N. Specifically, ink of an ejection amount corresponding to the amplitude of the drive signal V is ejected from the nozzle N. One discharge portion 266 illustrated in FIG. 5 is a portion including the piezoelectric element 74, the diaphragm 73, the pressure chamber SC, and the nozzle N.

  Note that, of the first electrode 742 and the second electrode 746, the electrode to which the reference potential VM is supplied can be a common electrode across the plurality of piezoelectric elements 74. As described above, in the configuration of FIG. 5, the piezoelectric element 74 is deformed by the supply of the drive signal V and the pressure in the pressure chamber SC is changed, so that the pressure in the internal space SD of the liquid ejection head 26 is changed. Ink can be discharged from.

  In the cleaning of the liquid discharge head 26 in the present embodiment, ink is discharged from the nozzles N and the discharge surface 260 is wiped. Ink is discharged or discharged while the nozzle N is sealed by the capping mechanism 34. Ink suction is a process of discharging thickened ink and bubbles to the cap 342 by sucking the nozzle N with a pump (not shown) communicating with the cap 342, for example. Ink ejection (flushing) is a process of discharging thickened ink and bubbles from the nozzle N to the cap 342 by driving the piezoelectric element 74.

  By discharging such ink, thickened ink and bubbles can be discharged from the nozzle N to the cap 342, and clogging and ejection failure of the nozzle N can be suppressed. The ink discharged to the cap 342 is discarded into a waste liquid tank (not shown) via a waste liquid channel (not shown) communicating with the cap 342.

  Wiping of the ejection surface 260 is a process of wiping the ejection surface 260 with the wiper 322 described above, and is performed to remove stains such as ink adhering to the ejection surface 260. The wiping may be performed after the ink is discharged, or may be performed separately from the ink discharging. When the wiping is performed after the ink is discharged, the wiping is performed in a state where the cap 342 is separated from the ejection surface 260.

  By the way, on the ejection surface 260 of the liquid ejection head 26, there are cases where stains such as scratches and solidified ink that cannot be removed even if the above-described cleaning is performed may occur. For example, if ink adheres to a flaw on the ejection surface 260, the flaw remains even if the ink can be removed by cleaning. Scratches on the ejection surface 260 are dirt that cannot be removed by wiping or the like, and if the ink adhering to the ejection surface 260 is solidified, it is very difficult to remove by wiping or the like.

  FIG. 6 is a plan view showing the ejection surface 260 before and after cleaning. P1 and P2 in FIG. 6 are dirt such as ink that can be removed by cleaning, and Q1 and Q2 are dirt such as scratches that remain without being removed by cleaning and solidified ink. As shown in FIG. 6, the ejection surface 260 before cleaning has dirt P1, P2 and dirt Q1, whereas the ejection surface 260 after cleaning has dirt Q1, Q2. Q1 is dirt that has not been removed by cleaning. Q2 is what is hidden behind the dirt P1 before cleaning, but remains after the dirt P1 is removed by cleaning.

  Thus, if dirt that cannot be removed by cleaning has occurred, the dirt remains even after repeated cleaning. In addition, repeated wiping causes wear of the ejection surface 260 to progress, and repeated exhaust processing for sucking or ejecting ink causes a large amount of ink to be wasted.

  Therefore, in cleaning the liquid ejection head 26 according to the first embodiment, an image before cleaning by the cleaning device 30 and an image after cleaning are captured by the imaging device 362, and a change in the image after cleaning with respect to the captured image before cleaning is captured. The amount is calculated, and a notification process for urging replacement of the liquid ejection head 26 is performed according to the amount of change. In this way, the amount of change in the image of the ejection surface 260 after cleaning with respect to the image of the ejection surface 260 before cleaning imaged by the imaging device 362 is calculated, and the replacement of the liquid ejection head 26 is urged according to the amount of change. Since the notification process is performed, wasteful repetition of cleaning can be suppressed and ink waste due to cleaning can be suppressed. In addition, according to the amount of change, it is possible to determine with high accuracy whether or not dirt that cannot be removed by cleaning, such as scratches on the ejection surface 260 or fixed ink, has occurred, so that the liquid ejection head 26 can be replaced accurately. Can be notified in advance at the timing.

  Note that the amount of change in the image according to the present embodiment is calculated by comparing regions M including the nozzles N as shown in FIG. If dirt Q2 such as scratches that cannot be removed by cleaning or solidified ink remains in the region M including the nozzle N, there is a high possibility of causing a discharge failure of the nozzle N. On the other hand, the dirt Q1 in a region other than the region M including the nozzle N is not likely to cause a discharge failure of the nozzle N. Therefore, in this embodiment, the replacement of the liquid ejection head 26 is notified in accordance with the amount of change in the image calculated by comparing the region M including the nozzle N.

  Hereinafter, an operation method of the liquid ejection apparatus 10 for cleaning the liquid ejection head 26 according to the first embodiment will be described. FIG. 7 is a flowchart of the maintenance process of the liquid ejection head 26 according to the first embodiment. In the maintenance process shown in FIG. 7, the controller 50 acquires an image of the ejection surface 260 before cleaning in step S101. In the present embodiment, for example, an image of a region M including the nozzle N as illustrated in FIG. 6 is acquired as an image of the ejection surface 260. Specifically, the liquid ejection head 26 is moved to the imaging area H <b> 1 by the carriage 24, and an image of the ejection surface 260 is captured by the imaging device 362. The image of the ejection surface 260 captured by the imaging device 362 is acquired by the image acquisition unit 52 and stored in the data table C by the control unit 50.

  Next, in step S <b> 102, the control unit 50 performs cleaning of the liquid ejection head 26. Specifically, the liquid ejection head 26 is moved to the cleaning region H2 by the carriage 24, and cleaning is performed by controlling the wiping mechanism 32 and the capping mechanism 34. As described above, in the cleaning of the liquid discharge head 26 in this embodiment, ink is discharged from the nozzles N and the discharge surface 260 is wiped.

  In cleaning the liquid ejection head 26, the controller 50 first sucks ink from the nozzle N by driving a pump (not shown) with the nozzle N sealed by bringing the cap 342 into contact with the ejection surface 260. To do. As a result, thickened ink and bubbles are discharged from the nozzle N to the cap 342. In addition, the nozzle N can be driven by driving the piezoelectric element 74 in a state where the nozzle N is sealed with the cap 342 or by providing a pump between the liquid container 14 and the liquid discharge head 26 to pressurize the ink. By discharging ink from N onto the cap 342, thickened ink or bubbles may be discharged. Next, the control unit 50 wipes the ejection surface 260 with the wiper 322 to remove stains such as ink adhering to the ejection surface 260.

  Subsequently, in step S103, the control unit 50 acquires an image of the ejection surface 260 after cleaning. In the present embodiment, for example, an image of a region M including the nozzle N as illustrated in FIG. 6 is acquired as an image of the ejection surface 260. Specifically, the liquid ejection head 26 is moved to the imaging area H <b> 1 by the carriage 24, and an image of the ejection surface 260 is captured by the imaging device 362. The image of the ejection surface 260 captured by the imaging device 362 is acquired by the image acquisition unit 52 and stored in the data table C by the control unit 50.

  Next, in step S104, the control unit 50 calculates the amount of change in the image on the ejection surface 260 before and after cleaning. In the present embodiment, the absolute value of the difference between the luminance of the image before cleaning of the ejection surface 260 and the luminance of the image after cleaning of the ejection surface 260 is calculated as the luminance variation. In step S105, the control unit 50 determines whether or not the amount of change is greater than or equal to a threshold value. If the control unit 50 determines in step S105 that the amount of change in luminance is greater than or equal to the threshold value, the maintenance process ends. On the other hand, when the control unit 50 determines that the amount of change in luminance is not greater than or equal to the threshold value (there is a portion below the threshold value) in step S105, a notification process that prompts replacement of the liquid ejection head 26 is performed in step S106. End the maintenance process.

  8A and 8B are diagrams showing images of the ejection surface 260 before and after cleaning, and the luminance in the region M and the amount of change in luminance in the nozzle row direction. N1 to N4 indicate nozzles having nozzle numbers 1 to 4, respectively. FIG. 8A shows a case where the dirt P on the ejection surface 260 is removed by cleaning. FIG. 8B shows a case where dirt Q that could not be removed by cleaning remains on the ejection surface 260. As shown after cleaning in FIG. 8A, in the image of the ejection surface 260, when the portion other than the nozzle N is not contaminated, the brightness of the image on the ejection surface 260 decreases at the nozzles N1 to N4, and the nozzle N1. It becomes high in parts other than ~ N4. In the region M where the portion other than the nozzle N is not contaminated, when the change in the luminance of the image on the ejection surface 260 along the nozzle row is shown, the luminance of the region including the nozzles N1 to N4 is The luminance of the region of the nozzle N and the luminance of the discharge surface 260 around the nozzle N is added to the luminance L1, and the luminance of the region not including the nozzles N1 to N4 is equal to the luminance L2 of the discharge surface 260 in the portion. Become. Since the inside of the nozzle N is filled with ink and has a lower luminance than the ejection surface 260 on which no dirt is attached, the luminance L1 is lower than the luminance L2.

  If there is dirt P adhered to the ejection surface 260 by overlapping ink, etc., before cleaning in FIG. 8A, the brightness of the area including the nozzles N1 to N4 among the dirt P of brightness A before cleaning is as follows. The luminance L4 is obtained by adding the luminance of the area of the nozzle N in this portion and the luminance of the ejection surface 260 to which the dirt P around the nozzle N adheres, and the luminance L4 is lower than the luminance L1. In addition, in the portion of the stain P with the brightness A before cleaning, the brightness of the portion of the area not including the nozzles N1 to N4 is a brightness L3 lower than the brightness L2 of the ejection surface 260 where the stain is not attached. When the dirt P is removed by the cleaning, the brightness of the area including the nozzles N1 to N4 in the area from which the dirt P is removed is changed from the brightness L4 to the brightness L1, as in the brightness B after cleaning in FIG. 8A. The brightness of the area that does not include the nozzles N1 to N4 changes greatly from the brightness L3 to the brightness L2. Therefore, in this case, the luminance change amount L (= | luminance B−luminance A |), which is the absolute value of the difference obtained by subtracting the luminance A before cleaning from the luminance B after cleaning, is | L2− L3 | and | L1-L4 |, which are equal to or greater than the threshold value, the control unit 50 ends the maintenance process. Here, the threshold value is a criterion for determining whether or not the dirt on the ejection surface 260 has been improved by cleaning so as not to adversely affect ejection. For example, the amount of change in the brightness of the image on the ejection surface 260 from which the ink has been removed by cleaning to the extent that the ejection surface 260 does not adversely affect the ejection with respect to the brightness of the image on the ejection surface 260 to which the solidified ink is attached so as to adversely affect the ejection Can be confirmed in advance by experiments or the like, a threshold value can be determined based on the confirmation result, and the threshold value can be stored in the data table C in advance.

  On the other hand, when there is dirt Q that cannot be removed by cleaning as after cleaning in FIG. 8B, the brightness of the dirt Q portion including the nozzles N1 to N4 is lower than L1, and the brightness L4 of the dirt P before cleaning. The luminance of the portion not including the nozzles N1 to N4 is lower than L2, and becomes the luminance L3 ′ higher than the luminance L3 of the dirt P before cleaning. Here, as the dirt remaining after cleaning, solidification of a part of the area of dirt P before cleaning has progressed and cannot be completely removed by cleaning, and the area having luminance L3 becomes narrower after cleaning than before cleaning. There is a case. In some cases, the luminance of the same region is improved from the luminance L3 to the luminance L3 ′. For example, FIG. 8B illustrates a case where the dirt range is narrowed from the dirt P range to the dirt Q range due to cleaning, and the luminance of the remaining dirt portion is improved from the luminance L3 to the luminance L3 ′. In FIG. 8B, the change amount between the luminance A and the luminance B (= | luminance B−luminance A |) is determined by the control unit 50 that the dirt Q portion is not equal to or greater than the threshold (there is a portion below the threshold). This is a case in which the notification process for prompting the replacement of 26 is performed and the maintenance process is terminated.

  Therefore, as shown in FIG. 8B, even if the ink stain P before cleaning is removed by cleaning, if the solidified stain Q remains after cleaning, the amount of change in luminance before and after cleaning. L (= | luminance B−luminance A |) is equal to or greater than the threshold value because the portion where the dirt P is removed and the ejection surface 260 is exposed is | L2−L3 |. On the other hand, the amount of change in luminance before and after the cleaning of the dirt Q portion is | L3′−L3 |, and is not equal to or greater than the threshold value. Thus, when there is a portion where the luminance change amount L is below the threshold value, there is a high possibility that the dirt Q that cannot be removed by cleaning has occurred. Therefore, in this case, the control unit 50 ends the maintenance process after performing a notification process that prompts replacement of the liquid ejection head 26.

  As described above, according to the first embodiment, wasteful repetition of cleaning can be suppressed, and wasted ink due to cleaning can be suppressed. In addition, the amount of change in the image (in this case, the amount of change in brightness) can determine with high accuracy whether or not dirt that cannot be removed by cleaning, such as ink adhered to the ejection surface 260, can be determined with high accuracy. Can be notified in advance at an appropriate timing. In addition, it is possible to easily determine whether to end the maintenance process by performing a notification process for prompting the replacement of the liquid ejection head 26 simply by comparing the amount of change in the image with a predetermined threshold value.

  As the notification process, for example, a display for prompting replacement of the liquid ejection head 26 is performed on the display unit 132. For example, a message such as “I found a flaw on the discharge surface of the liquid discharge head or solidification of the ink. If this happens, an ink discharge failure may occur. Replace the liquid discharge head.” . In this case, the user may be made to select and display “perform the ejection surface determination again”, “confirm the ejection surface”, “print as it is”, or the like. When the user selects “confirm ejection surface”, the image of the ejection surface 260 after cleaning is displayed on the display unit 132. Note that the images of the ejection surface 260 before and after cleaning as shown in FIG. 6 may be displayed on the display unit 132 to allow the user to determine whether or not to replace the liquid ejection head 26. . Further, the cleaning may be repeated according to the user's selection.

  Further, in this embodiment, since an image of the ejection surface 260 before cleaning is captured in step S101 in FIG. 7, it is determined whether or not the cleaning in step S102 is executed from the image of the ejection surface 260 before cleaning. May be. Specifically, there is no dirt if there is no part below brightness L2 ′ (not shown) when there is no dirt in the part other than the nozzle N from the image of the ejection surface 260 before cleaning taken in step S101. The maintenance process is terminated, and if there is a portion with luminance L2 ′ or less, it may be determined that there is dirt and the cleaning in step S102 may be executed. The luminance L2 ′ in this case is determined based on the result of measuring the luminance value of the region other than the nozzles of the image on the ejection surface 260 on which the dirt is not adhered in advance through experiments or the like, and is stored in the data table C. According to this, since unnecessary cleaning is not performed when the ejection surface 260 before cleaning is clean, it is possible to suppress ink consumption and wear of the ejection surface 260 due to cleaning.

Second Embodiment
A second embodiment of the present invention will be described. In the following exemplary embodiments, elements having the same functions and functions as those of the first embodiment are diverted using the same reference numerals used in the description of the first embodiment, and detailed descriptions thereof are appropriately omitted. In the first embodiment, the image determination is performed based on the images of the ejection surface 260 before and after cleaning. However, in the second embodiment, before the liquid ejection head 26 is used (hereinafter referred to as “before head use”). ) And the image of the ejection surface 260 after cleaning are exemplified. “Before use of the head” refers to a state in which the liquid ejection device 10 is in a substantially unused state and is initially activated, or at the first activation after the liquid ejection head 26 is replaced. There are no scratches or dirt before using the head, so if there is any dirt that cannot be removed after cleaning, the image before using the head will be different from the image after cleaning. To determine the image.

  FIG. 9 is a flowchart showing a maintenance process of the liquid ejection head 26 according to the second embodiment. In the maintenance process shown in FIG. 9, the control unit 50 acquires an image of the ejection surface 260 before using the head from the data table C in step S201. In the present embodiment, for example, at the first activation of the liquid ejection device 10 or at the first activation after the replacement of the liquid ejection head 26, the liquid ejection head 26 is moved to the imaging area H1 by the carriage 24, and the imaging device 362 is moved. Thus, an image of the ejection surface 260 before use of the head is taken. The image of the ejection surface 260 before use of the head imaged by the imaging device 362 is acquired by the image acquisition unit 52 and stored in advance in the data table C by the control unit 50.

  Next, the control unit 50 performs cleaning of the liquid discharge head 26 in step S202, and acquires an image of the cleaned discharge surface 260 in step S203. Note that the processing in the next step S202 and step S203 is the same as the processing in step S102 and step S103 in FIG.

  Next, in step S204, the amount of change in the image on the ejection surface 260 before use of the head and after cleaning is calculated. Here, as in the first embodiment, the amount of change in luminance is calculated. Specifically, in this embodiment, as the amount of change in the image, the absolute value of the difference between the luminance of the image on the ejection surface 260 before using the head and the luminance of the image after the cleaning of the ejection surface 260 is used as the amount of change in luminance. Calculate as In step S205, the control unit 50 determines whether or not the amount of change is equal to or greater than a threshold value. If the control unit 50 determines in step S205 that the amount of change in luminance is not greater than or equal to the threshold (less than the threshold), the maintenance process ends. On the other hand, if the control unit 50 determines that the amount of change in luminance is equal to or greater than the threshold value in step S205, a notification process for prompting replacement of the liquid ejection head 26 is performed in step S206, and the maintenance process is terminated.

  10A and 10B are diagrams showing an image of the ejection surface 260 before use of the head and after cleaning, and the amount of change in luminance and luminance. FIG. 10A shows a case where the dirt P before cleaning similar to FIG. 8A is removed by cleaning. FIG. 10B shows a case where dirt / scratches Q that could not be removed by cleaning remain on the ejection surface 260. Before the head shown in FIG. 10A is used, the portion other than the nozzle N in the image on the ejection surface 260 is not soiled or scratched. Therefore, the luminance C2 of the image on the ejection surface 260 is the luminance L2 of the portion other than the nozzles N1 to N4. It becomes higher than the luminance L1 of the portion of ~ N4.

  After the cleaning in FIG. 10A, the dirt P is removed by the cleaning, and the dirt disappears. Accordingly, the luminance change amount L (= | luminance B−luminance C |) in this case is almost zero. Therefore, in the second embodiment, it is determined whether or not there are any scratches or dirt remaining on the ejection surface 260 after cleaning, which have an adverse effect on the ejection, with respect to a state where there is no scratch or dirt on the ejection surface 260 before use of the head. For example, the amount of change in the brightness of the image on the ejection surface 260 where the scratches or stains that have an adverse effect on the ejection after cleaning with respect to the brightness of the image on the ejection surface 260 before using the head is confirmed in advance through experiments or the like. Based on the threshold value, the threshold value can be stored in the data table C in advance. Therefore, if the dirt P is removed by the cleaning and the change amount L of the brightness B and the brightness C is not equal to or greater than the threshold value, it is determined that the dirt has been removed by the cleaning without any flaws that adversely affect the ejection, and the maintenance process can be terminated. I have to. That is, since the luminance change amount L in FIG. 10A is zero and not more than the threshold value, the control unit 50 ends the maintenance process.

  On the other hand, after the cleaning in FIG. 10B, the dirt Q that cannot be removed by the cleaning remains. The portion of the area including the nozzles N1 to N4 in the portion where the dirt B of the brightness B after cleaning remains is the same as the discharge surface 260 where the brightness of the area of the nozzle N in the portion and the dirt Q around the nozzle N remain. The luminance L4 ′ is obtained by adding the luminances of the luminances L4 ′ and the luminance L4 ′ is lower than the luminance L1. In addition, the portion of the region where the dirt Q remains without including the nozzles N1 to N4 has a brightness L3 'lower than the brightness L2 of the ejection surface 260 where the dirt Q does not remain. In this case, the luminance change amount L (= | luminance B−luminance C |), which is the absolute value of the difference obtained by subtracting the luminance B after cleaning from the luminance C before using the head, is | L2−L3 at the portion of the dirt Q. '| And | L1-L4' |, which are equal to or greater than the threshold value.

  As another example, when a scratch that cannot be removed by cleaning occurs, the protective film on the surface of the ejection surface 260 is shaved and the underlying metal is exposed. For this reason, the brightness L3 ″ (not shown) of the scratched portion of the image on the ejection surface 260 after cleaning can be higher than the brightness L2 of the portion that is not contaminated before using the head and does not include the nozzle N. . Also in such a case, the luminance change amount L (= | luminance B−luminance C |), which is the absolute value of the difference obtained by subtracting the luminance B after cleaning from the luminance C before use of the head, is | L2 −L3 ″ |, which is equal to or greater than the threshold value. Therefore, if the luminance change amount L is equal to or greater than the threshold value, the control unit 50 determines that there is a scratch that has an adverse effect on ejection or dirt that cannot be sufficiently removed by cleaning, and prompts replacement of the liquid ejection head 26. After performing the processing, the maintenance processing is terminated.

  As described above, according to the second embodiment, as in the first embodiment, unnecessary repetition of cleaning can be suppressed, and wasted ink due to cleaning can be suppressed. In addition, in the second embodiment, it is highly accurate whether or not stains that cannot be removed by cleaning, such as scratches on the ejection surface 260 and fixed ink, are generated due to the amount of change in the image (here, the amount of change in luminance). Therefore, the replacement of the liquid ejection head 26 can be notified in advance at an appropriate timing before the cleaning is repeated unnecessarily. Particularly, in the second embodiment, since the image is compared with the image of the ejection surface 260 before using the head without any scratches or fixed ink, it is easy to find the scratches or fixed ink remaining on the ejection surface 260 after cleaning. In addition, it is possible to easily determine whether to end the maintenance process by performing a notification process for prompting the replacement of the liquid ejection head 26 simply by comparing the amount of change in the image with a predetermined threshold value.

<Third Embodiment>
A third embodiment of the present invention will be described. The third embodiment exemplifies a case where image determination is performed by comparing images on the ejection surface 260 before use of the head and before cleaning, and comparing images on the ejection surface 260 before use of the head and after cleaning. To do.

  FIG. 11 is a flowchart showing a maintenance process of the liquid ejection head 26 according to the third embodiment. FIG. 12 is a diagram illustrating the image and brightness of the ejection surface 260 before use of the head and before and after cleaning, and the amount of change in brightness. The upper part of FIG. 12 is an example of the first difference value La of the luminance that is the absolute value of the difference calculated by subtracting the luminance A before cleaning from the luminance C before using the head. The lower part of FIG. 12 shows an example of the second difference value Lb of the luminance, which is the absolute value of the difference calculated by subtracting the luminance B after cleaning from the luminance C before using the head. Also in FIG. 12, similarly to FIG. 8A of the first embodiment, the dirt P adheres to the ejection surface 260 before cleaning, and the lower stage shows the dirt Q that could not be removed by cleaning, as in FIG. 8B. Is a case where the ink remains on the ejection surface 260 after cleaning.

  In the maintenance process shown in FIG. 11, the controller 50 acquires images of the ejection surface 260 before using the head and before cleaning in step S301. Also in the present embodiment, as in the second embodiment, the image of the ejection surface 260 before use of the head is captured by the imaging device 362, for example, when the liquid ejection device 10 is first activated or when the liquid ejection head 26 is replaced. And stored in the data table C in advance. Therefore, in step S301, the image of the ejection surface 260 before use of the head is acquired from the data table C, and the image of the ejection surface 260 before cleaning is captured by the imaging device 362 and acquired.

  Next, in step S302, the control unit 50 calculates a first difference value La that is the amount of change in the image of the ejection surface 260 before using the head and before cleaning, and in step S303, the first difference value La is set to the first threshold value. It is determined whether it is above. Here, the amount of change in the image of the ejection surface 260 before using the head and before cleaning is the absolute value of the difference between the brightness of the image on the ejection surface 260 before using the head and the brightness of the image on the ejection surface 260 before cleaning. This is the amount of change in the brightness of the image. The first threshold value is a criterion for determining whether there is a scratch or dirt that adversely affects ejection on the ejection surface 260 before cleaning with respect to a state where there is no scratch or dirt on the ejection surface 260 before using the head. . For example, the amount of change in the brightness of the image on the ejection surface having scratches or dirt that has an adverse effect on ejection relative to the brightness of the image on the ejection surface 260 to which scratches and dirt are not adhered before use of the head is tested in advance. The first threshold value can be determined based on the confirmation result and stored in the data table C.

  In step S303, the control unit 50 determines that the first difference value La, which is the amount of change in the brightness of the image on the ejection surface 260 before cleaning with respect to the brightness of the image on the ejection surface 260 before using the head, is not greater than or equal to the first threshold value. When the determination is made, the maintenance process is terminated, assuming that there is no scratch or dirt on the discharge surface 260 before the use of the head that has an adverse effect on the discharge on the discharge surface 260 before the cleaning.

  On the other hand, in step S303, control is performed such that the first difference value La, which is the amount of change in the brightness of the image on the ejection surface 260 before cleaning with respect to the brightness of the image on the ejection surface 260 before using the head, is greater than or equal to the first threshold value. If the determination is made by the unit 50, the control unit 50 performs cleaning of the discharge surface 260 in step S304, assuming that there are scratches or dirt that adversely affect the discharge. In other words, in step S303, the control unit 50 determines whether or not the ejection surface 260 is to be cleaned. According to this, when the ejection surface 260 before cleaning is not contaminated to the extent that affects ejection, unnecessary cleaning is not executed, so that consumption of ink and cleaning of the ejection surface 260 due to cleaning can be suppressed.

  Next, the control unit 50 acquires an image of the ejection surface 260 after cleaning in step S305. Note that the processing in step S304 and step S305 is the same as the processing in step S102 and step S103 in FIG.

  Subsequently, in step S306, a second difference value Lb, which is a change amount of the image on the ejection surface 260 before use of the head and after cleaning, is calculated. The second difference value Lb here is the amount of change in luminance of the image, and is the same as the amount of change in luminance in the second embodiment. Specifically, the absolute value of the difference between the luminance of the image on the ejection surface 260 before using the head and the luminance of the image after cleaning the ejection surface 260 is calculated as the second difference value Lb. Subsequently, in step S307, the control unit 50 determines whether or not the second difference value Lb is greater than or equal to the first threshold value. Similarly to the case shown in FIG. 10A of the second embodiment, if the dirt is removed by the cleaning, and there is no scratch or dirt that adversely affects the ejection on the ejection surface 260 after the cleaning, the second difference Since the value Lb is not equal to or greater than the first threshold value, the maintenance process ends in that case.

  As illustrated in the lower part of FIG. 12, when the control unit 50 determines that the second difference value Lb is equal to or greater than the first threshold value in step S307, the control unit 50 determines the first difference value La in step S308. A third difference value L that is an absolute value of the difference between the second difference values Lb (amount of change between the first difference value La and the second difference value Lb) is calculated. In step S309, the control unit 50 determines whether or not the third difference value L is greater than or equal to the second threshold value. Here, the second threshold is a criterion for determining whether or not a predetermined amount of dirt has been removed by cleaning. For example, although a dirt remains after cleaning, a predetermined amount of dirt can be removed by cleaning and remains. This is also a standard for determining that there is a possibility that dirt will be removed by future cleaning. For example, the amount of change in the brightness of the image on the ejection surface 260 that can be removed to some extent by cleaning although the stain remains after cleaning with respect to the brightness of the image on the ejection surface 260 to which the ink solidified before cleaning has adhered is tested in advance. The second threshold value can be determined based on the confirmation result, and the second threshold value can be stored in the data table C.

  As shown in the upper part of FIG. 12, the first difference value La is an amount of change due to scratches or dirt adhering from before using the head to before cleaning, and as shown in the lower part of FIG. 12, the second difference value Lb is The amount of change due to scratches or dirt remaining after cleaning. Therefore, in step 309, as shown in the rightmost column of FIG. 12, the absolute value of the difference between the first difference value La and the second difference value Lb, that is, the amount of change in the image due to the removal of dirt by cleaning. When the control unit 50 determines that a certain third difference value L is equal to or greater than the second threshold value, it is assumed that dirt has been removed to some extent by cleaning, and the maintenance process is terminated.

  On the other hand, when the control unit 50 determines in step S309 that the third difference value L is not equal to or greater than the second threshold value (below the second threshold value), the cleaning surface cannot sufficiently remove scratches or dirt on the ejection surface 260. In step S310, a notification process for prompting replacement of the liquid ejection head 26 is performed, and the maintenance process is terminated.

  Hereinafter, the maintenance process of the present embodiment will be described more specifically using the example of FIG. Since the image on the ejection surface 260 before cleaning in the upper part of FIG. 12 has dirt P, the first difference value La (= | luminance A−luminance C |) is | L3−L2 | , Greater than or equal to the first threshold. Since the image of the ejection surface 260 after the lower stage of FIG. 12 has dirt Q, the second difference value Lb (= | luminance B−luminance C |) is | L3′−L2 | And is less than the first threshold. As described above, when the second difference value Lb does not exceed the first threshold value, the control unit 50 calculates the third difference value L that is an absolute value of the difference between the first difference value La and the second difference value Lb. .

  As shown in the rightmost column of FIG. 12, the third difference value L (| = L2−L1 |), which is the amount of change between the first difference value La and the second difference value Lb, is the portion where the dirt P has been removed by cleaning. Whereas it is equal to or higher than the second threshold, the portion where the dirt Q remains is lower than the second threshold. Therefore, in this case, since there is a portion below the second threshold value, the control unit 50 determines that the third difference value L is not equal to or greater than the second threshold value, and performs a notification process that prompts replacement of the liquid ejection head 26. The maintenance process ends.

  As described above, according to the third embodiment, as in the first embodiment and the second embodiment, unnecessary repetition of cleaning can be suppressed, and waste of ink due to cleaning and wear of the ejection surface 260 can be suppressed. In addition, in the third embodiment, depending on the amount of change in the image (in this case, the amount of change in luminance), whether or not cleaning is necessary before cleaning, scratches on the ejection surface 260 and fixed ink, etc. after cleaning are removed by cleaning. It is possible to determine with high accuracy whether or not kisses or dirt that adversely affect the discharge that cannot be completely generated have occurred, and whether or not dirt has been sufficiently removed by cleaning. Therefore, the replacement of the liquid discharge head 26 can be notified in advance before repeating cleaning unnecessary at a more accurate timing. In particular, in the third embodiment, as in the second embodiment, comparison is made with the image of the ejection surface 260 before use and after cleaning, which does not have any scratches or fixed ink, so It is easy to find stuck ink. Whether or not the maintenance process is ended after performing a notification process for prompting the replacement of the liquid ejection head 26 simply by comparing the amount of change of the image with a predetermined threshold (here, the first threshold and the second threshold). Can be determined.

  In the third embodiment, in step S307 in FIG. 11, if it is determined whether or not dirt is removed by cleaning, and it is possible to determine whether or not scratches or dirt that adversely affect ejection remain on the ejection surface 260 after cleaning. A first 'threshold value (not shown) different from the 1 threshold value can also be used.

  In step S309, if the control unit 50 determines that the third difference value L is equal to or greater than the second threshold value, the current ejection surface 260 has scratches or dirt greater than or equal to the first threshold value. It is also possible to determine that the situation is improved more than the second threshold and perform the maintenance process again from step 301. Further, step S307 is a procedure for calculating the amount of change in the luminance of the image on the ejection surface 260 before and after cleaning, as in steps S204 and S205 of the second embodiment, and determining whether the amount of change is equal to or greater than a second threshold. Even if it is replaced, the same determination can be made. However, it is possible to reduce the processing procedure if the determination is made in step S307 using the already calculated first difference value La and second difference value Lb.

<Modification>
The aspects and embodiments exemplified above can be variously modified. Specific modifications are exemplified below. Two or more aspects arbitrarily selected from the following exemplifications and the above-described aspects can be appropriately combined as long as they do not contradict each other.

(1) In the above-described embodiment, the case where the change amount of the luminance is calculated as the change amount of the image is illustrated, but the present invention is not limited to this. For example, the change amount of the color difference may be calculated as the change amount of the image on the ejection surface 260. For example, the color difference value of the image on the ejection surface 260 before cleaning or before the use of the head, and the ejection surface 260 after cleaning, depending on whether the ink stains on the ejection surface 260 remain after cleaning or not. This is different from the color difference value of the image. Therefore, image determination similar to that in the above-described embodiment can be performed also by the amount of change that is the absolute value of the difference between the color difference values. Alternatively, the stain area may be measured from the image on the ejection surface 260, and the change amount of the stain area may be calculated as the change amount of the image. Since the dirt area on the ejection surface 260 before cleaning or before use of the head and the dirt area on the ejection surface 260 after cleaning may change, the image similar to that in the above-described embodiment also depends on the amount of change in the dirt area. Judgment is possible.

(2) In the above-described embodiment, the case where the image determination of the ejection surface 260 is performed every time the maintenance process is performed is illustrated, but the present invention is not limited to this. For example, the image determination of the ejection surface 260 is performed in the maintenance process performed when the liquid ejection apparatus 10 is started or the maintenance process performed at the timing instructed by the user, and the image determination of the ejection surface 260 is performed in the maintenance process at other timings. It is also possible to perform only cleaning without performing the above. Further, in the setting of the maintenance process, when the user selects the image determination of the discharge surface 260, the image determination of the discharge surface 260 may be performed by the maintenance process. Further, the image determination of the discharge surface 260 may be performed for each range including one or a plurality of nozzles N. When a plurality of nozzle rows are arranged on the discharge surface 260, the image determination of the discharge surface 260 is performed. You may make it carry out for every range in which one or a plurality of nozzle rows are included.

(3) In the above-described embodiment, whether the image change amount is equal to or greater than the threshold value in the comparison between the image change amount by the control unit 50 and the threshold value, the first threshold value, the second threshold value (hereinafter simply referred to as the threshold value). Alternatively, it is determined whether the amount of change in the image is not greater than or equal to the threshold (less than the threshold), but is not limited thereto. For example, depending on the setting of the image change amount, it can be determined whether the image change amount exceeds the threshold value or whether the image change amount is equal to or less than the threshold value.

(4) In the above-described embodiment, the case where the display process is performed on the display unit 132 to urge the replacement of the liquid discharge head 26 is exemplified as the notification process. Exchange may be prompted.

(5) In the above-described embodiment, the serial head in which the carriage 24 on which the liquid discharge head 26 is mounted is reciprocated repeatedly along the X direction is exemplified. However, the line head in which the liquid discharge heads 26 are arranged over the entire width of the medium 12. The present invention can also be applied to.

(6) In the above-described embodiment, the piezoelectric liquid discharge head 26 using the piezoelectric element that imparts mechanical vibration to the pressure chamber is exemplified. However, a heating element that generates bubbles in the pressure chamber by heating is used. It is also possible to employ a heat-type liquid discharge head that is used.

(7) The liquid ejection apparatus 10 exemplified in the above-described embodiment can be employed in various apparatuses such as a facsimile apparatus and a copying machine in addition to an apparatus dedicated to printing. However, the use of the liquid ejection apparatus 10 of the present invention is not limited to printing. For example, a liquid ejection device that ejects a color material solution is used as a manufacturing device for forming a color filter of a liquid crystal display device, an organic EL (Electro Luminescence) display, an FED (surface emitting display), or the like. In addition, a liquid discharge apparatus that discharges a solution of a conductive material is used as a manufacturing apparatus that forms wiring and electrodes of a wiring board. Further, it is also used as a chip manufacturing apparatus that discharges a bioorganic solution as a kind of liquid.

DESCRIPTION OF SYMBOLS 10 ... Liquid discharge apparatus, 12 ... Medium, 13 ... Operation panel, 132 ... Display part, 14 ... Liquid container, 20 ... Control unit, 202 ... Control apparatus, 203 ... Memory | storage device, 22 ... Conveyance mechanism, 24 ... Carriage, 26 DESCRIPTION OF SYMBOLS ... Liquid discharge head, 260 ... Discharge surface, 262 ... Drive part, 264 ... Liquid discharge part, 266 ... Discharge part, 30 ... Cleaning device, 302 ... Opening part, 32 ... Wiping mechanism, 322 ... Wiper, 34 ... Capping mechanism, 342 ... Cap, 36 ... Imaging mechanism, 362 ... Imaging device, 364 ... Shutter, 40 ... Drive signal generation unit, 50 ... Control unit, 52 ... Image acquisition unit, 71 ... Flow path substrate, 712 ... Opening portion, 714 ... Branch Flow path, 716 ... Communication flow path, 72 ... Pressure chamber substrate, 722 ... Opening, 73 ... Diaphragm, 74 ... Piezoelectric element, 742 ... First electrode, 744 ... Piezoelectric body, 746 ... 2 electrodes, 75 ... support, 754 ... introducing flow path, 76 ... nozzle plate, C ... data table, COM ... drive signal, G ... printing data, H ... non-printing area, H1 ... imaging area, H2 ... cleaning area, L: change in luminance, L1, L2, L3, L3 '... luminance, M ... area, N ... nozzle, N1-N4 ... nozzle, P, P1, P2 ... dirt, Q, Q1, Q2 ... dirt, SC ... Pressure chamber, SD ... Internal space, SI ... Print signal, SR ... Common liquid chamber, V ... Drive signal, VM ... Reference potential, W ... Discharge waveform.

Claims (12)

A liquid ejection head having an ejection surface on which nozzles for ejecting liquid are formed;
A cleaning device for cleaning the ejection surface;
An imaging device that captures an image of the ejection surface;
An image before cleaning by the cleaning device and an image after cleaning are picked up by the image pickup device, and a notification process for prompting replacement of the liquid ejection head is performed in accordance with a change amount of the image after cleaning with respect to the image before cleaning. A liquid ejection apparatus comprising: a control unit; The liquid ejection apparatus according to claim 1, wherein the control unit performs a notification process that prompts replacement of the liquid ejection head when the amount of change is not equal to or greater than a predetermined threshold. A liquid ejection head having an ejection surface on which nozzles for ejecting liquid are formed;
A cleaning device for cleaning the ejection surface;
An imaging device that captures an image of the ejection surface;
An image before use of the liquid discharge head and an image after cleaning by the cleaning device are picked up by the image pickup device, and the replacement of the liquid discharge head is urged according to the amount of change of the image after cleaning with respect to the image before use. And a control unit that performs a notification process. The liquid ejecting apparatus according to claim 3, wherein when the amount of change is equal to or greater than a predetermined threshold, the control unit performs a notification process that prompts replacement of the liquid ejecting head. A liquid ejection head having an ejection surface on which nozzles for ejecting liquid are formed;
A cleaning device for cleaning the ejection surface;
An imaging device that captures an image of the ejection surface;
An image before the cleaning of the liquid discharge head, an image before the cleaning by the cleaning device, and an image after the cleaning are picked up by the image pickup device, and is a first change amount of the image before the cleaning with respect to the image before the use. Control that performs notification processing for prompting replacement of the liquid ejection head according to a third difference value that is a change amount between the difference value and a second difference value that is a change amount of the image after cleaning with respect to the image before use. A liquid ejecting apparatus. The liquid ejecting apparatus according to claim 5, wherein the control unit performs a notification process that prompts replacement of the liquid ejecting head when the third difference value is not equal to or greater than a predetermined threshold value. The liquid ejection apparatus according to claim 1, wherein the image for calculating the amount of change is an image of an area including the nozzle on the ejection surface. The change amount of the image is at least one of a change amount of luminance of the image of the discharge surface, a change amount of color difference of the image of the discharge surface, and a change amount of the area of the liquid attached to the discharge surface. The liquid ejection device according to claim 1. An operation method of a liquid discharge apparatus including a liquid discharge head having a discharge surface on which a nozzle for discharging liquid is formed,
Taking an image of the ejection surface before cleaning,
Cleaning the ejection surface;
Taking an image after cleaning the ejection surface,
Calculating the amount of change in the image after cleaning relative to the image before cleaning;
An operation method of a liquid ejection apparatus that performs a notification process that prompts replacement of the liquid ejection head according to the amount of change. An operation method of a liquid discharge apparatus including a liquid discharge head having a discharge surface on which a nozzle for discharging liquid is formed,
Taking an image before use of the ejection surface of the liquid ejection head,
Cleaning the ejection surface;
Taking an image after cleaning the ejection surface,
Calculating the amount of change in the image after cleaning with respect to the image before use;
An operation method of a liquid ejection apparatus that performs a notification process that prompts replacement of the liquid ejection head according to the amount of change. An operation method of a liquid discharge apparatus including a liquid discharge head having a discharge surface on which a nozzle for discharging liquid is formed,
Taking an image before use of the ejection surface of the liquid ejection head,
Taking an image of the ejection surface before cleaning,
Cleaning the ejection surface;
Taking an image after cleaning the ejection surface,
Calculating a first difference value that is a change amount of the image before cleaning with respect to the image before use;
Calculating a second difference value that is a change amount of the image after cleaning with respect to the image before use;
Calculating a third difference value that is a change amount of the second difference value with respect to the first difference value;
An operation method of a liquid ejection apparatus that performs a notification process that prompts replacement of the liquid ejection head according to the third partial value. Calculating the first difference value before cleaning the ejection surface;
The method of operating a liquid ejection apparatus according to claim 11, wherein it is determined whether or not to perform cleaning of the ejection surface according to the first difference value.

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