JP2009061722A - Inspecting method for ink jet head, ink jet recording device, and inspecting member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily obtain the discharged state of an ink drop relating to each of nozzles. <P>SOLUTION: A plurality of permeation areas 35 and a non-permeation area 36 defining the permeation areas 35 are formed on an inspection panel 30. The inspection panel 30 is disposed so that each of the nozzles of an ink jet head and each permeation area 35 are disposed opposite to each other (disposing step). In this condition, ink drops are discharged from all the nozzles 108 of the ink jet head (discharging step). The inspection panel 30 is disposed between a photo-detector array and an LED illuminator. The photo-detector array detects the ink coverage of each permeation area 35 (permeating state detection step). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inspection method for an inkjet head that ejects ink droplets, an inkjet recording apparatus, and an inspection member.

  In an inkjet head in which a plurality of nozzles that eject ink droplets to a recording medium such as recording paper is formed, impurities such as paper dust enter the nozzle or the ink in the nozzle thickens, The nozzle may be clogged and ink droplet ejection failure may occur. In this case, since the landing position of the ink droplet changes or the ink droplet is no longer ejected, the print quality is deteriorated. Therefore, there is a technology for detecting an ejection failure of an ink droplet related to a nozzle by ejecting ink droplets so that a test pattern is formed on a transparent film and reading the test pattern using a CCD (Charge Coupled Device). It is disclosed (see Patent Document 1).

JP 2006-069027 A (FIG. 17)

  According to the technique described above, in order to detect the ejection state of the ink droplets related to each nozzle, the presence or absence or position of each ink dot formed on the transparent film is grasped. Since the volume of the ejected ink droplet is about several pl and the size of the ink dot formed on the transparent film is minute, it is difficult to accurately detect the ejection state of the ink droplet related to the nozzle.

  SUMMARY An advantage of some aspects of the invention is that it provides an ink jet head inspection method, an ink jet recording apparatus, and an inspection member capable of easily grasping an ejection state of ink droplets related to a nozzle.

  The ink jet head inspection method of the present invention is an ink jet head inspection method in which a plurality of nozzles for ejecting ink droplets are formed on a recording medium, and a plurality of ink droplets ejected from different nozzles are landed. An arrangement step in which an inspection member in which a non-transmission region that defines the region and the plurality of transmission regions is formed is arranged so that the transmission region and the nozzle corresponding to the transmission region face each other; and the arrangement step And a discharge step of discharging ink droplets from the plurality of nozzles.

  The ink jet recording apparatus of the present invention includes a transport mechanism for transporting a recording medium, an ink jet head in which a plurality of nozzles for ejecting ink droplets are formed on the recording medium transported by the transport mechanism, and ejection from different nozzles. A plurality of transmission regions on which the ink droplets landed, an inspection member formed with a non-transmission region defining the plurality of transmission regions, the transmission region and the nozzle corresponding to the transmission region by the transport mechanism; The inspection member transported to a position opposite to each other includes a transmission state detection unit that detects a transmission state of each transmission region of the inspection member after ejecting ink droplets from the plurality of nozzles.

  The inspection member of the present invention is an inspection member for inspecting the ejection state of ink droplets at the nozzles related to an inkjet head in which a plurality of nozzles for ejecting ink droplets is formed, and the ejection members are ejected from different nozzles. A plurality of transmission areas where ink droplets land and a non-transmission area that defines the plurality of transmission areas are formed.

  According to these aspects of the present invention, when the ink droplet lands on the center of the transmissive region, the region exposed from the ink in the transmissive region is almost eliminated, so that the ink coverage of the transmissive region is the highest. In addition, when ink droplets do not land on the transmissive area, the entire transmissive area is exposed from the ink, so that the ink coverage of the transmissive area is the lowest. Furthermore, when the ink droplets land at a position away from the center of the transmissive area in one direction, the area exposed from the ink in the transmissive area is unevenly distributed in the other direction, so the ink coverage of the transmissive area depends on the uneven distribution amount. Changes. Thus, the transmissive state of the transmissive region, that is, the ink coverage in the transmissive region and the shape of the region exposed from the ink change depending on the landing state of the ink droplet in the transmissive region. Therefore, it is possible to grasp the ink droplet ejection state at the nozzle, that is, whether or not the ink droplet is ejected and the ink droplet ejection direction, by an easy method of grasping the transmission state of the transmission region of the inspection member from which the ink droplet has been ejected. be able to.

  In the ink jet head inspection method of the present invention, a detection region is further formed on the inspection member, and the inspection member is formed based on a detection result of a position detection sensor that detects the detection region in the placement step. It is preferable to arrange.

  In the ink jet recording apparatus of the present invention, it is preferable that a detection area is further formed on the inspection member, and further provided with a position detection sensor for detecting the detection area.

  According to these, the inspection member can be accurately arranged at a predetermined position in the arrangement step.

  In the ink jet head inspection method of the present invention, it is more preferable that the method further includes a transmission state detection step of detecting a transmission state of each transmission region of the inspection member after the ejection step. According to this, the transmission state of each transmission region can be accurately detected.

  Furthermore, in the ink jet head inspection method of the present invention, in the transmission state detection step, the coverage of the ink in the transmission region may be detected using a transmission type optical sensor.

  In the ink jet recording apparatus of the present invention, the transmission state detection unit may detect the ink coverage of the transmission region using a transmission type optical sensor.

  According to these, it is possible to detect the ink coverage in the transmission region with an inexpensive configuration.

  Alternatively, in the ink jet head inspection method of the present invention, in the transmission state detection step, the transmission region and the dots formed by landing the ink droplets ejected from the nozzle corresponding to the transmission region by image processing, The positional relationship may be detected.

  In the ink jet recording apparatus of the present invention, the transmission state detection unit is configured to position the transmission region and a dot formed by landing an ink droplet ejected from the nozzle corresponding to the transmission region by image processing. A relationship may be detected.

  According to these, since it is possible to detect the shape of the region exposed from the ink related to the transmission region, it is possible to grasp the ejection presence / absence and ejection direction of the ink droplets from the nozzle.

  In the ink jet recording apparatus of the present invention, it is preferable that the ink jet recording apparatus further includes a cleaning mechanism for cleaning a surface of the inspection member on which the ink droplet has landed after the inspection unit completes the inspection. According to this, the inspection member can be used repeatedly.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic side view showing the overall configuration of an inkjet printer according to an embodiment of the present invention. As shown in FIG. 1, the inkjet printer 101 is a color inkjet printer having four inkjet heads 1. The ink jet printer 101 includes a paper feeding unit 11 on the lower side in FIG. 1 and a paper discharge unit 12 on the right side in FIG. Further, a nozzle inspection unit 29 is disposed on the left side in FIG. Furthermore, the inkjet printer 101 has a control device 16 that controls the entire inkjet printer 101.

  Inside the ink jet printer 101, a paper transport path is formed through which the paper P is transported from the paper feed unit 11 toward the paper discharge unit 12. The paper feeding unit 11 accommodates the paper P in a stacked state, and includes a pickup roller 11a that sequentially feeds the paper P located in the uppermost layer to the left in FIG. A pair of feed rollers 5a and 5b and a guide 5c for nipping and conveying the paper are arranged immediately downstream of the paper supply unit 11. The pair of feed rollers 5a and 5b feed the paper P fed by the pickup roller 11a further from the paper feed unit 11 to the left in the drawing. The guide 5c reverses the sheet P fed to the feed rollers 5a and 5b to the right in FIG. In the intermediate portion relating to the paper conveyance path, two belt rollers 6 and 7, an endless conveyance belt 8 wound around the rollers 6 and 7, and an area surrounded by the conveyance belt 8 A paper transport mechanism 13 including a platen 15 disposed at a position facing the inkjet head 1 is provided. The platen 15 supports the conveyance belt 8 so that the conveyance belt 8 does not bend downward in a region facing the inkjet head 1. A nip roller 4 is disposed at a position facing the belt roller 7 on the downstream side of the guide 5c. The nip roller 4 presses the paper P guided by the guide 5 c against the outer peripheral surface 8 a of the conveyance belt 8.

  The conveyance belt 8 travels when the conveyance motor (not shown) rotates the belt roller 6. Thereby, the conveyance belt 8 conveys the paper P pressed against the outer peripheral surface 8 a by the nip roller 4 toward the paper discharge unit 12 while being adhesively held.

  A peeling mechanism 14 is provided immediately downstream of the conveying belt 8 along the sheet conveying path. The peeling mechanism 14 is configured to peel the paper P adhered to the outer peripheral surface 8 a of the transport belt 8 from the outer peripheral surface 8 a and send it to the paper discharge unit 12.

  The four inkjet heads 1 are provided side by side along the transport direction corresponding to four colors of ink (magenta, yellow, cyan, and black). That is, the ink jet printer 101 is a line printer. Each of the four inkjet heads 1 has a head body 2 at the lower end thereof. The head main body 2 has an elongated rectangular parallelepiped shape that is long in a direction orthogonal to the transport direction. Further, the bottom surface of the head main body 2 is an ink ejection surface 2a that faces the outer peripheral surface 8a. When the paper P transported by the transport belt 8 sequentially passes immediately below the four head bodies 2, ink droplets of each color are ejected from the ink ejection surface 2a toward the upper surface of the paper P, that is, the printing surface. Thus, a desired color image can be formed on the printing surface of the paper P. In addition, a pair of position detection sensors 40 are disposed in the vicinity of the downstream side of each inkjet head 1 so as to face the vicinity of both ends in the width direction of the conveyance belt 8. The position detection sensor 40 detects a position detection mark 41 on the inspection panel 30 described later.

  Next, the head body 2 will be described with reference to FIGS. FIG. 2 is a plan view of the head body 2. FIG. 3 is an enlarged view of a region surrounded by a one-dot chain line in FIG. In FIG. 3, for convenience of explanation, the pressure chamber 110, the aperture 112, and the nozzle 108 that are to be drawn with broken lines below the actuator unit 21 are drawn with solid lines. FIG. 4 is a partial cross-sectional view taken along the line IV-IV shown in FIG.

  As shown in FIG. 2, the head body 2 includes a flow path unit 9 and an actuator unit 21, and a reservoir unit (not shown) that supplies ink to the head body 2 and a drive that drives the actuator unit 21. The ink jet head 1 is formed by assembling a driver IC (not shown) that generates a signal.

  The head body 2 includes a flow path unit 9 and four actuator units 21 fixed to the upper surface 9 a of the flow path unit 9. As shown in FIG. 3, the flow path unit 9 has an ink flow path including a pressure chamber 110 and the like formed therein. The actuator unit 21 includes a plurality of actuators corresponding to the pressure chambers 110, and has a function of selectively giving ejection energy to the ink in the pressure chambers 110.

  The flow path unit 9 has a rectangular parallelepiped shape. A total of ten ink supply ports 105b are opened on the upper surface 9a of the flow path unit 9 corresponding to the ink outflow flow path (not shown) of the reservoir unit. As shown in FIGS. 2 and 3, a manifold channel 105 communicating with the ink supply port 105 b and a sub manifold channel 105 a branched from the manifold channel 105 are formed inside the channel unit 9. On the lower surface of the flow path unit 9, there is formed an ink ejection surface 2a in which a large number of nozzles 108 are arranged in a matrix. A large number of pressure chambers 110 are also arranged in a matrix like the nozzles 108 on the fixed surface of the actuator unit 21 in the flow path unit 9.

  In the present embodiment, 16 rows of pressure chambers 110 arranged at equal intervals in the longitudinal direction of the flow path unit 9 are arranged in parallel to each other in the short direction. The number of pressure chambers 110 included in each pressure chamber row is arranged so as to gradually decrease from the long side toward the short side corresponding to the outer shape (trapezoidal shape) of the actuator unit 21 described later. Yes. The nozzle 108 is also arranged in the same manner.

  As shown in FIG. 4, the flow path unit 9 includes a cavity plate 122, a base plate 123, an aperture plate 124, a supply plate 125, manifold plates 126, 127, and 128, a cover plate 129, and a nozzle plate 130 in order from the top. It consists of nine metal plates such as stainless steel. These plates 122 to 130 have a rectangular plane elongated in the main scanning direction.

  The cavity plate 122 is formed with a large number of through holes corresponding to the ink supply ports 105b and substantially rhombic through holes corresponding to the pressure chambers 110. In the base plate 123, a communication hole between the pressure chamber 110 and the aperture 112 and a communication hole between the pressure chamber 110 and the nozzle 108 are formed for each pressure chamber 110, and the communication between the ink supply port 105 b and the manifold channel 105 is formed. A hole (not shown) is formed. The aperture plate 124 is formed with a through hole serving as the aperture 112 for each pressure chamber 110 and a communication hole between the pressure chamber 110 and the nozzle 108, and a communication hole between the ink supply port 105 b and the manifold channel 105 (see FIG. (Not shown) is formed. In the supply plate 125, a communication hole between the aperture 112 and the sub manifold channel 105 a and a communication hole between the pressure chamber 110 and the nozzle 108 are formed for each pressure chamber 110, and the ink supply port 105 b and the manifold channel 105 are formed. A communication hole (not shown) is formed. In the manifold plates 126, 127, and 128, a communication hole between the pressure chamber 110 and the nozzle 108 for each pressure chamber 110, and a through-hole that is connected to each other at the time of stacking to form the manifold channel 105 and the sub-manifold channel 105a are formed. Has been. In the cover plate 129, a communication hole between the pressure chamber 110 and the nozzle 108 is formed for each pressure chamber 110. In the nozzle plate 130, nozzles 108 are formed for the respective pressure chambers 110.

  By laminating these plates 122 to 130 while being aligned with each other, the nozzle 108 in the flow path unit 9 passes from the manifold flow path 105 to the sub manifold flow path 105a and from the outlet of the sub manifold flow path 105a through the pressure chamber 110. A large number of individual ink channels 132 are formed.

  Next, the ink flow in the flow path unit 9 will be described. The ink supplied from the reservoir unit into the flow path unit 9 via the ink supply port 105b is branched from the manifold flow path 105 to the sub-manifold flow path 105a. The ink in the sub-manifold channel 105a flows into each individual ink channel 132 and reaches the nozzle 108 through the aperture 112 and the pressure chamber 110 functioning as a throttle.

  The actuator unit 21 will be described. As shown in FIG. 2, each of the four actuator units 21 has a trapezoidal planar shape, and is arranged in a staggered manner so as to avoid the ink supply ports 105b. Furthermore, the parallel opposing sides of each actuator unit 21 are along the longitudinal direction of the flow path unit 9, and the oblique sides of the adjacent actuator units 21 overlap each other in the width direction (sub-scanning direction) of the flow path unit 9. Yes.

  The actuator unit 21 has a laminated structure in which a plurality of piezoelectric sheets made of a lead zirconate titanate (PZT) ceramic material having ferroelectricity are laminated. The piezoelectric sheet is a continuous flat plate having a size straddling a plurality of pressure chambers 110. An individual electrode (not shown) is arranged at a position facing the pressure chamber 110 on the upper surface of the uppermost piezoelectric sheet. A common electrode (not shown) formed on the entire surface of the uppermost piezoelectric sheet is disposed on the lower surface of the uppermost piezoelectric sheet.

  The common electrode is equally grounded in the region corresponding to all the pressure chambers 110. On the other hand, a drive signal from the driver IC is selectively input to the individual electrode. That is, in the actuator unit 21, a portion sandwiched between the individual electrodes and the pressure chambers 110 functions as individual actuators, and a plurality of actuators corresponding to the number of pressure chambers 110 are formed.

  Here, a driving method of the actuator unit 21 will be described. The piezoelectric sheet is polarized in the thickness direction, and the portion where the individual electrode is disposed functions as an active layer. In this active layer, when an electric field is applied to the piezoelectric sheet in the polarization direction with the individual electrode having a potential different from that of the common electrode, the electric field application portion of the piezoelectric sheet is distorted by the piezoelectric effect. For example, if the polarization direction is the same as the electric field application direction, the active portion contracts in a direction (plane direction) perpendicular to the polarization direction. That is, the actuator unit 21 is a so-called unimorph type actuator in which the uppermost piezoelectric sheet is a layer including an active portion and the lower piezoelectric sheet is an inactive layer. Since the piezoelectric sheet is fixed to the upper surface of the cavity plate 122 that defines the pressure chamber 110, a difference in distortion in the plane direction occurs between the electric field application portion of the uppermost piezoelectric sheet and the piezoelectric sheet below it. The entire piezoelectric sheet is deformed (unimorph deformation) so as to be convex toward the pressure chamber 110. As a result, pressure (discharge energy) is applied to the ink in the pressure chamber 110, and an ink droplet is discharged from the nozzle 108.

  Returning to FIG. 1, the nozzle inspection unit 29 inspects the ejection state of the ink droplets related to the nozzles 108 in each inkjet head 1, and includes an inspection panel (inspection member) 30, an LED illumination 31, and a photodetector array ( (Transmission state detection means) 32 and a cleaning device 33. The inspection panel 30 will be described with reference to FIG. FIG. 5 is a plan view of the inspection panel 30. As shown in FIG. 5, the inspection panel 30 has a plurality of transmission regions 35 and a non-transmission that defines the transmission regions 35 by applying a non-transparent coating to a transparent hard thin plate member (glass, polycarbonate, etc.). A region 36 is formed.

  Further, position detection marks (detected areas) 41 are formed in the vicinity of both ends in the longitudinal direction of the inspection panel 30. Each transmission region 35 has a circular shape and is disposed so as to correspond to the nozzle 108 of the inkjet head 1. The inspection panel 30 can be moved in the left-right direction in FIG. 1 on a plane including the upper surface of the conveyor belt 8 by a panel moving mechanism (not shown), and to the right in FIG. 1 until it faces the upper surface of the conveyor belt 8. By being moved, the sheet is placed on the conveyor belt 8 from the downstream side of the nip roller 4. The inspection panel 30 placed on the transport belt 8 can be moved on the paper transport path by the paper transport mechanism 13.

  The position detection mark 41 is arranged in a specific positional relationship with each transmission region 35 on the downstream side in the transport direction (right side in FIG. 5). When the inspection panel 30 is conveyed to the paper conveyance mechanism 13 and the position detection mark 41 is detected by the position detection sensor 40 disposed on the downstream side of each inkjet head 1, each nozzle 108 of the inkjet head 1 and the inspection are detected. Each transmission region 35 of the panel 30 is opposed. Thus, the inspection panel 30 is placed on the conveyor belt 8. In this state, when ink droplets are ejected from all the nozzles 108 of the inkjet head 1, the ink droplets land on the transmission region 35 facing each nozzle 108 to form ink dots (see FIG. 7).

  Returning to FIG. 1, the LED illumination 31 is disposed below the inspection panel 30 at a position not facing the upper surface of the conveyor belt 8, and emits light upward. The photodetector array 32 is disposed so as to face the LED illumination 31 via the inspection panel 30 located at a position not facing the upper surface of the transport belt 8, and detects light emitted by the LED illumination 31. The photodetector array 32 includes a plurality of photodetectors arranged so as to be opposed to all the transmission regions 35 of the inspection panel 30. Thus, the LED illumination 31 and the photodetector array 32 constitute a light transmission type sensor that detects the ink coverage of each transmission region 35.

  The cleaning device 33 cleans the surface of the inspection panel 30 to which ink has adhered. A wipe unit to which cleaning liquid is supplied is disposed on the lower surface of the cleaning device 33, and the panel moving mechanism moves the inspection panel 30 while the wipe unit is in contact with the surface of the inspection panel 30. The surface of the panel 30 is wiped and cleaned.

  Next, an inspection method for inspecting the ejection state of the ink droplets related to the nozzles 108 of the inkjet head 1 will be described with reference to FIGS. 6 and 7. FIG. 6 is a block diagram illustrating a method for detecting the ejection state of ink droplets related to the nozzle 108. FIG. 7 is a partially enlarged view of the inspection panel 30. FIG. 7A shows a state before ink droplets from the nozzles 108 land, and FIG. 7B shows a state after ink droplets from the nozzles 108 land. Each state is shown. The inspection of the ink droplet ejection state related to the nozzle 108 is performed immediately after the ink jet printer 101 is turned on, before printing is started, or when an instruction is given from the user.

  When the inspection of the ink droplet ejection state is started, as shown in FIG. 6, the panel moving mechanism of the nozzle inspection unit 29 moves the inspection panel 30 so as to be placed at a predetermined position on the conveyor belt 8. Further, the sheet conveyance mechanism 13 conveys the inspection panel 30 until the position detection mark 41 of the inspection panel 30 is detected by the position detection sensor 40 disposed on the downstream side of the inkjet head 1. When the position detection mark 41 is detected, each nozzle 108 of the inkjet head 1 and each transmission region 35 of the inspection panel 30 face each other (arrangement step). Thereafter, in this state, ink droplets are ejected from all the nozzles 108 of the inkjet head 1 (ejection process). As a result, as shown in FIGS. 7A and 7B, ink droplets land on the transmission region 35 facing each nozzle 108 to form ink dots.

  Thereafter, the paper transport mechanism 13 returns the inspection panel 30 on which the ink dots are formed to the panel moving mechanism (the reverse direction of the paper transport direction). Further, the panel moving mechanism moves the inspection panel 30 so that the transmissive region 35 is disposed between the LED illumination 31 and the photodetector array 32. At this time, the photodetector array 32 detects the amount of light emitted from the LED illumination 31, in other words, the ink coverage of each transmissive area 35 (ratio in which the transmissive area 35 is covered with ink: transmissive state) (transmissive). State detection step). The photodetector array 32 outputs the detection result to the control device 16.

  When an ink droplet lands on the center of the transmissive area 35, the area exposed from the ink in the transmissive area 35 is almost eliminated, so that the ink coverage of the transmissive area 35 is the highest. When ink droplets are not landed on the transmissive area 35 (for example, X in FIG. 7B), since the entire transmissive area 35 is exposed from the ink, the ink coverage of the transmissive area 35 is the lowest. Furthermore, when the ink droplet has landed at a position away from the center of the transmissive region 35 in one direction, the region exposed from the ink in the transmissive region 35 is unevenly distributed in the other direction. Ink coverage changes. Therefore, the controller 16 can easily grasp the ink droplet ejection state of the nozzle 108 by grasping the ink coverage of the transmission region 35.

  When the photodetector array 32 completes the detection of the ink coverage in all the transmission regions 35, the panel moving mechanism moves the inspection panel 30 so that the entire surface of the inspection panel 30 is wiped by the cleaning device 33. Cleaning is completed (cleaning process). By performing the above steps in order for each inkjet head 1, the inspection of the ejection state of the ink droplets related to the nozzles of each inkjet head 1 is completed.

  The control device 16 detects the nozzle 108 in a non-ejection state or a state where the ink droplet landing position is a predetermined amount or more away from the center of the transmission region 35 (ejection abnormal state) based on the inspection result of the ink droplet ejection state. Then, the recovery operation of the nozzle 108 is performed by a purge operation for forcibly discharging the ink from the nozzle 108, or the driving of the nozzle 108 that is in an abnormal discharge state at the time of printing is stopped to discharge the ink discharged from the surrounding nozzles 108. Complement by changing the drop volume.

  As described above, according to the present embodiment described above, it is possible to inspect the ink droplet ejection state at the nozzle 108 by an easy method of detecting the ink coverage of the transmission region 35 of the inspection panel 30 from which the ink droplet has been ejected. .

  In addition, since the position detection mark 41 is formed on the inspection panel 30 and the inspection panel 30 is arranged according to the detection result of the position detection sensor 40 that detects the position detection mark 41 in the arrangement process, the inspection panel 30 is accurately set. It can be arranged at a predetermined position.

  Further, the LED illumination 31 and the photodetector array 32 constitute a light transmission type sensor that detects the ink coverage of each transmission region 35, and the photodetector array 32 detects ink in each transmission region 35 in the transmission state detection step. Since the coverage is detected, the ink coverage of each transmission region 35 can be accurately detected with an inexpensive configuration.

  In addition, since the cleaning device 33 cleans the surface of the inspection panel 30 to which ink has adhered in the cleaning process, the inspection panel 30 can be used repeatedly.

<First Modification>
In the present embodiment, the LED illumination 31 and the photodetector array 32 constitute a light transmission type sensor that detects the ink coverage of each transmission region 35. However, as shown in FIG. The CCD camera 32A is installed in the transmissive area 35, and the shape of the area exposed from the ink in the transmissive area 35 is imaged by the CCD camera 32A. You may detect the positional relationship with the ink dot formed when the ink droplet discharged from the nozzle 108 lands. According to this, it is possible to grasp whether or not the ink droplets are ejected from the nozzle 108 and the ejection direction.

<Second Modification>
In the present embodiment, in the transmission state detection step, the photodetector array 32 of the nozzle inspection unit 29 is configured to detect the ink coverage in each transmission region 35. However, the inkjet printer uses the photodetector array 32. The configuration may be such that the nozzle inspection unit 29 is not included and the inspection sheet 30A is discharged after ejecting ink droplets onto the inspection sheet (inspection member) 30A as shown in FIG. The inspection sheet 30 </ b> A is subjected to non-transparent printing on a transparent film, so as to correspond to each of the four inkjet heads 1, a plurality of transmission regions 35 and four non-transmission regions that define the transmission regions 35. Regions 36a to 36d are formed. In addition, position detection marks (detected areas) 41a to 41d are formed in the vicinity of both ends in the longitudinal direction of the inspection sheet 30A corresponding to the non-transmissive areas 36a to 36d. The position detection marks 41a to 41d are arranged at different positions with respect to the direction orthogonal to the paper transport direction. In this modification, the position detection sensor 40 disposed in the vicinity of the downstream side of the inkjet head 1 corresponding to the position detection marks 41a to 41d is disposed so as to face the position detection marks 41a to 41d. Shall.

  When inspecting the ejection state of ink droplets, the inspection sheet 30A is set on the paper feeding unit 11 and conveyed from the paper feeding unit 11 along the paper conveyance path. Each time the position detection sensor 40 detects the corresponding position detection marks 41a to 41d, the conveyance of the inspection sheet 30A is stopped. Accordingly, the inspection sheet 30A is arranged so that the nozzle 108 of the inkjet head 1 corresponding to the position detection marks 41a to 41d and the transmission region 35 face each other (arrangement step). In this state, ink droplets are ejected from the corresponding nozzles 108 of the inkjet head 1 to the transmission region 35 (ink ejection process). After performing the above steps for each inkjet head 1, the inspection sheet 30 </ b> A is discharged to the paper discharge unit 12.

  By inspecting the discharged inspection sheet 30A by visual inspection or the like, the nozzle 108 in an abnormal state can be detected. The inspection sheet 30A may be inspected by using a separately prepared transmission type optical sensor or CCD camera.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. For example, in the above-described embodiment, the position detection mark 41 is formed on the inspection panel 30, and the step of arranging the inspection panel 30 according to the detection result of the position detection sensor 40 that detects the position detection mark 41 in the arrangement step. However, the configuration may be such that the position detection mark 41 is not formed on the inspection panel 30 and the inspection panel is arranged visually or based on the driving amount of the conveyor belt 8.

  In the above-described embodiment, the inkjet printer 101 includes the cleaning device 33. However, the inkjet printer 101 may not include the cleaning device 33. In this case, it is preferable to replace the inspection panel 30 every time the ink discharge state is inspected.

  The inspection panel 30 exhibits hydrophobicity with respect to ink depending on the material (for example, glass or polycarbonate). For this reason, even if an appropriate ink droplet is ejected from each nozzle 108, it may be determined that the ejection amount is insufficient. From the viewpoint of accurately detecting at least the presence or absence of non-ejection, it is preferable to perform hydrophilic treatment on the transmission region 35. At this time, it is preferable that the plain paper has an average hydrophilicity. In addition, as a hydrophilic process, if glass is a base material, there exists a coating of a silicon oxide or a titanium oxide. Moreover, the contact angle with respect to a liquid is mentioned as a parameter | index which measures the hydrophilic property.

It is an external appearance side view of the inkjet head with which the nozzle plate which concerns on embodiment of this invention was assembled | attached. FIG. 3 is a plan view of the head main body shown in FIG. 2. It is an enlarged view of the area | region enclosed with the dashed-dotted line shown in FIG. It is the IV-IV sectional view taken on the line shown in FIG. It is a top view of the test | inspection panel shown in FIG. FIG. 4 is a block diagram illustrating an inspection method of an ink droplet ejection state related to the nozzle illustrated in FIG. 3. It is the elements on larger scale of the inspection panel shown in FIG. It is a top view of the inspection sheet concerning a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet head 13 Paper conveyance mechanism 16 Control apparatus 29 Nozzle inspection unit 30 Inspection panel (inspection member)
31 LED illumination 32 Photo detector array 33 Cleaning device 35 Transmission region 36 Non-transmission region 40 Position detection sensor 41 Position detection mark 101 Inkjet printer 108 Nozzle 30A Inspection sheet 32A Camera

Claims (11)

An inspection method for an inkjet head in which a plurality of nozzles for discharging ink droplets is formed on a recording medium,
An inspection member in which a plurality of transmission regions where ink droplets ejected from different nozzles land and a non-transmission region that defines the plurality of transmission regions are formed, corresponds to the transmission region and the transmission region. An arrangement step of arranging the nozzles to face each other;
An inkjet head inspection method comprising: an ejection step of ejecting ink droplets from the plurality of nozzles after the arranging step. A detection area is further formed on the inspection member,
2. The ink jet head inspection method according to claim 1, wherein in the disposing step, the inspection member is disposed based on a detection result of a position detection sensor that detects the detection area. 3.   The inkjet head inspection method according to claim 1, further comprising a transmission state detection step of detecting a transmission state of each transmission region of the inspection member after the ejection step.   4. The ink jet head inspection method according to claim 3, wherein, in the transmission state detection step, a coverage ratio of the ink related to the transmission region is detected using a transmission type optical sensor.   The positional relationship between the transmission region and a dot formed by landing of an ink droplet ejected from the nozzle corresponding to the transmission region by image processing is detected in the transmission state detection step. 4. A method for inspecting an inkjet head according to item 3. A transport mechanism for transporting the recording medium;
An inkjet head in which a plurality of nozzles for discharging ink droplets are formed on the recording medium conveyed by the conveyance mechanism;
A plurality of transmission regions where ink droplets ejected from different nozzles land, and a non-transmission region that defines the plurality of transmission regions;
Each of the transmission regions of the inspection member is ejected from the plurality of nozzles onto the inspection member that has been transported to a position where the transmission region and the nozzle corresponding to the transmission region face each other by the transport mechanism. An ink jet recording apparatus comprising: a transmission state detection unit that detects a transmission state of the ink. A detection area is further formed on the inspection member,
The inkjet recording apparatus according to claim 6, further comprising a position detection sensor that detects the detected area.   8. The ink jet recording apparatus according to claim 6, wherein the transmission state detection unit detects a coverage of the ink related to the transmission region by using a transmission type optical sensor.   The transmission state detection unit detects a positional relationship between the transmission region and dots formed by landing of ink droplets ejected from the nozzle corresponding to the transmission region by image processing. The ink jet recording apparatus according to 6 or 7.   The inkjet recording apparatus according to claim 6, further comprising a cleaning mechanism for cleaning a surface of the inspection member on which the ink droplet has landed after the inspection unit completes the inspection. . An inspection member for inspecting the ejection state of ink droplets at the nozzles according to an inkjet head in which a plurality of nozzles that eject ink droplets are formed,
An inspection member comprising: a plurality of transmissive regions on which ink droplets ejected from different nozzles land; and a non-transmissive region that defines the plurality of transmissive regions.

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