JP2013078852A - Detector, liquid ejector, and method for detecting abnormality of liquid ejection surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detector capable of detecting presence or absence of abnormality of a liquid ejection surface even when a distance between a detection element and the liquid ejection surface is varied without requiring strict focusing, and to provide a liquid ejector and a method for detecting abnormality of the liquid ejection surface.SOLUTION: When imaging the liquid ejection surface 16A of an inkjet head 16 by relatively moving the inkjet head 16 and an imaging part 140 arranged opposite to the liquid ejection surface 16A from an oblique direction so that a focusing object surface crosses the liquid ejection surface 16A, a focusing object area is set in an imaging area by the imaging part 140 on the liquid ejection surface 16A, and the imaging part 140 is made to focus on the liquid ejection surface 16A. The liquid ejection surface 16A is imaged at predetermined time intervals while relatively moving the inkjet head 16 and the imaging part 140 as a state where the imaging part 140 is made to focus on the liquid ejection surface 16A is maintained. Thus, abnormality information of the liquid ejection surface 16A is generated from imaging data of the focusing object area, and the abnormality information of the liquid ejection surface 16A is output.

Description

  The present invention relates to a detection device, a liquid ejection device, and an abnormality detection method for a liquid ejection surface, and more particularly to an abnormality detection technique for a liquid ejection surface of an inkjet head.

  The ink jet head provided in the ink jet recording apparatus may deteriorate the ejection performance when dirt such as liquid ink or solidified ink adheres to the ink ejection surface (liquid ejection surface). For example, if dirt is attached in the vicinity of the nozzle opening, the discharge amount is decreased and the flying direction is bent, which causes a dot size abnormality and a dot formation position abnormality.

  In order to avoid a decrease in ink discharge performance of the ink jet head, the ink discharge surface of the ink jet head is periodically cleaned to remove dirt from the ink discharge surface. For example, before cleaning the ink ejection surface, the ink ejection surface and the optical sensor are relatively scanned to detect the contamination of the ink ejection surface, and from the detection result, the presence or absence of contamination on the ink ejection surface is ascertained. By reflecting the detection result, the cleaning process of the ink ejection surface is efficiently performed.

  Patent Document 1 discloses an ink jet recording apparatus configured to take an image of a nozzle array surface using an image pickup unit provided in a standby area, and determine whether there is a discharge failure based on an image pickup result. Patent Document 1 discloses a configuration in which when an ejection failure of a line-type inkjet head is detected, the imaging unit is moved in the same direction by retracting the inkjet head in the longitudinal direction.

  Patent Document 2 discloses an ink jet recording apparatus that includes a CCD camera that observes a recording head from a face surface, and that analyzes an image obtained from the CCD camera to determine the presence or absence of color mixing on the face surface. . Japanese Patent Laid-Open No. 2004-26883 states that the liquid that adheres to the face surface is focused while focusing on the surface of the face surface, and that the image is shaken when the depth of field is shallow when the face surface is completely captured. Disclosure.

  Patent Document 3 discloses a camera that performs imaging while scanning. Patent Document 3 discloses a technical problem that the image plane and the object plane are not parallel, and discloses that a CCD camera inspection is performed while the distance measurement system and the goniometer are parallel to each other as a solution. Yes.

  Patent Document 4 discloses a configuration for supporting the camera while adjusting the angle of the camera with respect to the liquid discharge head. Patent Document 4 discloses that a meniscus, a still image or a moving image of a flying droplet is photographed by a camera, and the droplet ejection abnormality is detected by analyzing the captured image.

  Patent Document 5 discloses a nozzle plate configured to acquire position information of each nozzle hole and distance information of focusing with respect to the nozzle hole, and continuously recognize an image of the inside of each nozzle hole to detect the presence or absence of foreign matter. An inspection device is disclosed.

Japanese Patent No. 3929049 JP 2006-277772 A US Pat. No. 6,525,810 JP 2007-229928 A JP 2010-139357 A

  However, it is difficult to relatively move the ink discharge surface and the detection surface at a constant speed while accurately maintaining the parallel state of the ink discharge surface of the inkjet head and the detection surface of the sensor (the light receiving surface of the image sensor). If a change in the distance between the ink ejection surface and the detection surface or a change in the relative speed occurs, the detection result is affected.

  In particular, it is difficult to always keep the ink ejection surface and the detection surface parallel while moving a large-sized inkjet head such as a full-line inkjet head. When imaging an ink ejection surface (acquisition of an image) using an imaging device such as a CCD solid-state imaging device as a sensor, a part of the image obtained by the imaging may not be in focus and thus obtained. It is possible that the presence or absence of dirt on the ink ejection surface cannot be grasped from the obtained image.

  In an aspect in which continuous imaging is performed while appropriately performing focusing, the above-described problem can be solved, but it is necessary to stop relative movement between the inkjet head and the sensor during focusing. As the number of times of focusing increases, the number of times that the relative movement between the inkjet head and the sensor is stopped increases, and the time spent for detecting the ink ejection surface increases.

  The configurations disclosed in Patent Documents 1 to 5 perform detection while performing focusing, and there is a concern that dirt attached to the ink ejection surface cannot be accurately detected when the focus is shifted. On the other hand, as the number of times of focusing is increased, the time spent for detecting the ink ejection surface becomes longer.

  Further, the configuration disclosed in Patent Document 4 is difficult to adjust and focus on the optical path length, and there is a concern that the device configuration becomes complicated. Since the configuration disclosed in Patent Document 5 separately measures the focusing distance, the configuration becomes complicated.

  The present invention has been made in view of such circumstances, and does not require strict focusing and can detect whether there is an abnormality in the liquid ejection surface even when the distance between the detection element and the liquid ejection surface varies. It is an object to provide a detection device, a liquid ejection device, and a method for detecting a liquid ejection surface.

  In order to achieve the above object, a detection apparatus according to the present invention is arranged to avoid being directly under a liquid discharge surface of an inkjet head, and has an imaging unit that images the liquid discharge surface from an oblique direction with respect to the liquid discharge surface. A focusing setting unit that focuses the imaging unit on the liquid ejection surface, a relative moving unit that relatively moves the inkjet head and the imaging unit, and a relative moving unit that is relative to the imaging unit. In-focus target area setting means for setting a focus target area in which a focus position on the liquid discharge surface is included in an area in which the imaging means can capture an image on the moved liquid discharge surface; and the focus setting means The imaging hand is configured to image the liquid ejection surface at predetermined time intervals while relatively moving the inkjet head and the imaging unit while maintaining the focusing setting by Imaging control means for controlling the operation of the imaging apparatus, data processing means for performing predetermined processing on the imaging data obtained from the imaging means, and the liquid ejection surface from the imaging data of the focusing target area processed by the data processing means Abnormality information generating means for generating the abnormality information, and abnormality information output means for outputting the abnormality information of the liquid ejection surface generated by the abnormality information generating means.

  According to the present invention, the imaging obtained by the imaging means when imaging the liquid ejection surface from an oblique direction with respect to the liquid ejection surface by the imaging output arranged so as to avoid being directly below the liquid ejection surface of the inkjet head. From the data, an in-focus target area, which is an area where an in-focus image is obtained, is set, and while the imaging unit maintains the in-focus setting, the inkjet head and the imaging unit are relatively moved, Since the liquid ejection surface is imaged at a predetermined time interval, it is possible to capture an area on the liquid ejection surface where an image in focus of the imaging unit is obtained at a predetermined time interval, and change the focus setting of the imaging unit The imaging data over the entire surface of the liquid ejection surface can be acquired without doing so.

  Further, since the imaging data of the focus target area is extracted and the abnormality of the liquid ejection surface is detected based on the imaging data, the liquid ejection surface and the imaging means for focusing on the entire imageable area of the imaging means It is not necessary to make precise adjustments to make them parallel to each other.

1 is an overall configuration diagram showing a schematic configuration of an ink jet recording apparatus according to an embodiment of the present invention. 1 is a perspective plan view showing an example of the structure of the inkjet head shown in FIG. 1 is a block diagram showing a schematic configuration of a maintenance processing unit of the ink jet recording apparatus shown in FIG. 1 is a block diagram showing a schematic configuration of a control system of the ink jet recording apparatus shown in FIG. 3 is an explanatory diagram showing a detection range of the detection device shown in FIG. 3, a: a diagram of the inkjet head viewed from a direction orthogonal to the transport direction, b: a diagram viewed from the maintenance position side, and c: a diagram viewed from the ink ejection surface side. Block diagram of the detector shown in FIG. Schematic configuration diagram of a CCD image sensor provided in the detection apparatus shown in FIG. The block diagram which shows the structure of the signal processing part of the CCD image sensor shown in FIG. Explanatory drawing of the focusing target area on the ink ejection surface Explanatory drawing of composition processing of imaging data Explanatory drawing showing the image data of the focusing target area FIG. 11 is an explanatory diagram of an image synthesis process of the in-focus target area, a: edge detection process, b: shift process, c: enlargement / reduction process a: explanatory diagram showing a line segment parallel to the in-focus target position, b: explanatory diagram showing imaging data on the line segment Explanatory drawing of the process which shifts the imaging data of the line segment set to the focusing object area | region Top view of the ink ejection surface showing markings formed on the ink ejection surface Explanatory drawing of abnormality detection of the ink ejection surface based on the imaging data of the focusing target area 6 is a flowchart showing a flow of control for detecting abnormality of the ink ejection surface according to the present invention. Explanatory drawing of an example in which the abnormality detection result of the ink ejection surface is reflected in the wiping process 6 is a flowchart showing a flow of control of maintenance processing of an inkjet head including abnormality detection of an ink ejection surface according to the present invention. Overall configuration diagram showing a schematic configuration of an inkjet recording apparatus according to an application example to another apparatus configuration 20 is an explanatory diagram of abnormality detection of the ink ejection surface in the ink jet recording apparatus shown in FIG. 20, a: when there is one detection device, and b: when there are two detection devices. Explanatory drawing of the subject in the case of performing abnormality detection of the ink discharge surfaces of a plurality of inkjet heads using one detection device Explanatory drawing of the other subject at the time of performing abnormality detection of the ink discharge surface of a some inkjet head using one detection apparatus. Explanatory drawing of abnormality detection of the ink ejection surface by a detection device equipped with an imaging unit of a telephoto macro system Explanatory drawing of the image obtained by the detection apparatus shown in FIG.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.

[Overall configuration of inkjet recording apparatus]
FIG. 1 is an overall configuration diagram of an inkjet recording apparatus 10 according to the present invention. An ink jet recording apparatus 10 shown in FIG. 1 is an on-demand type ink jet recording apparatus, and a recording medium transport unit 14 that holds and transports a recording medium 12 and a recording medium 12 held by the recording medium transport unit 14. , K (black), C (cyan), M (magenta), and printing unit 17 including ink jet heads 16K, 16C, 16M, and 16Y that discharge color inks corresponding to Y (yellow). Yes.

  The recording medium conveyance unit 14 includes an endless conveyance belt 18 provided with a plurality of suction holes (not shown) in a recording medium holding area where the recording medium 12 is held, and a conveyance roller (drive) around which the conveyance belt 18 is wound. The roller 20 and the driven roller 22) and the back side of the conveyance belt 18 in the recording medium holding region (the surface opposite to the recording medium holding surface on which the recording medium 12 is held), and the non-adjustment provided in the recording medium holding region. A chamber 24 communicated with the illustrated suction hole and a vacuum pump 26 for generating a negative pressure in the chamber 24 are included.

  The recording medium transport unit 14 is housed in a housing frame (not shown in FIG. 1, but shown by reference numeral 15 in FIG. 3), and is fixedly supported by the housing frame.

  The carry-in unit 28 into which the recording medium 12 is carried is provided with a pressure roller 30 for preventing the recording medium 12 from floating, and the discharge roller 32 from which the recording medium 12 is discharged is also provided with a pressure roller 34. It has been.

  The recording medium 12 carried in from the carry-in section 28 is given a negative pressure from the suction hole provided in the recording medium holding area, and is sucked and held in the recording medium holding area of the transport belt 18.

  On the conveyance path of the recording medium 12, a temperature adjustment unit 36 for adjusting the surface temperature of the recording medium 12 to a predetermined range is provided on the upstream side of the printing unit 17 (upstream side in the recording medium conveyance direction). A reading device (reading sensor) 38 that reads an image recorded on the recording medium 12 is provided on the rear side of the recording medium 17 (downstream in the recording medium conveyance direction).

  The recording medium 12 carried in from the carry-in section 28 is sucked and held in the recording medium holding area of the conveyor belt 18 and subjected to temperature adjustment processing by the temperature adjustment section 36, and then image recording is performed in the printing section 17.

  As shown in FIG. 1, the inkjet heads 16K, 16C, 16M, and 16Y are arranged in this order from the upstream side in the recording medium conveyance direction. When the recording medium 12 passes directly under the ink jet heads 16K, 16C, 16M, and 16Y, each color ink of KCMY is ejected onto the recording medium 12 to form a desired color image.

  The printing unit 17 is not limited to the above-described form. For example, the inkjet heads 16LC and 16LM corresponding to LC (light cyan) and LM (light magenta) may be provided. Further, the arrangement order of the inkjet heads 16K, 16C, 16M, and 16Y can be changed as appropriate.

  The recording medium 12 on which the image has been recorded is discharged from the discharge section 32 after a recorded image (test pattern) is read by the reading device 38 and necessary fixing processing is performed by a fixing processing section (not shown). The reading result of the reading device 38 is used to determine ejection abnormality of the inkjet heads 16K, 16C, 16M, and 16Y.

  Although not shown in FIG. 1, the ink jet recording apparatus 10 includes a maintenance processing unit (shown with reference numeral 60 in FIG. 3) that performs maintenance processing on the ink jet heads 16K, 16C, 16M, and 16Y. The maintenance processing unit is arranged at a position away from the printing unit 17 in a direction orthogonal to the recording medium conveyance direction of the printing unit 17 (see FIG. 3).

  The ink jet recording apparatus 10 shown in FIG. 1 includes an ink supply unit (not shown). The ink supply unit includes an ink tank for each color (each head) that stores ink supplied to the inkjet heads 16K, 16C, 16M, and 16Y. Each of the ink tanks for each color and the ink jet heads 16K, 16C, 16M, and 16Y communicate with each other through an ink supply path (not shown).

(Composition of printing part)
FIG. 2 is a perspective plan view (viewed from the side opposite to the ink ejection surface) showing a structural example of the ink jet heads 16K, 16C, 16M, and 16Y provided in the printing unit 17. Since the same structure can be applied to the inkjet heads 16K, 16C, 16M, and 16Y illustrated in FIG. 1, here, the inkjet heads 16K, 16C, 16M, and 16Y are illustrated with a common reference numeral 16. To do.

  The inkjet head 16 is a full-line inkjet head in which ejection elements 54 including a plurality of nozzles 50 and pressure chambers 52 are arranged over a length exceeding the entire length of the recording medium 12 in the main scanning direction M.

  A recorded image can be recorded over the entire area of the recording medium 12 by a single-pass method in which the full-line inkjet head 16 and the recording medium 12 are moved only once relatively.

  In the inkjet head 16 shown in FIG. 2, a plurality of nozzles 50 (ejection elements 54) are arranged in a matrix along a row direction along the main scanning direction M and an oblique column direction not orthogonal to the main scanning direction M and the sub-scanning direction S. Has a structured.

  By arranging the nozzles 50 in a matrix as shown in FIG. 2, the substantial nozzle arrangement density in the main scanning direction M is increased. The nozzle arrangement of the inkjet head applicable to the present invention is not limited to the matrix arrangement shown in FIG.

  For example, a mode in which a single nozzle row in which a plurality of nozzles 50 are arranged along the longitudinal direction of the inkjet head 16 or a mode in which a plurality of nozzles 50 are arranged in two rows in the same direction can be applied.

  As the ejection method of the ink jet head 16, various ejection methods such as a piezoelectric method that utilizes the bending deformation of the piezoelectric element and a thermal method that utilizes the film boiling phenomenon of ink can be applied. The inkjet head 16 to which the piezoelectric method is applied includes a nozzle 50 that ejects ink, a pressure chamber 52 that communicates with the nozzle 50, and a piezoelectric element that is provided on at least one wall surface of the pressure chamber 52.

  A piezoelectric element has a structure in which a piezoelectric body is sandwiched between an upper electrode and a lower electrode, and bending deformation occurs when a driving voltage is applied between the upper electrode and the lower electrode, and pressure is caused by the bending deformation of the piezoelectric element. As the chamber 52 is deformed, the ink stored in the pressure chamber 52 is ejected from the nozzle 50.

  The inkjet head to which the thermal method is applied includes a heater that heats the ink stored in the pressure chamber (liquid chamber) 52, and bubbles are generated by instantaneously heating the ink in the pressure chamber 52. The ink is ejected from the nozzle 50.

[Description of the maintenance processing section]
FIG. 3 is a schematic configuration diagram of the maintenance processing unit 60 of the inkjet recording apparatus 10 shown in FIG. 1, and shows the arrangement relationship between the maintenance processing unit 60 and the printing unit 17.

  As shown in FIG. 3, the maintenance processing unit 60 moves the inkjet head 16 (16K, 16C, 16M, 16Y) from the image forming position on the recording medium conveying unit 14 in a direction substantially orthogonal to the conveying direction of the recording medium 12. It is arranged at the position moved horizontally.

  The maintenance processing unit 60 includes a cleaning device 62 that applies a cleaning liquid to the ink discharge surface 16A of the inkjet head 16, and a cap unit 64 that performs a purge process or a suction process (ink discharge process in the nozzles) on the inkjet head 16. A wiping processing unit 68 including a blade 66 that performs wiping processing on the ink ejection surface 16A of the inkjet head 16 after the purge processing or suction processing, and a detection device 70 that detects an abnormality in the ink ejection surface 16A of the inkjet head 16. And is configured.

  The cleaning device 62 and the wiping processing unit 68 may be configured integrally, or the cleaning device 62, the wiping processing unit 68, and the cap unit 64 may be configured integrally.

  In FIG. 3, the configuration of the maintenance processing unit 60 corresponding to one head is illustrated, but the cleaning device 62, the cap unit 64, the wiping processing unit 68, and the detection device 70 are provided for each inkjet head 16. There are as many as there are. A plurality of cleaning devices 62 and the like can be integrally formed.

  In order to move the ink jet head 16 from the image forming position immediately above the recording medium transport section 14 (the ink jet head 16 positioned at the image forming position is indicated by a broken line) to the maintenance position, the ink jet head 16 is moved onto the recording medium transport section 14. The image is temporarily retracted upward from the image forming position and further moved horizontally in a direction perpendicular to the conveyance direction of the recording medium 12.

  As the moving mechanism for moving the inkjet head 16 in the vertical direction and the horizontal direction, a well-known horizontal conveyance mechanism and vertical conveyance mechanism can be applied.

  The “maintenance position” is a concept including a processing region of the detection device 70, a processing region of the wiping processing unit 68, a processing region of the cleaning device 62, and a processing region of the cap unit 64. In FIG. 3, the inkjet head 16 located in the processing region of the cap portion 64 is illustrated by a one-dot broken line.

  When the ink jet head 16 reaches the processing area of the cleaning device 62, the cleaning device 62 is moved upward (or the ink jet head 16 is moved downward), and the ink ejection surface 16A is cleaned.

  When the cleaning process of the ink discharge surface 16A is completed, the inkjet head 16 is moved to the processing region of the cap part 64, the cap part 64 is brought into close contact with the ink discharge surface 16A, and the suction process or the purge process is executed.

  The cap unit 64 communicates with the waste ink tank 74 via the discharge channel 72, and a pump 76 is provided in the discharge channel 72. When the pump 76 is operated with the cap portion 64 in close contact with the ink discharge surface 16A, ink in the inkjet head 16 is sucked through the nozzles.

  In this way, when the purge or suction process of the inkjet head 16 is completed, the inkjet head 16 moves to the image forming position.

  The detection device 70 includes a CCD image sensor (not shown in FIG. 3 and indicated by reference numeral 160 in FIG. 7) that images the ink discharge surface 16A of the inkjet head 16 from an oblique direction facing the ink discharge surface 16A. An imaging unit (not shown in FIG. 3 and indicated by reference numeral 140 in FIG. 6) is provided. The inkjet recording apparatus 10 reflects the detection result of the detection device 70 based on the imaging data (still image imaging data) obtained from the imaging unit in the maintenance process of the inkjet head 16.

  Since the image pickup surface of the image pickup unit faces the image forming position, the detection device 70 prevents contamination due to ink mist scattered from the housing frame 15 and the ink jet head 16 housing the recording medium transport unit 14. Therefore, the imaging surface of the imaging unit is disposed at a position sufficiently away from the housing frame 15.

  Note that when the imaging surface of the imaging unit faces the direction of the maintenance processing unit 60, it is difficult to be affected by the above-described ink mist, so that the detection device 70 can be disposed closer to the housing frame 15. Therefore, the apparatus can be downsized.

[Explanation of control system]
FIG. 4 is a block diagram illustrating a schematic configuration of a control system of the inkjet recording apparatus 10. As shown in the figure, the inkjet recording apparatus 10 includes a communication interface 100, a system control unit 102, a conveyance control unit 104, an image processing unit 106, a head driving unit 108, and an image memory 110, a ROM 112, and the like. .

  The communication interface 100 is an interface unit that receives raster image data sent from the host computer 114. As the communication interface 100, a serial interface such as USB (Universal Serial Bus) may be applied, or a parallel interface such as Centronics may be applied. The communication interface 100 may include a buffer memory (not shown) for speeding up communication.

  The system control unit 102 includes a central processing unit (CPU) and its peripheral circuits, and functions as a control device that controls the entire inkjet recording apparatus 10 according to a predetermined program, and also functions as an arithmetic device that performs various calculations. Further, it functions as a memory controller for the image memory 110 and the ROM 112.

  That is, the system control unit 102 controls the communication interface 100, the conveyance control unit 104, and the like, performs communication control with the host computer 114, read / write control of the image memory 110 and the ROM 112, and the like. A control signal to be controlled is generated.

  Image data (recorded image data) sent from the host computer 114 is taken into the inkjet recording apparatus 10 via the communication interface 100 and subjected to predetermined image processing by the image processing unit 106.

  The image processing unit 106 has a signal (image) processing function for performing various processes and corrections for generating a print control signal from the image data, and the generated print data (dot data) is transferred to the head drive unit. 108 is a control unit for supplying to 108.

  When required signal processing is performed in the image processing unit 106, the ejection droplet amount (droplet ejection amount) and ejection of the inkjet head 16 via the head driving unit 108 based on the print data (halftone image data). Timing control is performed.

  Thereby, a desired dot size and dot arrangement are realized. Note that the head drive unit 108 shown in FIG. 4 may include a feedback control system for keeping the drive conditions of the inkjet head 16 constant.

  The conveyance control unit 104 controls the conveyance timing and conveyance speed of the recording medium 12 (see FIG. 1) based on the print data generated by the image processing unit 106. 4 includes a motor that drives the drive roller 20 (22) of the recording medium transport unit 14 that transports the recording medium 12, and the transport control unit 104 functions as a driver of the motor. Yes.

  An image memory (temporary storage memory) 110 functions as temporary storage means for temporarily storing image data input via the communication interface 100, a development area for various programs stored in the ROM 112, and a calculation work area for the CPU. (For example, a work area of the image processing unit 106). As the image memory 110, a volatile memory (RAM) capable of sequential reading and writing is used.

  The ROM 112 stores programs executed by the CPU of the system control unit 102, various data necessary for control of each unit of the apparatus, control parameters, and the like, and data is read and written through the system control unit 102. The ROM 112 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used. Alternatively, a removable storage medium that includes an external interface may be used.

  The parameter storage unit 118 stores various control parameters necessary for the operation of the inkjet recording apparatus 10. The system control unit 102 appropriately reads out parameters necessary for control and updates (rewrites) various parameters as necessary.

  The program storage unit 120 is a storage unit that stores a control program for operating the inkjet recording apparatus 10. When the system control unit 102 (or each unit of the device) executes control of each unit of the device, a necessary control program is read from the program storage unit 120, and the control program is appropriately executed.

  The display unit 122 is a means for displaying various information sent from the system control unit 102, and a general-purpose display device such as an LCD monitor is applied. Note that lighting (flashing and extinguishing) of the lamp may be applied to the display form of the display unit 122. Further, sound (sound) output means such as a speaker may be provided.

  As the input interface (I / F) 124, information input means such as a keyboard, a mouse, and a joystick is applied. Information input via the input interface 124 is sent to the system control unit 102.

  The maintenance control unit 126 controls the operation of each unit of the maintenance processing unit 60 illustrated in FIG. 3 based on the command signal sent from the system control unit 102. For example, the vertical movement, horizontal movement of the inkjet head 16, application of cleaning liquid to the ink discharge surface 16 A by the cleaning device 62, preliminary discharge by the cap unit 64, suction, contact and separation of the blade 66 with respect to the ink discharge surface 16 A, and the like are controlled. To do.

  The abnormality detection unit 128 determines whether there is an abnormality in the ink ejection surface 16A of the inkjet head 16 based on the detection result obtained from the detection device 70. Examples of the abnormality of the ink discharge surface 16A of the inkjet head 16 include adhesion of dirt to the ink discharge surface 16A, discovery of scratches, and the like. Abnormal information (the presence / absence of abnormality, the position of abnormality) of the ink ejection surface 16A is sent to the system control unit 102.

  When the system control unit 102 acquires the abnormality information of the ink ejection surface 16A, the abnormality information is stored in a predetermined memory and sent to the maintenance control unit 126. The maintenance control unit 126 reflects the abnormality information of the ink discharge surface 16A in the maintenance process of the inkjet head 16 by the maintenance processing unit 60.

[Explanation of abnormal detection of ink ejection surface]
Next, abnormality detection of the ink discharge surface 16A by the detection device 70 will be described in detail. FIG. 5 is an explanatory diagram of a detection range of the detection device 70 shown in FIG.

  FIG. 5A is a view of the inkjet head 16 (16K, 16C, 16M, 16Y) moving from the image forming position to the maintenance position as seen from the direction orthogonal to the transport direction, and the left side is the image forming position. The right side is the maintenance position. FIG. 5B shows the inkjet head 16 viewed from the maintenance position side, and the direction penetrating the paper surface is the moving direction of the inkjet head 16. FIG. 5C is a view as seen from the ink discharge surface 16A side, and the lower side of the drawing is a maintenance position.

  As shown in FIGS. 5A to 5C, the detection device 70 (imaging unit 140) is directly below the vertical direction (the direction orthogonal to the horizontal plane) of the ink discharge surface 16A of the inkjet head 16 (FIG. 5B). ) In FIG. 5A, the ink ejection surface 16A of the inkjet head 16 and the imaging surface of the imaging unit 140 due to ink dropped from the frame are avoided.

  That is, the optical axis of the detection device 70 (imaging unit 140) (shown with reference numeral 140A in FIG. 5C) is non-parallel to the normal line of the ink ejection surface 16A of the inkjet head 16. A detection device 70 is arranged.

  Further, since the detection device 70 needs to acquire image data that can grasp the dirt and scratches on the ink discharge surface 16A, the detection device 70 is disposed in the vicinity of the path through which the ink discharge surface 16A passes.

  5A to 5C, the imaging surface is opposed to the ink discharge surface 16A from an oblique direction, and the ink discharge surface 16A is inclined from the oblique direction with respect to the moving direction of the inkjet head 16. The imaging surfaces are arranged so as to face each other and the imaging data of the ink ejection surface 16A is acquired.

  On the other hand, in order to cope with a case where the detection device 70 does not have an imageable area (image angle of view) and imaging accuracy capable of acquiring imaging data with sufficient accuracy over the entire surface of the ink ejection surface 16A by one imaging, Imaging data of the entire surface of the ink ejection surface 16A is acquired by performing imaging for each position while changing the relative position with the ink ejection surface 16A.

  Since the stain on the ink ejection surface 16A is likely to adhere to the nozzle arrangement area where the nozzles are arranged, the detection device 70 captures imaging data from at least the entire nozzle arrangement area where the nozzles on the ink ejection surface 16A are arranged. It only has to be acquired. Of course, dirt on the ink discharge surface 16A may adhere to the entire surface of the ink discharge surface 16A. Therefore, the detection device 70 preferably acquires image data from the entire surface of the ink discharge surface 16A.

  A dashed line denoted by reference numeral 71A in FIG. 5A represents a surface (focus target surface 71A) on which the imaging unit 140 is focused. The focusing target surface 71A is a surface from which imaging data in focus of the detection device 70 (imaging unit 140) is obtained, and is a surface orthogonal to the optical axis of the imaging unit. The focusing target surface 71A in FIG. 5A extends in a direction penetrating the paper surface.

  A position where the focusing target surface 71A and the ink discharge surface 16A intersect is a focusing target position 71B on the ink discharge surface 16A, which is an actual focusing position on the ink discharge surface 16A. The focusing target position 71B in FIG. 5A is a line extending in a direction penetrating the paper surface.

  In the plan view of the ink discharge surface 16A shown in FIG. 5C, the focusing target position 71B has a length that reaches both ends of the ink discharge surface 16A in the short direction and intersects the short direction of the ink discharge surface 16A. It is grasped as an oblique line.

  5C can also be said to illustrate a state in which the optical axis 140A (a representative optical axis is illustrated) of the imaging unit 140 is projected onto a plane parallel to the ink ejection surface 16A. From FIG. 5C, it is understood that the direction of the optical axis 140A when the optical axis 140A of the imaging unit 140 is projected onto a plane parallel to the ink discharge surface 16A intersects the moving direction of the inkjet head 16. it can.

  The detection device 70 has an in-focus target area having a predetermined width centered on the in-focus target position 71B on the ink discharge surface 16A (the ink discharge surface 16A shown in FIG. An area in which imaging data can be acquired is set, and at least imaging data of the focusing target area is acquired.

  In order to acquire the imaging data of the focus target area, after acquiring the imaging data of the entire imageable area, the imaging data of the focus target area is cut out (extracted) from the imaging data of the entire imageable area. Alternatively, only the imaging data of the focus target area may be acquired.

  In other words, after acquiring the imaging data from the entire area of the imaging unit, the imaging data of the focusing target region may be extracted by processing the imaging data, or the imaging data is extracted from only a part corresponding to the focusing target region of the imaging unit. You may acquire (detailed later).

[Configuration example of detection device]
Next, an example of the configuration of the detection device 70 will be described. FIG. 6 is a block diagram illustrating a schematic configuration of the detection device 70. As shown in the figure, the imaging unit 140 including a CCD image sensor (shown with reference numeral 160 in FIG. 7) for imaging the ink ejection surface 16A (see FIG. 5) and each part of the detection device 70 are integrated. A control unit 142 that controls the image, an imaging condition setting unit 144 that sets the imaging conditions (focusing target area, imaging time interval, etc.) of the imaging unit 140, and imaging data obtained from the imaging unit 140 are subjected to predetermined processing. An imaging data processing unit 146 that generates detection information and a storage unit 148 that stores imaging data obtained from the imaging unit 140 and detection information (such as an image of the ink ejection surface 16A) generated by the imaging data processing unit 146. And an information output unit 150 for outputting the detection information to the outside, an input interface (input I / F) unit 152 for inputting information from the outside, and irradiating the ink ejection surface 16A with illumination light Configured to include an illumination unit 154, the that.

  The imaging condition setting unit 144 sets the imaging conditions of the imaging unit 140 with reference to imaging condition information stored in advance. The imaging information can be information input from the outside via the input I / F unit 152.

  A general-purpose interface such as USB (Universal Serial Bus), an input device such as a keyboard (touch panel), and a mouse can be applied to the input I / F unit 152.

  FIG. 7 is a schematic configuration diagram of a CCD image sensor 160 provided in the detection device 70. A CCD image sensor 160 shown in the figure is an interline CCD having a color filter.

  The CCD image sensor 160 shown in the figure includes a plurality of photodiodes 162 (162A, 162B) arranged two-dimensionally, and a vertical transfer CCD 164 that vertically transfers signal charges accumulated in the photodiodes 162, and a vertical transfer CCD 164. A horizontal transfer CCD 166 that transfers the signal charge sent from the transfer CCD 164 in the horizontal direction, and an output circuit 168 that outputs the signal charge transferred in the horizontal direction by the horizontal transfer CCD 166 as a dot sequential voltage signal are provided.

  In the CCD image sensor 160 shown in FIG. 7, since the photodiodes 162 are arranged in a staggered manner, the imaging resolution in the vertical direction is substantially twice the arrangement density of the photodiodes 162 in the same direction. For example, the photodiode group including the photodiode 162A and the photodiode group including the photodiode 162B on the right side of the photodiode group have the same arrangement pitch of the photodiodes 162 and are arranged with the vertical phase shifted by 1/2 pitch. Has been.

  These two photodiode groups can be regarded as one photodiode group in substantially the same direction. In FIG. 7, illustration of a transfer gate provided between the photodiode 162 and the vertical transfer CCD 164, a transfer gate electrode for controlling the transfer gate, and the like are omitted.

  Reading of the signal charge of the CCD image sensor 160 is performed according to the following procedure. (1) First, a transfer gate (not shown) is closed, and the ink ejection surface 16A of the inkjet head 16 is imaged (photodiode 162 is exposed). (2) The transfer gate is opened to transfer the charges accumulated in the photodiode 162 to the vertical transfer CCD 164 all at once. (3) The transfer gate is closed and the charge of each vertical transfer CCD 164 is transferred once. The charge of the pixel at the end of each photodiode group 93 is transferred to the horizontal transfer CCD 166.

  (4) A transfer pulse is sequentially applied to the horizontal transfer CCD 166 to output all horizontal pixels. (5) Returning to (3), steps (3) to (5) are repeated until all the pixels of the vertical transfer CCD 164 are read, and signal charges are read from all the photodiodes 162.

  FIG. 7 illustrates an interline CCD image sensor having a structure in which the photodiodes 162 are arranged in a staggered manner as an example of the imaging element provided in the imaging unit 140. However, the photodiodes 162 are arranged in a square lattice pattern. An interline CCD image sensor having the above structure may be applied, or a frame transfer CCD image sensor may be applied.

  In this example, a CCD image sensor provided with a color filter is illustrated, but a monochrome CCD image sensor not provided with a color filter may be applied. A CMOS image sensor may be used.

  FIG. 8 is a block diagram showing the configuration of the signal processing unit of the CCD image sensor 160 shown in FIG. 8 constitutes a part of the imaging data processing unit 146 in FIG. 6, and therefore, the same or similar parts in FIG. 8 as those in FIG. The description is omitted.

  A signal processing unit 170 shown in FIG. 8 performs an analog signal processing unit 172 that performs predetermined signal processing on an output signal (analog signal) of the CCD image sensor 160, and an analog signal after the signal processing by the analog signal processing unit 172 is converted into a digital signal. A / D conversion unit 174 for converting to digital signal, digital signal processing unit 176 for performing predetermined signal processing on the digital signal, CCD image sensor 160, analog signal processing unit 172, and A / D conversion unit 174 for synchronous control The CCD driving unit 178 for outputting the synchronization signal, the storage unit 180 for storing the digital signal (digital data) after the signal processing by the digital signal processing unit 176, and the digital data stored in the storage unit 180 are output. A signal output unit 182.

  The signal processing unit 170 shown in FIG. 8 is controlled by the control unit 142 together with the optical system 161 of the CCD image sensor 160. The optical system 161 includes a focus lens, a zoom lens, a diaphragm, and the like.

  In addition, an aspect including a display unit 186 that displays an image of the ink discharge surface 16A generated by the signal processing unit 170 is also possible. In this aspect, a television signal processing unit 188 that converts digital data stored in the storage unit 180 into a television signal (video signal) is provided.

  The analog signal processing unit 172 shown in FIG. 8 performs processing such as color separation, gain adjustment, and offset adjustment, and the digital signal processing unit 176 performs signal processing such as white balance adjustment and gamma correction, and the ink discharge surface 16A. The image is stored in the storage unit 180.

[Explanation of imaging data processing]
Next, a specific example of imaging data processing in the detection device 70 will be described. FIG. 9 is an explanatory view of a focusing target area on the ink discharge surface, is a plan view of a part of the ink discharge surface 16A, and FIG. 10 is an explanatory view of the imaging data combining process.

  As shown in FIG. 9, a focus target area 200 (illustrated by a dashed dotted thick line) is set on a part of an imageable area 201 (illustrated by a dashed dotted thin line) of the imaging unit 140 on the ink ejection surface 16A. .

  The focus target area 200 is in focus and blurred with the focus target position 71B (shown with reference numeral 202 in FIG. 9) described with reference to FIGS. 5A to 5C as a center line. The planar shape is a trapezoidal, fan-shaped, or rectangular region where a captured image can be obtained. In addition, you may correct | amend corresponding to the planar shape of the focusing object area | region 200 as needed.

  As described above, since the imaging data of the ink discharge surface 16A is acquired from an oblique direction with respect to the ink discharge surface 16A, the image is focused in the light receiving region of the CCD image sensor 160 (see FIG. 7). There is a blurred area that is out of focus with the existing area.

  In the detection apparatus 70 shown in this example, a focusing target area 200 in which an in-focus image (imaging data) is obtained is determined in advance as an imaging condition. The focusing target area 200 can be determined in advance from the positional relationship between the ink discharge surface 16A and the CCD image sensor 160. It can also be determined when the CCD image sensor 160 is focused.

  Further, when the imaging unit 140 has a center focus function, the width from the center of the imaging unit 140 (CCD image sensor 160) and the light rays of the ink ejection surface 16A and the focusing target surface 71A of the imaging unit 140 are detected. From the angle with the (focusing target position 71B), the focusing target area 200 can be obtained at the time of focusing.

  Then, in a state where the setting of the focusing target area 200 (focusing setting of the imaging unit 140) is maintained, the entire surface of the ink ejection surface 16A (at least the nozzle arrangement) is performed while relatively moving the inkjet head 16 and the detection device 70. Anomaly detection is performed over the entire area).

  FIG. 10 is an explanatory diagram of the imaging data combining process. The composition process illustrated in FIG. 10 is an example in which images obtained from the focus target areas 200-1, 200-2,...

  In the example illustrated in FIG. 10, the imaging data of only the focusing target area 200 is cut out from the imaging data of the imaging possible area including each focusing target area 200, and an image of each focusing target area 200 is generated. Images of the focus target area 200 are synthesized in order of time series, and an image of the entire surface of the ink ejection surface 16A is generated.

  Note that the synthesized image may be generated from the synthesized imaging data after the imaging data (image data after the imaging data is processed) of each focusing target area 200 are synthesized in chronological order.

  Observing the image of the ink ejection surface 16A shown in FIG. 10 makes it possible to grasp the stain 204A and the stain 204B. An image of the ink ejection surface 16A in a state where there is no abnormality such as dirt is stored in advance, and an image of the ink ejection surface 16A in a state where there is no abnormality is compared with an image generated by the detection device 70 to determine whether there is an abnormality. Can be judged.

  Next, the above-described image data composition processing will be described in more detail. In the following description, an example in which an image is synthesized based on the edge (edge, edge) of the ink discharge surface 16A will be described. The data format of the image data will be described as a bitmap format.

  FIG. 11 shows image data 210 of the focusing target area 200 generated based on the imaging data of the focusing target area 200 extracted from the imaging data of the imageable area including the arbitrary focusing target area 200. It is explanatory drawing.

  FIGS. 12A to 12C are explanatory diagrams of the image synthesizing process of the focusing target area 200 shown in FIG. Hereinafter, the procedure of the image data synthesis process will be described in time series. Note that the images of the focusing target area 200 illustrated in FIGS. 12A to 12C are examples in which the nozzle row is included in the focusing target area 200, and the focusing target area 200 of the processing target is illustrated. The image may include not only those illustrated in FIG. 11 but also those illustrated in FIGS. 12A to 12C and others.

  First, the long side edge (edge in the short direction) 16B of the ink discharge surface 16A is extracted (FIG. 12A). Next, the image data is shifted so that the edge 16B is aligned with the X-axis or Y-axis on the bitmap data (FIG. 12B. Further, a short side edge (in the longitudinal direction) that can be acquired immediately after the start of image data acquisition. The data is shifted in the direction orthogonal to the image data shift of the edge 16B from the inclination information of the edge.

  With these pre-processing, the portion corresponding to the focus area of the image when the nozzle plate is viewed from the front can be converted into data on the bitmap data, which is convenient for image synthesis, and the image is displayed on the display unit through the TV signal processing unit. It is also convenient when displaying. In addition, when it is necessary to adjust the scale so that the width of each image data is uniform, the scale is calculated based on information such as the length of the long side edge that can be acquired immediately after the start of image data acquisition and the focus target area 200. Information necessary for the adjustment can be obtained.

  Specifically, since the side closer to the sensor at the longitudinal edge of the ink ejection surface 16A is magnified and imaged, the focusing target area 200 is set to a trapezoid in advance according to the magnification, and the above-described image is captured after imaging. By performing trapezoidal correction at the time of pre-processing, it is possible to obtain a rectangular and scale-adjusted image, and by taking a very narrow width of the focusing target area 200 and synthesizing many linear images. Correction can also be omitted.

  In this way, a portion corresponding to the focusing target area 200 is converted into bitmap data as an image of the nozzle plate viewed from the front on the bitmap (FIG. 12C).

  In this way, when the image data of each focus target area 200 is generated, the image data of each focus target area 200 is synthesized in chronological order while the overlapping portions of the image data are deleted. When information on the imaging timing time of each focus target area 200 and information on the relative speed between the detection device 70 and the inkjet head 16 are stored, each focus that does not cause duplication or omission while referring to these information The composition process of the image data of the target area 200 can be realized.

  Further, the image data may be combined while overlapping a part thereof. An AND process (a process for extracting an overlapping part) or a process for giving priority to data having a lower density may be applied to the overlapping part process. By applying such processing, while noise data is removed, image data in which valid data continues in a wide area such as dirt is left. Furthermore, the rectangular images before the synthesis process can be arranged and stored in the storage unit without performing the synthesis process, and the image can be displayed on the display unit through the television signal processing unit.

  FIG. 13A is an explanatory diagram showing line segments 240 (240A, 240B, 240C) set in the focusing target area 200 and parallel to the focusing target position 71B, and FIG. It is explanatory drawing which shows the imaging data on the minute 240. FIG.

  In the image data combining process described above, the line segments 240A, 240B, and 240C arranged at the focusing target position 71B (240B) illustrated in FIG. 13A can be used. Note that the line segment 240B in FIG. 13A matches the in-focus target position 71B. Also, the line indicated by reference numeral 16C in FIG. 13A is a line parallel to the short direction passing through the center in the longitudinal direction (the center line in the longitudinal direction of the ink ejection surface 16A).

  The focusing target area 200 illustrated in FIG. 13A is, for example, when the ink discharge surface 16A is viewed at a very close position and in a direction close to the front, or when the width of the focusing target area 200 is very large. In this example, the focusing target area 200 is not distorted, the planar shape is almost rectangular, and the three line segments 240A, 240B, and 240C are parallel to each other. On the other hand, if the scale is different between the near side (lower side of the figure) and the far side (upper side of the figure) of the captured image of the focusing target area 200 and the captured nozzle row (group) appears to be trapezoidal or fan-shaped, 3 The line segments 240A, 240B, and 240C may be non-parallel.

  The data values of the imaging data 250A, 250B, and 250C on the respective line segments 240A, 240B, and 240C illustrated in FIG. 13B include a luminance signal data value, a detection value of an arbitrary color component, and a combined value of each color component. Etc. can be applied.

  FIGS. 14A and 14B are explanatory views schematically illustrating processing for shifting the imaging data 250A, 250B, and 250C of the line segments 240A, 240B, and 240C illustrated in FIG. 13A.

  FIG. 14A shows an example in which the imaging data 250B and 250C are shifted and stored so that the reference position is aligned on the imaging data 250A, 250B, and 250C with the short edge 16B of the ink ejection surface 16A as the reference position. (Offset in the short direction of the ink discharge surface 16A).

  In FIG. 14A, the position denoted by reference numeral 260 is the reference position (edge 16B), and the imaging data 250B and 250C are shifted according to the imaging data 250A.

  Further, since the line segments 240A, 240B, and 240C are not orthogonal to the longitudinal center line 16C of the ink discharge surface 16A, the longitudinal center line 16C of the ink discharge surface 16A and the line segments 240A, 240B, and 240C, respectively. It is necessary to obtain angles formed by 240C and store the image data by shifting addresses on the image data.

  Therefore, the longitudinal offset of the ink discharge surface 16A can be obtained by using a longitudinal edge (not shown) of the ink discharge surface 16A or by marking the ink discharge surface 16A with a center line 16C in the longitudinal direction. As shown in FIG. 14B, the imaging data can be shifted from the reference position 262 based on the offset amount.

  In this way, the edge 16B of the ink discharge surface 16A, the edge in the longitudinal direction (not shown), the center line 16C in the longitudinal direction of the ink discharge surface 16A, and the like correspond to the edge of the ink discharge surface 16A and the edge. By extracting the feature points of the part and shifting the imaging data with reference to the feature points, the imaging data (image) of the in-focus target region 200 can be synthesized without duplication or omission.

  The characteristic points of the ink discharge surface 16A include a virtual line connecting nozzles at the ends of nozzle groups composed of boundary portions (head module connecting portions) for fitting the head modules and nozzles 50 arranged obliquely. May be applied. The imaginary line can be calculated from the nozzle arrangement data.

  It is also possible to extract image features (such as points having a high contrast portion) as feature points.

  FIG. 15 is a plan view of the ink ejection surface 16A showing an example in which markings are formed on the ink ejection surface 16A as a reference for the synthesis process.

  As shown in the figure, a marking 270 (270A, 270B, 270C) for each focusing target area 200 is formed on the ink discharge surface 16A, and each focusing is performed while referring to the marking 270 for each focusing target area 200. It is also possible to synthesize the image data of the target area 200.

  Although FIG. 15 illustrates an example in which the markings 270A, 270B, and 270C having different shapes are formed for each focusing target region 200, the markings 270 having the same shape may be formed. Further, as another example of the marking 270, an aspect in which a continuous line is formed on both sides of the nozzle group in which the nozzles 50 are arranged in an oblique direction, a continuous line of a specific color (for example, white) that is easily distinguished from dirt, The aspect to form is mentioned. Furthermore, a nozzle arrangement can be used.

  In the processing of the imaging data described above, the processing for generating the image (image data in the bitmap format or the like) of the ink ejection surface 16A from the imaging data of the focusing target area 200 has been described. Alternatively, it is also possible to generate image data and detect an abnormality for each focusing target area 200 without performing a composition process.

  For example, the imaging data of the focusing target area 200 is extracted from the imaging data of the imageable area for each imaging, the image data of the focusing target area 200 is generated, and the imaging timing of each focusing target area 200 is determined. Whether or not there is an abnormality may be determined in units of the focusing target area 200 while referring to information on time data, information on the relative speed between the detection device 70 and the inkjet head 16, and the like.

  Further, as shown in FIG. 13B, it is possible to determine the presence or absence of abnormality based on the imaging data (luminance data before image data is generated) 250. Next, abnormality detection of the ink ejection surface 16A based on the imaging data 250 illustrated in FIG. 13B will be described.

  FIG. 16 is an explanatory diagram of abnormality detection of the ink ejection surface 16 </ b> A based on the imaging data 250 of the focusing target area 200. FIG. 16A is a plan view of the ink ejection surface 16A to which the dirt 280 is attached, and FIG. 16B is an explanation showing imaging data 250A ′, 250B ′, and 250C ′ of the ink ejection surface 16A to which the dirt 280 is attached. FIG.

  In the imaging data 250A ′, 250B ′, and 250C ′ illustrated in FIG. 16B, signal components 252A, 252B, and 252C corresponding to the dirt 280 illustrated in FIG. Therefore, it is possible to determine the presence or absence of abnormality from the change in the pattern of the imaging signal based on the imaging signals 250A, 250B, and 250C (see FIG. 13B) at the normal time.

  It is also possible to determine whether there is an abnormality from the change in the ratio of the color components. When the ratio of the color components exceeds a preset threshold value, the case where the value of a certain color component continuously shows a high value can be handled as an abnormality. Further, by combining these abnormality determinations, it is possible to determine the presence / absence of an abnormality based on a plurality of criteria.

  This abnormality detection can also be performed on a rectangular image before the synthesis process. In such a case, since abnormality detection can be performed even during imaging (detection), feedback can be immediately applied to wiping control using a blade (see FIG. 3), which is convenient.

  FIG. 17 is a flowchart showing a flow of control for detecting abnormality of the ink discharge surface 16A. As shown in the figure, when the abnormality detection of the ink ejection surface 16A is started (step S10), the detection condition of the detection device 70 (imaging condition of the imaging unit 140) is set (step S12). Examples of the imaging conditions include setting of a focusing target area 200 (see FIG. 9), focus setting, moving speed of the inkjet head 16, imaging timing, and the like.

  When the imaging condition is set in step S12, imaging of the ink ejection surface 16A is started, imaging data is sequentially acquired, and image data is generated from the imaging data and stored (step S13). In step S14, it is determined whether or not the entire area of the ink ejection surface 16A has been imaged, and this process is repeated until the imaging of the entire area is completed (No determination in step S14).

  On the other hand, if it is determined that the entire area of the ink ejection surface 16A has been imaged (Yes determination in step S14), the image data is analyzed (step S16). If no abnormality is found by the analysis of the image data in step S16 (No determination in step S18), the abnormality detection of the ink ejection surface 16A is terminated (step S24).

  On the other hand, if an abnormality is found in step S18 (Yes determination), the abnormality information is stored in a predetermined memory (step S20), and the abnormality information is output (step S22). This abnormality information includes information on the position of the abnormality (focusing target area where the abnormality has occurred) and information on the content of the abnormality (dirt, scratch, etc.).

  When abnormality information is output in step S22, the abnormality detection of the ink ejection surface 16A is terminated. If it is determined whether or not there is an abnormality while imaging, and feedback is immediately applied to the wiping control by the blade, the determination of whether or not there is an abnormality is made before determining whether or not all areas have been imaged (step S14). And information on the presence or absence of abnormality may be output to the outside together with the imaging position information.

  According to the abnormality detection of the detection device 70 and the ink discharge surface 16A configured as described above, the intersection position (focus target position 71B) of the focus target surface 71A of the detection device 70 (imaging unit 140) and the ink discharge surface 16A. ) Including the focusing target area 200 is set, the focus is set, and the imaging data of the focusing target area 200 is acquired in a state where these settings are maintained, and the imaging data of the focusing target area 200 is obtained. Since the presence / absence of abnormality of the ink discharge surface 16A is determined based on this, the setting of the detection condition (image pickup condition of the image pickup unit 140) of the detection device 70 that cannot detect the entire surface of the ink discharge surface 16A at a time is changed. In other words, it is possible to detect the entire ink discharge surface 16A (at least the entire nozzle arrangement region).

  In addition, by setting the focusing target area 200, it is not necessary to adjust the ink ejection surface 16A and the detection surface of the detection device 70 (imaging surface of the imaging unit 140) accurately in parallel, and the ink ejection surface 16A and the detection surface are detected. Even if the positional relationship with the detection surface of the apparatus 70 varies, it is possible to acquire imaging data (image) of the ink ejection surface 16A.

  Furthermore, it is not necessary to focus the detection device 70 (imaging unit 140) while relatively moving the detection device 70 and the inkjet head 16, and the ink discharge surface 16A can be detected at high speed.

[Description of maintenance processing of inkjet head]
Next, the maintenance process of the inkjet head 16 that reflects the result of the abnormality detection of the ink discharge surface 16A described above will be described.

  FIG. 18 is an explanatory diagram of an example in which the abnormality detection result of the ink discharge surface 16 </ b> A is reflected in the wiping process by the blade 66. The blade 66 is in contact with the ink discharge surface 16A wetted by a wet processing unit (not shown), and wipes and removes dirt on the ink discharge surface 16A.

  An adjustment mechanism that adjusts the posture of the blade 66 so that the blade 66 is inclined with respect to the moving direction of the inkjet head 16 (the longitudinal direction of the inkjet head 16 illustrated by the arrow line) is provided. The angle α of the blade 66 is adjusted according to the angle of the focusing target area 200.

  As described above, when the posture of the blade 66 is adjusted so as to be substantially parallel to the focusing target area 200, simple control is performed when it is determined that the ink ejection surface 16A is contaminated. This enables feedback to the wiping condition (change of wiping pressure) of the wiping processing unit 68 (blade 66).

  That is, the condition of the maintenance process can be changed according to the abnormality information on the ink ejection surface 16A, and the focus is set so that the feedback of the abnormality information to the maintenance conditions (the number of maintenance, the processing environment temperature, etc.) is simplified. A relationship between the target area 200 and the maintenance processing unit may be determined.

  FIG. 19 is a flowchart showing a control flow of maintenance processing of the inkjet head 16 that reflects the result of abnormality detection of the ink ejection surface 16A shown in this example.

  As shown in the figure, when the maintenance process of the inkjet head 16 is started (step S100), the inkjet head 16 is moved from the image forming position to the maintenance position (step S102), and the ink discharge surface 16A shown in FIG. Abnormality detection is executed (step S104).

  When the abnormality detection of the ink ejection surface 16A in step S104 is completed, the presence / absence of abnormality information on the ink ejection surface 16A is confirmed (step S106). If there is no abnormality information (No determination in step S106), the maintenance condition is set to the standard condition, and the ink discharge surface cleaning (step S110), purge (step S112), and the like are appropriately executed.

  On the other hand, if there is abnormality information (Yes determination in step S106), maintenance conditions are set (changed) corresponding to the abnormality information (step S108), the ink ejection surface is cleaned (step S110), and purged (step S112). Etc. are appropriately executed.

  When the predetermined process for the inkjet head 16 is completed, the inkjet head 16 is moved to the image forming position (step S114), and the maintenance process for the inkjet head 16 is terminated (step S116).

  In this example, the aspect in which the abnormality detection of the ink ejection surface 16A is performed before the maintenance process of the inkjet head 16 is described. However, the abnormality detection of the ink ejection surface 16A may be performed after the maintenance process of the inkjet head 16. The abnormality detection of the ink discharge surface 16A may be executed both before and after the maintenance process of the inkjet head 16.

  When abnormality detection of the ink ejection surface 16A is performed after maintenance of the inkjet head 16, the direction of the detection device 70 in FIG. 3 is reversed left and right, and the detection surface of the detection device 70 is directed toward the maintenance processing unit 60. May be.

  In this aspect, data for detecting the ink discharge surface 16A can be acquired at an earlier timing.

  In addition, it is preferable that the detection device 70 is disposed so as to avoid the direction in which the elastic deformation of the blade 66 is released. For example, in FIG. 3, the positions of the detection device 70 and the blade 66 may be interchanged so that the detection device 70 is disposed on the upstream side in the movement direction of the inkjet head 16 and the blade 66 is disposed on the downstream side.

  Further, in the arrangement shown in FIG. 3, the detection device may be arranged at a position where the distance between the detection device 70 and the blade 66 is increased and the liquid does not fly when the elastic deformation of the blade 66 is released. The position where the liquid does not fly when the elastic deformation of the blade 66 is released varies depending on the moving speed of the inkjet head 16, the material of the blade 66, the aging, and the state of deterioration.

[Application examples to other device configurations]
Next, an application example of the above-described abnormality detection of the ink discharge surface 16A to another apparatus configuration will be described. In the following description, the ink discharge surfaces 316A (316AK, 316AC, 316AM, 316AY) of the inkjet heads 316K, 316C, 316M, and 316Y are inclined with respect to the horizontal plane so as to face the outer peripheral surface of the impression cylinder 314 at right angles. A mode in which the inkjet heads 316K, 316C, 316M, and 316Y are arranged will be described.

  FIG. 20 is a schematic configuration diagram of an ink jet recording apparatus 300 to which an impression cylinder transport method is applied for transport of a recording medium. In the inkjet recording apparatus 300 shown in the figure, a color image is formed by the printing unit 317 on the recording medium transferred from the transfer cylinder 328 to the impression cylinder (drawing cylinder) 314, and the recording medium after the image formation is compressed. The material is transferred from the cylinder 314 to the transfer cylinder 332.

  Although not shown in FIG. 20, the ink jet recording apparatus 300 includes a maintenance processing unit at a position away from the impression cylinder 314 in a direction orthogonal to the recording medium conveyance direction (a direction penetrating the paper surface in FIG. 20) (FIG. 20). 3). The inkjet heads 316K, 316C, 316M, and 316Y are configured to collectively move between the image forming position and the processing position of the maintenance processing unit.

  FIG. 21 is an explanatory diagram of abnormality detection of the ink ejection surface 316A in the ink jet recording apparatus 300 shown in FIG. 20, FIG. 21 (a) shows the case where there is one detection device 370, and FIG. 21 (b) shows the detection. This is a case where there are two apparatuses 370 (370-1, 370-2).

  In the case of including one detection device 370 shown in FIG. 21A, the detection device 370 is arranged at the center (between the inkjet head 316C and the inkjet head 316M) of the four inkjet heads 316K, 316C, 316M, and 316Y. One detection device 370 simultaneously detects the ink ejection surfaces 316AK, 316AC, 316AM, and 316AY of the four inkjet heads 316K, 316C, 316M, and 316Y under a common imaging condition.

  In the embodiment illustrated in FIG. 21A, the ink ejection surfaces 316AK, 316AC, 316AM, and 316AY of the inkjet heads 316K, 316C, 316M, and 316Y are inclined toward the outer peripheral surface of the impression cylinder 314, and thus the pressure is increased. By disposing the detection device 370 on a line extending in a direction orthogonal to the horizontal plane from the rotation axis (center axis) of the cylinder 314, the ink ejection surfaces 316AK, 316AC, 316AM, and 316AM of the inkjet heads 316K, 316C, 316M, 316Y, 316AY can be accommodated in the detection area of the detection device 370.

  In the case where two detection devices 370 shown in FIG. 21B are provided, the first detection device 370-1 is disposed between the inkjet head 316M and the inkjet head 316Y, and the second detection device 370-2 is provided. Is arranged between the inkjet head 316K and the inkjet head 316C, and one detection device 370-1 detects the ink ejection surfaces 316AM and 316AY of the two inkjet heads 316M and 316Y simultaneously, and the detection device 370-2 is the inkjet head. The ink ejection surfaces 316AK and 316AC of 316K and 316C are simultaneously detected under common imaging conditions.

  That is, the number of ink ejection surfaces 316AK, 316AC, 316AM, 316AY of the plurality of inkjet heads 316K, 316C, 316M, 316Y arranged to be inclined with respect to the horizontal plane is smaller than the number of inkjet heads 316K, 316C, 316M, 316Y. The number of detection devices 370 is used for detection, and one detection device 370 simultaneously detects one ink ejection surface 316A or a plurality of ink ejection surfaces 316A under common imaging conditions.

  Also in the example illustrated in FIGS. 21A and 21B, the detection device 370 ejects ink from an oblique direction with respect to the ink ejection surfaces 316AK, 316AC, 316AM, and 316AY of the inkjet heads 316K, 316C, 316M, and 316Y. Surfaces 316AK, 316AC, 316AM, and 316AY are detected.

  In addition, the detection device 370 is disposed so as to avoid a position directly below the ink discharge surface 316A (directly below the passage area of the ink discharge surface 316A), and ink scattered from the blade 366 (366K, 366C, 366M, 366Y) adheres thereto. Arranged to avoid the area.

  The detection device 370 is disposed on the inner side of the surface of the inkjet head 316K lowered in the vertical direction and on the inner side of the surface of the inkjet head 316Y lowered in the vertical direction.

  Further, the image pickup unit of the detection device is arranged so that the direction of the image pickup unit (the direction of the optical axis of the image pickup unit) intersects any of the surfaces parallel to the ink discharge surfaces 316AK, 316AC, 316AM, and 316AY.

  Here, a problem in the case of performing abnormality detection on the ink ejection surfaces 316A of the plurality of inkjet heads 316 using one detection device 370 will be described. FIG. 22 is an explanatory diagram showing the problem.

  In detecting the abnormality of the ink ejection surface 316A, since the presence or absence of dirt or scratches having a size of several tens to several hundreds of micrometers is analyzed, it is obtained by close-up photography (proximity imaging) or microscopic imaging (high magnification enlarged imaging). A high-definition image of the order is required. However, in order to put the ink ejection surfaces 316A of the plurality of inkjet heads 316 in the image pickup possible region, there is a restriction on the performance of the detection device 370 (image pickup unit).

  Although it is conceivable to include an optical system capable of wide-angle imaging, in this case, the detection device 370 needs to be brought closer to the ink ejection surface 316A, and there are restrictions on the arrangement of the inkjet head 316.

  Further, as shown in FIG. 22, there is a difference in distance between the detection device 370 and the ink ejection surfaces 316AK, 316AC, 316AM, 316AY of the inkjet heads 316K, 316C, 316M, and 316Y, and the detection device 370 is changed to the ink ejection surface 316AK. , 316AC, 316AM, and 316AY, the difference in distance is enlarged, and the inkjet heads 316K and 316Y that are further away from the detection device 370 have a large image distortion, making it difficult to obtain a high-definition image. become.

  Then, when the images of the focusing target areas 200 (see FIG. 9) on the ink ejection surfaces 316AK, 316AC, 316AM, and 316AY of the inkjet heads 316K, 316C, 316M, and 316Y are combined, distortion correction increases, and the image is corrected. There is a problem that the accuracy of the system drops.

  On the other hand, as shown in FIG. 23, the distances between the ink ejection surfaces 316AK, 316AC, 316AM, and 316AY and the detection device 370 can be made equal, but there are restrictions on the arrangement of the detection device 370. It is difficult to avoid restrictions on the arrangement of the detection device 370 while satisfying the required accuracy of detection.

  Therefore, as shown in FIG. 24, a detection device 370 ′ having a telephoto macro imaging unit is provided, and the detection device 370 ′ is arranged at a position somewhat away from each ink ejection surface 316AK, 316AC, 316AM, 316AY. While detecting the ink ejection surfaces 316AK, 316AC, 316AM, and 316AY in the visual field of the detection device 370 ′, the detection is performed so that the distance between the ink ejection surfaces 316AK, 316AC, 316AM, and 316AY and the detection device 370 ′ becomes shorter. The arrangement of the device 370 ′ is adjusted.

  That is, in the aspect provided with the telephoto macro system imaging unit, the distance from the detection device 370 ′ to the observation surface (the focus target area 200 of the ink discharge surfaces 316AK, 316AC, 316AM, and 316AY) is separated, but the ink discharge surface 316AK. , 316AC, 316AM, 316AY itself and the distance between the detection device 370 ′ may not be separated.

  In FIG. 24, the one-dot broken lines illustrated with reference numerals 371KB, 371CB, 371MB, and 371YB are the focus target positions at the imaging timings of the respective ink ejection surfaces 316AK, 316AC, 316AM, and 316AY, and the arrow lines are representative. Expresses the field of view.

  FIG. 25 is an explanatory diagram showing the respective inkjet heads 316K, 316C, 316M, 316Y (see FIG. 24) images 340K, 340C, 340M, 340Y obtained by the detection device 370 'shown in FIG.

  The focus target positions 371KB, 371CB, 371MB, and 371YB, which are the intersection lines between the focus target surface (see FIG. 5) of the detection device 370 ′ and the ink discharge surface, are different for each of the ink discharge surfaces 316AK, 316AC, 316AM, and 316AY. Therefore, the focus target area is determined for each of the ink ejection surfaces 316AK, 316AC, 316AM, and 316AY.

  Here, when setting the imaging conditions, the focusing target surface of the detection device 370 ′ and the ink discharge surfaces 316AK, 316AC, 316AM, and 316AY correspond to the inkjet heads 316K, 316C, 316M, and 316Y and the detection device 370 ′. If it is set so as to intersect during the relative movement, it is possible to acquire images of the focus target areas of the respective ink ejection surfaces 316AK, 316AC, 316AM, and 316AY at a time.

  That is, when setting the imaging condition, the distance to the focusing target surface is set for one head, the focusing target area is set, and the setting for the one head is set for the remaining heads. The focus target area for each head is determined while maintaining the above. In addition, the planar shape and the number of the focusing target regions may be different for each head.

  The process of synthesizing the image of the focus target area 200 (see FIG. 9) and the process of determining abnormality of the ink ejection surface 316A from the imaging data of the focus target area are performed by one detection device 70 described above. A process for detecting the ink discharge surface 16A can be applied.

  According to the abnormality detection of the ink ejection surface according to this example, the abnormality detection of the ink ejection surfaces 316A of the plurality of inkjet heads 316 can be simultaneously performed by a single detection device under a common detection condition. The configuration can be simplified.

  In the embodiment of the present invention, the abnormality detection of the ink discharge surface of the ink jet head provided in the ink jet recording apparatus that forms a color image on the recording medium has been described as an example. However, the scope of the present invention is the ink jet recording apparatus. It is not limited to.

  For example, it is widely applied to pattern forming devices that form a predetermined pattern (mask pattern, wiring pattern) with functional liquid containing resin particles and metal particles, and liquid ejecting devices that eject liquid onto a medium by an ink jet method. Is possible.

  In the above-described embodiment, the abnormality detection of the ink discharge surface of the full-line type ink jet head has been described as an example. However, the present invention is a serial type in which nozzles are arranged over a flow less than the full width of the recording medium. It can also be applied to the head.

  Furthermore, it is possible to appropriately change, add, or delete the configuration requirements without departing from the spirit of the present invention.

[Appendix]
As will be understood from the description of the embodiments of the invention described in detail above, the present specification includes disclosure of various technical ideas including at least the following aspects.

  (First Aspect): The detection device according to the first aspect is disposed avoiding a position directly below the liquid ejection surface of the inkjet head, and an imaging unit that images the liquid ejection surface from an oblique direction with respect to the liquid ejection surface; Focus setting means for focusing the image pickup means on the liquid ejection surface, relative movement means for relatively moving the inkjet head and the image pickup means, and movement relative to the image pickup means by the relative movement means A focus target area setting unit that sets a focus target area in which a focus position on the liquid discharge surface is included in a region that can be imaged by the imaging unit on the liquid discharge surface; and the focus setting unit The operation of the imaging unit is performed so as to image the liquid ejection surface at predetermined time intervals while relatively moving the inkjet head and the imaging unit while maintaining the focus setting. Imaging control means for controlling, data processing means for performing predetermined processing on the imaging data obtained from the imaging means, and abnormal information on the liquid ejection surface from imaging data of the focusing target area processed by the data processing means And an abnormality information output means for outputting the abnormality information of the liquid ejection surface generated by the abnormality information generation means.

  According to the first aspect, when the imaging unit arranged to avoid an area directly below the liquid ejection surface of the ink jet head captures the liquid ejection surface from an oblique direction with respect to the liquid ejection surface, the imaging unit obtains the imaging unit. From the captured image data, an in-focus area, which is an area where an in-focus image is obtained, is set, and the inkjet head and the imaging means are moved relatively while maintaining the in-focus setting of the imaging means. Since the liquid ejection surface is imaged at a predetermined time interval, it is possible to capture an area on the liquid ejection surface where an image in focus of the imaging unit is obtained at a predetermined time interval. The imaging data over the entire surface of the liquid ejection surface can be acquired without changing.

  Further, since the imaging data of the focus target area is extracted and the abnormality of the liquid ejection surface is detected based on the imaging data, the liquid ejection surface and the imaging means for focusing on the entire imageable area of the imaging means It is not necessary to make precise adjustments to make them parallel to each other.

  Furthermore, since the image pickup means is disposed so as to avoid a position directly below the liquid discharge surface, contamination of the image pickup means by the liquid dripping from the liquid discharge surface is avoided.

  There exists an aspect in which an imaging means contains the image pick-up element which has a predetermined imaging possible range, and the optical system provided in the image pick-up target side of an image pick-up element. There is also an aspect in which a color filter is provided on the imaging target side of the imaging element.

  The position avoiding the position immediately below the liquid discharge surface means that the liquid discharge surface and the horizontal surface are formed when the edge of the liquid discharge surface is projected onto the horizontal plane, and the outside of the region surrounded by the surface that reaches the horizontal plane from the edge of the liquid discharge surface. It is.

  At least, the image pickup surface of the image pickup means may not be arranged at a position avoiding a position directly below the liquid discharge surface.

  (2nd aspect): The detection apparatus which concerns on a 2nd aspect is provided with the extraction means which extracts the imaging data of the said focusing object area | region from the imaging data continuously imaged by the said imaging means.

  According to such an aspect, since the imaging data of the in-focus area is extracted from the imaging data including the imaging data of the imaging area that is not in focus, based on the imaging data in focus, Abnormality of the liquid ejection surface is detected.

  (Third Aspect): The detection device according to the third aspect synthesizes the imaging data of the focus target area extracted by the extraction unit in time series to generate a composite image of the liquid ejection surface. Image generation means is provided.

  According to this aspect, it is possible to obtain an image in which a wider range of focus of the liquid ejection surface is in focus.

  (Fourth Aspect): In the detection device according to the fourth aspect, the composite image generating means uses a reference position provided on the liquid ejection surface as a reference to capture imaging data of the plurality of focus target areas in time series. They are synthesized in order.

  According to this aspect, when synthesizing the image of the focus target area, it is possible to avoid missing or overlapping images, and a preferable synthesized image is formed.

  The reference position may be an end portion (end side) of the liquid discharge surface or a marking formed on the liquid discharge surface. Furthermore, an arrangement of nozzles (nozzle openings) formed on the liquid ejection surface may be used.

  (5th aspect): The detection apparatus which concerns on a 5th aspect is provided with the extraction means which extracts the imaging data of the said focusing object area | region from the imaging data obtained by one imaging by the said imaging means.

  According to this aspect, it is possible to detect abnormality of the liquid ejection surface in units of imaging data obtained by one imaging.

  (Sixth aspect): In the detection device according to the sixth aspect, the abnormality information generation means includes a normal image of the liquid discharge surface stored in advance and a liquid discharge surface generated by the composite image generation means. The liquid discharge surface abnormality information is generated based on the comparison result obtained by comparing the first and second images.

  According to this aspect, normality and abnormality can be visually determined, and it is easy to determine whether there is an abnormality.

  (Seventh aspect): In the detection device according to the seventh aspect, the data processing unit generates a detection signal representing a data value of imaging data of the focus target region with respect to a position on the liquid ejection surface.

  According to this aspect, it is not necessary to generate an image from captured data, and the data processing load can be reduced.

  In such an aspect, there is an aspect in which the data values of the imaging data are synthesized in time series order to generate a detection signal that represents the relationship of the data values of the imaging data to the position of the liquid ejection surface in the relative movement direction.

  (Eighth aspect): In the detection device according to the eighth aspect, the abnormality information generation unit generates abnormality information of the liquid ejection surface based on a change in the pattern of the detection signal.

  According to this aspect, the abnormality of the liquid ejection surface can be detected based on the fluctuation of the data value of the imaging data.

  (Ninth aspect): A liquid ejection apparatus according to a ninth aspect relatively moves an inkjet head, a detection apparatus that detects an abnormality of a liquid ejection surface of the inkjet head, and the inkjet head and the detection apparatus. And a relative movement means, wherein the detection device is arranged avoiding a position directly below the liquid ejection surface of the inkjet head, and imaging means for imaging the liquid ejection surface from an oblique direction with respect to the liquid ejection surface; In-focus setting means for focusing the imaging means on the liquid ejection surface, and in the liquid ejection surface moved relative to the imaging means by the relative movement means, the liquid ejection in an imageable area of the imaging means A focus target area setting unit that sets a focus target area including a focus position on the surface; and maintaining the focus setting by the focus setting unit, An imaging control means for controlling the operation of the imaging means so as to take an image of the liquid ejection surface at predetermined time intervals while relatively moving the head and the imaging means, and imaging data obtained from the imaging means Data processing means for performing predetermined processing, abnormal information generation means for generating abnormality information of the liquid ejection surface from imaging data of the focus target area processed by the data processing means, and generation by the abnormality information generation means Abnormality information output means for outputting abnormality information of the liquid discharge surface.

  The liquid ejecting apparatus is an apparatus that applies a predetermined liquid (droplet) onto a medium by an ink jet method. As an example, an ink jet recording apparatus that forms a color image on a recording medium can be given.

  The inkjet head is provided with a full-line head having a nozzle group having a length corresponding to the entire width of the medium (the entire length of the medium in the direction orthogonal to the medium conveyance direction), and a plurality of nozzles along the medium conveyance direction. There is a serial type head.

  The relative moving means includes an aspect in which the imaging means is moved with respect to the fixed inkjet head, an aspect in which the inkjet head is moved with respect to the fixed imaging means, and an aspect in which both the imaging means and the inkjet head are moved.

  (Tenth aspect): In the liquid ejection apparatus according to the tenth aspect, the detection device has a detection surface arranged in an oblique direction with respect to a movement direction of the relative movement unit.

  In such an aspect, it is preferable that the direction in which the detection surface is directed and the direction in which the movement direction of the relative movement unit is projected in a direction parallel to the liquid ejection surface intersect.

  (11th aspect): The liquid discharge apparatus which concerns on an 11th aspect is provided with the wiping member which wipes the said liquid discharge surface, and the said detection apparatus is arrange | positioned in the position where the liquid scattered from the wiping member does not adhere.

  According to this aspect, it is possible to avoid contamination of the detection device with the liquid scattered from the wiping member.

  As an example of the wiping member in such an embodiment, there is a blade that wipes the liquid ejection surface by bringing it into contact with the liquid ejection surface while being elastically deformed. When the elastic deformation of the blade is released, the liquid wiped off from the liquid discharge surface may scatter, so that the detection device may be arranged avoiding the direction in which the blade returns from the elastic deformation state.

  This aspect is effective when the wiping member is disposed in front of the detection device.

  (Twelfth aspect): In the liquid ejection device according to the twelfth aspect, the detection device is arranged at a position where the liquid scattered by the liquid ejection of the inkjet head does not adhere.

  According to this aspect, it is possible to avoid contamination of the detection device with the liquid (mist liquid) scattered by the liquid ejection of the inkjet head.

  (Thirteenth aspect): The liquid ejection apparatus according to the thirteenth aspect sets the processing conditions of the maintenance means based on maintenance processing means for performing maintenance processing on the inkjet head and the abnormality information output from the detection device. Processing condition setting means for setting.

  According to this aspect, it is possible to execute the inkjet head maintenance process in accordance with the presence / absence of abnormality of the liquid ejection surface (presence / absence of dirt).

  (Fourteenth aspect): In the liquid ejection device according to the fourteenth aspect, the relative movement means includes the inkjet head and the detection device between the liquid ejection position of the inkjet head and a maintenance processing position by the maintenance means. The detection device detects an abnormality of the liquid ejection surface of the inkjet head before or after the maintenance process.

  According to this aspect, by detecting the liquid ejection surface before the maintenance process, the state of the liquid ejection surface can be reflected in the maintenance process. Further, by detecting the liquid discharge surface after the maintenance process, it can be determined whether or not the maintenance of the liquid discharge surface has been appropriately performed.

  Further, when the inkjet head, which is a heavy object, moves to the maintenance processing position at a constant speed, it is possible to acquire imaging data over the entire liquid ejection surface without stopping.

  (Fifteenth aspect): The liquid ejection apparatus according to the fifteenth aspect includes a plurality of the inkjet heads, and includes a smaller number of the detection devices than the number of the inkjet heads.

  According to this aspect, in a device including a plurality of inkjet heads, the configuration for detecting the liquid ejection surfaces can be reduced in size by detecting the liquid ejection surfaces of all the inkjet heads with fewer detection devices. This can contribute to the simplification of the device configuration.

  The image pickup means in this aspect is preferably an aspect having a telephoto macro optical system.

  (Sixteenth aspect): The liquid discharge apparatus according to the sixteenth aspect has a cylindrical shape, supports a medium that receives the liquid discharged from the inkjet head on an outer peripheral surface, and uses the central axis of the cylindrical shape as a rotation axis. A plurality of inkjet heads disposed at positions facing the outer peripheral surface of the medium transport unit; and the relative movement unit includes: a medium transport unit configured to rotate and transport the medium along the outer peripheral surface; A plurality of inkjet heads are collectively moved relative to the detection device.

  In this aspect, since the liquid discharge surface of each inkjet head is inclined toward the outer peripheral surface of the medium transport unit, the line extends from the rotation axis (center axis) of the medium transport unit in a direction perpendicular to the horizontal plane. There is a mode in which imaging means is arranged.

  (Seventeenth aspect): In the liquid ejection apparatus according to the seventeenth aspect, the inkjet head is a full-line head, and the relative movement means is substantially parallel to the longitudinal direction of the inkjet head and the detection. The device is moved relatively.

  In such an aspect, the imaging region in one imaging operation of the imaging unit corresponds to the overall length in the short direction of the inkjet head (liquid ejection surface), so that the inkjet head and the detection device can extend over the entire length in the longitudinal direction of the inkjet head. By relatively moving only once, the entire surface of the liquid ejection surface can be imaged.

  (18th aspect): In the liquid ejection apparatus according to the 18th aspect, the detection device includes the detection device according to any one of the second aspect to the eighth aspect.

  (Nineteenth aspect): The liquid discharge surface abnormality detection method according to the nineteenth aspect is arranged avoiding a position directly below the liquid discharge surface of the inkjet head, and images the liquid discharge surface from an oblique direction with respect to the liquid discharge surface. In the liquid discharge surface abnormality detection method, the image pickup unit and the inkjet head are moved relatively to image the liquid discharge surface, and the abnormality of the liquid discharge surface is detected based on the imaging result. An in-focus position on the liquid ejection surface is included in a focus setting step for focusing the liquid ejection surface on the liquid ejection surface, and an imageable area of the imaging unit on the liquid ejection surface that is moved relative to the imaging unit A focusing target area setting step for setting a focusing target area to be set, and while moving the inkjet head and the imaging means relative to each other while maintaining the focusing setting of the imaging means. From an imaging process for imaging the liquid ejection surface at time intervals, a data processing process for performing predetermined processing on the imaging data obtained by the imaging process, and imaging data of the focusing target area processed by the data processing process An abnormality information generation step for generating abnormality information on the liquid ejection surface; and an abnormality information output step for outputting abnormality information on the liquid ejection surface generated by the abnormality information generation step.

  In such an aspect, an aspect including an extraction step of extracting imaging data of the focusing target area from imaging data continuously captured by the imaging process, or combining imaging data of the focusing target area extracted by the extraction process in time series And the aspect containing the synthetic image generation process which produces | generates the synthetic image of a liquid discharge surface is preferable.

  In the composite image generation process, it is preferable that the imaging data of the plurality of focus target areas be combined in time series with reference to a reference position provided on the liquid ejection surface.

  Furthermore, an aspect including extraction for extracting imaging data of a focusing target region from imaging data obtained by one imaging by the imaging process is also preferable.

  In such an aspect, the abnormality information generation step includes a comparison result obtained by comparing a normal image of the liquid discharge surface stored in advance with an image of the liquid discharge surface generated from the imaging data obtained by the imaging unit. A mode in which abnormal information on the liquid ejection surface is generated based on the above is also preferable.

  Further, the data processing step generates a detection signal that represents the data value of the imaging data of the in-focus target region with respect to the position on the liquid discharge surface. In the abnormality information generation step, based on the change in the pattern of the detection signal, A mode of generating abnormality information is also preferable.

  In addition, an ink jet head maintenance method in which the processing conditions are set based on the liquid discharge surface abnormality information is also preferable, including the liquid discharge surface abnormality detection method according to the twentieth aspect.

  DESCRIPTION OF SYMBOLS 10,300 ... Inkjet recording apparatus, 16, 16K, 16C, 16M, 16Y, 316, 316K, 316C, 316M, 316Y ... Inkjet head, 16A, 316A ... Ink ejection surface, 60 ... Maintenance processing part, 66 ... Blade, 68 ... wiping processing unit, 70 ... detection device, 71A ... focusing target surface, 72B, 202 ... focusing target position 102 ... system control unit, 126 ... maintenance control unit, 128 ... abnormality detection unit, 140 ... imaging unit, 142 ... Control unit, 144 ... imaging condition setting unit, 146 ... data processing unit, 150 ... information output unit, 176 ... digital signal processing unit, 200 ... focus target area, 201 ... imageable area

Claims (19)

An imaging unit that is arranged avoiding a position directly below the liquid ejection surface of the inkjet head, and that images the liquid ejection surface from an oblique direction with respect to the liquid ejection surface;
Focusing setting means for focusing the imaging means on the liquid ejection surface;
Relative movement means for relatively moving the inkjet head and the imaging means;
An in-focus target region that includes a focus position on the liquid ejection surface in a region that can be imaged by the imaging unit on the liquid ejection surface that is moved relative to the imaging unit by the relative movement unit. A focus target area setting means;
While maintaining the focus setting by the focus setting means, the image pickup means operates to image the liquid ejection surface at predetermined time intervals while relatively moving the inkjet head and the image pickup means. Imaging control means for controlling;
Data processing means for performing predetermined processing on the imaging data obtained from the imaging means;
Abnormality information generating means for generating abnormality information of the liquid ejection surface from the imaging data of the focus target area processed by the data processing means;
Abnormality information output means for outputting abnormality information of the liquid ejection surface generated by the abnormality information generation means;
A detection device comprising:   The detection apparatus according to claim 1, further comprising an extraction unit that extracts imaging data of the focus target region from imaging data continuously captured by the imaging unit.   The detection apparatus according to claim 2, further comprising: a composite image generation unit configured to combine the imaging data of the focus target area extracted by the extraction unit in time series to generate a composite image of the liquid ejection surface.   The detection apparatus according to claim 3, wherein the synthesized image generation unit synthesizes the imaging data of the plurality of focus target regions in time series with reference to a reference position provided on the liquid ejection surface.   The detection apparatus according to claim 1, further comprising an extraction unit that extracts imaging data of the focusing target region from imaging data obtained by one imaging by the imaging unit.   The abnormality information generation unit is based on a comparison result obtained by comparing a normal image of the liquid discharge surface stored in advance with an image of the liquid discharge surface generated from imaging data obtained by the imaging unit. The detection device according to claim 3, wherein abnormality information of the liquid ejection surface is generated.   The detection device according to claim 1, wherein the data processing unit generates a detection signal representing a data value of imaging data of the focus target region with respect to a position on the liquid ejection surface.   The detection apparatus according to claim 7, wherein the abnormality information generation unit generates abnormality information of the liquid ejection surface based on a change in a pattern of the detection signal. An inkjet head;
A detection device for detecting an abnormality of the liquid ejection surface of the inkjet head;
Relative movement means for relatively moving the inkjet head and the detection device;
With
The detection device is arranged avoiding a position directly below the liquid ejection surface of the inkjet head, and an imaging unit that images the liquid ejection surface from an oblique direction with respect to the liquid ejection surface;
Focusing setting means for focusing the imaging means on the liquid ejection surface;
An in-focus target region that includes a focus position on the liquid ejection surface in a region that can be imaged by the imaging unit on the liquid ejection surface that is moved relative to the imaging unit by the relative movement unit. A focus target area setting means;
While maintaining the focus setting by the focus setting means, the image pickup means operates to image the liquid ejection surface at predetermined time intervals while relatively moving the inkjet head and the image pickup means. Imaging control means for controlling;
Data processing means for performing predetermined processing on the imaging data obtained from the imaging means;
Abnormality information generating means for generating abnormality information of the liquid ejection surface from the imaging data of the focus target area processed by the data processing means;
Abnormality information output means for outputting abnormality information of the liquid ejection surface generated by the abnormality information generation means;
A liquid ejection apparatus comprising:   The liquid ejection device according to claim 9, wherein the detection device is arranged such that a detection surface is inclined with respect to a movement direction of the relative movement unit. A wiping member for wiping the liquid ejection surface;
The liquid ejecting apparatus according to claim 9, wherein the detection device is disposed at a position where the liquid scattered from the wiping member does not adhere.   12. The liquid ejection device according to claim 9, wherein the detection device is arranged at a position where liquid scattered by liquid ejection of the inkjet head does not adhere. Maintenance processing means for performing maintenance processing on the inkjet head;
Processing condition setting means for setting a processing condition of the maintenance means based on the abnormality information output from the detection device;
The liquid ejection apparatus according to claim 9, further comprising: The relative movement means relatively moves the inkjet head and the detection device between a liquid discharge position of the inkjet head and a maintenance processing position by the maintenance means,
14. The liquid ejection device according to claim 9, wherein the detection device detects an abnormality of the liquid ejection surface of the inkjet head before or after maintenance processing.   The liquid ejecting apparatus according to claim 9, further comprising a plurality of the ink jet heads and the number of the detection devices smaller than the number of the ink jet heads. A medium that has a cylindrical shape, supports a medium that receives liquid ejected from the inkjet head on an outer peripheral surface, rotates the central axis of the cylindrical shape as a rotation axis, and conveys the medium along the outer peripheral surface A transport means,
The plurality of inkjet heads are arranged at positions facing the outer peripheral surface of the medium transport unit,
The liquid ejecting apparatus according to claim 9, wherein the relative movement unit moves the plurality of inkjet heads relative to the detection apparatus at once. The inkjet head is a full line type head,
17. The liquid ejection apparatus according to claim 9, wherein the relative movement unit relatively moves the inkjet head and the detection device substantially parallel to a longitudinal direction of the inkjet head.   The liquid ejection device according to any one of claims 9 to 17, wherein the detection device includes the detection device according to any one of claims 2 to 8. The liquid discharge surface is disposed by avoiding a position directly below the liquid discharge surface of the ink jet head and relatively moving the image pickup means for picking up the image of the liquid discharge surface from an oblique direction relative to the liquid discharge surface In the liquid discharge surface abnormality detection method for detecting an abnormality of the liquid discharge surface based on the imaging result,
A focus setting step for focusing the imaging means on the liquid ejection surface;
A focus target area setting step of setting a focus target area including a focus position on the liquid discharge surface in a region where the image pickup means can capture an image on the liquid discharge surface moved relative to the image pickup means; ,
An imaging step of imaging the liquid ejection surface at predetermined time intervals while relatively moving the inkjet head and the imaging unit while maintaining the focus setting of the imaging unit;
A data processing step of performing predetermined processing on the imaging data obtained by the imaging step;
An abnormality information generation step of generating abnormality information of the liquid ejection surface from the imaging data of the focus target region processed by the data processing step;
An abnormality information output step of outputting abnormality information of the liquid ejection surface generated by the abnormality information generation step;
An abnormality detection method for a liquid ejection surface including

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