JP2013071292A - Liquid droplet discharge device and maintenance method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid droplet discharge device for securely inspecting a liquid discharge face and a method for maintaining a detection device.SOLUTION: The liquid droplet discharge device includes: an ink jet head 16 having a liquid discharge face with openings of a plurality of nozzles formed thereon; the detection device 70 detecting an abnormality of the liquid discharge face of the ink jet head 16; and a moving means relatively displacing the ink jet head 16 and the detection device. The detection device 70 includes: an imaging means 154 imaging the liquid discharge face; an opening/closing member 150 which is openably/closably interposed between the imaging means 154 and the liquid discharge face 16A; and a reference plate 152 for obtaining a predetermined light receiving amount during imaging by the imaging means 154. The invention also relates to a maintenance method of the detection device 70.

Description

  The present invention relates to a droplet discharge device and a maintenance method of a detection device, and more particularly, to a droplet discharge device that inspects dirt on an image pickup unit that inspects an inkjet head, and a maintenance method of a detection device.

  2. Related Art Inkjet image forming apparatuses are known that eject liquid ink as droplets and record an image on a recording medium. In such an image forming apparatus, if dirt such as liquid ink or solidified ink adheres to the vicinity of the discharge port of the ink discharge surface, the discharge amount decreases, the trajectory of the discharged ink shifts, and the dot size is abnormal. Doing so may cause an abnormality in the dot formation position.

  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.

  For example, the following Patent Document 1 includes a CCD as an ejection surface imaging unit, recognizes dirt adhering to the droplet ejection surface based on image information captured by the ejection surface imaging unit, and controls the ejection surface cleaning unit. A droplet discharge device that cleans the droplet discharge surface is described.

JP 2008-12880 A

  However, when the droplet discharge surface is imaged using the discharge surface imaging unit as described in Patent Document 1, the ink falls from the nozzle formed on the droplet discharge surface, and the discharge surface imaging unit It may be dirty. In Patent Document 1, a cover member that covers the lens of the CCD is provided to prevent the lens from becoming dirty. However, if the lens is dirty, the droplet discharge surface is not dirty, but the captured image is not stained. Since there is dirt, it can be considered that the droplet discharge surface is judged to be dirty. In Patent Document 1, the CCD lens is prevented from being soiled, but the case where the CCD lens is soiled is not taken into consideration.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a droplet discharge device capable of more accurately inspecting a liquid discharge surface and a maintenance method for a detection device.

  In order to achieve the above object, the present invention provides an inkjet head having a liquid ejection surface in which openings of a plurality of nozzles are formed, a detection device for detecting an abnormality in the liquid ejection surface of the inkjet head, and the inkjet head And a moving means for relatively moving the detection device, wherein the detection device separates an image pickup means for picking up an image of the liquid discharge surface and the image pickup means and the liquid discharge surface so as to be freely opened and closed. There is provided a droplet discharge device comprising an opening / closing member and a reference plate that obtains a predetermined amount of received light when imaged by the imaging means.

  According to the present invention, the detection device that detects an abnormality of the liquid ejection surface of the ink jet head is provided, and the imaging means provided in the detection device is separated by an openable and closable opening / closing member. When the imaging unit is not used to image the liquid ejection surface, the detection device is closed by the opening / closing member, and when the liquid ejection surface is imaged, the ink droplet is imaged from the liquid ejection surface by opening the opening / closing member. Can be reduced to fall.

  In addition, the reference plate is provided, and the received light amount obtained from the reference plate by the imaging unit in the initial state before imaging the liquid ejection surface and the reference plate by the imaging unit after being used for the inspection of the liquid ejection surface for a certain period of time. By comparing the amount of received light obtained by imaging, the contamination of the imaging means can be confirmed. Therefore, the abnormality of the liquid ejection surface can be confirmed more reliably by the imaging means without contamination.

  In the droplet discharge device according to another aspect of the present invention, it is preferable that the reference plate is formed of a member in which the amount of light received from the reference plate is equal to the amount of light received from the liquid discharge surface.

  According to the present invention, the amount of light received from the reference plate is made equal to the amount of light received from the liquid ejection surface. Therefore, if the imaging means is normal, when the reference plate is imaged, it is equivalent to the liquid ejection surface. Since the amount of received light can be set, it is possible to easily determine the performance of the imaging means.

  In the droplet discharge device according to another aspect of the present invention, it is preferable that the reference plate is provided on a side opposite to the discharge surface of the opening / closing member.

  According to the present invention, since the reference plate is provided on the side opposite to the discharge surface of the opening and closing member, it is possible to prevent the reference plate from becoming dirty, and by checking the imaging of the reference plate, it is possible to confirm an abnormality of the imaging member. be able to.

  In the droplet discharge device according to another aspect of the present invention, it is preferable that a cleaning member is provided on the image pickup means side of the opening / closing member.

  According to the present invention, by providing the opening / closing member with the cleaning member on the imaging means side, the imaging member can be cleaned when the opening / closing member is opened / closed.

  In the liquid droplet ejection apparatus according to another aspect of the present invention, it is preferable that the liquid ejected from the inkjet head is an ultraviolet curable ink, and the opening / closing member is made of a UV cut material.

  According to the present invention, even if ultraviolet curable ink is attached to the image pickup means, the opening / closing member is made of a UV cut material, so that it is possible to prevent the ink from being solidified by the ultraviolet rays used for fixing the image. Therefore, the attached ink can be easily cleaned.

  In the droplet discharge device according to another aspect of the present invention, it is preferable that the imaging unit includes a protective member having transparency.

  According to the present invention, by providing the imaging member with a permeable protective member, the liquid dropped from the liquid ejection surface can be protected by the protective member, and the imaging unit can be prevented from becoming dirty. Also, if the protective member is dirty, the liquid ejection surface cannot be observed accurately, but can be easily returned to the initial state by replacing the protective member.

  In the droplet discharge device according to another aspect of the present invention, the protective member is preferably made of a UV cut material.

  According to the present invention, since the protective member is made of a UV cut material, it is possible to prevent the ink on the liquid ejection surface from being solidified by irradiating ultraviolet rays from the light emitting element used together with the imaging unit.

  In order to achieve the above object, the present invention detects the abnormality of the liquid ejection surface of the ink jet head, and the reference light receiving amount measuring step of measuring the reference light receiving amount by imaging the reference plate using the imaging means in the initial state. A detection step, an imaging unit after the detection step is used to image the reference plate, and a received light amount measurement step for measuring a received light amount; a received light amount in the reference received light amount measurement step; and a received light amount measurement step There is provided a maintenance method for a detection apparatus, comprising: an imaging unit abnormal state determination step of comparing an amount of received light and determining an abnormal state of the imaging unit.

  According to the present invention, the received light amount obtained from the reference plate imaged using the imaging means after the detection process is compared with the received light amount obtained from the reference plate imaged using the imaging means before use. The abnormal state of the imaging means can be determined. Therefore, it is possible to use an image pickup means that is free from dirt, and it is possible to confirm abnormality of the liquid ejection surface with certainty.

  In the maintenance method for a detection apparatus according to another aspect of the present invention, it is preferable that the amount of received light obtained from the reference plate is equal to the amount of received light obtained from the droplet discharge surface.

  According to the present invention, since the reference plate is formed so as to have the same amount of received light as the droplet discharge surface of the ink jet head, it can be easily determined when the imaging means is dirty.

  In the maintenance method for a detection apparatus according to another aspect of the present invention, it is preferable that the reference plate is formed of a member that can obtain a constant amount of received light in an initial state.

  According to the present invention, since the reference plate is formed of a member capable of obtaining a constant light reception amount in the initial state, the light reception amount of the reference plate obtained by using the imaging member in the initial state is compared. Thus, it is possible to easily determine the contamination of the imaging means.

  According to the maintenance method for a detection apparatus according to another aspect of the present invention, it is preferable that the imaging unit is cleaned or replaced based on a result of the imaging unit abnormal state determination step.

  According to the present invention, since the contamination of the imaging unit can be confirmed by the imaging unit abnormal state determination step, the imaging unit can be cleaned or replaced according to the result of the imaging unit abnormal state determination step.

  According to the maintenance method for a detection apparatus according to another aspect of the present invention, it is preferable that a protection member for protecting the imaging unit is provided, and the protection member is replaced according to a result of the imaging unit abnormal state determination step.

  According to the present invention, since the protection member for protecting the imaging unit is provided and the protection member is replaced according to the result of the abnormal state determination step, it can be returned to the initial state more easily than the replacement of the imaging unit itself. .

  According to the droplet ejection device and the maintenance method of the detection device of the present invention, the inkjet head is reliably inspected by the imaging device without contamination by checking and cleaning the imaging device for observing the inkjet head. be able to.

1 is an overall configuration diagram showing a schematic configuration of an ink jet recording apparatus according to an embodiment of the present invention. FIG. 2 is a perspective plan view showing a structural example of the inkjet head shown in FIG. 1. It is a schematic block diagram of the maintenance process part of the inkjet recording device shown in FIG. It is a block diagram which shows schematic structure of the detection apparatus shown in FIG. FIG. 2 is a block diagram illustrating a schematic configuration of a control system of the ink jet recording apparatus illustrated in FIG. 1. It is a schematic block diagram of the detection apparatus which concerns on 1st Embodiment. It is a figure explaining the state which observes an ink discharge surface. It is a modification of the detection apparatus which concerns on 1st Embodiment. It is a schematic block diagram of the detection apparatus which concerns on 2nd Embodiment. It is a flowchart which shows the maintenance method of a detection apparatus.

  Hereinafter, preferred embodiments of the present invention will be described 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 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 ejected from the ejection unit 32 after the recorded image (test pattern) is read by the reading device 38.

  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 inkjet head 16, various ejection methods such as a piezoelectric method that utilizes the bending deformation of a piezoelectric element and a thermal method that utilizes a 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 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 corresponding to 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 for performing wiping processing on the ink discharge surface 16A of the inkjet head 16 after purge processing or suction processing, and an abnormality in the ink discharge surface 16A of the ink jet head 16 after wiping processing are detected. And a detecting device 70 that performs the above operation.

  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.

  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. While the ink jet head 16 moves from the processing position of the cap portion 64 to the image forming position, the wiping processing of the ink discharge surface 16A is performed by the blade 66 of the wiping processing portion 68.

  After the wiping processing by the wiping processing unit 68, the detection device 70 detects abnormality of the ink ejection surface 16A. Details of the abnormality detection of the ink discharge surface 16A by the detection device 70 will be described later.

[Configuration of detection device]
FIG. 4 is a configuration diagram illustrating a schematic configuration of the detection device 70 illustrated in FIG. 3, and schematically illustrates abnormality detection of the ink ejection surface 16 </ b> A illustrated in the present example. A detection device 70 shown in FIG. 4 includes a sensor 80 in which a plurality of detection elements are two-dimensionally arranged, and a light emitting element (LED) 82 that functions as an illumination unit.

  The light receiving surface of the sensor 80 and the light emitting surface of the light emitting element 82 are disposed at positions facing the ink ejection surface 16A of the inkjet head 16 that is moved from the processing position of the cap portion 64 (see FIG. 3) to the image forming position.

  When illumination light is irradiated from the light emitting element 82 to the ink ejection surface 16A, the sensor 80 receives reflected light reflected by the ink ejection surface 16A, and a voltage proportional to the amount of received light is output from the sensor 80. From the voltage signal obtained by the sensor 80, a detection signal for the ink ejection surface 16A is generated.

  The waveform of the detection signal at normal time (the peak value, the time width, etc.) and the waveform of the detection signal generated sequentially are compared, and an abnormality in the ink ejection surface 16A can be detected as a waveform abnormality in a circuit form.

[Explanation of control system]
FIG. 5 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 and a ROM 112.

  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 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. The head drive unit 108 shown in FIG. 5 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. 5 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 signal 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 a command signal for executing the maintenance process of the inkjet head 16 is sent to the maintenance control unit 126. In the maintenance processing unit 60, maintenance processing of the inkjet head 16 is executed.

  In addition, the abnormality detection unit 128 also determines whether there is an abnormality in the detection device 70. As will be described later, a storage unit is provided that stores the amount of light received when the amount of light received before using the detection device 70 is measured using a reference plate. In addition, the storage unit stores the received light amount when the received light amount is measured using the reference plate by the detection device 70 after the detection process for detecting the abnormality of the ejection surface 16A. These data are sent to the determination unit, and when the difference is greater than or equal to a predetermined numerical value due to the difference in the amount of received light, it is determined that the inspection apparatus is abnormal.

[Configuration of detection device]
[First Embodiment]
FIG. 6 is a diagram showing a nozzle plate detection device 70. As shown in FIG. 6, the detection device 70 includes a sensor unit 154 that includes a sensor 80 that monitors the ink discharge surface 16 </ b> A of the inkjet head 16 and a light emitting element (such as an LED) 82 that functions as an illumination unit. Yes. Further, a shutter 150 that protects the sensor 80 and the light emitting element 82 when not in use is provided. By providing the shutter 150, it is possible to prevent ink attached to the ink ejection surface 16A from attaching to the sensor 80 and the light emitting element 82 when the detection device 70 is not used. It is also possible to use a dustproof door instead of the shutter 150.

  Further, as shown in FIG. 6, a reference plate 152 is provided on the back side of the shutter 150 in the sensor unit 154. The reference plate 152 is used for inspecting the sensor 80 for dirt. When the reference plate 152 is monitored using the sensor 80, a plate is used that can obtain the same amount of received light as when the ink ejection surface 16A is monitored. By monitoring the reference plate 152 using the sensor 80, if the received light amount equivalent to the initial value can be confirmed, the sensor 80 is not dirty, and if the received light amount is reduced, the sensor 80 is dirty. Can be confirmed.

  The position of the reference plate 152 is provided on the sensor unit 154 side, which is the opposite side of the shutter 150 from the ink ejection surface 16A in FIG. By providing the shutter 150 on the sensor unit 154 side, it is possible to prevent the reference plate 152 from becoming dirty even when ink drops from the ink discharge surface. By preventing the reference plate 152 from contamination, the reference plate can be monitored and compared with the initial amount of received light to check the contamination of the sensor 80. In addition, instead of the reference plate 152, processing can be performed so as to have the same effect as when the reference plate is provided on the sensor unit 154 side of the shutter 150. Examples of such treatment include gloss treatment, mirror finish treatment, and resin coating treatment.

  The reference plate 152 is preferably made of a material that is equivalent to the amount of light received in the initial state where the ink ejection surface 16A is not soiled. Further, the color of the reference plate 152 is preferably a color that is not used in ink, and more preferably white. If the color used in the ink is used, it is not preferable because it cannot be confirmed even if dirt is attached to the image pickup means. Further, by setting the color to white, it is possible to facilitate imaging by light emission by the light emitting element.

  In addition, as shown in FIG. 6, it is preferable to provide a cleaning member 156 on the sensor unit 154 side of the shutter 150. As the cleaning member 156, a rubber wiper or a brush can be used. By providing the cleaning member 156 on the sensor unit 154 side of the shutter 150, the sensor 80 can be cleaned when the shutter 150 is opened and closed.

  FIG. 7 is a diagram when the shutter 150 is opened and the ink ejection surface 16A is observed. As shown in FIG. 7, when observing the ink ejection surface 16A, the shutter 150 is opened and monitored by the sensor 80 and the light emitting element 82, and the contamination of the ink ejection surface 16A is observed. When the shutter 150 is opened, the sensor unit 154 can be cleaned by the cleaning member 156 provided on the sensor unit 154 side of the shutter 150 as described above.

  In the present embodiment, the ink to be used is not particularly limited. For example, a UV curable ink can be used. The UV curable ink contains a UV curable monomer in the ink, and the UV curable monomer is cured and polymerized by irradiating the image with UV at a fixing unit equipped with a UV irradiation lamp, thereby improving the image strength. Can be improved.

  When such UV curable ink is used, it is conceivable that the ink is solidified around the sensor unit 154 when the ultraviolet rays are irradiated after the ink has adhered around the sensor unit 154. When the ink is solidified, it is difficult to remove the ink, and thus the detection device 70 needs to be replaced. In order to prevent this, the member surrounding the sensor unit 154 and the shutter 150 are preferably formed of a UV cut material. In this way, even if ink adheres to the sensor unit 154, it is not necessary to replace the sensor by wiping the ink. The UV cut material may be any member that does not transmit light including UV light, and metal, colored resin, or the like can be used. When it is desired to form a skeleton using a transparent member, a commercially available ultraviolet absorption filter or SC filter for cameras, for example, a Fujifilm SC filter using a TAC support, can be used at low cost. Further, for example, a filter as disclosed in JP-A-11-248932 can be used. Further, when the detection device 70 is formed integrally with the cleaning device 62, the wiping processing unit 68, etc., UV does not enter from the side surface of the detection device 70, so only the shutter 150 is used as the UV cut material. By doing so, it is possible to prevent the ink containing the UV component from being irradiated from another device and the ink adhering to the sensor 80 from being solidified.

  Further, instead of the reference plate 152, another plate that can obtain a constant amount of light in the initial state of the sensor 80 is used, this plate is measured, and the received light level is recorded. And by measuring this plate regularly, the contamination of the sensor 80 can be confirmed by the change of the light quantity. The reference plate 152 described above has a light reception amount equivalent to that of the ink ejection surface 16A. However, in another plate, there is no particular limitation, and contamination of the sensor 80 is confirmed by comparison with the initial light reception amount. can do. As such another plate, a resin material that has been subjected to the same coating treatment as the head nozzle surface can be used.

  FIG. 8 is a diagram illustrating a modification of the detection device according to the first embodiment. The detection device 70 ′ shown in FIG. 8 is different from the detection device shown in FIG. 6 in that a protective member 158 is provided on the sensor 80 and the light emitting element 82 of the sensor unit 154.

  By providing the protection member 158, the sensor 80 can be protected by the protection member 158 even if an ink droplet falls from the ink ejection surface 16A. Therefore, it is possible to prevent the sensor 80 from becoming dirty. In addition, when the protective member 158 is dirty and the discharge surface cannot be sufficiently observed, the protection member 158 can be replaced to return to the initial state, so that the sensor 80 and the light emitting element 82 are replaced. This can be done more easily than When the protective member 158 is provided, the protective member 158 is cleaned by the cleaning member 156.

  The protective member 158 preferably has transparency because the ink discharge surface 16A is imaged through the protective member 158. Further, as the protective member 158, it is preferable to use a UV cut material. As such a material, for example, a commercially available ultraviolet absorbing filter or SC filter for a camera, for example, a Fujifilm SC filter using a TAC support can be used at low cost. Further, for example, a filter as disclosed in JP-A-11-248932 can be used. Further, on the protective member 158, a UV cut material can be partially provided, or a portion where a fluorescent dye or the like is attached to the UV cut material on the side opposite to the sensor unit can be provided. According to this configuration, the UV light component from the outside can be obtained by comparing the place where the UV-cut material is present and the place where the UV-cut material is present, and comparing the place where the fluorescent material is present and the place where the fluorescent material is not present on the UV-cut material. Therefore, it is possible to know whether or not the environment for replacing the protective member is appropriate so that the ink adhering to the sensor unit is not cured when the protective member is replaced. . Here, the portion where the UV cut material is not provided on the protective member may not be provided at all, or may be provided in a very small part outside the area where the nozzle surface is imaged, and the UV light is filtered on the UV cut material. The fluorescent material that can be changed to light that can transmit light may be provided in a very small portion outside the area where the nozzle surface is imaged. Furthermore, it is preferable to image the nozzle surface using a light source with a filter that cuts unnecessary UV light components. When a nozzle surface is imaged, if UV curable ink is used when the nozzle surface is irradiated with light containing a UV component, the ink is solidified on the nozzle surface, and therefore an image is captured using a light source that does not include the UV component. It is preferable to do.

[Second Embodiment]
FIG. 9 is a view showing the imaging means of the nozzle plate according to the second embodiment. 9A is a configuration diagram when the sensor 280 of the detection device 270 is not used, and FIG. 9B is a configuration diagram when the ink ejection surface 16A is monitored by the detection device 270. As shown in FIG. 9, the second embodiment is different from the first embodiment in that the sensor unit 354 is rotatable.

  As shown in FIG. 9, in the detection device 270 shown in the second embodiment, the sensor unit 354 rotates 180 ° while the inkjet head is not moving, for example, during drawing, maintenance, and standby, It faces away from the surface through which the inkjet head 16 passes. Thereby, it can prevent reliably that a dirt adheres to a sensor.

  The reference plate 352 is preferably provided at a position where the sensor unit 354 is rotated. In FIG. 9, the reference plate 352 is opposite to the shutter 350 with the sensor unit 354 in the detection device 270 interposed therebetween, that is, not used. A reference plate 352 is provided at a position that is sometimes rotating. If the reference plate 352 is provided at a position where the sensor unit 354 is rotated, and if the reference plate 352 is monitored while the ink jet head is not moving, an amount of light equivalent to the initial light receiving level can be obtained. If the sensor 80 is not contaminated and the light quantity is reduced, it can be confirmed that the sensor 80 is dirty.

  When monitoring the ink discharge surface 16A, the sensor unit 354 is rotated 180 ° as shown in FIG. 9B. Then, by opening the shutter 350, the ink discharge surface 16A can be monitored.

  As a method of rotating the sensor unit 354, a conventionally known method can be used.

  In the second embodiment, the cleaning member 356 is preferably provided during the rotation of the sensor unit 354, as shown in FIG. By providing the sensor unit 354 during the rotation, the sensor unit 354 can be cleaned using the rotation, and the cleaning can be performed efficiently.

  In addition, although FIG. 9 demonstrated the case where the sensor unit 354 rotated 180 degrees, in this embodiment, it is not limited to this, It can be set as another angle. The standard plate can be used at any angle, but it is preferable that the standard plate is provided at a position where the sensor unit is stopped. By providing the standard plate at the position where the sensor unit is stopped, the contamination of the sensor can be confirmed while the ink jet head is not moving.

  Although not shown, in the second embodiment, similarly to the first embodiment, a protective member for protecting the sensor 80 and the light emitting element 82 of the sensor unit 354 can be provided. As with the first embodiment, the reference plate 352 can be checked for contamination of the sensor 80 using another plate.

[Maintenance method of detection device]
FIG. 10 is a flowchart illustrating a maintenance method for the detection apparatus.

  In order to measure the amount of received light in the initial state of the sensor 80 of the detection device 70, such as disclosure of use of the sensor 80, the reference plate is imaged and the amount of received light serving as a reference is measured (reference received light amount measurement step, step S10). At the end of the maintenance of the ink discharge surface 16A of the inkjet head 16, a detection process for detecting an abnormality in the ink discharge surface 16A is performed (step S12). After the detection process is completed, in order to check the contamination of the sensor 80, the received light quantity is measured using the sensor 80 after the detection process using the reference plate 152 used in the reference received light quantity measurement process (received light quantity measurement process, step S14). ). In the detection process, since the image is picked up by the sensor 80 from below the ink ejection surface 16A, the ink may drop on the sensor 80 and the sensor 80 may become dirty.

  The received light amount obtained in the reference received light amount measuring step is compared with the received light amount obtained in the received light amount measuring step (imaging means abnormal state determining step, step S16). The received light amount obtained in the reference received light amount measurement step is compared with the received light amount obtained in the received light amount measurement step. If there is no problem, it is determined that there is no abnormality (N determination), and the sensor 80 is contaminated. The maintenance of the detection device ends. If there is a difference in the amount of received light, it is determined that there is an abnormality (Y determination) (step S18), and after the sensor 80 has been cleaned or replaced (step S20), the maintenance ends. In FIG. 10, the received light amount measurement step is performed after the detection step of detecting abnormality of the ink ejection surface. However, when the maintenance of the detection device is not performed at the last use, the drawing is performed by the inkjet head. It is also possible to determine a sensor abnormality by performing a received light amount measuring step before performing.

  DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device 16, 16K, 16C, 16M, 16Y ... Inkjet head, 16A ... Ink ejection surface, 60 ... Maintenance processing part, 62 ... Cleaning apparatus, 64 ... Cap part, 66 ... Blade, 68 ... Wiping process part , 70, 270 ... detection device, 80, 280 ... sensor, 82 ... light emitting element (LED), 126 ... maintenance control unit, 128 ... abnormality detection unit, 150 ... shutter, 152, 352 ... reference plate, 154, 354 ... sensor Unit, 156, 356 ... cleaning member, 158 ... protective member,

Claims (12)

An inkjet head having a liquid ejection surface in which openings of a plurality of nozzles are formed;
A detection device for detecting an abnormality of the liquid ejection surface of the inkjet head;
Moving means for relatively moving the inkjet head and the detection device;
The detection device obtains a predetermined amount of received light when imaged by the imaging unit, an imaging unit that images the liquid ejection surface, an opening / closing member that opens and closes the imaging unit and the liquid ejection surface, and an imaging unit. A liquid droplet ejecting apparatus comprising: a reference plate;   2. The droplet discharge device according to claim 1, wherein the reference plate is formed of a member having a light reception amount obtained from the reference plate equal to a light reception amount obtained from the liquid discharge surface.   The liquid droplet ejection apparatus according to claim 1, wherein the reference plate is provided on a side opposite to the ejection surface of the opening / closing member.   The liquid droplet ejection apparatus according to claim 1, wherein a cleaning member is provided on the imaging unit side of the opening / closing member. The liquid discharged from the inkjet head is an ultraviolet curable ink,
The droplet discharge device according to claim 1, wherein the opening / closing member is made of a UV cut material.   The liquid droplet ejection apparatus according to claim 1, wherein the imaging unit includes a transparent protective member.   The droplet discharge device according to claim 6, wherein the protective member is made of a UV cut material. A reference received light amount measurement step of imaging a reference plate using an imaging device in an initial state and measuring a received light amount as a reference;
A detection step of detecting an abnormality in the liquid discharge surface of the inkjet head;
Received light amount measurement step of imaging the reference plate using the imaging means after the detection step and measuring the received light amount;
An imaging device abnormality state determination step of comparing the received light amount of the reference received light amount measurement step with the received light amount of the received light amount measurement step to determine an abnormal state of the imaging unit. Maintenance method.   9. The maintenance method of the detection apparatus according to claim 8, wherein a received light amount obtained from the reference plate is equal to a received light amount obtained from the droplet discharge surface.   9. The maintenance method for a detection apparatus according to claim 8, wherein the reference plate is formed of a member that can obtain a constant amount of received light in an initial state.   11. The maintenance method for a detection apparatus according to claim 8, wherein the imaging unit is cleaned or replaced based on a result of the imaging unit abnormal state determination step.   11. The maintenance of the detection apparatus according to claim 8, wherein a protection member that protects the imaging unit is provided, and the protection member is replaced according to a result of the imaging unit abnormality state determination step. Method.

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