JP2013078858A - Detection device, liquid ejecting apparatus, method for detecting abnormal condition of liquid ejection surface, and inkjet head maintenance method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detection device capable of determining minute contaminations or scratches on a liquid ejection surface at high speed and with high accuracy, and to provide a liquid ejecting apparatus, a method for detecting abnormal conditions on the liquid ejection surface, and an inkjet head maintenance method.SOLUTION: The detection device includes: capturing an image on the liquid ejection surface (16A) while relatively moving an area sensor (80) with a plurality of sensors and an inkjet head (16); deciding the presence of the abnormal conditions and the position of the abnormal conditions of the liquid ejection surface, based on an imaging signal obtained from a portion of sensor row (80A) of a plurality of sensor rows; capturing the image of the position of the abnormal conditions again when deciding the presence of the abnormal conditions on the liquid ejection surface; and deciding the abnormal conditions, based on the imaging signal obtained from all sensor rows of the area sensor.

Description

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

  Patent Document 1 discloses a liquid ejection apparatus that includes a camera that images a meniscus formed in a nozzle hole, and that is configured to detect an ejection abnormality by analyzing an image captured by the camera.

  Patent Document 2 includes a CCD that images the head ejection surface, and based on image data obtained from the CCD, data on the distance from the ejection port of the ejection surface dirt and the area of the ejection surface dirt as ejection surface dirt information. Is output, and the droplet discharge device configured to control the cleaning operation of the discharge surface based on the discharge surface contamination information is disclosed.

  Patent Document 3 discloses a technique of using a solid-state imaging device as a CCD area sensor as a highly sensitive line sensor.

JP 2007-229928 A JP 2008-12880 A Japanese Patent Laid-Open No. 11-112878

  In order to obtain imaging data of the entire surface of the ink ejection surface of the inkjet head, a CCD area sensor of a size that can be imaged at once in the width direction of the inkjet head is scanned relative to the longitudinal direction of the inkjet head. There is a method in which imaging is performed a plurality of times at a sampling period and the imaging data sampled at each timing is synthesized.

  In order to image fine dirt and fine scratches on the ink ejection surface, at least the reading resolution of the imaging device equivalent to the nozzle arrangement density is required, and the resolution in the scanning direction is also required. When the reading resolution is increased, it takes time to read the imaging signal from the imaging device. Also, if the scan resolution is increased, the scan speed cannot be increased.

  On the other hand, if high-speed data reading or high-speed scanning is attempted, there is a risk of missing fine stains and fine scratches on the ink ejection surface.

  The present invention has been made in view of such circumstances, and a detection device, a liquid discharge device, a liquid discharge surface abnormality detection method capable of grasping minute dirt and scratches on the liquid discharge surface with high speed and high accuracy, And it aims at providing the maintenance method of an inkjet head.

  In order to achieve the above object, a detection apparatus according to the present invention includes a plurality of photoelectric conversion elements arranged in a two-dimensional manner, and a nozzle region in a first direction of a nozzle area where a nozzle opening on a liquid ejection surface of an inkjet head is arranged. A structure in which a plurality of light source conversion element arrays in which a plurality of photoelectric conversion elements are arranged along the first direction corresponding to the entire length is arranged along a second direction orthogonal to the first direction is provided. Imaging means for imaging the liquid ejection surface, relative movement means for relatively moving the inkjet head and the imaging means along the second direction, and a photoelectric conversion element as a part of the imaging means Based on the imaging signal obtained from the column, the imaging means while relatively moving the imaging device and the inkjet head, the determination means for determining the presence / absence of abnormality of the liquid ejection surface and the position of the abnormality The imaging is performed so that the nozzle region of the liquid ejection surface is imaged by a stage, and when the determination unit determines that there is an abnormality in the liquid ejection surface, the imaging unit is used to image the position of the abnormality. An abnormality for judging the state of the abnormality based on an imaging signal obtained from more photoelectric conversion element arrays than the partial photoelectric conversion element array of the imaging means and a control means for controlling the means and the relative movement means State determination means.

  According to the present invention, the photoelectric conversion array in which the plurality of photoelectric conversion elements are arranged in the second direction corresponding to the total length in the first direction of the nozzle region in which the nozzle openings are arranged on the liquid discharge surface of the inkjet head. The nozzle region on the liquid ejection surface of the inkjet head is imaged while relatively moving the imaging means arranged in plurality along the inkjet head, and based on the imaging signals obtained from a part of the plurality of photoelectric conversion element arrays Since the presence / absence of abnormality of the liquid ejection surface of the ink jet head is determined, the abnormality of the liquid ejection surface can be easily detected in a short time.

  Also, if an abnormality is found, the abnormal position is imaged, and imaging signals are acquired from more photoelectric conversion element arrays than when the presence or absence of abnormality is determined, so it is necessary to grasp the state of the abnormality in detail Can do.

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. Schematic configuration diagram of a maintenance processing unit of the ink jet recording apparatus shown in FIG. The block diagram which shows schematic structure of the detection 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. FIG. 3 is an explanatory diagram schematically illustrating abnormality detection of the ink ejection surface by the detection device illustrated in FIG. 3; Explanatory drawing schematically illustrating abnormality detection of an ink ejection surface by a detection device having a magnifying optical system 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 detection apparatus shown in FIG. An explanatory diagram of a detection signal when no abnormality has occurred, a: a diagram showing the relationship between the ink ejection surface and area sensor and the detection signal, b: a waveform diagram of the detection signal Explanatory diagram of detection signal when abnormality occurs, a: diagram showing relationship between ink ejection surface and area sensor and detection signal, b: waveform diagram of detection signal 6 is a flowchart showing a control flow of an ink discharge surface abnormality detection method for an inkjet head according to the present invention. The flowchart which shows the flow of control of the area detection mode shown in FIG. 6 is a flowchart showing a flow of control of a maintenance method for an inkjet head according to the present invention. Explanatory drawing which illustrated typically the abnormality detection of the ink discharge surface of the inkjet head which concerns on the application example of this invention Explanatory drawing which shows the detection signal of the inkjet head shown in FIG. Explanatory drawing which illustrated typically the other aspect of the ink discharge surface detection of the inkjet head shown in FIG. Explanatory drawing which shows the detection signal of the ink discharge surface detection of the inkjet head 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 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 positioned in the processing region of the cap portion 64 that is a part of the processing region 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 purge process or the suction 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. FIG. 4 illustrates a state in which the inkjet head 16 moves from right to left and the detection of the ink ejection surface 16A is performed after the wiping processing by the wiping processing unit 68.

  A detection device 70 shown in FIG. 4 includes an area sensor 80 in which a plurality of detection elements are two-dimensionally arranged, a light emitting element (LED) 82 that functions as an illumination unit, and a support member (not shown) that supports these. Are provided.

  The light receiving surface of the area sensor 80 and the light emitting surface of the light emitting element 82 are arranged 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 area sensor 80 receives the reflected light reflected by the ink ejection surface 16A, and a voltage proportional to the amount of received light is output from the area sensor 80. From the voltage signal obtained by the area sensor 80, a detection signal (shown with reference numerals 160 and 162 in FIGS. 10B and 11B) of the ink ejection surface 16A is generated.

  Waveform (crest value, time width, etc.) of a normal detection signal (shown with reference numeral 160 in FIG. 10B) and a sequentially generated detection signal (for example, detection signal 162 in FIG. 11B) And the abnormality of the ink discharge surface 16A can be detected in a circuit as an abnormality of the waveform of the detection signal (details will be described later).

[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 inkjet head 16 is moved up and down, horizontally, the cleaning device 62 applies cleaning liquid to the ink discharge surface 16A, the cap unit 64 purges (preliminary discharge), suction, and the blade 66 contacts and separates from the ink discharge surface 16A. Control etc.

  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.

[Explanation of abnormal detection of ink ejection surface]
Next, abnormality detection of the ink discharge surface 16A of the inkjet head 16 according to the embodiment of the present invention will be described in detail.

  6 (a) and 6 (b) are explanatory views schematically showing abnormality detection of the ink discharge surface 16A by the detection device 70 shown in FIG. 3, and the ink discharge surface 16A is viewed from the side opposite to the ink discharge surface 16A. It is a perspective plan view.

  6A shows a state immediately after the start of detection, and FIG. 6B shows a state immediately before the end of detection. The area sensor 80 shown in FIGS. 6A and 6B includes a plurality of detection elements (not shown) arranged two-dimensionally, and the short direction of the inkjet head 16 (the sub-scan shown in FIG. 2). The length in which the detection element in the direction S) is arranged is equal to or longer than the length of the ink discharge surface 16A in the same direction.

  Further, the arrangement density of the detection elements in the same direction is equal to or greater than the substantial nozzle arrangement pitch of the inkjet head 16 in the same direction. For example, the arrangement density of the nozzles 50 corresponds to 600 dpi (dots per inch), and the resolution of the detection element is 1200 dpi (dots per inch). In other words, the pixel density of the detection elements in the sub-scanning direction S is equal to or higher than the pixel density of the inkjet head 16 in the same direction, and one detection element corresponds to at least one nozzle.

  On the other hand, the length in which the detection element is arranged in the longitudinal direction of the ink jet head 16 of the area sensor 80 (main scanning direction M shown in FIG. 2) is sufficiently shorter than the length of the ink ejection surface 16A in the same direction.

  That is, detection data can be acquired for the entire length in the sub-scanning direction S of the ink discharge surface 16A (at least the total length in the same direction of the nozzle region in which the nozzle openings are formed) by one detection. By performing detection a plurality of times while relatively moving the sensor 80 in the main scanning direction M), detection data can be acquired for the entire area of the ink ejection surface 16A (at least the entire area of the nozzle area).

  In the abnormality detection of the ink ejection surface 16 </ b> A shown in this example, the detection data acquired from some of the detection element groups among the plurality of detection element groups arranged along the sub-scanning direction included in the area sensor 80. Based on this, it is determined whether or not the ink discharge surface 16A is abnormal, and the position of the abnormality is specified.

  That is, a part of the area sensor 80 is used as a line sensor, and the presence / absence of an abnormality of the ink ejection surface 16A and the position of the abnormality are grasped at high speed (line detection mode).

  When an abnormality is detected in the ink ejection surface 16A, detection data is detected from all the detection elements of the area sensor 80 (at least using more detection elements than the detection elements used in the line detection mode) at the abnormality occurrence position. It is acquired (that is, used as an area sensor), and an abnormal state is grasped in detail based on the detection data (area detection mode).

  In the example shown in FIGS. 6A and 6B, the detection element group 80A in the first row of the area sensor 80 is used in the line detection mode. The detection element group used in the line detection mode may be two or more rows, or may be a part of the center part of the area sensor 80 or a part of the area sensor 80 at the end of reading.

  FIG. 7 is an explanatory view schematically showing the abnormality detection of the ink discharge surface 16A by the detection device having the magnifying optical system. As shown in FIG. 7, an area sensor 80 ′ having a detection element group 80 A ′ having a length less than the entire length in the short direction of the inkjet head 16 is provided. The detection range of the area sensor 80 ′ in the direction may be expanded to correspond to the entire length of the inkjet head 16 in the sub-scanning direction S.

  Note that the magnifying optical system 84 illustrated in FIG. 7 can employ a configuration in which a plurality of lenses, a diaphragm mechanism, and the like are combined. Further, the area sensor 80 is arranged so that the light receiving surface of the area sensor 80 (80 ′) does not face the ink discharge surface 16A, and the reflected light from the ink discharge surface 16A is guided to the light receiving surface of the area sensor 80 by a mirror. It may be configured.

  FIG. 8 is a schematic configuration diagram of an interline CCD image sensor applied to the area sensor 80 provided in the detection device 70.

  A CCD image sensor 90 shown in FIG. 1 includes a plurality of photodiodes 92 (corresponding to the detection elements described above) arranged two-dimensionally, and a vertical transfer CCD 94 that transfers signal charges accumulated in each photodiode 92 in the vertical direction. And a horizontal transfer CCD 96 for transferring the signal charge sent from the vertical transfer CCD 94 in the horizontal direction, and an output circuit 98 for outputting the signal charge transferred in the horizontal direction by the horizontal transfer CCD 96 as a dot sequential voltage signal. Yes.

  In the CCD image sensor 90 shown in FIG. 8, since the photodiodes 92 are arranged in a staggered manner, the imaging resolution in the substantially vertical direction is twice the arrangement density of the photodiodes 92 in the same direction. For example, in the drawing, the leftmost photodiode group 93-1 in the leftmost direction and the photodiode group 93-2 in the same direction on the right have the same arrangement pitch of the photodiodes 92, and the vertical direction The phase is shifted by 1/2 pitch.

  The two photodiode groups 93-1 and 93-2 can be regarded as one photodiode group in substantially the same direction.

  The first row of detection element groups 80A used in the line detection mode shown in FIGS. 6A and 6B are the photodiode group 93-1 and the photodiode group in the CCD image sensor 90 shown in FIG. 93-2.

  In FIG. 8, illustration of a transfer gate provided between the photodiode 92 and the vertical transfer CCD 94, a transfer gate electrode for controlling the transfer gate, and the like are omitted.

  Reading of the signal charge of the CCD image sensor 90 is performed according to the following procedure. (1) First, the transfer gate (not shown) is closed, and the ink ejection surface 16A of the inkjet head 16 is imaged (photodiode 92 is exposed). (2) Open the transfer gate and transfer the charges accumulated in the photodiode 92 to the vertical transfer CCD 94 all at once. (3) The transfer gate is closed and the charge of each vertical transfer CCD 94 is transferred once. The charge of the pixel at the end of each photodiode group 93 is transferred to the horizontal transfer CCD 96.

  (4) A transfer pulse is sequentially applied to the horizontal transfer CCD 96 to output all horizontal pixels. (5) Returning to (3), (3) to (5) are repeated until all the pixels of the vertical transfer CCD 94 are read, and signal charges are read from all the photodiodes 92.

  When the CCD image sensor 90 is used in the line detection mode, the signal charge of the photodiode group 93 other than the photodiode group 93 to be used may be swept to the overflow drain without being transferred to the vertical transfer CCD 94, or an output circuit You may process in the signal processing after outputting from 98.

  FIG. 8 illustrates an interline CCD image sensor having a structure in which the photodiodes 92 are arranged in a staggered manner as an example of the area sensor 80, but an interline having a structure in which the photodiodes 92 are arranged in a square lattice pattern. A type CCD image sensor may be applied, or a frame transfer type CCD image sensor may be applied.

  Further, when used in the line detection mode, the unused photodiode group 93 may be shielded by a mechanical shutter or the like. Furthermore, other area sensors such as a CMOS sensor can be applied as the area sensor 80.

  FIG. 9 is a block diagram illustrating a schematic configuration of a signal processing unit 140 for imaging signals obtained from the area sensor 80 illustrated in FIG. In the line detection mode, a voltage signal proportional to the amount of light received by the photodiode is output from the signal processing unit 140 for each imaging, and in the area detection mode, an image at an abnormal position on the ink ejection surface 16A is output from the signal processing unit 140. Is output.

  The signal processing unit 140 illustrated in FIG. 9 converts an analog signal processing unit 142 that performs predetermined signal processing on the output signal (analog signal) of the area sensor 80, and converts the analog signal after the signal processing by the analog signal processing unit 142 into a digital signal. A / D conversion unit 144 for conversion, a digital signal processing unit 146 that performs predetermined signal processing on the digital signal, an area sensor 80, an analog signal processing unit 142, and an A / D conversion unit 144 for synchronization control A CCD driving unit 148 that outputs a signal, a control unit 150 that comprehensively controls the signal processing unit 140, a storage unit 152 that stores a digital signal (digital data) after the signal processing by the digital signal processing unit 146, and A television signal processing unit 154 that converts digital data stored in the storage unit 152 into a television signal (video signal); It includes a display unit 156 converted image is output, the signal output section 158 for outputting the digital data stored in the storage unit 152, the No..

  In the line detection mode, a single imaging region (a region surrounded by the total length of the ink ejection surface 16A in the sub-scanning direction S and the length of the two rows of photodiode groups 93 of the area sensor 80 in the main scanning direction is described above. For each detection region), a detection signal (for example, a detection signal using a luminance signal) having a voltage proportional to the amount of light received by each photodiode 92 is generated.

  The detection signal is sent from the signal output unit 158 to the abnormality detection unit 128 illustrated in FIG. 5, and the abnormality detection unit 128 determines the presence or absence of dirt or scratches in one imaging region based on the voltage waveform of the detection signal. At the same time, the position of dirt or scratches (position in the sub-scanning direction S of the ink discharge surface 16A) is grasped.

  In the area detection mode, a process for generating an image of the ink ejection surface 16A is performed on the output signal output from the area sensor 80. The analog signal processing unit 142 performs processing such as color separation, gain adjustment, and offset adjustment, and the digital signal processing unit 146 performs signal processing such as white balance adjustment and gamma correction, and stores them in the storage unit 152.

  The image data stored in the storage unit 152 is converted into a video signal of a predetermined format such as the NTSC system by the television signal processing unit 154 and output to the display unit 156.

  The display unit 156 is a monitor device such as an LCD display. The display unit 156 in FIG. 9 may be shared with the display unit 122 in FIG. 5 or may be provided separately from the display unit 122 in FIG. 5.

  Next, an example of a detection signal obtained in the line detection mode will be described. FIG. 10A illustrates the relationship between the ink ejection surface 16A and the area sensor 80 when no abnormality has occurred on the ink ejection surface 16A, and a part 160A of the detection signal 160 illustrated in FIG. 10B. It is a figure and the approximate center part vicinity in the subscanning direction S of 16 A of ink discharge surfaces is shown in figure.

  FIG. 10B is a waveform diagram showing the entire voltage waveform of the detection signal 160 corresponding to a part 160A of the detection signal shown in FIG. The horizontal axis in FIG. 10B corresponds to the position in the sub-scanning direction S, and the vertical axis corresponds to the data value for each position in the sub-scanning direction S. In the following description, it is assumed that the arrangement density of the photodiodes 92 (see FIG. 8) is at least twice the arrangement density of the nozzles 50.

  As shown in FIG. 10A, the area sensor 80 has a photodiode 92 squarely arranged with respect to the nozzle 50 arranged obliquely, and the arrangement of the nozzle 50 and the arrangement of the photodiode 92 do not match. . In such a state, reading cannot be performed for each pixel on a line that completely coincides with the photodiode 92 and the nozzle 50.

  However, as shown by a broken line in FIG. 10A, when the area sensor 80 is inclined with respect to the sub-scanning direction S in accordance with the arrangement of the nozzles 50, a waveform corresponding to the arrangement of the nozzles 50 is obtained. A detection signal can be obtained.

  On the other hand, when the area sensor 80 is arranged in parallel with the sub-scanning direction S, the detection is performed once with a width corresponding to a plurality of nozzle rows, and the reference numeral 160A is added to FIG. As described above, a detection signal having unevenness (voltage waveform fluctuation) smaller than the actual nozzle interval is obtained.

  Note that the period of fluctuation of the voltage waveform of the part 160A of the detection signal differs depending on the arrangement density of the photodiodes 92, and the amplitude of fluctuation of the voltage waveform differs depending on the sensitivity (dynamic range) of the photodiodes 92.

  FIG. 11A is a diagram corresponding to FIG. 10A in the case where an abnormality has occurred on the ink discharge surface 16A, and illustrates a state in which dirt 164B and 164C are attached to the ink discharge surface 16A. . FIG. 11B shows a detection signal 162 obtained when a state in which the stains 164B and 164C are attached to the ink ejection surface 16A is detected.

  If dirt 164B and 164C are attached to the ink ejection surface 16A as shown in FIG. 11A, the data values (abnormal portion data values (162B and 162C) are attached as shown in FIG. 11B. The voltage of the detection signal 162 is extremely reduced.

  That is, if the ink discharge surface 16A is not contaminated or scratched, the amount of light received by each photodiode 92 does not change abruptly, and the voltage waveform rapidly changes as in the detection signal 160 shown in FIG. Change does not appear. On the other hand, if the ink ejection surface 16A has dirt or scratches, the amount of light received by the photodiode 92 corresponding to the position of the dirt (scratch) changes abruptly compared to the amount of light received by the surrounding photodiodes 92. Therefore, a sudden change (shown with reference numerals 162B and 162C) appears in the voltage waveform as in the detection signal 162 shown in FIG. 11B.

  Further, the position of abnormality of the ink ejection surface 16A in the sub-scanning direction S can be determined from the information on which photodiode 92 corresponds to the data corresponding to the rapid change in the voltage waveform.

  In this way, the detection signal generated based on the image pickup signal obtained from a part of the photodiode group 93 of the area sensor 80 is used to detect whether or not the ink ejection surface 16A is soiled, scratched, and soiled or scratched. The position is determined.

  By detecting the ink discharge surface 16A as described above while moving the detection target position in the main scanning direction M, it is possible to detect the presence or absence of abnormality over the entire surface of the ink discharge surface 16A. It should be noted that the data obtained by one detection is subjected to processing such as integration and averaging to generate representative data values, and the representative data values are arranged in time series so that the main scanning direction M The relationship of the representative data value with respect to the position may be derived to determine whether there is an abnormality.

  Next, the overall flow of abnormality detection of the ink ejection surface 16A of the inkjet head 16 described above will be described in time series. FIG. 12 is a flowchart showing a control flow of the ink discharge surface abnormality detection method of the ink jet head according to the present invention.

  When the abnormality detection of the ink discharge surface 16A is started (step S10), the detection mode of the area sensor 80 is set to the line detection mode (step S12), and a part of the photodiode group 93 (see FIG. 9) of the area sensor 80 is set. A charge signal is acquired only from the two rows of photodiode groups 93-1 and 93-2) surrounded by a dashed line, and the detection signal 160 shown in FIG. 10B (or the detection signal shown in FIG. 11B). 162) is generated, and the presence or absence of an abnormal waveform in the detection signal is determined for each detection (step S14 in FIG. 12).

  In step S14, when no abnormal waveform exists in the detection signal (NO determination), detection of the next region is sequentially executed to determine whether there is an abnormal waveform in the generated detection signal, Proceed to step S18. On the other hand, if an abnormal waveform is found from the detection signal in step S14 (YES determination), the abnormal position is stored (step S16). In this way, detection of the ink ejection surface 16A is continued while relatively moving the inkjet head 16 and the detection device 70 (No determination in step S18).

  On the other hand, when the entire area of the ink ejection surface 16A is detected (Yes in step S18), the memory in which the information on the abnormal position is stored is referred to (step S20). No determination in step S20), the abnormality detection is ended (step S26).

  On the other hand, when the abnormal position is stored in the memory (Yes determination in step S20), the area sensor 80 is set to the area detection mode (step S22), and the area detection mode is executed (step S24).

  In step S24, imaging for acquiring the detailed state (information) of the abnormal position is executed, an image of the abnormal position is generated and stored, and the abnormality detection is terminated (step S26).

  FIG. 13 is a flowchart showing a flow of control in the area detection mode shown in step S24 of FIG. As shown in FIG. 13, when the area detection mode is started (step S100), the position information of the abnormal part is read (step S102), and the abnormal position is stored in the imaging region of the detection device 70 (area sensor 80). The inkjet head 16 and the detection device 70 are relatively moved so as to be positioned (step S104).

  During relative movement between the inkjet head 16 and the detection device 70, it is monitored whether or not the abnormal position is located in the imaging region of the detection device 70 (step S106). This monitoring is continued until the abnormal position is located in the imaging region of the detection device 70 (No determination in step S106). When the abnormal position is located in the imaging region of the detection device 70 (Yes determination in step S106), the monitoring is continued. Imaging of the abnormal position is executed (step S108).

  Thereafter, an imaging signal is acquired (step S110), and an image of the abnormal position is generated (step S112) and stored (step S114). This image may be displayed on the display unit 156 of FIG.

  If there is another abnormal part (No determination in step S116), each process from step S102 to step S114 is repeatedly executed, and if there is no other abnormal part (Yes determination in step S116). The area detection mode is ended (step S118).

  Since the abnormality detection of the ink discharge surface 16A described above is executed at the end of the maintenance process (after the wiping process of the ink discharge surface 16A by the wiping processing unit 68), if an abnormality is found, the maintenance process is performed again. Is executed.

  Next, the entire maintenance process of the inkjet head 16 will be described. FIG. 14 is a flowchart showing a control flow of the inkjet head maintenance method according to the present invention. The inkjet head maintenance process described below is appropriately executed when the apparatus is started up, between print jobs, when an abnormality occurs, or when requested by an operator.

  As shown in FIG. 14, when the maintenance process is started (step S200), the inkjet head 16 is moved to the maintenance position (step S202 in FIG. 14). Whether or not the inkjet head 16 has reached the maintenance position is monitored (step S204 in FIG. 14), and this monitoring is continued until the inkjet head 16 moves to the maintenance position (No determination in step S204).

  When the inkjet head 16 reaches the processing area of the cleaning device 62 (Yes in step S204), the cleaning process of the ink discharge surface 16A by the cleaning device 62 is executed (step S206).

  Thereafter, the inkjet head 16 is moved to the processing area of the cap portion 64, and a purge process or a suction process is executed (step S208). Thereafter, the inkjet head 16 is moved from the processing area of the cap unit 64 to the drawing position (step S210). When the inkjet head 16 reaches the detection region of the detection device 70, abnormality detection of the ink ejection surface 16A illustrated in FIGS. 12 and 13 is performed (step S212).

  In step S212, when an abnormality is found in the ink discharge surface 16A and it is determined that another maintenance process is necessary (Yes determination in step S214), the process returns to step S202, and the maintenance process of the inkjet head 16 is executed. .

  On the other hand, if no abnormality is found in the ink discharge surface 16A (No in step S214), it is monitored whether or not the inkjet head 16 has been returned to the drawing position (step S216), and when the inkjet head is returned to the drawing position. (Yes determination of step S216), the maintenance process of the inkjet head 16 is terminated (step S218).

  In the maintenance process of the inkjet head 16, an abnormality of the ink discharge surface 16A is detected before the ink discharge surface 16A cleaning process (step S206). If the abnormality is dirty, the process proceeds to the maintenance process. If the abnormality is a flaw, the fact may be notified and masking may be performed so that the nozzles around the flaw are not used.

  As an example of abnormality notification, there is a mode in which an image of the ink ejection surface 16A imaged in the area detection mode is displayed on the display unit 122 in FIG.

  Further, the cleaning content of the ink ejection surface 16A can be switched to the simple mode, the normal mode, and the strong mode according to the state of dirt (for example, the size and content of the adhered matter).

  Further, the state of the scratch is judged, and if it is a scratch that does not hinder use, maintenance processing is executed. If it is determined that there is a hindrance to use, masking of the nozzles around the scratch, the inkjet head 16 You may comprise so that replacement | exchange etc. may be performed.

  According to the abnormality detection of the ink ejection surface configured as described above, a part of the photodiode group 93 of the CCD image sensor 90 (area sensor 80) in which a plurality of photodiodes 92 are two-dimensionally arranged is used for ink jetting. While relatively moving the head 16 and the CCD image sensor 90 (detection device 70), the nozzle area in which at least the nozzle opening of the ink ejection surface 16A of the inkjet head 16 is arranged is detected, and the ink ejection surface 16A is detected. Since the presence / absence of an abnormality and the position of the abnormality are determined, the time required for detection can be greatly reduced as compared with the case where the ink ejection surface 16A of the inkjet head 16 is detected using all the pixels of the CCD image sensor 90. it can.

  Further, when an abnormality is found in the ink discharge surface 16A, all the pixels of the CCD image sensor 90 are used to image the abnormality, and an image of the ink discharge surface 16A is generated. It becomes possible to observe.

  In the line detection mode using a part of the CCD image sensor 90, a detection signal 160 (162) having a voltage waveform representing a data value proportional to the amount of light received by the photodiode 92 is generated in a region detectable by one detection. Therefore, the presence / absence of an abnormality can be easily and reliably grasped based on the detection signal voltage waveform (abrupt change in voltage).

  By setting the length of the photodiode group 93 used in the line detection mode to a length corresponding to the short direction of the inkjet head 16 (ink ejection surface 16A), the inkjet head 16 and the CCD image sensor 90 are connected to the inkjet head. The entire surface of the ink discharge surface 16A can be detected by making a relative movement only once for the entire length in the longitudinal direction.

  In the line detection mode, it is only necessary to detect at least a nozzle region in which the nozzle opening is formed in the ink discharge surface 16A.

  In this example, two photodiode groups 93-1 and 93-2 in the vertical direction that transfer charges to the same vertical transfer CCD 94 are illustrated as a part of the photodiode groups included in the CCD image sensor 90. A group of photodiodes along the line may be used.

  The use of photodiode groups along the horizontal direction suppresses the occurrence of smear. In particular, when a photodiode group close to the horizontal transfer CCD 96 is used, the reading time to the horizontal transfer CCD 96 can be greatly shortened.

  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.

[Application example]
Next, abnormality detection of the ink ejection surface of the inkjet head according to an application example of the present invention will be described. In the application example described below, detection of an abnormality on the ink ejection surface of a full-line head having a structure in which a plurality of head units are connected will be described.

  In the following description, the same or similar parts as those described above are denoted by the same reference numerals, and the description thereof is omitted.

  FIG. 15 is an explanatory diagram schematically illustrating abnormality detection of the ink discharge surface 210A of the inkjet head 210 including n head units 200 (200-1 to 200-n). FIG. 15A is a perspective plan view of the ink ejection surface 210A of the inkjet head 210, and FIG. 15B is an explanatory diagram schematically illustrating abnormality detection of the ink ejection surface 210A by the area sensor 80. FIG.

  The inkjet head 210 illustrated in FIGS. 15A and 15B includes n head units 200 in which nozzles 50 are arranged in a matrix, and the n head units 200 are in the longitudinal direction of the inkjet head 210 (main scanning direction). It has a structure arranged in a line along M).

  In the joint portion 202 between the head units 200, there is a region where the nozzles 50 belonging to one head unit 200 and the nozzles 50 of the other head unit 200 are interpolated with each other.

  Further, in the connecting portion 202 between the head units 200, the nozzles 50 belonging to one head unit 200 are redundant nozzles of the nozzles 50 of the other head unit 200 in order to ease the positioning accuracy of each head unit 200. An area exists.

  In FIGS. 15A and 15B, only the connecting portion between the head unit 200-1 and the head unit 200-2 is provided with a reference numeral, and the reference numerals of the other connecting sections are omitted.

  In the abnormality detection of the ink ejection surface 210A according to this application example, a contrivance is made so that the connecting portion 202 is not erroneously detected as an abnormality.

  FIG. 16A is an explanatory diagram showing a detection signal 260 generated in the line detection mode. The horizontal axis of the detection signal 260 shown in the figure is the position in the sub-scanning direction S. A portion denoted by reference numeral 262 in the same figure represents a data value at a position corresponding to the connecting portion 202 (see FIG. 15).

  Since one detection area of the line detection mode and the connecting portion 202 intersect each other, data corresponding to the connecting portion 202 (data in which a rapid voltage change occurs) is included in one detection data of the line detection mode. Appears in one place. The data corresponding to the connecting portion 202 moves in time series as illustrated by the broken line in FIG.

  Since the data corresponding to the connecting portion 202 has periodicity, the position of the data corresponding to the connecting portion 202 in the detection signal can be grasped by comparing with the immediately preceding detected data or the immediately following detected data. .

  By applying the mask 264 (shown in FIG. 16B) to the detection signal 260 in synchronization with the detection data 262 corresponding to the connecting portion 202, it is possible to avoid erroneous detection of the connecting portion 202 as an abnormality. The position on the waveform of the mask 264 shown in FIG. 16B is changed according to the detection timing.

  According to this application example, in the abnormality detection of the ink discharge surface 210 </ b> A of the inkjet head 210 having a structure in which a plurality of head units 200 are connected, the area sensor 80 corresponds to the connection portion 202 between the head units 200. Since the mask 264 is applied to the detection signal 260 generated in the line detection mode, it is possible to prevent erroneous detection of the connecting portion 202 between the head units 200 as an abnormality.

  Further, as shown in FIG. 17, mask markings 268 (268A, 268B) are formed outside the nozzle area 266 (shown by broken lines) where the nozzles 50 (see FIG. 2) are arranged on the ink ejection surface 210A. May be.

  FIG. 18A shows a detection signal 260'-1 including data 262A 'of the joint 202 corresponding to the marking 268A for masking (see FIG. 17). FIG. 18B shows a detection signal 260'-2 including data 262B 'of the joint portion 202 corresponding to the mask marking 268B.

  When preparing a mask corresponding to the connecting portion 202 between the head units 200, an imaging signal using the area sensor 80 in the area detection mode is acquired.

  When performing abnormality detection on the ink ejection surface 210A of the inkjet head 210 having a structure in which a plurality of head units 200 are connected as shown in this application example, a detection signal may be acquired for each head unit 200.

  In this application example, the head unit 200 illustrated the inkjet head 210 having a substantially parallelogram planar shape, but the present invention is also applied to an inkjet head including a head unit having a substantially rectangular or substantially square planar shape. It is possible.

  In addition, the configuration requirements can be changed, added, and deleted as appropriate 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 apparatus according to the first aspect includes a total length in a first direction of a nozzle region in which a plurality of photoelectric conversion elements are two-dimensionally arranged and nozzle openings on a liquid ejection surface of an inkjet head are arranged. Corresponding to the first direction, a plurality of light source conversion element arrays in which a plurality of photoelectric conversion elements are arranged are arranged along a second direction orthogonal to the first direction. Imaging means for imaging the liquid ejection surface, relative movement means for relatively moving the inkjet head and the imaging means along the second direction, and a photoelectric conversion element array as a part of the imaging means Based on the imaging signal obtained from the above, the imaging means determines the presence or absence of abnormality of the liquid ejection surface and the position of the abnormality, and the imaging means while relatively moving the imaging apparatus and the inkjet head. Imaging the nozzle region of the liquid ejection surface, and when the determination unit determines that there is an abnormality in the liquid ejection surface, the imaging unit and the imaging unit, An abnormal state determination that determines the abnormal state based on a control unit that controls the relative movement unit and an imaging signal obtained from a larger number of photoelectric conversion element arrays than the partial photoelectric conversion element array of the imaging unit. Means.

  According to the first aspect, the photoelectric conversion array in which the plurality of photoelectric conversion elements are arranged corresponding to the total length in the first direction of the nozzle region in which the nozzle openings on the liquid ejection surface of the inkjet head are arranged is the second The nozzle area of the liquid ejection surface of the inkjet head is imaged while relatively moving the imaging means arranged in the direction and the inkjet head, and an imaging signal obtained from a part of the plurality of photoelectric conversion element arrays is obtained. Based on this, it is determined whether there is an abnormality in the liquid ejection surface of the ink jet head, so that the abnormality of the liquid ejection surface can be easily detected in a short time.

  Also, if an abnormality is found, the abnormal position is imaged, and imaging signals are acquired from more photoelectric conversion element arrays than when the presence or absence of abnormality is determined, so it is necessary to grasp the state of the abnormality in detail Can do.

  The relative moving means in such an aspect has an aspect in which the liquid ejection surface and the light receiving surface of the imaging means are moved in opposition.

  (2nd aspect): The detection apparatus which concerns on a 2nd aspect WHEREIN: The said photoelectric conversion element for every position in the 1st direction of the said liquid discharge surface based on the imaging signal obtained from the said one part photoelectric conversion element row | line | column Detection signal generation means for generating a detection signal representing a voltage corresponding to the received light amount, and the determination means determines whether or not the liquid ejection surface is abnormal based on a voltage change of the detection signal.

  According to this aspect, since the detection signal having a voltage corresponding to the amount of light received by the photoelectric conversion element is generated, it is possible to easily determine whether there is an abnormality from the voltage fluctuation in the detection signal. Further, the position of abnormality can be determined from the position of voltage fluctuation.

  (3rd aspect): The detection apparatus which concerns on a 3rd aspect is provided with the image generation means which produces | generates the image of the said abnormal position imaged by the said imaging means.

  According to this aspect, the abnormal state can be grasped more accurately by generating the image of the abnormal position.

  (4th aspect): The liquid discharge apparatus which concerns on a 4th aspect WHEREIN: The inkjet head which has the liquid discharge surface in which the opening part of the several nozzle arrange | positioned two-dimensionally is formed, and the liquid discharge surface of the said inkjet head A detection device for detecting an abnormality, wherein the detection device includes a first nozzle region in which a plurality of photoelectric conversion elements are two-dimensionally arranged and nozzle openings on the liquid ejection surface of the inkjet head are arranged. A plurality of light source conversion element arrays in which a plurality of photoelectric conversion elements are arranged along the first direction corresponding to the total length of the first direction are arranged along a second direction orthogonal to the first direction. An imaging unit having a structure for imaging the liquid ejection surface; a relative moving unit for relatively moving the inkjet head and the imaging unit along the second direction; and a part of the imaging unit. Based on the imaging signal obtained from the photoelectric conversion element array, the determination means for determining the presence / absence of abnormality of the liquid ejection surface and the position of the abnormality, while relatively moving the imaging device and the inkjet head, The nozzle area of the liquid ejection surface is imaged by an imaging unit, and when the determination unit determines that there is an abnormality in the liquid ejection surface, the imaging unit is used to image the position of the abnormality. The abnormal state is determined based on an imaging unit and a control unit that controls the relative movement unit, and an imaging signal obtained from a larger number of photoelectric conversion element arrays than the partial photoelectric conversion element array of the imaging unit. An abnormal state determination means.

  As an example of the ink jet head in such an embodiment, there is a full line type ink jet head in which a plurality of nozzles are arranged over a length corresponding to the entire width of a medium that receives discharged liquid.

  (Fifth aspect): In the liquid ejection apparatus according to the fifth aspect, the first direction is a short direction of the inkjet head, and the second direction is a longitudinal direction of the inkjet head.

  According to this aspect, it is possible to detect abnormality of the entire liquid discharge surface of the inkjet head by relatively moving the inkjet head and the detection device (imaging means) only once.

  (Sixth aspect): A liquid ejection apparatus according to a sixth aspect includes a maintenance processing unit that performs a maintenance process on the inkjet head, and the relative movement unit includes a liquid ejection position from which the liquid is ejected from the inkjet head; The maintenance device is moved between maintenance positions where maintenance processing is performed by the maintenance means, and the detection device detects an abnormality of the liquid ejection surface of the inkjet head after the maintenance processing is performed by the maintenance means. Yes.

  According to this aspect, the abnormality of the liquid ejection surface after the maintenance process of the ink jet head is detected. If an abnormality is found, the abnormality can be eliminated by a second maintenance process or the like.

  (Seventh aspect): In the liquid ejection device according to the seventh aspect, the inkjet head has a structure in which a plurality of head modules are connected together, and the determination unit is configured to capture an image corresponding to a connection part between the head units. The signal is masked.

  According to this aspect, the connecting portion between the head modules of the inkjet head having a structure in which a plurality of head modules are connected is not erroneously detected as an abnormality.

  (Eighth aspect): In the liquid ejection device according to the eighth aspect, the liquid ejection surface of the inkjet head is provided with a marking that represents a boundary between the nozzle area of each head unit and the outside of the nozzle area.

  According to this aspect, the boundary of the nozzle region can be easily grasped by marking.

  (Ninth aspect): The liquid discharge surface abnormality detection method according to the ninth aspect includes a second nozzle region in which a plurality of photoelectric conversion elements are two-dimensionally arranged and nozzle openings on the liquid discharge surface of the inkjet head are disposed. A plurality of light source conversion element arrays in which a plurality of photoelectric conversion elements are arranged along the first direction corresponding to the entire length in one direction are arranged along a second direction orthogonal to the first direction. The nozzle region of the liquid ejection surface by the imaging unit while relatively moving the imaging unit that images the liquid ejection surface and the inkjet head along the second direction. The first imaging step for imaging the image, and the presence or absence of abnormality of the liquid ejection surface based on the imaging signal obtained from a part of the photoelectric conversion element array of the imaging means by the first imaging step, and the abnormality Determine the position When it is determined that there is an abnormality in the liquid ejection surface by the determination step and the determination step, the second imaging step of imaging the position of the abnormality using the imaging unit, and the second imaging step And an abnormal state determination step of determining the abnormal state based on imaging signals from more photoelectric conversion element rows than the partial photoelectric conversion element rows of the imaging means.

  (10th aspect): The maintenance method of the inkjet head which concerns on a 10th aspect performs the maintenance process to the inkjet head which has the liquid discharge surface in which the opening part of the several nozzle arrange | positioned two-dimensionally is formed And an abnormality detection step of detecting an abnormality of the liquid ejection surface of the ink jet head after the maintenance process, wherein the abnormality detection step includes a plurality of photoelectric conversion elements arranged two-dimensionally, and the ink jet head A light source conversion element array in which a plurality of photoelectric conversion elements are arranged along the first direction corresponding to the total length in the first direction of the nozzle region in which the nozzle openings on the liquid ejection surface are arranged. An image pickup means for picking up an image of the liquid ejection surface, the image pickup means having a plurality of arrangements along a second direction orthogonal to the direction of the first ink; A first imaging step of imaging at least a nozzle region of the liquid ejection surface by the imaging means while moving the jet head relatively along the second direction; and the first imaging A determination step for determining presence / absence of an abnormality of the liquid ejection surface and a position of the abnormality based on an imaging signal obtained from a photoelectric conversion element array of a part of the imaging unit by the step, and the determination step; When it is determined that there is an abnormality in the liquid ejection surface, a second imaging step of imaging the position of the abnormality using the imaging unit, and the part of the imaging unit obtained by the second imaging step And an abnormal state determination step of determining the abnormal state based on imaging signals from photoelectric conversion element arrays that are more than photoelectric conversion element arrays.

  The maintenance process in such an aspect may include an aspect including a cleaning process and a wiping process for the liquid ejection surface, and a nozzle recovery process.

  DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device 16, 16K, 16C, 16M, 16Y, 210 ... Inkjet head, 16A, 210A ... Nozzle surface, 60 ... Maintenance processing unit, 70 ... Detection device, 80 ... Area sensor, 102 ... System control unit, DESCRIPTION OF SYMBOLS 126 ... Maintenance control part, 128 ... Abnormality detection part, 90 ... CCD image sensor, 92 ... Photodiode, 93 ... Photodiode group, 146 ... Digital signal processing part, 158 ... Signal output part, 160, 162, 260 ... Detection signal , 200 ... Head unit, 268 ... Marking

Claims (10)

A plurality of photoelectric conversion elements are arranged two-dimensionally, and a plurality of photoelectric conversion elements are arranged along the first direction corresponding to the total length in the first direction of the nozzle region where the nozzle openings on the liquid ejection surface of the inkjet head are arranged. An imaging unit having a structure in which a plurality of light source conversion element arrays in which conversion elements are arranged are arranged along a second direction orthogonal to the first direction, and imaging the liquid ejection surface;
Relative movement means for relatively moving the inkjet head and the imaging means along the second direction;
Determination means for determining presence / absence of abnormality of the liquid ejection surface and the position of the abnormality based on an imaging signal obtained from a part of the photoelectric conversion element array of the imaging means;
When the imaging device and the inkjet head are relatively moved, the nozzle unit of the liquid ejection surface is imaged by the imaging unit, and the imaging unit determines that the liquid ejection surface is abnormal. Control means for controlling the imaging means and the relative movement means so as to image the position of the abnormality using the means;
An abnormal state determining unit that determines the abnormal state based on an imaging signal obtained from a larger number of photoelectric conversion element rows than the partial photoelectric conversion element row of the imaging unit;
A detection device comprising: Detection that generates a detection signal representing a voltage corresponding to the amount of light received by the photoelectric conversion element for each position in the first direction of the liquid ejection surface, based on an imaging signal obtained from the partial photoelectric conversion element array Comprising signal generating means,
The detection device according to claim 1, wherein the determination unit determines whether there is an abnormality in the liquid ejection surface based on a voltage change of the detection signal.   The detection apparatus according to claim 1, further comprising an image generation unit configured to generate an image of the abnormal position imaged by the imaging unit. An inkjet head having a liquid ejection surface in which openings of a plurality of nozzles arranged two-dimensionally are formed;
A detection device for detecting an abnormality of the liquid ejection surface of the inkjet head;
Comprising
The detection device includes a plurality of photoelectric conversion elements arranged in a two-dimensional manner, and a first area corresponding to a total length in a first direction of a nozzle region where a nozzle opening on the liquid ejection surface of the inkjet head is disposed. A plurality of light source conversion element arrays in which a plurality of photoelectric conversion elements are arranged along a direction is arranged along a second direction orthogonal to the first direction, and the liquid ejection surface is imaged Imaging means;
Relative movement means for relatively moving the inkjet head and the imaging means along the second direction;
Determination means for determining presence / absence of abnormality of the liquid ejection surface and the position of the abnormality based on an imaging signal obtained from a part of the photoelectric conversion element array of the imaging means;
When the imaging device and the inkjet head are relatively moved, the nozzle unit of the liquid ejection surface is imaged by the imaging unit, and the imaging unit determines that the liquid ejection surface is abnormal. Control means for controlling the imaging means and the relative movement means so as to image the position of the abnormality using the means;
An abnormal state determining unit that determines the abnormal state based on an imaging signal obtained from a larger number of photoelectric conversion element rows than the partial photoelectric conversion element row of the imaging unit;
A liquid ejection apparatus comprising:   The liquid ejecting apparatus according to claim 4, wherein the first direction is a short direction of the inkjet head, and the second direction is a longitudinal direction of the inkjet head. Maintenance processing means for performing maintenance processing on the inkjet head,
The relative movement means moves between a liquid discharge position where liquid is discharged from the inkjet head and a maintenance position where maintenance processing is performed by the maintenance means,
6. The liquid ejecting apparatus according to claim 4, wherein the detecting device detects an abnormality of the liquid ejecting surface of the inkjet head after the maintenance process is performed by the maintenance unit. The inkjet head has a structure in which a plurality of head modules are connected together,
The liquid ejecting apparatus according to claim 4, wherein the determination unit masks an imaging signal corresponding to a connecting portion between the head units.   The liquid ejection apparatus according to claim 7, wherein the liquid ejection surface of the inkjet head is provided with a marking that represents a boundary between the nozzle region and the outside of the nozzle region of each head unit. A plurality of photoelectric conversion elements are arranged two-dimensionally, and a plurality of photoelectric conversion elements are arranged along the first direction corresponding to the total length in the first direction of the nozzle region where the nozzle openings on the liquid ejection surface of the inkjet head are arranged. An image pickup unit having a structure in which a plurality of light source conversion element arrays in which conversion elements are arranged are arranged along a second direction orthogonal to the first direction, and imaging the liquid ejection surface; and the inkjet head A first imaging step of imaging the nozzle region of the liquid ejection surface by the imaging means, while relatively moving along the second direction;
A determination step of determining presence / absence of abnormality of the liquid ejection surface and a position of the abnormality based on an imaging signal obtained from a part of the photoelectric conversion element array of the imaging unit by the first imaging step;
A second imaging step of imaging the position of the abnormality using the imaging means when it is determined by the determination step that the liquid ejection surface is abnormal;
An abnormal state determination step of determining the abnormal state based on imaging signals obtained from the second imaging step and from more photoelectric conversion element rows than the partial photoelectric conversion element row of the imaging means;
An abnormality detection method for a liquid ejection surface, comprising: A maintenance process for performing a maintenance process on an inkjet head having a liquid ejection surface in which openings of a plurality of nozzles arranged two-dimensionally are formed;
An abnormality detection step of detecting an abnormality of the liquid ejection surface of the inkjet head after the maintenance process;
Including
In the abnormality detection step, the plurality of photoelectric conversion elements are two-dimensionally arranged, and the first detection area corresponds to a total length in a first direction of a nozzle region where a nozzle opening on the liquid ejection surface of the inkjet head is arranged. A plurality of light source conversion element arrays in which a plurality of photoelectric conversion elements are arranged along a direction is arranged along a second direction orthogonal to the first direction, and the liquid ejection surface is imaged A first imaging step of imaging at least a nozzle region of the liquid ejection surface by the imaging unit while relatively moving the imaging unit and the inkjet head along the second direction; When,
A determination step of determining presence / absence of abnormality of the liquid ejection surface and a position of the abnormality based on an imaging signal obtained from a part of the photoelectric conversion element array of the imaging unit by the first imaging step;
A second imaging step of imaging the position of the abnormality using the imaging means when it is determined by the determination step that the liquid ejection surface is abnormal;
An abnormal state determination step of determining the abnormal state based on imaging signals obtained from the second imaging step and from more photoelectric conversion element rows than the partial photoelectric conversion element row of the imaging means;
A maintenance method of an ink jet head, comprising:

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