JP2009083320A - Image recording device and abnormality detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image recording device which permits an abnormality concerning ink discharge and other abnormalities in transfer recording and the like in a system for recording images by transferring by using a detection means in one location to be separated and detected, and an abnormality detection method. <P>SOLUTION: The image forming device forms a primary image in which a recorded image and charts before and after the image are formed on an intermediate transfer body, and transfers and records the primary image after going through prescribed processes. After detecting the charts on the recording medium and performing image processing emphasizing an abnormality, the device judges whether or not the image whose abnormality is emphasized is within a reference range. When the image whose abnormality is emphasized is within the reference range, it is output as a good quality image. If the image whose abnormality is emphasized is not within the reference range, it is judged abnormal. When discharge is judged abnormal, the device shifts to a recording head maintenance process. When transfer recording is judged abnormal, the device optimizes a solvent removal section or the like. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image recording apparatus and an abnormality detection method, and more particularly to recording abnormality detection in an image recording apparatus using a transfer recording method in which a primary image is formed on an intermediate transfer member and then the primary image is transferred and recorded on a recording medium. Regarding technology.

  2. Description of the Related Art Conventionally, a transfer type ink jet recording apparatus (image recording apparatus) that forms a primary image on an intermediate transfer member using a liquid such as ink and transfers and records the primary image on a recording medium is known. An image recording apparatus to which the transfer recording system is applied has a feature that a high-quality image can be obtained regardless of the type of recording medium, and is therefore preferably used for high-definition image recording. In an ink jet recording apparatus, when a recording head discharge abnormality occurs, a non-uniformity (density unevenness) occurs in a recorded image, so that a recording head discharge abnormality is quickly found and a recovery process is performed on the recording head. Must be configured.

  As a method for detecting malfunction of a recording head in a transfer recording type ink jet recording apparatus, the presence or absence of ink on a transfer medium (intermediate transfer member) is detected, and when there is no ink droplet at a predetermined lattice point corresponding to recording data, the recording head A method has been proposed in which the writing process is stopped when it is determined that there is an operation failure, and a recovery process is performed to recover the operation failure nozzle (Patent Document 1). Also, a test image is marked from an ink jet that is considered defective on the blank portion of the intermediate transfer drum, the test image is evaluated using a sensor, the inspected ink jet is measured, and the print head is measured using the measured value. A method has been proposed in which a maintenance cycle is started, and the probability of occurrence of a recoverable failure as a function of the number of prints from the previous failure is predicted using failure probability data to adjust the interval of ink jet defect measurement ( Patent Document 2).

Furthermore, a sensor for detecting a first registration mark indicating the position in the width direction and the position in the length direction on the foil sheet (intermediate transfer member), and a second registration mark indicating the position transferred from the foil sheet of the printing paper. A sensor is provided for detecting, and an error in the transfer position of the foil transfer pattern on the printing paper is detected from the detection result of the sensor, and if this error is equal to or greater than a predetermined value, the position of the image on the foil pattern is changed. A method has been proposed (Patent Document 3). Furthermore, when a composite pattern is formed by overlapping the patterns of each color on the drum, the density of the composite pattern is measured using an optical detector having a resolution larger than the pixel size, and the measured density value exceeds the expected density value. Discloses a method for performing X-axis alignment of a print head (Patent Document 4).
JP-A-6-305127 JP 2006-123549 A JP 2003-136893 A JP 2005-145065 A

  However, when the image on the intermediate transfer body is read to determine the abnormality of the recording head, if the intermediate transfer medium is made of a material different in spectral reflection distribution and light absorption from the final output medium, the detected image and the actual output There is a difference. Or, there is a disadvantage that a general image detection means cannot be used. Further, detection of defects on the final output medium is essential for detection of abnormalities in image forming processes such as image transfer and solvent removal on the intermediate transfer member, and detection of ink fly-off and dust.

  On the other hand, the image on the final output medium has an image defect caused by an abnormality in primary image formation on the intermediate transfer member (recording head abnormality) and an abnormality in the process after the primary image formation on the intermediate transfer member. Since the resulting image defects are mixed, it is difficult to determine which process is an image defect based on the reading result of the final output medium.

  In order to solve the above problem, it is conceivable to include both a sensor for detecting an image on the intermediate transfer member and a sensor for detecting an image on the final output medium, but the same kind of detection system is provided in one apparatus. It will be provided redundantly, and it can be said that it is disadvantageous in terms of space efficiency and cost of the apparatus.

  The inventions described in Patent Documents 1 and 2 and Patent Document 4 include a sensor for detecting the presence or absence of ink on the transfer medium. However, the sensor cannot determine abnormality during transfer recording. Further, in the invention described in Patent Document 3, since the sensor is provided only on either the upstream side or the downstream side of the transfer position, only one of the abnormality of the image recording head or the abnormality of the transfer is provided. It cannot be detected. That is, the invention described in Patent Document 3 does not detect both abnormality of the image recording head and abnormality of transfer with one sensor.

  The present invention has been made in view of such circumstances, and it is possible to detect both abnormality relating to primary image formation in the transfer recording method and other abnormality such as transfer recording by using a single detection unit. An object of the present invention is to provide an image recording apparatus and an abnormality detection method.

  In order to achieve the above object, an image recording apparatus according to the present invention is a transfer recording means for transferring and recording a primary image formed on an intermediate transfer member with an image forming liquid discharged from a nozzle of a recording head onto a recording medium. An image recording apparatus comprising: an image detection unit that converts an image recorded on the recording medium into electronic data; and applying predetermined image processing to the image data converted into electronic data by the image detection unit, And image processing means for discriminating whether there is a transfer abnormality of the transfer recording means or a discharge abnormality of the recording head.

  According to the present invention, based on the reading result of the image recorded on the recording medium, it is determined whether or not the transfer recording unit has a transfer abnormality or an image abnormality caused by a recording head ejection abnormality. It is possible to separately detect the transfer abnormality of the transfer recording means and the discharge abnormality of the recording head using the image detection means integrated in one place.

  In addition, by configuring the process to change from the image recording process to the maintenance process so as to perform an image abnormality recovery process based on the detection result, maintenance is performed on the recording head at an appropriate timing. Reduced operating rate is prevented.

  The image forming liquid ejected from the recording head includes ink containing a color material. Further, it may include a recording head (inkjet head) that discharges a treatment liquid that reacts with the ink to aggregate or insolubilize the ink (coloring material).

  The image detecting unit includes an reading unit that reads an image on a recording medium, and a conversion unit that converts a read signal obtained from the reading unit into electronic data. Further, the image processing means stores storage means for storing the image data converted into electronic data, and determination means for determining whether or not an ejection abnormality of the recording head has occurred with reference to the image data stored in the storage means. There is an aspect provided with.

The present invention includes a full-line head in which a plurality of nozzles are arranged over a length corresponding to the width of the intermediate transfer member in a direction orthogonal to the moving direction of the intermediate transfer member, and the intermediate transfer member and the recording head are relatively This is particularly effective when single-pass recording is performed in which image recording is performed over the entire surface in a predetermined image forming area after being moved only once.

  A second aspect of the present invention relates to an aspect of the image recording apparatus according to the first aspect, wherein the primary image formed on the intermediate transfer member includes a solid image formed around a recorded image, and the image The processing means performs predetermined image processing of the image data of the solid image converted into electronic data by the image detection means, thereby determining whether the transfer recording means is abnormal in transfer or the recording head is abnormal in discharge. It is characterized by discriminating.

  According to the second aspect of the present invention, density unevenness can be easily detected by using a solid image, and transfer abnormality and ejection abnormality can be separately detected based on the tendency of density unevenness. The solid image applied to the invention according to claim 2 is preferably formed by discharging the image forming liquid from all nozzles provided in the recording head. The dot coverage of the solid image is preferably 100%.

  The periphery of the recording image includes the front side of the recording image (downstream in the conveyance direction of the recording medium) and the rear side of the recording image (upstream in the conveyance direction of the recording medium).

  Abnormalities in transfer recording may include abnormalities other than the abnormality in the recording head, such as adhesion of foreign matter to the intermediate transfer member and abnormality in the solvent removal process before transfer recording.

  A third aspect of the present invention relates to an aspect of the image recording apparatus according to the second aspect, wherein the image processing means performs the intermediate transfer member in the recording medium for image data obtained by converting the solid image into electronic data. The image processing for emphasizing density unevenness in the x direction orthogonal to the y direction corresponding to the moving direction of the image is performed.

  According to the third aspect of the present invention, particularly when an abnormality occurs in a specific nozzle in image recording using a full-line type recording head, density unevenness (vertical length) along the y direction at a position to be recorded by the nozzle. Therefore, by enhancing the density unevenness in the y direction, the image abnormality caused by the abnormality of the recording head is emphasized, and it becomes easy to find the image abnormality and the image abnormality is detected by the recording head. It can be easily determined that it is caused by the abnormality.

  The image processing for emphasizing density unevenness here may be configured by combining two or more types of image processing.

  A fourth aspect of the present invention relates to an aspect of the image recording apparatus according to the second aspect, wherein the image processing means performs the intermediate transfer member in the recording medium for image data obtained by converting the solid image into electronic data. The differential processing is performed in the x direction orthogonal to the y direction corresponding to the moving direction.

  According to the fourth aspect of the present invention, since a portion having a large rate of change in the x direction in the image read by using the differential processing in the x direction is extracted, an edge portion having a density along the y direction (for example, , A boundary between density unevenness and a normal part) can be easily determined.

  A mode in which Fourier transform processing is performed on the x direction in combination with differentiation processing in the x direction is preferable. The correlation between the spatial frequency and the density intensity in the image is derived by the Fourier transform process, and the abnormality due to the ejection abnormality can be easily determined by paying attention to the intensity in the high frequency region of the spatial frequency.

  The high frequency region of the spatial frequency preferably includes a spatial frequency corresponding to the dot pitch in the x direction (minimum nozzle pitch in the main scanning direction corresponding to the x direction in the recording head). Further, the high frequency region of the spatial frequency may include a spatial frequency corresponding to the reading resolution in the x direction of the image detection unit.

  A fifth aspect of the present invention relates to an aspect of the image recording apparatus according to the second aspect, wherein the image processing means performs a filtering process using a high frequency filter on image data obtained by converting the solid image into electronic data. It is characterized by.

  According to the fifth aspect of the present invention, the high frequency component is extracted from the change components in the image by using the high frequency filter. In image recording with a full-line type recording head, density unevenness occurs in a high-frequency region corresponding to the arrangement pitch of nozzles in the main scanning direction. Therefore, by extracting the high-frequency component from the change components in the image, it occurs in the image. It is easy to determine that the abnormal image is caused by the ejection abnormality of the recording head.

  A sixth aspect of the present invention relates to an aspect of the image recording apparatus according to any one of the first to fifth aspects, wherein the primary image formed on the intermediate transfer member is formed around the recorded image. The image processing means includes a test pattern in which a dot group in which a plurality of dots are arranged in a direction parallel to the moving direction of the intermediate transfer member is arranged at equal intervals in a direction orthogonal to the moving direction of the intermediate transfer member. A nozzle having an ejection abnormality is specified by performing predetermined image processing on the image data of the test pattern converted into electronic data by the detection means.

  According to the sixth aspect of the present invention, it is possible to accurately detect the abnormal discharge nozzle and to shorten the processing time required for the recovery process by performing the recovery process on the abnormal discharge nozzle. .

  A test pattern suitable for the invention according to claim 6 is a dot pattern (a line segment having a predetermined length in the sub-scanning direction) in which a plurality of dots are arranged along the moving direction (sub-scanning direction) of the intermediate transfer member. This dot group row (line segment row) is arranged along the length of the intermediate transfer member in the main scanning direction every n dots (n times the pitch between the minimum dots) in the main scanning direction orthogonal to the moving direction of the intermediate transfer member. ) Are arranged in n rows along the sub-scanning direction, and each of the n dot group rows is arranged with a phase shift of 1 dot pitch in the main scanning direction.

  A seventh aspect of the present invention relates to an aspect of the image recording apparatus according to any one of the first to sixth aspects, wherein the image processing unit detects an abnormal discharge from a transition of a result of the predetermined image processing. It is characterized by having a mechanism for discriminating whether or not the image abnormality due to the above reaches a visual recognition level and changing the process based on the discrimination result.

  According to the seventh aspect of the present invention, the recovery process can be performed on the recording head before the image abnormality (for example, density unevenness in the y direction) due to the ejection abnormality reaches the visual recognition level. It is possible to avoid the occurrence of image abnormality due to ejection abnormality without dropping.

  The aspect of changing the process includes an aspect of changing from a normal image recording process to a recording head recovery process. For example, there is an aspect including a control unit that controls each part of the apparatus so that the recovery process of the recording head is executed immediately before the number of printed sheets when a value at which the ejection abnormality becomes a visual recognition level is set for the number of printed sheets. .

The invention according to an eighth aspect relates to an aspect of the image recording apparatus according to the first aspect, wherein the image processing unit is configured to transfer the solid image to the intermediate transfer member in the recording medium with respect to image data obtained by converting the solid image into electronic data. The one-dimensional Fourier transform process is performed in the y direction corresponding to the moving direction of the image, the one-dimensional Fourier transform process is performed in the x direction orthogonal to the y direction, the one-dimensional Fourier transform process result in the x direction, and the y direction. Comparing with a one-dimensional Fourier transform process, it is discriminated whether the transfer recording means has a transfer abnormality or the recording head has a discharge abnormality.

  According to the eighth aspect of the invention, the one-dimensional Fourier transform processing in the moving direction (y direction) and the orthogonal direction (x direction) of the intermediate transfer member is applied, and the y direction processing result and the x direction processing result are applied. By comparing these, it is easy to distinguish between an image abnormality caused by ejection abnormality and an image abnormality caused by transfer recording.

  For example, if the value (intensity) of the one-dimensional Fourier transform processing result in the y direction exceeds the value of the one-dimensional Fourier transform processing result in the x direction, it is determined that ejection is abnormal, and the value of the one-dimensional Fourier transform processing result in the y direction Is less than the value of the one-dimensional Fourier transform processing result in the x direction, it can be determined that the transfer recording is abnormal.

  Moreover, the method invention for achieving the said objective is provided. That is, the abnormality detection method according to claim 9 is an abnormality detection method in an image recording apparatus for transferring and recording a primary image formed on an intermediate transfer member by an image forming liquid ejected from a nozzle of a recording head onto a recording medium. Whether the image recorded on the recording medium is converted into electronic data, and the image data converted into electronic data is subjected to predetermined image processing to determine whether it is a transfer recording abnormality or a recording head ejection abnormality. It is characterized by distinguishing.

  In the image processing process for processing the image data that has been converted into electronic data, processing for emphasizing density unevenness in the direction perpendicular to this, which is seen as a streak along the moving direction of the intermediate transfer member, and the moving direction of the intermediate transfer member It may include differential processing in the orthogonal direction, Fourier transform processing after the differential processing, one-dimensional Fourier transform processing in the direction orthogonal to the moving direction of the intermediate transfer member and the moving direction of the intermediate transfer member.

  According to the present invention, based on the reading result of the image recorded on the recording medium, it is determined whether or not the transfer recording unit has a transfer abnormality or an image abnormality caused by a recording head ejection abnormality. It is possible to separately detect the transfer abnormality of the transfer recording means and the discharge abnormality of the recording head using the image detection means integrated in one place. In addition, by configuring the process to change from the image recording process to the maintenance process so as to perform an image abnormality recovery process based on the detection result, maintenance is performed on the recording head at an appropriate timing. Reduced operating rate is prevented

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

〔Device configuration〕
FIG. 1 is a schematic configuration diagram showing the overall configuration of an ink jet recording apparatus according to an embodiment of the present invention. As shown in the figure, the inkjet recording apparatus 10 employs a transfer recording system in which a primary image on the intermediate transfer body 12 is transferred and recorded on a recording medium 14 after a primary image is formed on the intermediate transfer body 12. . Further, when forming a primary image on the intermediate transfer body 12, there is a two-liquid system in which color material particles are aggregated by reacting ink containing pigment particles (color material particles) with the treatment liquid on the intermediate transfer body 12. Applied.

That is, the inkjet recording apparatus 10 includes a processing liquid application unit 16 that applies a processing liquid having a function of aggregating or insolubilizing ink over the entire surface of the image forming region on which the primary image of the intermediate transfer body 12 is formed, and black (K ), Cyan (C), magenta (M), yellow (Y), and a printing unit 18 having a plurality of inkjet heads (heads) 18K, 18C, 18M, and 18Y provided corresponding to inks containing colorants of the respective colors. And an ink storage / loading unit 20 that supplies ink of a color corresponding to each of the heads 18K, 18C, 18M, and 18Y of the printing unit 18, and the processing liquid and ink react on the intermediate transfer body 12 to generate ink colors. A solvent removal processing unit 22 that removes the solvent component (liquid) after separation into a material (dot) and a solvent, and an intermediate transfer body 12 (primary image) after the solvent removal treatment are preliminarily added. A preheating processing unit 24 that performs transfer, a transfer recording unit 28 that transfers and records the primary image formed on the intermediate transfer body 12 to the recording medium 14 supplied from the paper feeding unit 26, and after transfer recording by the transfer recording unit 28 A fixing section 30 for peeling the intermediate transfer body 12 and the recording medium 14; a fixing section 32 for fixing an image transferred and recorded on the recording medium 14 after peeling from the intermediate transfer body 12; The inline scanner 34 for reading the recorded image on the recording medium 14 after being formed, a discharge unit (not shown) for discharging the recording medium 14 to the outside of the apparatus after the reading process by the inline scanner 34, and the intermediate transfer body 12 after transfer recording And a cleaning processing unit 39 that cleans the image forming area and removes deposits such as ink and dust remaining on the intermediate transfer body 12.

  The intermediate transfer body 12 is an endless belt wound around a plurality of stretching rollers 38A to 38F. When at least one stretching roller (driving roller) among the stretching rollers 38A to 38F is rotated, In synchronization with the rotation of the driving roller, the intermediate transfer member 12 moves in a predetermined direction (shown by an arrow A in FIG. 1). For example, when the tension roller 38 </ b> A is rotated counterclockwise using the tension roller 38 </ b> A as a driving roller, the intermediate transfer body 12 moves from the right to the left in FIG. 1 in the printing area immediately below the printing unit 18.

  In the ink jet recording apparatus 10 shown in this example, the moving speed of the intermediate transfer body 12 is controlled to be constant throughout a series of image forming processes. The moving speed of the intermediate transfer member 12 can be changed as appropriate according to the ink droplet ejection period of the printing unit 18 and the resolution of the recorded image. For example, if the ink droplet ejection period is constant, the resolution of the recorded image becomes coarse when the moving speed of the intermediate transfer body 12 is relatively fast, and the resolution of the recorded image becomes relatively slow when the moving speed of the intermediate transfer body 12 is relatively slow. It becomes fine.

  In addition, an image forming area on which at least a primary image is formed on the image forming surface of the intermediate transfer body 12 facing the printing unit 18 is impermeable so that ink droplets do not permeate and is made of a material such as resin, metal or rubber. Are preferably used. Further, at least the image forming area of the intermediate transfer body 12 is configured to form a horizontal surface (flat surface) having a predetermined flatness.

  In FIG. 1, an endless belt is shown as one embodiment of the intermediate transfer body 12. However, the intermediate transfer body 12 applied to the present invention may be a drum shape (see FIG. 18) or a flat plate shape. The intermediate transfer member 12 may have a multilayer structure having a support (support layer) having a predetermined rigidity inside the surface layer.

  Preferred materials used for the surface layer (image forming surface) of the intermediate transfer body 12 include, for example, a polyimide resin, a silicon resin, a polyurethane resin, a polyester resin, a polystyrene resin, a polyolefin resin, a polybutadiene resin, Known materials such as polyamide-based resins, polyvinyl chloride-based resins, polyethylene-based resins, and fluorine-based resins can be used.

  The treatment liquid application unit 16 brings the surface of the intermediate transfer body 12 into contact with the application roller 16A for applying the treatment liquid to the intermediate transfer body 12, a container 16B for storing the treatment liquid, and the application roller 16A in the vertical direction. And an up-and-down mechanism (not shown) to be moved. The coating roller 16A is made of a material whose surface has a function of absorbing liquid, such as a porous member, and is configured such that the distance from the intermediate transfer body 12 can be varied by the vertical mechanism.

  When applying the treatment liquid to the intermediate transfer body 12, the application roller 16A is brought into contact with the intermediate transfer body 12, and the position of the application roller 16A is moved so as to be pressed with a predetermined pressure. On the other hand, when the treatment liquid is not applied to the intermediate transfer body 12, the position of the application roller 16A is moved so that the application roller 16A and the intermediate transfer body 12 are separated from each other.

  The application roller 16A has a cylindrical shape, and the length in the longitudinal direction corresponds to the width of the intermediate transfer body 12 (the length in the direction orthogonal to the moving direction of the intermediate transfer body) (see FIG. 2). . A configuration in which a plurality of application rollers having a length shorter than the width of the intermediate transfer body 12 is arranged in the width direction of the intermediate transfer body 12 is also possible.

  In this example, a mode in which the treatment liquid is applied to the intermediate transfer body 12 using the application roller 16A is illustrated, but other application members such as a blade may be used instead of the application roller 16A, or a spray method or an ink jet method. The treatment liquid may be applied to the intermediate transfer body 12.

  A printing unit 18 is provided on the downstream side of the treatment liquid application unit 16 in the moving direction of the intermediate transfer member. The ink storage / loading unit 20 has an ink supply tank (indicated by reference numeral 60 in FIG. 5) for storing the ink of the color corresponding to each head, and the ink of each color passes through the required ink flow path to each head 18K. , 18C, 18M, 18Y. Further, the ink storage / loading unit 20 includes notifying means (display means, warning sound generating means) for notifying when the ink remaining amount is low, and a member having a mechanism for preventing erroneous loading between colors. Is used.

  A solvent removal processing unit 22 is provided on the downstream side of the printing unit 18 in the moving direction of the intermediate transfer member. The solvent removal processing unit 22 includes an absorption roller 22A that contacts the liquid on the intermediate transfer body 12 and absorbs the liquid. The opposite side of the intermediate transfer body 12 of the absorbing roller 22A is supported by a roller 38B.

  A preheating processing unit 24 is provided on the downstream side of the solvent removal processing unit 22 in the moving direction of the intermediate transfer member. A flat-plate infrared heater is suitably used for the preheating processing unit 24, and a preheating temperature lower by about 10 ° C to 20 ° C than the heating temperature at the time of transfer recording is given to the primary image (intermediate transfer member). In this example, the preheating temperature is set in the range of 50 ° C to 100 ° C. A mode in which a heater is provided inside the image forming area of the intermediate transfer body 12 and the intermediate transfer body is preheated using the heater is also possible.

  By performing the preheating process by the preheating processing unit 24, the liquid component existing in the vicinity of the primary image is evaporated, and the temperature of the primary image and the vicinity thereof is slightly lower than the temperature suitable for transfer recording. By raising the temperature, it is possible to shorten the heating time during transfer recording.

  The primary image that has been subjected to the preheating process by the preheating processing unit 24 is transferred and recorded on the recording medium 14 by the transfer recording unit 28. In the transfer recording process by the transfer recording unit 28, first, the recording medium 14 is supplied from the paper supply unit 26 through a predetermined supply path, and the recording medium 14 and the intermediate transfer body 12 (primary image) are aligned. The recording medium 14 is cut into a predetermined size by the cutter 41. Next, the recording medium 14 is sandwiched between the pressure roller 28A and the intermediate transfer member 12, and a predetermined heater is used by a heater built in the heating roller 28B disposed on the opposite side of the intermediate transfer member 12 to the pressure roller 28A. The primary image formed on the intermediate transfer body 12 is transferred and recorded on the recording medium 14 by being pressed at a predetermined pressure by the pressure roller 28A while being heated to a temperature.

As an example of the configuration of the paper supply unit 26, a magazine for rolled paper (continuous paper) can be cited. In the ink jet recording apparatus 10 shown in the present example, an abnormality detection chart (test image, see FIG. 7) is formed before and after the recorded image, so that a region where the chart is formed can be secured more than a desired size. It is cut larger than the desired size by the chart forming area.

  When the paper feeding unit 26 is configured to be able to use a plurality of types of recording paper, an information recording body such as a barcode or a wireless tag that records the paper type information is attached to the magazine, and information on the information recording body is stored in a predetermined manner. It is preferable that the type of recording medium (medium type) to be used is automatically determined by reading with the reading device, and ink ejection control is performed so as to realize appropriate ink ejection according to the media type.

  Specific examples of the recording medium 14 applicable to this example include permeable media such as plain paper and inkjet paper, non-permeable or low permeable media such as coated paper, and adhesive and release labels on the back surface. There are various media such as sticker paper, resin films such as OHP sheets, metal sheets, cloth, and wood.

  The cutting cutter 41 provided in the front stage of the transfer recording unit 28 includes a fixed blade 41A having a length equal to or larger than the conveyance path width of the recording medium, and a round blade 41B that moves along the fixed blade. The fixed blade 41A is provided on the print back side, and the round blade 41B is arranged on the print surface side across the conveyance path.

  The transfer temperature during transfer recording is set in the range of 60 ° C. to 120 ° C., and the transfer pressure is set in the range of 0.5 MPa to 3.0 MPa. Note that the transfer temperature and the transfer pressure may be appropriately adjusted according to the type (material, thickness, etc.) of the recording medium and the type of ink used. For example, when the recording medium 14 is relatively thick, the transfer pressure is relatively small, and when the recording medium 14 is relatively thin, the transfer pressure is relatively large. Further, when the surface roughness of the recording medium 14 is relatively rough (for example, when using plain paper), the transfer pressure is relatively increased, and the surface roughness of the recording medium 14 is relatively fine ( For example, when using photo-only paper or coated paper), the transfer pressure is relatively small.

  As a means for adjusting the transfer pressure at the time of transfer recording in the transfer recording section 28, a mechanism (drive means) for moving the pressure roller 28A in the vertical direction in FIG. That is, when the heating roller 28B (pressure roller 28A) is moved in a direction to increase the clearance between the heating roller 28B and the pressure roller 28A, the transfer pressure is reduced, and the clearance between the heating roller 28B and the pressure roller 28A is reduced. When the heating roller 28B (pressure roller 28A) is moved in the direction, the transfer pressure increases.

  When the transfer recording on the recording medium 14 is completed in the transfer recording unit 28, the intermediate transfer body 12 and the image-recorded recording medium 14 are peeled off at the peeling unit 30 provided on the downstream side of the transfer recording unit 28 in the intermediate transfer body moving direction. Then, the recording medium 14 is sent to the fixing unit 32.

  The peeling unit 30 is configured to peel the recording medium 14 from the intermediate transfer body 12 with the rigidity (waist strength) of the recording medium 14 itself by the winding curvature of the peeling roller of the intermediate transfer body 12. The peeling part 30 may be used in combination with means for promoting peeling such as a peeling nail.

  The fixing unit 32 performs a fixing process and applies heat and pressure to fix the image recorded on the recording medium 14. The fixing unit 32 includes a heating roller pair whose temperature can be adjusted in the range of 50 ° C. to 200 ° C. The heating temperature of the fixing unit 32 is preferably 130 ° C. and the pressure is preferably 0.5 MPa to 3.0 MPa. The heating temperature of the fixing unit 32 is preferably set according to the glass transition temperature of the polymer fine particles contained in the ink.

When the ink contains resin fine particles or polymer fine particles, the polymer fine particles are formed (a thin film in which fine particles are dissolved is formed on the outermost surface of the image), thereby improving the fixability and scratch resistance. it can. If the transfer recording unit 28 can achieve both transferability and film formation, a mode in which the fixing unit is omitted is also possible.

  An aspect in which a cooling device for cooling the recording medium 14 is provided between the peeling unit 30 and the fixing unit 32 is also preferable. Examples of the cooling device include a configuration including a fan that applies cold air to the recording medium 14 and a configuration including a cooling member such as a Peltier element or a heat sink.

  When the transfer recording process on the recording medium 14 is completed, the intermediate transfer body 12 is subjected to a cleaning process by a cleaning processing section 39 provided on the downstream side of the transfer recording section 28 in the intermediate transfer body moving direction. The cleaning processing unit 39 has a blade that wipes and removes deposits such as residual ink while contacting the image forming surface of the intermediate transfer body 12, and a collection unit that collects the removed residual ink. The configuration of the cleaning processing unit 39 that removes the residue of the intermediate transfer body 12 is not limited to the above example, but a method of niping a brush roll, a water absorption roll, etc., an air blow method of blowing clean air, an adhesive roll There are methods or combinations thereof. In the case where the cleaning roll is nipped, the cleaning effect is great if the belt linear velocity and the roller linear velocity are changed.

  The ink jet recording apparatus 10 shown in this example includes an inline scanner 34 that reads an image subjected to a fixing process. In this example, charts (shown by reference numerals 102 and 104 in FIG. 7) are recorded before and after the recorded image, the chart is read by the inline scanner 34, and ejection abnormalities of the heads 18K, 18C, 18M, and 18Y based on the read results. In addition, it is possible to detect an abnormality such as a solvent removal abnormality in the solvent removal processing unit 22, a transfer recording abnormality in the transfer recording unit 28, and a foreign matter adhering to the intermediate transfer body 12.

  The charts provided before and after the recorded image are used for inspecting the relationship between color density and data (tone reproducibility) in addition to abnormalities relating to ejection and transfer. Needless to say, if the required area is sufficient either before or after the recorded image, it may be provided only on one side.

  Although the detailed configuration of the inline scanner 34 is not shown, the inline scanner 34 includes a reduction optical system (not shown) including a lens set and a mirror, and a three-color line CCD corresponding to RGB. In this example, since a separate chart is recorded for each color, the CCD mounted on the in-line scanner 34 may be a monochrome compatible one.

  Alternatively, one image may be created while reducing and projecting an image on the recording medium 14 conveyed to the line CCD and correcting it by an output of an encoder (position detection device) of a conveyance system of the recording medium 14. Instead of the color line CCD having RGB three-color filters, the paper output by the area CCD may be photographed for each sheet. Furthermore, a mode using a CMOS sensor or a contact image sensor instead of the CCD is also possible.

[Description of printing section]
Next, the printing unit 18 will be described in detail. As shown in FIG. 2, each of the heads 18K, 18C, 18M, and 18Y of the printing unit 18 has a length corresponding to the maximum width of the image forming area in the intermediate transfer body 12, and image formation is performed on the ink ejection surface. This is a full line type head in which a plurality of nozzles for ink ejection (shown by reference numeral 51 in FIG. 3) are arranged over the entire width of the region.

  The heads 18K, 18C, 18M, and 18Y are black (K), cyan (C), magenta (M), and yellow (Y) colors from the upstream side along the moving direction (sub-scanning direction) A of the intermediate transfer body 12. The heads 18K, 18C, 18M, and 18Y are fixedly installed so as to extend in a direction (main scanning direction) orthogonal to the moving direction of the intermediate transfer body 12.

  According to the configuration in which the full line type head having the nozzle row covering the entire width of the intermediate transfer body 12 is provided for each color ink, the intermediate transfer body 12 and the printing unit 18 in the moving direction of the intermediate transfer body 12. The primary image can be recorded in the image forming area of the intermediate transfer body 12 only by performing the operation of relatively moving the two times (that is, by one sub-scan). As a result, the heads 18K, 18C, 18M, and 18Y can perform high-speed printing as compared with a serial (shuttle) type head that reciprocates in the main scanning direction orthogonal to the moving direction of the intermediate transfer body 12, thereby improving print productivity. Can be made.

  In this example, the configuration of the standard colors (four colors) of KYMC is exemplified, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink, dark ink, and special color ink are used as necessary. May be added. For example, it is possible to add an ink head that discharges light-colored ink such as light cyan and light magenta, and the arrangement order of the color heads is not particularly limited.

[Head structure]
Next, the structure of the heads 18K, 18C, 18M, and 18Y will be described in detail. Since the heads 18K, 18C, 18M, and 18Y have the same structure, the head is represented by the reference numeral 50 as a representative of them.

  FIG. 3A is a plan perspective view showing an example of the structure of the head 50, and FIG. 3B is an enlarged view of a part thereof. 3C is a perspective plan view showing another example of the structure of the head 50, and FIG. 4 is a sectional view showing the three-dimensional configuration of the ink chamber unit (4-4 in FIGS. 3A and 3B). It is sectional drawing which follows a line.

  In order to increase the dot pitch formed on the intermediate transfer body 12, it is necessary to increase the nozzle pitch in the head 50. As shown in FIGS. 3A and 3B, the head 50 of this example includes a plurality of ink chamber units 53 including nozzles 51 that are ink droplet ejection holes and pressure chambers 52 corresponding to the nozzles 51. The nozzles are arranged in a staggered matrix (two-dimensionally), so that a substantial nozzle interval (projection nozzle pitch) projected so as to be aligned in the longitudinal direction of the head (sub-scanning direction) High density is achieved.

  The form in which one or more nozzle rows are configured in the main scanning direction over a length corresponding to the entire width of the intermediate transfer body 12 is not limited to this example. For example, instead of the configuration of FIG. 3A, as shown in FIG. 3C, short head modules 50 ′ in which a plurality of nozzles 51 are two-dimensionally arranged are arranged in a staggered manner and connected. A line head having a nozzle row having a length corresponding to the entire width of the intermediate transfer body 12 may be configured. Although not shown, a line head may be configured by arranging short head modules in a line.

  The pressure chamber 52 provided corresponding to each nozzle 51 has a substantially square planar shape, and the nozzle 51 and the supply port 54 are provided at both corners on the diagonal line. Each pressure chamber 52 communicates with a common flow channel 55 through a supply port 54. The common flow channel 55 communicates with an ink supply tank (not shown in FIG. 4; indicated by reference numeral 60 in FIG. 5) as an ink supply source, and the ink supplied from the ink supply tank is the common flow channel 55 of FIG. Is distributed and supplied to each pressure chamber 52.

  As shown in FIG. 4, a piezoelectric element 58 having an individual electrode 57 is joined to a diaphragm 56 that constitutes the top surface of the pressure chamber 52 and also serves as a common electrode, and a drive voltage is applied to the individual electrode 57. As a result, the piezoelectric element 58 is deformed and ink is ejected from the nozzle 51. When ink is ejected, new ink is supplied from the common channel 55 to the pressure chamber 52 through the supply port 54.

  In this example, the piezoelectric element 58 is applied as a means for generating ink ejection force ejected from the nozzles 51 provided in the head 50. However, a heater is provided in the pressure chamber 52, and the pressure of film boiling caused by heating of the heater is used. It is also possible to apply a thermal method that ejects ink.

  As shown in FIG. 3B, the ink chamber units 53 having such a structure are arranged in a fixed manner along a row direction along the main scanning direction and an oblique column direction having a constant angle θ that is not orthogonal to the main scanning direction. By arranging a large number of patterns in a lattice pattern, the high-density nozzle head of this example is realized.

  That is, with a structure in which a plurality of ink chamber units 53 are arranged at a constant pitch d along the direction of an angle θ with respect to the main scanning direction, the pitch P of the nozzles projected so as to be aligned in the main scanning direction is d × cos θ. Thus, in the main scanning direction, each nozzle 51 can be handled equivalently as a linear arrangement with a constant pitch P. With such a configuration, it is possible to realize a high-density nozzle configuration in which 2400 nozzle rows are projected per inch (2400 nozzles / inch) so as to be aligned in the main scanning direction.

  In the implementation of the present invention, the nozzle arrangement structure is not limited to the illustrated example, and various nozzle arrangement structures such as an arrangement structure having one nozzle row in the sub-scanning direction can be applied.

[Configuration of supply system]
FIG. 5 is a schematic diagram showing the configuration of the ink supply system in the inkjet recording apparatus 10. The ink supply tank 60 is a base tank that supplies ink to the head 50 and is included in the ink storage / loading unit 20 described with reference to FIG. The ink supply tank 60 includes a system that replenishes ink from a replenishing port (not shown) and a cartridge system that replaces the entire tank when the remaining amount of ink decreases. The cartridge system is suitable for changing the ink type according to the intended use. In this case, it is preferable that the ink type information is identified by a barcode or the like, and ejection control is performed according to the ink type.

  As shown in FIG. 5, a filter 62 is provided between the ink supply tank 60 and the head 50 in order to remove foreign substances and bubbles. The filter mesh size is preferably equal to or smaller than the nozzle diameter (generally about 20 μm).

  Although not shown in FIG. 5, a configuration in which a sub tank is provided in the vicinity of the head 50 or integrally with the head 50 is also preferable. The sub-tank has a function of improving a damper effect and refill that prevents fluctuations in the internal pressure of the head.

  Further, the inkjet recording apparatus 10 is provided with a cap 64 as a means for preventing the nozzle 51 from drying or preventing an increase in ink viscosity near the nozzle, and a cleaning blade 66 as a means for cleaning the ink discharge surface of the head 50. Yes.

  The maintenance unit (maintenance means) including the cap 64 and the cleaning blade 66 can be moved relative to the head 50 by a moving mechanism (not shown), and is moved from a predetermined retracted position to a maintenance position below the head 50 as necessary. Moved.

  The cap 64 is displaced up and down relatively with respect to the head 50 by an elevator mechanism (not shown). The cap 64 is raised to a predetermined raised position when the power is turned off or during printing standby, and is brought into close contact with the head 50, thereby covering the nozzle surface with the cap 64.

During printing or standby, if the frequency of use of a specific nozzle 51 is reduced and ink is not ejected for a certain period of time, the ink solvent near the nozzle evaporates and the ink viscosity increases. In such a state, ink cannot be ejected from the nozzle 51 even if the piezoelectric element 58 operates.

  Before such a state is reached (within the range of viscosity that can be discharged by the operation of the piezoelectric element 58), the piezoelectric element 58 is operated, and a cap is formed to discharge the deteriorated ink (ink in the vicinity of the nozzle whose viscosity has increased). Preliminary ejection (purge, idle ejection, collar ejection, dummy ejection) is performed toward 64 (ink receiver).

  In addition, a mode in which ink is ejected toward the intermediate transfer body 12 to perform preliminary discharge, so-called flushing is also possible. For example, when a plurality of images are continuously formed, preliminary ejection can be performed between images. In particular, when a plurality of identical images are formed, the frequency of ink (treatment liquid) discharge at a specific nozzle is low and the possibility of abnormal discharge increases, so preliminary discharge is performed between images for the specific nozzle. It is preferable to carry out.

  When preliminary discharge is performed on the intermediate transfer body 12, the heating roller 28B is moved to prevent the ink from the preliminary discharge from adhering to the pressure roller 28A (see FIG. 1). A predetermined clearance (for example, about 10 mm) may be provided between the two. By using the intermediate transfer body 12 as an ink receiver, the time for moving the cap 64 directly below the printing unit 18 (see FIG. 1) and the time for retracting the intermediate transfer body 12 from directly below the printing unit 18 can be omitted. The time required for preliminary ejection can be shortened.

  Further, when air bubbles are mixed into the ink in the head 50 (in the pressure chamber 52), the ink cannot be ejected from the nozzle even if the piezoelectric element 58 is operated. In such a case, the cap 64 is applied to the head 50, the ink in the pressure chamber 52 (ink mixed with bubbles) is removed by suction with the suction pump 67, and the suctioned and removed ink is sent to the recovery tank 68.

  In this suction operation, the deteriorated ink with increased viscosity (solidified) is sucked out when the ink is initially loaded into the head or when the ink is used after being stopped for a long time. Since the suction operation is performed on the entire ink in the pressure chamber 52, the amount of ink consumption increases. Therefore, it is preferable to perform preliminary ejection when the increase in ink viscosity is small.

  The cleaning blade 66 is made of an elastic member such as rubber, and can slide on the ink ejection surface of the head 50 by a blade moving mechanism (not shown). When ink droplets or foreign matter adhere to the ink ejection surface, the ink ejection surface is wiped by sliding the cleaning blade 66 on the ink ejection surface, and the ink ejection surface is cleaned.

When preliminary ejection is performed between images, ink attached to the intermediate transfer body 12 by preliminary ejection is removed from the intermediate transfer body 12 using the cleaning processing unit 39.
[Explanation of control system]
FIG. 6 is a principal block diagram showing the system configuration of the inkjet recording apparatus 10. The inkjet recording apparatus 10 includes a communication interface 70, a system control unit 72, an image memory 74, a motor driver 76, a heater driver 78, a solvent application / removal control unit 79, a print control unit 80, an image buffer memory (not shown), and a head driver. 84, a maintenance control unit 90 and the like.

The communication interface 70 is an interface unit that receives image data sent from the host computer 86. As the communication interface 70, a serial interface such as USB (Universal Serial Bus), IEEE 1394, Ethernet (registered trademark), a wireless network, or a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted. Image data sent from the host computer 86 is taken into the inkjet recording apparatus 10 via the communication interface 70 and temporarily stored in the image memory 74.

  The image memory 74 is storage means for temporarily storing an image input via the communication interface 70, an image read by the inline scanner 34, an image (data) after image processing by the image processing unit 94, and the like. Data is read and written through the unit 72. The image memory 74 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used.

  The system control unit 72 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. To do. That is, the system control unit 72 controls the communication interface 70, the image memory 74, the motor driver 76, the heater driver 78, and the like, and performs communication control with the host computer 86, read / write control of the image memory 74, and the like. A control signal for controlling the motor 88 and the heater 89 of the transport system is generated.

  The image memory 74 stores programs executed by the CPU of the system control unit 72 and various data necessary for control. Note that the image memory 74 may be a non-rewritable storage means, or may be a rewritable storage means such as an EEPROM. The image memory 74 is used as a temporary storage area for image data, and is also used as a program development area and a calculation work area for the CPU. Further, a memory built in a processor constituting the system control unit 72 or the like may be used as the image memory 74.

  The motor driver 76 is a driver that drives the motor 88 in accordance with an instruction from the system control unit 72. In FIG. 6, the motor (actuator) disposed in each part in the apparatus is represented by reference numeral 88. For example, the motor 88 shown in FIG. 6 includes a motor that drives the tension roller 38A in FIG. 1, a motor that drives the application roller 16A, a motor that drives the absorption roller 22A of the solvent removal processing unit 22, and the like.

  The heater driver 78 is a driver that drives the heater 89 in accordance with an instruction from the system control unit 72. In FIG. 6, a plurality of heaters provided in the ink jet recording apparatus 10 are represented by reference numeral 89. For example, the heater 89 includes the heater of the preheating processing unit 24 and the like.

  The solvent application / removal control unit 79 controls the treatment liquid application of the treatment liquid application unit 16 (coat) in FIG. 1 and also controls the solvent removal in the solvent removal processing unit 22 (remover) in FIG. When the sensor for detecting the position of the intermediate transfer body 12 (not shown) detects that the image forming area of the intermediate transfer body 12 has reached the processing area of the processing liquid application section 16, the solvent application / removal control section 79 applies the application. The roller 16A is brought into contact with the intermediate transfer body 12, and the movement and rotation of the application roller 16A are controlled so as to rotate the application roller 16A.

  Further, when it is detected that the image forming area where the primary image is formed has reached the processing area of the solvent removal processing unit 22, the solvent application / removal control unit 79 contacts the absorbing roller 22 </ b> A against the intermediate transfer body 12. In addition, the movement of the absorbing roller 22A is controlled so as to apply a predetermined pressure.

The print control unit 80 has a signal processing function for performing various processing and correction processes for generating a print control signal from the image data in the image memory 74 according to the control of the system control unit 72. A control unit that supplies print data (dot data) to the head driver 84. Necessary signal processing is performed in the print controller 80, and the ejection amount and ejection timing of the ink droplets of the head 50 are controlled via the head driver 84 based on the image data. Thereby, a desired dot size and dot arrangement are realized.

  The print control unit 80 includes an image buffer memory (not shown), and image data, parameters, and other data are temporarily stored in the image buffer memory when the print control unit 80 processes image data. Also possible is a mode in which the print control unit 80 and the system control unit 72 are integrated to form a single processor.

  A transfer recording control unit (not shown) controls the pressure roller 28A of the transfer recording unit 28 shown in FIG. Optimum pressing values of the heating roller 28B and the pressure roller 28A are obtained in advance for each type of the recording medium 14 and ink, and are stored in a predetermined memory (for example, the image memory 74) as a data table. When the information on the recording medium 14 and the ink used are acquired, the pressure on the pressure roller 28A is controlled with reference to the memory. Further, the transfer recording control unit controls the heating temperature of the heater built in the heating roller 28 </ b> B according to a command from the system control unit 72. For example, when the type of the recording medium 14 is selected (set) via a user interface (not shown), the system control unit 72 acquires information on the recording medium 14 and sets an optimum transfer temperature for the recording medium. A command signal including transfer temperature information is sent to the transfer recording control unit. The transfer recording control unit controls the heating temperature of the heater built in the heating roller 28 </ b> B in accordance with a command signal from the system control unit 72.

  The head driver 84 generates a drive signal to be applied to the piezoelectric element 58 of the head 50 based on the image data given from the print control unit 80, and drives the piezoelectric element 58 by applying the drive signal to the piezoelectric element 58. Including a driving circuit. The head driver 84 shown in FIG. 6 may include a feedback control system for keeping the driving condition of the head 50 constant.

  Image data to be printed is input from the outside via the communication interface 70 and stored in the image memory 74. At this stage, RGB image data is stored in the image memory 74.

  The image data stored in the image memory 74 is sent to the print control unit 80 via the system control unit 72, and is converted into dot data for each ink color by the print control unit 80. That is, the print control unit 80 performs processing for converting the input RGB image data into dot data of four colors of KCMY. The dot data generated by the print controller 80 is stored in an image buffer memory (not shown).

  Note that the primary image formed on the intermediate transfer body 12 should be a mirror image of the secondary image (recorded image) finally formed on the recording medium 14 in consideration of inversion during transfer. I must. That is, the drive signal supplied to the head 50 is a drive signal corresponding to the mirror image, and the print control unit 80 needs to invert the input image.

  Various control programs are stored in a program storage unit (not shown), and the control program is read and executed in accordance with a command from the system control unit 72. The program storage unit may use a semiconductor memory such as a ROM or an EEPROM, or may use a magnetic disk or the like. An external interface may be provided and a memory card or PC card may be used. Of course, you may provide several recording media among these recording media. The program storage unit may also be used as storage means (not shown) for operating parameters.

In the ink jet recording apparatus 10, a large number of sensors are provided in each part. For example,
There are a temperature sensor for detecting the temperature of each part in the apparatus, a position sensor for detecting the intermediate transfer body 12 (position on the conveyance path of the primary image), a sensor for detecting the remaining amount of ink in the ink supply tank 60 shown in FIG. Can be mentioned.

  A detection signal of the sensor is sent to the system control unit 72. When the system control unit 72 acquires the detection signal sent from the sensor, the system control unit 72 determines various information from the detection signal and controls each unit based on the information.

  The chart reading signal read by the inline scanner 34 is subjected to predetermined signal processing such as noise removal, amplification, and waveform shaping, and then sent to the image processing unit 94 via the system control unit 72. The image processing unit 94 performs predetermined image processing including sharpening processing on the read signal (read image), and then stores the image processed data in a predetermined area in the image memory 74. In addition, the system control unit 72 determines whether an image abnormality has occurred in the image based on the sharpened data stored in the predetermined area of the image memory 74 and prints the image abnormality. Section 18 (see FIG. 1), whether it is caused by an abnormality in ink discharge or an abnormality in the solvent removal processing section 22 or an abnormality in transfer recording in the transfer recording section 28, and determines the determination result. The data is sent to the system control unit 72.

  When an image abnormality has occurred in the read image and the determination result indicates that the image abnormality is caused by an abnormality in ink ejection of the printing unit 18, the system control unit 72 performs the maintenance control unit 90. Then, the maintenance driving unit 92 is operated via the printer to perform the recovery process (maintenance process) of the printing unit 18. The maintenance drive unit 92 in FIG. 6 includes a drive system that moves the cap 64 in FIG. 5, a drive system that moves the cleaning blade 66, a pump 67, and the like.

  On the other hand, when a determination result indicating that the image abnormality is a transfer abnormality in the transfer recording unit 28 is sent, the system control unit 72 sets the transfer temperature and transfer pressure at the time of transfer recording via the transfer recording control unit described above. Change and optimize transfer recording conditions. Further, if necessary, the operator is informed that an abnormality has occurred in the transfer recording unit 28 using notifying means (not shown). In addition, when foreign matter such as dust adheres to the intermediate transfer body 12, the cleaning control of the cleaning processing unit 39 in FIG. 1 is changed to the strong cleaning mode (for example, extending the cleaning time) to optimize the cleaning processing. Turn into. Furthermore, in the case of an abnormality in the solvent removal process, the pressure of the absorbing roller 22A is changed to optimize the solvent removal process.

[Description of abnormality detection]
Next, abnormality detection applied to the ink jet recording apparatus 10 shown in FIG. 1 will be described. The abnormality detection shown in the present example includes ejection failure separation determination and transfer recording abnormality detection. In the single pass image recording by the intermediate transfer type inkjet recording apparatus 10 equipped with the full line type head shown in FIG. 1, the upper and lower ends of the printed image (upstream and downstream of the intermediate transfer body of the recorded image) are used for detection. Draw a chart at the same time. Next, the image and inspection chart (detection chart) formed on the intermediate transfer body 12 are transferred and recorded on the recording medium 14, and then differentiated in the x (width) direction as a sharpening process of the read chart image. , Y-direction streaks (longitudinal streaks) are emphasized and Fourier transformed to detect ejection defects of the head 50 separately from defects such as ink ejection other solvent removal and transfer abnormality.

<Explanation of the chart>
FIG. 7 shows the recording medium 14 on which the charts 102 and 104 are recorded on the top and bottom (front and back) of the image 100. 8A shows the K portion 102K extracted from the chart 102 shown in FIG. 7, and FIG. 8B shows a part of the K portion 102K shown in FIG. 8A. Is shown enlarged. In this example, since the chart 102 and the chart 104 are the same image, the chart 102 will be described as a representative of both. In FIG. 7, the x direction which is the short direction of the recording medium 14 corresponds to the main scanning direction shown in FIG. 3A, and the y direction which is the longitudinal direction of the recording medium 14 is the sub scanning direction of FIG. It is assumed that the recording medium 14 is conveyed from the upper side to the lower side in FIG.

  First, charts (the detection chart and the inspection chart described above) are added above and below the print image data. For example, in the case of an image creating apparatus (inkjet recording apparatus) that finally uses a chrysanthemum half size (636 mm × 469 mm) as a printed matter (recording medium 14), the paper used is about 720 mm × 520 mm, A chart area of 42 mm in the longitudinal direction is prepared. That is, a chart area of 42 mm is prepared in the conveyance direction of the recording medium 14.

  The chart 102 shown in FIG. 7 is based on the K portion formed by the ink ejected from the head 18K shown in FIG. 1, the C portion formed by the ink ejected from the head 18C, and the ink ejected from the head 18M. The formed M portion and the Y portion formed by the ink ejected from the head 18Y are included. In FIG. 7, for convenience of illustration, the above-described K part, C part, M part, and Y part are not shown individually, but are collectively indicated by reference numeral 102. In the abnormality detection shown in this example, since a chart is formed for each color (for each head), abnormality can be determined for each color (for each head).

  The charts 102 and 104 may be provided before and after the image 100 to read the same pattern twice to improve the accuracy. Unlike the patterns shown in FIGS. 8A and 8B, the density on the front side or the rear side gradually changes. It is also possible to obtain a pattern for calibrating how to change the density (gamma) by using a density scale or a small area (patch) consisting of several density levels.

  In order to confirm the ejection of each nozzle of the head, the chart area is divided into a KCMY four-color solid area and a finer area (test pattern) using all the nozzles for each color.

That is, the K portion 100K shown in FIG. 8A has a solid portion a which is a solid pattern of a single color (K) and y-direction linear portions b ₁ and b ₁ every 4 dots in the x direction for one dot in the x direction. _b 3, _{b 1} and 4 dots moved y-direction linear portion _b 2 is moved, _{b 1} to y-direction linear portion _b 3 which is moved in two dots x-direction, _{b 1} to 3 dots x direction includes a y-direction linear portion b ₄ is moved to a separatory x-direction, the solid portion a and the y-direction linear portion b ₁ ~b ₄ from the downstream side in the conveying direction of the recording medium 14 along the y-direction (see FIG. 8 (a) Are arranged in the order of a, b ₁ , b ₂ , b ₃ , b ₄ .

  The solid part a is composed of ink ejected from all nozzles of the head 18K. In this example, the dot density of the solid portion a is 1200 dpi, and the dot coverage is 100%. The dot coverage can be adjusted as appropriate depending on the sensitivity of the in-line scanner 34 and the density of the solid portion a.

The y-direction straight portions b _{1 to} b ₄ are arranged at equal intervals along the y direction, and the y-direction straight portions b _{1 to} b ₄ are arranged with a phase shifted in the main scanning direction. In FIG. 8B, the y-direction linear portions b _{1 to} b ₄ are arranged so that the positions in the y-direction do not overlap. The y-direction linear portions b _{1 to} b ₄ each have a y-direction dot group (line segment having a predetermined length in the y direction) having a predetermined length and a 4-dot interval (main scanning) along the main scanning direction. Are arranged at intervals of four times the minimum inter-dot pitch in the direction).

That is, the y-direction straight line b ₁ includes y-direction straight lines b ₁ -1, b ₁ -2, b ₁ -3,..., And the y-direction straight line b ₁ -1 and the y-direction straight line b ₁ -2. The arrangement interval is 4 dots, and the arrangement interval between the y-direction straight line b ₁ -2 and the y-direction straight line b ₁ -3 is also a 4-dot interval. The y-direction straight line b ₂ includes y-direction straight lines b ₂ -1, b ₂ -2, b ₂ -3,..., And the y-direction straight line b ₂ -1 and the y-direction straight line b ₂ -2. The arrangement interval is 4 dots, and the arrangement interval between the y-direction straight line b ₂ -2 and the y-direction straight line b _2-3 is also a 4-dot interval.

Further, the y-direction straight line b ₃ includes y-direction straight lines b ₃ -1, b ₃ -2, b ₃ -3,..., And the y-direction straight line b ₃ -1 and the y-direction straight line b ₃ -2 are included. The arrangement interval is 4 dots, and the arrangement interval between the y-direction straight line b ₃ -2 and the y-direction straight line b ₃ -3 is also a 4-dot interval. Moreover, y-direction linear portion _{b 4} y-direction line _{b 4 -1, b 4 -2,} b 4 -3, consists ..., include, y direction line _b 4 -1 and y direction line _{b 4} - The arrangement interval of 2 is a 4-dot interval, and the arrangement interval of the y-direction straight line b ₄ -2 and the y-direction straight line b ₄ -3 is also a 4-dot interval.

Regarding the phase in the x direction, the y direction straight line b ₁ -1 and the y direction straight line b ₂ -1 are one dot interval in the x direction, and the y direction straight line b ₁ -1 and the y direction straight line b ₃ -1 are 2 in the x direction. The phase is shifted by the dot interval, and the y-direction straight line b ₁ −1 and the y-direction straight line b ₄ −1 are shifted by the three-dot interval in the x direction.

In other words, the y-direction straight line portion b ₂ corresponds to the y-direction straight line b ₁ by one dot interval in the x-direction (right side in FIG. 7), and the y-direction straight line portion b ₃ corresponds to the y-direction straight line b ₁ in the x-direction (right side in FIG. 7). ), The y-direction straight line b ₃ is arranged at a position moved by the y-direction straight line b ₁ in the x direction (right side in FIG. 7) by the three-dot interval.

The reading resolution of the inline scanner 34 applied to this example is 600 dpi, and does not correspond to the dot density 1200 dpi of the solid part a, so the solid part a cannot be read one dot at a time (with a resolution of one dot pitch). It has a configuration. However, even when the reading resolution of the in-line scanner 34 is coarser than the dot density of the solid part a, the dot pattern of the test pattern part b shown in FIG. The nozzles that are not ejecting can be identified in units of one (the nozzle corresponding to each dot can be identified from the relationship between the reading element of the in-line scanner 34 and the read pattern). In this example, the nozzle is specified using both the solid portion and the y-direction straight portions b _{1 to} b ₄ in consideration of the measurement accuracy and the detection resolution.

For example, depending on whether it y direction line _b 1 _{-1~b 4} -1 is likely to be read by one reading element, the read element is reading any of the y direction line B1～b _4, line y It is possible to determine which of the direction straight lines b ₁ −1 to b ₄ −1 is being read.

  Note that the above-described nozzle specifying method is merely an example, and the relationship between the dot and the nozzle may be determined using other methods.

  By identifying the nozzle causing the problem in this way, when shifting to the maintenance mode, the wiping, capping and flushing of the nozzle (and the peripheral nozzle) in question are particularly focused. The maintenance time can be shortened.

<Discharge abnormality detection>
Next, detection of image abnormality due to ejection abnormality will be described. FIG. 9 is a flowchart showing a control flow of ejection abnormality detection in the image recording control of the inkjet recording apparatus 10 shown in FIG.

As shown in FIG. 9, when image recording is started (step S10), print data (recorded image data) is received from the host computer 86 of FIG. 6 via the communication interface 70 (step S12 of FIG. 9). Then, the image 100 and the charts 102 and 104 are output to the intermediate transfer body 12 (step S14 in FIG. 9). That is, in step S14, the recording image 100 shown in FIG. 7 and the primary images of the charts 102 and 104 are formed on the intermediate transfer member 12 shown in FIG.

  Next, after passing through predetermined steps such as a solvent removal step and a preheating step, transfer and output from the intermediate transfer body 12 to the paper surface are performed in the transfer recording section 28 shown in FIG. 1 (step S16 in FIG. 9). That is, in step S16, the primary image on the intermediate transfer body 12 shown in FIG.

  After that, the recording medium 14 on which the recorded image 100 and the charts 102 and 104 are recorded is conveyed to the reading area of the inline scanner 34 shown in FIG. 1, and the image and chart on the paper surface are detected by the inline scanner 34 (FIG. 9). Step S18). That is, in the reading of the image and chart shown in step 18, each time the chart and image on the paper are transferred, they are sequentially read by the inline scanner, and the chart image is read as digital data by the three-color line CCD.

  For example, if the removal of the solvent is not properly performed, an image having a 5% density is sufficiently transferred, but if the image has a 100% density, the image may not be transferred sufficiently.

  When the charts 102 and 104 are read in step S18, the read result data is sent from the inline scanner 34 to the image processing unit 94 via the system control unit 72 of FIG. The abnormalities in the charts 102 and 104 are emphasized (step S20 in FIG. 9).

  That is, in step S20, the image processing unit 94 performs sharpening processing on the read image. In this example, as a sharpening process, the gray chart part (solid part a in FIG. 8 (a)) is subjected to a differential process in the x direction to emphasize stripe unevenness (density unevenness) along the y direction. A Fourier transform process is performed to obtain a correlation between the spatial frequency and the intensity of density unevenness, and the data after the image processing is stored in the image memory 74 in FIG. In the differentiation process, when the concentration value is represented by g [x], the differentiation of the concentration g [a] at the point a can be represented by the following equation (1).

dg [a] / dx = lim _{Δx → 0} (g [a + Δx] −g [a]) / Δx (1)
In image recording using a line-type head, stripe unevenness along the sub-scanning direction (y direction) perpendicular to the longitudinal direction of the head is likely to occur due to ejection abnormality of a specific nozzle. By performing the differentiation process in the direction, it is possible to emphasize the unevenness in the y direction (edge of density change) and to easily determine the presence or absence of density unevenness.

  Further, Fourier transform processing is performed on the image in which the density unevenness is emphasized, thereby revealing y-direction unevenness. FIG. 10 shows the correlation (characteristic diagram 120) between the spatial frequency (cycle / mm) after the Fourier transform process and the intensity (frequency) of density unevenness.

A curve 122 in the characteristic diagram 120 shown in FIG. 10 indicates the characteristic of the intensity g ₁ (f) when the image abnormality occurs, and the curve 124 indicates the intensity g ₂ (f) when the density unevenness is not noticeable (normal image). ) Characteristics. In the curve 122 of FIG. 10, the intensity f (a) at the spatial frequency (a = 0.023 (cycle / mm)) corresponding to the module pitch of the head, and the spatial frequency (b = 12 (cycle / mm) corresponding to the swath pitch. The intensity f (c) at the spatial frequency (c = 24 (cycle / mm)) corresponding to the reading resolution of the inline line scanner 34 (see FIG. 1) is higher than the intensity f (b) at). On the other hand, in the curve 124 of the image where the density unevenness is not conspicuous, the intensity at the spatial frequency c corresponding to the reading frequency of the in-line scanner 34 is small even when the enhancement process is performed. In this case, it is verified whether the density unevenness reaches the visual recognition level using the value represented by the following expression (2) as an index (reference value).

(2 × f (c)) / (f (a) + f (b)) (2)
That is, the intensity of the low frequency region (for example, the spatial frequency region below the swath pitch) and the intensity of the high frequency region (for example, the spatial frequency region exceeding the swath pitch, the spatial frequency corresponding to the reading resolution and the spatial frequency corresponding to the dot pitch). In comparison, the intensity f (c) at the spatial frequency c corresponding to the reading resolution with respect to the average value of the intensity f (a) at the spatial frequency a corresponding to the module pitch and the intensity f (b) at the spatial frequency b corresponding to the swath pitch. ) Exceeds a predetermined value, it is determined that the density change (density unevenness) in the read image is large and the density unevenness can be visually recognized.

  For example, if the index after the emphasis processing of the limit that causes no problem in the visual recognition level is 2.0, when the value of the index represented by the above formula (2) exceeds 2.0, it reaches a defective level where the density unevenness is conspicuous. It can be said that. Specifically, the index value of the formula (2) in the curve 122 is 3.2, and the index value of the formula (2) in the curve 124 is 2.0.

A module pitch, the head of nozzle is arranged in a matrix, a repetition pitch of the modules in the the line type head 50 constructed by combining a plurality of head modules 50 '(shown by reference numeral P _m in FIG. 11) . Also, the Suwasupitchi a repetition pitch of the matrix arrangement are folded position of the nozzle (repetitive pitch in the main scanning direction in the main scanning direction of the diagonal direction of the nozzle row 51A) (shown by reference numeral P _s in Fig. 11) . The module pitch in the head of this example is P _m = 0.023 (cycle / mm), and the swath pitch is P _s = 12 (cycle / mm). Also, the dot pitch P _d is the minimum nozzle pitch in the main scanning direction, in this example, a _{P d = 47 (cycle / mm} ).

Note that when reading pitch _{P r (= 24 (cycle /} mm)) of the in-line scanner 34 is higher than the dot pitch P _d is the presence or absence of ejection abnormalities based on the intensity of the spatial frequency corresponding to the dot pitch P _d However, when the reading resolution of the in-line scanner 34 does not correspond to the dot pitch P _d as in this example, a higher frequency cannot be measured than the reading pitch P _r (reading resolution), so the dot pitch P _d is supported. The intensity of the spatial frequency is smaller than the intensity of the reading pitch (reading resolution).

  That is, in step S22 of FIG. 9, the index represented by (2) above is calculated. If the index value exceeds 2.0, it is determined that a discharge abnormality has occurred, and the maintenance shown in step S24 is performed. Move to the process. In the maintenance process of step S24, the recovery process of the corresponding head 50 is executed. In addition, since the nozzle in which the ejection abnormality has occurred is specified, the recovery process may be preliminary ejection for each nozzle. If there are multiple nozzles in which ejection abnormality has occurred, the recovery process may be performed for each head module. You may perform discharge or suction. Furthermore, when nozzles in which ejection abnormality has occurred exist across a plurality of head modules, preliminary ejection or suction may be performed on the entire head.

  On the other hand, if the index value is 2.0 or less in step S22 (YES determination), it is output as a non-defective printed matter (step S26), and the process returns to step S12.

In addition, as shown in FIG. 12, it replaces with the differentiation process of the x direction in the sharpening process process (differentiation process + Fourier-transform process) of FIG.9 S20, and may apply a high frequency filter process (step S20 '). . Density unevenness due to head ejection abnormalities usually occurs at the narrowest interval (high frequency region of spatial frequency), so that the density unevenness can be emphasized by high frequency filter processing.

<Prediction of occurrence of discharge abnormality after separation of discharge abnormality>
Next, a process for predicting the occurrence of ejection abnormality will be described. FIG. 13 is a flowchart showing the control flow of the ejection abnormality prediction process in the image recording control of the inkjet recording apparatus 10 shown in FIG. Note that, in the ejection abnormality prediction process described below, the same or similar parts as those of the ejection abnormality detection described above are denoted by the same reference numerals, and the description thereof is omitted.

In the ejection failure prediction processing shown in FIG. 13, the step of storing a change in the proportion of high-frequency component corresponding to Suwasupitchi P _s or read pitch P _r after the Fourier transform using the ejection abnormality judgment described above in a predetermined memory And having a step of predicting and detecting a discharge abnormality from the transition of the stored ratio.

  Specifically, the index represented by the above equation (2) is stored for each image recording, and the occurrence timing of ejection abnormality is predicted from the transition of the index. When ejection abnormality is determined based on the detection result of the image after transfer recording, there is a case where image recording is performed by the head in which the ejection abnormality has occurred from the timing when the ejection abnormality is determined until the maintenance process is started. As a result, the occurrence of abnormal discharge is predicted in advance, and maintenance processing is performed on the head before the occurrence of abnormal discharge (immediately before the occurrence of abnormal discharge), thereby recording an abnormal image due to abnormal discharge. Is avoided.

  That is, after differential processing (or high-frequency filter processing) and Fourier transform processing are performed in step S20, the process proceeds to step S100, and feature amount data is built in a predetermined memory (for example, the image memory 74 or the processor in FIG. 6). Memory). Thereafter, the process proceeds to step S102 in FIG. 13, and the transition of the feature amount stored in the predetermined memory is predicted.

  When the transition of the feature value is predicted in step S102, it is determined in step S104 whether or not the estimated feature value is within the reference range. In other words, in step S104, the number of recording media (recording time) exceeding the reference range is estimated, and until the estimated number of recording media is reached (YES determination), it is output as a non-defective printed matter (step S26) and estimated. When the number reaches the number (NO determination), the process proceeds to step S24, and the maintenance process is executed.

  That is, the index represented by the above equation (2) is calculated and stored as the feature amount for each image recording. When the feature amount continuously increases corresponding to the increase in the number of printed sheets, it can be determined by extrapolation whether or not the increase exceeds 2.0 given as an example.

In other words, as shown in FIG. 14A, when the change in the index shows an increasing tendency such as a monotonous increase with respect to the change in the number of printed sheets, the number of printed sheets t ₁ with the index exceeding 2.0 is predicted. can do. For example, from t ₀ the number of printed sheets is shown in FIG. 14 (a) to t ₁ -1 is ejection failure of the head normal image recording without generating is performed, the discharge abnormality of the printed sheets is t ₁ head Since it can be predicted that image generation will occur, image recording is performed from t ₀ to t ₁ −1, and when the number of prints reaches t ₁ , the _first image recording is not performed and the process proceeds to a maintenance process. .

  On the other hand, as shown in FIG. 14 (b), when the change of the index shows a tendency to change with a change within a certain range with respect to the change of the number of printed sheets, it is determined that the index does not exceed 2.0. The occurrence of abnormal discharge is not predicted. When storing the index, the number of printed sheets and the calculated value of the index may be stored in association with each other, or the number of printed sheets and the change amount of the index may be stored in association with each other. In addition, the calculated value (change amount) of the index may be stored for each operation time instead of the number of printed sheets.

<Detection of abnormal transfer recording>
Next, the transfer recording abnormality detection executed after the ejection abnormality separation determination will be described. FIG. 15 is a flowchart showing a flow of control including detection of abnormal transfer recording in the image recording control of the inkjet recording apparatus 10 shown in FIG. In the transfer recording abnormality detection described below, the same or similar parts as those in the discharge abnormality detection and discharge abnormality prediction processing described above are denoted by the same reference numerals, and the description thereof is omitted.

  In the transfer recording abnormality determination, ejection failure prediction determination based on the chart image (charts 102 and 104 in FIG. 7). After the density determination is performed, the process includes a step of detecting abnormalities such as transfer defects, solvent removal, and ink skipping by storing and sequentially comparing the non-defective printed image and the printed image.

  In other words, the reading result of the master chart image as a reference is stored in a predetermined memory (for example, the image memory 74 in FIG. 6), and the reading image read for each image recording and the reading result of the master chart image are stored. By comparison, it is determined whether there is transfer recording abnormality, solvent removal abnormality, dust or the like. The contents of the master chart image are the same as those of the chart 102 shown in FIG.

  That is, in the flowchart shown in FIG. 15, when image recording is started (step S10), a master chart storing step is executed. Each process of the master chart storage process is shown in FIG.

  When the master chart storage process shown in FIG. 16 is started (step S220), the master chart is recorded on the recording medium 14 through a predetermined process (step S221), and the master chart is stored in the inline scanner 34 (see FIG. 1). (Step S222), and is stored in a predetermined memory as a master chart image (determination reference image of the read image) (step S224), and the master chart storing step is terminated (step S226). Note that the master chart storage process is performed in a state where no solvent removal abnormality, transfer recording abnormality, dust or the like has occurred, and therefore is executed at a timing immediately after the initialization process or immediately after the maintenance process of the entire apparatus.

  Next, when image data is received (step S10), the chart 102 (104) is read for each image recording through steps S12 to S20, and the process proceeds to step S202. In step S202, the chart 102 for each image recording is compared with a master chart stored in advance, and the presence / absence of an image abnormality is determined. Specifically, the density value of the chart 102 is compared with the density value of the master chart.

  For example, when the color reproduction region is a reproduction region of 15 (white) to 215 (black), the image digital data read by the CCD included in the in-line scanner 34, the density value of the solid portion a of the K portion 102K of the master chart are When the density value of the K portion 102K of the chart 102 continuously read is distributed from 183 to 199 and the density value tends to gradually increase (or decrease) with respect to 190, the density Correction is performed in a direction in which the density value decreases (increases) from the change tendency of the value.

  That is, the master chart and the continuously read chart are sequentially compared in the memory. If a foreign matter with a difference larger than a preset size is detected in the image, it is determined that there is an image defect due to transfer recording abnormality, solvent removal processing abnormality, dust adhesion, etc. The

In other words, the density value of the chart 102 sequentially read for each image recording is stored for each color, and the difference between the density value and the density value of the master chart is obtained, and the difference becomes a predetermined threshold value. In the case of exceeding, it is determined that an image defect due to transfer recording abnormality, solvent removal processing abnormality, dust or the like has occurred.

  If it is determined in step S202 that the difference is within the reference range through the above-described processing (YES determination), the process proceeds to step S26, and is output as a non-defective print, and the process returns to step S12.

  On the other hand, when it is determined in step S202 that the difference exceeds the reference range (NO determination), maintenance of the intermediate transfer body 12, the solvent removal processing unit 22, and the transfer recording unit 28 is performed (step S204).

  In the above-described image abnormality detection method, the discharge abnormality detection shown in FIG. 9 (or FIG. 12) and the transfer recording abnormality detection shown in FIG. 15 are combined to cause the discharge abnormality based on the read result of the image after transfer recording. It is possible to separate whether an image abnormality has occurred or an image abnormality due to a transfer recording abnormality has occurred, and maintenance processing is executed in accordance with each abnormality cause. Further, by combining the ejection abnormality prediction shown in FIG. 13, the head 50 can be subjected to a maintenance process before the ejection abnormality occurs.

  It is also possible to measure the color tone using the three-color color line CCD, that is, measure the balance of K, C, M, and Y density, while detecting the ejection abnormality and the transfer recording abnormality as described above. It is.

  According to the inkjet recording apparatus 10 configured as described above, when performing single-pass image recording in the intermediate transfer type inkjet recording apparatus 10 equipped with a line-type head, the image after transfer recording is read, and the read result is differentiated. By performing density unevenness emphasis processing such as processing and high-frequency filter processing, head ejection defects and defects caused by transfer are separated and detected, so abnormalities related to the head and abnormalities caused by processes such as image transfer can be detected. By detecting at one place, a member related to image reading can be omitted. Further, by separating and detecting the ejection abnormality of the head 50 and other abnormality such as transfer recording, the system control unit 72 of the image forming apparatus (inkjet recording apparatus 10) starts to the maintenance control unit 90 in order to recover the ejection failure. It is possible to determine at an appropriate timing whether to transmit a signal or to transmit an adjustment signal to the solvent application / removal controller. Usually, since the maintenance process reduces the operating rate of the apparatus, it is preferable in terms of apparatus design to be a process only when a discharge failure is detected.

  Furthermore, since the occurrence of a printing defect is predicted from the transition using image data in which vertical stripes (stripes along the y direction shown in FIG. 7) are emphasized by image processing, the image forming unit (of FIG. 1) is detected. No defective printed matter is produced between the heads 18K, 18C, 18M, 18Y), and no waste paper is produced. In other words, the number of recordings in which an ejection abnormality occurs is predicted based on the transition of the image feature amount index read for each image recording, and the head is subjected to maintenance processing immediately before the number of recordings in which the ejection abnormality occurs. Therefore, an image abnormality due to an ejection abnormality does not occur, and the recording medium is not wasted.

  After predicting vertical streaks with an image with emphasized vertical streaks, transfer defects are detected by comparing them with non-defective products after subtracting the vertical streak component from the image. It is also possible to detect with high accuracy.

After the abnormality is emphasized by image processing for each ink, paper, device, and head, a feature amount is extracted and stored as reference data, so the feature is stored and learned for each ink material, paper, and machine difference. By doing so, it becomes possible to improve the prediction accuracy of ejection failure.

Second Embodiment
A second embodiment of abnormality detection shown in this example will be described. In the second embodiment, predetermined signal processing is performed on the read result of the chart, and ejection abnormality and other abnormality are separated based on the chart subjected to the signal processing.

  FIG. 17 is a flowchart showing a control flow of abnormality detection according to the second embodiment in the control flow of image recording of the ink jet recording apparatus 10 shown in FIG. Note that, in the second embodiment, the same or similar parts as those of the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  In this example, Fourier transform processing is performed on the chart read in step S18 in each of the x direction and the y direction (see FIG. 7), and transfer recording abnormality and ejection abnormality are discriminated based on the processing result. It is configured.

  That is, when the chart image is read in step S18 shown in FIG. 17, the process proceeds to step S300. In step S300, a one-dimensional Fourier transform process is performed in the conveyance direction (y direction) and the conveyance orthogonal direction (x direction), and the relationship between the spatial frequency and the density unevenness intensity (intensity) is obtained in the x direction, and the y direction. The relationship between the intensity and the spatial frequency is obtained (see FIG. 10). In step S300, enhancement processing such as differentiation processing may be used in combination.

  Next, the process proceeds to step S302, where it is determined whether or not the intensity in the x direction and the intensity in the y direction are equal to or greater than a setting limit value of the intensity for a preset frequency. In step S302, when the intensity in the x direction and the intensity in the y direction are less than a predetermined limit value of the intensity with respect to a preset frequency (NO determination), it is output as a non-defective printed matter (step S26), and the process returns to step S12.

  On the other hand, if it is determined that the intensity in the x direction and the intensity in the y direction are equal to or greater than the intensity setting limit value for a preset frequency (YES determination), the process proceeds to step S304. In step S304, the intensity in the x direction and the intensity in the y direction are compared, and the process proceeds to step S306 to determine whether there is an ejection abnormality or an abnormality other than the ejection abnormality, such as a transfer recording abnormality, based on the comparison result in step S304. To do.

  That is, when the relationship between the spatial frequency and the intensity approximates in the x direction and the y direction, it can be determined that the defect does not depend on the direction, that is, a transfer recording abnormality. On the other hand, when the intensity in the x direction is clearly higher than that in the y direction, it can be determined that there is a discharge abnormality.

  If it is determined in step S306 that the strength in the x direction> the strength in the y direction, that is, ejection failure (YES determination), the process proceeds to step S24, and the head maintenance process is executed. On the other hand, if it is determined in step S306 that the intensity in the x direction <the intensity in the y direction, that is, transfer recording abnormality or the like (NO determination), the process proceeds to step S216, where the intermediate transfer body 12, the solvent removal processing unit 22, and transfer recording are performed. The maintenance process of the unit 28 is executed.

According to the second embodiment described above, when the read image of the chart 102 is subjected to a one-dimensional Fourier transform process in each of the x direction and the y direction, and the intensity is equal to or greater than a predetermined reference value (limit value). Judged as an abnormal image. Further, when it is determined that the image is abnormal, the intensity in the x direction is compared with the intensity in the y direction, and based on the comparison result, the image abnormality is caused by an ejection abnormality or an abnormality other than the ejection abnormality. Judge whether it is a thing. Therefore, it is possible to properly determine ejection abnormalities and transfer recording abnormalities other than ejection abnormalities, solvent removal abnormalities, and adhesion of dust to the intermediate transfer member, and appropriate maintenance processing can be performed according to the cause of the abnormality. Become.

[Modification]
FIG. 18 is an overall configuration diagram of an inkjet recording apparatus 200 according to a modification of the above-described embodiment. In FIG. 18, parts that are the same as or similar to those in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted.

  18 uses a drum-shaped intermediate transfer body 212 instead of the belt-shaped intermediate transfer body 12 shown in FIG. That is, a primary image is formed by the ink ejected from the printing unit 18 while the intermediate transfer member 212 is rotated counterclockwise in FIG. 18, and the recording medium 14 is placed between the intermediate transfer member 212 and the transfer drum 228. By pressing, the primary image is transferred and recorded on the recording medium 14. In the modification shown in FIG. 18, an inline inline scanner 34 is provided at the rear stage of the transfer drum in the conveyance path of the recording medium 14.

  That is, the shape of the intermediate transfer member may be a belt or a drum. It is also possible to apply a flat type intermediate transfer member.

1 is an overall configuration diagram of an ink jet recording apparatus according to an embodiment of the present invention. FIG. 1 is a plan view of a main part around a printing unit of the ink jet recording apparatus shown in FIG. Plane perspective view showing a configuration example of the head shown in FIG. Sectional view along line 4-4 in FIG. Schematic diagram showing the configuration of an ink supply system in the ink jet recording apparatus shown in FIG. 1 is a principal block diagram showing the system configuration of the ink jet recording apparatus shown in FIG. Schematic diagram of the recording medium on which the chart is recorded The figure explaining the chart of FIG. The flowchart which shows the flow of discharge abnormality detection of this invention Diagram explaining the relationship between spatial frequency and intensity Schematic diagram of the head Modified example of the flowchart shown in FIG. The flowchart which shows the flow of the discharge abnormality prediction of this invention Diagram explaining ejection failure prediction Flowchart showing the flow of detection of abnormal transfer recording of the present invention The flowchart which shows the flow of control of the master chart memory | storage process of FIG. The flowchart which shows the flow of abnormality detection which concerns on 2nd Embodiment of this invention. The whole block diagram of the inkjet recording device which concerns on the modification of this invention

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,200 ... Inkjet recording device, 12 ... Intermediate transfer body, 14 ... Recording medium, 18 ... Printing part, 22 ... Solvent removal processing part, 28, 228 ... Transfer recording part, 34 ... Inline sensor, 72 ... System control part, 74: Image memory, 90: Maintenance control unit, 92: Maintenance drive unit, 94: Image processing unit

Claims (9)

An image recording apparatus comprising transfer recording means for transferring and recording a primary image formed on an intermediate transfer member by an image forming liquid discharged from a nozzle of a recording head onto a recording medium,
Image detection means for converting the image recorded on the recording medium into electronic data;
Image processing means for determining whether the transfer recording means is a transfer abnormality or the recording head discharge abnormality by performing predetermined image processing on the image data converted into electronic data by the image detection means;
An image recording apparatus comprising: The primary image formed on the intermediate transfer member includes a solid image formed around the recorded image,
The image processing means performs a predetermined image process on the image data of the solid image converted into electronic data by the image detection means, thereby causing a transfer abnormality of the transfer recording means or a discharge abnormality of the recording head. The image recording apparatus according to claim 1, wherein:   The image processing means performs image processing for emphasizing density unevenness in the x direction orthogonal to the y direction corresponding to the moving direction of the intermediate transfer member on the recording medium on the image data obtained by converting the solid image into electronic data. The image recording apparatus according to claim 2.   The image processing means performs differential processing on image data obtained by converting the solid image into electronic data in an x direction orthogonal to a y direction corresponding to a moving direction of the intermediate transfer member on the recording medium. The image recording apparatus according to claim 2.   The image recording apparatus according to claim 2, wherein the image processing unit performs a filtering process using a high frequency filter on image data obtained by converting the solid image into electronic data. In the primary image formed on the intermediate transfer member, a dot group in which a plurality of dots are arranged around the recording image in a direction parallel to the moving direction of the intermediate transfer member is perpendicular to the moving direction of the intermediate transfer member. Including test patterns arranged at intervals,
6. The nozzle according to claim 1, wherein the image processing unit identifies a nozzle having an ejection abnormality by performing predetermined image processing on the image data of the test pattern converted into electronic data by the image detection unit. The image recording apparatus according to any one of the above.   The image processing means has a mechanism for determining whether or not an image abnormality due to an ejection abnormality reaches a visual recognition level from a transition of a result of the predetermined image processing, and changing a process based on the determination result. The image recording apparatus according to any one of claims 1 to 6.   The image processing means performs one-dimensional Fourier transform processing on image data obtained by converting the solid image into electronic data in the y direction corresponding to the moving direction of the intermediate transfer member on the recording medium, and is orthogonal to the y direction. The recording head is subjected to a one-dimensional Fourier transform process in the x direction, and the result of the one-dimensional Fourier transform process in the x direction and the one-dimensional Fourier transform process in the y direction The image recording apparatus according to claim 1, wherein it is determined whether or not the discharge is abnormal. An abnormality detection method in an image recording apparatus for transferring and recording a primary image formed on an intermediate transfer member by an image forming liquid discharged from a nozzle of a recording head onto a recording medium,
An image recorded on the recording medium is converted into electronic data, and a predetermined image processing is performed on the image data converted into the electronic data, thereby determining whether the recording is abnormal or ejection failure of the recording head. An abnormality detection method characterized by the above.

Images