JP2020023107A - Inkjet recording device and control method for the same - Google Patents

Abstract

To achieve a method in which even if a difference of brightness values between ink and base color of a recording medium is small, a pattern to be recorded by ink can be detected with good accuracy and a recording position can be adjusted.SOLUTION: An inkjet recording device comprises: correcting means that corrects a signal corresponding to a first color using first shading data on the basis of a white reference and corrects a signal corresponding to a second color using second shading data on the basis of a base color of a recording medium and a color of an area formed using prescribed ink, with respect to an image of a chart; specifying means that specifies areas formed using a plurality of ink respectively in the image of the chart, using the signal corrected by the correcting means; and calculating means that calculates positional shift amounts of a recording head on the basis of positions of the areas specified by the specifying means.SELECTED DRAWING: Figure 15

Description

  The present invention relates to an inkjet recording apparatus and a control method thereof.

  2. Description of the Related Art There is known an inkjet recording apparatus provided with a so-called full-line type recording head having a recording width corresponding to the width of a recording medium. In an inkjet recording apparatus having such a recording head, an image can be recorded on almost the entire surface of the recording medium by moving the recording head once relative to the recording medium. In a recording apparatus provided with a full-line type recording head, an error may occur in a mounting position of the recording head or a relative mounting position between a plurality of recording heads. This error causes a shift in the ink landing position (adhering position) on the recording medium, and causes a reduction in recording quality. Hereinafter, such a process of correcting the displacement of the ink landing position is referred to as “print position adjustment”.

  For example, in the recording position adjustment method disclosed in Patent Document 1, a print pattern is read using a reading device such as a scanner, and the pattern position is calculated from the read image using template matching. Further, it describes that a relative position between patterns is calculated, and a recording position is adjusted based on the relative position.

JP 2012-166385 A

  However, in position detection using template matching, when the difference in luminance value between the base color of the recording medium and the ink color is not sufficient, the pattern detection accuracy is reduced due to the influence of irregularities and scratches on the surface of the recording medium. .

  SUMMARY OF THE INVENTION It is an object of the present invention to improve the accuracy of print position adjustment by accurately detecting a pattern printed with ink even when the difference in luminance value between the ink and the base color of the print medium is small. .

  In order to solve the above problems, the present invention has the following configuration. That is, an ink jet recording apparatus having a recording head of an ink jet recording system and a reading unit, wherein a first shading data is created by using an image obtained by reading a white reference by the reading unit. Forming means, a first obtaining means for obtaining a base image of the recording medium by reading the recording medium with the reading means, and a plurality of inks formed on the recording medium by the recording head. A second obtaining unit that obtains an image formed with a predetermined ink among the plurality of inks by reading the chart with the reading unit; and a second image forming unit that is formed with the base image and the predetermined ink. A second creating unit that creates second shading data using the image, and an image of the chart read by the reading unit. On the other hand, correction means for correcting a signal corresponding to a first color using the first shading data and correcting a signal corresponding to a second color using the second shading data, and the correction means A specifying unit that specifies a region formed by each of the plurality of inks in the image of the chart using the signal corrected by the control unit; and the recording head based on a position of the region specified by the specifying unit. And a calculating means for calculating the amount of positional deviation.

  According to the present invention, it is possible to detect a pattern recorded with ink with high accuracy even when the difference in luminance between the ink and the base color of the recording medium is small.

FIG. 1 is a schematic diagram of a recording system. FIG. 3 is a perspective view of a recording unit. FIG. 3 is an explanatory diagram of a displacement mode of the recording unit in FIG. 2. FIG. 2 is a block diagram of a control system of the recording system in FIG. 1. FIG. 2 is a block diagram of a control system of the recording system in FIG. 1. FIG. 2 is an explanatory diagram of an operation example of the recording system in FIG. 1. FIG. 2 is an explanatory diagram of an operation example of the recording system in FIG. 1. Schematic view of the inspection unit 9B in FIG. 1 (from the top of the apparatus) Schematic view of the inspection unit 9B in FIG. 1 (from the front of the apparatus) FIG. 4 is a diagram for explaining a test pattern for correcting a head position shift according to the first embodiment. FIG. 4 is a diagram illustrating an example of a pattern matching pattern according to the first embodiment. FIG. 3 is a diagram for explaining a pattern layout according to the first embodiment. FIG. 5 is a diagram for explaining a method for calculating the amount of displacement of the recording head according to the first embodiment. FIG. 4 is a diagram for explaining detection of a detection mark of a pattern corresponding to a recording chip. FIG. 4 is a diagram illustrating a flow of a shift amount calculation according to the first embodiment. FIG. 9 is a view for explaining a test pattern for correcting a head position shift according to the second embodiment. FIG. 9 is a view showing an example of a pattern matching pattern according to the second embodiment. FIG. 9 is a view for explaining a pattern layout according to the second embodiment. FIG. 9 is a view for explaining a method of calculating a shift amount of a print head according to the second embodiment.

  An embodiment of the present invention will be described with reference to the drawings. In each of the drawings, arrows X and Y indicate a horizontal direction and are orthogonal to each other. Arrow Z indicates the vertical direction.

[Recording system]
FIG. 1 is a front view schematically showing a recording system 1 according to an embodiment of the present invention. The recording system 1 is a sheet-fed inkjet printer that manufactures a recorded material P ′ by transferring an ink image onto a recording medium P via a transfer body 2. The recording system 1 includes a recording device 1A and a transport device 1B. In the present embodiment, the X direction, the Y direction, and the Z direction indicate the width direction (full length direction), the depth direction, and the height direction of the recording system 1, respectively. The recording medium P is transported in the X direction.

  It should be noted that “recording” is not limited to forming significant information such as characters and figures, but also includes forming images, patterns, and patterns on a recording medium or processing the medium regardless of significance. A case is also included, and it does not matter whether or not it has been exposed so that humans can perceive it visually. Further, in the present embodiment, sheet-shaped paper is assumed as the “recording medium”, but may be cloth, plastic film, or the like.

  The components of the ink are not particularly limited, but in the present embodiment, it is assumed that an aqueous pigment ink containing a pigment as a coloring material, water, and a resin is used.

[Recording device]
A recording apparatus 1A as an inkjet recording apparatus includes a recording unit 3, a transfer unit 4, peripheral units 5A to 5D, and a supply unit 6.

[Recording unit]
The recording unit 3 includes a plurality of recording heads 30 of an ink jet recording type and a carriage 31. Please refer to FIG. 1 and FIG. FIG. 2 is a perspective view of the recording unit 3. The recording head 30 discharges liquid ink onto the transfer body 2 to form an ink image of a recording image on the transfer body 2.

  In the case of the present embodiment, each recording head 30 is a full line head extending in the Y direction, and the nozzles are arranged in a range covering the width of the image recording area of the recording medium of the maximum usable size. I have. The recording head 30 has an ink ejection surface with nozzles opened on the lower surface thereof, and the ink ejection surface faces the surface of the transfer body 2 via a minute gap (for example, several mm). In the case of the present embodiment, since the transfer body 2 is configured to move cyclically on a circular orbit, the plurality of recording heads 30 are radially arranged.

  Each nozzle is provided with a discharge element. The ejection element is, for example, an element that generates pressure in the nozzle to eject ink in the nozzle, and a known inkjet head technology of an inkjet printer can be applied. As the ejection element, for example, an element that ejects ink by causing film boiling in the ink by an electro-thermal converter to form a bubble, an element that ejects ink by an electro-mechanical converter, and an ink that utilizes static electricity to discharge ink. An element that discharges the ink may be used. From the viewpoint of high-speed and high-density recording, a discharge element using an electro-thermal converter can be used.

  In the case of the present embodiment, nine recording heads 30 are provided. Each recording head 30 ejects different types of ink. The different types of ink are, for example, inks having different color materials, such as yellow ink, magenta ink, cyan ink, and black ink. One recording head 30 discharges one type of ink, but one recording head 30 may discharge a plurality of types of ink. When a plurality of recording heads 30 are provided in this manner, some of them may eject ink (for example, clear ink) containing no coloring material.

  The carriage 31 supports a plurality of recording heads 30. Each recording head 30 has an end on the ink ejection surface side fixed to the carriage 31. Thereby, the gap between the ink ejection surface and the surface of the transfer body 2 can be maintained more precisely. The carriage 31 is configured to be displaceable while mounting the recording head 30 under the guidance of the guide member RL. In the case of the present embodiment, the guide members RL are rail members extending in the Y direction, and a pair of guide members RL are provided apart from each other in the X direction. A slide portion 32 is provided on each side of the carriage 31 in the X direction. The slide portion 32 engages with the guide member RL and slides in the Y direction along the guide member RL.

  FIG. 3 is a diagram schematically illustrating a displacement mode of the recording unit 3 and a right side surface of the recording system 1. At the rear of the recording system 1, a recovery unit 12 is provided. The recovery unit 12 has a mechanism for recovering the ejection performance of the recording head 30. Examples of such a mechanism include a cap mechanism for capping the ink ejection surface of the recording head 30, a wiper mechanism for wiping the ink ejection surface, and a suction mechanism for suctioning the ink in the recording head 30 from the ink ejection surface under a negative pressure. be able to.

  The guide member RL extends from the side of the transfer body 2 to the recovery unit 12. The recording unit 3 can be displaced between a discharge position POS1 indicated by the solid line and the recovery position POS3 indicated by the broken line by the guidance of the guide member RL. Is moved by

  The ejection position POS1 is a position at which the recording unit 3 ejects ink to the transfer body 2, and is a position where the ink ejection surface of the recording head 30 faces the surface of the transfer body 2. The recovery position POS3 is a position retracted from the ejection position POS1, and is a position where the recording unit 3 is located on the recovery unit 12. The recovery unit 12 can execute a recovery process for the recording head 30 when the recording unit 3 is located at the recovery position POS3. In the case of the present embodiment, the recovery processing can be executed even during the movement of the recording unit 3 before reaching the recovery position POS3. There is a preliminary recovery position POS2 between the ejection position POS1 and the recovery position POS3. The recovery unit 12 can execute a preliminary recovery process on the print head 30 at the preliminary recovery position POS2 while the print head 30 is moving from the ejection position POS1 to the recovery position POS3. Note that the recovery process may be individually executable for each of the plurality of recording heads 30, or may be collectively executable for some of the recording heads 30.

[Transfer unit]
The transfer unit 4 will be described with reference to FIG. The transfer unit 4 includes a transfer drum (transfer cylinder) 41 and an impression cylinder 42. Each of these bodies is a rotating body that rotates around a rotation axis in the Y direction, and has a cylindrical outer peripheral surface. In FIG. 1, the arrows shown in the figures of the transfer drum 41 and the impression cylinder 42 indicate the rotation directions thereof, and the transfer drum 41 rotates clockwise and the impression cylinder 42 rotates counterclockwise.

  The transfer drum 41 is a support that supports the transfer body 2 on its outer peripheral surface. The transfer body 2 is provided on the outer peripheral surface of the transfer drum 41 continuously or intermittently in the circumferential direction. When provided continuously, the transfer body 2 is formed in an endless belt shape. When provided intermittently, the transfer body 2 is formed into a plurality of segments in the form of a strip having ends, and each segment can be arranged on the outer peripheral surface of the transfer drum 41 in an arc at an equal pitch.

  Due to the rotation of the transfer drum 41, the transfer body 2 cyclically moves on a circular orbit. By the rotation phase of the transfer drum 41, the position of the transfer body 2 can be distinguished into a pre-ejection processing region R1, an ejection region R2, post-ejection processing regions R3 and R4, a transfer region R5, and a post-transfer processing region R6. The transcript 2 passes through these regions cyclically.

  The pre-ejection processing area R1 is an area where pre-processing is performed on the transfer body 2 before the recording unit 3 ejects ink, and is an area where processing is performed by the peripheral unit 5A. In the case of the present embodiment, a reaction liquid is applied. The ejection region R2 is a formation region where the recording unit 3 ejects ink to the transfer body 2 to form an ink image. The post-ejection processing areas R3 and R4 are processing areas for performing processing on the ink image after ink ejection, the post-ejection processing area R3 is an area where processing is performed by the peripheral unit 5B, and the post-ejection processing area R4 is a peripheral unit 5C. Is an area where the process is performed. The transfer area R5 is an area where the transfer unit 4 transfers the ink image on the transfer body 2 to the recording medium P. The post-transfer processing region R6 is a region where post-processing is performed on the transfer body 2 after the transfer, and is a region where processing by the peripheral unit 5D is performed.

  In the case of the present embodiment, the discharge region R2 is a region having a certain section in the rotation direction. The sections of the other areas R1, R3 to R6 are narrower than the discharge area R2. In the case of the present embodiment, in the case of a clock face, the pre-ejection processing region R1 is located at approximately 10:00, the ejection region R2 is approximately in the range from 11:00 to 1:00, and the post-ejection processing region R3 is approximately. The position is at 2 o'clock, and the post-ejection processing region R4 is approximately at 4 o'clock. The transfer region R5 is located at approximately 6 o'clock, and the post-transfer processing region R6 is approximately at 8 o'clock.

  The transfer body 2 may be composed of a single layer, but may be a laminate of a plurality of layers. In the case of a configuration with a plurality of layers, for example, it may include three layers of a surface layer, an elastic layer, and a compression layer. The surface layer is the outermost layer having an image forming surface on which an ink image is formed. By providing the compression layer, the compression layer absorbs the deformation, disperses the fluctuation with respect to the local pressure fluctuation, and can maintain the transferability even at the time of high-speed recording. The elastic layer is a layer between the surface layer and the compression layer.

  Various materials such as resin and ceramic can be used as appropriate for the material of the surface layer, but a material having a high compression modulus in terms of durability and the like can be used. Specific examples include an acrylic resin, an acrylic silicone resin, a fluorine-containing resin, and a condensate obtained by condensing a hydrolyzable organic silicon compound. The surface layer may be subjected to a surface treatment in order to improve the wettability of the reaction solution, the transferability of an image, and the like. Examples of the surface treatment include a frame treatment, a corona treatment, a plasma treatment, a polishing treatment, a roughening treatment, an active energy ray irradiation treatment, an ozone treatment, a surfactant treatment, and a silane coupling treatment. You may combine these two or more. Also, an arbitrary surface shape can be provided on the surface layer.

  Examples of the material of the compression layer include acrylonitrile-butadiene rubber, acrylic rubber, chloroprene rubber, urethane rubber, and silicone rubber. At the time of molding such a rubber material, a predetermined amount of a vulcanizing agent, a vulcanization accelerator and the like are blended, and further, a filler such as a foaming agent, hollow fine particles or salt is blended as necessary, and the porous rubber material is blended. It may be. Thereby, since the bubble portion is compressed with a change in volume in response to various pressure fluctuations, deformation in directions other than the compression direction is small, and more stable transferability and durability can be obtained. Porous rubber materials include those having a continuous pore structure in which each pore is continuous with each other and those having an independent pore structure in which each pore is independent, but any structure may be used. May be.

  Various materials such as resin and ceramic can be used as appropriate for the member of the elastic layer. Various elastomer materials and rubber materials can be used in terms of processing characteristics and the like. Specific examples include fluorosilicone rubber, phenylsilicone rubber, fluorine rubber, chloroprene rubber, urethane rubber, nitrile rubber, and the like. In addition, ethylene propylene rubber, natural rubber, styrene rubber, isoprene rubber, butadiene rubber, ethylene / propylene / butadiene copolymer, nitrile butadiene rubber and the like can be mentioned. In particular, silicone rubber, fluorosilicone rubber, and phenylsilicone rubber are advantageous in terms of dimensional stability and durability because of their low compression set. In addition, the change in elastic modulus due to temperature is small, which is advantageous in terms of transferability.

  Various adhesives and double-sided tapes can be used between the surface layer and the elastic layer and between the elastic layer and the compression layer to fix them. Further, the transfer body 2 may include a reinforcing layer having a high compression elastic modulus in order to suppress lateral elongation when the transfer body 41 is mounted on the transfer drum 41 and to maintain stiffness. Further, a woven fabric may be used as the reinforcing layer. The transfer body 2 can be produced by arbitrarily combining the layers made of the above materials.

  The outer peripheral surface of the impression cylinder 42 is pressed against the transfer body 2. At least one grip mechanism for holding the leading end of the recording medium P is provided on the outer peripheral surface of the impression cylinder 42. A plurality of grip mechanisms may be provided apart from each other in the circumferential direction of the impression cylinder 42. The ink image on the transfer body 2 is transferred when the recording medium P passes through a nip portion between the impression cylinder 42 and the transfer body 2 while being conveyed in close contact with the outer peripheral surface of the impression cylinder 42. A drive source such as a motor for driving the transfer drum 41 and the impression cylinder 42 is common to these, and the driving force can be distributed by a transmission mechanism such as a gear mechanism.

[Peripheral unit]
The peripheral units 5A to 5D are arranged around the transfer drum 41. In the case of the present embodiment, the peripheral units 5A to 5D are an applying unit, an absorbing unit, a heating unit, and a cleaning unit in this order.

  The application unit 5A is a mechanism that applies a reaction liquid onto the transfer body 2 before the recording unit 3 discharges ink. The reaction liquid is a liquid containing a component that increases the viscosity of the ink. Here, increasing the viscosity of the ink means that the colorant or resin constituting the ink chemically reacts or physically adsorbs when it comes into contact with a component that increases the viscosity of the ink. That is, an increase in the viscosity of the ink is observed. In order to increase the viscosity of the ink, not only the case where the viscosity of the entire ink is increased, but also the case where the viscosity is locally increased due to aggregation of a part of the ink component such as a coloring material or a resin. Is also included.

  The component that increases the viscosity of the ink is not particularly limited, such as metal ions and a polymer coagulant, but a substance that causes a change in the pH of the ink and agglomerates the coloring material in the ink can be used. Can be used. Examples of the reaction liquid application mechanism include a roller, a recording head, a die coating device (die coater), and a blade coating device (blade coater). If the reaction liquid is applied to the transfer member 2 before the ink is ejected to the transfer member 2, the ink that has reached the transfer member 2 can be immediately fixed. Thus, bleeding in which adjacent inks are mixed can be suppressed.

  The absorption unit 5B is a mechanism that absorbs a liquid component from an ink image on the transfer body 2 before transfer. By reducing the liquid component of the ink image, bleeding of an image recorded on the recording medium P can be suppressed. If the reduction of the liquid component is described from a different viewpoint, it can be expressed that the ink constituting the ink image on the transfer body 2 is concentrated. Concentrating the ink means that a decrease in the liquid component contained in the ink causes an increase in the content ratio of the solid component such as a coloring material and a resin contained in the ink to the liquid component.

  The absorption unit 5B includes, for example, a liquid absorbing member that comes into contact with the ink image and reduces the amount of the liquid component of the ink image. The liquid absorbing member may be formed on the outer peripheral surface of the roller, or the liquid absorbing member may be formed in an endless sheet shape and run cyclically. In terms of protecting the ink image, the liquid absorbing member may be moved in synchronization with the transfer member 2 by setting the moving speed of the liquid absorbing member to be the same as the peripheral speed of the transfer member 2.

  The liquid absorbing member may include a porous body that comes into contact with the ink image. In order to suppress the adhesion of the ink solids to the liquid absorbing member, the pore diameter of the porous body on the surface in contact with the ink image may be 10 μm or less. Here, the pore diameter indicates an average diameter, and can be measured by a known means, for example, a mercury intrusion method, a nitrogen adsorption method, SEM image observation, or the like. The liquid component is not particularly limited as long as it does not have a fixed shape, has fluidity, and has a substantially fixed volume. For example, water, an organic solvent, and the like contained in the ink and the reaction liquid are examples of the liquid component.

  The heating unit 5C is a mechanism for heating the ink image on the transfer body 2 before the transfer. By heating the ink image, the resin in the ink image melts, and the transferability to the recording medium P is improved. The heating temperature can be equal to or higher than the minimum film forming temperature (MFT) of the resin. The MFT can be measured by a generally known method, for example, each device based on JIS K 6828-2: 2003 or ISO2115: 1996. From the viewpoint of transferability and image fastness, heating may be performed at a temperature higher than MFT by 10 ° C. or more, and further, may be performed at a temperature higher by 20 ° C. or more. As the heating unit 5C, for example, a known heating device such as various lamps such as infrared rays, a hot air fan and the like can be used. In terms of heating efficiency, an infrared heater can be used.

  The cleaning unit 5D is a mechanism for cleaning the transfer body 2 after the transfer. The cleaning unit 5D removes ink remaining on the transfer member 2, dust on the transfer member 2, and the like. As the cleaning unit 5D, a known method such as a method of bringing a porous member into contact with the transfer member 2, a method of rubbing the surface of the transfer member 2 with a brush, and a method of scraping the surface of the transfer member 2 with a blade is used as appropriate. Can be. The cleaning member used for cleaning may have a known shape such as a roller shape or a web shape.

  As described above, in the present embodiment, the application unit 5A, the absorption unit 5B, the heating unit 5C, and the cleaning unit 5D are provided as peripheral units, but a cooling function of the transfer body 2 is provided to some of these units, or , A cooling unit may be added. In the present embodiment, the temperature of the transfer body 2 may increase due to the heat of the heating unit 5C. If the ink image exceeds the boiling point of water, which is the main solvent of the ink, after the recording unit 3 discharges the ink onto the transfer member 2, the absorption performance of the liquid component by the absorption unit 5B may be reduced. By cooling the transfer body 2 so that the ejected ink is maintained at a temperature lower than the boiling point of water, the absorption performance of the liquid component can be maintained.

  The cooling unit may be a blowing mechanism for blowing air to the transfer body 2 or a mechanism for bringing a member (for example, a roller) into contact with the transfer body 2 and cooling the member by air or water cooling. Further, a mechanism for cooling the cleaning member of the cleaning unit 5D may be used. The cooling timing may be a period after the transfer in the transfer region R5 and before the application of the reaction liquid in the pre-ejection processing region R1.

[Supply unit]
The supply unit 6 is a mechanism that supplies ink to each recording head 30 of the recording unit 3. The supply unit 6 may be provided on the rear side of the recording system 1. The supply unit 6 includes a storage unit TK for storing ink for each type of ink. The storage unit TK may be configured by a main tank and a sub tank. Further, in the storage unit TK, a tank of a different size may be used or a different number of tanks may be provided for each type of ink. Each storage section TK and each recording head 30 communicate with each other through a flow path 6a, and ink is supplied from the storage section TK to the recording head 30. The flow path 6a may be a flow path for circulating ink between the storage unit TK and the recording head 30, and the supply unit 6 may include a pump or the like for circulating ink. A degassing mechanism for degassing bubbles in the ink may be provided in the middle of the flow path 6a or in the storage part TK. A valve for adjusting the ink pressure and the atmospheric pressure may be provided in the middle of the flow path 6a or in the storage section TK. The height of the reservoir TK and the recording head 30 in the Z direction may be designed such that the ink liquid level in the reservoir TK is lower than the ink ejection surface of the recording head 30.

[Transport device]
The transport device 1B is a device that feeds the recording medium P to the transfer unit 4 and discharges the recorded material P ′ on which the ink image has been transferred from the transfer unit 4. The transport device 1B includes a feed unit 7, a plurality of transport cylinders 8, 8a, two sprockets 8b, a chain 8c, and a recovery unit 8d. In FIG. 1, the arrows inside the figures of the respective components of the transport device 1B indicate the rotation direction of the components, and the outer arrows indicate the transport path of the recording medium P or the recorded material P ′. The recording medium P is transported from the feeding unit 7 to the transfer unit 4, and the recorded matter P 'is transported from the transfer unit 4 to the collection unit 8d. The feed unit 7 may be referred to as an upstream side in the transport direction, and the collection unit 8d may be referred to as a downstream side.

  The feeding unit 7 includes a stacking unit on which a plurality of recording media P are stacked, and includes a feeding mechanism for feeding the recording media P one by one from the stacking unit to the transport drum 8 at the uppermost stream. Each of the transfer cylinders 8 and 8a is a rotating body that rotates around a rotation axis in the Y direction, and has a cylindrical outer peripheral surface. At least one grip mechanism for holding the leading end of the recording medium P (or the recorded matter P ') is provided on the outer peripheral surface of each of the transport cylinders 8 and 8a. The gripping operation and the releasing operation of each gripping mechanism are controlled so that the recording medium P is transferred between adjacent transport cylinders.

  The two transport cylinders 8a are transport cylinders for reversing the recording medium P. When recording the recording medium P on both sides, after the transfer to the front surface, the recording medium P is transferred from the impression cylinder 42 to the transport cylinder 8a without passing to the transport cylinder 8 adjacent to the downstream side. The recording medium P is turned upside down via the two transfer cylinders 8a, and is transferred again to the impression cylinder 42 via the transfer cylinder 8 on the upstream side of the impression cylinder 42. As a result, the back surface of the recording medium P faces the transfer drum 41, and the ink image is transferred to the back surface.

  The chain 8c is wound between two sprockets 8b. One of the two sprockets 8b is a driving sprocket and the other is a driven sprocket. The chain 8c runs cyclically by the rotation of the drive sprocket. The chain 8c is provided with a plurality of grip mechanisms spaced apart in the longitudinal direction. The grip mechanism grips the end of the recorded matter P '. The recorded material P 'is transferred from the transport cylinder 8 located at the downstream end to the gripping mechanism of the chain 8c, and the recorded material P' gripped by the gripping mechanism is transported to the collection unit 8d by the traveling of the chain 8c, and the gripping is released. You. Thereby, the recorded matter P 'is stacked in the collection unit 8d.

[Post-processing unit]
Post-processing units 10A and 10B are provided in the transport device 1B. The post-processing units 10A and 10B are arranged downstream of the transfer unit 4 and are mechanisms for performing post-processing on the recorded matter P '. The post-processing unit 10A performs a process on the front side of the recorded matter P ′, and the post-processing unit 10B performs a process on the back side of the recorded matter P ′. Examples of the content of the processing include a coating on the image recording surface of the recorded material P ′ for the purpose of protecting the image, polishing the image, and the like. Examples of the content of the coating include application of a liquid, welding of a sheet, and lamination.

[Inspection unit]
Inspection units 9A and 9B are provided in the transport device 1B. The inspection units 9A and 9B are arranged downstream of the transfer unit 4 and are mechanisms for inspecting the recorded matter P ′.

  In the case of the present embodiment, the inspection unit 9A is an image capturing device that captures an image recorded on the record P ', and includes, for example, an image sensor (not shown) such as a CCD sensor or a CMOS sensor. The inspection unit 9A captures a recorded image during a continuous recording operation. Based on the image photographed by the inspection unit 9A, it is possible to confirm a temporal change such as a tint of the recorded image and determine whether or not the image data or the recorded data can be corrected. In the case of the present embodiment, the inspection unit 9A has an imaging range set on the outer peripheral surface of the impression cylinder 42, and is arranged so as to be able to partially capture a recorded image immediately after transfer. The inspection unit 9A may inspect all the recorded images, or may inspect every predetermined number.

  In the case of the present embodiment, the inspection unit 9B is also a photographing device that photographs an image recorded on the recorded matter P ', and includes, for example, an image sensor (not shown) such as a CCD sensor or a CMOS sensor. The inspection unit 9B captures a recorded image in a test recording operation. The inspection unit 9B can photograph the entire recorded image, and can make various basic settings for various corrections on the recorded data based on the image photographed by the inspection unit 9B. In the case of the present embodiment, it is arranged at a position where the recorded matter P 'conveyed by the chain 8c is photographed. When the recorded image is photographed by the inspection unit 9B, the traveling of the chain 8c is temporarily stopped, and the whole is photographed. The inspection unit 9 </ b> B may be a scanner that scans the recorded matter P ′.

[Controller unit]
Next, a control unit of the recording system 1 will be described. 4 and 5 are block diagrams of the control unit 13 of the recording system 1. The control unit 13 is communicably connected to a host device (DFE) HC2, and the host device HC2 is communicably connected to a host device HC1.

  The host device HC1 generates or stores document data that is the basis of a recorded image. The document data here is generated in the form of an electronic file such as a document file or an image file. This document data is transmitted to the host device HC2, and the host device HC2 converts the received document data into a data format usable by the control unit 13 (for example, RGB data expressing an image in RGB). The converted data is transmitted as image data from the host device HC2 to the control unit 13, and the control unit 13 starts a recording operation based on the received image data.

  In the case of the present embodiment, the control unit 13 is roughly divided into a main controller 13A and an engine controller 13B. The main controller 13A includes a processing unit 131, a storage unit 132, an operation unit 133, an image processing unit 134, a communication I / F (interface) 135, a buffer 136, and a communication I / F 137.

  The processing unit 131 is a processor such as a CPU, executes a program stored in the storage unit 132, and controls the entire main controller 13A. The storage unit 132 is a storage device such as a RAM, a ROM, a hard disk, and an SSD, stores a program executed by the CPU 131 and data, and provides a work area to the CPU 131. The operation unit 133 is, for example, an input device such as a touch panel, a keyboard, and a mouse, and receives an instruction from a user.

  The image processing unit 134 is, for example, an electronic circuit having an image processor. The buffer 136 is, for example, a RAM, a hard disk, or an SSD. The communication I / F 135 communicates with the host device HC2, and the communication I / F 137 communicates with the engine controller 13B. In FIG. 4, broken arrows indicate the flow of processing of image data. Image data received from the host device HC2 via the communication I / F 135 is stored in the buffer 136. The image processing unit 134 reads the image data from the buffer 136, performs predetermined image processing on the read image data, and stores the read image data in the buffer 136 again. The image data after the image processing stored in the buffer 136 is transmitted from the communication I / F 137 to the engine controller 13B as print data used by the print engine.

  As shown in FIG. 5, the engine controller 13B includes control units 14, 15A to 15E, and performs acquisition of the detection results of the sensor group and the actuator group 16 included in the recording system 1 and drive control. Each of these control units includes a processor such as a CPU, a storage device such as a RAM and a ROM, and an interface with an external device. Note that the division of the control units is merely an example, and a part of the control may be executed by a plurality of subdivided control units, or conversely, a plurality of control units may be integrated and their control contents may be integrated. It may be configured to be performed by one control unit.

  The engine control unit 14 controls the entire engine controller 13B. The recording control unit 15A converts the recording data received from the main controller 13A into a data format suitable for driving the recording head 30, such as raster data. The print control unit 15A controls the ejection of each print head 30.

  The transfer control unit 15B controls the application unit 5A, controls the absorption unit 5B, controls the heating unit 5C, and controls the cleaning unit 5D.

  The reliability control unit 15C controls the supply unit 6, controls the recovery unit 12, and controls the drive mechanism that moves the recording unit 3 between the ejection position POS1 and the recovery position POS3.

  The transport control unit 15D controls the drive of the transfer unit 4 and controls the transport device 1B. The inspection control unit 15E controls the inspection unit 9B and controls the inspection unit 9A.

  Among the sensor group and the actuator group 16, the sensor group includes a sensor for detecting the position and speed of the movable unit, a sensor for detecting temperature, an image sensor, and the like. The actuator group includes a motor, an electromagnetic solenoid, an electromagnetic valve, and the like.

[Operation example]
FIG. 6 is a diagram schematically illustrating an example of the recording operation. The following steps are performed cyclically while the transfer drum 41 and the impression cylinder 42 are rotated. As shown in state ST1, first, the reaction liquid L is applied to the transfer body 2 from the application unit 5A. The portion of the transfer body 2 to which the reaction liquid L has been applied moves as the transfer drum 41 rotates. When the portion to which the reaction liquid L has been applied reaches below the recording head 30, ink is ejected from the recording head 30 to the transfer body 2 as shown in state ST2. Thus, an ink image IM is formed. At that time, the ejected ink mixes with the reaction liquid L on the transfer body 2, thereby promoting the aggregation of the coloring material. The ejected ink is supplied to the recording head 30 from the storage section TK of the supply unit 6.

  The ink image IM on the transfer body 2 moves as the transfer body 2 rotates. When the ink image IM reaches the absorption unit 5B, the liquid component is absorbed from the ink image IM by the absorption unit 5B as shown in a state ST3. When the ink image IM reaches the heating unit 5C, as shown in a state ST4, the heating unit 5C heats the ink image IM, the resin in the ink image IM melts, and the ink image IM is formed. The recording medium P is transported by the transport device 1B in synchronization with the formation of such an ink image IM.

  As shown in the state ST5, the ink image IM and the recording medium P reach the nip portion between the transfer body 2 and the impression cylinder 42, the ink image IM is transferred to the recording medium P, and the recorded matter P 'is manufactured. . After passing through the nip portion, the image recorded on the recorded matter P 'is photographed by the inspection unit 9A, and the recorded image is inspected. The recorded material P 'is transported by the transport device 1B to the collection unit 8d.

  When the ink image IM on the transfer body 2 has reached the cleaning unit 5D, it is cleaned by the cleaning unit 5D as shown in the state ST6. After the cleaning, the transfer body 2 has made one rotation, and the transfer of the ink image onto the recording medium P is repeatedly performed in the same procedure. In the above description, for ease of understanding, the transfer of the ink image IM to one recording medium P is performed once in one rotation of the transfer body 2. The transfer of the ink image IM to the plurality of recording media P can be continuously performed.

  If such a recording operation is continued, maintenance of each recording head 30 is required. FIG. 7 shows an operation example at the time of maintenance of each recording head 30. The configuration in FIG. 7 corresponds to the configuration shown in FIG. The state ST11 indicates a state where the recording unit 3 is located at the ejection position POS1. The state ST12 indicates a state in which the recording unit 3 has passed the preliminary recovery position POS2, and the recovery unit 12 performs a process of recovering the ejection performance of each recording head 30 of the recording unit 3 during the passage. Thereafter, as shown in the state ST13, in the state where the recording unit 3 is located at the recovery position POS3, a process of recovering the ejection performance of each recording head 30 is executed by the recovery unit 12.

  FIG. 8 shows the inspection unit 9B and its peripheral configuration, which is viewed from above the apparatus. FIG. 9 shows the inspection unit 9B and its peripheral configuration, which is viewed from the front side of the apparatus.

  The recording medium P is transported in the transport direction 801, stops transporting in the vicinity of the inspection unit 9 </ b> B, and performs imaging using the CCD sensor 802 that can scan in the width direction 803 orthogonal to the transport direction 801. The recording medium P is conveyed to the inspection unit 9B by holding the leading end of the recording medium P with a gripping mechanism 906 installed on the chain 8c and running the chain 8c cyclically. When imaging the imaging area 805, the recording medium P is moved close to the CCD sensor 802 by moving the lift 907, which can be driven in the vertical direction 908, to the pressing position 907B. In this case, instead of stopping the conveyance, the CCD sensor 802 may be arranged along a direction orthogonal to the conveyance direction, and the imaging may be performed while the conveyance speed is reduced.

<First embodiment>
[Recording head misalignment correction method]
FIG. 10 is a diagram for explaining a test pattern for correcting a positional deviation of the recording head according to the present embodiment.

  FIG. 10 shows an example in which a test pattern 1002 for head position shift correction is recorded using cut paper as the recording medium 1001. Note that, although the description will be made assuming that the test pattern fits on one cut sheet used here, a configuration in which a plurality of test patterns are recorded depending on the size of the cut sheet may be used. The nozzle row direction 1003 indicates the nozzle arrangement direction of the recording head 30. That is, the nozzle row direction 1003 corresponds to the Y direction in FIG.

  As shown in FIG. 2, a plurality of recording heads 30 are provided. Each print head corresponds to five colors of K (black), M (magenta), C (cyan), Y (yellow), and clear ink from the downstream side in the transport direction of the print medium 1001. The color order of the recording head 30 may be changed, or the number of heads corresponding to other colors such as G (gray), LM (light magenta), LC (light cyan) may be increased or changed.

  The inspection unit 9B is disposed downstream of the recording head 30 in the transport direction of the recording medium 1001 with respect to the recording head 30. The inspection unit 9B reads the test pattern 1002 recorded on the recording medium 1001 in order to detect the amount of displacement of the recording head 30.

  One recording head 30 is composed of a plurality of recording chips, and one recording chip is a recording chip 1004. In the present embodiment, an example is shown in which one recording chip has a parallelogram shape. In this embodiment, 36 print chips 1004 are arranged in the print head 30 along the nozzle row direction 1003, but the number of print chips may be changed. The nozzle row direction 1003 corresponds to the width direction 803 in FIG. In the recording chip 1004, a plurality of nozzle rows 1005 are arranged. In the present embodiment, 24 nozzle rows 1005 are arranged on the recording chip 1004, but the number of rows may be changed. Further, in the present embodiment, as shown in FIG. 10, in the recording chip 1004, the nozzle rows 1005 are arranged at a predetermined angle with respect to the transport direction. Further, the end of the nozzle row 1005 is arranged so as to be inclined with respect to the transport direction.

  The type of head misalignment will be described. Any of these is caused by a molding error of a chip or a nozzle of the recording head 30 or an installation error of the recording head 30. The types of shift include a shift between nozzle rows 1005 in the print chip 1004, a shift between print chips between the print chips 1004, a shift between colors between the print heads 30, and the like. If there is such a shift, the ink ejection position shifts from the ideal position, and the quality of the recorded image deteriorates. The head misalignment correction is a function of correcting the ink ejection position by changing the ink ejection timing of the recording chip 1004 or the nozzle that performs ejection.

  In the present embodiment, the displacement in the direction orthogonal to the nozzle row direction 1003 (the transport direction 801) is corrected by changing the ejection timing of each of the print chips 1004 constituting the print head 30. Regarding the displacement in the nozzle row direction 1003, the displacement is corrected by changing the ejection data. With respect to the inclination of the recording head 30, the position deviation is corrected by rotating the recording head 30. Here, the rotation corresponds to an operation of controlling the ejection direction (normal direction of the transfer body 41) of the recording head 30 to the transfer body 41.

  The test pattern 1002 is a test pattern for correcting a head displacement of the recording head 30. The test pattern 1006 is a test pattern for calculating the amount of displacement between the recording heads 30. The test pattern 1006 will be described in detail with reference to FIG.

  In the present embodiment, a test pattern 1007 is a test pattern for calculating a shift amount between print heads, and is an enlarged view of the test pattern 1006. In the configuration shown in the test pattern 1007, the correspondence between the test pattern and the ink color according to the type of the recording head 30 may be changed. In the test pattern 1007, the area expressed in black is the area recorded with the corresponding ink. The area expressed in white is the background color of the recording medium 1001 and is an area not recorded with ink.

  The recording head 30 according to the present embodiment has a configuration in which a plurality of recording chips 1004 are linearly arranged along the nozzle row direction 1003. A test chip 1007 is recorded by selecting a recording chip from the recording chips 1004 constituting the recording head 30.

  A configuration and a printing method of the test pattern 1007 for calculating a shift amount between print heads will be described. The test pattern 1007 includes a detection mark 1008, alignment marks 1009 and 1010, and pattern matching patterns 1011 and 1012. The detection mark 1008 is a pattern for detecting the test pattern 1007 when calculating a shift amount between print heads by image analysis processing. The detection mark 1008 is a pattern recorded in a rectangular area shape as shown in FIG. In the present embodiment, as described above, the recording chip is configured by a plurality of nozzle rows. The detection mark 1008 is recorded by droplet ejection by a plurality of nozzle arrays. By performing recording using a plurality of nozzle rows, even when a non-discharge nozzle is present, droplets are ejected by nozzles of another nozzle row, and thus the loss of the detection pattern due to the non-discharge nozzle is reduced. Therefore, the detection mark can be stably detected in the image analysis processing.

  The alignment marks 1009 and 1010 are used for calculating a reference position of an analysis area of the pattern matching patterns 1011 and 1012 by image analysis processing. The alignment marks 1009 and 1010 are recorded in a rectangular area shape as shown in FIG. The alignment marks 1009 and 1010 are recorded for each pattern matching pattern 1011 and 1012 corresponding to the nozzle row by droplet ejection from a plurality of nozzle rows. The pattern matching pattern 1011 corresponds to the alignment mark 1009, and the pattern matching pattern 1012 corresponds to the alignment mark 1010.

  The pattern matching patterns 1011 and 1012 are patterns for detecting a displacement of the recording head 30 by the image analysis processing. The patterns 1011 and 1012 for pattern matching are selectively used depending on the recording color and the type of the calculated shift amount.

  In the pattern formed by the clear ink, a signal difference between the luminance value of the base color of the recording medium 1001 and the recording color (transparent color) is hard to appear. That is, it is difficult to detect a difference in luminance value between the base and the ink. Therefore, in the present embodiment, for the clear ink, the misregistration is detected using the pattern matching pattern 1012 that is a pattern that is larger than the pattern matching pattern 1011. Details will be described later with reference to FIG.

  FIG. 11 is a diagram showing a detailed layout of the pattern matching patterns 1011 and 1012. 1101 indicates the number of pixels in the vertical direction of the pattern matching pattern 1011, and 1102 indicates the number of pixels in the horizontal direction. 1103 indicates the number of pixels in the vertical direction of the pattern matching pattern 1012, and 1104 indicates the number of pixels in the horizontal direction.

  In the present embodiment, 1101 in the pattern matching pattern 1011 is parallel to the transport direction 801, 1102 is parallel to the nozzle row direction 1003, and both are 82 pixels in 1200 DPI (dot per inch) units. Also, 1103 in the pattern matching pattern 1012 is parallel to the transport direction 801 and 1104 is parallel to the nozzle row direction 1003, both of which are 210 pixels in 1200 DPI units. Note that the number of pixels constituting each pattern matching pattern is not limited to the above, and may be changed. As shown in FIG. 11, the pattern matching pattern 1011 has a smaller size than the pattern matching pattern 1012.

  FIG. 12 is a diagram showing a correspondence between a test pattern for performing a shift correction calculation between print heads and print heads and print chips. The test pattern 1201 is a test pattern for calculating a position error between the recording heads 30. In this, a pattern is recorded by a recording head of each recording color shown in 1202. In each print head, one print chip 1004 to be used for printing a pattern is selected, and here, the print chip at the position of the print chip 1203 in each print head is selected. In this embodiment, a pattern is recorded using the recording chip 1203. In the test pattern 1201, a portion expressed in black is a portion of a pattern recorded in a corresponding recording color (ink), and a portion expressed in white is a portion of paper white (base) of the recording medium 1001. Is shown.

  In the present embodiment, the pattern matching pattern 1011 is used for K, C, M, and Y inks. For clear ink (denoted by T), a pattern matching pattern 1012 is used. The reason for using the pattern matching pattern 1012 for the clear ink is that the pattern formed with the clear ink hardly produces a signal difference from the luminance value of the base color of the recording medium 1001, and thus the detection accuracy is further improved. As shown in the layout 1202, a pattern is recorded using K as a reference head, and the positional deviation of each recording head is calculated. As the pattern of the reference head, the same pattern as the pattern matching pattern of the recording color whose deviation is to be calculated is used. Pattern matching patterns corresponding to colors are not limited to those shown in FIGS. 11 and 12, and different patterns may be used.

  The test pattern 1201 used for calculating the color shift between the recording heads 30 is recorded such that the recording timing on the recording medium 1001 exceeds the maximum amount of color deviation of the recording head. By shifting the recording timing of each recording head in this way, the overlapping of the test patterns is prevented.

(Calculation of deviation between print heads)
FIG. 13 is a diagram for explaining a method of calculating the amount of displacement between the recording heads. In the present embodiment, the first recording head counted from the downstream side in the transport direction 801 is a recording head K using the ink color BK, and is hereinafter referred to as a recording head C, a recording head M, and a recording head Y. Further, a recording head for recording with clear ink is referred to as a recording head T. A method of calculating a shift amount between print heads (hereinafter, referred to as “color shift”) using a scanned image of a printed pattern according to a layout 1202 corresponding to the test pattern 1201 will be described.

  The test pattern 1201 is a test pattern used for calculating a color shift amount. A test pattern 1201 is printed using a print chip 1203 at a predetermined position of the print head 30 corresponding to a predetermined color shown in the layout 1202. In this embodiment, the chip 18 is used as the recording chip 1203 at a predetermined position. The recording patterns 1301 to 1310 are recorded by the reference head, and are patterns recorded by the recording head K in this embodiment. The other recording color patterns are the colors for which the positional deviation between the recording heads is to be calculated. In the present embodiment, these patterns are C, M, Y, and T (clear ink) patterns, but the number of recording colors may be increased or decreased. In the present embodiment, an area in which a pattern by another recording head enters is secured. In the present embodiment, C, M, and Y are recorded using the pattern matching pattern 1011 shown in FIG. The K recording patterns 1301 to 1306 of the corresponding reference patterns are also recorded using the configuration of the pattern matching pattern 1011.

  In the present embodiment, the recording pattern 1317 using clear ink is recorded using the configuration of the pattern matching pattern 1012 shown in FIG. Accordingly, the recording patterns 1307 to 1310, which are the K patterns of the corresponding reference patterns, are also recorded using the configuration of the pattern matching pattern 1012. The same type of pattern matching pattern is used for the reference head and the target head for calculating the color shift.

  In the present embodiment, when calculating the shift amount between the printhead K (reference head) and another printhead, the shift amount is calculated using the same method for each printhead. Here, as an example, a method of calculating a shift amount between the print head K and the print head T (clear ink) will be described. The recording pattern 1320 corresponds to the recording pattern 1307, and the recording pattern 1321 corresponds to the recording pattern 1308. These are the patterns of the reference head recorded by the chip 18 of the recording head K. The recording pattern 1322 corresponds to the recording pattern 1317, is a recording pattern on the chip 18 of the recording head T, and is a recording pattern recorded by the recording head for which the amount of displacement is to be calculated.

  When there is no displacement of the landing position of the ejected ink when each recording pattern is recorded by the recording head K and the recording head T, the recording pattern of the recording head T is recorded on a straight line connecting the recording pattern 1320 and the recording pattern 1321. The patterns are arranged so that A recording pattern 1324 indicates the position of the recording pattern of the recording head T recorded at an ideal position where there is no landing position deviation of the ejected ink. On the other hand, the actual recording position is indicated by a recording pattern 1322.

  In the present embodiment, it is assumed that the displacement between the recording pattern 1322 and the recording pattern 1324 in the scanned image is a relative displacement between the recording head T and the recording head T. And The shift amount 1325 is the length of a perpendicular drawn to the recording pattern 1322, which is orthogonal to the straight line connecting the recording pattern 1320 and the recording pattern 1321. Therefore, the shift amount 1325 can be obtained from the positions of the recording pattern 1320, the recording pattern 1321, and the recording pattern 1322. In addition, a distance between a perpendicular line passing through the recording pattern 1322 and a perpendicular line passing through the recording pattern 1324 is obtained with respect to a straight line connecting the recording pattern 1320 and the recording pattern 1321. As a result, a shift amount 1326 between the recording pattern 1324 and the recording pattern 1322 can be obtained. In the present embodiment, the calculation of the positional deviation amount of the recording head is performed by calculating the correction amount also in the direction orthogonal to the head positional deviation amount 1325. Therefore, for the head position shift amount, the correction amount is calculated in both directions for the shift amount 1325 and the shift amount 1326.

  By applying the method described above, it is possible to obtain the amount of color shift of each print head other than the print head K with respect to the reference head.

(Mark detection processing)
FIG. 14 is a diagram for explaining a mark detection process corresponding to the recording chip 1004. In the present embodiment, a process of detecting a detection mark of each pattern corresponding to the recording chip 1004 from a read image of a test pattern for calculating a shift amount will be described. FIG. 14 shows a test pattern for calculating the amount of displacement between print heads, which is shown by the test pattern 1201 in FIG. 12, and the mark detection processing will be described using this pattern.

  The mark detection process is roughly divided into three steps. In the first step, the detection mark 1008 is detected. The position of the test pattern 1201 is estimated based on the detection position of the detection mark 1008. In the second step, alignment marks 1009 and 1010 are detected based on the above-described estimated test pattern positions. FIG. 14 illustrates an alignment mark 1403 as an example of the alignment mark 1009. Since the same steps are performed for the detection processing of the alignment marks 1009 and 1010, the detection processing will be described here using the alignment mark 1403 which is an example of the alignment mark 1009. Since the alignment mark is recorded near each pattern matching pattern, the position of the corresponding pattern matching pattern can be estimated from the detected position of the alignment mark. From the position of the alignment mark 1403, the position of the corresponding pattern matching pattern is estimated. In the third step, pattern position detection using pattern matching is performed based on the estimated position of the pattern matching pattern in the second step.

  The process of detecting the detection mark 1008 in the first step will be described. This processing uses the luminance value of the channel having the highest density in the recording color of the recording head of the pattern to be detected among the three RGB channels of the image read by the inspection unit 9B. For example, when the color having the highest density is C (cyan), the R channel is used, when M (magenta) is used, the G channel is used, and when Y (yellow) is used, the B channel is used. In the case of a recording color having a high density in all the channels, such as K (black), any one of the channels is designated and used.

  Reference numeral 1405 is an enlarged view of a part of the detection mark 1008. The detection mark 1008 is detected based on the average density of a predetermined area of the read image. The detection mark detection area 1406 is an area for acquiring an average density. When the average density acquired in the detection mark detection area 1406 is equal to or higher than a predetermined density, the area is specified as a detection mark area, and the center position is set as a detection mark detection position 1407. The range of the detection mark detection area and the predetermined density used as the threshold may be changed.

  Subsequently, the upper left end position and the upper right end position of the detection mark 1008 are detected. 1408 is an enlarged view of the vicinity of the upper left end of the detection mark 1008, and 1410 is an enlarged view of the vicinity of the upper right end thereof. From the detection mark detection position 1407, an area having a predetermined density or higher is scanned, and the upper left end of the area having the predetermined density or higher is set as a detection mark upper left position 1409. Similarly, the upper right end of the region having the predetermined density or more is set as the upper right end position 1411 of the detection mark. Starting from the position determined based on the upper left position 1409 of the detection mark, the density centroid of the predetermined area is calculated to estimate the alignment mark detection range. By detecting the detection mark 1008 of the test pattern 1007 in FIG. 10, the detection range of Teva Taoba and the alignment mark 1403 can be estimated. Similarly to the detection process of the detection mark 1008, the detection process of the alignment mark 1403 is performed by scanning an area having a predetermined density or more, and calculating the density centroid of the area to detect the position of the alignment mark 1403.

  Subsequently, the position of the pattern for pattern matching is estimated. An area 1404 is an area indicating the upper left position of the pattern matching pattern. The detection result of the detection mark 1008 is used to determine whether this pattern is a test pattern corresponding to which recording head and which chip. After a rough position of the pattern for pattern matching is determined by the above processing, a final position on the image is detected by performing position detection processing including pattern matching processing. The position of the pattern matching pattern on the image is the position for calculating the distance used in the calculation of the head position shift amount. Here, the various shift amounts correspond to a manufacturing error between nozzle arrays, a manufacturing error between print chips, a tilt of a print head, a positional shift between print heads, and the like.

[Processing flow]
FIG. 15 is a flowchart for explaining the procedure of reading each pattern and analyzing the pattern according to the present embodiment. That is, FIG. 15 is a flowchart of the calculation process of the head displacement amount for performing the correction, which is performed using the test pattern 1002 for correcting the head displacement recorded on the recording medium 1001. These processing flows are performed by the control units of the engine controller 13B in cooperation with each other. When this processing is started, it is assumed that the test pattern 1002 has already been recorded on the recording medium 1001.

  In S101, the inspection unit 9B reads the test pattern 1002 for correcting a head position shift recorded on the recording medium 1001. At this time, the inspection unit 9B reads the image after correcting it with shading data created by a plurality of methods. In the present embodiment, the inspection unit 9B reads a white reference plate (not shown), which is a white reference, and creates first shading data based on the white reference plate. Further, the inspection unit 9B reads the background color of the recording medium 1001 and the ink color “the luminance value difference between the background color of the recording medium and the ink color is small”, and creates second shading data based on this. In the present embodiment, the description is given on the assumption that the ink color “the luminance value difference between the base color of the recording medium and the ink color is small” is clear ink. The value of the second shading data is a value between the data obtained by reading the base color and the data obtained by reading the clear ink. When the data is a luminance value, the relation of background color data> clear ink data is satisfied.

  Then, the inspection unit 9B corrects the signals of the R channel and the G channel in the read test pattern 1002 with the first shading data to obtain these read images. In addition, the inspection unit 9B corrects the signal of the B channel in the test pattern 1002 with the second shading data to obtain a read image of the corrected signal. As described above, in S101, one of each of the RGB channels is selected using a plurality of shading data created by a plurality of methods, and is used for image correction. In this correction, data having a value lower than the value of the shading data is corrected to have the lowest luminance value (here, 0). If it is assumed that background color data> shading data> clear ink, the value of the read data of the clear ink is a value corresponding to the lowest luminance. By doing so, the correction is performed so that the color of the image of the clear ink approaches black. With this configuration, a luminance difference between the base color of the recording medium 1001 and the clear ink occurs in the B channel of the read image, and the accurate recording position of the pattern can be detected.

  The timing at which the inspection unit 9B starts reading the test pattern 1002 may start reading after waiting a predetermined amount of time from the start of recording of the test pattern 1002. Alternatively, reading may be started after the recording medium 1001 is conveyed by a predetermined amount from the end of the recording of the test pattern 1002. The timing to end reading ends when a predetermined number of sub-scanning lines have been read from the start of reading.

  In S102, inspection control unit 15E detects a pattern for correcting positional deviation of recording head 30 on the R channel of the read image. The pattern to be detected is a test pattern 1201 for displacement between the recording heads 30. In the present embodiment, since the R channel is a channel corrected by shading data (second shading data) created by reading a white reference plate (not shown), the position of this pattern can be detected.

  In S103, the inspection control unit 15E estimates a pattern position of the print head 30 for which the calculation of the print head position shift amount has not been performed, from the test pattern 1201 for the position shift between the print heads 30 detected in S102. The recording head 30 whose position is to be corrected has the ink color “the luminance value difference between the base color of the recording medium and the ink color is small”, and corresponds to clear ink in the present embodiment. Since the reference head for correcting the positional deviation of the recording head 30 is the K recording head in the present embodiment, the pattern position recorded by the clear ink and the K recording head is estimated.

  The pattern position estimation according to the present embodiment will be described with reference to the drawings. A test pattern 1201 shown in FIG. 12 is a pattern for correcting the positional deviation of the recording head 30. The layout 1202 indicates which print head forms each pattern matching pattern included in the test pattern 1201. As described above, the pattern of the print head 30 to be subjected to the misalignment correction according to the present embodiment in S103 is the print pattern 1317 corresponding to the clear ink. The patterns of K as the reference head are a recording pattern 1307 and a recording pattern 1308. The pattern of K can be detected on the R channel of the RGB signal to be corrected with shading data (first shading data) read from a white reference plate (not shown). The clear ink can detect a pattern in the B channel of the RGB signal to be corrected by the shading data (second shading data) based on the base color.

  Further, the detection mark 1008 and the alignment mark described with reference to FIG. 14 are recorded by the recording head K as the reference head in the test pattern 1201 for correcting the displacement of the recording head 30. In the present embodiment, from the detection of the detection mark 1008 of the test pattern 1201, the area of the approximate position of both the recording patterns 1307 and 1308 of the reference head K and the recording pattern 1317 of the correction target clear ink is estimated. Then, based on the estimated area, the pixels of the RGB signal channel suitable for the ink of the recording head are selected for the pixels of the image for which the positional deviation correction of the test pattern 1201 is performed, and the image corresponding to each channel is selected. Create This image is used for detecting each pattern. Accordingly, it is possible to correct the positional deviation of the recording head by pattern detection using pattern matching for both the reference head K and the recording head of the clear ink to be corrected.

  In S104, the inspection control unit 15E selects a pattern corresponding to the correction of the displacement of the recording head 30 of the clear ink, and analyzes the inclination amount of the recording head. The analysis method here is the method described with reference to FIG. The recording color to be analyzed here is the recording color of the recording head detected in the channel corresponding to the recording color based on the estimation result of the pattern position in S103. Completion of S104 completes the calculation of the positional deviation amount of the recording head 30 including the clear link of the recording head 30.

  As described above, in the image in which the test pattern is read by the reading unit, even when a part of the recording color pattern has a small difference in luminance value between the base color of the recording medium and the recording color, it is possible to detect an accurate recording position of each pattern. Further, the processing in S102 can be realized by one reading without reading the same pattern a plurality of times. Then, based on the shift amount obtained by the above processing, it is possible to control the position of the recording head and control the ejection of ink.

  In the above description, both the shading data (first shading data) created by reading the white reference plate and the shading data (second shading data) created by reading the base color and recording color of the recording medium 1001 are used. Correct the RGB signal values of the image. Then, a pattern is detected using the corrected RGB signal values. According to this method, the correct recording position of both patterns of each recording color read using any one of the read RGB channels corrected by the white reference plate and the recording color having a small difference in the luminance value between the base color of the recording medium and the recording medium is determined by one. It can be detected by reading twice. As a result, the processing time is reduced as compared with the case where the same print pattern is read a plurality of times. In addition, there is an effect that a reading error for each reading when adjusting a printing position between different read images does not affect the printing position detection accuracy of the pattern.

<Second embodiment>
In the present embodiment, an example in which a test pattern recorded with clear ink is changed to further improve the visibility of a pattern recorded with clear ink in the configuration described in the first embodiment will be described. The configuration other than the test pattern is the same as that of the first embodiment, and a duplicate description will be omitted.

  FIG. 16 is a view for explaining a test pattern for correcting a positional deviation of the recording head according to the present embodiment. The difference from FIG. 10 described in the first embodiment is that the alignment mark 1610 and the pattern matching pattern 1612 of the test pattern 1007 for calculating the amount of color shift between print heads are changed. Is a point. In order to enhance the visibility of the clear ink, the alignment mark 1610 and the pattern matching pattern 1612 are black and white inverted from those of the first embodiment shown in FIG. The black and white reversal increases the recording area of the clear ink portion. The black portion is a portion recorded using clear ink. The white portion is an unprinted portion, that is, a base portion of the recording medium 1001. In the pattern matching pattern 1612, the pattern can be recognized in a white unprinted portion and a portion where black clear ink is recorded.

  FIG. 17 shows details of the pattern matching pattern 1612. Reference numeral 1703 denotes the number of pixels in the vertical direction of the pattern matching pattern 1612, and reference numeral 1704 denotes the number of pixels in the horizontal direction. This is the same as the pattern matching pattern 1012 shown in FIG. 11 of the first embodiment.

  FIG. 18 is a diagram showing a correspondence between a test pattern for performing a color shift correction calculation between print heads and the print chip 1004 according to the present embodiment. K, C, M, and Y are the same as those in FIG. 12 described in the first embodiment. The test pattern 1810 is a test pattern 1801 for calculating a position error between the recording heads 30. In this case, a pattern is recorded by a recording head of each recording color shown in a layout 1802. As shown in the layout 1802, a pattern is printed using K as a reference head, and the displacement of each print head 30 is calculated. The pattern 1803 for calculating the displacement between K and the clear ink uses a pattern matching pattern 1612. The black portion is the location of the pattern recorded in the corresponding memory color (ink). A white portion is an unprinted portion (that is, a base of the recording medium 1001). In the present embodiment, the visibility of the test pattern for clear ink is enhanced as compared with the first embodiment by using the pattern matching pattern 1612 that is inverted in black and white. In addition, the pattern of the reference head uses the same pattern as the pattern matching pattern of the recording color whose deviation is to be calculated. The corresponding pattern matching pattern may vary depending on the color.

  FIG. 19 is a diagram illustrating a method for calculating a shift amount between print heads according to the present embodiment. In the present embodiment, the recording patterns 1301 to 1306, which are the C, M, and Y patterns and the K pattern of the reference pattern, and the method of calculating the color shift are the same as those in FIG. 13 described in the first embodiment. In the present embodiment, the recording pattern 1917 using clear ink is recorded as the pattern matching pattern 1612 in FIG. Accordingly, the corresponding K patterns 1907 to 1910 of the reference pattern are also recorded as the pattern matching pattern 1612.

  As described above, in the present embodiment, the visibility is improved by setting the test pattern recorded by the clear ink that is hardly visible to be a black-and-white inverted matching pattern. Further, by performing the shading process as shown in FIG. 15 of the first embodiment together, the accuracy of the clear ink detection is improved, and the same pattern is not read a plurality of times without being read multiple times. It can be realized by reading twice.

  In the present embodiment, the matching pattern is a black-and-white inversion pattern in order to enhance the visibility of the clear ink in the ink color. However, the ink color is not limited to this, and when the difference in luminance value between the base color of the recording medium and the recording color is small, the same effect is exhibited with, for example, light ink. In addition, by inverting the position where the image is formed in the pattern, the area of the clear ink is enlarged, and when the visibility is improved, the size for pattern matching is set to the same for the color ink and the clear ink. You may comprise so that it may become.

<Other embodiments>
In the above embodiment, the recording unit 3 has a plurality of recording heads 30, but may have one recording head 30. The recording head 30 may not be a full line head, and may be a serial type in which ink is ejected from the recording head 30 to form an ink image while moving a carriage in which the recording head 30 is removably mounted in the Y direction. Good.

  The conveyance mechanism of the recording medium P may be another method such as a method of nipping and conveying the recording medium P by a pair of rollers. In a method in which the recording medium P is conveyed by a pair of rollers, a roll sheet may be used as the recording medium P, or the roll sheet may be cut after the transfer to produce a recorded matter P ′.

  Further, in the above-described embodiment, the transfer body 2 is provided on the outer peripheral surface of the transfer drum 41. However, another method such as a method in which the transfer body 2 is formed in an endless band shape and run cyclically may be used. .

  In addition, the present invention supplies a program for realizing one or more functions of the above-described embodiments to a system or an apparatus via a network or a storage medium, and one or more processors in a computer of the system or the apparatus read and execute the program. This processing can be realized. Further, it can also be realized by a circuit (for example, an ASIC) that realizes one or more functions.

  9B: detection unit, 13A: main controller, 13B: engine controller, 14: engine controller, 15A: recording controller, 15E: inspection controller, 30: recording head, 1001: recording medium, 1004: recording chip, 1005 ... Nozzle row

Claims (11)

An ink jet recording method, comprising: a recording head of an ink jet recording method;
First creating means for creating first shading data using an image obtained by reading the white reference by the reading means;
A first acquisition unit that acquires a base image of the recording medium by reading a recording medium with the reading unit;
A second acquisition that acquires an image formed with a predetermined ink among the plurality of inks by reading a chart formed by using a plurality of inks on the recording medium with the recording head by the reading unit; Means,
A second creation unit that creates second shading data using the base image and the image formed with the predetermined ink;
A signal corresponding to a first color is corrected for the image of the chart read by the reading unit using the first shading data, and a signal corresponding to a second color is corrected to the second shading. Correction means for correcting using the data,
Using a signal corrected by the correction unit, a specification unit that specifies a region formed by each of the plurality of inks in the image of the chart,
An ink jet recording apparatus comprising: a calculating unit that calculates a positional shift amount of the print head based on a position of the area specified by the specifying unit. The specifying means includes:
Using a signal corresponding to the first color corrected using the first shading data, specifying a region of the first color,
Estimating an area formed by the predetermined ink based on the position of the area of the first color and the configuration of the chart, and correcting the estimated area using the second shading data 2. The ink jet recording apparatus according to claim 1, wherein a second area formed with the predetermined ink is specified using a signal corresponding to the second color. The first color is red;
The inkjet recording apparatus according to claim 1, wherein the second color is blue.   4. The ink jet recording apparatus according to claim 1, wherein the predetermined ink is an ink having a difference in luminance value from a base color of the recording medium smaller than a predetermined threshold. 5. The chart is configured to include a first pattern formed of the predetermined ink and a second pattern formed of an ink different from the predetermined ink,
5. The inkjet recording apparatus according to claim 1, wherein the size of the first pattern is larger than the size of the second pattern. 6.   6. The ink jet recording apparatus according to claim 5, wherein the first pattern and the second pattern are formed such that positions formed by ink and positions not formed are inverted.   The inkjet recording apparatus according to claim 1, wherein the predetermined ink is a clear ink.   8. The inkjet recording apparatus according to claim 1, further comprising an adjusting unit that adjusts the positional shift of the printhead using the positional shift amount calculated by the calculating unit. 9. .   The correction of the displacement by the adjusting means is any one of a correction of a displacement between recording heads, a correction of a displacement between recording chips included in the recording head, and a correction of a displacement between nozzle arrays in the recording chips. The ink jet recording apparatus according to claim 8, wherein   The inkjet recording apparatus according to any one of claims 1 to 9, wherein a plurality of the recording heads are provided. A recording head of an ink jet recording system, a method for controlling an ink jet recording apparatus having a reading unit,
A first creation step of creating first shading data using an image obtained by reading a white reference by the reading unit;
A first acquisition step of acquiring a base image of the recording medium by reading the recording medium with the reading unit;
A second acquisition method of acquiring an image formed of a predetermined ink among the plurality of inks by reading a chart formed on the recording medium using the plurality of inks by the recording head by the reading unit; Process and
A second creation step of creating second shading data using the base image and the image formed with the predetermined ink;
A signal corresponding to a first color is corrected for the image of the chart read by the reading unit using the first shading data, and a signal corresponding to a second color is corrected to the second shading. A correction step of correcting using the data,
Using the signal corrected in the correction step, a specifying step of specifying a region formed by each of the plurality of inks in the image of the chart,
Calculating a position shift amount of the print head based on the position of the area specified in the specifying step.

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