JP2018043400A - Inkjet recording device, and method for acquiring adjustment information of discharge head arrangement direction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording device and a method for acquiring adjustment information of a discharge head arrangement direction, that restrict occurrence of color shifts between discharge heads.SOLUTION: An inkjet recording device includes: an ink discharge unit which comprises plural discharge heads with plural nozzles respectively for discharging ink, and in which an arrangement direction of the plural discharge heads respectively is adjustable; test image recording control means which makes the ink discharge unit record a test image capable of acquiring color reproducibility information related to color reproducibility according to an arrangement direction of the plural discharge heads respectively, on a recording medium, by discharging ink from the plural nozzles in the plural discharge heads respectively onto the recording medium that is relatively moved by a moving unit for relatively moving the ink discharge unit and the recording medium; and adjustment information generation means which generates and outputs adjustment information for adjusting an arrangement direction so that variation in color reproducibility in the plural discharge heads is reduced, on the basis of the color reproducibility information acquired from imaging data of the test image.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an inkjet recording apparatus and a method for obtaining adjustment information of an ejection head arrangement direction.

  2. Description of the Related Art Conventionally, there is an inkjet recording apparatus that records an image by ejecting ink onto a recording medium from a plurality of nozzles of the ejection head while relatively moving an ejection head on which a plurality of nozzles that eject ink are arranged and a recording medium. 2. Description of the Related Art In recent years, in an ink jet recording apparatus, a long ink discharge unit (line head) in which a plurality of discharge heads are arranged at different positions in the width direction intersecting the relative movement direction in order to meet the demand for an improvement in recording speed. And a technique for recording an image with the long ink discharge portion is used.

  In an inkjet recording apparatus having such a long ink discharge section, the mounting angle of each discharge head in the ink discharge section is adjusted so that the positions of the plurality of nozzles in each of the plurality of discharge heads are equally spaced in the width direction. By doing so, there is a technique for making the recording resolution in the width direction uniform by the ink discharge section (for example, Patent Document 1).

JP 2010-125806 A

  However, the ejection direction of ink from each nozzle is not necessarily uniform due to variations in nozzle characteristics and the like, so in the conventional technique, the width direction of the ink ejected from the nozzle on the recording medium is It is difficult to make the landing position intervals in the discharge head uniform. Furthermore, the characteristics relating to the variation in the landing position interval usually differ for each ejection head. Accordingly, there is a problem in that color misregistration and color reproducibility are different between the ejection heads in a long ink ejection unit, resulting in a decrease in the image quality of the recorded image.

  An object of the present invention is to provide an inkjet recording apparatus and an adjustment information acquisition method for an ejection head arrangement direction that can suppress the occurrence of color misregistration between ejection heads.

In order to achieve the above object, the invention of the ink jet recording apparatus according to claim 1 comprises:
An ink discharge section having a plurality of discharge heads each provided with a plurality of nozzles for discharging ink, each of the plurality of discharge heads being provided so that an arrangement direction thereof can be adjusted;
A moving unit that relatively moves the ink discharge unit and the recording medium;
The arrangement direction of each of the plurality of ejection heads is caused by ejecting ink from the plurality of nozzles in each of the plurality of ejection heads by the ink ejection unit with respect to the recording medium relatively moved by the moving unit. Test image recording control means for recording on the recording medium a test image capable of acquiring color reproducibility information relating to color reproducibility according to
Based on the color reproducibility information acquired from the imaging data of the test image, generates and outputs adjustment information for adjusting the arrangement direction so as to reduce the variation in color reproducibility in the plurality of ejection heads Adjustment information generating means for
It is characterized by having.

According to a second aspect of the present invention, in the ink jet recording apparatus of the first aspect,
The test image recording control unit is configured to identify a landing position in a width direction orthogonal to the moving direction of ink ejected from a plurality of nozzles on a recording medium relatively moved in one moving direction. An image is recorded by the ink ejection unit,
The adjustment information generating unit is characterized in that the color reproducibility information is acquired based on landing position intervals in the width direction between the landing positions specified from imaging data of the test image.

The invention according to claim 3 is the ink jet recording apparatus according to claim 2,
The adjustment information generation unit acquires the color reproducibility information by specifying variation in the landing position interval with respect to a plurality of different arrangement directions.

According to a fourth aspect of the present invention, in the ink jet recording apparatus according to the third aspect,
The adjustment information generating unit may be configured to reduce the landing position interval related to the ejection heads other than the reference ejection head due to the variation in the landing position interval related to the reference ejection head having the largest variation in the landing position interval among the plurality of ejection heads. The adjustment information that approximates the variation is generated.

The invention according to claim 5 is the ink jet recording apparatus according to claim 1,
The test image recording control unit records the test image having a predetermined density by the ink ejection unit,
The adjustment information generation means is characterized in that the color reproducibility information is acquired from the density of the test image read from the imaging data of the test image and information indicating the arrangement direction.

A sixth aspect of the present invention is the ink jet recording apparatus according to the first aspect,
The test image recording control unit records a test image of a predetermined density by the ink ejection unit,
The adjustment information generation unit is characterized in that the color reproducibility information is acquired from gloss information relating to the gloss of the test image and information indicating the arrangement direction.

The invention according to claim 7 is the inkjet recording apparatus according to any one of claims 1 to 6,
The plurality of nozzles in the ejection head are two-dimensionally arranged.

The invention according to claim 8 is the ink jet recording apparatus according to claim 7,
The plurality of nozzles in the ejection head constitute a plurality of nozzle rows each composed of two or more nozzles arranged in a predetermined direction.

The invention according to claim 9 is the ink jet recording apparatus according to any one of claims 1 to 8,
An image pickup means for picking up the test image is provided.

In order to achieve the above object, the invention of the adjustment information acquisition method of the ejection head arrangement direction according to claim 10 comprises:
An ink ejection unit having a plurality of ejection heads each provided with a plurality of nozzles for ejecting ink, each of the plurality of ejection heads being capable of adjusting an arrangement direction; the ink ejection unit and the recording medium; An adjustment information acquisition method for the ejection head arrangement direction in an inkjet recording apparatus comprising:
The arrangement direction of each of the plurality of ejection heads is caused by ejecting ink from the plurality of nozzles in each of the plurality of ejection heads by the ink ejection unit with respect to the recording medium relatively moved by the moving unit. A test image recording step for recording on the recording medium a test image capable of acquiring color reproducibility information relating to color reproducibility according to
Based on the color reproducibility information acquired from the imaging data of the test image, generates and outputs adjustment information for adjusting the arrangement direction so as to reduce the variation in color reproducibility in the plurality of ejection heads Adjustment information generation step,
It is characterized by including.

  According to the present invention, there is an effect that occurrence of color misregistration between the ejection heads can be suppressed.

It is a figure which shows schematic structure of an inkjet recording device. It is a schematic diagram which shows the structure of a head unit. It is a block diagram which shows the main function structures of an inkjet recording device. FIG. 4 is a diagram illustrating an example of a landing position on a recording medium of ink ejected from a recording head. FIG. 10 is a diagram illustrating another example of a landing position of ink ejected from a recording head on a recording medium. It is a figure explaining the adjustment method of the dispersion | variation in the ink landing position space | interval by adjustment of a relative angle. It is a figure which shows the example of the test image used for specification of the adjustment amount of a relative angle. 6 is a flowchart illustrating a control procedure of recording head attachment adjustment processing. It is a figure explaining the relationship between the overlapping state of an ink, and glossiness.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments according to an ink jet recording apparatus and a method for obtaining adjustment information of an ejection head arrangement direction of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of an ink jet recording apparatus 1 according to an embodiment of the present invention.
The ink jet recording apparatus 1 includes a paper feeding unit 10, an image recording unit 20, a paper discharge unit 30, and a control unit 40 (FIG. 3). Under the control of the control unit 40, the inkjet recording apparatus 1 conveys the recording medium P stored in the paper feeding unit 10 to the image recording unit 20, and records an image (inkjet image) on the recording medium P by the image recording unit 20. Then, the recording medium P on which the image is recorded is conveyed to the paper discharge unit 30. As the recording medium P, in addition to paper such as plain paper and coated paper, various media capable of fixing ink landed on the surface, such as cloth or sheet-like resin, can be used. The recording medium P is not limited to a short medium such as a sheet, but may be a long medium such as roll paper supplied by a roll-to-roll method.

  The paper supply unit 10 includes a paper supply tray 11 that stores the recording medium P, and a medium supply unit 12 that conveys and supplies the recording medium P from the paper supply tray 11 to the image recording unit 20. The medium supply unit 12 includes a ring-shaped belt supported on the inside by two rollers, and the recording medium P is removed from the paper feed tray 11 by rotating the roller while the recording medium P is placed on the belt. It is conveyed to the image recording unit 20.

  The image recording unit 20 includes a transport unit 21 (moving unit), a delivery unit 22, a heating unit 23, a head unit 24 (ink ejection unit), a fixing unit 25, an imaging unit 26 (imaging unit), and a delivery. Part 27 and the like.

  The transport unit 21 holds a recording medium P placed on the transport surface (outer peripheral surface) of a cylindrical transport drum 211, and the transport drum 211 is a rotating shaft extending in the width direction perpendicular to the drawing in FIG. The conveyance drum 211 and the recording medium P on the conveyance drum 211 are conveyed in the conveyance direction (movement direction) by rotating around the cylinder axis. The transport drum 211 includes a claw portion and a suction portion (not shown) for holding the recording medium P on the transport surface. The recording medium P is held on the conveyance surface by the end being pressed by the claw portion and sucked to the conveyance surface by the intake portion. The transport unit 21 includes a transport drum motor (not shown) for rotating the transport drum 211, and the transport drum 211 rotates by an angle proportional to the rotation amount of the transport drum motor.

  The delivery unit 22 delivers the recording medium P conveyed by the medium supply unit 12 of the paper supply unit 10 to the conveyance unit 21. The delivery unit 22 is provided at a position between the medium supply unit 12 and the conveyance unit 21 of the paper supply unit 10, and picks up one end of the recording medium P conveyed from the medium supply unit 12 by the swing arm unit 221. Then, it is delivered to the transport unit 21 via the delivery drum 222.

  The heating unit 23 is provided between the arrangement position of the delivery drum 222 and the arrangement position of the head unit 24, and the recording medium P conveyed by the conveyance unit 21 has a temperature within a predetermined temperature range. Heat P. The heating unit 23 includes, for example, an infrared heater, and energizes the infrared heater based on a control signal supplied from the control unit 40 (FIG. 3) to cause the infrared heater to generate heat.

  The head unit 24 is disposed on the recording medium P from a nozzle opening provided on an ink discharge surface facing the conveyance surface of the conveyance drum 211 at an appropriate timing according to the rotation of the conveyance drum 211 on which the recording medium P is held. Then, an image is recorded by performing a recording operation of ejecting ink. The head unit 24 is disposed such that the ink discharge surface and the transport surface are separated by a predetermined distance. In the ink jet recording apparatus 1 of the present embodiment, four head units 24 respectively corresponding to four color inks of yellow (Y), magenta (M), cyan (C), and black (K) are transported in the recording medium P. They are arranged so as to be arranged at predetermined intervals in the order of Y, M, C, and K colors from the upstream side.

FIG. 2 is a schematic diagram showing the configuration of the head unit 24. FIG. 2 is a plan view of the entire head unit 24 as viewed from the side facing the conveyance surface of the conveyance drum 211.
In the present embodiment, the head unit 24 includes four recording heads 242 (ejection heads), and in each recording head 242, recording elements having nozzles 243 that eject ink are two-dimensionally arranged. Each of the recording elements communicates with a pressure chamber (channel) for storing ink, a piezoelectric element provided on a wall surface of the pressure chamber, an electrode for applying a voltage to the piezoelectric element to generate an electric field, and a pressure chamber. And a nozzle 243 for discharging ink in the pressure chamber. When a driving signal for deforming the piezoelectric element is input to the recording element, the pressure chamber is deformed by the deformation of the piezoelectric element and the pressure in the pressure chamber changes, and ink is ejected from the nozzle 243 communicating with the pressure chamber. . The amount of ink ejected from the nozzle 243 can be adjusted by changing the amplitude of the voltage of the drive signal. FIG. 2 shows the positions of the ink discharge ports of the nozzles 243 that are the constituent elements of the printing element.

As shown in FIG. 2, each recording head 242 has a configuration in which four nozzle arrays 2421 including a plurality of nozzles 243 arranged one-dimensionally in the width direction are combined. In each recording head 242, four nozzle rows 2421 having the same nozzle array are combined by being shifted in the width direction by a quarter of the arrangement interval of the nozzles 243 in each nozzle row 2421. The positions in the width direction of the nozzles 243 in the nozzle row 2421 are different from each other, and the intervals between the nozzles 243 in the width direction are uniform. With the configuration having the nozzles 243 arranged two-dimensionally in this way, each recording head 242 can perform recording with a resolution of 1200 dpi (dot per inch) in the width direction. Each recording head 242 is provided so that the arrangement direction (attachment angle with respect to the attachment member 244) can be adjusted, and the position and interval of the nozzle 243 in the width direction of the recording head 242 are finely adjusted by adjusting the arrangement direction. be able to. In the present embodiment, the arrangement direction of the recording heads 242 is represented by the arrangement direction of the nozzle rows 2421, and the angle formed by the conveyance direction and the arrangement direction is described as a relative angle θ (usually 90 degrees).
In the inkjet recording apparatus 1 of the present embodiment, several hundred nozzles 243 are provided in each nozzle row 2421. However, in FIG. 2, the number of nozzles 243 included in the nozzle row 2421 is omitted to seven. I draw. Further, the arrangement direction of the nozzle rows 2421 in each recording head 242 is not limited to the width direction orthogonal to the conveyance direction, and may be a direction that intersects the conveyance direction at an angle other than a right angle.

Further, the four recording heads 242 include ranges in which the arrangement ranges of the nozzles 243 in the width direction are different from each other, and a range in which ink can be ejected from the nozzles 243 in the width direction in the entire four recording heads 242 is continuously connected. With such a positional relationship, the line head is configured by being arranged in a staggered pattern so that the arrangement ranges in the width direction partially overlap each other.
In the head unit 24 having such a configuration, the position in the transport direction of the nozzle 243 differs depending on the position in the transport direction of the recording head 242 and the position in the transport direction of each nozzle row 2421 in the recording head 242. By adjusting the ink discharge timing according to the position of each nozzle 243 in the transport direction, ink is discharged from each nozzle 243 to the same position in the transport direction on the recording medium P.
In the arrangement of the staggered recording heads 242, the arrangement ranges of the nozzles 243 in the width direction in a pair of adjacent recording heads 242 may be partially overlapped. In this case, in the overlapping range where the arrangement ranges of the nozzles 243 overlap, ink may be ejected from the nozzles 243 belonging to any one of the pair of recording heads 242 at each position in the width direction. Further, the number of recording heads 242 included in the head unit 24 may be two or three, or may be five or more.

  The arrangement range in the width direction of the nozzles 243 included in the head unit 24 covers the width in the width direction of an area in which an image can be recorded in the recording medium P transported by the transport unit 21. The head unit 24 is used at a fixed position during image recording, and sequentially ejects ink at different intervals (conveyance direction intervals) to different positions in the conveyance direction according to the conveyance of the recording medium P. Record an image using the single pass method. In this embodiment, the conveyance direction interval is an interval at which the recording resolution in the conveyance direction is 1200 dpi.

  In the recording head 242, the ink discharge state is set to the initial setting due to variations in processing when forming the nozzles 243, variations in characteristics of the piezoelectric elements, clogging of the nozzles 243, or clogging due to adhesion of foreign matters to the nozzle openings. Different nozzles 243 may result. Here, the different ink discharge states include the ink discharge direction (flight direction of ejected ink droplets), the ink discharge amount (volume of ejected ink droplets), the speed of ejected ink droplets, and the like. Say different. Of these, when the ink ejection direction changes from the initial setting, the overlapping state of the inks ejected from the adjacent nozzles changes, which affects the color of the image recorded by the recording head 242. A method for adjusting the color of the image in such a case will be described later.

As the ink ejected from the nozzle 243 of the recording element, an ink that has a property of changing in a gel or sol state depending on the temperature and being cured by irradiating energy rays such as ultraviolet rays is used.
In this embodiment, ink that is gel-like at room temperature and becomes sol-like when heated is used. The head unit 24 includes an ink heating unit (not shown) that heats the ink stored in the head unit 24. The ink heating unit operates under the control of the control unit 40, and supplies the ink to a sol-like temperature. Heat. The recording head 242 discharges ink that has been heated to form a sol. When the sol-like ink is ejected onto the recording medium P, the ink droplets land on the recording medium P, and then naturally cool to solidify on the recording medium P due to natural cooling.

  The fixing unit 25 has an energy beam irradiation unit arranged across the width in the width direction of the conveyance unit 21, and ultraviolet rays or the like from the energy beam irradiation unit to the recording medium P placed on the conveyance unit 21. The ink ejected on the recording medium P is cured and fixed by irradiating energy rays. The energy ray irradiating unit of the fixing unit 25 is arranged to face the conveying surface between the arrangement position of the head unit 24 and the arrangement position of the delivery drum 271 of the delivery unit 27 in the conveying direction.

The imaging unit 26 is arranged so as to be able to read the surface of the recording medium P on the conveyance surface at a position between the fixing position of the ink by the fixing unit 25 and the arrangement position of the transfer drum 271 in the conveyance direction. An image recorded on the transported recording medium P is read within a predetermined reading range, and imaging data of the image is output.
In the present embodiment, the imaging unit 26 includes a light source that irradiates light to the recording medium P conveyed by the conveying drum 211 and an imaging element that detects the intensity of reflected light of the light incident on the recording medium P in the width direction. And a line sensor 262 (FIG. 3) arranged in a line. Specifically, the line sensor 262 is provided with three image sensor rows each including image sensors arranged in the width direction, and R (red), G (green), A signal corresponding to the intensity of the wavelength component of B (blue) is output. Imaging elements corresponding to R, G, and B are, for example, R, G, or B in a light receiving portion of a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor that includes a photodiode as a photoelectric conversion element. A filter in which a color filter that transmits light having a wavelength component of is arranged can be used. The reading resolution of each image sensor of the line sensor 262 is, for example, 600 dpi in the width direction. That is, this image sensor may acquire an image with a resolution lower than the resolution corresponding to the arrangement interval of the recording elements. Further, the output timing of the signal from the line sensor 262 is adjusted so that the reading resolution in the transport direction is 600 dpi.
The signal output from the line sensor 262 is output to the control unit 40 as imaging data by the imaging control unit 261 (FIG. 3).
Note that the configuration of the imaging unit 26 is not limited thereto, and for example, an area sensor may be used instead of the line sensor 262.

  The delivery unit 27 includes a belt loop 272 having an annular belt supported on the inside by two rollers, and a cylindrical delivery drum 271 that delivers the recording medium P from the transport unit 21 to the belt loop 272. The recording medium P transferred from the transport unit 21 onto the belt loop 272 by the transfer drum 271 is transported by the belt loop 272 and sent to the paper discharge unit 30.

  The paper discharge unit 30 includes a plate-shaped paper discharge tray 31 on which the recording medium P sent out from the image recording unit 20 by the delivery unit 27 is placed.

FIG. 3 is a block diagram showing the main functional configuration of the inkjet recording apparatus 1.
The inkjet recording apparatus 1 includes a heating unit 23, a head unit 24 having a head control unit 241, a head driving unit 2422, and a head position adjusting mechanism 245, a fixing unit 25, an imaging unit having an imaging control unit 261, and a line sensor 262. 26, a control unit 40 (test image recording control unit, adjustment information generation unit), a conveyance drive unit 51, an operation display unit 52, an input / output interface 53, a bus 54, and the like.

The head control unit 241 outputs various control signals and image data to the head driving unit 2422 provided in the recording head 242 at an appropriate timing according to the control signal from the control unit 40.
The head driving unit 2422 supplies a driving signal for deforming the piezoelectric element to the recording element of the recording head 242 according to the control signal or image data input from the head control unit 241, and from the opening of each nozzle 243. Ink is ejected.

  The head position adjustment mechanism 245 adjusts the mounting angle of the recording head 242 to the mounting member 244 in order to adjust the relative angle θ between the arrangement direction of the nozzle rows 2421 in the recording head 242 and the transport direction. In the present embodiment, the head position adjusting mechanism 245 operates by being electrically driven in response to a control signal input from the control unit 40. The head position adjustment mechanism 245 may be driven and operated in accordance with a setting value input by an input operation on the operation display unit 52 by the user, or the recording head 242 may be operated by a user operation. The relative angle θ may be adjusted manually directly.

  The imaging control unit 261 causes the line sensor 262 to capture an image on the recording medium P based on the control signal input from the control unit 40. In addition, the imaging control unit 261 performs processing such as current-voltage conversion, amplification, noise removal, and analog-digital conversion on the signal output from the line sensor 262 by the imaging, and as imaging data indicating the luminance value of the read image Output to the control unit 40.

  The control unit 40 includes a CPU 41 (Central Processing Unit), a RAM 42 (Random Access Memory), a ROM 43 (Read Only Memory), and a storage unit 44.

  The CPU 41 reads various control programs and setting data stored in the ROM 43, stores them in the RAM 42, executes the programs, and performs various arithmetic processes. The CPU 41 controls the overall operation of the inkjet recording apparatus 1.

  The RAM 42 provides a working memory space to the CPU 41 and stores temporary data. The RAM 42 may include a nonvolatile memory.

  The ROM 43 stores various control programs executed by the CPU 41, setting data, and the like. In place of the ROM 43, a rewritable nonvolatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory may be used.

  In the storage unit 44, a print job (image recording command) input from the external device 2 via the input / output interface 53, image data of a normal image to be recorded according to the print job, image data of a test image described later, The imaging data generated by the imaging unit 26 is stored. As the storage unit 44, for example, an HDD (Hard Disk Drive) is used, and a DRAM (Dynamic Random Access Memory) or the like may be used in combination.

  The transport drive unit 51 supplies a drive signal to the transport drum motor of the transport drum 211 based on the control signal supplied from the control unit 40 to rotate the transport drum 211 at a predetermined speed and timing. Further, the transport drive unit 51 supplies a drive signal to a motor for operating the medium supply unit 12, the delivery unit 22, and the delivery unit 27 based on the control signal supplied from the control unit 40, and the recording medium P Is supplied to the transport unit 21 and discharged from the transport unit 21.

  The operation display unit 52 includes a display device such as a liquid crystal display and an organic EL display, and operation keys and an input device such as a touch panel disposed on the screen of the display device. The operation display unit 52 displays various information on the display device, converts a user input operation to the input device into an operation signal, and outputs the operation signal to the control unit 40.

  The input / output interface 53 mediates data transmission / reception between the external device 2 and the control unit 40. The input / output interface 53 is configured by any one of various serial interfaces, various parallel interfaces, or a combination thereof.

  The bus 54 is a path for transmitting and receiving signals between the control unit 40 and other components.

  The external device 2 is a personal computer, for example, and supplies a print job, image data, and the like to the control unit 40 via the input / output interface 53.

Next, a method for adjusting the arrangement direction of the recording head 242 in the inkjet recording apparatus 1 of the present embodiment will be described.
In the inkjet recording apparatus 1 of the present embodiment, an image corresponding to image data is recorded using a long head unit 24 in which four recording heads 242 are connected in the longitudinal direction. For this reason, it is desirable that the colors of images recorded by the recording heads 242 according to the same image data are the same. Here, the color of the image to be recorded is defined by three elements of hue, saturation, and brightness. Hereinafter, the degree of color of a recorded image corresponding to predetermined image data by the recording head 242 is referred to as color reproducibility.
However, as described in detail below, the color reproducibility of the recording head 242 is often caused by variations in the arrangement interval of the nozzles 243 in the recording head 242 and variations in the ink discharge direction from the nozzles 243. Since the recording heads 242 are different, if color reproducibility is not adjusted, color unevenness occurs at positions corresponding to the joints of the recording heads 242 in the recorded image, leading to deterioration in image quality. The color reproducibility of each recording head 242 can be adjusted by changing the ink landing position from the nozzle 243 by adjusting the arrangement direction of the recording head 242 (that is, by adjusting the relative angle θ). In this embodiment, the arrangement direction of the recording heads 242 is adjusted so that the variation in color reproducibility of the four recording heads 242 is reduced, and preferably the color reproducibility is the same.

Hereinafter, first, adjustment of color reproducibility by changing the relative angle θ of the recording head 242 will be described.
FIG. 4 is a diagram illustrating an example of a landing position of the ink ejected from the recording head 242 on the recording medium P. In the upper part of FIG. 4, the ink ejection surface of one recording head 242 </ b> A among the four recording heads 242 of the head unit 24 is shown. In the lower part of FIG. 4, recording of each ink droplet ejected from each nozzle 243 and landed on the recording medium P when a solid image (an image in which all pixels have the maximum gradation) is recorded by the recording head 242A. The landing range on the medium P (the range where the wetting spreads) is indicated by a circle. The center of the circle indicates the ink landing position. Actually, in many cases, the amount of ejected ink is adjusted so that the landing range of ink droplets is a wider range including a plurality of adjacent ink landing positions, but it is difficult to see in FIG. In order to avoid this, the landing range is drawn with a size almost in contact with each other. Hereinafter, the four nozzle rows 2421 in the recording head 242A are referred to as nozzle rows 2421a to 2421d in order from the upstream side in the transport direction.

  The recording head 242A is attached to the attachment member 244 in a state where the relative angle θ is 90 degrees. In the recording head 242A, the relative angle θ is 90 degrees, the intervals Δ of the nozzles 243 in the width direction are uniform, and the ink ejection direction from the nozzles 243 hardly varies. For this reason, the landing positions of the ink discharged from each nozzle 243 are substantially equal in the width direction, and the overlapping state of the inks discharged from the adjacent nozzles 243 and landing on the recording medium P is substantially uniform. It has become. That is, the recording head 242A is an appropriate recording head capable of landing ink at a position almost as originally set.

FIG. 5 is a diagram illustrating an example of landing positions on the recording medium P of ink ejected from the recording head 242B different from the recording head 242A among the four recording heads 242 in the head unit 24.
The recording head 242B is attached to the attachment member 244 in a state where the relative angle θ is 90 degrees. Further, in the recording head 242B, the nozzle rows 2421a are combined with the nozzle rows 2421a being shifted from the originally set position in the right direction in FIG. 5 and the nozzle rows 2421b being shifted in the left direction. For this reason, the variation in the interval Δ of the nozzles 243 in the width direction is larger than the variation in the interval Δ in the recording head 242A. As a result, the landing position intervals of the ink ejected from the adjacent nozzles 243 on the recording medium P are non-uniform, and as a result, the overlapping state of the inks is non-uniform. Specifically, the coverage ratio between the ink ejected from the nozzle row 2421b and the ink ejected from the nozzle row 2421c (the ratio of the portion overlapping the landing range of other ink droplets in the landing range of the ink droplets) ), And the coverage ratio between the ink ejected from the nozzle array 2421a and the ink ejected from the nozzle array 2421d is larger than the appropriate coverage ratio. Further, the coverage between the ink ejected from the nozzle array 2421a and the ink ejected from the nozzle array 2421b is smaller than the appropriate coverage (in FIG. 5, the landing ranges do not overlap with each other). ) Here, the appropriate coverage is, for example, the coverage of ink ejected by the appropriate recording head 242A of FIG.

  For this reason, in the solid image recorded by the recording head 242B of FIG. 5, the ratio of the overlapping region R2 where the ink landing ranges overlap in the image and the non-covering region R3 not included in any landing range However, it is relatively larger than the solid image recorded by the appropriate recording head 242A. Further, in the solid image in FIG. 5, the ratio of the single-layer region R <b> 1 in which the ink landing area is not overlapped and the ink is a single layer is relatively smaller than the solid image in FIG. 4. .

Here, since the thickness of the ink layer is larger in the overlapping region R2 than in the single layer region R1, the color is darker than that in the single layer region R1. Further, in the uncovered region R3, the color of the recording medium P appears as it is. Since the color expressed by the landed ink is a color in which the color of the single layer region R1, the color of the overlapping region R2, and the color of the non-covered region R3 are mixed according to the ratio of each region, the single layer region R1 When the ratios of the overlapping region R2 and the non-covering region R3 are different, colors expressed according to the image data are different from each other. Therefore, there is a difference in the color reproducibility of the recorded image between the proper recording head 242A and the recording head 242B in FIG.
Further, the difference in the colors of the images recorded by the recording head 242A and the recording head 242B can occur not only in the solid image but also in the intermediate gradation. That is, in the recording head 242A and the recording head 242B, in each of the gradations in which the inks ejected from the adjacent nozzles 243 and landed at least partially overlap among the recordable minimum gradation to the maximum gradation. The colors used will be different.

  Even when the nozzles 243 are arranged at regular intervals as shown in FIG. 4 when the nozzles 243 are arranged at regular intervals as shown in FIG. 4, if the variation in the ink ejection direction from each nozzle 243 is large, the ink landing position is shifted from the appropriate position. Variations occur in the overlapping state of the landed inks. For this reason, as in FIG. 5, the ratio of the overlapping region R2 and the non-covering region R3 in the recorded image increases, and a difference in color reproducibility occurs with the appropriate recording head 242A.

  The difference in the color of the recording image between the recording heads 242 due to the variation in the interval Δ of the nozzles 243 and the variation in the ink discharge direction depends on the interval between the nozzles 243, the size of the ink droplets, and the like. * B * Coordinate system color difference ΔE * can be as large as three. This is a level at which the color difference can be clearly felt in the adjacent comparison. Therefore, when the recording unit 242 having different color reproducibility as described above is included in the head unit 24, a color shift that cannot be ignored between the recording heads 242 occurs in an image recorded by the head unit 24, and the image quality of the recording image is increased. Incurs a decline.

Here, if the ink landing positions in all the recording heads 242 can be adjusted to the appropriate positions shown in FIG. 4 by adjusting the relative angle θ of the recording heads 242, the color reproducibility of the recording heads 242 can be made uniform. However, such adjustment is difficult for the following reasons.
That is, first, when manufacturing the recording head 242, it is difficult to accurately align the nozzle rows 2421 without any slight deviation. In addition, since the variation in the ink ejection direction from the nozzle 243 occurs later due to the initial failure of the nozzle 243 and the adhesion of foreign matter to the nozzle opening, etc., the occurrence of variation in the ink ejection direction is completely prevented. It is difficult. For these reasons, it is basically unavoidable that the recording head 242 has some variation in the ink landing position interval in the width direction.
In addition, since the dispersion method of the landing position intervals is different for each recording head 242, even if the relative angle θ is adjusted in each of the four recording heads 242, and the ink landing position interval is made to be the most uniform, it is between the recording heads. There remains a difference in how the ink landing position intervals vary, and therefore there remains a difference in color reproducibility between recording heads. That is, each print head 242 has the highest color reproducibility in each head because the error in the arrangement position of the nozzle row 2421 and the variation in the ink ejection direction are different from each other and the range of adjustable color reproducibility is different from each other. Even if the relative angle θ is adjusted as described above, it is difficult to eliminate the variation in color reproducibility between the recording heads.

  Therefore, in the present embodiment, the relative angle θ is set so as to increase the variation in the ink landing position interval in the other recording heads 242 in accordance with the recording head 242 (reference ejection head) having the largest variation in the ink landing position interval. Adjusting the color reproducibility of the recording heads 242. In the present embodiment, it is assumed that the variation in the ink landing position interval among the four recording heads 242 of the head unit 24 is the largest in the recording head 242B shown in FIG.

FIG. 6 is a diagram for explaining a method for adjusting variation in ink landing position interval by adjusting the relative angle θ.
FIG. 6 shows the ink landing position when the proper recording head 242A shown in FIG. 4 is rotated so that the relative angle is θa (<90 degrees) and the arrangement direction is adjusted. By such rotation of the recording head 242A, the variation in the interval Δ of the nozzles 243 in the width direction is increased. As a result, the variation in the landing position interval of the ink ejected from each nozzle is increased, and the nozzles 243 are ejected from adjacent nozzles 243. Thus, the overlapping state of the inks that land on the recording medium P is not uniform. Specifically, the coverage of the discharged ink is appropriate between the nozzle row 2421a and the nozzle row 2421b, between the nozzle row 2421b and the nozzle row 2421c, and between the nozzle row 2421c and the nozzle row 2421d. It is larger than the coverage. Further, the coverage between the ink ejected from the nozzle row 2421a and the ink ejected from the nozzle row 2421d is smaller than the appropriate coverage (in FIG. 6, the landing ranges do not overlap with each other). ) In FIG. 6, the relative angle θa is adjusted so that the ratio of the single-layer area R1, the overlapping area R2, and the non-covered area R3 in the recorded image is substantially equal to the ratio in the recording head 242B shown in FIG. Yes. As a result, the color reproducibility becomes substantially equal between the recording head 242A after the rotation adjustment and the recording head 242B.
Similarly for the recording heads 242 other than the recording heads 242A and 242B, the color of the four recording heads 242 is adjusted by adjusting the relative angle θ so that the variation in the ink landing position interval is equivalent to that of the recording head 242B. Variation in reproducibility can be suppressed.

Next, a method for specifying an appropriate adjustment amount (appropriate adjustment amount in the arrangement direction) (adjustment information) of the relative angle θ in each recording head 242 will be described.
FIG. 7 is a diagram illustrating an example of the test image 70 used for specifying the adjustment amount of the relative angle θ. In FIG. 7, the portion recorded by the two recording heads 242 in the test image 70 is shown enlarged, and the recording medium P and the head unit 24 are arranged so that the positional relationship between the portion and the recording head 242 can be understood. It is drawn. The test image 70 is recorded in a separate area on the recording medium P by each of the four head units 24 or on a different recording medium P.

  The test image 70 includes a plurality of lines 71 extending in the transport direction. Each of the plurality of lines 71 is recorded by continuously ejecting ink from one nozzle 243 to the recording medium P conveyed in the conveyance direction. In the test image 70, a plurality of lines 71 recorded by every third nozzle 243 in the width direction are arranged to form a line group 71G. Further, four line groups 71G are recorded in the transport direction, and the nozzles 243 that record the lines 71 are shifted one by one between the adjacent line groups 71G.

  In such a test image 70, the position in the width direction of each line 71 indicates the landing position of the ink ejected from each nozzle 243 in the width direction on the recording medium P. Therefore, by analyzing the imaging data of the test image 70 by the imaging unit 26, it is possible to acquire the variation in the landing position intervals of the inks from the nozzles 243.

In the method for specifying the adjustment amount of the relative angle θ in the present embodiment, first, the distance d in the width direction between adjacent lines 71 in each line group 71G is acquired, and then corresponds to each of the four recording heads 242. A variation σ of the interval d is calculated. Then, the recording head 242 having the largest variation σ is specified. Hereinafter, the recording head 242 is referred to as a reference recording head, and the variation σ in the reference recording head is referred to as variation σmax.
Here, the variation σ is a value having a correlation with the overlapping state of the inks. That is, as the variation σ increases, the variation in the landing position interval in the width direction of the ink increases, and the average value of the coverage ratio between the inks increases. Further, as described above, the ink overlap state has a correlation with the color reproducibility. Therefore, the variation σ of the present embodiment is an aspect of color reproducibility information relating to color reproducibility according to the arrangement direction of each of the plurality of recording heads 242 (according to the relative angle θ).

  Next, for each recording head 242 other than the reference recording head, the relationship between the relative angle θ and the variation σ when the relative angle θ is changed is calculated. Specifically, the displacement amount in the width direction of each nozzle 243 when the relative angle θ is changed by a predetermined value is calculated, and the displacement of each line 71 in the imaging data of the test image 70 according to the displacement amount of the nozzle. A later position is calculated. And the dispersion | variation (sigma) of the space | interval d of each line 71 after a displacement is calculated. Further, the calculation of the variation σ is performed for each of a plurality of relative angles θ. The calculation of the variation σ may be performed for each value of the adjustable relative angle θ, or the variation σ may be calculated for several relative angles θ and the relative angle θ and the variation σ may be calculated. The relational expression (approximate expression) may be obtained.

For each recording head 242, the relative angle θ at which the variation σ matches the variation σmax is specified as an appropriate relative angle, and the adjustment amount of the relative angle θ is determined. When the variation in the interval d of the lines 71 associated with each recording head 242 is equal to σmax, the variation in the overlapping state of the ink landing ranges is substantially the same. As a result, the single-layer region R1, the overlapping region R2, and The ratio of the non-covering region R3 is substantially the same, and the color reproducibility is substantially the same between the recording heads. Therefore, the color reproducibility of the four recording heads 242 in the head unit 24 can be made uniform by adjusting the relative angles of the recording heads 242 by the adjustment amount determined as described above. That is, the expressed colors are adjusted to be substantially the same in each of the minimum gradation and the maximum gradation that can be recorded by each recording head 242.
If the position in the transport direction of each nozzle 243 is deviated from the initial setting by adjusting the relative angle θ of the recording head 242, the timing of ink ejection from the nozzle 243 depends on the magnitude of the deviation. Adjusted.

  Next, a control procedure by the control unit 40 (CPU 41) of the recording head attachment adjustment process performed in the inkjet recording apparatus 1 will be described.

FIG. 8 is a flowchart showing a control procedure by the control unit 40 of the recording head attachment adjustment process.
The recording head attachment adjustment process is performed by the user from the operation display unit 52 when the inkjet recording apparatus 1 is shipped, the head unit 24 is replaced, or when a color misregistration in the recorded image occurs. It is executed when a predetermined input operation instructing the attachment adjustment of 242 is performed.

  When the recording head attachment adjustment process is started, the control unit 40 causes the head unit 24 to record the test image 70 on the recording medium P (step S101: test image recording step). Here, the control unit 40 first outputs a drive signal from the conveyance driving unit 51 to the conveyance drum motor of the conveyance drum 211 to start the rotation operation of the conveyance drum 211. Next, a control signal is output to the conveyance driving unit 51 to operate the paper feeding unit 10, the delivery unit 22, and the conveyance unit 21 to place the recording medium P on the conveyance surface of the conveyance drum 211. Next, the control unit 40 outputs the test image image data and control signals stored in the storage unit 44 from the head control unit 241 to each recording head 242 (head drive unit 2422) at an appropriate timing according to the rotation of the transport drum 211. ), The test image 70 is recorded on the recording medium P by ejecting ink from the nozzles 243 of the recording heads 242 to the recording medium P. Further, the control unit 40 fixes the ink onto the recording medium P by irradiating the ink with a predetermined energy beam at the timing when the recording medium P to which the ink has been applied has moved to the position of the fixing unit 25. Let me.

  The control unit 40 causes the imaging unit 26 to capture the test image 70 on the recording medium P (step S102). That is, the control unit 40 outputs a control signal to the imaging control unit 261 at a timing when the test image 70 on the recording medium P moves to the imaging position by the imaging unit 26 according to the rotation of the transport drum 211, and the imaging unit 26 Imaging of the test image 70 is started. The imaging control unit 261 repeatedly acquires signals from the line sensor 262 at predetermined time intervals, generates imaging data of the test image 70, and stores the imaging data in the storage unit 44.

  The control unit 40 acquires the variation σ of the ink landing position interval of each recording head 242 based on the imaging data of the test image 70 (step S103). That is, the control unit 40 identifies the interval d between all the lines 71 in each line group 71G from the imaging data of the test image 70, and calculates the variation σ of the interval d for each recording head 242 based on the identification result. .

  The control unit 40 identifies the reference recording head having the maximum variation σ, acquires the variation value (σmax) related to the reference recording head, and stores it in the RAM 42 (step S104).

  The control unit 40 determines the adjustment amount of the relative angle θ at which the variation value of the ink landing position interval is σmax for each recording head 242 other than the reference recording head (step S105: adjustment information generation step). That is, the control unit 40 calculates a variation σ corresponding to a plurality of different relative angles θ for each recording head 242, or obtains a relational expression between the relative angle θ and the variation σ, and the variation σ is equal to σmax. The relative angle θ at which it becomes (or the closest value) is specified, the adjustment amount of the relative angle θ is determined, and adjustment information related to the adjustment amount is generated.

  The control unit 40 adjusts the relative angle θ of each recording head 242 based on the determined adjustment amount of the relative angle θ (step S106: adjustment step). That is, the control unit 40 outputs a control signal to the head position adjustment mechanism 245 so that the head position adjustment mechanism 245 performs an operation of adjusting the relative angle θ of each recording head 242 by the adjustment amount determined in step S105. . When the process of step S106 ends, the control unit 40 ends the recording head attachment adjustment process.

  When the head position adjusting mechanism 245 is manually operated, the control unit 40 outputs the adjustment amount specifying result by a predetermined method in step S105, and attaches the recording head without performing the process of step S106. The adjustment process ends. In this case, after the recording head mounting adjustment process is completed, the user may read the output information and manually adjust the relative angle θ. In addition, as an output method of the adjustment amount in step S105, for example, the adjustment result is output to the operation display unit 52 in a predetermined manner, or the adjustment amount of the relative angle θ is included in the margin of the recording medium P. For example, a method of recording information related to the adjustment of the relative angle θ may be used.

(Modification 1)
Next, the modification 1 of the said embodiment is demonstrated. This modification is different from the above embodiment in the content of the test image used for specifying the adjustment amount of the relative angle θ and the adjustment amount specifying method. Hereinafter, differences from the above embodiment will be described.

In this modification, the relative angle θ of the recording head 242 is adjusted to a plurality of different values, and the recording head 242 adjusted to each relative angle θ causes a gradation image of a predetermined density as a test image on the recording medium P. To be recorded. The relationship (color reproducibility information) between the density of each test image read from the image data of the test image and the relative angle θ in the recording head 242 used for recording the test image is as follows. To be acquired. Thereafter, the adjustment amount of the relative angle θ of each recording head 242 is determined so that the density of the test image recorded by each recording head 242 of the head unit 24 becomes equal.
It should be noted that the color (instead of the density) may be acquired from the image data of the test image, and the relationship (color reproducibility information) between the relative angle θ and the color of the test image may be acquired.

  The density of the test image of this modification is set so that the inks ejected from the adjacent nozzles 243 partially overlap each other. Therefore, as the test image image data, for example, the maximum gradation or intermediate gradation data close to the maximum gradation is used, depending on the interval between the nozzles 243, the amount of ink droplets, and the intermediate gradation expression method. be able to.

(Modification 2)
Next, Modification 2 of the above embodiment will be described. Similar to the first modification, the present modification is different from the above embodiment in the content of the test image used for specifying the adjustment amount of the relative angle θ and the adjustment amount specifying method. Hereinafter, differences from the above embodiment will be described.

  In this modification, the relative angle θ of the recording head 242 is adjusted to a plurality of different values, and the recording head 242 adjusted to each relative angle θ causes a gradation image of a predetermined density as a test image on the recording medium P. To be recorded. Then, the relationship (color reproducibility information) between the information (gloss information) relating to the gloss of each test image read from the image data of the test image and the relative angle θ in the recording head 242 used for recording the test image. Are obtained for each recording head 242. Thereafter, the adjustment amount of the relative angle θ of each recording head 242 is determined so that the gloss of the test image recorded by each recording head 242 of the head unit 24 becomes equal.

FIG. 9 is a diagram for explaining the relationship between the overlapping state of ink and gloss.
In the upper part of FIG. 9, the overlapping state and landing range of the ink on the surface of the recording medium P are shown, and in the lower part of FIG. 9, the ink transport direction in the state where the landed ink has spread as shown in the upper part of FIG. 9. A cross section in a plane perpendicular to is shown. Further, the left side of FIG. 9 shows a case where the variation in the ink landing position interval is large in the width direction, and the right side shows a case where the ink landing position interval is uniform.

As shown on the left side of FIG. 9, when the variation in the ink landing position is large and the coverage of the ink is large, the ink droplets are separated on the recording medium P as shown in the lower cross-sectional view. The ink droplets on the recording medium P tend to be large. For this reason, the surface of the ink solidified and fixed on the recording medium P has a larger proportion of the portion that is not parallel to the surface of the recording medium P. Therefore, the light incident on the ink is directed in various directions on the ink surface. Scattered and less glossy.
On the other hand, as shown on the right side of FIG. 9, when the landing positions of the inks are uniform and the coverage of the inks is small, the ink droplets are spread over a wide area on the recording medium P as shown in the lower cross-sectional view. And the height of the ink on the recording medium P tends to be small. For this reason, the ratio of the portion of the ink solidified and fixed on the recording medium P that is parallel or nearly parallel to the surface of the recording medium P increases, so that the light incident on the ink is regularly reflected on the ink surface. The ratio that is applied increases and the gloss increases.
Thus, since the gloss of the recording medium P reflects the distribution of ink on the recording medium P, the gloss information relating to the gloss has a correlation with the overlapping state of the inks, and thus with the color reproducibility of the recording head 242. The color reproducibility can be made uniform by adjusting the relative angle θ so that the gloss of the test images recorded by the respective recording heads 242 is equal.

The density of the test image of this modification is set to such a density that inks at appropriate landing position intervals partially overlap, and inks that do not overlap each other are generated when variations in landing position intervals increase.
In addition, as a method for acquiring gloss information related to the gloss of this modification, for example, light is incident from a light source at a predetermined incident angle (for example, 60 degrees), and the amount of reflected light in the direction perpendicular to the recording medium P is calculated. A measuring method can be used.

As described above, the ink jet recording apparatus 1 of the present embodiment has a plurality of recording heads 242 each provided with a plurality of nozzles 243 for ejecting ink, and each of the plurality of recording heads 242 adjusts the arrangement direction. The head unit 24 that can be provided, a transport unit 21 that relatively moves the head unit 24 and the recording medium P, and a control unit 40 are provided. The control unit 40 is a recording medium P that is relatively moved by the transport unit 21. On the other hand, the head unit 24 causes the ink to be ejected from the plurality of nozzles 243 in each of the plurality of recording heads 242, so that the color reproducibility information relating to the color reproducibility according to the arrangement direction of each of the plurality of recording heads 242 is obtained. Is recorded on the recording medium P (test image recording control means), and the color acquired from the imaging data of the test image 70 is recorded. Based on the actuality information, an adjustment amount (adjustment information) of the relative angle θ for adjusting the arrangement direction so as to reduce the variation in color reproducibility among the plurality of recording heads 242 is generated and output (adjustment information generation) means).
According to such a configuration, the recording head 242 can suppress the variation in color reproducibility between the recording heads in the head unit 24 and the occurrence of color misregistration between the recording heads due to the variation in the color reproducibility. The amount of adjustment of the relative angle θ can be acquired. Therefore, the occurrence of color misregistration between the recording heads can be suppressed by adjusting the arrangement direction of the recording heads 242 based on the adjustment amount. Further, by determining the adjustment amount of the relative angle θ based on the reading result of the test image recorded on the recording medium P, not only the variation in color reproducibility due to the variation in the arrangement interval of the nozzles 243 but also the nozzle 243. The variation in color reproducibility due to the deviation of the ink ejection direction from the ink can also be appropriately suppressed.

  Further, the control unit 40 prints a test image 70 for identifying the landing position in the width direction orthogonal to the transport direction of the ink ejected from the plurality of nozzles 243 on the recording medium P relatively moved in the transport direction. Recording is performed by the unit 24 (test image recording control unit), and color reproducibility information is acquired based on the landing position interval in the width direction between the landing positions specified from the imaging data of the test image 70 (adjustment information generating unit). . According to this, the relative angle θ of the recording head 242 can be appropriately set by a simple method using the correlation between the overlapping state of the inks according to the interval between the ink landing positions and the color reproducibility of the recording head 242. Adjustment amount can be determined.

  Further, the control unit 40 acquires the color reproducibility information by specifying the variation σ of the landing position interval with respect to a plurality of different relative angles θ (adjustment information generating means). The variation σ in ink landing position interval has a correlation with the overlapping state of the landed inks, and the overlapping state of the ink has a correlation with the color reproducibility of the recording head 242. With respect to the recording head 242, the relationship between the arrangement direction of the recording head 242 and the color reproducibility can be acquired. Thereby, it is possible to determine the adjustment amount of the relative angle θ of each recording head 242 that can make the color reproducibility of the plurality of recording heads 242 of the head unit 24 uniform.

  Further, the control unit 40 sets the landing position interval of the recording heads 242 other than the reference ejection head to the variation σmax of the landing position interval of the reference recording head having the largest landing position interval variation σ of the plurality of recording heads 242. An adjustment amount of the relative angle θ that brings the variation σ closer is determined (adjustment information generation means). The minimum value of the variation σ of the landing position interval that can be adjusted in each recording head 242 is different for each recording head 242, and by adjusting the variation σ according to the recording head 242 having the largest variation σ as described above, The variation σ of the landing position intervals of the plurality of recording heads 242 in the head unit 24, and consequently the color reproducibility can be matched or brought closer together.

  In the ink jet recording apparatus 1 according to the first modification, the control unit 40 causes the head unit 24 to record a test image having a predetermined density as a test image (test image recording control unit), and is read from the imaging data of the test image. Color reproducibility information is acquired from the density of the test image and information indicating the arrangement direction of the recording head 242 (adjustment information generating means). According to such a configuration, the color reproduction information is acquired based on the color of the test image actually recorded by the recording head 242, and the adjustment amount in the arrangement direction is determined, so that there is no error related to the accuracy of the simulation. Adjustment amount can be obtained.

  Further, in the ink jet recording apparatus 1 according to the modified example 2, the control unit 40 causes the head unit 24 to record a test image of a predetermined density (test image recording control unit), and gloss information related to the gloss of the test image, and the recording head. Color reproducibility information is acquired from the information indicating the arrangement direction of 242 (adjustment information generating means). According to such a configuration, the color reproducibility information can be acquired by a simple method for measuring the gloss of the test image.

  In addition, the plurality of nozzles 243 in the recording head 242 are two-dimensionally arranged. In such a configuration, the arrangement interval of the nozzles 243 in the width direction is likely to be non-uniform according to the arrangement direction of the recording head 242, but according to the above embodiment, it is caused by the non-uniform arrangement interval of the nozzles 243. The variation in color reproducibility between recording heads can be effectively suppressed.

  Further, the plurality of nozzles 243 in the recording head 242 constitute a plurality of nozzle rows each composed of two or more nozzles 243 arranged in a predetermined direction. In such a configuration, the change in the arrangement interval of the nozzles 243 in the width direction according to the arrangement direction of the recording head 242 and the change in the ink landing position interval become regular. The relationship can be easily specified, and color reproducibility information can be acquired more easily.

  The inkjet recording apparatus 1 includes an imaging unit 26 that captures the test image 70. Thereby, the imaging data of the test image 70 can be acquired in the inkjet recording apparatus 1 and the arrangement direction of the recording head 242 can be adjusted.

  In addition, the adjustment information acquisition method for the ejection head arrangement direction according to the present embodiment uses the head unit 24 to perform ink from the plurality of nozzles 243 in each of the plurality of recording heads 242 with respect to the recording medium P relatively moved by the transport unit 21. A test image recording step for recording on the recording medium P a test image 70 capable of acquiring color reproducibility information relating to color reproducibility according to the arrangement direction of each of the plurality of recording heads 242 Based on the color reproducibility information acquired from the 70 imaging data, an adjustment amount (adjustment information) of the relative angle θ for adjusting the arrangement direction so as to reduce the variation in color reproducibility in the plurality of recording heads 242 is obtained. An adjustment information generation step of generating and outputting. According to such a method, the adjustment amount of the relative angle θ of the recording head 242 that can appropriately suppress the occurrence of color misregistration between the recording heads in the head unit 24 can be acquired.

The present invention is not limited to the above embodiment, and various modifications can be made.
For example, in the above-described embodiment and each modified example, the adjustment amount of the relative angle θ (correction angle) has been described as the adjustment information of the arrangement direction of the recording head 242, but the present invention is not limited to this. Other adjustment information for adjusting the arrangement direction of 242 may be generated. For example, when the head position adjustment mechanism 245 is a mechanism that changes the relative angle θ of the recording head 242 in accordance with the rotation amount of a predetermined adjustment screw, information indicating the rotation amount of the adjustment screw is generated as adjustment information. Also good.

  Further, in the above-described embodiment and each modified example, the color reproducibility information has been described using an example of using information regarding the variation σ of the interval Δ of the line 71 in the test image 70, the density of the test image, and the glossiness. However, the present invention is not limited thereto, and other color reproducibility information having a correlation with the color reproducibility of the recording head 242 may be acquired from the test image 70, and the adjustment amount of the relative angle θ may be determined based on the color reproducibility information.

  In the above embodiment and each modification, the adjustment amount of the relative angle θ of each recording head 242 is determined based on the variation σ of the interval d between the adjacent lines 71 in the line group 71G of the test image 70. However, the adjustment amount of the relative angle θ may be determined based on the variation in the interval between the lines 71 recorded by the nozzle 243 having the closest position in the width direction.

  In the above-described embodiment and each modification, the description has been given using the example in which each recording head 242 is provided with a plurality of nozzle rows 2421 and the nozzles 243 are two-dimensionally arranged, but instead, each recording head 242 is provided. The nozzles 243 may be one-dimensionally arranged.

  In the above embodiment, the example in which the inkjet recording apparatus 1 includes the imaging unit 26 has been described. Instead, the test image 70 is captured by an imaging apparatus separately provided outside the inkjet recording apparatus 1. Then, imaging data may be generated.

  In each of the above embodiments, the example in which the recording medium P is transported by the transport drum 211 has been described. However, the present invention is not limited to this. For example, the recording medium P is supported by two rollers and moves according to the rotation of the rollers. The recording medium P may be transported by a transporting belt.

  In the above embodiment, the single-pass inkjet recording apparatus 1 has been described as an example. However, the present invention may be applied to an inkjet recording apparatus that records an image while scanning a head unit.

  Although several embodiments of the present invention have been described, the scope of the present invention is not limited to the above-described embodiments, and includes the scope of the invention described in the claims and equivalents thereof. .

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 2 External device 10 Paper feed part 11 Paper feed tray 12 Medium supply part 20 Image recording part 21 Conveyance part 211 Conveyance drum 22 Delivery unit 23 Heating part 24 Head unit 241 Head control part 242,242A, 242B Recording head 2421 , 2421a to 2421d Nozzle row 2422 Head drive unit 243 Nozzle 244 Mounting member 245 Head position adjustment mechanism 25 Fixing unit 26 Imaging unit 261 Imaging control unit 262 Line sensor 27 Delivery unit 30 Paper discharge unit 31 Paper discharge tray 40 Control unit 41 CPU
42 RAM
43 ROM
44 Storage Unit 51 Transport Drive Unit 52 Operation Display Unit 53 Input / Output Interface 54 Bus 70 Test Image 71 Line 71G Line Group P Recording Medium R1 Single Layer Area R2 Overlapping Area R3 Uncovered Area θ Relative Angle

Claims (10)

An ink discharge section having a plurality of discharge heads each provided with a plurality of nozzles for discharging ink, each of the plurality of discharge heads being provided so that an arrangement direction thereof can be adjusted;
A moving unit that relatively moves the ink discharge unit and the recording medium;
The arrangement direction of each of the plurality of ejection heads is caused by ejecting ink from the plurality of nozzles in each of the plurality of ejection heads by the ink ejection unit with respect to the recording medium relatively moved by the moving unit. Test image recording control means for recording on the recording medium a test image capable of acquiring color reproducibility information relating to color reproducibility according to
Based on the color reproducibility information acquired from the imaging data of the test image, generates and outputs adjustment information for adjusting the arrangement direction so as to reduce the variation in color reproducibility in the plurality of ejection heads Adjustment information generating means for
An ink jet recording apparatus comprising: The test image recording control unit is configured to identify a landing position in a width direction orthogonal to the moving direction of ink ejected from a plurality of nozzles on a recording medium relatively moved in one moving direction. An image is recorded by the ink ejection unit,
The said adjustment information generation means acquires the said color reproducibility information based on the landing position space | interval about the said width direction of the said landing positions specified from the imaging data of the said test image. The ink jet recording apparatus described.   The inkjet recording apparatus according to claim 2, wherein the adjustment information generation unit acquires the color reproducibility information by specifying variations in the landing position intervals with respect to a plurality of different arrangement directions. .   The adjustment information generating unit may be configured to reduce the landing position interval related to the ejection heads other than the reference ejection head due to the variation in the landing position interval related to the reference ejection head having the largest variation in the landing position interval among the plurality of ejection heads. The inkjet recording apparatus according to claim 3, wherein the adjustment information that approximates the variation of the image is generated. The test image recording control unit records the test image having a predetermined density by the ink ejection unit,
The said adjustment information production | generation means acquires the said color reproducibility information from the density | concentration of the said test image read from the imaging data of the said test image, and the information which shows the said arrangement | positioning direction. Inkjet recording apparatus. The test image recording control unit records a test image of a predetermined density by the ink ejection unit,
The inkjet recording apparatus according to claim 1, wherein the adjustment information generation unit acquires the color reproducibility information from gloss information related to the gloss of the test image and information indicating the arrangement direction.   The inkjet recording apparatus according to claim 1, wherein the plurality of nozzles in the ejection head are two-dimensionally arranged.   The inkjet recording apparatus according to claim 7, wherein the plurality of nozzles in the ejection head constitute a plurality of nozzle rows each including two or more nozzles arranged in a predetermined direction.   The inkjet recording apparatus according to claim 1, further comprising an imaging unit that captures the test image. An ink ejection unit having a plurality of ejection heads each provided with a plurality of nozzles for ejecting ink, each of the plurality of ejection heads being capable of adjusting an arrangement direction; the ink ejection unit and the recording medium; An adjustment information acquisition method for the ejection head arrangement direction in an inkjet recording apparatus comprising:
The arrangement direction of each of the plurality of ejection heads is caused by ejecting ink from the plurality of nozzles in each of the plurality of ejection heads by the ink ejection unit with respect to the recording medium relatively moved by the moving unit. A test image recording step for recording on the recording medium a test image capable of acquiring color reproducibility information relating to color reproducibility according to
Based on the color reproducibility information acquired from the imaging data of the test image, generates and outputs adjustment information for adjusting the arrangement direction so as to reduce the variation in color reproducibility in the plurality of ejection heads Adjustment information generation step,
The adjustment information acquisition method of the ejection head arrangement direction characterized by including.