JP6708074B2 - INKJET RECORDING APPARATUS AND METHOD FOR ACQUISITION OF ADJUSTING HEAD ADJUSTION - Google Patents

Description

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

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

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

JP, 2010-125806, A

However, the ejection direction of the ink from each nozzle is not always uniform due to variations in the characteristics of the nozzles, etc. Therefore, in the above-described 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 of 1) uniform in the ejection head. Further, the characteristic relating to the variation in the landing position interval is usually different for each ejection head. Therefore, there is a problem in that the color misregistration and the difference in color reproducibility occur between the ejection heads in the long ink ejection unit, and the image quality of the recorded image is deteriorated.

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

In order to achieve the above object, the invention of an ink jet recording apparatus according to claim 1 is
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 provided so that the arrangement direction can be adjusted;
A moving unit that relatively moves the ink ejecting unit and the recording medium,
By causing the ink ejecting section to eject ink from the plurality of nozzles in each of the plurality of ejection heads with respect to the recording medium that is relatively moved by the moving section, the arrangement direction of each of the plurality of ejection heads Test image recording control means for recording on the recording medium a test image capable of obtaining color reproducibility information relating to color reproducibility according to
Generates and outputs adjustment information for adjusting the arrangement direction so as to reduce the variation in the color reproducibility among the plurality of ejection heads, based on the color reproducibility information acquired from the imaged data of the test image. Adjustment information generating means,
It is characterized by having.

The invention described in claim 2 is the ink jet recording apparatus according to claim 1,
The test image recording control means is for performing the test for identifying the landing position of the ink ejected from the plurality of nozzles on the recording medium that is relatively moved in one moving direction, in the width direction orthogonal to the moving direction. An image is recorded by the ink ejection unit,
The adjustment information generating unit acquires the color reproducibility information based on a landing position interval in the width direction between the landing positions specified from the imaged data of the test image.

According to a third aspect of the invention, in the inkjet recording apparatus according to the second aspect,
The adjustment information generating means is characterized in that the variation in the landing position interval is specified for each of the plurality of different arrangement directions, and the color reproducibility information is acquired.

According to a fourth aspect of the invention, in the ink jet recording apparatus according to the third aspect,
The adjustment information generating means is configured to adjust the landing position interval of the ejection heads other than the reference ejection head to the landing position interval variation of the reference ejection head having the largest landing position spacing variation among the plurality of ejection heads. It is characterized in that the adjustment information for approximating the variation of is generated.

According to a fifth aspect of the invention, in the inkjet recording apparatus according to the first aspect,
The test image recording control means records the test image of a predetermined density by the ink ejecting unit,
The adjustment information generating means is characterized in that the color reproducibility information is acquired from the density of the test image read from the imaged data of the test image and the information indicating the arrangement direction.

The invention described in claim 6 is the ink jet recording apparatus according to claim 1,
The test image recording control means causes the ink ejecting unit to record a test image having a predetermined density,
The adjustment information generating unit is characterized in that the color reproducibility information is acquired from the gloss information regarding the gloss of the test image and the information indicating the arrangement direction.

The invention described in 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 described in 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 of which includes two or more nozzles arranged in a predetermined direction.

According to a ninth aspect of the invention, in the inkjet recording apparatus according to any one of the first to eighth aspects,
It is characterized by comprising an image pickup means for picking up the test image.

In order to achieve the above-mentioned object, the invention of the adjustment information acquisition method of the ejection head arrangement direction according to claim 10 is
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 a recording medium; A moving section that relatively moves the ink jet recording apparatus, and
By causing the ink ejecting section to eject ink from the plurality of nozzles in each of the plurality of ejection heads with respect to the recording medium that is relatively moved by the moving section, the arrangement direction of each of the plurality of ejection heads A test image recording step of recording on the recording medium a test image capable of obtaining color reproducibility information relating to color reproducibility according to
Generates and outputs adjustment information for adjusting the arrangement direction so as to reduce the variation in the color reproducibility in the plurality of ejection heads, based on the color reproducibility information acquired from the imaging data of the test image. Adjustment information generation step to
It is characterized by including.

According to the present invention, it is possible to suppress the occurrence of color misregistration between the ejection heads.

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. FIG. 3 is a block diagram showing a main functional configuration of an inkjet recording apparatus. FIG. 6 is a diagram illustrating an example of a landing position of ink ejected from a recording head on a recording medium. FIG. 6 is a diagram showing another example of the landing position of the ink ejected from the recording head on the recording medium. FIG. 7 is a diagram illustrating a method of adjusting variations in ink landing position intervals by adjusting relative angles. 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 printhead attachment adjustment processing. FIG. 5 is a diagram illustrating a relationship between an overlapping state of ink and gloss.

Hereinafter, an embodiment of an inkjet recording apparatus and a method for acquiring adjustment information of an ejection head arrangement direction of the present invention will be described with reference to the drawings.

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

The paper feed unit 10 includes a paper feed 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 feed tray 11 to the image recording unit 20. The medium supply unit 12 is provided with a ring-shaped belt whose inside is supported by two rollers, and the rollers are rotated with the recording medium P placed on the belt to rotate the recording medium P from the paper feed tray 11. The image 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 ejecting unit), a fixing unit 25, an imaging unit 26 (imaging unit), and delivery. It has a part 27 and the like.

The transport unit 21 holds the recording medium P placed on the transport surface (outer peripheral surface) of the cylindrical transport drum 211, and the rotary shaft in which the transport drum 211 extends in the width direction perpendicular to the drawing in FIG. The transport drum 211 and the recording medium P on the transport drum 211 are transported in the transport direction (moving direction) by rotating around the (cylindrical axis) and moving around. The transport drum 211 includes a claw portion and an air suction portion (not shown) for holding the recording medium P on the transport surface thereof. The end of the recording medium P is pressed by the claw portion, and the recording medium P is held on the conveyance surface by being sucked up to the conveyance surface by the suction portion. The transport unit 21 has 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 transported by the medium supply unit 12 of the paper feeding unit 10 to the transport unit 21. The delivery unit 22 is provided at a position between the medium supply unit 12 of the paper feed unit 10 and the transport unit 21, and holds one end of the recording medium P transported from the medium supply unit 12 by the swing arm unit 221 and picks it up. 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 transfer drum 222 and the arrangement position of the head unit 24, and the recording medium P conveyed by the conveyance unit 21 is kept within a predetermined temperature range. Heat P. The heating unit 23 has, for example, an infrared heater or the like, and energizes the infrared heater based on a control signal supplied from the control unit 40 (FIG. 3) to heat the infrared heater.

The head unit 24 ejects the recording medium P from the nozzle openings provided on the ink ejection surface facing the conveyance surface of the conveyance drum 211 at an appropriate timing according to the rotation of the conveyance drum 211 holding the recording medium P. An image is recorded by performing a recording operation in which ink is ejected by using the recording medium. The head unit 24 is arranged so that the ink ejection surface and the transport surface are separated by a predetermined distance. In the inkjet recording apparatus 1 of the present embodiment, four head units 24 respectively corresponding to inks of four colors of yellow (Y), magenta (M), cyan (C), and black (K) are provided in the recording medium P conveyance direction. The colors Y, M, C, and K are arranged in order from the upstream side so as to be arranged at predetermined intervals.

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 seen from the side facing the transport surface of the transport 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 recording element communicates with a pressure chamber (channel) that stores ink, a piezoelectric element provided on the wall surface of the pressure chamber, an electrode for applying a voltage to the piezoelectric element to generate an electric field, and the pressure chamber. And a nozzle 243 for ejecting ink in the pressure chamber. In this recording element, when a drive signal for deforming the piezoelectric element is input, the pressure chamber is deformed due to the deformation of the piezoelectric element, the pressure inside 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. In FIG. 2, the position of the ink ejection port of the nozzle 243, which is a component of the recording element, is shown.

As shown in FIG. 2, each recording head 242 has a configuration in which four nozzle rows 2421 each composed of 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 arrangement are combined by being shifted in the width direction by a length that is ¼ of the arrangement interval of the nozzles 243 in each nozzle row 2421, thereby combining four nozzle rows 2421. The positions of the nozzles 243 in the nozzle row 2421 in the width direction are different from each other, and the intervals of 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. Further, 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 in the width direction of the nozzle 243 in the recording head 242 are finely adjusted by adjusting the arrangement direction. be able to. In this embodiment, the arrangement direction of the nozzle rows 2421 represents the arrangement direction of the recording heads 242, and the angle formed by the conveyance direction and the arrangement direction is referred to as a relative angle θ (normally 90 degrees).
In the inkjet recording apparatus 1 of the present embodiment, each nozzle row 2421 is provided with hundreds of nozzles 243, but in FIG. 2, the number of nozzles 243 included in the nozzle row 2421 is omitted to be seven. I am drawing. Further, the array direction of the nozzle rows 2421 in each recording head 242 is not limited to the width direction orthogonal to the transport direction, and may be the direction intersecting the transport direction at an angle other than a right angle.

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

The widthwise arrangement range of the nozzles 243 included in the head unit 24 covers the widthwise width of the image recordable region of the recording medium P conveyed by the conveying unit 21. The head unit 24 is used with a fixed position during image recording, and sequentially ejects ink at predetermined intervals (conveying direction intervals) at different positions in the conveying direction according to the conveyance of the recording medium P. Images are recorded using the single-pass method. In the present embodiment, the interval in the carrying direction is set so that the recording resolution in the carrying direction is 1200 dpi.

In the recording head 242, the ink ejection state is set to the initial setting due to variations in processing when forming the nozzles 243, variations in characteristics of the piezoelectric element, clogging of the nozzles 243, or blockage due to adhesion of foreign matter to the nozzle openings. May result in different nozzles 243. Here, the difference in the ink ejection state means that the ink ejection direction (flying direction of ejected ink droplets), the ink ejection amount (volume of ejected ink droplets), the speed of ejected ink droplets, and the like. Say different. If the ink ejection direction changes from the initial setting, the overlapping state of the ink ejected from the adjacent nozzles changes, which affects the color of the image recorded by the recording head 242. A method of 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, there is used an ink which has a property of undergoing a phase change into a gel or a sol according to temperature and being cured by being irradiated with energy rays such as ultraviolet rays.
In addition, in this embodiment, an 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, and the ink heating unit operates under the control of the control unit 40 to bring the ink to a sol temperature. To heat. The recording head 242 ejects the sol-like ink that is heated. When this sol-like ink is ejected onto the recording medium P, the ink droplets land on the recording medium P and are then naturally cooled, whereby the ink rapidly becomes a gel state and solidifies on the recording medium P.

The fixing unit 25 has an energy ray irradiation unit arranged across the width of the conveyance unit 21, and the recording medium P placed on the conveyance unit 21 is exposed to ultraviolet rays or the like from the energy ray irradiation unit. The ink ejected onto the recording medium P by being irradiated with energy rays is cured and fixed. The energy ray irradiation unit of the fixing unit 25 is arranged so as to face the conveyance 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 conveyance 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, and the conveyance drum 211 causes The image recorded on the conveyed recording medium P is read in a predetermined reading range, and the image pickup data of the image is output.
In the present embodiment, the imaging unit 26 includes a light source that irradiates the recording medium P conveyed by the conveying drum 211 with light, and an image sensor 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 rows of image pickup elements including image pickup elements arranged in the width direction, and R (red), G (green) of incident light, and A signal corresponding to the intensity of the B (blue) wavelength component is output. The image pickup devices 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 including a photodiode as a photoelectric conversion element. It is possible to use a color filter in which a color filter for transmitting the light of the wavelength component is arranged. 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 at 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 becomes 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).
The configuration of the imaging unit 26 is not limited to this, and an area sensor may be used instead of the line sensor 262, for example.

The delivery unit 27 has a belt loop 272 having a ring-shaped belt whose inside is supported 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 onto the belt loop 272 from the transfer unit 21 by the transfer drum 271 is transferred by the belt loop 272 and delivered to the paper output unit 30.

The paper discharge unit 30 has a plate-shaped paper discharge tray 31 on which the recording medium P sent 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 including a head control unit 241, a head driving unit 2422, and a head position adjusting mechanism 245, a fixing unit 25, an imaging unit including 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 drive unit 2422 provided in the recording head 242 at appropriate timing according to the control signal from the control unit 40.
The head drive section 2422 supplies a drive signal for deforming the piezoelectric element to the recording element of the recording head 242 in accordance with a control signal or image data input from the head control section 241, and from the opening of each nozzle 243. Eject ink.

The head position adjusting 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 according to the input of the control signal from the control unit 40. It should be noted that the head position adjusting mechanism 245 may be one that is electrically driven and operates according to the set value input by the user's input operation to the operation display unit 52, or the recording head 242 may be operated by the user. The relative angle θ may be directly and manually adjusted.

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. Further, the image pickup 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 image pickup to obtain image pickup data indicating the brightness 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 out various control programs and setting data stored in the ROM 43, stores them in the RAM 42, and executes the programs to perform various arithmetic processes. Further, the CPU 41 centrally controls the overall operation of the inkjet recording apparatus 1.

The RAM 42 provides the CPU 41 with a working memory space and stores temporary data. The RAM 42 may include a non-volatile memory.

The ROM 43 stores various control programs executed by the CPU 41, setting data, and the like. Instead 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, Image pickup data and the like generated by the image pickup unit 26 are 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 together.

The transport driving 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 or an organic EL display, an operation key, and an input device such as a touch panel arranged so as to be superimposed on the screen of the display device. The operation display unit 52 displays various kinds of information on the display device, converts the user's input operation on the input device into an operation signal, and outputs the operation signal to the control unit 40.

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

Next, a method of adjusting the arrangement direction of the recording head 242 in the inkjet recording apparatus 1 of this embodiment will be described.
In the inkjet recording apparatus 1 of the present embodiment, an image corresponding to image data is recorded using the long head unit 24 in which four recording heads 242 are connected in the longitudinal direction. Therefore, it is desirable that the colors of the images recorded by the recording heads 242 according to the same image data be the same. Here, the color of the image to be recorded is defined by three elements of hue, saturation and lightness. Further, in the following, the degree of color of the recorded image corresponding to the predetermined image data by the recording head 242 will be referred to as color reproducibility.
However, as described in detail below, the color reproducibility of the print head 242 is often due to variations in the arrangement intervals of the nozzles 243 in the print head 242 and variations in the ink ejection direction from the nozzles 243. Since the recording heads 242 are different from each other, unless color reproducibility is adjusted, color unevenness occurs at positions corresponding to the joints of the recording heads 242 in a recorded image, which leads to deterioration in image quality. The color reproducibility of each recording head 242 can be adjusted by adjusting the arrangement direction of the recording head 242 (that is, adjusting the relative angle θ) to change the ink landing position from the nozzle 243. In the present 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.

In the following, first, the adjustment of the color reproducibility by changing the relative angle θ of the recording head 242 will be described.
FIG. 4 is a diagram showing an example of the landing positions 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 242A of 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 (image in which all pixels have the maximum gradation) is recorded by the recording head 242A. The landing range (wetting and spreading range) on the medium P is indicated by a circle. The center of the circle indicates the ink landing position. In reality, the ejected ink amount is often adjusted so that the landing range of the ink droplet 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 impact areas are drawn so that they are almost in contact with each other. Further, hereinafter, the four nozzle rows 2421 in the recording head 242A are set 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. Further, in the recording head 242A, when the relative angle θ is 90 degrees, the intervals Δ between the nozzles 243 in the width direction are uniform, and there is almost no variation in the ink ejection direction from the nozzles 243. Therefore, the landing positions of the ink ejected from the nozzles 243 are substantially equal in the width direction, and the overlapping state of the ink ejected from the adjacent nozzles 243 and landing on the recording medium P is substantially uniform. Is becoming That is, the recording head 242A is a proper recording head capable of landing the ink at the position almost as originally set.

FIG. 5 is a diagram showing an example of a landing position on the recording medium P of ink ejected from a 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 in a state where the nozzle rows 2421a are displaced to the right in FIG. 5 from the originally set positions and the nozzle rows 2421b are displaced to the left. Therefore, the variation in the distance Δ between the nozzles 243 in the width direction is larger than the variation in the distance Δ between the recording heads 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 due to this, 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 proportion of the portion of the ink droplet landing area that overlaps with the landing area of another ink droplet) ), and the coverage between the ink ejected from the nozzle row 2421a and the ink ejected from the nozzle row 2421d is larger than the appropriate coverage. Further, the coverage between the ink ejected from the nozzle row 2421a and the ink ejected from the nozzle row 2421b is smaller than the proper coverage (in FIG. 5, the landing ranges do not overlap with each other). Has become). Here, the appropriate coverage is, for example, the coverage between the inks ejected by the appropriate recording head 242A in FIG.

Therefore, in the solid image recorded by the recording head 242B in FIG. 5, the proportion occupied by the overlapping region R2 in which the ink landing ranges overlap each other in the image and the non-covering region R3 that is 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 of FIG. 5, the proportion of the single-layer region R1 in which the ink landing ranges do not overlap and the ink is a single layer is relatively smaller than that in the solid image of FIG. ..

Here, since the thickness of the ink layer in the overlapping region R2 is larger than that in the single layer region R1, the color is darker than in the single layer region R1. In the non-covered area R3, the color of the recording medium P appears as it is. The color represented 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-covering region R3 are mixed according to the ratio of each region, so the single-layer region R1 If the ratios of the overlapping region R2 and the non-covering region R3 are different, the 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 of FIG.
Further, the color difference between the images recorded by the recording heads 242A and 242B can occur not only in the solid image but also in the intermediate gradation. That is, the recording head 242A and the recording head 242B express at each of the minimum to maximum recordable gradations and the gradation at which the ink ejected from the adjacent nozzles 243 and landed at least partially overlap each other. The colors displayed will be different from each other.

Even if the nozzles 243 of the recording head 242 are arranged at equal intervals as shown in FIG. 4, if the variation in the ink ejection direction from each nozzle 243 is large, the ink landing position deviates from the proper position. Variation occurs in the overlapping state of the landed inks. Therefore, as in FIG. 5, the ratio of the overlapping region R2 and the non-covering region R3 in the recorded image becomes high, and the color reproducibility differs from that of the proper recording head 242A.

The difference in the color of the print image between the print heads 242 due to the variation in the distance Δ between the nozzles 243 and the variation in the ink ejection direction depends on the distance between the nozzles 243 and the size of the ink droplets. The color difference ΔE* in the *b* coordinate system can be as large as 3. This is a level at which the difference in color can be clearly seen in the adjacent comparison. Therefore, when the recording units 242 having different color reproducibility as described above are included in the head unit 24, a non-negligible color shift occurs between the recording heads 242 in the image recorded by the head unit 24, and the image quality of the recorded image. Cause decline.

If the ink landing positions on all the recording heads 242 can be set to the proper 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 deviation. Further, variations in the ink ejection direction from the nozzles 243 are also generated subsequently due to foreign matters adhering to the nozzle openings in addition to the initial failure of the nozzles 243, so that the variations in the ink ejection direction are completely prevented. Is difficult. For these reasons, in the recording head 242, it is basically inevitable that the ink landing position interval in the width direction varies to some extent.
Further, since the variation in the landing position interval differs for each recording head 242, even if the relative land 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, the distance between the recording heads will be the same. A difference remains in the variation of the ink landing position interval, and thus a difference in color reproducibility between recording heads. That is, since the recording heads 242 differ from each other in the error in the arrangement position of the nozzle row 2421 and the variation in the ink ejection direction, the range of adjustable color reproducibility is different from each other, and therefore the color reproducibility of each head is the highest. Even if the relative angle θ is adjusted so that it is difficult to eliminate the variation in the color reproducibility between the recording heads.

Therefore, in this embodiment, the relative angle θ is set so as to increase the variation in the ink landing position intervals of the other recording heads 242 in accordance with the recording head 242 (reference ejection head) in which the variation in the ink landing position intervals is the largest. The color reproducibility of each recording head 242 is adjusted by adjusting. In this embodiment, it is assumed that among the four recording heads 242 of the head unit 24, the variation in the ink landing position interval in the recording head 242B shown in FIG. 5 is the largest.

FIG. 6 is a diagram illustrating a method of adjusting variations in the landing position intervals of ink 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. As a result of the rotation of the recording head 242A thus increasing the variation in the distance Δ between the nozzles 243 in the width direction, the variation in the landing position spacing of the ink ejected from each nozzle also increases, and the ink is ejected from the adjacent nozzles 243. Thus, the overlapping state of the inks landing on the recording medium P is not uniform. Specifically, the coverage between the ejected inks 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 normal 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. Has become). Further, in FIG. 6, the relative angle θa is adjusted so that the ratio of the single-layer region R1, the overlapping region R2, and the non-covered region R3 in the recorded image is substantially equal to the ratio in the recording head 242B shown in FIG. There is. As a result, the color reproducibility becomes substantially the same 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 relative angle θ is adjusted so that the variation in the ink landing position interval is equal to that of the recording head 242B. Variations in reproducibility can be suppressed.

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

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 onto the recording medium P conveyed in the conveying direction. In the test image 70, a plurality of lines 71 recorded by every third nozzle 243 are arranged in the width direction to form a line group 71G. Further, four line groups 71G are recorded in the transport direction, and the nozzles 243 for recording the line 71 are displaced by one between adjacent line groups 71G.

In such a test image 70, the position of each line 71 in the width direction 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 image pickup data of the test image 70 by the image pickup unit 26, it is possible to obtain the variation in the landing position interval of the ink from each nozzle 243.

In the method for specifying the adjustment amount of the relative angle θ in the present embodiment, first, the widthwise distance d between the adjacent lines 71 in each line group 71G is acquired, and then the four recording heads 242 are respectively handled. The variation σ of the distance d is calculated. Then, the recording head 242 having the largest variation σ is identified. Hereinafter, this recording head 242 will be referred to as a reference recording head, and the variation σ in the reference recording head will be referred to as variation σmax.
Here, the variation σ is a value having a correlation with the overlapping state of the inks. That is, the greater the variation σ, the greater the variation in the landing position interval of the ink in the width direction, and the greater the average value of the coverage rates of the inks. In addition, as described above, the overlapping state of ink has a correlation with 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 (corresponding 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 corresponding to the displacement amount of the nozzle is calculated. Later positions are calculated. Then, the variation σ of the interval d between the respective lines 71 after displacement is calculated. Further, this variation σ is calculated for each of the plurality of relative angles θ. The variation σ may be calculated for each value of the adjustable relative angle θ, or the variation σ may be calculated for several relative angles θ and the variation between the relative angle θ and the variation σ may be calculated. The relational expression (approximate expression) may be obtained.

Then, 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 variations in the distance d between the lines 71 of the respective print heads 242 are equal to each other at σmax, the variations in the overlapping state of the ink landing ranges are substantially the same, and as a result, the single-layer region R1, the overlapping region R2, and The ratios of the non-covered regions R3 are 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 angle of each recording head 242 by the adjustment amount determined as described above. That is, in each of the minimum gradation to the maximum gradation that can be recorded by each recording head 242, the colors to be expressed are adjusted to be substantially the same.
When the position of each nozzle 243 in the transport direction deviates from the initial setting by adjusting the relative angle θ of the recording head 242, the ejection timing of the ink 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 printhead attachment adjustment process performed in the inkjet recording apparatus 1 will be described.

FIG. 8 is a flow chart showing a control procedure by the control unit 40 of the print head attachment adjustment processing.
This recording head attachment adjustment process is performed by the user with respect to the operation display unit 52 when the inkjet recording apparatus 1 is shipped, when the head unit 24 is replaced, or when an image quality defect due to color misregistration in a recorded image occurs. It is executed when a predetermined input operation for 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 causes the transport driving unit 51 to output a drive signal to the transport drum motor of the transport drum 211 to start the rotation operation of the transport drum 211. Next, a control signal is output to the transport driving unit 51 to operate the paper feeding unit 10, the delivery unit 22, and the transport unit 21 to place the recording medium P on the transport surface of the transport drum 211. Next, the control unit 40 controls the image data and the control signal of the test image stored in the storage unit 44 from the head control unit 241 to each recording head 242 (head driving unit 2422) at an appropriate timing according to the rotation of the transport drum 211. The ink is ejected from the nozzles 243 of each recording head 242 onto the recording medium P to record the test image 70 on the recording medium P. Further, the control unit 40 causes the fixing unit 25 to irradiate the ink with a predetermined energy ray at the timing when the recording medium P to which the ink has been applied moves to the position of the fixing unit 25, thereby fixing the ink to the recording medium P. Let

The control unit 40 causes the image capturing 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 image pickup control unit 261 at the timing when the test image 70 on the recording medium P moves to the image pickup position of the image pickup unit 26 according to the rotation of the transport drum 211, and the image pickup unit 26 outputs the control signal. 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 obtains the variation σ of the ink landing position interval of each recording head 242 based on the imaged data of the test image 70 (step S103). That is, the control unit 40 identifies the interval d of all the lines 71 in each line group 71G from the imaged data of the test image 70, and calculates the variation σ of the interval d for each print head 242 based on the identification result. ..

The control unit 40 identifies the reference recording head having the largest 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 becomes σmax for each recording head 242 other than the reference recording head (step S105: adjustment information generating step). That is, the control unit 40 calculates the variation σ corresponding to a plurality of different relative angles θ for each recording head 242, or acquires the relational expression between the relative angle θ and the variation σ, and the variation σ is equal to σmax. When the relative angle θ becomes (or becomes the closest value), the adjustment amount of the relative angle θ is determined, and the 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 adjusting mechanism 245, and causes the head position adjusting mechanism 245 to perform 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 printhead attachment adjustment process.

When the head position adjusting mechanism 245 is manually operated, the control unit 40 outputs the identification result of the adjustment amount by a predetermined method in step S105 and mounts the recording head without performing the process of step S106. The adjustment process ends. In this case, the user may read the output information and manually adjust the relative angle θ after the print head attachment adjustment process is completed. Further, as a method of outputting the adjustment amount in step S105, for example, the specification result of the adjustment amount is output to the operation display unit 52 in a predetermined mode, or the adjustment amount of the relative angle θ is included in the margin of the recording medium P or the like. There is a method of recording information relating to the adjustment of the relative angle θ.

(Modification 1)
Next, a first modification of the above embodiment will be described. In this modification, the content of the test image used to specify the adjustment amount of the relative angle θ and the method of specifying the adjustment amount are different from those of the above embodiment. 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 heads 242 adjusted to the respective relative angles θ each generate a gradation image of a predetermined density on the recording medium P as a test image. Recorded in. Then, the relationship (color reproducibility information) between the density of each test image read from the captured image of the test image and the relative angle θ of the print head 242 used to print the test image is shown for each print head 242. To be acquired. After that, 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 is also possible to acquire a color instead of the density from the image data of the test image, and acquire the relationship (color reproducibility information) between the relative angle θ and the color of the test image.

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

(Modification 2)
Next, a modified example 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 heads 242 adjusted to the respective relative angles θ each generate a gradation image of a predetermined density on the recording medium P as a test image. Recorded in. Then, the relationship between the information about the gloss of each test image (gloss information) read from the captured image of the test image and the relative angle θ of the recording head 242 used for recording the test image (color reproducibility information). Are acquired for each recording head 242. After that, the adjustment amount of the relative angle θ of each recording head 242 is determined so that the glossiness of the test image recorded by each recording head 242 of the head unit 24 becomes equal.

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

As shown on the left side of FIG. 9, when the dispersion of the landing positions of the inks is large and the coverage of the inks is large, the ink droplets are separated on the recording medium P as shown in the lower sectional view. The state of the ink drops easily, and the height of each ink drop on the recording medium P tends to increase. For this reason, the surface of the ink that is solidified and fixed on the recording medium P has a large proportion of the portion that is not parallel to the surface of the recording medium P, so that 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 ink are uniform and the coverage ratio of the inks is small, the ink droplets are spread over a wide range on the recording medium P, as shown in the lower sectional view. And the height of the ink on the recording medium P is likely to be small. For this reason, the surface of the ink that is solidified and fixed on the recording medium P has a large proportion of a portion parallel or nearly parallel to the surface of the recording medium P, so that the light incident on the ink is specularly reflected on the ink surface. The ratio of being applied is increased and the gloss is increased.
As described above, since the gloss of the recording medium P reflects the distribution of the 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 test images recorded by the recording heads 242 have the same gloss.

The density of the test image of this modification is such that the inks having appropriate landing position intervals partially overlap with each other, and when the variations of the landing position intervals become large, inks that do not overlap each other are produced.
In addition, as a method of acquiring the gloss information regarding the gloss of the present modified example, for example, light is incident from a light source at a predetermined incident angle (for example, 60 degrees), and the reflected light amount in the direction perpendicular to the recording medium P is determined. Any measuring method can be used.

As described above, the inkjet recording apparatus 1 of the present embodiment has the plurality of recording heads 242 each provided with the plurality of nozzles 243 that eject ink, and each of the plurality of recording heads 242 adjusts the arrangement direction. The recording medium P includes a head unit 24 that is provided so that the head unit 24 and the recording medium P move relative to each other, and a control unit 40. The control unit 40 moves the recording medium P that is relatively moved by the conveyance unit 21. On the other hand, by causing the head unit 24 to eject ink from the plurality of nozzles 243 in each of the plurality of recording heads 242, color reproducibility information relating to color reproducibility according to the arrangement direction of each of the plurality of recording heads 242. Is recorded on the recording medium P (test image recording control means), and the color reproducibility of the plurality of recording heads 242 is based on the color reproducibility information acquired from the imaged data of the test image 70. Generates and outputs an adjustment amount (adjustment information) of the relative angle θ for adjusting the arrangement direction so as to reduce the dispersion of (adjustment information generation means).
With such a configuration, it is possible to suppress variations in color reproducibility between the print heads in the head unit 24 and color shifts between the print heads due to the variations in the color reproducibility. The adjustment amount of the relative angle θ of can be acquired. Therefore, by adjusting the arrangement direction of the recording heads 242 based on the adjustment amount, it is possible to suppress the occurrence of color misregistration between the recording heads. 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 of the color reproducibility due to the variation of the arrangement interval of the nozzles 243 but also the nozzles 243. It is also possible to appropriately suppress variations in color reproducibility due to deviation of the ink ejection direction from the ink.

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

Further, the control unit 40 specifies the variation σ of the landing position intervals for each of a plurality of different relative angles θ and acquires color reproducibility information (adjustment information generation means). The variation σ of the 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. Therefore, according to the above configuration, For the recording head 242, the relationship between the arrangement direction of the recording head 242 and the color reproducibility can be acquired. This makes it 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 variation σ max of the reference recording head having the largest landing position spacing variation σ of the plurality of recording heads 242 to the landing position spacing of the recording heads 242 other than the reference ejection head. An adjustment amount of the relative angle θ that brings the variation σ closer is determined (adjustment information generating means). The minimum value of the variation σ of the landing position intervals that can be adjusted in each recording head 242 is different for each recording head 242. By adjusting the variation σ according to the recording head 242 having the largest variation σ as described above, The variation σ in the landing position intervals of the plurality of recording heads 242 in the head unit 24, and thus the color reproducibility, can be more surely matched or brought close to each other.

Further, in the inkjet recording apparatus 1 according to the modified example 1, 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 means), and the image is read from the image data of the test image. Color reproducibility information is acquired from the density of the test image and the information indicating the arrangement direction of the recording head 242 (adjustment information generating means). With such a configuration, since 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, an accurate error-free simulation can be performed. It is possible to obtain a large adjustment amount.

Further, in the inkjet recording apparatus 1 according to the modified example 2, the control unit 40 causes the head unit 24 to record the test image of a predetermined density (test image recording control means), and the gloss information regarding 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). With such a configuration, the color reproducibility information can be acquired by a simple method of measuring the gloss of the test image.

Further, the plurality of nozzles 243 in the recording head 242 are two-dimensionally arranged. In such a configuration, the arrangement intervals of the nozzles 243 in the width direction tend to be non-uniform according to the arrangement direction of the recording head 242. However, according to the above-described embodiment, the arrangement intervals of the nozzles 243 are not uniform. It is possible to effectively suppress variations in color reproducibility among the recording heads.

In addition, the plurality of nozzles 243 in the recording head 242 form a plurality of nozzle rows each including 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 corresponding to the arrangement direction of the recording head 242, and thus the change in the ink landing position interval, become regular, so that the arrangement direction and the color reproducibility are The relationship can be easily specified, and the color reproducibility information can be acquired more easily.

The inkjet recording device 1 also includes an image capturing unit 26 that captures the test image 70. As a result, the inkjet recording apparatus 1 can acquire the imaging data of the test image 70 and adjust the arrangement direction of the recording head 242.

Further, according to the method of acquiring the adjustment information of the ejection head arrangement direction of the present embodiment, the ink is ejected from the plurality of nozzles 243 in each of the plurality of recording heads 242 by the head unit 24 with respect to the recording medium P relatively moved by the transport unit 21. By ejecting the test image 70, 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, a test image Based on the color reproducibility information acquired from the image pickup data of 70, the adjustment amount (adjustment information) of the relative angle θ for adjusting the arrangement direction so as to reduce the variation in the color reproducibility in the plurality of recording heads 242. An adjustment information generating step of generating and outputting. According to such a method, it is possible to obtain the adjustment amount of the relative angle θ of the recording heads 242 that can appropriately suppress the occurrence of color misregistration between the recording heads in the head unit 24.

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, an example in which the adjustment amount itself (correction angle) of the relative angle θ is determined as the adjustment information of the arrangement direction of the recording head 242 has been described, 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 according to the rotation amount of a predetermined adjustment screw, information indicating the rotation amount of the adjustment screw is generated as adjustment information. Is also good.

Further, in the above-described embodiment and each modified example, an example in which the variation σ of the interval Δ of the line 71 in the test image 70, the density of the test image, and the information on the gloss are used as the color reproducibility information has been described. Not limited to this, 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.

Further, in the above-described 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.

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

Further, in the above-described embodiment, the example in which the inkjet recording device 1 includes the imaging unit 26 has been described, but instead of this, the test image 70 is captured by the imaging device separately provided outside the inkjet recording device 1. Then, the imaging data may be generated.

Further, in each of the above-described embodiments, an example in which the recording medium P is conveyed by the conveying drum 211 has been described, but the present invention is not limited to this, and is supported by, for example, two rollers and moves according to the rotation of the rollers. The recording medium P may be conveyed by a conveying belt that operates.

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

Although some 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 the equivalent scope thereof. ..

DESCRIPTION OF SYMBOLS 1 Inkjet recording apparatus 2 External apparatus 10 Paper feed section 11 Paper feed tray 12 Medium supply section 20 Image recording section 21 Conveying section 211 Conveying drum 22 Transfer unit 23 Heating section 24 Head unit 241 Head control section 242, 242A, 242B Recording head 2421 , 2421a to 2421d Nozzle row 2422 Head drive unit 243 Nozzle 244 Mounting member 245 Head position adjusting mechanism 25 Fixing unit 26 Imaging unit 261 Imaging control unit 262 Line sensor 27 Delivery unit 30 Paper ejection unit 31 Paper ejection 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 region R2 overlapping region R3 uncovered region θ relative angle

Claims (10)

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 provided so that the arrangement direction can be adjusted;
A moving unit that relatively moves the ink ejecting unit and the recording medium,
By causing the ink ejecting section to eject ink from the plurality of nozzles in each of the plurality of ejection heads with respect to the recording medium that is relatively moved by the moving section, the arrangement direction of each of the plurality of ejection heads Test image recording control means for recording on the recording medium a test image capable of obtaining color reproducibility information relating to color reproducibility according to
Generates and outputs adjustment information for adjusting the arrangement direction so as to reduce the variation in the color reproducibility among the plurality of ejection heads, based on the color reproducibility information acquired from the imaged data of the test image. Adjustment information generating means,
An inkjet recording apparatus comprising: The test image recording control means is for performing the test for identifying the landing position of the ink ejected from the plurality of nozzles on the recording medium that is relatively moved in one moving direction, in the width direction orthogonal to the moving direction. An image is recorded by the ink ejection unit,
The adjustment information generating unit acquires the color reproducibility information based on a landing position interval in the width direction between the landing positions specified from the imaged data of the test image. The inkjet recording device described. The inkjet recording apparatus according to claim 2, wherein the adjustment information generation unit specifies the variation in the landing position interval for each of the plurality of different arrangement directions and acquires the color reproducibility information. .. The adjustment information generating means may adjust the landing position intervals of the ejection heads other than the reference ejection head to the landing position intervals of the reference ejection head having the largest landing position interval variation among the plurality of ejection heads. The ink jet recording apparatus according to claim 3, wherein the adjustment information that approximates the variation of the above is generated. The test image recording control means records the test image of a predetermined density by the ink ejecting unit,
The adjustment information generation unit acquires the color reproducibility information from the density of the test image read from the imaged data of the test image and the information indicating the arrangement direction. Inkjet recording device. The test image recording control means causes the ink ejecting unit to record a test image having a predetermined density,
The inkjet recording apparatus according to claim 1, wherein the adjustment information generation unit acquires the color reproducibility information from gloss information regarding 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 ink jet recording apparatus according to claim 7, wherein the plurality of nozzles in the ejection head form 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 a recording medium. A moving section that relatively moves the ink jet recording apparatus, and
By causing the ink ejecting section to eject ink from the plurality of nozzles in each of the plurality of ejection heads with respect to the recording medium that is relatively moved by the moving section, the arrangement direction of each of the plurality of ejection heads A test image recording step of recording a test image on the recording medium capable of obtaining color reproducibility information relating to color reproducibility according to
Generates and outputs adjustment information for adjusting the arrangement direction so as to reduce the variation in the color reproducibility among the plurality of ejection heads, based on the color reproducibility information acquired from the imaged data of the test image. Adjustment information generation step,
An adjustment information acquisition method for the ejection head arrangement direction, comprising: