JP2014136319A - Method for detecting position displacement of recording head, and image recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a relative position of a recording dot between adjacent head modules with high accuracy even when using a scanner with low resolution.SOLUTION: A plurality of test patterns each of which has a different shift quantity are recorded while changing the shift quantity of a recording position in a second direction of a first head module and a second head module that are adjacent to each other. From read data of the test patterns, a density of an area recorded by a recording element of an overlapping area between the first head module and the second head module is acquired. From the shift quantity and the density, an initial amount of displacement of the recording position in the second direction of the first head module and the second head module is calculated.

Description

  The present invention relates to a recording head positional deviation detection method and an image recording apparatus, and more particularly to a technique for detecting positional deviation between head modules of a recording head composed of a plurality of head modules.

Two-dimensional images are formed by ejecting ink from the nozzles of a full-size head formed by arranging multiple head modules in the X direction to form landing dots (recording dots) on the paper transported in the Y direction. An ink jet recording apparatus is known. In such an ink jet recording apparatus, the positional displacement of each head module in the Y direction, the positional displacement in the Z direction (ejection direction), the displacement of the head mounting angle θ _x (angle around the X axis), each head When variations in the ejection speed of ink from the modules, variations in the ejection timing of each head module, and the like occur, a deviation occurs in the position of the landing dot in the Y direction between the head modules. If the Y-direction positions of the landing dots between the head modules are relatively shifted, streaks and unevenness occur at the connecting portions between adjacent head modules, which causes a problem in image quality.

  Therefore, it is necessary to adjust the Y-direction relative position deviation of the landing dots between the adjacent head modules to be equal to or less than the allowable value. For this reason, it is necessary to detect the Y-direction relative position deviation of the landing dots of the adjacent head module with high accuracy. There is. If the relative positional deviation of the landing dots can be detected, the positional deviation can be adjusted or corrected by physical position adjustment, ejection timing correction, or the like.

  In order to detect the relative positional deviation of landing dots between adjacent head modules, a method of drawing a test chart for detecting positional deviation with each head module, reading the image with a scanner, and calculating the positional deviation is considered. It is done.

  For example, in Patent Document 1, the amount of printing misalignment between the unit recording heads (head modules) and between the recording heads in the paper conveyance direction is detected by reading an image for alignment adjustment by reading means, and the amount of printing misalignment. Describes a technique for controlling the ink ejection timing so as to be small.

  Japanese Patent Laid-Open No. 2004-228561 outputs a predetermined test pattern in a recording head in which two or more sub heads (head modules) are connected, calculates an amount of step between the sub heads using an external reading device, and drives timing. Techniques for adjusting are described.

Japanese Patent Laid-Open No. 2004-268452 JP 2011-168023 A

  As the alignment accuracy in the Y direction between adjacent head modules, for example, if the recording resolution is 1200 dpi, an accuracy of about 10 μm or less is required. On the other hand, when the built-in scanner such as the cited document 1 is used, the reading resolution in the Y direction is generally as low as about 100 dpi (250 μm), which is insufficient for the adjustment accuracy of 10 μm or less. As a result, there is a problem in that the relative positional deviation of the landing dots in the Y direction between the adjacent head modules cannot be accurately corrected, and the connecting portion becomes uneven.

  On the other hand, there is a method of reading with high resolution using an external scanner in order to improve the detection accuracy of the position in the Y direction, as in Cited Document 2. However, in this case, a predetermined image such as a test chart is drawn, and the paper is set on an external scanner and read, and care is required for manual and time-consuming work and handling of the paper. There is a problem that careful work is required.

  The present invention has been made in view of such circumstances, and even when a low-resolution scanner is used, detection of a positional deviation of a recording head that accurately detects the relative position of recording dots between adjacent head modules. It is an object to provide a method and an image recording apparatus.

  In order to achieve the above object, one aspect of a recording head positional deviation detection method is a recording head configured by connecting a plurality of head modules each having a plurality of recording elements arranged in a first direction. A recording head having a complementary region in which projection recording elements of adjacent head modules are nested in a projection recording element array in which a plurality of recording elements are projected so as to be arranged in the first direction; Control for performing recording on the recording medium by the recording element while relatively moving the recording head and the recording medium while moving the recording medium relative to the second direction intersecting the first direction. And a first head module and a second head that are adjacent to each other among a plurality of head modules. And a test pattern recording step of recording a test pattern on a recording medium by the first head module and the second head module. A test pattern recording step for recording a plurality of test patterns with different recording position shift conditions under the condition that a part of recording dots recorded adjacent to each other in the first direction overlap, and a recorded test A read data acquisition step of acquiring pattern read data; and a data generation step of generating complementary region data of a portion recorded by the recording elements of the complementary regions of the first head module and the second head module from the read data; The first head module and the second head module are calculated from the shift amount and the complementary area data. And a calculation step of calculating an initial shift amount of the recording position in the second direction between Lumpur.

  According to this aspect, the test pattern is recorded on the recording medium while changing the shift amount of the recording position in the second direction of the first head module and the second head module adjacent to each other. The read data is acquired, the complementary area data of the portion recorded by the recording element of the complementary area of the first head module and the second head module is acquired from the read data, and the first is obtained from the shift amount and the complementary area data. Since the initial shift amount of the recording position in the second direction between the head module and the second head module is calculated, even when a low resolution scanner is used, recording between adjacent head modules is performed. The relative position of the dots can be detected with high accuracy.

  The data generation step includes a complementary area data of a portion recorded by a recording element in a complementary area between the first head module and the second head module, and a complementary area other than the complementary area of the first head module or the second head module. It is preferable to obtain a difference from the non-complementary region data of the portion recorded by the recording element of the region, and to calculate an initial deviation amount from the shift amount and the difference. By using the difference, the density variation of the test pattern image can be canceled, and the initial shift amount can be calculated appropriately.

  The test pattern is preferably a line pattern in the first direction. By using such a test pattern, the initial deviation amount can be calculated appropriately.

  The data generation step preferably generates density data. By using the density data, the initial deviation amount can be calculated appropriately.

  In the changing step, it is preferable to change the recording position shift amount in the second direction by making the recording timing of the recording element of the first head module different from the recording timing of the recording element of the second head module. Thereby, a plurality of test patterns having different recording position shift amounts can be recorded appropriately.

  In the head module, it is preferable that the recording elements are two-dimensionally arranged. This aspect can be applied to detection of a positional deviation of a recording head provided with such a head module.

  In the recording head, the existence ratio of the recording elements of the first head module gradually decreases from the first head module toward the second head module in the complementary region, and the recording elements of the second head module The abundance ratio may increase gradually. This aspect is suitable for detecting a positional deviation of a recording head including such a head module.

  The recording head may be an inkjet head, and the recording element may be a nozzle that ejects ink. Thus, this aspect is suitable for correcting the positional deviation of an inkjet head having a nozzle for ejecting ink.

  In order to achieve the above object, one aspect of the image recording apparatus is a recording head configured by connecting a plurality of head modules each having a plurality of recording elements arranged in a first direction, In a projection recording element array in which recording elements are projected so as to be arranged in the first direction, a recording head having a complementary region in which projection recording elements of adjacent head modules are nested, a recording head, and a recording medium Moving means for relatively moving in a second direction intersecting the first direction, and control means for performing recording on the recording medium by the recording element while relatively moving the recording head and the recording medium. And a correction unit that corrects the positional deviation of the recording head based on the initial deviation amount calculated by the positional deviation detection method of the recording head.

  According to this aspect, since the positional deviation of the recording head can be corrected based on the initial deviation amount calculated by the recording head positional deviation detection method, streaks and unevenness occur between adjacent head modules. Without recording, a high-quality image can be recorded.

  The correcting means is preferably a changing means. Thereby, it is possible to appropriately correct the positional deviation of the recording head.

  It is preferable to include reading means for reading the recorded test pattern and generating read data. Thereby, the read data of the recorded test pattern can be automatically acquired, and the complicated work by the operator is unnecessary.

  According to the present invention, the relative position of the recording dots between adjacent head modules can be detected with high accuracy.

Schematic diagram showing an inkjet recording apparatus Plan view showing an example of the structure of a line head Partial enlarged view of FIG. Plan view showing nozzle arrangement of head module Sectional drawing which shows the three-dimensional structure of a droplet discharge element Adjacent head module System configuration diagram of inkjet recording apparatus Diagram showing test pattern The figure which shows the density | concentration D of a complementary recording area and a normal recording area Diagram showing changes in concentration when Δy is changed Flowchart illustrating correction processing for droplet ejection position deviation between head modules Flow chart showing test pattern recording process Diagram showing test pattern The figure for demonstrating the process which calculates the value of (DELTA) t used as (DELTA) D = 0. Diagram showing test pattern The block diagram which shows the whole structure of another inkjet recording device Main block diagram showing the system configuration of the inkjet recording apparatus

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

<Outline of inkjet recording apparatus>
FIG. 1 is a schematic diagram illustrating an ink jet recording apparatus according to the present embodiment, in which FIG. 1A is a side view and FIG. 1B is a plan view. The ink jet recording apparatus 200 has a recording surface of a sheet 1 (an example of a recording medium) that is conveyed in a sub-scanning direction (Y direction, corresponding to the second direction) by a conveyance unit (an example of a moving unit, reference numeral 260 in FIG. 7). A printer (an example of an image recording apparatus) that forms an image by ejecting ink from a nozzle surface 210A of a line head 210 (an example of a recording head). A scanner 220 (an example of a reading unit) is provided on the downstream side of the line head 210 in the sub-scanning direction, and is configured to be able to read an image formed on the recording surface of the paper 1.

  FIG. 2 is a plan view showing a structural example of the line head 210, and is a view of the head 210 as seen from the nozzle surface 210A side. FIG. 3 is a partially enlarged view of FIG.

  As shown in FIG. 2, the head 210 connects n head modules 210-i (i = 1, 2, 3,..., N) along the main scanning direction (X direction, corresponding to the first direction). A plurality of nozzles (not shown in FIG. 2) are provided over a length corresponding to the entire width of the paper 1.

  Each head module 210-i is supported by a head module support member 210B from both sides of the head 210 in the short direction. Further, both end portions of the head 210 in the longitudinal direction are supported by a head support member 210D.

  As shown in FIG. 3, each head module 210-i (n-th head module 210-n) has a structure in which a plurality of nozzles are arranged in a matrix (two-dimensional). An oblique solid line denoted by reference numeral 212 in FIG. 3 represents a nozzle row in which a plurality of nozzles are arranged in a row.

  FIG. 4 is a plan view showing the nozzle arrangement of the head module 210-i. As shown in the figure, the head module 210-i has a number of nozzles 216 arranged in a matrix along a column direction W that forms an angle α with respect to the Y direction and a row direction V that forms an angle β with respect to the X direction. The substantial nozzle arrangement density in the X direction is increased. In FIG. 4, nozzle groups (nozzle rows) arranged along the row direction V are shown with reference numeral 212, and nozzle groups (nozzle rows) arranged along the column direction W are assigned reference numeral 214. Is shown.

  The nozzle arrangement applicable to the present invention is not limited to the nozzle arrangement shown in FIG. 4. For example, a plurality of nozzle arrangements are provided along the row direction along the X direction and the column direction oblique to the X direction and the Y direction. The present invention is also applicable to an embodiment in which the nozzles are arranged in a matrix.

  FIG. 5 is a cross-sectional view showing a three-dimensional configuration of one channel of droplet discharge elements (ink chamber units corresponding to one nozzle 216) serving as a recording element unit. As shown in the figure, the head 210 (head module 210-i) of this example includes a nozzle plate 114 in which nozzles 216 are formed, and a flow path in which flow paths such as a pressure chamber 116 and a common flow path 118 are formed. It has a structure in which plates 120 and the like are laminated and joined. The nozzle plate 114 constitutes a nozzle surface 210A of the head 210, and a plurality of nozzles 216 communicating with the pressure chambers 116 are two-dimensionally formed.

  The flow path plate 120 constitutes a side wall portion of the pressure chamber 116 and a flow path forming a supply port 122 as a throttle portion (most narrowed portion) of an individual supply path that guides ink from the common flow path 118 to the pressure chamber 116. It is a forming member. For convenience of explanation, the flow path plate 120 has a structure in which one or a plurality of substrates are stacked, although it is illustrated schematically in FIG.

  The nozzle plate 114 and the flow path plate 120 can be processed into a required shape by a semiconductor manufacturing process using silicon as a material.

  The common flow path 118 communicates with an ink tank (not shown) serving as an ink supply source, and ink supplied from the ink tank is supplied to each pressure chamber 116 via the common flow path 118.

  A diaphragm 124 constituting a part of the pressure chamber 116 (the top surface in FIG. 5) includes an individual electrode 126 and a lower electrode 128, and the piezoelectric body 130 is sandwiched between the individual electrode 126 and the lower electrode 128. A piezoelectric actuator 132 having the above structure is joined. When the diaphragm 124 is formed of a metal thin film or a metal oxide film, it functions as a common electrode corresponding to the lower electrode 128 of the piezoelectric actuator 132. In the aspect in which the diaphragm is formed of a non-conductive material such as resin, a lower electrode layer made of a conductive material such as metal is formed on the surface of the diaphragm member.

  By applying a driving voltage to the individual electrode 126, the piezoelectric actuator 132 is deformed to change the volume of the pressure chamber 116, and ink is ejected from the nozzle 216 due to the pressure change accompanying this. When the piezo actuator 132 returns to its original state after ink ejection, new ink is refilled into the pressure chamber 116 from the common flow path 118 through the supply port 122.

As shown in FIG. 4, the ink chamber unit having such a structure is latticed in a fixed arrangement pattern along a row direction V that forms an angle β with respect to the main scanning direction and a column direction W that forms an angle α with respect to the sub-scanning direction. The high-density nozzle head of this example is realized by arranging a large number in the shape. In this matrix arrangement, when the interval between adjacent nozzles in the sub-scanning direction is Ls, the nozzles 216 are substantially equivalent to those in which the nozzles 216 are arranged linearly at a constant pitch P _N = Ls / tan θ in the main scanning direction. Can be handled.

  In this example, the piezo actuator 132 is applied as a means for generating ink ejection force to be ejected from the nozzles 216 provided in the head 210. However, a heater is provided in the pressure chamber 116 and the pressure of film boiling caused by heating of the heater is used. It is also possible to apply a thermal method that ejects ink.

  FIG. 6A is a diagram showing the arrangement of the nozzles 216 in the overlapping area (complementary area) 218 of the head modules 210-m and 210- (m + 1) adjacent to each other. It is the figure which permeate | transmitted and showed.

  In FIG. 6A, a nozzle 216 indicated by a black circle is a nozzle belonging to the head module 210-m, and a nozzle 216 indicated by a white circle is a nozzle belonging to the head module 210- (m + 1). Note that an alternate long and short dash line illustrated with reference symbol B in FIG. 6A represents a boundary between the head module 210-m and the head module 210- (m + 1).

FIG. 6B is a diagram showing a projected nozzle group in which the nozzles 216 shown in FIG. 6A are projected so as to be arranged in the head module arrangement direction (X direction). As described above, the nozzle 216 is capable of handling pitch P _N to be equivalent to those arranged linearly at the X-direction.

  As shown in FIG. 6B, in the complementary region 218, the nozzle 216 belonging to the head module 210-m and the nozzle 216 belonging to the head module 210- (m + 1) in the projection nozzle group are nested. The existence ratio changes at a cycle of 4 nozzles. That is, from the left in the figure, in the complementary region 218a, there are two periods in which the nozzle 216 belonging to the head module 210-i is composed of three nozzles and the nozzle 216 belonging to the head module 210- (m + 1) is composed of one nozzle, Next, in the complementary region 218, there are two periods in which the nozzle 216 belonging to the head module 210-m is composed of two nozzles, and the nozzle 216 belonging to the head module 210- (m + 1) is composed of two nozzles, and further, the complementary region 218c. , There are two periods in which the nozzle 216 belonging to the head module 210-m is composed of one nozzle and the nozzle 216 belonging to the head module 210- (m + 1) is composed of three nozzles.

  In this way, in the projection nozzle group shown in FIG. 6B, the nozzle ratio of the head module 210-m gradually decreases from the left side to the right side in the figure, and the nozzle of the head module 210- (m + 1). The abundance ratio is gradually increasing.

  FIG. 6C is a diagram showing lines of recording dots ejected in a straight line in the X direction on the recording medium by the nozzles 216 shown in FIG. In the figure, the circle indicated by the solid line is the outer diameter of the recording dots ejected from the nozzle 216 belonging to the head module 210-m, and the circle indicated by the broken line is the droplet ejected from the nozzle 216 belonging to the head module 210- (m + 1). The outer diameter of the recorded dots is shown.

  FIG. 7 is a system configuration diagram of the inkjet recording apparatus 200. As shown in the figure, the inkjet recording apparatus 200 includes an image input interface 250, an image processing unit 252, a control unit 254 (an example of a control unit), a reference signal generation unit 256, a timing change, in addition to the line head 210 and the scanner 220. 258 and a transport unit 260 (an example of a moving unit).

  The image input interface 250 acquires image data via a wired or wireless communication interface. The image processing unit 252 performs desired image processing on the input image data. The control unit 254 controls the line head 210, the reference signal generation unit 256, the timing change unit 258, the transport unit 260, and the image analysis unit 262 based on the image data processed by the image processing unit 252.

  The reference signal generator 256 includes an oscillation circuit, a frequency divider circuit, and a waveform shaping circuit, and generates a signal that serves as a reference for the drive waveform signal supplied to all the piezo actuators 132 included in each head module 210-i. Let The timing changing unit 258 is provided with each timing changing unit 259-i for each head module 210-i, and changes the timing for each head module 210-i with respect to the reference signal input from the reference signal generating unit 256. And input to each head module 210-i.

  The timing changing unit 259-i has a delay circuit that can set a delay amount, delays the input reference signal by the set delay amount, and inputs the delayed reference signal to each head module 210-i. Thereby, the droplet ejection timing of the nozzle can be shifted for each head module 210-i.

  In addition, the control unit 254 inputs a nozzle selection signal for selecting a nozzle from which an ink droplet is ejected to each head module 210-i. As a result, ink droplets can be ejected from each head module 210-i at a desired timing from a desired nozzle to form recording dots on the recording surface of the paper 1.

  The transport unit 260 transports the paper 1 placed on the upper surface in the Y direction. The control unit 254 can record an image on the entire surface of the paper 1 by the line head 210 by controlling the line head 210 and the transport unit 260.

  In addition, the scanner 220 is disposed on the downstream side of the line head 210 so as to face the paper 1 placed on the upper surface of the transport unit 260, and reads an image recorded on the paper 1. In the present embodiment, the reading resolution of the scanner 220 in the X direction (the width direction of the paper 1) is 500 dpi, and the reading resolution in the Y direction (the conveyance direction of the paper 1) is 100 dpi.

  Image data read by the scanner 220 is input to the image analysis unit 262. The image analysis unit 262 detects the relative displacement amount in the Y direction of each head module 210-i based on the input image data. This process will be described later.

<Principle of detection of misalignment of head module>
FIG. 8 is a diagram showing a test pattern (line pattern) recorded on the recording surface of the paper 1 using the head module 210-m and the head module 210- (m + 1) shown in FIG. This test pattern is composed of a plurality of (here, five) lines extending in the X direction. Each line is similar to the line shown in FIG. 6C, and the head module 210-m and the head module 210- (m + 1). ) Of recording dots ejected from all nozzles 216.

  In FIG. 8, the recording dots 230a indicated by solid lines indicate recording dots ejected by the nozzles 216 of the head module 210-m, and the recording dots 230b indicated by broken lines indicate the head module 210- (m + 1). The recording dots ejected by the nozzles 216 are shown. Reference numeral 232 indicates a complementary recording area recorded by the nozzle 216 in the complementary area 218 of the head module 210-m and the head module 210- (m + 1), and reference numeral 233 indicates the complement of the head module 210-m. A non-complementary recording area (normal recording area) recorded by the nozzle 216 in an area other than the area 218 is shown.

Here, the diameter R of the recording dots ejected from the nozzles 216 satisfy the relation of R> P _N. That is, each recording dot is arranged under the condition that a part thereof overlaps in the X direction. Further, the interval P _{Y in} the Y direction of each line satisfies the relationship P _Y > R. That is, each recording dot (each line) is arranged under the condition that it does not overlap in the Y direction.

  When the head module 210-m and the head module 210- (m + 1) are ideally arranged, as shown in FIG. 8A, lines in the X direction and recording dots formed by the recording dots 230a. The line in the X direction formed by 230b is aligned on the same straight line.

On the other hand, a physical positional deviation in the Y direction, a positional deviation in the Z direction (ejection direction), a head mounting angle θx (an angle about the X axis) between the head module 210-m and the head module 210- (m + 1). Misregistration, variation in ink ejection speed, variation in ejection timing, and the like, misregistration in the Y direction occurs in the ejected recording dots. As a result, as shown in FIGS. 8B and 8C, a deviation occurs in the Y direction between the X direction line formed by the recording dots 230a and the X direction line formed by the recording dots 230b. FIG. 8B shows a case where Δy ₁ and FIG. 8C show a deviation of Δy ₂ .

  As can be seen from FIGS. 8A to 8C, the coverage by the recording dots on the recording surface of the recording medium in the complementary recording area 232 varies depending on the amount of deviation Δy. Therefore, the density (lightness) of the complementary recording area 232 varies depending on the shift amount Δy.

  FIG. 9 is a diagram showing the density D of the complementary recording area 232 and the normal recording area 233 when the scanner 220 reads the test pattern shown in FIG. Here, the density is a value averaged in the Y direction within the width of the test pattern. FIG. 9A shows the density when the deviation amount Δy is zero. As shown in the figure, the density of the complementary recording area 232 and the density of the normal recording area 233 have the same value.

FIG. 9B shows the density in the Y direction when the shift amount Δy is P _Y / 4. As shown in the figure, the density of the complementary recording area 232 is higher than the density of the normal recording area 233 by ΔD _a . That is, since the coverage of the recording dots is higher in the complementary recording area than in the normal recording area, the density of the complementary recording area is higher.

Further, FIG. 9C shows the density when the deviation amount Δy is P _Y / 2. As shown in the figure, the density of the complementary recording area 232 is higher than the density of the normal recording area 233 by ΔD _b (ΔD _b > ΔD _a ). That is, since the coverage of the recording dots is higher in the complementary recording area than in the normal recording area, the density of the complementary recording area is higher. Further, since the coverage of the recording dots is higher in the case of P _Y / 2 than in the case of the deviation amount Δy of P _Y / 4, the density in the case of the deviation amount Δy of P _Y / 2 is greater. It is high.

FIG. 10 is a diagram showing changes in density when Δy is changed from −P _Y to P _{Y. The} horizontal axis indicates the amount of deviation Δy in the Y direction, and the vertical axis indicates the density of the complementary recording area 232 and normal recording. A difference ΔD from the density of the region 233 is shown. As shown in the figure, ΔD is minimum when Δy is −P _Y , 0, and P _Y , and ΔD is maximum when Δy is −P _Y / 2 and P _Y / 2.

  In the present embodiment, the initial deviation amount Δy is obtained and corrected from the relationship between the deviation amount Δy in the Y direction of the adjacent head module and the density of the complementary recording area.

<Position displacement correction processing (first embodiment)>
FIG. 11 is a flowchart showing a correction process of the droplet ejection position deviation between the head modules according to the present embodiment. Here, a description will be given of a case where the Y droplet ejection position misalignment between the head module 210-m and the head module 210- (m + 1) shown in FIG. 6 is corrected.

(Step S1)
First, a test pattern is recorded on the paper 1 by the head module 210-m and the head module 210- (m + 1) (an example of a test pattern recording process). FIG. 12 is a flowchart showing test pattern recording processing.

(Steps S11 and S12)
First, n is initialized to 0. Next, it is incremented to n and n = 1.

(Step S13)
The control unit 254 uses the timing changing unit 259-m and the timing changing unit 259- (m + 1) to set the droplet ejection timing difference Δt between the head module 210-m and the head module 210- (m + 1) as t ₁ (change). An example of the process), the test pattern is recorded on the paper 1.

FIG. 13 is a diagram showing a test pattern 2 recorded on the recording surface of the paper 1 in the present embodiment, and reference numeral 2-1 shows a test pattern when Δt = t ₁ . In the figure, reference numeral 3-m is a non-complementary recording area recorded by the nozzle 216 of the head module 210-m, and reference numeral 3- (m + 1) is a non-complementary recording recorded by the nozzle 216 of the head module 210- (m + 1). An area 4 indicates a complementary recording area recorded by the nozzle 216 in the complementary area of the head module 210-m and the head module 210- (m + 1).

Similarly to the test pattern shown in FIG. 8, the test pattern 2-1 is arranged in the X direction composed of recording dots ejected from all nozzles of the head module 210 -m and the head module 210-(m + 1). A plurality of extending lines are arranged at intervals in the Y direction. The test pattern 2-1 satisfies the relationship of P _Y >R> P _N where R is the diameter of the recording dots ejected from each nozzle 216 and P _Y is the interval between the lines.

It should be noted that the test pattern recorded here may be arranged so that each recording dot partially overlaps in the X direction and does not overlap in the Y direction. For example, when satisfying the relationship R> 2P _N, it may form a respective line by every other nozzle 216.

(Step S14)
It is determined whether or not all test patterns have been recorded. Here, in order to record five patterns, the process returns to step S12, and m is incremented to n = 2.

Next, in step S13, the control unit 254 causes the timing change unit 259-m and the timing change unit 259- (m + 1) to perform the droplet ejection timing difference between the head module 210-m and the head module 210- (m + 1). A test pattern is recorded on the paper 1 with Δt being t ₂ . Code 2-2 shown in FIG. 13 shows a test pattern for Δt = _{t 2.}

Thereafter, similarly, test patterns 2-3, 2-4, and 2-5 are recorded. Note that t ₁ , t ₂ , t ₃ , t ₄ , and t ₅ are different values. Here, all the test patterns 2-1 to 2-5 are recorded on one sheet of paper 1, but a mode of recording over two or more sheets 1 is also possible.

(Step S2)
Returning to FIG. 11, the recorded test pattern is read by the scanner 220 and read data of the test pattern is acquired (an example of a read data acquisition process). As described above, the reading resolution of the scanner 220 is 500 dpi in the X direction and 100 dpi in the Y direction.

(Step S3)
The image analysis unit 262 acquires (generates) density data (an example of complementary area data) of the complementary recording area 4 of the test patterns 2-1 to 2-5 from the read data of the test pattern 2 acquired in step S2 ( An example of a data generation process).

In the present embodiment, the density data of the non-complementary recording area 3-m of the test patterns 2-1 to 2-5 (an example of non-complementary area data) is acquired simultaneously, and the density data of the complementary recording area 4 for each test pattern is obtained. A difference ΔD from the density data of the non-complementary recording area 3-m is calculated. Differences in the test patterns 2-1 to 2-5 are denoted by ΔD ₁ to ΔD ₅ , respectively.

(Step S4)
The image analysis unit 262 calculates an initial droplet ejection position shift amount (when the droplet ejection timing is not shifted) between the head module 210-m and the head module 210- (m + 1) (an example of a calculation process).

As shown in FIG. 14A, the image analysis unit 262 displays the points (t ₁ , ΔD ₁₎ acquired in step S3 on a graph in which the horizontal axis represents the difference in droplet ejection timing and the vertical axis represents the difference in density data. ) To (t ₅ , ΔD ₅ ) are plotted. These plotted points, obtains an approximation curve as shown in FIG. 14 (b), calculates a value of Δt comprising the approximate curve as ΔD = ₀ (t 0 in the example of FIG. _14).

From this Δt = t ₀ , assuming that the transport speed of the paper 1 transported in the Y direction by the transport unit 260 is V _Y , the initial displacement of the droplet ejection position between the head module 210 -m and the head module 210-(m + 1). The quantity can be expressed as t ₀ × V _Y.

  In this way, a plurality of test patterns 2-1 to 2-5 having different recording position shift amounts are recorded, and the density data of the complementary recording area 4 and the density data of the non-complementary recording area 3-m of each test pattern are recorded. The difference ΔD is calculated. From the relationship between the shift amount of each test pattern and the difference between the density data, the shift amount at which the difference ΔD becomes 0 can be calculated using an approximation process using a polynomial. The shift amount at which the difference ΔD becomes 0 may be calculated using interpolation (interpolation) processing, extrapolation (extrapolation) processing, or the like instead of approximation processing using a polynomial. Further, the initial shift amount can be calculated from the shift amount at which the difference ΔD becomes zero.

When the amount of deviation in the Y direction of the adjacent head module is larger than the interval P _{Y in} the Y direction of each line, the exact amount of deviation cannot be calculated only with the density data in the complementary recording area. In this case, the approximate shift amount in the Y direction between the head modules is calculated by deriving the position of each line with a reading resolution unit of the scanner 220 or with an accuracy of a fraction thereof.

In this embodiment, since the reading resolution in the Y direction is 100 dpi, the resolution is 250 μm. Therefore, even if the deviation amount can be calculated with an accuracy of 1/10, the reading accuracy is 25 μm. In this case, the interval P _{Y in} the Y direction of each line needs to be 25 μm or more. As described above, the interval P _{Y in} the Y direction between the lines of the test pattern is preferably set according to the reading resolution of the scanner 220.

(Step S5)
Finally, the droplet ejection position deviation is corrected (an example of a correction process). Here, the timing changing unit 259-m and the timing changing unit 259- (m + 1), may be controlled so as droplet ejection timing of the head module 210-m and the head module 210- (m + 1) is shifted by _{t 0} . For example, the droplet ejection timing of the head module 210-m remain constant, be shifted by _{t 0} than the droplet ejection timing of the head module 210- (m + 1) head module droplet ejection timing of the 210-m.

The droplet ejection timing shift amount t ₀ may be stored in a memory (not shown) so that the control unit 254 reads it from the memory and controls the timing changing unit 258 during image recording.

In this embodiment, the timing changing unit 258 (an example of a correction unit) corrects the droplet ejection position shift by shifting the droplet ejection timing for each head module. However, the head module 210-m and the head module 210- (m + 1) The droplet ejection position deviation may be corrected by physically correcting the position in the Y direction. In this case, the physical shift amount t ₀ × V _Y can be calculated from Δt = t ₀ acquired in step S 4 and the transport speed V _{Y of the} sheet 1 transported in the Y direction by the transport unit 260. .

  Also, the test patterns 2-1 to 2-5 were recorded by shifting the droplet ejection timing for each head module by the timing changing unit 258, but the head modules 210-m and 210- (m + 1) in the Y direction were recorded. The position may be physically changed and recorded.

  The test pattern 2 is composed of five types of test patterns 2-1 to 2-5 in which the droplet ejection timing is changed. In order to accurately obtain the approximate curve shown in FIG. It is preferable that the number of test patterns whose timing is changed is large.

  Further, in this embodiment, the value Δt at which ΔD = 0 is calculated using the difference ΔD between the density data of the complementary recording area 4 and the density data of the non-complementary recording area 3-m. The value of Δt that minimizes the density data may be calculated from the density data.

  In this case, the test pattern may be recorded using only the nozzles 216 in the complementary region 218, or only the complementary recording region 232 may be read from the test patterns recorded using all the nozzles 216.

  However, when there is a variation in density in the image of the test pattern 2 due to various factors, if the determination is made only with the density data in the complementary recording area 4, there may be a large error in detecting the positional deviation. As in this embodiment, the determination of the difference ΔD based on the density of the non-complementary recording area 3-m makes it possible to reduce the positional deviation detection error.

  Note that it is not essential to generate density data from the read data of the test pattern, and other methods may be used as long as the value of Δt can be calculated from the read data of the test pattern. For example, the read data may be used as it is. Since the read data is data that depends on the amount of reflected light, the change characteristics of the signal in the complementary region are opposite to those in the case of using the density, and the smaller the amount of deviation Δy between the head modules, the smaller.

  In the present embodiment, the X-direction line pattern is used as the test pattern. However, other test patterns may be used as long as the positional deviation of the landing dots in the complementary region appears as a change in image density.

<Second Embodiment>
In the first embodiment, the example in which the positional deviation in the Y direction between the two adjacent head modules 210-m and 210- (m + 1) is corrected has been described. An actual line head is illustrated in FIG. As described above, it has three or more head modules. Here, a description will be given of a mode in which the positional deviation of the relative positions of three or more head modules is corrected.

  FIG. 15 is a diagram showing the test pattern 5 recorded on the recording surface of the line head 210 and the sheet 1 of the present embodiment. The line head 210 of this embodiment includes five head modules 210-1 to 210-5.

  As in the first embodiment, first, test patterns 5-1 to 5-5 are recorded on the paper 1 while changing the droplet ejection timing by the head modules 210-1 to 210-5 of the line head 210. Similarly to the test pattern 2 shown in FIG. 13, the test pattern 5 has a line extending in the X direction composed of recording dots ejected from all nozzles of the head modules 210-1 to 210-5. A plurality are arranged at intervals in the direction.

  In addition, each test pattern 5-1 to 5-5 has a different droplet ejection timing from the adjacent head module. Here, the droplet ejection timings of the head modules 210-1, 210-3, and 210-5 (hereinafter referred to as odd-numbered modules) are set at the same time, and the head modules 210-2 and 210-4 (hereinafter referred to as even-numbered modules) are impacted. Drop timing is simultaneous. Further, the droplet ejection timing of the odd module is made constant, and the test pattern is recorded while changing the droplet ejection timing of the even module with respect to this timing.

Test patterns 5-1 shown in FIG. 15 is a test pattern difference Δt of droplet ejection timing was t ₁ of the odd modules and the even modules. Similarly, test patterns 5-2, 5-3, 5-4, and 5-5 are test patterns in which Δt is t ₂ , t ₃ , t ₄ , and t ₅ , respectively. Similar to the test pattern 2 shown in FIG. 13, t ₁ , t ₂ , t ₃ , t ₄ , and t ₅ are different values.

  The test pattern 5 recorded in this way is read by the scanner 220 to obtain density data. As described with reference to FIG. 14, the image analysis unit 262 calculates the value of Δt at which ΔD = 0, that is, the correction amount of the droplet ejection timing, from the density data for each complementary recording area.

The correction amount between the head module 210-1 and the head module 210-2 is Δt ₁₁ , the correction amount between the head module 210-2 and the head module 210-3 is Δt ₁₂ , and the head module 210-3 and the head module 210-4 Is the correction amount Δt ₁₃ , and the correction amounts of the head module 210-4 and the head module 210-5 are Δt ₁₄ .

In this case, the control unit 254 sets the timing correction amounts of the timing change units 259-1, 259-2, 259-3, 259-4, and 259-5 to 0, Δt ₁₁ , Δt ₁₁ + Δt ₁₂ , and Δt _{11, respectively.} + Δt ₁₂ + Δt ₁₃ , Δt ₁₁ + Δt ₁₂ + Δt ₁₃ + Δt ₁₄ may be used.

<Outline of Inkjet Recording Apparatus According to Other Embodiment>
FIG. 16 is a configuration diagram showing the overall configuration of another inkjet recording apparatus. The inkjet recording apparatus 10 includes a plurality of colors from inkjet heads 72M, 72K, 72C, and 72Y on a recording medium 24 (sometimes referred to as “paper” for convenience) held on an impression cylinder (drawing drum 70) of the drawing unit 16. Is an impression cylinder direct drawing type ink jet recording apparatus that forms a desired color image by applying ink droplets of the ink. A treatment liquid (here, an aggregating treatment liquid) is applied onto the recording medium 24 before ink droplet ejection, This is an on-demand type image forming apparatus to which a two-liquid reaction (aggregation) method for forming an image on a recording medium 24 by reacting a treatment liquid and an ink liquid is applied.

  As shown in FIG. 16, the ink jet recording apparatus 10 mainly includes a paper feed unit 12, a treatment liquid application unit 14, a drawing unit 16, a drying unit 18, a fixing unit 20, and a discharge unit 22.

(Paper Feeder)
The paper supply unit 12 is a mechanism that supplies the recording medium 24 to the treatment liquid application unit 14, and a recording medium 24 that is a sheet is stacked on the paper supply unit 12. The paper feed unit 12 is provided with a paper feed tray 50, and the recording medium 24 is fed from the paper feed tray 50 to the processing liquid application unit 14 one by one.

  In the inkjet recording apparatus 10 of this example, a plurality of types of recording media 24 having different paper types and sizes (paper sizes) can be used as the recording medium 24. A mode is also possible in which a plurality of paper trays (not shown) are provided in the paper feed unit 12 to separately collect various recording media and the paper to be sent to the paper feed tray 50 is automatically switched from among the plurality of paper trays. In addition, a mode is also possible in which the operator selects or replaces the paper tray as necessary. In this example, a sheet (cut paper) is used as the recording medium 24, but a configuration in which continuous paper (roll paper) is cut to a required size and fed is also possible.

(Processing liquid application part)
The processing liquid application unit 14 is a mechanism that applies the processing liquid to the recording surface of the recording medium 24. The treatment liquid contains a color material aggregating agent that agglomerates the color material (pigment in this example) applied in the ink provided by the drawing unit 16, and the ink comes into contact with the colorant when the treatment liquid comes into contact with the ink. And the solvent are promoted.

  As shown in FIG. 16, the treatment liquid application unit 14 includes a paper feed drum 52, a treatment liquid drum 54, and a treatment liquid application device 56. The treatment liquid drum 54 is a drum that holds and rotates and conveys the recording medium 24. The processing liquid drum 54 is provided with a claw-shaped holding means (gripper) 55 on the outer peripheral surface thereof, and the recording medium 24 is sandwiched between the claw of the holding means 55 and the peripheral surface of the processing liquid drum 54 to thereby remove the recording medium 24. The tip can be held. The treatment liquid drum 54 may be provided with suction holes on the outer peripheral surface thereof and connected to suction means for suction from the suction holes. As a result, the recording medium 24 can be held in close contact with the peripheral surface of the treatment liquid drum 54.

  A processing liquid coating device 56 is provided outside the processing liquid drum 54 so as to face the peripheral surface thereof. The processing liquid coating device 56 includes a processing liquid container in which the processing liquid is stored, an anix roller partially immersed in the processing liquid in the processing liquid container, and the recording medium 24 on the anix roller and the processing liquid drum 54. And a rubber roller that transfers the measured processing liquid to the recording medium 24. According to the processing liquid application device 56, the processing liquid can be applied to the recording medium 24 while being measured.

  The recording medium 24 to which the processing liquid is applied by the processing liquid applying unit 14 is transferred from the processing liquid drum 54 to the drawing drum 70 of the drawing unit 16 via the intermediate transport unit 26.

(Drawing part)
The drawing unit 16 includes a drawing drum 70, ink jet heads 72 </ b> M, 72 </ b> K, 72 </ b> C, 72 </ b> Y, and a paper holding roller 74. The drawing drum 70 includes a claw-shaped holding means (gripper) 71 on the outer peripheral surface thereof, like the processing liquid drum 54. The recording medium 24 fixed to the drawing drum 70 is conveyed with the recording surface facing outward, and ink is applied to the recording surface from the inkjet heads 72M, 72K, 72C, 72Y.

  The configurations of the inkjet heads 72M, 72K, 72C, and 72Y are the same as those of the line head 210 described with reference to FIGS.

  The droplets of the corresponding color ink are ejected from the respective ink jet heads 72M, 72K, 72C, 72Y toward the recording surface of the recording medium 24 held tightly on the drawing drum 70. The ink comes into contact with the treatment liquid previously applied to the recording surface, and the color material (pigment) dispersed in the ink is aggregated to form a color material aggregate. Thereby, the color material flow on the recording medium 24 is prevented, and an image is formed on the recording surface of the recording medium 24.

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

  The recording medium 24 on which an image is formed by the drawing unit 16 is transferred from the drawing drum 70 to the drying drum 76 of the drying unit 18 via the intermediate conveyance unit 28.

(Drying part)
The drying unit 18 is a mechanism for drying moisture contained in the solvent separated by the color material aggregation action, and includes a drying drum 76 and a solvent drying device 78 as shown in FIG.

  Similar to the treatment liquid drum 54, the drying drum 76 includes a claw-shaped holding unit (gripper) 77 on the outer peripheral surface thereof, and the holding unit 77 can hold the leading end of the recording medium 24.

  The solvent drying device 78 is disposed at a position facing the outer peripheral surface of the drying drum 76, and includes a plurality of IR heaters 82 and hot air ejection nozzles 80 disposed between the IR heaters 82.

  Various drying conditions can be realized by appropriately adjusting the temperature and air volume of the hot air blown toward the recording medium 24 from each hot air jet nozzle 80 and the temperature of each IR heater 82.

  The surface temperature of the drying drum 76 is set to 50 ° C. or higher. Drying is accelerated by heating from the back surface of the recording medium 24, and image destruction during fixing can be prevented. The upper limit of the surface temperature of the drying drum 76 is not particularly limited, but from the viewpoint of safety of maintenance work such as cleaning ink adhering to the surface of the drying drum 76 (preventing burns due to high temperature). It is preferably set to 75 ° C. or lower (more preferably 60 ° C. or lower).

  The recording drum 24 is held on the outer peripheral surface of the drying drum 76 so that the recording surface of the recording medium 24 faces outward (that is, in a state where the recording surface of the recording medium 24 is convex), and is dried while being rotated and conveyed By doing so, it is possible to prevent the recording medium 24 from being wrinkled or lifted, and to reliably prevent uneven drying due to these.

  The recording medium 24 that has been dried by the drying unit 18 is transferred from the drying drum 76 to the fixing drum 84 of the fixing unit 20 via the intermediate conveyance unit 30.

(Fixing part)
The fixing unit 20 includes a fixing drum 84, a halogen heater 86, a fixing roller 88, and an inline sensor 90. Like the processing liquid drum 54, the fixing drum 84 includes a claw-shaped holding unit (gripper) 85 on its outer peripheral surface, and the holding unit 85 can hold the leading end of the recording medium 24.

  With the rotation of the fixing drum 84, the recording medium 24 is conveyed with the recording surface facing outward. The recording surface is preheated by the halogen heater 86, fixed by the fixing roller 88, and by the inline sensor 90. Inspection is performed. The halogen heater 86 is controlled to a predetermined temperature (for example, 180 ° C.). Thereby, the recording medium 24 is preheated.

  The fixing roller 88 is a roller member for heating and pressurizing the dried ink to weld the self-dispersing thermoplastic resin fine particles in the ink to form a film of the ink. The fixing roller 88 is configured to heat and press the recording medium 24. Composed. Specifically, the fixing roller 88 is disposed so as to be in pressure contact with the fixing drum 84, and constitutes a nip roller with the fixing drum 84. As a result, the recording medium 24 is sandwiched between the fixing roller 88 and the fixing drum 84 and nipped at a predetermined nip pressure (for example, 0.15 MPa), and a fixing process is performed.

  The fixing roller 88 is configured by a heating roller in which a halogen lamp is incorporated in a metal pipe such as aluminum having good thermal conductivity, and is controlled to a predetermined temperature (for example, 60 to 80 ° C.). By heating the recording medium 24 with this heating roller, thermal energy equal to or higher than the Tg temperature (glass transition temperature) of the thermoplastic resin fine particles contained in the ink is applied, and the thermoplastic resin fine particles are melted. As a result, pressing and fixing are performed on the unevenness of the recording medium 24, and the unevenness of the image surface is leveled to obtain glossiness.

  In the embodiment of FIG. 16, only one fixing roller 88 is provided. However, a configuration in which a plurality of fixing rollers 88 are provided may be provided depending on the thickness of the image layer and the Tg characteristics of the thermoplastic resin fine particles.

  On the other hand, the inline sensor 90 is a means for reading an image fixed on the recording medium 24 and converting it into image data, and a CCD line sensor or the like is applied.

  According to the fixing unit 20 configured as described above, the thermoplastic resin fine particles in the thin image layer formed by the drying unit 18 are heated and pressurized by the fixing roller 88 and melted. Can be fixed and fixed. Further, by setting the surface temperature of the fixing drum 84 to 50 ° C. or higher, drying is promoted by heating the recording medium 24 held on the outer peripheral surface of the fixing drum 84 from the back surface, thereby preventing image destruction during fixing. In addition, the image intensity can be increased by the effect of increasing the image temperature.

  In addition, when a UV curable monomer is contained in the ink, after the water is sufficiently volatilized in the drying unit, the image is irradiated with UV at the fixing unit equipped with a UV irradiation lamp. The monomer can be cured and polymerized to improve the image strength.

(Discharge part)
As shown in FIG. 16, a discharge unit 22 is provided following the fixing unit 20. The discharge unit 22 includes a discharge tray 92, and a transfer drum 94, a conveyance belt 96, and a tension roller 98 are provided between the discharge tray 92 and the fixing drum 84 of the fixing unit 20 so as to be in contact therewith. It has been. The recording medium 24 is sent to the conveying belt 96 by the transfer drum 94 and discharged to the discharge tray 92.

  Although not shown in the drawing, the ink jet recording apparatus 10 of this example has an ink storage / loading unit for supplying ink to each of the ink jet heads 72M, 72K, 72C, and 72Y, and a treatment liquid application, in addition to the above-described configuration. A means for supplying a processing liquid to the unit 14, and a head maintenance unit for cleaning each of the inkjet heads 72M, 72K, 72C, 72Y (wiping, purging, nozzle suction, etc. of the nozzle surface), A position detection sensor for detecting the position of the recording medium 24, a temperature sensor for detecting the temperature of each part of the apparatus, and the like are provided.

(Control system)
FIG. 17 is a principal block diagram showing the system configuration of the inkjet recording apparatus 10. The inkjet recording apparatus 10 includes a communication interface 170, a system controller 172, a memory 174, a motor driver 176, a heater driver 178, a print control unit 180, an image buffer memory 182, a head driver 184, and the like.

  The communication interface 170 is an interface unit that receives image data sent from the host computer 186. As the communication interface 170, a serial interface such as USB (Universal Serial Bus), IEEE 1394, Ethernet (registered trademark), a wireless network, or a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted. Image data sent from the host computer 186 is taken into the inkjet recording apparatus 10 via the communication interface 170 and temporarily stored in the memory 174.

  The memory 174 is a storage unit that temporarily stores an image input via the communication interface 170, and data is read and written through the system controller 172. The memory 174 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used.

  The system controller 172 includes a central processing unit (CPU) and its peripheral circuits, and functions as a control device that controls the entire inkjet recording apparatus 10 according to a predetermined program, and also functions as an arithmetic device that performs various calculations. . That is, the system controller 172 controls the communication interface 170, the memory 174, the motor driver 176, the heater driver 178, and the like, performs communication control with the host computer 186, read / write control of the memory 174, etc. A control signal for controlling the motor 188 and the heater 189 is generated.

  The memory 174 stores programs executed by the CPU of the system controller 172 and various data necessary for control. Note that the memory 174 may be a non-rewritable storage means, or may be a storage means such as an electrically erasable / recordable nonvolatile memory. The memory 174 is used as a temporary storage area for image data, and is also used as a program development area and a calculation work area for the CPU.

  Various control programs are stored in the program storage unit 190, and the control programs are read and executed in accordance with instructions from the system controller 172. The program storage unit may be a semiconductor memory such as a ROM or a non-volatile memory, or may be a magnetic disk. An external interface may be provided and a memory card or PC card may be used.

  Of course, you may provide several recording media among these recording media. Note that the program storage unit may also be used as a storage means such as operation parameters.

  The motor driver 176 is a driver that drives the motor 188 in accordance with an instruction from the system controller 172. In FIG. 17, a motor (actuator) arranged at each part in the apparatus is represented by reference numeral 188. For example, the motor 198 shown in FIG. 17 includes a motor for driving the processing liquid drum 54 and the drawing drum 70 shown in FIG.

  The heater driver 178 is a driver that drives the heater 199 in accordance with an instruction from the system controller 172. In FIG. 17, a plurality of heaters provided in the ink jet recording apparatus 10 are represented by reference numeral 189. For example, the heater 189 shown in FIG. 17 includes the IR heater 82 and the halogen heater 86 shown in FIG.

  The print control unit 180 has a signal processing function for performing various processes, corrections, and the like for generating a print control signal from the image data in the memory 174 in accordance with the control of the system controller 172. The generated print data This is a control unit that supplies (dot data) to the head driver 184. Necessary signal processing is performed in the print control unit 180, and the ejection amount and ejection timing of the ink droplets of the inkjet head 72 are controlled via the head driver 184 based on the image data. Thereby, a desired dot size and dot arrangement are realized.

  The print control unit 180 is provided with an image buffer memory 182, and image data, parameters, and other data are temporarily stored in the image buffer memory 182 when image data is processed in the print control unit 180. Also possible is an aspect in which the print controller 180 and the system controller 172 are integrated and configured with one processor.

  An overview of the processing flow from image input to print output is as follows. Image data to be printed is input from the outside via the communication interface 170 and stored in the memory 174. At this stage, for example, RGB multivalued image data is stored in the memory 174.

  The original image (RGB) data stored in the memory 174 is sent to the print control unit 180 via the system controller 172, and the print control unit 180 uses the halftoning process using a threshold matrix, an error diffusion method, etc. It is converted into dot data (binary data or multi-value data including dot size information) for each color (K, C, M, Y).

  Thus, the dot data generated by the print control unit 180 is stored in the image buffer memory 182. This color-specific dot data is converted into CMYK droplet ejection data for ejecting ink from the nozzles of the inkjet head 72, and ink ejection data to be printed is determined.

  The head driver 184 generates a drive signal for driving a piezoelectric element corresponding to each nozzle of the inkjet head 72 based on print data (that is, dot data stored in the image buffer memory 182) given from the print control unit 180. Output. The head driver 184 may include a feedback control system for keeping the head driving condition constant.

  The ink jet recording apparatus 10 shown in this example includes an ink jet head 72 configured by connecting a plurality of head modules each having a plurality of nozzles arranged in a direction orthogonal to the conveyance direction of the recording medium 24, and each head module includes Is applied with a drive signal whose timing is changed from a common reference signal. In response to this drive signal, a piezoelectric drive method is applied in which ink is ejected from the nozzle corresponding to each piezoelectric element by switching on and off the switch elements connected to the individual electrodes of each piezoelectric element.

  The print control unit 180 illustrated in FIG. 17 includes the control unit 254, the reference signal generation unit 256, the timing change unit 258, and the image analysis unit 262 illustrated in FIG.

  The head driver 184 may be provided with a head module moving means for physically changing the position of each head module in the Y direction.

  The print detection unit 144 is a block including the in-line sensor 90. The print detection unit 144 reads an image printed on the recording medium 24, performs necessary signal processing, etc., and print status (color, density, presence / absence of ejection, variation in droplet ejection, etc.) ) And the detection result is provided to the print controller 180 via the system controller 172.

  The print control unit 180 determines an abnormal discharge nozzle based on information obtained from the print detection unit 144, and performs image correction when the abnormal discharge nozzle can be corrected by image correction. Then, a control signal is sent to each part via the system controller 172. If the image correction cannot cope, a control signal is sent to each unit via the system controller 172 so as to perform a nozzle recovery operation such as preliminary discharge or suction for the abnormal discharge nozzle.

  In the above embodiment, the case where the present invention is applied to an ink jet recording apparatus has been described, but the scope of application of the present invention is not limited thereto. That is, the present invention relates to an image recording apparatus of a type other than an ink jet recording apparatus, for example, a thermal transfer recording apparatus including a recording head using a thermal element as a recording element, and an LED electrophotography including a recording head including an LED element as a recording element. The present invention can also be applied to a printer and a silver halide photographic printer having an LED line exposure head.

  The technical scope of the present invention is not limited to the scope described in the above embodiment. The configurations and the like in the embodiments can be appropriately combined between the embodiments without departing from the gist of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Paper, 2, 5 ... Test pattern, 3-m, 233 ... Non-complementary recording area, 4,232 ... Complementary recording area, 218 ... Complementary area, 200 ... Inkjet recording apparatus, 210 ... Line head, 210-i ... Head module, 216 ... Nozzle, 220 ... Scanner, 254 ... Control unit, 258 ... Timing changing unit, 260 ... Conveying unit, 262 ... Image analysis unit

Claims (11)

A recording head constituted by connecting a plurality of head modules each having a plurality of recording elements arranged in a first direction, wherein the plurality of recording elements are projected so as to be arranged in the first direction. A recording head having a complementary region in which the projection recording elements of adjacent head modules are nested,
Moving means for relatively moving the recording head and the recording medium in a second direction intersecting the first direction;
Control means for performing recording on the recording medium by the recording element while relatively moving the recording head and the recording medium;
A positional deviation detection method for a recording head of an image recording apparatus comprising:
A changing step of changing a shift amount of a recording position in the second direction by a changing unit for the first head module and the second head module adjacent to each other among the plurality of head modules;
A test pattern recording step of recording a test pattern on the recording medium by the first head module and the second head module, wherein some of the recording dots recorded adjacent to each other in the first direction are A test pattern recording step for recording a plurality of test patterns under overlapping conditions and different recording position shift amounts;
A read data acquisition step of acquiring read data of the recorded test pattern;
A data generation step of generating complementary region data of a portion recorded by a recording element of a complementary region of the first head module and the second head module from the read data;
A calculation step of calculating an initial shift amount of a recording position in the second direction between the first head module and the second head module from the shift amount and the complementary region data;
A method for detecting misalignment of a recording head comprising: The data generation step includes a complementary area data of a portion recorded by a recording element of a complementary area of the first head module and the second head module, and the first head module or the second head module. To obtain a difference from the non-complementary region data of the portion recorded by the recording element in the region other than the complementary region,
The recording head positional deviation detection method according to claim 1, wherein the calculating step calculates the initial deviation amount from the shift amount and the difference.   The method of detecting a positional deviation of a recording head according to claim 1, wherein the test pattern is a line pattern in the first direction.   The method of detecting a positional deviation of a recording head according to any one of claims 1 to 3, wherein the data generation step generates density data.   The changing step changes the recording position shift amount in the second direction by making the recording timing of the recording element of the first head module different from the recording timing of the recording element of the second head module. Item 5. A method for detecting positional deviation of a recording head according to any one of Items 1 to 4.   6. The method of detecting misalignment of a recording head according to claim 1, wherein the recording element is arranged two-dimensionally in the head module.   In the complementary area, the recording head has a recording element ratio of the first head module that gradually decreases from the first head module toward the second head module in the complementary region. The method for detecting a positional deviation of a recording head according to claim 1, wherein the abundance ratio of the recording elements gradually increases.   8. The method of detecting misalignment of a recording head according to claim 1, wherein the recording head is an inkjet head, and the recording element is a nozzle that ejects ink. A recording head constituted by connecting a plurality of head modules each having a plurality of recording elements arranged in a first direction, wherein the plurality of recording elements are projected so as to be arranged in the first direction. A recording head having a complementary region in which the projection recording elements of adjacent head modules are nested,
Moving means for relatively moving the recording head and the recording medium in a second direction intersecting the first direction;
Control means for performing recording on the recording medium by the recording element while relatively moving the recording head and the recording medium;
A correction unit that corrects the positional deviation of the recording head based on the initial deviation amount calculated by the positional deviation detection method of the recording head according to claim 1;
An image recording apparatus comprising:   The image recording apparatus according to claim 9, wherein the correcting unit is the changing unit.   The image recording apparatus according to claim 9, further comprising a reading unit that reads the recorded test pattern and generates read data.

Images