JP6111542B2 - Discharge adjustment pattern forming method, ink jet head discharge adjusting method, and ink jet printer - Google Patents

Description

  The present invention relates to a nozzle ejection adjustment technique for suppressing density unevenness caused by variations in ejection characteristics among a plurality of nozzles of an inkjet head.

  Conventionally, in the field of inkjet printers, there has been a problem that density unevenness occurs in a recorded image formed on a recording medium due to a difference in ink ejection characteristics between a plurality of nozzles of an inkjet head. ing.

  That is, due to factors such as variations in nozzle diameter, variations in flow resistance due to differences in the shape of the ink flow path connected to the nozzles, or variations in the characteristics of actuators that impart discharge energy to ink, the discharge characteristics ( The amount of ejected ink droplets and the velocity of the ejected droplets vary. If the ejection characteristics vary between multiple nozzles, the size of the dots formed on the recording medium will vary, or the dot position (landing position) will deviate from the specified position, resulting in density in the recorded image. Unevenness occurs and image quality is greatly impaired. Thus, conventionally, a technique for suppressing density unevenness caused by variations in ejection characteristics by adjusting the ejection conditions of each of a plurality of nozzles is known.

  Patent Document 1 discloses a method for printing a pattern for acquiring density unevenness information necessary for correcting the ejection characteristic variation among a plurality of nozzles. In this Patent Document 1, first, while moving an inkjet head in a predetermined scanning direction with respect to a recording paper (recording medium), a plurality of nozzles constituting one nozzle row are used on this recording paper. Two fill patterns (patterns for detecting density unevenness) are formed. Next, these patterns are read by the image sensor, and the densities of the portions of the respective patterns formed by the plurality of nozzles are acquired. Based on the density data acquired for each of the plurality of nozzles in this way, density correction for each nozzle is performed during image recording. In the method of Patent Document 1, four density data corresponding to four density measurement patterns are obtained for one nozzle. However, in Patent Document 1, these four density data are averaged. Or there is a description that the mode may be used.

Japanese Patent No. 317849

  By the way, it is desirable that the gap between the inkjet head and the recording medium (hereinafter, also simply referred to as a gap) is constant at a certain ideal value throughout the recording medium. In many cases, gaps vary across the recording medium due to floating, warping, or undulation in the medium.

  When the density measurement pattern is formed on the recording medium in such a state, the density of the density measurement pattern changes due to the gap at the position where the pattern is formed. An example is given below.

  As a recording method using an inkjet head, a method of recording by discharging ink only when moving in one direction of scanning (referred to as one-way printing) and a method of recording by discharging ink when moving in two directions (respectively) Called bidirectional printing).

  When the bidirectional printing is performed, if the gap between the nozzle of the inkjet head and the recording medium varies, the landing positions of the inks ejected in both directions are shifted. As shown in FIG. 5 of the embodiment, when the gap between the inkjet head 26 and the recording medium 100 is smaller than the ideal gap (Ga) (Gb), the flight time of the ink droplets ejected from the nozzles 31. The ink ejected in both directions is landed at positions B1 and B2 close to the ejection position. In contrast, when the gap is larger than the ideal gap (Ga) (Gc), the droplet flight time is long, and the ink lands on the positions C1 and C2 far from the ejection position. Accordingly, the ink ejected during the forward movement and the ink ejected during the backward movement should land at the position A in the scanning direction, respectively. When the gap is small, they land at the positions B1 and B2, respectively, and the gap is large. Will land at positions C1 and C2, respectively. In this way, when the landing positions of the inks ejected in both directions are deviated, density unevenness occurs in an image formed by bidirectional printing.

  As described above, particularly when the pattern is formed by bidirectional printing, the pattern density change due to the gap difference at the position where the density measurement pattern is formed appears remarkably. Even in the case of directional printing, a change in the density of the pattern due to the difference in gap can occur.

This will be described with reference to FIG. In FIG. 11A, a carriage 25 (inkjet head 26) indicated by a solid line on the left side indicates a position when ink is ejected from the nozzle 31, and a carriage 25 (inkjet head 26) indicated by a two-dot chain line on the right side. Indicates that the ink ejected at the left solid line position has moved from the solid line position to this point.
As shown in FIG. 11A, when the ink jet head 26 mounted on the carriage 25 moves in one direction (rightward in the figure), a gap is formed when ink is ejected from the plurality of nozzles 31. If the gap is different from the ideal gap (Ga), the ink landing position is accordingly shifted in the scanning direction with respect to the ideal landing position. However, if considered normally, the amount of deviation of the landing position due to the gap is the same among all the dots in one pattern. That is, in FIG. 11A, a pattern composed of dots A formed at the ideal gap (Ga) position, a pattern composed of dots B formed at the small gap position (Gb), and a position where the gap is large. In the pattern composed of dots C formed in (Gc), each pattern itself has the same dot arrangement, and the position of the entire pattern is simply shifted in the scanning direction.

  However, the above is a case where it is assumed that only one droplet is ejected from one nozzle 31, but a plurality of droplets are often ejected from one nozzle 31. For example, as shown in FIG. 11B, after the main droplet Da is discharged from one nozzle 31, the satellite droplet Db having a considerably smaller volume than the main droplet Da is discharged with a delay. By the way, when droplets are continuously discharged from one nozzle 31, the satellite droplet Db generated at a certain discharge timing is usually combined with the main droplet Da discharged at the next discharge timing to be recorded medium. Land on 100. However, when the gap is smaller than the ideal value (the state shown in FIG. 11B), it is conceivable that the main droplet Da and the satellite droplet Db land separately before being combined. As a result, the density of the pattern is increased (increased) in that portion.

  In this regard, in Patent Document 1, four density measurement patterns are formed in four areas of the recording paper, respectively, but how close each of these four density measurement patterns is to the ideal value. It is difficult to determine whether it is formed under conditions. Accordingly, it is impossible to select a pattern in which the gap is close to the ideal state from the four density measurement patterns in consideration of the gap variation and perform the discharge adjustment based on the selected pattern.

  An object of the present invention is to specify a pattern formed under a condition in which a gap is close to an ideal state, and to use this pattern to eliminate the influence of gap variation as much as possible, and to perform discharge adjustment of each nozzle.

The discharge adjustment pattern forming method of the first invention is orthogonal to the scanning direction by an inkjet head that discharges ink from a plurality of nozzles while moving along one direction in the scanning direction and another direction opposite to the one direction. A method of forming a columnar pattern on a recording medium , wherein a first density measurement pattern having a plurality of the columnar first patterns by ejecting ink from the plurality of nozzles of the inkjet head; and the concentration measurement pattern including a second density measuring pattern having a large number of the rows of the second pattern to form each of a plurality of pattern forming regions on the recording medium, and density measurement pattern forming step, before the concentration by ejecting ink from the same plurality of nozzles and when forming the measurement pattern, said rows of pattern The determination pattern including a first determination pattern and a second determination pattern having one down, to the plurality of pattern formation region in which the density measuring pattern is formed respectively, are formed respectively, and a determination pattern forming step The first concentration measurement pattern is moving in the one direction at a discharge timing delayed by a predetermined deviation amount from a reference timing corresponding to each landing target position of the multiple first patterns. ink formed by Rukoto ejected from the plurality of nozzles of the ink jet head, the second concentration measurement pattern, the reference corresponding to the target landing position of the second pattern positioned between said first pattern adjacent in the ejection timing Okurashi by the predetermined shift amount from the timing, the inkjet head moving in the other direction Form shape by discharging ink from said plurality of nozzles, before Symbol decision patterning step, the first determination pattern and Okurashi by the predetermined shift amount from the reference timing corresponding to the target landing position in ejection timing reference which the ink is formed by ejecting from the plurality of nozzles of the inkjet head moving in one direction, the pre-Symbol second determination pattern, corresponding to the target landing position of the first determination pattern from timing formed by ejecting ink from the plurality of nozzles of the ink-jet head while moving the other direction at a discharge timing Okurashi by the predetermined shift amount.

  In the present invention, a plurality of density measurement patterns and a plurality of determination patterns are formed in a plurality of pattern formation regions of a recording medium, respectively. The plurality of determination patterns are for determining how close the plurality of density measurement patterns are formed to an ideal state where the gap is an ideal value, and both are linear first determination patterns And a second determination pattern.

The discharge timing conditions of the plurality of nozzles when forming the density measurement pattern are made equal between the plurality of pattern formation regions. Further, the discharge timing conditions of the plurality of nozzles when the first and second determination patterns of the determination pattern are respectively formed between the plurality of pattern formation regions are also made equal. Therefore, if the gaps of the plurality of pattern formation regions are all ideal values, the densities of the density measurement patterns are the same in the plurality of pattern formation regions, and the first determination pattern and the first determination pattern of the determination pattern are the same. The positional relationship between the two determination patterns is the same. On the other hand, when the gaps vary between the plurality of pattern formation regions, the density of the density measurement pattern differs between the plurality of pattern formation regions, and the positional relationship between the first determination pattern and the second determination pattern of the determination pattern Will also be different.

  For the discharge adjustment of a plurality of nozzles, it is desirable to use a density measurement pattern formed under conditions where the gap is as close as possible to the ideal state. Therefore, it is necessary to determine which density measurement pattern is formed under conditions close to the ideal state among the plurality of density measurement patterns formed in the plurality of pattern formation regions. It is difficult to determine this from itself. However, since the first and second determination patterns of the determination pattern formed corresponding to the density measurement pattern in each pattern formation region are linear patterns, the positional relationship between the first and second determination patterns It is easy to figure out. Therefore, by grasping the positional relationship between the first and second determination patterns, it is possible to detect which pattern formation region density measurement pattern is formed under the condition that the gap is close to the ideal state.

In the present invention, the discharge timing conditions of the plurality of nozzles when forming the density measurement pattern are made equal between the plurality of pattern formation regions. Further, the discharge timing conditions of the plurality of nozzles when the first and second determination patterns of the determination pattern are respectively formed between the plurality of pattern formation regions are also made equal. If the gaps vary between the plurality of pattern formation regions, the density of the density measurement pattern differs, but the positional relationship between the first determination pattern and the second determination pattern of the determination pattern also deviates. Here, it is difficult to determine which density measurement pattern is formed under conditions close to the ideal state of the gap from the density information of each density measurement pattern. It is easy to grasp the positional relationship between the first and second determination patterns. Therefore, by grasping the positional relationship between the first and second determination patterns, it is possible to detect which pattern formation region density measurement pattern is formed under the condition that the gap is close to the ideal state.

1 is a perspective view of an ink jet printer according to an embodiment. It is a top view which shows roughly the internal structure of an inkjet printer. FIG. 2 is a block diagram schematically illustrating an electrical configuration of a printer. It is process drawing of the discharge adjustment of a nozzle. It is a figure explaining the landing position of the ink in bidirectional printing. FIG. 6 is a diagram illustrating a discharge adjustment pattern formed on a recording sheet. It is a detailed view of a discharge adjustment pattern formed in one pattern formation region. It is process drawing of the discharge adjustment of the nozzle in a change form. It is a figure which shows the correlation of the density | concentration of the determination pattern and the density | concentration of the pattern for density measurement in the modification of FIG. It is a figure which shows the mechanism which forms a waveform on the recording paper in another modification. (A) is a figure explaining the landing position of the ink in unidirectional printing, (b) is a figure explaining discharge of a main droplet and a satellite droplet.

  Next, an embodiment of the present invention will be described. FIG. 1 is a perspective view of the ink jet printer according to the present embodiment. In the installation state when the ink jet printer 1 shown in FIG. 1 is used, the vertical and horizontal directions and the front and rear directions are defined. FIG. 2 is a plan view schematically showing the internal configuration of the ink jet printer.

  As shown in FIG. 1, the inkjet printer 1 includes a printer housing 2 and a cover 3 that is rotatably attached to the printer housing 2. As shown in FIG. 2, the printer housing 2 accommodates a printer unit 4 that records an image or the like on a recording paper 100. Further, the printer housing 2 is provided with a paper discharge unit 11 that opens forward and discharges the recording paper 100 on which an image is recorded by the printer unit 4. Further, an inclined surface 12 is formed on the front side of the cover 3 of the printer housing 2, and an operation panel 13 is disposed on the inclined surface 12. A lid 14 is attached to the right side portion of the paper discharge unit 11 of the printer housing 2. Behind the lid 14 is a holder 9 on which ink cartridges 17 of four colors (black, yellow, cyan, magenta) are respectively mounted.

  The cover 3 is disposed above the printer casing 2 so as to cover internal mechanisms such as the printer unit 4 accommodated in the printer casing 2. The cover 3 is attached to the printer housing 2 so as to be rotatable up and down at the rear end. Accordingly, it is possible to open the inside of the printer housing 2 by rotating the cover 3 upward during paper jam removal or maintenance inspection. Although not described in detail, the cover 3 is provided with a scanner unit 22 including an image scanner that captures an image recorded on a document. That is, the ink jet printer 1 according to the present embodiment is configured as a multifunction machine capable of executing printing, scanning, copying, and the like.

  Next, the printer unit 4 will be described. As shown in FIG. 2, the recording paper 100 stored in the paper feed cassette 23 is supplied to the printer unit 4 one by one from the back by a paper feed mechanism (not shown). The printer unit 4 conveys the carriage 25 that can reciprocate in the left-right direction (scanning direction), the inkjet head 26 mounted on the carriage 25, and the supplied recording paper 100 forward (conveying direction) along a horizontal plane. A transport mechanism 27 and the like are included.

  A platen 28 that supports the recording paper 100 from below is installed in the printer housing 2 in a horizontal posture. Two guide rails 29 and 30 extending in parallel with the scanning direction are provided above the platen 28. A carriage drive motor 32 is connected to the carriage 25 via an endless belt 39. As the belt 39 travels with the driving force of the carriage drive motor 32, the carriage 25 moves in the scanning direction along the two guide rails 29, 30 in a region facing the recording paper 100 on the platen 28.

  The printer housing 2 is provided with a linear encoder 33 having a large number of light transmitting portions (slits) arranged at intervals in the scanning direction. On the other hand, the carriage 25 is provided with a transmissive encoder sensor 34 having a light emitting element and a light receiving element. The encoder sensor 34 outputs a detection signal every time it detects the light transmitting portion of the linear encoder 33, and the printer 1 recognizes the position of the carriage 25 in the scanning direction from the number of outputs.

  The ink jet head 26 is attached to the lower portion of the carriage 25 with a gap between the ink jet head 26 and the platen 28. A plurality of nozzles 31 are formed on the lower surface of the inkjet head 26 (the surface on the opposite side of the paper surface of FIG. 2). The plurality of nozzles 31 are arranged along the transport direction to form four nozzle rows that respectively eject four colors of ink (black, yellow, cyan, magenta). The inkjet head 26 is connected to the holder 9 by a tube (not shown), and the four colors of ink stored in the four ink cartridges 17 are supplied to the inkjet head 26 through the tube.

  The inkjet head 26 includes an actuator (not shown) that applies ejection energy to the ink in the plurality of nozzles 31. The configuration of the actuator is not particularly limited. For example, a piezoelectric actuator that applies a voltage to the piezoelectric layer and uses the strain generated in the piezoelectric layer can be employed. The ink jet head 26 individually ejects ink from the plurality of nozzles 31 by applying ejection energy to the ink in the plurality of nozzles 31 by an actuator.

  The transport mechanism 27 includes two transport rollers 35 and 36 arranged in the front and rear so as to sandwich the platen 28 and the carriage 25. These two transport rollers 35 and 36 are rotationally driven by a transport motor 37 (see FIG. 3), respectively, and transport the recording paper 100 forward (transport direction) between the inkjet head 26 and the platen 28.

  The above-described printer unit 4 ejects ink from the plurality of nozzles 31 of the inkjet head 26 while moving the carriage 25 in the scanning direction (left-right direction in FIG. 1) on the recording paper 100 on the platen 28. When the movement of the carriage 25 in the scanning direction (also referred to as a pass) is completed, the printer unit 4 transports the recording paper 100 by a predetermined amount in the transport direction by the two transport rollers 35 and 36 of the transport mechanism 27. A desired image is printed on the recording paper 100 by alternately repeating the pass of the carriage 25 and the transport operation of the transport mechanism 27.

  Note that the printer 1 of the present embodiment is a printer capable of bidirectional printing. In bidirectional printing, the inkjet head 26 moves in one direction (rightward in FIG. 2) (referred to as forward movement) and moves in the other direction in the scanning direction (leftward in FIG. 2) ( During the backward movement), ink is ejected from each of the plurality of nozzles 31 to print an image on the recording paper 100.

  Next, the electrical configuration of the printer 1 will be described. FIG. 3 is a block diagram schematically showing the electrical configuration of the printer. A control device 40 that controls the overall control of the inkjet printer 1 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a control circuit, and the like. Various operation units of the printer 1 such as the operation panel 13 and the ink jet head 26 are connected to the control device 40. The components of the control device 40 such as the CPU function as the recording control unit 41, the scanner control unit 42, the discharge condition adjustment unit 43, and the like shown in FIG. The control device 40 is connected to a PC 50 that is an external device.

  An output signal of the encoder sensor 34 is input to the recording control unit 41, and the position of the inkjet head 26 in the scanning direction is always grasped. The recording control unit 41 is a printer unit such as a carriage driving motor 32 that drives the carriage 25, an inkjet head 26, a conveyance motor 37 that drives the conveyance rollers 35 and 36, and the like based on data relating to a recording image input from the PC 50. 4 is controlled to record a desired image on the recording paper 100. In addition, the recording control unit 41 controls each unit of the printer 1 such as the above-described ink jet head 26 to record a later-described ejection adjustment pattern for adjusting the ejection conditions of the plurality of nozzles 31 on the recording paper 100. Is possible.

  The scanner control unit 42 controls the operation of the scanner unit 22 when reading an image. The discharge condition adjustment unit 43 adjusts the discharge conditions of the plurality of nozzles 31 of the ink jet head 26 based on information about a discharge adjustment pattern, which will be described later, acquired by the PC 50 and the scanner 51 which are external devices.

  Hereinafter, the discharge adjustment of the nozzle 31 of the inkjet head 26 will be described. The following ejection adjustment is performed individually for four nozzle rows corresponding to four colors (black, yellow, cyan, magenta) of ink.

(Outline of discharge adjustment)
When the discharge characteristics (droplet discharge amount and droplet discharge speed) are the same among the plurality of nozzles 31 in each nozzle row, ink droplets can be discharged from the plurality of nozzles 31 at the same timing. The same volume droplets discharged from the plurality of nozzles 31 can be landed uniformly on the recording paper 100. At this time, the density of the image formed on the recording paper 100 becomes uniform. However, in practice, the difference between the nozzle diameters between the plurality of nozzles 31, the difference in flow path resistance, or the difference in the actuator characteristics that give ejection energy to the ink in the nozzles 31. In general, the discharge characteristics vary. In this case, the size of droplets discharged from the plurality of nozzles 31 and the landing positions of the droplets vary, resulting in uneven density in the recorded image.

Therefore, the discharge conditions of the plurality of nozzles 31 are adjusted through the following three steps so that the density unevenness due to the discharge characteristic variation of the plurality of nozzles 31 is reduced. FIG. 4 is a process chart of nozzle discharge adjustment.
(1) While moving the inkjet head 26 in the scanning direction, each of the plurality of nozzles 31 ejects ink droplets to form a predetermined ejection adjustment pattern on the recording paper 100 (ejection adjustment pattern forming step).
(2) The discharge adjustment pattern is read by the scanner 51, and density information (information on density unevenness) of this pattern is acquired (density information acquisition step).
(3) The discharge conditions of the plurality of nozzles 31 are adjusted based on the density information of the discharge adjustment pattern (adjustment step).

  The “discharge condition” in the above (3) is a condition that affects the size and landing position deviation of the droplets discharged from each nozzle 31, and specifically, the discharge timing described below. Conditions and discharge energy conditions.

  The ejection timing condition refers to how much the actual ejection timing is shifted with respect to a reference timing predetermined with respect to the predetermined position when ink is landed on the predetermined landing target position of the recording paper 100. This is the amount of time deviation. More specifically, the encoder sensor 34 shown in FIG. 2 detects the amount of time delay until the ink is ejected after the light transmission portion (slit) of the linear encoder corresponding to the predetermined landing target position is detected. Discharge delay amount). When the landing position of a droplet discharged from a certain nozzle 31 deviates from the landing position of another nozzle 31, the landing position is adjusted by adjusting the discharge timing condition of the nozzle 31 whose landing position is shifted. It is possible to align the positions.

  The ejection energy condition is the magnitude of ejection energy given to the ink in each nozzle 31 by the actuator of the inkjet head 26. In the case of the piezoelectric actuator exemplified above, this is the magnitude of the drive voltage applied to the piezoelectric layer for each nozzle 31. Even if the discharge energy conditions are the same among the plurality of nozzles 31, if the degree of energy loss is different due to a difference in flow path resistance or the like, the size and liquid of the liquid droplets discharged from the plurality of nozzles 31, respectively. Drop speed is different. Therefore, in such a case, it is possible to align the droplet size and the droplet velocity (that is, the droplet landing position) by adjusting the discharge energy condition.

(Discharge adjustment pattern formation step)
First, a step of forming a discharge adjustment pattern on the recording paper 100 will be described. Here, in order to suppress density unevenness of an image recorded by bidirectional printing, the discharge adjustment pattern is also formed by bidirectional printing. By the way, the gap with the inkjet head 26 is not necessarily constant over the entire area of the recording paper 100, and the gap is an ideal value (assumed value) depending on the location due to floating, warping, or undulation in the recording paper 100. May be different.

  FIG. 5 is a diagram for explaining ink landing positions in bidirectional printing. As shown in FIG. 5, when the gap is an ideal value (Ga), it is assumed that both ink droplets ejected in both forward and backward movements land on the position A. However, when the gap is smaller than the ideal value (Ga) (Gb), the ink droplets ejected in both directions land at positions B1 and B2, which are closer to the ejection position than the position A, respectively. When the gap is larger than the ideal value (Ga) (Gc), the ink droplets ejected in both directions land at positions C1 and C2 farther from the ejection position than the position A, respectively. Therefore, ideally, the ink ejected during the forward movement and the ink ejected during the backward movement should each land on the ideal position A. If the gap is small, they land on the positions B1 and B2, respectively. If it is larger, it will land at positions C1 and C2, respectively. As described above, in bidirectional printing, not only variations in ejection characteristics among the plurality of nozzles 31 but also deviations in the bidirectional landing position occur due to gaps.

  If the discharge adjustment pattern is formed without considering the above-mentioned gap problem, is the density unevenness existing in the discharge adjustment pattern due to variations in discharge characteristics among the plurality of nozzles 31 or due to the gap? I don't know. Therefore, when performing ejection adjustment in bidirectional printing, it is necessary to eliminate as much as possible the impact of the landing position deviation due to the gap.

  FIG. 6 is a diagram showing a discharge adjustment pattern formed on the recording paper. As shown in FIG. 6, a plurality of ejection adjustment patterns 61 are formed in a plurality of areas (pattern formation area 60) of the recording paper 100. The plurality of pattern formation regions 60 are regions that are regularly arranged in the scanning direction and the conveyance direction, respectively. That is, a plurality of ejection adjustment patterns 61 arranged in a matrix in the scanning direction and the conveyance direction are formed on the recording paper 100.

  FIG. 7 is a detailed view of the discharge adjustment pattern formed in one pattern formation region. As shown in FIG. 7, the discharge adjustment pattern 61 of one pattern formation region 60 includes a density measurement pattern 62 and two determination patterns 63 arranged so as to sandwich the density measurement pattern 62 in the scanning direction. Become. The following discharge adjustment pattern 61 is formed by the recording control unit 41 of the control device 40 controlling the printer unit 4.

  The density measurement pattern 62 is a fill pattern composed of a first density measurement pattern 62a and a second density measurement pattern 62b. The first density measurement pattern 62a is formed by ejecting ink from a plurality of nozzles 31 constituting one nozzle row 38 during the forward movement (FWD) of the inkjet head 26, and is formed at predetermined intervals in the scanning direction (details). Is composed of a large number of dot rows (indicated by thin hatching) arranged in an interval of twice the nozzle arrangement pitch of the nozzle row 38. The second density measurement pattern 62b is composed of a large number of dot rows (indicated by dark hatching) formed by ejecting ink from the plurality of nozzles 31 in the same manner when the inkjet head 26 is moved backward (RVS). The dot row of the second density measurement pattern 62b is formed so as to be positioned between the two dot rows of the first density measurement pattern 62a. It is preferable to form a plurality of density measurement patterns 62 so as to have a width of about 10 to 20 mm in the scanning direction. A plurality of density data can be acquired for each nozzle 31 by providing a certain width (number). It is desirable that the density data of a certain nozzle 31 in each pattern formation region 60 is obtained by averaging a plurality of density data.

  As shown in FIG. 7, dummy patterns 64, which are the same fill patterns as the density measurement pattern 62, are formed on the upstream side and the downstream side in the conveyance direction of the density measurement pattern 62. The dummy pattern 64 on the upstream side in the transport direction is formed by another path before the density measurement pattern 62 is formed, and the downstream dummy pattern 64 is formed by another path after the density measurement pattern 62 is formed. . When the upstream and downstream edges (portions formed by both ends of the nozzle row 38) of the density measurement pattern 62 are adjacent to a white area where no pattern is formed, the density When the measurement pattern 62 is read by the scanner 51, a reading error increases due to reflection of the white recording paper 100 or the like. Therefore, the reading error can be suppressed by forming the dummy pattern 64 so as to be adjacent to the density measurement pattern 62 as described above.

  The determination pattern 63 includes a first determination pattern 63a and a second determination pattern 63b. The first determination pattern 63a is a linear pattern (dot row) formed by discharging ink from a plurality of nozzles 31 constituting one nozzle row 38 when the inkjet head 26 moves forward, and extending in the transport direction. is there. The second determination pattern 63b is a linear pattern (dot row) that is formed by ejecting ink from the plurality of nozzles 31 when the inkjet head 26 moves backward, and extending in the transport direction. The second determination pattern 63b is formed to overlap the first determination pattern 63a in the scanning direction. The determination pattern 63 is formed using the same nozzle 31 (with the same color) as the density measurement pattern 62 in the scanning direction. The determination pattern 63 is formed away from the density measurement pattern 62 by a predetermined distance in the scanning direction. By forming the determination pattern 63 away from the density measurement pattern 62 in this way, it is difficult to be affected by the density measurement pattern 62 at the time of reading, and it is desirable that the distance is about 3 to 5 mm. Since the determination pattern 63 determines landing deviation as will be described later, it may be at least one linear pattern as shown in FIG. 7, but there may be a plurality of determination patterns.

  In the formation of the density measurement pattern, the first density formed in both directions when the gap between the inkjet head 26 and the recording paper 100 is in a predetermined ideal value (referred to as an ideal state). The measurement pattern 62a and the second density measurement pattern 62b are set to have a predetermined positional relationship. FIG. 7A shows a discharge adjustment pattern when the gap is in an ideal state. Specifically, as shown in FIG. 7A, when the gap is in an ideal state, the dot of the second density measurement pattern 62b is positioned exactly in the middle of the two dots of the first density measurement pattern 62a. Thus, the discharge conditions are set. At this time, the density measurement pattern 62 is a filled pattern having a uniform dot arrangement (density) in which a large number of dots formed in both directions are arranged at equal intervals in the scanning direction and the conveyance direction. “Dots are uniformly arranged” means that the distance between dots is equal between a dot and surrounding dots adjacent to the dot. It should be noted that the dots are uniformly arranged in the ideal state of the gap only when the discharge characteristics of the plurality of nozzles 31 are all equal, and when the discharge characteristics vary among the plurality of nozzles 31, Of course, the landing positions of some of the dots will shift. In other words, in the ideal state of the gap, the dots are uniformly arranged when the discharge characteristics of the plurality of nozzles 31 are all equal. Conversely, the discharge characteristics of the plurality of nozzles 31 vary. It becomes easy to grasp the density unevenness in the case. That is, “dots are uniformly arranged” means that the discharge characteristics of the plurality of nozzles 31 are assumed to be equal, and the discharge characteristics of the plurality of nozzles 31 before discharge adjustment are the same. Even when the pattern is formed in a dispersed state, it does not mean that the dots are arranged uniformly.

  In the formation of the determination pattern 63, when the gap is in an ideal state, the first determination pattern 63a and the second determination pattern 63b are in a predetermined positional relationship. Specifically, as shown in FIG. 7A, when the gap is in an ideal state, the ejection conditions are set so that the linear first determination pattern 63a and the second determination pattern 63b completely overlap. To do.

  Further, the discharge conditions of the plurality of nozzles 31 are made equal between the plurality of pattern formation regions 60. Therefore, when the gap is an ideal value and constant throughout the recording paper 100, in each of the plurality of pattern formation regions 60, as shown in FIG. The filled pattern is arranged, and the determination pattern 63 is a state in which the linear first determination pattern 63a and the second determination pattern 63b are completely overlapped.

  However, when gaps vary in a plurality of pattern formation regions 60, landing position deviations caused by the gaps occur in the density measurement pattern 62 and the determination pattern 63 in the pattern formation regions 60 where the gaps are different from the ideal values. FIG. 7B shows a discharge adjustment pattern when the gap is not in an ideal state. When the gap deviates from the ideal value, as shown in FIG. 7B, in the density measurement pattern 62, the positional relationship in the scanning direction between the first density measurement pattern 62a and the second density measurement pattern 62b is shifted, and a large number of Deviation from a state where dots are evenly arranged. At this time, compared with FIG. 7A, the density of the density measurement pattern 62 is low because the area where the ink actually landed is small.

  In the determination pattern 63, as shown in FIG. 7B, the positional relationship in the scanning direction between the linear first determination pattern 63a and the second determination pattern 63b is shifted. At this time, the thickness of the determination pattern 63 is larger than that in FIG. 7A in which the first determination pattern 63a and the second determination pattern 63b are completely overlapped. As will be described later, the density measurement pattern 62 is in the ideal state of the gap based on the degree of displacement in the scanning direction of the first determination pattern 63a and the second determination pattern 63b (thickness of the determination pattern 63). It can be ascertained whether it was formed under nearly the same conditions.

(Concentration information acquisition step)
As shown in FIG. 4, the density information acquisition step includes a reading step and a determination step. In the reading step, the plurality of ejection adjustment patterns 61 formed on the recording paper 100 are read by the scanner 51 connected to the PC 50. The pattern information read by the scanner 51 is sent to the PC 50. For each of the plurality of ejection adjustment patterns 61, the PC 50 acquires the density information of the density measurement pattern 62 portion and the determination pattern 63 portion formed by each nozzle 31 in association with each other. For example, in FIG. 7A, with respect to the nozzle 31 positioned third from the top in the drawing, the density information of the density measurement pattern 62 surrounded by the thick frame X formed by this nozzle 31 and the thick frame Y Are obtained in association with the density information of the determination pattern 63 surrounded by. In addition, it can be recognized as follows, for example, to which nozzle 31 the density information of a part of the density measurement pattern 62 and the determination pattern 63 corresponds. First, in the previous pattern formation step, a reference pattern is formed in each of the plurality of pattern formation regions 60 using a predetermined nozzle 31 in addition to the discharge adjustment pattern 61. In addition, in this density information acquisition step, based on how far the density measurement pattern 62 and the determination pattern 63 are apart from the reference pattern, the nozzle 31 that formed the part is specified.

  In the determination step, it is determined which density measurement pattern 62 in which pattern formation region 60 is formed under the condition where the gap is closest to the ideal state. However, the degree of positional deviation between the two density measurement patterns 62a and 62b is grasped from the density information of the density measurement pattern 62, which is a filled pattern, and which density measurement pattern 62 is formed under the condition closest to the ideal state. It is quite difficult to determine whether it is. Therefore, this is determined from the positional relationship in the scanning direction between the first determination pattern 63a and the second determination pattern 63b of the determination pattern 63. Since the two determination patterns 63a and 63b are linear patterns, the amount of positional deviation in the scanning direction of the first determination pattern 63a and the second determination pattern 63b is grasped unlike the two density measurement patterns 62a and 62b. It's pretty easy.

  Specifically, for each nozzle 31, the PC 50 has the lowest density in the portion of the determination pattern 63 formed by the nozzle 31 among the plurality of pattern formation regions 60 (the positional deviation between the two determination patterns 63 a and 63 b). The pattern formation region 60 having the smallest amount and the smallest thickness of the determination pattern 63 is specified as a region where the gap is closest to the ideal value. Then, the density information of the density measurement pattern 62 in the specified pattern formation region 60 is used as information used for the discharge adjustment of the nozzle 31. Further, the above determination is performed for all of the plurality of nozzles 31. As described above, it is possible to acquire density information of the density measurement pattern 62 in which the gap is formed under a condition close to the ideal state for each of the plurality of nozzles 31.

  In the present embodiment, the determination pattern 63 is formed so that the first determination pattern 63a and the second determination pattern 63b completely overlap when the gap is in an ideal state. When the first determination pattern 63a and the second determination pattern 63b are completely overlapped, the thickness of the determination pattern 63 is the thinnest. Therefore, by comparing the thicknesses of the plurality of determination patterns 63 respectively formed in the plurality of pattern formation regions 60, it is determined which density measurement pattern 62 is formed under the condition closest to the ideal state for each nozzle 31. Easy to judge.

  The above determination is based on the premise that the gap is almost the same between the formation region of the density measurement pattern 62 and the formation region of the determination pattern 63 in each pattern formation region 60. Therefore, it is preferable to form the density measurement pattern 62 and the determination pattern 63 in one pattern formation region 60 as close as possible. In the present embodiment, two determination patterns 63 are formed on both sides of the density measurement pattern 62 in the scanning direction. As a result, when the gaps are not equal on both sides of the density measurement pattern 62, the state can be grasped by the determination patterns 63 on both sides. For example, even if the density of one judgment pattern 63 is low, if the density of the other judgment pattern 63 is quite high, the gap is greatly different on both sides of the density measurement pattern 62 in this pattern formation region 60. Therefore, the density information of the density measurement pattern 62 is not used for the discharge adjustment. Note that it is not essential to form the determination patterns 63 on both sides of the density measurement pattern 62, and the determination patterns 63 may be formed only on either the left or right side.

  In the above description, the PC 50 connected to the scanner 51 specifies the density measurement pattern 62 formed under the conditions closest to the ideal state of the gap from the plurality of ejection adjustment patterns 61 read by the scanner 51. Note that the above determination may be performed by the control device 40 of the printer 1 instead of the PC 50.

(Adjustment step)
In the adjustment step, the discharge condition adjustment unit 43 of the control device 40 performs plural printing when performing bidirectional printing based on the density information of the density measurement pattern 62 for each of the plurality of nozzles 31 sent from the PC 50. The discharge conditions of the nozzles 31 are respectively adjusted. For example, density unevenness can be suppressed by adjusting the discharge energy conditions of the plurality of nozzles 31 so that the density information of the density measurement pattern 62 has the lowest density information. Since the discharge adjustment of the nozzle 31 based on the density information is already a well-known technique, further detailed description is omitted.

  As described above, in the present embodiment, the discharge conditions of the plurality of nozzles 31 when forming the density measurement pattern 62 are made equal between the plurality of pattern formation regions 60. In addition, the discharge conditions of the plurality of nozzles 31 when the first determination pattern 63a and the second determination pattern 63b of the determination pattern 63 are respectively formed between the plurality of pattern formation regions 60 are also made equal. Therefore, if the gaps of the plurality of pattern formation regions 60 are all ideal values, the density of the density measurement pattern 62 is the same in the plurality of pattern formation regions 60, and the first of the determination patterns 63 The positional relationship between the determination pattern 63a and the second determination pattern 63b (the thickness of the determination pattern 63) is also the same. On the other hand, when gaps vary between the plurality of pattern formation regions 60, the density of the density measurement pattern 62 differs between the plurality of pattern formation regions 60, and the first determination pattern 63 a and the second determination pattern 63 of the determination pattern 63 are different. The positional relationship of the determination pattern 63b is also different.

  For the discharge adjustment of the plurality of nozzles 31, it is desirable to use a density measurement pattern 62 formed under conditions as close as possible to the ideal state of the gap. In the present embodiment, the first and second determination patterns 63a and 63b of the determination pattern 63 formed corresponding to the density measurement pattern 62 in each pattern formation region 60 are linear patterns. It is easy to grasp the positional relationship between the first and second determination patterns 63a and 63b. Therefore, by grasping the positional relationship between the first and second determination patterns 63a and 63b, it is detected which pattern forming region 60 has the density measurement pattern 62 formed under conditions close to the ideal state of the gap. can do.

  As shown in FIG. 6, in this embodiment, a plurality of pattern formation regions 60 are arranged in the scanning direction and the transport direction. For this reason, it is possible to deal with both fluctuations in the scanning direction of the gap and fluctuations in the transport direction. For example, when a plurality of pattern formation regions 60 are arranged only in the scanning direction and the gap varies greatly in the transport direction, the ejection adjustment pattern 61 is formed only in a place where the gap is extremely large or small. It is possible that it will be done. That is, the ejection adjustment pattern 61 may not be formed at a position where the gap is an ideal value. In this respect, if the plurality of pattern formation regions 60 are also arranged in the transport direction, the above-described problem is unlikely to occur.

  Next, modified embodiments in which various modifications are made to the embodiment will be described. However, components having the same configuration as in the above embodiment are given the same reference numerals and description thereof is omitted as appropriate.

1] In the above-described embodiment, for each of the plurality of nozzles 31, it is individually determined which pattern formation region 60 the density information of the density measurement pattern 62 is to be adopted. However, if the gap hardly fluctuates in the nozzle arrangement direction (transport direction in the above embodiment) and the conditions regarding the gap are substantially the same for all the nozzles 31 in one nozzle row 38, the above-mentioned is true for all the nozzles 31. There is no need to make a determination. For example, only for one nozzle 31, the density measurement pattern 62 formed in a state closest to the ideal state of the gap is specified, and all the density measurement patterns 62 are specified based on the density information of the specified density measurement pattern 62. The discharge adjustment of the nozzle 31 may be performed.

2] In the embodiment, in the density information acquisition step, the density measurement pattern formed under the conditions close to the ideal state of the gap from among the plurality of density measurement patterns 62 respectively formed in the plurality of pattern formation regions 60. 62 was specified (selected). However, in this case, the selected density measurement pattern 62 may be closest to the ideal state among the plurality of density measurement patterns 62, but the viewpoint of improving the accuracy of the discharge adjustment in the subsequent adjustment step. Then, it is desirable to obtain pattern density information when formed under conditions that are as close as possible to the ideal state of the gap. Of course, if a large number of density measurement patterns 62 are formed, the accuracy is improved, but there is a limit to this. Therefore, as described below, in the density information acquisition step, the density of the density measurement pattern 62 formed in the ideal state of the gap may be estimated using the information of the plurality of ejection adjustment patterns 61 read by the scanner. .

  FIG. 8 is a process chart of nozzle discharge adjustment in this modified embodiment. In FIG. 8, the discharge adjustment pattern forming step is a step of forming the discharge adjustment pattern 61 of FIGS. 6 and 7 of the above-described embodiment and is the same as that of the above-described embodiment. The density information acquisition step includes a reading step, a correlation acquisition step, and an estimation step.

  In the reading step, the plurality of ejection adjustment patterns 61 formed on the recording paper 100 are read by the scanner 51 connected to the PC 50 as in the above embodiment. Then, the PC 50 acquires, for each of the plurality of ejection adjustment patterns 61, the density information of the density measurement pattern 62 portion and the determination pattern 63 portion formed by each nozzle 31 in association with each other.

  Next, in the correlation acquisition step, the correlation between the density of the plurality of determination patterns 63 obtained for each nozzle 31 and the density of the corresponding plurality of density measurement patterns 62 is obtained. FIG. 9 shows an example of the correlation between the density of the determination pattern and the density of the density measurement pattern. As shown in FIG. 9, with respect to each nozzle 31, a plurality of pieces of density information are plotted using the density of the determination pattern 63 on the horizontal axis and the density of the density measurement pattern 62 on the vertical axis, and the least square method or the like is used. Interpolate with an appropriate interpolation function. Further, the correlation as shown in FIG. 9 is acquired for each of the plurality of nozzles 31.

In the estimation step, the density of the density measurement pattern 62 when the gap is formed in an ideal state is estimated using the correlation between the density of the determination pattern 63 and the density measurement pattern 62 in FIG. When the density measurement pattern 62 is formed under the condition that the gap is an ideal value, the first determination pattern 63a and the second determination pattern 63b of the determination pattern 63 are completely overlapped. The concentration (thickness) can be predicted in advance. Therefore, as shown in FIG. 9, when the determination pattern 63 has an ideal density, the density of the density measurement pattern 62 is obtained, and this density is estimated as the density formed in the ideal state. Then, this density estimation is performed for each of the plurality of nozzles 31 using the respective correlations.
Similar to the above-described embodiment, the correlation acquisition step and the estimation step described above may be executed by the PC 50 connected to the scanner 51, or may be executed by the control device 40 of the printer 1.

  Next, in the adjustment step shown in FIG. 9, the discharge conditions are adjusted for each of the plurality of nozzles 31 using the density information of the density measurement pattern 62 estimated in the estimation step. In this modification, in order to estimate the density information of the density measurement pattern 62 when formed in the ideal state of the gap, the influence of the gap variation is almost completely eliminated using this estimated density information. Accurate discharge adjustment is possible.

3] In the above embodiment, the determination pattern 63 is formed so that the first determination pattern 63a and the second determination pattern 63b completely overlap in the ideal state of the gap, but the first determination pattern 63a and the second determination pattern are formed. The pattern 63b may be arranged at a predetermined distance in the scanning direction. In this case, in the pattern formation region where the gap is different from the ideal value, the first determination pattern 63a and the second determination pattern 63b are shifted in the scanning direction in accordance with the amount of deviation from the ideal value of the gap. The separation distance changes. Accordingly, by detecting the distance in the scanning direction between the first determination pattern 63a and the second determination pattern 63b in each of the plurality of pattern formation regions 60, the density measurement pattern 62 in which pattern formation region 60 is the ideal gap. It can be determined whether the film is formed under the condition closest to the state.

4] The discharge adjustment pattern 61 of the present invention is not necessarily formed by bidirectional printing, and may be formed by unidirectional printing. That is, the density measurement pattern 62 may be formed by one-way printing or two-way printing depending on whether the discharge adjustment is performed when performing one-way printing or the discharge adjustment when performing two-way printing. For example, the density measurement pattern 62 may be formed by one-way printing. That is, when the ink jet head 26 moves in one direction in the scanning direction, a large number of dots are uniformly arranged by landing the ink ejected from the plurality of nozzles 31 constituting one nozzle row 38 without any gap. Form a fill pattern.

  When the density measurement pattern 62 is formed by unidirectional printing, the linear first and second determination patterns 63a and 63b of the determination pattern 63 are also formed by unidirectional printing. In order to completely overlap the first determination pattern 63a and the second determination pattern 63b as in the above-described embodiment by this unidirectional printing, the first determination pattern 63a and the second determination pattern 63b are formed. In this case, the discharge energy condition may be different and the droplet discharge speed may be different from each other. As a result, two droplets discharged from one nozzle 31 at different timings can be landed on the same position on the recording paper 100 due to the difference in discharge speed between the two droplets.

  An example of forming such an ejection adjustment pattern is given. First, in the first pass of the inkjet head 26, all the density measurement patterns 62 are formed (one-way printing), and the first determination pattern 63a of the determination patterns 63 is formed. Next, in the second pass of the inkjet head 26 (the first pass and the movement direction of the inkjet head 26 are the same: one-way printing), the first determination pattern 63a is formed and the ejection conditions (ejection timing condition, ejection energy) The second determination pattern 63b is formed so as to overlap the first determination pattern 63a under different conditions.

4] In the above-described embodiment, one determination pattern 63 has one first determination pattern 63a and one second determination pattern 63b. However, the first determination pattern 63a and the second determination pattern 63b are You may have multiple each. For example, with only one first determination pattern 63a and one second determination pattern 63b, the thickness of the line is too thin, and the positional relationship between the first determination pattern 63a and the second determination pattern 63b is the thickness (density). ), It is effective to form a plurality of first determination patterns 63a and a plurality of second determination patterns 63b.

5] When the printer 1 has a scanner function as in the above embodiment, the discharge adjustment pattern 61 printed on the recording paper 100 by the printer 1 is read by the scanner unit 22 of the printer 1 and further acquired by the scanner unit 22. The information may be processed by the control device 40 of the printer 1. In this case, printing of the discharge adjustment pattern 61 onto the recording paper 100, reading of the discharge adjustment pattern 61, and adjustment of the discharge conditions of the plurality of nozzles 31 can all be performed by one printer 1.

6] In order to prevent warping or the like of the recording paper 100 during conveyance, there is a technique for intentionally forming a wave shape on the recording paper 100 in which crests and troughs are alternately arranged in the scanning direction. For example, as shown in FIG. 10, a plate 71 having a plurality of ribs 70 a is arranged below the recording paper 100 at a position upstream of the platen 28 (see FIG. 2) in the transport direction. A plurality of claw portions 71 are arranged on the top. A plurality of ribs 70a and a plurality of claw portions 71 are alternately arranged in the scanning direction. The recording paper 100 placed on the plurality of ribs 70 a of the plate is suppressed from above by the plurality of claw portions 71. As a result, the recording paper 100 has a crest 101 at the position of the rib 70a, a trough 102 at the position of the claw 71, and a wave shape in which the crest 101 and the trough 102 are alternately arranged in the scanning direction. . In this embodiment, the gap between the inkjet head 26 and the recording paper 100 varies greatly in the scanning direction. Therefore, in the printer 1 having the above configuration, it is very significant to specify the density measurement pattern 62 formed under the condition close to the ideal state of the gap by applying the present invention.

  As shown in FIG. 10, when a wave shape is intentionally formed on the recording paper 100, the crest portion 101 a of the crest portion 101 of the recording paper 100 (the portion where the rib 70 a is in contact with the trough portion 102). It is preferable to form the discharge adjustment pattern 61 in a region between the portion 102a (the portion in contact with the claw portion 71), and the gap between the peak portion 101a and the inkjet head 26 takes a minimum value. Therefore, the gap has a maximum value at the valley bottom portion 102a of the valley portion 102. Therefore, there is a high possibility that the location where the gap is an ideal value exists between the peak portion 101a and the valley bottom portion 102a. By forming a discharge adjustment pattern between the portion 101a and the valley bottom portion 102a, the density measurement pattern 62 is formed at a position where the gap becomes an ideal value. It becomes easier.

7] The pattern formation area 60 for forming the ejection adjustment pattern 61 of the recording paper 100 is not limited to the form aligned in the scanning direction and the carrying direction as shown in FIG. For example, the pattern formation regions 60 may be arranged only in the scanning direction, or the pattern formation regions 60 may be arranged only in the transport direction. Furthermore, the pattern formation regions 60 may be arranged in directions that intersect the scanning direction and the conveyance direction (for example, the diagonal direction of the recording paper).

DESCRIPTION OF SYMBOLS 1 Inkjet printer 26 Inkjet head 31 Nozzle 40 Control apparatus 41 Recording control part 43 Ejection condition adjustment part 60 Pattern formation area 61 Ejection adjustment pattern 62 Density measurement pattern 63 Judgment pattern 63a First judgment pattern 63b Second judgment pattern 70a Rib 71 Nail Part 100 Recording paper 101 Mountain portion 101a Mountain top portion 102 Valley portion 102a Valley bottom portion

Claims (8)

A columnar pattern perpendicular to the scanning direction is formed on the recording medium by an inkjet head that ejects ink from a plurality of nozzles while moving along one direction in the scanning direction and the other direction opposite to the one direction. A method,
By ejecting ink from the plurality of nozzles of the inkjet head, a first density measurement pattern having a large number of the first row-shaped patterns and a second density measurement pattern having a large number of the second row-shaped patterns A density measurement pattern forming step in which a density measurement pattern is formed in each of a plurality of pattern formation regions on the recording medium; and
Wherein by ejecting ink from the same plurality of nozzles and when forming the density measuring pattern, the determination pattern including a first determination pattern and a second determination pattern having one said column-like pattern, the density measurement A determination pattern forming step for forming each of the plurality of pattern formation regions in which the patterns for use are formed,
In the density measurement pattern forming step,
The inkjet moving in the one direction at an ejection timing obtained by delaying the first density measurement pattern by a predetermined shift amount from a reference timing corresponding to each landing target position of the multiple first patterns. ink formed by Rukoto ejected from the plurality of nozzles of the head,
The second density measurement pattern is ejected by delaying the predetermined deviation amount from the reference timing corresponding to the landing target position of the second pattern located between the adjacent first patterns in the other direction. form shape by discharging ink from said plurality of nozzles of the inkjet head moving in,
Prior Symbol decision patterning step,
The first determination pattern, the discharge timing from the timing of the reference was Okurashi by the predetermined shift amount corresponding to the target landing position, ink is ejected from the plurality of nozzles of the inkjet head moving in the one direction It was formed by causing,
The pre-Symbol second determination pattern, the plurality of the ink jet head during movement from said first determination pattern corresponding reference timing to target landing position of the other direction at the predetermined shift amount by the ejection timing Okurashi A method for forming an ejection adjustment pattern, which is formed by ejecting ink from a nozzle. The recording medium has a wave shape in which crests and troughs are alternately arranged in the scanning direction,
  2. The discharge adjustment pattern forming method according to claim 1, wherein an area between a peak portion of the peak portion and a valley bottom portion of the valley portion in the recording medium is set as the pattern formation region. 3. The discharge adjustment pattern forming method according to claim 1, wherein in the determination pattern forming step, the two determination patterns are formed so as to sandwich one density measurement pattern in the scanning direction. The discharge adjustment pattern forming method according to claim 1 , wherein the plurality of pattern forming regions are arranged in the scanning direction. 5. The discharge adjustment pattern forming method according to claim 1 , wherein the plurality of pattern formation regions are arranged in a transport direction of the recording medium that intersects the scanning direction. 6. In each pattern formation region, a dummy pattern is formed adjacent to the density measurement pattern in a direction orthogonal to the scanning direction,
The method according to claim 1 , wherein the determination pattern is formed at a predetermined distance from the density measurement pattern in the scanning direction. A method for performing discharge adjustment of the plurality of nozzles of the inkjet head using a discharge adjustment pattern formed on a recording medium by the discharge adjustment pattern forming method according to claim 1 ,
A reading step of reading the density measurement pattern and the determination pattern for each of the plurality of pattern formation regions of the recording medium;
Of the plurality of the determination patterns read in the reading step, the information on the positional deviation amount of the first determination pattern and the second determination pattern in the scanning direction is used as the recording medium among the plurality of density measurement patterns. A determination step of determining a density measurement pattern formed under a condition closest to an ideal state in which a gap with the inkjet head is a predetermined ideal value ;
An adjustment step of adjusting discharge conditions for each of the plurality of nozzles using density information of the density measurement pattern determined in the determination step;
An ejection adjustment method for an ink jet head, comprising: A method for adjusting an ejection timing condition of the plurality of nozzles of an inkjet head that ejects ink from a plurality of nozzles while moving along one direction in a scanning direction and another direction opposite to the one direction,
By ejecting ink from the plurality of nozzles of the inkjet head to a plurality of pattern formation regions of a recording medium, a first density measurement pattern having a number of the first columnar patterns and the second columnar second patterns. A density measurement pattern forming step for forming density measurement patterns each including a second density measurement pattern having a large number of patterns;
A first determination pattern having one of the row-like patterns by ejecting ink from the plurality of nozzles, which is the same as when forming the density measurement pattern , in the plurality of pattern formation regions of the recording medium; A determination pattern forming step of forming determination patterns each including a second determination pattern ;
A reading step of reading the density measurement pattern and the determination pattern for each of the plurality of pattern formation regions of the recording medium;
Information on the amount of shift in the scanning direction of the first determination pattern and the second determination pattern of the plurality of determination patterns read in the reading step, and a plurality of density measurement patterns respectively corresponding to the plurality of determination patterns A correlation acquisition step for obtaining a correlation between the positional deviation information of the determination pattern and the density information using the density information of
An ideal state in which the gap between the recording medium and the inkjet head is a predetermined ideal value by using the correlation between the positional deviation information of the determination pattern acquired in the correlation acquisition step and the density information. An estimation step for estimating the density information of the pattern for density measurement when formed by:
Using the density information estimated in the estimation step, and adjusting the discharge timing condition for each of the plurality of nozzles, and
In the density measurement pattern forming step,
The inkjet moving in the one direction at an ejection timing obtained by delaying the first density measurement pattern by a predetermined shift amount from a reference timing corresponding to each landing target position of the multiple first patterns. ink formed by Rukoto ejected from the plurality of nozzles of the head,
The second density measurement pattern is ejected by delaying the predetermined deviation amount from the reference timing corresponding to the landing target position of the second pattern located between the adjacent first patterns in the other direction. form shape by discharging ink from said plurality of nozzles of the inkjet head moving in,
In the determination pattern forming step,
The first determination pattern, the discharge timing from the timing of the reference was Okurashi by the predetermined shift amount corresponding to the target landing position, ink is ejected from the plurality of nozzles of the inkjet head moving in the one direction It was formed by causing,
The pre-Symbol second determination pattern, the plurality of the ink jet head during movement from said first determination pattern corresponding reference timing to target landing position of the other direction at the predetermined shift amount by the ejection timing Okurashi An ink jet head discharge adjustment method, wherein the ink jet head is formed by discharging ink from a nozzle.

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