JPWO2016039185A1 - Droplet ejection apparatus and ejection head adjustment method - Google Patents

Abstract

Provided are a droplet discharge device and a discharge head adjustment method for suppressing deterioration in image quality when a droplet discharge failure occurs. A droplet discharge device has two or more discharge heads, a droplet discharge means for landing droplets on a discharge target medium that is relatively moved in a predetermined movement direction, and a landing pattern for obtaining the arrangement direction of the discharge head A discharge control means for discharging droplets, a landing pattern detection means, an arrangement direction correction amount calculation means based on the detection data, and an arrangement direction adjustment means. Discharge nozzles are arranged at a predetermined resolution in the orthogonal width direction, and the discharge heads are arranged so as to overlap each other in the movement direction in a relative positional relationship that increases the resolution, and the landing pattern is formed downstream of the movement direction. The correction amount is calculated so that the arrangement direction of the second ejection head is closer to the ideal direction than the first ejection head formed only by the ejection nozzles of the second ejection head and upstream in the movement direction.

Description

  The present invention relates to a droplet discharge device and a method for adjusting a discharge head.

  2. Description of the Related Art Conventionally, there is a droplet discharge device that forms an image, a film, or a layer on a discharge medium by arranging a plurality of nozzles and discharging droplets from the nozzles. As such a droplet discharge device, for example, there is an ink jet recording device that forms an image by discharging ink droplets of respective colors.

  In recent years, there has been a demand to narrow the nozzle arrangement interval in order to increase the accuracy of the output pattern. In addition, the nozzles are arranged over the entire width of the medium to be discharged in the width direction perpendicular to the conveyance direction of the medium to be discharged, and only the medium to be discharged is moved, so that the liquid droplets are quickly formed on the medium to be discharged. There is a one-pass type ink jet recording apparatus for landing. In these cases, due to technical limitations and cost problems, instead of arranging all the nozzles in a row in the width direction, the nozzles are divided into a plurality of nozzle rows in the transport direction. Are arranged in a staggered pattern, or the nozzles of each nozzle row are alternately arranged in the width direction to narrow the arrangement interval as a whole. At this time, when a plurality of nozzle rows are formed by being divided into a plurality of ejection heads and attached to each of them, a relative positional deviation or rotational deviation slightly occurs due to the accuracy of the attachment, and it is completely uniform. There is a problem of not being an array.

  On the other hand, Patent Document 1 discloses a technique for detecting a relative inclination between a plurality of inkjet heads. Patent Document 2 discloses a technique for detecting a relative displacement between a plurality of inkjet heads. Patent Document 3 discloses a technique for detecting the inclination of the inkjet head in which the ink discharge nozzles are arranged in the width direction perpendicular to the conveyance direction of the recording medium with respect to the conveyance direction.

  In addition, in a droplet discharge device, when a droplet is discharged at a timing close to a nozzle at a position close to the size of a droplet discharged from the nozzle and landing on the discharge medium, the droplet is discharged on the discharge medium. When both droplets partially overlap, the droplets are pulled together by surface tension before the droplets dry and solidify on the medium to be ejected (liquid gathering), and unintended landing deviation may occur. There is a problem. On the other hand, Patent Document 4 describes a technique of measuring the degree of blur in advance and correcting a halftone processing matrix so as to suppress the deviation of the landing.

  On the other hand, in a droplet discharge device, a droplet discharge failure often occurs due to nozzle clogging or failure. When such a discharge failure occurs, there is a technique for complementing by discharging droplets from a plurality of nozzles in the vicinity of the nozzle in which the discharge failure has occurred. At this time, it is known that liquid drop is generated between the discharged droplets instead of the integration and the deterioration caused by the landing shape of the droplet due to the complementary operation can be suppressed to a small extent.

JP 2011-251480 A JP 2010-42565 A JP 2009-137015 A JP 2007-69378 A

  However, in a droplet discharge device in which a plurality of discharge heads are dispersedly arranged at different positions in the transport direction, a nozzle that discharges a complementary droplet depending on the position of the nozzle where the droplet discharge failure occurred In some cases, the order of ejecting droplets between adjacent nozzles that perform ordinary droplet ejection is switched. Therefore, depending on the ejection order, there is a problem in that liquid ejection occurs in a direction different from the nozzle to be complemented between the ejected liquid droplets, and the ejection pattern such as density unevenness and streaks is likely to occur.

  An object of the present invention is to provide a droplet discharge device capable of suppressing deterioration in image quality when a discharge failure of droplets occurs, and a method for adjusting an ejection head capable of suppressing deterioration in image quality.

In order to achieve the above object, the invention according to claim 1
A droplet discharge means that has a predetermined number of two or more discharge heads provided with a plurality of discharge nozzles for discharging droplets, and causes the droplets to land on a discharge target medium that is relatively moved in a predetermined movement direction. When,
Discharge that causes each of the plurality of discharge nozzles to discharge droplets in a predetermined adjustment landing pattern for obtaining a relative angle between a predetermined axis direction and the moving direction in the arrangement direction of the predetermined number of discharge heads. Control means;
Detecting means for detecting the adjustment landing pattern on the discharged medium;
Correction amount calculation means for determining and outputting information relating to the correction amount of the relative angle based on the detection data of the adjustment landing pattern;
Adjusting means for adjusting the relative angle;
With
In the discharge head, the plurality of discharge nozzles are arranged so that the resolution in the width direction orthogonal to the moving direction is a predetermined recording resolution,
The droplet discharge means includes two droplets in the moving direction over the width that can be discharged in the width direction by the droplet discharge means in a relative positional relationship in which the predetermined number of discharge heads increases the recording resolution. Arranged so as to overlap,
The discharge control unit is configured to apply the adjustment landing pattern to the plurality of discharge heads according to a second discharge head provided downstream in the moving direction at each position in the width direction among the predetermined number of discharge heads. It is formed by ejecting droplets only from the nozzle,
The correction amount calculating unit is configured to dispose the second ejection head from the arrangement direction of the first ejection head provided upstream in the moving direction at each position in the width direction among the predetermined number of ejection heads. In the liquid droplet ejection apparatus, the information related to the correction amount is determined so that the direction approaches an ideal arrangement reference direction.

According to a second aspect of the present invention, in the droplet discharge device according to the first aspect,
The droplet discharge means has two discharge heads,
The correction amount calculation means is characterized in that, of the two ejection heads, information relating to the correction amount that matches the arrangement direction of the second ejection head with the arrangement reference direction is defined.

According to a third aspect of the present invention, in the droplet discharge device according to the first or second aspect,
The plurality of ejection nozzles in the predetermined number of ejection heads are distributed and provided at any position on a plurality of nozzle rows different in the moving direction.

According to a fourth aspect of the present invention, in the droplet discharge device according to any one of the first to third aspects,
The arrangement of the plurality of discharge nozzles in the predetermined number of discharge heads is the same as each other,
The array of the plurality of discharge nozzles related to the predetermined number of discharge heads is provided so as to be shifted from each other by a half of the arrangement interval of the discharge nozzles in the width direction according to the recording resolution. It is a feature.

Invention of Claim 5 is a droplet discharge apparatus as described in any one of Claims 1-4,
It is characterized by comprising an adjustment control means for operating the adjusting means based on the information related to the correction amount and adjusting the relative angle.

A sixth aspect of the present invention provides the droplet discharge device according to any one of the first to fifth aspects,
The adjustment landing pattern is composed of a plurality of lines in the movement direction by droplets discharged from the discharge nozzles selected at predetermined intervals in the width direction,
The correction amount calculation means is characterized in that information relating to the correction amount is acquired in accordance with a landing amount distribution of the droplets on the ejection target medium.

The invention described in claim 7
A droplet discharge means that has a predetermined number of two or more discharge heads provided with a plurality of discharge nozzles for discharging droplets, and causes the droplets to land on a discharge target medium that is relatively moved in a predetermined movement direction. Detecting means for detecting a landing pattern of droplets ejected from the plurality of ejection nozzles on the ejection target medium, a predetermined axial direction according to an arrangement direction of the predetermined number of ejection heads, and the moving direction. Adjusting means for adjusting the relative angle between, and a method for adjusting a discharge head in a droplet discharge device comprising:
A discharge control step of discharging droplets with a predetermined adjustment landing pattern for obtaining a relative angle between the predetermined axial direction and the moving direction from the plurality of discharge nozzles;
A landing pattern detection step of detecting the adjustment landing pattern by the detection means;
A correction amount calculating step for determining and outputting information related to the correction amount of the relative angle based on the detected adjustment landing pattern;
An ejection head adjustment step of adjusting the relative angle according to the information relating to the correction amount;
Including
In the discharge head, the plurality of discharge nozzles are arranged so that the resolution in the width direction orthogonal to the moving direction is a predetermined recording resolution,
The droplet discharge means includes two droplets in the moving direction over the width that can be discharged in the width direction by the droplet discharge means in a relative positional relationship in which the predetermined number of discharge heads increases the recording resolution. Arranged so as to overlap,
In the ejection control step, the plurality of ejections related to the second ejection heads provided on the downstream side in the movement direction at the respective positions in the width direction among the predetermined number of ejection heads. It is formed by ejecting droplets only from the nozzle,
In the correction amount calculating step, among the predetermined number of the ejection heads, the arrangement of the second ejection heads relative to the arrangement direction of the first ejection heads provided on the upstream side in the movement direction at each position in the width direction. The information related to the correction amount is determined so that the direction approaches the ideal arrangement reference direction.

  According to the present invention, in the droplet discharge device, there is an effect that deterioration of image quality can be suppressed when a droplet discharge failure occurs.

1 is an overall perspective view showing an ink jet recording apparatus as an embodiment of a droplet discharge apparatus of the present invention. It is a block diagram which shows the internal structure of an inkjet recording device. FIG. 4 is a diagram illustrating a positional relationship between an ink discharge surface of a discharge module and a recording medium. FIG. 4 is a diagram illustrating a positional relationship between an ink discharge surface of a discharge module and a recording medium. FIG. 6 is a diagram for explaining a complementary operation for ink ejection failure in an inkjet recording apparatus. FIG. 6 is a diagram for explaining a complementary operation for ink ejection failure in an inkjet recording apparatus. It is a flowchart which shows the procedure of a discharge module attachment adjustment process. It is a figure explaining the periodic image formed by discharge module attachment adjustment processing. It is a figure explaining the periodic image formed by discharge module attachment adjustment processing.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall perspective view showing an inkjet recording apparatus 1 as an embodiment of a droplet discharge apparatus of the present invention.

  The inkjet recording apparatus 1 includes a transport unit 10, an image forming unit 20, a detection unit 30 (detection unit), a control unit 40 (see FIG. 2, discharge control unit, correction amount calculation unit, adjustment control unit) and the like. Prepare.

  The conveyance unit 10 includes a motor (not shown) and the like, and moves on the conveyance surface relative to the image forming unit 20 in a predetermined conveyance direction (movement direction), so that the recording placed on the conveyance surface. The medium P (ejection medium) is moved in the transport direction.

The image forming unit 20 is provided across the width of the recording medium P in the width direction orthogonal to the transport direction within a plane parallel to the transport surface. The image forming unit 20 includes a plurality of, here seven, discharge modules 21 (droplet discharge means) each provided with a plurality of nozzles (discharge nozzles). These ejection modules 21 are arranged in a staggered pattern, and each ejects ink (droplets) from a plurality of nozzle openings provided on the surface facing the recording medium P. An image is formed on. Here, the image forming unit 20 is fixed and used during image formation. That is, the discharge module 21 constitutes a line head, and the inkjet recording apparatus 1 forms an image by a one-pass method.
Here, only one color is shown as the image forming unit 20, but when a plurality of colors, for example, four colors of YMCK, are ejected, the four color image forming units 20 differ in the transport direction. It is arranged at each position.

  The image forming unit 20 can finely adjust the mounting angle of the plurality of mounted ejection modules 21. This fine adjustment may be performed manually by the user's operation, or may be performed without the user's operation according to the control operation of the control unit 40 provided with an electric adjustment mechanism.

  The detection unit 30 is provided on the downstream side in the transport direction with respect to the image forming unit 20, images an image formed on the recording surface of the recording medium P by the image forming unit 20, and outputs the imaged data. As the detection unit 30, for example, a line sensor in which a CCD (Charge Coupled Device) sensor, a CMOS (Complementary Metal-Oxide-Semiconductor) sensor, and the like are arranged as an imaging element in the width direction is used. The detection unit 30 may include a light source that illuminates the recording surface in order to increase the contrast of the imaging data, for example, an LED (Light Emitting Diode) light.

  FIG. 2 is a block diagram showing the internal configuration of the inkjet recording apparatus 1 of the present embodiment.

  The inkjet recording apparatus 1 includes a control unit 40, a transport driving unit 41, a head driving unit 421, a head position adjusting mechanism 422 (adjusting unit), a communication unit 43, a storage unit 44, and an operation display unit 45. , A detection drive unit 46, a bus 47, and the like.

  The controller 40 controls the overall operation of the inkjet recording apparatus 1. Further, the CPU 401 performs inspection and adjustment relating to the arrangement of the ejection modules 21 and the ink ejection of each nozzle opening based on the formed image captured by the detection unit 30.

  The control unit 40 includes a CPU 401 (Central Processing Unit), a ROM 402 (Read Only Memory), a RAM 403 (Random Access Memory), and the like. The CPU 401 performs various arithmetic processes and executes processes related to various controls. The ROM 402 stores and saves control programs related to various controls. As the ROM 402, a mask ROM or a readable / writable nonvolatile memory is used.

  The RAM 403 provides a working memory space for the CPU 401 and stores temporary data and various settings. As the RAM 403, various volatile memories such as SRAM and DRAM are used.

  The head driving unit 421 outputs a control signal for driving each ejection module 21 of the image forming unit 20, and ejects ink from the nozzle openings (see FIGS. 3A and 3B) of each ejection module 21 at an appropriate timing. Let These control signals are output in parallel to the discharge modules 21. The control signal is output in synchronization with an encoder (not shown) that measures the conveyance speed (position) of the recording medium P by the conveyance unit 10.

  The head position adjusting mechanism 422 adjusts the angle formed by the ejection module 21 and the transport direction in order to adjust the arrangement direction of the plurality of nozzle openings arranged in the ejection modules 21 provided in the image forming unit 20. To do. The head position adjusting mechanism 422 may be operated by being electrically driven by a user input of a set value or a control signal input from the control unit 40, or may be operated by a user. It may be performed manually by directly operating.

  The communication unit 43 acquires image formation data and a print job from an external computer terminal or a print server, and outputs a status signal related to image formation.

  The storage unit 44 stores image formation data acquired through the communication unit 43 and processing data thereof. The storage unit 44 may store various execution programs relating to image formation. For example, an HDD (Hard Disk Drive) is used as the storage unit 44, and a RAM or the like may be used in combination.

  The operation display unit 45 displays a user input operation reception screen and status information, receives a user input operation, and outputs an operation signal to the control unit 40. As the operation display unit 45, for example, a liquid crystal screen provided with a touch sensor and its driver are used. Or as a display part, the display screen which concerns on other display systems, such as an organic EL display, may be used, and the LED lamp for status display etc. may be used together. Further, as the operation unit, a push button switch, a rotation switch, or the like may be provided instead of or in addition to the touch panel.

  The detection drive unit 46 operates the detection unit 30 at an appropriate timing. The detection driving unit 46 operates each imaging element in synchronization with the conveyance timing of the image formed on the recording medium P to perform imaging, and sequentially transfers the captured data to the control unit 40.

  The bus 47 is a path for transmitting and receiving signals between the control unit 40 and other components.

  Next, the ink ejection surface of the ejection module 21 and the position adjustment of the ejection module 21 in the inkjet recording apparatus 1 of the present embodiment will be described.

3A and 3B are diagrams illustrating the positional relationship between the ink ejection surface of the ejection module 21 and the recording medium P. FIG.
In this figure, the arrangement of the front side of the recording medium P (surface on which an image is formed) and the nozzle openings provided in the recording heads 211 and 212 when viewed through the recording heads 211 and 212 from above the conveying surface is shown. It is shown.
As shown in FIG. 3A, the ejection module 21 of the present embodiment is configured so that two recording heads 211 and 212 (ejection heads) are as parallel as possible at different positions in the transport direction (the recording heads 211 and 212 are They are provided in parallel and are integrally formed so as to overlap in the transport direction. Each of the recording heads 211 and 212 includes a plurality of nozzles, and a nozzle opening that is an ink ejection port from the plurality of nozzles is provided on a surface (ink ejection surface) facing the conveyance surface of the recording heads 211 and 212. Are distributed at nozzle positions 6d on three linear nozzle rows 211a to 211c and 212a to 212c respectively extending in the width direction at three different locations (a plurality of positions) in the transport direction. The three nozzle rows 211a to 211c in the recording head 211 are provided so as to be shifted from each other by an interval of 2d in the width direction, and the three nozzle rows 212a to 212c in the recording head 212 are offset from each other by an interval of 2d in the width direction. Is provided. Accordingly, the recording heads 211 and 212 as a whole are provided with nozzle openings at intervals of 2d over a width (droplet dischargeable width) corresponding to the positions of the nozzle openings at both ends in the width direction. . In addition, the nozzle openings in the recording heads 211 and 212 are arranged in the same manner.
Hereinafter, the direction of the straight line related to the nozzle rows 211a to 211c is the direction of the recording head 211, and the direction of the straight line related to the nozzle rows 212a to 212c is the direction of the recording head 212 (predetermined axis direction). When the inkjet recording apparatus 1 is assembled, installed, or when the ejection module 21 is replaced, the ejection module 21 has an angle (relative angle) that the recording head 211 and the recording head 212 make with the transport direction within a possible range. The ink jet recording apparatus 1 is attached in the direction.

  Furthermore, the recording head 211 and the recording head 212 are attached to the ejection module 21 at a position different in the transport direction, shifted from each other by a distance d in the width direction (relative positional relationship for increasing the recording resolution). Therefore, in the whole of the recording heads 211 and 212, the nozzle openings are provided at intervals d in the width direction.

The resolution in the width direction is determined by the interval d (nozzle pitch) in which these nozzle openings are provided. Here, in each of the recording heads 211 and 212, for example, the nozzle openings are approximately each in the width direction in each nozzle row. They are arranged with a constant width of 127 μm (corresponding to 200 dpi). Accordingly, the respective recording heads 211 and 212 are arranged with nozzles at an interval of about 42.3 μm in the width direction (600 dpi: predetermined recording resolution), and the positional deviation between the two recording heads 211 and 212. Accordingly, the nozzle openings are arranged in a relative positional relationship in which the nozzle openings are provided at an interval of approximately 21.2 μm (corresponding to 1200 dpi) in the width direction as a whole.
The nozzle openings shown here are only a part of the whole, and the number of nozzle openings is appropriately set according to various conditions such as resolution and width of image formation.

  In the image forming unit 20, when some nozzles are clogged inside or the nozzle openings are covered with dirt or the like, ink is not ejected normally and ink ejection failure (liquid droplet ejection failure) occurs. There is. When this ink ejection failure occurs, the ink jet recording apparatus 1 of the present embodiment replaces the complementary ink from the nozzle openings located on both sides in the width direction with respect to the nozzle opening related to the ink ejection failure. Completion is performed by outputting to.

  When a plurality of recording heads 211 and 212 are integrally formed in one ejection module 21, these recording heads 211 and 212 are ideally arranged in a direction perpendicular to the conveying direction (arrangement reference direction). Ink is ejected perpendicularly to the ink ejection surface parallel to the transport surface, and the relative positional relationship is usually due to mechanical errors during the formation of the ejection module 21. A slight shift occurs in In addition, the ink may be ejected with a slight inclination with respect to the ink ejection surface for each nozzle row. As shown in FIG. 3B, here, the recording head 211 (first ejection head) is mounted with an inclination of the rotation angle φf with respect to the recording head 212 (second ejection head), considering only the displacement. Yes. As a result, the nozzle openings of the recording head 211 are displaced in the transport direction and the width direction.

When the recording head is displaced in the rotational direction from the original mounting position (that is, in the arrangement direction), the direction and size of the displacement of the nozzle opening in the width direction is relative to the central position of the rotation of the nozzle opening. It depends on the position, ie the distance and the direction from the center of rotation. As a result, the interval between the nozzle openings in the width direction becomes non-uniform due to the positional relationship between these nozzle openings. Therefore, the interval 2dw in the width direction of the nozzle openings 211b1 and 211a1 used for complementation when the nozzle opening 212a1 is defective in ejection is wider than the original interval 2d, and is complemented when the nozzle opening 212c2 is defective in ejection. The interval 2dn in the width direction of the nozzle openings 211a1, 211c2 used in the above is narrower than the original interval 2d.
Here, for the sake of explanation, the rotation angle φf is shown to be large, but normally the relative rotation angle φf between the printheads in the discharge module in which a plurality of printheads are integrally formed in this way is sufficiently large. The arrangement order in the width direction of the nozzle openings is not reversed from the original arrangement order.

Here, the ink gathering will be described.
The ink droplet landed on the recording medium P spreads and solidifies in a predetermined size (for example, a diameter of about 50 μm) in the vicinity of the ink droplet landing position on the recording medium P. Accordingly, the range in which the ink droplets ejected from the nozzle openings separated by two in the width direction spread on the recording medium P has overlapping portions.

  When the ink droplets discharged from one nozzle opening solidify on the recording medium P and other landed ink droplets spread and come into contact with the ink droplets, these ink droplets are By attracting each other by the surface tension, liquid gathering is generated and combined on the recording medium P to form one ink droplet. When ejection failure of ink from a certain nozzle opening occurs, if ejection is performed from the nozzle openings adjacent to each other in the width direction (that is, nozzle openings separated by two in the width direction), the ejection failure is complemented. By integrating the ink droplets by liquid gathering in this way, the ink droplets have a shape more similar to the ink droplets originally ejected from the original ejection failure nozzle. Therefore, it is preferable that ink droplets related to complementation are ejected so that this liquid gathering occurs.

4A and 4B are diagrams for explaining a complementary operation for ink ejection failure in the inkjet recording apparatus 1 of the present embodiment.
As described above, in the inkjet recording apparatus 1, a certain nozzle opening and a nozzle opening that is adjacent to the nozzle opening in the width direction are always provided in different recording heads 211 and 212. Yes. Further, the ink droplets ejected from the opening of the recording head 211 to the recording medium P are more than the ink droplets ejected from the nozzle opening of the recording head 212 to the same position in the recording medium P transport direction. It will be discharged first. Therefore, as shown in FIG. 4A, first, when ink discharge failure occurs at the nozzle opening of the recording head 212 at timing a1, ink droplets L11 and L12 that complement ink discharge from the nozzle opening are as follows. Ink droplets L13 and L14 ejected from the nozzle openings of the recording head 211 that are further ejected from both sides, that is, two nozzle openings in the width direction from the nozzle opening where the ink ejection failure occurred (see FIG. 4A). It is discharged prior to timing c1). Therefore, at the timing b1, these ink droplets L11 and L12 are integrated by liquid gathering into an ink droplet L10.

  Thereafter, at the timing c1, the ink droplets L13 and L14 are ejected from the recording head 212 while being in contact with the ink droplet L10, and at the timing d1, the whole is integrated by liquid gathering to become the ink droplet L19.

  In contrast, when an ink ejection failure occurs in the nozzle opening of the recording head 211, ink droplets related to normal image formation from the two nozzle openings adjacent to each other in the width direction from the nozzle opening are recorded first. The ink droplets are ejected from the nozzle openings of the head 211, and then ink droplets relating to the complement of the ink ejection failure are ejected from the nozzle openings of the recording head 212.

  That is, as shown in FIG. 4B, first, at the timing a2, the ink liquid is discharged from the nozzle openings of the recording head 211 that are separated by two in the width direction from the nozzle opening where the ink ejection failure has occurred first from the recording head 211. When the droplets L23 and L24 are ejected, at the timing b2, the liquid is squeezed in a streak shape in the transport direction, and two streaky ink droplets L25 and L26 are generated.

  In this state, when complementary ink droplets L21 and L22 are ejected from the nozzle opening of the recording head 212 at timing c2, the ink droplets L21 and L22 separated by one pixel in the width direction are before contacting each other. In addition, as a result of liquid gathering occurring between the ink droplets L25 and L26 formed in advance and the ink being biased toward the center of the liquid gathering, the ink droplets L21 and L22 are integrated together at timing d2. In some cases, ink droplets L27 and L28 may be generated without being changed.

  As described above, whether or not the ink droplets L21 and L22 in the case of complementing the ink ejection failure at the nozzle opening of the recording head 211 are integrated by liquid gathering is simply determined by whether the ink droplets L21 and L22 are in the recording medium P. In addition to being in contact with each other on the landing surface, it is further determined by the distance between the ink droplets L21 and L22 and the ink droplets L25 and L26, respectively. The width condition in the width direction (particularly, the upper limit value) between the nozzle openings of the recording head 212 that can cause the liquid droplets of the ink droplets L21 and L22 related to the formation and attachment of the ejection module 21 is ink. It becomes stricter (smaller) than the condition (upper limit value) in the width direction between the nozzle openings of the recording head 211 capable of causing the liquid droplets L11 and L12 to be brought together.

  When the rotation angle φf is a minute angle, since the distance in the width direction between the nozzle openings can be considered to change in proportion to this angle, the upper limit value of the length for the occurrence of liquid gathering is the rotation angle φf Depends on the upper limit of. That is, the recording head 212 needs to be attached to the ink jet recording apparatus 1 in a direction more accurately orthogonal to the transport direction than the recording head 211. Here, adjustment is simply performed so that the recording head 212 is attached to the inkjet recording apparatus 1 in a direction orthogonal to the conveyance direction.

  FIG. 5 is a flowchart showing the procedure of the attachment adjustment process of the ejection module 21 in the inkjet recording apparatus 1 of the present embodiment.

This discharge module attachment adjustment process is called and started at the time of inspection before shipment, initial startup, or replacement of the image forming unit 20 or the discharge module 21.
When the ejection module attachment adjustment process is started, the control unit 40 (CPU 401) outputs a control signal to the head driving unit 421, and uses only the recording head 212 of each ejection module 21 to perform periodic image ( (Adjustment landing pattern), for example, a solid image is formed (step S101). That is, the solid image is formed uniformly with half the number of nozzles of the original solid image formed by the inkjet recording apparatus 1 of the present embodiment. The control unit 40 outputs a control signal to the detection drive unit 46, captures the formed solid image, and acquires imaging data (detection data) (step S102).

  The control unit 40 detects the entire density distribution (droplet landing amount distribution) from the acquired imaging data, and calculates the inclination of the entire recording head 212 (step S103). Various known methods can be used for this calculation method. The control unit 40 calculates a correction angle for correcting the inclination (step S104), and outputs the calculated correction angle (information on the correction amount) by a predetermined method (step S105).

When the head position adjustment mechanism 422 is electrically operated, the control unit 40 causes the head position adjustment mechanism 422 to perform the adjustment operation of each ejection module 21 based on the correction angle. When the head position adjustment mechanism 422 is manually operated, the control unit 40 may cause the operation display unit 45 to output a calculation result, or at the end of the recording medium P that has output a periodic image. Information related to the tilt adjustment including the correction angle may be recorded.
And the control part 40 complete | finishes a discharge module attachment adjustment process.
When the head position adjustment mechanism 422 is operated manually, the user may read the output information and perform manual adjustment after the discharge module attachment adjustment process is completed.

6A and 6B are diagrams for explaining the periodic image formed by the process of step S101.
Here, a case where ink is ejected from the nozzle openings on the two nozzle rows 212a and 212c among the three nozzle rows 212a to 212c is shown.

  When the recording head 212 is inclined with respect to the conveyance direction as shown in FIG. 6B as compared to the case where the conveyance direction and the recording head 212 are orthogonal to each other as shown in FIG. 6A, the nozzle openings 212c1, 212a1. The distance between the nozzle openings 212c2 and 212a2 increases, while the distance between the nozzle openings 212a1 and 212c2 decreases. As a result, the overlapping portion of the ink droplets ejected from the nozzle openings 212a1 and 212c2 on the recording medium P increases, and the ink droplet ejected from the nozzle openings 212c1 and 212a1 increases on the recording medium P. And the gap on the recording medium P of the ink droplets ejected from the nozzle openings 212c2 and 212a2 are widened. As a result, the density non-uniformity increases as a whole.

  In the inkjet recording apparatus 1 of the present embodiment, the control unit 40 forms a histogram of pixel value (density) distribution in the width direction in the periodic image captured data by the detection unit 30. When density unevenness occurs as described above, the frequency distribution spreads on the higher and lower density sides compared to the case where there is no density unevenness. The inclination angle is calculated according to the extent of such distribution. Alternatively, a correspondence table between the distribution and the tilt angle may be stored in advance, and the correspondence table may be referred to based on a parameter related to the distribution.

As described above, the ink jet recording apparatus 1 of the present embodiment has two (predetermined number) recording heads 211 and 212 provided with a plurality of nozzles for ejecting ink droplets, and is arranged in a predetermined transport direction. The discharge module 21 of the image forming unit 20 that causes ink droplets to land on the relatively moved recording medium P, the detection unit 30 that captures a formed image on the recording medium P, and the orientations of the recording heads 211 and 212 as a whole. As a head position adjustment mechanism 422 and a control unit 40 having a CPU 401.
In the recording heads 211 and 212, a plurality of nozzles are arranged so that the recording resolution in the width direction orthogonal to the transport direction is a predetermined value, for example, 600 dpi, and the ejection module 21 includes two recording heads. In a relative positional relationship in which the recording resolution by 211 and 212 is increased to 1200 dpi, the two are arranged in the width direction so as to overlap with each other in the transport direction over the ink dischargeable width of the discharge module 21. .
The control unit 40 ejects ink from a plurality of nozzles, and sets the relative angle between the direction of the two (predetermined number) recording heads 211 and 212 (the linear direction of the nozzle rows 212a to 212c) and the transport direction. A periodic image or a solid image, which is an image of a predetermined adjustment landing pattern to be obtained, is formed (ejection control means), and the above-described periodic image is detected by the detection unit 30, and the periodic pattern in the image is obtained. Based on the data, the correction amount of the relative angle is obtained and output (correction amount calculation means). At this time, the control unit 40 adjusts the landing pattern for adjustment used for calculating the correction amount only from the nozzles related to the recording head 212 provided on the downstream side in the transport direction at each position in the width direction of the two recording heads. Ink that is related to the image formation is ejected, and the arrangement direction of the recording head 212 provided on the downstream side of the arrangement direction of the recording head 211 provided on the upstream side in the conveyance direction is an ideal arrangement reference direction. The correction amount of the relative angle is obtained so as to approach the direction orthogonal to the direction, that is, the direction in which the intervals in the width direction of the nozzles are evenly spaced 2d.
Therefore, when the ink droplet ejection failure occurs and the complementary ink is ejected from the nozzles adjacent to each other in the width direction, the complementary ink is ejected after the normal ink ejection. However, since the distance between the nozzles on both sides of the defective ejection nozzle can be maintained almost accurately, the complementary ink that has landed on the recording medium P can be appropriately brought together. As a result, it is possible to suppress deterioration in image quality related to complementation.

  In addition, the ejection module 21 of the image forming unit 20 includes two recording heads 211 and 212, and the control unit 40 (correction amount calculation unit) of the two recording heads 211 and 212 is downstream in the transport direction. Since the information related to the correction amount of the orientation of the ejection module 21 is determined so that the orientation of the recording head 212 provided on the side coincides with the above-described arrangement reference direction, the ejection order of adjacent inks in the complementary operation of ejection failure nozzles Therefore, even if it is difficult to cause liquid gathering, the complementary ink landed on the recording medium P can be reliably brought together.

  Further, the nozzle openings corresponding to the plurality of ejection nozzles in the respective recording heads 211 and 212 are dispersed at any position on three linear nozzle rows 211a to 211c and 212a to 212c that are different in the transport direction. Therefore, it is possible to form an image with high resolution more easily and accurately. Further, by applying the present invention to a recording head having such a nozzle arrangement that is likely to be affected by positional deviation due to rotational deviation, it is possible to perform a complementary operation that does not deteriorate the image more effectively.

  The arrangement patterns of the plurality of ejection nozzles in the recording heads 211 and 212 are the same as each other, and the arrangement of the plurality of ejection nozzles related to the recording heads 211 and 212 is in the width direction according to the recording resolution of 600 dpi. A recording resolution of 1200 dpi is achieved by shifting the nozzle openings from each other by about 21.2 μm, which is a half of about 42.3 μm which is the arrangement interval of the nozzle openings. In such image formation by the high-resolution ejection module 21, it is possible to perform the operation of complementing the defective ejection nozzle in such a manner that the formed image with high resolution achieved is not lost as much as possible.

  Further, since the control unit 40 operates the head position adjustment mechanism 422 based on the information related to the correction amount of the direction of the ejection module 21 to adjust the relative angle, the user does not need to perform the adjustment operation manually. The preferred correction amount can be automatically determined and adjusted.

  In addition, a plurality of lines are formed in the transport direction using nozzles selected from the plurality of nozzles related to the recording head 212 at predetermined intervals in the width direction, and the plurality of lines formed on the recording medium P are formed on the recording medium P. Since the correction amount of the direction of the ejection module 21 is calculated according to the density distribution, the correction to the optimal direction of the recording heads 211 and 212 can be easily performed with a simple image pattern having a frequency suitable for acquisition of the density distribution. I can do it.

Also, the recording head adjustment method of the present embodiment has two recording heads 211 and 212 provided with a plurality of nozzles for ejecting ink droplets, and the recording medium P is relatively moved in a predetermined transport direction. The discharge module 21 of the image forming unit 20 that makes ink droplets land on the surface, the detection unit 30 that detects the image pattern of the droplets discharged from the plurality of nozzles on the recording medium P, and the recording heads 211 and 212. An ink jet recording apparatus comprising: a head position adjusting mechanism 422 for adjusting a relative angle between a predetermined axial direction related to an arrangement direction and the moving direction. A discharge control step for forming a periodic image for obtaining a relative angle between the axial direction and the moving direction, and picking up a periodic image formed by the detection unit 30 A landing pattern detection step to be output, a correction amount calculation step for determining and outputting information relating to the correction amount of the relative angle based on the detected periodic image data, and adjusting the relative angle according to the information relating to the correction amount A discharge head adjustment step.
The nozzles are arranged in the recording heads 211 and 212 so that the resolution in the width direction orthogonal to the conveying direction is a predetermined recording resolution, for example, 600 dpi, and the ejection head 21 has the recording heads 211 and 212 in the recording resolution. Are arranged so as to be overlapped with each other in the transport direction over the ink dischargeable width of the discharge module 21 in the width direction.
In the ejection control step, the adjustment landing pattern used for calculating the correction amount is calculated only from the nozzle related to the recording head 212 provided on the downstream side in the transport direction at each position in the width direction of the two recording heads. Eject ink for image formation,
In the correction amount calculating step, the direction of the recording head 212 provided on the downstream side from the direction of the recording head 211 provided on the upstream side in the transport direction at each position in the width direction of the recording heads 211 and 212 is determined. The correction amount of the relative angle is obtained so as to approach the direction orthogonal to the conveyance direction, which is an ideal arrangement reference direction, that is, the direction in which the intervals in the width direction of the nozzles are evenly closer to the interval 2d.
As described above, when ink droplet ejection failure occurs and complementary ink is ejected from the adjacent nozzles in the width direction, the complementary ink is ejected after normal ink ejection. Even so, the distance between the nozzles on both sides of the defective ejection nozzle can be maintained almost accurately, so that the complementary ink that has landed on the recording medium P can be appropriately brought together. As a result, it is possible to suppress deterioration in image quality related to complementation.

The present invention is not limited to the above-described embodiment, and various modifications can be made.
For example, in the above-described embodiment, the case where two recording heads 211 and 212 are provided in each of the seven ejection modules 21 has been described, but 14 recording heads are arranged in the same arrangement in a single ejection module. Even in the case where the recording head is provided, two recording heads are provided at each position in the width direction except for a portion overlapping at both ends of each recording head. In this case, the first and third recording heads from the upstream side become upstream recording heads (first recording heads), and the second and fourth recording heads from the upstream side become downstream recording heads. It becomes a head (second recording head). Thus, when a plurality of second recording heads are provided, the correction amount may be obtained so that the arrangement of all the second recording heads is optimized.
Further, in the single ejection module 21, one first recording head and one second recording head capable of ejecting ink over the entire width capable of image recording may be provided substantially in parallel. That is, the number of ejection modules 21 and the number of recording heads arranged in the width direction in the ejection modules 21 are not limited to a specific number.

  In the above embodiment, the ink jet recording apparatus has been described as an example of the droplet discharge apparatus, but the present invention is not limited to this. Various treatment liquids other than ink may be discharged, or a discharge device that discharges a thin film material used when forming a thin film layer or the like on a substrate may be used.

  In the above-described embodiment, the nozzle openings are arranged in a three-row staggered arrangement in each of the recording heads 211 and 212. However, the present invention is not limited to this. Other numbers of columns may be used. Further, even if the print head 211 and the print head 212 have different arrangement patterns, it is only necessary that the ejection failure nozzle complementary operation can be executed by the adjacent nozzles in the other print head. Further, the nozzle rows 211a to 211c and 212a to 212c in the respective recording heads 211 and 212 do not necessarily need to be orthogonal as long as they intersect the transport direction.

In the above embodiment, the inkjet recording apparatus using the one-pass type line head that ejects ink onto the recording medium P conveyed from the fixed ejection module 21 has been described. However, the ejection module 21 is moved. However, the ink may be ejected. In this case, since it is necessary to define the upstream side and the downstream side in the moving direction, it is necessary to discharge ink only when moving in one direction even when the discharge module 21 reciprocates. is there.
Also in this case, similarly to the above-described line head, the number of ejection modules 21 and the number of recording heads arranged in the width direction in the ejection modules 21 are not limited to a specific number. For example, it may be a single ejection module in which two recording heads are simply arranged at different positions in the transport direction, or a plurality of ejection modules in which two recording heads are arranged at different positions in the transport direction, They may be arranged in a staggered pattern. Alternatively, in each ejection module, the upstream recording head and the downstream recording head may be divided into a plurality of parts in the width direction. In this case, the plurality of divided recording heads are staggered, respectively. You may arrange | position in the grid | lattice form.

  Further, when it is necessary to consider the deviation in the ink ejection direction for each ink row ignored in the above embodiment, the value in consideration of the influence of the deviation in the arrangement direction and the arrangement reference direction of the recording heads 211 and 212 is set. Use it.

Further, in the above embodiment, an appropriate correction amount is calculated based on the periodic image density distribution, but when the ejected droplet is not ink, for example, a colorless transparent droplet, A detection unit 30 that acquires various quantitative indexes such as the thickness of the droplet, the light reflectance, and the refractive index at each landing position is provided, and a distribution of landing patterns can be obtained based on the detection result.
In addition, the specific details shown in the above embodiment can be appropriately changed without departing from the gist of the present invention.

  The present invention can be used for a droplet discharge device and a method for adjusting a discharge head.

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 10 Conveyance part 20 Image formation part 21 Discharge module 211 Recording head 211a-211c Nozzle row 211a1 Nozzle opening 211b1 Nozzle opening 212 Recording head 212a-212c, Nozzle row 212a1 Nozzle opening 212c1 Nozzle opening 212c2 Nozzle opening Unit 30 detection unit 40 control unit 41 transport drive unit 421 head drive unit 422 head position adjustment mechanism 43 communication unit 44 storage unit 45 operation display unit 46 detection drive unit 47 bus P recording medium

Claims (7)

A droplet discharge means that has a predetermined number of two or more discharge heads provided with a plurality of discharge nozzles for discharging droplets, and causes the droplets to land on a discharge target medium that is relatively moved in a predetermined movement direction. When,
Discharge that causes each of the plurality of discharge nozzles to discharge droplets in a predetermined adjustment landing pattern for obtaining a relative angle between a predetermined axis direction and the moving direction in the arrangement direction of the predetermined number of discharge heads. Control means;
Detecting means for detecting the adjustment landing pattern on the discharged medium;
Correction amount calculation means for determining and outputting information relating to the correction amount of the relative angle based on the detection data of the adjustment landing pattern;
Adjusting means for adjusting the relative angle;
With
In the discharge head, the plurality of discharge nozzles are arranged so that the resolution in the width direction orthogonal to the moving direction is a predetermined recording resolution,
The droplet discharge means includes two droplets in the moving direction over the width that can be discharged in the width direction by the droplet discharge means in a relative positional relationship in which the predetermined number of discharge heads increases the recording resolution. Arranged so as to overlap,
The discharge control unit is configured to apply the adjustment landing pattern to the plurality of discharge heads according to a second discharge head provided downstream in the moving direction at each position in the width direction among the predetermined number of discharge heads. It is formed by ejecting droplets only from the nozzle,
The correction amount calculating unit is configured to dispose the second ejection head from the arrangement direction of the first ejection head provided upstream in the moving direction at each position in the width direction among the predetermined number of ejection heads. A liquid droplet ejection apparatus, wherein information relating to the correction amount is determined so that a direction approaches an ideal arrangement reference direction. The droplet discharge means has two discharge heads,
2. The correction amount calculation unit determines information related to the correction amount that causes the arrangement direction of the second ejection head to coincide with the arrangement reference direction among the two ejection heads. Droplet discharge device.   The plurality of ejection nozzles in the predetermined number of ejection heads are distributed and provided at any position on a plurality of nozzle rows that are different in the moving direction. Droplet discharge device. The arrangement of the plurality of discharge nozzles in the predetermined number of discharge heads is the same as each other,
The array of the plurality of discharge nozzles related to the predetermined number of discharge heads is provided so as to be shifted from each other by a half of the arrangement interval of the discharge nozzles in the width direction according to the recording resolution. The liquid droplet ejection apparatus according to claim 1, wherein the liquid droplet ejection apparatus is a liquid ejection apparatus.   5. The droplet discharge according to claim 1, further comprising an adjustment control unit configured to operate the adjustment unit based on the information related to the correction amount and adjust the relative angle. apparatus. The adjustment landing pattern is composed of a plurality of lines in the movement direction by droplets discharged from the discharge nozzles selected at predetermined intervals in the width direction,
The said correction amount calculation means acquires the information which concerns on the said correction amount according to the landing amount distribution of the said droplet on the said to-be-discharged medium. The Claim 1 characterized by the above-mentioned. Droplet discharge device. A droplet discharge means that has a predetermined number of two or more discharge heads provided with a plurality of discharge nozzles for discharging droplets, and causes the droplets to land on a discharge target medium that is relatively moved in a predetermined movement direction. Detecting means for detecting a landing pattern of droplets ejected from the plurality of ejection nozzles on the ejection target medium, a predetermined axial direction according to an arrangement direction of the predetermined number of ejection heads, and the moving direction. Adjusting means for adjusting the relative angle between, and a method for adjusting a discharge head in a droplet discharge device comprising:
A discharge control step of discharging droplets with a predetermined adjustment landing pattern for obtaining a relative angle between the predetermined axial direction and the moving direction from the plurality of discharge nozzles;
A landing pattern detection step of detecting the adjustment landing pattern by the detection means;
A correction amount calculating step for determining and outputting information related to the correction amount of the relative angle based on the detected adjustment landing pattern;
An ejection head adjustment step of adjusting the relative angle according to the information relating to the correction amount;
Including
In the discharge head, the plurality of discharge nozzles are arranged so that the resolution in the width direction orthogonal to the moving direction is a predetermined recording resolution,
The droplet discharge means includes two droplets in the moving direction over the width that can be discharged in the width direction by the droplet discharge means in a relative positional relationship in which the predetermined number of discharge heads increases the recording resolution. Arranged so as to overlap,
In the ejection control step, the plurality of ejections related to the second ejection heads provided on the downstream side in the movement direction at the respective positions in the width direction among the predetermined number of ejection heads. It is formed by ejecting droplets only from the nozzle,
In the correction amount calculating step, among the predetermined number of the ejection heads, the arrangement of the second ejection heads relative to the arrangement direction of the first ejection heads provided on the upstream side in the movement direction at each position in the width direction. A method for adjusting an ejection head, characterized in that information relating to the correction amount is determined so that a direction approaches an ideal arrangement reference direction.

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