JP2011255567A - Liquid discharge apparatus, controller, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain excellent recording quality, without assembling a head again, even when discharge failures such as a landing position deviation and a white streak occur.SOLUTION: A UV irradiation unit 60 is arranged on the downstream side of a line type head 10 in a conveyance direction. The UV irradiation unit 60 includes light emitting elements 61 arranged in a main scanning direction. The light emitting elements 61 constitute light emitting element groups 61G1 to 61G8 corresponding to the main parts 14Ga1 and 14Ga2 of the respective discharge port groups 14G (14G1 to 14G8) of the head 10 and a light emitting element group 61Gb corresponding to an overlapping part 14Gb. Illuminance of ultraviolet light emitted from the light emitting elements 61 is decided for each of the light emitting element groups 61G1 to 61G8 and 61Gb. As the result of test recording, when the landing position deviation and the white steak are detected, the illuminance is adjusted for the light emitting element groups including the light emitting elements 61, corresponding to the detected parts.

Description

  The present invention relates to a liquid ejection apparatus that ejects a liquid (UV ink or the like) that is cured by irradiation with ultraviolet rays, a control apparatus that controls the liquid ejection apparatus, and a program.

  In an ink jet printer which is an example of a liquid ejecting apparatus, a technique for performing recording using UV ink that is cured by irradiation with ultraviolet rays is known. For example, the printer described in Patent Document 1 is arranged on the downstream side in the conveyance direction of each head, a conveyance belt that conveys the recording medium in the conveyance direction, four line-type inkjet heads that are long in the main scanning direction, and Four light sources. In Patent Document 1, in order to prevent intercolor bleeding, a light source for ultraviolet irradiation is disposed on the downstream side in the transport direction of each head.

JP-A-2005-280346

  However, in Patent Document 1, no consideration is given to the problem of ejection failure such as deviation of landing positions and white stripes.

  Since the line type head is long in the main scanning direction, when positioning in relation to the plane along the ejection surface in the printer with reference to one end in the main scanning direction, the position accuracy on the other end side in the main scanning direction In particular, the position of the discharge port on the other end side tends to be easily shifted from a desired position. When the positional accuracy of the head is out of the predetermined range, the landing position of the ink on the recording medium is displaced, and good recording quality cannot be obtained. Therefore, it is necessary to reassemble the head.

  Further, when white streaks (white streaks that can occur in a part of the image along the conveyance direction) occur, it is necessary to replace the head in order to obtain good recording quality. Therefore, in this case, there is a problem that it is necessary to reassemble the head in the same manner as described above, in addition to the environmental and economic disadvantages associated with discarding the head.

  An object of the present invention is to provide a liquid ejection apparatus, a control apparatus, and a program capable of obtaining good recording quality without reassembling the head even when ejection failure such as deviation in landing position or white stripe occurs. Is to provide.

  In order to achieve the above object, according to a first aspect of the present invention, a transport unit having a transport surface that transports in a transport direction while supporting a recording medium on which an image is formed, and a main scanning direction orthogonal to the transport direction. A line-type head that has a long discharge surface and forms an image by discharging a liquid that is cured by irradiation of ultraviolet rays from a plurality of discharge ports that are opened in the discharge surface, the head facing the transport surface A line-type head having an ejection surface; and an ultraviolet irradiation unit that has a light emitting surface elongated in the main scanning direction and irradiates ultraviolet rays from a plurality of light emitting elements arranged on the light emitting surface. For each of a plurality of light emitting element groups, each of which is composed of one or more of the light emitting elements arranged in the main scanning direction, and an ultraviolet irradiation unit having the light emitting surface facing the conveying surface on the downstream side in the conveying direction, From the light emitting element There is provided a liquid ejecting apparatus comprising: a determining unit that determines an illuminance of ultraviolet rays to be irradiated; and a control unit that controls driving of the light emitting element so that the illuminance determined by the determining unit is obtained. The

  According to the second aspect of the present invention, there is a transport unit having a transport surface that transports in the transport direction while supporting a recording medium on which an image is formed, and a long ejection surface in the main scanning direction orthogonal to the transport direction. A line-type head that forms an image by discharging a liquid that is cured by irradiation of ultraviolet rays from a plurality of discharge ports that are open on the discharge surface, the line-type head having the discharge surface facing the transport surface. An ultraviolet irradiation unit that has a light emitting surface that is long in the main scanning direction and that emits ultraviolet light from a plurality of light emitting elements arranged on the light emitting surface; A control unit for use in a liquid ejection apparatus including an ultraviolet irradiation unit having the light emitting surface opposed to a transport surface, wherein the plurality of light emitting elements are arranged in the main scanning direction and each includes one or more light emitting elements. Light emitting device And a determination unit that determines the illuminance of ultraviolet rays emitted from the light emitting element, and a control unit that controls driving of the light emitting element so that the illuminance determined by the determination unit is obtained. A control device is provided.

  According to the third aspect of the present invention, there is a transport unit having a transport surface that transports in the transport direction while supporting a recording medium on which an image is formed, and a long ejection surface in the main scanning direction perpendicular to the transport direction. A line-type head that forms an image by discharging a liquid that is cured by irradiation of ultraviolet rays from a plurality of discharge ports that are open on the discharge surface, the line-type head having the discharge surface facing the transport surface. An ultraviolet irradiation unit that has a light emitting surface that is long in the main scanning direction and that emits ultraviolet light from a plurality of light emitting elements arranged on the light emitting surface; An ultraviolet irradiation unit having the light emitting surface opposed to the transport surface, and a liquid ejection device that is arranged in the main scanning direction and each of a plurality of light emitting element groups each composed of one or more light emitting elements, Illuminated from the light emitting element Determining means for determining the illuminance of ultraviolet rays, and, as the illuminance said determining means has determined is obtained, the program for causing to function as control means, for controlling the driving of the light emitting device is provided.

  According to the present invention, even when a landing position shift or white streak occurs, the illuminance of ultraviolet rays emitted from the light emitting elements is determined for each light emitting element group arranged in the main scanning direction, thereby landing on the recording medium. With respect to the liquid, the degree of curing (curing speed, etc.) can be adjusted to obtain the desired density, dot (pixel) diameter, and the like. As a result, good recording quality can be obtained without reassembling the head.

1 is a schematic side view showing an internal structure of an ink jet printer according to an embodiment of a liquid ejection apparatus of the present invention. It is a top view which shows the flow-path unit and actuator unit of the inkjet head contained in the printer of FIG. FIG. 3 is an enlarged view showing a region III surrounded by an alternate long and short dash line in FIG. 2. FIG. 4 is a partial cross-sectional view taken along line IV-IV in FIG. 3. It is a longitudinal cross-sectional view of an inkjet head. It is a top view which shows a pair of head and UV irradiator. It is a flowchart which shows operation | movement of the printer after power activation. It is a flowchart which shows operation | movement of the printer after the assembly of each part of the printer.

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

  First, an overall configuration of an ink jet printer 1 according to an embodiment of the liquid ejection apparatus of the present invention will be described with reference to FIG.

  The printer 1 has a rectangular parallelepiped casing 1a. A paper discharge unit 31 is provided on the top of the casing 1a. The internal space of the housing 1a can be divided into spaces A, B, and C in order from the top. Spaces A and B are spaces in which a paper transport path that continues to the paper discharge unit 31 is formed. In the space A, the conveyance of the paper P and the recording of the image on the paper P are performed. In the space B, an operation related to paper feeding is performed. In the space C, a cartridge 40 as an ink supply source is accommodated. The cartridge 40 contains UV ink that cures when irradiated with ultraviolet rays.

  In the space A, four inkjet heads 10, four UV irradiators 60, a transport unit 21 for transporting the paper P, a guide unit (described later) for guiding the paper P, and the like are arranged. Above the space A, a control device 1p that controls the operation of each part of the printer 1 including these mechanisms and controls the operation of the entire printer 1 is disposed.

  The control device 1p is configured to perform recording preparation operations, paper P supply / conveyance / discharge operations, and ink synchronized with paper P conveyance so that an image is recorded on the paper P based on image data supplied from the outside. Controls the discharge operation and ultraviolet irradiation.

  In addition to a CPU (Central Processing Unit) that is an arithmetic processing unit, the control device 1p includes a ROM (Read Only Memory), a RAM (Random Access Memory), an ASIC (Application Specific Integrated Circuit), an I / O F (Interface), I / O (Input / Output Port), etc. The ROM stores programs executed by the CPU, various fixed data, and the like. The RAM temporarily stores data (for example, image data) necessary for executing the program. In the ASIC, image data is rewritten and rearranged (signal processing and image processing). The I / F performs data transmission / reception with a host device. I / O inputs / outputs detection signals of various sensors. Each functional unit of the control device 1p is constructed by cooperation of these hardware configurations and programs in the ROM.

  As shown in FIG. 1, the transport unit 21 includes a belt roller 6, 7 and an endless transport belt 8 wound between both rollers 6, 7, and a nip roller 4 disposed on the outer side of the transport belt 8 and a peeling member. The plate 5 and the platen 9 disposed inside the conveyor belt 8 are included.

  The belt roller 7 is a drive roller, and is rotated by driving a conveyance motor (not shown), and rotates clockwise in FIG. At this time, the conveyor belt 8 travels in the direction of the thick arrow in FIG. The belt roller 6 is a driven roller and rotates clockwise in FIG. 1 as the transport belt 8 travels. The nip roller 4 is disposed to face the belt roller 6 and presses the paper P supplied from the upstream guide portion (described later) against the outer peripheral surface 8 a of the transport belt 8. The peeling plate 5 is disposed so as to face the belt roller 7, and peels the paper P from the outer peripheral surface 8 a and guides it to the downstream guide portion (described later). The platen 9 is disposed to face the four heads 10 and supports the upper loop of the conveyor belt 8 from the inside. Thus, a predetermined gap suitable for image recording is formed between the outer peripheral surface 8a and the lower surface of the head 10 (ejection surface 10a).

  The guide unit includes an upstream guide portion and a downstream guide portion disposed with the transport unit 21 interposed therebetween. The upstream guide portion has two guides 27 a and 27 b and a pair of feed rollers 26. The guide unit connects a paper feeding unit 1 b (described later) and the transport unit 21. The downstream guide portion has two guides 29 a and 29 b and two pairs of feed rollers 28. The guide unit connects the transport unit 21 and the paper discharge unit 31.

  The head 10 is a line-type head that is long in the main scanning direction (direction orthogonal to the paper surface of FIG. 1), and has a substantially rectangular parallelepiped outer shape. During image recording, magenta, cyan, yellow, and black UV inks are ejected from the ejection surfaces 10a of the four heads 10, respectively.

  The UV irradiator 60 is provided for each head 10 and is disposed downstream of each head 10 in the transport direction of the paper P by the transport unit 21 (hereinafter simply referred to as “transport direction”). Similar to the head 10, the UV irradiator 60 is long in the main scanning direction and has a substantially rectangular parallelepiped outer shape. During image recording, ultraviolet rays are irradiated from the lower surfaces (light emitting surfaces 60a) of the four UV irradiators 60, and the UV ink attached on the paper P is cured and fixed by the irradiation.

  The head 10 and the UV irradiator 60 are arranged at a predetermined pitch in the sub-scanning direction, and are supported by the housing 1a via the frame 3. More specific configurations of the head 10 and the UV irradiator 60 will be described later.

  A scanner 70 is disposed at a position downstream of the head 10 and the UV irradiator 60 in the transport direction and facing the belt roller 7. The scanner 70 reads a test image described later under the control of the control device 1p.

  In the space B, the paper feeding unit 1b is arranged. The paper feed unit 1 b includes a paper feed tray 23 and a paper feed roller 25. Among these, the paper feed tray 23 is detachable from the housing 1a. The paper feed tray 23 is a box that opens upward, and can store a plurality of types of paper P. The paper feed roller 25 feeds the uppermost paper P in the paper feed tray 23 and supplies it to the upstream guide unit.

  As described above, in the spaces A and B, the paper transport path from the paper feed unit 1b to the paper discharge unit 31 via the transport unit 21 is formed. Based on the recording command, the paper P fed from the paper feed tray 23 is supplied to the transport unit 21 via the upstream guide portion. When the paper P passes directly below each head 10 in the sub-scanning direction, UV ink is ejected in order from the ejection surface 10a, and further, UV light is sequentially irradiated from the light emitting surface 60a to cure the UV ink, whereby the paper P A color image is formed on top. The sheet P on which the image is formed is conveyed through the downstream guide unit and is discharged from the upper opening 30 to the sheet discharge unit 31.

  Here, the sub-scanning direction is a direction parallel to the transport direction of the paper P by the transport unit 21, and the main scanning direction is a direction parallel to the horizontal plane and perpendicular to the sub-scanning direction.

  In the space C, the ink unit 1c is detachably arranged with respect to the housing 1a. The ink unit 1 c includes a cartridge tray 35 and four cartridges 40 accommodated in the tray 35 side by side. Each cartridge 40 supplies ink to the corresponding head 10 via an ink tube (not shown).

  Next, the configuration of the head 10 will be described in more detail with reference to FIGS. In FIG. 3, the pressure chamber 16 and the aperture 15 which are located below the actuator unit 17 and should be indicated by dotted lines are indicated by solid lines.

  As shown in FIG. 5, the head 10 is a stacked body in which the flow path unit 12, the actuator unit 17, the reservoir unit 11, and the substrate 64 are stacked. Among these, the actuator unit 17, the reservoir unit 11, and the substrate 64 are accommodated in a space formed by the upper surface 12 x of the flow path unit 12 and the cover 65. Within the space, an FPC (flat flexible substrate) 50 electrically connects the actuator unit 17 and the substrate 64. A driver IC 57 is mounted in the middle of the FPC 50.

  The cover 65 includes a top cover 65a and a side cover 65b as shown in FIG. The cover 65 is a box that opens downward, and is fixed to the upper surface 12 x of the flow path unit 12. The side cover 65b is made of an aluminum plate and also functions as a heat radiating plate. The driver IC 57 contacts the inner surface of the side cover 65b and is thermally coupled to the cover 65b.

  The reservoir unit 11 is a laminated body in which four metal plates 11a to 11d each having a through hole and a recess are bonded to each other. An ink flow path including a reservoir is formed inside the reservoir unit 11. One end of the ink flow path is connected to the cartridge 40 via a tube or the like, and the other end is opened on the lower surface of the reservoir unit 11. In the plate 11d, an ink outflow channel 73 (a part of the ink channel of the reservoir unit 11) communicating with the reservoir 72 is formed. The flow path 73 is open to the tip surface of the convex portion on the lower surface of the plate 11d (that is, the bonding surface with the upper surface 12x).

  The flow path unit 12 is a laminated body in which nine rectangular metal plates 12a, 12b, 12c, 12d, 12e, 12f, 12g, 12h, and 12i (see FIG. 4) having substantially the same size are bonded to each other. As shown in FIG. 2, an opening 12 y that faces the opening 73 a of the ink outflow channel 73 is formed on the upper surface 12 x of the channel unit 12. Inside the flow path unit 12, an ink flow path that is connected to the ejection port 14a from the opening 12y is formed. As shown in FIGS. 2, 3, and 4, the ink flow path includes a manifold flow path 13 having an opening 12y at one end, a sub-manifold flow path 13a branched from the manifold flow path 13, and a sub-manifold flow path 13a. The individual flow path 14 from the outlet to the discharge port 14a through the pressure chamber 16 is included.

  The manifold channel 13 and the sub-manifold channel 13a are channels common to the plurality of discharge ports 14a, as shown in FIGS. The individual flow path 14 is formed for each discharge port 14a, and includes an aperture 15 functioning as a flow path resistance adjusting aperture and a pressure chamber 16 opened to the upper surface 12x, as shown in FIG. As shown in FIG. 3, each of the pressure chambers 16 has a substantially rhombus shape, and is arranged in a matrix to constitute a total of eight pressure chamber groups 16G that occupy a substantially trapezoidal region in plan view. Similarly to the pressure chambers 16, the discharge ports 14 a opened in the discharge surface 10 a are arranged in a matrix, thereby constituting a total of eight discharge port groups 14 G occupying a substantially trapezoidal region in plan view. The ejection port group 14G and the pressure chamber group 16G are arranged in two rows in a staggered pattern in the main scanning direction on the ejection surface 10a and the upper surface 12x, respectively.

  As shown in FIG. 2, each actuator unit 17 has a trapezoidal planar shape, and is disposed on the trapezoidal region of the pressure chamber group 16G. In any actuator unit 17, the lower bottom portion of the trapezoid is close to the end of the flow path unit 12 in the sub-scanning direction. The actuator unit 17 is disposed in a gap created by the reservoir unit 11 and the flow path unit 12 while avoiding the convex portion on the lower surface of the reservoir unit.

  The FPC 50 is provided for each actuator unit 17 and has wiring corresponding to each electrode of the actuator unit 17. Each wiring is connected to the output terminal of the driver IC 57. Under the control of the control device 1p (see FIG. 1), the FPC 50 transmits various drive signals adjusted by the substrate 64 to the driver IC 57, and transmits each drive signal generated by the driver IC 57 to the actuator unit 17.

  Thus, during image formation, ejection driving is performed in units of actuator units. One actuator unit 17, the FPC 50, the driver IC 57, and a part of the flow path unit 12 (partial flow path unit) involved in this constitute a short head unit. In the present embodiment, eight partial flow path units integrally form one flow path unit 12 to form one head 10. In other words, in this embodiment, a head unit is formed in a portion corresponding to each actuator unit 17, and one head 10 includes a total of eight head units.

  Each actuator unit 17 is composed of a piezoelectric layer, a diaphragm, a common electrode, and individual electrodes (not shown). Among the above members, the piezoelectric layer, the diaphragm, and the common electrode have a trapezoidal shape having a size that defines the outer shape of the actuator unit 17. The individual electrode is disposed to face each pressure chamber 16 and has a substantially similar shape to the pressure chamber 16. The diaphragm is disposed between the common electrode and the flow path unit 12. The same number of individual electrodes as the pressure chambers 16 in the corresponding pressure chamber group 16G are formed on the upper surface of the uppermost piezoelectric layer. The portions facing the individual electrodes of the actuator unit 17 function as independent piezoelectric actuators.

  Next, the configuration of the UV irradiator 60 will be specifically described with reference to FIG.

  FIG. 6 shows one head 10 and one UV irradiator 60 provided corresponding to this, but the other heads 10 and UV irradiators 60 also have the same configuration. Further, FIG. 6 is a view seen from above, but for the sake of explanation, the ejection port groups formed on the lower surface of the head 10 and the UV irradiator 60 (ejection surface 10a and light emitting surface 60a: see FIG. 1), respectively. 14G (14G1 to 14G8) and the light emitting element groups 61G1 to 61G8 and 61Gb are indicated by solid lines, respectively. The solid line related to the discharge port group 14G corresponds to the outline of the region occupied by each group, and the solid line related to the light emitting element group corresponds to the outline of the region occupied by the light emitting element 61 included in each group.

  The UV irradiator 60 has a light emitting surface 60a (see FIG. 1) that is long in the main scanning direction. On the light emitting surface 60a, as shown in FIG. 6, a large number of light emitting elements 61 are arranged in a line in the main scanning direction. Examples of the light emitting element 61 include a mercury lamp, a metal halide lamp, an LED element, and an LD element. However, the light emitting element 61 is not limited to these, and any element that irradiates ultraviolet rays can be applied.

  Here, the discharge port group 14G is arranged in two rows in a staggered manner in the main scanning direction, and therefore, from the upstream group 14G2, 14G4, 14G6, 14G8 and the upstream group arranged upstream in the transport direction. Can also be distinguished into downstream groups 14G1, 14G3, 14G5, 14G7 arranged downstream in the transport direction. The upstream group and the downstream group adjacent to each other in the main scanning direction have an overlapping portion 14Gb (hatched portion in FIG. 6) that overlaps when viewed from the transport direction. The ejection port groups 14G1 and 14G8 at both ends in the main scanning direction include one overlapping portion 14Gb and a main portion 14Ga1 excluding the overlapping portion 14Gb. The discharge port groups 14G2 to 14G7 include two overlapping portions 14Gb and a main portion 14Ga2. The main portions 14Ga1 and 14Ga2 are portions of the region of the discharge port group 14G that do not overlap with the other discharge port groups 14G when viewed from the transport direction. The central main portion 14Ga2 has a substantially rectangular shape, and the overlapping portion 14Gb has a substantially right triangle shape. The main portion 14Ga1 at both ends has a substantially trapezoidal shape in which a rectangle and a right triangle are combined.

  The large number of light emitting elements 61 are divided into two types according to the positional relationship with the ejection port group 14G in the transport direction. One of the light emitting element groups 61G1 to 61G8 overlaps the main portions 14Ga1 and 14Ga2 of the discharge port group 14G in the transport direction. The other is the light emitting element group 61Gb, which overlaps the overlapping portion 14Gb of the ejection port group 14G in the transport direction. Among these, the light emitting element groups 61G1 and 61G8 are arranged at both ends in the main scanning direction as shown in FIG. The light emitting element groups 61G2 to 61G7 are arranged in the central portion of the line, and each includes four light emitting elements 61. The seven light emitting element groups 61Gb are disposed between the light emitting element groups 61G1 to 61G8, respectively, and each includes two light emitting elements 61.

  The plurality of light emitting elements 61 included in one light emitting element group irradiate ultraviolet rays having the same illuminance. Hereinafter, the “illuminance of the light emitting element group” means the illuminance of ultraviolet rays emitted from the light emitting elements included in the light emitting element group.

  The light emitting element groups 61G1 to 61G8 and 61Gb have different illuminances of the light emitting element groups depending on the positional relationship with the ejection port group 14G in the transport direction. The illuminance of the light emitting element groups 61G2, 61G4, 61G6, 61G8 corresponding to the upstream groups 14G2, 14G4, 14G6, 14G8 is the light emitting element groups 61G1, 61G3, 61G5, 61G7 corresponding to the downstream groups 14G1, 14G3, 14G5, 14G7. Greater than illuminance. Further, the illuminance of each light emitting element group 61Gb is set to be an average value of the illuminance of two light emitting element groups sandwiching the light emitting element group 61Gb. For example, the illuminance of the light emitting element group 61Gb at the left end in FIG. 6 is equal to the average value of the illuminances of the two light emitting element groups 61G1 and 61G2.

  With such a configuration, the influence on the pixel density produced by the ink cured and fixed on the paper due to the difference in the distance from the ejection port 14a to the UV irradiator 60 is reduced. When this separation distance is increased, the time from the ink landing on the paper P until the ultraviolet irradiation is increased, and the spread of pixels on the paper P is increased. For the same illuminance, the greater the distance, the lower the pixel density. Therefore, in this embodiment, the magnitude of the illuminance is set corresponding to the magnitude of the separation distance. That is, if the separation distance is large, the illuminance is increased to suppress the spread of the pixels, and the decrease in the pixel density is suppressed. If the separation distance is small, the illuminance is reduced to promote the spread of the pixels and suppress the increase in pixel density. Thereby, recording (printing) with a uniform density can be performed in the entire head 10. Furthermore, by making the illuminance of the light emitting element group 61Gb related to the overlapping portion 14Gb the average value of the illuminance of the light emitting element groups on both sides, the recording density can be made more uniform.

  Next, the operation of the printer 1 after the power is turned on will be described with reference to FIG. The operation described below is executed under control performed by the CPU of the control device 1p according to a program stored in the ROM.

  If image formation is continued over a long period of time, uneven printing may be noticeable due to a change in the light emission characteristics of the light emitting element 61 or a change in the drive characteristics of the actuator unit 17. Or, due to foreign matter adhering to the ejection surface 10a, ejection failure such as deviation of ink landing position or non-ejection may occur. In either case, the recording quality is reduced. The operation described below is a recovery operation for suppressing such a decrease in recording quality, and may be executed periodically or at an arbitrary timing as necessary. The recovery operation includes a method of directly changing the illuminance of the light emitting element group and a method of changing the separation distance between the head 10 (discharge port 14a) and the UV irradiator 60 (light emitting element group).

  First, the control device 1p controls each part of the printer 1 including all the heads 10 and all the UV irradiators 60 so that test recording (S1) is performed. At this time, one sheet P is fed out from the sheet feeding tray 23, and a color image for test recording is formed on the sheet P. At this time, the actuator unit 17 of the head 10 is driven based on the image data for test recording. Further, the light emitting elements 61 of the UV irradiator 60 are each driven under predetermined conditions. As the predetermined condition, the driving condition set immediately before the test recording (S1) is performed is used. In the first test recording (S1) after shipment of the printer 1, conditions preset at the time of shipment are used.

  Next, the control device 1p controls the scanner 70 (see FIG. 1) so that the test image formed on the paper P is read (S2). The control device 1p receives the read image data, and detects the density of each color ink pixel in the test image based on the data (S3).

  After S3, the control device 1p determines the illuminance of each of the light emitting element groups 61G1 to 61G8, 61Gb (S4). The illuminance is determined by performing adjustment based on the result of the density detection (S3) with respect to the driving condition at the time of test recording.

  For example, from the result of the density detection (S3), it is possible to determine the presence or absence of ejection defects such as a deviation of the landing position and a white stripe that may occur in a part of the image along the conveyance direction. The illuminance of the light emitting element group including the light emitting element 61 corresponding to the portion where the landing position is shifted or the white stripe is generated is made smaller than the illuminance at the time of test recording. The adjustment of the illuminance is performed, for example, by changing the driving condition (pulse width or voltage value) of the light emitting element 61. When it is determined that there is no ejection failure, the illuminance at the time of test recording is maintained.

  Further, from the result of the density detection (S3), a recording (printing) density for each ejection port group 14G is obtained, and for the ejection port group 14G in which a density decrease is observed, the illuminance of the corresponding light emitting element group is increased. The driving condition of the light emitting element 61 is changed.

  After S4, the control device 1p determines whether or not a recording command has been received from a host device such as a PC (S5). When the recording command is not received (S5: NO), the control device 1p repeats the process. When the recording command is received (S5: YES), the control device 1p controls driving of the head 10, the UV irradiator 60, the transport unit 21 and the like so that the recording according to the recording command is performed.

  As described above, according to the printer 1, the control device 1p, and the program according to the present embodiment, the light emitting element groups 61G1 to 61G8 arranged in the main scanning direction even when the landing position is displaced or the white stripe is generated. , 61 Gb (see FIG. 6), by adjusting the illuminance of the ultraviolet light emitted from the light emitting element 61, the degree of curing (curing speed, etc.) of the ink landed on the paper P is adjusted, and the desired density and A dot diameter etc. can be obtained. As a result, good recording quality can be obtained without reassembling the head 10.

  From the result of density detection (S3 in FIG. 7), it is possible to determine whether or not there is a deviation in the landing position or white stripes. Then, for the light emitting element group including the light emitting element 61 corresponding to the portion where the landing position is shifted or the white stripe is generated, the illuminance is determined to be smaller than the illuminance at the time of test recording (S4). Good recording quality can be obtained without performing again.

  Here, the principle of improving the recording quality will be described more specifically. For example, by adjusting the illuminance of ultraviolet rays and reducing the degree of ink curing for areas where landing positions are displaced or white stripes are generated, the outer edge of the dot (pixel) is blurred or the dot diameter is increased. Can do. Further, when the density is higher (or lower) than the predetermined value, the degree of curing of the ink can be adjusted by reducing (or increasing) the illuminance of ultraviolet rays, and can be brought close to a desired density. For ejection failures such as white stripes, the illuminance is reduced, the outer edge of the pixel is blurred, the pixel density is lowered, and the visibility of the defective state is lowered. Even when the image density is high, the pixel density can be lowered by reducing the illuminance.

  When a plurality of ejection port groups 14G are arranged in the main scanning direction on the ejection surface 10a (see FIG. 6), errors occur in ejection performance for each ejection port group 14G due to dimensions, positioning errors, and the like in the manufacturing process. obtain. Therefore, by adjusting the illuminance for each of the light emitting element groups 61G1 to 61G8 corresponding to the ejection port groups 14G1 to 14G8, it is possible to suppress the influence on the recording quality due to the performance error.

  When the ejection port group 14G adjacent in the main scanning direction has the overlapping portion 14Gb, the illuminance of the light emitting element group 61Gb corresponding to the overlapping portion 14Gb is set as the illuminance of the two light emitting element groups sandwiching the group 61Gb from both sides. The average value is determined. Thereby, even better recording quality can be obtained.

  Next, the fixing form of the head 10 and the UV irradiator 60 to the frame 3 will be described.

  As shown in FIG. 6, the head 10 and the UV irradiator 60 are both supported by a frame-like frame 3 fixed to the housing 1a. For example, the head 10 is fixed to the frame 3 via a plate (for example, a plate 11d) that is longer in the main scanning direction than the other plates among the plates 11a to 11d of the reservoir unit 11.

  The head 10 is screwed by through holes 10x and 10y formed at both ends of the plate (for example, the plate 11d) in the main scanning direction and fixed to the frame 3 so as not to move. On the other hand, the UV irradiator 60 is fixed so that the position of the UV irradiator 60 can be adjusted (the angle with respect to the main scanning direction can be adjusted). The UV irradiator 60 has through holes 60x and 60y at both ends in the main scanning direction. A support pin is inserted into the through hole 60x, and an eccentric pin is inserted into the through hole 60y. These fixing operations are performed based on the through holes 10x and 60x at one end in the main scanning direction (left side in FIG. 6) (that is, one end in the main scanning direction is positioned by inserting a screw or a pin into the through holes 10x and 60x). Thereafter, the other end in the main scanning direction (right side in FIG. 6) is fixed).

  Near the other end in the main scanning direction of the UV irradiator 60, for example, a moving mechanism (not shown) including gears and a motor 60M for driving the moving mechanism are arranged. The motor 60M rotates under the control of the control device 1p in angle adjustment (S16: see FIG. 8) described later. As the motor 60M rotates, the moving mechanism is driven, and the eccentric pin inserted into the through hole 60y rotates. At this time, the other end of the UV irradiator 60 moves to the upstream side or the downstream side in the transport direction, and the UV irradiator 60 rotates around the through hole 60x. Therefore, although the UV irradiator 60 is arranged along the straight line O parallel to the main scanning direction in FIG. 6, the angle θ with respect to the straight line O can be changed within a predetermined range by driving the motor 60M. .

  Next, the operation of the printer 1 after assembling each part of the printer 1 will be described with reference to FIG. The operation described below is executed under control performed by the CPU of the control device 1p according to a program stored in the ROM. The operation described below may be executed not only after assembling each part of the printer 1 but also at an arbitrary timing as a recovery operation for recovering the recording quality.

  First, the control device 1p determines whether the assembly of the head 10 and the UV irradiator 60 has been completed (S11). The determination is made based on, for example, manual input by the user, a sensor incorporated in the frame 3, and the like.

  When the assembly of the head 10 and the UV irradiator 60 is completed (S11: YES), the control device 1p reads the test recording (S12) similar to S1, reads the test image similar to S2 (S13), and S3. Each part of the printer 1 is controlled so that the same density detection (S14) is sequentially performed.

  And the control apparatus 1p judges whether angle adjustment is required about each UV irradiation device 60 according to the result of density | concentration detection (S14) (S15). At this time, the control device 1p requires angle adjustment when a density difference of a predetermined value or more is detected on both sides with respect to the center of the ejection area in the main scanning direction, or when ejection failure such as landing position deviation or white stripe is detected. Judge. For example, when it is determined from the result of the density detection (S14) that the landing position has shifted, the control device 1p determines that the angle adjustment is necessary for the corresponding UV irradiator 60 (S15: YES). . In this case, the control device 1p determines an angle with respect to the main scanning direction for the UV irradiator 60, and performs angle adjustment (S16) so that the determined angle is obtained. At this time, the control device 1p drives a moving mechanism (not shown) by rotating a motor 60M (see FIG. 6), and adjusts the angle of the UV irradiator 60 with respect to the main scanning direction.

  As described above, according to the present embodiment, even when the landing position is deviated, by adjusting the angle of the UV irradiator 60 with respect to the main scanning direction, the leaving time of the ink ejected from the ejection port 14a. The desired density and dot diameter can be obtained. As a result, good recording quality can be obtained without reassembling the head 10.

  More specifically, the density and dot diameter of the image formed by the ink ejected from the ejection port 14a and landed on the paper P vary depending on the distance between the ejection port 14a and the light emitting element, that is, the above-described leaving time. Therefore, by adjusting the angle of the UV irradiator 60 with respect to the main scanning direction and adjusting the standing time, the degree of ink curing (curing speed, etc.) can be adjusted to approach the desired density and dot diameter. That is, with respect to the deviation of the landing position and the white stripe, by increasing the standing time from the ink landing on the paper P, the outer edge of the pixel is blurred and the pixel density after ink curing and fixing is lowered. At this time, the eccentric pin is arranged so that the side with ejection failure is far from the head 10 with respect to the center of the ejection region in the main scanning direction. As a result, the recording quality can be recovered. When there is a density difference between both sides with respect to the center of the ejection region in the main scanning direction, the eccentric pin may be arranged so that the side with the higher density is farther from the head 10. In the recovery operation of FIG. 8, the illuminance of each light emitting element 61 is not changed.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various design changes can be made as long as they are described in the claims.

  In determining whether or not the angle adjustment (S16) is necessary, in the above-described embodiment, the deviation of the landing position is determined using the result of the density detection (S14). The position of the discharge port may be directly detected, and the deviation of the landing position may be determined from the detection result.

  In the present invention, the series of steps shown in FIG. 8 is not an essential requirement. That is, the position of the UV irradiator 60 may not be adjustable with respect to the frame 3, as with the head 10.

  The density detection (S3) may be performed using a scanner or the like outside the housing 1a. Further, without detecting the concentration (S3), the position of the discharge port may be directly detected by a sensor or the like, and the concentration may be detected by directly correlating the position of the discharge port and the landing position.

  The light emitting elements are not limited to being arranged in one column along the main scanning direction, and two or more columns may be formed.

  The actuator for applying the liquid discharge energy from the discharge port may be a thermal type, an electrostatic type or the like in addition to the piezoelectric type as in the above-described embodiment.

  The number of actuator units is eight per head in the above-described embodiment, but may be four and arbitrary. The shape of the actuator unit is not limited to a trapezoid, and may be a rectangle or the like.

  The ejection port groups are not limited to being arranged in a staggered manner in the main scanning direction, and may be arranged in one row in the main scanning direction. Adjacent discharge port groups do not have to have overlapping portions.

  The liquid ejection apparatus according to the present invention is not limited to a printer, but can be applied to a facsimile, a copier, and the like. Furthermore, the head according to the present invention may eject a liquid other than ink.

  The recording medium is not limited to the paper P as long as it is a recordable medium, and may be a cloth or the like.

1 Inkjet printer (liquid ejection device)
1p control device (decision means, control means, detection means, second detection means, second decision means, second control means)
3 Frame (support mechanism)
8a Outer peripheral surface (conveying surface)
10 Inkjet head (head)
10a Discharge surface 14a Discharge port 14G (14G1 to 14G8) Discharge port group 14G2, 14G4, 14G6, 14G8 Upstream side group 14G1, 14G3, 14G5, 14G7 Downstream side group 14Ga1, 14Ga2 Main part 14Gb Overlapping part 21 Transport unit (transport part)
60 UV irradiator (ultraviolet irradiation unit)
60a Light emitting surface 61 Light emitting element 61G1-61G8, 61Gb Light emitting element group 70 Scanner (detection means, second detection means)
P paper (recording medium)

Claims (8)

A transport unit having a transport surface for transporting in the transport direction while supporting a recording medium on which an image is formed;
A line-type head that has an ejection surface that is long in the main scanning direction perpendicular to the transport direction, and forms an image by ejecting liquid that is cured by irradiation of ultraviolet rays from a plurality of ejection openings that are opened in the ejection surface. A line-type head having the ejection surface opposed to the conveyance surface;
An ultraviolet irradiating unit having a light emitting surface elongated in the main scanning direction and irradiating ultraviolet rays from a plurality of light emitting elements arranged on the light emitting surface, on the conveying surface downstream of the conveying direction of the head; An ultraviolet irradiation part having the light emitting surface opposed to the light emitting surface;
Determining means for determining the illuminance of ultraviolet rays emitted from the light emitting elements for each of a plurality of light emitting element groups arranged in the main scanning direction and each composed of one or more light emitting elements;
A liquid ejecting apparatus comprising: a control unit that controls driving of the light emitting element so that the illuminance determined by the determining unit can be obtained. A detecting means for detecting a density of an image formed by a liquid discharged from the discharge port and landed on a recording medium;
The liquid ejecting apparatus according to claim 1, wherein the determining unit determines the illuminance for each of the light emitting element groups according to a detection result of the detecting unit. A plurality of ejection port groups each composed of one or more ejection ports are arranged in the main scanning direction on the ejection surface,
The liquid ejection device according to claim 1, wherein the light emitting element group corresponds to each of the ejection port groups. The plurality of ejection port groups are arranged in a staggered manner in the main scanning direction, and an upstream group disposed on the upstream side in the transport direction and a downstream side disposed on the downstream side in the transport direction with respect to the upstream group Make up a group,
The deciding means determines the illuminance so that the illuminance of the light emitting element group corresponding to the upstream group is greater than the illuminance of the light emitting element group corresponding to the downstream group. The liquid discharge apparatus according to 1. The upstream group ejection port group and the downstream group ejection port group arranged adjacent to each other in the main scanning direction have overlapping portions partially overlapping when viewed from the transport direction,
The light emitting element group corresponds to each of the main part excluding the overlapping part and the overlapping part in the discharge port group,
In the determining means, the illuminance of the light emitting element group corresponding to the overlapping portion is an average value of the illuminance of the two light emitting element groups corresponding to the main portion of the two ejection port groups constituting the overlapping portion. The liquid ejection apparatus according to claim 4, wherein the illuminance of the light emitting element is determined. A support mechanism for supporting the ultraviolet irradiation unit so that an angle with respect to the main scanning direction can be adjusted;
Second detection means for detecting a positional shift of a pixel formed by a liquid discharged from the discharge port and landed on a recording medium in the main scanning direction;
Second determination means for determining the angle according to a detection result of the second detection means;
Second control means for controlling driving of the support mechanism so that the angle determined by the second determination means is obtained;
The second control unit is configured to irradiate the ultraviolet ray at the discharge port at the end portion closer to the position shift with respect to the main scanning direction than at the discharge port at the end portion far from the position shift position. The liquid ejection apparatus according to any one of claims 1 to 5, wherein the drive of the support mechanism is controlled so that a separation distance in the transport direction with respect to a portion is increased. A transport unit having a transport surface that transports in the transport direction while supporting a recording medium on which an image is formed, and a plurality of discharge surfaces that are long in the main scanning direction orthogonal to the transport direction and open to the discharge surface A line-type head that forms an image by discharging a liquid that is cured by irradiation of ultraviolet rays from a discharge port of the line, the line-type head having the discharge surface facing the transport surface, and a long head in the main scanning direction. An ultraviolet irradiation unit for irradiating ultraviolet rays from a plurality of light emitting elements arranged on the light emitting surface, the light emitting surface facing the transport surface downstream of the head in the transport direction. A control device used in a liquid ejection device including an ultraviolet irradiation unit,
Determining means for determining the illuminance of ultraviolet rays emitted from the light emitting elements for each of a plurality of light emitting element groups arranged in the main scanning direction and each composed of one or more light emitting elements;
And a control unit that controls driving of the light emitting element so that the illuminance determined by the determination unit is obtained. A transport unit having a transport surface that transports in the transport direction while supporting a recording medium on which an image is formed, and a plurality of discharge surfaces that are long in the main scanning direction orthogonal to the transport direction and open to the discharge surface A line-type head that forms an image by discharging a liquid that is cured by irradiation of ultraviolet rays from a discharge port of the line, the line-type head having the discharge surface facing the transport surface, and a long head in the main scanning direction. An ultraviolet irradiation unit for irradiating ultraviolet rays from a plurality of light emitting elements arranged on the light emitting surface, the light emitting surface facing the transport surface downstream of the head in the transport direction. A liquid ejection device including an ultraviolet irradiation unit having
Determining means for determining the illuminance of ultraviolet rays emitted from the light emitting elements for each of a plurality of light emitting element groups arranged in the main scanning direction and each composed of one or more light emitting elements; and
Control means for controlling driving of the light emitting element so that the illuminance determined by the determining means can be obtained;
A program characterized by functioning as

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