JP2021146631A - Liquid discharge device and image recorder comprising the same - Google Patents

Abstract

To provide a liquid discharge device suppressing oxygen inhibition on a nozzle array end part, and an image recorder comprising the same.SOLUTION: A liquid discharge device comprises: a discharge head comprising at least one row of a nozzle row including a plurality of nozzles which are arranged in a sub scanning direction, in a main scanning direction, and moving in the main scanning direction; and an ultraviolet lamp including at least one row of a chip row including a plurality of light emitting diode chips which is arranged in the sub scanning direction, in the main scanning direction, and moving in the main scanning direction. In at least one chip row, chip density which is the number of the light emitting diode chips for a unit length in the sub scanning direction on an end part of the sub scanning direction, is greater than chip density on a center in the sub scanning direction, illuminance on the end part is greater than illuminance on a center, and at least one light emitting diode chip is provided at outside of the sub scanning direction relative to the nozzle provided on a nozzle end being an end part of the nozzle row.SELECTED DRAWING: Figure 7

Description

The present invention relates to an ultraviolet irradiation device that irradiates ultraviolet rays that cure ultraviolet curable ink, and an image recording device such as an inkjet printer provided with the ultraviolet irradiation device.

In recent years, for example, as shown in Patent Document 1, a device used in an image recording device such as an inkjet printer to irradiate ultraviolet curable ink that is cured by ultraviolet rays with ultraviolet rays (described as a liquid ejection device in Patent Document 1). )It has been known. The liquid ejection device disclosed in this document cures the ink and fixes it on the printed matter by irradiating the ink droplets landed on the printed matter with ultraviolet rays. By using the ultraviolet curable ink in this way, it is possible to print on a resin, metal, or the like other than paper, for example, and a glossy printed matter can be obtained.

In the liquid discharge device of the above document, a plurality of light emitting diode chips are provided on the array. The light emitting diode chips are arranged in a matrix along the lateral direction (main scanning direction) and the longitudinal direction (secondary scanning direction) of the array. Each light emitting diode chip is arranged at a constant pitch in the main scanning direction and also at a constant pitch in the sub scanning direction. On the other hand, since a desired illuminance distribution cannot be obtained simply by arranging a plurality of light emitting diode chips regularly in this way, in the above liquid discharge device, the illuminance of ultraviolet rays at the end portion in the sub-scanning direction is the central portion. A plurality of light emitting diode chips are driven so as to be larger than the illuminance. In this case, the illuminance of each light emitting diode chip is controlled by adjusting the current supplied to each light emitting diode chip. With such a configuration, it is possible to uniformly irradiate ultraviolet rays in the sub-scanning direction, and unevenness of the irradiation light amount is suppressed.

JP-A-2019-209494

By the way, at the end of the nozzle row, oxygen inhibition occurs, which is a phenomenon in which the monomer of the ultraviolet curable ink is captured by oxygen, and the ink becomes difficult to cure due to the oxygen inhibition. In particular, when solid printing such as clear ink is performed, the surface area of the liquid landed on the printed matter is larger at the position corresponding to the end of the nozzle row than at the position corresponding to the center of the nozzle row. The effect of oxygen inhibition at the position corresponding to the end of the row is greater than at other parts. However, in the above-mentioned conventional liquid discharge device, there is room for further suppressing oxygen inhibition at the end of the nozzle row.

Therefore, an object of the present invention is to provide a liquid discharge device capable of suppressing oxygen inhibition at the end of a row of nozzles and an image recording device including the liquid discharge device.

The liquid ejection device of the present invention is a liquid ejection device that cures ultraviolet curable ink ejected onto a printed matter by ultraviolet rays, and a nozzle row including a plurality of nozzles arranged side by side in the sub-scanning direction is formed in the sub-scanning direction. A chip row having at least one row in the main scanning direction, which is a direction orthogonal to the main scanning direction, and including a discharge head moving in the main scanning direction and a plurality of light emitting diode chips arranged side by side in the sub scanning direction is provided in the main scanning direction. The light emitting device per unit length in the sub-scanning direction at the end of the sub-scanning direction in at least one of the chip rows. The chip density, which is the number of diode chips, is higher than the chip density in the central portion in the sub-scanning direction, the illuminance at the end portion is higher than the illuminance at the central portion, and the end portion of the nozzle row. It includes at least one light emitting diode chip located outside the sub-scanning direction with respect to the nozzle located at the end of the nozzle.

According to the present invention, the chip density at the end in the sub-scanning direction is higher than the chip density at the center thereof, and the illuminance at the end in the sub-scanning direction is higher than the illuminance at the center thereof. Oxygen inhibition in In particular, in the present invention, since at least one light emitting diode chip is arranged outside the nozzle located at the nozzle end in the sub-scanning direction, the illuminance at the end in the sub-scanning direction is surely higher than the illuminance at the center thereof. can do. As a result, oxygen inhibition at the end of the nozzle row can be suppressed more than before.

According to the present invention, it is possible to provide a liquid discharge device capable of suppressing oxygen inhibition at the end of a row of nozzles and an image recording device including the liquid discharge device.

It is a perspective view which shows the image recording apparatus which concerns on 1st Embodiment of this invention. It is a top view which shows the arrangement example of the discharge head and the ultraviolet irradiation apparatus mounted on the carriage of FIG. It is a block diagram which shows the structure of the image recording apparatus of FIG. It is a bottom view which shows the arrangement example of the nozzle row in the discharge head of FIG. 1 and the light emitting diode chip in an ultraviolet irradiation apparatus. It is a figure which shows schematic the internal structure of the ultraviolet irradiation apparatus. It is a figure which shows the high gap and the low gap. (A) is a diagram for explaining an example of an end arrangement pitch and an adjacent arrangement pitch, and (b) is a diagram for explaining another example of an end arrangement pitch and an adjacent arrangement pitch. It is a figure which shows the light emitting diode chip arranged in the end arrangement pitch and the adjacent arrangement pitch in Comparative Example 1 and Examples 1-5. 3 is a graph showing the relationship between the position in the sub-scanning direction and the illuminance in the nozzle row corresponding to Comparative Examples 1 and 1 to 5 in FIG. 8 obtained by simulation. It is a figure which shows the light emitting diode chip arranged in the end arrangement pitch and the adjacent arrangement pitch in Comparative Example 2 and Example 6 to Example 12. 3 is a graph showing the relationship between the position in the sub-scanning direction and the illuminance in the nozzle row corresponding to Comparative Example 2 and Examples 6 to 12 in FIG. 10 obtained by simulation.

Hereinafter, the liquid discharge device according to the embodiment of the present invention and the image recording device including the liquid discharge device will be described with reference to the drawings. The liquid discharge device and the image recording device described below are only one embodiment of the present invention. Therefore, the present invention is not limited to the following embodiments, and additions, deletions, and changes can be made without departing from the spirit of the present invention.

FIG. 1 is a perspective view showing an image recording device 1 according to an embodiment of the present invention. In FIG. 1, the directions orthogonal to each other are the vertical direction, the horizontal direction, and the front-rear direction. The left-right direction is the main scanning direction Ds described later, and the front-rear direction is the sub-scanning direction Df described later. The image recording device 1 not only prints on a printed matter W such as printing paper, but also prints goods printed on a printed matter W (FIG. 6) such as resin such as goods to be printed on various goods. be.

As shown in FIG. 1, the image recording device 1 of the present embodiment includes a housing 2, a carriage 3, an operation key 4, a display unit 5, a platen 6, and an upper cover 7. Further, the image recording device 1 includes the control unit 19 shown in FIG.

The housing 2 is formed in a box shape. The housing 2 has an opening 2a on the front surface and an opening (not shown) on the back surface. An operation key 4 is provided at a position on the right front side of the housing 2. A display unit 5 is provided at a position behind the operation key 4. The operation key 4 accepts an operation input by the user. The display unit 5 is composed of, for example, a touch panel and displays predetermined information. A part of the display unit 5 also functions as an operation key at a predetermined timing. The control unit 19 realizes a printing function based on an input from the operation key 4 or an external input via a communication interface (not shown) and controls the display of the display unit 5.

The carriage 3 is configured to be reciprocating along the main scanning direction Ds. As shown in FIG. 2, a liquid discharge device 50 is mounted on the carriage 3. The liquid discharge device 50 includes two discharge heads 10 (10A, 10B) and two ultraviolet irradiation devices 40 (40A, 40B). As the ejection head 10, for example, an inkjet head that ejects ultraviolet curable ink can be used. Further, the ultraviolet irradiation device 40 has a plurality of light emitting diode chips DT (FIG. 4) that emit ultraviolet rays, and irradiates ultraviolet rays for curing the ink ejected by the ejection head 10. The discharge head 10A and the discharge head 10B are arranged side by side along the sub-scanning direction Df. The discharge head B is arranged in front of the discharge head A. Further, the ultraviolet irradiation device 40A and the ultraviolet irradiation device 40B are arranged side by side along the sub-scanning direction Df. The ultraviolet irradiation device 40B is arranged in front of the ultraviolet irradiation device 40A. Further, the discharge head 10A and the ultraviolet irradiation device 40A are arranged side by side along the main scanning direction Ds. The ultraviolet irradiation device 40A is arranged on the right side of the discharge head 10A. Further, the discharge head 10B and the ultraviolet irradiation device 40B are arranged side by side along the main scanning direction Ds. The ultraviolet irradiation device 40B is arranged on the right side of the discharge head 10B.

Here, in FIG. 2, the carriage 3 moves to the left of the main scanning direction Ds during one pass in the printing process. As a result, the ejection head 10 and the ultraviolet irradiation device 40 move to the left during the printing process. In this case, the ejection head 10 ejects ink to the printed matter W while moving to the left of the main scanning direction Ds, and the ultraviolet irradiation device 40 moves to the left of the main scanning direction Ds and lands on the printed matter W. Is irradiated with ultraviolet rays. As a result, since the ultraviolet irradiation device 40 is positioned behind the ejection head 10 in the moving direction of the carriage 3 during the printing process, it is possible to irradiate the ink immediately after landing on the printed matter W with ultraviolet rays. ..

Further, when one pass of the printing process is completed, the carriage 3 moves to the right of the main scanning direction Ds and returns to a predetermined position in the main scanning direction Ds. As a result, the discharge head 10 and the ultraviolet irradiation device 40 move to the right in the main scanning direction Ds. In this case, the ejection head 10 moves to the right of the main scanning direction Ds without ejecting the ink, and the ultraviolet irradiation device 40 moves to the right of the main scanning direction Ds without ejecting the ink with respect to the ink ejected during the printing process. And irradiate with ultraviolet rays. As a result, the ink can be sufficiently irradiated with ultraviolet rays, and the curability of the ink can be improved.

In the present embodiment, the ejection head 10A ejects inks of each color of yellow (Y), magenta (M), cyan (C), and black (K), which are sometimes collectively referred to as color inks. The ejection head 10A is provided with nozzle rows NL for ejecting each of these inks extending along the sub-scanning direction Df. Each nozzle row NL is provided at regular intervals along the main scanning direction Ds. The arrangement order of each nozzle row NL in the main scanning direction Ds is as shown in FIG. 2, the nozzle row NL for ejecting yellow (Y) color ink and the nozzle row for ejecting magenta (M) color ink from the left side. The order is not limited to NL, the nozzle row NL for ejecting cyan (C) color ink, and the nozzle row NL for ejecting black (K) color ink, and can be set as appropriate.

On the other hand, the ejection head 10B ejects white (W) ink and clear (Cr) ink. The ejection head 10B is provided with nozzle rows NL for ejecting each of these inks extending along the sub-scanning direction Df. Each nozzle row NL is provided at regular intervals along the main scanning direction Ds. The interval in the main scanning direction Ds of each nozzle row NL in the discharge head 10B may be different from the interval in the main scanning direction Ds of each nozzle row NL in the discharge head 10A (example of FIG. 2), or may be the same. .. The arrangement order of each nozzle row NL in the main scanning direction Ds is as follows: a nozzle row NL that ejects white (W) color ink from the left side as shown in FIG. 2, and a nozzle that ejects clear (K) color ink. The order is not limited to the column NL, and the columns can be arranged in reverse. A color image is printed on the printed matter W by ejecting the above six colors of ink onto the printed matter W. Specifically, when a color image is printed on the cloth as the object to be printed W, white ink is first ejected as the base ink in order to reduce the influence on the color of the cloth and the material of the cloth, and the white is white. Color ink is ejected on top of the ink. The clear ink is ejected when giving gloss or protecting the printed portion.

The platen 6 is configured so that the printed matter W can be placed on it. The platen 6 has a predetermined thickness, and is composed of, for example, a rectangular plate material having the sub-scanning direction Df as the longitudinal direction. The platen 6 is detachably supported by a platen support base (not shown). The platen support base is configured to be movable between a printing position for executing printing on the printed matter W and a attachment / detachment position for removing the printed matter W from the platen 6. The printing position is a position where the platen 6 faces the discharge head 10, and the attachment / detachment position is a position where the platen support base is arranged outside the housing 2, and the printed matter W is placed on the platen 6. It is a possible position. At the time of printing, the platen 6 moves in the sub-scanning direction Df, so that the printed matter W placed on the platen 6 is conveyed in the sub-scanning direction Df.

The upper cover 7 is configured to rotate upward with a rotatably configured base end as a fulcrum when the front portion thereof is lifted. As a result, the inside of the housing 2 is exposed.

Next, the functions of each configuration of the image recording device 1 of the present embodiment will be described with reference to the block diagram. As shown in FIG. 3, in the image recording device 1 of the present embodiment, in addition to the above-mentioned components, the motor driver ICs 30 and 31, the head driver ICs 32 and 36, the conveyor motor 33, the carriage motor 34, and the irradiation device drivers ICs 37 and 38 , An internal power supply 15, and a power receiving unit 16. The image recording device 1 includes an ink tank (not shown) for storing ink to be supplied to the ejection head 10.

The control unit 19 includes a CPU 20, a storage unit (ROM21, RAM22, EEPROM23, HDD24), and an ASIC25. The CPU 20 is a control unit of the image recording device 1, is connected to the storage unit, and controls the drivers ICs 30 to 32, 36 to 38 and the display unit 5.

The CPU 20 executes various functions by executing a predetermined program stored in the ROM 21. The CPU 20 may be mounted on the control unit 19 as one processor, or may be mounted as a plurality of processors that cooperate with each other.

The ROM 21 stores a print control program for the CPU 20 to execute the print process. The calculation result of the CPU 20 is stored in the RAM 22. Various initial setting information input by the user is stored in the EEPROM 23. Specific information and the like are stored in the HDD 24. This specific information is highly confidential information that is not preferably leaked to the outside. For example, information about a user, job data including a user ID received from the outside by the image recording device 1 and specifying a source, and a user in the job data. It includes user usage history information including an ID, secure job data including a password and data related to the secure job, print history, cloud setting data, and the like. The information about the user includes, for example, telephone directory information, e-mail address information, image recording device 1 administrator (security administrator) information, network setting information, and the like. When the image recording device 1 receives the job data, the CPU 20 stores the user usage history information including the user ID in the job data in the HDD 24.

The motor driver ICs 30 and 31, the head driver ICs 32 and 36, and the irradiation device drivers ICs 37 and 38 are connected to the ASIC 25. When the CPU 20 receives a print job from the user, the CPU 20 outputs a print command to the ASIC 25 based on the print control program. The ASIC 25 drives the driver ICs 30 to 32 and 36 to 38 based on the print command. The CPU 20 drives the transfer motor 33 by the motor driver IC 30, so that the platen 6 moves in the sub-scanning direction Df, and the printed matter W is conveyed. Further, the CPU 20 drives the carriage motor 34 by the motor driver IC 31 to move the carriage 3. Further, the CPU 20 ejects ink from the ejection head 10 mounted on the carriage 3 moved by the head drivers ICs 32 and 36, and causes the conveyed object W to print the image data. Further, the CPU 20 irradiates the ultraviolet irradiation devices 40A and 40B with ultraviolet rays for curing the ink by the irradiation device drivers ICs 37 and 38. The printing process is performed in this flow.

The internal power supply 15 is provided at a predetermined position in the housing 2. The internal power supply 15 enables the control unit 19 to operate when the main body power supply of the image recording device 1 is in the OFF state. The internal power source 15 is, for example, a secondary battery. Further, the power receiving unit 16 is provided so as to be exposed to the outside from the housing 2, and receives power from an external power source. When the main body power is on, power from the outside is supplied to each part of the image recording device 1 via the power receiving part 16. Regardless of the state of the main body power supply, power from the outside is supplied to the internal power supply 15 via the power receiving unit 16, and the internal power supply 15 is charged by this power.

Subsequently, the arrangement of the plurality of light emitting diode chips DT in the ultraviolet irradiation device 40 of the present embodiment will be described. In the present embodiment, the light emitting diode chip DT is a semiconductor element that generates ultraviolet rays. Although the ultraviolet irradiation device 40A and the discharge head 10A will be typically described below, the ultraviolet irradiation device 40B and the discharge head 10B can be configured in the same manner as the ultraviolet irradiation device 40A and the discharge head 10A.

As shown in FIG. 4, the ultraviolet irradiation device 40A includes a support substrate 41 formed in a rectangular shape, for example, in a plan view. The support substrate 41 is, for example, an aluminum substrate. The support substrate 41 may be formed of another metal such as copper. Each light emitting diode chip DT is arranged on the support substrate 41.

In each light emitting diode chip DT, when the ink is irradiated with ultraviolet rays, the photopolymerization initiator contained in the ink reacts, the monomers contained in the ink are polymerized, and the ink is fixed on the printed matter W. Each light emitting diode chip DT is arranged in a matrix. Each light emitting diode chip DT is arranged, for example, with reference to the center of a rectangular unit cell having sides along the longitudinal direction and the lateral direction of the support substrate 41. As a result, the light emitting diode chips DT are arranged at regular intervals along the main scanning direction Ds and at regular intervals along the sub scanning direction Df. Therefore, each light emitting diode chip DT is arranged along the row direction parallel to the main scanning direction Ds and the column direction parallel to the sub scanning direction Df. FIG. 4 shows an example in which there are 11 rows of light emitting diode chip DTs arranged in the left-right direction and 5 columns of light emitting diode chips DT arranged in the front-rear direction. A group of a plurality of light emitting diode chips DT arranged side by side at regular intervals along the sub-scanning direction Df is referred to as a chip row DL. Therefore, FIG. 4 shows an example in which five chip rows DL are arranged. The number of light emitting diode chip DTs arranged on the support substrate 41 is not limited to the above, and is determined based on the integrated light amount and power consumption in one pass.

As described above, the discharge head 10A is provided with four nozzle rows NL. Each nozzle row NL includes a plurality of nozzles Nz arranged side by side at regular intervals along the sub-scanning direction Df. The ink is ejected from the nozzle Nz. In each nozzle row NL, the distance from the nozzle Nz located at the front end of the sub-scanning direction Df to the nozzle Nz located at the rear end of the sub-scanning direction Df is defined as the nozzle length Lh. Note that FIG. 4 shows only the nozzle row NL that ejects black (K) ink, and the other three nozzle rows are omitted.

Each light emitting diode chip DT of the ultraviolet irradiation device 40A is arranged so that the light emitting region of ultraviolet rays by the light emitting diode chip DT is larger than the nozzle row NL in the sub-scanning direction Df. As a result, the length of each chip row DL in the sub-scanning direction Df, that is, the light-emitting diode chip DT located at the front end of the sub-scanning direction Df in each chip row DL to the light-emitting diode chip located at the rear end of the sub-scanning direction Df. When the distance to the DT is the light emitting length Ld, this light emitting length Ld can be made larger than the nozzle length Lh. Therefore, it is possible to satisfactorily irradiate the ink droplets ejected from the nozzles Nz located at the front end and the rear end of the nozzle row NL with ultraviolet rays.

The light emitting diode chips DT are arranged side by side at a predetermined pitch in the main scanning direction Ds. The arrangement pitch of each light emitting diode chip DT in the sub-scanning direction Df will be described later.

Next, the heat dissipation structure of the ultraviolet irradiation device 40 will be described. FIG. 5 is a diagram schematically showing the internal configuration of the ultraviolet irradiation device 40. As shown in FIG. 5, the ultraviolet irradiation device 40 includes the above-mentioned support substrate 41 that supports a plurality of light emitting diode chip DTs, and a surface (lower surface) of the surfaces of the support substrate 41 on which a plurality of light emitting diode chip DTs are provided. It is provided with a plate-shaped heat sink 42 provided on a surface (upper surface) opposite to the above. The heat sink 42 includes a base portion 42a arranged on the support substrate 41 and a plurality of heat radiating plates (fins) 42b extending upward on the base portion 42a. The heat sinks 42b are arranged at equal intervals. Further, electronic components (not shown) are provided on the lower surface of the support substrate 41, and a plurality of electrodes 45 are provided on these electronic components corresponding to each light emitting diode chip DT. Each light emitting diode chip DT is electrically connected to each electrode 45. The lower surface of the support substrate 41 is covered with the insulating film 44 with a part of each electrode 45 exposed. In such a configuration, the heat generated by each light emitting diode chip DT is dissipated upward via the heat sink 42.

The image recording apparatus 1 of the present embodiment can print on a printed matter in a low gap and a high gap. As shown in FIG. 6, the printed matter W has, for example, a lower portion T1 in which the distance from the ultraviolet irradiation surface TS of the light emitting diode chip DT is a high gap GH, and a distance from the ultraviolet irradiation surface TS is larger than that in the high gap GH. Includes a high portion T2 that results in a small low gap GL. The high gap GH is, for example, 18 mm. The low gap GL is, for example, 2 mm.

Subsequently, the arrangement pitch of each light emitting diode chip DT in the sub-scanning direction Df will be described with reference to the drawings.

In the present embodiment, in at least one chip row DL (for example, all chip row DLs), the chip density which is the number of light emitting diode chip DTs per unit length of the sub-scanning direction Df at the end of the sub-scanning direction Df. Is higher than the chip density at the center of the sub-scanning direction Df. The end portion of the sub-scanning direction Df is a region outside the sub-scanning direction Df with respect to the nozzle end. Further, in at least one chip row DL (for example, all chip row DLs), the illuminance at the end of the sub-scanning direction Df is higher than the illuminance at the center. Further, at least one chip row DL, for example, all chip row DLs, has at least one light emitting diode chip located outside the sub-scanning direction Df with respect to the nozzle Nz located at the nozzle end, which is the end of the nozzle row NL. DT is included respectively. Hereinafter, a detailed description will be given.

In FIG. 7A, the light emitting diode chip DT closest to the nozzle end in the sub-scanning direction Df is referred to as the end light emitting diode chip DTt. In the example of FIG. 7A, the position of the end light emitting diode chip DTt in the sub-scanning direction Df is the same as the position of the nozzle end in the sub-scanning direction Df. The arrangement pitch with the light emitting diode chip DT adjacent to at least one side (both sides in the example of FIG. 7A) of the outer side and the inner side of the sub-scanning direction Df with respect to such an end light emitting diode chip DTt is set to the end. The part arrangement pitch Pt is used. Further, the arrangement pitch of the light emitting diode chip DT located inside the end light emitting diode chip DTt and the light emitting diode chip DT located further inside the light emitting diode chip DT is defined as the adjacent arrangement pitch Pr. At this time, the end arrangement pitch Pt is smaller than the adjacent arrangement pitch Pr. In this way, at least one chip row DL in which the end arrangement pitch Pt is smaller than the adjacent arrangement pitch Pr is provided. With such a configuration, the chip density of the light emitting diode chip DT at the end of the sub-scanning direction Df is higher than the chip density at the center thereof. Further, as shown in the figure, at least one chip row DL has at least one light emitting diode chip DT located outside the sub-scanning direction Df with respect to the nozzle Nz located at the nozzle end, which is the end of the nozzle row NL. Is included. In the example of FIG. 7A, there is only one light emitting diode chip DT located on the outer side. With the above configuration, in at least one chip row DL, the illuminance at the end of the sub-scanning direction Df is higher than the illuminance at the center.

Further, as shown in FIG. 7B, as the end light emitting diode chip DTt, the light emitting diode chip DT closest to the nozzle end is adopted even if it is not the same as the position of the nozzle end in the sub-scanning direction Df. May be good. Also in the example of FIG. 7B, there is only one light emitting diode chip DT located on the outside.

A specific example of the arrangement of the light emitting diode chip DT in the present embodiment will be described based on the configurations of FIGS. 7 (a) and 7 (b) described above.

FIG. 8 shows the arrangement of the light emitting diode chip DTs in Comparative Examples 1 and 5 (Examples 1 to 5). In FIG. 8, only the arrangement (upper arrangement) of the light emitting diode chip DT in the region from one nozzle end to the center in the nozzle row NL is shown, and the light emitting diode chip in the region from the other nozzle end to the center is shown. Since the arrangement of the DT is the same as the above-mentioned upper arrangement, it is omitted.

Comparative Example 1 is an embodiment in which the light emitting diode chip DT located outside the sub-scanning direction Df from the nozzle end does not exist. In Comparative Example 1, the arrangement pitch between the adjacent light emitting diode chips DT is set to 4.5 mm.

On the other hand, in the first and second embodiments, there is one light emitting diode chip DT located outside the sub-scanning direction Df from the nozzle end. In the first embodiment, the arrangement pitch between the adjacent light emitting diode chips DT is set to 4.5 mm. That is, the end arrangement pitch Pt and the adjacent arrangement pitch Pr are the same. On the other hand, in the second embodiment, only the rear end arrangement pitch Pt is set to 4 mm, and the front end arrangement pitch Pt and the adjacent arrangement pitch Pr are set to 4.5 mm.

Further, in Examples 3 to 5, there are two light emitting diode chips DTs located outside the sub-scanning direction Df from the nozzle end. In the third embodiment, the arrangement pitch between the adjacent light emitting diode chips DT is set to 4.5 mm. That is, the end arrangement pitch Pt and the adjacent arrangement pitch Pr are the same. Further, in the fourth embodiment, the rear end arrangement pitch Pt, the front end arrangement pitch Pt, and the adjacent arrangement pitch Pr are set to 4.5 mm, and are located on the rear side of the end light emitting diode chip DTt. The arrangement pitch of the light emitting diode chip DT and the light emitting diode chip DT adjacent to the light emitting diode chip DT is 4 mm. On the other hand, in the fifth embodiment, the front end arrangement pitch Pt and the adjacent arrangement pitch Pr are set to 4.5 mm, and the rear end arrangement pitch Pt and the end light emitting diode chip DTt are located on the rear side. The arrangement pitch of the light emitting diode chip DT and the light emitting diode chip DT adjacent thereto is 4 mm.

Using each of the aspects of Comparative Example 1 and Examples 1 to 5, the relationship between the position of the sub-scanning direction Df and the illuminance in the nozzle row NL was obtained by simulation. FIG. 9 is a graph showing the relationship between the position of the sub-scanning direction Df and the illuminance in the nozzle row NL, which corresponds to Comparative Example 1 and Examples 1 to 5 of FIG. As shown in FIG. 9, in Comparative Example 1, the illuminance at the nozzle end was clearly lower than the illuminance at the central portion. On the other hand, in Examples 1 to 5, the illuminance at the nozzle end was equal to or higher than the illuminance at the central portion. In particular, in Example 5, the illuminance at the nozzle end was significantly higher than the illuminance at the central portion. Then, in Example 5, the maximum illuminance (peak illuminance) appeared in the region outside the sub-scanning direction Df (on the left side of the nozzle end in FIG. 9) from the nozzle end. In the present embodiment, the difference between the illuminance at the nozzle end and the illuminance at the center portion is, for example, 0.1 w / cm ² or more.

Next, another specific example of the arrangement of the light emitting diode chip DT in this embodiment will be described.

FIG. 10 shows the arrangement of the light emitting diode chip DTs in Comparative Examples 2 and 7 (Examples 6 to 12). Note that, in FIG. 10, as in FIG. 8, only the arrangement (upper arrangement) of the light emitting diode chip DT in the region from one nozzle end to the center in the nozzle row NL is shown, and the other nozzle end to the center is shown. Since the arrangement of the light emitting diode chip DT in the regions up to is the same as the above-mentioned upper arrangement, it is omitted.

Comparative Example 2 is an embodiment in which the light emitting diode chip DT located outside the sub-scanning direction Df from the nozzle end does not exist. In Comparative Example 2, the array pitches between the adjacent light emitting diode chips DT are all 6.0 mm.

On the other hand, the sixth embodiment is an embodiment in which one light emitting diode chip DT located outside the sub-scanning direction Df from the nozzle end exists. In the sixth embodiment, the array pitch between the adjacent light emitting diode chips DT is set to 6.0 mm. That is, the end arrangement pitch Pt and the adjacent arrangement pitch Pr are the same.

Further, in Examples 7 to 10, there are two light emitting diode chips DTs located outside the sub-scanning direction Df from the nozzle end. In the seventh embodiment, the array pitch between the adjacent light emitting diode chips DT is set to 6.0 mm. That is, the end arrangement pitch Pt and the adjacent arrangement pitch Pr are the same. On the other hand, in the eighth embodiment, all the remaining arrangement pitches are 6 except that the arrangement pitch of the light emitting diode chip DT located on the rear side of the end light emitting diode chip DTt and the light emitting diode chip DT adjacent thereto is 4 mm. It is set to 0.0 mm. That is, the rear end arrangement pitch Pt, the front end arrangement pitch Pt, and the adjacent arrangement pitch Pr are the same. Further, in the ninth embodiment, the arrangement pitch of the light emitting diode chip DT located on the rear side of the end light emitting diode chip DTt and the light emitting diode chip DT adjacent thereto and the rear end arrangement pitch Pt are set to 4 mm. Other than that, the remaining array pitch is set to 6.0 mm. That is, the front end arrangement pitch Pt and the adjacent arrangement pitch Pr are the same. Further, in the tenth embodiment, except that the rear end arrangement pitch Pt and the front end arrangement pitch Pt are 4.0 mm, the residual arrangement pitch including the adjacent arrangement pitch Pr is all 6.0 mm. ..

Further, the eleventh embodiment is an embodiment in which one light emitting diode chip DT located outside the sub-scanning direction Df from the nozzle end is present. In the eleventh embodiment, all the remaining arrangement pitches are 6.0 mm except that the rear end arrangement pitch Pt is 4.0 mm. That is, the front end arrangement pitch Pt and the adjacent arrangement pitch Pr are the same. Further, the twelfth embodiment is an embodiment in which two light emitting diode chips DTs located outside the sub-scanning direction Df from the nozzle end are present. In the twelfth embodiment, the arrangement pitch of the light emitting diode chip DT located on the rear side of the end light emitting diode chip DTt and the light emitting diode chip DT adjacent thereto, the rear end arrangement pitch Pt, and the front end. Except for the arrangement pitch Pt of 4.0 mm, all the remaining arrangement pitches including the adjacent arrangement pitch Pr are set to 6.0 mm.

Using each of the aspects of Comparative Example 2 and Examples 6 to 12, the relationship between the position of the sub-scanning direction Df in the nozzle row NL and the illuminance was obtained by simulation. FIG. 11 is a graph showing the relationship between the position of the sub-scanning direction Df and the illuminance in the nozzle row NL, which corresponds to Comparative Example 2 and Examples 6 to 12 of FIG. As shown in FIG. 11, in Comparative Example 2, the illuminance at the nozzle end was clearly lower than the illuminance at the central portion. On the other hand, in Examples 6 to 12, the illuminance at the nozzle end was equal to or higher than the illuminance at the central portion. In particular, in Examples 9 to 12, the illuminance at the nozzle end was significantly higher than the illuminance at the central portion. Then, in Examples 7, 8, 9, and 11, the maximum illuminance appeared in the region outside the sub-scanning direction Df (on the left side of the nozzle end in FIG. 11) from the nozzle end.

As described above, according to the liquid discharge device 50 of the present embodiment, the chip density at the end of the sub-scanning direction Df is higher than the chip density at the center, and the illuminance at the end of the sub-scanning direction Df is at the center. By having a higher illuminance than the illuminance at the portion, oxygen inhibition at the end of the nozzle row can be suppressed. In particular, since at least one light emitting diode chip DT is arranged outside the sub-scanning direction Df with respect to the nozzle Nz located at the nozzle end, the illuminance at the end of the sub-scanning direction Df is surely higher than the illuminance at the center thereof. can do. As a result, oxygen inhibition at the end of the nozzle row can be suppressed more than before.

Further, in the present embodiment, since the end arrangement pitch Pt is smaller than the adjacent arrangement pitch Pr, the chip density of the light emitting diode chip DT at the end portion in the sub-scanning direction Df is higher than the chip density at the central portion thereof. As a result, the illuminance at the end of the sub-scanning direction Df can be made higher than the illuminance at the center thereof.

Further, in the present embodiment, two light emitting diode chips DT can be arranged outside the sub-scanning direction Df with reference to the end light emitting diode chip DTt, and one of the two light emitting diode chips DT is a light emitting diode. The arrangement pitch of the chip DT and the other light emitting diode chip DT can be the same as the end arrangement pitch Pt. As a result, the illuminance at the end of the sub-scanning direction Df can be made higher than the illuminance at the center thereof.

Further, in the present embodiment, since the chip row DL includes the light emitting diode chip DT arranged at the same position as the nozzle end position in the sub-scanning direction Df, oxygen inhibition at the nozzle end is less likely to occur, and sufficient ink curing is performed. Sex can be ensured.

Further, in the present embodiment, the difference between the illuminance at the end portion of the sub-scanning direction Df (the region outside the sub-scanning direction Df from the nozzle end) and the illuminance at the central portion is 0.1 w / cm ² or more. , Oxygen inhibition in the region outside the sub-scanning direction Df from the nozzle end is less likely to occur, and sufficient ink curability can be more ensured.

Further, in the present embodiment, the maximum illuminance can be generated in a region outside the sub-scanning direction Df from the nozzle end. As a result, oxygen inhibition in a region outside the sub-scanning direction Df from the nozzle end is less likely to occur, and sufficient ink curability can be reliably ensured.

Further, by providing the above-mentioned liquid discharge device 50 in the image recording device 1, it is possible to suppress oxygen inhibition at the end of the nozzle row in the image recording device 1.

(Modification example)
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example:

In the above embodiment, in all the chip row DLs, the chip density of the light emitting diode chip DT at the end of the sub-scanning direction Df is higher than the chip density at the center thereof, but the chip density is not limited to this, for example. The above configuration may be adopted for only one chip row DL or for half of the chip row DLs.

Further, in the above embodiment, in all the chip row DLs, the illuminance at the end portion in the sub-scanning direction Df is higher than the illuminance at the central portion, but the illuminance is not limited to this, and for example, one row of chip row DLs. The above configuration may be adopted for only or half of the chip row DLs.

Further, in the above embodiment, in all the chip row DLs, there is at least one light emitting diode chip DT located outside the sub-scanning direction Df with respect to the nozzle Nz located at the nozzle end, which is the end of the nozzle row NL. However, the present invention is not limited to this, and for example, the above configuration may be adopted for only one row of chip row DLs or for half of the chip row DLs.

Further, in the above embodiment, the end arrangement pitch Pt is made smaller than the adjacent arrangement pitch Pr, but the present invention is not limited to this, and the end arrangement pitch Pt is set to the same value as the adjacent arrangement pitch Pr. , At least one light emitting diode chip DT may be configured to be located outside the sub-scanning direction Df with respect to the nozzle Nz located at the nozzle end.

Further, in the above embodiment, the high gap GH is set to 15 mm and the low gap GL is set to 2 mm, but the high gap GH and the low gap GL are not limited to the above values, and the low gap GL is higher than the high gap GH. Should be small. For example, the high gap GH is 7 mm or more, and the difference between the high gap GH and the low gap GL is 5 mm or more.

Further, in the above embodiment, the carriage 3 is provided with two discharge heads 10 (10A, 10B) and two ultraviolet irradiation devices 40 (40A, 40B), but the present invention is not limited to this, and the discharge head 10A and ultraviolet rays are not limited to this. Only the irradiation device 40A may be mounted.

1 Image recording device 3 Carriage 10, 10A, 10B Discharge head 40, 40A, 40B Ultraviolet irradiation device 50 Liquid discharge device Df Sub-scanning direction DL chip row Ds Main scanning direction Ds1 Outward route Ds2 Return route DT Light emitting diode chip DTt End light emitting diode chip NL Nozzle Row Nz Nozzle Pr Adjacent Arrangement Pitch Pt End Arrangement Pitch W Printed Material

Claims (8)

A liquid ejection device that cures ultraviolet-curable ink ejected onto printed matter with ultraviolet rays.
A discharge head having at least one row of nozzles including a plurality of nozzles arranged side by side in the sub-scanning direction in the main scanning direction, which is a direction orthogonal to the sub-scanning direction, and moving in the main scanning direction.
A chip row including a plurality of light emitting diode chips arranged side by side in the sub-scanning direction is provided in the main scanning direction, and an ultraviolet irradiation device that moves in the main scanning direction is provided.
In at least one of the chip rows
The chip density, which is the number of the light emitting diode chips per unit length in the sub-scanning direction at the end of the sub-scanning direction, is higher than the chip density at the center of the sub-scanning direction.
The illuminance at the end is higher than the illuminance at the center, and
A liquid discharge device including at least one light emitting diode chip located outside the sub-scanning direction with respect to the nozzle located at the nozzle end, which is the end of the nozzle row. The end light emitting diode chip, which is the light emitting diode chip closest to the nozzle end in the sub scanning direction, and the end light emitting diode chip are adjacent to at least one side of the outside and the inside of the sub scanning direction. The end arrangement pitch, which is the arrangement pitch with the light emitting diode chip, is the arrangement pitch of the light emitting diode chip located inside the end light emitting diode chip and the light emitting diode chip further inside the light emitting diode chip. The liquid discharge device according to claim 1, which is smaller than the adjacent arrangement pitch, which is the arrangement pitch. Two of the light emitting diode chips are arranged outside the sub-scanning direction with reference to the end light emitting diode chip, and one of the two light emitting diode chips and the other light emitting diode chip are arranged. The liquid discharge device according to claim 2, wherein the arrangement pitch with and is the same as the end arrangement pitch. The liquid discharge device according to any one of claims 1 to 3, wherein the chip row includes the light emitting diode chip arranged at the same position as the nozzle end position in the sub-scanning direction. The liquid discharge device according to any one of claims 1 to 4, wherein the difference between the illuminance at the end portion in the sub-scanning direction and the illuminance at the central portion in the sub-scanning direction is 0.1 w / cm ^{2 or more.} The liquid discharge device according to any one of claims 1 to 5, wherein the illuminance at the end in the sub-scanning direction includes the maximum illuminance. The liquid discharge device according to claim 6, wherein the end portion in the sub-scanning direction is a region outside the sub-scanning direction from the nozzle end. An image recording device including the liquid discharge device according to any one of claims 1 to 7 and a carriage provided with the liquid discharge device.

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