JP2011126250A - Ink-jet image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink-jet image forming apparatus capable of forming images that can improve flexibility in layout design and flexibility in design of other equipment at side face parts at both ends in the moving direction of a recording head. <P>SOLUTION: The ink-jet image forming apparatus 100 includes: a grid roll 102 conveying a recording medium WK on a platen 101; a recording head group 122 ejecting and sticking ink onto the surface of the recording medium WK while moving in a direction orthogonal to the conveyed direction of the recording medium WK; side UV light sources 122a, 123b arranged adjoining the recording head group 122 to accelerate curing of ink sticking to the surface of the recording medium WK while moving with the recording head group 122; and a front UV light source 124 arranged oppositely downstream in the conveyed direction of the recording medium WK to the recording head group 122 to accelerate curing of ink sticking onto the recording medium WK while moving with the recording head group 122. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ink jet image forming apparatus that forms a desired image on a recording medium by ejecting ink droplets onto the recording medium.

  Conventionally, ink droplets are ejected from a recording head while moving the recording head intermittently while moving the ink head in a direction (main scanning direction) orthogonal to the recording medium conveyance direction (sub-scanning direction). An ink jet image forming apparatus for forming an image, a so-called ink jet printer is known. Among such ink jet printers, there is an ink jet printer that forms a desired image using ink that is cured by receiving ultraviolet rays or infrared rays (hereinafter referred to as “ultraviolet curable ink” or “thermosetting ink”).

  For example, Patent Document 1 below discloses an ink jet printer that includes UV irradiation devices that irradiate ultraviolet rays on both sides of a recording head that discharges ultraviolet curable ink toward a recording medium. In such an ink jet printer, in order to cure the ink ejected onto the recording medium with certainty, the ultraviolet irradiation area by the UV irradiation device is set to a length that is at least twice the print width of the recording head. It is comprised so that an ultraviolet-ray can be irradiated 2 times or more with respect to.

JP 2004-1326 A

  However, in the ink jet printer as shown in Patent Document 1, UV irradiation devices are provided on both side surfaces of the recording head so as to protrude at a length that is twice or more the printing width of the recording head. For this reason, it is necessary to secure a space at both ends of the recording head in the moving direction for accommodating the UV irradiation devices protruding in the recording medium conveyance direction on both side surfaces of the recording head. There was a problem that the degree of freedom in layout design and the degree of freedom in design of other devices in the department was low.

  The present invention has been made to cope with the above-described problems, and an object of the present invention is to improve the degree of freedom in layout design and design of other devices on the side surfaces at both ends in the moving direction of the recording head. An object of the present invention is to provide an ink jet image forming apparatus capable of forming an image.

  In order to achieve the above object, a feature of the present invention according to claim 1 is that the recording medium conveying means for conveying the recording medium on the platen and the recording medium while moving in the direction orthogonal to the direction in which the recording medium is conveyed. In the ink jet image forming apparatus, comprising: a recording head that discharges and adheres ink to the surface of the recording medium; and an ink curing acceleration unit that accelerates curing of the ink adhered on the recording medium. It is provided with forward arrangement hardening promoting means provided in a movable state at a position downstream of the recording head in the recording medium conveyance direction along a direction inclined with respect to the recording medium conveyance direction. .

  According to the characteristic of the present invention according to claim 1 configured as described above, the inkjet image forming apparatus is movable in the same direction as the recording head and is downstream of the recording head in the conveyance direction of the recording medium. A forward arrangement hardening accelerating means is provided along a direction inclined with respect to the conveyance direction of the recording medium. That is, the forward arrangement curing promoting means is provided obliquely arranged in front of the recording head (downstream in the recording medium conveyance direction), and is provided so as to protrude downstream in the recording medium conveyance direction on both side surfaces of the recording head. It is not done. Thereby, it is not necessary to secure a space for accommodating the forward arrangement hardening promoting means protruding in the recording medium conveyance direction on both side surfaces of the recording head at both ends of the recording head in the moving direction. Further, compared with the ink jet image forming apparatus in the above conventional example, that is, the ink jet image forming apparatus in which the UV irradiation device is formed with a length more than twice the print width of the recording head along the conveyance direction of the recording medium. In addition, since the forward-setting curing promoting means is obliquely arranged, the mechanical structure of the recording head unit composed of the recording head and the UV irradiation device is made compact to reduce the size of the inkjet printer, reduce power consumption, and assemble / Maintenance work can be simplified. As a result, the degree of freedom in layout design and design freedom of other devices at both ends of the recording head in the moving direction is improved. In addition, the ink can be reliably cured by increasing the time for continuously irradiating light energy, and the quality of image formation can be improved.

  According to another aspect of the present invention according to claim 2, in the inkjet image forming apparatus, the ink curing accelerating means is disposed adjacent to the recording head and moves together with the recording head while the surface of the recording medium. The present invention has a laterally arranged curing accelerating means for accelerating the curing of the ink attached to the ink.

  According to another aspect of the present invention according to claim 2 configured as described above, the ink jet recording apparatus can cure the ink adhering to the surface of the recording medium adjacent to the recording head, in addition to the forward curing accelerating means. A lateral arrangement hardening accelerating means for promoting is provided. Accordingly, the ink curing process can be immediately performed on the ink adhered to the recording medium, and the width and accuracy of image formation accuracy can be improved. In this case, the mechanical configuration of the recording head unit can be kept compact by setting the length in the conveyance direction of the recording medium in the side curing promoting means to be less than twice the printing width of the recording head.

  According to a third aspect of the present invention, in the ink jet image forming apparatus, the laterally arranged curing promoting means is disposed adjacent to both sides of the recording head.

  According to another aspect of the present invention according to claim 2 configured as described above, the side-arrangement hardening promoting means is disposed adjacent to both sides of the recording head. For this reason, regardless of the moving direction of the recording head, the ink curing process can be immediately performed on the ink attached to the recording medium, and the width and accuracy of image formation accuracy can be improved.

  According to still another aspect of the present invention according to claim 4, in the ink jet image forming apparatus, the laterally arranged curing accelerating unit is configured such that the curing area in the recording medium conveyance direction has a single conveyance amount of the recording medium and recording. The total length with the ink ejection range of the head or the integral multiple of the transport amount of the recording medium at one time.

  According to another aspect of the present invention according to claim 4 configured as described above, the laterally arranged curing promoting means is configured such that the curing area in the recording medium conveyance direction has a single conveyance amount of the recording medium (so-called one pass). And the total length of the ink ejection range of the recording head, or an integral multiple of a single conveyance amount of the recording medium. In this case, the ink ejection range of the recording head is the ink ejection range of the recording head in the recording medium conveyance direction, in other words, the image formation range. According to this, the ink curing acceleration process is performed for each image forming area unit by the recording head, and the one curing process for the image on the same main scanning line is performed twice or more. Therefore, curing can be accelerated with high accuracy.

  Another feature of the present invention according to claim 5 is that, in the ink jet image forming apparatus, the arrangement curing promoting means and the side arrangement curing promoting means record the interval between the curing areas in the recording medium conveyance direction. That is, the length is equivalent to a single transport amount of media or an integral multiple of the transport amount.

  According to another aspect of the present invention according to claim 5 configured as described above, the distance between the curing region in the laterally arranged curing accelerating unit and the curing region in the forwardly arranged curing accelerating unit is a single conveyance amount of the recording medium or It is set to a length corresponding to an integral multiple of the carry amount. As a result, the curing process in the forward arrangement curing promoting unit is performed in units of one image forming area by the recording head, and one curing process for images on the same main scanning line is performed in two or more times. Therefore, curing can be accelerated with high accuracy.

  According to still another aspect of the present invention according to claim 6, in the ink jet image forming apparatus, the forward arrangement curing promoting unit is configured such that the curing area in the recording medium conveyance direction is a single conveyance amount of the recording medium or the same conveyance. The length is equivalent to an integral multiple of the quantity.

  According to another feature of the present invention according to claim 6 configured as described above, the forward arrangement curing promoting means is configured such that the curing area in the recording medium conveyance direction is a single conveyance amount of the recording medium or an integer of the conveyance amount. It is set to a length corresponding to double. According to this, the ink curing acceleration process is performed for each image forming area unit by the recording head, and the one curing process for the image on the same main scanning line is performed twice or more. Therefore, curing can be accelerated with high accuracy.

  Another feature of the present invention according to claim 7 is that, in the ink jet image forming apparatus, the recording head ejects ink that is cured when irradiated with ultraviolet rays or infrared rays onto a recording medium, and accelerates the forward arrangement curing. The means and the laterally arranged curing promoting means each include a light source that irradiates light including ultraviolet rays or infrared rays, and the forwardly arranged curing accelerating means irradiates light having a wavelength longer than the light emitted from the laterally arranged curing accelerating means. There is to do.

  In this case, as shown in claim 8, in the ink jet image forming apparatus, for example, the laterally arranged curing promoting means includes a light source that irradiates ultraviolet light having a wavelength of 365 nm, and the forwardly arranged curing promoting means has a wavelength of A light source that irradiates ultraviolet rays of 400 nm may be provided.

  According to the other characteristic of this invention which concerns on Claim 7 comprised in this way, a front arrangement | positioning hardening acceleration | stimulation means irradiates the light ray of a wavelength longer than the light ray irradiated from a side arrangement | positioning hardening acceleration | stimulation means. According to this, the ink ejected onto the recording medium is accelerated on the ink surface by the light having a short wavelength irradiated from the side-arranged curing accelerating means. Then, the ink on the recording medium transported to the front arrangement / curing acceleration means side is accelerated in the ink by a long wavelength light beam irradiated from the front arrangement / curing acceleration means. As a result, the ink droplets ejected on the recording medium can be cured with high accuracy, and the image forming accuracy can be improved.

  According to a ninth aspect of the present invention, in the inkjet image forming apparatus, the image forming apparatus further includes output control means for controlling an output of the lateral arrangement curing promoting means, and the output control means When the first laterally arranged curing accelerating means passes through the ink attached to the surface, the output of the laterally arranged curing accelerating means is controlled to be less than the output suitable for curing the ink.

  In this case, in the ink jet image forming apparatus, for example, the output control means may set the output of the lateral arrangement hardening accelerating means to an output of about 10% of the optimum output for the ink curing.

  According to another aspect of the present invention according to claim 9 configured as described above, the output control means is configured to cure the lateral arrangement when the first lateral arrangement hardening acceleration means passes through the ink adhering to the surface of the recording medium. The output of the accelerating means is controlled to be less than the optimum output for curing the ink ejected on the recording medium. As a result, the ink droplets ejected on the recording medium are further spread on the recording medium because the progress of curing is slower than at the time of output optimum for curing the ink. As a result, it is possible to accurately form an image to be filled or an image having a low resolution.

  According to a tenth aspect of the present invention, in the ink jet image forming apparatus, the output control means further includes the step of until the ink attached to the surface of the recording medium finishes passing through the laterally arranged curing promoting means. This is to stop the output of the side-position hardening promoting means.

  According to another aspect of the present invention according to claim 10 configured as described above, the output control means is configured so that the ink arranged on the surface of the recording medium is disposed on the same side until the ink passing through the side-position hardening promoting means is finished. Stop the output of the promotion means. In other words, the ink set acceleration process is executed only by the front arrangement curing promotion unit without performing the curing promotion process by the side arrangement curing promotion unit for the ink deposited on the recording medium. As a result, the start of the ink curing process for the ink adhering to the recording medium is delayed, so that the ink curing promoting process is performed by the front-position curing promoting means when the inks adjacent to each other on the recording medium become familiar with each other. . As a result, it is possible to widen the range of variations in image formation, for example, it is possible to accurately form glossy texture images when using transparent ink.

1 is an external perspective view showing an entire inkjet image forming apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram of a control system that controls the operation of the ink jet image forming apparatus shown in FIG. 1. FIG. 2 is a plan view schematically showing a configuration of a main part of a recording head unit provided in the ink jet image forming apparatus shown in FIG. 1. FIGS. 4A to 4C are explanatory diagrams schematically showing an image forming process mainly by the recording head unit shown in FIG. (A)-(C) are explanatory drawings which show typically the ultraviolet irradiation process by the front UV light source of the recording head unit mainly shown in FIG. FIG. 9 is a plan view schematically showing a configuration of a main part of a recording head unit according to a modified example of the invention. FIG. 10 is a plan view schematically showing a configuration of a main part of a recording head unit according to another modified example of the invention.

(Configuration of Inkjet Image Forming Apparatus 100)
Hereinafter, an embodiment of an ink jet image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view showing the entire inkjet image forming apparatus 100 according to the present invention. FIG. 2 is a block diagram of a control system for controlling the operation of the inkjet image forming apparatus 100. Note that each drawing referred to in the present specification is schematically represented by exaggerating some of the components in order to facilitate understanding of the present invention. For this reason, the dimension, ratio, etc. between each component may differ. The image forming apparatus 100 is a so-called inkjet printer that forms an image of a desired character, symbol, figure, or the like by attaching ink to the surface of a sheet-like recording medium WK that is an image formation target.

  The image forming apparatus 100 includes a platen 101 having a flat portion arranged in a horizontal state. The platen 101 is a mounting table on which the recording medium WK is mounted on the flat portion, and is formed to extend in the horizontal direction in the figure. A cylindrical grid roller 102 is provided at the center of the platen 101 along the horizontal direction in the drawing with its upper surface exposed. The grid roller 102 is rotationally driven by an X-axis direction feed motor 103 whose operation is controlled by a controller 130 described later.

  A long guide rail 104 is provided above the platen 101 so as to be parallel to the platen 101. Under the guide rail 104, four pinch rollers 105 each having a cylindrical portion facing the grid roller 102 are provided at substantially equal intervals. The grid roller 102 and the pinch roller 105 convey the sheet-like recording medium WK in the front-rear direction shown in the figure while being sandwiched from the upper side in the figure. Note that the front-rear direction (X-axis direction) in the drawing in which the recording medium WK is conveyed is the sub-scanning direction, and the left-right direction (Y-axis direction) orthogonal to the X-axis direction is the main scanning direction.

  The guide rail 104 supports the recording head unit 120 via the linear motion rail 106 and the linear motion block 107. The linear motion rail 106 is a single rail fixed to the guide rail 104 along the main scanning direction (Y-axis direction in the drawing). The linear motion block 107 is a moving body that slides along the linear motion rail 106, and is fixed to the back surface of the recording head unit 120. That is, the recording head unit 120 is guided in the main scanning direction along the linear motion rail 106 (guide rail 104).

  A part of the drive belt 108 laid in the main scanning direction (Y-axis direction in the drawing) is fixed to the upper back of the recording head unit 120. The drive belt 108 is connected to a Y-axis direction scan motor 109 whose drive is controlled by the controller 130, and moves in the main scanning direction by the rotational drive of the Y-axis direction scan motor 109. That is, the recording head unit 120 moves in the main scanning direction by driving the Y-axis direction scanning motor 109 via the driving belt 108.

  In FIG. 1, the recording head unit 120 is shown in a standby position in the Y-axis direction. The standby position in the Y-axis direction of the recording head unit 120 is an origin position that serves as a reference for the movement of the recording head unit 120 in the Y-axis direction. Therefore, when the image forming apparatus 100 is activated or when printing on the recording medium WK is not performed, the recording head unit 120 stands by at this standby position.

  On the other hand, above the recording head unit 120, a long upper cover 110 that constitutes an upper casing of the image forming apparatus 100 is provided. Further, side covers 111R and 111L that constitute a housing on both sides of the image forming apparatus 100 are provided on both sides of the platen 101 and the upper cover 110, respectively. Among these, on the front surface of the side cover 111R, there is provided an operation panel 112 for giving instructions to the image forming apparatus 100 (controller 130) and displaying information from the image forming apparatus 100 (controller 130). . Further, below the platen 101 is provided a stand 113 that supports the image forming apparatus 100 and can move the image forming apparatus 100 to a position desired by the user.

  As shown in FIG. 3, the recording head unit 120 includes a recording head group 122, side UV light sources 123 a and 123 b, and a front UV light source 124 in a box-shaped recording head case 121. Among these, the recording head group 122 has six different colors (cyan (C), magenta (M), yellow (Y), black (K), transparent (CL), and white (W)). Three types of recording heads that discharge each ultraviolet curable ink (ink that is cured by receiving ultraviolet rays) from a plurality of nozzles (not shown) toward the recording medium WK, specifically, a process color ink recording head 122a and transparent ink The recording head 122b and the white ink recording head 122c are configured. Of these, the process color ink recording head 122a discharges four different colors (cyan (C), magenta (M), yellow (Y), and black (K)) of ultraviolet curable ink. It is composed of four recording heads.

  These process color ink recording heads 122a, transparent ink recording heads 122b, and white ink recording heads 122c constituting the recording head group 122 are parallel to the sub-scanning direction in the recording head case 121 along the main scanning direction. They are arranged adjacent to each other. Further, nozzles (not shown) that discharge ultraviolet curable ink along the sub-scanning direction, which is the conveyance direction of the recording medium WK, on each lower surface (the surface facing the platen 101) of each recording head constituting the recording head group 122. Are formed in a row. In the present embodiment, nozzles that discharge ultraviolet curable ink are arranged in a range of 80 mm. That is, in this embodiment, the image forming area in the sub-scanning direction of the recording head group 122 is 80 mm. The process color ink recording head 122a, the transparent ink recording head 122b, and the white ink recording head 122c are connected to ink tanks (not shown), and ultraviolet curable inks of the respective colors are supplied from these ink tanks. .

  The side UV light sources 123a and 123b and the front UV light source 124 are long bodies in which LED light sources (not shown) that emit ultraviolet rays having the same wavelength for curing the ultraviolet curable ink are arranged along the sub-scanning direction. The platen 101 is fixed in the recording head case 121 in such a direction as to irradiate ultraviolet rays. Of these side UV light sources 123 a and 123 b and the front UV light source 124, the side UV light sources 123 a and 123 b are disposed adjacent to both sides of the recording head group 122. That is, the side UV light sources 123 a and 123 b are arranged on the same main scanning line as the recording head group 122. In these side UV light sources 123a and 123b, in addition to the image forming area of the recording head group 122, the ultraviolet irradiation area in the sub-scanning direction has a length corresponding to the conveyance amount of the recording medium WK at the time of image formation. It is formed to extend downstream in the sub-scanning direction (X direction side). In the present embodiment, the conveyance amount of one recording medium WK at the time of image formation on the recording medium WK is set to half the length (40 mm) of the image forming area in the recording head group 122, and the side The ultraviolet light irradiation areas of the UV light sources 123a and 123b are formed to be 120 mm.

  On the other hand, the front UV light source 124 is disposed with a predetermined gap in a state facing the recording head group 122 on the downstream side in the sub-scanning direction (X direction side). In this case, the predetermined gap cannot mechanically interfere at least the lower end portion (lower end portion in the drawing) of the recording head group 122 and the upper end portion (upper end portion in the drawing) of the front UV light source 124. It is longer than the length of the part. That is, the extended portion of the irradiation region in the side UV light sources 123a and 123b compensates for a range in which ultraviolet rays cannot be irradiated in the mechanical interference portion between the recording head group 122 and the front UV light source 124. Therefore, when the recording head group 122 and the front UV light source 124 can be disposed in a substantially intimate contact state, it is not always necessary to provide an extended portion in the irradiation region of the side UV light sources 123a and 123b. In the present embodiment, as described above, the irradiation area of the side UV light sources 123a and 123b is set to an integral multiple of the single conveyance amount of the recording medium WK. Ink curing acceleration processing is performed in units of formation regions.

  The front UV light source 124 has an area irradiated with ultraviolet rays that is six times the conveyance amount of the recording medium WK at one time (in other words, the length of the nozzle array arranged in the sub-scanning direction of the recording head group 122). The irradiation area is provided along the direction inclined with respect to the sub-scanning direction. In this case, the front UV light source 124 is arranged in a direction inclined in the sub-scanning direction in a range in which the ultraviolet irradiation region is an integral multiple of the conveyance amount of the recording medium WK once along the sub-scanning direction. In the present embodiment, the length in the sub-scanning direction of the ultraviolet irradiation region of the front UV light source 124 is arranged at an inclination angle that is the conveyance amount (80 mm) of the recording medium WK twice. The inclination angle of the front UV light source 124 is preferably an angle at which the length of the ultraviolet irradiation area in the sub-scanning direction is an integral multiple of the conveyance amount of the recording medium WK at one time for equalizing the number of ultraviolet irradiations. It is not limited to.

  The controller 130 is configured by a microcomputer including a CPU, a ROM, a RAM, and the like, and is previously stored in a storage device such as a ROM in accordance with an instruction from a user or an instruction from an external computer device 140 connected via the interface 131. Various operations of the inkjet image forming apparatus 100 are controlled by executing the stored program. Specifically, the controller 130 operates each of the X-axis direction feed motor 103, the Y-axis direction scan motor 109, and the recording head unit 120 (recording head group 122, side UV light sources 123a and 123b, front UV light source 124). To control each. The external computer device 140 is a personal computer (so-called personal computer) including an input device 141 composed of a keyboard and a mouse and a display device 142 composed of a liquid crystal display.

(Operation of Inkjet Image Forming Apparatus 100)
Next, the operation of the ink jet image forming apparatus 100 configured as described above will be described. First, the user connects the external computer device 140 and the inkjet image forming apparatus 100 via the interface 131, and turns on the external computer device 140 and the inkjet image forming apparatus 100, respectively. As a result, the external computer device 140 enters a standby state waiting for an input of a command from the user by executing a predetermined program (not shown). The ink jet image forming apparatus 100 executes a predetermined program (not shown) stored in advance in the ROM in the controller 130 to return the recording head unit 120 to the origin, and then sends an instruction from the external computer device 140. Waiting for In this case, the origin of the recording head unit 120 is one movable limit position (the rightmost end in the drawing) within the movable range of the recording head unit 120 in the main scanning direction.

  Next, the user sets the recording medium WK on the platen 101 with the recording medium WK sandwiched between the grid roller 102 and the pinch roll 105, and then operates the input device 141 of the external computer device 140 to form an image. The apparatus 100 is instructed to form an image. In this case, the user creates a formation target image to be formed on the recording medium WK in advance on the external computer 140. In response to the instruction, the external computer device 140 generates image data corresponding to the image to be formed stored in the external computer device 140 and outputs the image data to the inkjet image forming apparatus 100 (controller 130). .

  The controller 130 of the ink jet image forming apparatus 100 that has input the image data starts an image forming process on the recording medium WK by executing a predetermined image forming program (not shown) in response to the input of the image data. In this case, the controller 130 performs image formation by a so-called two-pass method that completes the image formation by scanning the recording head unit 120 twice on the same portion of the recording medium WK.

  Specifically, as shown in FIG. 4A, the controller 130 controls the operation of the X-axis direction feed motor 103 to convey the recording medium WK, thereby lowering the lower end of the recording medium WK in the sub-scanning direction. (The lower front end in the figure) is positioned at the position of the upstream half of the recording head group 122 in the sub-scanning direction. Next, the controller 130 appropriately discharges ultraviolet curable ink of each color from the recording head group 122 while controlling the operation of the Y-axis direction scanning motor 109 to perform the main scanning (outward path) of the recording head unit 120 in the direction of the arrow in the drawing. Thus, an image is formed on the main scanning line L1 on the recording medium WK. In this case, the controller 130 irradiates the ultraviolet curable ink ejected from the recording head group 122 and attached on the main scanning line L1 in the recording medium WK from the side UV light source 123b. Thereby, curing of the ultraviolet curable ink discharged onto the main scanning line L1 is promoted. That is, the side UV light sources 123a and 123b correspond to the side arrangement curing acceleration unit according to the present invention and also correspond to the ink curing acceleration unit according to the present invention.

  Next, as shown in FIG. 4B, the controller 130 controls the operation of the X-axis direction feed motor 103 to convey the recording medium WK by one conveyance amount (40 mm in this embodiment). As a result, the lower end in the sub-scanning direction (the lower end in the figure) of the recording medium WK is positioned at the position of the lower end in the sub-scanning direction of the recording head group 122. Next, the controller 130 appropriately discharges ultraviolet curable ink of each color from the recording head group 122 while controlling the operation of the Y-axis direction scanning motor 109 to perform main scanning (return path) of the recording head unit 120 in the direction of the arrow in the drawing. Thus, images are formed on the main scanning line L1 and the main scanning line L2 on the recording medium WK. Thereby, the image forming process by the recording head group 122 on the main scanning line L1 in the recording medium WK is completed.

  In this case, the controller 130 irradiates the ultraviolet curable ink adhered on the main scanning line L1 with ultraviolet rays from the side UV light sources 123b and 123a, and is discharged from the recording head group 122 to be recorded on the recording medium WK. UV light is irradiated from the side UV light source 123a to the UV curable ink adhering to the main scanning line L2. Thereby, the curing of the ultraviolet curable ink discharged onto the main scanning lines L1 and L2 is promoted.

  Next, as shown in FIG. 4C, the controller 130 controls the operation of the X-axis direction feed motor 103 to convey the recording medium WK by one conveyance amount. The lower end in the sub-scanning direction (the lower front end in the figure) is positioned at the position of the lower end in the sub-scanning direction of the side UV light sources 123a and 123b. As a result, the main scanning line L1 on the recording medium WK deviates from the portion immediately below the recording head group 122 to the downstream side in the sub-scanning direction. Next, the controller 130 appropriately discharges ultraviolet curable ink of each color from the recording head group 122 while controlling the operation of the Y-axis direction scanning motor 109 to perform the main scanning (outward path) of the recording head unit 120 in the direction of the arrow in the drawing. Thus, images are respectively formed on the main scanning line L2 and the main scanning line L3 on the recording medium WK. Thereby, the image forming process by the recording head group 122 on the main scanning line L2 in the recording medium WK is completed as described above.

  Also in this case, the controller 130 irradiates the ultraviolet curable ink attached on the main scanning line L2 with ultraviolet rays from the side UV light sources 123a and 123b, and is ejected from the recording head group 122 to the recording medium WK. UV light is irradiated from the side UV light source 123b to the UV curable ink attached on the main scanning line L3. As a result, the curing of the ultraviolet curable ink discharged onto the main scanning lines L2 and L3 is accelerated. In this case, the ultraviolet curable ink on the main scanning line L1 of the recording medium WK conveyed downstream from the portion directly below the recording head group 122 is irradiated from the extended portions of the side UV light sources 123a and 123b. Curing is promoted three times by the ultraviolet rays.

  Next, as shown in FIG. 5 (A), the controller 130 controls the operation of the X-axis direction feed motor 103 to convey the recording medium WK by one conveyance amount, so that the recording medium WK is recorded. The lower end in the sub-scanning direction (the lower front end in the figure) is positioned at the intermediate position in the sub-scanning direction in the ultraviolet irradiation region of the front UV light source 124. That is, the main scanning line L1 of the recording medium WK is positioned directly below the upstream half in the sub-scanning direction in the ultraviolet irradiation region of the front UV light source 124. Next, the controller 130 appropriately discharges ultraviolet curable ink of each color from the recording head group 122 while controlling the operation of the Y-axis direction scanning motor 109 to perform main scanning (return path) of the recording head unit 120 in the direction of the arrow in the drawing. Thus, images are respectively formed on the main scanning line L3 and the main scanning line L4 on the recording medium WK. Since the image forming process on the main scanning lines L3, L4 of the recording medium WK and the ultraviolet irradiation process on the main scanning lines L2, L3, L4 are the same as described above, description thereof will be omitted.

  In this case, the controller 130 lights the front UV light source 124 in the main scanning (outward path) of the recording head unit 120 in the illustrated arrow direction. Thereby, the ultraviolet curable ink attached on the main scanning line L1 of the recording medium WK positioned at the intermediate position in the sub-scanning direction in the ultraviolet irradiation region of the front UV light source 124 is main-scanned in the direction of the arrow shown in the drawing together with the recording head unit 120. The forward UV light source 124 (returned) is irradiated with ultraviolet rays to accelerate curing. Further, in this case, since the front UV light source 124 is disposed obliquely with respect to the sub-scanning direction, the front UV light source 124 passes once compared to the case where the front UV light source 124 is disposed in parallel with the sub-scanning direction. In this case, the irradiation time of ultraviolet rays becomes longer, and curing is further promoted. That is, the front UV light source 124 corresponds to the forward arrangement curing promoting unit according to the present invention and also corresponds to the ink curing promoting unit according to the present invention.

  Next, as shown in FIG. 5B, the controller 130 controls the operation of the X-axis direction feed motor 103 to convey the recording medium WK by a single conveyance amount, so that the recording medium WK The lower end in the sub-scanning direction (the lower front end in the figure) is positioned at the lower end in the sub-scanning direction (the lower front end in the figure) in the ultraviolet irradiation region of the front UV light source 124. That is, the main scanning lines L1 and L2 of the recording medium WK are positioned immediately below the ultraviolet irradiation region of the front UV light source 124. Next, the controller 130 appropriately discharges ultraviolet curable ink of each color from the recording head group 122 while controlling the operation of the Y-axis direction scanning motor 109 to perform the main scanning (outward path) of the recording head unit 120 in the direction of the arrow in the drawing. Thus, images are respectively formed on the main scanning line L4 and the main scanning line L5 on the recording medium WK. Since the image forming process on the main scanning lines L4, L5 and the ultraviolet irradiation process on the main scanning lines L3, L4, L5 of the recording medium WK are the same as described above, description thereof will be omitted.

  In this case, the controller 130 detects the front UV light source with respect to the ultraviolet curable ink attached on the main scanning lines L1 and L2 of the recording medium WK in the main scanning (outward path) of the recording head unit 120 in the direction indicated by the arrow. The ultraviolet ray is irradiated from 124. Thereby, the curing of the ultraviolet curable ink adhering to the main scanning lines L1 and L2 of the recording medium WK is promoted. Also in this case, since the front UV light source 124 is disposed obliquely with respect to the sub-scanning direction, the front UV light source 124 is rotated once compared to the case where the front UV light source 124 is disposed parallel to the sub-scanning direction. The irradiation time of the ultraviolet rays when passing through becomes longer, and curing is further promoted.

  All of the ultraviolet irradiation processing for the main scanning line L1 of the recording medium WK is completed by the irradiation of the ultraviolet rays on the downstream side in the sub-scanning direction in the ultraviolet irradiation region of the front UV light source 124. Therefore, in the present embodiment, the recording medium WK is irradiated with ultraviolet rays in units of one conveyance amount (one pass unit) of the recording medium WK for a total of seven times. As a result, it is possible to prevent the UV irradiation of the image on the same main scanning line from being performed twice or more and to accelerate the curing with high accuracy.

  Thereafter, as shown in FIG. 5C, the controller 130 controls the operation of the X-axis direction feed motor 103 to convey the recording medium WK by one conveyance amount. As a result, the main scanning line L1 of the recording medium WK deviates from the portion directly below the downstream side in the sub scanning direction in the ultraviolet irradiation region of the front UV light source 124 to the downstream side in the sub scanning direction. On the other hand, the image forming process and the ultraviolet irradiation process similar to those described above are continuously performed on the main scanning lines L2, L3, L4, L5, and L6 of the recording medium WK. Then, the controller 130 performs image formation processing and ultraviolet irradiation processing on all image data input from the external computer device 140, and then ejects the recording medium WK and shifts to the standby state again.

  As can be understood from the above operation description, according to the embodiment, the front UV light source 124 that cures the ultraviolet curable ink on the recording head group 122 on the downstream side in the transport direction of the recording medium WK is the recording medium WK. Is provided in a state facing the recording head group 122 on the downstream side in the transport direction. That is, the front UV light source 124 is provided on the front surface (the surface on the downstream side in the conveyance direction of the recording medium WK) of the recording head group 124, and protrudes downstream in the conveyance direction of the recording medium WK on both side surfaces of the recording head group 124. Is not provided. Accordingly, it is necessary to secure a space for accommodating the front UV light source 124 projecting in the conveyance direction of the recording medium WK on both side surfaces of the recording head group 124 at both ends in the main scanning direction of the recording head group 124. There is no. As a result, the degree of freedom in layout design and design of other devices at both ends of the recording head group 124 in the main scanning direction is improved.

  Further, according to the embodiment, the front UV light source 124 is provided along a direction inclined with respect to the direction in which the recording medium WK is conveyed. For this reason, the ink jet image forming apparatus in the above-described conventional example, that is, the ink jet image forming apparatus in which the UV irradiation device is formed with a length of twice or more the print width of the recording head along the conveyance direction of the recording medium WK. Compared to the above, the mechanical structure of the recording head unit 120 including the recording head and the UV irradiation device is made compact, so that the configuration of the ink jet image forming apparatus 100 is reduced, the power consumption is reduced, and the assembly / maintenance work is simplified. be able to. Further, it is possible to use an ink that is effectively cured by increasing the time for which the ultraviolet rays are continuously applied, and the quality of image formation can be improved.

  Furthermore, in carrying out the present invention, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the object of the present invention.

  For example, in the above embodiment, two side UV light sources 123 a and 123 b are arranged adjacent to both sides of the recording head group 122. However, the side UV light sources 123a and 123b may be appropriately provided according to the characteristics of the ink to be used and the quality of the formed image. That is, the side UV light sources 123a and 123b are arranged on either one of the two sides of the recording head group 122 (left side in the drawing) as shown in FIG. Alternatively, as shown in FIG. 7, the recording head unit 120 can be configured without providing the side UV light sources 123a and 123b. According to these, the recording head unit 120 can be configured more compactly.

  In the above-described embodiment, the front UV light source 124 is disposed so as to be inclined in the sub-scanning direction in a range in which the irradiation area of the ultraviolet rays in the sub-scanning direction is twice the transport amount of the recording medium WK. However, the inclination angle of the front UV light source 124 may be appropriately set depending on the properties of the ultraviolet curable ink and the quality of the image to be formed. For example, in the case where effective UV curable ink curing or image formation can be realized by intermittently irradiating UV rays, the front UV light source 124 may be arranged close to a direction parallel to the sub-scanning direction. On the other hand, when effective ultraviolet curing ink curing or image formation can be realized by continuously irradiating ultraviolet rays, the front UV light source 124 may be arranged close to a direction parallel to the main scanning direction ( (See FIG. 6).

  In these cases, the ultraviolet irradiation region in the sub-scanning direction of the front UV light source 124 may be set to a length corresponding to one transport amount of the recording medium WK or an integral multiple of the transport amount. According to this, the ink curing acceleration process is performed by the recording head group 122 in units of one image forming area, and one curing process for images on the same main scanning line is performed in two or more times. Therefore, curing can be accelerated with high accuracy.

  In the above embodiment, the UV light having the same wavelength is irradiated from the side UV light sources 123 a and 123 b and the front UV light source 124. However, the side UV light sources 123a and 123b and the front UV light source 124 can irradiate ultraviolet rays having different wavelengths. For example, the side UV light sources 123a and 123b irradiate ultraviolet rays having a relatively short wavelength (for example, a wavelength of 365 nm) and the front UV light source 124 irradiates ultraviolet rays having a relatively long wavelength (for example, a wavelength of 400 nm). In this way, the surface layer of the ultraviolet curable ink attached on the recording medium WK can be cured at an early stage by irradiating ultraviolet rays having a short wavelength from the side UV light sources 123a and 123b. An image can be formed while suppressing the spread on the WK. Further, by irradiating ultraviolet light having a long wavelength from the front UV light source 124, the deep layer of the ultraviolet curable ink adhered on the recording medium WK can be effectively cured, and the image forming accuracy can be improved.

  In the above embodiment, the side UV light sources 123a and 123b always radiate ultraviolet rays with an output suitable for promoting the curing of the ultraviolet curable ink. However, the output from the side UV light sources 123a and 123b at the time of image formation, that is, the intensity of ultraviolet rays may be changed. For example, the output of the side UV light source 123 a or the side UV light source 123 b that first passes through the droplets of the ultraviolet curable ink ejected from the recording head group 122 and attached to the recording medium is decreased by the control of the controller 130. .

  Specifically, for example, as shown in FIG. 4A, the controller 130 controls the operation of the Y-axis direction scan motor 109 to perform the main scanning (outward path) recording in the recording head unit 120 in the direction indicated by the arrow. When an image is formed on the main scanning line L1 on the medium WK, the output of the ultraviolet rays irradiated from the side UV light source 123b is set to about 10% of the output suitable for curing the ultraviolet curable ink (normal output). Then, as shown in FIG. 4B, the controller 130 controls the operation of the Y-axis direction scan motor 109 to perform the main scanning (return path) of the recording head unit 120 in the direction of the arrow in the figure, and performs the main scanning on the recording medium WK. When forming an image on the scanning lines L1 and L2, the output of the ultraviolet rays irradiated from the side UV light source 123b is set to an output suitable for curing the ultraviolet curable ink (normal output 100%) and the side UV light source. The output of the ultraviolet rays emitted from 123a is set to about 10% of the output suitable for curing the ultraviolet curable ink (normal output). That is, the controller 130 corresponds to output control means according to the present invention.

  As a result, the ink droplets of the ultraviolet curable ink ejected on the recording medium WK are further spread on the recording medium WK because the degree of curing is slower than when the output is optimal for curing the ink. As a result, it is possible to accurately form an image to be filled or an image having a low resolution. The amount by which the output of the side UV light sources 123a and 123b is reduced is appropriately determined in the range of more than 0% and 100% or less of the output (normal output) suitable for curing the ultraviolet curable ink to be cured. do it. The amount by which the output of the side UV light sources 123a and 123b is reduced to 100% means that the side UV light source 123a that first passes over the ultraviolet curable ink ejected from the recording head group 122 and attached to the recording medium. The side UV light source 123b does not irradiate the ultraviolet light, and the side UV light source 123a or the side UV light source 123b that passes through the recording medium WK after the second time passes and irradiates the ultraviolet light.

  In this case, no UV irradiation is performed by the side UV light source 123a or the side UV light source 123b that passes the second time after the ink is deposited on the recording medium WK. Curing acceleration can also be performed. As a result, the start of the ink curing process for the ink adhering to the recording medium WK is delayed, so that the ink curing acceleration process is performed by the front UV light source 124 when the inks adjacent to each other on the recording medium WK become familiar with each other. Is called. As a result, it is possible to widen the range of texture variations in image formation, such as being able to accurately form glossy texture images when transparent ink is used.

  Further, in the above embodiment, when the recording medium WK does not exist directly below the front UV light source 124, specifically, when the recording medium WK is not conveyed to the position immediately below the front UV light source 124 in the initial stage of image formation. In the configuration, ultraviolet irradiation from the front UV light source 124 is not performed. Thereby, the power consumption of the inkjet image forming apparatus 100 can be suppressed. That is, when there is no ultraviolet curable ink that requires ultraviolet irradiation immediately below the side UV light sources 123a and 123b and the front UV light source 124, the ultraviolet irradiation from the side UV light sources 123a and 123b and the front UV light source 124 is stopped. By doing so, the power consumption of the inkjet image forming apparatus 100 can be suppressed. For example, when there is no image immediately below the side UV light sources 123a and 123b at the final stage of image formation, the ultraviolet irradiation from the side UV light sources 123a and 123b may be stopped.

  In the above embodiment, an image is formed using a so-called ultraviolet curable ink that is cured by receiving ultraviolet rays. However, the present invention is not limited to the above embodiment as long as it is ink that is cured by applying some physical action after being ejected onto the recording medium WK. For example, an image may be formed using ink that is cured by applying heat or absorbing heat (that is, cooling) after being discharged onto the recording medium WK. In this case, instead of the side UV light sources 123a and 123b and the front UV light source 124, a device that applies heat to or absorbs the discharged ink may be used as the hardened layer forming unit. Also by these, the same effect as the above-mentioned embodiment can be expected.

  In the above-described embodiment, the front UV light source 124 is arranged adjacent to the downstream side of the side UV light sources 123a and 123b immediately downstream in the conveyance direction of the recording medium WK. As a result, the ink curing acceleration process is continuously performed by the front UV light source 124 on the recording medium WK immediately after passing through the side UV light sources 123a and 123b. However, you may make it arrange | position the front UV light source 124 through a clearance gap with respect to the side UV light sources 123a and 123b. Accordingly, the ink accelerated by the side UV light sources 123a and 123b undergoes a curing acceleration process by the front UV light source 124 after waiting for a time corresponding to the gap. Thereby, the width of the variation of the texture in image formation can be expanded. In this case as well, the distance between the side UV light sources 123a and 123b and the front UV light source 124 is equal to the distance corresponding to one image forming area (one transport amount of the recording medium WK) by the recording head group 122. Alternatively, an interval that is an integral multiple of the single conveyance amount of the recording medium WK may be used. As a result, it is possible to prevent the UV irradiation of the image on the same main scanning line from being performed twice or more and to accelerate the curing with high accuracy.

WK ... recording medium, L1 to L2 ... main scanning line 100 ... image forming apparatus, 101 ... platen, 102 ... grid roll, 104 ... guide rail, 105 ... pinch roller 120 ... recording head unit, 121 ... recording head case, 122 ... Recording head group, 122a ... process color ink head, 122b ... transparent ink head, 122c ... white ink head, 123a, 123b ... side UV light source, 124 ... front UV light source 130 ... controller 140 ... external computer device

Claims (10)

A recording medium conveying means for conveying the recording medium on the platen;
A recording head that discharges and attaches ink to the surface of the recording medium while moving in a direction perpendicular to the direction in which the recording medium is conveyed;
In an ink jet image forming apparatus provided with an ink curing accelerating means for accelerating the curing of the ink attached on the recording medium,
The ink curing acceleration means is
A forward disposition promoting means provided in a direction that is movable with respect to the recording head and at a position downstream of the recording head in the transport direction of the recording medium along a direction inclined with respect to the transport direction of the recording medium. An ink jet image forming apparatus comprising: The inkjet image forming apparatus according to claim 1, further comprising:
The ink curing acceleration means is
An ink jet image forming apparatus comprising: a laterally arranged curing accelerating unit that is arranged adjacent to the recording head and accelerates the curing of ink attached to the surface of the recording medium while moving together with the recording head. The inkjet image forming apparatus according to claim 2,
The lateral arrangement curing promoting means is
An ink jet image forming apparatus, which is disposed adjacent to both sides of the recording head. In the ink jet image forming apparatus according to claim 2 or 3,
The lateral arrangement curing promoting means is configured such that the curing area in the conveyance direction of the recording medium is a total length of a single conveyance amount of the recording medium and an ink discharge range of the recording head, or a single conveyance of the recording medium. An ink jet image forming apparatus having an integral multiple of the quantity. The ink jet image forming apparatus according to any one of claims 2 to 4, wherein:
The forward arrangement hardening promoting means and the lateral arrangement hardening promoting means have a length in which the interval between the cured areas in the conveyance direction of the recording medium corresponds to one conveyance amount of the recording medium or an integral multiple of the conveyance amount. An ink jet image forming apparatus. In the ink jet image forming apparatus according to any one of claims 2 to 5,
The forward arrangement curing promoting means is characterized in that the curing area in the conveyance direction of the recording medium has a length corresponding to one conveyance amount of the recording medium or an integral multiple of the conveyance amount. Forming equipment. The inkjet image forming apparatus according to any one of claims 2 to 6,
The recording head discharges ink that is cured by irradiation with ultraviolet rays or infrared rays onto the recording medium,
The forward arrangement curing promoting means and the lateral arrangement curing promoting means each include a light source that irradiates light including the ultraviolet rays or the infrared rays,
The forward arrangement hardening promoting means includes
An ink jet image forming apparatus irradiating a light beam having a longer wavelength than the light beam irradiated from the side arrangement curing promoting means. The inkjet image forming apparatus according to claim 7,
The lateral arrangement curing promoting means includes a light source that emits ultraviolet light having a wavelength of 365 nm,
2. The ink jet image forming apparatus according to claim 1, wherein the forward arrangement curing promoting means includes a light source that emits ultraviolet light having a wavelength of 400 nm. The inkjet image forming apparatus according to any one of claims 2 to 7, further comprising:
Comprising output control means for controlling the output of the lateral arrangement hardening accelerating means;
The output control means reduces the output of the lateral arrangement curing acceleration means to less than an output suitable for curing of the ink when the ink that adheres to the surface of the recording medium passes through the first lateral arrangement curing acceleration means. An ink jet image forming apparatus that controls the ink jet image forming apparatus. The inkjet image forming apparatus according to claim 9,
The output control means further stops the output of the side arrangement curing acceleration means until the ink attached to the surface of the recording medium has passed through the side arrangement curing acceleration means. Image forming apparatus.

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