Patent Application
20200276833
The present invention relates to an ejecting apparatus, an image forming apparatus, a curing method, and a computer-readable medium.
An inkjet apparatus that forms an image with an activation energy ray curable liquid, such as an ultra-violet (UV) curable ink, has conventionally been known. Use of a technology for performing gloss coating with a clear ink, in order to achieve glossiness on a printout, in the UV-curable inkjet apparatus has also been known.
Normally, during color printing performed by the UV-curable inkjet apparatus, the ink is cured immediately after the ink is ejected, by irradiating the ink with UV rays. By contrast, when performing the gloss coating, the clear ink is irradiated with UV rays after the ink has become levelled (smoothed), instead of irradiating the ink immediately after the clear ink is ejected. At this time, if the clear ink has the same composition as the color ink, the color coating becomes dissolved with the clear ink, while the clear ink is being ejected and levelled, unless the clear ink is cured immediately after the clear ink is levelled. Therefore, in order to prevent such dissolution, the clear ink needs to be ejected and irradiated with UV rays as a continuous process. To perform gloss coating as a continuous processes, it is possible to use a configuration provided with two irradiators, one being a color-printing UV irradiator that irradiates the color ink with UV rays immediately after the color ink is ejected, and the other being a clear-coating UV irradiator that irradiates the clear ink with UV rays after the clear ink has become levelled. It is also possible to use a configuration including one irradiator that achieves the same effect as that achieved by two irradiators, by partly turning off the irradiator.
For example, in the configuration in which one irradiator is partly turned off to achieve the same effect as that achieved by two irradiators, it is preferable for the irradiator to have one part that emits rays (turned on) and the other part that is turned off, depending on the configuration of heads and the number of scans. As an example of such a technology of implementing an irradiator having one part emitting rays (turned on) and the other part that is turned off, there has been a disclosure of a technology in which, when the number of passes is n, the rays are emitted immediately after the ink is ejected up to the n−mth pass, the clear ink is allowed to level in the mth pass, and the levelled clear ink is irradiated with rays in the remaining passes to achieve a gloss finish (see Patent Literature 1).
However, the technology disclosed in Patent Literature 1 controls to cause a part having the same width as the scan width to be turned on, and the irradiator is caused to emit rays and turned off exactly in units of one scan. Therefore, some efforts have been required to newly develop an irradiator supporting such turning-on control based on the number of scans, and the cost will be increased, compared with use of a general-purpose irradiator.
The present invention is made in consideration of the above, and has an object to accurately perform gloss coating at a lower cost.
In order to solve the above problem and achieve the object, according to one aspect of the present invention, an ejecting apparatus includes an ejection control unit, an irradiating unit, an irradiation control unit. The ejection control unit is configured to cause a first ejecting unit among ejecting units configured to move in a main-scanning direction, to eject a liquid that is activation energy ray curable, to a recording medium. The irradiating unit is configured to emit an activation energy ray and divided into a plurality of irradiating blocks in a sub-scanning direction perpendicular to the main-scanning direction. The irradiation control unit is configured to turn off an irradiating block corresponding to the first ejecting unit moving in the main-scanning direction, among the plurality of irradiating blocks. The irradiating unit is positioned in such a manner that a first distance is larger than a second distance. The first distance is a distance between a downstream end of the first ejecting unit in the sub-scanning direction and an upstream end of an irradiating block that is positioned downstream among the plurality of irradiating blocks. The second distance is a distance by which the irradiating block irradiates the recording medium outside from an end of an emission surface of the irradiator block in the sub-scanning direction. The irradiation control unit is configured to cure the liquid by causing the irradiating block positioned downstream of the turned-off irradiating block corresponding to the first ejecting unit in the sub-scanning direction, to emit the activation energy ray.
According to the present invention, gloss coating can be performed accurately at a lower cost.
An embodiment of an ejecting apparatus, an image forming apparatus, a curing method, and a computer-readable medium according to the present invention will now be explained in detail with reference to
As illustrated in
The controller unit 3 is a device that controls the operations of the units included in the image forming apparatus 1. The controller unit 3 includes, as illustrated in
The unit control circuit 31 is a circuit that controls the operations of the main scanning unit 100, the sub-scanning unit 200, the head unit 300, the irradiating unit 400, and the maintenance unit 500, in response to a command received from the CPU 34.
The CPU 34 controls the operation of the entire image forming apparatus 1 by executing a computer program stored in the ROM 32, using the memory 33 as a working area. Specifically, the CPU 34 controls the operations of the main scanning unit 100, the sub-scanning unit 200, the head unit 300, the irradiating unit 400, and the maintenance unit 500, via the unit control circuit 31. The CPU 34 also controls these units based on record data received from a personal computer (PC) 2 illustrated in
The I/F 35 is an interface for establishing a connection for enabling the image forming apparatus 1 to perform data communication with the external PC 2. In
A printer driver is installed on the PC 2, and the PC 2 generates record data to be transmitted to the image forming apparatus 1, from image data, using the printer driver. The record data contains command data for causing the units such as the sub-scanning unit 200 in the image forming apparatus 1 to operate, and pixel data that is related to an image. The pixel data has, for example, two-bit data in each pixel, and is expressed in four gradients.
The detector group 4 includes various types of sensors required for the image forming apparatus 1 to operate. For example, the detector group 4 includes sensors such as a height sensor 41 illustrated in
The main scanning unit 100 is a unit that moves in a Z axis direction (height direction) illustrated in
The sub-scanning unit 200 is a unit that moves a base material 201 (one example of a recording medium) that is placed on the sub-scanning unit 200 illustrated in
The head unit 300 is a unit including heads for ejecting yellow (Y), magenta (M), cyan (C), black (K), clear (CL), and white (W) UV-curable inks (examples of an ink that is activation energy ray curable), respectively. The head unit 300 is provided to the bottom surface of the main scanning unit 100. An arrangement and a configuration of the heads in the head unit 300 will be explained later with reference to
Each head in the head unit 300 has a piezoelectric element, and, when the piezoelectric element receives an application of a driving signal from the unit control circuit 31, a contracting motion takes place in the head unit 300, and a pressure change resulting from the contracting motion causes a UV-curable ink to be ejected to the base material. As a result, a surface applied with the ink is formed on the base material. Examples of the UV-curable ink according to the embodiment includes an ink including acrylate-based monomer or methacrylate-based monomer, for example. A methacrylate-based monomer is relatively less skin sensitizing, advantageously, but exhibits greater cure shrinkage than a general ink does.
The irradiating unit 400 is provided to two perpendicular side surfaces of the main scanning unit 100, being perpendicular to the X axis direction (main-scanning direction). The irradiating unit 400 is a unit for emitting UV rays (one example of an activation energy ray), in response to a driving signal received from the unit control circuit 31. The irradiating unit 400 includes a UV irradiation lamp that mainly emits UV rays. This UV irradiation lamp is implemented by a light emitting diode (LED), for example. The irradiating unit 400 includes an irradiating unit 400L that is provided to one of the perpendicular side surfaces of the main scanning unit 100, being perpendicular to the X axis direction (main-scanning direction), and an irradiating unit 400R that is provided to the other surface, as illustrated in
The maintenance unit 500 is a unit that cleans (performs a maintenance of) the heads of the head unit 300, in order to maintain and to recover the performance of the heads of the head unit 300, in the main scanning unit 100 having moved above the maintenance unit 500. Specifically, the maintenance unit 500 includes a wiper unit 501, as illustrated in
The hardware configuration of the image forming apparatus 1 illustrated in
As illustrated in
As illustrated in
The white (W) color ink ejected from the heads 301W1 to 301W3 is used to as a white ink for the base material 201 having a base color other than white. The clear ink ejected from the heads 301CL1 to 301CL3 is used to form a gloss-coating layer on the base material 201, or over the color inks applied on the base material 201. The ink that is ejected from the heads 301CL1 to 301CL3 and with which the gloss-coating layer is formed is not limited to a clear ink with no color, and may be an opaque ink, or an ink with some color added, for example.
As illustrated in
Furthermore, as illustrated in
As mentioned earlier, the irradiating unit 400 includes the irradiating unit 400L and the irradiating unit 400R that are provided to the perpendicular side surfaces of the main scanning unit 100, being perpendicular to the X axis direction. Each of the irradiating unit 400L and the irradiating unit 400R is divided into a plurality of irradiating blocks, and each of the irradiating blocks is configured in such a manner that the LED output thereof is independently controllable. In the example illustrated in
As illustrated in
In the example described above, the irradiating unit 400L (400R) is moved manually in the sub-scanning direction with respect to the main scanning unit 100 (the lamp fixing mechanism 403), but the present invention is not limited thereto. In other words, the lamp moving mechanism 402 may be provided with an actuator (one example of an irradiation moving unit) for moving the irradiating unit 400L (400R) in the sub-scanning direction, so that the irradiating unit 400L (400R) can be moved automatically to a specific position in the sub-scanning direction.
An image forming process (including a curing process) performed by the image forming apparatus 1 according to the embodiment will now be explained briefly.
To begin with, the sub-scanning unit 200 moves in the sub-scanning direction (Y axis direction) in response to a driving signal received from the CPU 34 (the unit control circuit 31), to move the base material 201 to an initial value for forming the image.
The main scanning unit 100 then moves to a height suitable for allowing the head unit 300 to eject the UV-curable ink (e.g., a height at which the head unit 300 and the base material 201 forms a gap of 1 millimeter), in response to a driving signal received from the CPU 34 (the unit control circuit 31). At this time, the CPU 34 recognizes the height of the head unit 300 with respect to the base material 201 based on detection data related to the height detected by the height sensor 41.
The main scanning unit 100 then moves reciprocally (scans) in the main-scanning direction (X axis direction), in response to a driving signal received from the CPU 34 (the unit control circuit 31). As the main scanning unit 100 moves reciprocally, the head unit 300 ejects color inks (energy-curable colored liquids), in response to a driving signal received from the CPU 34 (the unit control circuit 31). As a result, an image corresponding to one scan is formed on the base material 201. As the main scanning unit 100 moves reciprocally, the color ink ejected on the base material 201 is cured by the irradiation with the UV rays emitted from the irradiating unit 400. The sub-scanning unit 200 then moves by a width corresponding to one scan (hereinafter, sometimes referred to as a “scan width”) in the sub-scanning direction (Y axis direction), in response to a driving signal received from the CPU 34 (the unit control circuit 31). In the process thereafter, the operation of forming an image corresponding to one scan and the operation of moving the sub-scanning unit 200 by the scan width in the sub-scanning direction are repeated until the image formation is completed.
When gloss coating with a clear ink is to be performed, the operation of the irradiating unit 400 is withheld for a time period allowing the clear ink to smooth out (to level) (hereinafter, sometimes referred to as “levelling time”), instead of curing the clear ink by irradiating the clear ink with UV rays immediately after the clear ink is ejected, and then the clear ink having levelled is cured by the irradiation with the UV rays emitted from the irradiating unit 400, and the gloss coating layer is formed thereby.
As illustrated in
The movement control unit 601 is a functional unit that causes the unit control circuit 31 to apply driving signals to the main scanning unit 100 and the sub-scanning unit 200, to move the main scanning unit 100 in the Z axis direction (height direction) and the X axis direction (main-scanning direction), and to move the sub-scanning unit 200 in the Y axis direction (sub-scanning direction). The movement control unit 601 is implemented by a computer program executed by the CPU 34 illustrated in
The droplet ejection control unit 602 is a functional unit that controls an ink ejecting operation of the head unit 300. The droplet ejection control unit 602 causes the unit control circuit 31 to apply a driving signal such as that illustrated in
The irradiation control unit 603 is a functional unit that causes the unit control circuit 31 to apply a driving signal to the irradiating unit 400, and controls the operation of UV ray emissions, in units of an irradiating block 401L and an irradiating block 401R of the irradiating unit 400.
When h denotes the height of the emission surface of the irradiating block 401L (401R) with respect to the base material 201 (hereinafter, sometimes simply referred to as an “emission surface height”), an irradiation width Lh irradiated with the UV rays at this height h is broader than the irradiation width L1, in the sub-scanning direction. In other words, the irradiation width Lh has a protruding part Lr/2 (Lr=Lh−L1) protruding from the irradiation width L1, and therefore, it is necessary to consider the effect given to how the ink is cured, by the UV rays corresponding to the protruding part Lr/2. This point will be described later in detail with reference to
As illustrated in the enlarged view in
In the example illustrated in
An image forming process in the gloss-coating mode when Y<C will now be explained with reference to
The color coating film formed by ejecting color inks has an uneven finish (matte finish), because the color inks are irradiated with the UV rays immediately after the inks are ejected. The heads 301CL2, 301CL3 (one example of a first ejecting unit; one example of a specific ejecting unit) are then used as the heads 301 for ejecting the clear ink (one example of a liquid that is activation energy ray curable) with which the gloss coating is performed. At this time, because the ejection of the clear ink and the image formation with the color inks are carried out as one continuous process, the heads 301CL2, 301CL3 eject the clear ink in the same scan width as that of the scan for ejecting the color inks. The clear ink is ejected from the heads 301CL2, 301CL3 in the fifth to the twelfth scans. At that time, the irradiation control unit 603 turns off the irradiating blocks 401R4 to 401R8, which are the irradiating blocks 401R covering the scan widths of the scans for ejecting the clear ink (the fifth to the twelfth scans). In this manner, the clear ink is allowed to level sufficiently, without being irradiated with the UV rays immediately after the clear ink is ejected.
Subsequently, the UV rays for curing the clear ink having levelled sufficiently are emitted, in the thirteenth and the fourteenth scans. To achieve this end, the irradiating block 401R9, which is the irradiating block 401R covering the scan widths of the scans for irradiating the clear ink with UV rays (the thirteenth and the fourteenth scans), is brought to turned-on state (emitting state). In this manner, the clear ink, having levelled, is irradiated with the UV rays, and a gloss coating layer is formed thereby.
In the example in which Y<C illustrated in
To address this issue, to achieve a glossy gloss coating layer, a user moves the irradiating unit 400R in the sub-scanning direction in such a manner that Y>C is satisfied, as illustrated in
Furthermore, in
Furthermore, as illustrated in
In the example explained with reference to
As illustrated in
A user removes the lamp fixing pin 405R that is attached to the lamp moving mechanism 402 and the lamp fixing mechanism 403, and moves the irradiating unit 400R in the sub-scanning direction in such a manner that A<C<Y is satisfied. After moving the irradiating unit 400R, the user fixes the irradiating unit 400R to the lamp fixing mechanism 403 by fitting the lamp fixing pin 405R into the lamp moving mechanism 402 and the lamp fixing mechanism 403. The process is then shifted to Step S12.
The droplet ejection control unit 602 specifies the heads 301 that are positioned upstream as heads for ejecting color inks, and specifies the head 301 positioned downstream as a head for ejecting the clear ink, among the heads 301 that are arranged in the sub-scanning direction. The irradiation control unit 603 then brings the irradiating blocks 401R covering the scan widths of the scans for ejecting the color ink to turned-on (emitting state). The irradiation control unit 603 also turns off the irradiating blocks 401R covering the scan widths of the scans for ejecting the clear ink. The movement control unit 601 then starts repeating the operation of scanning the main scanning unit 100 in the main-scanning direction and the operation of moving the sub-scanning unit 200 in the sub-scanning direction. In the explanation herein, it is assumed that, in the same manner as the example illustrated in
If the next scanning operation to be performed by the main scanning unit 100 is a scan for ejecting a color ink (Yes at Step S13), the process is shifted to Step S14. If the operation is not a scan for ejecting a color ink (No at Step S13), the process is shifted to Step S16. In the example illustrated in
The droplet ejection control unit 602 forms a color image by causing the head 301CM1 and the head 301YK1 to eject the color inks onto the base material 201, in synchronization with the operation of scanning the main scanning unit 100, achieved by the movement control unit 601. The process is then shifted to Step S15.
Immediately after the droplet ejection control unit 602 has caused the color inks to be ejected, the irradiation control unit 603 cures the color ink by causing the irradiating block 401R corresponding to this scan and having been turned on to irradiate the color coating film, formed with the color inks, with UV rays. Instead of the irradiation control unit 603 performing the operation of turning on the irradiating block 401R, the irradiating block 401R may be always turned on, or may be turned on at the timing at which the irradiating block 401R is scanned over a color ink that is to be cured. The process is then shifted to Step S20.
If the next scanning operation to be performed by the main scanning unit 100 is a scan for ejecting clear ink (Yes at Step S16), the process is shifted to Step S17. If the operation is not a scan for ejecting clear ink (No at Step S16), the process is shifted to Step S19. In the example illustrated in
The droplet ejection control unit 602 causes one of the head 301CL2 and the head 301CL3, whichever corresponds to the scan, to eject the clear ink onto the base material 201, in a manner synchronized with the scanning operation of the main scanning unit 100, achieved by the movement control unit 601. The process is then shifted to Step S18.
Immediately after the droplet ejection control unit 602 causes the clear ink to be ejected, the clear ink is allowed to level (smooth out), without being irradiated with the UV rays, because the irradiation control unit 603 keeps the irradiating block 401R corresponding to this scan in turned-off state. The process is then shifted to Step S20.
If the scan is not a scan for ejecting the color ink or the clear ink, but is a scan at the final stage (the thirteenth scan and the fourteenth scan in the example illustrated in
If the final scanning operation has been completed (Yes at Step S20), the image forming process is ended. If the final scanning operation has not been completed yet (No at Step S20), the movement control unit 601 moves the base material 201 by one scan width in the sub-scanning direction, and the process is returned to Step S13.
Through the operations at Steps S11 to S20 described above, the image forming process in the gloss-coating mode is executed.
As described above, in the image forming apparatus 1 according to the embodiment, the irradiating unit 400R (400L) is moved in the sub-scanning direction in such a manner that Y>C is satisfied. Therefore, in the most downstream scan in which the clear ink is ejected, it is possible to allow the clear ink ejected by the most downstream head 301 to level sufficiently, because the range covered by the scan is not irradiated with a part of the irradiation rays (protruding part) for curing the clear ink emitted from the irradiating block 401R (401L). Hence, a glossy gloss coating layer can be formed over a color coating film at a lower cost.
In the image forming apparatus 1 according to the embodiment, the irradiating unit 400R is moved in the sub-scanning direction in such a manner that A<C<Y is satisfied, when A denotes the length (third distance) between the most upstream end of the irradiating block 401R (401L) and the most upstream end of H that is the length by which the color inks are ejected in the sub-scanning direction. By maintaining A<C, the upstream end part of the color coating film, which is achieved by the color ink ejected by the head 301 in the first scan, is also irradiated with the UV rays from the most upstream irradiating block 401R (401L). Therefore, coalescence of one color ink with the others is suppressed, and a beautiful color image can be achieved.
Furthermore, if the boundary part between the irradiating blocks is at a position corresponding to vicinity of the boundary between one color ink ejection and another color ink ejection, the irradiating unit 400R (400L) is moved in the sub-scanning direction in such a manner that the boundary part is covered by the irradiating block that is in the emitting state, among the irradiating blocks provided, within the range in which A<C<Y is satisfied, as described above. In this manner, a glossy gloss coating layer can be formed over a clear ink with a matte finish, and the color inks are reliably irradiated with the UV rays. Therefore, a beautiful color image can be achieved.
Furthermore, in the image forming apparatus 1 according to the embodiment, the scan width is set smaller than the length B of one irradiating block 401R (401L). As a result, it is possible to avoid a situation in which a part of the ejected clear ink remains without being irradiated, and the clear ink remains uncured in some area, for a reason that, although the irradiating block 401R (401L) is configured to emit UV rays in the last scan, the irradiating block 401R (401L) adjacent thereto is configured to be turned off. Therefore, a sufficiently cured gloss coating layer can be achieved.
As illustrated in
In this manner, by tilting the emission surface of the irradiating unit 400R (400L) with respect to the top surface of the base material 201 in the sub-scanning direction, the travelling distance is extended so that the irradiation range broadens. Therefore, even if the length L of the irradiating unit 400R (400L) in the sub-scanning direction is short, a partial irradiation with the irradiating block 401R (401L) is achieved.
Furthermore, by tilting in such a manner that a downstream part of the emission surface of the irradiating unit 400R in the sub-scanning direction is positioned higher, the UV rays having a lower illuminance is emitted from the leftmost irradiating block, in the view facing the paper surface in
Furthermore, in the embodiment and the modification described above, when at least one of the functional units of the image forming apparatus 1 is implemented by execution of a computer program, the computer program is provided in a manner incorporated in the ROM or the like in advance. Furthermore, the computer program executed by the image forming apparatus 1 according to the embodiment and the modification described above may be provided in a manner recorded in a computer-readable recording medium such as a compact disc read-only memory (CD-ROM), a flexible disk (FD), a compact disc recordable (CD-R), and a digital versatile disc (DVD), as a file in an installable or executable format. Furthermore, the computer program executed by the image forming apparatus 1 according to the embodiment and the modification described above may be stored in a computer connected to a network such as the Internet, and made available for download over the network. Furthermore, the computer program executed by the image forming apparatus 1 according to the embodiment and the modification described above may be provided or distributed over a network such as the Internet. Furthermore, the computer program executed by the image forming apparatus 1 according to the embodiment and the modification described above has a modular structure including at least one of the functional units described above, and, as actual hardware, by causing the CPU 34 to read the computer program from the storage device (e.g., the ROM 32) and to execute the computer program, the functional units described above are loaded to and generated on the main memory (e.g., the memory 33).
Japanese Laid-open Patent Publication No. 2015-186918
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-195962 | Oct 2017 | JP | national |
| 2018-164754 | Sep 2018 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2018/037123 | 10/3/2018 | WO | 00 |
