The present invention relates to an inkjet printing apparatus that performs printing by ejecting ink to a print medium supported on a platen.
Japanese Patent Laid-Open No. 2017-061076 discloses an inkjet printing apparatus that performs so-called “borderless printing” in which printing is performed without margins provided in end portions of a print medium. A platen included in the inkjet printing apparatus of Japanese Patent Laid-Open No. 2017-061076 has a tilted surface that receives ink drops ejected to outside of the print medium in the borderless printing. The ink drops are made to land on the tilted surface close to the print medium to reduce a landing distance that is a distance over which the ink flies and reduce generation of mist. Reducing the generation of ink mist as described above reduces adhering of the mist to a back surface of the print medium. Moreover, the inkjet printing apparatus is configured such that the ink drops landing on the tilted surface slide down the tilted surface and then flow to an ink guide hole.
However, in some cases, the landing ink does not reach the ink guide hole and remains on the tilted surface on which the ink has landed, depending on the characteristics of the ink and the temperature and humidity of the environment. Such remaining ink gradually accumulates and, in the case where the height of the accumulating ink reaches the height of a print medium support portion of the platen, there is a risk that the accumulating ink and the back surface of the print medium come into contact with each other and the back surface of the print medium is smeared.
The present invention thus provides an inkjet printing apparatus that can reduce generation of smears on a back surface of a print medium by reducing generation of mist and accumulation of ink in a platen.
The inkjet printing apparatus of the present invention for achieving this object includes a platen having a support surface that supports a print medium to be printed by a printing unit configured to perform printing by ejecting ink, the platen includes an ink receiving portion that is provided away from the support surface by a predetermined distance in an ejection direction of the ink by the printing unit and that receives the ink ejected from the printing unit, and the ink receiving portion has a lattice shape provided with a plurality of receiving members that receive the ejected ink and a plurality of through-holes that are formed adjacent to the receiving members.
The present invention can provide an inkjet printing apparatus that can reduce smears on a back surface of a print medium by reducing accumulation of ink in a platen while reducing generation of mist.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
A first embodiment of the present invention is described below with reference to the drawings.
Multiple independent support portions 6 (see
In borderless printing in which an image is printed on the entire surface of the print medium 4 with no margins provided in end portions of the print medium 4, the ink is ejected to spread out to a position outside the print medium 4. The platen 5 thus includes ink receiving portions 8 that receive ink drops ejected to spread outside the print medium 4. Moreover, the ink receiving portions 8 are provided at multiple positions in the platen 5 and are each formed in a mesh shape by laying multiple linear receiving members that receive the ink.
Multiple mesh apertures of the receiving members formed in the mesh-shape are through-holes through which the ink that does not land on the receiving members passes. The through-holes are provided adjacent to the receiving members. Specifically, each ink receiving portion 8 is formed of the receiving members and the through-holes. In order to enable borderless printing on various print media 4 varying in width, the ink receiving portions 8 are provided at multiple positions, in the scanning direction (X direction), corresponding to the positions of side end portions 4a of the various print media 4 conveyed by a not-illustrated conveying unit.
The ink drops ejected to the outside of the print medium 4 include ink drops that land on the receiving members of the ink receiving portion 8 as well as ink drops that do not land on the receiving members and pass through the through-holes. Ink drops having a predetermined size (volume) among the ink drops landing on the receiving members and the ink drops passing through the through-holes as described above are described as main drops. The ink drops ejected to the outside of the print medium 4 include ink drops that do not have a predetermined size unlike the main drops and turn into ink mist floating in the air in a mist form. In the platen 5, an ink guide hole 9 is provided below each ink receiving portion 8 to collect the main drops and the ink mist of the ink drops ejected to the ink receiving portion 8. The main drops and the ink mist of the ink drops ejected to the ink receiving portion 8 are guided from the ink receiving portion 8 to the ink guide hole 9.
The mesh-shaped ink receiving portion 8 that receives the ink drops ejected to the outside of the print medium 4 is a plate-shaped porous body which is substantially parallel to the support surfaces 6a and in which many holes (mesh apertures) are formed. Moreover, an area of the hole of the through-holes of the ink receiving portion 8 is desirably greater than the cross-sectional area of the receiving members in the horizontal direction. Making the hole diameter greater than the cross-sectional area of the receiving members forming the ink receiving portion in the horizontal direction reduces the proportion of the ink drops landing on the receiving members of the ink receiving portion 8 and increases the proportion of the ink drops passing through the through-holes to be guided to the ink guide hole 9 in the ink drops ejected to the outside of the side end portion 4a of the print medium 4. Accumulation of the ink on the receiving members of the ink receiving portion 8 can thereby reduced.
As illustrated in
Moreover, an ink flow portion 20 for guiding the ink to the ink guide hole 9 is formed in the −Z direction of the ink receiving portion 8. The ink flow portion 20 includes tilted surfaces that guide the ink to an opening 21 of the ink guide hole 9 and the ink and ink mist that do not directly reach the opening 21 of the ink guide hole 9 adhere to the tilted surfaces. As illustrated in
The ink ejected from the print head 3 is a fine droplet of about 4 pl. Due to the reasons described above, in the case where the size of the droplet adhering to the tilted surface is sufficiently large, the falling energy is greater than the adhesion energy and the droplet falls. However, the smaller the size of the droplet is, the smaller the difference between the adhesion energy and the falling energy is and the droplet is less likely to slide down unless the tilt angle α at which the droplet slides down is set sufficiently large. Accordingly, in the embodiment, the configuration is such that the tilt angle α of the ink flow portion 20 with respect to the horizontal plane is set to about 60 degrees. Note that, in order to cause the droplet to slide down, the tilted surface to which the droplet adheres is desirably close to vertical as a matter of course and the tilt angle is not limited to 60 degrees as long as the configuration of the main body allows.
Moreover, in the case where the ink receiving portion 8 is molded as a resin member by injection molding, as illustrated in
In the embodiment, the cross-sectional shape of each receiving member in the direction of gravity (Z direction) is substantially hexagonal and the parting line is provided on the vertical wall surfaces as illustrated in
Each of the conventional ink receiving portions includes a tilted surface tilted at a certain angle with respect to a print medium support portion to guide the ink landing on the ink receiving portion to an ink guide hole and is connected to the ink guide hole at the lowest position of the tilted surface. In the case where borderless printing is performed in such an ink receiving portion, the ink ejected to the outside of the print medium temporarily lands on the tilted surface of the ink receiving portion. In this case, if the ink is to be landed at a position close to the ink guide hole in the tilted surface as illustrated in
Accordingly, in the conventional ink receiving portion illustrated in
However, in the case where the ink is made to land at a position away from the ink guide hole in the tilted surface as in
In the ink receiving portion 8 in the embodiment, the ink guide hole 9 is provided directly below the end portion of the print medium and the mesh-shaped ink receiving portion 8 is provided at the position away from the back surface of the printing medium at the predetermined interval. The predetermined interval in this case is set to such a distance that no ink mist is generated from the ejected ink drop. The receiving members of the ink receiving portion 8 thereby receive the ejected ink and reduce the generation of mist. For the ink passing through the through-holes of the ink receiving portion 8, the generation of floating mist is reduced by directly guiding the ink turning into mist in air to the ink guide hole 9 or by causing it to adhere to the wall surface of the ink guide hole 9.
Moreover, the cross-sectional shape of the receiving members of the ink receiving portion 8 in the direction of gravity (Z direction) is configured to be polygonal and the ink drops landing on the ink receiving portion 8 are guided to the ink guide hole 9 by using the tilted surfaces of the polygonal shape. Thus, the accumulation of the ink on the ink receiving portion 8 can be reduced.
As described above, the ink receiving portion 8 of the embodiment has a guide structure that guides the ink landing on the receiving members of the ink receiving portion 8 to the ink guide hole 9 with the tilted surfaces while reducing the generation of the ink mist, and can thereby reduce the accumulation of the ink on the receiving members of the ink receiving portion 8.
Note that, in the case where the printing apparatus uses a print head with a large length in the conveyance direction (Y direction) of the print medium, the length of the platen in the conveyance direction of the print medium increases according to the length of the print head and the area of the ink receiving portion increases with this increase in length. In the case where the area of the ink receiving portion 8 increases, the volume of the space which needs to be set to negative pressure to suck the print medium increases. Thus, the negative pressure force per unit area decreases and the suction efficiency decreases. Accordingly, the suction force acting on the print medium decreases and the print medium is more likely to lift in the printing. Hence, in a printer employing a long print head, the area of the ink receiving portion is desirably made as small as possible.
As described above, the ink receiving portion 8 of the platen 5 is provided away from the print medium supported on the support surface, by a predetermined distance. Moreover, the receiving members of the ink receiving portion 8 are formed in the mesh shape and include the tilted surfaces that guide the ink received by the ink receiving portion 8 to the ink guide hole 9. This can reduce the accumulation of the ink in the platen 5 while suppressing the generation of mist and thereby achieve an inkjet printing apparatus that can reduce smears on the back surface of a print result medium.
A second embodiment of the present invention is described below with reference to the drawings. Since the basic configuration of this embodiment is the same as that of the first embodiment, only the characteristic configurations are described below.
Conventionally, a method in which dye ink is used on microporous media have been mainly used to print images such as silver halide photographs from viewpoints of glossiness and the like. However, there is also provided an inkjet printing apparatus that achieves high glossiness while using pigment ink in addition to dye ink from a viewpoint of image fastness.
In the case where a dot diameter of the pigment ink landing on the print medium is compared with that of the dye ink, the dot diameter of the pigment ink is smaller than the dot diameter of the dye ink and is about 0.75 to 0.8 times the dot diameter of the dye ink. This means that, in the case where the pigment ink and the dye ink land on the same print medium surface, the dye ink tends to wet and spread on the print medium and the pigment ink is less likely to wet and spread. The wettability and spreadability of the ink on the print medium surface depend on the contact angle of the ink with the print medium surface. The dye ink has a smaller contact angle with the print medium surface than the pigment ink and tends to wet and spread more than the pigment ink. Meanwhile, the pigment ink has a larger contact angle with the print medium surface than the dye ink and tends to wet and spread less than the dye ink.
Accordingly in the embodiment, in an inkjet printing apparatus that ejects the dye ink, the surfaces of the ink receiving portion 8 and the ink flow portion 20 are modified to hydrophilic surfaces that are highly-wettable surfaces.
Although there are various methods of modifying the surfaces, in the embodiment, the modification is achieved by changing surface roughness of the molds used in the injection molding. Generally, there is such a principle that the closer a solid surface is to a smooth surface without unevenness, the higher the hydrophilic property is. Accordingly, the surfaces of the injection molding molds for the ink receiving portion 8 and the ink flow portion 20 are subjected to polishing or the like to be formed into smooth surfaces and the surfaces of the ink receiving portion 8 and the ink flow portion 20 are thereby made to function as the hydrophilic surfaces. Moreover, a configuration in which a functional liquid for hydrophilic processing is applied or a configuration in which a hydrophilic sheet member is attached may be employed as other means.
As described above, in addition to the first embodiment, the surfaces of the receiving members of the ink receiving portion 8 are formed as hydrophilic surfaces. This can reduce the accumulation of the ink in the platen while reducing the generation of mist and thereby achieve an inkjet printing apparatus that can reduce smears on a back surface of a print result medium.
A third embodiment of the present invention is described below with reference to the drawings. Since the basic configuration of this embodiment is the same as that of the first embodiment, only the characteristic configurations are described below.
In the embodiment, in an inkjet printing apparatus that ejects the pigment ink, the surfaces of the ink receiving portion 8 and the ink flow portion 20 are modified to water-repellent surfaces that are surfaces with low wettability.
Reducing the wettability and spreadability of the ink drop as described above increases the contact angle of the ink drop with the surfaces of the ink receiving portion 8 and the ink flow portion 20 and the ink drop is more likely to be repelled on the surfaces. The ink drop is thereby made less likely to stay in place. Making the ink drop less likely to stay in place as described above enables efficient guiding of the ink drop from the ink receiving portion 8 to the ink guide hole 9 and the ink accumulation on the surfaces can be reduced.
Although there are various methods of modifying the surface of the ink receiving portion 8, in the embodiment, the modification is achieved by changing surface roughness of the molds used in the injection molding. Generally, there is such a principle that the greater the surface area of a solid surface is, that is the greater the unevenness on the surface is, the higher the water repellent property is. Accordingly, a surface of the injection molding mold for the ink receiving portion 8 is roughened by etching or the like to form an uneven shape on the surface and the surface of the ink receiving portion 8 is made to function as the water repellent surface. Moreover, a configuration in which a functional liquid for water repellent processing is applied or a configuration in which a water repellent sheet member is attached may be employed as other means.
As described above, in addition to the first embodiment, the surfaces of the receiving members of the ink receiving portion 8 are formed as water repellent surfaces. This can reduce the accumulation of the ink in the platen while reducing the generation of mist and thereby achieve an inkjet printing apparatus that can reduce smears on a back surface of a print result medium.
A fourth embodiment of the present invention is described below with reference to the drawings. Since the basic configuration of this embodiment is the same as that of the first embodiment, only the characteristic configurations are described below.
In the lattice-shaped mesh illustrated in the first embodiment, in the case where the ink ejected onto the ink receiving portion 8 remains in the mesh aperture, an ink film is sometimes formed in the through-hole due to interfacial tension acting between the lattice and the remaining ink. In the case where the ink film is formed, there is a risk that the ink film increases in viscosity over time and solidifies to block the through-hole and the solidified ink gradually accumulates. Accordingly, it is ideal to suppress the formation of ink film in the through-hole as much as possible.
We examine a lattice shape that can reduce formation of the ink film as much as possible. Assume that force acting on the ink film formed between portions of the lattice (in the through-hole) includes:
interfacial tension (force acting between the ink and the lattice)=force for forming the ink film; and
surface tension (surface tension of the ink)+gravity=force for breaking the ink film.
In this case, the greater the surface tension is relative to the interfacial tension, the greater the effect of suppressing the formation of ink film is exhibited.
The interfacial tension is proportional to a circumferential length [m] of one lattice cell. Moreover, the surface tension is surface free energy per unit area and is expressed in units of [J/m2=N/m]. Accordingly, it is found that, in order to increase the surface tension relative to the interfacial tension, it is effective to reduce the circumferential length [m] per unit area of the through-holes in the ink receiving portion 8.
Employing a circular shape is effective in reducing the circumferential length per unit area. However, in the case of forming a lattice, a circular shape cannot cover a plane without gaps and polygonal shapes are thus considered. Generally, polygonal shapes that can cover a plane include three shapes of regular triangle, square, and regular hexagon and the regular hexagon has the smallest circumferential length, provided that these three shapes have the same area. In other words, designing the lattice shape to be regular hexagon can increase the surface tension relative to the interfacial tension.
Accordingly, in the embodiment, the lattice shape in the ink receiving portion 8 is configured to be a honeycomb (hexagonal) shape to increase the surface tension relative to the interfacial tension. This can suppress formation of the ink film in each through-hole and suppress accumulation of the ejected ink.
As described above, in addition to the first embodiment, in the ink receiving portion 8, the multiple receiving members are laid in the lattice shape that is regular hexagon. This can reduce the accumulation of the ink in the platen while reducing the generation of mist and thereby achieve an inkjet printing apparatus that can reduce smears on the back surface of a print result medium.
A fifth embodiment of the present invention is described below with reference to the drawings. Since the basic configuration of this embodiment is the same as that of the first embodiment, only the characteristic configurations are described below.
As illustrated in
Although the structure in which the outer peripheries of the through-holes with the honeycomb shape are partially absent is described in the embodiment, the cut-away portions may be provided in outer peripheries of through-holes with other polygonal shapes such as, for example, triangle and quadrangle.
Moreover, the outer periphery of the through-hole only needs to be partially absent and the portion that is absent is not limited to a particular portion.
As described above, in addition to the fourth embodiment, in the ink receiving portion 8, the multiple receiving members are laid to have a configuration shape formed of partially-absent hexagons. This can suppress formation of the ink film in the through-holes.
A sixth embodiment of the present invention is described below with reference to the drawings. Since the basic configuration of this embodiment is the same as that of the first embodiment, only the characteristic configurations are described below.
Although the configuration in which cylindrical pillars are arranged is described as an example in the embodiment, configurations in which pillars with polygonal prism shapes such as, for example, triangular prism and quadrangular prism are arranged may be used.
As described above, the receiving members of the ink receiving portion 8 have the configuration in which multiple pillars (pillar bodies) are arranged and this can suppress the formation of ink film.
A seventh embodiment of the present invention is described below with reference to the drawings. Since the basic configuration of this embodiment is the same as that of the first embodiment, only the characteristic configurations are described below.
Moreover, providing the receiving member 8b arranged at a position facing the ink guide hole 9 below the receiving members 8a and 8c in the periphery of the receiving member 8b can provide such an effect that the ink runs down the receiving member 8b and flows downward.
As described above, the receiving members of the ink receiving portion 8 are formed by being laid three-dimensionally to intersect one another in the direction of gravity. This can reduce the accumulation of the ink in the platen while reducing the generation of mist and thereby achieve an inkjet printing apparatus that can reduce smears on a back surface of a print result medium.
Note that the aforementioned embodiments may be carried out in any combination.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2019-160347 filed Sep. 3, 2019, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
---|---|---|---|
JP2019-160347 | Sep 2019 | JP | national |
Number | Name | Date | Kind |
---|---|---|---|
5311214 | Hirasawa et al. | May 1994 | A |
5739828 | Moriyama et al. | Apr 1998 | A |
5887991 | Narita et al. | Mar 1999 | A |
5895155 | Narita et al. | Apr 1999 | A |
6089697 | Tajika et al. | Jul 2000 | A |
6099116 | Fujita et al. | Aug 2000 | A |
6120141 | Tajika et al. | Sep 2000 | A |
6158834 | Kato et al. | Dec 2000 | A |
6196655 | Hirasawa et al. | Mar 2001 | B1 |
6206502 | Kato et al. | Mar 2001 | B1 |
6234606 | Suzuki | May 2001 | B1 |
6264320 | Moriyama et al. | Jul 2001 | B1 |
6309051 | Koitabashi et al. | Oct 2001 | B1 |
6325492 | Koitabashi et al. | Dec 2001 | B1 |
6390583 | Kato et al. | May 2002 | B1 |
6412934 | Moriyama et al. | Jul 2002 | B1 |
6435639 | Nakajima et al. | Aug 2002 | B1 |
6450606 | Kato et al. | Sep 2002 | B1 |
6464328 | Hiramatsu | Oct 2002 | B1 |
6467866 | Nagoshi et al. | Oct 2002 | B1 |
6474768 | Yano et al. | Nov 2002 | B1 |
6494557 | Kato et al. | Dec 2002 | B1 |
6505909 | Kato et al. | Jan 2003 | B1 |
6572216 | Koitabashi et al. | Jun 2003 | B1 |
6585353 | Kanematsu et al. | Jul 2003 | B1 |
6612678 | Kato et al. | Sep 2003 | B2 |
6650350 | Suzuki et al. | Nov 2003 | B2 |
6652053 | Imanaka et al. | Nov 2003 | B2 |
6834947 | Moriyama et al. | Dec 2004 | B2 |
6859220 | Suzuki et al. | Feb 2005 | B2 |
6860578 | Yamada et al. | Mar 2005 | B2 |
6877835 | Kato et al. | Apr 2005 | B2 |
6918656 | Koitabashi et al. | Jul 2005 | B2 |
6966629 | Nakajima et al. | Nov 2005 | B2 |
6986824 | Suzuki et al. | Jan 2006 | B2 |
6988783 | Ikeda et al. | Jan 2006 | B2 |
6991327 | Goto et al. | Jan 2006 | B2 |
7044592 | Sato et al. | May 2006 | B2 |
7097267 | Kato et al. | Aug 2006 | B2 |
7119914 | Nakajima et al. | Oct 2006 | B2 |
7125095 | Yamada et al. | Oct 2006 | B2 |
7144093 | Nakajima et al. | Dec 2006 | B2 |
7281780 | Nagamura et al. | Oct 2007 | B2 |
7347519 | Nagamura et al. | Mar 2008 | B2 |
7367643 | Furuichi et al. | May 2008 | B2 |
7396098 | Kanematsu et al. | Jul 2008 | B2 |
7425056 | Koitabashi et al. | Sep 2008 | B1 |
7460271 | Kanematsu et al. | Dec 2008 | B2 |
7517044 | Suzuki et al. | Apr 2009 | B2 |
7556343 | Kato et al. | Jul 2009 | B2 |
7762640 | Kanda et al. | Jul 2010 | B2 |
7775622 | Suzuki et al. | Aug 2010 | B2 |
7789476 | Tomida et al. | Sep 2010 | B2 |
7891754 | Nagamura et al. | Feb 2011 | B2 |
7980652 | Baba et al. | Jul 2011 | B2 |
8057009 | Tomida et al. | Nov 2011 | B2 |
8388090 | Nakajima et al. | Mar 2013 | B2 |
8444246 | Muro et al. | May 2013 | B2 |
8469484 | Jogo et al. | Jun 2013 | B2 |
8517490 | Kanematsu et al. | Aug 2013 | B2 |
8608277 | Tomida et al. | Dec 2013 | B2 |
8613492 | Suzuki et al. | Dec 2013 | B2 |
8622501 | Komamiya et al. | Jan 2014 | B2 |
8628163 | Kanematsu et al. | Jan 2014 | B2 |
8630017 | Kanematsu et al. | Jan 2014 | B2 |
8636334 | Nishioka et al. | Jan 2014 | B2 |
8675250 | Muro et al. | Mar 2014 | B2 |
8702192 | Danzuka et al. | Apr 2014 | B2 |
8721021 | Nakajima et al. | May 2014 | B2 |
8727477 | Kosaka et al. | May 2014 | B2 |
8757754 | Azuma et al. | Jun 2014 | B2 |
8845060 | Azuma et al. | Sep 2014 | B2 |
8950843 | Oikawa et al. | Feb 2015 | B2 |
9028029 | Azuma et al. | May 2015 | B2 |
9028049 | Azuma et al. | May 2015 | B2 |
9039112 | Murayama et al. | May 2015 | B2 |
9039120 | Nishioka | May 2015 | B2 |
9079421 | Kato et al. | Jul 2015 | B2 |
9108409 | Suzuki et al. | Aug 2015 | B2 |
9114607 | Ishii et al. | Aug 2015 | B2 |
9211748 | Baba et al. | Dec 2015 | B2 |
9340009 | Murayama et al. | May 2016 | B2 |
9434196 | Fukasawa et al. | Sep 2016 | B2 |
9878549 | Fima | Jan 2018 | B1 |
10232644 | Wada et al. | Mar 2019 | B2 |
10668717 | Azuma et al. | Jun 2020 | B2 |
20090021548 | Suzuki et al. | Jan 2009 | A1 |
20090079777 | Nagamura et al. | Mar 2009 | A1 |
20120033006 | Murayama et al. | Feb 2012 | A1 |
20120050360 | Nagamura | Mar 2012 | A1 |
20120069067 | Torigoe et al. | Mar 2012 | A1 |
20130235107 | Ibe et al. | Sep 2013 | A1 |
20160263498 | Kamp | Sep 2016 | A1 |
20160347092 | Kurata | Dec 2016 | A1 |
20170087884 | Wada et al. | Mar 2017 | A1 |
20170297344 | Ibe et al. | Oct 2017 | A1 |
20180353888 | Nie | Dec 2018 | A1 |
20200290359 | Ishizaki | Sep 2020 | A1 |
20200307283 | Nishioka et al. | Oct 2020 | A1 |
Number | Date | Country |
---|---|---|
2017-061076 | Mar 2017 | JP |
Number | Date | Country | |
---|---|---|---|
20210060982 A1 | Mar 2021 | US |