The invention relates to the field of printing systems, and in particular, to serpentine microwave dryers that are used to dry liquid materials that are applied to a print media by the printing system.
Production printing systems for high-volume printing typically utilize a production printer that marks a continuous-form print medium (e.g., paper) with a wet colorant (e.g., an aqueous ink). After marking the continuous-form print medium, a dryer downstream from the production printer is used to dry the colorant applied to the continuous-form print medium. Serpentine microwave dryers may be employed as a dryer for a production printing system in some applications.
A serpentine microwave dryer utilizes microwave energy to heat the colorant to cause a liquid portion of the colorant to evaporate, thereby fixing the colorant to the continuous-form print medium. A microwave source directs the microwave energy down a long axis of a waveguide, and a passageway through a short axis of the waveguide is sized to pass the continuous-form print medium through the waveguide. As the continuous-form print medium traverses the passageway, the wet colorants applied to the continuous-form print medium are exposed to the microwave energy and are heated. In a serpentine microwave dryer, the waveguides have a long axis that traverses the width of the print medium. The waveguides are electromagnetically coupled together in a row along a media path of the continuous-form print medium, and are aligned in the same plane.
One problem with serpentine microwave dryers is that the electromagnetic energy through successive waveguides is attenuated along the media path. The result is that waveguides at the end of the row farthest from the microwave source exhibit a lower microwave power than the waveguides at the front closest to the microwave source. This reduces the drying efficiency of the microwave dryer.
Serpentine microwave dryers and a method of fabricating same are disclosed. The serpentine microwave dryers utilize microwave waveguides that includes passages through a short axis of the microwave waveguides that are sized to pass a continuous-form print medium. A long axis of the microwave waveguides are positioned across a width of a media path of the continuous-from print medium. Electromagnetic energy transported along the microwave waveguides is used to dry wet colorants applied to the continuous-form print medium. At least one of the microwave waveguides has an offset from other microwave waveguides that is perpendicular to the media path of the continuous-form print medium. The offset reduces an attenuation of the electromagnetic energy in microwave waveguide(s) that are offset.
One embodiment comprises a serpentine microwave dryer that dries a wet colorant applied to a continuous-form print medium by a printing system. The serpentine microwave dryer includes a microwave source that generates electromagnetic energy to dry the wet colorant, and a first microwave waveguide having a long axis that is positioned across a width of a media path of the continuous-form print medium, where the first microwave waveguide has a first end that is electromagnetically coupled to the microwave source, a second end distal to the first end, and a first passageway through a short axis of the first microwave waveguide that is sized to pass the continuous-form print medium from the printing system through the first microwave waveguide. The serpentine microwave dryer further includes a second microwave waveguide having a long axis that is positioned across the width of the media path, where the second microwave waveguide has a third end that is electromagnetically coupled to the second end of the first microwave waveguide, a fourth end distal to the third end, and a second passageway through a short axis of the second microwave waveguide that is sized to pass the continuous-form print medium from the first microwave waveguide through the second microwave waveguide, where the second microwave waveguide has a first offset that is perpendicular to a plane of the media path from the first microwave waveguide to reduce an attenuation of the electromagnetic energy at the second microwave waveguide.
Another embodiment comprises a method of fabricating a serpentine microwave dryer that dries a wet colorant applied to a continuous-form print medium by a printing system. The method comprises positioning a long axis of a first microwave waveguide across a width of a media path of the continuous-form print medium, where the first microwave waveguide has a first end that is electromagnetically coupled to a microwave source that generates electromagnetic energy, a second end distal to the first end, and a first passageway through a short axis of the first microwave waveguide that is sized to pass the continuous-form print medium from the printing system through the first microwave waveguide. The method further comprises positioning a long axis of a second microwave waveguide across the width of the media path, where the second microwave waveguide has a third end that is electromagnetically coupled to the second end of the first microwave waveguide, a fourth end distal to the first end, and a second passageway through a short axis of the second microwave waveguide that is sized to pass the continuous-form print medium from the first microwave waveguide through the second microwave waveguide. The method further comprises offsetting the second microwave waveguide perpendicular to a plane of the media path a first amount from the first microwave waveguide to reduce an attenuation of the electromagnetic energy at the second microwave waveguide.
Another embodiment comprises a printing system that includes a printer that applies a wet colorant to a continuous-form print medium. The printing system further includes a serpentine microwave dryer downstream of the printer along a media path of the continuous-form print medium that dries the wet colorant utilizing electromagnetic energy. The serpentine microwave dryer includes a 2.4 Gigahertz microwave source that generates electromagnetic energy to dry the wet colorant, and a first microwave waveguide having a long axis that is positioned across a width of the media path, a first end that is electromagnetically coupled to the 2.4 Gigahertz microwave source, a second end distal to the first end, and a first passageway through a short axis of the first microwave waveguide that is sized to pass the continuous-form print medium from the printing system through the first microwave waveguide. The serpentine microwave dryer further includes a bend coupler electromagnetically coupled to the second end of the first microwave waveguide, and a second microwave waveguide having a long axis that is positioned across the width of the media path, a third end that is electromagnetically coupled to the bend coupler, a fourth end distal to the third end, and a second passageway through a short axis of the second microwave waveguide that is sized to pass the continuous-form print medium from the first microwave waveguide through the second microwave waveguide, where the second microwave waveguide has an first offset between 1 millimeter and 5 millimeters that is perpendicular to a plane of the media path from the first microwave waveguide to reduce an attenuation of the electromagnetic energy at the second microwave waveguide.
Other exemplary embodiments may be described below.
Some embodiments of the present invention are now described, by way of example only, and with reference to the accompanying drawings. The same reference number represents the same element or the same type of element on all drawings.
The figures and the following description illustrate specific exemplary embodiments of the invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within the scope of the invention. Furthermore, any examples described herein are intended to aid in understanding the principles of the invention, and are to be construed as being without limitation to such specifically recited examples and conditions. As a result, the invention is not limited to the specific embodiments or examples described below, but by the claims and their equivalents.
In this embodiment, printing system 100 includes a printer 102 and a serpentine microwave dryer 108. Printer 102 applies a wet colorant to a top side 114 of print medium 112, which is then dried by serpentine microwave dryer 108. In printing system 100, a print controller 104 of printer 102 receives print data 110 for imprinting onto print medium 112, which is rasterized by print controller 104 into bitmap data. The bitmap data is used by a print engine 106 (e.g., a drop-on-demand print engine, a continuous-ejection print engine, etc.) of printer 102 to apply wet colorants to print medium 112. Print medium 112 travels downstream of printer 102 to serpentine microwave dryer 108. Serpentine microwave dryer 108 applies electromagnetic energy (e.g., microwave energy) to print medium 112 utilizing one or more microwave waveguides 118, which heat the wet colorants applied to print medium 112 and evaporates a liquid portion of the wet colorants. This fixes the wet colorants to print medium 112. In this embodiment, microwave waveguides 118 have an offset 120 (e.g. a first offset) from each other that improves the drying capability for serpentine microwave dryer 108 by reducing the attenuation that occurs in waveguides that are aligned in the same plane. Although printer 102 and serpentine microwave dryer 108 are illustrated as separate elements in
In serpentine microwave dryers, microwave waveguides have a long axis that span a width of media path 116 of the print medium, and further include passageways through a short axis that are sized to pass the print medium through the microwave waveguides. The microwave waveguides are also electromagnetically coupled together in a pattern such that microwave energy injected into one end of a microwave waveguide follows a serpentine path (e.g., an “S” pattern) from one end to another end of each of the microwave waveguides.
In serpentine microwave dryer 200, each of microwave waveguides 204-207 lie in the same plane. For example, if each of microwave waveguides 204-207 has the same height, width, and length, then the top surfaces of microwave waveguides 204-207 are aligned and the bottom surfaces of microwave waveguides 204-207 are aligned.
As the microwaves travel from microwave waveguide 204 to microwave waveguide 207, the presence of print medium 201 within microwave waveguides 204-207 attenuates the electric field strength of the microwave energy from one waveguide to another at the same operating point (e.g., at the same point within subsequent waveguides along media path 203). The result of this is that for the same operating point, the electric field strength in microwave waveguide 207 is lower than the electric field strength in microwave waveguide 204.
A conventional operating point 305 is illustrated in
In
In some embodiments, offset 601 is based on a tolerance for a movement of print medium 112 perpendicular to a plane of media path 116 (e.g., vertically displacement of print medium 112 in
In some embodiments, first and second microwave waveguides 602-603 may include a plurality of guides 610 that prevent print medium 112 from fluttering and/or contacting the interior of first and second microwave waveguides 602-603. Guides 610 are in contact with print medium 112 on a side (e.g., a bottom side 612) that does not include the wet colorant. Guides 610 may comprise rods, roller, or combinations of rods and roller. Guides 610 may also be formed from a material that is transparent to electromagnetic energy. This prevents guides 610 from interfering with the transmission of electromagnetic energy within first and second microwave waveguides 602-603.
Electromagnetic energy generated by microwave source 704 travels from first end 706 of first microwave waveguide 602 to second end 708 of first microwave waveguide 602, where bend coupler 712 (e.g., an e-bend coupler) is able to re-direct electromagnetic energy into second microwave waveguide 603. Electromagnetic energy then travels from third end 710 of second microwave waveguide 603 to a fourth end 714 of second microwave waveguide 603 that is distal to third end 710. If second microwave waveguide 603 is the last waveguide in a row of waveguides, then a shorting plate 724 may be located at second end 714 of second microwave waveguide 603 as a termination element.
Although
To fabricate serpentine microwave dryer 108, first microwave waveguide 602 has a long axis 716 that is positioned across width 702 of media path 116 for print medium 112. As discussed previously, first microwave waveguide 602 has microwave source 704 coupled to first end 706, which generates electromagnetic energy. First microwave waveguide 602 also includes first passageway 608 through a short axis 718, which is sized to pass print medium 112 through an interior of first microwave waveguide 602 (see
Utilizing offset waveguides, the efficiency and drying performance of serpentine microwave dryer 108 is improved over aligned waveguides. This improvement may result in lower operating costs for serpentine microwave dryer 108, since the overall efficiency of serpentine microwave dryer 108 has been increased (e.g., lower electrical costs). This improvement may also result in reducing the footprint for serpentine microwave dryer 108, since a fewer number of waveguides may be sufficient to ensure that the wet colorants applied to print medium 112 are adequately dried.
Although specific embodiments were described herein, the scope of the invention is not limited to those specific embodiments. The scope of the invention is defined by the following claims and any equivalents thereof.
Number | Name | Date | Kind |
---|---|---|---|
4214379 | Hope et al. | Jul 1980 | A |
4570045 | Jeppson | Feb 1986 | A |
5422463 | Gooray et al. | Jun 1995 | A |
5958275 | Joines et al. | Sep 1999 | A |
6259077 | Drozd | Jul 2001 | B1 |
6470597 | Stipp | Oct 2002 | B1 |
6525752 | Vackier et al. | Feb 2003 | B2 |
6906297 | Tops | Jun 2005 | B2 |
7014309 | Aukerman | Mar 2006 | B2 |
7091457 | Gregoire et al. | Aug 2006 | B2 |
7211299 | Siegel | May 2007 | B2 |
7298994 | Morgenweck et al. | Nov 2007 | B2 |
8426784 | Drozd | Apr 2013 | B2 |
8955957 | Boland et al. | Feb 2015 | B2 |
9327524 | Yamada et al. | May 2016 | B1 |
20030081098 | Wotton | May 2003 | A1 |
20140103031 | Peelamedu | Apr 2014 | A1 |
20150210089 | Biegelsen | Jul 2015 | A1 |
20160013056 | Kasai et al. | Jan 2016 | A1 |
20160309549 | Kimrey et al. | Oct 2016 | A1 |
Entry |
---|
Frederick W. Ahrens; Application of a Device for Uniform Web Drying and Preheating Using Microwave Energy; Final Report; Sep. 2003, entire document. |