A printer may apply print agents to a paper or another substrate. One example of a printer is a Liquid Electro-Photographic (“LEP”) printer, which may be used to print using a fluid print agent such as an electrostatic printing fluid. Such electrostatic printing fluid includes electrostatically charged or chargeable particles (for example, resin or toner particles which may be colorant particles) dispersed or suspended in a carrier fluid).
In an example of LEP printing, a printing device may form an image on a print substrate by placing an electrostatic charge on a photoconductor, and then utilizing a laser scanning unit to apply an electrostatic pattern of the desired image on the photoconductor to selectively discharge the photoconductor. The selective discharging forms a latent electrostatic image on the photoconductor. The printing device includes a development station to develop the latent image into a visible image by applying a thin layer of electrostatic ink (which may be generally referred to as “LEP ink”, or “electronic ink” in some examples) to the patterned photoconductor. Charged toner particles in the LEP ink adhere to the electrostatic pattern on the photoconductor to form a liquid ink image. The liquid ink image, including colorant particles and carrier fluid, is transferred from the photoconductor to an intermediate transfer member (referred herein as a “blanket”). The blanket is heated until carrier fluid evaporates and colorant particles melt, and a resulting molten film representative of the image is then applied to the surface of the print substrate via pressure and tackiness.
For printing with colored inks, the printing device may include a separate development station for each of the various colored inks. There are typically two process methods for transferring a colored image from the photoreceptor to the substrate. One method is a multi-shot process method in which the process described in the preceding paragraph is repeated a distinct printing separation for each color, and each color is transferred sequentially in distinct passes from the blanket to the substrate until a full image is achieved. With multi-shot printing, for each separation a molten film (with one color) is applied to the surface of the print substrate. A second method is a one-shot process in which multiple color separations are acquired on the blanket via multiple applications (each with one color) of liquid ink in from the photoconductor to the blanket, and then the acquired color separations are transferred in one pass from the blanket to the substrate.
In certain examples of LEP printing the blanket can be heated to improve transferability of the developed image. For slower speed systems, the blanket may heated internally and operate without any drying systems. In these systems the heat of the blanket can dry the image and remove carrier fluid in liquid ink image to improve the transfer of the image to the substrate. For high speed imaging, a dryer system is can be used to hasten evaporation of the carrier fluid and the melting of the colorant particles to form the molten film. Typically, the dryer system will includes fans connected to air knives along the blanket circumference and will blow heated air towards the liquid ink image on the blanket. The applied heated air facilitates removing carrier fluid, e.g. by evaporation, for drying the liquid ink image prior to transferring the image to the substrate.
A significant challenge in blanket heating systems is to complete the evacuation of the liquid carrier from the blanket after the transfer of the molten film from the blanket to the media. Prior to the transfer, the film blocks a portion of the liquid carrier that lays below that film from being evaporated. And as commonly the media will be at or near an ambient temperature, immediately after the ink transfer from the blanket to the media the blanket surface temperature will drop to a level that is too low to ensure proper evaporation of the liquid carrier that was below the film. If not removed, the remaining liquid carrier may disturb the proper blanket functionality, e.g. causing print quality defect called short term memory, sometimes observed as a ghost of previously printed image. Heating the blanket to a point that would permit liquid carrier evaporation even with owing for temperature loss upon contact with the blanket is a possibility, but damage to the blanket is a concern.
In some systems, evacuation of the liquid carrier in this environment may be accomplished by exposing the blanket to intensive ventilation after the molten film is transferred to media. The intensive ventilation is to compensate for a lack of high temperature after the transfer to the media. Intensive ventilation systems can be very expensive, however, with costs including purchase price, space requirements, operating expense, and maintenance expense for the fans and conduits associated with such systems.
To address these issues, various examples described in more detail below provide a system and a method that enables reduction of blanket memory artifacts. In one example, a first transfer of ink is made from a photoconductor to a blanket in contact with the photoconductor. The blanket is to cycle along a path, and the first transfer is to occur at a first arc of the blanket path. A second transfer of the ink is made from the blanket to a media in contact with the blanket. The second transfer occurs at a second arc of the blanket path. A heat source located adjacent to a third arc of the blanket path is utilized to heat an external surface of the blanket. The heating is to occur following the second transfer of the ink.
In this manner the disclosed apparatus and method should significantly reduce memory artifacts associated with a blanket reduction by quickly and efficiently applying heat when needed at a third arc of a blanket path, without the need for an intensive ventilation system. Users of LEP printing systems will enjoy the printed image quality, energy savings, and consumables life extension made possible by the disclosed blanket memory artifact reduction apparatus and method. Installations and utilization of LEP printers should thereby be enhanced.
In an example, first ink transfer engine 102 represents generally a combination of hardware and programming to cause a first transfer of ink from a photoconductor 120 to a blanket 122 that is in contact with the photoconductor 120. The blanket 122 is to cycle along a path 020 in a path direction 128 and the first transfer of ink is caused to occur at a first arc 126 of the blanket path 020. As used herein, to “cycle” refers generally to move in a repeatable course. In examples a repeatable course may be a course determined by a length or course of a belt. In examples the belt may be a continuous belt. In other examples, a repeatable course may be determined by rotation of a drum or other cylinder. In examples, the photoconductor may be a photoconductor drum, a photoconductor belt, a photoconductor plate, or any other form of photoconductor. In examples, the blanket 122 may be situated upon a flexible belt 123, or other belt, and the blanket path may be, or may be determined by, a belt path.
Second ink transfer engine 104 represents generally a combination of hardware and programming to making a second transfer of the ink from the blanket 122 to a media 022 in contact with the blanket 122. In examples, media 022 may be a sheet media and the second transfer is caused to occur at a second arc 132 of the blanket path. In other examples, the media may be a media situated upon a rotating media drum or upon a belt.
First heating engine 106 represents generally a combination of hardware and programming to utilize a heat source 134 located adjacent to a third arc 136 of the blanket path 020 to heat an external surface of the blanket 122. While this disclosure frequently refers to a heat source 134, it should be noted that heat source 134 is not limited to a single component and may comprise multiple heat source components (e.g., multiple laser emitters, multiple infrared lamps, etc.). Heating of the external surface of the blanket 122 is to occur following the second transfer of the ink at the second arc 132, and before the blanket 122 returns to the first arc 126 for a new transfer of ink from the photoconductor 120.
In a particular example, the blanket 122 includes an external surface area of approximately 1 μm to 10 μm, and first heating engine 106 caused the heat source 134 to heat the external surface to a peak temperature of about 90° C. to 160° C. Such heating is focused on the external surface. For example, in some implementations after first heating engine 106 causes the heat source to activate (raising the external surface to between 90° C. to 160° C.), portions of the blanket 122 other than the external surface remain below 60° C.
In some examples, first heating engine 106 utilizes a laser emitter as the heat source 134. In these examples, the laser emitter is located adjacent to the third arc 136 of the blanket path 020 and to heat the external surface of the blanket 122 following the second transfer of the ink. The laser emitter is to emit a burst of light energy to rapidly heat the external surface of the blanket 122 to about 90° C. to 160° C. In certain examples, the rapid heating is accomplished with a burst of light energy lasting less than five milliseconds. In certain examples, the laser emitter may have a power density of between 0.5 and 5 W/mm2. In certain examples, the laser emitter may emit light energy at wavelengths between 700 nm to 1μ, and may have a power consumption of less than 10 W per millimeter of printing width as the light energy is emitted to the blanket 122.
Moving to
Continuing at
In the example of
Continuing with the example of
Moving to
Next a second transfer of ink is made from the blanket to a media situated upon a rotating media drum 130 (
Continuing at
To accelerate the evaporation of the remaining carrier fluid at the blanket, the disclosed examples provide for utilizing a laser emitter or other rapid heat source 134 (
At point 512, after termination of the heating by the first heating source 134 (
In the foregoing discussion of
Memory resource 630 represents generally any number of memory components capable of storing instructions that can be executed by processing resource 640. Memory resource 630 is non-transitory in the sense that it does not encompass a transitory signal but instead is made up of a memory component or memory components to store the relevant instructions. Memory resource 630 may be implemented in a single device or distributed across devices. Likewise, processing resource 640 represents any number of processors capable of executing instructions stored by memory resource 630. Processing resource 640 may be integrated in a single device or distributed across devices. Further, memory resource 630 may be fully or partially integrated in the same device as processing resource 640, or it may be separate but accessible to that device and processing resource 640.
In one example, the program instructions can be part of an installation package that when installed can be executed by processing resource 640 to implement system 100. In this case, memory resource 630 may be a portable medium such as a CD, DVD, or flash drive or a memory maintained by a server from which the installation package can be downloaded and installed. In another example, the program instructions may be part of an application or applications already installed. Here, memory resource 630 can include integrated memory such as a hard drive, solid state drive, or the like.
In
A second transfer of the ink is made from the blanket to a media in contact with the blanket. The second transfer occurs at a second arc of the blanket path (block 704). Referring back to
A heat source located adjacent to a third arc of the blanket path is utilized to heat an external surface of the blanket. The heating is to occur following the second transfer of the ink (block 706). Referring back to
Although the flow diagram of
It is appreciated that the previous description of the disclosed examples is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these examples will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other examples without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the examples shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the blocks or stages of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features, blocks and/or stages are mutually exclusive. The terms “first”, “second”, “third” and so on in the claims merely distinguish different elements and, unless otherwise stated, are not to be specifically associated with a particular order or particular numbering of elements in the disclosure.
This application is a Continuation of U.S. application Ser. No. 16/485,516, filed Aug. 13, 2019, which is a U.S. National Stage Application of International Application No. PCT/EP2017/054814, filed Mar. 1, 2017, each of which is incorporated herein by reference.
Number | Name | Date | Kind |
---|---|---|---|
5978631 | Lee | Nov 1999 | A |
6466756 | Nakashima et al. | Oct 2002 | B1 |
7233762 | Kunii | Jun 2007 | B2 |
8185020 | Yoshie | May 2012 | B2 |
20020146258 | Iida | Oct 2002 | A1 |
20050025534 | Fujita | Feb 2005 | A1 |
20050179721 | Jones et al. | Aug 2005 | A1 |
20110058867 | Kodera | Mar 2011 | A1 |
20120093544 | Sandler | Apr 2012 | A1 |
20150165758 | Sambhy et al. | Jun 2015 | A1 |
20150273817 | Qi et al. | Oct 2015 | A1 |
Number | Date | Country |
---|---|---|
0848304 | Jun 1998 | EP |
2004066804 | Mar 2004 | JP |
2006218721 | Aug 2006 | JP |
2009190366 | Aug 2009 | JP |
100413689 | May 2003 | KR |
WO-2016041598 | Mar 2016 | WO |
WO-2017016599 | Feb 2017 | WO |
Number | Date | Country | |
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20210026278 A1 | Jan 2021 | US |
Number | Date | Country | |
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Parent | 16485516 | US | |
Child | 17066064 | US |