Patent Application
20120014707
Materials such as paints, aerosols, varnishes, polishes, coatings, and oils may emit volatile organic compounds (VOCs) and other air pollutants, some of which may contribute to the formation of ground level ozone or smog. These emissions may be regulated by local and national regulatory agencies to protect the environment and/or health of the populace. In a printer or press, printing ink may be mixed with oil or other solvents that may emit such compounds. It would be desirable to reduce the emission of such compounds from these printers.
Where considered appropriate, reference numerals may be repeated among the drawings to indicate corresponding or analogous elements. Moreover, some of the blocks depicted in the drawings may be combined into a single function.
In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the invention. However, it will be understood by those of ordinary skill in the art that the embodiments of the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to obscure the present invention.
Embodiments of the present invention may be used in a variety of applications. Although the present invention is not limited in this respect, the techniques disclosed herein may be used in paper handling machines such as printers, presses, copiers, multi-function printers, and the like.
In some printers or presses, the oil that carries the printer ink may evaporate into the atmosphere, emitting hydrocarbons including VOCs in the process. Embodiments of the present invention operate to reduce vapor emissions, including VOCs, from such a printer by treating in a chamber, while the machine is operating, vapor-laden air and sealing inlets to the chamber, while the machine is idle, from which the vapors may otherwise escape to the atmosphere.
Reference is now made to
The parts and blocks shown in
Embodiments of the present invention may use a liquid electrophotography (LEP) process to print on a substrate 75, such as coated or uncoated paper or card stock or other media. In LEP, scorotrons 70 charge PIP drum 20. Writing head 10 then uses scanning laser beam 15 to electrostatically charge a latent image onto PIP drum 20. A colorant, such as liquid ink or toner, stored in ink containers 50, may be applied to charged PIP drum 20, using ink rollers 60 (also called “binary ink developers” (BID)). This colorant may be transferred to ITM drum 30, or, more precisely, to a blanket wrapped around ITM drum 30, and then transferred from the blanket to substrate 75 using impression drum 40 to form the image on the substrate.
Liquid ink or toner (an example of which is Hewlett-Packard's ElectroInk®) used in LEP may be a combination of a solid pigment in a liquid solvent or carrier. The solid part may be paste-like and may include micron-sized electrically charged particles. The liquid solvent may be an oil, or an oil mixture (such as HP Imaging Oil), which may include an isoparaffinic fluid such as Isopar® or Isopar-L (made by ExxonMobil Chemical Co.).
During printing, the ink paste may be mixed with the imaging oil and then delivered to the printing area. After printing, the substrate may be dried by evaporating the liquid (oil) part of the ink from the printed image, and then cooling the vapor in a cooling cabinet to recover the oil. This process is shown generally in a conceptual block diagram in
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Besides the benefit of controlling VOC and other vapor emissions (at least 40% reduction in some instances for the printer as a whole), having the ability to open and close the inlet and outlet doors retains and saves the oil (as much as 98% of the printer oil, which may constitute three to four liters or more per day), which can be used when the press begins operating again (e.g., the next day), so much less oil is used and wasted.
Reference is now made to
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Prior attempts to reduce VOC or other emissions included capturing these compounds and destroying them or diverting them to other locations or adding small permanent enclosures around the whole press or large permanent enclosures around the press room or warehouse. These methods still emit the compounds, however. In flexographic printing, which uses an embossed relief plate as in offset printing, enclosed doctor blade chambers have been used to enclose the area right next to the main ink drum (within the printing area), scrape off excess ink from the drum with one or two blades, and return the ink to a reservoir to be used again. But these chambers do not control VOCs emitted from the other printing drums, the printed substrate, or the printing area as a whole. They also do not open and close depending on the operational status of the printer.
In sum, a novel arrangement is described that may be used to reduce VOC or other emissions from a printer, press, or copier by using doors to seal, typically while the machine is idle, inlets to the chamber from which the compounds may escape to the atmosphere. This limits environmental emissions of these compounds. Other benefits of the arrangement are reduced oil consumption, because the oil stays in the printer rather than evaporating to the atmosphere, reduced maintenance, because there is no need to refill oil each day, reduced operation cost, because of the saving of the cost of oil, and reduced environmental impact, because there is less of a need to produce oil.
The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications. It is also intended that the word “printer” in the claims include apparatuses such as presses and copiers, in addition to printers.
