Stock material or miscellaneous articles – Liquid crystal optical display having layer of specified... – With charge transferring layer of specified composition
Reexamination Certificate
1999-04-28
2003-04-08
Hess, Bruce H. (Department: 1774)
Stock material or miscellaneous articles
Liquid crystal optical display having layer of specified...
With charge transferring layer of specified composition
C156S277000, C427S146000, C428S195100, C428S913000
Reexamination Certificate
active
06544601
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to printing using an inkjet printing mechanism, and more particularly to a reusable media that replaces paper for printing in a modified inkjet printing mechanism, and to a printing system and method for using this revolutionary reusable media.
BACKGROUND OF THE INVENTION
Inkjet printing mechanisms use cartridges, often called “pens,” which shoot drops of liquid colorant, referred to generally herein as “ink,” onto a page. Each pen has a printhead formed with very small nozzles through which the ink drops are fired. To print an image on paper media, for instance, the printhead is propelled back and forth across the page, shooting drops of ink in a desired pattern as it moves. The particular ink ejection mechanism within the printhead may take on a variety of different forms known to those skilled in the art, such as those using piezo-electric or thermal printhead technology. For instance, two earlier thermal ink ejection mechanisms are shown in U.S. Pat. Nos. 5,278,584 and 4,683,481, both assigned to the present assignee, Hewlett-Packard Company. In a thermal system, a barrier layer containing ink channels and vaporization chambers is located between a nozzle orifice plate and a substrate layer. This substrate layer typically contains linear arrays of heater elements, such as resistors, which are energized to heat ink within the vaporization chambers. Upon heating, an ink droplet is ejected from a nozzle associated with the energized resistor. By selectively energizing the resistors as the printhead moves across the page, the ink is expelled in a pattern on the print media to form a desired image (e.g., picture, chart or text).
To clean and protect the printhead, typically a “service station” mechanism is mounted within the printer chassis so the printhead can be moved over the station for maintenance. For storage, or during non-printing periods, the service stations usually include a capping system which hermetically seals the printhead nozzles from contaminants and drying. Some caps are also designed to facilitate priming, such as by being connected to a pumping unit that draws a vacuum on the printhead. During operation, clogs in the printhead are periodically cleared by firing a number of drops of ink through each of the nozzles in a process known as “spitting,” with the waste ink being collected in a “spittoon” reservoir portion of the service station. After spitting, uncapping, or occasionally during printing, most service stations have an elastomeric wiper that wipes the printhead surface to remove ink residue, as well as any paper dust or other debris that has collected on the printhead.
Over the last decade or so, hardcopy printing has rapidly become an affordable technology in our every day life for outputting various different types of computer-generated information. The most common print media is paper, although other media are often used, such as transparencies, foil, and fabric, to name a few. For instance, paper media is printed upon and used as a reminder for information.
Despite the advances in electronic information display technology, the use of paper as a hardcopy print media has shown no signs of decline. Indeed, the trend has been toward improving the print media to improve the print quality of the final image, as well as researching new types of hardcopy print media, such as photo-quality paper and printable fabric. Still, thus far, the hardcopy printing technology has focused on providing a permanent print output, while neglecting situations where a reusable printing technology may be preferred. For example, it may be desirable to print a hardcopy output of various reoccurring information, such as printing the current day's news or the daily stock prices from a computer website location. Other situations where reusable media may be preferred are as simple as an electronic mail message from a friend that one would like to share with family, or simply a draft of an article or report that one would like to proofread. It is apparent that there are many different situations where it would be helpful to have hardcopy in hand to read, but a permanent copy of the information is simply not required.
Thus, from both an economical and an environmental point of view, it would be desirable in this information age to have a system for temporarily recording information on a familiar hardcopy output, without later throwing the hardcopy away, wasting both ink and the media, which is typically paper. Granted, paper is recycled today in many homes and offices to lessen the waste of disposing the hardcopy output. Unfortunately, recycling paper has several economic and environmental side effects, such as the additional air pollution caused by vehicles hauling the waste media to the recycling center, as well as the consumption of fossil fuels used to power these vehicles. Furthermore, additional energy, often in the form of electrical energy, is required to process the waste paper at the recycling plant. Thus, it would be desirable to have a reusable media that avoids wasting media and conventional recycling.
One approach recently advertised by the E.I. DuPont de Nemours and Company of Willmington, Del., is an electronic journal display. Here, the user must connect a cable between the computer output and the journal display device. After making this connection, the computer then downloads the information into the journal display device where the information is stored for later reading at a remote site. This journal display device may be useful for reading newspapers and other periodicals, but unfortunately, it is cumbersome to use, requiring the repeated coupling and uncoupling of the cable each time new material is downloaded. Furthermore, a totally separate piece of equipment is required beyond that found in the normal office environment. Thus, it would be desirable to provide a printing mechanism, such as an inkjet printer, which is capable of printing both a permanent record on a single-use or “permanent” print media such as paper, and a temporary image on a reusable print media.
SUMMARY OF THE INVENTION
According to one aspect of the invention, a printing system is provided for temporarily printing an image to a reusable print media having a changeable property that changes the optical appearance of the reusable print media when exposed to a physical effect. The printing system has a chassis and a reusable media printhead supported by the chassis to expose the reusable print media to said physical effect in response to a firing signal to change the optical appearance of the reusable print media to display the image for viewing. The printing system also has a controller that generates the firing signal to print the image to the reusable print media.
In an illustrated embodiment, the printing system comprises an inkjet printing mechanism having an inkjet printhead that is interchangeable with the reusable media printhead, allowing a user to print with inkjet ink on a surface of a print media or to print a temporary image on the reusable print media. In the illustrated embodiments, the printheads may be stationary page-wide arrays or replaceable cartridges carried by a carriage mechanism across a printzone adjacent the media.
According to further aspects of the invention, a reusable media cartridge, as well as a reusable print media, are provided for use in the printing systems described above.
According to an additional aspect of the invention, a method is provided for making a reusable print media that temporarily displays an image after exposure to a physical effect generated in a printzone by a printing mechanism. The method includes the step of supplying a base layer and a changeable layer, with the changeable layer comprising a material having a changeable property that changes the optical appearance of the reusable print media to display the image when exposed to said physical effect by the printing mechanism. In a bonding step, the changeable layer is bonded to the base layer as a flexible sheet for feed
Hess Bruce H.
Hewlett--Packard Development Company, L.P.
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