Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
2001-12-28
2003-01-14
Hallacher, Craig (Department: 2861)
Incremental printing of symbolic information
Ink jet
Controller
C347S005000, C347S035000, C347S106000
Reexamination Certificate
active
06505906
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to a method for exercising the nozzles of an inkjet printer as may be used in a photofinishing operation to produce a print medium such as a sheet of photographs that is subsequently cut into individual photos. More particularly the invention relates to exercising the nozzles of the print head to produce fiducial registration marks on a print medium wherein the fiducial marks act as an image locator for improving the accuracy of cutting the individual photos from the larger sheet of print medium.
BACKGROUND OF THE INVENTION
In photofinishing operations it is conventional to develop and print photographs on roll stock photographic paper having a width that generally accommodates one size of print. After printing out a roll of photos on a piece of the roll stock, the printed piece is cut to provide the individual prints each cut severing one of the prints from the strip. Dedicating a given width of roll stock to the production of a given size photo is less flexible for fulfilling print orders and slows throughput. It requires the photofinishing operation either to have multiple machines, each dedicated to a given size of photo or it places a burden on the operator to change the print media from one size to another after completing orders.
Advancements in photofinishing allow for the production of photographs by ink jet printers, laser printers and other photofinishing printer systems not dependent upon traditional wet chemistry. Such printers for example produce the image from a digital memory. Moreover, the use of computers in connection with these advancements allows for further improvement. For example, with a computer controlled printer it is not necessary to use roll stock having the width of a desired finished photo. A photofinishing printer now can generate photos of various sizes on a single sheet of print media. Also the images can be manipulated to arrange multiple images on a single larger sheet. The single sheet then is cut longitudinally and transversely to separate the individual photographs.
Most inkjet print heads encounter several problems if left unused out in the atmosphere. Chemical components in the ink slowly evaporate from the exposed meniscus at each nozzle causing the ink to locally increase in viscosity, become increasingly concentrated with dye, or otherwise be inconsistent with the bulk ink properties. If left unchecked, the printing resulting from using these aged nozzles would result in decreased image quality. To prevent these problems, new print heads are shipped with tape covering the nozzle plate that is removed when the print head is installed. During operation, a capping station within the printer seals the nozzle plate, preventing evaporation of the ink during periods of inactivity. For inks with an especially short decap time, the nozzles must be fired periodically when the printer is uncapped.
A most convenient way to keep nozzles “fresh” is to occasionally spit from every nozzle into a single spittoon located at a service station a few centimeters away from the printed image. This does not present a productivity issue in conventional operations because even when printing in a high quality mode on special paper, the action is taken infrequently. For example the action may be taken after every few pages are printed. However, in a commercial photofinishing operation, the nozzles must be freshened more frequently. This is because commercial photographic printing must be of the highest quality and defects at the print edges are not tolerated. Also, print quality must be maintained in various different environmental conditions and it is understood that nozzles must be exercised more in cold and dry environments than in humid environments. It also is understood that all nozzles in the print head need not be exercised at the same frequency. Depending upon such factors, among others, such as the particular color, composition, consistency and throughput, some nozzles must be exercised more often than others.
One alternative to spitting all nozzles into a spittoon is to exercise the nozzles by firing onto the print medium during printing. This allows a more consistent production since it avoids the delays associated with interrupting the printing operation and indexing the print head to a distant spittoon.
After printing and when cutting single images from a larger sheet there are several sources of errors such as offset errors that contribute to inaccuracies in making the several cuts necessary to produce the single image. For example, the printer can misalign the images on the larger sheet of print medium. Mechanism skew, drive roller tolerance, cutter positioning errors and resolution also contribute to cutting errors. To some extent over-printing the images to a size slightly larger than the finished photograph size can compensate for these errors. By over-printing, portions of the image can be removed during cutting without materially altering the image.
Mechanical sensors for detecting the edge of the sheet also can remedy these errors to some extent. However, errors associated with mechanical paper edge sensors are large. Often the tolerance inherent with mechanical edge sensors is larger than the plus or minus 1.0 mm of over-printing commonly used. In view of the problems associated with the precise placement of inkjet printed images as noted above, the present invention has as an object the utilization of the exercise from the inkjet to improve accuracy in locating the image.
Accordingly, an object of the present invention is to provide a method for simultaneously exercising the nozzles of an inkjet print head and printing fiducial marks on the print medium.
Another object of the present invention is to provide a method for exercising the nozzles of an inkjet printer wherein the exercise is used to print fiducial marks that are in registry with printed images on a larger sheet of the print medium.
Still another object of the present invention is to provide an ink jet printed segment having a fiducial mark composed of the exercise of a nozzle associated with an image on the segment for identifying the location of one or more printed images on the sheet.
SUMMARY OF THE INVENTION
In the present invention an inkjet printer, laser printer or the like is used to print one or more photographs onto a larger sheet, preferably photographic paper. The photographs are generated from a digital file and a computer is programmed to array the images on the sheet to best utilize the space available. Where image size and number permit, the photographs can be arrayed in aligned transverse rows and aligned longitudinal columns. Preferably, the print sizes are selected and arranged on the sheet so that all the prints in any given row have aligned leading and trailing edges. The computer further generates the location of fiducial marks relative to the array of images and these fiducial marks are printed together with the photographic images. Preferably, two fiducial marks are printed together with the images. A first fiducial mark extends across the leading edge of the sheet in advance of a first row of photographic images. A second fiducial mark is printed along a lateral edge of the sheet and orthogonal to the first fiducial mark so fiducial marks along two axes are formed.
The printing of the fiducial marks is accomplished by an exercise of the print head nozzles. The marks are printed in a known size and a known distance from the images printed on the print medium and from other locations such as the edges of the printing medium. The printed marks preferably are composed of a combination of subtractive printing colors of each of the colors contained in the printing system. The amounts and relative ratios of each color used in the nozzle exercise are determined based on the specific necessity of each color to be exercised. For example, one color may require twice the number of nozzle firings relative to another color to remain healthy. Accordingly, a print pattern first is determined that will work to ex
Bland William E.
Chang Terence Chee Sung
Puyot Michael
Ramaswamy Rajan
Aceto, Esq. Roger
Hallacher Craig
Harter Secrest & Emery LLP
Phogenix Imaging LLC
Salai Esq. Stephen B.
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