Incremental printing of symbolic information – Ink jet – Combined
Reexamination Certificate
1998-07-28
2001-03-20
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Combined
C347S218000
Reexamination Certificate
active
06203131
ABSTRACT:
TECHNICAL FIELD
This invention relates to a printer having a first polychromatic print station, a second monochromatic print station, and a pathway between the stations for guiding a continuous strip of media from the first station to the second station and providing a variable length queue between the stations. This arrangement allows printing of a high quality color image and a sharply defined monochromatic image on the same media location while minimizing delays in the printing process.
BACKGROUND INFORMATION
In the printing of bar code labels, it is sometimes desirable or required to have a color image on the label as well as the typically black bar code image. The previous approach to providing printers having the capability of printing such labels has been to utilize a single printing technology in the printer. Since the various known printing technologies have widely differing characteristics in regard to the print quality produced, the use of a single technology to produce both color images and bar code images has required compromises that result in severe limitations on the print quality of the color image and/or the bar code image.
For bar codes and other machine readable symbologies, it is desirable that the printed image have sharp boundaries that are accurately detectable by a machine. Sharp boundaries are produced by pixels (printed dots) that have essentially the same dimensions-as the addressability of the print engine. In order words, the printed dots remain discrete and do not overlap or bleed into each other. The main technologies that meet this criterion are direct thermal and thermal transfer. For color images, color saturation is a major consideration for producing a high quality image. Pixels that are large relative to the addressability of the printer cause undesirable bleeding of bar code borders across narrow spaces in the symbol, significantly hurting readability. On the other hand, relatively large pixels provide the desired color saturation for color images. Technologies that produce relatively large pixels include ink jet, electrophotography, and dot matrix impact.
The different desirable characteristics of bar code and color images and the different technologies that produce these desirable characteristics have led to the compromises referred to above. The standard industry practice has been to use the sharp definition technologies of direct thermal and thermal transfer for the printing of bar codes, whether or not each printed label also includes a color image. Currently existing color bar code printers have generally used thermal transfer technology. The use of this technology has caused either high printer cost or low throughput, i.e. slow printing rates, as well as relatively high media expense. In order to maintain a relatively high throughput, color thermal transfer printers must essentially replicate the entire printing mechanism for each color desired. Therefore, the equipment cost for a color bar code printer that prints black as well as a normal range of colors is nearly four times that of a monochrome printer. One approach to achieving lower printer costs has been to sequentially array on a ribbon all of the colors to be used in the images to be produced by a printer. In such an arrangement, the media must be fed backward and then forward for each color after the first color. The backward and forward feeding causes slow throughput as well as registration inaccuracies. In both the arrangement of multiple print mechanisms and the arrangement of a sequentially arrayed ribbon, a print head lifting mechanism may be required to allow independent feeding of ribbon and paper. Print head lifting mechanisms contribute significantly to reliability problems, noise, and cost.
The failure of the industry to provide an acceptable color bar code printer is a result of a general failure to fully appreciate the nature of the problem and the actual needs of most situations in which bar code labels with color images are to be printed. This lack of understanding has led to the unsuccessful efforts described above. Such efforts have resulted in printer designs that are either excessively expensive or that fail to meet practical needs.
SUMMARY OF THE INVENTION
The present invention provides a printer and a method of printing that avoid or minimize the problems that have been encountered in relation to previous color bar code printers. A major contribution of the invention is a full appreciation of the nature of the problems associated with printing bar code/color image labels and an accurate assessment of the practical requirements for such printing. These requirements are discussed more fully below.
According to an aspect of the invention, a dual technology printer comprises a first print station, a second print station, and pathway means. The first print station has a polychromatic print engine. The second print station has a monochromatic print engine. The pathway means extends between the stations for guiding a continuous strip of media from the first station to the second station and providing a queue between the stations including a variable length of media.
The pathway means may provide the media queue in various ways. In a first embodiment, the pathway means provides a variable length loop of media between the stations. In another embodiment, the pathway means provides an accordion fold arrangement of media between the stations. The strip of media may be fully continuous or may include a number of discrete media segments. For example, the media segments may be discrete adhesive backed labels carried on a continuous liner strip. The specific type of print engines may also be varied. Currently, a polychromatic ink jet print engine and a monochromatic thermal print engine are preferred. As used herein the term “thermal print engine” includes both direct thermal print engines and thermal transfer print engines.
According to another aspect of the invention, a dual technology printer includes first and second print stations and at least one guide roller. The first and second print stations have a polychromatic print engine and a monochromatic print engine, respectively. The guide roller is positioned between and offset from the stations to provide a looped pathway for a media strip between the stations. The roller thereby provides a length of media queued between the stations. The roller is movably mounted to permit the length of media queued between the stations to be varied by adjusting the position of the roller.
The printer may include a single guide roller or a plurality of guide rollers. In the latter case, the guide rollers may be arranged to provide a plurality of loops along the pathway. The single guide roller or one or more of a plurality of guide rollers are preferably movably mounted to permit the queued length of media to be varied.
According to still another aspect of the invention, a dual technology printer comprises a first print station having a polychromatic print engine and a second print station having a monochromatic print engine. The monochromatic print engine has a predetermined pixel addressability and a resolution substantially equal to the addressability to produce sharp borders for machine readable symbologies. A variable length pathway extends from the first print station to the second print station. The pathway provides a queue between the stations including a variable length of a strip of media.
The pathway may include a variable length loop. In such case, preferably, at least one guide roller is positioned between and offset from the stations to define a bight portion of the loop. As a supplement or alternative to the loop, the pathway may include a support for the media in an accordion fold arrangement.
The invention also encompasses a method of printing a polychromatic image and a monochromatic machine readable symbology at a plurality of locations on a strip of media. According to an aspect of the invention, the method comprises providing a first print station having a polychromatic print engine, and a second print stati
Intermec IP Corp.
Le N.
Pauly Joan H.
Pham Hai C.
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