Incremental printing of symbolic information – Thermal marking apparatus or processes – Record receiver and transfer medium feeding or driving means
Reexamination Certificate
2001-04-12
2003-06-03
Nguyen, Lamson (Department: 2861)
Incremental printing of symbolic information
Thermal marking apparatus or processes
Record receiver and transfer medium feeding or driving means
Reexamination Certificate
active
06573923
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to methods and apparatus for printing a graphic product on sheet material in accordance with a printing program and stored data representative of the graphic product, and more particularly to methods and apparatus for printing a wide format multicolor graphic product on a printing sheet, such as a vinyl sheet for use as signage.
Known in the art are thermal printing apparatus for generating signs, designs, characters and other graphic products on a printing sheet in accordance with a printing program and data representative of the graphic product. Typically, a thermal printer interposes a donor sheet that includes donor material and a backing between a thermal printhead and the printing sheet. The thermal printhead includes an array of thermal printing elements. The thermal printhead prints by pressing the donor sheet against the printing sheet and selectively energizing the thermal printing elements of the array, thereby selectively transferring pixels of donor medium from the donor sheet to the printing sheet. Movement of the printing sheet relative to the thermal printhead (or vice versa) while pressing the donor sheet against the printing sheet with the thermal printhead draws fresh donor sheet past the thermal printhead. The printing sheet typically includes a vinyl layer secured to a backing layer by a pressure sensitive adhesive so that after printing the vinyl bearing the graphic product can be cut and stripped from the backing material and affixed to an appropriate sign board or other material for display.
The proper printing of many graphic products, such as commercial artwork or signage, can require high quality print work. Often, it is desired that the final multicolor graphic product be physically large, such as several feet wide by tens of feet long. Typically, existing thermal printers are limited in the width of printing sheet that they can print upon. For example, one popular thermal printer prints on sheets that are one foot wide. Accordingly, the final graphic product is often assembled from separately printed strips of printing sheet that must be secured to the signboard in proper registration with one another. Often, the registration is less than perfect and the quality of the final graphic product suffers, especially when backlit.
Wide format thermal printers are known in the art. For example, one wide format thermal printer currently available can accommodate a printing sheet up to three feet wide and uses four full width (i.e., three feet wide) printheads, each interposing a different color donor sheet between the printhead and the printing sheet. Accordingly, far fewer seams, if any at all, require alignment when creating the sign or other product. Also, the use of four printheads allows faster printing of the multicolor graphic product.
Unfortunately, this type of machine can be expensive to manufacture and to operate. For example, each printhead, at a typical resolution of 300 dpi, includes literally thousands of thermal printing elements, all of which are typically required to have resistances that are within a narrow tolerance range. Such a thermal printhead is difficult and expensive to manufacture, and moreover, burnout of simply a few thermal printing elements can require replacement of the entire printhead. Furthermore, donor sheet is also expensive, and the full-width printing heads can be wasteful of donor sheet when printing certain types of, or certain sections of, graphic products. For example, consider that a single color stripe one inch wide and perhaps a foot long is to be printed in center of the printing sheet. Though the printed object occupies {fraction (1/12)} of a square foot, an area of donor sheet that is three feet wide by one foot long, or three square feet, is transferred past the print head when printing the above object, and hence consumed. The printing of a wide format graphic product that includes a narrow border about the periphery of the printing sheet is another example that typically can be wasteful of donor sheet when printing with the above wide format thermal printer.
Other wide format printers are known in the art, such as wide format ink-jet printers, which can also print in a single pass. However, inkjet printed multicolor graphic products are typically not stable when exposed to the elements (e.g., wind, sun, rain) or require special post-printing treatment to enhance their stability, adding to the cost and complexity of printing with such apparatus.
Accordingly, it is an object of the present invention to address one or more of the foregoing and other deficiencies and disadvantages of the prior art.
Other objects will in part appear hereinafter and in part be apparent to one of ordinary skill in light of the following disclosure, including the claims.
SUMMARY OF THE INVENTION
In one aspect, the invention provides a wide format thermal printer for printing a multicolor graphic product onto a printing sheet in separate color planes and responsive to a controller and machine readable data representative of the graphic product. The wide format thermal printer includes a workbed including a platen and having a worksurface for supporting the printing sheet. The worksurface contains a print axis and printing sheet translation axis perpendicular to the print axis.
The wide format thermal printer also includes a pair of translatable clamps each movable between clamped and unclamped conditions relative to the printing sheet supported on the worksurface, and each extending across the workbed in the direction of the print axis from a first end to second end. The clamps are for translating the printing sheet in the direction of the printing sheet translation axis, and the first ends are mechanically coupled to one another and the second ends are mechanically coupled to one another such that the clamps are substantially fixedly spaced from one another in the direction of the printing sheet translation axis. At least one actuator is coupled to the clamp pair for translating the clamp pair in the direction of the printing sheet translation axis between first and second positions.
Further included is a thermal printhead having an array of thermal printing elements extending parallel to the printing sheet translation axis. The thermal printhead is translatable parallel to the print axis for printing on the printing sheet in print swaths extending parallel to the print axis in an area between the clamps by pressing the donor sheet against the printing sheet and selectively energizing the thermal printing elements.
The wide format thermal printer also includes donor sheet means including a supply shaft for rotationally engaging a supply roll of the donor sheet, a take-up shaft for rotationally engaging a take-up roll for winding thereon donor sheet that has been drawn from the supply roll and interposed between the thermal printhead and the printing sheet, and a take-up motor rotationally coupled to the take-up shaft, the shafts and rolls mounted with the thermal printhead for translation parallel to the print axis therewith. Means for securing the printing sheet to the workbed when printing on the printing sheet and releasing the printing sheet from the workbed when translating the printing sheet are also provided.
According to another aspect, the invention provides a wide format thermal printer for printing a multicolor graphic product onto a printing sheet in separate color planes and responsive to a controller and machine readable data representative of the graphic product. The wide format thermal printer includes a workbed including a platen and having a worksurface for supporting the printing sheet, the worksurface including a print axis and a printing sheet translation axis. Also included are: means for translating the printing sheet along a printing sheet translation axis and means for securing the printing sheet to the workbed when printing on the printing sheet and releasing the printing sheet from the workbed when translating the printing sheet.
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Banavige Michael J.
Binnall Daniel G.
Downey Roy Douglas
Ehrhardt Kurt J.
Hevenor Charles M.
Feggins K.
Gerber Scientific Products, Inc.
McCormick Paulding & Huber LLP
Nguyen Lamson
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