Incremental printing of symbolic information – Thermal marking apparatus or processes – With transfer medium or driving means therefor
Reexamination Certificate
2000-05-16
2001-11-06
Le, N. (Department: 2861)
Incremental printing of symbolic information
Thermal marking apparatus or processes
With transfer medium or driving means therefor
C242S528000
Reexamination Certificate
active
06313859
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to media handling in an image processing apparatus and, more particularly, to an improved apparatus and method for feeding sheet media to a vacuum drum.
BACKGROUND OF THE INVENTION
Pre-press color proofing is a procedure that is used by the printing industry for creating representative images of printed material without the high cost and time that is required to actually produce printing plates and set up a high-speed, high-volume, printing press in order to produce a single example of an intended image. These intended images may require several corrections and may need to be reproduced several times to satisfy customer requirements. This can result in a large loss of profits. By utilizing pre-press color proofing time and money can be saved.
One such commercially available image processing apparatus, which is depicted in commonly assigned U.S. Pat. No. 5,268,708 to Harshbarger et al., is an image processing apparatus having half-tone color proofing capabilities. This image processing apparatus is arranged to form an intended image on a sheet of thermal print media by transferring dye from a sheet of dye donor material to the thermal print media. This is accomplished by applying a sufficient amount of thermal energy to the dye donor material to form an intended image. This image processing apparatus is comprised generally of a material supply assembly or carousel, lathe bed scanning subsystem (which includes a lathe bed scanning frame, translation drive, translation stage member, print-head, and vacuum imaging drum), and thermal print media and dye donor material exit transports.
The operation of the image processing apparatus comprises metering a length of the thermal print media (in roll form) from the material assembly or carousel. The thermal print media is then measured and cut into sheet form of the required length and transported to the vacuum imaging drum, registered, wrapped around and secured onto the vacuum imaging drum. Next a length of dye donor material (in roll form) is also metered out of the material supply assembly or carousel, then measured and cut into sheet form of the required length. It is then transported to and wrapped around the vacuum imaging drum, such that it is superposed in the desired registration with respect to the thermal print media (which has already been secured to the vacuum imaging drum).
After the dye donor material is secured to the periphery of the vacuum imaging drum, the scanning subsystem or write engine provides the scanning function. This is accomplished by retaining the thermal print media and the dye donor material on the spinning vacuum imaging drum while it is rotated past the printhead that will expose the thermal print media. The translation drive then traverses the printhead and translation stage member axially along the vacuum imaging drum, in coordinated motion with the rotating vacuum imaging drum. These movements combine to produce the intended image on the thermal print media.
After the intended image has been written on the thermal print media, the dye donor material is then removed from the vacuum imaging drum. This is done without disturbing the thermal print media that is beneath it. The dye donor material is then transported out of the image processing apparatus by the dye donor material exit transport. Additional dye donor materials are sequentially superposed with the thermal print media on the vacuum imaging drum, then imaged onto the thermal print media as previously mentioned, until the intended image is completed. The completed image on the thermal print media is then unloaded from the vacuum imaging drum and transported to an external holding tray on the image processing apparatus by the receiver sheet material exit transport.
The scanning subsystem, or write engine, of the lathe bed scanning type comprises the mechanism that provides the mechanical actuators for imaging drum positioning and motion control to facilitate placement, loading onto, and removal of the thermal print media and the dye donor material from the vacuum imaging drum. The scanning subsystem, or write engine, provides the scanning function by retaining the thermal print media and dye donor material on the rotating vacuum imaging drum. This generates a once per revolution timing signal to the data path electronics as a clock signal while the translation drive traverses the translation stage member and printhead axially along the vacuum imaging drum in a coordinated motion with the vacuum imaging drum rotating past the printhead. This is done with positional accuracy maintained, to allow precise control of the placement of each pixel, in order to produce the intended image on the thermal print media.
The lathe bed scanning frame provides the structure to support the vacuum imaging drum and its rotational drive. The translation drive with the translation stage member and printhead are supported by the two translation bearing rods, which are substantially straight along their longitudinal axis and positioned parallel to the vacuum imaging drum and lead screw. Consequently, they are parallel to each other, forming a plane along with the vacuum imaging drum and lead screw.
The translation bearing rods are, in turn, supported by the outside walls of the lathe bed scanning frame of the lathe bed scanning subsystem or write engine. The translation bearing rods are positioned and aligned therebetween, for permitting low friction movement of the translation stage member and the translation drive. The translation bearing rods are sufficiently rigid for this application, so as not to sag or distort between the mounting points at their ends. They are preferably as exactly parallel as is possible with the axis of the vacuum imaging drum. The front translation bearing rod is preferably arranged so that the axis of the printhead lies precisely on the axis of the vacuum imaging drum. The axis of the printhead is located perpendicular, vertical, and horizontal to the axis of the vacuum imaging drum. The translation stage member front bearing is arranged to form an inverted “V”. The translation stage member, with the printhead mounted on the translation stage member, is preferably held in place only by its own weight. The rear translation bearing rod locates the translation stage member—with respect to rotation of the translation stage member—about the axis of the front translation bearing rod. This is done so that there is no over constraint of the translation stage member that might cause it to bind, chatter, or otherwise impart undesirable vibration to the translation drive or printhead during the writing process. Such vibrations can cause unacceptable artifacts in the intended image. This benefit is accomplished by the rear bearing, which engages the rear translation bearing rod on the diametrically opposite side of the translation bearing rod on a line that is perpendicular to a line connecting the centerlines of the front and rear translation bearing rods.
The translation drive is for permitting relative movement of the printhead by synchronizing the motion of the printhead and stage assembly such that the required movement is made smoothly and evenly throughout each rotation of the drum. A clock signal generated by a drum encoder provides the necessary reference signal accurately indicating the position of the drum. This coordinated motion results in the printhead tracing out a helical pattern around the periphery of the drum. The coordinated motion is accomplished by means of a DC servo motor and encoder which rotates a lead screw that is typically, aligned parallel with the axis of the vacuum imaging drum. The printhead is preferably placed on the translation stage member in a “V” shaped groove, which is formed in the translation stage member. The printhead is selectively locatable with respect to the translation stage member, thus it is positioned with respect to the vacuum imaging drum surface. By adjusting the distance between the printhead and the vacuum imaging drum surface, as well as angular po
Kerr Roger S.
Sanger Kurt M.
Eastman Kodak Company
Feggins K.
Harleston Law Firm
Le N.
LandOfFree
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