Incremental printing of symbolic information – Thermal marking apparatus or processes – Record receiver driving means
Reexamination Certificate
2000-12-09
2001-11-06
Tran, Huan (Department: 2861)
Incremental printing of symbolic information
Thermal marking apparatus or processes
Record receiver driving means
C400S618000
Reexamination Certificate
active
06313861
ABSTRACT:
BACKGROUND OF THE INVENTION
The instant invention relates generally to thermal printing devices and more particularly to a thermal label printing device having a printing film saving system wherein the print head is lifted during media advancement so that the print film is not advanced during media advancement, and an associated arrangement for tensioning of the print media during printing and print head lifting operations so that the printing film does not pull upwardly when the print head is lifted.
Currently available thermal transfer printing heads generally comprise a plurality of thermal elements. The heating elements are generally provided on one side of a flat substrate of ceramic or like material along with the requisite electronic circuitry for controlling the activation of the heating elements.
The thermal transfer printing head is typically used in conjunction with a roller platen assembly and ink transfer printing film or ribbon, which carries a thermally transferable printing ink. During printing, a web of material to be printed is oriented between the thermal elements of the printing head and the roller platen of the roller platen assembly such that the printing ribbon is adjacent to the print head and the material to be printed is adjacent to the roller platen. The roller platen and printing head are moved against each other so that the printing ribbon and the material to be printed are pressed against the printing head such that when selected thermal elements of the printing head are heated, ink from the ink transfer printing ribbon is transferred to the surface of the material.
Thermal transfer printers such as these are often used to print adhesive labels wherein the adhesive labels are serially mounted on a continuous web. These label printers typically have a single drive means located downstream of the print head for drawing or pulling the web from the web supply through the print head. As the web is advanced or pulled through the printing device, the heating elements of the print head are selectively energized so that the print head is only selectively operative for printing on the adhesive label portion of the web rather than on the intermediate portions of the web backing. The labels are printed serially as they pass through the print head and are advanced out of the printer wherein they are either wound on a spool for later use or presented for use by an operator. Such label printers have found widespread acceptance in industries wherein a plurality of adhesive labels is printed identically.
However, in other industries where it is desired to repeatedly change the printing on the labels, such as for example in the individual printing of shipping labels, there are drawbacks to using the same type of continuous printing as for the identical label. The primary problem relates to the use of a continuous web with serial labels, the position of the just printed label with regard to the print head immediately after printing, and the proximity of the exit opening in relation to the print head and the drive assembly. Because the labels are serially mounted on the carrier web, the freshly printed label is still positioned near to the print head after printing, and is still within the drive means. While the exit end of the print head is adjacent to the exit opening in the device, the entire label or a portion of this just printed label is still not immediately accessible to the operator for removal from the web. In this case, the first printed label cannot be removed for use until several additional labels have been printed and have thus advanced the first label outwardly far enough to be accessible. Serially printing labels in this manner and allowing several labels to be backed up within the printer can cause errors in matching the labels with packages or other goods upon which the labels are to be placed.
Accordingly, there is a need for a label printer that can effectively function under both scenarios, i.e. serially printing a plurality of identical labels, or individually printing labels one at a time.
SUMMARY OF THE INVENTION
In this regard, the instant invention provides a solution to the above-noted need. The instant invention solves the noted problems by providing two improved mechanisms in the printing engine. The first improvement comprises the provision of a print head lifting mechanism, wherein the print head is lifted away from the print media during operation. Print head lifting mechanisms have also been used in the past for single station thermal color print engines wherein a single print head is used to print in color on the print media. The print head lifting mechanism provides two significant functional advantages in this arrangement. The first advantage is in allowing the print media to be quickly advanced and retracted without being held by the print head. In this manner, after an individual label is printed, the print head can be lifted, and the label advanced out of the printer for removal. The print media can then be retracted for printing of the next label. The second advantage is in print film saving. By lifting the print head out of engagement with the print media during media advancement, the apparatus does not draw print film during periods when no printing occurs, i.e. while the print head is lifted. The second improvement comprises the use of a print media tensioning system to maintain tension of the print media during operation. Lifting of the print head from the print media permits the print media to move during advancement and retraction and often can cause mis-registration when the print head is lowered back into engagement with the print media. In addition, because thermal printing involves the heated transfer of printing ink from the film to the media, the printing film can sometimes stick to the print media. Lifting of the print head from the print media can thus pull the print media upwardly with the printing film and further cause registration problems and smudging of the ink.
The print media tensioning system generally comprises the use of two tensioning devices, a first device located upstream of the print head and a second device located downstream of the print head. The use of upstream and downstream tensioning device serves to effectively holds the print media taught at both ends even when the print head is not in engagement with the platen.
More specifically, a continuous web of labels comprises a plurality of adhesive backed labels serially mounted on a continuous backing web from which the labels can be removed during operation. The thermal transfer printer comprises a supply roll for carrying a supply of the continuous web of labels and a take up roll for taking up the backing web as the labels are printed and removed from the backing web. The supply roll includes a back tensioning clutch for tensioning removal of the web from the supply.
In a first embodiment, a color print engine comprises four serial print heads, each of which print a single color, i.e. cyan, magenta, yellow and black, as the labels advance through the printer. This arrangement would typically be used to serially print a plurality of identical labels. Each printing mechanism includes a platen and a thermal print head mounted for biased engagement with the platen. The backing web passes intermediate the thermal print head and the platen. In addition, a thermal printing film passes intermediate the backing web and the thermal print head. Each printing mechanism includes a print head lifting mechanism that is selectively engageable with the print head for moving the print head between a first position wherein the print head—is biased into engagement with the platen, and a second position wherein the print head is lifted out of engagement with the platen. Movement of the web through the apparatus is accomplished by a nip or feed drive positioned forwardly of the printing mechanism for pulling the continuous web forwardly through the printing mechanism when the print heads are in the engaged position. Images are printed on the labels during this f
Astro-Med Inc.
Barlow Josephs & Holmes
Tran Huan
LandOfFree
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