Incremental printing of symbolic information – Ink jet – Medium and processing means
Reexamination Certificate
2000-02-23
2003-02-25
Tran, Huan (Department: 2853)
Incremental printing of symbolic information
Ink jet
Medium and processing means
C428S001600
Reexamination Certificate
active
06523949
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to an apparatus for variable image printing. More particularly, the invention relates to an inkjet printer for printing variable identifying information on plain paper label stock, linerless label stock and tape to be applied to the outside of a container, such as a cardboard box or carton.
BACKGROUND OF THE INVENTION
Manufacturers of products who ship their goods in a container, such as a cardboard box or carton, referred to herein as a case, often desire to apply a label to the outside of the case. The label typically has identifying information, such as product codes, stock or lot numbers, bar codes and shipping data, printed thereon to identify the manufacturer of the goods, the contents of the case or the destination of the case. The label has a first side, referred to herein as the face, on which the identifying information is printed and a second side opposite the face which is coated with a pressure sensitive adhesive. The adhesive side of the label is applied to the outside of the case so that the identifying information on the face of the label is available to be read either manually or by an electronic scanner.
If the identifying information for two or more successive cases is the same, it can be pre-printed on the label, for example, by a flexo-graphic printing process, and applied to the outside of the case by a conventional label applicator. Often, however, the identifying information for successive cases varies so that the manufacturer, the contents, or the destination of a single case or a series of cases can be readily identified. The process of printing variable identifying information on a label or on a series of labels is known as variable image printing. The present practice is to print the variable identifying information on plain paper label stock using a direct contact printer immediately before the label is applied to the case. As used herein, the term plain paper label stock refers to labels having a plain paper surface on one side and an activated chemical adhesive surface on the other side that is protected by a liner coated with a release film which must be removed before the label is applied to the case.
Plain paper label stock, linerless label stock and tape can be manufactured in a continuous roll and wound onto a spool mounted on an unwind spool spindle driven by a conventional motor. Plain paper label stock, however, is expensive relative to linerless label stock and tape. In addition, plain paper label stock requires specially designed equipment to remove the liner before the label is applied to the case. Plain paper label stock is typically applied to the case by a tamp head positioned on the end of a pneumatic or hydraulic tamp. The plain paper label stock is held on the face of the tamp by a vacuum created behind the tamp head and is transferred to the case by activating an air jet in the direction of the case. The liner of the plain paper label stock, however, must be removed before the label is transferred to the case. Further, the equipment required to position the plain paper label stock on the tamp head and to transfer the label to the case is susceptible to misfeeding and malfunctioning. Thus, the cost of variable image printing on plain paper label stock and the additional equipment required to remove the liner and apply the label to a case decreases the productivity and increases the complexity of the labeling process.
The same manufacturers often utilize automated production lines to package, seal and label cases. A typical production line includes a sealing station where the case is sealed with an adhesive sealing tape and a separate labeling station where a plain paper stock label is applied to the case. If variable identifying information is to be printed on the label, the labeling station includes a variable image printer. It has long been recognized that combining the sealing and labeling stations would result in increased productivity, and thus increase profitability. However, the full advantages of a combined sealing and labeling station cannot be realized unless the station is capable of printing variable identifying information onto a label and sealing the case with the label at the same speed or faster than the speed of the production line, which is between about 8 and about 24 inches per second, and preferably is at least about 16 inches per second. Direct contact variable image printers, and in particular thermal transfer printers, are limited to operating speeds of less than about 12 inches per second at a resolution of about 300 dots per inch or less.
As a result, manufacturers presently combine the tasks of sealing and labeling a case only when the information to be printed on the labels is constant. This is accomplished by utilizing a continuous roll of linerless label stock or adhesive sealing tape having the identifying information preprinted on the face of the linerless label stock or tape. Until now, the difficulties that manufacturers have had to overcome to simultaneously seal and label a case when variable identifying information is to be printed on the linerless label stock or tape have proven insurmountable. The primary difficulty is that the adhesive side of the linerless label stock or tape must be supported against the pressure of the print head as the ink is transferred to the face of the label or tape. As a result, the adhesive side of the linerless label stock or tape adheres to the supporting structure, typically one or more platen rollers, or the adhesive accumulates on the exterior surfaces of the supporting structure. Another difficulty is that conventional ink formulations do not adequately adhere to the release agent on the face of the linerless label stock or tape. A further difficulty is that the linerless label stock or tape must be printed and applied at a rate that is compatible with a conventional high-speed production line.
The adhesive side of the linerless label stock or tape can be supported against the pressure of the print head by a platen roller having a TEFLON®, silicon or plasma exterior surface, or that is itself coated with a suitable release film. The linerless label stock and tape currently utilized for sealing cases, however, typically have an exceptionally strong adhesive to insure that the case does not break open during handling. Over time, the adhesive accumulates on the platen roller or strips the TEFLON®, silicon, plasma or release film from the exterior surface of the platen roller. If either instance occurs, the case will likely be inadequately sealed. Thus, the condition of the platen roller and the adhesive on the linerless label stock or tape must be monitored closely. The platen roller must be replaced or the coating must be reapplied at regular intervals, thereby decreasing productivity and increasing the maintenance required to operate the combined sealing and labeling station on the production line.
A dry chemical adhesive that must be wetted to activate the adhesive could be used, and the linerless label stock or tape could be printed with the variable identifying information just before the adhesive is wetted. The platen roller would then support only the dry adhesive side of the linerless label stock or tape against the pressure of the print head while the variable identifying information is printed. A dry adhesive that requires wetting immediately prior to application, however, typically does not produce an adhesive bond that is adequate to insure that the case remains closed during normal handling and shipping conditions. Further, the use of a dry chemical adhesive requires the introduction of an additional mechanism to activate the adhesive. Any such additional mechanism increases the complexity of the sealing and labeling station, thereby decreasing productivity and increasing the maintenance required to operate the combined sealing and labeling station on the production line.
The assignee of the present invention has previously developed a unique thermal transfer printer for variable image printin
Dremann Christopher C.
Dudding Alfred
Tran Huan
LandOfFree
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