Patent Application
20090033732
The printer and the method of printing medium loading and unloading relate to digital printing and particularly to high-speed inkjet printing.
Inkjet printing is a well known in the art printing method. The basics of this technology are described, for example by Jerome L. Johnson “Principles of Non-impact Printing”, Palatino Press, 1992, Pages 302-336. ISBN 0-9618005-2-6. Commercial products such as computer printers, large format graphics printers and others exist.
An ink-jet print head consists of an array or a matrix of ink nozzles, with each nozzle selectively ejecting ink droplets towards a printing medium. The printing medium could be mounted on a drum, flat bed or just pulled from one roll to other. Relative movement between the print head and the medium allows image printing. Drum printers are the fastest of all known printer architectures, since at least in one direction (drum rotation) the medium movement is a continuous one. Recently, page wide or sheet wide arrays have become popular. They have further increased printer throughput. However, for exchange of the imaged or printed medium on a new one requires complete stop of the drum rotation.
This medium loading and unloading process, especially for wide format printers, where the medium may be 2×5 m2 wide, reduces printer utilization and overall printer throughput. Therefore, there is a need in a method and printer that would perform the medium loading and unloading process without loosing the time and interrupting the printing process.
The printer and the method of loading and unloading the medium are particularly pointed out and distinctly claimed in the concluding portion of the specification. The apparatus and the method, however, both as to organization and method of operation, may best be understood by reference to the following detailed description when read with the accompanied drawings, in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the method.
In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the printer may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “leading,” “trailing,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments of the present invention can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present printer and method are defined by the appended claims.
Drum 108 driven by motor 158, rotates around its rotational axis 162. Each of platens or platens 138, 146, and 150 of medium loading module 130 has a freedom of linear reciprocating movement in the directions shown by elongated oval openings 166. Autonomously driven take-up platen 154 of medium unloading module 134 has a freedom of linear reciprocating movement in the direction shown by elongated oval opening 170.
In one embodiment, drum 108 and platens 138, 146, 150, and 154 are connected to a common or separate vacuum systems that allow maintain the platen surfaces at a pressure below atmospheric. The vacuum holds the medium attached to each of the surfaces of drum 108 and platens 138, 146, 150, and 154. The pressure may be different at each of the surfaces and may be regulated as required by the process. In another embodiment, grippers may be used to hold or transfer medium from one platen to another and to/from the drum.
Print head 104 is usually an array, or a number of arrays, of monochrome or color printing inkjet print heads. For example, for printing with four conventional printing colors cyan, magenta, yellow, and black, it could be an assembly of four different arrays. In another embodiment, print head 104 is an assembly of eight individual arrays where in addition to four conventional printing colors a light cyan, light magenta, light yellow, and light black colors are added.
Depending on the type of ink, used drying or curing unit 124 may be a UV or other curing radiation unit or an IR or other heat generating unit.
When sheet 182 is securely attached to platen 138, platen 138, as shown in
As the printing process terminates and it is possible to remove printed substrate 174 and replace it by substrate 182.
Concurrently interim storage module 130 departs from platen 138, which returns to its stand-by position. Autonomous drive initializes rotation of platen 146 and transmits this rotation by friction to peel-off platen 150 that picks-up the free edge of sheet 182 and peels-off sheet 182 from platen 146. In the mean time platen 146 accelerates such that the linear speed of the surface 200 of platen 150, or actually the speed of sheet 182 becomes equal to the linear speed of the surface 196 of drum 108. Platen 150 with sheet 182 engages the free from sheet 174 drum 108 surface and attaches to it sheet 182 (
The printer and continuous medium loading, printing, and unloading method described significantly improve the utilization of the printer and associated with it throughput. Uninterrupted printing is possible, as well as automatic loading of different sheet formats.
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present printer and method. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this printer and method be limited only by the claims and the equivalents thereof.
