Patent Application
20070101883
The present disclosure relates to a method of printing images, the method having aspects in common with gravure-type printing, and also having aspects in common with digital printing systems.
There are currently two popular basic technologies for the mass production of printed images: offset printing and xerography. Offset printing is currently favored for large volumes of identical prints, such as the pages of magazines and books. One downside of offset printing is that a plate must be prepared for every image desired to be printed, and such plates typically cannot be modified for subsequent use after the particular print job is concluded. In recent years xerography has become cost-effective for somewhat smaller print jobs than are typical with offset printing; and, with laser-based imaging, xerography enables images generated at a computer to be readily printed in large volumes without the hands-on work required in offset.
There have been efforts to make basic offset printing technology adapt to certain imaging techniques that are common in xerography, with some attendant practical advantages. One line of research concerns the making of “flexographic” printing plates, such as described in U.S. Pat. No. 5,279,697, and U.S. Published Patent Application 2005/0150407-A1. Another type of printing technology, within the general realm of offset, includes the use of what are called “Anilox” rolls to retain liquid ink and transfer the ink to a print sheet or blanket roll, such as described in materials published by Harper® Corporation.
Japanese Kokai 11-258785 proposes another method for using digital imaging techniques in a largely offset-based environment.
Nature, Vol. 434, pp. 879-882 (14 Apr. 2005) describes what is called a “light-induced shape-memory polymer”.
U.S. Published Patent Applications 2004/0081911; 2004/0103801; 2004/0241583; and 2005/0221230 disclose various recent approaches to providing digital imaging, such as through a modulating laser, in a largely offset-based environment.
According to one aspect, there is provided an apparatus for printing an image, comprising a printing plate. The printing plate defines in a main surface thereof an arrangement of imageable areas, each imageable area being capable of selectably increasing or decreasing an amount of marking material retainable thereat, in response to energy applied thereto.
According to another aspect, there is provided an apparatus for printing an image, comprising a first printing plate and a second printing plate. Each printing plate defines in a main surface thereof an arrangement of imageable areas, each imageable area being capable of selectably increasing or decreasing an amount of marking material retainable thereat, in response to energy applied thereto.
According to another aspect, there is provided a printing plate useful in printing an image, the printing plate defining in a main surface thereof an arrangement of imageable areas, each imageable area being capable of selectably increasing or decreasing an amount of marking material retainable thereat, in response to energy applied thereto.
In overview, the plate 10, defining a large number of pixel-size cavities 20 in the main surface thereof, is able to retain marking material (typically, but not necessarily, liquid ink) in an imagewise fashion thereon. The cavities such as 20b in
Returning to
Downstream of laser 32 along the illustrated process direction of plate 10, the main surface of plate 10 is inked by an inking station generally indicated as 40. Inking station 40, which can be of any of variety of configurations as is generally known in, for example, offset printing, applies ink to the main surface of plate 10, so that ink is retained in the cavities of configuration 20b in
At transfer station 50, in the illustrated embodiment, a print sheet S is brought into contact with the inked main surface of plate 10, to receive the ink in imagewise fashion therefrom. A pressure roller 52 is shown, but other mechanisms having the desired transfer effect are known generally in the printing art. Alternatively, instead of transferring the ink directly to a print sheet, there may be provided a “blanket roll” (not shown), as is generally familiar in offset printing, which would receive the ink and in turn transfer it to a print sheet.
Following transfer, excess ink is removed from the main surface of plate 10 so that the plate 10 can pick up a new image in a following cycle. In the present embodiment, with the energy-sensitive material that will be described below, application of light of a predetermined wavelength, such as from lamp 56, will cause the material 22 to return to its full size, thus pushing ink out of each cavity 20. Ink remaining generally on the surface of plate 10 can then be removed by brush 58, or equivalent. The fact the material 22 can selectably expand and contract, or selectably change its position, enables a particular cavity 20 to selectably retain more or less marking material therein following the application of energy of a particular type, whether from laser 32 or lamp 56. In this way, the surface of plate 10 can be made erasable via lamp 56 and re-imageable via laser 32. This erasing and re-imaging can occur with every rotation of the cylindrical or otherwise rotatable plate 10.
In alternate embodiments, a control system can operate the illustrated apparatus to enable multiple inking and printing cycles of the rotatable plate 10, to make multiple identical images, before the image manifest in the cavities 20 is erased by lamp 56. The properties of the material 22 can be selected depending on whether it will be desired to provide multiple inking and printing cycles, and whether such multiple cycles will be very long term, such as hundreds or thousands of prints made before re-imaging.
Material 22 comprises, in one embodiment, a “light-induced shape-memory polymer.” Examples of such materials are described in a letter appearing in Nature, Vol. 434, pp. 879-882 (14 Apr. 2005). Materials such as those described in the article have the property of changing shape, or in some arrangements position, when exposed to light of different frequencies, typically ultraviolet.
The bulk of plate 10, in which the cavities 20 are defined, can comprise ceramic, aluminum, copper, carbon, or any other suitable material. A relevant consideration of the material for plate 10 is that it is suitable for permanent attachment of material 22, such as with an adhesive.
Although the present embodiment includes a material that changes its shape or volume depending on the application of radiant energy of a predetermined wavelength, other approaches to obtaining the desired effect of each imageable area being capable of changing an amount of marking material disposable thereat, in response to energy applied thereto, can be envisioned. It is conceivable to provide a material that becomes more or less absorbent of an applied liquid depending on the application of different types of energy, radiant or otherwise, applied thereto. The pixel-sized cavities shown in the illustrated embodiment may not be required. Micromechanical structures providing the effect could be provided.
The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
