Patent Application
20130063744
Reference is made to commonly-assigned copending U.S. patent application Ser. No. ______ (Attorney Docket No. K000556US01NAB), filed herewith, entitled IMAGING HEAD FOR A FLAT BED SCANNER, by Kort; the disclosure of which is incorporated herein.
The present invention relates to methods and apparatus for printing plates imaging head and more specifically to a flat bed imaging head.
Digital imaging systems have gained wide acceptance in the preparation of printing precursor elements for use in printing operations. For example, flexographic printing presses are widely used in the printing of packaging products where the use of a compressible relief imaging element is advantageous for printing on a variety of substrates including, for example, plastic and cardboard. A flexographic media generally comprises a layer of photopolymer that is exposed to UV radiation through an image mask, such as a film, to selectively harden the photopolymer.
Optical heads for imaging emit a plurality of light spots on a light-sensitive medium. The optical imaging head may be configured from an array of pigtailed laser diodes. Each laser diode is optically coupled to a proximal tip of a multi-mode optical fiber. The media is often on a rotational drum and imaged by the array of lasers. Another system for imaging printing plates is a flat bed based imaging device. The media is positioned on a horizontal bed and the optical path is designed to scan the optical beam across the media mounted on the flat bed.
The present invention addresses different features used in computer to plate (CTP) devices, and more specifically in the field of direct imaging on a media positioned on a flat bed.
Briefly, according to one aspect of the present invention an imaging head for a flatbed imaging system includes a first rotating multi-facet spinner; a first set of long mirrors directed towards imaging media positioned on a flatbed surface wherein the first set mirrors is at a first distance from said media; a second set of long mirrors directed towards the imaging media wherein the second set of mirrors is at a second distance from said media; a first laser source configured to emit light on the spinner at a first height on the spinner wherein light emitted from the first height on the spinner is directed to the first set of mirrors; and a second laser source configured to emit light on the spinner at a second height on the spinner wherein light emitted from the second height on the spinner is directed to the second set of mirrors.
The imaging device scans plurality of imaging data on a plurality of media regions during the same imaging cycle.
The invention and its objects and advantages will become more apparent in the detailed description of the preferred embodiment presented below.
The present invention will be directed in particular to elements forming part of, or in cooperation more directly with the apparatus in accordance with the present invention. It will be understood that elements not specifically shown or described may take various forms well known to those skilled in the art.
The multi-spinner is a polygon shape wherein each facet represents a full fast scan line impinging on a long mirror. The laser beams 324 and 328 are directed at different heights on the multi-spinner 304 and are deflected from multi-spinner 304 to the long mirrors 316 and 320 by beams 332 and 336 respectively. The long mirrors 316 and 320 are positioned at an angle to direct the laser beams onto a printing plate 436 or out multiple printing plates (not shown). A plan view of an embodiment using four mirrors is shown in
As discussed above, the light beam is emitted from multiple laser sources 308 and 312 through lenses 416 and 420 respectively on the multi-facet structure 428 of multi-spinner 404. Laser source 308 emits beam 460 on multi-spinner 404, further distributed from spinner as beam 464 which is directed on mirrors 444 and 452. Laser source 312 emits beam 470 on multi-spinner 404, further distributed from spinner as beam 474 which is directed on mirrors 440 and 448. The light from the different laser sources is emitted at different heights on multi-spinner 404 or at different independent spinners. The light is further distributed through lens 424 on to multiple long mirrors 440, 444, 448 and 452. The emitted light beams are directed towards printing plate 436. The printing plate 436 is affixed to a vacuum table 432. The vacuum table 432 is adapted to advance between in the slow scan direction at carriage direction 456.
The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the scope of the invention.
