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AssigneeBarco Graphics N.V.
InventorsRonny A. De Loor, Dov Rosenfeld
Estimating the term…
A method and system for exposing a light sensitive material using device for forming a row of spots of light onto the light sensitive material located on a focal plane, device for modulating each of the spots according to imaging data so that at any point of time, the row of spots forms a data pattern according to the imaging data, device for generating relative motion between the imaging mechanism and the light sensitive material on the focal plane, the direction of motion substantially parallel to the direction of the row of spots on the light sensitive material; and data synchronizing device for shifting the imaging data into the modulating device at a rate determined by the speed of relative motion to maintain the image of any data pattern substantially stationary on the light sensitive material.
A light modulation and exposure system for exposing imaging data including:
A light modulation and exposure system for exposing imaging data including:
A method for exposing a light sensitive material according to imaging data, the method comprising:
A method for exposing a light sensitive material according to imaging data, the method comprising:
Dependencies are inferred from the claim text.
No related US applications are recorded in the indexed filing history.
Scanning systems: using multifaceted mirrors
Apparatus for additive manufacturing
Using light-emitting diode [LED] or laser arrays: special optical means therefor, e.g. lenses, mirrors, focusing means
Using the combination of scanning and modulation of light: using dot sequential main scanning by means of a light deflector, e.g. a rotating…
Term ended 1 Nov 2018 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
This invention is related to optical output scanning and in particular to controlling exposure using extended light sources to achieve high resolution output at a high exposure level.
Constructing a scanner with an extended light source such as an arc lamp or a high power laser diode or a laser diode array poses a difficult task for a designer. Because of the extended size of the source, it is impossible to collect all the light transmitted by the source into one or more small spots, for example of diameter on the order of 10 micrometers at a sufficiently high exposure level. Laser image recorders typically use lasers with a very well defined optical beam, for example, a low power laser diode, or a gas laser. Such laser diodes provide a high enough beam quality to be focused with high efficiency to a relatively small spot, and thus have been widely used in office laser printers and in the graphic arts industry.
For low sensitivity media printers such as a laser thermal printer, a higher power laser needs to be used to achieve a high throughput. CO2 and Nd-Yag lasers do provide high, clean power with nearly Gaussian beams, and can be focused onto small spots with high efficiency, but these are extremely expensive. In addition, a Nd-Yag laser has a wavelength of 1064 nm, while for thermal imaging a lower wavelength, typically 830 nm, is preferred. The high power is of particular importance when writing on thermal materials such as thermal offset plates. In this type of material, heat is used to cross-link polymer chains. The cross-linked polymer is later used as the ink attracting layer (the printing layer) in an offset press. The necessary energy may not be applied in a very short time period (less than 100 ns) since this would ablate the polymer layer. This is in contradiction with modern fast imaging systems that expose more than 50 million pixels per second, which corresponds to only 20 nanoseconds per pixel.
The present invention will be more fully understood from the detailed preferred embodiments of the invention, which, however, should not be taken to limit the invention to any specific embodiment but are for explanation and better understanding only. The embodiments in turn are explained with the aid of the following figures:
FIG. 1 shows the preferred embodiment of the system of the invention using a multi-channel modulator;
FIG. 2A shows the image of a source moving with velocity Vs and a fixed pixel on a scan line on the focal plane;
The first one or two digits in a reference numeral indicate on which figure that reference numeral is first introduced. Reference numerals between 100 and 199 are first introduced in FIG. 1, those between 200 and 299 are first introduced in FIG. 2, and so forth.
Referring to FIG. 1, in one embodiment, the exposure system consists of a light source 101, a modulator subsystem 103, a scanning means 105 and a light sensitive material held on a focal plane 107.
Light source 101 in the preferred embodiment has an approximate line shape and could be, for example, a broad area laser diode which is a line shaped source that produces high beam quality in the direction perpendicular to the junction. In this direction, the source can be imaged onto a very narrow spot (in the order of 5 to 60 microns). In the direction parallel to the junction, on the other hand, it is not possible to focus all the available power onto a small spot. A broad area laser diode with a source dimension of 1 micron by 500 microns and full-width-half-maximum (FWHM) far-field angles of 36 degrees by 10 degrees can be easily imaged by a 4 times magnification system onto a 10 micron by 2000 micron line. Such a source is used in the preferred embodiment. In an alternate implementation, light source 101 could be composed of a set of smaller light sources arranged as a linear array, such as the source described in U.S. Pat. No. 5,521,748 to Sarraf, incorporated herein by reference. In addition to a single stripe laser diode, one might use a broad area laser diode or a multi-emitter laser diode.