Exposure device and method for compensating optical defects

• US 6,844,920 B2
• Filed: 03/08/2001
• Issued: 01/18/2005
• Est. Priority Date: 03/11/2000
• Status: Expired due to Term

• Current Assignee: Xeikon Prepress NV (ColourOz TopCo)
• Original Assignee: Basys Print GmbH Systeme Fuer Die Druckindustrie
• Inventors: Luellau, Friedrich
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): Dinh, Jack
• Application Number:
  US10/149,298
• Publication Number:
  US 20030077089A1
• Time in Patent Office: 1,412 Days
• Field of Search: 359/237, 359/238, 359/291, 359/637, 355/53, 355/67, 430/5, 430/20, 430/30, 250/548
• US Class Current: 355/67
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices
• CPC Class Codes: G03F 7/70433 Layout for increasing efficiency or for compensating imaging errors, e.g. layout of exposure fields for reducing focus errors; Use of mask features for increasing efficiency or for compensating imaging errors

Abstract

An exposure device for exposing a projection of an electronically stored artwork pattern onto a substrate, in particular a printing plate 1, with image processing electronics (2) that can store the image data, with a light modulator (7) that can be electronically controlled by the image processing electronics (2), in particular an LCD display (7) or a micro-mirror device, with an illuminating device (8, 9) for illuminating the light modulator (7), and with a projection lens (11) for projecting the light modulator (7) onto the substrate (1), is improved according to the invention in that the image processing electronics (2) include a compensation device (4, 5) to compensate for optical defects and/or tolerances in the beam path of the exposure device.

Claims

1. An exposure device for exposing a projection of an electronically stored artwork pattern onto a substrate, in particular a printing plate (1), with image processing electronics (2) that can store the image data, with a light modulator (7) that can be electronically controlled by the image processing electronics (2), in particular an LCD display (7) or a micro-mirror device, with an illuminating device (8, 9) for illuminating the light modulator (7) and with a projection lens for projecting the light modulator (7) onto the substrate (1), characterized in that the image processing electronics (2) include a compensation device (4, 5) to compensate for optical defects and/or tolerances in the beam path of the exposure device, and the compensation device (4, 5) can modulate the total quantity of incident light striking any point of the substrate (1) to be exposed during the exposure process.

2. An exposure device for exposing a projection of an electronically stored artwork pattern onto a substrate, in particular a printing plate (1), with image processing electronics (2) that can store the image data, with a light modulator (7) that can be electronically controlled by the image processing electronics (2), in particular an LCD display (7) or a micro-mirror device, with an illuminating device (8, 9) for illuminating the light modulator (7) and with a projection lens for projecting the light modulator (7) onto the substrate (1), characterized in that the image processing electronics (2) include a compensation device (4, 5) to compensate for optical defects and/or tolerances in the beam path of the exposure device, and during the exposure process, a locus-dependent intensity modulation of the stored artwork pattern can be provided with an electronically stored gray mask.

3. An exposure device for exposing a projection of an electronically stored artwork pattern onto a substrate, in particular a printing plate (1), with image processing electronics (2) that can store the image data, with a light modulator (7) that can be electronically controlled by the image processing electronics (2), in particular an LCD display (7) or a micro-mirror device, with an illuminating device (8, 9) for illuminating the light modulator (7) and with a projection lens for projecting the light modulator (7) onto the substrate (1), characterized in that the image processing electronics (2) include a compensation device (4, 5) to compensate for optical defects and/or tolerances in the beam path of the exposure device, and in order to achieve a locus-dependent light modulation, the ON times of individual pixels of the light modulator (7) during the exposure process can be varied in accordance with an stored gray mask.

4. A method for compensating for optical defects and/or tolerances in the beam path of an exposure device, in which a projection of an artwork pattern stored in a set of image processing electronics (2) is projected onto a substrate, in particular a printing plate (1), in which a light modulator that is controlled by the image processing electronics (2), in particular an LCD display (7) or a micro-mirror device, is illuminated by means of an illuminating device (8, 9), and is projected onto the substrate (1) to be exposed by means of a projecting lens (11), characterized in that the total quantity of incident light striking any point of the substrate (1) during the exposure process is modulated in such a way that the exposure differences on the substrate to be exposed, which are due to optical defects and/or tolerances in the beam path, are compensated for.

5. The method according to claim 4, characterized in that during the exposure process, a locus-dependent intensity modulation of the stored artwork pattern takes place with an electronically stored gray mask.

6. The method according to claim 4, characterized in that in order to achieve a locus-dependent light quantity modulation, the ON times of individual pixels of the light modulator during the exposure process are varied in accordance with an electronically stored gray mask.

7. The method according to claim 4, characterized in that in order to generate the electronically stored gray mask, a test exposure of a printing plate (1) is executed, in which all pixels of the light modulator (7) are triggered with an average gray value, and that the luminosity distribution produced on the printing plate (1) after the development of the printing plate (1) is input into the image processing electronics (2), which generate the electronic gray mask based on this information, preferably by inverting the gray shades of the individual pixels.

8. The method according to claim 7, characterized in that an electronic camera or a scanner is used to input the luminosity distribution of the developed test printing plate (1).