Imaging system with electrophotographic patterning of an image definition material and methods therefor
View Patent ↗A system comprises an electrophotographic subsystem, a transfer subsystem, an imaging member, and an inking subsystem. The electrophotographic subsystem comprises a photoreceptor, a charging subsystem, an exposure subsystem, and a development subsystem. In operation, the photoreceptor is charged areawise. An exposure pattern is formed by the exposure subsystem on the surface of the charged photoreceptor to thereby write a latent charge image onto the photoreceptor surface. The image is developed with an image definition material, such as a dampening fluid. The image definition material forms a positive pattern of the image to be printed. The image pattern is then transferred to the reimageable surface. The transferred pattern is then developed by selectively applying an ink over regions of image definition material. The inked image may be transferred to a substrate.
1. A variable data lithography system, comprising:
a photoreceptor;
a charging subsystem for applying a first electrostatic charge to the photoreceptor;
an exposure subsystem disposed for selective exposure of the photoreceptor to form an exposure pattern from regions that are exposed and unexposed by the exposure subsystem on a surface of the photoreceptor, the exposure enabling altering of the electrostatic charge on the photoreceptor to define first regions of the photoreceptor having a first electrostatic charge state and second regions of the photoreceptor having a second electrostatic charge state;
an image definition material subsystem disposed proximate to the photoreceptor for selectively applying an image definition material substantially over the first regions of the photoreceptor having the first electrostatic charge state and not over the second regions having the second electrostatic charge state to form an image definition material image on a surface of the photoreceptor corresponding to the exposure pattern;
an inking subsystem disposed proximate to the photoreceptor for selectively applying ink over the photoreceptor such that the ink preferentially occupies regions over the image definition material to thereby form an inked image;
an imaging member having a reimageable surface formed thereon, disposed proximate the photoreceptor such that the inked image is transferred to the reimageable surface; and
an image transfer subsystem for transferring the inked image from the reimageable surface to a substrate,
wherein:
the first regions of the photoreceptor having the first electrostatic charge state have a first charge polarity, and the image definition material subsystem is configured such that the image definition material applied over comprises electrostatically charged particles having a second charge polarity, the first charge polarity being opposite the second charge polarity, and
the image definition material comprises a dampening fluid, the dampening fluid comprising a carrier fluid in which the particles are disposed, and the carrier fluid is electrically insulative.
2. The variable data lithography system of claim 1 , further comprising a viscosity control subsystem disposed proximate to the reimageable surface and between a point at which the inked image is transferred to the reimageable surface and the image transfer subsystem in a direction of motion of the imaging member, for controlling the viscosity of ink forming the inked image prior to transfer of the inked image to the substrate.
3. The variable data lithography system of claim 2 , wherein the viscosity control subsystem comprises a heating element configured to direct heat energy toward the reimageable surface.
4. The variable data lithography system of claim 1 , wherein the image definition material subsystem further comprises a charge application subsystem for applying an electrostatic charge having the second charge polarity to the particles.
5. The variable data lithography system of claim 1 , wherein the particles are organic polymers.
6. The variable data lithography system of claim 1 , wherein the particles are selected from a group consisting of: inorganic magnetic nanoparticles and inorganic dielectric nanoparticles.
7. The variable data lithography system of claim 1 , further comprising a charge application device disposed proximate the imaging member and configured to apply an electrostatic charge of the first polarity to the imaging member such that the particles are electrostatically attracted to the reimageable surface during transfer from the photoreceptor to the reimageable surface.
8. The variable data lithography system of claim 1 , further comprising a charge application device disposed proximate the image transfer subsystem and configured to apply an electrostatic charge of a polarity opposite that of the first electrostatic charge to an element of the image transfer subsystem such that the particles, but not the ink, are electrostatically rejected in a region at which the ink transfers from the reimageable surface to the substrate.
9. The variable data lithography system of claim 1 , further comprising a segregation material subsystem disposed proximate the reimageable surface and between the photoreceptor and the inking subsystem in a direction of motion of the imaging member, the segregation material subsystem being configured to selectively deposit segregation material substantially in regions of no image definition material over the reimageable surface.
10. The variable data lithography system of claim 1 , further comprising a segregation material subsystem disposed proximate the photoreceptor and between the image definition material subsystem and a point at which the image definition material is transferred to the reimageable surface in a direction of motion of the imaging member, the segregation material subsystem being configured to selectively deposit segregation material substantially in regions of no image definition material over the photoreceptor, and the reimageable surface is configured to receive both the image definition material and the segregation material in a pattern substantially corresponding to the image definition material image with the segregation material substantially occupying the regions of no image definition material over the reimageable surface.