Dampening fluid deposition by condensation in a digital lithographic system

Patent metadata

Field	Value
Publication number	US-9032874-B2
Application number	US-201213426262-A
Country	US
Kind code	B2
Filing date	Mar 21, 2012
Priority date	Mar 21, 2012
Publication date	May 19, 2015
Grant date	May 19, 2015

Abstract

A system and corresponding methods are disclosed for depositing of a layer of dampening fluid to a reimageable surface of an imaging member in a variable data lithography system by way of condensation. Dampening fluid in an airborne state is introduced proximate the reimageable surface in a condensation region. Conditions in the condensation region are such that the airborne dampening fluid preferentially condenses on the reimageable surface in a precisely controlled quantity, to thereby form a precisely controlled layer of dampening fluid of desired thickness over the reimageable surface. Among other advantages, improved print quality is obtained.

First claim

What is claimed is:

1. A subsystem for forming a dampening fluid layer over a reimageable surface of an imaging member in a variable data lithography system, comprising:
a dampening fluid reservoir configured to provide dampening fluid in an airborne state to said reimageable surface;
a flow conduit communicatively coupled to said dampening fluid reservoir and within which said airborne dampening fluid may travel from said dampening fluid reservoir toward said reimageable surface;
a flow control structure for confining airborne dampening fluid provided from said flow conduit to a condensation region to support forming a dampening fluid layer on said reimageable surface by way of condensation of said airborne dampening fluid over said reimageable surface;
an extraction subsystem for extracting excess airborne dampening fluid that does not condense over said reimageable surface from said condensation region;
a barrier structure configured to be disposed between said flow control structure and an optical patterning subsystem in a direction of travel of said imaging member to prevent evaporated dampening fluid from settling on said dampening fluid layer following evaporation and to otherwise prevent disturbing said dampening fluid layer between the point of evaporation and the optical patterning subsystem;
a controller to compare a thickness of said dampening fluid layer at a location following said condensation region to a target thickness so as to generate control signals to increase or decrease the flow of dampening fluid in an airborne state and for controlling temperature at the flow control structure and the reimageable surface; and
a valve responsive to a control signal from the generated control signals to control the flow of airborne dampening fluid in an airborne state between said dampening fluid reservoir and said condensation region.

2. The subsystem for forming a dampening fluid layer of claim 1 , wherein said airborne state of the dampening fluid is in a vapor state with a vapor pressure higher than a saturated vapor pressure at the reimageable surface.

3. The subsystem for forming a dampening fluid layer of claim 1 , further comprising:
a vapor generator communicatively coupled to said dampening fluid reservoir for creating a vapor state of the dampening fluid contained in said dampening fluid reservoir; and
nozzles disposed at the flow control structure such that a pressurized gas exits there from in the direction of said reimageable surface.

4. The subsystem for forming a dampening fluid layer of claim 3 , further comprising a gas transport device for transporting particles of said dampening fluid vapor from said dampening fluid reservoir to said reimageable surface.

5. The subsystem for forming a dampening fluid layer of claim 1 , further comprising a heating element communicatively coupled to said flow control structure for maintaining said flow control structure at a temperature exceeding a temperature of said reimageable surface in said condensation region such that condensation of dampening fluid on said flow control structure is inhibited.

6. The subsystem for forming a dampening fluid layer of claim 1 , wherein said extraction subsystem is a vacuum extraction subsystem configured to extract said excess airborne dampening fluid that does not condense over said reimageable surface from said condensation region without affecting said dampening fluid layer outside of said condensation region.

7. The subsystem for forming a dampening fluid layer of claim 6 , further comprising a dampening fluid reservoir, communicatively coupled to said extraction subsystem, for collecting and recycling dampening fluid extracted from said condensation region for reuse by said dampening fluid subsystem.

8. The subsystem for forming a dampening fluid layer of claim 1 , further comprising a thickness sensor for determining the thickness of said dampening fluid layer at a location following said condensation region.

9. The subsystem for forming a dampening fluid layer of claim 8 , wherein said controller is configured such that a thickness determined by said thickness sensor may be compared to a target thickness and in response to said comparison said controller may provide a signal to said flow control device to adjust the flow of said airborne dampening fluid to thereby control the extent of condensation of said dampening fluid.

10. The subsystem for forming a dampening fluid layer of claim 9 , wherein said controller is communicatively coupled to a control mechanism for actuating an apparatus for controlling aspects of the extent of condensation of said airborne dampening fluid.

11. A variable data lithography system, comprising:
an imaging member having an arbitrarily reimageable surface;
a dampening fluid subsystem for applying a layer of dampening fluid to said reimageable surface, comprising: a dampening fluid reservoir configured to provide dampening fluid in an airborne state to said reimageable surface;
a flow conduit communicatively coupled to said dampening fluid reservoir and within which said airborne dampening fluid may travel from said dampening fluid reservoir toward said reimageable surface;
a flow control structure for confining airborne dampening fluid provided from said flow conduit to a condensation region to support forming said layer of dampening fluid on said reimageable surface by way of condensation of said airborne dampening fluid over said reimageable surface, wherein the flow control structure has one or more slots disposed such that a pressurized gas exits therefrom in the direction of said reimageable surface;
a plurality of control devices to maintain the flow control structure at a temperature higher than the reimageable surface and to operate a heating element in the dampening fluid reservoir thereby to control the temperature of the dampening fluid in the airborne state;
an extraction subsystem for extracting excess airborne dampening fluid that does not condense over said reimageable surface from said condensation region;
a patterning subsystem for selectively removing portions of the dampening fluid layer so as to produce an image in the dampening fluid;
a barrier structure configured to be disposed between said flow control structure and the patterning subsystem in a direction of travel of said imaging member to prevent evaporated dampening fluid from settling on said dampening fluid layer following evaporation and to otherwise prevent disturbing said dampening fluid layer between the point of evaporation and the patterning subsystem;
a controller to compare a thickness of said dampening fluid layer at a location following said condensation region to a target thickness so as to generate control signals;
an inking subsystem for applying ink over the reimageable surface such that said ink selectively occupies regions where dampening fluid was removed by the patterning subsystem to thereby form an inked latent image;
an image transfer subsystem for transferring the inked latent image to a substrate; and
a cleaning subsystem for removing residual ink and dampening fluid from the reimageable surface.

12. The variable data lithography system of claim 11 , wherein said reimageable surface has a temperature and corresponding saturated vapor pressure, and further wherein said airborne state of the dampening fluid is a vapor state with a vapor pressure great than the saturated vapor pressure at the temperature of reimageable surface.

13. The variable data lithography system of claim 11 , wherein said dampening fluid reservoir is further configured to contain dampening fluid in a liquid state, and wherein said heating ele

Assignees

• Liu Chu-Heng
• Howe Patrick Jun
• Xerox Corp

Inventors

• Liu Chu-Heng
• Howe Patrick Jun

Classifications

• B41F7/37

  with supercooling for condensation of air moisture · CPC title

• B41N3/08

  Damping; Neutralising or similar differentiation treatments for lithographic printing formes; {Gumming or finishing solutions, fountain solutions, correction or deletion fluids, or on-press development (treatment of materials containing silver salts G03F7/063; developers per se for processing photosensitive materials G03F7/32)} · CPC title

• B41F7/32 Primary

  Ducts, containers, or like supply devices for liquids · CPC title

• B41F33/0054

  Devices for controlling dampening · CPC title

• B41P2227/70

  Forming the printing surface directly on the form cylinder · CPC title