Claims
- 1. A lithographic plate that is transformable so as to change the affinity of said plate for ink, said plate being a layered structure including a substrate, a conductive layer and a coating, said coating containing a dispersion of particles that comprise at least one doped metal-oxide compound.
- 2. The plate of claim 1 wherein the particles comprise In.sub.2 O.sub.3 doped with SnO.sub.2.
- 3. The plate of claim 1 wherein the particles comprise SnO.sub.2 doped with Sb.sub.2 O.sub.3.
- 4. The plate of claim 1 wherein the compound is a doped zinc oxide compound.
- 5. A lithographic plate that is transformable so as to change the affinity of said plate for ink, said plate being a layered structure including a substrate, a conductive layer and a coating, said coating containing a dispersion of particles that comprise at least one compound selected from the group consisting of metal nitrides, metal arsenides, metal phosphides, metal antimonides, metal bismuthides, metal carbides, metal silicides, metal borides, or elemental silicon or an alloy thereof.
- 6. The plate of claim 5 wherein the compound includes at least one metal arsenide.
- 7. The plate of claim 5 wherein the compound includes at least one metal phosphide.
- 8. The plate of claim 7 wherein the metal phosphide is an interstitial compound.
- 9. The plate of claim 5 wherein the compound includes at least one metal antimonide.
- 10. The plate of claim 5 wherein the compound includes at least one metal bismuthide.
- 11. The plate of claim 5 wherein the compound includes at least one metal carbide.
- 12. The plate of claim 11 wherein the metal carbide is an interstitial compound.
- 13. The plate of claim 5 wherein the compound includes at least one metal silicide.
- 14. The plate of claim 13 wherein the metal silicide is an interstitial compound.
- 15. The plate of claim 5 wherein the compound includes elemental silicon or an alloy thereof.
- 16. The plate of claim 5 wherein the compound includes at least one metal boride.
- 17. The plate of claim 16 wherein the metal boride is an interstitial compound.
- 18. The plate of claim 17 wherein the boride is a hexaboride.
- 19. The plate of claim 17 wherein the boride is a dodecaboride.
- 20. The plate of claim 5 wherein the compound includes at least one metal nitride.
- 21. The plate of claim 20 wherein the metal nitride is an interstitial compound.
- 22. A lithographic plate that is transformable so as to change the affinity of said plate for ink, said plate being a layered structure including a substrate, a conductive layer and a coating, said coating containing a dispersion of particles that comprise a doped, conditionally conductive material deposited on an inert core.
- 23. A method of imaging a lithographic plate, the method comprising the steps of:
- a. providing a lithographic plate having a printing surface and including a substrate, a conductive layer and a coating, said coating containing a dispersion of particles consisting essentially of at least one crystalline conditional conductor whose conductivity is enhanced by the presence of an electric field;
- b. spacing from the printing surface at least one discharge source, each of which includes a writing head comprising an electrode, each writing head being oriented opposite the printing surface; and
- c. removing said coating and conductive layer to reveal said substrate, and to thereby change the affinity of said printing surface for said liquid, by exposing the printing surface to a strong electric field at selected points, said exposures producing discharges substantially perpendicular to the printing surface at said points.
- 24. The method of claim 23 wherein the electric field interacts with the particles to cause substantially straight-line travel of said discharge from said writing head to said printing surface.
- 25. The method of claim 23 and including the additional step of altering, in order to vary the sizes of image spots produced by said discharges, a characteristic of the discharge selected from the group consisting of voltage, current, time duration and number of said discharges at any particular point.
- 26. The method of claim 23 further comprising the step of mounting the plate, prior to the spacing and exposing steps, to a plate cylinder of a lithographic press having at least one plate cylinder.
RELATED APPLICATION
This is a continuation-in-part of Ser. No. 07/442,317, filed Nov. 28, 1989, now U.S. Pat. No. 5,109,771, which is itself a continuation-in-part of Ser. No. 07/234,475, filed Aug. 19, 1988, now U.S. Pat. No. 4,911,075.
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Continuation in Parts (2)
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Number |
Date |
Country |
Parent |
442317 |
Nov 1989 |
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Parent |
234475 |
Aug 1988 |
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