Thermodynamic printing method and means

Printing apparatus responsive to an incoming digital data stream for printing on a printing medium variable thickness ink dot patterns representing an original image, said apparatus comprising:

• A. printing means having a printing surface;
• B. means defining in said printing means a multiplicity of discrete, independently electrically chargable capacitor microcells adjacent to said surface;
• C. means for activating selected ones of said microcells in accordance with the incoming data stream, the activated microcells being geometrically related to the dots in the pattern to be printed;
• D. means for depositing electrical charges on the microcells selected for activation at controlled, variable coulombic charge levels to create at said printing means surface localized electrical fields of various strengths that are proportional to the print densities desired for said related dots in the pattern to be printed;
• E. a voltage sensitive ink for application as a liquid to said printing means surface;
• F. means for contacting said surface with said liquid ink whereby, under the influence of said fields, said ink is deposited on said printing means surface only at the locations of said microcells selected for activation, with the thickness of each said ink deposit being proportional to the strength of the field at that microcell thereby to form a variable-thickness ink pattern on said printing means surface;
• and
• G. means for transferring said ink pattern to said printing medium whereby the ink dot pattern printed on the printing medium is a faithful reproduction of said original image.

A method of printing on a printing medium an ink dot print pattern in color representative of an original color image, said method including the steps of:

• A. forming a dielectric printing member having a printing surface that is somewhat ink repellant;
• B. applying to said printing surface a first pattern of tiny discrete localized electropositive charge deposits representive of a first color component of said original image;
• C. controlling the magnitude of each deposit in the pattern so that said magnitude is representative of the print density desired for the related dot in the print pattern to be printed;
• D. contacting said printing surface with a first color electroscopic ink in liquid form whereby the ink is deposited on the printing surface as ink dots only at the locations of said charge deposits in said first charge deposit pattern, with the thickness of the first color ink dot at any location on the printing surface being proportional to the magnitude of the underlying first pattern charge deposit, thereby to form a variable thickness first color ink dot pattern on the printing surface;
• and
• E. transferring said first color ink dot pattern to said printing medium to form said print pattern thereon.