Thermodynamic printing method and means
First Claim
1. A method of printing on a printing medium a variable thickness ink dot pattern representing an original image in response to an incoming digital data stream comprising the steps of:
- A. forming printing means having a printing surface;
B. defining in the printing means a multiplicity of discrete, independently electrically chargable capacitor microcells adjacent to said printing surface;
C. activating selected ones of the microcells in accordance with the incoming data stream so that the activated microcells are geometrically related to the dots in the pattern to be printed;
D. depositing electrical charges on the microcells selected for activation at controlled, variable coulombic charge levels to create at said printing surface localized electrical fields of various strengths that are proportional to the print densities desired for said related data in the pattern to be printed;
E. contacting said printing surface with a voltage sensitive ink in liquid form whereby the ink, under the influence of said fields, is deposited on said printing 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 the said printing surface; and
F. transferring said ink pattern to said printing medium to provide a faithful hardcopy reproduction of said original image.
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Abstract
In a method of printing on a printing medium a variable thickness ink dot pattern representing an original image in response to an incoming digital data stream, a printing member, e.g. a cylinder, is formed which defines a multiplicity of discrete, independently electrically chargable capacitor microcells adjacent to a printing surface of that member. Selected ones of the microcells are activated in accordance with the incoming data stream so that the activated microcells are geometrically related to the dots in the pattern to be printed. Then, electrical charges are deposited on the microcells selected for activation at controlled variable coulombic charge levels to create at the printing surface, localized electrical fields of various strengths that are proportional to the print densities desired for the related dots in the pattern to be printed. Following this, the printing surface is contacted by a two-component, voltage sensitive, thermoplastic ink whereby ink colorant, under the influence of the fields, is deposited on the printing surface only at the locations of the microcells selected for activation, with the thickness of each ink deposit being proportional to the strength of the field at that microcell, thereby to form a variable-thickness ink pattern on the printing surface. That ink pattern is then transferred completely to the printing medium to provide a faithful hardcopy reproduction of the original image. Apparatus for practicing the method are also disclosed.
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Citations
54 Claims
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1. A method of printing on a printing medium a variable thickness ink dot pattern representing an original image in response to an incoming digital data stream comprising the steps of:
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A. forming printing means having a printing surface; B. defining in the printing means a multiplicity of discrete, independently electrically chargable capacitor microcells adjacent to said printing surface; C. activating selected ones of the microcells in accordance with the incoming data stream so that the activated microcells are geometrically related to the dots in the pattern to be printed; D. depositing electrical charges on the microcells selected for activation at controlled, variable coulombic charge levels to create at said printing surface localized electrical fields of various strengths that are proportional to the print densities desired for said related data in the pattern to be printed; E. contacting said printing surface with a voltage sensitive ink in liquid form whereby the ink, under the influence of said fields, is deposited on said printing 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 the said printing surface; and F. transferring said ink pattern to said printing medium to provide a faithful hardcopy reproduction of said original image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. 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:
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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. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. In printing apparatus of the type including a printing member having a substantially smooth, unbroken printing surface for printing on a printing medium an ink pattern representative of an original image, a recording station for applying an electronic charge pattern to said printing member, an inking station for applying a voltage sensitive ink to said surface and a transfer station for transferring ink from said surface to a printing medium to form a printed image thereon, the improvement wherein said printing member comprises:
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A. a rigid, thin-walled, dielectric structure having opposite surfaces one of which constitutes said printing surface; B. means defining in said printing member an array of closely packed, but discrete, capacitor microcells which array extends over the area of said printing surface, each microcell being separately chargeable at said recording station so as to acquire a discrete localized electrical field thereat whose field lines are perpendicular to, and extend above, said printing surface. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 38, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 51, 52, 53, 54)
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37. movable means for contacting said printing surface selectively with any one of said inks;
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C. wherein said control means also operates said contacting means and said rotating means so that after first color ink is transferred to said printing medium, the cylinder is rotated in reverse to return the printing surface and printing medium to their original positions and said contacting means is moved so that said printing surface is contacted by a second one of said plurality of different color inks whereupon the control means rotates the cylinder in the forward direction again to record a second electronic pattern on the printing surface, printing a second color component of the pattern to be printed, and to apply second color ink to said printing surface and to transfer said second color ink to said printing medium congruently to said first color ink transferred thereto. - View Dependent Claims (39)
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50. 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:
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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.
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Specification