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US3299809A - Electrostatic printing process for use with printing plate having plural levels - Google Patents

Electrostatic printing process for use with printing plate having plural levels Download PDF

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Publication number
US3299809A
US3299809A US409209A US40920964A US3299809A US 3299809 A US3299809 A US 3299809A US 409209 A US409209 A US 409209A US 40920964 A US40920964 A US 40920964A US 3299809 A US3299809 A US 3299809A
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US
United States
Prior art keywords
areas
plate
metal
printing
dielectric
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US409209A
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English (en)
Inventor
Laszlo J Javorik
Edward D Higgins
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Continental Can Co Inc
Original Assignee
Continental Can Co Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Continental Can Co Inc filed Critical Continental Can Co Inc
Priority to US409209A priority Critical patent/US3299809A/en
Priority to DEC37076A priority patent/DE1254160B/de
Application granted granted Critical
Publication of US3299809A publication Critical patent/US3299809A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/14—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base
    • G03G15/16—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer
    • G03G15/163—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer using the force produced by an electrostatic transfer field formed between the second base and the electrographic recording member, e.g. transfer through an air gap
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G13/00—Electrographic processes using a charge pattern
    • G03G13/26—Electrographic processes using a charge pattern for the production of printing plates for non-xerographic printing processes

Definitions

  • This invention relates to a printing procedure and a printing plate for employment therewith, whereby multiple copies may be printed by an electrostatic operation.
  • defects in the dielectric such as pinholes, scratches, local variations in dielectric by thickness or dielectric constant, and surface contaminations upon the surface thereof, can cause defects in the printing.
  • defects in the dielectric such as pinholes, scratches, local variations in dielectric by thickness or dielectric constant, and surface contaminations upon the surface thereof, can cause defects in the printing.
  • some of the developer particles remain adherent to the surface of the dielectric and modify its reaction to a later corona charging: and mechanical cleaning of the plate, between printings, does not maintain a satisfactory quality of printing. Each mechanical cleaning increases the probability of scratching the surface.
  • FIGURE 1 is a perspective view of a portion of a composite printing plate
  • FIGURE 2 is a section through a metal base being prepared to form a printing plate according to this invention, with raised metal image areas thereon;
  • FIGURE 3 shows the metal base of FIGURE 2, with a coating of dielectric thereon;
  • FIGURE 4 shows the base as in FIGURE 3, with the dielectric coating removed from the metal printing areas;
  • FIGURE 5 is a view like FIGURE 2, of a metal base for practicing another form of the invention.
  • FIGURE 6 is a view of the base of FIGURE 5, with a thick all-over coating of a dielectric
  • FIGURE 7 shows the same, with the surface reduced to the level of the metal surface of the original base
  • FIGURE 8 shows the same, with metal deposited upon the exposed metal areas of FIGURE 7;
  • FIGURE 9 shows the same, with the deposited metal reduced to a smooth surface above the level of the dielectric
  • FIGURE 10 is a diagrammatic showing of the charging of a composite printing plate
  • FIGURE 11 is an enlarged section through a portion of a charged printing plate
  • FIGURE 12 is a diagrammatic showing of the development of a printing plate
  • FIGURE 13 is an enlarged section through a portion of a developed printing plate
  • FIGURE 14 is a diagrammatic showing of an operation of printing from a developed plate
  • FIGURE 15 is a diagrammatic showing of another printing operation
  • FIGURE 16 is a section through another form of printing plate, after printing therefrom.
  • FIGURE 17 is a diagrammatic showing of simultaneous charging and developing of a composite printing plate.
  • the printing plate may be the surface of a roller, or a flat sheet, the latter being illustrated.
  • a base 10 formed of metal or other conductive material, has depressions 11 formed therein, e.g., .by etching, routing or other operation, so that elevated metal surface areas 12 exist in the pattern of the image to be printed, while the depressions 11 are to define the background or nonprinted areas of the final substrate to be printed.
  • An allover insulating coating preferably of uniform thickness, is then applied to the base 10 as a coating 13 which in the depressions 11 is of a lesser thickness than the depth of the depressions.
  • Such a coating 13 may be applied by spraying or brushing an organic enamel composition.
  • a satisfactory composition is one in which the solids are electrically insulating when dried, and which gives a tough adherent coating. Polyesters and acrylic resins have been found suitable, in a volatile organic solvent. When the coating has dried, the portions which overlie the metal image areas, as shown :by dotted lines 14 in FIGURE 4, are removed so the metal is exposed.
  • the resulting printing plate has the metal base 10 with exposed metal image areas 15' where the dielectric portions 14 have been removed, and dielectric coatings in the depressions 11, with the top surfaces 16 of the dielectric coatings at a lower level than the metal areas 15.
  • the depressions 11 have a depth D, and the difference between the surface of image areas 15 and the top surface 16 of the non-image areas define a recess 17 having a depth R.
  • the dielectric coating below the surface 16 must be thinner than the depth of the depressions 11 so as to form the recess 17.
  • a dielectric coating as thin or less than one thousandths of an inch can be satisfactory.
  • Depressions 11 should be as deep as possible.
  • a depth of 0.005 produces an appreciable improvement which might be suitable for half tone but further improvements are obtained by increasing the depth to a dimension of of an inch or greater.
  • the metal base 10 of FIGURE 5 is like that of FIGURE 2, with depressions 11 at background areas, and with the raised metal surfaces 12 providing the pattern or image areas which are to be printed.
  • a thick coating 23 of dielectric material is then applied, preferably to a thickness which is greater than the depth of the cavities; FIG. 6. This may be by a single application of a lacquer as with FIGURE 3, or by successive builtup coatings, or by a fused resin polyester or any suitable dielectric.
  • the surface of the total plate is then dressed down, as by grinding, to a single level; FIGURE 7.
  • the metal areas are thus bared, while the areas between and around them, i.e., the background areas, are occupied by the dielectric bodies 24.
  • the metal areas 12 are then built up in height, e.g., by electroplating with the 3 dielectric bodies 24; providing resists so that no metal is deposited over the background regions, to a greater height 25 which extends well above the surfaces of the background regions. Finally the metal elevations are dressed down to parallelism with the background surfaces, FIGURE 9, to provide the printing image surfaces 26.
  • the electroplated deposits may extend 20 to 50 mils or more above the background surfaces, and be dressed down to a differential elevation of 15 to 45 mils or to any suitable level between the raised metal and the surfaces of the dielectric.
  • the metal base 10 In the practice of FIGURES 2-4, the metal base 10 must be etched to a depth sufliciently greater than the extending difference of level so that the surface of the dielectric areas 16, FIGURE 4, will be at the desired level below the metal printing areas 15. In the practice of FIGURES 5-9, the etching depth can be less, because the difference in level is provided by increasing the metal thickness above the background levels 24.
  • the composite printing plate 30 of FIGURE 1 has the conductive or metal base with a layer of dielectric or insulating material 31 thereon at the background or nonprinting portions thereof, such being the residues 16 or 24 of FIGURES 29.
  • the image or printing areas 32 are formed of bare conductor as set out for the areas or 26 of FIGURES 2-9.
  • the composite plate 30 is being moved over a conductive support 35 in the direction of the arrow, and beneath a source of corona discharge shown as wires 36 extending across the direction of plate movement.
  • the wires 36 may be moved relative to the plate 30, noting that the purpose is to apply charges to the dielectric areas 31.
  • the high voltage source 37 acts to establish a potential difference by which the metal base 10 becomes positive relative to the corona wires 36, and these wires emit electrons and negative ions which move toward the composite plate along paths at right angles to the composite plate.
  • the electrons and negative ions which encountered the exposed metal areas 32 are dissipated and discharged thereat or, in other words, complete the movement of the electric current in circuit back to the source 37.
  • the electrons and negative ions which encounter the insulation areas 31 remain in place thereon, being prevented from continuing in the circuit by the insulating material.
  • the composite plate is thus charged, so that the surfaces of the insulating areas 31 have a resident negative electric charge, i.e., at the background areas from which no printing is to be done, while the body of the metal including the exposed metal areas from which printing is to be done is maintained at a positive potential relative to the charging potential as indicated in FIGURE 11.
  • the composite plate is then developed by employment of toner particles having a negative charge. This may be done as in FIGURE 12, where the composite plate 30 is positioned at a slope and the toner 38 is delivered from a hopper 39 and allowed to cascade over the plate surface, with the residue being collected in a trough 40.
  • the negatively charged particles are attracted to and held by the metal areas 32, which are maintained at a positive potential that is induced by the negative charge on the surfaces 31, and are repelled from the negatively charged surfaces 31 of insulating material.
  • factors acting singly or in conjunction contribute to the force that holds the toner particles to the metal areas depending on the position of the plate in the cycle and the method employed to charge the particles. Among these are image effect, induced electrostatic edge efiect, field and corona discharge or other electrostatic field.
  • the development may be by introducing a cloud of toner particles beneath the corona wires 36, so the particles become negatively charged and are attracted to and deposit upon the metal areas 32, which are maintained at a positive potential with respect to the corona wires 36, but are repelled from the negatively charged insulation areas 31, noting that such corona-charged toner particles are preferably employed after a primary negative corona charging of the areas 31 has been accomplished.
  • the developed composite plate 30 is then brought opposite a substrate 42 to be printed, as in FIGURE 14.
  • the substrate 42 may be of conductive material such as metal. If the substrate 42 is of dielectric material, e.g a nonconductor or p001 conductor such as paper or a plastic film, it is placed against a back electrode 43.
  • a source 44 is connected to establish an electrostatic field between the base 10 of the composite plate and the surface of the substrate 42, with the substrate positive relative to the base 10. This electrostatic field creates a force on the toner particles 38 which in the case of some of the particles, particularly the particles in the outer layers, exceeds the force attracting the particles to the metal area 32 and, hence, these particles are transferred to the substrate along paths essentially at right angles to the substrate.
  • the toner can then be fixed to the substrate by appropriate means.
  • this fixation may be by simple heating.
  • the transfer from composite plate to substrate can be accomplished with the substrate above the plate 10, as shown in FIGURE 15.
  • E /d Transfer potential gradient between the center of the particle and the transfer electrode or conductive substrate (volts/cm.).
  • E /d Potential gradient between the center of the particle and the printing plate, which voltage and gradient are produced by the induced electrostatic field of the charged-up dielectric.
  • d Double of the distance between the center of the particle and the substrate.
  • the practices according to FIGURES 2 to 9 can be employed with rougher-textured substrates, where parts of the substrate surface may be at greater distances from the raised metal areas than other parts are from depressed metal areas.
  • the thin dielectric layers, with repellent electric charges thereon, greatly reduce the amount of toner adherent to the background or non-image areas defined thereby, and clean and sharply defined prints are produced. After each use, there is a residue of toner particles upon such areas, having been held by forces other than merely electrostatic attraction.
  • the composite plates are easy to clean, by a long-haired brush, by airblast, or the like, without requiring a vigorous wiping or scraping action which could cause scratchnig.
  • FIGURES 2-4 the widths of metal areas 12 is determined during the etching; with FIGURES 5-9, the area increases due to the widening of the metal area during electroplating, as shown in the drawings.
  • the practice of FIGURES 2-4 is preferred.
  • the practice of FIGURES 5-9 is preferred, allowance being made for the widening, e.g., by etching the adjacent recesses so that the metal area 12 of FIGURE 5 is narrower than the printing to be done therefrom.
  • FIGURE 17 shows a corona discharge device 50 which is energized by the negative terminal 51 of a power supply 52 which has a positive terminal 53 connected to the base metal of the printing plate 10. This results in the deposition of negative charges on the surface of the dielectric coating 13, which negative charges induce positive charges on the metal surface areas 12 immediately adjacent to the dielectric coating 13.
  • the electrostatic field created between the corona discharge device 50 and the printing plate 10, which electric field is indicated by the dotted lines 55, propels toner particles 56 to the metal surfaces of the printing plate 10 even in the absence of the electrostatic charge induced in the metal portions by the negative charge on the dielectric coating 13.
  • the corona discharge device 50 thus has two functions; one function is to charge the toner particles 56, and the other function is that of a development electrode for charging the printing plate 10.
  • toners having negative charges have been set out for the employment of toners having negative charges.
  • positively charged toners with or without negatively charged carrier particles, can be employed by employing a positive charging of the dielectric areas 31, e.g., by reversing the connections from the source 37 to the corona wires 36 and to the base 35.
  • the printing plates 10 nee-d not be planar, but can be cylindrical; wherewith the difference in levels between raised and recessed portions is the radial distance between the cylindrical surface including the raised portions and the surface including the recessed portions.
  • the method of electrostatic printing which comprises preparing a printing plate of conductive material having raised image areas and recessed background or nonprinting areas, holding the plate at one polarity and applying to both the raised image areas and recessed background areas a toner comprising particles charged to the opposite polarity, bringing a substrate to be printed to a position opposite to the raised and recessed areas of the plate, and applying a potential difference between the substrate and the plate which establishes forces upon the toner particles on raised areas of the plate adequate to cause the particles to leave the same, said potential difference being selected to be too low to establish forces upon the toner particles on recessed areas of the plate adequate to cause the latter toner particles to leave the recessed areas.
  • the method of electrostatic printing which comprises preparing a printing plate of conductive material having raised image areas and recessed background or nonprinting areas, said recessed areas having a dielectric layer thereon, the exposed surfaces of said layers being below the levels of the adjacent raised portions of the plate, holding the plate at one polarity and applying to both the raised image areas and recessed dielectric layer, a toner comprising particles charged to the opposite polarity, bringing a substrate to be printed to a position opposite to the raised and recessed areas of the plate, and applying a potential difference between the substrate and the plate which establishes forces upon the toner particles on raised areas of the plate adequate to cause the particles to leave the same, said potential difference being selected to be too low to establish forces upon the toner particles on recessed areas of the plate adequate to cause the latter toner particles to leave the recessed areas.
  • the method of developing a printing plate comprising the steps of providing a printing plate having raised image areas formed of electrically conductive material and recessed non-image areas covered with dielectric material, exposing the printing plate to a corona discharge having a predetermined polarity, and simultaneously introducing toner particles into the zone of the same corona discharge, said corona discharge charging said toner particles and said dielectric material to the same polarity whereby toner particles are repelled by said dielectric material.
  • the method of electrostatic printing which comprises the steps of, preparing a printing plate of conductive material having raised image areas and recessed nonimage areas, said non-image areas having a dielectric layer thereon, exposing the printing plate two a corona discharge having a predetermined polarity, developing said printing plate by introducing toner particles intothe zone of the same corona discharge for charging said toner particles and said dielectric material to said predetermined polarity whereby toner particles are applied to said image areas and repelled by said dielectric layer on said nonimage area; bringing a substrate to be printed to a position opposite to the image areas and non-image areas of the plate; and creating a potential difference between the substrate and the printing plate for applying forces upon the toner particles to cause the toner par-ticles to be transferred from the image areas of said printing plate to the substrate.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Printing Methods (AREA)
US409209A 1964-11-05 1964-11-05 Electrostatic printing process for use with printing plate having plural levels Expired - Lifetime US3299809A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US409209A US3299809A (en) 1964-11-05 1964-11-05 Electrostatic printing process for use with printing plate having plural levels
DEC37076A DE1254160B (de) 1964-11-05 1965-10-07 Elektrostatisches Druckverfahren sowie Verfahren zum Herstellen der Druckplatte zu dessen Durchfuehrung

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3370529A (en) * 1966-08-05 1968-02-27 Fairchild Camera Instr Co Electrostatic printer having selfregulating corona discharge
US3386551A (en) * 1966-11-14 1968-06-04 Litton Business Systems Inc Method of and apparatus for using radio or high frequency energy to produce printed matter
US3443517A (en) * 1967-01-04 1969-05-13 Xerox Corp Electrostatic duplicating system employing relief printing plate
US3477368A (en) * 1967-10-24 1969-11-11 Itt Printing apparatus employing magnetic transfer band in which image impressions can be made
US3515059A (en) * 1968-03-05 1970-06-02 Patent Dev Corp Hot stamping die having insulated surfaces adjacent the die faces
US3786745A (en) * 1970-09-05 1974-01-22 Philips Corp Durable registration template for electrostatic printers
US3902421A (en) * 1973-06-08 1975-09-02 Rank Xerox Ltd Method for forming a picture image

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1941148A (en) * 1932-08-06 1933-12-26 American Wringer Company Inc Printing plate
US2725304A (en) * 1951-08-31 1955-11-29 Haloid Co Process for developing an electrostatic latent image
US2824813A (en) * 1952-05-12 1958-02-25 Haloid Co Method for developing electrostatic latent images
GB820763A (en) * 1956-07-16 1959-09-23 Kodak Ltd Improvements in or relating to electrostatic printing
US2910351A (en) * 1955-01-03 1959-10-27 Gen Electric Method of making printed circuit
US2972304A (en) * 1959-06-02 1961-02-21 Eastman Kodak Co Electrostatic printing
US3091176A (en) * 1960-08-18 1963-05-28 James F Wall Plastic printing plates
US3120806A (en) * 1957-04-24 1964-02-11 Ibm Magnetic image plate
US3121009A (en) * 1960-03-16 1964-02-11 Rca Corp Preparation of etched plates
US3160091A (en) * 1959-05-14 1964-12-08 Xerox Corp High speed xeroprinter and method therefor

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1941148A (en) * 1932-08-06 1933-12-26 American Wringer Company Inc Printing plate
US2725304A (en) * 1951-08-31 1955-11-29 Haloid Co Process for developing an electrostatic latent image
US2824813A (en) * 1952-05-12 1958-02-25 Haloid Co Method for developing electrostatic latent images
US2910351A (en) * 1955-01-03 1959-10-27 Gen Electric Method of making printed circuit
GB820763A (en) * 1956-07-16 1959-09-23 Kodak Ltd Improvements in or relating to electrostatic printing
US3120806A (en) * 1957-04-24 1964-02-11 Ibm Magnetic image plate
US3160091A (en) * 1959-05-14 1964-12-08 Xerox Corp High speed xeroprinter and method therefor
US2972304A (en) * 1959-06-02 1961-02-21 Eastman Kodak Co Electrostatic printing
US3121009A (en) * 1960-03-16 1964-02-11 Rca Corp Preparation of etched plates
US3091176A (en) * 1960-08-18 1963-05-28 James F Wall Plastic printing plates

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3370529A (en) * 1966-08-05 1968-02-27 Fairchild Camera Instr Co Electrostatic printer having selfregulating corona discharge
US3386551A (en) * 1966-11-14 1968-06-04 Litton Business Systems Inc Method of and apparatus for using radio or high frequency energy to produce printed matter
US3443517A (en) * 1967-01-04 1969-05-13 Xerox Corp Electrostatic duplicating system employing relief printing plate
US3477368A (en) * 1967-10-24 1969-11-11 Itt Printing apparatus employing magnetic transfer band in which image impressions can be made
US3515059A (en) * 1968-03-05 1970-06-02 Patent Dev Corp Hot stamping die having insulated surfaces adjacent the die faces
US3786745A (en) * 1970-09-05 1974-01-22 Philips Corp Durable registration template for electrostatic printers
US3902421A (en) * 1973-06-08 1975-09-02 Rank Xerox Ltd Method for forming a picture image

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Publication number Publication date
DE1254160B (de) 1967-11-16

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