US3417734A - Apparatus for developing a latent electrostatic image with a liquid aerosol - Google Patents

Apparatus for developing a latent electrostatic image with a liquid aerosol Download PDF

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Publication number
US3417734A
US3417734A US440850A US44085065A US3417734A US 3417734 A US3417734 A US 3417734A US 440850 A US440850 A US 440850A US 44085065 A US44085065 A US 44085065A US 3417734 A US3417734 A US 3417734A
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United States
Prior art keywords
electrode
development
grid
counterelectrode
grid electrode
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Expired - Lifetime
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US440850A
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English (en)
Inventor
Simm Walter
Koch Otto
Taterra Gottfried
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Bayer AG
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Bayer AG
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Priority claimed from DE1964F0042540 external-priority patent/DE1241264B/de
Application filed by Bayer AG filed Critical Bayer AG
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Publication of US3417734A publication Critical patent/US3417734A/en
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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
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/10—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer
    • G03G15/101—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer for wetting the recording material

Definitions

  • ATTORNEYS 3,417,734 APPARATUS FOR DEVELOPING A LATENT ELEC- TROSTATIC HMAGE WITH A LIQUID AERQSOL Walter Simm, Upladen, Otto Koch, 'Cologne-Stammheim,
  • An apparatus for developing a latent electrostatic image on a photoconductive layer on a photoconductive material with a liquid aerosol comprises means for transporting the developer liquid to the atomizing electrode with the grid electrode arranged between the atomizing electrode and photoconductive layer and with the grid being parallel to the layer and a counterelectrode supports the photoconductive material.
  • the counterelectrode is made of electrically conductive wire mesh.
  • the apparatus also includes means for generating a stream of gas from behind and through the counterelectrode with the gas flowing in the opposite direction as the liquid aerosol.
  • the invention relates to an apparatus for the electrophotographic development of latent electrostatic images, using liquid aerosols which have been prepared electrostatically, a grid electrode being used as developer elec trode and a Wire mesh as counterelectrode.
  • the central effect When using the above mentioned apparatus for developing charge images, a certain distance between the grid electrode and the support carrying the image is necessary in order to ensure that the grid structure does not appear on the reproduction.
  • an aberration is frequently observed under these conditions, which will here be termed the central effect. It occurs especially when the images have not been developed sufficiently completely or when the optical contrast is not sufficient.
  • the central effect consists in small image areas, which are uniformly blackened in the original, becoming more strongly blackened in the central parts of the copy than at the periphery due to the aerosol development. This phenomenon is in contrast to the marginal effect which frequently occurs in electrostatic development with toner powder and which particularly emphasises the margins of image areas.
  • the central effect is marked in United States Patent 3,417,734 Patented Dec. 24, 1968 lines of about 1 mm. in width and below. Under unfavourable conditions, lines of smaller width than in the original are obtained on the copy.
  • the known development apparatus is not suitable for a continuous process since the continuous development would have to be interrupted for cleaning the development grid electrode. Moreover, it would not be possible to keep the metal plate, which serves as support for the electrophotographic material, completely and constantly covered by the paper as the individual sheets of the paper pass through the apparatus. If, however, the surface of the supporting plate is exposed from time to time to the aerosol which is to a large extent held back by the grid electrode lying above the plate but nevertheless penetrates in very small quantities, a thin layer of the deposited aerosol is formed on the plate after a short time, this layer contaminating the paper from the rear surface.
  • the grid electrode is kept at a distance of about 5 mm. from the photoconductive layer containing the alternativet charge image in order to avoid contamination of the photoconductive layer by the grid and suppress the reproduction of the grid structure in the image.
  • a liquid aerosol development apparatus having means for electrostatically generating the aerosol, which is characterized by a development grid electrode and a grid-like counterelectrode for the development electrode which serves as support for the photoconductive material to be developed.
  • the apparatus of the invention is further characterized by means for producing a stream of gas preferably .air from behind the counterelectrode which flows through the counterelectrode moving in the opposite direction to the liquid aerosol.
  • the photoconductive material is placed beween the development electrode and the counterelectrode, so that the photoconductive layer bearing the latent electrostatic image contacts the development electrode and the rear of the photoconductive material is placed on the counterelectrode. No contamination of the photoconductive layers occurs even when the photoconductive material is moved between the electrodes. This was very unexpected since it had to be assumed that as the photoconductive layer glides along the development grid electrode, this layer would be contaminated by the liquid developer aerosol and moreover, it had to be assumed that when the photoconductive layer made contact with the development grid electrode, a transfer of charge would take place which would disturb the latent charge image on the photoconductive layer.
  • Transfers of charges between the photoconductive layer bearing a charge pattern in accordance with the image to be reproduced and the development grid electrode occur only to such a slight extent that they are negligible. More- 3 over, such transfers of charges can be prevented by coating the surface of the grid with a thin insulating layer of lacquer on the side facing the paper.
  • a conductive wire mesh is arranged parallel to the grid electrode, the distance being chosen to be so small that the electrophotographic paper slides with the photoconductive layer along the development grid electrode and with its paper support over the wire mesh of the counterelectrode through the development station.
  • the counterelectrode has preferably a mesh size of be tween 10 and 50 meshes per cm.
  • the development grid electrode and the wire mesh of the counterelectrode are preferably conductively connected together or connected to a variable voltage through a voltage source.
  • the aerosol sprayed from the atomizer electrode cannot be deposited on that side of the grid electrode but only on the surface facing the atomizer electrode.
  • the electrostatic field is so powerful that deposition is hardly impaired.
  • electric wind we understand the following phenomenon: Electric charges or charged particles, which tlow in a certain direction cause an agitation of the air or any gas being present in that space in the same direction. This effect appears as a blast or draught of the gas.
  • two or more rollers having an absorbent covering are rolled over the grid, these absorbent rollers being preferably so arranged that the atomizer electrode lies between two rollers and is moved by them simultaneously in order to clean the surface of the development grid electrode which faces the atomizing electrode from the droplets of the developer aerosol sprayed on it.
  • FIG. 1 A preferred embodiment for the apparatus according to the invention is shown in FIG. 1. It consists of a development grid electrode '1 with a wire mesh as counterelectrode 2 arranged parallel thereto, the distance between the grid and the mesh being maintained so small that an electrophotographic paper 3 lying between them has its photoconductive layer 4- bearing the latent electrostatic image in contact with the grid electrode 1 and its rear surface at the same time in contact with the counterelectrode 2.
  • the counterelectrode 2 is connetced to the grid it through a voltage source which preferably has a low internal resistance. The voltage can be adjusted in the region of v. to 300 v.
  • One of the electrodes 1 or 2 is grounded and connected to the voltage source 100 in such a manner that the grid eletcrode 1 has a negative potential as compared with the counterelectrode 2.
  • a ventilator 5 which blows a stream of air, uniformly distributed over the whole grid by the deflector plate 6, through the wire mesh of the counterelectrode and the development grid electrode.
  • the grid electrode is coated with a thin insulating layer on the surface remote from the atomizer electrode.
  • the grid lines of the development grid electrode extend obliquely at an angle between 0 and 45, preferably 23, to the direction of Sliding of the electrophotographic paper.
  • rollers 7 equipped with absorbent covers 8 press against the surface of the grid electrode 1 which faces the atomizer electrode.
  • the rollers are attached to a movable support 9 and together with this support they are moved parallel to the grid in two directions by a suitable device such as a cross-hatched screw 10 which in turn is driven by a motor 11.
  • the container 12 for the developer liquid with the electrostatic atomizer electrode 13 which is driven by a motor 14 by way of an insulating driving element 15, e.g., a drive belt.
  • Atomizer apparatus of this kind are described in Belgian Patent No. 634,184.
  • the atomizer electrode is arranged between rollers 3 in such a way that sufi'icicnt space is left to enable the aerosol produced to be deposited on the grid.
  • the developer container 12 with atomizer electrode 13 is secured in insulated manner on the support 9.
  • the high voltage required for the atomization is supplied through a metal tip 16 which sweeps over a metal rail 17 being fixed in an insulated manner, during the movement of the support 9 but without touching the rail.
  • the high potential required for the electrostatic atomizing is conducted from rail 17 to the metal tip 16 and the atomizer electrode through a corona which is formed at the metal tip.
  • the rail is connected to a high voltage source having, for example, preferably a voltage of 10 to 30 kv.
  • the electrophotographic paper slides between the grid 1 and the mesh 2, the movement of the paper taking place obliquely to the direction of the grid lines of the development electrode.
  • the atomizer electrode 13 with the rollers 7 at the same time performs a pendulous motion perpendicularly to the direction of travel of the electrophotographic material. The deflection from the central position is sufficient to enable the surfaces over which the rollers move to make contact with each other or overlap.
  • the apparatus supplied sharp images without disturbing marginal or central effects. Apart from rendering charge images visible, it may also be used for sensitizing surfaces either in areas corresponding to images or in a mosaic pattern or homogeneously, according to the process of Belgian Patents Nos. 633,517 and 633,694.
  • any developer liquid which has been found suitable for electrostatical atomizing such as described in Belgian Patent No. 619,914.
  • electrophotographic materials can be developed in the apparatus of the present invention.
  • the ordinary electrophotographic elements comprising a supported photoconductive layer which essentially consists of zinc oxide as photoconductive compound dispersed in an insulating binding agent, such as silicone resins, styrene butadien copolyers, styrene-alkyd resins, silicone-alkyd resins, soya-alkyd resins, polyvinylchloride, polyvinylacetate and the like.
  • an insulating binding agent such as silicone resins, styrene butadien copolyers, styrene-alkyd resins, silicone-alkyd resins, soya-alkyd resins, polyvinylchloride, polyvinylacetate and the like.
  • Suitable electrophotographic materials have been described in prior art.
  • the present invention is preferably performed with photoconductive layers which yield negatively charged latent electrostatic images and with a liquid aerosol, the droplets of which are positively charged.
  • the development grid electrode has either no potential or a slightly negative potential for example up to -20 v.
  • an apparatus for developing a latent electrostatic image on a photoconductive layer of a photoconductive material with a liquid aerosol comprising an atomizing electrode for spraying developer aerosol, said atomizer electrode being in liquid communication with a source of developer liquid, a grid electrode arranged between the electrostatic atomizing electrode and the photoconductive layer bearing the latent electrostatic image to be developed, said grid electrode being parallel to the photoconductive layer, and a counterelectrode supporting the photoconductive material, the improvement consisting of said counterelectrode being electrically conductive wire mesh, means for generating a stream of a gas from behind the counterelectrode and through the counterelectrode, flowing in the opposite direction to the liquid aerosol, said grid electrode and said counterelectrode being arranged at a distance essentially corresponding to the thickness of the photoconductive material so that the photoconductive layer contacts the grid electrode and the rear surface of the photoconductive material contacts the counterelectrode, said counterelectrode being connected to the grid electrode through voltage source means, and said voltage source means applying
  • An apparatus as defined in claim 1 characterized in that said means for generating a stream of gas is a ventilator arranged behind the counterelectrode.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Wet Developing In Electrophotography (AREA)
US440850A 1964-04-07 1965-03-18 Apparatus for developing a latent electrostatic image with a liquid aerosol Expired - Lifetime US3417734A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE1964F0042540 DE1241264B (de) 1964-04-07 1964-04-07 Vorrichtung zur elektrophotographischen Entwicklung von Ladungsbildern
FR12280A FR1429157A (fr) 1964-04-07 1965-04-07 Appareil pour le développement d'images photographiques constituées par des charges électrostatiques

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US3417734A true US3417734A (en) 1968-12-24

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3854399A (en) * 1972-12-29 1974-12-17 Dick Co Ab Method and means for operating an ink jet printer without splatter
US3967549A (en) * 1973-05-11 1976-07-06 Electroprint, Inc. Ink supply system for an ink mist printer
US4137867A (en) * 1977-09-12 1979-02-06 Seiichiro Aigo Apparatus for bump-plating semiconductor wafers

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2784109A (en) * 1950-09-18 1957-03-05 Haloid Co Method for developing electrostatic images
US2808328A (en) * 1950-07-15 1957-10-01 Carlyle W Jacob Method and apparatus for xerographic reproduction
US3005726A (en) * 1958-05-01 1961-10-24 Xerox Corp Process of developing electrostatic images
US3068115A (en) * 1961-02-06 1962-12-11 Xerox Corp Electrostatic emulsion development
US3169886A (en) * 1959-11-18 1965-02-16 Bayer Ag Apparatus for the electrophotographic production of images
US3212890A (en) * 1955-09-30 1965-10-19 Minnesota Mining & Mfg Photoconductive element for use in electrophotography containing a heavy metal soap of a long chain fatty acid; and process for using same
US3330683A (en) * 1961-04-26 1967-07-11 Bayer Ag Method of developing an electrostatic image with an electrically charged liquid aerosol

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2808328A (en) * 1950-07-15 1957-10-01 Carlyle W Jacob Method and apparatus for xerographic reproduction
US2784109A (en) * 1950-09-18 1957-03-05 Haloid Co Method for developing electrostatic images
US3212890A (en) * 1955-09-30 1965-10-19 Minnesota Mining & Mfg Photoconductive element for use in electrophotography containing a heavy metal soap of a long chain fatty acid; and process for using same
US3005726A (en) * 1958-05-01 1961-10-24 Xerox Corp Process of developing electrostatic images
US3169886A (en) * 1959-11-18 1965-02-16 Bayer Ag Apparatus for the electrophotographic production of images
US3068115A (en) * 1961-02-06 1962-12-11 Xerox Corp Electrostatic emulsion development
US3330683A (en) * 1961-04-26 1967-07-11 Bayer Ag Method of developing an electrostatic image with an electrically charged liquid aerosol

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3854399A (en) * 1972-12-29 1974-12-17 Dick Co Ab Method and means for operating an ink jet printer without splatter
US3967549A (en) * 1973-05-11 1976-07-06 Electroprint, Inc. Ink supply system for an ink mist printer
US4137867A (en) * 1977-09-12 1979-02-06 Seiichiro Aigo Apparatus for bump-plating semiconductor wafers

Also Published As

Publication number Publication date
FR1429157A (fr) 1966-02-18

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