US3804659A - Electrophotographic reversal development process for enhancing the quality of the developed image - Google Patents

Electrophotographic reversal development process for enhancing the quality of the developed image Download PDF

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Publication number
US3804659A
US3804659A US00205996A US20599671A US3804659A US 3804659 A US3804659 A US 3804659A US 00205996 A US00205996 A US 00205996A US 20599671 A US20599671 A US 20599671A US 3804659 A US3804659 A US 3804659A
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US
United States
Prior art keywords
toner
insulating layer
electrophotographic
reversal development
liquid
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
US00205996A
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English (en)
Inventor
M Sato
Y Tamai
K Horikawa
O Fukushima
S Matsumoto
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Fujifilm Holdings Corp
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Fuji Photo Film Co Ltd
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Publication date
Application filed by Fuji Photo Film Co Ltd filed Critical Fuji Photo Film Co Ltd
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Publication of US3804659A publication Critical patent/US3804659A/en
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording-members for original recording by exposure, e.g. to light, to heat or to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/005—Materials for treating the recording members, e.g. for cleaning, reactivating, polishing
    • 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
    • G03G15/11—Removing excess liquid developer, e.g. by heat
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
    • Y10S430/001—Electric or magnetic imagery, e.g., xerography, electrography, magnetography, etc. Process, composition, or product
    • Y10S430/102—Electrically charging radiation-conductive surface

Definitions

  • Electrophotographic liquid developers are usually involved in processes as are described below.
  • pre-bathing An electrophotographic material with an electrostatic latent image formed thereon is first dipped in a tonerless insulating liquid and wetted on both sides. This practice is called pre-bathing.
  • the purpose of prebathing is to form a thin film to prevent adhesion of the toner suspended in the liquid developer to the electrophotographic material.
  • the pre-bathing liquid kerosene, cyclohexene, benzene, pentane, decalin, and many other non-polar hydrocarbons and halogenated hydrocarbons have been used.
  • the electrophotographic material that has undergone the pre-bathing process is then dipped in the developer.
  • the developer is composed of an insulating liquid (called a carrier liquid) with fine chargeable particles (toner) suspended therein.
  • a charge controlling agent intended to control the charging of the toner or a dispersion stabilizer intended to stabilize the dispersion is also present in the carrier liquid, either in suspension or dissolved.
  • charge controlling agents or dispersion stabilizers resins, varnishes or non-drying oils which are soluble in the carrier liquid, or resins, varnishes or the like which are not soluble in the carrier liquid have been used.
  • the carrier liquid is usually the same liquid used for prebathing.
  • the charge of the toner has the same sign as the electrostatic latent image, deposition of the toner onto noncharged or slightly charged regions of the latent image occurs, which is called reversal or repulsion development.
  • the toner is deposited onto the charged region of the latent image, which is called normal or attraction devel, opment.
  • the toner particles which are colorless or colored inorganic or organic pigments, are suspended in the carrier liquid, either by themselves or in such a form that resin or varnish is absorbed on the surface thereof.
  • Rinsing is accomplished either by dipping the developed electrophotographic material into a rinse or by spraying a rinse over the developed electrophotographic material.
  • a quick-drying insulating liquid with low solubility for the toner is utilized as the rinse.
  • difluorotetrachlorethane, trifluorotrichloroethane and Isoper E are recommended.
  • the purpose of rinsing is to remove the developer deposited on the surface of the electrophotographic material and to enhance the adhesiveness of the toner-developed image. The reason the toner-developed image is increased in adhesiveness is that the resin or varnish absorbed on the toner particles is fixed without being dissolved.
  • the electrophotographic material that has been rinsed is passed through squeeze rollers, whereby its surface is cleared of the developer deposited thereof and is almost dried. If the electrophotographic material is passed through the squeeze rollers immediately after being developed without being rinsed, the tonerdeveloped image often is transferred to the squeeze rollers or is crushed and oozes out. Even if rinsing is done, a too quick rinse, or an undesirable choice of the rinse can also give rise to the aforementioned troubles. Such trouble is liable to particularly occur when an electrophotographic material that has been reversal developed is squeezed. Normal development is hardly ever accompanied by such a problem.
  • FIG. 1 is a sectional view of an electrophotographic material with toner particles deposited on the surface thereof.
  • FIG. 2 is a sectional view equivalent to FIG. 1 illustrating the principle of the process of the invention.
  • FIG. 3 is a sectional view of apparatus useful for the practice of the present invention.
  • FIG. 1 illustrates a model intended to indicate the difference in the resistance of a toner image to squeezing between normal development and reversal development.
  • Electrophotographic material 10 is composed of a photoconductive insulating layer 11 and a conductive base 12.
  • a mixture of photoconductive powder and an insulating resin or an organic photoconductive compound is utilized to provide the photoconductive insulating layer.
  • the conductive base a plastic film coated with a conductive polymer, or a metal-vacuum deposited or metal plated paper or a paper impregnated with conductive polymer may also be employed, as may a metalized paper.
  • the photoconductive insulating layer 11 is assumed to be an n-type semiconductor.
  • a layer coated with a mixture of zinc oxide powder and insulating resin is such an n-type semiconductor.
  • the latent image is formed by negative charge 13.
  • the charge 14 is a positive counter charge, nearly equivalent to the negative charge 13, which is concentrated at the boundary between the photoconductive insulating layer 11 and the base 12.
  • the negative charge 13 exists mostly on the surface of the photoconductive insulating layer 11.
  • FIG. 2 is a view equivalent to FIG. I intended to illustrate the principle of the present invention.
  • Device 20 is a known and available corona charging unit composed of a corona electrode 21 and a shield case 22.
  • 23 is a DC high voltage powder source used to apply a positive high voltage to the corona electrode 21.
  • Positive corona ions resulting from the corona discharge are deposited on the toner 16 shown in FIG. 1, changing the negative polarity of toner 16 to a positive polarity.
  • Reference character 24 represents the toner l6 changed to have a positive charge.
  • a negative charge 25 equivalent thereto is imparted from the conductive layer 12 into the photoconductive insulating layer 11 (l 100 [1. thick), through which it arrives very close to toner 16.
  • the insulating layer 11 be an n-type semiconductor and the electrons are free to move. That is, n-type photoconductive insulating layer on which a negative latent image is formed is developed with negatively charged toner and then the image bearing layer is exposed to positive corona ion. Even if negative corona ions are made to deposit on the toner 16 by applying negative high voltage to the corona no positive charge equivalent thereto is imparted into the insulating layer 1 1. Therefore, the Coulombic force is low due to long distance between the negative charge and the positive charge of the toner 16.
  • the photoconductive insulating layer 11 is a p-type semiconductor such as selenium or polyvinylcarbazole
  • a positive latent image is formed thereon and developed with positively charged toner.
  • a developer made by dispersing resins, pigments and preferably heavy metal salts of organic acid into carrier liquid, as described in US. Pat. No. 3,257,322 or British Pat. No. 1,065,795. And then negative high voltage is applied to the corona electrode 21 so that the developed layer is exposed to negative corona ion.
  • the layer When the photoconductive insulating layer is n-type the layer must be positively charged after development and when p-type, the layer must be negatively charged.
  • FIG. 3 is a sectional view of equipment which can be used for this embodiment of the present invention.
  • Rollers 30 and 31 are a pair of feed rollers used to feed the developed electrophotographic material 10 held therebetween.
  • the roller 30 is flanged at both ends to prevent the surface thereof from contacting the toner image, and the electrophotographic material is fed while held between the flanges of the roller 30 and the roller 31.
  • Nozzles 32 and 33 are used to spray the rinse liquid over the top and back surfaces of the electrophotographic material.
  • Rollers 34 and 35 are a pair of feed rollers similar to rollers 30 and 31. Roller 34 is flanged at both ends.
  • Reference characters 36 and 37 denote a corona wire and a shield plate respectively.
  • Rollers 38 and 39 are pair of squeeze rollers. At least one of rollers 38 and 39 is covered with an elastic soft material (rubber, sponge, etc.). Rollers 30, 31, 34, 35 and 38 can be made of a hard material, such as metal or plastic.
  • the electrophotographic material is washed with the rinse between rollers 30 and 31 and rollers 34 and 35. Subsequently to rollers 34 and 35 it has the toner image surface thereof exposed to the corona discharge, and is thereafter squeezed to be dried.
  • the process of the present invention is not effective.
  • the present invention can be practiced as long as the toner layer deposited on the photoconductive layer shows a surface resistance of l0Q/square or higher.
  • Example I A sheet of art paper was coated with a mixture obtained by mixing weight parts of photoconductive zinc oxide powder with 20 weight parts of styrenated alkyd resin (Styresol 4400 trade name of Nippon Reichhold Co.) so that the dried thickness was approximately 7 microns.
  • the art paper used had earlier been coated with a polymeric quaternary ammonium salt (a conductive polymer known as Calgon Conductive Polymer 261 manufactured by Calgon, U.S.A.) to provide a dried coverage of 1.5 g/m
  • This electrophotographic material was charged to a surface potential of -180 V by a negative corona discharge in the dark and then exposed to imaging light, whereby a negative latent image was formed thereon. Subsequently, it was dipped into a developer containing a toner having a negative charge and developed for 1 minute.
  • the developer was prepared by the following procedure:
  • Safflower oil-modified alkyd resin 200 weight parts (Super Beckosol 1-537, trademark material manufactured by Nippon Reichhold Co.)
  • Rollers 31, 35 and 38 were l6 mm in diameter and were of stainless steel.
  • Rollers 30 and 34 were 16 mm in diameter, the flanges thereof being 18 mm in diameter, and were of stainless steel.
  • Roller 39 was 16 mm in outer diameter and was covered with 4 mm thick rubber. A stainless steel corona electrode of 0.1 mm diameter was used.
  • the corona electrode was impressed with a positive voltage of 8 kV with the corona electrode approximately 10 mm from the electrophotographic material.
  • the electrophotographic material was fed at a rate of mm per second, but the toner image withstood squeezing by rollers 38 and 39.
  • Example II Carbon Black Phthalocyanine Blue 0.4 weight parts 0.05 weight parts Ethyl Cellulose 1 weight part Ethyl Acetate 20 weight parts Toluene 19 weight parts
  • the pigments are covered by the ethyl cellulose and its polarity as toner was positive.
  • the latent image bearing paper was developed in such developer for 20 sec. After the development, the electrophotographic paper is rinsed in lsoper G (trade name of Esso Standard Oil Co.; isoparaffinic solvent whose evaporation speed is much higher than that of lsoper H) and exposed to negative corona ion in wet state.
  • the corona discharge electrode of molybdenum wire of 30 p. d) was kept at 15 mm apart from the paper, and applied a voltage of minus 7 KV. And then lsoper G sticked on the paper was removed by the squeeze rollers. An excellent negative image to original image was obtained.
  • exposure to corona ion after the development may be processed after rinse as described above or may be done immediately after the development eliminating the rinsing step.
  • the rinse is advantageous in making the paper dry fast and preventing fog on the image.
  • An electrophotographic process as claimed in claim 1 including rinsing the reversely developed insulating layer with an isoparaffinic solvent prior to said charging step.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Wet Developing In Electrophotography (AREA)
  • Photoreceptors In Electrophotography (AREA)
US00205996A 1970-12-10 1971-12-10 Electrophotographic reversal development process for enhancing the quality of the developed image Expired - Lifetime US3804659A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP45109877A JPS4926901B1 (https=) 1970-12-10 1970-12-10

Publications (1)

Publication Number Publication Date
US3804659A true US3804659A (en) 1974-04-16

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Application Number Title Priority Date Filing Date
US00205996A Expired - Lifetime US3804659A (en) 1970-12-10 1971-12-10 Electrophotographic reversal development process for enhancing the quality of the developed image

Country Status (6)

Country Link
US (1) US3804659A (https=)
JP (1) JPS4926901B1 (https=)
CA (1) CA960919A (https=)
DE (1) DE2161194A1 (https=)
FR (1) FR2117538A5 (https=)
GB (1) GB1356687A (https=)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3956524A (en) * 1974-12-04 1976-05-11 Xerox Corporation Method for the preparation of electrostatographic photoreceptors
US5815779A (en) * 1996-05-17 1998-09-29 Xerox Corporation System for conditioning liquid ink in a liquid ink type electrostatographic system
EP0921444A3 (en) * 1997-12-08 1999-09-08 Samsung Electronics Co., Ltd. Electrophotographic printer

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6177866A (ja) * 1984-09-26 1986-04-21 Ishihara Sangyo Kaisha Ltd カラ−電子写真方法
FR2648634B1 (fr) * 1989-06-16 1991-11-22 Salmson Pompes Circuit magnetique de stator de moteur electrique

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3383209A (en) * 1960-11-08 1968-05-14 Gevaert Photo Prod Nv Electrophotographic process including selective wetting by the developer liquid
US3444369A (en) * 1966-10-11 1969-05-13 Xerox Corp Method and apparatus for selective corona treatment of toner particles
US3560203A (en) * 1966-11-02 1971-02-02 Fuji Photo Film Co Ltd Electrophotographic developing process
US3650622A (en) * 1970-03-09 1972-03-21 Eastman Kodak Co Apparatus for control of bias potential in an electrophotographic copier
US3655419A (en) * 1968-11-12 1972-04-11 Fuji Photo Film Co Ltd Electrophotographic reversal developing process
US3663219A (en) * 1967-05-23 1972-05-16 Canon Camera Co Electrophotographic process
US3722994A (en) * 1969-06-04 1973-03-27 Canon Kk Method and device for removing developing liquid

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3383209A (en) * 1960-11-08 1968-05-14 Gevaert Photo Prod Nv Electrophotographic process including selective wetting by the developer liquid
US3425829A (en) * 1960-11-08 1969-02-04 Agfa Gevaert Nv Electrophotographic recording process
US3444369A (en) * 1966-10-11 1969-05-13 Xerox Corp Method and apparatus for selective corona treatment of toner particles
US3560203A (en) * 1966-11-02 1971-02-02 Fuji Photo Film Co Ltd Electrophotographic developing process
US3663219A (en) * 1967-05-23 1972-05-16 Canon Camera Co Electrophotographic process
US3655419A (en) * 1968-11-12 1972-04-11 Fuji Photo Film Co Ltd Electrophotographic reversal developing process
US3722994A (en) * 1969-06-04 1973-03-27 Canon Kk Method and device for removing developing liquid
US3650622A (en) * 1970-03-09 1972-03-21 Eastman Kodak Co Apparatus for control of bias potential in an electrophotographic copier

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3956524A (en) * 1974-12-04 1976-05-11 Xerox Corporation Method for the preparation of electrostatographic photoreceptors
US5815779A (en) * 1996-05-17 1998-09-29 Xerox Corporation System for conditioning liquid ink in a liquid ink type electrostatographic system
EP0921444A3 (en) * 1997-12-08 1999-09-08 Samsung Electronics Co., Ltd. Electrophotographic printer

Also Published As

Publication number Publication date
JPS4926901B1 (https=) 1974-07-12
DE2161194A1 (de) 1972-06-29
FR2117538A5 (https=) 1972-07-21
CA960919A (en) 1975-01-14
GB1356687A (en) 1974-06-12

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