US3775106A - Electrophotographic process - Google Patents

Electrophotographic process Download PDF

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Publication number
US3775106A
US3775106A US00175450A US3775106DA US3775106A US 3775106 A US3775106 A US 3775106A US 00175450 A US00175450 A US 00175450A US 3775106D A US3775106D A US 3775106DA US 3775106 A US3775106 A US 3775106A
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United States
Prior art keywords
light
color
electrophotographic process
black
developing
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Expired - Lifetime
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US00175450A
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English (en)
Inventor
Y Tamai
S Osawa
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Fujifilm Holdings Corp
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Fuji Photo Film Co Ltd
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    • 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
    • G03G13/06—Developing
    • G03G13/08—Developing using a solid developer, e.g. powder developer
    • 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
    • G03G13/01—Electrographic processes using a charge pattern for multicoloured copies
    • 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, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/12—Recording members for multicolour processes
    • 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

  • ABSTRACT An electrophotographic process which comprises uniformly charging a surface of a photoconductive insulating layer having light-sensitivity in an intrinsic sensitive region and extended spectrum region, the photoconductive insulating layer exhibiting light fatigue when exposed to light in the range of its intrinsic sensitive region, imagewise exposing the surface to light which covers the entire light-sensitive region of the light-sensitive layer from an original which includes a first colored portion which absorbs substantially all of the light and a second colored portion which absorbs from the light substantially only the wavelength range corresponding to the intrinsic sensitive region to form on the photoconductive insulating layer an electrostatic latent image corresponding to the first colored portion and a substantially non-conductive area corresponding to the second colored portion, developing the electrostatic latent image by electroscopic developer, again uniformly charging the surface of the layer to form a second electrostatic latent image at least at the substantially non-conductive area and developing the second electrostatic latent image with electroscopic developer.
  • An electrophotographic process in which electrostatic latent images formed on the surface of a photoconductive light-sensitive layer are developed with electroscopic powders (toners) has already been utilized practically.
  • repetition exposure and development procedures in each color a copy of an original (object) containing color image is obtained.
  • a process containing imagewise exposure on a charged xerographic plate through a color separation filter, development by toners having complementary color to the color filter, and transfer the toner image onto a sheet of white paper is repeated changing the combination of the filter and toners to obtain a color image.
  • so-called o'verprinting method comprising cycles of charging electrophotographic lightsensitive paper, imagewisely exposing by color separation method and developing by color toner for obtaining color image has already been practically used as REMAK PROCESS.
  • an object of this invention is to obtain rapidly a copy of color images. Another object is to obtain color images by one time exposing operation and further object is to obtain color images with accurate registration.
  • the inventors found a method to obtain a color image by only one time exposing operation.
  • the electrophotographic process of this invention is characterized in that a surface of a photoconductive insulating layer having light-sensitivity in intrinsic sensitivity region and extended spectrum region is uniformly charged in the dark, imagewisely exposing the layer with light which covers the whole sensitive region of the layer developing the formed electrostatic latent image with an electroscopic toner to form a first image charging again the entire surface of the layer then developing with an electroscopic toner to form a second image.
  • FIGS. 1-6 are schematic views showing the process ofthis invention.
  • FIG. 1 shows a sensitive sheet comprising a photoconductive insulating layer 12 provided on a support 11.
  • the photoconductive insulating layer comprises a mixture of photoconductor such as zinc oxide, titanium dioxide, cadmium sulfide, or zinc sulfide, and insulative resin also a layer of an organic photoconductor and a layer containing an organic photoconductive material may be used.
  • a support 11 or its surfaceto be applied a sensitive layer 12 should be treated to show conduc- I tivity.
  • the sensitivity of a photoconductive material is normally limited to a spectral region where an intrinsic sensitivity of the material exists.
  • the intrinsic sensitive region of conventional photoconductors generally exists at ultraviolet region or near ultraviolet region.
  • a photoconductor to be employed in this invention is preferred to be spectrally sensitized so that it would have photoconductivity to the light of range other than its intrinsic sensitive region.
  • the commonly well known methods which employ a sensitizing dye gives preferably effects.
  • the sensitive region may also be extended by the use of coloring pigments. 1
  • FIG. 2 shows an example of process for uniformly charging the surface of light-sensitive layer 12.
  • 211 is a corona electrode and 22 is a conductive case.
  • Corona electrode comprises fine metal wire 'or metal probe.
  • High voltage of direct or alternative current is applied to the corona electrode.
  • FIG. 3 is a view showing image being exposed on the surface of the charged light-sensitive layer.
  • Light comprising intrinsic sensitive region and spectrally extended sensitive region is being applied.
  • a dye-sensitized zinc oxide is used as a photoconductor
  • light from a light source supplying near ultraviolet rays, for example a tungsten bulb or a fluorescent lamp is applied.
  • 31 is an original.
  • a black image 32 and a color image (other than black) 33 are beared on a transparent support is used.
  • An electrostatic latent image is formed on the sensitive layer 12 by means of exposure of light through an original.
  • portion A corresponding to black image 32 of the original the charge is retained since the portion was not exposed.
  • An electrical charge on portion B cor responding to a color image 33 is discharged, as a part of light within the sensitive region of the sensitive layer reach'ed'the light-sensitive layer through a color image 33.
  • an important phenomenon has occurred in the sensitive layer 12. Namely, usual color images do not transmit or reflect the ultraviolet or near ultraviolet rays, therefore, the portion B corresponding to a color image 33 is not irradiated with the light of an intrinsic sensitive region of the light-sensitive layer.
  • the portions other than A and B on the light-sensitive layer 12 is exposed to light of an intrinsic sensitive region and sensitized region.
  • the photoconductive layer containing dyesensitized zinc oxide When the photoconductive layer containing dyesensitized zinc oxide is exposed to light of its intrinsic sensitive region, the photoconductive layer shows lightfatigue. The light-fatigue is exhibited as a persistence of conductivity after exposure. Accordingly, a portion A having electrostatic latent images and non-light fatigued portion B are formed on the light-sensitive layer 12 in FIG. 3.
  • FIG. 4 shows developing step of the electrostatic latent image formed according to the process as shown in FIG. 3 with an electroscopic toner. Only on the portion A where the electrostatic latent image existed the developing toner is electrostatically deposited. While the toner does not deposit on the non-light fatigued portion B where electrical charge was conducted away.
  • FIG. 5 shows a process in which the sensitive sheet having animage obtained along the method of FIG. 4 is subjected torecharging operation.
  • the portions A and B where has no light fatigue due to exposing operation of FIG. 3 are charged by this recharging operation.
  • the portion effected with light fatigue (the portions other than A and B in the lightsensitive layer) is hardly charged or a little if any.
  • the charge on A and B portions is a little decreased at edge portions, as the first image previously formed and light-fatigued portion have already been generated on the light-sensitive sheet, therefore, an indistinct image may be obtained.
  • FIG. 6 shows a process which the sensitive sheet is again developed.
  • a toner 61 is deposited electrostatically on A and B portions. Accordingly the images thus formed on the light-sensitive sheet are, at A portion, an image comprising a mixed color of developing toner 41 and developing toner 61, and, at B portion, an image comprising only developing toner 61.
  • An electroscopic developer those used in a conventional electrophotographic process such as cascade developer, magnetic blush developer, liquid developer, and powder cloud developer may be employed. It may also be possible to carry out development by utilizing wetability to a liquid at the latent image portion, as shown in U. S. Pat. No. 3,285,741.
  • Any organic or inorganic pigments so far as they are used as toners in usual electrophotographic developing methods, may be used which is, for example, carbon black, brilliant carmine 6B, phthalocyanine blue, benzidine yellow. hanza yellow, chrome yellow, iron oxide, cadmium sulfide, and quinacridon red.
  • Example Color of developer Color of Image The first The second B developing developing 7 portion portion 1 black magenta black magenta 2 black red black red 3 black cyan black cyan 4 green magenta black magenta 5 black green black green 6 cyan magenta blue magenta 7 blue red purple red 8 magneta cyan blue cyan 9 yellow cyan green cyan
  • Examples 1, 2 and 4 are suitable for copying an original which is a printed document having red correction marks and/or signature in red color.
  • Example 3 is suitable for copying original which is a printed document in black having additional remarks or signature in blue ink.
  • a two-color copy may optionally be obtained by other combinations.
  • the difference of color tone between A and B portions may be further emphasized by adding a material for preventing recharging to the developing toner of the first developing process.
  • the letters, as well as the color of the paper can, of course, be reproduced.
  • a developing method in the first developing step does not necessarily to be the same as that in the second developing step.
  • the first color developing step may be done by using a liquid developing method, and the second color may then be developed by cascade developing method.
  • both of the first and second developing steps may preferably done by a liquid developing method to obtain good results. Namely, fixing of the toners is easily performed, and while the sheet being still wet, after developing the first color, the recharging and the subsequent second color development steps may be carried out.
  • the first color if formed by a liquid development while the second color is formed by a dry type developing method, it is necessary that the surface of the sheet be dried after the first development. If the sheet surface is still wet, it may cause to stick dry toners to non-image portions.
  • An image having varied optical density due to the difference of color hue of the original may be obtained by using the same color toner in both the first and the second developing steps.
  • a layer may be appropriate which shows a light fatigue against irradiation of light of the intrinsic sensitivity region, but not to have light fatigue against the light of optically sensitized region. Examples of such materials may generally be found in a dye-sensitized zinc oxide sheet.
  • the dyes used in the invention for extending the spectral sensitivity of the recording sheet are well known in the art, and found, for example, in US. Pat. No. 3,052,540.
  • the typical examples of dyes are fluorescein, eosine erythrosine, rose bengal, malachite green, crystal violet, fuchsine, methyl green, brilliant green, methylene blue, acridine orange, kryptocyanine, pinacyanol, alizarine red, etc.
  • a method of dye sensitizing photoconductive zinc oxide powder with dye in combination with a Lewis acid as described in British Pat. No. 1,005,245 may be employed in this invention.
  • the dyes used in the method are auramine 0, thioflavine TG, rhodamine B, quinaldine red, nigrosine, 1,4-diaminoanthraquinone, chrome blue GCB, lithosol blue 6G, etc.
  • sensitizing dye for photoconductive titanium dioxide used in the invention there may be illustrated auramine, fluorescein, rose bengal, basic flavine 86, etc.
  • the amount of dye may readily be determined by a person having ordinary skill in the art.
  • the insulative resinous binder of the sheet may be selected from thermoplastic resins and thermosetting resins.
  • suitable resins are vinyl chloride-vinyl acetate copolymers, polystyrene, styrene-butadiene copolymers, polyolefines, acryl resins, alkyd resins cured with metal salts or polyisocyanates, polyesters, etc.
  • Preferred binder is copolymers of vinyl chloride and cured alkyd resins.
  • the ratio of the photoconductor to the resinous binder may be varied between 8 l to 2,5 l by weight.
  • the light-sensitive layer may be charged to either positively or negatively.
  • the sensitive sheet is ordinarily used by negatively charging, however, it may be utilized positive charging by using copolymers of vinyl chloride as binder. While titanium dioxide-binder sheet may be chargedto both polarities.
  • a light-sensitive sheet which is difficult to be fatigued in its intrinsic sensitivity region while read ily fatigued by light of sensitizing region may be employed in this invention.
  • an electric charge on a light-sensitive sheet is opposite to that of a developing toners.
  • a toner used in the step of FIG. 4 is preferred to be positively charged.
  • EXAMPLE 1 The surface of a sheet of paper having a conductive layer has been provided with a photoconductive insulating layer comprising styrene modified alkyd resin hardened by polyisocyanate compound and photoconductive zinc oxide (Sazex made by Sakai Chemical Industry Co., Ltd.)
  • Weight rate of the resin and the zinc oxide being 4 parts by weight of zinc oxide per 1 part by weight of the resin.
  • the sensitive region of this sensitive layer has been extended in the visual spectrum region in its entirely by adding sensitizing dyes of fluorescein, rose bengal and brilliant blue FCF.
  • the sensitive layer was sufficiently adapted to the darkness retained at 40 'C., and its light fatigue was well removed. And then it was subjected in the dark for uniform charging to corona discharge from corona electrode given with 6KV.
  • the surface potential was 210V.
  • the original used was a white art paper typed with black ink having some additional remarks in red ink. The light from a white wolfram light source was applied to the original, and its reflective light image was projected to a surface of the charged sensitive layer.
  • the surface of the layer was wetted with Isoper H (isoparaffinic hydrocarbon made by Esso Standard Co.) and then it was developed by black liquid developer dispersed with carbon black in isoparaffinic hydrocarbon. The charge of the toner was positive. Black image for only the typed portion in black in the original was obtained.
  • thesensitive layer having a black image was again subjected to corona discharge from corona electrode having 6KV, and was then developed by a liquid developer having magenta color toner dispersed with Brilliant Carmine 6B. The toner of magenta color in the developer had positive charge.
  • EXAMPLE 2 In place of the original in Example I, a sheet of red color paper printed with black ink was used as an original. The other conditions remain the same as those of Example 1. The sheet obtained had magenta toner deposited on its entire surface, in which a black image was clearly copied.
  • EXAMPLE 4 In place of the first black liquid developer of Example l, cascade developer containing black toner was used. Subsequent to the development of the first color, the sheet surface was retained for 15 seconds in vapor of trichlorethylene to fix image and recharged.
  • a black and cyan color image was obtained upon the same procedures as those of Example 1.
  • the portion in red ink in the original was copied to be in cyan color.
  • EXAMPLE 6 In place of the first black liquid developer of Example 1, green liquid developer disposed with phthalocyanine blue and Benzidine Yellow GR, was used. The black image in the original was copied to be in pure black, and the portion in red ink was copied in magenta color.
  • EXAMPLE 7 The original used in Example 5 was replaced by a sheet of white art paper, on which descriptions were made in black and blue inks.
  • An electrophotographic process which comprises uniformly charging a surface of a photoconductive insulating layer having light-sensitivity in an intrinsic sensitive region and extended spectrum region, said photoconductive insualating layer exhibiting light fatigue when exposed to light in the range of its intrinsic sensitive region, imagewise exposing the surface to light which covers the entire light-sensitive region of the light-sensitive layer from an original which includes a first colored portion which absorbs substantially all of said light and a second colored portion which absorbs from said light substantially only the wavelength range corresponding to said intrinsic sensitive region to form on said photoconductive insulating layer an electrostatic latent image corresponding to said first colored portion and a substantially non-conductive area corresponding to said second colored portion, developing the electrostatic latent image by electroscopic developer, again uniformly charging the surface of the layer to form a second electrostatic latent image at least at said substantially non-conductive area and developing thesaid second electrostatic latent image with electroscopic developer.
  • photoconductive insulating layer comprises dye-sensitized zinc oxide dispersed in resinous binder.
  • photoconductive insulating layer comprises dye-sensitized titanium dioxide dispersed in resinous binder.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photoreceptors In Electrophotography (AREA)
  • Developing Agents For Electrophotography (AREA)
  • Color Electrophotography (AREA)
  • Liquid Developers In Electrophotography (AREA)
  • Electrophotography Using Other Than Carlson'S Method (AREA)
US00175450A 1970-08-28 1971-08-27 Electrophotographic process Expired - Lifetime US3775106A (en)

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JP45075319A JPS4917531B1 (enrdf_load_stackoverflow) 1970-08-28 1970-08-28

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JP (1) JPS4917531B1 (enrdf_load_stackoverflow)
BE (1) BE771855A (enrdf_load_stackoverflow)
CA (1) CA946465A (enrdf_load_stackoverflow)
CH (1) CH577190A5 (enrdf_load_stackoverflow)
DE (1) DE2142804A1 (enrdf_load_stackoverflow)
GB (1) GB1328318A (enrdf_load_stackoverflow)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4250239A (en) * 1977-06-09 1981-02-10 Ricoh Company, Ltd. Color electrostatographic process and material
US4281051A (en) * 1978-11-29 1981-07-28 Ricoh Company, Ltd. Three color electrostatographic process
US4310610A (en) * 1978-04-27 1982-01-12 Ricoh Company, Ltd. Two color electrostatographic process
US4335194A (en) * 1978-02-20 1982-06-15 Ricoh Company, Ltd. Two color electrophotographic process and material
US4349268A (en) * 1979-06-28 1982-09-14 Konishiroku Photo Industry Co., Ltd. Electrostatic image-forming process and an apparatus therefor
DE3243869A1 (de) * 1981-11-27 1983-06-09 Ishihara Sangyo Kaisha, Ltd., Osaka Elektrophotographisches aufzeichnungsverfahren
US4599285A (en) * 1983-10-03 1986-07-08 Konishiroku Photo Industry Co., Ltd. Multiplex image reproducing method
US5183717A (en) * 1990-08-03 1993-02-02 Eastman Kodak Company Field-enhanced charge injection amplification
US5700611A (en) * 1995-12-07 1997-12-23 Eastman Kodak Company Method for forming overlapping toner images
USRE36304E (en) * 1983-10-03 1999-09-14 Konica Corporation Multiplex image reproducing method

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS50146828U (enrdf_load_stackoverflow) * 1974-05-20 1975-12-05
JPS6028351B2 (ja) * 1977-10-13 1985-07-04 株式会社リコー ２色電子写真複写装置

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3337340A (en) * 1961-12-28 1967-08-22 Australia Res Lab Method for the reproduction of color
US3355288A (en) * 1963-11-19 1967-11-28 Australia Res Lab Electrostatic printing method and apparatus
US3368894A (en) * 1963-11-05 1968-02-13 Australia Res Lab Multiple copy printing method and apparatus
US3576624A (en) * 1967-10-17 1971-04-27 Australia Res Lab Electrostatic printing method employing a pigmented light filter

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3337340A (en) * 1961-12-28 1967-08-22 Australia Res Lab Method for the reproduction of color
US3368894A (en) * 1963-11-05 1968-02-13 Australia Res Lab Multiple copy printing method and apparatus
US3355288A (en) * 1963-11-19 1967-11-28 Australia Res Lab Electrostatic printing method and apparatus
US3576624A (en) * 1967-10-17 1971-04-27 Australia Res Lab Electrostatic printing method employing a pigmented light filter

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4250239A (en) * 1977-06-09 1981-02-10 Ricoh Company, Ltd. Color electrostatographic process and material
US4335194A (en) * 1978-02-20 1982-06-15 Ricoh Company, Ltd. Two color electrophotographic process and material
US4310610A (en) * 1978-04-27 1982-01-12 Ricoh Company, Ltd. Two color electrostatographic process
US4281051A (en) * 1978-11-29 1981-07-28 Ricoh Company, Ltd. Three color electrostatographic process
US4349268A (en) * 1979-06-28 1982-09-14 Konishiroku Photo Industry Co., Ltd. Electrostatic image-forming process and an apparatus therefor
DE3243869A1 (de) * 1981-11-27 1983-06-09 Ishihara Sangyo Kaisha, Ltd., Osaka Elektrophotographisches aufzeichnungsverfahren
US4599285A (en) * 1983-10-03 1986-07-08 Konishiroku Photo Industry Co., Ltd. Multiplex image reproducing method
US4679929A (en) * 1983-10-03 1987-07-14 Konishiroku Photo Industry Co., Ltd. Multiplex image reproducing apparatus
USRE36304E (en) * 1983-10-03 1999-09-14 Konica Corporation Multiplex image reproducing method
USRE36935E (en) * 1983-10-03 2000-10-31 Konica Corporation Multiplex image reproducing apparatus
US5183717A (en) * 1990-08-03 1993-02-02 Eastman Kodak Company Field-enhanced charge injection amplification
US5700611A (en) * 1995-12-07 1997-12-23 Eastman Kodak Company Method for forming overlapping toner images

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Publication number Publication date
DE2142804A1 (de) 1972-03-02
CA946465A (en) 1974-04-30
GB1328318A (en) 1973-08-30
CH577190A5 (enrdf_load_stackoverflow) 1976-06-30
JPS4917531B1 (enrdf_load_stackoverflow) 1974-05-01
BE771855A (fr) 1971-12-31

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