US3844783A - Electrophotographic process including a color masking operation - Google Patents

Electrophotographic process including a color masking operation Download PDF

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Publication number
US3844783A
US3844783A US00213136A US21313671A US3844783A US 3844783 A US3844783 A US 3844783A US 00213136 A US00213136 A US 00213136A US 21313671 A US21313671 A US 21313671A US 3844783 A US3844783 A US 3844783A
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photosensitive element
transparent
main
toner
color
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US00213136A
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English (en)
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S Matsumoto
I Takahashi
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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
    • G03G13/01—Electrographic processes using a charge pattern for multicoloured copies

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  • An electrophotographic process including a color masking operation comprising providing a photoconductive insulator as a main photosensitive element and a substantially transparent photoconductive insulator as a transparent photosensitive element, where the main photosensitive element is provided with a grounded conductive support and the transparent photosensitive element is provided with a transparent grounded conductive support and where the spectrum sensitivity region of the transparent photosensitive element is different from the spectrum sensitivity region of the main photosensitive element or the main photosensitive element combined with a colored filter, charging both photosensitive elements with the same polarity, facing the charged surfaces of both the photosensitive elements toward each other so that a slight gap exists therebetween l) with the colored filter interposed and/or a substantially transparent insulator interposed, or (2) with nothing interposed, image exposing while both the photosensitive elements are held in registry from the side of the transparent photosensitive element
  • the present invention relates to a masking process which compensates deficiencies in the spectral absorption properties of coloring agents used for forming electrophotography multicolor images.
  • the so-called subtractive color process is utilized for multi-color electrophotographic printing to obtain a colored image by distributing the quantities of three kinds of coloring agents, which respectively absorb blue, green and red components of visible rays.
  • three kinds of coloring agents yellow to absorb blue; magenta to absorb green; and cyan to absorb red.
  • Coloring agents of magenta and cyan such as printing inks, pigments, dyestuffs, etc. absorb only green or red, respectively, and they do inaccurately absorb other wave length areas.
  • cyan coloring agents absorb a fair amount of green and a minor amount of blue while magenta absorbs a fair amount of blue and a minor amount of red.
  • the yellow coloring agent is nearly ideal in absorption.
  • the quantity of magenta coloring agent to absorb green decreased by the amount of said inaccurate absorption of the cyan coloring agent.
  • the overlapping portions of cyan and magenta color agents will then absorb a proper amount of green.
  • the cyan coloring agent absorbs blue and, if necessary, a decrease of yellow coloring agent corresponding to the quantity of cyan coloring agent in the image will overcome this fault. Correction for the inaccurate absorption of magenta coloring agents is quite the same.
  • a transparent electrophotographic sensitive element and an ordinary electrophotographic sensitive element are provided.
  • the photosensitive layers are sensitive to different regions of the spectrum.
  • the two photosensitive elements are uniformly charged and are placed as photosensitive layers facing each other to obtain simultaneously two color separated electrostatic latent images by exposure from the side of the transparent photosensitive element.
  • a primary object of the present invention is to provide a process of correcting the inaccurate absorption of coloring agents and provide clear color images.
  • FIG. I is an illustration of the exposure process of the present invention.
  • FIGS. 2 and 3 are illustrations of the whole process of the present invention.
  • FIG. 1 is an illustration the exposure process by the present invention.
  • 12 is the main photosensitive element and comprises a main photosensitive layer 1 which is a photoconductive insulating layer, and conductive support 2.
  • the transparent photosensitive element which acts as a developing electrode during development, and comprises transparent photosensitive layer 4 which is, a photoconductive insulating layer, and transparent support 5.
  • FIG. 7 represents the charge uniformly given the main photosensitive layer 1
  • 8 represents the charge uniformly given the transparent photosensitive layer 4.
  • the uniform charge may be either positive or negative, but the charges on the main and transparent photosensitive layers should be the same polarity.
  • a negative charge is shown in FIG. 1.
  • 10 is an original picture such as a color slide for exposure.
  • 11 is a source of illumination, and 9 is a projection lens.
  • 14 is a red, green or blue filter inserted between the transparent photosensitive layer 4 and the main photosensitive layer 1.
  • the main photosensitive layer and the trannsparent photosensitive layer are made to face each other, and filter 14 is placed between them whereafter exposure is made from the transparent photosensitive layer side as shown.
  • electrostatic latent images are formed on both photosensitive layers. Since the transparent photosensitive layers spectral sensitivity distribution differs from that of the main photosensitive layer due to the combination of the filter 14 and the main photosensitive layer, the electrostatic latent images formed are different and correspond to the colors of the original picture.
  • the total (or resulting) spectral sensitivity distribution of the main photosensitive layer is a function not only of the spectral sensitivity of the main photosensitive layer per se but also the spectral transmittance of the filter 14. It is important that the total (or resulting) spectral sensitivity distribution of the main photosensitive layer (that is, the spectral transmittance of filter 14 plus the spectral sensitivity of the main photosensitive layer) is substantially different from the spectral sensitivity of the transparent photosensitive layer. Thus, it is possible that the spectral sensitivity of the two photosensitive layers be different or the spectral sensitivity may be the same with a filter such as filter 14 inserted.
  • an electrostatic latent image corresponding to the magenta image portion on the main photosensitive layer may be made as follows (where the main photosensitive layer is panchromatically sensitized):
  • an ultra-violet filter in an appropriate position between the light source 11 and the transparent photosensitive element 13.
  • the main photosensitive layer 1 is exposed to light through the transparent photosensitive element 13 and the filter 14 (which is a green filter and only transmits green light).
  • an electrostatic latent image corresponding to green light that is, the magenta portion of the image is formed.
  • While on the transparent photosensitive layer 4 which is red-sensitive an electrostatic latent image corresponding to red light, that is, the cyan portion of the image is formed.
  • FIG. 2 is a representation of the relative positions of the elements during development.
  • the main photosensitive element and the transparent photosensitive element are secured with a small space therebetween (to insure no movement) in a facing relationship as during exposure.
  • 3 represents the electrostatic latent image on the main photosensitive layer
  • 6 represents the electrostatic latent image on the transparent photosensitive layer.
  • the electrostatic latent image 3 (for example, having a negative polarity) on the main photosensitive layer is developed with a positively charged magenta toner.
  • the coloring agent adheres well to the edge portion of electrostatic latent image 3 on the main photosensitive layer 1 which does not face the electrostatic latent image 6 on the transparent photosensitive layer as can be seen in FIG. 2.
  • the latent image 6 corresponds to the cyan portion of the original and on the highly charged portion of the main photosensitive element a large amount of magenta toner is deposited.
  • the magenta toner is deposited corresponding to the charge, that is, the latent image.
  • the amount of toner deposited is influenced by the charge on the transparent photosensitive layer (that is, latent image 6). Therefore, the amount of toner deposited on the portion which faces the highly charged portion of the latent image 6 is decreased.
  • the magenta image density thus decreased is compensated by the magenta absorption portion of the cyan toner image which normally is an unwanted absorption.
  • the above process is carried out in cyan, magenta and yellow colors.
  • the main photosensitive layer must be panchromatically sensitized.
  • the toner image on the main photosensitive layer is obtained by correcting the inaccurate absorption of individual toner image for other colors.
  • the electrostatic latent image of the transparent photosensitive layer and the main photosensitive layer should be developed with no movement in their positions while they are facced but since exposure is carried out with one above another, registration is very easy.
  • the photosensitive elements may be fixed relative to each other at one end, or may have a stick inserted into holes at one corner, etc.
  • the two electrostatic latent images are easily formed by a one time exposure.
  • the electrostatic latent images on the transparent photosensitive element and the main photosensitive element are in a mutual image relationship because the former is exposed from the support mirror side and the latter from the photosensitive layer side.
  • the present invention thus finds excellent application to obtaining electrostatic latent images in a mirror image relation by a one time exposure.
  • Plastic films having a conductive surface layer such as vacuum vaporized metal
  • Plastic films having applied thereto organic materials e.g., potassium polybenzene sulphonate so as, to be conductive.
  • any photoconductive material may be used, for example, the following materials can be used:
  • Photoconductive zinc oxide which is spectrally sensitized by a coloring material, applied on the support in a polymeric binder, e.g., a styrenated alkyd resin, to provide a 5-30 micron dry thickness.
  • a polymeric binder e.g., a styrenated alkyd resin
  • Photoconductive CdS powder which is spectrally sensitized by a coloring material absorptive in the red, green and blue regions, applied as in 1 above with a binder.
  • An organic photoconductive body such as polyvinyl carbazole which is spectrally sensitized by a coloring material, applied on the support with a plasticizer.
  • the following may be used:
  • the transparent photosensitive part need not neces sarily be completely transparent, and may be translucent with little absorption or diffusion of light because the main photosensitive part is exposed through the transparent photosensitive element.
  • An organic photoconductive body such as polyvinyl carbazole which is dye-sensitized.
  • the toner image is preferably transferred onto an appropriate material such as paper, so that the colored image is obtained by repetitively transferring the different color images on the same material in position registration,
  • main photosensitive layers which are respectively sensitive to only blue, green and red can be used in each transfer process.
  • the filter 14 is not necessary, since the spectral sensitivity of the main photoconductive layer is only blue, green or red.
  • two photoconductive layers can directly each other, but in order to prevent undesirable discharging it is preferable to insert a transparent insulative material, that is, a plastic film between these two photoconductive layers.
  • the first toner image should not influence the electrophotography process occurring during the formation of the second color toner image.
  • the liquid developing process using fine toner dispersed in an insulating liquid as the developer is especially suitable in this situation.
  • the present invention is also available for obtaining a separated positive separation or negative separation with color masking for printing instead of a colored image by applying toner image in an electrophotography process. In the instance, there is no need to change the color of the toner to each color with multiple applications.
  • the exposure and development of the present invention are made one time with each color, and the color masked separated positives or negatives are obtained which can be used in photoengraving.
  • the foregoing description applies only to ordinary color separation color reproduction.
  • the color of filter 14 shown in FIG. I, or the spectral sensitivity of the main photosensitive layer combined with the filter 14, or the spectral sensitivity of the main photosensitive layer without the use of filter H can be used to obtain special effects to extend over two colors or to select the middle color, without being limited to red, green and blue.
  • the spectral sensitivity of the transparent photosensitive layer may also be varied in the same manner.
  • the present invention is available for obtaining images by a positive positive or negative negative process as well as by a negative positive process.
  • the developing electrode is given a bias voltage of the same polarity as that of the charge of the electrostatic 6 latent image and developing is made with a charged toner of the same polarity.
  • the present invention can employ a transparent photosensitive element wherein the charge thereon acts as a biasing voltage instead of a developing electrode to which is applied a biasing voltage.
  • toners deposit on the portion where less charge is present on the main photoconductive element.
  • magenta toner is deposited but reduced.
  • An electrophotographic process including a color masking operation comprising providing a photoconductive insulator as a main photosensitive element and a substantially transparent photoconductive insulator as a transparent photosensitive element, where said main photosensitive element is provided with a grounded conductive support and said transparent photosensitive element is provided with a transparent grounded conductive support and where the spectrum sensitivity region of said transparent photosensitive element is different from the spectrum sensitivity region of said main photosensitive element or said main photosensitive element combined with a colored filter, charging both photosensitive elements with the same polarity, facing the charged surfaces of both said photosensitive elements toward each other so that a slight gap exists therebetween (l) with said colored filter interposed and/or a substantially transparent insulator interposed, or (2) with nothing interposed, image exposing while both said photosensitive elements are held in registry from the side of said transparent photosensitive element to obtain the electrostatic latent images of reflected image relation on said main photosensitive element and said transparent photosensitive element, and developing the latent image on said main photosensitive element while maintaining said registry between both said photosensitive elements, the amount

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Color Electrophotography (AREA)
  • Photoreceptors In Electrophotography (AREA)
  • Electrophotography Using Other Than Carlson'S Method (AREA)
  • Combination Of More Than One Step In Electrophotography (AREA)
US00213136A 1970-12-28 1971-12-28 Electrophotographic process including a color masking operation Expired - Lifetime US3844783A (en)

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JP45120544A JPS503649B1 (de) 1970-12-28 1970-12-28

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JP (1) JPS503649B1 (de)
DE (1) DE2163903A1 (de)
GB (1) GB1374619A (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4188213A (en) * 1973-12-03 1980-02-12 Xerox Corporation Color corrected printing system
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
US4518246A (en) * 1983-05-12 1985-05-21 Eastman Kodak Company Apparatus and method for forming multicolor electrophotographic images

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4006983A (en) * 1973-10-29 1977-02-08 Electroprint, Inc. Electrostatic color printing systems using modulated ion streams
JPS5926957B2 (ja) * 1973-12-28 1984-07-02 キヤノン株式会社 カラ−電子写真方法

Citations (9)

* 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
US2962375A (en) * 1956-05-02 1960-11-29 Haloid Xerox Inc Color xerography
US2962374A (en) * 1956-05-01 1960-11-29 Haloid Xerox Inc Color xerography
US2986466A (en) * 1955-12-06 1961-05-30 Edward K Kaprelian Color electrophotography
US3043686A (en) * 1958-07-08 1962-07-10 Xerox Corp Xerographic color masking
US3057720A (en) * 1959-05-04 1962-10-09 Xerox Corp Xerographic color reproduction
NL6812120A (de) * 1967-05-22 1970-03-02
US3620798A (en) * 1967-01-18 1971-11-16 Fuji Photo Film Co Ltd Development of latent electrostatic image employing novel development electrode
US3687661A (en) * 1969-12-01 1972-08-29 Xerox Corp Color electrophotographic process

Patent Citations (10)

* 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
US2986466A (en) * 1955-12-06 1961-05-30 Edward K Kaprelian Color electrophotography
US2962374A (en) * 1956-05-01 1960-11-29 Haloid Xerox Inc Color xerography
US2962375A (en) * 1956-05-02 1960-11-29 Haloid Xerox Inc Color xerography
US3043686A (en) * 1958-07-08 1962-07-10 Xerox Corp Xerographic color masking
US3057720A (en) * 1959-05-04 1962-10-09 Xerox Corp Xerographic color reproduction
US3620798A (en) * 1967-01-18 1971-11-16 Fuji Photo Film Co Ltd Development of latent electrostatic image employing novel development electrode
NL6812120A (de) * 1967-05-22 1970-03-02
US3615391A (en) * 1967-05-22 1971-10-26 Fuji Photo Film Co Ltd Electrophotographic color developing method
US3687661A (en) * 1969-12-01 1972-08-29 Xerox Corp Color electrophotographic process

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4188213A (en) * 1973-12-03 1980-02-12 Xerox Corporation Color corrected printing system
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
US4518246A (en) * 1983-05-12 1985-05-21 Eastman Kodak Company Apparatus and method for forming multicolor electrophotographic images

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Publication number Publication date
GB1374619A (en) 1974-11-20
DE2163903A1 (de) 1972-07-27
JPS503649B1 (de) 1975-02-07

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