US3551145A - Method of reproducing a toner image carried by an electrophotographic plate - Google Patents

Method of reproducing a toner image carried by an electrophotographic plate Download PDF

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Publication number
US3551145A
US3551145A US662049A US3551145DA US3551145A US 3551145 A US3551145 A US 3551145A US 662049 A US662049 A US 662049A US 3551145D A US3551145D A US 3551145DA US 3551145 A US3551145 A US 3551145A
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United States
Prior art keywords
image
photoconductive
layer
plate
xerographic
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
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US662049A
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English (en)
Inventor
William Trachtenberg
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.)
Eastman Kodak Co
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Eastman Kodak Co
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Filing date
Publication date
Application filed by Eastman Kodak Co filed Critical Eastman Kodak Co
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Publication of US3551145A publication Critical patent/US3551145A/en
Anticipated expiration legal-status Critical
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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
    • G03G15/22—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20
    • G03G15/225—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 using contact-printing
    • 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
    • G03G13/22—Processes involving a combination of more than one step according to groups G03G13/02 - G03G13/20
    • 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

  • a uniform electrostatic charge of the same polarity is applied to a surface of the photoconductive layer carrying the image and to the photoconductive layer of the unexposed xerographic plate before the charge surfaces are positioned in intimate contact for exposure through the image-carrying xerographic plate.
  • This invention relates to electrophotographic reproduction and more particularly to an improved method for reproducing a fully developed image, which is carried by a xerographic plate, as a latent electrostatic image on another Xerographic plate whereby there is little, if any, loss of image sharpness or resolution.
  • an electrostatic image is formed on a xerographic plate by conventional methods and a charged dielectric film with a conductive base is placed on top of the electrostatic image on the plate surface. Both electrodes are then brought to ground potential and since the potential difference between the conductive substrates is zero, the voltage across the air gap in the image area is determined by the combined potentials of the positively charged image and the negatively charged dielectric. The surfaces are then separated and the image transfer takes place during separation. In this process it is noted that the provision is made to bring both electrodes to ground potential so that no secondary discharge effect occurs between the surfaces upon separation.
  • One object of the invention is to provide an improved electrophotographic reproduction system in which a visible image on a xerographic plate can be reproduced or duplicated on another xerographic plate.
  • Another object of the invention is to provide an im proved electrophotographic reproduction method by which secondary discharge effects between the contacting surfaces of two insulating materials are substantially eliminated upon separation of the surfaces.
  • Yet another object of the invention is to provide an improved electrophotographic reproduction method by which surface discharge patterns are eliminated from the surface of a photoconductive insulating material bearing a latent electrostatic image.
  • a uniform electrostatic charge is applied to a surface of the photoconductive layer of the xerographic plate.
  • a uniform electrostatic charge of the same polarity and potential is also applied to the photoconductive surface of the second xerographic plate.
  • the charged surfaces (original and copy) are then positioned in intimate contact and the photoconductive layer of the second xerographic plate is exposed through the xerographic plate (original) to a source of uniform actinic illumination.
  • the charges in the light or transparent area's are substantially neutralized and the charges remain in the dark or unexposed areas, the latter being the toned areas on the original xerographic plate.
  • the potential gradient between the facing surfaces in both the image and non-image areas is reduced to a level of potential such that no dielectric breakdown of air can occur upon separation of the facing surfaces of the original and copy.
  • the second xerographic plate is then separated from the first xerographic plate and the electrostatic image thereon is then developed by any known xerographic method. Since the electrostatic image is formed on the surface that is in contact with, or in close proximity to, the duplicated image, it is identical to the original image with little, if any. loss in sharpness or resolution.
  • FIG. 1 is a schematic representation of two xerographic plates having the photoconductive layers in close proximity and showing the manner in which discharge patterns are formed;
  • FIG. 2 is a schematic representation similar to that shown in FIG. 1 showing the manner in which discharge patterns are formed when the conductive backing support of one of the xerographic plates is connected to ground;
  • FIG. 3 is a schematic representation similar to that shown in FIG. 1 showing the manner in which the field lines are formed when a bias voltage is applied to the conductive hacking support of one of the xerographic plates without exposure to subsequent illumination;
  • FIG. 4 is a schematic representation similar to that shown in FIG. 1 in which the photoconductive layer of each xerographic plate is charged to the same polarity and to substantially the same level of potential and showing that no external fields exist to form any discharge pattern;
  • FIGS. and 6 are schematic representations of a xerographic plate havin a fully developed and visual image thereon and a xerographic plate for receiving a duplicate image, FIG. 5 showing the charge formation prior to illumination and FIG. 6 showing the charge configuration relative to the image after illumination; and
  • FIG. 7 is a schematic arrangement of an apparatus for practicing the invention as a continuous method.
  • a xerographic plate 10 comprises a photoconductive insulating layer 11 overlying a conductive backing support 12.
  • a second xerographic plate 13 comprises a photoconductive layer 14 and a conductive backing support 15.
  • the surface of layer 14 was first charged negatively to a potential of 1000 volts.
  • the plate 13 was then placed with its photoconductive layer 14 in contact with the photoconductive insulating layer 11 of plate 10.
  • the conductive backing support of each plate was allowed to float, that is, was not intentionally grounded, and there was no exposure step. Since the support 12 is conductive, it contains both positive and negative charges that may move about freely. When the charged surface of layer 14 is brought into contact with layer 11, some of the positive charges in layer 12 will be drawn by the induced electrical field toward negative charges on layer 14.
  • a xerographic plate 20 comprising a conductive backing support 21 and a photoconductive layer 22 had its conductive support 21 connected to ground.
  • a second xerographic plate 23 comprises a conductive backing support 24 and a photoconductive layer 25. The surface of layer 25 was charged negatively to a potential of 1000 volts and then placed in contact with the surface of layer 22. Upon separation and development of each of plates 20 and 23, discharge patterns were again evident on each of the surfaces of layers 22. and 25.
  • the arrows 26 indicate the electrical field existing between the photoconductive layers 22, 25 and in which areas secondary discharge effects occur due to the induced charges. In this case, however, the negative charges in layer 21 leak off because the layer 21 is connected to ground.
  • a xerographic plate 30 comprising a photoconductive layer 31 overlying a conductive backing support 32 had a negative bias of 1000 v. connected to the conductive support 32.
  • a xerographic plate 33 comprises a conductive backing support 34 and a photoconductive layer 35. The surface of layer 35 was charged negatively to 1000 v. and the photoconductive layer 35 was then placed in contact with the layer 31 of xerographic plate 30. Upon separation and subsequent development of the plates 30 and 33 no discharge patterns were observed on the surfaces of layers 31 and 35. In this example it is believed that biasing the plate 30 to a potential of the same polarity as that of the plate 33, in effect, neutralizes any electrical field that may exist between photoconductive layers 31, 35 so that the plates can be separated without any transfer of charge or secondary discharge effects. However, even with the application of a bias to support 32, secondary discharge effects are obtained upon subsequent illumination through support 32 and separation of layers 31, 35.
  • a xerographic plate 40 comprising a conductive backing support 41 and a photoconductive layer 42 and a xerographic plate 43 comprising a conductive backing support 44 and a photoconductive layer 45 were charged in the same manner as the previous examples to the same negative voltage (1000 volts).
  • the plates 40 and 43 were then placed photoconductive layer to photoconductive layer in accordance with the present invention. After separation, each plate was developed and no discharge patterns were evident on either plate.
  • the plate 43 was charged to a negative 500 volts surface potential and the plate 40 was charged to a negative 1000 volts surface potential and then positioned in the same relationship as described above, the developed images showed some secondary discharge effects which were less than with no charging of the layer 42, but more than with equal charging.
  • FIGS. 5 and 6 disclose the invention as practiced with substantially no secondary discharge effects.
  • An original or xerographic plate 50 comprising a photoconductive layer 51 overlying a backing support 52 carries a toned image '53.
  • the toned image 53 is one which has been formed by well known xerographic methods and is therefore a fully visible imageQA copy material 54 can comprise a xerographic plate with a photoconductive layer 55 overlying a conductive backing support 56.
  • the photoconductive layers 51 and 55 were charged negatively to a surface potential 1000 v. and then placed in intimate contact.
  • the conductive support 52 must be transparent in order to permit uniform illumination through the original 50.
  • the illumination therefore is through the original and the light incident on the photoconductive surface 55 renders the exposed areas conductive so that the charges in these areas are substantially neutralized. Since the toned image 53 prevents light from reaching the corresponding areas of the surface of layer 55 the charge remains in the image areas. Upon separation, electric fields exist only in the image areas and are not sufficient to cause dielectric breakdown when the plates 50 and 54 are separated one from the other.
  • the latent electrostatic image on the original that is, on the surface of the toner, is formed because of the toner thickness, and under proper charging conditions the two latent electrostatic images can be identical.
  • the extent to which the original and photoconductive copy material should be charged is a function of the relative dielectric constants, the thickness of the toner deposit on the original and the thickness of the photoconductive layers, the secondary discharge effects being caused by the capacitive arrange ment of the photoconductive layers, the air gap and the conductive backing supports.
  • the original material 70 is shown as a web comprising a xerographic material which would contain a number of longitudinally spaced visible images.
  • the copy material 71 is a xerographic material having a photoconductive layer overlying a conductive support as described above. The two materials are brought together at a point determined by a pair of rolls 72, 73 which are connected to ground. The image surface on the original is positioned so as to be brought into contact with the photoconductive layer of the copy material.
  • a corona charging means 74 is arranged between the copy and original material and connected to a DC. source of potential 75.
  • the source can provide either positive or negative potential to the corona wire 76 which charges the materials with either a or charge in accordance with the requirement.
  • Either one or a pair of spaced corona shields 77 which are connected to ground can be used to direct the spray of ions to the surfaces of the original and copy materials.
  • the copy material is subjected to uniform actinic illumination by means of a lamp 80 and a condenser lens system 81.
  • the copy material 71 and original 70 are separated at rolls 78, 79, the original being taken up in the form of a roll 82 and the copy material being moved through a developing means 83, a fusing means 84 and then wound up on roll 85.
  • the image in the copy material 71 after being developed, can be transferred to another material in a known manner to provide a paper copy, in which case the copy material 71 would then be wound onto roll 85 and the transfer material would be moved into and through the fusing station 84.
  • the original material 70 is a xerographic material bearing visual images, it must be provided with a transparent conductive backing support in order to permit illumination through the material to provide the necessary neutralization of the charge in the non-image areas.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photoreceptors In Electrophotography (AREA)
  • Electrophotography Using Other Than Carlson'S Method (AREA)
US662049A 1967-08-21 1967-08-21 Method of reproducing a toner image carried by an electrophotographic plate Expired - Lifetime US3551145A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US66204967A 1967-08-21 1967-08-21

Publications (1)

Publication Number Publication Date
US3551145A true US3551145A (en) 1970-12-29

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Family Applications (1)

Application Number Title Priority Date Filing Date
US662049A Expired - Lifetime US3551145A (en) 1967-08-21 1967-08-21 Method of reproducing a toner image carried by an electrophotographic plate

Country Status (6)

Country Link
US (1) US3551145A (fr)
BE (1) BE719702A (fr)
CH (1) CH489043A (fr)
DE (1) DE1797130A1 (fr)
FR (1) FR1577666A (fr)
GB (1) GB1221453A (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS48104539A (fr) * 1972-04-13 1973-12-27
US3963487A (en) * 1970-12-14 1976-06-15 Fuji Photo Film Co., Ltd. Electrophotographic process using separate photoconductive elements
JPS5358248A (en) * 1976-11-08 1978-05-26 Gakken Co Ltd Device for forming image on transparent sheet

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3963487A (en) * 1970-12-14 1976-06-15 Fuji Photo Film Co., Ltd. Electrophotographic process using separate photoconductive elements
JPS48104539A (fr) * 1972-04-13 1973-12-27
JPS5358248A (en) * 1976-11-08 1978-05-26 Gakken Co Ltd Device for forming image on transparent sheet

Also Published As

Publication number Publication date
FR1577666A (fr) 1969-08-08
GB1221453A (en) 1971-02-03
CH489043A (fr) 1970-04-15
BE719702A (fr) 1968-10-31
DE1797130A1 (de) 1971-04-01

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