US3799666A - Apparatus for forming white frame in electrophotography - Google Patents

Apparatus for forming white frame in electrophotography Download PDF

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Publication number
US3799666A
US3799666A US00336748A US33674873A US3799666A US 3799666 A US3799666 A US 3799666A US 00336748 A US00336748 A US 00336748A US 33674873 A US33674873 A US 33674873A US 3799666 A US3799666 A US 3799666A
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US
United States
Prior art keywords
light
electrostatic latent
latent image
photoconductive layer
charged photoconductive
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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US00336748A
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English (en)
Inventor
S Matsumoto
M Sato
O Fukushima
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Individual
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Individual
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Filing date
Publication date
Priority claimed from JP45003099A external-priority patent/JPS5018394B1/ja
Priority to FR7100603A priority Critical patent/FR2075386A5/fr
Application filed by Individual filed Critical Individual
Priority to US00336748A priority patent/US3799666A/en
Application granted granted Critical
Publication of US3799666A publication Critical patent/US3799666A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • G03G15/04—Apparatus for electrographic processes using a charge pattern for exposing, i.e. imagewise exposure by optically projecting the original image on a photoconductive recording material
    • G03G15/045—Apparatus for electrographic processes using a charge pattern for exposing, i.e. imagewise exposure by optically projecting the original image on a photoconductive recording material with means for charging or discharging distinct portions of the charge pattern on the recording material, e.g. for contrast enhancement or discharging non-image areas
    • G03G15/047—Apparatus for electrographic processes using a charge pattern for exposing, i.e. imagewise exposure by optically projecting the original image on a photoconductive recording material with means for charging or discharging distinct portions of the charge pattern on the recording material, e.g. for contrast enhancement or discharging non-image areas for discharging non-image areas
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2215/00—Apparatus for electrophotographic processes
    • G03G2215/04—Arrangements for exposing and producing an image
    • G03G2215/0429—Changing or enhancing the image
    • G03G2215/0431—Producing a clean non-image area, i.e. avoiding show-around effects
    • G03G2215/0448—Charge-erasing means for the non-image area

Definitions

  • ABSTRACT Electrophotographic apparatus having an exposure device for producing a white frame border about an electrostatic latent image.
  • the apparatus comprises a plurality of internal channel members surrounding the exposure light source which open downwardly onto the copy sheet.
  • the channel members contain a plurality of light sources for projecting light onto the perimetric vportions of the copy sheet in partially overlapping relation to the electrostatic latent image for completely dissipating the charge about the electrostatic latent image so that no black border appears about the electrostatic latent image after toner development.
  • FIG. 5 FIG. 5
  • This invention relates to a device for forming a white frame having no toner deposited thereon on the perimetric portion bounding the image without exerting any adverse effect upon the image on the sensitive layer.
  • FIG. 1 and FIG. 2 are longitudinally sectioned side views of the devices for working the present invention and FIG. 3 through FIG. 6 are longitudinally sectioned side views of the important parts thereof.
  • the perimetric portion bounding the image plane is covered by the printing frame and therefore is suffered to remain unexposed to light.
  • a developing agent containing a toner charged to the opposite sign to that of the polarity of the electric charge for forming the electrostatic latent image (namely, the polarity of the electric charge to be conferred uniformly) (hereinafter, the treatment will be referred to as attraction development)
  • attraction development since the toner is deposited in proportion to the amount of electric charge remaining on the sensitive layer, the toner is also deposited on the perimetric portion of image and consequently produces color thereon.
  • the perimetric portion of image Since the perimetric portion of image has not undergone discharging at all, it is developed to the highest density in all the area of the sensitive layer, making the reproduced image unsightly. Further, since unnecessary development is effected on the perimetric portion, the toner is wasted heavily. Therefore, the difference in toner density of developing agent becomes large before and after a large number of developments. As a result, there is involved a shortcoming that a heavy change occurs in the density of electrophotographic images as the treatment of development is repeated.
  • This invention relates to a device for forming a white frame having no toner deposited thereon on the perimetric portion bounding the image without exerting any adverse effect upon the image on the sensitive layer. And, this device has overcome those shortcomings mentioned above.
  • FIG. 1 denotes a lightshielding frame having a cross section of the shape of l lwith an opening in the direction of the sensitive layer
  • the photosensitive surface of the sensitive paper 8 is spaced by an opening t from the lower end of the lightshieldi ng frame 1.
  • the transparent original 4 is projected and formed on the sensitive paper 8 by means of the light source for projection 6 and the projection lens system 7 so as to form an electrostatic latent image and, at the same time, the frame-shaped perimetric portion bounding the formed image is exposed to light from the light source 2 held within the light-shielding frame 1 until the electric charge on the sensitive paper 8 in that portion is eliminated completely.
  • the light from the light source 2 within the light-shielding frame 1 falls on the sensitive paper almost at right angles.
  • the portion of light from the light source for porjection which advances diagonally through the opening t at the lower end of the lightshielding frame 1 reaches the frame-shaped portion exposed by means of the light-shielding frame 1.
  • the light for the formation of image has its boundary formed by the outer edge 3l at the lower end of the light-shielding frame 1 and, with respect to the sensitive paper, the boundary is formed at the point 32 below the light-shielding frame 1.
  • the boundary 34 which is formed by the inner edge 33 at the lower end of the light-shielding frame 1 lies inside the image area.
  • the opening t is determined by taking this relationship into account.
  • the value of t is desired to be as small as possible.
  • the opening must be such that the sensitive paper 8, when suffered to rise, will not come into contact with the lower end of the light-shielding frame 1.
  • the opening is desired not to exceed 20 mm.
  • the value of t for which the aforementioned effect can be achieved becomes small according as the board forming the light-shielding frame 1 decreases in thickness.
  • the light source 2 may comprise a number of electric bulbs disposed at suitable intervals, a slender light source like a fluorescent lamp or a light-conducting tube such as of fiber optics.
  • FIG. 2 illustrates a device for providing a fixed magnification, which device has a diffusing plate 9 and a cylindrical lens 10 directly below the light source 2 in the device shown in FIG. 1.
  • This device serves to uniformize the light projected for the formation of white frame and enhance the quantity of light utilized therefor.
  • a light-shielding plate 10 is disposed above the light-shielding frame 1 so as to permit the device to be utilized where not perfectly dark room is available.
  • the interior surface of the light-shielding frame 1 finished with a black delustered paint having high absorbing property, for example.
  • the lower end of the light-shielding frame 1 is desired to be formed with a material having relatively high resistance so that it may not destroy the latent image even when the sensitive paper 8 is suffered to rise from the base and come into contact therewith.
  • FIG. 4 illustrates an example wherein the lower end of the light-shielding frame 1 is cut diagonally along the direction in which the light for the formation of image advances.
  • FIG. 5 and FIG. 6 illustrate examples wherein the light-shielding frame is inclined with reference to the surface of the sensitive paper.
  • this invention covers a method for forming a white frame, whereby the lightshielding frame is placed at a distance from the surface of the sensitive paper so that when the light for projection of the image and the light from the light source within the light-shielding frame are emitted, these lights overlap at the portion where the white frame is formed in the perimetric portion bounding the image area and consequently there is produced a clear white frame.
  • An electrophotographic apparatus comprising: means for projecting a light image from an original sheet onto a copy sheet having an uniformly electrically charged photoconductive layer to form an electrostatic latent image thereon; means for fixedly supporting a copy sheet having an uniformly electrically charged photoconductive layer to form an electrostatic latent image thereon; means for fixedly supporting a copy sheet having an uniformly electrically charged photoconductive layer in a fixed position in alignment with said projection means during formation of the electrostatic latent image; and exposure means for forming a white frame border about the electrostatic latent image, said exposure means comprising frame forming means adjacent said projection means for projecting light onto a perimetric portion of the charged photoconductive layer in partially overlapping relation to the electrostatic latent image while the copy sheet remains at said fixed position for completely dissipating the charge about the electrostatic latent image so that no black border appears about the electrostatic latent image after the image is toner developed.
  • said frame forming means comprises a plurality of internal channel members opening downwardly onto the charged photoconductive layer, said channel members surrounding said projection means with the opening thereof disposed adjacent portions of the charged photoconductive layer and a plurality of light sources respectively disposed within said channel members.
  • each said channel member includes means for directing the light therefrom substantially perpendicularly onto the charged photoconductive layer.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Exposure Or Original Feeding In Electrophotography (AREA)
US00336748A 1970-01-10 1973-02-28 Apparatus for forming white frame in electrophotography Expired - Lifetime US3799666A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
FR7100603A FR2075386A5 (enrdf_load_stackoverflow) 1970-01-10 1971-01-11
US00336748A US3799666A (en) 1970-01-10 1973-02-28 Apparatus for forming white frame in electrophotography

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP45003099A JPS5018394B1 (enrdf_load_stackoverflow) 1970-01-10 1970-01-10
US00336748A US3799666A (en) 1970-01-10 1973-02-28 Apparatus for forming white frame in electrophotography

Publications (1)

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US3799666A true US3799666A (en) 1974-03-26

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US00336748A Expired - Lifetime US3799666A (en) 1970-01-10 1973-02-28 Apparatus for forming white frame in electrophotography

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US (1) US3799666A (enrdf_load_stackoverflow)
FR (1) FR2075386A5 (enrdf_load_stackoverflow)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3972613A (en) * 1975-04-23 1976-08-03 Scott Paper Company Copyboard
US4008954A (en) * 1974-07-15 1977-02-22 Minolta Camera Kabushiki Kaisha Device for extinguishing unnecessary electrostatic charge in electrophotographic copier
US4415261A (en) * 1980-09-26 1983-11-15 Konishiroku Photo Industry Co., Ltd. An improved platen cover for a copying machine
US4576464A (en) * 1983-12-28 1986-03-18 Mita Industrial Co., Ltd. Charge eliminating lamp device
EP0178021A1 (en) * 1984-10-10 1986-04-16 Océ-Nederland B.V. A device for exposing an edge zone of a photoconductive element to light
US4585330A (en) * 1982-12-03 1986-04-29 Sharp Kabushiki Kaisha Unnecessary charge removing device from a latent image bearing element of electrophotographic copying machine
US4712905A (en) * 1984-10-15 1987-12-15 Fuji Photo Film Co., Ltd. Method of preventing the occurrence of blackened margins on photosensitive sheets in electrophotography
US5359389A (en) * 1991-03-13 1994-10-25 Canon Kabushiki Kaisha Exposure apparatus including two illuminating systems and exposure process using the same
US5668624A (en) * 1993-12-22 1997-09-16 Nikon Corporation Scan type exposure apparatus

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3556655A (en) * 1968-01-22 1971-01-19 Addressograph Multigraph Photoelectrostatic copying machine
US3671121A (en) * 1970-08-05 1972-06-20 Eastman Kodak Co Exposure device for controlling charge on a portion of a charged surface bordering an image frame projected on the charged surface

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3556655A (en) * 1968-01-22 1971-01-19 Addressograph Multigraph Photoelectrostatic copying machine
US3671121A (en) * 1970-08-05 1972-06-20 Eastman Kodak Co Exposure device for controlling charge on a portion of a charged surface bordering an image frame projected on the charged surface

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4008954A (en) * 1974-07-15 1977-02-22 Minolta Camera Kabushiki Kaisha Device for extinguishing unnecessary electrostatic charge in electrophotographic copier
US3972613A (en) * 1975-04-23 1976-08-03 Scott Paper Company Copyboard
US4415261A (en) * 1980-09-26 1983-11-15 Konishiroku Photo Industry Co., Ltd. An improved platen cover for a copying machine
US4585330A (en) * 1982-12-03 1986-04-29 Sharp Kabushiki Kaisha Unnecessary charge removing device from a latent image bearing element of electrophotographic copying machine
US4576464A (en) * 1983-12-28 1986-03-18 Mita Industrial Co., Ltd. Charge eliminating lamp device
EP0178021A1 (en) * 1984-10-10 1986-04-16 Océ-Nederland B.V. A device for exposing an edge zone of a photoconductive element to light
US4648703A (en) * 1984-10-10 1987-03-10 Oce-Nederland B.V. Device for exposing an edge zone of a photoconductive element to light
US4712905A (en) * 1984-10-15 1987-12-15 Fuji Photo Film Co., Ltd. Method of preventing the occurrence of blackened margins on photosensitive sheets in electrophotography
US5359389A (en) * 1991-03-13 1994-10-25 Canon Kabushiki Kaisha Exposure apparatus including two illuminating systems and exposure process using the same
US5668624A (en) * 1993-12-22 1997-09-16 Nikon Corporation Scan type exposure apparatus

Also Published As

Publication number Publication date
FR2075386A5 (enrdf_load_stackoverflow) 1971-10-08

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