US3892480A - Exposure device for copying machine and the like - Google Patents

Exposure device for copying machine and the like Download PDF

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Publication number
US3892480A
US3892480A US417719A US41771973A US3892480A US 3892480 A US3892480 A US 3892480A US 417719 A US417719 A US 417719A US 41771973 A US41771973 A US 41771973A US 3892480 A US3892480 A US 3892480A
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US
United States
Prior art keywords
size
original
light source
plate
photosensitive layer
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
US417719A
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English (en)
Inventor
Ryuzo Okada
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.)
Fujifilm Business Innovation Corp
Original Assignee
Fuji Xerox Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Fuji Xerox Co Ltd filed Critical Fuji Xerox Co Ltd
Application granted granted Critical
Publication of US3892480A publication Critical patent/US3892480A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • G03G2215/0434—Parameters defining the non-image area to be cleaned
    • G03G2215/0436—Document properties at the scanning position, e.g. position and density
    • 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
    • G03G2215/0434—Parameters defining the non-image area to be cleaned
    • G03G2215/0446—Magnification degree
    • 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
    • G03G2215/0463—Exposure lamp used for scanning

Definitions

  • ABSTRACT In an electrostatic copying machine where an original of a first size positioned on a transparent platen is illuminated by a light source and the image thereof is reflected onto a uniformly charged photosensitive layer to form a latent electrostatic image on the photosensitive layer, which is subsequently toner developed, the improvement of preventing toner deposition at a predetermined marginal area of the photosensitive layer when an original of a second size smaller than the first size is copied by the machine, the predetermined marginal area corresponding to the excess area of the first size original with respect to the second size original, the improvement comprising means for reducing the area illuminated by the light source to an area substantially the same as that of the second size original and for exposing the predetermined marginal area of the photosensitive layer in the same manner as the non-image areas of the latent electrostatic image so that when the image is toner developed, toner will deposit only on the image areas.
  • This invention relates to an exposure device for a copying machine or the like, and more particularly, to an exposure device for an electrostatic copying machine employing a reflection exposure system in which an original is placed on an original holder made of transparent glass or the like (hereinafter referred to as platen), and the original is scanned by a movable light source.
  • an electrostatic copying machine comprises a drum-shaped photosensitive material comprising a photoconductive material coated on a metal, a charging device for charging the photosensitive mate rial, an exposure device for imagewise discharging the surface of the charged photosensitive material, a development device for developing the charged image by use of a developer containing a resin powder (hereinafter referred to as toner") attracted by the electrostatic force of the image, a transfer device for transferring the toner image formed on the photosensitive material to an image receiver such as paper, a fixing device for fix ing the toner image on the image receiver, and a clean' ing device for cleaning the toner remaining on the photosensitive material being not transferred and so forth.
  • toner a developer containing a resin powder
  • the portion outside the original does not reflect light from the exposure lamp and thus this light is not projected onto the photosensitive materiai 3 and accordingly the charges 4 existing in the area on the photosensitive material corresponding to the area outside the original are not discharged.
  • the toner also deposits onto the latter area at development station 5. This effect is quite prominent in copying machines which employ the improved development system in which half tones of photographs and solid parts of such photographic images are faithfully developed. Consequently, when the image receiver or transfer sheet is larger than the original, the marginal portion of the image receiver is blackened with toner that is, a black framed copy 6 is obtained.
  • the toner 7 in the area corresponding to the area outside the original is not transferred to the image receiver and undersirable phenomena occur in the copying machine. That is, for example, the amount of toner consumption increases, the load on the cleaning device 8 increases, and machine contamination increases.
  • the present invention has been made in view of the above-described problems and a primary object thereof is to provide an improved exposure device for a copying machine or the like in which the exposure area is limited to a predetermined size when an original having a smaller size than the maximum effective area of the platen is used and light outside the limited, predetermined area is reflected onto the photosensitive material or the like.
  • FIG. 1 is a perspective view of an illustrative prior art copying machine.
  • FIG. 2 is a perspective view partly cut away of an illustrative embodiment of the present invention.
  • FIG. 3 is a cross-sectional view along the line IIIIII of FIG. 2.
  • FIG. 4 is a cross-sectional view for explaining the operation of the invention when an A4 size original is replaced by a B4 size original DESCRIPTION OF PREFERRED EMBODIMENT
  • the present invention will be described in detail with reference to an illustrative embodiment thereof shown in FIGS. 2 and 4.
  • a transparent platen 10 is supported on a frame base (not shown) and on the platen 10 is placed an original 12 of size A4 (letter size).
  • the maximum effective area of the platen 10 is typically the area of B4 size (legal size) and is indicated by phantom line 14.
  • the area outside phantom line I4 is generally covered with a panel, which is omitted in the drawing for purposes of clarity.
  • a lamp housing 20 including two parallel lamps 21 moves adjacent the lower surface of the platen 20 along a pair of guide rails 22, 22 as is known.
  • a horizontally extending, reflecting plate 18 is vertically movably mounted in retaining chambers 22a, 22a formed by bent projected portions 24, 24 of the pair of guide rails 22, 22.
  • a cutaway portion 18a having the same width as that of the A4 size papers, and at the lower face thereof projects an engaging member 19, which removably engages a vertical wall 200 of the lamp housing 20.
  • a solenoid I6 is provided on a framework (not shown) of the machine and a plunger 16a thereof is located in contact with the lower surface of reflecting plate 18 and upwardly biases the plate 18 in retaining chamber 220.
  • Control of solenoid 16 may be effected by operation of appropriate selection switch buttons (not shown) provided on the exterior of the machine or it is possible to automatically retract the plunger of the solenoid l6 whenever an A4 size copying paper is placed on the copying machine, this being effected by automatic detecting means such as a photocell detector.
  • said light source comprises at least one elongated tube movably mounted with respect to said transparent platen for scanning an original, the opening in said plate being such that when said plate is interposed between said elongated tube and said platen, both ends of said tube are covered thereby reducing the area illuminated by said tube to approximately that of said second size original.
  • a positive copy is obtained from a positive original and said improvement comprises a light reflecting plate movably mounted with respect to said light source, said reflecting plate including an opening therein and means for moving said reflecting plate to (l) a first position interposed between said light source and said transparent platen when said second size original is copied and (2) to a second position not interposed between said light source and said transparent platen when said first size original is copied, the size of the opening in said reflecting plate being such that it reduces the area illuminated by said light source to substantially that of said second size original, the remaining light from said light source being reflected by said reflecting plate onto said photosensitive layer to discharge the charge at said predetermined marginal area and thereby prevent toner deposition thereat, said toner being charged to a polarity opposite to that of the charge on said photosensitive layer.
  • a positive copy is obtained from a negative original and said improvement comprises a light absorbing plate movably mounted with respect to said light source, said absorbing plate including an opening therein and means for moving said absorbing plate to (l) a first position interposed between said light source and said transparent platen when said second size original is copied and (I) to a second position not interposed between said light source and said transparent platen when said first size original is copied, the size of the opening in said reflecting plate being such that it reduces the area illumlncted by said light source to substantially that of said second size original, the remaining light from said light source being absorbed by said absorbing plate to prevent the discharge of charge at said predetermined marginal area of the photosensitive layer and thereby prevent toner deposition thereat, said toner being charged to the same polarity as of the charge on said photosensitive layer.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Exposure Or Original Feeding In Electrophotography (AREA)
  • Holders For Sensitive Materials And Originals (AREA)
  • Optical Systems Of Projection Type Copiers (AREA)
  • Light Sources And Details Of Projection-Printing Devices (AREA)
US417719A 1972-12-27 1973-11-21 Exposure device for copying machine and the like Expired - Lifetime US3892480A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP1972148094U JPS5232198Y2 (enrdf_load_stackoverflow) 1972-12-27 1972-12-27

Publications (1)

Publication Number Publication Date
US3892480A true US3892480A (en) 1975-07-01

Family

ID=15445093

Family Applications (1)

Application Number Title Priority Date Filing Date
US417719A Expired - Lifetime US3892480A (en) 1972-12-27 1973-11-21 Exposure device for copying machine and the like

Country Status (4)

Country Link
US (1) US3892480A (enrdf_load_stackoverflow)
JP (1) JPS5232198Y2 (enrdf_load_stackoverflow)
DE (1) DE2364324B2 (enrdf_load_stackoverflow)
GB (1) GB1446748A (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4101213A (en) * 1975-05-14 1978-07-18 Xerox Corporation Zoom lens copier

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2757850C3 (de) * 1977-12-23 1981-01-29 Agfa-Gevaert Ag, 5090 Leverkusen Transparente Auflageplatte für ein Original in einem optischen Kopiergerät
JPS5494038A (en) * 1978-01-07 1979-07-25 Ricoh Co Ltd Copier for zerography

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2927516A (en) * 1955-12-21 1960-03-08 Ibm Record card controlled electro-graphic printer
US3556655A (en) * 1968-01-22 1971-01-19 Addressograph Multigraph Photoelectrostatic copying machine
US3724940A (en) * 1970-12-07 1973-04-03 Ricoh Kk Electrophotographic copying apparatus with means for erasing marginal images

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2927516A (en) * 1955-12-21 1960-03-08 Ibm Record card controlled electro-graphic printer
US3556655A (en) * 1968-01-22 1971-01-19 Addressograph Multigraph Photoelectrostatic copying machine
US3724940A (en) * 1970-12-07 1973-04-03 Ricoh Kk Electrophotographic copying apparatus with means for erasing marginal images

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4101213A (en) * 1975-05-14 1978-07-18 Xerox Corporation Zoom lens copier

Also Published As

Publication number Publication date
GB1446748A (en) 1976-08-18
DE2364324A1 (de) 1974-07-18
DE2364324B2 (de) 1976-11-18
JPS5232198Y2 (enrdf_load_stackoverflow) 1977-07-22
JPS49106349U (enrdf_load_stackoverflow) 1974-09-11

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