EP0147206A2 - Skorotron mit verteilter Koronawicklung - Google Patents

Skorotron mit verteilter Koronawicklung Download PDF

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Publication number
EP0147206A2
EP0147206A2 EP84309000A EP84309000A EP0147206A2 EP 0147206 A2 EP0147206 A2 EP 0147206A2 EP 84309000 A EP84309000 A EP 84309000A EP 84309000 A EP84309000 A EP 84309000A EP 0147206 A2 EP0147206 A2 EP 0147206A2
Authority
EP
European Patent Office
Prior art keywords
corona
charging device
photoconductive surface
wire
emitting means
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.)
Withdrawn
Application number
EP84309000A
Other languages
English (en)
French (fr)
Other versions
EP0147206A3 (de
Inventor
Robert William Gundlach
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.)
Xerox Corp
Original Assignee
Xerox Corp
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 Xerox Corp filed Critical Xerox Corp
Publication of EP0147206A2 publication Critical patent/EP0147206A2/de
Publication of EP0147206A3 publication Critical patent/EP0147206A3/de
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T19/00—Devices providing for corona discharge
    • 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
    • G03G15/02—Apparatus for electrographic processes using a charge pattern for laying down a uniform charge, e.g. for sensitising; Corona discharge devices
    • G03G15/0291—Apparatus for electrographic processes using a charge pattern for laying down a uniform charge, e.g. for sensitising; Corona discharge devices corona discharge devices, e.g. wires, pointed electrodes, means for cleaning the corona discharge device

Definitions

  • This invention relates to a compact corona device for charging a surface uniformly with either positive or negative ions.
  • Corona charging xerographic photoconductors has been disclosed in U.S. Patent 2,588,699. It has always been a problem that current levels for practical charging require coronode potentials of many thousands of volts, while photoconductors typically cannot support more than 1000 volts surface potential without dielectric breakdown.
  • a compact scorotron charging device for uniformly charging a photoconductive surface (16), comprising:
  • This invention enables more uniform charging of photoconductors at high speeds and with greater stability, lower manufacturing costs and service and less sensitivity to wire sagging, vibration and arcing. This also provides greater latitude in tensioning the coronode wire and provides a means of making scorotrons of indefinite length.
  • the scorotron may employ a helically wound coronode wire that is supported by an insulating support to provide free standing segments.
  • FIG. 1 depicts schematically the various components thereof.
  • like reference numerals will be employed throughout to designate identical elements.
  • the apparatus of the present invention is disclosed as a means for charging a photosensitive member, it should be understood that the invention could be used in an electrophotographic environment as a pre-cleaning, transfer or detack device, or in any apparatus where uniform surface potential is desired or required.
  • a drum 15 having a photoconductive surface 16 entrained about and secured to the exterior circumferential surface of a conductive substrate is rotated in the direction of arrow 12 through the various processing stations.
  • photoconductive surface 16 may be made from selenium of the type described in U.S. Patent 2,970,906.
  • a suitable conductive substrate is made from aluminum.
  • drum 15 rotates a portion of photoconductive surface 16 through charging station A.
  • Charging station A employs a corona generating device in accordance with the present invention, indicated generally by the reference numeral 40, to charge photoconductive surface 16 to a relatively high substantially uniform potential.
  • Exposure station B includes an exposure mechanism, indicated generally by the reference numeral 17, having a stationary, transparent platen, such as a glass plate or the like for supporting an original document thereon. Lamps illuminate the original document. Scanning of the original document is achieved by oscillating a mirror in a timed relationship with the movement of drum 15 or by translating the lamps and lens across the original document so as to create incremental light images which are projected through an apertured slit onto the charged portion of photoconductive surface 16. Irradiation of the charged portion of photoconductive surface 16 records an electrostatic latent Image corresponding to the information areas contained within the original document.
  • Drum 15 rotates the electrostatic latent image recorded on photoconductive surface 16 to development station C.
  • Development station C includes a developer unit, indicated generally by the reference numeral 19, having a housing with a supply of developer mix contained therein.
  • the developer mix comprises carrier granules with toner particles adhering triboelectrically thereto.
  • the carrier granules are formed from a magnetic material with the toner particles being made from a heat fuseable plastic.
  • Developer unit 19 is preferably a magnetic brush development system. A system of this type moves the developer mix through a directional flux field to form a brush thereof.
  • the electrostatic latent image recorded on photoconductive surface 16 is developed by bringing the brush of developer mix into contact therewith. In this manner, the toner particles are attracted electrostatically from the carrier granules to the latent image forming a toner powder image on photoconductive surface 16.
  • a copy sheet is advanced by sheet feeding apparatus 32 to transfer station D.
  • Sheet feed apparatus 32 advances successive copy sheets to forwarding registration rollers 35 and 36.
  • Forwarding registration roller 35 is driven conventionally by a motor (not shown) in the direction of arrow 13 thereby also rotating idler roller 36 which is in contact therewith in the direction of arrow 14.
  • feed device 32 operates to advance the uppermost substrate or sheet from stack 33 into registration rollers 35 and 36 and against registration fingers 38.
  • Fingers 38 are actuated by conventional means in timed relation to an image on drum 15 such that the sheet resting against the fingers is forwarded toward the drum in synchronism with the image on the drum.
  • a conventional registration finger control system is shown in U.S. Patent 3,902,715. After the sheet is released by fingers 38, it is advanced through a chute formed by guides 50 and 51 to transfer station D.
  • transfer station D includes a conventional corona generating device 55 which applies a spray of ions to the back side of the copy sheet. This attracts the toner powder image from photoconductive surface 16 to the copy sheet.
  • the sheet After transfer of the toner powder image to the copy sheet, the sheet is advanced by endless belt conveyor 60, in the direction of arrow 11, to fusing station E.
  • Fusing station E includes a fuser assembly indicated generally by the reference numeral 70.
  • Fuser assembly 70 includes a fuser roll 71 and a backup roll 72 defining a nip therebetween through which the copy sheet passes. After the fusing process is completed, the copy sheet is advanced by conventional rollers 75 and 76 to catch tray 78.
  • Cleaning station F includes a corona generating device (not shown) adapted to neutralize the remaining electrostatic charge on photoconductive surface 16 and that of the residual toner particles.
  • the neutralized toner particles are then cleaned from photoconductive surface 16 by a rotatably mounted fibrous brush (not shown) in contact therewith.
  • a discharge lamp (not shown) floods photoconductive surface 16 with light to dissipate any residual electrostatic charge remaining thereon prior to the charging thereof for the next successive imaging cycle.
  • Figure 2 depicts the corona generating scorotron device 40 in greater detail.
  • the segmented coronode scorotron unit is positioned above the photosensitive surface 16 and is arranged to deposit an electrical charge thereon as the surface 16 moves in a clockwise direction.
  • the corona unit includes a shield member 41 as shown in Figure 1 that encloses a substantial portion of coronode wire 42.
  • Wire 42 is adapted to have active regions that give off corona emissions and support regions that anchor the wire.
  • the shield is preferably made from an electrically conductive material that is biased with respect to ground at 43 by conventional means.
  • a slit or opening is formed in the bottom of the shield opposite the moving photoconductor or photoreceptor 15 and provides a path by which ions flow from coronode 42 through control screen 45 onto photoconductive surface 16.
  • the corona generating wire 42 is connected by suitable means such as an electrical connector to a high potential source or power supply 43.
  • the corona wire utilized in this embodiment is connected directly to the negative terminal of the power source whereby negative ion discharge is placed on the photosensitive surface 16.
  • an opposite polarity can be employed to obtain positive discharge.
  • the wire is spaced about 3/32" to 1/8" away from screen 45. As corona units of more than ten inches are required for copying machines, these low tolerance dimensions become sensitive to wire sagging, vibration and arcing. Also, corona for negative charging tends to be spotty, i.e., emission points are seen at intervals of about 1 cm.
  • corona wire 42 is angled at an angle ED from the direction of travel to reduce the effective distance d between "hot spots" to d cos0.. Also, with zig zagging, the coronode spans a very short distance at a time, therefore, sagging and "singing" are negligible.
  • An alternative corona generating scorotron 90 is shown in Figure 3 and comprises a wire 93 (1 to 4 mil diameter) that is helically wound on an insulating support so that charging regions of the wire overlap and give support to free standing segments.
  • the insulating support includes two U-shaped channel members shown molded together in Figure 3 that are made of plexiglass, polycarbonate, or the like.
  • a screen 45 encloses the wire to form a scorotron unit.
  • the region of overlap of the helically wound wire must be carefully adjusted to insure a uniform charge distribution on the receiver. For example, with reference to Figure 4, with segment "A" charging as shown, segment “B” must be spaced so that the sum of "A” + “B” is constant.
  • X is the length of the coronode wire and V s is the surface potential of photoconductive surface 16.
  • each segment of a coronode wire is overlapping half of the adjacent segment to provide redundancy to enchance the smoothing of "hot spots" in the coronode.
  • This embodiment gives a great amount of redundancy because it adds the corona currents from two wires, i.e., a straight line drawn from a to a' will go through two wires (in this example wire segments B and C) for better averaging.
  • the overlap of the coronode wire could be by 2/3 or another fraction if one desired.
  • the coronode wire could either be helically wound on an insulating support as shown in Figure 3, or be supported by end blocks as shown in Figure 2.
  • a corotron/scorotron design in which the coronode wire is supported in short segments which are angled to the conventional wire direction.
  • the segments are positioned so that their output currents overlap to deliver uniform current along the length of the device. Since the wire segments span short distances, singing and sagging are reduced. The use of fine wires and close spacings are made readily viable with this design.
  • the charging redundancy of overlapping segments serves to smooth out "hot spot" effects.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • General Physics & Mathematics (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
EP84309000A 1984-01-03 1984-12-21 Skorotron mit verteilter Koronawicklung Withdrawn EP0147206A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US56760884A 1984-01-03 1984-01-03
US567608 1995-12-05

Publications (2)

Publication Number Publication Date
EP0147206A2 true EP0147206A2 (de) 1985-07-03
EP0147206A3 EP0147206A3 (de) 1987-06-03

Family

ID=24267886

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84309000A Withdrawn EP0147206A3 (de) 1984-01-03 1984-12-21 Skorotron mit verteilter Koronawicklung

Country Status (3)

Country Link
EP (1) EP0147206A3 (de)
JP (1) JPS60158583A (de)
BR (1) BR8406739A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4724509A (en) * 1986-07-25 1988-02-09 Xerox Corporation Efficiently mounted long coronodes
DE19735972C2 (de) * 1997-08-19 2000-01-13 Eastman Kodak Co Vorrichtung zum Aufbringen einer gleichmäßigen elektrostatischen Ladung auf einen Photoleiter
DE19655080B4 (de) * 1995-09-12 2014-07-31 Fuji Xerox Co., Ltd. Elektrophotografisches Bilderzeugungsgerät

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1195165B (de) * 1963-04-30 1965-06-16 Fotoclark F Gruen K G Aufladegeraet fuer mit einer photoleitenden Schicht versehene Folien
US3348041A (en) * 1964-12-30 1967-10-17 Union Carbide Corp Apparatus for the corona discharge treatment of plastic surfaces having an adjustable length electrode assembly
US3470417A (en) * 1966-10-03 1969-09-30 Eastman Kodak Co Method of altering electrostatic charge on an insulating material
DE6752807U (de) * 1968-08-30 1969-06-04 Siegfried Rohr Vorrichtung zu erhoehung der kopiergeschwindigkeit bei elektrostatischen vervielfaeltigungsgeraeten.
JPS503345A (de) * 1973-05-11 1975-01-14
JPS55163555A (en) * 1979-06-05 1980-12-19 Ricoh Co Ltd Charging device
JPS5790663A (en) * 1980-11-27 1982-06-05 Konishiroku Photo Ind Co Ltd Corona discharge device

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4724509A (en) * 1986-07-25 1988-02-09 Xerox Corporation Efficiently mounted long coronodes
DE19655080B4 (de) * 1995-09-12 2014-07-31 Fuji Xerox Co., Ltd. Elektrophotografisches Bilderzeugungsgerät
DE19735972C2 (de) * 1997-08-19 2000-01-13 Eastman Kodak Co Vorrichtung zum Aufbringen einer gleichmäßigen elektrostatischen Ladung auf einen Photoleiter

Also Published As

Publication number Publication date
JPS60158583A (ja) 1985-08-19
BR8406739A (pt) 1985-10-22
EP0147206A3 (de) 1987-06-03

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Inventor name: GUNDLACH, ROBERT WILLIAM