US3736424A - Corona discharge device - Google Patents

Corona discharge device Download PDF

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Publication number
US3736424A
US3736424A US00204464A US3736424DA US3736424A US 3736424 A US3736424 A US 3736424A US 00204464 A US00204464 A US 00204464A US 3736424D A US3736424D A US 3736424DA US 3736424 A US3736424 A US 3736424A
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US
United States
Prior art keywords
corona
electrode
path
current flow
corona current
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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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US00204464A
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English (en)
Inventor
T Cecil
R Davidge
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International Business Machines Corp
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International Business Machines Corp
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Publication of US3736424A publication Critical patent/US3736424A/en
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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
    • G03G15/02—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
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05F—STATIC ELECTRICITY; NATURALLY-OCCURRING ELECTRICITY
    • H05F3/00—Carrying-off electrostatic charges
    • H05F3/04—Carrying-off electrostatic charges by means of spark gaps or other discharge devices

Definitions

  • the support blocks are configured to include a a v surface interruption that provides a cul-de-sac includ- UNITED STATES PATENTS ing surface which is shielded from the path of corona current and ionized gas thereby preventing accumula- 3;
  • Electrostatic document copying machines commonly employ a photoconductive copy surface capable of selectively discharging a uniformly applied initial electrostatic charge in response to a light image.
  • a latent electrostatic image remains following the discharge which can be developed by the application of charged electroscopic powder through any of several techniques.
  • the more sophisticated techniques employ a magnetic brush or powder cloud with a development electrode and are capable of developing half-tones and solid areas as well as line copy.
  • the charge corona is one possible source of non-image variations in charge which can interfere with the accurate reproduction of a document. Uniform operation of a charge corona is achieved through the selection of relatively large corona current flow which, by its very magnitude, reduces the significance of potential non uniformities.
  • a further object of our invention has been to provide a corona discharge unit having a sustained high quality performance that is achieved by the simple configuration of the electrode support parts.
  • the interruption comprises a shielded surface portion that is substantially out of the path of ionized gases and can preferably be in the form of an elongated cul-desac having a restricted entrance that is inherently nonreceptive to gaseous flows.
  • FIG. 1 is an elevational schematic view of a xerographic type electrostatic copy reproducing machine
  • FIG. 2 is a cross-sectional view of a charging corona unit constructed in accordance with our invention and taken along the line of its longitudinal axis; and
  • FIG. 3 is a side cross-sectional view of the corona unit shown in FIG. 2 taken along axis III III thereof.
  • a xerographic type electrostatic copy reproducing mechanism 10 having a corona discharge assembly or charge corona unit 20 for placing a uniform electrostatic charge on a copy drum surface 1 l.
  • the charged copy surface 11 is passed under an imaging station 12 where the original charge is selectively discharged by a light image from an original document 13.
  • the resultant latent image is moved to a development station 14 which for example could be like that described in U. S. Pat. No. 3,599,605.
  • the image After the image is developed, it is passed to a transfer station 15 where plain paper is fed into superimposition therewith and the image is transferred to the paper.
  • the paper then is separated from the drum surface 11 and passed to a heat fixing station 16 while the drum surface 11 continues to move to a cleaning station 17 for preparation for further copying.
  • the ability of the copy machine 10 to faithfully reproduce an image of the original document 13 depends, in part, upon the uniformity of the initial charge received by surface 11 from the charge corona unit 20.
  • the corona unit 20 includes three elongated corona emitting electrode wires 21 that are suspended in spaced relation from the copy surface 11 between hooks 22 carried by a pair of electrically insulative end blocks 30 best shown in FIG. 2.
  • the end blocks 30 are connected to suitable frame-work 18 through an electrically conductive shield 40 by screws 41.
  • the shield 40 is slideably mounted by a track member 42 on dovetail frame part 19 connected to the machine frame part I8 to permit removing of the corona unit 20 for repair or cleaning.
  • the hooks 22 are connected to the electrode wire ends 23 by tensioning springs 24.
  • Conductor rod 25 extends through the end block 30 and is electrically connected with the books 22 at one end and projects outwardly of a tapered plug portion 31 for connection to a suitable power'supply 26, see FIG. 1.
  • the charge corona unit 20 also includes a wire con trol grid 50 positioned between the corona wires 21 and the drum surface 11 for limiting the corona current received by the drum surface 11.
  • the wires 51 of grid 50 are also supported by the end blocks 30 as best shown in FIG. 2.
  • each grid wire 51 is connected through tensioning springs 52 to a tab 53 of a mounting plate 54.
  • a screw 55 anchors the mounting plate 54 to the end block 30.
  • Aconductor rod 56 is connected to the mounting plate 54 to provide for connection of the grid 50 to a suitable potential source such as power supply 26, see FIG. 1.
  • the electrode wires 21 are connected to a high potential line 27 of power supply 26.
  • the shield 40 and grid 50 are connected to a lower potential line 28 of the power supply 26, through conductors 43 and 56a respectively.
  • the shield 40 can be connected to ground if desired.
  • the difference in potential between the electrode wires 21 and the shield 40 and grid 50 causes the air therebetween to become ionized and a so-called corona current discharge or flow occurs. Since the copy surface 11 is at a different potential than the corona electrode wires 21, a potential exists for causing a portion of the corona current flow to go past the grid' 50 and deposit charge on the copy surface 11.
  • the path of the corona discharge current flow is shown by the lines 32 in FIGS. 1 and 2.
  • the flow of current in a corona discharge is accompanied by a movement of the gases that are ionized and these gases also move along the path of corona discharge 32. As seen in FIG. 2 these gases will brush against inwardly facing external surface 33 of the supporting end blocks 30. While all of the end blocks 30 are made of electrically insulated material and thereby provide no conductive path for current flow between v the corona electrode wires 21 and other conductive parts connected thereto, such as the grid wires 50 or the shield 40, the inwardly facing external surface 33 which is generally exposed to the path of corona cur rent flow can become conductive due to the deposition of salts from the corona gas movement.
  • the corona exposed surface region 33 of the end block 30 of our corona includes an interrupted configuration in the form of a long and narrow cul-de-sac 34 that is positioned between the point of corona wire suspensing connection 22 and the point of contact such as 57 between the end block 30 and the grid wire 50 or the point 44 between the end block 30 and the shield 40.
  • the cul-de-sac 34 includes a shielded surface portion 35 including an overhanging lip 36 that faces outwardly away from the corona wire 21 and extends at a substantial angle 37, greater that 45 and preferably 90 from the path 32 of corona discharge flow.
  • the culdesac 34 further, is preferably formed with a narrow inlet 38 and is relatively long with respect to the inlet 38 to substantially eliminate any regular flow of ionized gases therewithin.
  • corona discharge from electrode wires 21 produces ionized gases which precipitate salts on the exposed inwardly facing surface 33 of the corona end block 30. While the surfaces thus become conductive, a complete electrical path is not formed, however, due to the presence of the shielded surface 35 of the cul-de-sac 34 which does not receive corona generated salts. Thus, surface portion 35 remains an electrically insulated interruption lying in any path that can be traced on the corona exposed surface 33 from the corona wires 21 to a conductive member such as grid wires 50 or shield 40 that is also in contact with the end blocks 30. The performance of the charge corona unit' 20 thus will not deteriorate with time due to the accumulation of corona generated salts on its necessary supporting end blocks 30.
  • a corona discharge assembly of the type having electrode means, means for suspending said electrode means in spaced relation to a corona current receiving member whereby a corona current flow path is defined between said electrode means and said corona current receiving member, said suspending means comprising at least one electrically insulative member supportively connected to said electrode means and including an external surface having a region that is generally exposed to the path of corona current flow, and electrically conductive means engaging said insulative member at a location spaced from said electrode means wherein the improvement comprises:
  • corona discharge assembly as defined in claim 1 wherein said interruption comprises a cul-de-sac configuration formed in said insulative member and having at least a restricted external opening to minimize gaseous movement therethrough.
  • a corona discharge assembly of the type having at least one elongated electrode means, means for suspending said electrode means in spaced relation to a corona current receiving member whereby a corona current flow path is defined between said electrode means and said corona current receiving member, said suspending means comprising at least a pair of electrically insulative members supportively connected to opposed ends of said elongated electrode means, and each including an external surface region that is generally exposed to the path of corona current flow and electrically conductive means engaging said insulative members at points spaced from said electrode means, wherein the improvement comprises:
  • said electrically conductive means comprises a conductive shield partially surrounding said electrode means and being supportingly connected to said insulative members.
  • a corona discharge assembly of the type having at least one elongated electrode wire, means for suspending said electrode wire in spaced relation to a corona current receiving member whereby a corona current flow path is defined between said electrode wire and said corona current receiving member, said suspending means comprising at least a pair of electrically insulative members supportively connected to opposed ends of said electrode wire and each including an external surface region that is generally exposed to the path of corona current flow, and electrically conductive control grid means supportedly connected to said electrically insulative members and positioned between said electrode wire and said corona current receiving member for limiting corona current flow, wherein the improvement comprises:
  • An electrostatic copy reproducing mechanism having a copy surface, for receiving an electrostatic charge and comprising the improvement of a corona discharge assembly as defined in claim 11 wherein said copy surface comprises said corona current receiving member andfurther comprising high voltage power supply means for delivering corona generating potential to said electrode wire,

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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)
US00204464A 1971-12-03 1971-12-03 Corona discharge device Expired - Lifetime US3736424A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US20446471A 1971-12-03 1971-12-03

Publications (1)

Publication Number Publication Date
US3736424A true US3736424A (en) 1973-05-29

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Application Number Title Priority Date Filing Date
US00204464A Expired - Lifetime US3736424A (en) 1971-12-03 1971-12-03 Corona discharge device

Country Status (6)

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US (1) US3736424A (it)
JP (1) JPS5121797B2 (it)
CA (1) CA1001219A (it)
FR (1) FR2164155A5 (it)
GB (1) GB1398024A (it)
IT (1) IT967751B (it)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2448761A1 (de) * 1973-11-01 1975-05-07 Ibm Anordnung zur vermeidung der formierung von korpuskularem material in coronaentladungsvorrichtungen
US3922548A (en) * 1973-05-18 1975-11-25 Rank Xerox Ltd Corona charging device and support arrangement
US4104521A (en) * 1976-04-09 1978-08-01 Amp Incorporated Corotron connector
EP0016300A1 (en) * 1979-03-26 1980-10-01 International Business Machines Corporation Electrostatic copier
EP0026653A1 (en) * 1979-09-28 1981-04-08 Xerox Corporation Corona generating device
US20080074792A1 (en) * 2006-09-21 2008-03-27 Nanochip, Inc. Control scheme for a memory device
US20090074463A1 (en) * 2006-04-28 2009-03-19 Shigeru Nishio Corona discharge device, photoreceptor charger, and method for making discharge product removing member

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4556795A (en) * 1982-11-19 1985-12-03 Ensign-Bickford Industries, Inc. Corona discharge device
JPS61241540A (ja) * 1985-04-18 1986-10-27 Tatsuya Mikami エネルギ−吸収装置
EP3488805A1 (en) 2013-08-07 2019-05-29 Covidien LP Bipolar surgical instrument

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2070307A (en) * 1931-12-21 1937-02-09 Sunlite Company Inc Method and apparatus for treating material with ozone and ultra violet rays
US2863063A (en) * 1955-11-21 1958-12-02 Bruning Charles Co Inc Charging of photo-conductive insulating material
US3114877A (en) * 1956-10-30 1963-12-17 Gen Electric Particle detector having improved unipolar charging structure
US3369152A (en) * 1964-07-21 1968-02-13 Spengler Walter Device for collecting electrostatic charges from poor conductors by means of a corona discharge
US3396308A (en) * 1965-07-02 1968-08-06 Eastman Kodak Co Web treating device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2070307A (en) * 1931-12-21 1937-02-09 Sunlite Company Inc Method and apparatus for treating material with ozone and ultra violet rays
US2863063A (en) * 1955-11-21 1958-12-02 Bruning Charles Co Inc Charging of photo-conductive insulating material
US3114877A (en) * 1956-10-30 1963-12-17 Gen Electric Particle detector having improved unipolar charging structure
US3369152A (en) * 1964-07-21 1968-02-13 Spengler Walter Device for collecting electrostatic charges from poor conductors by means of a corona discharge
US3396308A (en) * 1965-07-02 1968-08-06 Eastman Kodak Co Web treating device

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3922548A (en) * 1973-05-18 1975-11-25 Rank Xerox Ltd Corona charging device and support arrangement
DE2448761A1 (de) * 1973-11-01 1975-05-07 Ibm Anordnung zur vermeidung der formierung von korpuskularem material in coronaentladungsvorrichtungen
US4104521A (en) * 1976-04-09 1978-08-01 Amp Incorporated Corotron connector
EP0016300A1 (en) * 1979-03-26 1980-10-01 International Business Machines Corporation Electrostatic copier
EP0026653A1 (en) * 1979-09-28 1981-04-08 Xerox Corporation Corona generating device
US20090074463A1 (en) * 2006-04-28 2009-03-19 Shigeru Nishio Corona discharge device, photoreceptor charger, and method for making discharge product removing member
US7885572B2 (en) * 2006-04-28 2011-02-08 Sharp Kabushiki Kaisha Corona discharge device, photoreceptor charger, and method for making discharge product removing member
US20080074792A1 (en) * 2006-09-21 2008-03-27 Nanochip, Inc. Control scheme for a memory device

Also Published As

Publication number Publication date
DE2257930A1 (de) 1973-06-20
JPS4864937A (it) 1973-09-07
JPS5121797B2 (it) 1976-07-05
DE2257930B2 (de) 1974-03-28
CA1001219A (en) 1976-12-07
FR2164155A5 (it) 1973-07-27
IT967751B (it) 1974-03-11
GB1398024A (en) 1975-06-18

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