US3699388A - Apparatus for electrostatic charging of paper in electrophotographic reproduction - Google Patents

Apparatus for electrostatic charging of paper in electrophotographic reproduction Download PDF

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Publication number
US3699388A
US3699388A US144182A US3699388DA US3699388A US 3699388 A US3699388 A US 3699388A US 144182 A US144182 A US 144182A US 3699388D A US3699388D A US 3699388DA US 3699388 A US3699388 A US 3699388A
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US
United States
Prior art keywords
electrode
discharge electrode
discharge
corona discharge
power source
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
US144182A
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English (en)
Inventor
Takeshi Ukai
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Ricoh Co Ltd
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Ricoh Co Ltd
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Publication date
Application filed by Ricoh Co Ltd filed Critical Ricoh Co Ltd
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Publication of US3699388A publication Critical patent/US3699388A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/003—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for electrostatic apparatus
    • 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
    • G03G15/0266—Arrangements for controlling the amount of charge
    • 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

  • a corona discharge electrode is supplied with voltage Related A fi fi Data from a high frequency power source to produce a corona discharge which strikes a sheet of reproducing [63] commuatlonlrlpart of 5 June paper to charge the same electrostatically.
  • a detection l 1968' electrode is positioned in the field of the corona discharge and is connected via a resistor and amplifier [30]
  • Fomg Apphcam Pnomy Data to the power source to control the same in accordance July 6, 19 7 j n 42/43571 with, the detected corona discharge to maintain the magnitude of the discharge field constant.
  • a switch is [52] U.S. Cl ..317/4, 317/262 A nn c in th power supply to interrupt connection 51 Int. Cl. ..G03g 15/02, HOlt 19/00 thereof with the discharge electrode if a spark [58] Field of Search ..3 1 7/262 R, 262 A, 4 discharge is produced between the discharge electrode and the paper. [56] References Cited UNITED STATES PATENTS Larsen et a]. ..317/262 R 5 Claims, 1 Drawing Figure BRIEF SUMMARY OF THE INVENTION The invention relates to apparatus and methods for controlling high voltage current supplied to a corona discharge electrode in electrophotographic reproduction apparatus. 7
  • An object of the present invention is to provide a charging device incorporating means for stabilizing the charging action and obviate any variations thereof.
  • a corona current detecting means is incorporated in the charging device for controlling the change of corona current for eliminating instability and for maintaining a uniform that a uniform copy may be obtained.
  • a charge control circuit for electrophotographic reproducing apparatus which comprises a high voltage power source, a corona discharge electrode electrically connected to said source for producing a corona discharge current, a target plate for supporting a sheet of reproducing paper, said target plate being grounded and facing said discharge electrode to expose the sheet of reproducing paper to the coronadischarge current from said corona discharge electrode whereby said sheet is electrostatically charged, a detection electrode positioned adjacent said discharge electrode to detect corona discharge current from said discharge electrode, and feedback means connected to said discharge electrode and to said high charge so voltage power source to control said power source in accordance with the detected corona discharge current to maintain the value of said current constant.
  • the discharge electrode and detection electrode are placed adjacent one, another in a hollow, grounded guide member which has an opening facing the target plate.
  • the discharge between the discharge electrode and the detection electrode is substantially constant regardless of the presence or absence of a copy sheet on the target plate.
  • a further object of the invention is to provide a safety device which is operative to interrupt supply of power to the discharge electrode if a spark discharge should be produced between the discharge electrode and the paper due to contact therebetween, or the like, which could produce a fire.
  • the safety device is operative when the detection electrode detects the absence of a corona discharge field upon the production of a spark discharge between the discharge electrode and the copy paper.
  • FIG. 1 is a circuit diagram of the charge control apparatus according to the invention.
  • FIG. 2 is a perspective view, partly broken away, of a portion of the apparatus of FIG. 1.
  • a corona discharge electrode 1 constituted as a tungsten wire.
  • a detection electrode 2 also in the form of a tungsten wire.
  • the detection electrode 2 is intended to detect the magnitude of the corona discharge field developed by the electrode 1.
  • the electrodes 1 and 2 are mounted in a hollow guide member 3. which is connected to ground and is pro vided with an opening facing a grounded target plate 10 on which a sheet of reproducing paper 11 can be placed.
  • the hollow member 3 servesto confine the corona discharge and direct the discharge to the paper 11 to charge the paper electrostatically.
  • the intensity of the corona field is the same at the detection electrode 2 as at the plate 10 with the exception that the electrode 2 is not subject to the variable effects of the paper 11 as is the plate 10.
  • the current detected in the electrode 2 is an accurate representation of the intensity of the corona field produced by the electrode 1.
  • the current in the electrode 2 will serve as a means to control the voltage applied to electrode 1 in order to stabilize the corona discharge and render the charge on the copy paper 1 l uniform.
  • the detection electrode 2 is connected to a variable resistor 4 across which a voltage is produced related to the current in detection electrode 2.
  • the resistor 4 is connected to the input of an amplifier 5 which produces an amplified output signal of the voltage in resistor 4.
  • the output of the amplifier produced at the plate of a triode V is connected to the control grid of an oscillating vacuum tube 6 which serves to control the voltage input to the discharge electrode 1 by virtue of its connection via resonance condenser 7 to the primary winding of a high frequency transformer 8.
  • the secondary of the transformer is connected to a high voltage rectifier 9 which is connectedto discharge electrode l.
  • the corona current is increased contrary to the above-mentioned case and the balance is maintained.
  • the corona current is always kept at a fixed value, and the charging operation is stabilized withoutany unevenness so that a uniform copy can be obtained by the electrophotographic reproduction apparatus.
  • the resistor 4, amplifier 5 and oscillation circuit constitute a feedback meansto control the power source of transformer 8 and rectifier 9 to maintain the value of the corona discharge current constant.
  • the same object is obtainable by providing the oscillation circuit of the invention with a pulse generator, thereby changing-the pulse interval by using the detected voltage of the variable resistor 4 and controlling the high voltage applied to the discharge electrode 1.
  • the detection electrode 2 need not be arranged adjacent to the electrode 1 and for example, a shielding box (similar to corona guide member 3) can be employed for electrode 1, but the shielding box is normally grounded directly.
  • the electrodes l and 2 are mounted in hollow guide member 3 with the electrode 2 remote from paper 11 and spaced further therefrom than is the electrode 1, in order to eliminate any effect of the paper 11 on the current detected in detection electrode 2.
  • a corona current detection produces a signal which is employed as a feedback to the corona generating power supply to maintain the corona current constant without any change so that a uniform copy may be obtained.
  • the circuit of the invention is also constructed to eliminate the possibility of a fire in the event that the copy paper should contact the discharge electrode 1 to produce a spark discharge therebetween.
  • a safety device which detects the presence of a spark discharge to open a switch 40 connected between the primary winding of trans former 8 and the voltage source.
  • a grid of a triode V is connected to the plate of triode V, through a Zener diode Zn.
  • a coil of a holding type relay 40' is connected to the plate of triode V Any holding type relay can be used if the open state of its contacts is maintained until the relay once operated is reset by hand.
  • a time constant circuit comprising a diode 30, a resistor 31, a condenser 32 and a resistor 33 is connected between the plate of the triode V and the Zener diode Zn. If a button is pushed to supply the charging device with power, a discharge will be effected in the discharge electrode 1 after a short delay of time during which the heater of the vacuum tube is heated. Herein, if there is not provided this time lag mechanism, the triode V is operated to open the switch contacts 40 of the relay 40'. In the state of normal use, the potential of the plate of the triode V, is lower than that of the Zener diode and the triode V is cut off.
  • the triode V will become conductive, and the normally closed switch contacts 40 of the relay coil 40' will be opened. These contacts can be closed by resetting them by hand after the trouble has been corrected.
  • a charge control circuit for electrophotographic reproducing apparatus comprising a high voltage power source, a corona discharge electrode electrically connected to said. source for producing a corona discharge current, a tar-.
  • said means to interrupt the connection of the power source to the discharge electrode comprising a switch means for interrupting power supply to the primary winding of the transformer, a relay controlling said switch means, and means including a timer circuit connected to said feedback means and to said relay to operate said relay and open said switch means if said feedback means detects lack of corona discharge current.
  • a circuit as claimed in claim 1 comprising a hollow grounded guide member having an opening facing said target plate, said discharge electrode and detection electrode being adjacent one another within said guide member.
  • said feedback means comprises a variable resistor connected to said detection electrode, amplifier means having an input connected to said variable resistor, control means connected to the amplifier means at the output thereof and to the power source to adjust the latter in accurrent to render said triode conductive whereupon the relay is activated and said switch means is opened.
  • a circuit as claimed in claim 4 wherein said timer circuit comprises a diode, a resistor means and a condenser connected between said Zener diode and said amplifier means.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • General Physics & Mathematics (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
US144182A 1967-07-06 1971-05-17 Apparatus for electrostatic charging of paper in electrophotographic reproduction Expired - Lifetime US3699388A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP4357167 1967-07-06

Publications (1)

Publication Number Publication Date
US3699388A true US3699388A (en) 1972-10-17

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ID=12667421

Family Applications (1)

Application Number Title Priority Date Filing Date
US144182A Expired - Lifetime US3699388A (en) 1967-07-06 1971-05-17 Apparatus for electrostatic charging of paper in electrophotographic reproduction

Country Status (4)

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US (1) US3699388A (en, 2012)
BE (1) BE715685A (en, 2012)
DE (1) DE1771684A1 (en, 2012)
GB (1) GB1235497A (en, 2012)

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3809955A (en) * 1973-03-26 1974-05-07 Graco Inc Safety circuit for electrostatic spray gun
US3909614A (en) * 1973-12-21 1975-09-30 Xerox Corp Scorotron power supply circuit
DE2550846A1 (de) * 1974-11-12 1976-05-13 Ricoh Kk Entwicklungseinrichtung fuer ein elektrophotographisches kopiergeraet
US3976881A (en) * 1975-10-29 1976-08-24 Xerox Corporation Arrangement for stabilizing corona devices
US3976880A (en) * 1975-10-29 1976-08-24 Xerox Corporation Corona stabilization arrangement
FR2309908A1 (fr) * 1975-04-28 1976-11-26 Xerox Corp Appareil de reproduction electrostatographique muni de moyens de mesure de courant corona
US4189642A (en) * 1978-04-03 1980-02-19 International Business Machines Corporation Method and apparatus for drum corona current measurement and alignment
US4346986A (en) * 1977-12-22 1982-08-31 Canon Kabushiki Kaisha Image formation method and apparatus
US4417804A (en) * 1981-06-19 1983-11-29 Xerox Corporation High voltage comparator for photoreceptor voltage control
DE3401445A1 (de) * 1983-01-20 1984-08-02 Sharp K.K., Osaka Elektrophotographischer kopierer
EP0207554A1 (en) * 1985-07-01 1987-01-07 Océ-Nederland B.V. Method of and device for determining a measure of the surface potential of a medium charged by means of a corona charging device
US5164771A (en) * 1978-08-24 1992-11-17 Canon Kabushiki Kaisha Image forming apparatus which adjusts illumination levels independently for test samples and for originals
US5164776A (en) * 1991-09-19 1992-11-17 Xerox Corporation Apparatus and method for correcting the voltage on a photoconductive device
US5317155A (en) * 1992-12-29 1994-05-31 The Electrogesic Corporation Corona discharge apparatus
US6034368A (en) * 1998-07-06 2000-03-07 Xerox Corporation AC corona current regulation
US20070075261A1 (en) * 2005-09-13 2007-04-05 Brundula Steven N Systems and Methods for ARC Energy Regulation
US20080158769A1 (en) * 2006-05-03 2008-07-03 Brundula Steven N D Systems And Methods For Arc Energy Regulation And Pulse Delivery
US20080259520A1 (en) * 2007-04-19 2008-10-23 Brundula Steven N D Systems and Methods for Pulse Delivery

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2353085A1 (fr) * 1976-05-26 1977-12-23 Canon Kk Procede et dispositif de charge d'un organe de reproduction electrophotographique par decharge par effluves
JPS58136063A (ja) * 1982-02-08 1983-08-12 Fuji Xerox Co Ltd 電子写真複写機のコロナ放電装置

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2767359A (en) * 1951-06-29 1956-10-16 Gen Motors Corp High voltage current control
US2868989A (en) * 1956-01-03 1959-01-13 Haloid Xerox Inc Electrostatic charging method and device
CA748015A (en) * 1966-12-06 Canadian Kodak Co. Limited Electrostatic charging methods and apparatus
US3390266A (en) * 1964-11-05 1968-06-25 Epping Reinhold Hermann Apparatus for charging the surface of photoelectric layers using corona discharge

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA748015A (en) * 1966-12-06 Canadian Kodak Co. Limited Electrostatic charging methods and apparatus
US2767359A (en) * 1951-06-29 1956-10-16 Gen Motors Corp High voltage current control
US2868989A (en) * 1956-01-03 1959-01-13 Haloid Xerox Inc Electrostatic charging method and device
US3390266A (en) * 1964-11-05 1968-06-25 Epping Reinhold Hermann Apparatus for charging the surface of photoelectric layers using corona discharge

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3809955A (en) * 1973-03-26 1974-05-07 Graco Inc Safety circuit for electrostatic spray gun
US3909614A (en) * 1973-12-21 1975-09-30 Xerox Corp Scorotron power supply circuit
US4423134A (en) * 1974-11-12 1983-12-27 Ricoh Company, Ltd. Developing unit for electrophotography
DE2550846A1 (de) * 1974-11-12 1976-05-13 Ricoh Kk Entwicklungseinrichtung fuer ein elektrophotographisches kopiergeraet
FR2309908A1 (fr) * 1975-04-28 1976-11-26 Xerox Corp Appareil de reproduction electrostatographique muni de moyens de mesure de courant corona
US3976881A (en) * 1975-10-29 1976-08-24 Xerox Corporation Arrangement for stabilizing corona devices
US3976880A (en) * 1975-10-29 1976-08-24 Xerox Corporation Corona stabilization arrangement
US4346986A (en) * 1977-12-22 1982-08-31 Canon Kabushiki Kaisha Image formation method and apparatus
US4189642A (en) * 1978-04-03 1980-02-19 International Business Machines Corporation Method and apparatus for drum corona current measurement and alignment
US5164771A (en) * 1978-08-24 1992-11-17 Canon Kabushiki Kaisha Image forming apparatus which adjusts illumination levels independently for test samples and for originals
US4417804A (en) * 1981-06-19 1983-11-29 Xerox Corporation High voltage comparator for photoreceptor voltage control
DE3401445A1 (de) * 1983-01-20 1984-08-02 Sharp K.K., Osaka Elektrophotographischer kopierer
EP0207554A1 (en) * 1985-07-01 1987-01-07 Océ-Nederland B.V. Method of and device for determining a measure of the surface potential of a medium charged by means of a corona charging device
US5164776A (en) * 1991-09-19 1992-11-17 Xerox Corporation Apparatus and method for correcting the voltage on a photoconductive device
US5317155A (en) * 1992-12-29 1994-05-31 The Electrogesic Corporation Corona discharge apparatus
US6034368A (en) * 1998-07-06 2000-03-07 Xerox Corporation AC corona current regulation
US20070075261A1 (en) * 2005-09-13 2007-04-05 Brundula Steven N Systems and Methods for ARC Energy Regulation
US7457096B2 (en) 2005-09-13 2008-11-25 Taser International, Inc. Systems and methods for ARC energy regulation
US20080158769A1 (en) * 2006-05-03 2008-07-03 Brundula Steven N D Systems And Methods For Arc Energy Regulation And Pulse Delivery
US7986506B2 (en) 2006-05-03 2011-07-26 Taser International, Inc. Systems and methods for arc energy regulation and pulse delivery
US8154845B1 (en) 2006-05-03 2012-04-10 Taser International, Inc. Systems and methods for arc energy regulation and pulse delivery
US8456793B2 (en) 2006-05-03 2013-06-04 Taser International, Inc. Systems and methods for ionization using adjusted energy
US8743527B2 (en) 2006-05-03 2014-06-03 Taser International, Inc. Systems and methods for arc energy regulation using binary adjustment
US20080259520A1 (en) * 2007-04-19 2008-10-23 Brundula Steven N D Systems and Methods for Pulse Delivery
US7821766B2 (en) 2007-04-19 2010-10-26 Taser International, Inc. Systems and methods for pulse delivery

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Publication number Publication date
GB1235497A (en) 1971-06-16
DE1771684A1 (de) 1971-01-14
BE715685A (en, 2012) 1968-10-16

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