US3908164A - Corona current measurement and control arrangement - Google Patents

Corona current measurement and control arrangement Download PDF

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Publication number
US3908164A
US3908164A US511831A US51183174A US3908164A US 3908164 A US3908164 A US 3908164A US 511831 A US511831 A US 511831A US 51183174 A US51183174 A US 51183174A US 3908164 A US3908164 A US 3908164A
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US
United States
Prior art keywords
corona
bridge
source
current
voltage
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
US511831A
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English (en)
Inventor
Delmer G Parker
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
Priority to US511831A priority Critical patent/US3908164A/en
Priority to GB2204475A priority patent/GB1467935A/en
Priority to NL7510460A priority patent/NL7510460A/xx
Priority to DE19752539400 priority patent/DE2539400A1/de
Priority to CA234,998A priority patent/CA1033805A/en
Application granted granted Critical
Publication of US3908164A publication Critical patent/US3908164A/en
Priority to JP50116260A priority patent/JPS5163662A/ja
Priority to FR7530436A priority patent/FR2287045A1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current 
    • G05F1/46—Regulating voltage or current  wherein the variable actually regulated by the final control device is DC
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R17/00—Measuring arrangements involving comparison with a reference value, e.g. bridge
    • G01R17/10—AC or DC measuring bridges
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
    • G01R29/24—Arrangements for measuring quantities 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
    • G03G15/0266—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 bridge circuit is formed which includes the corona device as one arm and a first resistor connected in the current return path from the corona device to a power supply as another arm thereof.
  • the remaining arms of the bridge include a capacitor and a resistor connected in series with each other across the source to complete the bridge and provide the signal required to compensate for reactive current through the corona device.
  • the bridge is first brought into balance with the power supply below corona onset voltage, then when the power supply is increased above the corona outset voltage the bridge output potential is used as a feedback signal to maintain the corona current constant.
  • the bridge output may also be used in determining the true corona charging current.
  • This invention relates generally to A.C. corona discharge devices and in particular to circuit arrangements for accurately measuring the amount of charging current delivered by' an A.C. corona discharge device to a charge receiving surfaceg; i
  • a uniform layer of electrostatic charge is deposited on the surface of a photoreceptor and is selectively dissipated in accordance with modulated radiation imaged thereon to form an electrostatic latent image of an original document.
  • the electrostatic image is then developed and transferred to a support surface to form a final copy of the original document.
  • the preferred device for depositing the charge on the photoreceptor surface is the c or'ona discharge device.
  • A.C. corona discharge devices are used for a'wide variety of other applications in electrophotography.
  • precleaning a photoreceptor by neutralizing thecharge on toner particles adhering to the surface of the photoreceptor after transfer of the developed image to a support surface pretransfer charging for altering the range-ofelectrostatic charge on toner prior to transfer, tacking, detacking, and paper charge neutralization.
  • Constant current power supplies are also used to combat long term changes in the uniformity of the corona output as toner accumulates on the surface of the corona generating apparatus.
  • zener diodes CR, and CR have characteristic zener breakdown voltages that correspond to the negative and positive corona threshold voltages respectively. As is well known, these breakdown voltages are generally somewhat different.
  • R is a non-linear resistance representing the corona resistance and C, is the capacity between the corona wire and the current collecting surfaces.
  • R is the series feedback resistor in series with the power supply and is selected to have a value so that R R,.
  • the current passing through R is the vector sum of the corona current I (the current through R,) and displacement current, I (the current through C,). Only the corona current I is important in xerographic processes since it alone represents the free charge transported per unit time by ions impinging on the collecting surface.
  • the reactive current will be an order of magnitude smaller and out of phase with the corona current, its contribution to the voltage drop across the feedback resistor is small and can be neglected with very little error.
  • the reactive current is linear with the applied voltage whereas the corona current is non-linear with the applied voltage. Consequently, the phase angle of the current through the feedback resistor with respect to the applied voltage is not constant as voltage changes. Furthermore, since the capacitive coupling and corona resistance vary within wide limits and in a non-linear fashion a function of the spacing between the corona device and the collecting surface it is clear that a given voltage across the feedback resistor may not correspond to a unique corona current.
  • the distributed capacity C between ground and the high tension lead connecting the corotron to the remote power supply will be in shunt with the corona resistance and will also contribute to the voltage developed across the feedback resistor R
  • the high tension cable capacity may be orders magnitude larger than that of the corotron itself.
  • the signal in the feedback resistor due to the corona current may be swamped or masked by the much larger reactive current.
  • large excursions in the corona current may represent only a small perturbation in the total power supply current which is beyond the ability of the control circuit to resolve. Therefore, the constant corona current characteristics are not realized.
  • an object of the invention to provide a method for measuring the true corona current deposited by an AC. corotron on a charge collecting surface.
  • a further object is to provide a means for regulating the current output of a corona device to supply a constant charging current to a charge receiving surface.
  • the invention provides an arrangement for discriminating between true corona current and (the current associated with the flow of charge to the surface to be charged) and reactive current capacitatively shunting the collecting surface.
  • a corrective signal equal in magnitude and 180 out of phase with the reactive component of the corotron current is added to the normal signal to eliminate the reactive component from the current reading.
  • a bridge circuit is formed which includes the corona device as one arm and a first resistor connected in the current return path from the corona device to a power supply as another arm thereof.
  • the remaining arms of the bridge include a capacitor and a resistor connected in series with each other across the source to complete the bridge and provide the signal required to compensate for reactive current through the corona device.
  • the bridge is first brought into balance with the power supply below corona onset voltage, then when the power supply is increased above the corona outset voltage the bridge output potential is used as a feedback signal to maintain the corona current constant.
  • the bridge output may also be used in determining the true corona charging current.
  • FIG. 1 illustrates a typical commercial circuit arrangement for obtaining constant current charging.
  • FIGS. 2 and 3 are equivalent circuits of the corona discharge arrangement of FIG. 1, and
  • FIG. 4 shows a bridge arrangement of the invention for obtaining accurate corona charging current measurements and for obtaining constant corona charging current.
  • the R,, CR,, CR and C, parallel combination represents the equivalent electrical circuit of the corona arrangement, discussed in connection with FIG. 2. Shown in dotted lines is the corona device and charge collecting plate to indicate the physical connections which are made to implement this circuit in a practical environment.
  • the feedback resistor R which is selected to be much smaller than R, and the impedence of C, discussed with reference to FIGS. 1 and 2 is connected as another arm of the bridge.
  • the reservoir R is connected into the current return path of the power supply in order to measure corona charging current.
  • the remaining arms of the bridge are formed by the capacitor C and the variable resistor R Capacitor C and resistor R are added to obtain the necessary compensating signal and to complete the bridge circuit.
  • the AC. power supply 5 is connected across the bridge in the conventional fashion and a high impedence voltmeter is coupled between the nodes A and B on the bridge to provide a reading of the condition thereof.
  • the nodes A and B of the bridge are also coupled to the input terminals of an amplifier 16 via conductors l4 and 15.
  • the amplifier 16 generates a signal on line 17 which is feed back to the control terminal of the power supply 5 to thereby maintain a constant corona current by varying the voltage supplied by the source in response to the output of the bridge.
  • the bridge is first balanced by setting the power supply to a magnitude below the corona onset voltage and varying R until a minimum or zero.reading is noted on the voltmeter. The same effect may be obtained by using a fixed R and a variable C Once balanced, the bridge will remain in this condition until the power supply voltage exceeds the corona onset value.
  • the current through the CBD side of the bridge i.e., through C, and R will be different than, but in phase with the current through the CAD side of the bridge (C and R).
  • the voltage across C will equal the voltage across C and the drop across R, will equal to the drop across'R Since R was selected to be much smaller than R, and X most of the applied voltage will be dropped across C, and R,.
  • the current in R is increased by the amount of the corona current and the voltage drop across R is greater than that across R, by the amount of the corona current drop across R
  • This voltage difference appears across the nodes A and B and may be used as a control signal to hold the corona current constant by feedback to the control terminal of the power supply. Since this voltage change is small, an amplifier 16 is used to step it up before application to the variable supply.
  • the true corona current value may be determined by dividing the voltmeter reading by the value of resistance R, and in this way the corona charging current may be adjusted accurately during the initial set up of the machine.
  • said corona charging current may be determined from the measured value of said imbalance and the value of said first resistor.
  • a method of holding constant the corona charging current output of an A.C. corona discharge device comprising forming an electrical bridge having input nodes and ouput nodes, said bridge including said device and a first resistor in series with each other across said input nodes, and a capacitor and second resistor in series with each other connected across said input nodes, said capacitor and corona device forming adjacent arms of the bridge,

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Electromagnetism (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Automation & Control Theory (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Measurement Of Current Or Voltage (AREA)
  • Elimination Of Static Electricity (AREA)
  • Control Or Security For Electrophotography (AREA)
US511831A 1974-10-03 1974-10-03 Corona current measurement and control arrangement Expired - Lifetime US3908164A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US511831A US3908164A (en) 1974-10-03 1974-10-03 Corona current measurement and control arrangement
GB2204475A GB1467935A (en) 1974-10-03 1975-05-22 Corona current measurement and control arrangement
NL7510460A NL7510460A (nl) 1974-10-03 1975-09-04 Corona-stroom meet- en regelschakeling.
DE19752539400 DE2539400A1 (de) 1974-10-03 1975-09-04 Verfahren zur konstanthaltung des abgegebenem korona-ladungsstroms einer wechselstrom-korona-entladungseinrichtung und brueckenschaltung zur durchfuehrung des verfahrens
CA234,998A CA1033805A (en) 1974-10-03 1975-09-08 Corona current measurement and control arrangement
JP50116260A JPS5163662A (en) 1974-10-03 1975-09-26 Koronadenryusokutei oyobi seigyosochi
FR7530436A FR2287045A1 (fr) 1974-10-03 1975-10-03 Appareil de mesure et de commande de courant corona

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US511831A US3908164A (en) 1974-10-03 1974-10-03 Corona current measurement and control arrangement

Publications (1)

Publication Number Publication Date
US3908164A true US3908164A (en) 1975-09-23

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US511831A Expired - Lifetime US3908164A (en) 1974-10-03 1974-10-03 Corona current measurement and control arrangement

Country Status (7)

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US (1) US3908164A (enrdf_load_stackoverflow)
JP (1) JPS5163662A (enrdf_load_stackoverflow)
CA (1) CA1033805A (enrdf_load_stackoverflow)
DE (1) DE2539400A1 (enrdf_load_stackoverflow)
FR (1) FR2287045A1 (enrdf_load_stackoverflow)
GB (1) GB1467935A (enrdf_load_stackoverflow)
NL (1) NL7510460A (enrdf_load_stackoverflow)

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4028596A (en) * 1974-12-13 1977-06-07 Coulter Information Systems, Inc. Corona power supply circuit
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
WO1983004108A1 (en) * 1982-05-20 1983-11-24 P.A. Management Consultants Limited State of charge indicator
US4528499A (en) * 1981-10-24 1985-07-09 Hewlett-Packard Gmbh Modified bridge circuit for measurement purposes
US5055269A (en) * 1989-03-06 1991-10-08 Bacharach, Inc Temperature limited catalytic gas detector apparatus
US5229818A (en) * 1990-09-14 1993-07-20 Canon Kabushiki Kaisha Image forming apparatus having a high voltage power source for a contact charger
US5359393A (en) * 1992-12-22 1994-10-25 Xerox Corporation Method and apparatus for measuring photoreceptor voltage potential using a charging device
US6034368A (en) * 1998-07-06 2000-03-07 Xerox Corporation AC corona current regulation
US20030115002A1 (en) * 2001-06-21 2003-06-19 Xerox Corporation Method of determining a resistive current
US20050093532A1 (en) * 2003-11-04 2005-05-05 Adlerstein Michael G. Broadband microwave power sensor
US20050094708A1 (en) * 2003-11-04 2005-05-05 Adlerstein Michael G. Integrated thermal sensor for microwave transistors
US20050279398A1 (en) * 2004-06-18 2005-12-22 Herrick Katherine J Microstrip power sensor
US20100253360A1 (en) * 2009-04-03 2010-10-07 Xerox Corporation Corona effluent sensing device
CN103048519A (zh) * 2012-12-12 2013-04-17 华北电力大学 一种电晕初始电流的测量装置及方法
CN103250312A (zh) * 2010-12-07 2013-08-14 3M创新有限公司 用于离子平衡测量和调节的具有隔离的电容器电路的离子化平衡装置
US9404945B2 (en) 2011-12-08 2016-08-02 Desco Industries, Inc. Ionization monitoring device
CN112730929A (zh) * 2021-03-30 2021-04-30 南京菲迈斯智能科技有限公司 一种多功能电力物联网测量传感器

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3604925A (en) * 1968-12-03 1971-09-14 Zerox Corp Apparatus for controlling the amount of charge applied to a surface
US3763410A (en) * 1971-09-17 1973-10-02 Du Pont Method of treating material by electrical discharge

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3604925A (en) * 1968-12-03 1971-09-14 Zerox Corp Apparatus for controlling the amount of charge applied to a surface
US3763410A (en) * 1971-09-17 1973-10-02 Du Pont Method of treating material by electrical discharge

Cited By (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4028596A (en) * 1974-12-13 1977-06-07 Coulter Information Systems, Inc. Corona power supply circuit
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
US4528499A (en) * 1981-10-24 1985-07-09 Hewlett-Packard Gmbh Modified bridge circuit for measurement purposes
WO1983004108A1 (en) * 1982-05-20 1983-11-24 P.A. Management Consultants Limited State of charge indicator
EP0095344A1 (en) * 1982-05-20 1983-11-30 Comtech Research Unit Limited Method of monitoring electrostatic charge deposition
US5055269A (en) * 1989-03-06 1991-10-08 Bacharach, Inc Temperature limited catalytic gas detector apparatus
US5229818A (en) * 1990-09-14 1993-07-20 Canon Kabushiki Kaisha Image forming apparatus having a high voltage power source for a contact charger
US5359393A (en) * 1992-12-22 1994-10-25 Xerox Corporation Method and apparatus for measuring photoreceptor voltage potential using a charging device
US6034368A (en) * 1998-07-06 2000-03-07 Xerox Corporation AC corona current regulation
US20030115002A1 (en) * 2001-06-21 2003-06-19 Xerox Corporation Method of determining a resistive current
US6777959B2 (en) * 2001-06-21 2004-08-17 Xerox Corporation Method of determining a resistive current
US20050093532A1 (en) * 2003-11-04 2005-05-05 Adlerstein Michael G. Broadband microwave power sensor
US20050094708A1 (en) * 2003-11-04 2005-05-05 Adlerstein Michael G. Integrated thermal sensor for microwave transistors
WO2005045449A1 (en) * 2003-11-04 2005-05-19 Raytheon Company Broadband microwave power sensor
US7030600B2 (en) 2003-11-04 2006-04-18 Raytheon Company Broadband microwave power sensor
US6991367B2 (en) 2003-11-04 2006-01-31 Raytheon Company Integrated thermal sensor for microwave transistors
US20050279398A1 (en) * 2004-06-18 2005-12-22 Herrick Katherine J Microstrip power sensor
US7670045B2 (en) 2004-06-18 2010-03-02 Raytheon Company Microstrip power sensor
US20100253360A1 (en) * 2009-04-03 2010-10-07 Xerox Corporation Corona effluent sensing device
US20120081134A1 (en) * 2009-04-03 2012-04-05 Xerox Corporation Corona effluent sensing device
US8159236B2 (en) * 2009-04-03 2012-04-17 Xerox Corporation Corona effluent sensing device
US8786290B2 (en) * 2009-04-03 2014-07-22 Xerox Corporation Corona effluent sensing device
CN103250312A (zh) * 2010-12-07 2013-08-14 3M创新有限公司 用于离子平衡测量和调节的具有隔离的电容器电路的离子化平衡装置
US9588161B2 (en) 2010-12-07 2017-03-07 Desco Industries, Inc. Ionization balance device with shielded capacitor circuit for ion balance measurements and adjustments
US9404945B2 (en) 2011-12-08 2016-08-02 Desco Industries, Inc. Ionization monitoring device
CN103048519A (zh) * 2012-12-12 2013-04-17 华北电力大学 一种电晕初始电流的测量装置及方法
CN103048519B (zh) * 2012-12-12 2015-01-07 华北电力大学 一种电晕初始电流的测量装置及方法
CN112730929A (zh) * 2021-03-30 2021-04-30 南京菲迈斯智能科技有限公司 一种多功能电力物联网测量传感器

Also Published As

Publication number Publication date
JPS6253779B2 (enrdf_load_stackoverflow) 1987-11-12
FR2287045B1 (enrdf_load_stackoverflow) 1979-03-09
FR2287045A1 (fr) 1976-04-30
GB1467935A (en) 1977-03-23
JPS5163662A (en) 1976-06-02
CA1033805A (en) 1978-06-27
NL7510460A (nl) 1976-04-06
DE2539400A1 (de) 1976-05-13

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