US3800154A - Method and apparatus for forming a uniform surface potential on photosensitive member - Google Patents

Method and apparatus for forming a uniform surface potential on photosensitive member Download PDF

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Publication number
US3800154A
US3800154A US00184867A US18486771A US3800154A US 3800154 A US3800154 A US 3800154A US 00184867 A US00184867 A US 00184867A US 18486771 A US18486771 A US 18486771A US 3800154 A US3800154 A US 3800154A
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current
corona
corona discharge
dielectric member
power source
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US00184867A
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S Tanaka
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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
    • G03G15/0266—Arrangements for controlling the amount of charge

Definitions

  • a dielectric member is charged by rectifying part of either the positive or negative current output of a corona discharge device by applying the rectified output current to at least one corona wire mounted in spaced relationship with respect to the dielectric member.
  • the positive or negative current is varied so that the effective current in the dielectric member is substantially zero whereby the surface potential of the dielectric member is made uniform.
  • the means for controlling the output current of the corona discharge device is a parallel connection of a variable resistance and a diode.
  • the present invention relates to both a method and apparatus for charging a photosensitive body or insulator in ele'ctrophotographic apparatus utilizing the characteristic of alternating corona discharge, and more particularly to such a method and apparatus which comprises controlling either positive or negative current in the alternating current corona discharge, controlling the charge of a photosensitive plate by utilizing the automatic balance of the surface potential of the photosensitive body or insulator with the corona current, and adjusting the surface potential.
  • One object of the present invention is to remove the above faults in the prior art, thereby providing charging method and apparatus for placing a uniform charge on a photosensitive body or insulator by means of alternating corona discharge.
  • Another object of the present invention is to provide such a method and apparatus for arresting either the positive current or negative current of the corona alternating current thereby making it possible to adjust the surface potential of the photosensitive plate.
  • Still another object of the present invention is to provide such a method and apparatus for arresting part of either the positive current or negative current in the corona alternating current, controlling the arrested current and thereby controlling the charge on the photosensitive plate.
  • the present invention employs a corona discharge device connected to a high-voltage alternating power source, and by means of a controlling member controls either the positive current or negative current of the corona alternating current for, controlling the charge fromed on the photosensitive plate by utilizing the automatic balancing of the surface potential of the photosensitive body or insulator by the corona current.
  • the surface potential of the photosensitive plate is uniform, thereby making it possible to adjust the surface potential to the desired value.
  • FIG. 1 (A) The relation between the corona voltage and corona current of the alternating corona discharge is shown in FIG. 1 (A) and FIG. 1 (B) illustrates a measuring circuit.
  • FIG. 2 (A) illustrates three characteristic waveforms of the corona current with the corona voltage constant and with different surface potentials of the electrode plate
  • FIG. 2 (B) shows the relationship between the corona current ic and the electrode plate potential Vp in the upper set of curves and the relationship between the effective current I and the same potential in the lower set of curves
  • FIG. 2 (C) is a measuring circuit.
  • FIG. 3 shows characteristic curves of the corona current with respect to variable corona voltage.
  • FIG. 4 is a characteristic curve diagram showing the relation between the corona volage and the saturation surface potential of the electrode plate (the potential at the intersection point of the positive corona current and the negative corona current in FIG. 3).
  • FIG. 5 shows the charging speed as a function of the corona voltage.
  • FIG. 6 shows the various curves of the negative corona currents as a function of variable corona voltage where only the negative corona current is controlled.
  • FIG. 7 (A) is a circuit which operates in accordance with the principle on which the present invention is formed
  • FIG. 7 (B) is an equivalent circuit diagram of the circuit shown in 7 (A) above.
  • FIG. 8 is a circuit diagram of one embodiment of the present invention.
  • the corona current of the corona discharge device to which a high-voltge alternating current is applied via a boosting transformer T from the alternating power source AC was measured by a synchroscope S used for the observation of two phenomena as shown in FIG. 1(3).
  • the wave forms are as shown in FIG. 1 (A) and the negative current wave forms are greater than the positive current wave forms.
  • FIG. 2 (C) With an AC corona voltage applied to the corona discharge device C, and the electrodeplate P biased at a voltage by the DC power source E, the measured corona current with respect to the different bias potentials of the electrodeplate P is illustrated in FIG. 2 (A).
  • the electrode plate P bias potential changes to -200V, V and +200V, the positive current becomes smaller, whereas the negative current becomes larger.
  • the effective current I falls to zero at the surface potential corresponding to the intersection point q. This shows that if there is a dielectric membrane on the electrodeplate P, that membrane is charged to a fixed surface potential Vq by means of alternating corona discharge, but at the voltage Vq the corona current balances automatically and the membrane is not charged further.
  • the charging speed at which the dielectric on the electrodeplate P is charged is illustrated by a graph, it is as shown in FIG. 5.
  • This graph shows that relative to all corona voltages the surface potential of the dielectric is charged in the form of curves as in FIG. 5 until it is charged to the automatically balancing surface potential, and further, that when it is above the automatically balancing surface potential it is saturated, and when it is kept within the limits of its surface potential it is controlled by means of the corona voltage.
  • control of the surface potential when the control of the surface potential is considered from FIG. 3, it may be shown that the control of the corona voltage results in the control of the corona currents, and if the corona currents are controlled, it is possible to control said the automatically balancing surface potential. Also, it may be known in FIG. 3 that, as regards the control of corona currents, if either positive current or negative current is controlled, it is sufficient and that both of them need not be controlled.
  • FIG. 7 (A) indicates the principle structure of the present invention utilizing the above mentioned phenomena, in which a control circuit comprising a parallel connection of a variable resistor V and a rectifier D are connected in the ground circuit of the secondary winding of a boosting transformer T. Connected in series with the control circuit to the other end of the secondary winding is the corona wire of a corona discharge device C. The electrodeplate P is grounded, and if the equivalent resistance of the corona discharge device C and the electrodeplate P is expressed as R the equivalent circuit is as shown in FIG. 7 (B).
  • the equivalent resistance R of the corona discharge device C varies according to some conditions, such as the form and size of device C, the space between the device and the electrodeplate P, and applied corona voltage, but since the above equivalent resistance has a fixed value in the case where the above conditions are fixed, it is possible to consider only the equivalent resistance of the device.
  • the above equivalent resistance has a fixed value in the case where the above conditions are fixed, it is possible to consider only the equivalent resistance of the device.
  • the equivalent resistance R since there is a difference in the mobility between positive and negative ions, at the time when the positive voltage is applied to the equivalent resistance R and at the time when negative voltage is applied to the resistance equivalent resistance R is different.
  • a sine wave alternating input is applied to the above equivalent resistance R it is necessary to consider R, as a function of time.
  • FIG. 8 illustrates an example of the present invention which embodies the principle structure of the present invention as shown in FIG. 7 (A).
  • Corona discharge device C is provided with two corona wires W and W each 200 mm in length, and which are suspended respectively in the center of and within shield frame g and h which are 22 mm in width.
  • Intermediate stabilizing plate f isinterposed between the wires which are suspended at a distance of l 1 mm from the upper part of the frames.
  • Grounded electrodeplate P is mounted at a distance of mm from the wires.
  • One end of the 799 secondary coil of the boosting transformer T is c onnected to the alternating power source A was connected to the above corona wires W, and W and to the other end of the above secondary coil the variable resistance V whose resistance value may be changed up to a maximum of 500 K O, and the commutating element D in parallel with the variable resistance V R are connected and grounded.
  • dielectric H which is 5 ,u. thick, and has a dielectric constant of 2.5 is mounted on the electrodeplate P and an alternating corona discharge is effected with the resistance value of the variable resistance V set to zero Q, a saturation surface potential of -30OV is obtained on dielectric H within approximately 2 seconds.
  • the present invention can form a uniform charge onto the photosensitive plate by means of the alternating corona discharge of the corona discharge device using a high-voltage alternating power source. Also the charge is fixed by the automatic balancing characteristics of the alternating corona discharge, and exactly the same surface potential set in advance can be formed without regard to the kind of photosensitive plate used by controlling either the positive current or the negative current of the alternating corona current. Moreover because controlling either the positive current or the negative current as mentioned above is sufficient control the apparatus is very simple, inexpensive and yet durable as compared with such commutating elements as variable resistors, di-
  • the invention with respect to either the positive residual charge or the negative residual charge left on the photosensitive plate it is possible to charge the surface potential uniformly and as desird, and therefore, in cases where a photosensitive plate is used repeatedly as in Xerography, the invention can do without the process of removing charge and any charge removing device. additionally, the invention affords a different gradation of copies by the adjustment of the variable resistance.
  • a device for charging a dielectric member in an electrophotographic device comprising:
  • a corona discharge device including at least a corona wire connected to one pole of said high-voltage alternating power source;
  • an electrode plate connectable to the other pole of said high-voltage alternating power source for supporting said dielectric member thereon facing said corona wire with a gap therebetween so as to make a corona discharge circuit through said dielectric member;
  • control means including rectifier means and variable resistor means connected in parallel with each other to said other pole whereby said rectifier means provides a DC current of one polarity and said variable resistor means provides a DC balancing current of the opposite polarity through said corona discharge circuit.
  • a method for controlling the charging of a dielectric member in an electrophotographic device comprising the steps of:
  • variable resistor means connected to said alternating power source in parallel with said rectifying means

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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)
  • Electrostatic Separation (AREA)
US00184867A 1970-10-02 1971-09-29 Method and apparatus for forming a uniform surface potential on photosensitive member Expired - Lifetime US3800154A (en)

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JP45086860A JPS4937864B1 (nl) 1970-10-02 1970-10-02

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JP (1) JPS4937864B1 (nl)
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3921042A (en) * 1974-11-25 1975-11-18 Xerox Corp Electrostatic reproduction machine with improved corona generating device
US3942080A (en) * 1974-04-05 1976-03-02 Scott Paper Company Method and apparatus for applying a uniform electrostatic charge to electrophotographic film
US3976880A (en) * 1975-10-29 1976-08-24 Xerox Corporation Corona stabilization arrangement
US4731633A (en) * 1987-04-27 1988-03-15 Xerox Corporation Elimination of streamer formation in positive charging corona devices
USRE35581E (en) * 1986-12-15 1997-08-12 Canon Kabushiki Kaisha Charging device

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5712986B2 (nl) * 1972-07-31 1982-03-13
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
CA1116227A (en) * 1977-03-07 1982-01-12 Bell & Howell Company Controlled corona for charging electrostatic photocopy paper having zno binder layer
JPS5422837A (en) * 1977-07-21 1979-02-21 Ricoh Co Ltd Charge control of copying apparatus for zerography
JPS54139736A (en) * 1978-04-21 1979-10-30 Sharp Corp Electrophotographic copier
JPS54167854U (nl) * 1978-05-17 1979-11-27
JPS56146156A (en) * 1980-04-15 1981-11-13 Sharp Corp Charging system in electrophotography
JPS5997161A (ja) * 1982-11-27 1984-06-04 Olympus Optical Co Ltd 電子写真方法
DE102022101193B4 (de) 2022-01-19 2023-11-30 Illinois Tool Works Inc. Ionisator und Verfahren zum Neutralisieren von Ladungen auf Oberflächen

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2879395A (en) * 1955-06-08 1959-03-24 Haloid Xerox Inc Charging device
US3076092A (en) * 1960-07-21 1963-01-29 Xerox Corp Xerographic charging apparatus
US3196270A (en) * 1962-07-31 1965-07-20 Union Carbide Corp Treating of plastic surfaces
US3515548A (en) * 1966-03-16 1970-06-02 Zenith Radio Corp Charging process for electrostatic screening of color tubes

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL302691A (nl) * 1963-01-04 1900-01-01
JPS4110931Y1 (nl) * 1964-07-31 1966-05-23
JPS4116589Y1 (nl) * 1964-07-31 1966-08-01
JPS439999Y1 (nl) * 1965-09-20 1968-04-30
JPS439997Y1 (nl) * 1965-09-20 1968-04-30

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2879395A (en) * 1955-06-08 1959-03-24 Haloid Xerox Inc Charging device
US3076092A (en) * 1960-07-21 1963-01-29 Xerox Corp Xerographic charging apparatus
US3196270A (en) * 1962-07-31 1965-07-20 Union Carbide Corp Treating of plastic surfaces
US3515548A (en) * 1966-03-16 1970-06-02 Zenith Radio Corp Charging process for electrostatic screening of color tubes

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3942080A (en) * 1974-04-05 1976-03-02 Scott Paper Company Method and apparatus for applying a uniform electrostatic charge to electrophotographic film
US3921042A (en) * 1974-11-25 1975-11-18 Xerox Corp Electrostatic reproduction machine with improved corona generating device
US3976880A (en) * 1975-10-29 1976-08-24 Xerox Corporation Corona stabilization arrangement
USRE35581E (en) * 1986-12-15 1997-08-12 Canon Kabushiki Kaisha Charging device
US4731633A (en) * 1987-04-27 1988-03-15 Xerox Corporation Elimination of streamer formation in positive charging corona devices

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Publication number Publication date
JPS4937864B1 (nl) 1974-10-12
DE2149119B2 (de) 1979-05-31
DE2149119A1 (de) 1972-04-20
DE2149119C3 (de) 1980-02-07

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