US3843906A - Method of reducing the generation of ozone - Google Patents

Method of reducing the generation of ozone Download PDF

Info

Publication number
US3843906A
US3843906A US00342625A US34262573A US3843906A US 3843906 A US3843906 A US 3843906A US 00342625 A US00342625 A US 00342625A US 34262573 A US34262573 A US 34262573A US 3843906 A US3843906 A US 3843906A
Authority
US
United States
Prior art keywords
corona
screen
voltage
voltage source
wires
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
US00342625A
Inventor
K Leibrecht
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.)
Kalle GmbH and Co KG
Original Assignee
Kalle GmbH and Co KG
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 Kalle GmbH and Co KG filed Critical Kalle GmbH and Co KG
Application granted granted Critical
Publication of US3843906A publication Critical patent/US3843906A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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

  • ABSTRACT An apparatus for the reduction in the generation of ozone during the discharge of corona wires which includes the wire surrounded on three sides by a screen and on the fourth side by a surface accepting a charge with a possible grid arranged in front of the surface. The method involves connecting the screen to 21 voltage between that of the support of the charge accepting surface and that of the corona wire.
  • the present invention relates to a method of reducing the generation of ozone during the discharge of corona wires which are surrounded on three sides by a screen and on the fourth side by a surface accepting the charge and possibly also by a grid arranged in front of this surface.
  • Corona discharge apparatuses are used for many purposes in the electrophotographic field. Devices equipped with a control grid are used for uniformly charging the photoconductor. Further, corona devices are used for cleaning the photoconductor and for transferring the toner image onto paper.
  • corona discharge devices have the serious drawback that such high energy is imparted in the electric field to the charge thus produced, that large quantities of ozone are generated. Moreover, only a small proportion of the current sprayed by the corona wire flows onto the surface accepting the charge,-whereas the main portion flows to the screen. In this manner, the power-supply units are unduly stressed.
  • an apparatus for charging a photoconductor has been described in which the corona wire is completely surrounded by a screen except for a small slot.
  • a voltage between the voltage of the corona wire and the voltage of the photoconductor, normally earth, may be applied to this screen.
  • Such a screen causes a very poor yield of current and serves only the function performed by the grid in other charging devices, i.e., to produce uniform charging of the layer to a defined voltage.
  • the current yield i.e., the ratio between the amount of current collected and utilized and the amount of current emitted by the corona wire, is kept particularly low by this intermediate voltage, which is highly undesirable. It causes in particular a very extensive and very annoying production of ozone.
  • a device of this type is described, e.g., in US. Pat. No. 2,817,765.
  • the screen is connected to a voltage which lies between that of the charge accepting surface or its support and that of the corona wire.'ln corona devices of conventional structure, the voltage of the screen may amount to about one-fourth to one-half of the corona wire voltage.
  • the current emitted by the corona wires may be considerably reduced by this method, without substantially diminishing the portion of current which is utilized, e.g., applied to the'photoconductor.
  • a first voltage source for the corona wire or wires a second voltage source for the grid
  • a third voltage source which is or may be electrically connected to the screen and whose voltage is between that of the first voltage source and the reference voltage.
  • FIG. 1 is a diagrammatic representationof the apparatus according to the invention.
  • FIG. 2 is a diagram of the currents measured.
  • FIG. 1 shows a sectional view of a corona discharge apparatus in which the actually utilized current is measured as a function of the screen voltage.
  • the apparatus comprises three corona wires 1 of 50 p. thick tungsten which are surrounded on three sides by a screen 2.
  • a grid 3 is arranged beneath the corona wires, and under the grid 3 there is a collector electrode 4.
  • the screen 2 is connected to an adjustable voltage source 5, the corona wires are connected over a milliammeter 6 to a voltage source 7, the grid 3 is connected to a voltage source 8, and the collector electrode is connected over a milliammeter 9 to ground.
  • the currents measured are shown in FIG. 2.
  • the hyperbolalike curves 0.1. 1 represent the currents of the corona wires 1 as measured by the milliammeter 6. For the sake of clarity, these curves are drawn as multiplied by 0.l. It can be seen that the current emitted by the corona device decreases rapidly with a decrease in the voltage U of the screen. At a screen voltage of only -2,200 V, the current 1 of the corona has dropped to less than half of its original value.
  • the current l measured on the collector electrode 4 first increases slightly, as compared with the current produced with the screen grounded when a voltage is applied to the screen 2, and that in the case of a corona wire voltage of 8 kV and a grid voltage of l,000 V it reaches its original value at a screen voltage U of 2,200 V.
  • the current yield i.e., the ratio between the current which is collected and utilized, and the current emitted by the corona'device, was improved by a factor of more than 2.'Consequently, the generation of ozone was reduced by this factor.
  • T he'potential of the screen causes a modification in the intensity of the field at the surface of the corona wire 2, especially in the sector facing the screen.
  • This change in the intensity of the field causes the substantial decrease of the current actually emitted by the wires '1, which can be seen from the'hyperbola-like curves" 0.1. 1,.
  • thisphenomenon With regard to the current I arriving at the electrode 4, thisphenomenonis superimposed by an effect which is due to the higher potential 'of the screen and causes part of the charges emitted by the corona wire 1 in the direction of the screento be deelectrode, and with it the emissiomdecreases to such an extent that the deflecting effect of the screen potential is overcome.
  • the curve representing the cur rent emitted by the corona wire will start at an acute angle from the ordinate and will rapidly decline with increasing screen potential, whereas the current curve of the collector electrode starts substantially horizontally from the ordinate and declines with increasing screen voltage only after the current at the corona wire has already dropped to half of its original value.
  • the method of the present invention has the considerable advantage that it increases the yield.
  • charging devices of simpler construction and power-supply units of smaller size may be used.
  • Corona discharge apparatus comprising,
  • a grid arranged between a photoconductor layer and the fourth, open, side of the screen, with the corona wires, the screen, and the grid. being electrically insulated from each other,
  • a third voltage source for the screen the voltage of the latter lying between the voltage of the first voltage source and that of a photoconductor support.
  • Corona discharge apparatus in which the corona wires consist of 50 u thick tungsten wire, the first voltage source supplies from *6 to -8 kV, the second voltage source supplies between -600 and l,000 V, and the third voltage source supplies about -2 kV.

Abstract

An apparatus for the reduction in the generation of ozone during the discharge of corona wires which includes the wire surrounded on three sides by a screen and on the fourth side by a surface accepting a charge with a possible grid arranged in front of the surface. The method involves connecting the screen to a voltage between that of the support of the charge accepting surface and that of the corona wire.

Description

. United States Patent m1 Leibrecht METHOD OF REDUCING THE GENERATION OF OZONE [75] Inventor: Klaus Leibrecht,l l0fl1eim,'Germany [73] Assignee: Kalle Aktiengesellschaft,
, Wiesbaden-Biebrich, Germany 221 Filed: Mar. 19, 1973 21 Appl. No: 342,625
[30] Foreign Application Priority Data Oct. 22, 1974 Primary ExaminerL. T. l-lix Attorney, Agent, or FirmStevens, Davis, Miller & Mosher 5 7] ABSTRACT An apparatus for the reduction in the generation of ozone during the discharge of corona wires which includes the wire surrounded on three sides by a screen and on the fourth side by a surface accepting a charge with a possible grid arranged in front of the surface. The method involves connecting the screen to 21 voltage between that of the support of the charge accepting surface and that of the corona wire.
2 Claims, 2 Drawing Figures METHOD OF REDUCING THE GENERATION OF OZONE The present invention relates to a method of reducing the generation of ozone during the discharge of corona wires which are surrounded on three sides by a screen and on the fourth side by a surface accepting the charge and possibly also by a grid arranged in front of this surface.
Corona discharge apparatuses are used for many purposes in the electrophotographic field. Devices equipped with a control grid are used for uniformly charging the photoconductor. Further, corona devices are used for cleaning the photoconductor and for transferring the toner image onto paper.
These corona discharge devices have the serious drawback that such high energy is imparted in the electric field to the charge thus produced, that large quantities of ozone are generated. Moreover, only a small proportion of the current sprayed by the corona wire flows onto the surface accepting the charge,-whereas the main portion flows to the screen. In this manner, the power-supply units are unduly stressed.
Further, an apparatus for charging a photoconductor has been described in which the corona wire is completely surrounded by a screen except for a small slot. A voltage between the voltage of the corona wire and the voltage of the photoconductor, normally earth, may be applied to this screen. Such a screen, however, causes a very poor yield of current and serves only the function performed by the grid in other charging devices, i.e., to produce uniform charging of the layer to a defined voltage. The current yield, i.e., the ratio between the amount of current collected and utilized and the amount of current emitted by the corona wire, is kept particularly low by this intermediate voltage, which is highly undesirable. It causes in particular a very extensive and very annoying production of ozone. A device of this type is described, e.g., in US. Pat. No. 2,817,765.
It is the object of the present invention to provide'a process of the above described type in which the amount of current emitted by the corona and, consequently, the amount of ozone generated, are kept as low as possible without the portion of utilized current becoming too small.
This object is achieved by a method which is characterized in that the screen is connected to a voltage which lies between that of the charge accepting surface or its support and that of the corona wire.'ln corona devices of conventional structure, the voltage of the screen may amount to about one-fourth to one-half of the corona wire voltage.
As has been found, the current emitted by the corona wires may be considerably reduced by this method, without substantially diminishing the portion of current which is utilized, e.g., applied to the'photoconductor.
ranged at the open side of the'screen, which three units are electricallyinsulated from one another, and further comprises a first voltage source for the corona wire or wires, a second voltage source for the grid, and, as the inventive feature, a third voltage source which is or may be electrically connected to the screen and whose voltage is between that of the first voltage source and the reference voltage.
The present invention and the advantages thereof will be described more in detail by reference to the drawing in which,
FIG. 1 is a diagrammatic representationof the apparatus according to the invention, and
FIG. 2 is a diagram of the currents measured.
FIG. 1 shows a sectional view of a corona discharge apparatus in which the actually utilized current is measured as a function of the screen voltage. The apparatus comprises three corona wires 1 of 50 p. thick tungsten which are surrounded on three sides by a screen 2. A grid 3 is arranged beneath the corona wires, and under the grid 3 there is a collector electrode 4.
The screen 2 is connected to an adjustable voltage source 5, the corona wires are connected over a milliammeter 6 to a voltage source 7, the grid 3 is connected to a voltage source 8, and the collector electrode is connected over a milliammeter 9 to ground.
The currents measured are shown in FIG. 2. The hyperbolalike curves 0.1. 1 represent the currents of the corona wires 1 as measured by the milliammeter 6. For the sake of clarity, these curves are drawn as multiplied by 0.l. It can be seen that the current emitted by the corona device decreases rapidly with a decrease in the voltage U of the screen. At a screen voltage of only -2,200 V, the current 1 of the corona has dropped to less than half of its original value. it was found, however, that the current l,, measured on the collector electrode 4, first increases slightly, as compared with the current produced with the screen grounded when a voltage is applied to the screen 2, and that in the case of a corona wire voltage of 8 kV and a grid voltage of l,000 V it reaches its original value at a screen voltage U of 2,200 V. This means that in this case the current yield, i.e., the ratio between the current which is collected and utilized, and the current emitted by the corona'device, was improved by a factor of more than 2.'Consequently, the generation of ozone was reduced by this factor.
Similar results were obtained when using other corona voltages and other grid voltages. This also can be seen from FIG. 2. The curves drawn in broken lines were obtained by using a grid voltage U of -l ,000 V., and the solid line curves were obtained by using a grid voltage U of V. It is evident from all the curves, that a screen voltage in the range of one-fourth to onehalf of the voltage at the corona wire causes a considerable improvement of the current yield and thus substaritially and advantagesouly reduces the generation of ozone.
Although not wishing to be so bound it is assumed that this phenomenon occurs as follows:
T he'potential of the screen causes a modification in the intensity of the field at the surface of the corona wire 2, especially in the sector facing the screen. This change in the intensity of the field causes the substantial decrease of the current actually emitted by the wires '1, which can be seen from the'hyperbola-like curves" 0.1. 1,. With regard to the current I arriving at the electrode 4, thisphenomenonis superimposed by an effect which is due to the higher potential 'of the screen and causes part of the charges emitted by the corona wire 1 in the direction of the screento be deelectrode, and with it the emissiomdecreases to such an extent that the deflecting effect of the screen potential is overcome.
The exact shape of the curves is dependent on the geometrical arrangement of the corona apparatus, the
voltage of the corona wires, and the voltage of the, grid. In all cases, however, the curve representing the cur rent emitted by the corona wire will start at an acute angle from the ordinate and will rapidly decline with increasing screen potential, whereas the current curve of the collector electrode starts substantially horizontally from the ordinate and declines with increasing screen voltage only after the current at the corona wire has already dropped to half of its original value.
In addition to the reduced generation of ozone in such charging devices, the method of the present invention has the considerable advantage that it increases the yield. Thus, charging devices of simpler construction and power-supply units of smaller size may be used.
What is claimed is: g
1. Corona discharge apparatus comprising,
a. at least one corona wire,
b. an electrically conductive screen which surrounds the corona wire or wires on three sides,
c. a grid arranged between a photoconductor layer and the fourth, open, side of the screen, with the corona wires, the screen, and the grid. being electrically insulated from each other,
d. a first voltage source for the corona wire or wires,
e. a second voltage source for the grid, and
f. a third voltage source for the screen, the voltage of the latter lying between the voltage of the first voltage source and that of a photoconductor support.
2. Corona discharge apparatus according to claim 1, in which the corona wires consist of 50 u thick tungsten wire, the first voltage source supplies from *6 to -8 kV, the second voltage source supplies between -600 and l,000 V, and the third voltage source supplies about -2 kV.

Claims (2)

1. Corona discharge apparatus comprising, a. at least one corona wire, b. an electrically conductive screen which surrounds the corona wire or wires on three sides, c. a grid arranged between a photoconductor layer and the fourth, open, side of the screen, with the corona wires, the screen, and the grid being electrically insulated from each other, d. a first voltage source for the corona wire or wires, e. a second voltage source for the grid, and f. a third voltage source for the screen, the voltage of the latter lying between the voltage of the first voltage source and that of a photoconductor support.
2. Corona discharge apparatus according to claim 1, in which the corona wires consist of 50 Mu thick tungsten wire, the first voltage source supplies from -6 to -8 kV, the second voltage source supplies between -600 and -1,000 V, and the third voltage source supplies about -2 kV.
US00342625A 1972-03-20 1973-03-19 Method of reducing the generation of ozone Expired - Lifetime US3843906A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2213419A DE2213419A1 (en) 1972-03-20 1972-03-20 METHODS FOR REDUCING OZONE PRODUCTION

Publications (1)

Publication Number Publication Date
US3843906A true US3843906A (en) 1974-10-22

Family

ID=5839478

Family Applications (1)

Application Number Title Priority Date Filing Date
US00342625A Expired - Lifetime US3843906A (en) 1972-03-20 1973-03-19 Method of reducing the generation of ozone

Country Status (7)

Country Link
US (1) US3843906A (en)
JP (1) JPS498240A (en)
AU (1) AU464794B2 (en)
DE (1) DE2213419A1 (en)
FR (1) FR2176915A1 (en)
GB (1) GB1405337A (en)
NL (1) NL7303359A (en)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4038583A (en) * 1974-05-09 1977-07-26 Jacques Leon Georges Breton Apparatus for the generation of negative or positive atmospheric ions
US4227233A (en) * 1976-10-01 1980-10-07 Olympus Optical Company Limited Corona discharge device for electrographic apparatus
EP0016842A1 (en) * 1978-07-11 1980-10-15 Ricoh Company, Ltd Corona discharge device
US4239373A (en) * 1978-11-01 1980-12-16 Xerox Corporation Full wave rectification apparatus for operation of DC corotrons
US4285025A (en) * 1978-05-31 1981-08-18 Olympus Optical Company Ltd. Corona charger
US4574326A (en) * 1984-03-09 1986-03-04 Minolta Camera Kabushiki Kaisha Electrical charging apparatus for electrophotography
US5087944A (en) * 1989-05-31 1992-02-11 Kabushiki Kaisha Toshiba Image forming apparatus with control means for the surface potential of a photosensitive body
US20060193657A1 (en) * 2005-02-28 2006-08-31 Xerox Corporation Xerographic charging device having three pin arrays
US20070147858A1 (en) * 2005-12-27 2007-06-28 Brother Kogyo Kabushiki Kaisha Image forming apparatus

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2611503C2 (en) * 1975-04-28 1986-09-04 Xerox Corp., Rochester, N.Y. Electrostatic copier
JPS5825661A (en) * 1981-08-07 1983-02-15 Ricoh Co Ltd Electrostatic charger
JPS5972067A (en) * 1982-10-18 1984-04-23 Toshiba Corp Detector for abnormality of electrifier
JPS59208563A (en) * 1983-05-02 1984-11-26 ゼロツクス・コ−ポレ−シヨン Minicorotron

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3611074A (en) * 1969-11-24 1971-10-05 Ibm Corona discharge device

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3611074A (en) * 1969-11-24 1971-10-05 Ibm Corona discharge device

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4038583A (en) * 1974-05-09 1977-07-26 Jacques Leon Georges Breton Apparatus for the generation of negative or positive atmospheric ions
US4227233A (en) * 1976-10-01 1980-10-07 Olympus Optical Company Limited Corona discharge device for electrographic apparatus
US4285025A (en) * 1978-05-31 1981-08-18 Olympus Optical Company Ltd. Corona charger
EP0016842A1 (en) * 1978-07-11 1980-10-15 Ricoh Company, Ltd Corona discharge device
EP0016842A4 (en) * 1978-07-11 1980-11-14 Ricoh Kk Corona discharge device.
US4239373A (en) * 1978-11-01 1980-12-16 Xerox Corporation Full wave rectification apparatus for operation of DC corotrons
US4574326A (en) * 1984-03-09 1986-03-04 Minolta Camera Kabushiki Kaisha Electrical charging apparatus for electrophotography
US5087944A (en) * 1989-05-31 1992-02-11 Kabushiki Kaisha Toshiba Image forming apparatus with control means for the surface potential of a photosensitive body
US20060193657A1 (en) * 2005-02-28 2006-08-31 Xerox Corporation Xerographic charging device having three pin arrays
US7149458B2 (en) * 2005-02-28 2006-12-12 Xerox Corporation Xerographic charging device having three pin arrays
US20070147858A1 (en) * 2005-12-27 2007-06-28 Brother Kogyo Kabushiki Kaisha Image forming apparatus
US7620335B2 (en) * 2005-12-27 2009-11-17 Brother Kogyo Kabushiki Kaisha Image forming apparatus

Also Published As

Publication number Publication date
AU464794B2 (en) 1975-09-04
GB1405337A (en) 1975-09-10
AU5339073A (en) 1974-10-10
NL7303359A (en) 1973-09-24
JPS498240A (en) 1974-01-24
DE2213419A1 (en) 1973-10-04
FR2176915A1 (en) 1973-11-02

Similar Documents

Publication Publication Date Title
US3843906A (en) Method of reducing the generation of ozone
US2868989A (en) Electrostatic charging method and device
ZA834028B (en) Lightning conductor construction
US3813549A (en) Self-healing electrode for uniform negative corona
US3611074A (en) Corona discharge device
JPS5895363A (en) Corona discharging device for electrophotographic device
US4775915A (en) Focussed corona charger
US3783283A (en) Corona charging device with semiconductive shield
US6205309B1 (en) AC corona charging arrangement with current—limiting capacitor
US3598991A (en) Electrostatic charging device having a spark gap voltage regulator between a corona source and a voltage source
GB1205040A (en) Negative corona device
US4227233A (en) Corona discharge device for electrographic apparatus
US5526222A (en) Background recharging scorotron
US3967119A (en) Corona charging device
US3880514A (en) Ion producing source for electrostatic recording apparatus
US3873895A (en) Technique for charging dielectric surfaces to high voltage
JPH1064659A (en) Phase modulated corona electric charger
JPH04233561A (en) Blade-type printer without arc
JP3690497B2 (en) Scorotron charger
JPH1010843A (en) Scanning corotron
US1620732A (en) Therapy x-ray system
JPH01159672A (en) Scorotron electrostatic charger
US4430686A (en) Charger for electrographic surfaces
Stringer et al. Excitation of coaxial and twinaxial cables by high intensity X-rays: Source term calculations
SU1223197A1 (en) Device for charging electrographic medium