US3783352A - Developing method for electrophotography - Google Patents

Developing method for electrophotography Download PDF

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Publication number
US3783352A
US3783352A US00276368A US3783352DA US3783352A US 3783352 A US3783352 A US 3783352A US 00276368 A US00276368 A US 00276368A US 3783352D A US3783352D A US 3783352DA US 3783352 A US3783352 A US 3783352A
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United States
Prior art keywords
developing
developing electrode
corona
latent image
electrode
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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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US00276368A
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English (en)
Inventor
I Soma
Y Ando
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Canon Inc
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Canon Inc
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Publication date
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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
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
    • Y10S430/001—Electric or magnetic imagery, e.g., xerography, electrography, magnetography, etc. Process, composition, or product
    • Y10S430/102—Electrically charging radiation-conductive surface

Definitions

  • This invention relates to'a method which uses a de-- veloping electrode to develop an electrostatic latent image formed by an electrophotography, electrostatic recording or other process, and more particularly to a method of insulating the developing electrode from other charging electrodes to thereby prevent such electrode from being excessively charged by those other electrodes.
  • the developing effect may vary with such factors as the state of the electrostatic latent image on the photosensitive medium, the distance between the photo-sensitive medium and the developing electrode, the voltage applied to the developing electrode, etc., and it is difficult to correlate such factors and accordingly to ensure that an excellent development is achieved.
  • the state of the electrostatic latent image is variable with extraneous factors such as ambient temperature and humidity, thus making it difficult to obtain a uniform developing effect.
  • FIG. 1 illustrates an example of the electrophotographic process to which the present invention is applicable
  • FIG. 2 is a view illustrating the effect of the developingelectrode insulated from others.
  • FIGS. 3 and 4 illustrate embodiments of the present invention.
  • a drum 1 comprises a three-layer photosensitive medium consisting of a dielectric layer 2, a photoconductive layer 3 and a conductive substrate 4.
  • a primary charger 5 Around the drum 1 there are disposed a primary charger 5, a corona charger 6 for use during the effecting of an exposure on drum 1, a developing electrode 7 and a charger 8 for transferring a developed image to a transfer medium.
  • an electrostatic latent image having dark areas of positive polarity by using an N-type-semi-conductor such as CdS with the above-described arrangement and to develop such an image by means of toner of negative polarity, fogging of the developed image by applying a bias to the developing electrode 7 so as to provide a potential which is positive with respect to the surface potential on the light areas of the image.
  • the dark areas of the image may be developed in accordance with the differ ence between the potential of the electrostatic latent image on the photosensitive medium and the potential of the developing electrode.
  • the potential of the developing electrode Since the potential of the developing electrode is predetermined, the density of the image will be varied if the potential of the latent image on the photosensitive medium is varied with variations in environmental factors (especially temperature and humidity). This would raise difficulties in setting the potential of the electrostatic latent image.
  • a charge will be induced on the developing electrode in accordance with the potential of the latent image on the photosensitive medium and thus, the charge on the entire developing electrode will be balanced with respect to the positive and negative polarities.
  • the potential of the developing electrode may always be maintained between the potential of the light areas of the latent image and the potential of the dark areas of the latent image.
  • FIG. 2 illustrates such self-bias effect.
  • numeral 11 designates the conductive substrate, 12 the photoconductive layer, 13 the dielectric layer, and 14 the developing electrode. It should be understood that the conductive substrate 11 is grounded and the developing electrode is insulated from others. If an electrostatic latent image a of positive polarity, for example, exists on the surface of the dielectric layer, a charge b of negative polarity will be induced on the corresponding portion of the developing electrode 14. However, since the developing electrode 14 is a conductive material insulated from others as described previously, a charge 0 of different polarity from the induced charge b will be produced on the other portion of the developing electrode than that portion in which the induced charge b exists, thus nullifying the charge on the entire developing electrode.
  • the charge c will in turn induce a charge d in the portion of the photosensitive layer which corresponds to the portion of the electrode carrying the charge 0.
  • the developing toner (which may be of negative polarity if a positive image is to be provided) will be attracted from the photosensitive layer toward the developing electrode to thereby prevent said portion of the photosensitive medium from being developed, thus providing a fogless, excellent image.
  • the present invention prevents corona ions from being applied to the developing electrode insulated from others, thereby ensuring a fogless, clear image to be obtained.
  • Various methods of blocking the flow of corona ions may come to mind, but a simple and inexpensive method will be described hereunder.
  • An insulating member may be disposed in the path of the corona ions flowing to the developing electrode so that the insulating member may be charged with the corona ions to repulse any further corona ions thereafter and thus prevent them from reaching the developing electrode.
  • FIG. 3 illustrates a specific arrangement for achieving such a result.
  • a corona-ion shield member 31 formed of insulative material is interposed between the charger 6 and the developing electrode 7. Any corona ion moving from the charger 6 toward the developing electrode 7 may thus be blocked by the shield member 31 and cannot reach the electrode 7.
  • the shielding effect for the corona ions depends on the distance from the shield member 31 to the outermost surface of the photosensitive medium 1, and a distance of mm or less has empirically been found practical. Most preferably, the distance may be 2 mm or less.
  • the shield member 31 may be disposed between the transfer charger 8 and the developing electrode 7 to block the corona ions from the charger 8.
  • Another shield means of insulative material may be provided adjacent to the charger 8, as indicated at 32.
  • the insulative member 32 located adjacent to the transfer charger 8 may be well charged to repulse the corona ions and thus, it is highly effective to prevent the tendency of corona ions to flow toward the developing electrode 7.
  • the shield members 31 and 32 may be reversed. If these shield members are formed of a conductive material, they may be grounded to attract corona ions or alternatively may be ungrounded so as to be charged in a manner similar to the insulative material, thereby repulsingsubsequent corona ions with a result that a good corona-ion shielding effect is achieved.
  • the shield members may be formed not only of an insulative material but also of a conductive material.
  • a method of preventing undesirable charging of the developing electrode comprising the steps of insulating said developing electrode to permit a self-bias to be induced thereon during developing of a said electrostatic latent image, and shielding said developing electrode from said corona discharge electrodes to prevent ions produced by said corona discharge electrodes from affecting the self-bias produced on said developing electrode.
  • a developing device for use in an electrophotographic apparatus including a device for carrying an electrostatic latent image, and at least one corona discharge device for use in producing a photocopy on said apparatus, the improvement comprising: an insulated developing electrode, and means mounting said developing electrode in a face-to-face relationship with a said electrostatic image carried on said carrier device wherein a self-bias is effected on said developing electrode due to its close proximity to a said electrostatic latent image; means for supplying a developer between said carrier and said developing electrode; and coronaion shielding means disposed between said corona discharge device and said developing electrode for preventing corona-ions generated by said corona discharge device from being deposited on said developing electrode.
  • a developing device for use in electrophotography wherein said corona-ion shielding means extends outwardly from said carrier device and is disposed within 5 mm of the surface of said carrier device which bears said electrostatic latent image.
  • a developing device wherein said corona-ion shielding means is formed of an insulative material.
  • corona-ion shielding means is formed of an insulated conductive materialf 6.
  • corona-ion shielding means is formed of v a grounded conductive material.
  • a developing device wherein said corona-ion shielding means is disposed adjacent to said corona discharge device.
  • a developing device for use in an electrophotographic apparatus including a device for carrying an electrostatic latent image, and at least one corona discharge device for use in producing a photocopy on said apparatus, the improvement comprising: an insulated developing electrode, and means mounting said developing electrode in a faceto-face relationship with a said electrostatic image carried on said carrier device wherein a self-bias is effected on said developing electrode due to its close proximity to a said electrostatic latent image; means for supplying a developer between said carrier and said developing electrode; and means for blowing air into the space between said developing bias effect is unaffected by said ions.
  • Patent No. ,783352 Dated January 1, 1974 Inventor) IKI JO SOMA, ET AL. T It is certified that error appears in the above-identified patent and that; said Letters Patentare hereby corrected a s shownbelow: Column 1, line 32, after "That is” insert Column 2, line .15, after “image” insert ma y be avoided-w T Column 3, line 64, "member” should read '-member:s--.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Dry Development In Electrophotography (AREA)
  • Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
  • Electrophotography Using Other Than Carlson'S Method (AREA)
US00276368A 1971-08-05 1972-07-31 Developing method for electrophotography Expired - Lifetime US3783352A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP46059146A JPS4826140A (en, 2012) 1971-08-05 1971-08-05

Publications (1)

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US3783352A true US3783352A (en) 1974-01-01

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US00276368A Expired - Lifetime US3783352A (en) 1971-08-05 1972-07-31 Developing method for electrophotography

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US (1) US3783352A (en, 2012)
JP (1) JPS4826140A (en, 2012)
AU (1) AU471512B2 (en, 2012)
DE (1) DE2238491C2 (en, 2012)
GB (1) GB1403535A (en, 2012)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3866096A (en) * 1972-09-28 1975-02-11 Commw Of Australia Charging photoconductive membranes
US4115114A (en) * 1972-09-21 1978-09-19 La Cellophane Electrostatic charge image transfer
RU2329452C2 (ru) * 2006-07-17 2008-07-20 Игорь Павлович Пыленок Пружина вакуум - блочное метательное оружие

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5267642A (en) * 1975-12-03 1977-06-04 Canon Inc Image forming apparatus

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2684902A (en) * 1951-11-23 1954-07-27 Haloid Co Image transfer mechanism for electrostatically adhering images
US3543023A (en) * 1966-11-21 1970-11-24 Gaf Corp Method of establishing an electrical charge on a conductive interlayer unconnected to a potential source
US3620617A (en) * 1969-11-24 1971-11-16 Ibm Electrophotographic apparatus with improved toner transfer

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2790082A (en) * 1955-08-01 1957-04-23 Haloid Co Xerographic charging device
US3219014A (en) * 1962-12-04 1965-11-23 Xerox Corp Mechanical shield to protect magnetic core in xerographic developing apparatus

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2684902A (en) * 1951-11-23 1954-07-27 Haloid Co Image transfer mechanism for electrostatically adhering images
US3543023A (en) * 1966-11-21 1970-11-24 Gaf Corp Method of establishing an electrical charge on a conductive interlayer unconnected to a potential source
US3620617A (en) * 1969-11-24 1971-11-16 Ibm Electrophotographic apparatus with improved toner transfer

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4115114A (en) * 1972-09-21 1978-09-19 La Cellophane Electrostatic charge image transfer
US3866096A (en) * 1972-09-28 1975-02-11 Commw Of Australia Charging photoconductive membranes
RU2329452C2 (ru) * 2006-07-17 2008-07-20 Игорь Павлович Пыленок Пружина вакуум - блочное метательное оружие

Also Published As

Publication number Publication date
AU471512B2 (en) 1976-04-29
AU4517272A (en) 1974-02-07
JPS4826140A (en, 2012) 1973-04-05
DE2238491A1 (de) 1973-03-01
GB1403535A (en) 1975-08-28
DE2238491C2 (de) 1985-01-03

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