US3620798A - Development of latent electrostatic image employing novel development electrode - Google Patents

Development of latent electrostatic image employing novel development electrode Download PDF

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Publication number
US3620798A
US3620798A US698229A US3620798DA US3620798A US 3620798 A US3620798 A US 3620798A US 698229 A US698229 A US 698229A US 3620798D A US3620798D A US 3620798DA US 3620798 A US3620798 A US 3620798A
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United States
Prior art keywords
insulator
electrostatic image
latent electrostatic
developing
photoconductive
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
US698229A
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English (en)
Inventor
Satoru Honjo
Yasuo Tamai
Masamichi Sato
Seiji Matsumoto
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.)
Fujifilm Holdings Corp
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Fuji Photo Film Co Ltd
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 Fuji Photo Film Co Ltd filed Critical Fuji Photo Film Co Ltd
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Publication of US3620798A publication Critical patent/US3620798A/en
Anticipated expiration legal-status Critical
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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
    • G03G15/10—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer

Definitions

  • the present invention relates to a process of developing a latent electrostatic image, wherein more developing particles are caused to adhere to an area of lower charge density in a pattern of charges formed on the surface of an insulator, and no developing particles are caused to adhere to a maximum charge density area.
  • a developing method which comprises applying to a developing electrode a DC voltage which is the same as the surface potential at a maximum charge density area of a latent electrostatic image and generating an electric field proportional to the difference of charge densities on a lower charged area between the developing electrode and insulator.
  • the surface potential of a latent electrostatic image on an insulator is dark attenuated with the passage of time. Since the characteristics of this dark attenuation are too complex to be determined by a time constant, and difl'er markedly with the kind of the insulator and ambient state, it is very difficult to change the voltage to be applied to a developing electrode in accordance with the dark attenuation.
  • the feature of the invention consists in the steps of facing, across a fine clearance, an insulator having a latent electrostatic image and another insulator for electric field controlling, having the same polarity as said insulator, uniform charges and characteristics substantially similar to the dark attenuation characteristics of said insulator, under the developing condition, and feeding developing particles having the same polarity as that of said latent electrostatic image to the clearance, whereby to develop said latent electrostatic image.
  • FIG. I and FIG. 2 are schematic side views of apparatus suitable for carrying out the invention.
  • Developing particles are spouted into this space from means 5 for charging and spouting developing particles.
  • developing particles spouted in the form of an aerosol from developing particle feed nozzle 6 are charged, in the same polarity as that of the charges forming the latent electrostatic image, by corona discharge of an annular high voltage electrode 8 to which a high voltage is applied by high voltage power source 7, and then are supplied or scattered in the developing space through nozzle 9.
  • the developing particles adhere to a lower charge density area of the charges forming the latent electrostatic image on light-sensitive paper 1 by electrostatic attraction but do not adhere to a maximum charge density area of the latent electrostatic image.
  • conductive plate 4 and conductive plate 2 may be grounded, as shown in FIG. I, or electrically insulated completely in some case.
  • both of the supports should be insulated electrically to give a better result.
  • light-sensitive paper 3 having the same characteristics as light-sensitive paper I to be developed is used, after charging as an insulator for electric field regulating in place of a developing electrode to which an external voltage is applied, so their surface potentials are similarly attenuated irrespective of the atmosphere. Therefore, the surface potential of light-sensitive paper 3 and the potential of a maximum charge density area of the latent electrostatic image on lightsensitive paper I are always equal and the developing is thus completed in the best state.
  • a maximum charge density area of the latent electrostatic image is also somewhat illuminated. Consequently, the surface potential is lower than before the image exposure.
  • electrophotographic light-sensitive paper 11 having a latent electrostatic image and uniformly charged light-sensitive paper 13 of the same kind are faced at a very small, constant interval.
  • Both of said light-sensitive papers are carried by conductive, perforated suction plates I2, I4 mounted on casings I7, 18 and pressure-reduced by suction pump (not shown) via pipes 15, I6.
  • Suction plates I2, 14 may be insulating or conducting, or both may be electrically connected.
  • the state of electric field in the developing space between light-sensitive papers ll, 13 is similar to that of FIG. I and the latent electrostatic image of light-sensitive paper 11. Dark attenuation of the surface potential of the photoconductive insulator in liquid developer 21 is larger than in the air, which is therefore suitable for the invention.
  • a latent electrostatic image is formed on a photoconductive insulator by the projection method in the foregoing two examples, not only photoconductive insulators but also mere insulators may be used as the insulator on which the latent electrostatic image is formed.
  • a method of forming a latent electrostatic image it has been well-known to form a latent electrostatic image on a uniformly charged photoconductive insulator according to the quantity of irradiation, to utilize discharge, induction or polarization on an insulator, to transfer a latent electrostatic image formed on an insulator to another insulator by ionization of air, to charge directly an insulator by electron beam, etc. Our developing process is available for all latent electrostatic images formed by these methods.
  • any insulator may be employed so far as it has a dark attenuation character similar to an insulator on which a latent electrostatic image is formed. Since, if a photoconductive insulator used as an insulator for electric field regulating is repeatedly used, its characteristics fluctuate, it is preferred to make it exchangeable in the case of continuously carrying out developing.
  • the used part is subjected to dark adaptation to stabilize the characteristic and rolled up, in particular, after drying adequately when using a liquid developer, followed by reusing, after a constant time.
  • an insulator having no photoconductive properties is preferably used.
  • its dark attenuation characteristic must be made similar to that of an insulator to be developed by adjusting its insulating property suitably.
  • a photoconductive insulator consisting essentially of a photoconductive powder and insulating resin
  • the same resin is used as a main component of the insulating material and the resistance is controlled with a suitable low resistance component and filler. It is thereby made easy to use the insulator repeatedly as an insulator for electric field regulating. Thus, a good development can be expected even if taking no notice of a small difference between the characteristics of an insulator having a latent electrostatic image and insulator for electric field regulating.
  • the best developing can be carried out always by suitably varying the quantity of charge on one of the insulators.
  • a fog-free, complete development of a latent electrostatic image can be accom plished by the use of an insulator for electric field regulating, having the same action as the conventional developing electrode to which an external voltage is applied and capable of denying influences of the attenuation of a latent electrostatic image to be developed in place of such developing electrode.
  • an insulator for electric field regulating and an insulator having suitable characteristics results in marked advantages, such as, reducing the influence of temperature, humidity, etc.
  • a process of reversely developing a latent electrostatic image which comprises facing across a small clearance a photoconductive insulator having a latent electrostatic image and another insulator for electric field regulating, said another insulator having l the same polarity as said photoconductive insulator, (2) uniform charges such as that the electric field emanating therefrom is substantially equal to or less than the electric field emanating from the area of maximum charge density of said latent electrostatic image and (3) dark attenuation characteristics substantially similar to the dark attenuation characteristics of said photoconductive insulator under the developing condition, and feeding developing particles having the same polarity as that of said latent electrostatic image to the clearance, whereby to reversely develop said latent electrostatic image.
  • a process as in claim 1 including the step of first transferring said latent electrostatic image to a further insulator having dark attenuation characteristics substantially similar to those of said another insulator and then reversely developing said latent electrostatic image in accordance with the remaining steps of claim 1.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Dry Development In Electrophotography (AREA)
  • Wet Developing In Electrophotography (AREA)
  • Electrophotography Configuration And Component (AREA)
US698229A 1967-01-18 1968-01-16 Development of latent electrostatic image employing novel development electrode Expired - Lifetime US3620798A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP42003496A JPS5244203B1 (is") 1967-01-18 1967-01-18

Publications (1)

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US3620798A true US3620798A (en) 1971-11-16

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US698229A Expired - Lifetime US3620798A (en) 1967-01-18 1968-01-16 Development of latent electrostatic image employing novel development electrode

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US (1) US3620798A (is")
JP (1) JPS5244203B1 (is")
BE (1) BE709410A (is")
DE (1) DE1622349A1 (is")
FR (1) FR1552425A (is")
GB (1) GB1186841A (is")

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3731655A (en) * 1970-03-14 1973-05-08 Int Standard Electric Corp Apparatus for marking insulated electrical conductors
US3844783A (en) * 1970-12-28 1974-10-29 Fuji Photo Film Co Ltd Electrophotographic process including a color masking operation
US3963487A (en) * 1970-12-14 1976-06-15 Fuji Photo Film Co., Ltd. Electrophotographic process using separate photoconductive elements

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54174613U (is") * 1978-05-31 1979-12-10

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2817765A (en) * 1956-01-03 1957-12-24 Haloid Co Xerographic method
US2817598A (en) * 1955-02-01 1957-12-24 Haloid Co Continuous tone reversal development process
US2899331A (en) * 1955-01-25 1959-08-11 Process of developing electrostatic

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2899331A (en) * 1955-01-25 1959-08-11 Process of developing electrostatic
US2817598A (en) * 1955-02-01 1957-12-24 Haloid Co Continuous tone reversal development process
US2817765A (en) * 1956-01-03 1957-12-24 Haloid Co Xerographic method

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3731655A (en) * 1970-03-14 1973-05-08 Int Standard Electric Corp Apparatus for marking insulated electrical conductors
US3963487A (en) * 1970-12-14 1976-06-15 Fuji Photo Film Co., Ltd. Electrophotographic process using separate photoconductive elements
US3844783A (en) * 1970-12-28 1974-10-29 Fuji Photo Film Co Ltd Electrophotographic process including a color masking operation

Also Published As

Publication number Publication date
GB1186841A (en) 1970-04-08
FR1552425A (is") 1969-01-03
JPS5244203B1 (is") 1977-11-05
BE709410A (is") 1968-05-30
DE1622349A1 (de) 1970-10-29

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