US3760152A - Corona discharge device for removing dielectric liquid - Google Patents

Corona discharge device for removing dielectric liquid Download PDF

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Publication number
US3760152A
US3760152A US00229540A US3760152DA US3760152A US 3760152 A US3760152 A US 3760152A US 00229540 A US00229540 A US 00229540A US 3760152D A US3760152D A US 3760152DA US 3760152 A US3760152 A US 3760152A
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United States
Prior art keywords
shield member
liquid
corona
corona discharge
dielectric
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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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US00229540A
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English (en)
Inventor
T Saito
Y Ando
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Canon Inc
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Canon Inc
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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
    • G03G15/11—Removing excess liquid developer, e.g. by heat
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G21/00—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge
    • G03G21/0088—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge removing liquid developer

Definitions

  • ABSTRACT A device for removing dielectric liquid from a holder member for a photosensitive medium or the like used in an electrophotographic copying machine includes a corona discharging electrode, a shield member substantially surrounding the corona discharging electrode in electrically isolated relationship therewith and having at least a discharge opening, corona discharge converging means provided adjacent to the discharge opening of the shield member, and a power source from which a voltage is applied to the corona discharge electrode.
  • This invention relates to a device for removing dielectric liquid which utilizes corona discharge to remove excess dielectric liquid which may be present on a photosensitive medium or sheet or a transfer medium during the copying process in various types of electrophotography.
  • the dielectric liquid to be removed by the device of the present invention may include excess liquid developer which may be present on a photosensitive medium after an electrostatic latent image formed on the surface thereof is liquiddeveloped but before the developed image is transferred to a transfer medium or which may be present on such transfer medium after the image transfer is done, or cleaning liquid which may be residual on the surface of the photosensitive medium after the developing liquid remaining on the image-transferred photosensitive medium is washed, with the cleaning liquid.
  • the device of the present invention for removing dielectric liquid may also be applicable to remove excess developing liquid which may be present on the surface of a photosensitive sheet after an electrostatic latent image formed thereon is, liquid-developed but before it is fixed.
  • Such adverse effect may be attributable to excess developing liquid which usually may contain at least toner and carrier and which may be residual on the surface of the photosensitive medium after the electrostatic latent image thereon has been developed, and to the fact that some of the toner particles contained in such developing liquid tend to be suspended in the other areas of the photosensitive surface than the image-bearing area thereof and remain fixed to such areas.
  • the aforesaid adverse effect may be attributed to the fact that the suspended toner particles tend to be transferred and fixed to the non-image-bearing portion of the transfer medium during the. image transfer process or to.
  • the amount of developing liquid transferred from the photosensitive medium to the transfer medium may contain a substantial amount of excess carrier, which would generate a great deal of carrier gas when the transfer medium is heated at a dryer, such gas being very harmful hygienically.
  • the prior art has provided squeeze rollers or like means disposed with respect to the photosensitive medium so that the excess developing liquid on the photosensitive medium may be squeezed out after the development process.
  • The. use of such squeeze rollers has necessarily disturbed the formed image in the same way as experienced during the aforesaid image transfer process, and this also holds true with the case wheresimilar squeeze rollers are used to remove the excess developing liquid remaining on the transfer medium.
  • use has heretofore been made of a blade, roller or other means disposed in contact with the surface of the photosensitive medium, but this system has been apt to injure the photosensitive medium and accordingly reduce its service life.
  • the device for removing dielectric liquid according to the present invention will be outlined hereunder.
  • the device of the present invention is applicable in electrophotographic copying machines and intended to remove dielectric liquid from a holder member by applying a corona discharge of any desired polarity to the holder member from one or the other surface thereof, which holder member may include a photosensitive medium or sheet from which a liquid-developed image is to be transferred to other medium and which carries excess developing liquid still left thereon after the liquid development process, a photosensitive medium from which an image is to be transferred to other medium and which carries cleaning liquid still left thereon after washed with the cleaning liquid, and a transfer medium which has received a liquid-developed image and carries excess developing liquid still left thereon.
  • a layer of such residual dielectric liquid is electrically charged progressively from one surface thereof toward the other, to thereby create a concave recess or self-squeezing effect in the liquid surface.
  • the residual liquid may almost completely gather together into a bulged body for ready removal.
  • the corona discharge applied to the developing or the cleaning liquid residual on the surface of a photosensitive medium causes the surface to be also electrically charged, with a resultant strong electric field produced at the end of the charged surface area to further increase the self-squeezing tendency of the liquid and enhance its removal effect.
  • the body of dielectric liquid self-squeezed in this way may then be removed as by suction or other removal means.
  • the polarity of the corona discharge may preferably be the same as the polarity of the toner contained in such liquid. The reason is that the corona discharge of the same polarity as that of the developing toner forces the toner particles against the surface of the photosensitive medium while squeezing the toner particles without disturbing the image on the photosensitive medium.
  • the polarity of the corona discharge applied to the liquid for the removal thereof may be opposite to the polarity of the developing toner, with a good result and without any disturbance imparted to the image.
  • either polarity may be available for a good removal effect, although this depends more or less upon the situation.
  • the polarity of the corona discharge to be applied to such liquid may be freely selected.
  • additional means may be provided as by raising the voltage to be applied to the corona discharging electrode or by disposing the corona wire adjacent to the holder member.
  • additional means will of necessity cause an intensified charge of the photosensitive medium which in turn would cause undesirable effects such as spark discharge, destruction of the dielectric layer in the photosensitive medium, etc. It is thus desirable to achieve a successful squeezing effect of dielectric liquid without resorting to a raised discharge potential.
  • the present invention provides either dielectric members or electrically conductive members electrically isolated from any other member in the vicinity of the discharge opening in the corona discharger, to thereby enable corona discharge to be abruptly effected in a narrow range of area.
  • the charge from the corona discharging electrode to the holder member even if its discharge potential is lower, may be much greater in quantity and intensity and may result in a much better removal effect of the dielectric liquid, than in the case where none of said members is provided in the neighborhood of the corona discharge opening.
  • FIG. 1A is a perspective view of the device for removing dielectric liquid according to an embodiment of the present invention
  • FIG. 1B is a cross-sectional view taken along lines 1-1 of FIG. 1A;
  • FIG. 2A is a perspective view of an improved embodiment of the device for removing dielectric liquid according to the present invention.
  • FIG. 2B is a cross-sectional view taken alsong lines II-II of FIG. 2A;
  • FIGS. 3 and 4 are cross-sectional views showing modifications, respectively, of the FIG. 2 embodiment.
  • FIG. 5 is a schematic view for illustrating the construction of an electrophotographic copying apparatus to which the device of the present invention has been applied.
  • the illustrated device for removing dielectric liquid is substantially the same as the corona discharger which has conventionally been used in an electrophotographic copying apparatus.
  • the device includes a corona discharging electrode 1, a grounded shield member 2 formed with a discharge opening, supporting blocks 3 mounted on the shield member at the opposite ends thereof, and supporting pins 4 provided in the blocks 3 for supporting the corona wire 1 extending therebetween.
  • a high voltage may be applied to the corona wire 1 through a power supply line 5.
  • FIG. 1B which is a cross section taken along lines I-I"of FIG.
  • a holder member for a photosensitive or a transfer medium designated by numeral 6, may be moved in the direction as indicated by arrow.
  • a layer of dielectric or insulative liquid 7, which may be developing liquid or cleaning liquid, is present over the outer surface of the photosensitive or the transfer medium.
  • the device for removing dielectric liquid is disposed with its discharge opening opposed to the dielectric liquid.
  • the corona wire 1 When supplied with a high voltage, the corona wire 1 produces lines of electric force, as designated at 8, which are shown to be relatively wide-angled with respect to the holder member.
  • the corona discharge charges the dielectric liquid over the holder member so that the charges of the same polarity produced in the dielectric liquid repulse one another or an electric field is produced by the charges on the holder member, and this seems to produce a result that the liquid self-squeezes to gather as at 9 for removal.
  • FIGS. 2A and B of which FIG. 2B is a cross section along lines II-II' of FIG. 2A, the parts designated by I, 2, 3, 4 and 5 are substantially the same as those designated by similar numerals in FIG. 1, except that the shield member 2 is provided with dielectric members attached tothe opening edges thereof as by bonding or other means.
  • the dielectric members 10 so attached to the shield member 2 serve to provide a narrower width over which the lines of electric force 8' are produced from the corona discharge electrode 1 onto the holder member, than in the case of FIG. 1.
  • the same voltage as that applied to the discharger of FIG. 1 was experimentally applied to the corona discharging electrode 1 of FIG.
  • the holder member after subjected to such liquid removing operation showed much less of residual liquid than in the case of FIG. 1. This is believed attributable to the fact that-corona discharge is abruptly effected within the reduced width to enhance the removal effect.
  • the dielectric members 10 may be formed of metal or other electrically conductive material, with substantially the same result attained, provided that these members 10 are sufficiently insulated from the grounded shield member 2 and the like.
  • FIGS. 3 and 4 show modifications of the FIG. 2 embodiment.
  • dielectric members 10' are positioned in spaced apart relationship from the opening edges of the shield member 2 and in parallel relationship with the holder member 6. This arrangement has again been found to provide good removal of the dielectric liquid residual on the holder member.
  • dielectric members of rod-like shape are disposed in parallel relationship with the discharger, as indicated at 11, and this arrangement may attain as good a result as that attained by the previous embodiments.
  • the dielectric members 11 may be formed of metal or other electrically conductive material and electrically isolated from the shield member 2, to thereby obtain the same result.
  • an electrostatic latent image may be formed on the outer surface of a drum 16 in a conventional manner.
  • the surface of the photosensitive medium 15 may be uniformly charged by a primary charger I7, subsequently subjected to simultaneous application of image light and secondary charge opposite in polarity to the primary charge or AC corona discharge by a coronadischarge and exposure means 18, and then, if required, subjected to overall exposure at 19 to thereby form an electrostatic latent image on the surface of the photosensitive medium.
  • Such an electrostatic latent image may be developed by a liquid developing device 20, and then the visible image may be transferred onto a transfer medium 21 with the aid of transfer roller 22 and fixed to provide a permanent copy by fixing means. Thereafter, the surface of the photosensitive medium 15 may be washed with cleaning liquid 24 so that it may be reused.
  • the device of the present invention for removing dielectric liquid is designated by numeral 25 and disposed behind the developing device 20 as viewed in the direction of movement of the drum 16, so that the residual developing liquid on the surface of the photosensitive medium may be efficiently removed therefrom in the described manner, without the developed image being disturbed.
  • the removing device is of the type as shwon in FIG. 1 or 2
  • the residual liquid will be caused to bulge or build up locally as indicated at 9 in FIG. 1B, and such bulged or built-up liquid would contact the opposed edge of the device and flow into the hollow of the shield member to stain the same.
  • each corona ion converging member 26 and shield member 27 may be provided between each corona ion converging member 26 and shield member 27 so that the liquid in contact with the converging members 26 may'flow down along these members 26 and thence along a guide 28 for collection into the developer container 20.
  • the formed image on the drum 16 may be fixed either immediately thereafter or after once transferred.
  • both the removal and collection of the dielectric carrier liquid remaining on the photosensitive medium may be achieved with high efficiency and without contaminating the discharger.
  • a device of the present invention may be disposed with respect to the transfer medium, as indicated at 29, to thereby remove the developing liquid from the transfer medium and also facilitate the fixing operation which is to follow.
  • An electrode 30 may be disposed in opposed relationship with the back side of the transfer medium and just below the device 29, and this electrode may be grounded.
  • a device of the present instead of a blade, may be provided as at 31 for removing cleaning liquid from the surface of the photosensitive medium so as to make it suitable for reuse.
  • the width a of the discharge opening in the shield member 2' was 20 mm
  • the distance b between the discharging electrode 1 and the surface of the holder member 6 was 12 mm
  • the distance 0 between the lower edge of the shield member 6 and the surface of the holder member was mm.
  • a voltage of 6.5 KV - was applied to the discharging electrode 1 with the holder member 6 moved at a rate of 16 cm/sec in the direction of arrow and carrying thereon a layer of dielectric liquid (with a resistivity of 10" 0. cm) as thick as approximately 100 microns. The result was that only 20 microns of dielectric liquid was left on the surface of the holder member 6.
  • the width a of the discharge opening in the shield member 2 was 20 mm
  • the width A of the opening defined by the dielectric members 10 was 14 mm
  • the distance b between the discharging electrode and the surface of the holder member was 12 mm
  • the distance 0' between the lower end of the dielectric member and the surface of the holder member was 2 mm.
  • a voltage of 6.5 KV was applied to the discharging electrode 1 with the holder member moved at the same rate and carrying thereon the same layer of dielectric liquid, as in the previous example. As the result, there was left a layer of dielectric liquid as thin as approximately 10 microns on the surface of the holder member.
  • the width a" of the discharge opening in the shield member 2 was 20 mm
  • the width A" of the opening defined by the dielectric members 11 having a diameter of 2 mm was 15 mm
  • the distance b' between the discharging electrode and the holder member was 12 mm
  • the-distance c" between the dielectric members and the holder member was 3 mm.
  • a voltage of +7.0 KV was applied to the discharging electrode with the holder member moved at a rate of 12 cm/sec in the direction of arrow and carrying thereon a layer of dielectric liquid (with a resistivity of 10" 0 cm) as thick as approximately 80 microns.
  • the use of the device of the present invention for removing the dielectric liquid staying on the holder member may lead to the advantages which will be mentioned hereunder.
  • Efficient removal of dielectric liquid may be ensured irrespective of the low voltage applied to the corona discharge wire of the liquid removing device, which in turn leads to the elimination of spark discharge which might otherwise occur on the surface of the photosensitive medium to destroy the dielectric layer thereof, and further to an economical advantage in the cost of operation.
  • the removal of the developing liquid from the surface of the photosensitive medium may be effectively achieved without adversely affecting the toner image which is acting to develop an electrostatic latent image.
  • the last-mentioned effect in particular, has been enhanced by disposing the corona discharge converging members in proximity to the corona discharge opening, thus ensuring that the developed image after subjected to such a removing process is entirely free of fogs.
  • a device for removing dielectric liquid from a holder member for a photosensitive medium or the like comprising, in combination:
  • a shield member means mounting said shield member adjacent to said electrode, said shield member substantially surrounding said electrode in electrically isolated relationship therewith and having at least a discharge opening;
  • corona discharge converging means means mounting said corona discharge converging means adjacent to said discharge opening of said shield number;
  • a power source for applying a voltage to said corona discharge electrode.
  • said shield member is formed of electrically conductive material and grounded.
  • said converging means comprises dielectric members attached to said shield member adjacent to said discharge opening thereof.
  • said converging means comprises dielectric members disposed in spaced apart relationship from said shield member and adjacent to said discharge opening thereof.
  • said converging means comprises electrically conductive members attached to said shield member adjacent to said discharge opening thereof but in electrically isolated relationship from said shield member.
  • said converging means comprises electrically conductive membersdisposed in spaced apart relationship from said shield member and adjacent to said discharge opening thereof but in electrically isolated relationship from said shield member.
  • a device according to claim 1, wherein said power source is an AC source.
  • a device wherein said power source is a DC source.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Cleaning In Electrography (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Wet Developing In Electrophotography (AREA)
US00229540A 1971-03-01 1972-02-25 Corona discharge device for removing dielectric liquid Expired - Lifetime US3760152A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP46010501A JPS524941B1 (enrdf_load_stackoverflow) 1971-03-01 1971-03-01

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US3760152A true US3760152A (en) 1973-09-18

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US00229540A Expired - Lifetime US3760152A (en) 1971-03-01 1972-02-25 Corona discharge device for removing dielectric liquid

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US (1) US3760152A (enrdf_load_stackoverflow)
JP (1) JPS524941B1 (enrdf_load_stackoverflow)
BE (1) BE780019A (enrdf_load_stackoverflow)
CA (1) CA952576A (enrdf_load_stackoverflow)
DE (1) DE7207653U (enrdf_load_stackoverflow)
FR (1) FR2127878A5 (enrdf_load_stackoverflow)
GB (1) GB1389854A (enrdf_load_stackoverflow)
IT (1) IT948755B (enrdf_load_stackoverflow)
NL (1) NL7202700A (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2739104A1 (de) * 1976-12-03 1978-06-08 Canon Kk Elektrophotographische nasskopiervorrichtung
US5152838A (en) * 1989-01-17 1992-10-06 Polaroid Corporation Coating fluid drying apparatus
US5668921A (en) * 1994-10-14 1997-09-16 Essler; Karl-Hermann Hot-air dryer with infrared heater and slit-shaped outlet
US20150291006A1 (en) * 2012-10-24 2015-10-15 Audi Ag Heating device for the vehicle interior of a motor vehicle

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1203175B (it) 1978-03-22 1989-02-15 Cantelli Paolo Apparecchio per la neutralizzazione di cariche elettrostatiche e per l asportazione della polvere da oggetti vari
JPH0173515U (enrdf_load_stackoverflow) * 1987-11-05 1989-05-18

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1686865A (en) * 1925-09-12 1928-10-09 Klotz Alfred Electric-heat applicator
US2867912A (en) * 1956-05-11 1959-01-13 Horace Dawson Method for the decontamination of metal foils
US3098143A (en) * 1960-02-24 1963-07-16 Reemtsma H F & Ph Perforating apparatus
US3348022A (en) * 1964-08-26 1967-10-17 Grace W R & Co Perforating film by electrical discharge
US3358378A (en) * 1965-04-19 1967-12-19 Thilmany Pulp & Paper Company Method and apparatus for measurement of moisture
US3619562A (en) * 1970-01-22 1971-11-09 Gen Motors Corp Movable reflector infrared heater

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1686865A (en) * 1925-09-12 1928-10-09 Klotz Alfred Electric-heat applicator
US2867912A (en) * 1956-05-11 1959-01-13 Horace Dawson Method for the decontamination of metal foils
US3098143A (en) * 1960-02-24 1963-07-16 Reemtsma H F & Ph Perforating apparatus
US3348022A (en) * 1964-08-26 1967-10-17 Grace W R & Co Perforating film by electrical discharge
US3358378A (en) * 1965-04-19 1967-12-19 Thilmany Pulp & Paper Company Method and apparatus for measurement of moisture
US3619562A (en) * 1970-01-22 1971-11-09 Gen Motors Corp Movable reflector infrared heater

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2739104A1 (de) * 1976-12-03 1978-06-08 Canon Kk Elektrophotographische nasskopiervorrichtung
US4161361A (en) * 1976-12-03 1979-07-17 Canon Kabushiki Kaisha Wet type electrophotographic apparatus
US5152838A (en) * 1989-01-17 1992-10-06 Polaroid Corporation Coating fluid drying apparatus
US5668921A (en) * 1994-10-14 1997-09-16 Essler; Karl-Hermann Hot-air dryer with infrared heater and slit-shaped outlet
US20150291006A1 (en) * 2012-10-24 2015-10-15 Audi Ag Heating device for the vehicle interior of a motor vehicle
US10137759B2 (en) * 2012-10-24 2018-11-27 Audi Ag Heating device for the vehicle interior of a vehicle

Also Published As

Publication number Publication date
NL7202700A (enrdf_load_stackoverflow) 1972-09-05
DE2209597B2 (de) 1976-04-29
DE7207653U (de) 1977-02-17
IT948755B (it) 1973-06-11
BE780019A (fr) 1972-08-29
CA952576A (en) 1974-08-06
DE2209597A1 (de) 1972-09-14
GB1389854A (en) 1975-04-09
JPS524941B1 (enrdf_load_stackoverflow) 1977-02-08
FR2127878A5 (enrdf_load_stackoverflow) 1972-10-13

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