US3285740A - Electrophotographic process - Google Patents

Electrophotographic process Download PDF

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Publication number
US3285740A
US3285740A US147538A US14753861A US3285740A US 3285740 A US3285740 A US 3285740A US 147538 A US147538 A US 147538A US 14753861 A US14753861 A US 14753861A US 3285740 A US3285740 A US 3285740A
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US
United States
Prior art keywords
layer
photoconductive
image
charge
photoconductor
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
US147538A
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English (en)
Inventor
John W Weigl
Alan B Amidon
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.)
GAF Chemicals Corp
R Q O HOLDING CO Inc
Original Assignee
General Aniline and Film Corp
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 General Aniline and Film Corp filed Critical General Aniline and Film Corp
Priority to US147538A priority Critical patent/US3285740A/en
Priority to GB39118/62A priority patent/GB971281A/en
Priority to DEG36204A priority patent/DE1293589B/de
Application granted granted Critical
Publication of US3285740A publication Critical patent/US3285740A/en
Assigned to R Q O HOLDING COMPANY INC reassignment R Q O HOLDING COMPANY INC ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: GAF CORPORATION
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/02—Charge-receiving layers
    • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
    • G03G5/06—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being organic
    • G03G5/0622—Heterocyclic compounds
    • G03G5/0624—Heterocyclic compounds containing one hetero ring
    • G03G5/0627—Heterocyclic compounds containing one hetero ring being five-membered
    • G03G5/0633—Heterocyclic compounds containing one hetero ring being five-membered containing three hetero atoms
    • 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
    • G03G15/22—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/02—Charge-receiving layers
    • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
    • G03G5/06—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being organic
    • G03G5/0601—Acyclic or carbocyclic compounds
    • G03G5/0605—Carbocyclic compounds
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/02—Charge-receiving layers
    • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
    • G03G5/06—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being organic
    • G03G5/0601—Acyclic or carbocyclic compounds
    • G03G5/0609—Acyclic or carbocyclic compounds containing oxygen
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/02—Charge-receiving layers
    • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
    • G03G5/06—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being organic
    • G03G5/0664—Dyes
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/02—Charge-receiving layers
    • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
    • G03G5/06—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being organic
    • G03G5/0664—Dyes
    • G03G5/0666—Dyes containing a methine or polymethine group
    • G03G5/0668—Dyes containing a methine or polymethine group containing only one methine or polymethine group
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/02—Charge-receiving layers
    • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
    • G03G5/08—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being inorganic
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/10—Bases for charge-receiving or other layers
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/14—Inert intermediate or cover layers for charge-receiving layers
    • G03G5/142—Inert intermediate layers

Definitions

  • This invention relates to improvements in electrophotography and, more particularly, to a method and apparatus for establishing electrical conductivity on a surface of photoconductive insulating layers, such as are conmonly used in electrostatic electrophotography.
  • photoconductive layer such as a dispersion of photoconductive Zinc oxide in an insulating resinous binder, coated over a conductive base, such as, for eX- ample, aluminum foil.
  • the electrostatic latent images are then formed by first applying a blanket charge to the face or receptive surface of the photoconductive layer while the hacking is electrically grounded. Thereafter, the face of the photoconductive layer is illuminated with an actinic radiation pattern which causes the surface charge to leak from the free surface of the photoconductive layer towards the conductive base.
  • Electrostatic latent images formed by the patternwise illumination of charged photoconductive layers are generally rendered visible ⁇ by the application thereto of particles of electrostatically charged powder which may be applied as dust clouds, as aerosols, as suspensoids in insulating liquids, or as adsorbates on magnetic particles or electroscopic carrier heads. Thereafter, the powder irnages may be transferred to a suitable receiving sheet or afxed directly to the photoconductive layer by wellknown means.
  • the reason for using a grounded conductive backing is to enable an equivalent image charge, of a polarity opposite to that applied to the free surface of the photoconductive layer, to distribute itself uniformly on the backed surface. This causes the sheet to bear a symmetrical dpole charge rather than a unipolar charge.
  • the image charge layer on the hacking causes the actinically sensitive charge layer on the free face of the photoconductor to be distributed densely and uniformly, and to remain stably attached until discharged by subsequent actinic radiation.
  • the use of a conductive hacking for the photoconductive layer enhances maximal image resolution by permitting lateral motion of image charge through the sheet during latent image formation.
  • the surface charges deposited on the receptive surface are relatively far apart, the mean separation being in the order of 0.1 micron; while at more common surface charge density levels, means separations of 0.2 to 0.3 micron are to be expected. Since charges deposited on an insulating surface tend to be trapped in clusters of 10 to 103 electrons, the actualseparation of surface charges becomes comparable to the thickness of the photoconductor, typically 2 to 10 microns, across which the surface charges face their opposite image charges in the conductive base.
  • a further object o-f the present invention is to provide an improved electrographic process whereby only a portion of the photoconductive insulating layer is rendered semi-conductive during processing.
  • the invention embraces the conditioning of photoconductive insulating materials without conductive hacking, to acquire during normal applications thereof in electrostatic electrophotography, a state of suflicient electrical conductivity on a selected surface, thereby exhibiting r the properties of materials having a conductive base.
  • the conditioning is accomplished by pre-illuminating the back surface of the photoconductive layer with actinic radiation prior to the electrostatic charging thereof.
  • Another object of the invention is to provide a novel combnation of illuminating and charging means whereby the process of the invention may be carried out.
  • FIGURES 1, 2 and 3 are enlarged schematic crosssectional views of a typical electrophotographic sheet
  • FIGURE 4 is a schematic diagrammatic View of one from of an apparatus designed to carry out the process.
  • the back surface of a photoconductive layer is pre-illuminated prior to applying to the front surface thereof an electrostatic charge. It is to be understood that in the material used the support of the photoconductive layer must be translucent or transparent, to the actinic radiation used for the photoconductor in question.
  • the process in accordance with the invention is also applicabl-e to films -of photoconductive material, which are not coated on the support, but are cast in a form of a film of photoconductive substance, the pre-illumination being applied in this case, to the side opposite to that used for the charging device.
  • this pre-illumination step causes a uniform, temporarily -semi-conductive layer to be formed within the photoconductive layer.
  • this semi-conductive layer serves the same purpose as the conductive base, and eliminates the separate coating heretofore employed in conventional processes.
  • this semiconductive layer may be connected, as required, to ground or to other convenient potential by means of suitable contaet devices.
  • the process of the present invention is also useful in various forms of Xerography in which a reusable photoconductive layer is normally backed by ⁇ a separate translucent or opaque member.
  • an external conductive backing may be eliminated 'by pre-illuminating the back of the photoconductor through the translucent member prior to the application of a surface charge.
  • the pre-illumination used in accordance with this invention is preferably of such wavelengths that only a thin semi-conductive layer is caused to form at the back side of the photoconductor.
  • the actinic radiation penetrate 'beyond about the first 10% of the layer thickness. This is easily accomplished, since the most practical photoconductors absorb light very strongly in their intrinsic absorbance regions.
  • the nearultraviolet radiation (200 to 3900 A.U.) provided by a commercial black light fluorescent lamp may be absorbed to an extent of more than 90% by a 0.3 micronthick layer of photoconductive zine oxide.
  • the thickness of useful Zinc oxide electrophotographic layers is usually in excess of about 6 ⁇ microns.
  • Like results may be o'btained by the use of other oommonly used photocondu-ctors, provided they are pre-illuminated in their ntrinsic regions.
  • the partially transmitted actinic radiation acts to decrease image density and contrast in a manner which is undesirable and acoordingly must be avoided. Therefore, pre-illumination from the front or charged side of the photoconductor, while mechanically simple to obtain, is considered ineffective since it would seriously degrade image density .and contrast.
  • the back illumination or pre-illumination is preferably applied just prior to, but not simultaneously with the charging step.
  • the difference in time between the pre-illumination of the photoconductor and the charging step should be limited to the period of time 'of darkness that prevails during which the particular photoconductor used can retain an appreciable fraction of its photoinduced semiconductivity, i.e., the effective duration of its memory from the pre-illumination.
  • the charge carrier mobility, the electron trap density, impurities present, and other electronic parameters of the particular photoconductor used memory periods vary from fraetions of a second to many minutes or even hours.
  • the minimum actinic exposure required to render the back layer of the photoconductor sufiicient-ly conductive for the purposes of the present invention is about equal to the exposure required to form an electrostatic charge latent image on the front surface, corrected for the opacty of the base material, provided the same wavelength range is used.
  • substantially greater exposures, that is, up to 20 times minimum, are not detrimental.
  • the upper limit of the period between the pre-illumination of the photoconductor and the charging steps is set by the memory period of the photoconductor.
  • overlap between the pre-illumination and the charging steps should be minimized in order to provide optimum charge density :and image contrast on the photoconductor. Image density and contrast are deleteriously affected if illumination is continued after charging has ceased.
  • the physical effect obtained in accordance with the present invention is believed to be the formation of a photo-induced, temporarily semi-conductive layer on the back side of the photoconductive insulating member.
  • FIGURES 1, 2 and 3 there is shown a transl ucent hacking material 11 supporting a photoconductive insulating layer 112.
  • the arrows 13 represent the illumination directed onto the hacking 11, which being absor-bed, causes the .formation of a temporarily semiconductive strip 14 on the back surface of the photoconductive insulating layer 12.
  • FIGURE 4 there is shown by way of example, a simple electrophotographic apparatus consisting of conventional Components, except ⁇ for the addition of the pre-illuminating unit so that this app-aratus may operate in accordance with the herein described invention.
  • a continuous Web of electrophotographc material 20 taken from the supply roll 21 passes through the various stages of the apparatus, and is wound up on the finished product roll 22.
  • the phot-oconductive coa-ting -of the web faoes downwardly.
  • the support carrying the photoconductive coating is preferably filmbase material, so as to permit light to pass through to the back surface of the photoconductive coating.
  • any material not opaque to actinic light may serve as such a support.
  • the web 20 may be wound through by any suitable means not shown here, either at a continuo us rate, or in step-by-step mode of operation, depending on the purpose and copying requirement of the apparatus.
  • a contact finger 23 which is electrically at ground potential, and engages the edge of the web 20, the-reby Contacting the photoconductive layer.
  • the purpose of the contact finger 23 is to form a "return circuit to ground fo!? the corona charge -unit 24.
  • the latter may consist of several fine wires 25 running transverse to the web, and con,- nected to a suitable direct circuit power supply as indicated by a block diagram.
  • the pre-illuminating unit 26 may have various forms depending upon the type of illu mination desired, and the intensity requirement.
  • the unit shown here comprises a housing or reflector 27 surrounding a pair of fluorescent tubula-r light sources 28 and 28'.
  • the 'location of the pre-illuminating unit 26 is so -chosen as to be ahead of the charging unit 24, since as explained hereinbefore, pre-illurnination is effected preferably prior to the blanket charging of the receptive surface of the photoconductive material.
  • the photoconductive coating thereof is conditioned to for-m a thin temporary semi-conductive layer facing the insulating support.
  • the 'face side of the photoconductor receives a blanket charge, the temporarily semi-conductive layer at the back acting as a conductive base.
  • the web is now ready for imagewise dischar ging of the ⁇ dipoles so formed, and this is accomplished 'by a suitable projecting unit shown here schematically, by a lens 30 which projects a reflected image from the original 3-1 when the latter is illuminated by the lamps 32 and 33.
  • the web is passed t-o the developing station 35, which by way of llustration, is shown hereto be of the liquid type, consisting of a container 36 filled with insulating liquid 37 in which is Suspended suitable electrostatically charged ton'er particles.
  • Guidng rollers 38 and 39 pass the web around the applicator roller 40 which is immersed in the s ol-uti on 37.
  • Similar guiding rollers 41 and 42 pass the web toward the finished product roll 22.
  • the image is now developed by the adhe-rence of the toner adhereles and is fixed -by the heating unit 43 containing suitable electrical heaters 44 and 45.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Emergency Medicine (AREA)
  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Photoreceptors In Electrophotography (AREA)
  • Electrophotography Using Other Than Carlson'S Method (AREA)
US147538A 1961-10-25 1961-10-25 Electrophotographic process Expired - Lifetime US3285740A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US147538A US3285740A (en) 1961-10-25 1961-10-25 Electrophotographic process
GB39118/62A GB971281A (en) 1961-10-25 1962-10-16 Electrophotographic process and apparatus
DEG36204A DE1293589B (de) 1961-10-25 1962-10-23 Verfahren und Vorrichtung zum Herstellen von Ladungsbildern auf elektrophotographischem Material

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US147538A US3285740A (en) 1961-10-25 1961-10-25 Electrophotographic process

Publications (1)

Publication Number Publication Date
US3285740A true US3285740A (en) 1966-11-15

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US147538A Expired - Lifetime US3285740A (en) 1961-10-25 1961-10-25 Electrophotographic process

Country Status (3)

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US (1) US3285740A (de)
DE (1) DE1293589B (de)
GB (1) GB971281A (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3477846A (en) * 1967-05-01 1969-11-11 Gaf Corp Xerographic charge transfer process
US3607259A (en) * 1967-01-06 1971-09-21 Australia Res Lab Package of charged photoconductive recording elements for electrophotography
US3629000A (en) * 1965-02-12 1971-12-21 Crown Zellerbach Corp Electrographic printing element
US3697172A (en) * 1968-09-09 1972-10-10 Ricoh Kk Electrostatic photography
US3749927A (en) * 1970-07-03 1973-07-31 Fuji Photo Film Co Ltd Electrostatic charging process for electrophotographic photosensitive material
US4673628A (en) * 1979-03-26 1987-06-16 Canon Kabushiki Kaisha Image forming member for electrophotography

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4923903B1 (de) * 1970-09-18 1974-06-19

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2937943A (en) * 1957-01-09 1960-05-24 Haloid Xerox Inc Transfer of electrostatic charge pattern
US2955938A (en) * 1955-08-01 1960-10-11 Haloid Xerox Inc Xerography
US2963365A (en) * 1956-02-16 1960-12-06 Rca Corp Electrostatic printing
US2979402A (en) * 1956-07-31 1961-04-11 Rca Corp Electrostatic printing
US3037861A (en) * 1957-09-07 1962-06-05 Kalle Ag Electrophotographic reproduction material
US3041167A (en) * 1959-08-19 1962-06-26 Xerox Corp Xerographic process
US3121007A (en) * 1958-02-12 1964-02-11 Xerox Corp Photo-active member for xerography

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB867668A (en) * 1957-11-21 1961-05-10 Otto Kurt Kolb Improvements in or relating to xerographic printing
DE1093385B (de) * 1958-01-24 1960-11-24 Rank Xerox Ltd Xerographisches Vervielfaeltigungsverfahren
BE606987A (fr) * 1960-08-08 1961-12-01 Commw Of Australia Procédé perfectionné de production d'images en électrophotographie et électroradiographie

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2955938A (en) * 1955-08-01 1960-10-11 Haloid Xerox Inc Xerography
US2963365A (en) * 1956-02-16 1960-12-06 Rca Corp Electrostatic printing
US2979402A (en) * 1956-07-31 1961-04-11 Rca Corp Electrostatic printing
US2937943A (en) * 1957-01-09 1960-05-24 Haloid Xerox Inc Transfer of electrostatic charge pattern
US3037861A (en) * 1957-09-07 1962-06-05 Kalle Ag Electrophotographic reproduction material
US3121007A (en) * 1958-02-12 1964-02-11 Xerox Corp Photo-active member for xerography
US3041167A (en) * 1959-08-19 1962-06-26 Xerox Corp Xerographic process

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3629000A (en) * 1965-02-12 1971-12-21 Crown Zellerbach Corp Electrographic printing element
US3607259A (en) * 1967-01-06 1971-09-21 Australia Res Lab Package of charged photoconductive recording elements for electrophotography
US3477846A (en) * 1967-05-01 1969-11-11 Gaf Corp Xerographic charge transfer process
US3697172A (en) * 1968-09-09 1972-10-10 Ricoh Kk Electrostatic photography
US3749927A (en) * 1970-07-03 1973-07-31 Fuji Photo Film Co Ltd Electrostatic charging process for electrophotographic photosensitive material
US4673628A (en) * 1979-03-26 1987-06-16 Canon Kabushiki Kaisha Image forming member for electrophotography
US4701394A (en) * 1979-03-26 1987-10-20 Canon Kabushiki Kaisha Image forming member for elecrophotography
US4737428A (en) * 1979-03-26 1988-04-12 Canon Kabushiki Kaisha Image forming process for electrophotography
US4877709A (en) * 1979-03-26 1989-10-31 Canon Kabushiki Kaisha Image forming member for electrophotography

Also Published As

Publication number Publication date
DE1293589B (de) 1969-04-24
GB971281A (en) 1964-09-30

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Effective date: 19820526

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