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CA1119448A - Charge transfer imaging with a semiconductor underlying the photo conductive surface - Google Patents

Charge transfer imaging with a semiconductor underlying the photo conductive surface

Info

Publication number
CA1119448A
CA1119448A CA000306521A CA306521A CA1119448A CA 1119448 A CA1119448 A CA 1119448A CA 000306521 A CA000306521 A CA 000306521A CA 306521 A CA306521 A CA 306521A CA 1119448 A CA1119448 A CA 1119448A
Authority
CA
Canada
Prior art keywords
accordance
semiconductor
photoconductive surface
image
electrostatic image
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
Application number
CA000306521A
Other languages
French (fr)
Inventor
Richard A. Fotland
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.)
Dennison Manufacturing Co
Original Assignee
Dennison Manufacturing Co
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 Dennison Manufacturing Co filed Critical Dennison Manufacturing Co
Application granted granted Critical
Publication of CA1119448A publication Critical patent/CA1119448A/en
Expired legal-status Critical Current

Links

Classifications

    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03GELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00Apparatus for electrographic processes using a charge pattern
    • G03G15/75Details relating to xerographic drum, band or plate, e.g. replacing, testing
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03GELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00Apparatus for electrographic processes using a charge pattern
    • G03G15/14Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base
    • G03G15/18Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a charge pattern
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03GELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/14Inert intermediate or cover layers for charge-receiving layers

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photoreceptors In Electrophotography (AREA)
  • Light Receiving Elements (AREA)

Abstract

ABSTRACT
Charge transfer imaging method and apparatus using a photoreceptor assembly. The assembly, which is formed by the interposition of a semiconducting substrate between a photoreceptor and a conducting base member, is used to transfer an image to a dielectric member with reduced image degradation.

Description

This inven-tion relates to charge transfer imaging and more particularly -to charge transfer imaging employing a modified photorecep-tor assembly to provide reduced image breakup during -the transfer process.
In charge transfer electrophotography, a photosensitive material is provided with the electros-tatic counterpart of an image that is to be reproduced. The elec-trostatic image is then transferred to a member possessing a dielectric surface.
Unfortunately, in the ordinary usage of the foregoing charge transfer techni~ue, a disrup-tive image breakup has been often encountered when the charge photosensitive surface has been brought to the vicinity of the carrier surface. This effect is described in detail in Xerography and Relate'd Process, edited by Jo~m H.
Desrauer and Harold E. Clark, the Focal Press, London and New York 1~65 at Page ~3~.
Accordingly the present invention is advantageous in attempting to reduce the extent of image degradation that takes place when a surface with an electrostatic image is brought to the vicinity of a surface to which the electrostatic image is to be transferred.
Still another advantage of the present invention is to modify a conventional photorecep-tor assembly to achieve reduced image degradation in electrophotography and to achieve a modified photoreceptor assembly for use in reducing the extent of image degradation when a charged surface of the photoreceptor assembly is brought to the vicinity of a receptor dielectric surEace.

'['he pres~nt invention provides an electrophotographicrr.ethod oor~
prising the s-teps of charging a photoconductive surface of a photorec~ptor asser~:ly, said photoreceptor asserrbly :Eur-ther including a conducting sl1bstrate, ~ 2 -and a semiconductor with a -thickness of at leas-t 1 mil, in-terposed between the photoconductive surface and the conduc-ting substrate;
exposing the char~ecl pho-toconductive surface -to a pa-ttern represen-ting an original to he reproduce~, whereby the surface is selectively discharged and a latent electrostatic image is produced -thereon;
moving the image bearing portion of said photoconductive surface into the -transfer region of a dielectric member; and transferring the latent electrostatic image to said dielectric member by the ionization of air in a gap between said photoconductive surface and said dielectxic member.
According to another aspect, the present invention provides a method of reducing image degradation during the transfer of an elec-trostatic image -to a receptor which comprises providing a semiconduc-tor underlying a photoconductive surtace from which the transfer is to take place~
In accordance with a further aspect, the present invention also provides an electrophotographic apparatus of the type including a photoreceptor assembly, means for charging a photo~
conductive surface of the photoreceptor assembly, means for exposing the.charged photoconductive surface layer to a pattern representing an original to be reproduced to form a latent electrostatic image thereon, an image receptor, and means for moving the image bearing portion of the photoconductive surEace into the transfer region of t.he image recep-tor, `characterized in that the photoreceptor member comprises: a photoconductive surface; a conducting substrate; and a semiconductor in-terposed between khe photoconductive surface and the conducting substra-te, said semiconductor having a thickness of at least 1 mil.
other aspects of the invention will become apparent af-ter consiclerinc3 several illustrative embodimen-ts taken in conjunction wi-th the drawinys in which FIG. 1 is a perspec-tive view of a schematic charge transfer member employing a photoreceptor assembly in accordance with the invention; and FIG. 2 is a perspec-tive view of an alternative photo-receptor assembly.
Turniny to the drawinys, a schema-tic representation of a charye transfer imaging assemb]y, in accordance with the invention, is outlined in FIG. 1.
In the particular embodiment of FIG. 1, the photorecep-tor assembly 20 is a drum with a photoconductive layer 21 overlying a semiconductor layer 23 on a conducting substrate 25.
In the conven-tional transfer process, the presence of the electric field associated with the charges of the electrostatic image formed on the drum 20 results in image deyradation in the transfer process. The effect of such image degradation is miti~ated in accordance with -the invention by the inclusion of the semiconduc-tor 23 between the conducting substrate 25 and the photoconductor 21.
Other forms of photoreceptor assembly in accordance with the invention can be provided, for example, by the flexible belt 20' o~ FIG. 2 in which a photoconductive layer 21' overlies a semiconductive layer 23' which is in turn positioned on a conductive substrate 25'. In order -to achieve the desired conductive substrate 25' a conductive coatiny may be applied to a plastic ~ilm or the substrate may be a thin metallic foil, for example nickel.
The conclucting substrate 25 of the drum 20 in FIG. 1 is illustratively of aluminum, but any combination of materials which provides the desiréd conductivity may also be employed.

J4~

It has been empirically discovered that the semi-conducting layers 23 and 23' preferably have a thickness in the range from 1 mil to 750 mlls. The reslstivity of the semiconductive layer must be such -that charge will pass through the layer in a reasonable time. ~ccordingly the resis-tivity is advantageously less than 1012 ohm centimeters.
On the other hand the resistivity must be sufficiently high to provide a time constant for smoothing the charge transfer and thus reduce -the degradation of the transfer image as heretofore encountered. The lower level of resistivity for the semiconductive layers 23 and 23' depends on the thickness of the layers, the thick-ness of the superimposed photoconductive layer, and the operating speed. It has been discovered generally that a resistivity of more than 10 ohm centimeters is suitable.
The semiconductive layer may be realized in a variety of ways. It may be formed by a semiconductive plastic or a semi-conductive elastorner. A suitable conducting agent is carbon black, while a suitable matrix for receiving the carbon black is an epoxy resin. Thus the semiconductor layer may be formed by dispersing carbon black in a resin matrix to achieve a resistivity within the range set forth above. Similarly a wide variety of rubbers can be used with carbon black to obtain the desired resistivity.
The photoconductor~may be of the type generally employed in electrostatic imaging. Ma-terials which have been found to function satisfactority with the semiconductive layer 23 or 23 include polyvinylcarbazole complexed with -trini-troEluorenone;
cadmium sulfide disporsed in a variety of binders includiny epoxies, , . . .
silicones and thermoplastics; selenium and selenium alloys, including amorphous selenium, and low fatigue zinc oxide.

~ - 5 -In ~eneral, for binder layer pho-toconductors, the semi-conducting layer may also be formed of the same material as the photoconductor, but with a higher photosensitive element con-centration, -thus a photoconductive layer of cadmium sulfide in epoxy with an 18~ concentration behaves as an insulator in the dark, while the same layer with a 30% cadmium sulfide concentration behaves as a semiconductor in the dark.
With any of the foregoing photoconductive layers, disrupti~e image breakdown of the kind discussed is observed when the la-tent image receptor consists of a dielectric surace contiguous to a conducting surface. The presence of this semiconducting layer 23 or 2~' between the photoconductor 21 or 21' and the substrate 25 or 25', however, significantly reduces degradation due to disruptive breakdown. Although -the phenomenon by which the semiconducting layer eliminates the disruptive breakdown is not completely understood~ it is believed that the time constant introduced by this semicondu~ting layer has the effect of smoothing or reducing the precipitous behaviour otherwise associated with disruptive breakdown.
The teachings of this invention are useful in situations where it is desirable to transfer a latent electrostatic charge image to any dielectric member, for example, an intermediate dielect-ric member which is subsequently toned and the image produced by toning is then transferred to a plain paper copy or a dielectric sheet which is itself toned to produce a copy.
While various aspects of the invention have been set forth by the drawings and the speciication, it is to be understood that the foregoing detailed description is for illustration only and that various changes in parts, as well as -the substitution of equivalent constituents for those shown and described, may be made without ~ - 6 -3~

departincJ from the spiri-t and scope of the invention as set forth in the appended claims.

Claims (19)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. An electrophotographic method comprising the steps of:
charging a photoconductive surface of a photoreceptor assembly, said photoreceptor assembly further including a conducting substrate, and a semiconductor with a thickness of at least 1 mil, interposed between the photoconductive surface and the conducting substrate;
exposing the charged photoconductive surface to a pattern representing an original to be reproduced, whereby the surface is selectively discharged and a latent electrostatic image is produced thereon;
moving the image bearing portion of said photoconductive surface into the transfer region of a dielectric member; and transferring the latent electrostatic image to said dielectric member by the ionization of air in a gap between said photoconductive surface and said dielectric member.
2. A method in accordance with claim 1 further comprising the step of toning the latent electrostatic image on said dielectric member.
3. A method in accordance with claim 1 wherein the transferring step comprises transferring said image to a dielectric sheet.
4. A method in accordance with claim 1 wherein the transferring step comprises transferring said image to an intermediate dielectric member.
5. A method in accordance with claim 4 further comprising the steps of toning the latent electrostatic image on said intermediate dielectric member, and transferring the toned latent electrostatic image to a plain paper copy.
6. Electrophotographic apparatus of the type including a photoreceptor assembly, means for charging a photoconductive surface of the photoreceptor assembly, means for exposing the charged photoconductive surface layer to a pattern representing an original to be reproduced to form a latent electrostatic image thereon, an image receptor, and means for moving the image bearing portion of the photoconductive surface into the transfer region of the image receptor, characterized in that the photoreceptor member comprises:
a photoconductive surface;
a conducting substrate; and a semiconductor interposed between the photoconductive surface and the conducting substrate, said semiconductor having a thickness of at least 1 mil.
7. Apparatus in accordance with claim 6 wherein the photoreceptor member further includes a conducting substrate underlying said semiconductor.
8. Apparatus in accordance with claim 6 wherein said semiconductor has a thickness in the range from about 1 mil to about 750 mils.
9. Apparatus in accordance with claim 6 wherein said semiconductor has a thickness of at least 1 mil.
10. Apparatus in accordance with claim 6 wherein said semiconductor has a resistivity between 10 to 3 and 10 to 12 ohm centimeters.
11. Apparatus in accordance with claim 6 wherein said semiconductor is selected from the class comprising semiconductive plastics and semiconductive elastomers.
12. Apparatus in accordance with claim 6 wherein said semiconductor is selected from the class consisting of conductors dispersed in a plastic or rubber matrix.
13. Apparatus in accordance with claim 9 wherein said semiconductor is selected from the class consisting of carbon black dispersed in rubber, carbon black dispersed in an epoxy resin, or cadmium sulfide in a plastic matrix.
14. Apparatus in accordance with claim 6 wherein said semiconductor layer is selected from the class consisting of cadmium sulfide dispersed in a binder, amorphous selenium and selenium alloys, zinc oxide binder layers, and organic photoconductors.
15. Apparatus in accordance with claim 6 wherein said photoconductive surface and said semiconductor are formed with the same matrix.
16. Apparatus in accordance with claim 12 wherein said matrix is a thermoset organic resin.
17. Apparatus in accordance with claim 13 wherein said matrix contains a concentration of cadmium sulfide.
18. Apparatus in accordance with claim 14 wherein the concentration of cadmium sulfide in said semiconductor is about 30 percent and the concentration of cadmium sulfide in said photoconductive surface layer is about 18 percent.
19. The method of reducing image degradation during the transfer of an electrostatic image to a receptor which comprises providing a semiconductor underlying a photoconductive surface from which the transfer is to take place.
CA000306521A 1977-07-15 1978-06-29 Charge transfer imaging with a semiconductor underlying the photo conductive surface Expired CA1119448A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US81601277A 1977-07-15 1977-07-15
US816,012 1977-07-15

Publications (1)

Publication Number Publication Date
CA1119448A true CA1119448A (en) 1982-03-09

Family

ID=25219441

Family Applications (1)

Application Number Title Priority Date Filing Date
CA000306521A Expired CA1119448A (en) 1977-07-15 1978-06-29 Charge transfer imaging with a semiconductor underlying the photo conductive surface

Country Status (15)

Country Link
JP (1) JPS5434837A (en)
AU (1) AU527300B2 (en)
BE (1) BE869000A (en)
BR (1) BR7804532A (en)
CA (1) CA1119448A (en)
CH (1) CH632604A5 (en)
DE (1) DE2830626A1 (en)
ES (1) ES471782A1 (en)
FR (1) FR2397660A1 (en)
GB (1) GB2001181B (en)
IT (1) IT1096901B (en)
MX (1) MX145280A (en)
NL (1) NL7806969A (en)
SE (1) SE438921B (en)
ZA (1) ZA783693B (en)

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5033859B2 (en) * 1972-08-02 1975-11-04
JPS514109B2 (en) * 1973-07-27 1976-02-09
DD110707A1 (en) * 1973-08-31 1975-01-05
JPS5754787B2 (en) * 1973-09-14 1982-11-19
JPS5072636A (en) * 1973-10-26 1975-06-16
US4015985A (en) * 1975-04-09 1977-04-05 Xerox Corporation Composite xerographic photoreceptor with injecting contact layer
JPS5269632A (en) * 1975-12-09 1977-06-09 Ricoh Co Ltd Electrophotographic light sensitive material

Also Published As

Publication number Publication date
SE7807033L (en) 1979-01-16
FR2397660A1 (en) 1979-02-09
FR2397660B1 (en) 1984-10-12
BE869000A (en) 1979-01-15
GB2001181B (en) 1982-01-27
GB2001181A (en) 1979-01-24
AU527300B2 (en) 1983-02-24
DE2830626A1 (en) 1979-02-01
JPH0154705B2 (en) 1989-11-20
MX145280A (en) 1982-01-20
SE438921B (en) 1985-05-13
DE2830626C2 (en) 1989-05-18
ES471782A1 (en) 1979-01-16
NL7806969A (en) 1979-01-17
AU3746678A (en) 1980-01-03
IT7825373A0 (en) 1978-07-05
JPS5434837A (en) 1979-03-14
BR7804532A (en) 1979-04-17
CH632604A5 (en) 1982-10-15
IT1096901B (en) 1985-08-26
ZA783693B (en) 1979-06-27

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