CA1094380A - Dielectric imaging member and imaging process therefor - Google Patents
Dielectric imaging member and imaging process thereforInfo
- Publication number
- CA1094380A CA1094380A CA269,741A CA269741A CA1094380A CA 1094380 A CA1094380 A CA 1094380A CA 269741 A CA269741 A CA 269741A CA 1094380 A CA1094380 A CA 1094380A
- Authority
- CA
- Canada
- Prior art keywords
- dielectric
- imaging member
- latent image
- image
- electrostatic latent
- 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
Links
- 238000003384 imaging method Methods 0.000 title claims abstract description 41
- 238000000034 method Methods 0.000 title claims abstract description 29
- 230000008569 process Effects 0.000 title claims abstract description 19
- 239000000758 substrate Substances 0.000 claims abstract description 16
- 239000000463 material Substances 0.000 claims abstract description 4
- 239000011248 coating agent Substances 0.000 claims description 17
- 238000000576 coating method Methods 0.000 claims description 17
- 229920005989 resin Polymers 0.000 claims description 9
- 239000011347 resin Substances 0.000 claims description 9
- 238000012546 transfer Methods 0.000 claims description 9
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Polymers C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 4
- 229920000728 polyester Polymers 0.000 claims description 3
- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 claims description 2
- 229920000515 polycarbonate Polymers 0.000 claims description 2
- 239000004417 polycarbonate Substances 0.000 claims description 2
- 229920002689 polyvinyl acetate Polymers 0.000 claims description 2
- 239000011118 polyvinyl acetate Substances 0.000 claims description 2
- 229920002554 vinyl polymer Polymers 0.000 claims description 2
- 230000015556 catabolic process Effects 0.000 claims 1
- -1 polyacrylics Polymers 0.000 claims 1
- ISXSCDLOGDJUNJ-UHFFFAOYSA-N tert-butyl prop-2-enoate Polymers CC(C)(C)OC(=O)C=C ISXSCDLOGDJUNJ-UHFFFAOYSA-N 0.000 claims 1
- 239000003989 dielectric material Substances 0.000 abstract description 2
- 239000010408 film Substances 0.000 description 13
- 238000011161 development Methods 0.000 description 6
- 239000007788 liquid Substances 0.000 description 6
- 229920006267 polyester film Polymers 0.000 description 4
- 239000000203 mixture Substances 0.000 description 3
- 101150034533 ATIC gene Proteins 0.000 description 2
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 2
- 241001422033 Thestylus Species 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 108091008695 photoreceptors Proteins 0.000 description 2
- 239000004014 plasticizer Substances 0.000 description 2
- 229920003227 poly(N-vinyl carbazole) Polymers 0.000 description 2
- FKNIDKXOANSRCS-UHFFFAOYSA-N 2,3,4-trinitrofluoren-1-one Chemical compound C1=CC=C2C3=C([N+](=O)[O-])C([N+]([O-])=O)=C([N+]([O-])=O)C(=O)C3=CC2=C1 FKNIDKXOANSRCS-UHFFFAOYSA-N 0.000 description 1
- CKVBKDOBKPEWOJ-UHFFFAOYSA-N 9h-carbazole;2,3,4-trinitrofluoren-1-one Chemical compound C1=CC=C2C3=CC=CC=C3NC2=C1.C1=CC=C2C3=C([N+](=O)[O-])C([N+]([O-])=O)=C([N+]([O-])=O)C(=O)C3=CC2=C1 CKVBKDOBKPEWOJ-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 241000283986 Lepus Species 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- 229920002125 Sokalan® Polymers 0.000 description 1
- 229920002472 Starch Polymers 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000006258 conductive agent Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 1
- 239000011104 metalized film Substances 0.000 description 1
- KKFHAJHLJHVUDM-UHFFFAOYSA-N n-vinylcarbazole Chemical compound C1=CC=C2N(C=C)C3=CC=CC=C3C2=C1 KKFHAJHLJHVUDM-UHFFFAOYSA-N 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 229920001467 poly(styrenesulfonates) Polymers 0.000 description 1
- 239000004584 polyacrylic acid Substances 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 150000003242 quaternary ammonium salts Chemical class 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 235000019698 starch Nutrition 0.000 description 1
- 239000008107 starch Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
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
- G03G5/0202—Dielectric layers for electrography
- G03G5/0205—Macromolecular components
-
- 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
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Photoreceptors In Electrophotography (AREA)
- Electrophotography Using Other Than Carlson'S Method (AREA)
Abstract
Abstract of the Disclosure An improved dielectric imaging member comprising a transparent dielectric substrate having a thickness of between about 75-175 micrometers, a conductive layer on said substrate and a dielectric material having a thickness of less than about 15 micrometers on said conductive layer. An imaging process is also provided comprising generating an electrostatic latent image on said dielectric imaging member and developing said image by contact with developer material.
Description
3~(~
DIELECTRIC IM~GING MEMBER AND I~GING PROCESS THER~FOR
Thi~ invention relates to a dielectric imaging member and processes for producing an Lmage on a dielec-tric imaging member, such as a polye~ter film.
Images can be reproduced on a dielectric surface through variouq electrostatographic processe~. In one ~uch proce~, an electro~tatic latent image is generated on the dielectric from a metallic electrode or pin by air ionization. Other such processe~ involve the transfer of an electrostatic latent image to a dielectric surface after it ha~ been formed either on a dielectric surace or on a photoconductive ~urface.
In the fir~t such process, generally referred to as electrography, electroqtatic latent images are generated by character ~hapecl ellsctrode~ or pin electrodes which axe brought into clo~e proximity to an in~ulating ~urface, such as a dielectric web, supported on a base electrod~. A potential is applied across the electrode~
below a critical stress value. Txanser of the character or pin configuration from the electrode to the Lnsulàting web is effected ky the use of a relatively low potential triggering pulse whiah xaises the electric ield above the critical stress value to produce a field discharge in the space between the insulating web and the electrode. The dl~charge action gives rise to the formation of an electro-statlc latent image of the character or pin on the insulatlng web. Thereafter, the generated image on the insulating web can be rendered visible by application of liquid or dry developer thereto.
~,~
Electrography is useful in many applications where it is required that a voltaqe signal pulse be applied directly to a dielectric receiving member, eOg., analog oscillographs, high speed line printers, digital plotters and the like. Typical requirements for such systems are pulses of 700 volts in 50 to 100 microseconds~
It haq been found, however, that applications of electrographic techniques to dielectric films of finite thickneQs, e.g., polyester films having a thickness of greater than 75 micrometers, results in a low density, difuse image that requires re].atively high voltage pulses in the millisecond range.
In the basic electrost:atographic process, a uniform electrostatic charge iS deposited upon a photo-conductive insulating layer which is thereafter exposed to a light image to selectively~ dissipate charge in those areas of the layer exposed to the light, thereby forming an electrostatic latent Lmage. The image can be developed b~ depositing a viewable toner thereon. Alternatively~
the latent image can be transferred to a dielectric surface for subsequent development. Skill further, the - latent image ormed upon a dielectric surface either by electrogxaphic techniques or transfer techniques as described above can, in turn, be trans~erred to a dielectric surface. Techniques for transferring electro-static latent im~ges to an insulating surfac~ are well ~nown in the art and have been accorded the acronym TESI
~Transfer of ElectroStatic Image) see, for example, Xero ra h And Related Processes,Dessauer and Clark, The Focal Press ~1965~ pp. 405 e~ seq~
~2-- ~0~3t~
IE desired, the latent image on the photoconductor can be developed dixectly and the developed areas can then be transferred by placing an insulating surface over the developed photoreceptor surface and applying thereto a high potential of opposite polarity to that o~ the developer by, for example, corona discharge. When the insulating surface is peeled away from the photoreceptor, it will carry thereon a sizable portion of the developer in ~mage configuration. ~hen transfer is accompl;shed, the developer can be fi`xed by fusing it to the receivin~ surface or by other conventional fixing means.
When the electrostatic latent image is transferred from the photoconductor surface to a dielectric surface before development, the charged photoconductive sur~ace is brought into intimate contact with the dielectric surface to effect charge transfer or transfer can occur across an air gap by impresslng ; a voltage between a conductive backing on the photoconductor and the opposed dielectr~c surface of a polarity to attract the charge on the imaged areas to the dielectric.
As a practical matter, however, it has heretofore been impossible to trans~er charge from a photoconductor to a thick, e.g., 75 micrometers or greater, dielectric film and subsequently develop the image to a high optical density with conventional systems.
According to the present invention, there is provided an improved dielectric imaglng member for receiving electrostatic latent images in the absence of an externally applied voltage so as to provide sharp density images consisting essentially of a transparent, resin film, dielectric substrate, an electro-conductive layer on said substrate, and a dielectric resin film in which said dielectric film has a thickness in the range of Cl about 1.4-10 micrometers on said electroconductive layer for receiving said latent images.
The invention further pro~-ides an imaging process comprising generating an electrostatic latent image on a dielectric ;maging member as defined above and developing said image by contacting said image with a de~eloper material.
In a further aspect there i5 provided a method for recording and storing information by directing a beam of electrons in a defined pattern onto a dielectric imaging member as defined above and in the form of a transparent electrographic film to form an imaged film wherein said dielectric resin film is ~rom 5 ~ to lQ ,u in thickness.
-3a-38~1~
An embodiment of the impxoved dielectric member of the present invention comprises a d electric substrate having a thickness between about 75 and 175 micromPters, a conductive coating on said substrate and a dielectric material having a thickness less than about lS micrometers overcoating ~aid conductive coating.
Transparent polye~ter films are presently used a~
the preferred hase material, for example, in micrographic~, due to their Rtrength and stability. To per~it process manipulation and handling, these polyester films are typically ahout 75-175 micrometers thick. Accordingly, reproduction proces_e~ ba3ed on the generation of an electrostatic latent image on Ruch dielectric ~ubstrates were heretofore unavailable for use in conjunction with such preferred, but relatively t.hick substrates.
From known relations such as C ~, and C is proportionate to t r where C = capacitance of the dielectric film, Q = ~urface charge density, V = ~urface voltage of the charge and t = ilm thickness, it is known that thin films will ~tore more electrostatic charge, alheit at the expen3e of surface voltage.
There~ore, in order to obtain optimum image den ity on a dielectric imag.ing member comprising a dielectric ~ub3trate having a thickness of ahout 75-175 micrometer~, it has been di~coverad ~hat if a second dielectric layer of le~ than 15 micrometers is applied to the dielectric ~ubstrate over a thin layer of a conductive agent, the capacitance of the re~ultant dielectric imaging member i~ changed relative to the chargad photoeonductor or a~ electrographic electrode to retain high charge ... , . _ _ _,, _ _ _ . . . . . .. . . .
~O~
density of an electro~atic laten~ image generated on the re~ul~ant dielec~ric imagina member. The generated image can be conventionally developed with high resolutionO
To ~he obser~er, h~wever, the original dielectric Lmaging member remain~ virtually unchanged ~c~ far as transparency and thickness is concernedO
FIGURE 1 of the drawings i~ a diagrammatic view illustrating the proces~ steps of one aspect Df the present invention;
F~GU~E 2 is a graph illustrating the experimental results obtained by coating a conductively treated polyester film with a dieleckric: of vari~us ~hicknesse~
and the developer density obtained on development of an electrostatic latent ima~e transferred to the film; and FIGURE 3 ic~ a composite gralph of both the 3urface voltage and charge density of an electrostatic latent image transferred to a di.electric coatinq of various thickness which is appli.ed to the conductively treated polyester ilm.
Re~erring now to the drawings in detail, whsrein like numerals indicate like elements, the process of the present invention i~ illustrated in FIGIJRE 1.
A typical 75-175 micrometers transparent dielectric substrate 10 has a th.in tran~parent electrically -conduc~ive layer 12 applied to it~ ~ur~ace. Conductive layer 12 has a resistivity value o~ less than 101Q~square, and praferably less than 10 ~ /square. The conductive layer 12 can be any conductive material which is typically applied to paper such as quaternary ammonium salts, sulfonat~d polystyrenes, polyacrylic acid salts and the like~ In addition~ provided a reasonable amount of tran~parency is maintained, metallized films can al~o be employedO
A coating of a dielectric resin 14, i.e. a re~in that ha3 electrical insulating properties, i5 applied over the aonductive coating 12. The dielectric re~in coating thickne~ le~ than about 15 micrometers and preferably, 4 5 micrometer~ and ~hould adhere to tha conductive ~ub~trate.
Dielectric resin~ suitable for use in either or both the dielectric ~ubstrate 10 or dielectric coating 14 include polyvinyl acetate~, acrylic~, styrenated acrylics~
polyester~, polyvinyl butyral, polycarbonates and other high dielectric resins.
In effect, by virtue oi-~ introducing the conductive layer 12, the ca~acitance of the sub~trate 10 is changed relative to a photoconductor 16 havinq a metallic . ~ub~trate 18 and bearing an electrostatic latent image 20 formed thereon by conventional techniques. For the ohserver, however, the substrate 10 i5 virtually unchanged : in thickness and tran~parency.
Because of the capacitative change provided by conductive layer 12 and dielectric coating 14, it has been found that the imag2 20 on the ~urface o~ photoconductor 16 can be transferred to ~he dielectric coating 14 on ~ub~trate 10 by brinying the photoconductor surface 16 into intimate contact with ~he 3urface of dielec~ric coating 14. The transferred electro~tatic latent image L3~
20l on dielectric coating 14 will have sufficiently high charge density to permit development by immersion of the dielectric imaging member in a bath of liquid developer 22 or by other conventional development technique~.
It should be understood that the process disclosed is not limited to charge transfer from a photoconductor. Any surface bearing an electrostatic latent image thereon, e.g., a dielectric surface which is corona charged and has a portion of the charge dissipated to form an electrostatic latent image or upon which an electros~atic latent image is formed by electrographic technique~ can be transferred to the dielectric imaging member of this invention. Further, utilization of the pre~ent invention permits image transfer to any electrically insulative surface of a thicknes~ which normally would have too small an electrical capacity to hold enough ahaxge to produce sufficient development.
The improved dielectric film of the pre~ent invention can also be imaged by conventional electro-graphic techniques to provide sharp, den~e images of the electrod~ configuration at re~uc~d voltages and at ~ignificantly ~horter pulse times~
The following examples further illustrate preferred embodiments of the present invention. These examples are included herein for ill~strative purpo~es only and are not to be construed as imposing any limita-tions upon the scope of the invention. Unless otherwise stated, all percentages and ~arts are by weight.
Exam~e 1 ~ielectric imaging members were prepared by coating a p~lyester substrate (~elinex*505 preprimed available from ICI) having a thickness of 100 micrometers with a conductive layer of sulfonated polystyrene obtained from National Starch. The surface conductivity was 107 ohm cm~ The resultinq conductive substrate was overcoated with a dielectric coating of styrenated acrylic from ~eSoto, Inc. in thicknesses ranging from 1.4 to 14.2 micrometers. Thickness measurements were made using a recording ~pectrophotometer and by mechanical means. An electrostatic latent image was transferred to the resulting dielectxic imaging member hy intimate contact with an electrostatic latent image-bearing photoconductive plate which itself had been charged hy a -5500 V corona. The 24 micrometer thick photoconductive plate had an initial sur~ace voltage o~ 600 volts. The photoconductor composition was a charg2 transfex complex of polyvinyl carbazole and trinitrofluoreno~e, of the type disclosed in UOS. Patent No. 3,484,2370 The electrostatic la~ent image formed on the dielectric imaging member was developed by immersion in a liquid developer compositi~n as di~closed in U.S. Patent No. 3,542,682.
Measurements and calculations were made to determine the charge and voltage transferred to the dielectric imaging mem~er from the photoconductive plate.
The resulting measured voltage ~Monroe Electrometer~
calculated voltage, calculated charge and toner density are shown graphically as a f~ction of thickness in the graphs of FIGU~R5 2 and 3.
*Trademark , ~ :.
,.
3~
It was found that as the ~hickness of the dielectric coating increased, the transferred voltage increased while the amount of transferred charge decreased.
This follows from the principle of conservation of total charge which i5 that charge initially on the photoconductor is~ on contact, shared between the photoconductor and the dielectric coating. ~s the dielectric coatin~ thickness is increased, its capacity to hold charge is decreased relative to the photoconductor.
Optimum results of develo~ed image density were observed when ~he thickness of the dielectric overcoating was in the range of 1.4-ln micrometers with maximum density occurring at a thickness of approximately 4-5 micrometers.
xample 2 A high resolution microimaging system is provided when the dielectric imaging member of the present invention is used to receive an electrostatic latent image from a polyvinyl carhazole photoconductor sensitized with trinitrofluorenone. It has been found that an electrostatic positive charge image formed on such photoconductor can be transferred to the di-electric imaging member of the present invention with no externally applied voltage while maintaining the original resolution to greater than lO0 line pairs per millimeter when developed.
_9 _ l38~
The preferred rnicroimaging system of the present invention as described above provides increased resolution by enabling the photoconductor to intimately contact the surface of the dielectric ima~inq member. Increased S resolution is accomplished by transferring the electro-static latent imaqe under conditions wherein the two sur- ;
faces are in closest proximity. By usinq the surprisingly smooth surfaces afforded by both the poly~inyl carbazole-trinitrofluorenone photoconductor and dielectric ima~in~ memher of the present invention and low ~ap volta~e, hi~h resolution is obtained. ~ccordingly, the use of a film-forminq or~anic photocondu~tor such as pol~vinyl carbazole is particuLarly advantaqeous.
A photoconductive plate was pre~ared hy applying the coatin~ co~position identiEied below to a finely grained aluminum substrate:
In~redients Amounts polyvinyl carbazole 9 ~r~s tetrahydrofuran 60 ml.
DIELECTRIC IM~GING MEMBER AND I~GING PROCESS THER~FOR
Thi~ invention relates to a dielectric imaging member and processes for producing an Lmage on a dielec-tric imaging member, such as a polye~ter film.
Images can be reproduced on a dielectric surface through variouq electrostatographic processe~. In one ~uch proce~, an electro~tatic latent image is generated on the dielectric from a metallic electrode or pin by air ionization. Other such processe~ involve the transfer of an electrostatic latent image to a dielectric surface after it ha~ been formed either on a dielectric surace or on a photoconductive ~urface.
In the fir~t such process, generally referred to as electrography, electroqtatic latent images are generated by character ~hapecl ellsctrode~ or pin electrodes which axe brought into clo~e proximity to an in~ulating ~urface, such as a dielectric web, supported on a base electrod~. A potential is applied across the electrode~
below a critical stress value. Txanser of the character or pin configuration from the electrode to the Lnsulàting web is effected ky the use of a relatively low potential triggering pulse whiah xaises the electric ield above the critical stress value to produce a field discharge in the space between the insulating web and the electrode. The dl~charge action gives rise to the formation of an electro-statlc latent image of the character or pin on the insulatlng web. Thereafter, the generated image on the insulating web can be rendered visible by application of liquid or dry developer thereto.
~,~
Electrography is useful in many applications where it is required that a voltaqe signal pulse be applied directly to a dielectric receiving member, eOg., analog oscillographs, high speed line printers, digital plotters and the like. Typical requirements for such systems are pulses of 700 volts in 50 to 100 microseconds~
It haq been found, however, that applications of electrographic techniques to dielectric films of finite thickneQs, e.g., polyester films having a thickness of greater than 75 micrometers, results in a low density, difuse image that requires re].atively high voltage pulses in the millisecond range.
In the basic electrost:atographic process, a uniform electrostatic charge iS deposited upon a photo-conductive insulating layer which is thereafter exposed to a light image to selectively~ dissipate charge in those areas of the layer exposed to the light, thereby forming an electrostatic latent Lmage. The image can be developed b~ depositing a viewable toner thereon. Alternatively~
the latent image can be transferred to a dielectric surface for subsequent development. Skill further, the - latent image ormed upon a dielectric surface either by electrogxaphic techniques or transfer techniques as described above can, in turn, be trans~erred to a dielectric surface. Techniques for transferring electro-static latent im~ges to an insulating surfac~ are well ~nown in the art and have been accorded the acronym TESI
~Transfer of ElectroStatic Image) see, for example, Xero ra h And Related Processes,Dessauer and Clark, The Focal Press ~1965~ pp. 405 e~ seq~
~2-- ~0~3t~
IE desired, the latent image on the photoconductor can be developed dixectly and the developed areas can then be transferred by placing an insulating surface over the developed photoreceptor surface and applying thereto a high potential of opposite polarity to that o~ the developer by, for example, corona discharge. When the insulating surface is peeled away from the photoreceptor, it will carry thereon a sizable portion of the developer in ~mage configuration. ~hen transfer is accompl;shed, the developer can be fi`xed by fusing it to the receivin~ surface or by other conventional fixing means.
When the electrostatic latent image is transferred from the photoconductor surface to a dielectric surface before development, the charged photoconductive sur~ace is brought into intimate contact with the dielectric surface to effect charge transfer or transfer can occur across an air gap by impresslng ; a voltage between a conductive backing on the photoconductor and the opposed dielectr~c surface of a polarity to attract the charge on the imaged areas to the dielectric.
As a practical matter, however, it has heretofore been impossible to trans~er charge from a photoconductor to a thick, e.g., 75 micrometers or greater, dielectric film and subsequently develop the image to a high optical density with conventional systems.
According to the present invention, there is provided an improved dielectric imaglng member for receiving electrostatic latent images in the absence of an externally applied voltage so as to provide sharp density images consisting essentially of a transparent, resin film, dielectric substrate, an electro-conductive layer on said substrate, and a dielectric resin film in which said dielectric film has a thickness in the range of Cl about 1.4-10 micrometers on said electroconductive layer for receiving said latent images.
The invention further pro~-ides an imaging process comprising generating an electrostatic latent image on a dielectric ;maging member as defined above and developing said image by contacting said image with a de~eloper material.
In a further aspect there i5 provided a method for recording and storing information by directing a beam of electrons in a defined pattern onto a dielectric imaging member as defined above and in the form of a transparent electrographic film to form an imaged film wherein said dielectric resin film is ~rom 5 ~ to lQ ,u in thickness.
-3a-38~1~
An embodiment of the impxoved dielectric member of the present invention comprises a d electric substrate having a thickness between about 75 and 175 micromPters, a conductive coating on said substrate and a dielectric material having a thickness less than about lS micrometers overcoating ~aid conductive coating.
Transparent polye~ter films are presently used a~
the preferred hase material, for example, in micrographic~, due to their Rtrength and stability. To per~it process manipulation and handling, these polyester films are typically ahout 75-175 micrometers thick. Accordingly, reproduction proces_e~ ba3ed on the generation of an electrostatic latent image on Ruch dielectric ~ubstrates were heretofore unavailable for use in conjunction with such preferred, but relatively t.hick substrates.
From known relations such as C ~, and C is proportionate to t r where C = capacitance of the dielectric film, Q = ~urface charge density, V = ~urface voltage of the charge and t = ilm thickness, it is known that thin films will ~tore more electrostatic charge, alheit at the expen3e of surface voltage.
There~ore, in order to obtain optimum image den ity on a dielectric imag.ing member comprising a dielectric ~ub3trate having a thickness of ahout 75-175 micrometer~, it has been di~coverad ~hat if a second dielectric layer of le~ than 15 micrometers is applied to the dielectric ~ubstrate over a thin layer of a conductive agent, the capacitance of the re~ultant dielectric imaging member i~ changed relative to the chargad photoeonductor or a~ electrographic electrode to retain high charge ... , . _ _ _,, _ _ _ . . . . . .. . . .
~O~
density of an electro~atic laten~ image generated on the re~ul~ant dielec~ric imagina member. The generated image can be conventionally developed with high resolutionO
To ~he obser~er, h~wever, the original dielectric Lmaging member remain~ virtually unchanged ~c~ far as transparency and thickness is concernedO
FIGURE 1 of the drawings i~ a diagrammatic view illustrating the proces~ steps of one aspect Df the present invention;
F~GU~E 2 is a graph illustrating the experimental results obtained by coating a conductively treated polyester film with a dieleckric: of vari~us ~hicknesse~
and the developer density obtained on development of an electrostatic latent ima~e transferred to the film; and FIGURE 3 ic~ a composite gralph of both the 3urface voltage and charge density of an electrostatic latent image transferred to a di.electric coatinq of various thickness which is appli.ed to the conductively treated polyester ilm.
Re~erring now to the drawings in detail, whsrein like numerals indicate like elements, the process of the present invention i~ illustrated in FIGIJRE 1.
A typical 75-175 micrometers transparent dielectric substrate 10 has a th.in tran~parent electrically -conduc~ive layer 12 applied to it~ ~ur~ace. Conductive layer 12 has a resistivity value o~ less than 101Q~square, and praferably less than 10 ~ /square. The conductive layer 12 can be any conductive material which is typically applied to paper such as quaternary ammonium salts, sulfonat~d polystyrenes, polyacrylic acid salts and the like~ In addition~ provided a reasonable amount of tran~parency is maintained, metallized films can al~o be employedO
A coating of a dielectric resin 14, i.e. a re~in that ha3 electrical insulating properties, i5 applied over the aonductive coating 12. The dielectric re~in coating thickne~ le~ than about 15 micrometers and preferably, 4 5 micrometer~ and ~hould adhere to tha conductive ~ub~trate.
Dielectric resin~ suitable for use in either or both the dielectric ~ubstrate 10 or dielectric coating 14 include polyvinyl acetate~, acrylic~, styrenated acrylics~
polyester~, polyvinyl butyral, polycarbonates and other high dielectric resins.
In effect, by virtue oi-~ introducing the conductive layer 12, the ca~acitance of the sub~trate 10 is changed relative to a photoconductor 16 havinq a metallic . ~ub~trate 18 and bearing an electrostatic latent image 20 formed thereon by conventional techniques. For the ohserver, however, the substrate 10 i5 virtually unchanged : in thickness and tran~parency.
Because of the capacitative change provided by conductive layer 12 and dielectric coating 14, it has been found that the imag2 20 on the ~urface o~ photoconductor 16 can be transferred to ~he dielectric coating 14 on ~ub~trate 10 by brinying the photoconductor surface 16 into intimate contact with ~he 3urface of dielec~ric coating 14. The transferred electro~tatic latent image L3~
20l on dielectric coating 14 will have sufficiently high charge density to permit development by immersion of the dielectric imaging member in a bath of liquid developer 22 or by other conventional development technique~.
It should be understood that the process disclosed is not limited to charge transfer from a photoconductor. Any surface bearing an electrostatic latent image thereon, e.g., a dielectric surface which is corona charged and has a portion of the charge dissipated to form an electrostatic latent image or upon which an electros~atic latent image is formed by electrographic technique~ can be transferred to the dielectric imaging member of this invention. Further, utilization of the pre~ent invention permits image transfer to any electrically insulative surface of a thicknes~ which normally would have too small an electrical capacity to hold enough ahaxge to produce sufficient development.
The improved dielectric film of the pre~ent invention can also be imaged by conventional electro-graphic techniques to provide sharp, den~e images of the electrod~ configuration at re~uc~d voltages and at ~ignificantly ~horter pulse times~
The following examples further illustrate preferred embodiments of the present invention. These examples are included herein for ill~strative purpo~es only and are not to be construed as imposing any limita-tions upon the scope of the invention. Unless otherwise stated, all percentages and ~arts are by weight.
Exam~e 1 ~ielectric imaging members were prepared by coating a p~lyester substrate (~elinex*505 preprimed available from ICI) having a thickness of 100 micrometers with a conductive layer of sulfonated polystyrene obtained from National Starch. The surface conductivity was 107 ohm cm~ The resultinq conductive substrate was overcoated with a dielectric coating of styrenated acrylic from ~eSoto, Inc. in thicknesses ranging from 1.4 to 14.2 micrometers. Thickness measurements were made using a recording ~pectrophotometer and by mechanical means. An electrostatic latent image was transferred to the resulting dielectxic imaging member hy intimate contact with an electrostatic latent image-bearing photoconductive plate which itself had been charged hy a -5500 V corona. The 24 micrometer thick photoconductive plate had an initial sur~ace voltage o~ 600 volts. The photoconductor composition was a charg2 transfex complex of polyvinyl carbazole and trinitrofluoreno~e, of the type disclosed in UOS. Patent No. 3,484,2370 The electrostatic la~ent image formed on the dielectric imaging member was developed by immersion in a liquid developer compositi~n as di~closed in U.S. Patent No. 3,542,682.
Measurements and calculations were made to determine the charge and voltage transferred to the dielectric imaging mem~er from the photoconductive plate.
The resulting measured voltage ~Monroe Electrometer~
calculated voltage, calculated charge and toner density are shown graphically as a f~ction of thickness in the graphs of FIGU~R5 2 and 3.
*Trademark , ~ :.
,.
3~
It was found that as the ~hickness of the dielectric coating increased, the transferred voltage increased while the amount of transferred charge decreased.
This follows from the principle of conservation of total charge which i5 that charge initially on the photoconductor is~ on contact, shared between the photoconductor and the dielectric coating. ~s the dielectric coatin~ thickness is increased, its capacity to hold charge is decreased relative to the photoconductor.
Optimum results of develo~ed image density were observed when ~he thickness of the dielectric overcoating was in the range of 1.4-ln micrometers with maximum density occurring at a thickness of approximately 4-5 micrometers.
xample 2 A high resolution microimaging system is provided when the dielectric imaging member of the present invention is used to receive an electrostatic latent image from a polyvinyl carhazole photoconductor sensitized with trinitrofluorenone. It has been found that an electrostatic positive charge image formed on such photoconductor can be transferred to the di-electric imaging member of the present invention with no externally applied voltage while maintaining the original resolution to greater than lO0 line pairs per millimeter when developed.
_9 _ l38~
The preferred rnicroimaging system of the present invention as described above provides increased resolution by enabling the photoconductor to intimately contact the surface of the dielectric ima~inq member. Increased S resolution is accomplished by transferring the electro-static latent imaqe under conditions wherein the two sur- ;
faces are in closest proximity. By usinq the surprisingly smooth surfaces afforded by both the poly~inyl carbazole-trinitrofluorenone photoconductor and dielectric ima~in~ memher of the present invention and low ~ap volta~e, hi~h resolution is obtained. ~ccordingly, the use of a film-forminq or~anic photocondu~tor such as pol~vinyl carbazole is particuLarly advantaqeous.
A photoconductive plate was pre~ared hy applying the coatin~ co~position identiEied below to a finely grained aluminum substrate:
In~redients Amounts polyvinyl carbazole 9 ~r~s tetrahydrofuran 60 ml.
2,4,7-trinitro-~-fluorenone 1 aram Clorafin*(a chlorinated hydro- 3 ~rams carbon plasticizer available from Hercules Corporation) The mixture was applied by conventional means to the aluminum substrate with a resultin~ dry thickness of 20 micrometers. Both the adhesion anA apparent coating smoothness were enhanced hy the a~dition of plasticizer.
*Trademark . .
9~3~
The resultinq photoconductive plate was - charged using positive corona and imaged with tungsten light. The electrostatic latent image was transferred to dielectric imaging memhers pre~ared as descrihed in Example 1. The latent image was developed by immersion in a negative liquid develo,Y~er. The re~ulting resolution was greater than 100 line pairs per millime~er.
Example 3 An electrographic imaqing system was established by placin~ a dielectric imaging member prepared as described in Exam~le 1 in contact with a grounded base electrode which was connected t:hrough a p~tential source to a stylus electrode. In thi~; manner, p~sitive high voltage (+800 ~r) was applied through the stylus to the dielectric imaging member ~or ~;quare wave ~uls~ durations of l.S x 10 to 1 x 10 1 seconds. An electrostatic latent image was generated on the dielectric imaging memher in the form of a circular charge pattern equivalent to the contact area of the stylus employed.
The resulting electrostatic latent image ~as develo~ed employing a negative liquid developer composition -(Hunt negative electro~tatic liquid toneravailable from Hunt Chemical).
Good stylist images were thus obtained for applied pulse voltages of 450 to 800 volts at 5 x 10 5 seconds pulse time.
.
~431~3 Under identical conditionq, no image wa obtained when a conventional polyester film having a thickness of 75 micrometers was employed. ~hen the pulse time was increased to 0.5 seconds, and the applied voltage to 1000 volt.s, some char~e in ~he stylus area appeared, but then only randomly.
~ . .
~ .
' ~
-l2-
*Trademark . .
9~3~
The resultinq photoconductive plate was - charged using positive corona and imaged with tungsten light. The electrostatic latent image was transferred to dielectric imaging memhers pre~ared as descrihed in Example 1. The latent image was developed by immersion in a negative liquid develo,Y~er. The re~ulting resolution was greater than 100 line pairs per millime~er.
Example 3 An electrographic imaqing system was established by placin~ a dielectric imaging member prepared as described in Exam~le 1 in contact with a grounded base electrode which was connected t:hrough a p~tential source to a stylus electrode. In thi~; manner, p~sitive high voltage (+800 ~r) was applied through the stylus to the dielectric imaging member ~or ~;quare wave ~uls~ durations of l.S x 10 to 1 x 10 1 seconds. An electrostatic latent image was generated on the dielectric imaging memher in the form of a circular charge pattern equivalent to the contact area of the stylus employed.
The resulting electrostatic latent image ~as develo~ed employing a negative liquid developer composition -(Hunt negative electro~tatic liquid toneravailable from Hunt Chemical).
Good stylist images were thus obtained for applied pulse voltages of 450 to 800 volts at 5 x 10 5 seconds pulse time.
.
~431~3 Under identical conditionq, no image wa obtained when a conventional polyester film having a thickness of 75 micrometers was employed. ~hen the pulse time was increased to 0.5 seconds, and the applied voltage to 1000 volt.s, some char~e in ~he stylus area appeared, but then only randomly.
~ . .
~ .
' ~
-l2-
Claims (13)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An improved dielectric imaging member for receiving electrostatic latent images in the absence of an externally applied voltage so as to provide sharp density images consisting essentially of a transparent resin film, dielectric substrate, an electroconductive layer on said substrate, and a dielectric resin film in which said dielectric film has a thickness in the range of about 1.4-10 micrometers on said electroconductive layer for receiving said latent images.
2. An improved dielectric imaging member in accordance with claim 1 in which said dielectric film has a thickness of about 4-5 micrometers.
3. An improved dielectric imaging member in accordance with claim 1 wherein said imaging member is transparent.
4. An improved dielectric imaging member in accordance with claim 1 wherein said electroconductive layer is an organic electroconductive layer.
5. An improved dielectric imaging member in accordance with claim 1 wherein said substrate had a thickness between about 75-175 micrometers and is selected from the group consisting of polyvinyl acetate, polyacrylics, poly(styrenated acrylics), polyesters, polyvinyl butyral and polycarbonates.
6. An imaging process comprising generating an electro-static latent image on a dielectric imaging member as defined in claim 1 and developing said image by contacting said image with a developer material.
7. An imaging process as defined in claim 6 further characterized in that an electrostatic latent image is formed on a photoconductive surface and transferred to said dielectric imaging member upon being brought into intimate contact therewith in the absence of externally applied voltage.
8. An imaging process as defined in claim 7 wherein the photoconductive surface is a coating of a charge transfer complex of polyvinyl carbazoletrinitrofluorenone photoconductor on a conductive surface.
9. An imaging process as defined in claim 7 wherein an electrostatic latent image is formed on a dielectric surface and transferred to said dielectric imaging member upon being brought into intimate contact therewith in the absence of externally applied voltage.
10. An imaging process as defined in claim 7 wherein the electrostatic latent image is electrographically generated upon said dielectric imaging member.
11. An imaging process as defined in claim 10 wherein the dielectric imaging member is supported on a grounded electrode which is in series connection with a potential source and an image-bearing electrode whereby when the breakdown potential of the air between the electrodes is exceeded, an electrostatic latent image is generated upon said dielectric imaging member.
12. A method for recording and storing information by directing a beam of electrons in a defined pattern onto a dielectric imaging member as defined in claim 1 and in the form of a transparent electrographic film to form an imaged film wherein said dielectric resin film is from 5 µ to 10 µ in thickness.
13. A method as set forth in claim 12 wherein the imaged film is developed by bringing it into intimate contact with a toner.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US66967576A | 1976-03-23 | 1976-03-23 | |
| US669,675 | 1976-03-23 | ||
| US718,361 | 1976-08-27 | ||
| US05/718,361 US4112172A (en) | 1976-03-23 | 1976-08-27 | Dielectric imaging member |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1094380A true CA1094380A (en) | 1981-01-27 |
Family
ID=27100164
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA269,741A Expired CA1094380A (en) | 1976-03-23 | 1977-01-14 | Dielectric imaging member and imaging process therefor |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS52115220A (en) |
| CA (1) | CA1094380A (en) |
| CH (1) | CH604218A5 (en) |
| DE (1) | DE2708930C2 (en) |
| FR (1) | FR2345747A1 (en) |
| GB (1) | GB1573222A (en) |
| IT (1) | IT1076319B (en) |
| NL (1) | NL7703132A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU511943B2 (en) * | 1978-07-12 | 1980-09-11 | Matsushita Electric Industrial Co., Ltd. | Electrographic recording |
| GB2031757B (en) * | 1978-08-31 | 1982-10-13 | Oji Paper Co | Electrostatic recording element |
| JPS5942864B2 (en) * | 1979-04-13 | 1984-10-18 | 京セラミタ株式会社 | Method for preparing a projection manuscript and electrostatic photographic transfer film used therein |
| DE3818162A1 (en) * | 1988-05-28 | 1989-12-07 | Miles Inc | METHOD FOR TROUBLE-FREE COATING OF HYDROPHOBIC MATERIALS WITH POLYURETHANES |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL278985A (en) * | 1961-05-31 | 1900-01-01 | ||
| NL134460C (en) * | 1965-09-10 | |||
| US3502408A (en) * | 1966-12-05 | 1970-03-24 | Varian Associates | Electrophotography employing a film having a thin charge retentive coating on a conductive web |
| US3672930A (en) * | 1970-04-02 | 1972-06-27 | Eastman Kodak Co | Process of transferring an electrostatic charge pattern without using external pressure or electrical bias |
| JPS5428743B2 (en) * | 1971-11-13 | 1979-09-19 |
-
1977
- 1977-01-11 GB GB99577A patent/GB1573222A/en not_active Expired
- 1977-01-14 CA CA269,741A patent/CA1094380A/en not_active Expired
- 1977-01-26 IT IT1967077A patent/IT1076319B/en active
- 1977-02-14 FR FR7704106A patent/FR2345747A1/en active Granted
- 1977-03-02 CH CH259577A patent/CH604218A5/xx not_active IP Right Cessation
- 1977-03-02 DE DE19772708930 patent/DE2708930C2/en not_active Expired
- 1977-03-17 JP JP2874077A patent/JPS52115220A/en active Pending
- 1977-03-23 NL NL7703132A patent/NL7703132A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| IT1076319B (en) | 1985-04-27 |
| GB1573222A (en) | 1980-08-20 |
| JPS52115220A (en) | 1977-09-27 |
| DE2708930A1 (en) | 1977-10-06 |
| NL7703132A (en) | 1977-09-27 |
| FR2345747B1 (en) | 1981-04-30 |
| CH604218A5 (en) | 1978-08-31 |
| DE2708930C2 (en) | 1982-12-09 |
| FR2345747A1 (en) | 1977-10-21 |
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