US3876424A - Electrophotographic liquid developing process employing non-polymer binding materials in the photoconductive - Google Patents

Electrophotographic liquid developing process employing non-polymer binding materials in the photoconductive Download PDF

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US3876424A
US3876424A US264335A US26433572A US3876424A US 3876424 A US3876424 A US 3876424A US 264335 A US264335 A US 264335A US 26433572 A US26433572 A US 26433572A US 3876424 A US3876424 A US 3876424A
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photosensitive member
developer
latent image
photoconductive layer
photoconductive
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Eiichi Inoue
Ichiro Endo
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Canon Inc
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Canon Inc
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Priority claimed from JP1180168A external-priority patent/JPS4834773B1/ja
Priority claimed from JP1180268A external-priority patent/JPS494661B1/ja
Priority claimed from JP43029256A external-priority patent/JPS4824052B1/ja
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/16—Developers not provided for in groups G03G9/06 - G03G9/135, e.g. solutions, aerosols
    • G03G9/18—Differentially wetting liquid developers
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/10—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer
    • G03G15/101—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer for wetting the recording material
    • G03G15/102—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer for wetting the recording material for differentially wetting the recording material
    • 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
    • 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
    • G03G5/05—Organic bonding materials; Methods for coating a substrate with a photoconductive layer; Inert supplements for use in photoconductive layers
    • G03G5/0503—Inert supplements
    • G03G5/051—Organic non-macromolecular compounds
    • G03G5/0514—Organic non-macromolecular compounds not comprising cyclic groups
    • 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
    • G03G5/09—Sensitisors or activators, e.g. dyestuffs
    • 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
    • G03G5/101—Paper bases
    • 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
    • G03G5/102—Bases for charge-receiving or other layers consisting of or comprising metals

Definitions

  • PATENTEUAPR 8M5 sumup g FIG. 8
  • This invention relates to an electrophotographic pho tosensitive member and more particularly to an electrophotographic photosensitive member used in wet developing method and to a novel process thereof.
  • an original picture is recorded in photosensitive member as an electrostatic image by projecting the optical image of the original picture onto the photoconductive layer provided in the photosensitive member, by such means as selectively eliminating the electric charges on the photoconductiw layer. that has previously been charged uniformly, corresponding to the optical image or inducing electrostatic charges corresponding the optical image projected. and by forming an electrostatic pattern consisting of the pattern of electrostatic charges that correspond to the optical image in the photoconductive layer or in other layers.
  • Various methods have already been proposed to form a visual image by developing the electrostatic latent image formed as mentioned so far.
  • a known method is to apply a colored toner charged either in the same polarity as or in a different polarity from the electrostatic latent image to the photosensitive member holding the electrostatic latent image, and to develop the image by having the electrostatic latent image attract the said toner electrostatically.
  • dry type developing agents in which the toner is adhered electrostatically to a holding body called the carrier. are in general use.
  • liquid type developing agents that contain the toner are also known to the public.
  • One of the known types of liquid developing agents is to use the developing agents in the form of aerosol.
  • development is con ducted by charging the atomized toner ofa dye solution electrostatically in high pressure equipment, by spraying the toner in an electric field between two electrodes one of which is the photosensitive member holding the electrostatic latent image, and by adhering electrostatically the charged atomized toner onto the electrostatic latent image.
  • the second type of developing agent is one in which the toner is dispersed into and suspended by holding liquids having a high electrical resistance and a low dielectric constant such as benzene, benzol, and carbon tetrachloride and simultaneously charged in a polarity different from that of the electrostatic latent image of photosensitive member.
  • the photosensitive member is immersed into the developer and the development is carried out by attracting and adhering the aforementioned toner onto the electrostatic latent image of the photosensitive member.
  • the socalled wetting developing method which, quite different from the aforementioned methods, develops the electrostatic la tent image by having the electrostatic force ofthe electrostatic latent image on the photosensitive member exert influence on the interfacial tension between the developer and the surface of the photosensitive memher when the developer is applied to the photosensitive member and by having the developer stick to the photosensitive member selectively, gas disclosed in U.S. Pat. Nov 3,084,043.
  • the so-called wetting developing system uses a liquid type developing agent like the aforementioned electrophotographic methods, the developing mechanism is quite different from those of the aforementioned methods.
  • the principle is based on the fact that when a liquid is applied to the surface of a body by the electrostatic force the interfacial tension of the surface of the body changes at the interface between the liquid and the surface of the body and the surface of the body exhibits wetting action.
  • the action by which a liquid wets the surface of a specific body can be expressed by the socalled contact angle.
  • contact angle is defined as the angle between the surface of a body and the tangent line to the surface of a liquid drop resting on the surface. Generally, when the surface of a body is wet ted by a liquid, the contact angle assumes an angle of or less, and when not wetted. more than 90.
  • the developer adheres to the photosensithe member either selectively or in different degrees, and, as a result, development is completed.
  • the developers used in the wetting developing system differ remarkably in composition from the developers used in the aforementioned well known electrophotographic methods.
  • the toner suspensions used in the aforemen tioned electronic photographic methods usually use organic solvents, whereas the developers employed in the wetting developing system use a solution of aqueous system having a high dielectric constant such as water instead of organic solvents. Therefore, in contrast to organic solvents, the developers ofthe wetting develop ing system are not combustible, cause no disturbance on human body and in these respects are very effective in practical use.
  • the conventional known photosensitive members are formed. for example. by dispersing pulverized photoconductive body such as zinc oxide into film forming polymers such as silicon resins. styrene resins. and butadiene resins. by applying a coat of the suspensions to a paper or metal base. and by drying.
  • pulverized photoconductive body such as zinc oxide
  • film forming polymers such as silicon resins. styrene resins. and butadiene resins.
  • high molecular polymers present on the surface of photoconductive material such as zinc oxide is being adsorbed. polymers of different compositions appear and are distributed on the surface that receives the developer and. as a result.
  • the photosensitive members so obtained had a surface on which the lyophilic and lyophobic sections are nonuniformly dispersed. Consequently. even when uniform electrostatic charge is present on the photosensitive member. uniform sticking of developer is impossible because of the effect of aforementioned nonuniformity of lyophobic and lyophilic sections. and even when an electrostatic latent image is formed on the photosensitive plate. only an extremely fogged and bad picture image was obtained by wetting development. Moreover. since the aforemen tioned photosensitive members employ polymers as film forming materials. the photosensitive members obtained were forced to be very thick.
  • the photoelectric layer used in the aforementioned well known example had a comparatively high dark resistance of about cm and, at the same time.
  • the developer supplying means such as the developing roller used to supply a developer employed in the conventional wetting developing systcm to the surface of the photosensitive member
  • the developer supplying means such as the developing roller used to supply a developer employed in the conventional wetting developing systcm to the surface of the photosensitive member
  • the one that has a geometrically uneven surface and has the developer filled in the said depressions was disclosed by the US. Pat. No. 3.084.043.
  • all the developer supplying means that have been disclosed are of the type that has a geometrically uneven surface. depressions of which serve to hold the developer. The reason is that. if the surface ofthe supplying means is plane and smooth. the surface of the photosensitive member is uniformly wet when developing and the developer sticks to the surface equally. Although the developer wet sticks to the surface of the photosensitive member according to the electrostatic latent image or conductive pattern formed on the photosensitive member, the developer is forced to stick evenly to the no-picture area where no such latent image or pattern exists. As a result, the image visualized by the developer has a dense fog.
  • the aforementioned developer supplying means have been formed in the shape of a roller. It was a difficult for such roller-shaped means to supply a constant amount of developer continuously.
  • General practice was to feed the ink with a great number of rollers. to supply the ink to an ink feed roller. and to re move the excessive ink finally with a doctor knife. as is usual in the known technique of printing.
  • a doctor knife as is usual in the known technique of printing.
  • An object of this invention is to offer an elcctrophotograhic photosensitive member for use in wetting development wherein the foregoing defects are removed and each ofthe lyophobic and lyophilic portions is evenly distributed on the surface.
  • Another object of this invention is to offer an electro photographic photosensitive member for wetting development wherein the surface is capable of adjusting both the lyophobic property and lyophilic property as desired.
  • a further object of this invention is to offer an electrophotographic photosensith e member for wetting development having a mechanical strength similar to the case in which the conventional film forming polymers are used and is enabled to be composed in very thin layers.
  • a still further object of the invention is to offer a novel visual-image-forming process wherein a visual image with an extremely high picture density is formed by using a photoconductive layer with comparatively low specific resistance and a base with a highly resistant layer or a barrier layer.
  • a still further object of this invention is to offer a image forming process. wherein an very clear visual image is obtained by using two kinds of developer for wetting development. one is hydrophobic and the other hydrophilic.
  • a still further object of this invention is to offer an image forming process. wherein the electric latent image formed on the photosensitive member is reversed and visualized by converting the polarity of the electrode that applies electricity to the developing roller for wetting development.
  • a still further object of this invention is to offer an image forming process in which visual image with an extremely high density is formed by the use of nonpolymcrs in forming film on the photosensitive member.
  • a still further object of this invention is to offer a novel wetting development process. wherein the electrostatic latent image on the photosensitive member is visualized by dropping wetting developer in cascade on the said latent image side of the photosensitive member.
  • a still further object of this invention is to offer a developing process. wherein wetting developer supplying means is employed to form a visual image with less fog, high resolution power. and further an extremely high picture image density.
  • a still further object of this invention is to offer a developing process, wherein a feed roller supplies the developer uniformly onto the developer supplying means which applies the developer onto the photosensitive member.
  • FIG. 1 and FIG. 2 are the drawings showing the principle of wetting development process where a photosensitive member according to this invention is employed;
  • FIG. 3 is a drawing showing the principle of the lst clectrophotographic image forming process and visual image forming process according to this invention:
  • FIG. 4 is a sketch of an embodiment of the principle shown in FIG. 3:
  • FIG. 5 is a drawing showing the principle of the second clectrophotographic image forming and visual image forming processing according to this imention:
  • FIG. 6 is a sketch of an embodiment of the principle shown in FIG. 5'.
  • FIG. 7 is a magnified drawing of the feed surface of developer supplying means of first type used in the de velopment processing according to this invention.
  • FIG. 8 is a drawing showing the principle on which the development of photosensitive member by means of the supplying means shown in FIG. 7 is based;
  • FIG. 9 shows a front view of the supplying means of FIG. 7;
  • FIG. 10 is a sketch of a device realizing a develop ment process by using the supplying means shown in FIG. 7;
  • FIG. II is a magnified cross section of the surface of developer supplying means used in the second type development process according to this invention:
  • FIG. 12 is a magnified drawing of the surface of the supplying means shown in FIG. ll;
  • FIG. I3 and FIG. 14 are the sketches of the device which realizes a development process using the developer supplying means shown in FIG. 11 and FIG. [2;
  • FIG. 15 is a cross section of the device which realizes briefly the dc ⁇ elopmcnt process using the wetting developer supplying means according to this invention shown in FIG. 16 through FIG. 21;
  • FIG. 16 through FIG. 21 show the developer supplying means used in the third type of wetting development process according to this invention.
  • FIGS. 22 and 23 show other embodiments of the developing device using the feed roller according to this invention.
  • FIG. 24 is a drawing showing the principle of developing method according to this invention.
  • a feature of this invention is to provide a photosensitive member for wetting development by using filmforming nonpolymer organic compounds as the bonding materials of photoconductive substances.
  • the wetting developing system is based on the principle that the interfacial tension between a photosensitive member and developer that is applied to the surface of the said member is changed by the effect of the electrostatic latent image formed on the photosensitive member and. as a result. wetting action is produced. and the developer sticks only to the surface of the latent image. It is extremely important in such a wetting developing system to form the surface of the photosensitive member to have lyophobic and lyophilic characteristics in a specified ratio and uniformly as well as to control the relationship between the Iyophobic character and lyophilic character on the surface of the photosensitive member.
  • the present inventors found out that these important requirements were fulfilled by controlling the ratio be tween the lyophobic property and the lyophilic property on the surface of the photosensitive member. and also found out that the best way to control the relationship between the lyophobic property and lyophilic property of the photosensitive member was to use nonpolymer organic compounds as the bonding material of film forming photoconductive material.
  • nonpolymer compounds have a lyophobic property.
  • the lyophobic property can be controlled arbitrarily by adding further a proper amount of nonpolymers such as. for example. higher fatty acids. higher fatty acid esters. and higher alcohols. The reason for this may be attributable to the fact that. for example. in the case in which zinc oxide is used as the photoconducti ⁇ e material and a higher fatty acid is further added. the carboxyl radical of the higher fatty acid is adsorbed chemically to the surface of zinc oxide and the alkyl radical of the higher fatty acid is oriented on the external side of the surface of zinc oxide.
  • the lyophobic property of the surface of photosensitive member can be controlled arbitrarily by the addition of a higher fatty acid.
  • a nonpolymer is. different from high molecular substances, the polymers. and has a definite chemical composition and, since its molecular weight is small. nonuniformity in electrical characteristic is greatly reduced as the photosensitive member. At the same time. since it is allowed to be dispersed homogeneously. it is possible to distribute the lyophobic property and lyophilic property uniformly on the surface of photosensitive member at a specified ratio.
  • One other advantage brought about by the use of nonpolymers as the film forming bonding material of photosensitive member is that a very thin layer can be obtained without loosing any electrophotographic characteristicv In other words. a nonuniform thin layer of resin is not formed on the surface any more. and the bonding characteristic with the base or the bonding characteristic in between individual photoconductive substances has a mechanical strength comparable to the case in which conventional film forming polymers are used.
  • composition of photosensitive member according to this invention will be described as follow.
  • the photoconductive materials used in this invention are. for example, zinc oxide. titanium dioxide, zinc sulfide. cadmium sulfide. selenated zinc. lead monoxide. indium oxide. anthracene. anthraquinone. carbazole. and heterocyclic compounds such as imidazole, oxazole. and thiazole.
  • One example of manufacturing process of electrophotographic photosensitive materials used in this invention is as follows: Prepare a solution of nonpolymer organic compound; Add to it an equal amount or more of photoconductive material and disperse the material by means of an appropriate means such as ultrasonic wave, ball mill. or colloidal mill. Next. apply a coat of the suspensoid on the base such as paper or metal sheet and. dry it to evaporate and remove the solvent. Thus an electrophotographic photosensitive material has been obtained.
  • the desirable ratio between the amount of nonpolymer organic compounds and the amount of photoconductive materials used in this invention is from 1 to 8 parts by weight of photoconductive materials to 1 part by weight of nonpolymer organic substances. ln this in vention addition of well known sensitizing dyes and chemical sensitizers is possible. if desired. and the sensitizing effect in such cases is quite equal to that of the case in which conventional film forming polymers are used as the bonding agents.
  • Nonpolymer organic compounds used in this invention are:
  • A. Organic acids and acid anhydrides Maleic acid. phthalic acid. salicyclic acid, L-ascorbic acid. abi ctic acid. benzoic acid. naphthenic acid. itaconic acid, adipic acid. sulfosuccinic acid. 2-furan carboxylic acid, alizarine. sebacic acid. lauric acid. myristic acid, terephthalic acid. maleic anhydride. phthalic anhydride. salicylic anhydride.
  • Phenol derivatives Phenolphthalein, phenyl salicylate. P-phenylphenol. O-phenylphcnol D.
  • Esters B-naphthyl methyl ether. dimethyl terephthalate.
  • Aniline derivatives Diphenyl guanidine. P-benzyl aniline. 2.4,5-trichloroaniline.
  • Phosphorous compounds Tributyl phosphate, zinc dithiophosphate. zinc pyrophosphate.
  • Ammonium salts of nonpolymers Ammonium benzoate, ammonium palmitate, ammonium phthalate, ammonium stealate, ammonium tartrate.
  • K Alkali metallic salts of nonpolymer organic compounds: Sodium palmitate, potassium palmitate, potassium picrate, potassium phthalate, apotassium tartrate.
  • L Water soluble nonpolymer organic compounds having one or more than one carboxyl radicals. sulfo radicals. phenolic hydroxyl radicals. amino radicals. or halogen radicals: Crotonic acid, maleic acid, benzenesulfonic acid, isocrotonic acid, ethylmaleic acid, dihydroxynaphthenic acid, dinitroph thaleic acid. furan carboxylic acid, P- aminodimethylaniline. hexamethylenediamine. aamino-l-naphthol. acid amides of glycol, 2,5
  • the number of kinds of nonpolymer organic compounds used in the preparation of electrophotographic photosensitive material according to this invention is not limited to one but to two or more than two kinds of the compounds at once. Combined use of high mo lecular bonding materials of high molecular organic photoconductive materials is also allowed when required.
  • this invention shall not be limited to the compounds described in the specification and examples.
  • the effective additives that make the surface of electrophotosensitive materials lyophobic in this invention are for example: higher fatty acids such as palmitic acid, stearic acid, behenic acid, oleic acid, and linolic acid; higher fatty acid esters such as linseed oil. perilla oil, olive oil, arachid oil, tsubaki oil, and tung oil: higher alcohols such as stearyl alcohol, myricyl alcohol, and cetyl alcohol.
  • Sensitizing effect is noticeable by the addition of an appropriate amount of conventional sensitizers to the photosensitive layer used in this invention.
  • the sensitiz ers used are for example: (a) conventional dyes such as Rose Bengal, Phloxine, Erythrasine, Uranine. Eosine, Rhodamine B, Fuchsine, Crystal Violet, Acridine Orange, and Methylene Blue; (b) conventional donor or acceptor additives for photoconductive substances such as maleic anhydride, phthalic anhydride, crotonic acid, benzophenone, hydroquinon, anthraquinone, benzaldehyde, diphenylamine, chloranil, paraphenylenediamine, and aminobenzaldehyde.
  • conventional dyes such as Rose Bengal, Phloxine, Erythrasine, Uranine. Eosine, Rhodamine B, Fuchsine, Crystal Violet, Acridine Orange, and Methylene Blue
  • conventional donor or acceptor additives for photoconductive substances such as
  • a more specific object of this invention is to offer a novel image forming process by using the photosensitive member comprising the aforementioned materials. This is explained in detail in the following.
  • the photosensitive member used in the process of this invention has a comparatively low resistant photoconductive layer formed in film on the base with photoconductive materials by using nonpolymers as the bonding materials and the base must have substantially a high resistance.
  • the substantially high resistant base can be referred to an insulating thin film of, for example, Mylar (Trade name of polyester resin) or to the one in which an electrical bar rier layer is formed between the base and photoconductive layer by interposing an epoxy resin layer between these layers.
  • a value of I0 9 cm or more is desirable for the value of high resistance. While the resistance of the photoconductive layer used here is desired to be less than 10 lO Q -cm.
  • the resistance of the photoconductive layer of photosensitive member used in electrophotography is required to be [0 -cm or more. This requirement must be fulfilled in in order to form and keep an electrical image on the photoconductive layer and when the resistance is lower than this value a good corona charging characteristic cannot be obtained, that is, such defects as no charging, small amount of charge, or a small charge holding capacity, etc. may be caused and, as a result, it becomes difficult to form a good quality latent image.
  • the specific resistance of photoconductive layer is high, the
  • photosensitive member has in general a defect of being low in sensitivity.
  • a photosensitive member comprising the aforementioned low resistance photoconductive layer and high resistance base is used to attain the purpose of obtaining a photosensitive member that meets the requirement of electrophotographic photosensitive member and has a high sensitivity.
  • An image forming process using such a photosensitive member will be described in the following.
  • an electrostatic latent image is formed by first giving the surface of the aforementioned photosensitive member an exposure oflight and dark pattern in dark place to form a conductive pattern within the photoconductive layer ofthe photosensitive member, then by applying to aforementioned photosensitive member an electric field under condition that an electrode is in close contact with the aforementioned plptosensitive member to form a high electric field at the light portion where the conductivity has been increased by the light and a low electric field at low conductive dark portion.
  • developer is applied to the surface holding the said electrostatic latent image.
  • the developer wet sticks to the portion where the electrostatic latent image is present, i.e. the light region, and does not stick to the portion where the said latent image is not present.
  • the developer is selectively attracted by the influence of the electrostatic latent image and, as a result, the electrostatic latent image is visualized.
  • a photosensitive member comprising a photosensitive layer 1 of ZnO bonding agent system having a rather low dark resistance compared with conventional ones and a base having a resistance almost equal to insulation
  • ZnO is a N- type semiconductor
  • the mobility of electrons is greater than the positive holes. that is. it is a majority carrier. Therefore, as shown in FIG. 3a, it is assumed that thermally excited free electron F and the electron T caught at the trap are present in the photosensitive layer even in the dark place.
  • a great amount of free carriers P positive hole, electron
  • the composite dark resistance of the photosensitive layer used in this invention is less than l0 lO' Q -cm. It is also considered desirable that the resistance of the base according to this invention is more than 9 -cm. It is desirable to form a barrier layer having a resistance of over lO fl -cm between photosensitive layer and base when a conductive base is used. The higher the resistance of the base and barrier layer, the more the applied voltage is required to be increased. This is explained by the presumption that the voltage is proportional to the relative ease of the initiation of injection or ejection of electric charge from the electrodes. However, it is considered that the base or barrier layer should have a resistance sufficient to hold and form the electric charge. Further detail will be understood by referring to the examples 1] and 12 described later.
  • the developing roller or the developer supplying means used in the developing process of the aforementioned image forming process a highly excellent visible image can be obtained by using a developer supplying means of No. I through No. 3 type explained as follows. Detailed explanation of them will be provided later.
  • the feature of this process is to visualize the latent image by projecting an optical image on the photosensitive member used in the aforementioned image forming process, by applying the developer while providing an electric field across the photosensitive member either simultaneously with or after the projection, and by letting the photosensitive member attract the developer either selectively or in different degrees in inverse proportion to the amount of electric charge ejected from the electric field.
  • the difference between this process and the firstly mentioned image forming process is that application of electric field and developer is not made separately but simultaneously, and the image forming process is essentially different from the first image forming process.
  • the interfacial tension between the said liquid and the surface of the said photosensitive member is affected by the presence or absence of the aforementioned electric charge ejection or by the degree of ejection, and the surface of the said photosensitive member is wetted by the said liquid according to the ejection pattern of the said electric charge. Therefore, in contrast to from the aforementioned first image forming process, the developer sticks not by the presence of electrostatic charge, but the ejection of latent image charge and injection of charges of different polarity is caused in the latent image region at time by applying electric field, and the developer is attached selectively by the repulsion of developer due to the transient phenomenon.
  • the aforementioned image forming process is different from the process in which development is carried out by applying in situ to the electrical latent image formed on the photosensitive member an electric field employing electrodes during development to extract the electrical latent image formed on the photosensitive member in, that an electric charge different in polarity to the said latent image is injected while the developer is applied. and that the developer is attached dynamically during mobile period of the electric charge. As a result, the developer adheres to the portion where no electric latent image is present. Especially, when the developer is applied, injection and ejection of the charge ofelectric latent image is started by the influence of electric field. However. as shown in FIG.
  • the electric charge injected from the base 2 side is held in the interface between the base 2 and the photoconductive layer 1 due to the high resistance of the base, and due also to the high resistance.
  • the charge of latent image formed on the photoconductive layer is retained without recombining with the charge on the base side to cause fade.
  • the photoconductive layer regardless of the low resistance, has an excellent latent image holding capacity and a latent image having an extremely good contrast is formed.
  • nonpolymer material capable of controlling the lyophobic and lyophilic properties arbitrarily is used as the bonding material of the photosensitive member used in the above. if the surface of the photosensitive member is made Iyophilic in advance. the region where the charge ejection is constrained has more accelerated wetting action due to the lyophilic property of the bonding agent. and a visible image higher in density than the conventional images can be obtained. This is one of the features of this invention.
  • the visible image formed on the photosensitive paper is reversed.
  • the photosensitive paper using a N type photoconductive substance it is preferrable to make the photosensitive layer side as electrode and the base side as electrode.
  • the electrodes are not limited to the above arrangement.
  • the first type of developer supplying means used in this invention comprises projections having pointed ends provided on a smooth surface at proper intervals. This will now be explained on a concrete embodiment referring to FIG. 7 through FIG. 10.
  • FIG. 7 is a partial cross section of developer suppying means.
  • F is a smooth surface body of the developer supplying means and is made of corrosion proof materials used in general printing concerns such as zinc. aluminum, paper, ether metals, and plastics.
  • the surface fof the body F is desired to be made of lyophilic materials or made lyophilic by surface treatment or processing when a water soluble ink is used as the developer.
  • Projections P are formed on the surfacefof the smooth surface body F.
  • the photoresist which is in wide use in printing techniques. is especially effective. It is especially desirable to use a metal that has undergone lyophobic treatment or processing for the projection P to have its surface lyophobic when a water soluble developer is used.
  • the shape of the projection P prefferably has an acute angle pointed end.
  • the desirable diameter of the end is between several p. and several tens of p and the desirable height of the projection is within the range of 5 to I00 11., although it varies with the kind of photosensitive material.
  • the spacing between two adjacent projections differ similarly with the kind of photosensitive material and, when the photosensitive material is composed of less flexible bases such as metals, the bending of the surface of the said material is also small. Therefore, the interval between, for example. projections P and P which are perpendicular to the direction A in which the developing roller rotates is desired to be from 30 mm to l00mm.
  • the said interval is desired to be sufficiently small to keep the surface of the photosensitive member horizontal.
  • the interval between the projection P and the projection P is desired to be made to 10mm to 50mm.
  • the interval between the projection 11 and the projection 12 is desired to be 5mm to 30mm.
  • the photosensitive body contacts only with the end of the projection P as shown in FIG. 2, and the supplying surface except for the projections is wet ted uniformly in film form by the developer.
  • the developer holding surface of the aforementioned developer supplying means is provided with many projections which are the same in height and have extremely sharp ends, the photosensitive member is held at a constant distance from the developer supplying means by those projections, and the developer address uniformly and indifferently to the photosensitive member.
  • the developer sticks and wets the latent image forming region of the photosensitive member.
  • the projections in contact with the photosensitive member are free from the adherence of the developer.
  • these projections have very sharp ends as mentioned above, they have no special influence on the imageformation. As a result, the visible image obtained has an excellent resolution power.
  • FIG. shows a device constructed by using the developer supplying means shown in FIG. 7 through FIG. 9, in which 103 shows the photosensitive member comprising the base 102 and the photoconductive layer 101.
  • the developer L in the developer tank V is supplied uniformly to the surface of the developer supplying roller R by the roller r.
  • the roller R On the surface of the developer supplying roller R is affixed the aforementioned developer supplying means F, and the roller R is no tated on the electrostatic latent image holding surface of the photosensitive member, making contact with the projections P ofthe said means.
  • the electrical-fieldapplying roller R On the base side of the photosensitive member is arranged the electrical-fieldapplying roller R, and the developer is applied to the photosensitive member while an electrical field is being applied to the photosensitive member by the rollers R and R'.
  • the smooth surface fof the above-mentioned developer supplying means is not always required to be a smooth surface but is required to be a surface sufficient to hold and form the liquid uniformly. There can therefore be used such porous substances as sponge, fiber, and sintered metals. Moreover. there can be a fine regularly or irregularly uneven surface such as a metal surface that underwent sand setting.
  • the printing field can also be used.
  • FlGS. 11 through l4 show an embodiment of the second type of developer supplying means. Different from the above-mentioned system, this embodiment features the system by which the developer is supplied to the photoconductive layer intermittently by physical action, using a smooth surface that has both lyohilic property and lyophobic property.
  • the feature of this second embodi ment lies in the fact that, when, for example, the devel oper used in wetting development is water soluble, the developer adheres to the lyophilic surface selectively, in other words, the liquid is kept in a separated state on the surface and supplied to the photoconductive layer, and the liquid is separated by physical action on the smooth surface which has both lyophilic property and lyophobic property.
  • Another feature of this embodiment lies in the fact that the division of developer is more easily performed on a smooth surface when on the smooth surface that has lyophilic and lyophobic properties the lyophobic portion is first wetted by lyophobic solution and then the lyophilic portion is wetted by using a water soluble developer.
  • FIGS. ll and 12 show the cross section and the top view of the developer supplying means.
  • H is prepared by forming grooves of l line/1mm order on a plate having lyophilic surface P, by filling a lyophobic substance into the said grooves, and by establishing finely divided lyophilic surface portions and lyophobic surface portions on the same surface alternatively.
  • the following method can be used as an example.
  • lv Lyophobic portion and lyophilic portion are divided into lines or mesh points within the range of l line/mm to 20 lines/mm by using the plain intaglic manufacturing technique of printing. Specifically, this is done as follows.
  • FIG. 12 (a) (b) show the formation of lyophobie portion H and lyophilic portion P through the mesh point division using that plate process of printing.
  • FIG. 12 (c) (d) show the fomation of lyophobic portion H and lyophilic portion P by line breaking-up and screen breaking-up with the same process.
  • the degree of breaking-up and the shape can be made to the level of some 20 lines/mm by selecting a proper pattern at time of breaking-up printing, and the size of the point is allowed to be selected freely.
  • Fine holes or recesses within the range of 1 line/mm to 20 lines/mm are made of the base plate by using printing plate making techniques such as letterpress, intaglio press, photogravurepress, and fiat press.
  • the concaves formed on the said base plate are filled with a material either lyophilic or lyophobic to form a smooth surface.
  • the said surface comprises lyophilic portion and lyophobic portion.
  • fine holes 50 a in diameter and 30 pt in depth were prepared lines/mm on a zinc sheet 300 p. in thickness using the method that prepares photogravure press.
  • An epoxy resin was used to fill the said holes.
  • the resin was applied uniformly over the zince sheet. dried. then the surface was polished with 150 mesh sandpaper until the surface of zinc was revealed uniformly.
  • a smooth surface S that had lyophilic portion P (zinc portion) and lyophobic portion (epoxy resin portion) was prepared.
  • Grooves (transversal grooves. longitudinal grooves. mesh form grooves) several p. to several mm in depth and distributed in the proportion of l line/mm to lines/mm are prepared. for example, on a metal roller by using mechanical processing technique. chemical etching processing technique, or electric surface treatment technique.
  • the said grooves are filled with a lyophobic material such as an oil soluble resin to provide smoothpess on the surface of the said roller and to provide a lyophilic portion and lyophobic portion.
  • a lyophobic material such as an oil soluble resin to provide smoothpess on the surface of the said roller and to provide a lyophilic portion and lyophobic portion.
  • the material for the said roller such materials as synthetic resins. synthetic rubbers. glass. and ceramics are used besides metals.
  • grooves 50 a in depth and distributed in 2 lines/mm were engraved on the surface of a brass roller 30 mm in diameter and 2H) mm in length by using mechanical processing technique.
  • the said grooves were filled with epoxy resin by forming a uniform film of the resin on the surface of the said roller. After drying. the surface of the said roller was polished until the brass surface was revealed uniformly.
  • smooth surface S that has lyophilic portion P (brass portion) and lyophobic portion H (resin portion) was made.
  • the material for the screen materials such as fibers can be used besides metals.
  • materials such as fibers can be used besides metals.
  • a film of epoxy resin was formed to fill a stainless steel screen of 300 mesh with the resin. After drying. the surface was polished until the stainless steel screen was uniformly revealed.
  • a smooth screen 5 having lyophilic portion P (stainless steel screen portion) and lyophobic section H (resin portion) as shown in FIG. 12 (a) was obtained.
  • FIG. 13 and FIG. 14 show an example of developing device using a developing roller made by making the above-mentioned developer supplying means into a roller.
  • R and R rollers made of materials having a porous surface such as sponge or rollers having many grooves are desirable.
  • the developer L in the tank V is spread on the developing roller R
  • the photosensitive member 103 that comprises the base 101 and the photosen sitive layer 102 is charged by corona discharge in advance. and bears an electrostatic latent image that was formed by image projection undergoes wetting development by the developer L (Refer to FIG. I).
  • Developer L is coated on the lyophilic portion P of the surface S of developing roller R when the said photosensitive member 103 passes through the space between the developing roller R and feed roller R and a good quality visible image that corresponds to the electro static image can be obtained.
  • the tank V is filled with a solution 0 which is lyophobic to developer and the tank V is filled with a developer.
  • Each liquid is coated on the developing roller R by coating rollers R and R respectively. and distributed separately to the lyophilic portion P and lyophobic portion H of the surface.
  • the developer L is coated on the lyophilic portion P and the liquid 0 that is lyophobic to the developer is coated on the lyophobic portion P.
  • the developer portion is transferred to the intermediate lyophilic blanket roller R
  • the photoconductive body 163 that carries an electrostatic latent image passes between the blanket roller R and the feed roller R wetting development is done by the developer on the blanket roller R and a good quality visible image can be obtained. In this case the blanket roller R can be removed.
  • a metal roller. a semiconductive rubber roller. or a roller having the surface treated to be conductive or semiconductive is desirable as the feed roller R This limitation is not applied specifically when no voltage is applied.
  • FIGS. I6 through 21 show the third type ofdcveloper supplying means according to this invention.
  • the features lie in the depressions 202 such as grooves in the proportion of l line/mm to 20 lines/mm or conical holes in the proportion of l/mm to 2(J/mm. that are capable of holding the developing solution by means of capillary phenomenon. which are prepared on the roller or plate of the developer supplying means.
  • the bottoms of the depressions 202 are made ofa lyophilic materials and the surface of the projections 203 are made of a lyophobic material. With such a construction as described above, the developer 204 stays only on the depressions 202 and does not stick to the projections 203. Therefore, when arranged as shown in FIG.
  • the developer supplying means used in the abovementioned examples are all shaped in drums and so contracted that a hygroscopic supply roller, for example a rubber roller or a sponge roller, absorbs the developer in the developer tank and supply it to the drumshaped developer supplying means.
  • a hygroscopic supply roller for example a rubber roller or a sponge roller
  • FIGS. 22 and 23 show an example of a developing device that employes such a supply roller.
  • 303 is an electrophotographic photosensitive member comprising a base 302 and a photoconductive layer 301 formed on the base 302.
  • R is developing roller and R' is a feed and pressure roller for the photosensitive member 303
  • r is a developer supply roller which supplied the developer in the container V to the developing roller R.
  • the developing roller R can be a metal roller having a smooth surface. but an extremely good image can be obtained by using the abovementioned first to third types of developer supplying meansv S is a bias power source that applies a voltage across the rollers R and R.
  • P is a pressure spring that acts on the roller R and is so constructed that it presses the roller R only when feeding the photosensitive member 303 and pulls up the roller R when the photosensitive member 303 is not between the rollers R and R to prevent the rollers R and R from contacting with each other and the bias power source S from being shortcircuitted.
  • the developer supply roller r has the grooves 305 on its surface as shown in FIG. 23 which are formed by winding a fine wire 304 for example a fine metal wire or synthetic fiber bundle, around its surface.
  • the rotating direction angle 9 which is formed by the contact position of the supply roller r and the developing roller R and the contact position of the developing roller R and the paper feed roller R must be changed depending on the viscosity of the developer and the diameters of the rollers, it was experimentally confirmed that the angle lower than was desirable.
  • the developer is supplied to the photosensitive member by developer supplying means such as the developing roller and the said developer is wet applied to the electric latent image of the photosensitive member and the action of the said latent image.
  • developer supplying means such as the developing roller
  • the wetting development by means of developer supplying means such as the roller does not result in a sharp image of good resolution power unless the rollers of special constitution such as used in the first through the third types are used.
  • This invention includes the novel developing method as mentioned, in which a photosensitive member capable of controlling the ratio between the lyophilic portion and the lyophobie portion and the surface of the said photosensitive member uses a nonpolymer bonding agent which is uniformly constant with respect to the lyophilic and lyophobic propertiesv
  • the feature of this developing method is that; an electrostatic image is formed on a photosensitive member, the surface which has been made sufficiently lyophobic by the addition of a nonpolymer bonding material, for example a higher fatty acid.
  • the developer is poured onto the said surface; the interfacial tension that acts upon the surface of the developer and the surface of the photosensitive member is changed by the effect of the electrostatic latent image.
  • the electrostatic latent image causes a change in the shape and size, of the contact angle of the developer body that flows down on the photosensitive memher. As a result, only the region where the latent image,
  • FIG. 24 shows a photosensitive member that has a photoconductive layer on the base.
  • the photosensitive member 401 has a photoconductive layer made of zinc oxide and as the bonding material. nonpolymer material and a higher fatty acid (Refer to the examples 26 through 32 for the specific composition of the photosensitive member).
  • the photosensitive member 401 is placed on a metal holder 402.
  • the metal holder 402 is placed tilted with an angle of slope of 60.
  • An electrostatic latent image has already been formed on the photosensitive member 401.
  • a developer tank 403 is placed above the photosensitive member 401 and the said tank contains a developer for wetting development made by adding a coloring agent to water or t9 a watery solvent.
  • the developer in the developer tank 403 falls on the photosensitive member and the developer rotates on the photosensitive member in cascade because the photosensitive member is placed inclined.
  • the developer flows into the developer pan 406.
  • the developer wets and sticks to the latent image region of the photosensitive member. but the developer does not stick to the nonlatent-image region because the photosensitive member has a lyophobic surface there.
  • the developer continues falling.
  • the abovementioned developing method is extremely effective in practice because the said method does not need developing means such as the developer supply roller and allows a good quality image to be obtained. Refer to the examples 26 through 32 described later for specific composition.
  • the surface of the roller R was made of sheet zinc on which a photoresist dot pattern l50 lines/inch in density was prepared by planography print technique.
  • the developer L was supplied to the hydrophilic surface of the roller R uniformly from the developer container by using the developer supply roller r.
  • the roller r was a porous sponge roller 20 mm in diameter and 210 mm in length. Thus a black positive visible image, that corresponded to the electrostatic charge pattern and was excellent in hlaf tone, was obtained.
  • EXAMPLE 2 I00 ml 50ml Water India ink (Taguchi Col An exposure of about 400 Lux-sec was given using a 60 W tungsten lamp (at a distance of 50 cm) by way of a positive original pattern. A good quality positive visible image was obtained after development that is similar to the Example I.
  • the developing roller R was an alumi num roller. 30 mm in diameter and 210 mm in length. having a surface almite plated.
  • EXAMPLE 3 A photosensitive member was obtained by dissolving 4 gr ofzinc naphthenade completely into 30 ml of toluene and by dispersing 10 gr ofZnO in the same manner as the Example I. A 2-minute of image projection with a 60 W tungsten lamp and a distance of 30 cm was given to the photosensitive member in advance by way of an positive original pattern, and then development was performed in the same manner as the Example 2. In this case a voltage of 500 V was applied across the developing roller R and paper feed roller R from the DC power source, having the polarity on the roller R and polarity on the roller R. The roller speed was 10 cm/sec. A good quality positive visible image that corresponded to the conductive latent image was obtained.
  • EXAMPLE 4 A photosensitive member was prepared by applying a uniform 8 p. thick coat of an emulsion, obtained by first dissolving 2 gr. of abietic acid in 30 ml of ethylalcohol and by dispersing 10 gr of ZnO and 0.l gr of tributyl phosphate for about 7 minutes with ultrasonic waves, to the surface of the art treated paper about [.t in thickness (RH: 50%, resistance: l0 l 0".0. -cm), and by natural drying the paper for 3 days in the dark.
  • RH 50%, resistance: l0 l 0".0. -cm
  • an electroconductive latent image was formed by exposing image-wise for I second in the dark place from a I00 W tungsten lamp (30 cm in distance) by way of a positive original pattern, then the said latent image was converted into an electrostatic charge latent image by a device as shown in FIG. 2, which is provided with conductive rollers C and C.
  • the photosensitive side I was made to have the polarity and the base side was made to have the polarity. then a voltage of 500 V was applied from the DC power source 6 across the roller electrodes and the photoconductive member was made to close contact with the rollers and be charged.
  • An electrostatice latent image was formed

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US5456782A (en) * 1991-10-24 1995-10-10 Ricoh Company, Ltd. Toner carrier and method of producing the same
US5943535A (en) * 1996-10-04 1999-08-24 Brother Kogyo Kabushiki Kaisha Device for developing a latent image with a water-based developing liquid
US6861377B1 (en) * 2002-03-27 2005-03-01 Seiko Epson Corporation Surface treatment method, surface-treated substrate, method for forming film pattern, method for making electro-optical device, electro-optical device, and electronic apparatus
US20060110545A1 (en) * 2004-11-25 2006-05-25 Seiko Epson Corporation Method of forming conductive pattern
US20060175824A1 (en) * 2003-02-13 2006-08-10 Fausto Giori Method for printing a security element and security element
US20060188661A1 (en) * 2005-02-23 2006-08-24 Seiko Epson Corporation Method of forming film pattern, method of manufacturing device, electro-optical device, and electronic apparatus

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US5456782A (en) * 1991-10-24 1995-10-10 Ricoh Company, Ltd. Toner carrier and method of producing the same
US5783288A (en) * 1991-10-24 1998-07-21 Ricoh Company, Ltd. Toner carrier and method of producing the same
US5943535A (en) * 1996-10-04 1999-08-24 Brother Kogyo Kabushiki Kaisha Device for developing a latent image with a water-based developing liquid
US6861377B1 (en) * 2002-03-27 2005-03-01 Seiko Epson Corporation Surface treatment method, surface-treated substrate, method for forming film pattern, method for making electro-optical device, electro-optical device, and electronic apparatus
US20060175824A1 (en) * 2003-02-13 2006-08-10 Fausto Giori Method for printing a security element and security element
US20060110545A1 (en) * 2004-11-25 2006-05-25 Seiko Epson Corporation Method of forming conductive pattern
US20060188661A1 (en) * 2005-02-23 2006-08-24 Seiko Epson Corporation Method of forming film pattern, method of manufacturing device, electro-optical device, and electronic apparatus

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