Abstract: The present invention provides a method for making an electrophotographic printing plate by reversal development which comprises uniformly charging the surface of an organic photoreceptor comprising an electrically conductive support and, provided thereon, an organic photoconductive compound bound with a resin binder, exposing the surface to a light image to form a static latent image corresponding to the light image on the surface of the organic photoreceptor and then, subjecting the static latent image to reversal development with an electrophotographic liquid developer containing charged toner particles, characterized in that the reversal development is carried out with the electrophotographic liquid developer having an electrodeposition potential set within the range of 0-80 V in absolute value.

Abstract: Imaging apparatus including an image forming surface, image forming apparatus for defining an electrostatic latent image on the image forming surface, the latent image having image portions and background portions, development apparatus for developing the electrostatic latent image in a reversal mode, using electrically charged pigmented toner particles to form a developed image overlying the image portions, whereby the developed image on the image forming surface is at a first electrical potential and the background portions on the image forming surface are at a second electrical potential, discharge apparatus for partially discharging the image forming surface so that the developed image is at a third electrical potential and the background portions are at a fourth potential and an image receiving surface at a fifth potential, for receiving the developed image from the image forming surface, wherein the difference between the fourth potential and the fifth potential is low enough such that substantially no

Abstract: The present invention relates to electrophotographic printing and, in particular, to a process for plural color electrophotographic printing with controlled deposition of each color during the printing process.

Abstract: Imaging apparatus including an image forming surface, image forming apparatus for defining an electrostatic latent image on the image forming surface, the latent image having image portions and background portions, development apparatus for developing the electrostatic latent image in a reversal mode, using electrically charged pigmented toner particles to form a developed image overlying the image portions, whereby the developed image on the image forming surface is at a first electrical potential and the background portions on the image forming surface are at a second electrical potential, discharge apparatus for partially discharging the image forming surface so that the developed image is at a third electrical potential and the background portions are at a fourth potential and an image receiving surface at a fifth potential, for receiving the developed image from the image forming surface, wherein the difference between the fourth potential and the fifth potential is low enough such that substantially no

Abstract: The present invention relates to a xeroprinting process, in particular a xeroprinting process comprising the following steps:(a) image-wise exposing to actinic radiation an electrostatic master having a photopolymerizable conductive layer to selectively polymerize and thereby increase resistivity in exposed areas of the layer;(b) forming a latent image of electrostatic charge by charging the master by corona discharge;(c) reversal developing the latent electrostatic image by depositing toner particles in the non-exposed areas of the layer;(d) transferring the toner image to another substrate and subsequent fusing;(e) resetting the process by cleaning and discharging the electrostatic master.According to a preferred embodiment the reversal development is effected by means of a development electrode inducing charges in the photopolymer plate opposite to the initial electrostatic image, and by means of dry electrophotographic toner.

Abstract: An electrophotographic photosensitive member has a charge-generating layer which includes selected photosensitive pigment particles and a compound which is a tetracyanoanthraquinodimethane compound, an anthraquinone compound, a dicyanovinyl compound, or a special quinone compound. The compound is incorporated in an amount in a range from 0.01 to 2 molar equivalents, preferably 0.1 to 1 molar equivalent, to the pigment, which has a positive hole transporting property. The photosensitive member has a charge-transporting layer and can also have a protective layer. The pigment is a phthalocyanine series pigment, a squearyrium series pigment, or a perylene series pigment. A process of using the photosensitive member includes reversal development and multicolor toner transfer. It is found that the process is adaptable to change in size of the transfer medium.

Abstract: An electrophotographic photosensitive member has a charge-generating layer which includes selected photosensitive pigment particles and a compound which is a tetracyanoanthraquinodimethane compound, an anthraquinone compound, a dicyanovinyl compound, or a special quinone compound. The compound is incorporated in an amount in a range from 0.01 to 2 molar equivalents, preferably 0.1 to 1 molar equivalent, to the pigment, which has a positive hole transporting property. The photosensitive member has a charge-transporting layer and can also have a protective layer. The pigment is a phthalocyanine series pigment, a squearyrium series pigment, or a perylene series pigment. A process of using the photosensitive member includes reversal development and multicolor toner transfer. It is found that the process is adaptable to change in size of the transfer medium.

Abstract: Process for reversal development of a latent electrostatic image in a layer on a conductive support by developing with an electrostatic developer having electrostatically charged toner particles by(a) generating imagewise areas in the layer having different rates of charge decay and/or charge acceptance,(b) charging the layer,(c) allowing formation of an electrostatic image corresponding to the imagewise generated areas by differential charge decay and/or charge acceptance,(d) creating an electrical field to attract toner particles preferentially to the areas of lesser charge, and(e) developing the areas of lesser charge with electrostatically charged toner particles having the same polarity as that of the charged layer.The developed image can be transferred to a receptor surface, e.g., paper. The process is useful with many type photosensitive masters in preparing reversal images with the use of only one master, toner and film original.

Abstract: A negative chargeable developer for developing electrostatic latent images, comprises a toner, and hydrophoic silica fine powder treated with an agent represented by the following compositional formula (I): ##STR1## wherein R.sub.1 denotes an alkyl or alkoxy group, R.sub.2 denotes an alkyl group having 1-3 carbon atoms, R.sub.3 denotes a long-chain alkyl group, a halogen-substituted alkyl group, phenyl group, or a phenyl group having a substituent, and m, n, m' and n' are independently 0 or a position integer satisfying the relationship of n>m, n'>m' and n+m+n'+m'<30.

Abstract: A method of producing positive multicolor proofs electrostetically including the steps of charging a photoconductor, exposing the charged photoconductor to a negative film, forming a latent electrostatic image on the photoconductor, transfer toning said latent image by virtual contact with a donor member carrying an electrostaticially deposited toner layer. The image remaining on the donor member is transferred to the printing stock paper forming the positive proof. Multiple images are formed from successive film negatives and transferred successively on the printing stock.The deposited form layer is split, between the charged areas on the photoconductor and the image areas on the donor member.

Abstract: A process for producing a reversed image proof from a negative film separation (66) including applying a uniform toner layer (60) to an offset member (46), exposing a charged surface (20) through the film separation (66) to produce unexposed non-image areas (68) and exposed image areas (70) thereon, contacting the offset member (46) to the charged surface (20) to transfer toner (74) from the offset member (46) to the surface (20) in the non-image areas (68), leaving an image residue (76) upon the offset member (46), and contacting the offset member (46) to a receptor (49) to transfer the image (76) thereto. The process may be repeated for subsequent colors to produce a positive multicolor image and may also be adapted to conventional proofers formerly capable of producing images from positive film separations only.

Abstract: A method of using a liquid electrophotographic toner with a permanent master to electrostatically transfer a electrophotographically developed electrostatic image via a reversal photographic process from the permanent master to a receiving surface is disclosed. The permanent master is made from a multilayer plate of a photopolymer material and a protective overcoated material whose surface is hard, low friction and acts as a physical and chemical barrier.

Abstract: A method of reverse development for depositing the toner particles to the light potential area of a photosensitive member. The developer used contains magnetic carrier particles and toner particles. An alternating electric field is formed in the developing position or zone. A relative volumetric ratio Q (%) of the magnetic carrier particles in the developing position satisfies 15.0.ltoreq.Q.ltoreq.28.0. The relative volumetric ratio is defined asQ=(M/h).times.(1/.rho.).times.C.sigma./(T+C)where M (g/cm.sup.2) is an amount of applied developer on a developing sleeve surface per unit area, h (cm) is a height of space in the developing position, .rho. (g/cm.sup.3) is a true density of the magnetic carrier particles, C/(T+C) (%) is a weight ratio of the carrier particles in the developer on the surface of the sleeve, and .sigma. is a ratio of a peripheral speed of the sleeve relative to the peripheral speed of the photosensitive member.

Abstract: A reverse development method comprising the steps of forming electrostatic image on the surface of an image-bearing member; supplying a developer comprising chargeable magnetic toner based on magnetic powder and a resin development roll comprising a conductive core, a permanent magnet arranged around the conductive core and a dielectric layer provided around and fixed to the permanent magnet and having conductive particles mutually insulated from each other; conveying the developer onto a surface of the image-bearing member by rotation of the developement roll so that the magnetic toner is attracted to the uncharged portions of the image; characterized in that the chargeable magnetic toner contains an aliphatic acid metal salt and is coated with hydrophobic silica.

Abstract: A developer for developing electrostatic latent images comprises negatively chargeable toner particles and hydrophobic, negatively chargeable silica fine power,said silica fine powder being obtained by treating silica fine powder with a silane coupling agent represented by the following formula:R.sub.m SiY.sub.n or Y.sub.3 --Si--NH--Si--Y.sub.3and treating further said treated silica fine powder with a silicone oil having the structure: ##STR1## An image forming method comprises forming an electrostatic latent image on a photosensitive drum; developing said latent image with a developer to form toner images, said developer comprising negatively chargeable toner particles and, hydrophobic, negatively chargeable silica fine powder,said silica fine powder being obtained by treating silica fine powder with a silane coupling agent represented by the following formula:R.sub.m SiY.sub.n or Y.sub.3 --Si--NH--Si--Y.sub.

Abstract: An image forming method wherein a latent image is formed by subjecting an image retainer having a photoconductive layer to a image exposure, a toner image is formed by developing the latent image with a toner, each the step of forming the latent image and the step of forming the toner image are repeated at least one time, and a plurality of toner images formed on the image retainer to a transfer material. At least one of the toner images is formed with a toner which has a spectral transmissivity as to substantially absorb a visible light but transmit a light having a wavelength of 750 nm or more. The latent image is formed by subjecting the image retainer bearing the toner image to an image exposure with a light containing a wavelength component of 750 nm or more.

Abstract: By utilizing an electrophotographic image forming process, a reversal image can be obtained in the following manner:charging a photosensitive member;forming an electrostatic latent image in a charged surface of the photosensitive member;developing the electrostatic latent image formed on the photosensitive member by using white toner;charging the photosensitive member again;developing the surface of the photosensitive member by using other toner different in color from the white toner; andtransferring the toner image formed on the photosensitive member onto a paper sheet.

Abstract: An image editing method utilizing an electrophotographic process, which method includes a first charging step of charging a photosensitive medium; a step of projecting an image onto the charged photosensitive medium to form an electrostatic latent image; a first developing step of developing the electrostatic latent image into a first powder image by the use of a first toner material having the same polarity as the charged polarity; a first transferring step of transferring the powder image onto a copying paper; a second charging step of again charging the photosensitive medium to a polarity the same as that of the charge established during the first charging step; a step of radiating rays of light to the charged photosensitive medium to remove the electrostatic charge at a specificed area of the photosensitive medium; a second developing step of developing the specified area of the photosensitive medium by the use of a second toner material different in color from the first toner material to form a second po

Abstract: An electrophotography apparatus of the present invention includes a movable photoconductive drum capable of carrying an electrostatic latent image on its surface, and a plurality of electrophotographic process means located along a moving direction of the photoconductive drum. A first or second static latent image is formed on the photoconductive drum charged by a main charger, at a first or second exposure radiating portion. In this case, the first and second exposure radiating portions are selectively operated in accordance with whether an original image is a positive or negative film, the first static latent image, formed at the first exposure radiating portion, is reversely developed by a first developing unit, and the second static latent image, formed at the second exposure radiating portion, is normally developed by a second developing unit.

Abstract: An electrophotographic device performing reversal development to develop the portion with lower absolute value of potential in an electrophotographic process having steps of primary charging, imagewise exposure, developing and cleaning, and having a photosensitive member of the lamination type which uses a layer coated with an organic pigment dispersed in a solvent or in a solvent and a polymer binder, as the charge generation layer, wherein the potential of the photosensitive member and process conditions are under constant conditions, said constant conditions being within the range as defined by the following formula of Vd, t and V.sub.H, when the surface potential of the photosensitive member immediately after charged with a primary charger is defined as Vd (V), the time from primary charging to toner development as t (sec) and further the surface potential of the photosensitive member at which the toner developing density becomes the half value of the saturated density as V.sub.H (V):.vertline.V.sub.H .

Abstract: An electrophotographic copying method for optionally producing either reversal or positive-positive copies from any original using the same photoconductive element and the same toner developing material by varying the exposure and electrostatic charging conditions.

Abstract: A reversal development method comprising the steps of forming a latent electrostatic image on the surface of an image-carrying member having predetermined charging characteristics; supplying a developer to a non-magnetic, conductive sleeve containing a magnetic field-generating means and positioned opposite to the image-carrying member, the developer comprising a magnetic toner consisting essentially of a resin and magnetic powder and adapted to be charged with the opposite polarity to that of the latent electrostatic image; conveying the developer onto the image-carrying member surface by relative rotation of the sleeve to the magnetic field-generating means; and applying DC voltage of the same polarity as that of the latent electrostatic image to the sleeve so that the magnetic toner is attracted to the nonimage areas of the latent electrostatic image.

Abstract: A method of using a dry powder electrophotographic toner with a permanent master to electrostatically transfer a electrophotographically developed electrostatic image via a reversal photographic process from the permanent master to a receiving surface is disclosed. The permanent master is made from a photopolymer material and is protected by a transparent overcoated material whose surface is hard and low friction.

Abstract: The present invention relates to a method for forming an outline of an image. By this method, at first, an electrostatic latent image bearing member is charged and then irradiated to a negative image to form an electrostatic latent image. Thereafter, the irradiated member is re-charged with a scorotron charger while applying a voltage to a grid, said voltage being lower than the surface potential of the non-image portion of the latent image, being higher than the potential of the image portion of the latent image and being of the same porality as that of the charging. By this re-charging, in one embodiment, the outline portion of the image has lower potential than the other portion. Then, the outline portion of the image with lower potential is visualized with a reversal development by using a toner charged to a polarity same as the polarity of charging.Or in another embodiment, the outline portion of the image has higher potential than the other portion.

Abstract: The invention disclosed relates to an image forming method using long wavelength light source. The method comprises a first step of charging and irradiating a photosensitive member to thereby form a negative electrostatic latent image; a second step of developing said negative electrostatic latent image by a reversal development; a third step of irradiating said photosensitive member with long wavelength light; a fourth step of transferring the developed electrostatic latent image to a paper; and a fifth step of irradiating said photosensitive member with long wavelength light. Said irradiating light used at the third step has the same or close wavelength region as the one used at the first step, and further, said irradiating light used at the fifth step has the same or close wavelength region as the one used at the first and third steps.

Abstract: The invention disclosed relates to a method of forming composite images. A photosensitive member including an electroconductive base, a photoconductive layer and an insulation layer in a superposed arrangement is used and to this photosensitive member, a negative image is exposed while simultaneously charging, irradiating with light, charging by an a.c. corona charging means and then exposing a positive image to form a composite electrostatic latent image. If the positive image overlaps with the negative image, the positive image is formed in preference.

Abstract: A method for preparing a lithographic printing plate is disclosed. The method involves providing a light-sensitive material comprised of an electroconductive support having a hydrophilic surface. The surface has provided thereon a light-sensitive layer and a photo-conductive insulating layer which may be provided in that order or combined in a single layer. The material is imagewise exposed and then subjected to electrophotographic processing to form an electrostatic latent image on the photoconductive insulating layer. After exposure the electrostatic latent image is developed with developer particles which are opaque to the light to which the light-sensitive layer is sensitive in the presence of an electrode facing the photoconductive insulating layer. The development is carried out while applying a bias voltage between the electrode and the light-sensitive layer so that residual charge on the non-latent image areas appears zero.

Abstract: An electrophotographic liquid developer is disclosed which is useful in the development of negatively charged charge images. The developer comprises an electrically insulating carrier liquid of high electrical resistivity and a low dielectric constant, a pigment or dye, a resinous binder, a charge controller comprising a copolymer of N-vinyl-2-pyrrolidone and a methacrylic acid ester, and a poly-N-vinyl-2-pyrrolidone which has been alkylated with an .alpha.-olefin. A process for producing the liquid developer is also disclosed.

Abstract: A novel method and apparatus for electrophotography is disclosed which enables selection the mode of image formation among positive-positive, negative-positive and combinations thereof without any need of changing the polarity of developing toner. The present invention is made on the basis of a known electrophotographic system in which a photosensitive member composed of essentially an electrically conductive substrate, a photoconductive substance layer and an insulating surface layer and which comprises the steps of charging the insulating surface layer, image-wise exposing it to light so as to form a first image almost simultaneously with or some time after the charging step, subjecting it to corona discharge with nearly simultaneous image-wise exposure so as to form a second image and uniformly exposing the whole surface of the photosensitive medium to light so as to form an electrostatic latent image corresponding to a composite image resulting from the first and second images.

Abstract: This invention provides a process for making image overlay through the steps constituting an electrophotographic process, and also an apparatus adapted for conducting such process. The process, based on an electrophotographic process utilizing a three-layered photosensitive member having an insulating cover layer, comprising exposing the photosensitive member to a first image-forming irradiation to be overlaid substantially simultaneously with or subsequent to a charging on the surface of the insulating layer, then exposing the photosensitive member to a second image-forming irradiation to be overlaid substantially simultaneously with an AC or DC corona discharge given to the photosensitive member, and subsequently giving a uniform exposure to the surface of said photosensitive member thereby obtaining an electrophotographic overlay image of the first and second irradiations.

Abstract: An electrophotographic process including forming, on a photosensitive plate, an electrostatic latent image corresponding to optical information, developing the latent image by the reversal development and transferring the developed image onto a transfer material includes the improvement whereby a voltage of polarity opposite to that of the developer is applied to the photosensitive plate at least during the time from the end of the reversal development to the transfer step. This improvement in the electrophotographic process and apparatus for same prevents developer particles from being scattered away from the photosensitive plate and thereby also avoids the trouble of distortion of the image at the transfer step.

Abstract: An electrophotography developing method according to this invention uses a one-component magnetic toner having an electric resistivity of 10.sup.7 or more ohm.multidot.centimeter, still remaining within the range of inter-particle electric induction, and a coercive force of 150 or more oersteds, thereby preventing appearance of fog in a reversal photographic image, which fog otherwise, would appear in case of reversal, magnetic brush development.

Abstract: An electrophotographic copying process utilizes a photosensitive member for electrophotography which comprises a first and a second photoconductive layer which are sensitive to radiation of a first and a second wavelength region, respectively.

Abstract: A two-component type dry developer for use in dichromatic electrophotography comprising two kinds of developers, said developers each consisting of a toner and a carrier therefor and adapted for the production of a dichromatic image by developing a both positively and negatively electrified electrostatic latent image successively with toners different in polarity and color from each other, wherein one carrier has a triboelectrification property of being electrified positively by friction with either of two toners while the other carrier has a triboelectrification property of being electrified negatively by friction with either of two toners.

Abstract: A bimodal electrophotographic apparatus and process which incorporates capabilities for making both positive and reversal copies. One surface of a layer of a zinc oxide coated paper, or the like, is given an initial electrostatic charge. The charged surface is then exposed to an image having light and dark areas for causing surface charge to dissipate, in varying degree depending on the amount of light striking the charged paper, in the exposure areas. A charged toner is applied to the zinc-oxide-coated paper by a magnetic brush. In the reversal mode, the brush has a bias potential. The brush is formed by an aggregation of magnetic toner particles clinging to the outside of a cylindrical sleeve while magnets inside the sleeve rotate. The toner collects on the paper to form an image depending upon where the charge is dissipated.

Abstract: An improved reversal development method of visualizing an electrostatic latent image through reversal development, including the steps of: forming a magnetic brush around an outer circumferential surface of a developing sleeve by the use of a developer composed of high-resistivity toner having a resistance value of 10.sup.13 .OMEGA.cm or more under an electric field of 10.sup.4 V/cm and a charge amount of 5 to 15 .mu.Q/g per unit mass generated by gaseous discharge; and applying simultaneously an a.c. bias, and a d.c. bias approximately equal to a sum of a potential of an image portion of the electrostatic latent image and a potential of its non-image portion to the magnetic brush.

Abstract: An electrostatic photographic method for reversal development using a magnetic brush, with the magnetic brush and photoconductive drum being grounded, and with the development being performed using a dry reversal developer comprising 100 parts by weight of a carrier having ferromagnetic properties and 1 to 10 parts by weight of a toner having a volume specific resistance falling within the range between 3.5.times.10.sup.9 and 1.times.10.sup.11 .OMEGA.-cm.

Abstract: A copy paper separating method for use in an electrophotographic copying apparatus which forms a latent electrostatic image on a recording member is provided. The method includes the step of depositing fine particles having insulating properties and charged to a polarity opposite of that of the toner image on the surface of the recording member before the copy paper is placed over the recording member, to cause the particles to reduce the electrostatic attraction between the copy paper and the recording member, thereby facilitating separation of the copy paper from said recording member.

Abstract: A reverse development is performed with application of development bias voltage to a development sleeve at the time of development, and the polarity of the bias voltage is reversed or the bias voltage is reduced to zero at the time of non-development. Furthermore, positive images and negative images can be selectively formed by changing the voltage to be applied to a charge injection electrode, without changing the bias voltage to be applied to the development sleeve.

Abstract: A method of electrophotography in which an electrostatic latent image is formed on the surface of a material layer and a non-magnetic cylinder is provided to confront the surface of said material layer. A permanent magnet roll made up of a plurality of symmetrically arranged magnetic poles extends axially in said cylinder. A magnetic brush is formed by attracting a semiconducting or insulating magnetic toner onto the cylinder with the aid of a magnetic attraction force of the permanent magnet roll. The cylinder and permanent magnet roll are moved relative to each other to permit the magnetic brush to slide along the surface of the material layer thereby to allow the magnetic toner to adhere at predetermined position on the surface of said material layer, and a toner image is transferred onto a transferring member and is then subjected to fixing.

Abstract: An electrophotographic process comprising uniformly charging a composite photosensitive body with a charging polarity exhibiting a response property to a visible light, said composite photosensitive body being composed of a photoconductive semiconductor for producing carrier when illuminated by the visible light and a light transmitting organic photosemiconductor superimposed one upon the other, illuminating the charged composite photosensitive body with a light image by the visible light and producing thereon a first electrostatic latent image and producing thereon a second electrostatic latent image based on said first electrostatic latent image, said second electrostatic latent image having a polarity which is opposite to said charging polarity.

Abstract: The sharpness and contrast of reversed images obtained by pressure-fixation of electrostatically developed copies of negative transparencies is provided by dissipating the electrostatic latent image after the development step but before the pressure-fixing step. The process finds application in microfilm reader/reproduction devices.

Abstract: A reversal developing process carried out preferably with an inductively chargeable magnetic powdery developer. An electrostatic latent image having first charged areas and second lesser charged areas formed on a photoreceptor or a photoconductor is developed negatively by forming a toner brush of single component, i.e., inductively chargeable, magnetic powdery developer on a shell incorporating a permanent magnet to adhere the developer on the first charged areas, charging uniformly the developed photoreceptor with the same polarity as the first charged area and further rubbing the surface of the photoreceptor with a second toner brush to remove the previously adhered developer from the surface and to adhere powdery developer onto the second lesser charged areas. The apparatus includes two applicators for powdery developer positioned along the path of movement of the latent image with a D.C. charger stationed between the applicators.

Abstract: This invention presents a process and an apparatus for repeatedly forming a high contrast image on a photosensitive member substantially comprising a conductive layer, a photoconductive layer and an insulating layer. According to this invention, during the processing steps of a latent image formed on the photosensitive member, an exposure step or means is provided for preventing the effect of a corona discharge of the same polarity as of the polarity of the photoconductive layer from affecting the succeeding latent image formation on the photosensitive member.

Abstract: For reversal development of an electrical potential pattern formed by imagewise exposure of a uniformly charged photoconductive layer, the charging of the layer is restricted to such a level below its breakdown voltage that the contact between the photoconductive layer and the toner powder used in the development step is insulating, and a magnetisable and inductively attractable toner powder is applied for the development. The toner powder is applied by means of a magnetic brush device comprising a conductive development roller which is provided with an electrical potential suited for reversal development. Preferably the photoconductive layer is charged to a level of at most 35-75% of its breakdown voltage, and a scorotron preferably is used for the charging. The photoconductive layer may comprise a photoconductive polymer and/or a bisazo pigment as photosensitive compound, or may be a layer of "pink" zinc oxide dispersed in a binder.

Abstract: A process for the ink development of an electrostatic image comprising the steps:(a) forming an electrostatic image on a charge retaining surface,(b) wetting the charge retaining surface with a thin layer of dielectric liquid which is chemically inert toward the surface,(c) inking the charge retaining surface with an electrically conductive liquid ink formulation which is immiscible with the dielectric liquid,(d) inducing at the interface between the ink and the dielectric liquid a charge differential with respect to the electrostatic image on the charge retaining surface, and, when the induced charge density at the dielectric liquid-oil interface exceeds a threshold value,(e) penetrating the dielectric liquid with the complete ink formulation, and(f) wetting the charge retaining surface with the ink formulation.

Abstract: This specification discloses an electrophotographic process for forming an electrostatic latent image on a photosensitive medium which may consist of an insulative layer and a photoconductive layer (and further an insulative layer), and also discloses an apparatus for carrying out the process. The electrophotographic process essentially comprises the primary charging step of uniformly charging the insulative layer of the photosensitive medium, and the step of contacting a liquid with said insulative layer and applying a desired voltage to the liquid to thereby discharge or charge the liquid and substantially simultaneously therewith, applying light from an object image to the photoconductive layer of the photosensitive medium. The process may further comprise other various steps as required in electrophotography, such as overall or blanket exposure, development, image transfer and cleaning of the photosensitive medium.

Abstract: This invention provides a dry planographic printing plate prepared by forming on an electrically conductive support a photoconductive layer composed of a binder and photoconductive powder dispersed in the binder, charging and then image-exposing a resultant photosensitive plate, and finally developing by means of a conductive toner and fixing the conductive toner. This invention also provides a dry planographic printing method including reversal-developing said printing plate by using a toner, transferring the toner to a sheet of transfer material, and then fixing the toner, as well as an apparatus used in said printing method.