Abstract: A method of making a colour display screen for a television display tube is disclosed. On the window portion of the tube an electron-absorbing layer is provided which is scanned by means of an electron beam via the shadow mask. The charge image on the layer is then developed xerographically. The layer is preferably photoconductive so as to be able to remove the charge remaining after the development by means of a uniform exposure.

Abstract: An electrophotographic method and apparatus is disclosed which is able to faithfully reproduce the half-tone portion of an original image on a photosensitive medium having an electroconductive layer, a photoconductive layer and an insulating surface layer. The present invention is directed particularly to improvements in the secondary charging step in the above method. According to the invention, the process of secondary charge includes the steps of subjecting the photosensitive medium to the action of corona discharge having the component of opposite polarity to that of the primary charge with simultaneous light image exposure, exposing the photosensitive medium surface to a light image while reducing or stopping the action of corona discharge and exposing the photosensitive medium surface to a light image while controlling the amount of corona discharge.

Abstract: A photosensitive member for electrophotography basically comprises a conductive support, on the surface of which a photoconductive layer and a transparent insulating layer are sequentially laminated. The photosensitive member is adapted to be used in a process for forming an electrostatic latent image including sequential steps of a primary corona charging concurrent with imagewise exposure, a secondary corona charging and a flush irradiation. The surface of the conductive support is treated to a mirror finish, based on experimental finding that the contrast voltage of the latent image depends on the degree of surface roughness of the support.

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: An electrophotographic imaging process having a double charging sequence and a photoreceptor utilized therein are provided, wherein the photoreceptor comprises a substrate, a photosensitive layer comprising a squaric acid methine dye, and an insulating layer. The photosensitive layer may also comprise a squaric acid methine dye and a charge transport material.

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 for forming a given number of copies of an original once formed on a photosensitive member including a conductive drum, a photoconductive layer applied on the drum and an insulating layer applied on the photoconductive layer. The photosensitive member is first subjected simultaneously to a uniform exposure and a primary charging in one polarity, and then is subjected simultaneously to an imagewise exposure and a secondary A.C. charging. Next, the photosensitive member is subjected to a secondary uniform exposure with a reduced light intensity to such an extent that the charge image has an electrostatic contrast which is about 60 to 90 percent of the maximum attainable value. During the formation of copies by repeated development and transfer, the photosensitive member is subjected to an additional uniform exposure to restore the deterorated charge image.

Abstract: A method for forming images comprises applying voltage or electric charge to one or more electrodes selected from an electrode group comprising electrodes each of which has a transistor and attaching a toner to the selected electrodes. A device for forming images comprises an electrode group and a toner supplying device, each of electrodes of the electrode group being provided with a transistor.

Abstract: An electrophotographic process for forming an electrostatic latent image in a photosensitive member. The photosensitive member is formed by applying, on a transparent conductive substrate, a transparent insulating layer and a photoconductive layer, which photoconductive layer is composed of a charge transfer layer and charge generation layers applied on both surfaces of the charge transfer layer. The charge transfer layer has a high mobility for charges of positive polarity. At first, the photosensitive member is negatively charged, while the member is uniformly irradiated from the side of the substrate. Then the photosensitive member is positively charged, while the member is exposed to a positive image of a document from the side of the photoconductive layer. Finally, the photosensitive member is exposed to a negative image of the document from the side of the photoconductive layer to form the electrostatic latent image from charges trapped across the insulating layer.

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. The photosensitive member may be subjected to steps of imagewise irradiation simultaneously with charging, then inverse charging, then uniform exposure and the like to form a positive or a negative electrostatic latent image. The electrostatic latent image thus formed is repeatedly subjected to a developing and a transfer step to produce a number of copies.

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: 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: In a process for forming electrophotographically a duplicated copy of a document by modulating a corona ion stream passing through fine apertures of a photosensitive screen in accordance with a primary electrostatic charge latent image formed on the photosensitive screen use is made of the photosensitive screen comprising an electrically conductive sheet-like member having a great number of fine apertures, a photoconductive member applied on at least one side of the conductive member and an electrically insulating member applied on the other side of the conductive member, the conductive member being completely surrounded by the photoconductive and insulating members.

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: An electrophotographic copying process employs a photosensitive member which includes a conductive layer carrying a sequential lamination of a photoconductive layer which is sensitive to visible light and a function layer different therefrom, forms an electrostatic latent image by trapping charge on opposite sides of either of the photoconductive layer and the function layer in such a condition that a layer which is not retaining the charge is one of photoconductive layers forming the photosensitive member, and repeatedly employs the electrostatic latent image to produce a plurality of copies. During the copying step for producing a plurality of copies, a uniform exposure by light rays which activate the one of photosensitive layers forming the photosensitive member which is not retaining the charge is applied to the photosensitive member.

Abstract: An information image of a first original and an information image of a second original are synthesized on a photoconductor which includes a photoconductive layer having a spectral sensitivity to A-colored light but not having a spectral sensitivity to B-colored light, and a photoconductive layer having a spectral sensitivity to B-colored light, but not having a spectral sensitivity to A-colored light, which are formed in layers on a conductive base member, by taking the steps of charging the photoconductor to a predetermined polarity and then charging the photoconductor to reverse the original surface potential of the photoconductor, while retaining the charges applied to the photoconductor, to the extent that latent electrostatic images can be formed on the surface of the photoconductor, and exposing the photoconductor to an A-colored light image corresponding to the information image of the first original and a B-colored light image corresponding to the information image of the second originals simultaneous

Abstract: A photosensitive member is formed by applying on an electrically conductive substrate, a first photoconductive layer sensitive to a visible light, an insulating charge retentive layer, and a second photoconductive layer sensitive to ultraviolet light, successively in this order. At first the photosensitive member is uniformly charged to a negative polarity, while the photosensitive member is uniformly exposed to the visible light. Then an image of a document to be copied is projected while the photosensitive member is charged to a positive polarity. After that the photosensitive layer is uniformly exposed to the visible light and finally the photosensitive member is uniformly exposed to the ultraviolet light. In this manner, an electrostatic charge image having high contrast and resolution is formed in the photosensitive member by means of charges which are stably trapped across the charge retentive layer.

Abstract: An electrophotographic method, in which a dielectric film is contacted with a surface of a charged and exposed electrophotographic layer and said film is acted on by positive and negative ions of the same concentration from a source of ions, which settle on the film and produce a latent image thereon. Then the electrophotographic layer is illuminated by an actinic light source to preserve the latent image on the film and the film is separated from the electrophotographic layer while being illuminated or after that. Thereafter the latent image obtained on the film is developed and fixed.

Abstract: In an electrically activatable recording element improvements are provided by an electrically conductive interlayer (ECI layer) separating (a) an electrically activatable recording layer from (b) a photoconductive layer or electrical activating means. The ECI layer comprises electrically conductive particles uniformly dispersed in an electrically insulating binder. The interlayer enables imaging with a minimized air gap between (a) and (b). The recording element is room light handleable. The element provides an image by dry development processing or by means of processing solutions.

Abstract: An image-forming method suitable particularly for copying using image exposure wavelengths of 700 to 850 nm such as are experienced with semiconductor laser beam printers. Useful photosensitive members include photoconductive layer prepared from a dispersion of a photoconductive material including at least cadmium sulfide in a resin binder. The photosensitive member is sequentially subjected to a plurality of prehysteresis operations, each comprising electrostatically charging the member and uniformly exposing the same to light until the photosensitivity of the photosensitive member has been substantially stabilized.

Abstract: An electrophotographic process comprising the steps of providing a composite photosensitive member consisting of a conductor, an intermediate layer of organic insulator, a photoconductive semiconductor layer as a charge generating layer formed on the conductor and a transparent photo semiconductor layer as a charge retentive and transporting layer; forming on the composite photosensitive member an electrostatic latent image corresponding to an image of a document to be copied; obtaining desired number of duplicated copies; uniformly charging the composite photosensitive member simultaneously with or before exposing ultraviolet rays on the composite photosensitive member to release charges trapped in the composite member.

Abstract: A photosensitive medium for electrophotography comprises an electricaly conductive or a dielectric substrate, a photoconductive layer overlying the substrate, and a transparent dielectric layer overlying the photoconductive layer. The substrate has the entire peripheral portion thereof formed to provide a region uncovered by the photoconductive layer. The transparent dielectric layer is resistant to liquid developer used in electrophotography and may cover the photoconductive layer and the uncovered region of the substrate. Alternatively, the transparent dielectric layer may be secured to the photoconductive layer and the uncovered region of the substrate by the use of an adhesive which is also resistant to the liquid developer.

Abstract: A residual charge erasing step in the electrophotographic process in which a transparent conductor backed photoconductor layer positioned in virtual contact with a conductor backed dielectric layer is exposed to a light image while a first voltage is applied between the conductors to produce on the dielectric layer an electrostatic latent image, the erasing step which is applied after the transfer of the latent image includes positioning the photoconductor and dielectric layers in virtual contact, illuminating the full surface of the photoconductor layer and applying between the conductors a second voltage of a polarity opposite to the first voltage and whose value is((.chi.a+.chi.d)/.chi.a)(312+6.2 .chi.a)wherein .chi.a and .chi.d are respectively the capacitive air gap equivalent thicknesses in microns between the virtually contacting layers and of the dielectric layer per se.

Abstract: A photoconductive material (11) coated on a drum, belt or sheet (22) is formed with a first photoconductive layer (11b) which is insensitive to red light, a second photoconductive layer (11d) which is sensitive to red light and a transparent insulating layer (11c) formed either between the photoconductive layers (11b), (11d) or on top thereof. The outer surface of the material (11) is radiated with white light while applying a first electrostatic charge thereto rendering both photoconductive layers (11b), (11d) photoconductive. Then, the material (11) is radiated with red light rendering only the second photoconductive layer (11d) photoconductive while applying an electrostatic charge of opposite polarity. Then, a third electrostatic charge of the same polarity as the first electrostatic charge is applied in the dark. The result is that electrostatic charges of opposite polarities are formed at the outer surfaces of the first and second photoconductive layers (11b), (11d).

Abstract: In an electrically activatable recording element, such as one comprising an electrically conductive support having thereon, in sequence: (a) a polymeric electrically active conductive (EAC) layer, (b) an electrically activatable recording layer comprising (A) a dye-forming coupler, and (B) an oxidation-reduction combination comprising (i) an organic silver salt oxidizing agent consisting essentially of a silver salt of a 1,2,4-mercaptotriazole derivative, with (ii) a reducing agent which, in its oxidized form, forms a dye with the dye-forming coupler, (c) a photoconductive layer separated from (b) by an air gap of up to 20 microns, and (d) an electrically conductive layer; improvements are provided by means of a polymeric EAC layer (a) consisting essentially of a vinyl addition polymer, such as poly(methyl acrylate-co-vinylidene chloride). The recording element is room light handleable and provides a dye image and silver image by dry development processing.

Abstract: A system and method using an integral sandwich structure including an insulative layer-photoconductive layer-conductive layer. A removable electrode member is positioned above and connected to the insulative layer by a thin liquid layer having a dipole moment greater than zero, a conductivity sufficient to maintain the electric potential of the surface of the insulative layer at the potential of the electrode member, a surface tension equal to or smaller than the critical surface tension of the insulative layer. Upon removal of the electrode member the liquid evaporates in a time period less than the dark dielectric time constant of the photoconductive insulative layer. A d.c. voltage is applied between the conductive layer and the removable electrode during which time a radiation image is applied to the photoconductive layer to cause an electrical charge image to be produced at the outer surface of the insulative layer.

Abstract: The present invention is directed to process and apparatus for overlaying images making use of steps constituting a known electrophotographic process. The electrophotographic process on which the present overlay process depends is of the type in which a three-layered photosensitive member having an insulating covering layer as the top layer of the member is used. The surface of the insulating layer is charged with an electric charge simultaneously with an imagewise irradiation for a first image to be overlaid or during the time of a photo hysteresis resulted from the first image-forming irradiation being still present in the photoconductive layer of the photosensitive member. Then, AC discharging or charging with an electric charge of opposite polarity to that of the above electric charge is effected. Thereafter, an imagewise irradiation for second image is carried out to obtain an electrophotographically overlaid image from the first and second images.

Abstract: A method of producing an electrostatic latent image of an original includes the successive steps of positioning of face-to-face virtual contact a photoconductor layer superimposed on a conductive backing electrode and a dielectric layer superimposed on another conductive backing electrode, applying a direct current voltage of a first polarity between the electrodes of a value to produce gas discharges between the layers to charge the dielectric layer while the photoconductor layer is unexposed to any light, short circuiting the electrodes while exposing the full surface of the photoconductor layer to light until the electric field across the photoconductor layer is substantially zero and applying a voltage between the electrodes at a polarity opposite to the first polarity while exposing the photoconductor layer to the light image of an original.

Abstract: This specification discloses an electrophotographic method and apparatus for forming an electrostatic latent image on a photosensitive medium having a conductive layer, a photoconductive layer and an insulating layer. The method comprises a primary charging step, an image light exposure step, a secondary charging step, a tone regulating step and a whole surface exposure step.

Abstract: An electrophotographic copying method in which there are employed a photosensitive member including a photoconductor layer backed by a conductive electrode and a dielectric layer backed by a conductive electrode comprises the steps of positioning the members with the layers in face-to-face virtual contact and while so positioned applying a voltage of a first polarity between the electrodes under dark conditions to cause gaseous discharges in the gaps between the layers and the charging of the dielectric layer and short circuiting the electrodes while illuminating the photoconductive layer until the electric field therein is zero, and then applying a voltage of reverse polarity between the electrodes while exposing the photoconducted layer to a light image to produce an electrostatic latent image thereof on the dielectric layer which is then separated from the photoconductor layer and the latent image developed and transferred to copy paper.

Abstract: A photoconductive member (11) has a conductive substrate (11a) on which is formed a first photoconductive layer (11b) which is insensitive to red light but sensitive to at least one other color component of white light and a second photoconductive layer (11c) formed on the first layer (11b) which is sensitive to red light. A first electrostatic charge of a first polarity is formed at the interface between the first and second layers (11b), (11c). A second electrostatic charge of a second polarity is formed on the second layer (11c). A light image having black, white and red areas is radiated onto the second layer (11c). The white light causes both layers (11b), (11c) to conduct and dissipate all charge. The red light causes only the second layer (11c) to conduct to form a bipolar electrostatic image.

Abstract: In an electrically activatable recording element, such as one comprising an electrically conductive support having thereon, in sequence: (a) a polymeric electrically active conductive (EAC) layer, (b) an electrically activatable recording layer comprising (A) a dye-forming coupler, and (B) an oxidation-reduction combination comprising (i) an organic silver salt oxidizing agent, such as a silver salt of a 1,2,4-mercaptotriazole derivative, with (ii) a reducing agent which, in its oxidized form, forms a dye with the dye-forming coupler, (c) a photoconductive layer separated from (b) by an air gap of up to 20 microns, and (d) an electrically conductive layer; improvements are provided by means of a polymeric EAC layer (a) comprising a halogen containing polyester, such as poly(2,2'-oxydiethylene:2,2'-dimethyl 1,3-propylene 50:50-2,5-dibromoterephthalate) and poly(ethylene:2,2-dimethyl-1,3-propylene 50:50-2,5-dibromoterephthalate).

Abstract: A process and apparatus for forming an electrostatic image on a photosensitive plate having a conductive base, a photoconductive layer overlying the base and exhibiting p-type or n-type semiconductivity, and an insulative layer overlying the photoconductive layer. The photosensitive plate is characterized in having carrier charge of a polarity corresponding to the conductivity type of the photoconductive layer injectable from the conductive base into the photoconductive layer and bound in the region of the interface between the insulative and photoconductive layers. The conductive base is transparent to activating light and the insulative layer is opaque to the activating light. A first charge of a polarity opposite to the conductivity type of the photoconductive layer is applied onto the insulative layer to inject and bind carrier charge in the region of the interface between the insulative and photoconductive layers.

Abstract: An electrophotographic process for printing a number of copies from a single electrostatic charge latent image once formed on a photosensitive member by projecting an optical image of a document to be copied comprises the following successive steps;(a) a step for effecting a uniform primary electrification with one polarity for the photosensitive member;(b) a step for forming on the uniformly charged photosensitive member, a primary electrostatic latent image corresponding to the image of the document by projecting the document image to the photosensitive member;(c) a step for developing the primary latent image with opaque toner particles having charged in the other polarity to form on the photosensitive member a toned image;(d) a step for placing a transfer member over a surface of the photosensitive member on which surface the toned image has been formed;(e) a step for effecting a secondary electrification with the one polarity from a side of the transfer member and for effecting a secondary exposure also

Abstract: A photosensitive member is exposed to light prior to primary charging so that the surface potential applied by primary charging may always be maintained at a constant level to which the photosensitive member is always charged when it is repetitively used for some time, which may be predetermined by test. Until the surface potential reaches this level, the intensity of light for pre-exposure is gradually decreased and after the surface potential has reached this level, no pre-exposure is applied. But when the surface potential rises after a predeterminable period during which the photosensitive member is not used, the pre-exposure is applied again. All the copies may have the same density.

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: The method of forming a charge-image on a charge-retaining object by applying an electrical image-activating energy and a mechanical image-activating energy in a manner to result in the functional dependence of the charge density of the consequent charge-image to the magnitudes of the image-activating energies and to the length of the activating time period, enabling the charge-image or the subsequent visible image to have a uniform desired level of desired density, controlled multiple levels of density, controlled continuously varying density, or a combination thereof. It also enables the trading off of charge density for a lower image-activating voltage and the trading off of charge-imaging speed for higher charge density. The resulting image is of high fidelity to the original.

Abstract: In the practice of electrophotography using a photosensitive medium having an insulating layer on a photoconductive layer, the surface of the photosensitive medium is uniformly charged with a primary charge. The primary-charged surface of the photosensitive medium is then charged with a charge of the opposite polarity or discharged and simultaneously therewith or therebefore or thereafter, exposed to image light from an original. A grid image is projected upon the surface of the photosensitive medium. For multi-color representation these steps may be repeated in accordance with the number of colors desired.

Abstract: A heat-developable photosensitive member for forming an electric printing master comprises a support, an organic silver salt layer containing an organic silver salt, a halide and a toning agent dispersed in a binder, and a surface protecting layer or a particular surface, and a reducing agent is contained in at least one layer of the organic silver salt layer and a layer adjacent to the organic layer.

Abstract: Process for eliminating the need for a separate cleaning station in a one-cycle electrophotographic document copier machine of the transfer type. A backcharge corona generator is added to provide an overcharge/backcharge process to obtain the desired level of charge on the photoconductive system prior to exposure of the photoreceptor to the subject. In that manner, residual toner remaining on the photoconductor after production of the previous copy is cleaned simultaneously with the development of the succeeding copy.

Abstract: A method and apparatus of electrophotography wherein before exposure of a photosensitive element to a light image the element is subjected to a substantially uniform light irradiation to release a part of the charge carriers trapped in a photoconductive layer of the element, thereby controlling the potential of a latent image to be formed on the element within a range fit for the development of the latent image.

Abstract: A first method of revealing a fingerprint involves the charging of the surface bearing the fingerprint to a high electric potential and applying finely divided carbon to the charged surface to form a pattern thereon corresponding to the fingerprint.The finely divided carbon may be dusted or sprayed on or may be in suspension in a dielectric liquid into which the charged surface is introduced.In another method the surface is charged while submerged in the dielectric liquid, under the action of an electric field in the dielectric.In another method an electrically charged sheet is brought into contact with a surface bearing a fingerprint and after being removed, the charged sheet has applied to its surface finely divided carbon which adheres thereto depending on the charge pattern remaining thereon after contact with the fingerprint.The pattern of finely divided carbon can be fixed in position by applying thereover a transparent protective layer.

Abstract: There is described an electrophotographic imaging method which utilizes an imaging member comprising a substrate, a layer of a charge carrier injecting material, a layer of a charge carrier transport material, a layer of a photoconductive charge carrier generating material and an electrically insulating overcoating layer. In operation, the member is charged a first time with electrostatic charges of a first polarity, charged a second time with electrostatic charges of a polarity opposite to said first polarity in order to substantially neutralize the charges residing on the electrically insulating surface of the member and exposed to an imagewise pattern of activating electromagnetic radiation whereby an electrostatic latent image is formed. The electrostatic latent image may be developed to form a visible image which may be transferred to a receiver member. Subsequently the imaging member may be reused to form additional reproductions after erasure and cleaning steps are carried out.

Abstract: An electrophotographic photosensitive member is prepared by dispersing photoconductive particle in a binder resin in a solvent and forming a photoconductive film by removing the solvent. Transition temperature of the binder resin and the preparation temperature are to be selected in such a way that the balance between these temperatures is within a certain range.

Abstract: A photoconductive drum formed with two photoconductive layers of different spectral sensitivty is charged a first time in the dark or while rendering one of the layers conductive and a second time with an opposite polarity in the dark to form a stratified electrostatic charge pattern. Exposure to a light image of an original document causes the layers to conduct according to color. Toner particles of two colors such as red and black adhere to respective areas of the resulting electrostatic image which have opposite polarities. Transfer of the resulting toner image to a copy sheet produces a finished copy in two colors.

Abstract: Electrophotographic medium which comprises a multilayer structure of materials for imaging radiant energy patterns at high speed and with high sensitivity of a degree capable of meeting and exceeding the sensitivity of silver halide film, with greater resolution than that of silver halide film of the high speed type.A method of using electrophotographic film to achieve high sensitivities and speeds.The medium comprises a transparent substrate, ohmic layer and coating of photoconductive material, all of which form a modulating structure for the radiant energy that is adapted to be projected through the substrate; a dielectric layer intimately bonded to the surface of the photoconductive coating and a conductive electrode in intimate contact with the dielectric layer.The use of the electrophotographic medium does not require initial charging; hence no means for effecting this are required.

Abstract: A method for producing visible images in certain charge sensitive, dry processable recording elements. Image recording is accomplished by flowing, in a resistive recording element containing a reducible metal compound, an imagewise pattern of electrical current of sufficient magnitude to produce therein a storable latent image. The metal compound in the latent image areas is subsequently reduced by a dry development technique to produce a visible image.

Abstract: Process and apparatus for electrophotography are disclosed in which a photosensitive medium basically composed of an electrically conductive layer, a photoconductive layer and an insulating layer is used. The process comprises the steps of applying onto the surface of the photosensitive medium a uniform corona discharge with a predetermined polarity, exposing it to an original light image, applying to it a secondary corona discharge with a component of the opposite polarity to that of the primary uniform corona discharge simultaneously with or immediately after the image-wise exposure, uniformly exposing it to near infrared light almost simultaneously with the secondary corona discharge and subjecting it to a whole surface exposure with white light so as to form an electrostatic latent image corresponding to the original light image.

Abstract: The present invention provides an electrophotographic process for producing copied images by repeating the respective steps of at least charging a layered photoconductor having a carrier generation layer and a carrier transport layer, in that order, on a light-transmissible electroconductive support, effecting image-wise exposure by way of one side of said layered photoconductor and developing subsequent thereto, in which the occurrence of stains on the ground of the image is minimized by uniformly applying light in an amount of exposure sufficient for substantially eliminating the residual potential resulting from said image-wise exposure by way of the other side of the layered photoconductor either simultaneously with the image-wise exposure or in the course of from the image-wise exposure to the development.

Abstract: A subtractive color electrophotographic process is disclosed for producing a multicolor print from a single exposure of a color original. The process utilizes a novel multilayer recording element containing an electrically conducting layer, an insulating layer and two or more photoconductive layers, each spectrally sensitized to a different portion of the optical spectrum. In carrying out the process, the recording element is first uniformly charged and exposed to a color original and then developed by a multistep procedure. Each step of the development procedure comprises flood exposing the recording element to radiation to which at least one of the photoconductive layers is responsive while applying toner particles having a different subtractive color characteristic and an appropriate electrical bias.