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: In an electrostatic photographic process comprising subjecting an electrostatic photographic photosensitive plate to the combination of negative charging, positive charging and imagewise exposure to form an electrostatic latent image of a positive polarity, said electrostatic photographic photosensitive plate having such charging characteristics that a photosensitive layer can be positively charged by sequential negative corona charging and positive corona charging and positive charging is rendered substantially impossible by irradiation with light, and then subjecting the so treated photosensitive plate to positive charging a predetermined number of times, whereby an electrostatic latent image is formed the predetermined number of times by imagewise exposure conducted once, if a zinc oxide-resin dispersion is used for the photosensitive layer of the photosensitive plate and predetermined amounts of a triphenylmethane basic dye and a silicone oil are incorporated in the photosensitive layer, the time required

Abstract: In the process of forming an electrostatic latent image on a photosensitive medium through at least two kinds of charging steps, the electrostatic latent image is stabilized by the steps of measuring the dark region potential V.sub.D and the light region potential V.sub.L on the photosensitive medium, comparing the measurement values with a predetermined referential dark region potential V.sub.DR and a predetermined referential light region potential V.sub.LR, and when the differences between the V.sub.D, V.sub.L and the V.sub.DR, V.sub.LR are not within predetermined ranges, setting the amount of control by control functions f(x,y) and g(x,y), in which the differences x=V.sub.DR -V.sub.D and y=V.sub.LR -V.sub.L are variables, and varying the potential of the latent image on the photosensitive medium in accordance with the set amount of control.

Abstract: A method and an apparatus for charging a dielectric layer electrostatically to a predetermined potential. An AC electrode is arranged at a distance from the dielectric layer and connected to one output of an AC voltage generator. The AC voltage generator has the other output connected to an output of a DC voltage generator. Between the AC electrode and the dielectric layer there is a DC electrode which is connected to the other output of the AC voltage generator. The dielectric layer rests on a counter-electrode which is connected to the other output of the DC voltage generator and is at ground potential. Each of the electrodes can comprise one or a plurality of mutually insulated single electrodes.

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: 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: In an electrophotographic image forming process, a method and apparatus for providing an electric toning bias wherein the instantaneous electric potential value of the bias is changed with time in proportion to the natural decay of the resident electric charge inherent in the photoconductor comprising the essence of the electrophotographic medium.

Abstract: This invention is generally directed to inorganic overcoated photoresponsive devices comprised of a substrate, a layer of hole injecting material capable of injecting holes into a layer on its surface, this layer being comprised of trigonal selenium, a hole transport layer in operative contact with the hole injecting layer, this layer being comprised of a halogen doped selenium arsenic alloy, wherein the percentage by weight of selenium present is from about 99.5 percent to about 99.9 percent, the percentage by weight of arsenic present is from about 0.1 percent to about 0.5 percent, and the halogen is present in an amount of from about 10 parts per million, to about 200 parts per million; a charge generating layer overcoated on the hole transport layer, comprised of an inorganic photoconductive material; and a layer of insulating organic resin overlaying the charge generating layer.

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: 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: For improving the electrical contact between an insulating image carrier and a conductive support during development of an electrostatic charge image in electrographic recording processes a gas permeable support is used through which gas ions are brought to the back of the carrier while development takes place on the image side.

Abstract: An electrophotographic photosensitive member comprises a base, a photoconductive layer and an insulating layer, and the photoconductive layer contains an intermediate layer formed at the base side of the photoconductive layer. The intermediate layer facilitates injection of electric charge.

Abstract: An electrographic apparatus for selectively producing, on a latent image holding member including a first electrostatic latent image produced thereon by a first charge, a second electrostatic latent image composed of a second charge which is negative with respect to the first electrostatic latent image and which is opposite in polarity to the first electrostatic latent image. The apparatus includes a device for selectively applying to the latent image holding member a second charge which is opposite in polarity to the first charge.

Abstract: An improved process for transferring a magnetizable developing powder from an insulating substitute, such as an electrostatic duplication master or photoconductive element to a receiving material, such as paper, in electrostatic image development enables the transfer of powder having a specific resistance greater than 10.sup.13 Ohm.cm. without the need for specially treated paper. The powder is applied imagewise, corresponding to a charge image, on an insulating substrate, the substrate with the powder image brought in contact with the receiving material to which the powder is to be transferred, two separate charges are applied to the free side of the receiving material during the period of contact with the substrate, the first of such charges, a pre-transfer charge, having a polarity opposite to that of the charge image and the second of such charges, a transfer charge, being greater than the first and having the same polarity as that of the charge image, and the powder transferred.