Abstract: Electrically photosensitive materials comprising electrically photosensitive colorant particles dispersed in a liquefiable, electrically insulating carrier containing a binder polymer and electropolymerizable bisphenol-acrylate monomers or mixtures of such monomers are disclosed. The disclosed materials are employed in photoelectrophoretic processes wherein the colorant particles are caused to migrate by the action of light and an electric field, while the material is electrohardened by the electric field.

Abstract: Method and apparatus for xerographic printing wherein a magnetic brush unit is used to both apply toner to an image on a photoconductive surface and clean the surface in the same cycle. A reverse imaging process is used in combination with an electronically controlled exposure station. A cleaner or separate cleaning station is not required in the inventive method and apparatus described herein.

Abstract: In a xerographic reproduction machine there is provided apparatus for partially neutralizing charge on the backside of a copy sheet electrostatically adhered to a photoconductive surface. Included in the apparatus is a conductive wire having a relatively thick insulative outer coating which is sufficiently thick that with an a.c. voltage applied to the conductive wire there is substantially no net d.c. current flow from the wire in the absence of an external electrostatic field. Such a construction of wire and outer coating is known as a dicorotron electrode. A net positive current flows from the wire to the back of the paper when an external electrostatic field is established between the conductive shield and the copy sheet by moving said copy sheet with a positive voltage on its backside past the conductive wire.

Abstract: Apparatus is described for providing controlled corona charging of an electrophotographic member that moves past a corona charging electrode. A corona sensor probe near the charging electrode receives a sample of the corona current flow from the electrode that is proportional to the current flow as it may be modified by extraneous influence, including air pressure, humidity, and corona electrode potential. The probe produces a signal that is adapted to vary the movement rate of the member past the charging electrode, being faster for a sensed increase of corona current and slower for a sensed decrease of corona current. The effective result is an electric charge on the electrophotographic member surface that is uniformly about constant, independent of the variations wrought by most external influences.

Abstract: A transfer unit includes a pair of guide and field stabilizer members disposed adjacent to a transfer member and along a conveying path for a transfer sheet. A voltage is applied to the stabilizer members which is of the same polarity as a bias voltage applied to the transfer member. It is assured that transfer sheet reliably contacts the pair of field stabilizer members as it passes therebetween.

Abstract: In an electronic copier provided with a light-sensitive medium, a charging station, an exposure station, a developing station, a transfer station and a fixing unit, the charging station includes a plurality of contact charging elements in contact with the light-sensitive medium and a voltage supply means for applying voltages to the contact charging elements. A voltage continuously rising in a predetermined period of time is supplied from the voltage supply means to the contact charging elements with the rotation of light-sensitive medium, and the light-sensitive medium is thus uniformly charged.

Abstract: In electrographic printing Paschen breakdown must be exceeded for writing to occur, or the Paschen breakdown level can be used as a measure of the suitability of record media for use in such printing. The onset of Paschen breakdown is determined by the appearance or disappearance of second harmonic current flow across a test gap. The DC output of an integrator rises until the onset of Paschen breakdown occurs caused by the combination of the D C output and a sinusoidal voltage from an oscillator.

Abstract: A process of imposing an electrical charge on an electrically insulating surface of a moving web wherein a brush electrode contacts the surface. The brush is made up of extremely soft and flexible fiber filaments comprising carbon mounted on a metallic brace which also serves as an electrical contact to supply the brush with d.c. potential whereby the electrically insulating surface is charged to nearly the potential applied to the brush.In order to improve charge uniformity the brush is oscillated in a direction transverse to the direction of web movement.

Abstract: The invention relates to a printing device for electrophoretic recording by means of electrodes which are relatively movable with respect to an image carrier. Between the image carrier and electrodes, a liquid developer fluid is present in which the electrodes are immersed. Recording takes place under the influence of a control voltage (U.sub.ST) causing adherence of electrophoretic pigment to the image carrier. In order to enable point-like (matrix-like) recording, the surface of the image carrier is electrically conductive and the developer fluid at the area of the electrodes is continuously exchanged to maintain the electrophoretic pigment supply.

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: 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: 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: 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: A method of making a display screen for a color television display tube in which a photoconductive layer on the window portion of the tube is provided with a uniform charge which may be either positive or negative. A charge pattern is then formed on that layer by scanning it with an electron beam passing through an apertured color selection electrode. The energy of the beam is such that the average depth of penetration of the electrons is greater than the thickness of the photoconductive layer so that the charge disappears at the regions struck by the beam. The remaining charge pattern is developed with a suspension of charged phosphor particles. By repeating this process, patterns of red, green and blue luminescent phosphor particles can be successively provided to form the display screen. It is also possible to scan the layer simultaneously or successively by three electron beams and to develop the resultant charge pattern with a light-absorbing pigment.

Abstract: A system for impressing images on electrophotographic film provides for the charging of each film frame rapidly to a peak voltage determined by the prevailing light conditions of the image to be produced or recorded. After charging the film frame is immediately exposed to an image. In the preferred method, the time of exposure is predetermined and fixed. Next, toner is applied immediately to the charged frame in the presence of a bias field which propels the toner particles toward the film. Thereafter excess toner is removed or leaves the film frame and the remaining toner is fused to the surface of the film to form a permanent visible image on the film frame. An alternate form transfers the toned image to an acceptor member where it is fixed.The various processing steps are all carried out at points on the dark decay portion of the characteristic discharge curve for the particular film so that the resultant image has high resolution and optimum contrast.

Abstract: My invention comprises charging a photoconductive surface in the dark and exposing it to a light and shade image of the original to produce a latent electrostatic image. The latent electrostatic image is then developed by any method known to the art employing a liquid developing fluid, and the apparent resolution or sharpness of the developed image is increased by exposing the developed image, while on the photoconductor, to the action of blanket light. The sharpened image may then be transferred to a carrier sheet by any method known to the art.The apparatus of my invention comprises a conventional electrophotographic reproduction apparatus in which a means is provided for subjecting a liquid-developed image, while on the photoconductor, to the action of blanket light. This means is positioned to act before the liquid-developed image is transferred to a carrier sheet after it has been developed, if a transfer is to take place.

Abstract: A method and apparatus for operating an electrophoretic indicating element driven by a drive signal, wherein the drive signal is modulated by an alternating voltage signal superimposed on the drive signal and having a frequency sufficiently high to prevent observation thereof. The modulating signal can have either a sinusoidal, triangular, or rectangular wave shape, or can be a succession of individual wave trains wherein the duration of each wave train is selected in accordance with the composition of the electrophoretic switching element.

Abstract: A photoelectrophoretic image-forming process utilizing a pair of electrodes with at least one of the electrodes being transparent and at least one of the electrodes having an electrically insulating surface, which comprises the following steps of:(1) forming a liquid film which comprises a suspension of light-sensitive particles in an electrically insulating carrier liquid on the electrically insulating surface of one of the electrodes (hereinafter called the first electrode),(2) in a first showering, showering the liquid film with corona ions of either a positive polarity or a negative polarity to form an electrically charged liquid film,(3) in a further showering, showering the electrically charged liquid film with corona ions containing corona ions of a polarity opposite to the polarity of the corona ions showered in the first showering,(4) positioning the other electrode (the second electrode) facing the first electrode with the liquid film therebetween,(5) image-wise exposing the liquid film through the

Abstract: An electrophotographic process including the step of pre-exposing the surface of a photosensitive member to light at an exposure of no less than 10.sup.3 lx-sec, followed by the uniform charging of the same. The photosensitivity of this type photosensitive member in an image exposing step varies according to its prior history. This process further includes the step of exposing an image by projecting an optical image, corresponding to an original image, onto the photosensitive member thus charged for forming a clear electrostatic latent image, corresponding to the original image, on the surface of the photosensitive member.