Abstract: Non-contact corona charging of a small radius moving surface to a desired surface voltage with a single corona charging system with a first corona generator applying a first charge through a screen grid having a first bias voltage to initially charge the surface to more than half of the desired voltage, and then a second corona generator applies the remainder of the desired surface charge through a separate screen grid having a second bias voltage. The two corona generators may be spaced pin arrays angled relative to one another and substantially perpendicular to their adjacent moving surface areas. The two screen grids may be electrically planar and angled relative to one another, substantially parallel to their adjacent moving surface areas.

Abstract: In a xerographic printing apparatus, a scorotron places a uniform charge on a photoreceptor for forming electrostatic latent images. Two conductive pin arrays are disposed in a housing defined by sidewalls and a grid adjacent the photoreceptor. For each array, the distance to the adjacent sidewall is 1.0 to 1.5 the distance to the grid.

Abstract: A method and apparatus for heating a charging unit to an appropriate temperature in a uniform manner is provided. In accordance with one example embodiment of the present invention, a heater for use in a charger includes a base. First and second contacts are disposed on the base. A heating element couples the first contact and the second contact. The heating element has an energy density that increases approximately exponentially from a first energy density at locations distal from the first and second heat sink locations to a relatively higher second energy density at locations proximal to the first and second heat sink locations. The heater, according to further embodiments of the present invention, is disposed on an opposite side of the substrate layer from the AC electrode layer, and underneath the charger.

Abstract: A rotatable charging apparatus includes a length extending between a first end and a second end, with the rotatable charging apparatus centered about an axis parallel to the length. The rotatable charging apparatus outer periphery forms N apparatus positions. One charging device is fixed to each of N−1 apparatus positions. The remaining (Nth) apparatus position is devoid of a charging device, thus forming an “empty” charging device position. A host printing machine selectively causes the rotatable charging apparatus to rotate about its axis thereby selectively position any of its N−1 charging devices to face a proximately-located photosensitive element. When a problem exists with the current charging device, or when the total number of operating hours of the current charging device exceeds a fixed threshold, the printing machine causes the rotatable charging apparatus to rotate from its current charging device to position a new charging device facing the photosensitive element.

Abstract: In an electrostatographic imaging apparatus employing at least one charging device, scorotron which consists of one or more fine wires supported on insulated blocks spaced between the photoconductive surface and a conductive or insulative surface parallel to it. A screen or grid is interposed between the corona wires and the photoconductive surface and the grid is maintained at a potential roughly equal to the potential desired on the photoconductive surface. The scorotrons geometry, the individual wires are from 1/2 to 11/2 inches apart and are spaced from the grid by about 3/4 of an inch. Field enhancement electrode(s) are placed on the screen and are biased at the same potential as the screen. The field enhancement electrode(s) enhance electrical performance.

Abstract: A color electrophotographic printer that prepares a composite toner image for transfer by exposing an image area containing the composite toner image to an erase lamp and then running the composite toner image by an AC scorotron.

Abstract: In an electrostatographic imaging apparatus employing at least one charging device, in an electrostatic charge process involving the creation of latent electrostatic images, A method for controlling corona current generation by said at least one charging device is disclosed. The method comprising the steps of: generating an AC current and an AC voltage with a power supply; measuring the steady state negative half cycle of current, filtering capacitive current spikes from said negative half cycle current measurement and generating a corona current feedback signal in response to said filtering step; and dynamically adjusting the AC voltage in response to the corona current feedback signal so that the steady state negative half cycle of current measured in said measuring step remains constant.

Abstract: A conformable bias transfer member for use in an electrostatographic printing apparatus comprising a conductive core having a layer of compressible material coated thereon to form a generally cylindrical roll member. The compressible material includes a conductive filler dispersed throughout the interstices thereof for providing conductivity control which is significantly insensitive to changes in temperature as well as relative humidity.

Abstract: A color REaD IOI system in which a light source illuminates the photoreceptor so as to erase that photoreceptor after the development of a first toner followed by a high slope AC corona system which recharges both the photoreceptor and first developed toner before exposure and development of the next color image.

Abstract: Printing machines and systems which incorporate recharging stations comprised of two corona generating devices which act together to recharge a previously developed photoreceptor to a predetermined potential. The first corona generating device recharges the photoreceptor's surface to a greater absolute potential than a predetermined potential which the surface is to have after being recharged. The second corona generating device reduces the photoreceptor's surface to the potential that it is to have. The second corona generating device is comprised of a plurality of spaced apart coronodes which each can impress charges on the photoreceptor's surface. The second corona generating device receives electrical inputs and applies DC potentials to the coronodes such that adjacent coronodes have opposite polarities.

Abstract: In a multi-color imaging apparatus utilizing a recharge step between two image creation steps for recharging a charge retentive surface to a predetermined potential pursuant to forming the second of the two images, a first corona generating device recharges the charge retentive surface to a higher absolute potential than a predetermined potential, and then a second corona generating device recharges the charge retentive surface to the predetermined potential. An electrical charge associated with the first image is substantially neutralized after being recharged by the first and second corona generating device.

Abstract: In a multi-color imaging apparatus utilizing a recharge step between two image creation steps for conditioning a charge retentive surface pursuant to forming the second of the two images, a voltage sensitive corona generating device having a high characteristic slope described in a graph of the current delivered to a charge receiving surface (I) vs. grid minus charge receiving surface voltage (V) is used to both reduce the residual toner voltage across the previously toned image, and to charge the toned and untoned areas of the charge retentive surface to a substantially uniform level so that developability conditions for the subsequent image are improved.

Abstract: A method and apparatus for extending the electrical life of a bias transfer roll is disclosed. The apparatus includes a biasing member comprising a bias roll member or other charging device for reversing current flow through the bias transfer roll. The apparatus of the present invention permits reversal of current flow through a bias transfer roll to replenish ions depleted therefrom during the transfer process.

Abstract: A corona generating device of the type in which a control grid adjacent a corona generating electrode regulates the charge deposited onto an imaging surface. The control grid defines elongated apertures located in alignment with the electrode, extending along a portion thereof wherein the control grid is adapted to selectively control the charge deposited on the imaging surface area for preventing development of the edge regions thereof.

Abstract: Pre pretransfer treatment for multiple toner toner images increases the operating latitude for pretransfer/transfer. In one embodiment of the invention, a pre pretransfer corona device is used to drive the tribos of two multiple toner images toward each other prior to pretransfer. A single constant current corona discharge device is used in this embodiment. Subsequent pretransfer treatment serves to reduce the delta tribo between the two images thereby providing an operating latitude of 3 micro coul/g.

Abstract: An electrophotographic device includes a flexible belt-type charge retentive member, bearing a developed latent image and brings a sheet of paper or other transfer member into intimate contact with the charge retentive surface at a transfer station for electrostatic transfer of toner from the charge retentive surface to the sheet. At the transfer station, a resonator suitable for generating vibratory energy is arranged in line contact with the back side of the charge retentive, to uniformly apply vibratory energy to the charge retentive member surface at a position opposite the transfer coronode or peak transfer field, or slightly upstream therefrom. Toner is released from the electrostatic and mechanical forces adjering it to the charge retentive surface at the line contact position.

Abstract: A discharge apparatus for use in applying a uniform electrostatic charge to a charge retentive surface. Specifically, the apparatus has an array of pin or needle electrodes for negatively charging the surface. The electrodes are coupled to a pulsed d.c. power supply designed to cause them to operate at sufficiently high current densities to insure stable output therefrom yet due to the pulsing stability is achieved at relatively low current levels. Thus, operation at higher current densities for shorter intervals, for example, at half duty achieves output stability at lower current levels.