Abstract: A corona discharge device including a corona discharge electrode in contact or closely spaced from a conductive shield electrode, the discharge electrode comprising a conductive wire coated with a relatively thick dielectric material so as to prevent the flow of conduction current therethrough. When the electrode is spaced from the shield, it is supported along its length on a dielectric surface and when it is in contact with the shield, the shield itself may provide the lengthwise support for the wire, or the support may alternatively be provided by a dielectric substrate on which the shield is carried. The delivery of charge to the photoconductive surface is accomplished by means of electric field separation of charges produced by the discharge electrode. These charges are produced by an alternating voltage applied to the discharge electrode. The flow of charge to the surface to be charged is regulated by means of a d.c. voltage bias applied to the shield electrode.

Abstract: A corona charging arrangement comprising a plurality of charging devices formed onto a unit. Each of the devices is rotatable to an operative position in which it is coupled to suitable terminals for applying energizing potential thereto, the operative position being selected so that charge therefrom is deposited on the imaging surface.

Abstract: Disclosed is a process and, to implement the process, an electrostatic charging apparatus comprising means for producing a corona discharge; a counter-electrode positioned below the discharge means adapted for supporting a recording material to be charged; means for supporting the counter-electrode, including a pair of opposed vertical side walls defining a guide channel of substantially rectangular cross-section along which the recording material can pass; and a pair of elongated strip-like members of electrically insulative material extending within the channel at least from the side walls laterally along the opposed marginal regions of the counter-electrode and longitudinally along the whole length of the counter-electrode.

Abstract: Disclosed is an improved apparatus for electrostatically charging an electrophotographic film held stationary with respect to a corona source. The improvement consists of a capacitor interconnecting the film to ground for limiting the amount of charge deposited upon the film during charging.

Abstract: Method and apparatus for enhancing charge retention of a photosensitive layer wherein an ion wind is created and applied to the photosensitive material prior to its reuse. The apparatus preferably comprises a corona charging unit having an opening and directing means adjacent the opening for directing the flow of ions created during corona charging into an uncharged portion of the photosensitive layer.

Abstract: Disclosed is an improved apparatus for applying a uniform electrostatic charge to a predetermined portion of an electrophotographic film. The apparatus includes a corona generation source and a mask framing the predetermined portion of the film. The improvement consists of an electrically conductive surface surrounding the frame opening of the mask and spaced from the surface of the film and a capacitor interconnecting the electrically conductive surface with ground. The electrically conductive surface on the mask develops a voltage close to that of the surface potential of the film during corona charging so that very little charge field discontinuity exists between the mask and the film, thereby permitting uniform electrostatic charging of the film up to the edges of the portion being charged.

Abstract: An electrostatographic machine is provided with an A.C. corona discharge device having a D.C. bias impressed thereon which is applied to the photoconductive surface prior to the passage thereof through an image transfer zone, the A.C. charge being such as to aid both transfer efficiency and background suppression while the D.C. bias further enhances the efficiency of background removal.

Abstract: A corona generating device including an elongated corona electrode in the form of a thin wire to which a corona generating potential is applied. The wire is partially surrounded by a conductive corona shield which may be grounded. Intermediate the wire and shield and spaced apart from each are various configurations of ozone reducing members which partially surround the wire. These members are coated with a catalytic material which reacts with the ozone in an area as close as possible to the area in which it is generated, preferably in the corona glow region, and thus have been found to be more effective in reducing the ozone.

Abstract: An arrangement for compensating for changes in the output of a corotron due to environmental changes. The arrangement includes a control corona device and a controlled corona device, the controlled corona device located in a xerographic reproduction machine in a position to deposit charge on an imaging surface and the control device located remote from said imaging surface and inoperative to deposit charge thereon, but exposed to some environmental conditions of pressure and temperature, etc. The output of the control corotron is used to generate a control signal which is fed back to control the controlled corotron which may be one or all of the corotrons used in the xerographic process.

Abstract: A corona charging apparatus including a corona electrode and a surface to be charged, and a corona discharge control line, which may be insulative or conductive, and grounded or impressed with a voltage located adjacent to the corona electrode. The relative geometry of electrode and control line is variable, both angularly and spatially to control the charge pattern deposited on the surface.

Abstract: In a photoconductive image processing system, consistent copy quality is possible if the charge necessary for the transfer of a toner image is produced by a source of substantially constant current. Changes in transfer material or humidity will not affect the current and thus the charge delivered. As a result, readjustment of the charge source is obviated.

Abstract: A method for charging an electrophotographic member which includes rotating a number of elongate corona electrodes, which are positioned parallel to and a predetermined distance from a central axis, about the central axis while simultaneously applying a corona voltage to each of the electrodes whereby each develops a corona, so that a substantially uniform corona charge is applied to the entire electrophotographic member. An additional step, performed simultaneously with production of the corona and rotation of the electrodes, can be the movement of one of the rotating electrodes and the electrophotographic member relative to the other with a predetermined distance being maintained between the member and central axis. Apparatus employed to perform this method also is disclosed.

Abstract: A corona generating apparatus in which the coronode wires and grid wires thereof are cleaned to remove particles therefrom. A wiper is positioned within the shield contacting the coronode wires and grid wires. The wiper moves along the coronode wires and grid wires to remove contaminating particles therefrom.

Abstract: Disclosed are apparatus and method for applying a uniform electrostatic charge to an electrophotographic film through use of a corona discharge electrode positioned close to the film, a high voltage AC potential source connected to the electrode and having a potential greater than the corona threshold potential of the electrode, and a high voltage DC potential source connected to the electrode in series with the AC potential source for biasing the AC potential source, the DC potential source voltage being less than the difference between the voltages of the AC potential source and the corona threshold potential of the electrode. The film is subject to a series of first corona discharges of the desired polarity, of which each discharge is alternated with one of a series of second corona discharges having the opposite polarity and of lesser intensity than the first corona discharges.

Abstract: A technique for charging a dielectric surface by corona discharge is described in which the voltage applied to a stationary corona wire is steadily increased over an initial time period to cause the gradual increase in voltage level on the dielectric surface over the same time period. The voltage on the stationary dielectric surface increases with the wire voltage. The potential difference between wire and plate is kept below the sparking voltage, but above the corona current threshold voltage.After the initial phase, the dielectric surface is moved relative to the corona wire (e.g. a rotating xerographic drum). The corona wire can now be held at its high voltage without sparking between the wire and the dielectric surface.

Abstract: A charging device for an electrophotographic apparatus wherein at least a first portion of a control plate is movable relative to a corona generating device. A support member having a photoconductive insulating layer is maintained in spaced relationship relative to the corona generating device. A suitable mechanism is operably associated with the control plate for varying the position of at least the first portion of the control plate relative to the corona generating device to thereby adjust the strength of the corona discharge from the portion of the corona generating device generally adjacent the first portion of the control plate.

Abstract: Apparatus for automatically regulating the amount of charge applied to an insulating surface. In a first embodiment an electrometer measures the electrostatic potential, or charge, on the insulating surface and generates an output voltage proportional thereto. The output voltage is continuously monitored and compared in a comparison means with a reference potential, the difference therebetween corresponding to an error signal. The error signal is periodically sampled and applied to an analog incremental integrator, the output thereof being coupled to a corona generator power supply, the power supply in turn being coupled to a corona electrode. The voltage applied by the power supply to the corona electrode is of a magnitude to cause the wire to apply sufficient charge to the insulating surface to reduce the error signal to substantially zero. In a second embodiment the output of the comparison means is sampled and delayed and then coupled to the corona generator power supply.

Abstract: An original electrostatic charge pattern on an electrically insulating image-bearing surface is reproduced, on an electrically insulating film, in an intensified form by the steps of:A. placing one surface of the film in contact with the original charge pattern on the image-bearing surface,B. wiping, with a grounded wetted sponge, the other surface of the film to induce thereon a monopolar charge pattern of opposite polarity to that of the original charge pattern,C. separating the film from the image-bearing surface and wiping, with a grounded wetted sponge, said one surface, whereby to induce a bipolar charge pattern on the film,D. disposing said one surface of the film in contact with the image-bearing surface so that the electrostatic charge patterns of the same polarities contact each other and are in register with each other,E. wiping, with a grounded wetted sponge, said other surface of the film to induce thereon a monopolar electrostatic charge pattern superimposed on the bipolar charge pattern, andF.