With Specific Power Supply Patents (Class 361/235)
  • Patent number: 4926285
    Abstract: Current injection electrostatic discharge equipment that includes a discharge capacitor connected to the input terminal of a sulfur-hexafluoride filled relay for selectively applying a current discharge to a test tip, the wave shape of the current discharge being highly repeatable.
    Type: Grant
    Filed: June 29, 1988
    Date of Patent: May 15, 1990
    Assignee: KeyTek Instrument Corp.
    Inventors: Nicholas Reinhardt, Geoffrey M. Weil
  • Patent number: 4918568
    Abstract: Air quality control systems for rooms or other enclosed spaces relying on generators which supply charges to particles present in the air thereby purifying or otherwise controlling the condition of the air. A source of high voltage is connected to radiating surfaces of various configurations carrying electrostatic charges. A fan or other air circulating device including natural air movement insures adequate contact of the air with the charges generated to thereby achieve the desired quality control. Operating mechanisms provided in the system include voltage varying circuitry to permit adjustment of the generating intensity. A sensor is provided to detect variations in conditions thereby permitting automatic voltage variations. A remote control station is comtemplated where independent environments may be involved and where separate control of these environments is desired.
    Type: Grant
    Filed: April 22, 1988
    Date of Patent: April 17, 1990
    Assignee: Air Physics Corporation
    Inventors: Judson F. Stone, Harold O. Schwartz
  • Patent number: 4916571
    Abstract: A spray-coating device for spraying liquid or powdered coating material on articles includes a transformer for stepping up an alternating voltage and a voltage multiplier circuit for converting the output of the transformer to a high DC output for driving a charging electrode in the spray-coating device. The alternating voltage for the transformer is obtained from a controllable source of alternating voltage which produces a sinusoidal voltage whose frequency is constantly adjusted such that the voltage and current flowing through the transformer are in phase with one another. This assures that the transformer is operated at its resonant frequency.
    Type: Grant
    Filed: July 20, 1988
    Date of Patent: April 10, 1990
    Assignee: Ransburg-Gema AG
    Inventor: Hans Staheli
  • Patent number: 4901194
    Abstract: Ion content of the air in a clean room or the like is controlled by generating positive and negative ions during alternating time periods using positive and negative high voltage generators connected to ionizing electrodes. Ion generation periods are followed by off intervals during which the ions disperse away from the electrodes before ions of opposite polarity are generated. In one aspect of the invention, each period of actuation of a high voltage generator of one polarity is followed by a momentary actuation of the high voltage generator of opposite polarity. This produces ions that are attracted to the electrode of the one polarity and then neutralize residual charge on the capacitors of the generator of the one polarity thereby assuring an abrupt termination of ion generation which can otherwise extend into the subsequent off period.
    Type: Grant
    Filed: December 29, 1988
    Date of Patent: February 13, 1990
    Assignee: Ion Systems, Inc.
    Inventors: Arnold J. Steinman, Michael G. Yost
  • Patent number: 4890190
    Abstract: A method of selecting the optimum value for a series limiting resistor in conjunction with a high-voltage power supply of the Cockcroft-Walton type, wherein the high-voltage circuit is used to deliver an electrostatic field in a volatile atmosphere of the type associated with paint spraying systems.
    Type: Grant
    Filed: December 9, 1988
    Date of Patent: December 26, 1989
    Assignee: Graco Inc.
    Inventor: Dale R. Hemming
  • Patent number: 4878149
    Abstract: A device for generating ions in gas streams is proposed, which has an electrode arrangement exposed to the gas streams and a pulsed high voltage supply, which supplies an alternating sequence of negative and positive pulses with step edges. The electrode arrangement comprises at least one point discharge electrode and at least one counterelectrode associated with one another in fixed, clearly defined manner. The time behaviour of the high voltage signal is fixed in such a way that the duration of the particular pulse corresponds to the transit time of the ions between the electrodes and the spacing of the pulses is adapted to the speed of the gas streams.
    Type: Grant
    Filed: December 3, 1987
    Date of Patent: October 31, 1989
    Assignee: Sorbios Verfahrenstechnische Gerate und GmbH
    Inventors: Hans-Henrich Stiehl, Thomas Sebald
  • Patent number: 4868907
    Abstract: An electrophotographic system including a corona charging device for applying a charge to a surface and having a coronode driven to a corona producing condition; a conductive grid interposed between the surface to be charged and the coronode; the conductive grid having a self-biasing arrangement to control the voltage thereon produced by corona current from the coronode, the self-biasing arrangement including a current sinking device between the conductive grid and a common; and a power supplying takeoff, electrically connected between the conductive grid and the current sinking device, and having a voltage thereat controlled by the current sinking device.
    Type: Grant
    Filed: May 18, 1988
    Date of Patent: September 19, 1989
    Assignee: Zerox Corporation
    Inventor: Jeffrey J. Folkins
  • Patent number: 4864459
    Abstract: A frame is placed in the flow of incident air from a laminar flow hood, and bare wires and insulated wires are stretched over the frame. A source including a transformer produces an alternating voltage. One of the outputs thereof is directly connected to the insulating wires and the other output thereof is connected to the bare wires via a capacitor. An electrode placed inside the volume of the cabinet fed with air from the hood is connected to a DC amplifier which applies a correcting voltage to the insulated wires. This apparatus turns out to be highly effective, in particular, for removing dust and neutralizing charge when manufacturing VLSI circuits.
    Type: Grant
    Filed: October 1, 1987
    Date of Patent: September 5, 1989
    Assignee: Office National D'Etudes Et De Recherches Aerospatiales
    Inventors: Serge Larigaldie, Joseph Taillet
  • Patent number: 4843336
    Abstract: A detachable multi-purpose self-defending device and in particular to one mainly composed of a grip and a barrel, the grip being provided with a high voltage oscillating circuit for supplying a high voltage to the electrodes mounted at the front end of the barrel so as to be able to make the wicked faint temporarily, a pizo siren for sending out warning signal to arouse the other's attention to arrest the wicked, a flashlight for giving light in the dark, and a strobe light for emitting rapid, brief and brilliant flashes of light to cause the weaked to lose consciousness momentarily. Moreover, the grip may be connected to a leaf-spring switch which is inserted between the door and the frame so that when the door is opened, the spring leaves thereof will separate from each other hence actuating the pizo siren.
    Type: Grant
    Filed: December 11, 1987
    Date of Patent: June 27, 1989
    Inventor: Shen-Shaon Kuo
  • Patent number: 4841425
    Abstract: A high-voltage power supply apparatus includes a transformer, and an input winding is turned on and off repeatedly by a switching element, and thereby an alternating current (AC) is generated in the input winding. By varying the duration of a turned-on state or a turned-off state of the switching element, an output voltage from the output winding of the transformer is regulated. A series connection of a first resistor and a transistor is connected between one end of the output winding and a reference potential. A second resistor is connected in parallel with the series connection. A medium voltage circuit is connected through a diode between the other end of the output winding and the reference potential, and a high voltage circuit is connected between a connection point of the medium voltage circuit and the diode and the reference potential.
    Type: Grant
    Filed: May 28, 1987
    Date of Patent: June 20, 1989
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Yukio Maeba, Kiyoteru Igashira
  • Patent number: 4833583
    Abstract: Device for supplying power from a three-phase network to an ozonizer comprising at least two discharge elements (3, 4) having a capacitive character, and comprising two single-phase step-up transformers (1, 2) having air gaps connected in a SCOTT circuit and connected between the three-phase network and said discharge elements (3, 4). The device further comprises a three-phase transformer (8) whose secondary windings (5, 6, 7) are connected between said single-phase transformers (1, 2) and the three-phase network and whose primary windings (9, 10, 11) are star-connected and connected to the three-phase network through a dimmer (12).
    Type: Grant
    Filed: January 22, 1988
    Date of Patent: May 23, 1989
    Assignee: Trailigaz-Compagnie Generale De L'Ozone
    Inventor: Jean F. Petitimbert
  • Patent number: 4825334
    Abstract: The maximum subcorona potential level to which a particular conductive bristle brush is able to regulate an electrostatic charge on charge-retaining material is substantially increased by limiting the electrical current available to said particular conductive bristle brush from a potential source coupled to said brush to a level that is less than a magnitude necessary for corona generation.
    Type: Grant
    Filed: September 24, 1985
    Date of Patent: April 25, 1989
    Assignee: Polaroid Corporation
    Inventor: Semyon Kisler
  • Patent number: 4808200
    Abstract: An electrostatic precipitator is supplied with a d-c voltage of variable level upon which is superimposed a series of voltage pulses. For each voltage pulse, the difference between a positive current-time area and a negative current-time area beneath a current-voltage curve is determined and maximized by changing the pulse amplitude, pulse width, pulse repetition frequency and/or the rate of pulse rise. In addition, the d-c voltage is controlled to have a value at a point of maximum slope of the function of precipitator current with respect to the magnitude of the d-c voltage.
    Type: Grant
    Filed: November 12, 1987
    Date of Patent: February 28, 1989
    Assignee: Siemens Aktiengesellschaft
    Inventors: Richard Dallhammer, Franz Neulinger, Walter Schmidt, Helmut Schummer
  • Patent number: 4809127
    Abstract: Apparatus for ionizing air molecules to suppress electrostatic charges in a room or for other purposes includes internal feedback which maintains a desired rate of ion production in the presence of electrode deterioration or other effects which could otherwise alter ion output. Production of air ions of a given polarity results in a ground return flow of electrical charges of opposite polarity from the high voltage generator at a rate corresponding to the rate of air ion output. The ground return current is monitored to produce an electrical feedback signal. A control circuit causes the high voltage generator to apply higher voltage to the electrode when the feedback signal decreases and to apply lower voltage to the electrode when the feedback signal increases. Such self-regulation of each individual electrode in systems having an array of electrodes that are otherwise jointly controlled acts to maintain a desired ratio of positive and negative ions in a room as well as a desired total ion concentration.
    Type: Grant
    Filed: August 11, 1987
    Date of Patent: February 28, 1989
    Assignee: Ion Systems, Inc.
    Inventors: Arnold J. Steinman, Michael G. Yost, Donald A. Gehlke
  • Patent number: 4791528
    Abstract: There is disclosed an integral power supply device for supplying a high voltage and a low voltage in stable manner. A switched input voltage is supplied to a self-excited transformer having two secondary output voltages. A high voltage output is supplied to a first load and is controlled by a control circuit which receives a low voltage output supplied also to a second load.
    Type: Grant
    Filed: March 7, 1988
    Date of Patent: December 13, 1988
    Assignee: Canon Kabushiki Kaisha
    Inventors: Koji Suzuki, Shunichi Komatsu
  • Patent number: 4789801
    Abstract: Electrokinetic transducing methods and systems are disclosed in which the two electrode arrays confront each other and each electrode in one array is equidistant from the two nearest electrodes in the other array. The electrode arrays are excited by pulsed exciting voltages, the individual pulses of which are preferably all negative or all positive, have durations equal to or less than the pulse intervals, and have rounded leading knees. Embodiments of the invention are disclosed for applications including electrokinetic loudspeakers, ion generators, fans, and electrostatic precipitators.
    Type: Grant
    Filed: April 3, 1987
    Date of Patent: December 6, 1988
    Assignee: Zenion Industries, Inc.
    Inventor: Jimmy L. Lee
  • Patent number: 4785373
    Abstract: An electrostatic discharge simulator employing the combination of a chargeable member connected in parallel with a parallel plate capacitor network. The chargeable member is maintained charged by a high voltage supply through a charging resistance. The capacitor network includes a bank of resistors and capacitors for providing a voltage step simultaneously with an ESD event and is detected by an event detector. The event detector turns off the high voltage supply. To charge the capacitances for the next event, the event detector is reset using a reset switch built into the device probe.
    Type: Grant
    Filed: August 7, 1987
    Date of Patent: November 15, 1988
    Inventor: Glen Dash
  • Patent number: 4785372
    Abstract: A method of charging or discharging a member including the steps of, opposing to a member to be acted, a discharging member having a dielectric member, an inducing electrode and a discharging electrode sandwiching the dielectric member so that the discharging electrode faces the member to be acted, applying an alternative voltage between the inducing electrode and the discharging electrode to produce a surface discharge on a surface of the dielectric member at the discharging electrode side, moving the member to be acted relative to the discharging electrode to charge or discharge the member to be acted by the thus formed surface discharge, ceasing the production of the surface discharge by attenuating both of positive and negative, at the discharging electrode relative to the inducing electrode, components of the alternating voltage at least down to a discharge stopping voltage and then rendering the voltage zero.
    Type: Grant
    Filed: September 15, 1986
    Date of Patent: November 15, 1988
    Assignee: Canon Kabushiki Kaisha
    Inventors: Nagao Hosono, Yukio Nagase, Tatsuo Takeuchi, Hidemi Egami, Hiroshi Satomura
  • Patent number: 4783716
    Abstract: A device for electrically discharging or charging a member to be discharged or charged, includes a dielectric member, first and second electrodes embedded in the dielectric member, the first and second electrodes being supplied with an alternating voltage therebetween to cause discharge adjacent a part of a surface of the dielectric member at a predetermined discharge starting voltage, a third electrode disposed to or adjacent a part of the surface of the dielectric member at such a position as when the discharge occurs by application of the alternating voltage between the first and second electrodes, no discharge occurs between the first electrode and the third electrode or between the second electrode and the third electrode, AC source for applying an alternating voltage between the first electrode and the second electrode, DC source for applying a bias voltage between the third electrode and the member to be discharged or charged.
    Type: Grant
    Filed: January 29, 1987
    Date of Patent: November 8, 1988
    Assignee: Canon Kabushiki Kaisha
    Inventors: Yukio Nagase, Hiroshi Satomura, Hidemi Egami, Yoshihiko Hirose
  • Patent number: 4775915
    Abstract: A corona charger includes a conductive electrode and a corona wire between the electrode and a receiver. A non-conductive shell about the wire is open toward the receiver. A voltage is periodically applied to the wire, whereby a corona charge is produced in the shell and the shell charges with the wire such that the corona charge is directed toward the receiver. A voltage is applied to the electrode of same sign but lagging the voltage applied to the wire such that the corona charge is accelerated by the electrode to the receiver when the voltage on the electrode approximates the voltage on the wire.
    Type: Grant
    Filed: October 5, 1987
    Date of Patent: October 4, 1988
    Assignee: Eastman Kodak Company
    Inventor: George R. Walgrove, III
  • Patent number: 4757422
    Abstract: A dynamically balanced ion generator is provided which incorporates a detection screen and feedback loop to ensure that the number of positive and negative ions emitted from the generator are substantially equal. The detection screen is located between the ion generating electrodes and the exit port of the device, and is contructed of conductive material which captures a predetermined percentage of ions emitted by the electrodes. The detected imbalance is corrected through a feedback loop comprising an operational amplifier circuit, a low pass filter, a balance control comparator, variable duty cycle oscillator. By varying the duty cycle of the variable duty cycle oscillator, the voltage applied to the primary of a high voltage transformer is controlled such that the relative concentrations of positive and negative ions generated may be altered to compensate for any detected imbalance.
    Type: Grant
    Filed: September 15, 1986
    Date of Patent: July 12, 1988
    Assignee: Voyager Technologies, Inc.
    Inventors: Peter R. Bossard, Robert H. Dunphy, Jr., Michael R. Betker
  • Patent number: 4757421
    Abstract: A room air ionization system for removing electrostatic charge from objects within the room in which one or more pairs of spaced-apart bus bars are equipped with regularly spaced, sharply pointed pins such that when the bus bars are energized with a predetermined high voltage, ions are emitted from the pointed electrodes to flood the room with approximately equal numbers of positive and negative ions. When the ions are electrically attracted to bodies exhibiting an electrostatic charge of opposite polarity, the charges are effectively neutralized. Because, in systems of this type, there is a tendency for particles of dirt to be attracted to the bus bars, spacers and surrounding ceiling and wall surfaces, frequent cleaning is usually necessary.
    Type: Grant
    Filed: May 29, 1987
    Date of Patent: July 12, 1988
    Assignee: Honeywell Inc.
    Inventor: Fred Mykkanen
  • Patent number: 4747012
    Abstract: A high-voltage power supply apparatus comprises a transformer, and an input winding is turned on and off repeatedly by a switching element, and thereby an alternating current (AC) is generated in the input winding. By varying a turned-on state or a turned-off state of the switching element, a voltage outputted from an output winding of the transformer is regulated. An output voltage of a dividing circuit which is constituted with two series resistors and divides an output voltage is compared with a reference voltage by a comparator, and a control signal in accordance with an output of the comparator is given to the switching element. A switching circuit is connected to one of the resistors of the voltage dividing circuit in parallel.
    Type: Grant
    Filed: January 7, 1987
    Date of Patent: May 24, 1988
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Yukio Maeba, Kiyoteru Igashira
  • Patent number: 4745520
    Abstract: An electrostatically aided coating dispensing system in which the high distributed capacitance of a high voltage cable for connecting the high voltage supply to dispensing device is entirely eliminated.
    Type: Grant
    Filed: October 10, 1986
    Date of Patent: May 17, 1988
    Assignee: Ransburg Corporation
    Inventor: Daniel C. Hughey
  • Patent number: 4740862
    Abstract: A relatively simple and compact device is disclosed for monitoring ion imbalance at a preselected, or work, area. A collector is utilized that is charged due to ions contiguous thereto, with the charge at the collector being processed, preferably utilizing a charging capacitor and operational amplifier, to provide an output signal indicative of ion imbalance at the preselected area, which output signal is then utilized to produce an indication of ion imbalance at the preselected area and/or to correct the ion output of an ion generator directing ions toward the preselected area. A pair of collectors can be utilized to separately sense positive and negative ions separately generated by an ion generator with the acquired charge on each collector being separately processed, and the indication of ion imbalance can be accomplished utilizing a meter and/or alarm.
    Type: Grant
    Filed: December 16, 1986
    Date of Patent: April 26, 1988
    Assignee: Westward Electronics, Inc.
    Inventor: Michael E. Halleck
  • Patent number: 4728880
    Abstract: Apparatus is disclosed for driving from a single AC power supply a plurality of corona chargers and includes a substantially constant-potential power supply and a circuit interconnecting said power supply to the plurality of corona chargers such that a substantially constant average current input is delivered to each of the corona chargers. The circuit includes a capacitor associated with each corona charger between the power supply and the corona charger such that the capacitors charge upon transition of the AC power source, and thereupon discharge through the chargers until the corona onset potential is reached. Upon reaching the onset potential, the corona current is quenched. The capacitors are selected such that quenching occurs after the transition within a time interval less than half the period of the AC power supply so that each capacitor regulates the current output of the associated corona charger.
    Type: Grant
    Filed: November 28, 1986
    Date of Patent: March 1, 1988
    Assignee: Eastman Kodak Company
    Inventor: George R. Walgrove
  • Patent number: 4729057
    Abstract: A static charge control device is disclosed having an electrostatic focusing arrangement. The device requires no forced air element yet enables ions, produced at separate positive and negative needle electrodes, to be separately directed outwardly to a neutralizing area for neutralization of static charges thereat. The needle electrodes are mounted on a mounting plate so that the tips of the needles extend forwardly through different apertures in the forwardly positioned electrostatic focusing plate.
    Type: Grant
    Filed: July 10, 1986
    Date of Patent: March 1, 1988
    Assignee: Westward Electronics, Inc.
    Inventor: Michael E. Halleck
  • Patent number: 4714978
    Abstract: A circuit for supplying power to the a.c. corotrons of copying or printing machines using a high leakage inductance type transformer both as a power transformer and as a low pass filter; a d.c. power source coupled to the transformer primary winding center tap; a push-pull amplifier having a MOSFET gate pair controlling energization of the transformer primary winding halves by the d.c. power source; a pulse width modulator for supplying alternating signal pulses to the MOSFET pair at a fixed frequency; a voltage doubler network for monitoring corotron current, the modulator adjusting the pulse width of the signal pulses in response to the network control signal to thereby adjust the power output of the circuit and maintain a constant corotron current; and a capacitor at the transformer output cooperable with the transformer to form said low pass filter.
    Type: Grant
    Filed: April 17, 1986
    Date of Patent: December 22, 1987
    Assignee: Xerox Corporation
    Inventor: James A. Coleman
  • Patent number: 4710849
    Abstract: Control of high voltage is effected using apparatus having a high impedance generator, the output being connected to a first member of low radius of curvature and a second member. The two members are spaced apart by a gas gap so that when the voltage between them exceeds a threshold value corona discharge across the gas can occur. Such apparatus is particularly useful in controlling voltage and hence the size and size distribution of liquid droplets in electrostatic spraying apparatus.
    Type: Grant
    Filed: July 8, 1985
    Date of Patent: December 1, 1987
    Assignee: Imperial Chemical Industries PlC
    Inventor: Alan J. Norris
  • Patent number: 4704672
    Abstract: Method and arrangement for varying a d.c. voltage occurring between electrodes of an electrostatic dust separator, said voltage being generated by a number of frequency-related pulses together forming a pulse train. A mains voltage (50 Hz) is fed via valve organs (8, 8a) controlled by a control circuit (7) to a transformer (T), the current pulses of which are full-wave rectified (9) and are connected to electrodes (10) of the dust separator. The control circuit (7) is so arranged as to extinguish an even number, being two, four or more, of pulses from the mains voltage between two consecutive pulses supplied to the electrodes of the dust separator.
    Type: Grant
    Filed: May 13, 1985
    Date of Patent: November 3, 1987
    Assignee: Flakt AB
    Inventor: Alf G. Gustafsson
  • Patent number: 4694376
    Abstract: Circuit for the pulsed operation of one or more high frequency ozonizers, having at least one power supply producing a direct current, having a number of circuits corresponding to the number of ozonizers for the derivation of electrical pulses from the direct current, and having a number of high voltage transformers corresponding to the number of the ozonizers, to whose primary side the pulses produced by each of the circuits are fed and whose secondary side is connected each to an ozonizer. The circuits contain, in accordance with the invention, a pulse width control triggered by an oscillator.
    Type: Grant
    Filed: September 26, 1985
    Date of Patent: September 15, 1987
    Inventor: Rudolf Gesslauer
  • Patent number: 4689715
    Abstract: A static charge control device is disclosed having laminar flow. The device utilizes a pair of spaced electrodes mounted adjacent to a pair of spaced apertures with the electrodes being positioned so as not to extend into the apertures. As specifically shown, a pair of needle electrodes are mounted on a mounting plate with each electrode being mounted above a different aperture in the plate with the needle electrodes extending outwardly from the mounting plate in a direction substantially normal thereto so that the tips of the electrodes extend in the direction of a laminar flow of air passing through the apertures in the plate, which air is provided by a fan positioned rearwardly of the mounting plate.
    Type: Grant
    Filed: July 10, 1986
    Date of Patent: August 25, 1987
    Assignee: Westward Electronics, Inc.
    Inventor: Michael E. Halleck
  • Patent number: 4682266
    Abstract: A solid state thyristor bridge inverter power supply for an ozonator in which the width and the amplitude of the ozonator current can be controlled and the ozonator voltage can be selectively reset. The power supply circuit includes a diode bridge rectifier for converting a commercial AC power main into a direct current power source which is coupled to a current source DC/AC inverter through a inductor and a current detecting circuit. A current amplitude control circuit controls the output current of the DC power source by comparing the output of the detecting circuit with a reference set point. Logic circuits are provided for controlling the frequency and the width of current pulses applied to the ozonator.
    Type: Grant
    Filed: April 22, 1985
    Date of Patent: July 21, 1987
    Assignee: National Distillers and Chemical Corporation
    Inventors: Anh N. Huynh, Phoivos D. Ziogas
  • Patent number: 4680686
    Abstract: A supply device connected to a 3-phase mains supply for an ozonizer comprising at least two capacitive discharge elements (7, 8). The device comprises two single-phase step-up voltage transformers (1, 2) having air gaps (5, 6) connected in a Scott circuit and connected between the 3-phase mains supply and said discharge elements (7, 8).
    Type: Grant
    Filed: December 23, 1985
    Date of Patent: July 14, 1987
    Assignee: Trailigaz "Cie Generale de l'Ozone"
    Inventors: Paul Chapsal, Jean-Francois Petitimbert
  • Patent number: 4680669
    Abstract: A corona discharging apparatus is adapted to vibrate a corona discharge wire and/or grid wires by the use of a vibrating element to remove foreign matters deposited on the corona discharging wire and/or grid wires.
    Type: Grant
    Filed: January 24, 1984
    Date of Patent: July 14, 1987
    Assignee: Canon Kabushiki Kaisha
    Inventors: Hiroaki Tsuchiya, Kazuki Tanaka, Keishi Osawa
  • Patent number: 4680533
    Abstract: A method and apparatus for protecting switching elements, and in particular, thyristor switching elements, which are used to supply pulses to a capacitive load, from damage resulting from sparkover occurring in that load are described. The load voltage pulse is characterized by a period of rising voltage followed by a period of falling voltage, these two periods being separated by a transition period of maximum vulnerability of the switching element to damage from sparkover. Specifically, during this period of maximum vulnerability of the switching elments to damage, a gate trigger pulse is applied to the elements to cause them to resume a conductive state, independent of the occurrence of an abnormal sparkover condition.
    Type: Grant
    Filed: August 1, 1985
    Date of Patent: July 14, 1987
    Assignee: General Electric Company
    Inventors: Abdallah M. Itani, Gerald J. Carlson, Peter W. Dietz
  • Patent number: 4680532
    Abstract: A method and apparatus for protecting switching elements, and in particular, thyristor switching elements, which are used to supply pulses to a capacitive load, from damage resulting from false triggering signals, i.e., triggering signals not accompanied by actual sparkover conditions in the load. Since termination of normal pulse cycles in such pulser systems are accomplished by a return to high forward voltage across the switching elements, false triggers generated closely prior to such termination and within the forward recovery time of a thyristor switching element present a danger that the termination of a normal cycle will result in a weak turn-on and consequent damage of the switching element. By insuring that all such potentially false triggers have a duration which extends past termination of the pulse cycle damage to the switching element resulting from such false triggers is inhibited.
    Type: Grant
    Filed: August 1, 1985
    Date of Patent: July 14, 1987
    Assignee: General Electric Company
    Inventors: Abdallah M. Itani, Peter W. Dietz, Gerald J. Carlson
  • Patent number: 4674003
    Abstract: A high-voltage generator for electrostatic sprayer devices includes a frequency-clocked power amplifier for feeding the primary of a transformer whose secondary is connected to a high-voltage cascade or multiplier circuit. The power amplifier is connected to a controllable low-voltage d.c. voltage source and to a controllable frequency generator, whereby the control of the d.c. voltage source and of the frequency generator is provided by a microcomputer such that the transformer is optimally matched for all voltages appearing at the high-voltage output of the cascade.
    Type: Grant
    Filed: April 3, 1985
    Date of Patent: June 16, 1987
    Assignee: J. Wagner AG
    Inventor: Hans-Joachim Zylka
  • Patent number: 4672505
    Abstract: A corona discharging device having a corona discharging electrode to which a high voltage is applied to produce corona discharge. The high voltage applied to the corona discharging electrode is provided by superposing an AC voltage to a DC voltage. The DC voltage and the AC voltage are determined such that the corona discharging current has only the polarity which is the same as that of the DC component voltage. The corona discharge is stabilized and hardly produces a non-uniform discharge.
    Type: Grant
    Filed: June 13, 1985
    Date of Patent: June 9, 1987
    Assignee: Canon Kabushiki Kaisha
    Inventors: Hiroaki Tsuchiya, Kimio Nakahata
  • Patent number: 4672500
    Abstract: Electrostatic spraying equipment having, in a working area likely to contain inflammable mixtures, at least a terminal part of a high-voltage generator with an electrode for charging a jet of material sprayed from a sprayer. At least one low-voltage line connects the terminal part of the generator to a remotely sited power supply equipped with cut-out device. A protective device designed to prevent repeated arcing in the working area as a result of deterioration of the low-voltage line comprises, in series with the line, a sensing device for sensing a current lower than a predetermined minimum current. A control device responsive to the sensing device are connected to the aforementioned cut-out device so as to operate them when a current in the line lower than the predetermined minimum is sensed.
    Type: Grant
    Filed: September 14, 1984
    Date of Patent: June 9, 1987
    Assignee: Sames S.A.
    Inventors: Roger Tholome, Jean-Pierre Burtin
  • Patent number: 4665462
    Abstract: Ionizing gas gun for ultra-clean static neutralization comprises a plastic nozzle enclosing positive and negative ion discharge electrodes and means for blowing a gas, such as air or nitrogen therethrough. A trigger actuates both the release of gas and application of positive and negative high voltage to the respective discharge electrodes, including delay circuitry for suspending discontinuance of the positive high voltage to its electrode for a momentary period subsequent to discontinuance of the negative high voltage when the gas is cut off in compensation of a slight preponderance of negative ion emission otherwise effected at cut-off. Venturi ports at the nozzle tip draw air over the discharge electrodes for admixing with higher mobility nitrogen ions when nitrogen rather than air is employed as the blowing medium. A changeable filter insures cleanliness, including monitoring means to indicate clogged or ruptured filter conditions or improper installation.
    Type: Grant
    Filed: June 17, 1985
    Date of Patent: May 12, 1987
    Assignee: The Simco Company, Inc.
    Inventors: Mark Blitshteyn, Richard D. Rodrigo, William S. Wright
  • Patent number: 4652694
    Abstract: The invention relates to a corona discharge lightning rod comprising a tip which is isolated from the ground and having a base which is connected via discharge means to the ground, said lightning rod being suitable for ionizing the ambient atmosphere at the end of its tip. An electric circuit is provided for periodically reducing the potential of the tip to a value which is too low to maintain corona discharge, thereby producing periodic and intermittent corona discharge pulses. Preferably, the tip is electrically connected to a potential generator such that the potential (V.sub.0) applied to the tip is a variable potential in the form of recurrent wave trains, and such that the peak value of the first half cycle of the train having a polarity opposite to the polarity of the ambient atmosphere is greater than the threshold at which the corona effect takes place. This need only occur in the presence of the natural amplification (V.sub.
    Type: Grant
    Filed: December 30, 1985
    Date of Patent: March 24, 1987
    Assignee: Centre National de la Recherche Scientifique
    Inventors: Max Goldman, Alice Goldman, Stephane Kuhn, Pierre-Emmanuel Langlois, Gerard Berger
  • Patent number: 4651264
    Abstract: A power supply with automatic arcing control and overload protection includes an electronic switch in an oscillator circuit with a primary winding of a step-up transformer. A high voltage, secondary winding of the transformer is loosely magnetically coupled to the primary winding. The frequency of oscillation of the oscillator circuit decreases as a load impedance across the secondary winding of the transformer decreases. In the case of arcing or shorting of an output circuit of the power supply the frequency of oscillation decreases below a pass band of the output circuit, thereby reducing the output current of the power supply.
    Type: Grant
    Filed: December 28, 1984
    Date of Patent: March 17, 1987
    Assignee: Trion, Inc.
    Inventor: Jerry Shiao-Chung Hu
  • Patent number: 4644439
    Abstract: A spark-over detector for an electrostatic precipitator has a current sensor (3) which provides a signal (a) which is differentiated twice to produce a signal (c). If the level of the signal (c) is above a predetermined level then a level-detecting circuit (7) passes a signal (d) to an AND-gate (8). A second level detecting circuit (9) receives the signal (a) and if this signal is above a predetermined level passes the signal (e) to a timing circuit (10) which provides a signal (f) from a first preset time after having received the signal (e) until a second preset time after the signal (e) has ceased. Thus, if a spark over starts to occur signals (d) and (f) occur simultaneously and the AND-gate produces an output signal (g) which can be used to trigger the thyristor switch circuit of the pulse generator to conduction to prevent thyristor damage or destruction.
    Type: Grant
    Filed: November 2, 1984
    Date of Patent: February 17, 1987
    Assignee: F. L. Smidth & Co. A/S
    Inventor: Claus E. Taarning
  • Patent number: 4638398
    Abstract: A pulse generator operating at a frequency preferably somewhat higher than 100 Hz charges a capacitor through a diode and the trailing edge of the pulse switches-in a discharge circuit to discharge the capacitor through the low-voltage winding of a pulse transformer, the high-voltage winding of which charges, through another diode, the high-voltage insulated conductor of an ionizer that cooperates with a point-bearing electrode that is grounded. The high-voltage electrode discharges through a resistor between pulses and the diode assures that ions of the same polarity will be produced. The ionizer is suited for being located inside a spray gun of an electrostatic coating apparatus for charging the coating material particles with the ions without producing an electric field between the spray gun and the workpiece that would interfere with the coating of hollow places of the workpiece because of the so-called cage effect.
    Type: Grant
    Filed: March 29, 1985
    Date of Patent: January 20, 1987
    Assignee: IRS Industrie Rationalisierungs-Systeme GmbH
    Inventors: Hermann Brennecke, Horst Liere, Michael Kiesel
  • Patent number: 4638397
    Abstract: A scorotron and control therefor for charging and/or discharging a charge retentive surface such as a photoreceptor of the type utilized in the process of xerographic printing. The control connects the wire grid of the scorotron to ground via a plurality of zener diodes and a variable resistor. The voltage across the variable resistor is low compared to the total circuit voltage so that variations in the grid current result in small variations in grid voltage. The control provides for compensation for out of tolerance zener diodes as well as for photoreceptor aging manufacturing tolerances and temperature elevation. When the variable resistor is a light dependent resistor a light emitting diode contained in a bridge network also containing a thermistor provides for automatic compensation due to elevation in photoreceptor temperature when such temperature is sensed by the thermistor.
    Type: Grant
    Filed: December 21, 1984
    Date of Patent: January 20, 1987
    Assignee: Xerox Corporation
    Inventor: Geoffrey M. T. Foley
  • Patent number: 4630167
    Abstract: A system and method for neutralizing a static charge using positive and negative ion discharge units. These units are operated alternately at a rate inversely proportional to the static voltage detected. The system and method operates the ion discharge units in a manner discharging a substantially equal number of positive and negative ions to travel at a selected velocity differential therebetween to selectively modulate the neutralization of ions in transit.
    Type: Grant
    Filed: March 11, 1985
    Date of Patent: December 16, 1986
    Assignee: Cybergen Systems, Inc.
    Inventor: Richard Huggins
  • Patent number: 4619513
    Abstract: An electrophotographic device for a magnetic brush development process in which a conductive material is used for rollers in the conveying mechanism of electrophotosensitive materials which abut on the materials after a charging step by a charging device, but before a developing step by a developing device so as to insulate the rollers from other components. One portion of a shield case of the charging device is insulated from another portion and is electrically connected to the rollers, thereby applying a bias voltage on the rollers using the voltage induced on this portion due to high voltage applied on a corona wire of the charging device.
    Type: Grant
    Filed: March 14, 1984
    Date of Patent: October 28, 1986
    Assignee: Fuji Photo Film Co., Ltd.
    Inventors: Keiichi Yamana, Hajime Tachibana, Shuichi Ohtsuka
  • Patent number: 4603964
    Abstract: A charge scorotron having a U-shaped shield positionable opposite a photoreceptor, a corona discharge wire in the shield, a grid between the wire and the photoreceptor for controlling the emission of ions to the photoreceptor, the grid being electrically subdivided into a first grid segment with a length substantially equal to the dimension of the smallest size copy sheet with subsequent grid segments having lengths chosen when combined with the first grid segment and each other to substantially equal various larger size copy sheets, switches responsive to the position of an adjustable sheet guide in the copy sheet supply tray connecting each of the other grid segments with the grid bias selectively, the switches when not actuated coupling the grid segment associated therewith to ground whereby the area of the photoreceptor charged is determined by the number of grid segments coupled to the grid bias in response to the size copy sheet being processed.
    Type: Grant
    Filed: October 22, 1984
    Date of Patent: August 5, 1986
    Assignee: Xerox Corporation
    Inventor: Gregory B. Swistak
  • Patent number: 4587591
    Abstract: A power supply for an ozone generator utilizes a magnetic-leakage type step-up transformer in series with a saturable core inductor which are connected in series across a low voltage AC source. The secondary of the transformer is connected to the ozone generator and the inductor has a control winding which is connected to a continuous (i.e. DC) current source whose value controls the inductance of the inductor. Since the voltage of the low voltage AC source is divided between the inductor and the transformer, the DC current effectively controls the magnitude of the voltage across the transformer primary and thereby controls the high AC voltage supplied to the ozone generator.
    Type: Grant
    Filed: September 5, 1984
    Date of Patent: May 6, 1986
    Assignee: Degremont
    Inventors: Maurice Adatto, Christian Coste