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.

Abstract: A continuous electrical connection between a high voltage power source and a paint charging electrode in an electrostatic spray gun. The electrode is mounted on a valve needle which is reciprocated by a trigger mechanism as the spray gun is operated. A novel spring establishes and maintains the electrical connection from a stationary contact on the gun barrel to the moving valve needle. The spring may be mounted on a spacer tube mounted coaxially about the valve needle. The spacer tube can move in an axial direction to exert a force on a seal between the barrel and the valve needle without affecting the electrical connection.

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.

Abstract: A powder charging apparatus, in which a plasma electrode pair is disposed within an insulative tubular passage for transporting powder as carried by gas, a device for intermittently applying a D.C. voltage between that pair of plasma electrode is provided to form a space where mainly desired polarity ions drawn from the plasma electrode pair exist and another space where mainly opposite polarity ions exist, well dispersed powder is fed to the former space where mainly the desired polarity ions exist, and thereby stable and strong charging performances can be assured for a long term without adhesion and accumulation of the powder to and on either one of the pair of plasma electrodes; and an electrostatic powder painting apparatus containing this powder charging apparatus therein and having excellent penetrating performance and painting efficiency.

Abstract: It is described a novel powder charging apparatus, wherein a high voltage is applied between a couple of electrodes, consisting of a plasma electrode of required polarity and a plasma electrode of opposite polarity, to form plasma at tip of each of electrodes, an eventually finely dispersed powder is made to pass only through an area wherein mainly ones of negative and positive ions derived of said plasma, that is, ions of required polarity exist, and thereafter the charged powder is discharged. In this apparatus, the adhesion of powder to each electrode is prevented and charging performance is maintained for a long time. It is also described an electrostatic powder coating apparatus comprising the above-described novel powder charging apparatus, which is excellent in performance for making thick coating, depositing efficiency and throwing power.

Abstract: A spraying gun for electrostatic spraying of coating material on an article contains a discharge electrode which is disposed entirely outside the region where the coating material flows. The coating material is accelerated through an annularly shaped and axially extending channel in which the coating material is electrically charged by friction between itself and the insulated walls that define the channel. A gas conduit extends from the discharge electrode and reaches into the annular feed channel of the coating material. Location of the gas conduit between the discharge electrode and the feed channel allows the gas flowing in the gas conduit toward the feed channel to serve the dual purposes of preventing coating material from flowing to and settling on the discharge electrode and providing an electrically conductive path through which undesired electrical charges which develop on the walls of the feed channel discharge to the discharge electrode.

Abstract: Apparatus for ionizing air, for example for feeding to a boiler to act as a catalyst, comprises a closed container (15) which is divided into two chambers (17, 18). Water is fed under pressure to atomizing jets (21,22) which produce a mist inside each chamber. Air is fed by a pump (28) into the first chamber and passes upwards through the mist in that chamber, through an aperture (20) near the top of a partition wall (19) and downwards through the mist in the second chamber. The thus-ionized air leaves the second chamber via an outlet pipe (30) and passes through a demoisturizing coil (31). The water for feeding to the jets is contained in a reservoir (2) at the bottom of a casing (1) in which the container is mounted.

Abstract: Electrostatic spraying apparatus wherein the liquid supply to the spray nozzle 20 is via a mechanical valve operated by an actuating member 12. Actuating member 12 is connected to a remote operating lever 3, which is preferably electrically conductive, via a connecting member 41 including an elastically extensible portion, e.g. a spring 39. Connecting member 41 is electrically conductive thus providing an electrical connection from lever 3 to the spray head.

Abstract: An electrostatic spray system including a spray device having a coating-charging electrode, a source of high voltage electrostatic potential, and a resistive path for safely transmitting high voltage between the electrode and the electrostatic supply. The resistive high voltage transmission path is composed of plural parallel-connected continuous silicon carbide fibers.

Abstract: An electrostatic spray gun muzzle comprises an insulating tube having a rear end adapted to be mounted in an electrostatic spray gun and a front end providing an exit for charged coating material. A conductive rod is mounted axially within the tube and has a conductive pin extending radially from one end thereof. The pin is electrically connected to a power terminal when the rear end of the insulated tube is mounted in a spray gun. A plurality of conductive centering bars extend radially from the rod, adjacent the front end of the insulating tube, to maintain the rod in centered, axial alignment with the insulating tube. An insulating deflector is mounted to the conductive rod, forward of the front end of the insulating tube.

Abstract: Electrostatic spraying apparatus e.g. for graphic work, having a hand or finger held body carrying a nozzle to which the atomizing potential is applied from a high voltage generator. The nozzle is of the non-drip type, e.g. a capillary bore or a felt- or fibre-tip so that no liquid is dispensed therefrom in the absence of the atomizing potential. The nozzle and liquid reservoir may be a cartridge, e.g. a felt-tip graphic marker. The generator may be within the body so as to provide a self-contained unit which can be "earthed" via the user's hand.

Abstract: A method of protecting a plant for coating objects with charged particles as well as a method and apparatus for coating objects is proposed. The generation of an electric arc having a too high energy which can cause an ignition of the particles to be applied onto the object is prevented by applying a test high voltage between the object to be coated and the respective earth connection. An insulation occurring between the object to be coated and the respective earth connection and having a contact resistance smaller than a permitted maximum value is overcome by an arcthrough of lower energy. The current flowing in the closed circuit is measured for determining the contact resistance of the insulation so that the operation of the plant can be stopped when the actual value of the current is below a minimum value as in this case the insulation cannot be overcome by the arcthrough as its contact resistance is higher than the permitted maximum value.

Abstract: An electrostatic spray gun having a rotatable voltage generator for providing electrical energy at low voltage for conversion within the spray gun into electrostatic high voltage energy, wherein a rotating voltage generator is driven by an air turbine under the influence of a pressurized input air supply, the pressurized air passing through conduits in the handle of the spray gun, an air valve actuated by a trigger, an air flow regulator, and into impinging contact against rotatable turbine blades. The air supply is exhausted from the spray gun through internal passages which provide cooling air to the electrical components within the spray gun, and through further passages opening from the bottom of the spray gun handle which minimize the audible noise caused by such air flow.

Abstract: A cleaning device on an electrophotographic copier uses a toner transport device having a housing with a toner transport device inside and electrode means integral with the periphery of the housing to generate electrostatic waves which affect the toner particles to preclude accumulation in the housing.

Abstract: A particle charging apparatus (Boxer-Charger) is constructed by disposing electrode assemblies each consisting of corona discharge electrodes and excitation electrodes, in parallel to each other with a charging space interposed therebetween. An a.c. voltage is applied between the corona discharge electrodes in the respective assemblies to establish a main electric field in the charging space. When the a.c. main voltage has entered a half cycle of particular polarity such as, for example, negative polarity, an excitation high frequency voltage including fast-rising pulses having a pulse duration time of 1 ns-1 ms is applied between the corona discharge electrodes and the excitation electrodes in the assembly to generate a creeping streamer on the corona electrode surface and thereby form a two-dimensional plasma source.

Abstract: A method and apparatus for creating electrostatic field by forming a high resistive anodic-oxidized film on an electrostatic electrode and applying thereto a high voltage direct current including high frequency component resonatable with inherent resistance and capacitance in the high resistive film.

Abstract: An electrodynamic spray painting system having a spray gun (13) for spraying paint toward a workpiece (15) and an electrode (16) for causing a charge to be imposed on the paint. A high voltage waveform generator (21) supplies an oscillating voltage to said electrode (16) such that coronas of varying strengths are periodically, controllably generated.This oscillating voltage enhances the spectrum of charges on the paint particles improving evenness of coverage of paint on the workpiece (15). Additionally, wastage of paint is decreased. This invention is also applicable to other coating materials, such as powders.

Abstract: A method of spraying electrically charged particulate material to ground from a low flying airplane. The method includes the steps of imposing an electrical charge of given polarity upon an emitted primary spray of particulate material of sufficient magnitude to electrostatically enhance the deposition thereof and concurrently emitting a secondary spray of oppositely charged particulate material of selective character from said airborne source at a charge level of a magnitude to avoid material degradation of the charge on said primary spray intermediate its loci of emission and deposition.

Abstract: An electrostatic powder painting device provided with an improved powder electro-charging device is described herein, which painting device comprises a duct for conveying powder suspended in gas, an electrode chamber communicating with a slit formed along the entire inner circumference of said duct, a ring electrode disposed within said electrode chamber and having a substantially large radius of curvature in cross-section, a corona discharge electrode disposed at the center of said duct, gas introduction means into said duct through said slit, a voltage source for applying a voltage between said corona discharge electrode and said ring electrode, and means disposed in the proximity of the outlet end of said duct for regulating an ejection pattern of a powder cloud, whereby said painting device can maintain an highly excellent charging performance over a long period of time when the powder conveyed by the gas is charged with unipolar electric charge and also the most important performance of an electrostatic

Abstract: An apparatus and method for applying powdered coating materials includes a central channel for directing the powdered coating material passed a conduit that mixes an air jet with the powdered material. The powder is then ionized and forced outwardly towards the workpiece. A conductive cathode attractor ring for creating a corona space charge which ionizes the particles is provided and includes a radially inner porous portion. Contamination of the attractor ring due to adherence thereon of powder particles is inhibited by diverting a secondary pressurized air flow through said porous portion thereby dislodging powder particles adhering to the ring. The porous inner portion is formed of a sintered mass of individual particles which provides an increased surface area for the attractor ring that, in turn, increases the corona space charge. A slidable deflector member is provided at the end of the central channel to alter the spray pattern of the apparatus.

Abstract: A hand-held manually operable deposition gun for projecting electrostatically charged particles. The gun includes at its front end means for discharging the particles, which may be either liquid or solid, and an electrode for electrostatically charging the particles. The electrode is maintained at a high unidirectional voltage of several tens of kilovolts by connection to a piezoelectric generator through a voltage integrating device, both mounted at the rear of the gun. The piezoelectric generator is actuated by a motor-driven impulse means also located at the rear of the gun. A trigger mounted on the gun activates both the motor and the flow of particles from the gun.

Abstract: A device for painting by electrostatic powder spraying wherein a passage for triboelectrifying powder particles is formed in an electrically conductive housing and is surrounded by an electric insulator layer of a synthetic macromolecular material, such as nylon or fluorocarbon resin, containing powder of an electrically conductive material, such as copper, aluminum or carbon. As the electrostatic powder moves through the passage, it frictionally engages the insulator layer and causes an electric charge on the surface of the electric insulator, due to the triboelectrification movement in the electric insulator, and a current flows to the powder. Therefore, powder particles can be continuously triboelectrified without suppling any voltage or with supplying a very low voltage for forming an electric field.

Abstract: In a device for electrically charging particles, a pair of parallel plasma generators are spaced from one another, each of the generators having corona discharge electrodes. A main field forming source of high AC voltage is connected between the plasma generators, to form a main field in the charging space, and intermittently operating corona generating high voltage power sources are coupled to apply high voltages to the respective corona discharge electrodes only when the plasma generators have relative specific polarity, whereby only particles of one polarity are driven into the charging space. The intermittent corona generating high voltage source has a frequency equal to or greater than the frequency of the AC voltage which provides the main AC field.

Abstract: Electrostatic spraying apparatus comprises a rotary spraying head and a multiple electrode arrangement which includes two high voltage electrodes one of which has an uninsulated portion, and a grounded electrode. A paint flow space is defined between the uninsulated portion and the grounded electrode as well as the remainder of the one high voltage electrode and the grounded electrode. The second high voltage electrode is spaced outwardly from the grounded electrode and has an insulating layer both on its outer side and on its side facing the grounded electrode.

Abstract: An improved powder material processing apparatus is described herein, in which a plurality of wire-shaped electrodes are disposed within an imaginary plane at an equal interval and in parallel to each other. An insulator layer is interposed between the adjacent wire-shaped electrodes to prevent spark discharge from being generated by an A.C. high voltage applied between the adjacent wire-shaped electrodes. A silent discharge region is established between said adjacent wire-shaped electrodes, and positive and negative charges are separately given to the particles forming said powder material by making uncharged powder material pass through said silent discharge region, resulting in formation of powder material consisting of substantially equal numbers of positively charged particles and negatively charged particles, whereby control characteristics of the processed powder material can be greatly improved and the above-mentioned charging process can be effected continuously at a high efficiency.

Abstract: An apparatus for use with a device for producing a suitable electric field to effect the electrodynamic spraying of solutions, dispersions, or mixtures of solids. The apparatus includes at least one spray station for spraying into a given spray zone. Each spray station includes two spaced apart tanks for holding the medium to be sprayed and which are disposed on both sides of the spray zone. An endless band is supported by pulleys disposed at each tank for circulating the band and constantly running a run thereof through the tanks. Squeegees are disposed at each tank to remove excess medium from the band and inlet and outlet connections in each tank effect a desired level of the medium therein.

Abstract: A dry dusting applicator for laying down a powder profile of starch, wax, or the like onto a substrate which comprises a receptacle for holding the powder to be dispensed which has an open bottom, a dispensing roll set in the open bottom and capable of picking up powder as it rotates in the receptacle and a brush means functioning to meter powder from the dispensing roll as well as otherwise preventing powder egress from the receptacle. In a preferred embodiment, at least one high voltage discharge wire charged to provide the desired electrostatic field is included and is positioned relative to the brush so that powder does not build up within.

Abstract: An electrostatic hand-held coating-dispensing apparatus includes a first pulley, a second pulley, and a continuous belt trained about the first and second pulleys. The first and second pulleys are supported and retained in spaced apart relation to maintain tension on the belt in a supporting housing. A first brush is provided adjacent the belt where the belt is trained about the first pulley. A second brush is provided adjacent the belt where the belt is trained about the second pulley. A curved conducting surface is also supported by the housing. The second brush is connected to the conducting surface. A small alternating current electric motor is provided for turning the first pulley. A container or canister is provided for the coating material. The canister is snugly received in the supporting housing in a position adjacent the conducting surface. The canister includes an end for transferring electrostatic potential from the curved surface to the coating material therein.

Abstract: Small highly charged droplets are produced without concurrent production of corona by conducting a liquid to a nozzle having a tip from which droplets of the liquid can exit, and forming a substantially uniform electric field over the surface of the liquid on the tip, the field being large enough to pull off droplets from the tip but not so large as to create corona discharge. Selected gas, solid particulates and liquid mists from gaseous effluents such as are produced by smelters, coal or oil-burning steam generators, chemical refineries and the like are removed by means of a unique electrostatic collector using the highly charged droplets. These droplets are caused to drift, by means of an electric field, through the gaseous effluent to a collecting electrode absorbing selected gases and aerosol particles and carrying them to a collecting electrode.

Abstract: A gun for tribo charging powder has a barrel body with a bore having an opening at one end. A venturi forming tube is contained in the barrel bore and a supply of powder enters the barrel through a bore of the venturi forming tube, which is in alignment with the bore of the barrel, creating an obstruction free passageway for the powder. A supply of pressurized propellant gas enters the barrel bore through an area between the outer venturi forming tube wall and the inner barrel wall and is the power source for charging the powder. Modifications for increasing the charge imparted to the powder include an insert in the venturi forming tube bore for forcing the powder to travel closer to the barrel wall upon exiting the venturi forming tube bore, and a system of holes through the venturi forming tube wall for imparting swirling motion to the powder in the venturi forming tube bore.

Abstract: A self adjusting power supply for induction charging electrodes used in electrostatic spray coating apparatus is disclosed. A first resistance of high ohmic value is connected in series between a source of high direct current voltage and the induction charging electrode, while a second resistance is connected between the source of voltage and a ground reference point. The first resistance acts as a voltage divider with the spacial impedance which exists between the charging electrodes and ground in the spray nozzle of the spray coating apparatus, and serves to regulate the charging voltage and to compensate for variations in the conductivity of the material being sprayed. If the value of the spacial impedance should decrease for any reason, the increased current flow therethrough produces an increase in the voltage drop across the first resistance, thereby reducing and thus regulating the potential at the charging electrodes and serving to prevent corona and arcing within the spray gun.

Abstract: A tribo-electro-gas-dynamic powder coating apparatus with an obstruction-free barrel having a semi-toroidal section throat at the inner end and having an opening at the outer end. An end cap is connected to the barrel end over the semi-toroidal section to form an annular chamber circumferentially surrounding the semi-toroidal section and having a clearance between the section and the end cap leading from the chamber to the barrel bore.

Abstract: In an electrostatic coating system in which material is sprayed onto a workpiece under the influence of an electrostatic field, any electrostatic charge supplied to the workpiece is removed by a discharging device maintained out of contact with the workpiece and disposed so that its effective range is outside the material spray region.

Abstract: Apparatus for applying powdered coating materials includes a channel portion wherein the powder coating material is passed around a conduit which delivers an air jet to the powder material, and where the powder material is ionized, and then forced through an outlet channel. The latter is made of nonconductive material, and includes a non-conductive insert disposed in the channel, with the dielectric constant of the insert being different from the dielectric constant of the material of the remainder of the channel. The ionized powder is directed by gas pressure through the channel toward a grounded object to be coated. The ionization electrode within the apparatus is hollow and an air jet is passed therethrough to aid in the dispersion of the powdered coated material.

Abstract: An improved electrostatic powder painting apparatus is described herein, in which in the vicinity of a discharge electrode disposed in opposition to a body to be painted there is separately provided a driving electrode, for establishment of a driving electric field. The generation of a mono-polar ion current is achieved by said discharge electrode, so that the driving electric field and the ion current density may be controlled quite independently of each other, whereby generation of inverse ionization can be prevented perfectly, while a maximum amount of electric charge can be given to paint powders and a maximum driving force is acted upon said paint powders.