Abstract: An electronic arrangement for generating, from a reference value proportional to the rate of movement, for example, from an a.c. voltage generated by a means of a tachometer generator, two a.c. voltages which can be shifted in phase with respect to each other by a constant frequency-independent amount. An arrangement is provided in which a variable input a.c. voltage is changed to a triangular voltage of constant amplitude and proportional in frequency to the a.c. voltage. There is a first square-wave voltage derived from the triangular voltage and the triangular voltage is inverted. The inverted and uninverted triangular voltage are each applied to one input of two comparators and a manually variable d.c. voltage is applied to the second input of each comparator. The d.c. voltage is manually variable between the maximum and minimum amplitudes of the triangular voltage.

Abstract: An apparatus for electrostatically coating conductive articles with powder. A mixture of powder and air is delivered through a passage of uniform cross-section and a short section of rotating tube to a rotating bell of nonconductive material having a surface angle with the axis of 50.degree. to 90.degree.. The powder is directed from a nozzle over the bell surface and the entraining air is dissipated laterally. The powder is discharged from the bell into an electrostatic field where the particles acquire a charge and are attracted to and deposited on the grounded articles. A pneumatic jet pump for entraining the powder particle in an air stream has a nozzle and venturi so related that the expanding air from the nozzle blends with the expanding portion of the venturi.

Abstract: Powder cloud development apparatus for developing latent electrostatic images on an insulating member, such as a photoconductive layer, wherein a cloud of charged developer particles is introduced into the development chamber through a first port in the chamber wall and air is introduced through a second port in the chamber wall opposite said first port. A baffle is positioned above the ports and below the surface of the insulator, the baffle extending between the opposed walls. A development electrode comprising a series of parallel wires, electrically biased in the development area, is connected at each end to a continuous loop drive mechanism, the upper plane of the grid wire being closely spaced from the insulator surface. The wire to wire spacing with respect to wire diameter is sufficiently large to allow the passage of toner therethrough.

Abstract: A selective corona charger is disclosed for imparting an electrical charge to liquid droplets in a spray, comprising conductor means, means for defining a grid, a means for moving the conductor means in the grid, scraper means for cleaning excess spray off the conductor means, and a power source for imparting a high voltage to the conductor means. The droplet charger is placed between the source of the spray and the article being sprayed. In operation, the article being sprayed is held at a low electrical potential, preferably ground. The spray is directed toward the article being sprayed and as the spray droplets pass through the corona charger they receive a high electrical potential or charge from the corona charger. The droplets are thereafter electrically attracted to the article being sprayed.

Abstract: A powder feeder pick-up tube having a central powder delivery tube receiving powder entrained in a propellant gas, an outer concentric tube delivering propellant gas to the powder delivery tube and evenly entraining powder in the gas as the powder enters the powder delivery tube. The propellant delivery tube has an inwardly curving end that forms a gap with the open end of the powder delivery tube, and the geometry of the curving end and the size of the gap are factors determining the operational characteristics of the pick-up tube. Variations on the basic pick-up tube include a concentric fluidizing tube surrounding the propellent delivery tube and locally fluidizing powder around the opening of the powder pick-up tube. The shape of the fluidizing orifice at the outlet of the fluidizing tube may be modified to alter its fluidizing characteristics. The tube is immersed in a hopper of powder when operating and the entire hopper may be fluidized and vibrated to assist the operation of the pick-up tube.

Abstract: An electrostatic spray coating system for spraying conductive coatings such as water base paint has a grounded paint supply sub-system which intermittently supplies conductive coating material to a high voltage sub-system across an air space. An interlock system prevents conductive coating material from being transferred from the grounded sub-system to the high voltage sub-system while high voltage electrical potentials being applied to the high voltage coating material sub-system.

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.

Abstract: An improved electrostatic spray charging device for spray guns is disclosed. The device comprises an adapter formed from a dielectric material in the shape of a generally cylindrical tube adapted at one end to be secured to the end of a conventional spray gun and constructed at the second end to provide an inductive charging field for materials discharged by the spray gun. The second end of the adapter is formed, in the preferred embodiment, into two diametrically opposed lobes, each of which carries on its interior surface at least one charging plate to which a d.c. voltage on the order of 10-20 KV is applied. The exterior surface of each lobe carries an electrically grounded electrode which preferably is annular in shape to provide an electric field configuration that prevents accumulation of charged spray particles on the exterior surfaces of the adapter.

Abstract: An improved apparatus is disclosed for controlling the build on wire moving in a vertical electrostatic fluidized bed which has opposing vacuum chambers for controlling the position of the cloud of powder in the bed. Each vacuum chamber is provided with an opening to the atmosphere and with means for controlling the size of the opening. By "spoiling" the vacuum in this manner the position of the cloud can be more precisely controlled thereby producing a more uniform coating on the wire.

Abstract: An apparatus for lubricating the internal wall of moulds for blanks comprises a corona charger for charging electrically the lubricant which is then injected into the mould. This latter is maintained at an electric potential such as to attract the lubricant and cause it to be deposited on the inside walls of the mould.

Abstract: A face-silent discharge electrode which includes plural parallel electrode bars separated from each other at a distance and arranged in a face is disposed to confront a substrate. A powder coating material is supplied in the space between said electrode and said substrate. An AC voltage is impressed on the electrode bars adjacent each other to generate a silent electric discharge over the entire surface of said face-silent discharge electrode. Concurrently, a DC voltage is impressed between the electrode bars and the substrate so that the powder coating material may adhere to a surface of the substrate to form a layer of uniform thickness.

Abstract: A powder cloud development apparatus is provided for developing latent electrostatic images on the surface of an insulating member, normally a photoconductive layer, employing a powder cloud development system. The development apparatus is operable in either a positive or negative mode and includes a development electrode comprising a plurality of spaced substantially parallel wires, a gap, or open section, which is formed between selected groups of these wires, the wires being connected at each end to a continuous loop drive mechanism. The parallel wires therefore or the gap may either be presented in operable relationship to the surface of the insulating member in order to provide either electroded or non-electroded development in the negative and positive modes respectively.

Abstract: An electrostatic spray apparatus and method for spraying highly electrically conductive water-based coating material in which safety hazards are minimized.