Abstract: An electrostatic spraying device for use in spraying inter alia personal care and personal hygiene products comprises an outlet (94) from which the product issues in the form of an electrostatically charged spray and a control member (60, 60a) for attenuating the potential gradient in the vicinity of the outlet (94) to such an extent that spraying is suppressed until the device is brought to within a predetermined distance from a site to be spayed.

Abstract: An electrostatic spraying device comprising a nozzle, means for establishing a column of material to be sprayed within a passage leading to the nozzle outlet such that the leading surface of the column is spaced from the nozzle outlet, means for pneumatically ejecting said column or part thereof from the nozzle and means for applying high voltage to the material so that the spray formed by breaking up of the column on ejection from the nozzle are electrically charged. The column of material in the passage is preferably a discreet slug having a leading surface spaced from the nozzle outlet and a trailing surface to which air, gas or vapor under pressure can be applied to effect ejection of the slug from the nozzle.

Abstract: An electrostatic spraying device is disclosed which is suitable for, but not limited to, dispensing an electrostatically sprayable substance for nasal or oral inhalation. Electrical charge is imparted to the spray particles by applying a high voltage to the substance prior to break up into a spray. In one embodiment, the device includes a nozzle portion for registry with the nasal or oral cavity and defines a passageway through which, in use, air can be drawn by inhalation on the part of the user. The substance to be sprayed passes into the passageway so that, with the assistance of user-induced air flow through the passageway, the resulting spray passes into the oral or nasal cavity.

Abstract: The present invention provides an electrostatic spraying device which includes a primary charge return path between the device and the target to be sprayed and circuitry for warning the operator of potentially hazardous spraying conditions. More particularly, the present invention includes circuitry for warning the operator of conditions wherein the primary charge path is inadequate and other conditions in which the return of spray current via the primary charge path is affected.

Abstract: An electrostatic spraying device is disclosed having a container (16) for the liquid to be sprayed and a capillary structure (22) extending into the container. To maintain a substantially constant liquid level at the location where liquid is drawn into the capillary structure, the container is partitioned into two chambers, one (68) of which is isolated from atmosphere and the other (66) of which is in communication with atmosphere. The capillary structure (22) extends through one chamber and the arrangement is such that the liquid level at the location where the capillary structure communicates with the liquid is maintained substantially constant over a wide range of variation of the liquid level within the other chamber. The upper end of the capillary structure may be provided with an oblique end face (50; 70, 72) to facilitate dispersal of the spray into the surroundings.

Abstract: An electrostatic spraying device for use in spraying liquids having resistivities of the order of 5.times.10.sup.6 ohm.multidot.cm and viscosities of the order of 1 Poise at a spraying rate up to at least 4 cc/min (especially paint formulations) is provided with an annular shroud (112) of semi-insulating material (e.g. bulk resistivity of the order of 10.sup.11 to 10.sup.12 ohm.multidot.cm) which is electrically connected to a high voltage generator (126) for supplying high voltage to liquid emerging at the outlet of the nozzle (114). In this way, a voltage is established on the annular electrode (126) which is of the same polarity, and substantially the same magnitude, as the voltage applied to the liquid thereby modifying the potential gradient in the immediate vicinity of the nozzle outlet so as to allow the use of the high voltage needed to effect efficient spraying of liquids having the specified resistivity and viscosity at flow rates up to at least 4 cc/min.

Abstract: A novel semiconductor switching device for use in high voltage applications (typically ranging from 5 kV up to about 50 kV) makes use of the well-known effect of reverse conduction in silicon diodes when exposed to light. Hitherto, photodiodes have been commercial available for relatively low voltage applications. The device disclosed herein is implemented by a high voltage diode having a series of semiconductor junctions and a light emitting diode operable to irradiate the junctions to render the high voltage diode conducting in the reverse bias direction. The switching device finds application in electrostatic spraying devices where the current demands are relatively small, eg up to about 2 .mu.A.