Electrostatic spraying device

• US 5,927,618 A
• Filed: 02/06/1996
• Issued: 07/27/1999
• Est. Priority Date: 09/02/1993
• Status: Expired due to Fees

• Current Assignee: The Procter & Gamble Company
• Original Assignee: The Procter & Gamble Company
• Inventors: Noakes, Timothy James, Green, Michael Leslie, Jefferies, Andrew, Prendergast, Maurice Joseph
• Primary Examiner(s): Kashnikow, Andres
• Assistant Examiner(s): DOUGLAS, LISA ANN
• Application Number:
  US08/592,418
• Time in Patent Office: 1,267 Days
• Field of Search: 239/690, 239/690.1, 239/3, 239/34, 239/44, 239/145, 239/326, 239/704, 239/708, 239/49
• US Class Current: 239/690.1
• CPC Class Codes: B05B 5/0255 spraying and depositing by electrostatic forces only

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.

Claims

1. A cartridge for use in electrostatic spraying comprising a container for liquid to be electrostatically sprayed, a capillary feed structure having one end thereof located within the container and an opposite end thereof forming or associated with a spraying tip of the device in use, and means within the container for controlling liquid level within the container, in which the base of the cartridge is of inwardly concave configuration with the lowest point located beneath the capillary structure.

2. In or for an electrostatic spraying device, a cartridge comprising a container containing a liquid to be sprayed, said liquid having a bulk resistivity within the range from about 10⁴ to about 5×

10⁷ ohm cm and a capillary tube of non-metallic material having one end thereof located within the container and an opposite end thereof forming a spraying tip of the device in use, said opposite end of the capillary tube being of asymmetric configuration such that spraying of liquid from one side of the tube is favoured, said capillary tube having a first capillary portion extending from one end followed by a second capillary portion terminating at or adjacent the opposite end of the capillary tube, the second portion having a bore of smaller cross-sectional area than that of the first portion.

3. An electrostatic spraying device comprising a spraying tip, a reservoir for containing liquid to be supplied to the spraying tip, a capillary tube having one end thereof located within the reservoir and the other end thereof forming the spraying tip, and means for applying high voltage to the liquid so that liquid discharged from the spraying tip is atomised under the influence of the electric field, the capillary tube, the reservoir and the voltage applying means being embodied in a housing which is adapted for stable location in a position in which the capillary tube points upwardly and feed of liquid from the reservoir to the spraying tip is provided by capillary action, characterised in that the capillary tube comprises a first capillary portion extending from said one end followed by a second capillary portion terminating at or adjacent said opposite end of the capillary tube, the second portion having a bore of smaller cross-sectional area than that of the first portion.

4. A cartridge for use in an electrostatic spraying device comprising a container containing a liquid to be electrostatically sprayed, a capillary tube extending from a location immediately adjacent one end of the container, through an opening at the opposite end of the container and terminating in a spraying tip to which said liquid is transported by capillary action, the capillary tube comprising a first capillary portion extending from said one end followed by a second capillary portion at or adjacent said spraying tip, the second portion having a bore of smaller cross-sectional area than that of the first portion.

5. A cartridge or device as claimed in claim 4 in which the first portion of the capillary tube has an outside diameter of 400 to 800 microns.

6. A cartridge or device as claimed in any one of claims 4 in which the first portion of the capillary tube has an inside diameter of 200 to 300 microns.

7. A cartridge or device as claimed in claim 4 in which the second capillary portion has an outside diameter of 200 to 400 microns.

8. A cartridge or device as claimed in claim 4 in which the second capillary portion has an inside diameter of 50 to 100 microns.

9. A cartridge or device as claimed in claim 4 in which the capillary structure comprises a capillary tube the wall thickness of which at the tip is no greater than 400 microns.

10. A cartridge or device as claimed in claim 9 in which the wall thickness of which at the tip is no greater than about 250-300 microns.

11. A cartridge or device as claimed in claim 9 in which the wall thickness of the tube at the tip is no greater than about 100-150 microns.