Method and apparatus for high transfer efficiency electrostatic spray

1 . A method of spraying an aerosol spray, comprising:

providing a grounded nozzle and an electrode separated by a predetermined distance;

placing the electrode at a high electrical potential relative to the nozzle, thereby creating an electric field between the nozzle and the electrode;

ejecting a liquid from the nozzle towards the electrode to atomize the ejected liquid into aerosol droplets or particles, so that in the applied electric field between the nozzle and the electrode the aerosol droplets or particles obtain an induced electric charge; and

forming a directed spray of aerosol droplets or particles having a desired shape and with sufficient momentum and electric charge so that the directed spray of aerosol droplets or particles is deposited on a target.

2 . The method of claim 1 , further comprising

providing a cover around the nozzle and the electrode, the cover having an opening that allows a directed spray to exit, wherein the cover comprises a nonconductive material; and

grounding the cover by applying a conductive or resistive coating to at least a portion thereof and connecting the conducting or resistive coating to ground.

3 . An airless electrostatic sprayer for spraying aerosol particles, comprising:

at least one electrically conductive, grounded nozzle;

a pressure source to force fluid through the nozzle wherein the exiting fluid forms a stream of aerosol particles or droplets; and

an electrode with high electric potential disposed at a distance from the nozzle and from the stream of aerosol particles or droplets, wherein the electric potential creates an electric field that charges the stream of aerosol particles or droplets;

wherein the electrode is placed sufficiently far from the stream of aerosol particles or droplets so as to induce a charge on the particles or droplets that is of the opposite polarity as the potential on the electrode.

4 . The sprayer of claim 3 further comprising a cover surrounding the nozzle and electrode, wherein the cover is made of a non-conductive material that is at least partially coated with a conductive material such that the conductive material is grounded.

5 . The sprayer of claim 3 wherein the electrode further comprises a plurality of grooves formed therein, wherein the grooves are perpendicular to the stream of aerosol particles or droplets, such that the grooves extend at least partially through the electrode.

6 . The sprayer of claim 3 wherein the pressure source is at least one of a pump and a high-pressure vessel.

7 . The sprayer of claim 3 further comprising a concave insulating cup to which the electrode is attached.

8 . The sprayer of claim 3 further comprising:

a manifold to which the nozzle is mounted; and

a second electrically conductive, grounded nozzle mounted on the manifold.

9 . The sprayer of claim 3 wherein the electrode comprises an annular segment of a cone.

10 . The sprayer of claim 3 wherein the electrode comprises a pair of adjacent flat plates.

11 . An airless electrostatic sprayer for spraying aerosol particles, comprising:

at least one electrically conductive, grounded nozzle;

a pressure source to force fluid through the nozzle wherein the exiting fluid forms a stream of aerosol particles or droplets; and

an electrode with high electric potential disposed at a distance from the nozzle and from the stream of aerosol particles or droplets, wherein the electric potential creates an electric field that charges the stream of aerosol particles or droplets;

wherein the electrode is placed sufficiently close to the stream of aerosol particles or droplets so as to induce a charge on the particles or droplets that is of the same polarity as the potential on the electrode.

12 . The sprayer of claim 11 further comprising a cover surrounding the nozzle and electrode, wherein the cover is made of a non-conductive material that is at least partially coated with a conductive material such that the conductive material is grounded.

13 . The sprayer of claim 11 wherein the electrode further comprises a plurality of grooves formed therein, wherein the grooves are perpendicular to the stream of aerosol particles or droplets, such that the grooves extend at least partially through the electrode.

14 . The sprayer of claim 11 wherein the pressure source is at least one of a pump and a high-pressure vessel.

15 . The sprayer of claim 11 further comprising a concave insulating cup to which the electrode is attached.

16 . The sprayer of claim 11 further comprising:

a manifold to which the nozzle is mounted; and

a second electrically conductive, grounded nozzle mounted on the manifold.

17 . The sprayer of claim 11 wherein the electrode comprises an annular segment of a cone.

18 . The sprayer of claim 11 wherein the electrode comprises a pair of adjacent flat plates.