US3680779A — Method and apparatus for electrostatic spraying

Claim 1

Independent Claim 157 words

In an electrostatic sprayer for depositing a material on an article spaced from and moving relative to said sprayer along a predetermined path, said sprayer including a metering means for supplying particles of said material, a conductor means spaced at a predetermined distance from said metering means intermediate said metering means and said path, and first circuit means connected to said metering means and said conductor means for establishing a primary a.c. electric field therebetween whereby said particles are accelerated away from said metering means; the combination of at least one electrode means spaced at a distance from said metering means greater than said predetermined distance, and second circuit means connected between said metering means and said electrode means for establishing an auxiliary electric field therebetween, said electrode means being positioned relative to said metering means and said path such that said auxiliary field further controls movement of said particles between said metering means and said article.

Claim 2

Dependent Claim 157 words

In an electrostatic sprayer for depositing a material on an article spaced from and moving relative to said sprayer along a predetermined path, said sprayer including a metering means for supplying particles of said material, a conductor means spaced at a predetermined distance from said metering means intermediate said metering means and said path, and first circuit means connected to said metering means and said conductor means for establishing a primary a.c. electric field therebetween whereby said particles are accelerated away from said metering means; the combination of at least one electrode means spaced at a distance from said metering means greater than said predetermined distance, and second circuit means connected between said metering means and said electrode means for establishing an auxiliary electric field therebetween, said electrode means being positioned relative to said metering means and said path such that said auxiliary field further controls movement of said particles between said metering means and said article.

Claim 3

Dependent Claim 65 words

The electrostatic sprayer of claim 1 wherein successive articles are moved relative to said sprayer along said path at a predetermined rate, said auxiliary field is a d.c. field, and said primary a.c. field has a frequency selected to synchronize the movement of said particles from said metering means to said path with the rate at which said articles are moved relative to said sprayer.

Claim 4

Dependent Claim 70 words

The electrostatic sprayer of claim 1 wherein successive articles are moved relative to said sprayer along said path at a predetermined rate, said auxiliary electric field is an a.c. field, and said primary and auxiliary a.c. fields have relative frequencies and phases selected to synchronize the movement of said particles from said metering means to said path with the rate at which said articles are moved relative to said sprayer.

Claim 5

Dependent Claim 43 words

The electrostatic sprayer of claim 1 wherein said path is disposed between said metering means and said electrode means, whereby the auxiliary field constrains said particles after they are accelerated out of said primary field and until they are deposited on said article.

Claim 6

Dependent Claim 69 words

The electrostatic sprayer of claim 4 wherein successive articles aRe moved relative to said sprayer along said path at a predetermined rate, the auxiliary field is an a.c. field, and the primary and auxiliary fields have relative frequencies and phases that are selected to cause said particles to move toward and away from said metering means in timed synchronism with the movement of said articles relative to said sprayer.

Claim 7

Dependent Claim 34 words

The electrostatic sprayer of claim 1 wherein said path is oriented relative to said sprayer means such that any gravitational force acting on said particles tends to deflect such particles away from said path.

Claim 8

Dependent Claim 50 words

The electrostatic sprayer of claim 1 wherein said electrode means is positioned between said metering means and said path, whereby the auxiliary electric field constrains said particles after they are accelerated out of said primary field for only a part of the distance between said metering means and said path.

Claim 9

Dependent Claim 67 words

The electrostatic sprayer of claim 7 wherein successive articles are moved relative to said sprayer along said path at a predetermined rate, the auxiliary electric field is an a.c. field, and said primary and auxiliary a.c. fields have relative frequencies and phases such that said particles are moved toward and away from said path in timed synchronism with the movement of said articles relative to said sprayer.

Claim 10

Dependent Claim 55 words

The electrostatic sprayer of claim 7 wherein the auxiliary electric field created is an a.c. field, and said primary and auxiliary a.c. fields have relative frequencies and phases such that said particles are accelerated toward said path by said auxiliary field after passing through the distance between said metering means and said first electrode means.

Claim 11

Dependent Claim 29 words

The electrostatic sprayer of claim 4 wherein said metering means and said electrode means are referenced to respective potentials which are of opposite polarities relative to a ground potential.

Claim 12

Dependent Claim 45 words

The electrostatic sprayer of claim 10 wherein said electrode means is a first electrode means, and further including a second electrode means which is referenced to a potential which is intermediate the potentials to which said metering means and said first electrode means are referenced.

Claim 13

Dependent Claim 62 words

The electrostatic sprayer of claim 4 wherein said electrode means is a first electrode means, and further including a second electrode means disposed between said metering means and said path, whereby a tertiary electric field of increased uniformity relative to said auxiliary field is established to provide an increased uniformity of distribution of said particles relative to the article to be coated.

Claim 14

Dependent Claim 43 words

The electrostatic sprayer of claim 12 further including a single a.c. voltage source which is connected by said first and second circuit means to said metering means and said first and second electrode means for establishing said primary, auxiliary, and tertiary electric field.

Claim 15

Dependent Claim 62 words

The electrostatic sprayer of claim 1 wherein said article is a dielectric, and further including a means positioned at an input side of said sprayer for depositing a predetermined charge on said article whereby said auxiliary electric field is established between said metering means and said article, and a means positioned at an output side of said sprayer for discharging said article.

Claim 16

Dependent Claim 18 words

The electrostatic sprayer of claim 1 wherein one of said metering means and said conductor means is insulated.

Claim 17

Independent Claim 78 words

A method for electrostatically spraying a powder coating on an article comprising the steps of: continuously supplying particles of powder, exposing said particles in a predetermined area at a distance from said article to an a.c. primary electric field so that successive groups of particles are oppositely charged relative to a predetermined reference potential for said primary field, and creating an auxiliary electric field to control movement of said particles for at least a portion of said distance.

Claim 18

Independent Claim 78 words

A method for electrostatically spraying a powder coating on an article comprising the steps of: continuously supplying particles of powder, exposing said particles in a predetermined area at a distance from said article to an a.c. primary electric field so that successive groups of particles are oppositely charged relative to a predetermined reference potential for said primary field, and creating an auxiliary electric field to control movement of said particles for at least a portion of said distance.

Claim 19

Dependent Claim 36 words

The method of claim 15 wherein said auxiliary electric field extends for at least the entirety of said distance, wherebY it controls movement of said particles from the area of said primary field to said article.

Claim 20

Dependent Claim 32 words

The method of claim 16 wherein said auxiliary electric field asserts a force on said particles in a direction that is angularly displaced from the direction of any gravitational forces acting thereon.

Claim 21

Dependent Claim 72 words

The method of claim 15 further including the step of moving successive articles to be coated past a predetermined spraying station at a predetermined rate; and wherein said auxiliary electric field is an a.c. field, and said primary and auxiliary fields have relative frequencies and phases that are selected to cause said powder particles to move toward and away from said station in timed synchronism with the movement of successive articles thereby.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1975-08-01	1976-01-31	1976-08-01	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1979-08-01	1980-01-31	1980-08-01	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1983-08-01	1984-01-31	1984-08-01	$7700.00	Window Closed / Lapsed

Method and apparatus for electrostatic spraying

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