US4780331A — Method and apparatus for induction charging of po…

Claim 1

Independent Claim 127 words

Apparatus for charging and delivering powder particles comprising: a lower plate, means for vibrating said lower plate, means for continuously delivering powder to said lower plate, a circular top plate spaced above said lower plate, means for rotating said top plate, a direct current high voltage source connected across said two plates to create an electrostatic field between them, a shroud of air of desired cross section surrounding said circular plate, and means for blowing air through said shroud and downwardly past said circular plate, whereby powder particles are charged by repeatedly bouncing on said lower plate until they levitate to said circular plate, said circular plate driving said particles by centrifugal force to its edge and the air emanating from said shroud driving said particles downwardly.

Claim 2

Dependent Claim 127 words

Apparatus for charging and delivering powder particles comprising: a lower plate, means for vibrating said lower plate, means for continuously delivering powder to said lower plate, a circular top plate spaced above said lower plate, means for rotating said top plate, a direct current high voltage source connected across said two plates to create an electrostatic field between them, a shroud of air of desired cross section surrounding said circular plate, and means for blowing air through said shroud and downwardly past said circular plate, whereby powder particles are charged by repeatedly bouncing on said lower plate until they levitate to said circular plate, said circular plate driving said particles by centrifugal force to its edge and the air emanating from said shroud driving said particles downwardly.

Claim 3

Independent Claim 109 words

The method of charging powder particles comprising the steps of: establishing an electric field between upper and lower surfaces, vibrating at least the lower surface, introducing uncharged particles to the vibrating surface, whereby the particles, as they repeatedly contact the lower surface, pick up electrostatic charges solely by electrostatic induction from the surface until the charge is sufficiently great to cause the particles to levitate according to the equation qE≧mg where q is the charge on the particle, E is the applied electric field, m is the mass of the particle and g is the acceleration of gravity, and continuously removing levitating particles from the space between said surfaces.

Claim 4

Independent Claim 109 words

The method of charging powder particles comprising the steps of: establishing an electric field between upper and lower surfaces, vibrating at least the lower surface, introducing uncharged particles to the vibrating surface, whereby the particles, as they repeatedly contact the lower surface, pick up electrostatic charges solely by electrostatic induction from the surface until the charge is sufficiently great to cause the particles to levitate according to the equation qE≧mg where q is the charge on the particle, E is the applied electric field, m is the mass of the particle and g is the acceleration of gravity, and continuously removing levitating particles from the space between said surfaces.

Claim 5

Independent Claim 36 words

The method as in claims 1 wherein the particles are charged at controlled levels up to the limit dictated by electrical breakdown of the surrounding air due to the high electric field of the charged particles.

Claim 6

Independent Claim 20 words

The method as in claims 1 wherein the electric field between said two surfaces is about 100 kV per meter.

Claim 7

Independent Claim 21 words

The method as in claims 1 wherein the frequency of vibration is in the range of frequencies in the audio range.

Claim 8

Independent Claim 62 words

The method of delivering powder particles to a workpiece comprising the steps of: establishing an electric field between upper and lower surfaces, introducing uncharged particles onto said lower surface, vibrating said lower surface to cause said particles to bounce upon it, thereby charging the particles solely by electrostatic induction, conveying those particles whose charge is sufficient to overcome gravity to said workpiece.

Claim 9

Independent Claim 62 words

The method of delivering powder particles to a workpiece comprising the steps of: establishing an electric field between upper and lower surfaces, introducing uncharged particles onto said lower surface, vibrating said lower surface to cause said particles to bounce upon it, thereby charging the particles solely by electrostatic induction, conveying those particles whose charge is sufficient to overcome gravity to said workpiece.

Claim 10

Dependent Claim 13 words

The method as in claim 6 wherein said workpiece forms said upper surface.

Claim 11

Dependent Claim 44 words

The method as in claim 6 wherein said upper surface has an opening through which particles may pass, the method comprising the further step of: passing air over the top of said upper surface to entrain charged particles and deliver them to said workpiece.

Claim 12

Dependent Claim 29 words

The method as in claim 6 further comprising the step of: establishing a second electrostatic field above said lower surface to entrain and guide charged particles toward said workpiece.

Claim 13

Dependent Claim 30 words

The method as in claim 6 further comprising the step of: vibrating said upper surface to dislodge stray particles which contact the upper surface before being delivered to said workpiece.

Claim 14

Dependent Claim 72 words

Apparatus for charging powder particles comprising: a pair of spaced upper and lower surfaces, means for applying a high voltage between said surfaces to establish an electric field therebetween, means for delivering particles continuously to said surface, means for vibrating said lower surface to charge said particles by repeated contact with said lower surface and solely by electrostatic induction, and means for removing levitating particles which are charged sufficiently to overcome gravity.

Claim 15

Dependent Claim 72 words

Apparatus for charging powder particles comprising: a pair of spaced upper and lower surfaces, means for applying a high voltage between said surfaces to establish an electric field therebetween, means for delivering particles continuously to said surface, means for vibrating said lower surface to charge said particles by repeated contact with said lower surface and solely by electrostatic induction, and means for removing levitating particles which are charged sufficiently to overcome gravity.

Claim 16

Dependent Claim 56 words

Apparatus as in claim 11 in which said upper surface is formed by a plate having an opening in it, said plate having a second surface on the opposite side of said plate from said upper surface, said removing means comprising means for passing air across said second surface to entrain particles levitating through said opening.

Claim 17

Dependent Claim 18 words

Apparatus as in claim 11 further comprising means for vibrating said upper surface to dislodge stray particles therefrom.

Claim 18

Dependent Claim 56 words

Apparatus as in claim 11 in which said upper surface has an opening therein, said apparatus further comprising: a plurality of spaced plates above said opening and defining a path for the passage of charged particles, and means for applying an electric field to said plates for transporting and for deflecting charged particles along said path.

Claim 19

Dependent Claim 20 words

Apparatus as in claim 11 in which said upper surface comprises a workpiece to be coated with said powder particles.

Claim 20

Dependent Claim 109 words

Apparatus for charging powder particles comprising: a lower horizontal conductive plate, an upwardly inclined insulating surface connected at its lower edge to said plate, means for vibrating said plate and surface, means for delivering powder to said inclined surface, a frusto-conical upper conductive member having a lower edge forming an opening above said conductive plate, and means for applying a high voltage across said plate and frusto-conical member, means for supporting a workpiece above said opening, whereby powder will be vibrated down to said conductive plate where repeated contact with said plate will charge each powder particle until its total charge is sufficient to levitate it through said opening.

Claim 21

Dependent Claim 109 words

Apparatus for charging powder particles comprising: a lower horizontal conductive plate, an upwardly inclined insulating surface connected at its lower edge to said plate, means for vibrating said plate and surface, means for delivering powder to said inclined surface, a frusto-conical upper conductive member having a lower edge forming an opening above said conductive plate, and means for applying a high voltage across said plate and frusto-conical member, means for supporting a workpiece above said opening, whereby powder will be vibrated down to said conductive plate where repeated contact with said plate will charge each powder particle until its total charge is sufficient to levitate it through said opening.

Claim 22

Dependent Claim 54 words

Apparatus as in claim 16 wherein said voltage-applying means is connected to said workpiece to maintain it at ground potential, to said lower plate to maintain it at a high potential different from ground potential, and to said upper plate to maintain it at a potential between ground and that applied to said workpiece.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1991-10-25	1992-04-25	1992-10-25	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1995-10-25	1996-04-25	1996-10-25	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1999-10-25	2000-04-25	2000-10-25	$7700.00	Window Closed / Lapsed

Method and apparatus for induction charging of powder by contact electrification

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