Apparatus and method for dissipating and discharging electrostatic charges

Claim 2

Apparatus adapted for dissipating and discharging electrostatic charge accumulated on an appliance, comprising: an enclosure having an inner surface and an outer surface and formed of an insulating material; a conductive foam body positioned in said enclosure; magnet means in said enclosure and in contact with said foam mass for producing a loop-shaped magnetic field throughout the foam body; a contact structure electrically connected to said foam body; a ground wire electrically connected to said foam body at a point spaced from said contact structure and adapted to electrically connect said foam body to an electrical ground; and a contact probe electrically connected to said contact structure and adapted to be electrically connected to said appliance whereby accumulated electrostatic charge on the appliance may be passed through the foam body to the ground potential.

Claim 3

Apparatus according to claim 1 wherein said foam body has a volume resistivity of approximately 10 4 to 10 7 ohms per square and a surface resistivity of approximately 10 3 to 10 5 ohms per square.

Claim 4

Apparatus according to claim 1 wherein said magnet means includes a plurality of permanent magnets embedded in said foam body.

Claim 5

Apparatus according to claim 3 wherein said magnets are oriented along the perimeter of a reference loop generally in the shape of a rectangle having dimensions smaller than said foam body.

Claim 6

Apparatus according to claim 4 wherein said foam body is generally in the shape of a rectangular prism, said enclosure being in the general shape of a rectangular housing having a top wall, a bottom wall, a pair of elongated side walls and a pair of end walls, said foam body being spaced from each of said side walls.

Claim 7

Apparatus according to claim 4 wherein said magnets are ellipsoid in shape and arranged with respect to one another whereby each magnet's north pole is facing an adjacent magnet's south pole.

Claim 8

Apparatus according to claim 6 wherein there are four magnets, each of said magnets being aligned along a respective side of said reference loop.

Claim 9

Apparatus according to claim 6 wherein said ground wire includes a ground contact embedded in said foam body at a location between the respective north and south poles of an adjacent pair of magnets.

Claim 10

Apparatus according to claim 8 wherein said ground contact is located in a region of maximum magnetic flux density between said adjacent pair of magnets.

Claim 11

Apparatus according to claim 9 wherein said contact structure and said ground contact are positioned at opposite end portions of said foam body.

Claim 12

Apparatus according to claim 1 wherein a portion of the inner surface of said enclosure is coated with a conductive layer to define a conductive shell around the perimeter of said foam body.

Claim 13

Apparatus according to claim 11 wherein said shell is a metal layer formed on the inner side wall of said enclosure.

Claim 14

Apparatus according to claim 1 wherein said probe includes a pick-up head electrically connected to a lead wire electrically connected to said contact structure, said pick-up head including a pad of conductive foam having a raised nub and a layer of non-conductive foam secured to said pad and surrounding said nub, said layer having an exposed face provided with an adhesive material whereby said probe may be adhered to said appliance with said nub in electrical communication therewith.

Claim 15

Apparatus according to claim 13 wherein said lead wire is releaseably secureable to said contact structure.

Claim 16

Apparatus according to claim 13 wherein said pad is constructed of cross-linked conductive foam, said nub having a contact surface laminated with a carbon that is heat treated to form a stable carbon layer.

Claim 17

Apparatus according to claim 15, wherein said pad has a volume resistivity and a surface resistivity both with a range of 10 5 to 10 7 ohms per square.

Claim 18

Apparatus adapted for dissipating and discharging electrostatic charge accumulated on an appliance, comprising: a hollow enclosure having an inner surface and an outer surface and formed of an insulating material; a first foam pad defined by a first plate-like mass of open celled conductive foam having a first mounting face, and a second foam pad defined by a second plate-like mass of open celled conductive foam having a second mounting face, said first and second foam pads positionable together with said first and second mounting faces abutting one another to define a foam body mounted in said enclosure; a first pair of elongated first magnets secured to said first foam pad on an end portion thereof in generally perpendicular relation to one another with one of said first magnets mounted on said first mounting face and the other of said first magnets embedded in said first foam pad with a portion protruding out of said first mounting face; a second pair of elongated second magnets secured to said second foam pad on an end portion thereof in generally perpendicular relation to one another with one of said second magnets mounted on said second mounting face and the other of said second magnets embedded in said second foam pad with a portion protruding out of said second mounting face; said first and second foam pads being positioned together so that said first magnet pair and said second magnet pair are at opposite end portions of said foam body when said foam body is mounted in said enclosure, said magnets being positined along the perimeter of a generally rectangular loop and oriented in said foam body such that each magnet's north pole is facing an adjacent magnet's south pole, said first magnet pair operative to mechanically depress the second foam pad and said second magnet pair operative to depress the first foam pad; an input contact structure at one end portion of said foam body adjacent one of said first and second magnet pairs and a ground contact structure at the other end portion of said foam body adjacent the other of said first and second magnet pairs; a ground lead connectable to said ground contact and operative to allow electrical grounding of said foam body; and a contact probe having a contact lead electrically connectable to said input contact structure and a pick-up head adapted to be secured to said appliance in electrical communication therewith whereby electrostatic charge may be passed from said appliance to said foam body, dissipated through said foam body and discharged to ground potential.

Claim 19

Apparatus adapted for dissipating and discharging electrostatic charge accumulated on an appliance, comprising: a hollow enclosure having an inner surface and an outer surface and formed of an insulating material; a first foam pad defined by a first plate-like mass of open celled conductive foam having a first mounting face, and a second foam pad defined by a second plate-like mass of open celled conductive foam having a second mounting face, said first and second foam pads positionable together with said first and second mounting faces abutting one another to define a foam body mounted in said enclosure; a first pair of elongated first magnets secured to said first foam pad on an end portion thereof in generally perpendicular relation to one another with one of said first magnets mounted on said first mounting face and the other of said first magnets embedded in said first foam pad with a portion protruding out of said first mounting face; a second pair of elongated second magnets secured to said second foam pad on an end portion thereof in generally perpendicular relation to one another with one of said second magnets mounted on said second mounting face and the other of said second magnets embedded in said second foam pad with a portion protruding out of said second mounting face; said first and second foam pads being positioned together so that said first magnet pair and said second magnet pair are at opposite end portions of said foam body when said foam body is mounted in said enclosure, said magnets being positined along the perimeter of a generally rectangular loop and oriented in said foam body such that each magnet's north pole is facing an adjacent magnet's south pole, said first magnet pair operative to mechanically depress the second foam pad and said second magnet pair operative to depress the first foam pad; an input contact structure at one end portion of said foam body adjacent one of said first and second magnet pairs and a ground contact structure at the other end portion of said foam body adjacent the other of said first and second magnet pairs; a ground lead connectable to said ground contact and operative to allow electrical grounding of said foam body; and a contact probe having a contact lead electrically connectable to said input contact structure and a pick-up head adapted to be secured to said appliance in electrical communication therewith whereby electrostatic charge may be passed from said appliance to said foam body, dissipated through said foam body and discharged to ground potential.

Claim 20

Apparatus according to claim 17 wherein said foam body has a volume resistivity within a range of 10 4 and 10 7 ohms per square and a surface resistivity within a range of 10 3 to 10 5 ohms per square.

Claim 21

Apparatus according to claim 17 wherein said ground contact structure is located between one of said first and second magnet pairs.

Claim 22

Apparatus according to claim 17 wherein said magnets have a strength generally within a range of 100 to 250 gauss.

Claim 23

Apparatus according to claim 17 including an annular conductive shell around the perimeter of said foam body.

Claim 24

Apparatus according to claim 21 wherein said shell is defined by a metallic layer formed on the inner surface of the enclosure.

Claim 25

Apparatus according to claim 17 wherein said probe includes a pick-up head formed as a disk of a conductive foam having a volume resistivity and a surface resistivity within a range of 10 5 to 10 7 ohms per square, said disk including an upstanding nub and said pick-up head having an insulating annulus surrounding said nub.

Claim 28

The method of claim 24 wherein said magnetic field has a strength of approximately 75 to 180 gauss.

Claim 29

The method of claim 24 wherein said foam body has a conductive shell around its perimeter.

Claim 30

The method of claim 24 wherein said ground lead is embedded in the foam body at a region of high magnetic flux density.