Electrostatic conveyor

Claim 2

A conveyor for articles comprising: a support bed having a bed surface; a conveyor assembly comprising at least one conveyor member supported for movement on a path of travel across at least a portion of said bed surface; said conveyor member having a first surface oriented toward said bed and a second obverse article transport surface facing away from the bed; and, charge means for establishing a first charge level between said bed and said first surface and a second charge level between said second surface and an article thereon, said first and second charge levels being unequal and producing an electrostatic force urging said article toward said bed and into frictional engagement with said conveyor member to cause said conveyor member to advance an article across said bed.

Claim 3

A conveyor as claimed in claim 1 wherein said charge means is comprised of an electrostatic generator formed by said at least one conveyor member and a nonconductive charging member interposed between and contacting said bed surface and said conveyor member, said conveyor member and said nonconductive charging member movable relative to each other and being triboelectrically different.

Claim 4

A conveyor as claimed in claim 2 wherein said conveyor member comprises a flat belt member having a low resistance to electric current flow transversely to the plane of said belt as compared to the electrical resistance of the belt in its plane.

Claim 5

A conveyor for articles comprising: a support bed having a bed surface; a conveyor assembly comprising at least one conveyor member comprising a flat belt supported for movement on a path of travel across at least a portion of said bed surface; said conveyor member having a first surface oriented toward said bed and an obverse article transport surface facing away from the bed; and, charge means for establishing a charge across said article transport surface and said bed whereby as article placed on said article transport surface substantially assumes the charge level of said article transpoRt surface and an electrostatic force urges said article toward said bed and into frictional engagement with said conveyor member to cause said conveyor member to advance an article across said bed; said charge means comprising an electrostatic generator formed by said at least one conveyor member and a nonconductive charging member interposed between said bed surface and said conveyor member, said charging member contacting said bed surface and defining a surface engageable with said belt; said conveyor member and said nonconductive charging member movable relative to each other and said charging member surface formed by a material which is triboelectrically negative with respect to the belt and has a low surface energy whereby electrons are deposited on said charging member surface by said belt and said charging member surface resists adhesion of foreign matter.

Claim 6

A conveyor for articles comprising: a support bed having a bed surface; a conveyor assembly comprising at least one conveyor member comprising a flat belt supported for movement on a path of travel across at least a portion of said bed surface; said conveyor member having a first surface oriented toward said bed and an obverse article transport surface facing away from the bed; and, charge means for establishing a charge across said article transport surface and said bed whereby as article placed on said article transport surface substantially assumes the charge level of said article transpoRt surface and an electrostatic force urges said article toward said bed and into frictional engagement with said conveyor member to cause said conveyor member to advance an article across said bed; said charge means comprising an electrostatic generator formed by said at least one conveyor member and a nonconductive charging member interposed between said bed surface and said conveyor member, said charging member contacting said bed surface and defining a surface engageable with said belt; said conveyor member and said nonconductive charging member movable relative to each other and said charging member surface formed by a material which is triboelectrically negative with respect to the belt and has a low surface energy whereby electrons are deposited on said charging member surface by said belt and said charging member surface resists adhesion of foreign matter.

Claim 7

A conveyor as claimed in claim 4 wherein said belt member is comprised of a woven fibrous material which is about neutral on the triboelectric scale.

Claim 8

A conveyor as claimed in claim 2 wherein said bed surface is electrically grounded whereby an electrostatic charge is created across said charging member and said bed surface.

Claim 9

A conveyor for articles comprising: a support bed having a bed surface; a conveyor assembly comprising at least one conveyor member comprising a flat endless belt supported for movement on a path of travel across at least a portion of said bed surface; said conveyor member having a first surface oriented toward said bed and an obverse article transport surface facing away from the bed; and, charge means for establishing a charge across said article transport surface and said bed whereby an article placed on said article transport surface substantially assumes the charge level of said article transport surface and an electrostatic force urges said article toward said bed and into frictional engagement with said conveyor member to cause said conveyor member to advance an article across said bed; said charge means comprising an electrostatic generator formed by said at least one conveyor member and a nonconductive charging member interposed between and contacting said bed surface and said conveyor member, said conveyor member and said nonconductive charging member movable relative to each other and being triboelectrically different; said belt having a low resistance to electric current flow through its thickness as compared to its electrical resistance in its plane and effective to conduct current to an article on said article transport surface from said charging member whereby an article is charged relative to said bed surface and electrostatically attracted to said bed surface.

Claim 10

A conveyor for articles comprising: a support bed having a bed surface; a conveyor assembly comprising at least one conveyor member comprising a flat endless belt supported for movement on a path of travel across at least a portion of said bed surface; said conveyor member having a first surface oriented toward said bed and an obverse article transport surface facing away from the bed; and, charge means for establishing a charge across said article transport surface and said bed whereby an article placed on said article transport surface substantially assumes the charge level of said article transport surface and an electrostatic force urges said article toward said bed and into frictional engagement with said conveyor member to cause said conveyor member to advance an article across said bed; said charge means comprising an electrostatic generator formed by said at least one conveyor member and a nonconductive charging member interposed between and contacting said bed surface and said conveyor member, said conveyor member and said nonconductive charging member movable relative to each other and being triboelectrically different; said belt having a low resistance to electric current flow through its thickness as compared to its electrical resistance in its plane and effective to conduct current to an article on said article transport surface from said charging member whereby an article is charged relative to said bed surface and electrostatically attracted to said bed surface.

Claim 11

An electrostatic conveyor apparatus for sheet or film-like material comprising: an electrically grounded conductive support member; a conveyor comprising a plurality of coextending generally parallel endless belts extending along said support member at spaced apart locations; drive means for moving said belts relative to said support member; a plurality of coextending generally parallel charging members attached to said support member and extending along said support member at spaced apart locations, each belt overlying and coextending with a respective one of said charging members whereby each belt slidingly contacts its associated charging member when said belt moves along said support member; each of said belts comprised of material having a high electrical resistance parallel to said charging member and a relatively low resistance transverse to said charging member; and, each of said charging members being triboelectrically different from its associated belt.

Claim 12

An electrostatic conveyor apparatus for sheet or film-like material comprising: an electrically grounded conductive support member; a conveyor comprising a plurality of coextending generally parallel endless belts extending along said support member at spaced apart locations; drive means for moving said belts relative to said support member; a plurality of coextending generally parallel charging members attached to said support member and extending along said support member at spaced apart locations, each belt overlying and coextending with a respective one of said charging members whereby each belt slidingly contacts its associated charging member when said belt moves along said support member; each of said belts comprised of material having a high electrical resistance parallel to said charging member and a relatively low resistance transverse to said charging member; and, each of said charging members being triboelectrically different from its associated belt.

Claim 13

Apparatus as claimed in claim 8 wherein said belts and said charging members are no less than about one-half inch wide, and further including structure providing a dielectric material between adjacent belts, said dielectric material interposed between adjacent belts, said dielectRic material interposed between conveyed material bridging said belts and said support member.

Claim 14

Apparatus as claimed in claim 9 wherein said structure includes a plurality of recesses formed in said support member between said belts, said recesses defining a space between conveyed material on said belts and said support member, said dielectric material comprising air in said space.

Claim 15

Apparatus as claimed in claim 8 wherein said belts are formed from a woven fabric material having a high electrical resistivity and said charging members are defined by thin strips of material characterized by having an extremely high electrical resistivity and being triboelectrically negative with respect to the belt material.

Claim 16

Apparatus as claimed in claim 11 wherein said charging members are composed at least principally of polytetrafluoroethylene.

Claim 17

Apparatus as claimed in claim 8 and further including heater means for heating said belts to a predetermined temperature whereby to limit the moisture content of said belts and control their electrical resistivity.

Claim 20

A method as claimed in claim 14 wherein electrically insulating the belt from the bed comprises interposing a nonconductive charging member between said belt and said bed and establishing a charge across the article and bed comprises engaging the belt with a surface of the charging member as the belt moves relative to the charging member and creating a charge across the charging member surface and the bed.