Developing apparatus

Claim 2

In apparatus for developing a latent electrostatic image retained on the photoconductive surface of a photoelectrostatic recording member, said member having a moisture-sensitive base supporting said surface, the combination comprising: developer means for applying electroscopic powder to the photoconductive surface of said recording member whereby the latent image is converted into a visible form; a source of electrical power; electrode means coupled to said power source and disposed adjacent said base support, said electrode means providing a bias voltage of a predetermined level to said member for repelling the powder from the nonimage areas; and means connected to said electrode means for automatically regulating the operation of said electrode means to maintain said bias voltage at said predetermined level in accordance with the moisture content of the base of said recording member.

Claim 3

The combination as defined in claim 1, wherein said automatic regulating means include conductive monitor means in electrical contact with the base for electrically connecting said base to said electrode means and said source.

Claim 4

The combination as defined in claim 2, wherein said electrode is of the corona-type having at least one discharge wire surrounded partially by a conductive shield and which establishes current through an air dielectric to said member.

Claim 5

The combination as defined in claim 3, wherein said conductive monitor means couple said base between said source and said discharge wire.

Claim 6

The combination as defined in claim 3, wherein said conductive monitor means couple said base in series connection between said shield and ground.

Claim 7

The combination as defined in claim 1, wherein said developer means comprises a magnetic brush made up of magnetic carrier particles and said powder and wherein the polarity of said powder and said bias voltage are the same.

Claim 8

The combination as defined in claim 1, wherein said electrode means is coupled electrically through said base support, whereby due to an increase in the moisture content of said base support, the conductivity thereof increases proportionally, causing a corresponding increase in electrical current through said electrode means thereby to maintain said bias voltage at said predetermined level.

Claim 9

The combination as defined in claim 7, wherein said regulating means further includes resistance means connected in parallel relation with said base support and interposed between said electrode means and said power source.

Claim 10

In an apparatus for developing a latent electrostatic image retained on the photoconductive surface of a photoelectrostatic recording member, said member having a base supporting said surface, said base varying in conductivity in accordance with changes in the humidity of the surrounding atmosphere or the like, the combination comprising: developer means for applying electroscopic powder of a predetermined polarity to the surface of said recording member whereby the latent image is converted into a visible form; a source of electrical power; electrode means coupled to said power source and disposed adjacent said base support, said electrode mEans providing a bias voltage having a polarity the same as that of said electroscopic powder applied to said member for repelling the powder from the nonimage areas of the photoconductive surface of said recording member; and sensor means coupled to said electrode means and the base support of said recording member for automatically regulating the operation of said electrode means to maintain said bias voltage at said predetermined level in accordance with the conductivity of said base support.

Claim 11

In an apparatus for developing a latent electrostatic image retained on the photoconductive surface of a photoelectrostatic recording member, said member having a base supporting said surface, said base varying in conductivity in accordance with changes in the humidity of the surrounding atmosphere or the like, the combination comprising: developer means for applying electroscopic powder of a predetermined polarity to the surface of said recording member whereby the latent image is converted into a visible form; a source of electrical power; electrode means coupled to said power source and disposed adjacent said base support, said electrode mEans providing a bias voltage having a polarity the same as that of said electroscopic powder applied to said member for repelling the powder from the nonimage areas of the photoconductive surface of said recording member; and sensor means coupled to said electrode means and the base support of said recording member for automatically regulating the operation of said electrode means to maintain said bias voltage at said predetermined level in accordance with the conductivity of said base support.

Claim 12

The combination as claimed in claim 9, wherein said sensor means includes a pair of spaced conductors coupled to said base support and connected to said electrode means, said base support completing a circuit between said conductors, whereby a change in conducting of said base support causes a corresponding change in current flow from said power source through said electrode means, thereby to maintain the level of said bias voltage on said member for repelling said electroscopic powder.

Claim 13

In an apparatus for developing a latent electrostatic image retained on the photoconductive surface of a photoelectrostatic recording member, said member having a moisture-sensitive base supporting said surface, the combination comprising: developer means for applying electroscopic powder to the surface whereby the latent image is converted into a visible form; a source of electrical power; a corona-type electrode disposed adjacent said base support providing an electrical current to said member to produce a bias voltage of a predetermined level for repelling the powder from the nonimage areas of said photoconductive surface and including a discharge wire surrounded partially by a conductive shield, said wire being electrically connected to said power source; a roller member mounted for rolling engagement with said recording member along the base support thereof, said roller member including first and second electrically conductive halves insulatively spaced from each other, said first roller half being connected to the conductive shield of said corona electrode and said second roller half being connected to ground potential; and said first and second roller halves being electrically interconnected through said base support, whereby when the moisture content of said base support increases, the conductivity thereof increases proportionally, thereby to in turn maintain said predetermined bias voltage for the repulsion of developer powder from the nonimage areas of said photoconductive surface.

Claim 14

In an apparatus for developing a latent electrostatic image retained on the photoconductive surface of a photoelectrostatic recording member, said member having a moisture-sensitive base supporting said surface, the combination comprising: developer means for applying electroscopic powder to the surface whereby the latent image is converted into a visible form; a source of electrical power; a corona-type electrode disposed adjacent said base support providing an electrical current to said member to produce a bias voltage of a predetermined level for repelling the powder from the nonimage areas of said photoconductive surface and including a discharge wire surrounded partially by a conductive shield, said wire being electrically connected to said power source; a roller member mounted for rolling engagement with said recording member along the base support thereof, said roller member including first and second electrically conductive halves insulatively spaced from each other, said first roller half being connected to the conductive shield of said corona electrode and said second roller half being connected to ground potential; and said first and second roller halves being electrically interconnected through said base support, whereby when the moisture content of said base support increases, the conductivity thereof increases proportionally, thereby to in turn maintain said predetermined bias voltage for the repulsion of developer powder from the nonimage areas of said photoconductive surface.

Claim 15

The combination as defined in claim 11, wherein each of said roller halves of said roller member comprises a conductive core extending axially thereof with a cylindrical insulating jacket formed thereabout, and wherein said roller halves include mounted at opposing ends thereof, electrically conductive disc members, each of which is connected to a respective one of said conductive cores of said roller halves, said disc members being joined by means of an insulating spacer and being in rolling engagement with the base support of said recording member.