Developing apparatus

Claim 2

A developing apparatus for supplying developer to an electrostatic latent image on an electrostatic latent image bearing member for developing the latent image, comprising: developer conveying means with developer on a surface thereof for conveying the developer to a developing region, said developer conveying means including a high resistance layer on a developer conveying surface thereof and a medium resistance layer formed thereover and having a volume resistivity of 10 8 to 10 12 Ωcm; means for supplying the developer to said developer conveying means; and means for applying a developing bias voltage to said developer conveying means.

Claim 3

An apparatus according to claim 1, wherein said high resistance layer is made of alumina and said medium resistance layer is made of a mixture of alumina and titania.

Claim 4

An apparatus according to claim 2, wherein the mixture of alumina and titania contains about 12% by weight of titania.

Claim 5

An apparatus according to claim 1, wherein said high resistance layer is made of alumina and said medium resistance layer is made of a quaternary ammonium salt.

Claim 6

An apparatus according to claim 1, wherein said high resistance layer is made of alumina and said medium resistance layer includes a transparent adhesive tape which has a volume resistivity of 10 8 to 10 11 Ω-cm and is adhered to a surface of said high resistance layer.

Claim 8

An apparatus according to claim 6, wherein said sealing agent is an epoxy resin.

Claim 10

A developing apparatus for supplying developer to an electrostatic latent image on an electrostatic latent image bearing member for developing the latent image, comprising: developer conveying means with developer on a surface thereof for conveying the developer to a developing region, said developer conveying means including a high resistance layer on a developer conveying surface thereof and a medium resistance layer formed thereover and having a volume resistivity of 10 8 to 10 12 Ωcm; means for supplying the developer to said developer conveying means; means for applying a developing bias voltage to said conveying means; and means for supplying charge to said medium resistance layer as a surface layer.

Claim 11

A developing apparatus for supplying developer to an electrostatic latent image on an electrostatic latent image bearing member for developing the latent image, comprising: developer conveying means with developer on a surface thereof for conveying the developer to a developing region, said developer conveying means including a high resistance layer on a developer conveying surface thereof and a medium resistance layer formed thereover and having a volume resistivity of 10 8 to 10 12 Ωcm; means for supplying the developer to said developer conveying means; means for applying a developing bias voltage to said conveying means; and means for supplying charge to said medium resistance layer as a surface layer.

Claim 12

An apparatus according to claim 9, wherein said high resistance layer is made of alumina and said medium resistance layer is made of a mixture of alumina and titania.

Claim 13

An apparatus according to claim 10, wherein the mixture of alumina and titania contains about 12% by weight of titania.

Claim 14

An apparatus according to claim 9, wherein said high resistance layer is made of alumina and said medium resistance layer is made of a quaternary ammonium salt.

Claim 15

An apparatus according to claim 9, wherein said high resistance layer is made of alumina and said medium resistance layer includes a transparent adhesive tape which has a volume resistivity of 10 8 to 10 11 Ω-cm and is adhered to a surface of said high resistance layer.

Claim 17

An apparatus according to claim 14, wherein said sealing agent is an epoxy resin.

Claim 19

An apparatus according to claim 9, wherein said charge supplying means includes an electrode disposed in contact with or near said developer conveying means.

Claim 20

An apparatus according to claim 9, wherein said charge supplying means includes a corona discharger.

Claim 21

An apparatus according to claim 9, wherein said charge supplying means includes a roller-shaped electrode disposed in contact with said developer conveying means.

Claim 22

An apparatus according to claim 1 or 9, wherein said developing bias voltage applying means applies an dc voltage to said developer conveying means.

Claim 23

An apparatus according to claim 1 or 9, wherein said developing bias voltage applying means applies an ac voltage to said developer conveying means.

Claim 24

An apparatus according to claim 1 or 9, wherein said developing bias voltage applying means applies an ac voltage biased with a dc voltage to said developer conveying means.

Claim 25

An apparatus according to claim 1 or 9, wherein said developer conveying means includes a nonmagnetic cylinder and a magnet disposed therein.

Claim 26

An apparatus according to claim 23, wherein the developer is a one-component toner.

Claim 27

An apparatus according to claim 23, wherein the developer is a two-component developer including a toner and a carrier.

Claim 28

An apparatus according claim 1 or 9, wherein the developer is a liquid developer.

Claim 29

A developing apparatus for developing an electrostatic latent image on an electrostatic latent image bearing member, comprising: an electrically conductive nonmagnetic sleeve being rotatably disposed relative to said electrostatic latent image bearing member, said sleeve having, on an outer circumference thereof, a high resistance layer which is formed by plasma spray coating an alumina powder and sealing pores of the alumina coated layer formed thereby with an epoxy resin, and having, a medium resistance layer which is formed on a surface of said high resistance layer by plasma spray coating a mixture of alumina and 12% titania; a magnet roller being fixed within said sleeve; a hopper for supplying a one-component magnetic toner on a surface of said sleeve; a magnetic doctor blade being arranged near said sleeve and in opposition to magnetic poles of said magnet roller, a clearance between said magnetic doctor blade and said sleeve being smaller than a clearance between said sleeve and said electrostatic latent image bearing member; and a power source for applying an ac developing bias voltage biased with a dc voltage between said sleeve and said electrostatic latent image bearing member.

Claim 30

A developing apparatus for developing an electrostatic latent image on an electrostatic latent image bearing member, comprising: an electrically conductive nonmagnetic sleeve being rotatably disposed relative to said electrostatic latent image bearing member, said sleeve having, on an outer circumference thereof, a high resistance layer which is formed by plasma spray coating an alumina powder and sealing pores of the alumina coated layer formed thereby with an epoxy resin, and having, a medium resistance layer which is formed on a surface of said high resistance layer by plasma spray coating a mixture of alumina and 12% titania; a magnet roller being fixed within said sleeve; a hopper for supplying a one-component magnetic toner on a surface of said sleeve; a magnetic doctor blade being arranged near said sleeve and in opposition to magnetic poles of said magnet roller, a clearance between said magnetic doctor blade and said sleeve being smaller than a clearance between said sleeve and said electrostatic latent image bearing member; and a power source for applying an ac developing bias voltage biased with a dc voltage between said sleeve and said electrostatic latent image bearing member.

Claim 31

An apparatus according to claim 27, further comprising means for supplying charge to said medium resistance layer as a surface layer.