US 4,287,850 AGranted

Magnetic brush developing apparatus

AssigneeMinolta Camera Kabushiki Kaisha

InventorsToshio Yamamoto, Shizuo Yuge

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Abstract

A magnetic brush developing apparatus for use in a toner powder image transfer type electrophotographic copying machine which includes an outer cylinder fixedly disposed at a position to confront a photosensitive member or photoreceptor, a magnet roller rotatably accommodated in the outer cylinder for being rotatably driven, a toner tank or hopper containing therein electrically conductive and magnetically attractive toner particles having high resistance and disposed above the outer cylinder for supplying the toner particles onto the outer cylinder, an excessive developing region for developing an image portion of an electrostatic latent image formed on said photosensitive member with sufficient density, and a toner removing region for removing toner particles adhering at least to non-image portion of the electrostatic latent image.

Claims18

Dependent claims

A magnetic brush developing apparatus for use in a toner powder image transfer type electrophotographic copying machine, which comprises:

a photosensitive member;
a single outer cylinder fixedly disposed in spaced opposed relation to said photosensitive member;
a magnet member rotatably accommodated in said outer cylinder for being rotatably driven;
a toner container containing therein a mono-component developer composed of magnetically attractive toner particles and disposed adjacent said outer cylinder for supplying the toner particles onto said outer cylinder;
a developing electrode plate on said outer cylinder and in spaced opposed relationship to the surface of said photosensitive member approximately equidistantly spaced from said photosensitive member and located upstream of the position at which the surface of said outer cylinder is closest to the surface of said photosensitive member an excessive developing region for causing the toner particles to be magnetically formed into a brush for transferring toner particles to said photosensitive member for developing the image portion of an electrostatic latent image formed on said photosensitive member with sufficient density;
toner particle guide means extending from said outer cylinder to the upstream end of said developing electrode plate for guiding toner particles from said outer cylinder to the upstream end of said developing electrode plate;
means connected to said apparatus in said excessive developing region for giving to said developing electrode plate a charge ranging from a charge equal to that of the reverse surface of the photosensitive member to a charge which biases said developing electrode plate with an opposite polarity to the polarity of said latent image, said outer cylinder and said photosensitive member downstream of said excessive developing region defining therebetween a toner removing region for removing toner particles adhering at least to the non-image portions of the electrostatic latent image, said magnet member in said outer cylinder being closer to said photosensitive member in said toner removing region than in said excessive developing region for exerting a substantially stronger magnetic force on toner particles in said toner removing region than in said excessive developing region;
and further means connected to said apparatus in said toner removing region for giving to said apparatus on the side of said toner removing region on which said outer cylinder is positioned a charge ranging from a charge equal to that of said photosensitive member to a charge which biases said side of the toner removing region with the same polarity of said latent image.

5 more elements

A magnetic brush developing apparatus for use in a toner powder image transfer type electrophotographic copying machine, which comprises:

a photosensitive member;
a single outer cylinder fixedly disposed in spaced opposed relation to said photosensitive member;
a magnet member rotatably accommodated in said outer cylinder for being rotatably driven;
a toner container containing therein a mono-component developer composed of magnetically attractive toner particles and disposed adjacent said outer cylinder for supplying the toner particles onto said outer cylinder;
a developing electrode plate on said outer cylinder and in spaced opposed relationship to the surface of said photosensitive member approximately equidistantly spaced from said photosensitive member and located upstream of the position at which the surface of said outer cylinder is closest to the surface of said photosensitive member, an excessive developing region for causing the toner particles to be magnetically formed into a brush for transferring toner particles to said photosensitive member for developing the image portion of an electrostatic latent image formed on said photosensitive member with sufficient density;
toner particle guide means extending from said outer cylinder to the upstream end of said developing electrode plate for guiding toner particles from said outer cylinder to the upstream end of said developing electrode plate;
means connected to said apparatus in said excessive developing region for giving to said developing electrode plate a charge ranging from a charge equal to that of the reverse surface of the photosensitive member to a charge which biases said developing electrode plate with an opposite polarity to the polarity of said latent image;
a toner removing electrode plate disposed on said outer cylinder downstream of said developing electrode plate, said toner removing electrode plate and said photosensitive member downstream of said excessive developing region defining therebetween a toner removing region for removing toner particles adhering at least to the non-image portions of the electrostatic latent image;
and a voltage source connected to said toner removing electrode plate for applying a biasing voltage thereto having the same polarity as that of the electrostatic latent image.

6 more elements

A magnetic brush developing device for developing an electrostatic latent image supported on a movable electrostatic latent image support member with a mono-component magnetizable toner which comprises:

(a) a developing electrode plate extending along and spaced from the surface of said electrostatic latent image support member and having at least two portions respectively having different potentials, one of said portions being located at a position upstream of the other portion relative to the direction of movement of said electrostatic latent image support member and having a potential opposite in polarity to the electrostatic latent image, and the other of said portions being located at a position downstream relative to the direction of movement of said electrostatic latent image support member and having a potential with the same polarity as the electrostatic latent image;
toner particle guide means extending to the upstream end of said one portion of said developing electrode plate for guiding toner particles to the upstream end of said one portion of said developing electrode plate;
and
(b) a single rotatably driven magnet roller positioned adjacent said developing electrode plate and in spaced opposed relation to said electrostatic latent image support member for causing the magnetizable toner to be magnetically attracted in the form of magnetic bristles on the surface of said developing electrode plate facing said electrostatic latent image support member and also for transporting said magnetizable toner in a predetermined direction.

1 more element

Dependencies are inferred from the claim text.