Image formation apparatus, developing device incorporated therein and conductive rubber roller used therein

A conductive rubber roller used in an image formation apparatus wherein an electrostatic latent image formed on an image carrying body is electrostatically developed with a toner developer, and is electrostatically transferred from said image carrying body to a recording medium, which conductive rubber roller comprises:

• a conductive tubular rubber roller element having an outer thicker portion including a given amount of conductive filler dispersed therein, and an inner skin layer defining a central bore thereof and exhibiting an electric resistivity considerably higher than that of said outer thicker portion for lack of conductive filler;
• a conductive shaft member fixedly inserted into the central bore of said conductive tubular rubber roller element;
• and
• an electrical contact establishing means provided between said conductive tubular rubber roller element and said conductive shaft member for establishing sufficient electrical contact therebetween, said electrical contact establishing means including two conductive plate members mounted on said conductive shaft member and adhered to end faces of said conductive tubular rubber roller element by thermally fusing a material of the outer thicker portion of said conductive tubular rubber roller element at the end faces thereof.

A conductive rubber roller used in an image formation apparatus wherein an electrostatic latent image formed on an image carrying body is electrostatically developed with a toner developer, and is electrostatically transferred from said image carrying body to a recording medium, which conductive rubber roller comprises:

• a conductive tubular rubber roller element having an outer thicker portion including a given amount of conductive filler dispersed therein, and an inner skin layer defining a central bore thereof and exhibiting an electric resistivity considerably higher than that of said outer thicker portion for lack of conductive filler;
• a conductive shaft member fixedly inserted into the central bore of said conductive tubular rubber roller element;
• and
• an electrical contact establishing means provided between said conductive tubular rubber roller element and said conductive shaft member for establishing sufficient electrical contact therebetween, said electrical contact establishing means including an at least partial thermal fusing of the inner skin layer of said conductive tubular rubber roller element.

A conductive rubber roller used in an image formation apparatus wherein an electrostatic latent image formed on an image carrying body is electrostatically developed with a toner developer, and is electrostatically transferred from said image carrying body to a recording medium, which conductive rubber roller comprises:

• a conductive tubular rubber roller element having an outer thicker portion including a given amount of conductive filler dispersed therein, and an inner skin layer defining a central bore thereof and exhibiting an electric resistivity considerably higher than that of said outer thicker portion for lack of conductive filler;
• a conductive shaft member fixedly inserted into the central bore of said conductive tubular rubber roller element;
• and
• an electrical contact establishing means provided between said conductive tubular rubber roller element and said conductive shaft member for establishing sufficient electrical contact therebetween, said electrical contact establishing means including an electrical insulation-breakage of the inner skin layer of said conductive tubular rubber roller element.

An electrophotographic recording apparatus comprising:

• an electrostatic latent image carrying body means;
• a developing roller means for entraining the developer to bring an electrostatically-charged toner developer to said electrostatic latent image carrying body means for development of an electrostatic latent image with the toner developer;
• and
• a transfer roller means for electrostatically transferring a charged toner image developed by said developing roller means from said electrostatic latent image carrying body means to a recording medium such as a paper,
• wherein at least one of said developing roller means and said transfer roller means includes a conductive foam rubber roller which comprises:
• a conductive tubular rubber roller element having an outer thicker portion including a given amount of conductive filler dispersed therein, and an inner skin layer defining a central bore thereof and exhibiting an electric resistivity considerably higher than that of said outer thicker portion for lack of conductive filler;
• a conductive shaft member fixedly inserted into the central bore of said conductive tubular rubber roller element;
• and
• an electrical contact establishing means provided between said conductive tubular rubber roller element and said conductive shaft member for establishing sufficient electrical contact therebetween, said electrical contact establishing means including two conductive plate members mounted on said conductive shaft member and adhered to end faces of said conductive tubular rubber roller element by a conductive adhesive.

An electrophotographic recording apparatus comprising:

• an electrostatic latent image carrying body means;
• a developing roller means for entraining the developer to bring an electrostatically-charged toner developer to said electrostatic latent image carrying body means for development of an electrostatic latent image with the toner developer;
• and
• a transfer roller means for electrostatically transferring a charged toner image developed by said developing roller means from said electrostatic latent image carrying body means to a recording medium such as a paper,
• wherein at least one of said developing roller means and said transfer roller means includes a conductive foam rubber roller which comprises:
• a conductive tubular rubber roller element having an outer thicker portion including a given amount of conductive filler dispersed therein, and an inner skin layer defining a central bore thereof and exhibiting an electric resistivity considerably higher than that of said outer thicker portion for lack of conductive filler;
• a conductive shaft member fixedly inserted into the central bore of said conductive tubular rubber roller element;
• and
• an electrical contact establishing means provided between said conductive tubular rubber roller element and said conductive shaft member for establishing sufficient electrical contact therebetween, said electrical contact establishing means including two conductive plate members mounted on said conductive shaft member and adhered to end faces of said conductive tubular rubber roller element by thermally fusing a material of the outer thicker portion of said conductive tubular rubber roller element at the end faces thereof.

An electrophotographic recording apparatus comprising:

• an electrostatic latent image carrying body means;
• a developing roller means for entraining the developer to bring an electrostatically-charged toner developer to said electrostatic latent image carrying body means for development of an electrostatic latent image with the toner developer;
• and
• a transfer roller means for electrostatically transferring a charged toner image developed by said developing roller means from said electrostatic latent image carrying body means to a recording medium such as a paper,
• wherein at least one of said developing roller means and said transfer roller means includes a conductive foam rubber roller which comprises:
• a conductive tubular rubber roller element having an outer thicker portion including a given amount of conductive filler dispersed therein, and an inner skin layer defining a central bore thereof and exhibiting an electric resistivity considerably higher than that of said outer thicker portion for lack of conductive filler;
• a conductive shaft member fixedly inserted into the central bore of said conductive tubular rubber roller element;
• and
• an electrical contact establishing means provided between said conductive tubular rubber roller element and said conductive shaft member for establishing sufficient electrical contact therebetween, said electrical contact establishing means including an at least partial thermal fusing of the inner skin layer of said conductive tubular rubber roller element.

An electrophotographic recording apparatus comprising:

• an electrostatic latent image carrying body means;
• a developing roller means for entraining the developer to bring an electrostatically-charged toner developer to said electrostatic latent image carrying body means for development of an electrostatic latent image with the toner developer;
• and
• a transfer roller means for electrostatically transferring a charged toner image developed by said developing roller means from said electrostatic latent image carrying body means to a recording medium such as a paper,
• wherein at least one of said developing roller means and said transfer roller means includes a conductive foam rubber roller which comprises:
• a conductive tubular rubber roller element having an outer thicker portion including a given amount of conductive filler dispersed therein, and an inner skin layer defining a central bore thereof and exhibiting an electric resistivity considerably higher than that of said outer thicker portion for lack of conductive filler;
• a conductive shaft member fixedly inserted into the central bore of said conductive tubular rubber roller element;
• and
• an electrical contact establishing means provided between said conductive tubular rubber roller element and said conductive shaft member for establishing sufficient electrical contact therebetween, said electrical contact establishing means including an electrical insulation-breakage of the inner skin layer of said conductive tubular rubber roller element.

A developing device using a non-magnetic type developer for developing an electrostatic latent image formed on an image carrying body, which device comprises:

• developer carrying means resiliently pressed against the image carrying body and formed of a conductive open-cell foam rubber material so that pore openings appear on a surface of said developer carrying means to entrain and carry the developer to a surface of the image carrying body for development of the electrostatic latent image formed thereon, said developer carrying means being supplied with a developing bias voltage;
• and
• developer regulating means engaged with said developer carrying means for regulating a thickness of the developer entrained and carried thereby,
• wherein the developer is composed of a toner component having a given average diameter, and a resin powder component having a diameter of about three hundredths of the average diameter thereof, the toner component of which has a polarity opposite to that of an electric charge of the resin powder component generated by triboelectrification therebetween,
• wherein the pore openings of said developer carrying means have a diameter of from about two and a half to about four times the average diameter of the toner component of said developer, and
• wherein the polarity of the resin powder component is opposite to that of the developing bias voltage so that the toner component is electrostatically held in the pore openings through the intermediary of the reversely-charged resin powder component.

A developing device using a non-magnetic type developer for developing an electrostatic latent image formed on an image carrying body, which device comprises:

• developer carrying means resiliently pressed against the image carrying body and formed of a conductive open-cell foam rubber material so that pore openings appear on a surface of said developer carrying means to entrain and carry the developer to a surface of the image carrying body for development of the electrostatic latent image formed thereon;
• and
• developer regulating means engaged with said developer carrying means for regulating a thickness of the developer entrained and carried thereby,
• wherein the developer is composed of a toner component and a resin powder component, the toner component of which has a polarity opposite to that of an electric charge of the resin powder component generated by triboelectrification therebetween,
• wherein the pore openings of said developer carrying means have a diameter of from about two and a half to about four times an average diameter of the toner component of said developer.

A developing device using a non-magnetic type developer for developing an electrostatic latent image formed on an image carrying body, which device comprises:

• developer carrying means resiliently pressed against the image carrying body and formed of a conductive open-cell foam rubber material so that pore openings appear on a surface of said developer carrying means to entrain and carry the developer to a surface of the image carrying body for development of the electrostatic latent image formed thereon;
• and
• developer regulating means engaged with said developer carrying means for regulating a thickness of the developer entrained and carried thereby,
• wherein the developer is composed of a toner component and a resin powder component, the toner component of which has a polarity opposite to that of an electric charge of the resin powder component generated by triboelectrification therebetween,
• wherein the pore openings of said developer carrying means have a diameter of from about two and a half to about four times an average diameter of the toner component of the developer, and
• wherein said developer carrying means includes:
• a conductive tubular foam rubber roller element having an outer thicker portion including a given amount of conductive filler dispersed therein, and an inner solid skin layer defining a central bore thereof and exhibiting an electrical resistivity considerably higher than that of said outer thicker portion for lack of conductive filler;
• a conductive shaft member fixedly inserted into the central bore of said conductive tubular rubber roller element;
• and
• an electrical contact establishing means provided between said conductive tubular rubber roller element and said conductive shaft member for establishing a sufficient electric contact therebetween.

An image formation apparatus comprising:

• image carrying means for carrying an electrostatic latent image formed thereon;
• and
• developing means for developing the electrostatic latent image of said image carrying means with a non-magnetic type developer, said developing means including a developer carrying means resiliently pressed against said image carrying means and formed of a conductive open-cell foam rubber material so that pore openings appear on a surface thereof to entrain and carry the developer to a surface of said image carrying means for development of the electrostatic latent image formed thereon, said developer carrying means being supplied with a developing bias voltage, and a developer regulating means engaged with said developer carrying means for regulating a thickness of the developer entrained and carried thereby,
• wherein the developer is composed of a toner component having a given average diameter, and a resin powder component having a diameter less than the average diameter thereof, the toner component of which has a polarity opposite to that of an electric charge of the resin powder component generated by triboelectrification therebetween, and
• wherein the polarity of the resin powder component is opposite to that of the developing bias voltage so that the toner component is electrostatically held in the pore openings through the intermediary of the reversely-charged resin powder component.

A developing device using a non-magnetic type developer for developing an electrostatic latent image formed on an image carrying body, which device comprises:

• a developer carrying roller resiliently pressed against the image carrying body and formed of a conductive open-cell foam rubber material so that pore openings appear on a surface of said developer carrying means to entrain and carry the developer to a surface of the image carrying body for development of the electrostatic latent image formed thereon;
• a shaft member for holding said developer carrying roller, said shaft member having a longitudinal axis;
• a thin metal blade member pressed against said developer carrying roller, said thin metal blade member extending along the longitudinal axis of said shaft member to regulate a thickness of the developer entrained and carried thereby;
• and
• a holder for holding said thin metal blade member so as to press the same against said developer carrying roller, said holder being constituted such that a larger pressure is applied to said thin metal blade member at a center of said shaft member in the longitudinal axis thereof, for compensating for a resilient deformation of the shaft member of said developer carrying roller, which is caused when pressing said thin metal blade member against said developer carrying roller.

A developing device using a non-magnetic type developer for developing an electrostatic latent image formed on an image carrying body, which device comprises:

• a developer carrying roller resiliently pressed against the image carrying body and formed of a conductive open-cell foam rubber material so that pore openings appear on a surface of said developer carrying means to entrain and carry the developer to a surface of the image carrying body for development of the electrostatic latent image formed thereon;
• and
• a developer regulating means including a thin metal blade member pressed against said developer carrying roller means for regulating a thickness of the developer entrained and carried thereby,
• wherein said developer regulating means further includes compensating means for compensating for a resilient deformation of a shaft member of said developer carrying roller means, which is caused when pressing said thin metal blade member against said developer carrying roller means, whereby the thickness of the developer regulated by said developer regulating means can be made substantially uniform, and
• wherein said developer carrying roller means includes:
• a conductive tubular foam rubber roller element having an outer thicker portion including a given amount of conductive filler dispersed therein, and an inner solid skin layer defining a central bore thereof and exhibiting an electrical resistivity considerably higher than that of said outer thicker portion for lack of conductive filler;
• a conductive shaft member fixedly inserted into the central bore of said conductive tubular rubber roller element;
• and
• an electrical contact establishing means provided between said conductive tubular rubber roller element and said conductive shaft member for establishing a sufficient element contact therebetween.