Developing device used in electrophotographic field and method of producing developing roller incorporated therein

A developing device using a one-component developer, which device comprises:

• a vessel for holding a one-component developer composed of toner particles;
• a developing roller rotatably provided within said vessel in such a manner that a portion of said developing roller is exposed therefrom and faces the surface of an electrostatic latent image carrying body;
• said developing roller being formed of a conductive open-cell foam rubber material so that pore openings appear over a surface of said developing roller, whereby during a rotation of said developing roller, the toner particles are captured and held by the pore openings of said developing roller to form a developer layer therearound and are carried to the surface of said electrostatic latent image carrying body;
• and
• the pore opening or porous cells of said developing roller being in communication with each other through fine passages formed among said porous cells, said fine passages having a diameter which is at most twice an average diameter of the toner particles.

A developing device using a one-component developer, comprising:

• a vessel for holding a one-component developer composed of toner particles;
• a developing roller rotatably provided within said vessel in such a manner that a portion of said developing roller is exposed therefrom and faces the surface of an electrostatic latent image carrying body;
• said developing roller being formed of a conductive rubber material by which the toner particles are entrained to form a developer layer therearound and are carried to the surface of said electrostatic latent image carrying body;
• and
• a developer layer regulating means provided within said vessel and resiliently engaged with said developing roller for regulating a thickness of the developer layer formed around said developing roller,
• wherein said developing roller is constituted such that a work function thereof approximates that of the toner particles, so that the toner particles are charged by a triboelectrification between said developer layer regulating means and the toner particles, whereby the toner particles can be given a desired charge distribution regardless of variations of temperature and air moisture content.

A developing device using a one-component developer, which device comprises:

• a vessel for holding a one-component developer composed of toner particles;
• a developing roller rotatably provided within said vessel in such a manner that a portion of said developing roller is exposed therefrom and faces the surface of an electrostatic latent image carrying body;
• said developing roller being formed of a conductive rubber material by which the toner particles are entrained to form a developer layer therearound and are carried to the surface of said electrostatic latent image carrying body;
• and
• a developer layer regulating means provided within said vessel and resiliently engaged with said developing roller for regulating a thickness of the developer layer formed around said developing roller,
• wherein when the toner particles are charged by a triboelectrification between said developing roller and developer layer regulating means and the toner particles, said developing roller and developer layer regulating means are constituted in such a manner that a relationship of work functions W.sub.1 and W.sub.2 thereof and a work function W.sub.3 of the toner particles is defined by the following formula:
• (W.sub.1 -W.sub.3).times.(W.sub.2 -W.sub.3)>0
• whereby the toner particles can be given a desired distribution.

A developing device using a one-component developer, comprising:

• a vessel for holding a one-component developer composed of toner particles;
• a developing roller rotatably provided within said vessel in such a manner that a portion of said developing roller is exposed therefrom and faces the surface of an electrostatic latent image carrying body;
• said developing roller being formed of a conductive rubber material by which the toner particles are entrained to form a developer layer therearound and are carried to the surface of said electrostatic latent image carrying body;
• and
• a developer layer regulating means provided within said vessel and resiliently engaged with said developing roller for regulating a thickness of the developer layer formed around said developing roller,
• wherein said developer layer regulating means is formed of a conductive material for applying a bias voltage thereto to prevent the toner particles from being electrostatically adhered to said developer layer regulating means, and wherein said developing roller and said developer layer regulating means are constituted in such a manner that work functions thereof approximate that of the toner particles, so that the toner particles are charged by a charge-injection effect resulting from the application of the bias voltage to said developer layer regulating means, whereby the toner particles can be given a desired charge distribution regardless of variations of temperature and air moisture content.

A developing device using a one-component developer, comprising:

• a vessel for holding a one-component developer composed of toner particles;
• a developing roller rotatably provided within said vessel in such a manner that a portion of said developing roller is exposed therefrom and faces the surface of an electrostatic latent image carrying body;
• said developing roller being formed of a conductive rubber material by which the toner particles are entrained to form a developer layer therearound and are carried to the surface of said electrostatic latent image carrying body;
• and
• a developer layer regulating means provided within said vessel and resiliently engaged with said developing roller for regulating a thickness of the developer layer formed around said developing roller,
• wherein said developer layer regulating means is formed of a conductive material for applying a bias voltage thereto to prevent the toner particles from being electrostatically adhered to said developer layer regulating means, and wherein a charge-injection effect resulting from the application of the bias voltage to said developer layer regulating means and a triboelectrification between said developing roller and/or developer layer regulating means and the toner particles are utilized for charging the toner particles.

A developing device using a one-component developer, which device comprises:

• a vessel for holding a one-component developer composed of toner particles;
• a developing roller rotatably provided within said vessel in such a manner that a portion of said developing roller is exposed therefrom and faces the surface of an electrostatic latent image carrying body;
• said developing roller being formed of a conductive rubber material by which the toner particles are entrained to form a developer layer therearound and are carried to the surface of said electrostatic latent image carrying body;
• and
• a developer layer regulating means provided within said vessel and resiliently engaged with said developing roller for regulating a thickness of the developer layer formed around said developing roller,
• wherein said developer layer regulating means is formed of a conductive material for applying a bias voltage thereto to prevent the toner particles from being electrostatically adhered to said developer layer regulating means;
• and when a charge-injection effect resulting from the application of the bias voltage to said developer layer regulating means is utilized for charging the toner particles, a difference between the bias voltage applied to said developer layer regulating means and a developing bias voltage applied to said developing roller is less than a level at which a high electrical current or an electrical discharge occurs between said developer layer regulating means and said developing roller.