Image-forming apparatus for use with negatively-charged toner and featuring a negatively-chargeable image-bearing member, and process cartridge using same

An image-forming apparatus comprising:

• an image-bearing member for holding thereon an electrostatic latent image;
• charging means for electrostatically charging a surface of said image-bearing member;
• an exposure unit for forming the electrostatic latent image on said image-bearing member by exposing the image-bearing member to light, said image bearing member having been charged by said charging means;
• and
• a plurality of developing units for developing electrostatic latent images with toners of different colors;
• wherein each of said plurality of developing units include a toner-carrying member for carrying and transporting thereon a negatively chargeable toner having a different color, a toner-carrying member of one developing unit selected from said plurality of developing units being brought into contact with said image-bearing member to form a developing zone where the toner is made to electrically adhere to the electrostatic latent image formed on said image-bearing member to render the electrostatic latent image visible,
• wherein each of said plurality of developing units are operated sequentially to form multi-color toner images,
• wherein in a triboelectric series relationship formed between the toner and a surface layer of said image-bearing member in each of said plurality of developing units, said surface layer has a charge polarity, which is a different polarity with respect to a charge polarity of each toner in each of said plurality of said developing units, and
• wherein said image-bearing member having the electrostatic latent image has a surface potential, as a nonimage area potential (Vd) within a range of −500 to −800 V, and as an image area potential (Vl), at which the maximum toner image density is to be obtained, within a range of −50 to −200 V.

A process cartridge, which is detachably mountable on a main body of an image-forming apparatus for forming a fixed image by developing with a toner an electrostatic latent image to form a toner image, and transferring the toner image to a transfer medium, followed by fixing, said process cartridge comprising:

• an image-bearing member for holding thereon the image;
• a developing unit, which includes a toner-carrying member for carrying and transporting a negatively chargeable toner thereon, said toner-carrying member being brought into contact with said image-bearing member to form a developing zone where the toner is made to electrically adhere to the electrostatic latent image formed on said image-bearing member, to render the electrostatic latent image visible to form a toner image;
• and
• at least one of a means selected from a group consisting of:
• (a) charging means for electrostatically charging a surface of said image-bearing member;
• (b) an exposure unit for forming the electrostatic latent image on said image-bearing member by exposing said image-bearing member to light, said image bearing member having been charged;
• (c) transfer means for transferring the toner image formed by said developing unit to a transfer medium;
• and
• (d) cleaning means for removing a toner remaining on said image-bearing member after the toner image has been transferred to the transfer medium, said cleaning means being integrally supported with said image-bearing member and said developing unit,
• wherein in a triboelectric series relationship formed between the toner and a surface layer of the image-bearing member, said surface layer of said image-bearing member having a charge polarity, which is a different polarity with respect to a charge polarity of the toner in said developing unit, and
• wherein said image-bearing member having the electrostatic latent image has a surface potential, as a nonimage area potential (Vd) within a range of −500 to −800 V, and as an image area potential (Vl), at which the maximum toner image density is to be obtained, within a range of −50 to −200 V.

An image-forming apparatus comprising:

• an image-bearing member for holding thereon an electrostatic latent image;
• an exposure unit for forming the electrostatic latent image on said image-bearing member by exposing said image-bearing member to light;
• and
• a developing unit, which includes a toner-carrying member for carrying and transporting thereon a negatively chargeable toner including toner particles and at least one external additive, said toner-carrying member being brought into contact with said image-bearing member to form a developing zone where the toner is made to electrically adhere to the electrostatic latent image formed on said image-bearing member to render the electrostatic latent image visible to form a toner image;
• wherein in a triboelectric series relationship formed between a surface layer of said image-bearing member, the toner particles, and the external additive are disposed in the order of the external additive, the toner particles, and said surface layer of said image-bearing member from the negative side, and
• wherein said image-bearing member having the electrostatic latent image has a surface potential, as a nonimage area potential (Vd) within a range of −500 to −800 V, and as an image area potential (Vl), at which the maximum toner image density is to be obtained, within a range of −50 to −200 V.

An image-forming apparatus comprising:

• an image-bearing member for holding thereon an electrostatic latent image;
• an exposure unit for forming the electrostatic latent image on said image-bearing member by exposing said image-bearing member to light;
• and
• a developing unit, which includes a toner-carrying member for carrying and transporting thereon a negatively chargeable toner having toner particles and at least one external additive, said toner-carrying member being brought into contact with said image-bearing member to form a developing zone where the toner is made to electrically adhere to the electrostatic latent image formed on said image-bearing member to render the electrostatic latent image visible to form a toner image,
• wherein in a triboelectric series relationship formed between a surface layer of said image-bearing member, the toner particles, and the external additive are disposed in the order of the toner particles, the external additive, and said surface layer of said image-bearing member from the negative side, and
• wherein said image-bearing member having the electrostatic latent image has a surface potential, as a nonimage area potential (Vd) within a range of −500 to −800 V, and as an image area potential (Vl), at which the maximum toner image density is to be obtained, within a range of −50 to −200 V.

An image-forming apparatus comprising:

• an image-bearing member for holding thereon an electrostatic latent image;
• an exposure unit for forming the electrostatic latent image on said image-bearing member by exposing said image-bearing member to light;
• and
• a developing unit, which includes a toner-carrying member for carrying and transporting thereon a negatively, chargeable toner, said toner including toner particles and at least one external additive, said toner-carrying member being brought into contact with said image-bearing member to form a developing zone where the toner is made to electrically adhere to the electrostatic latent image formed on said image-bearing member to render the electrostatic latent image visible to form a toner image;
• wherein in a triboelectric series relationship formed between a surface layer of said image-bearing member, the toner particles, and the external additive are disposed in the order of the toner particles, said surface layer of the image-bearing member, and the external additive from the negative side, and
• wherein said image-bearing member having the electrostatic latent image has a surface potential, as a nonimage area potential (Vd) within a range of −500 to −800 V, and as an image area potential (Vl), at which the maximum toner image density is to be obtained, within a range of −50 to −200 V.

A process cartridge, which is detachably mountable to a main body of an image-forming apparatus for forming a fixed image by developing with a toner an electrostatic latent image to form a toner image, and transferring the toner image to a transfer medium, followed by fixing, said process cartridge comprising:

• an image-bearing member for holding thereon the electrostatic latent image;
• a developing unit, which includes a toner-carrying member for carrying and transporting thereon a negatively chargeable toner, said toner including toner particles and at least one external additive, said toner-carrying member being brought into contact with said image-bearing member to form a developing zone where the toner is made to electrically adhere to the electrostatic latent image formed on said image-bearing member, to render the electrostatic latent image visible to form a toner image;
• and
• at least one of a means selected from the group consisting of:
• (a) charging means for electrostatically charging a surface of the image-bearing member;
• (b) an exposure unit for forming the electrostatic latent image on said image-bearing member by exposing said image-bearing member to light, said image bearing member having been charged;
• (c) transfer means for transferring the toner image formed by said developing unit, to the transfer medium;
• and
• (d) cleaning means for removing toner remaining on said image-bearing member after the toner image has been transferred to the transfer medium, said cleaning means being integrally supported with said image-bearing member and said developing unit,
• wherein in a triboelectric series relationship formed between a surface layer of the image-bearing member, the toner particles, and the external additive being in the order of the external additive, the toner particles, and said surface layer of said image-bearing member from the negative side, and
• wherein said image-bearing member having the electrostatic latent image has a surface potential, as a nonimage area potential (Vd) within a range of −500 to −800 V, and as an image area potential (Vl), at which the maximum toner image density is to be obtained, within a range of −50 to −200 V.

A process cartridge, which is detachably mountable to a main body of an image-forming apparatus for forming a fixed image by developing, with a toner, an electrostatic latent image to form a toner image, and transferring the toner image to a transfer medium, followed by fixing;

• said process cartridge comprising:
• an image-bearing member for holding thereon the electrostatic latent image;
• a developing unit, which includes a toner-carrying member for carrying and transporting thereon a negatively chargeable toner, said toner including toner particles and at least one external additive, said toner-carrying member being brought into contact with said image-bearing member to form a developing zone where the toner is made to electrically adhere the electrostatic latent image formed on said image-bearing member to render the electrostatic latent image visible to form a toner image;
• and
• at least one of a means selected from the group consisting of:
• (a) charging means for charging a surface of said image-bearing member electrostatically;
• (b) an exposure unit for forming the electrostatic latent image on said image-bearing member by exposing said image-bearing member to light, said image bearing member having been charged;
• (c) transfer means for transferring the toner image formed by said developing unit to the transfer medium;
• and
• (d) cleaning means for removing a toner remaining on said image-bearing member after the toner image has been transferred to the transfer medium, said cleaning means being integrally supported with said image-bearing member and said developing unit;
• wherein in a triboelectric series relationship formed between a surface layer of said image-bearing member, the toner particles, and the external additive are disposed in the order of the toner particles, the external additive, and said surface layer of said image-bearing member from the negative side, and
• wherein said image-bearing member having the electrostatic latent image has a surface potential, as a nonimage area potential (Vd) within a range of −500 to −800 V, and as an image area potential (Vl), at which the maximum toner image density is to be obtained, within a range of −50 to −200 V.

A process cartridge, which is detachably mountable to a main body of an image-forming apparatus for forming a fixed image by developing, with a toner, an electrostatic latent image to form a toner image, and transferring the toner image to a transfer medium, followed by fixing, said process cartridge comprising:

• an image-bearing member for holding thereon the electrostatic latent image;
• a developing unit, which includes a toner-carrying member for carrying and transporting thereon a negatively chargeable toner, said toner including toner particles and at least one external additive;
• said toner-carrying member being brought into contact with said image-bearing member to form a developing zone where the toner is made to electrically adhere to the electrostatic latent image formed on said image-bearing member to render the electrostatic latent image visible to form a toner image;
• and
• at least one of a means selected from a group consisting of:
• (a) charging means for electrostatically charging a surface of said image-bearing member;
• (b) an exposure unit for forming the electrostatic latent image on said image-bearing member by exposing said image-bearing member to light, said image bearing member having been charged;
• (c) transfer means for transferring the toner image formed by said developing unit, to the transfer medium;
• and
• (d) cleaning means for removing a toner remaining on said image-bearing member after the toner image has been transferred to the transfer medium, said cleaning means being integrally supported with said image-bearing member and said developing unit;
• wherein in a triboelectric series relationship formed between a surface layer of said image-bearing member, the toner particles, and the external additive are disposed in the order of the toner particles, said surface layer of said image-bearing member, and the external additive from the negative side, and
• wherein said image-bearing member having the electrostatic latent image has a surface potential, as an nonimage area potential (Vd) within a range of −500 to −800 V, and as an image area potential (Vl), at which the maximum toner image density is to be obtained, within a range of −50 to −200 V.