Developing apparatus
View Patent ↗A developing apparatus supplies a developer from a developing roller to an image-bearing body that bears an electrostatic latent image thereon. A toner-supplying roller is rotatably supported to oppose the developing roller. A rotating body has recesses formed in its surface, opposing the developer-bearing member. The toner-supplying roller and the rotating body rotate in opposite directions and at different circumferential speeds. The rotating body is formed of a foamed material having cells formed in and open to a surface of the rotating body, the cells having a cell size in the range of 10 to 40 cells/inch. The toner-supplying roller and the rotating body rotate at circumferential speeds such that a ratio between the circumferential speeds is in the range of 1 to 2.5. The rotating body and toner-supplying roller may have a diameter that varies along the length.
1. A developing apparatus that supplies a developer from a developer-bearing member to an image-bearing body that bears an electrostatic latent image thereon, the apparatus comprising:
a developer-bearing body rotatably supported and opposing said electrostatic latent image bearing body, said developer bearing body supplying developer to said electrostatic latent image bearing body;
a developer-supplying member rotatably supported and opposing the developer-bearing member, said developer-supplying member being formed of a foamed material and supplying the developer to said developer bearing body; and
a rotating body having cell walls formed on its surface and opposing said developer-supplying member;
wherein said rotating body rotates in an opposite direction to said developer-bearing body at a higher circumferential speed than said developer-supplying member, and has a higher hardness than said developer-supplying member.
2. The developing apparatus according to claim 1 , wherein said rotating body is formed of a foamed material.
3. The developing apparatus according to claim 2 , wherein the foamed material is urethane and the cell walls form cells open to a surface of said rotating body, the cells having a cell size in the range of 10 to 40 cells/inch.
4. The developing apparatus according to claim 1 , wherein said developer-supplying member and said rotating body rotate at circumferential speed such that a ratio between the circumferential speeds is in the range of 1 to 2.5.
5. The developing apparatus according to claim 1 , wherein said rotating body rotates on a shaft having a first end and a second end, said rotating body being driven in rotation at the first end and having a diameter that is larger nearer the second end.
6. The developing apparatus according to claim 1 , wherein said developer-supplying member has a first diameter and a first length along which the first diameter is larger nearer a first middle portion of said developer-supplying member;
wherein said rotating body has a second diameter and a second length along which the second diameter is smaller nearer a second middle portion of said rotating body.
7. The developing apparatus according to claim 3 , wherein said rotating body is formed of an electrically semiconductive material;
wherein said rotating body receives a first voltage, and said developer-supplying member receives a second voltage, the first voltage having a larger absolute value than the second voltage.
8. The developing apparatus according to claim 1 , wherein said rotating body is spaced from said developer bearing body.
9. The developing apparatus according to claim 2 , wherein said developer-supplying member and said rotating body are disposed with a gap not more than 0.5 mm therebetween.
10. The developing apparatus according to claim 2 , wherein said developer-supplying member and said rotating body are disposed with a nip not more than 1 mm therebetween.