Takano, Masao; Okuno, Ryozo; Nakamura, Kimihiko;

Nonmagnetic one-component developing method

A contact-type nonmagnetic one-component developing method using a developing apparatus having at least a developer carrying member and a developer layer thickness control member provided so as to be adjacent to, or to be in contact under pressure with, said developer carrying member, which method comprises feeding a developer to said developer carrying member, forming a thin layer of the developer on a surface of the developer carrying member with the developer layer thickness control member with negatively charging the developer under friction, bringing the thin layer of the developer into contact with a photoconductive material holding an electrostatic latent image to develop the electrostatic latent image, and transferring the resultant developed image to an image receptor, said developer being a nonmagnetic one-component developer prepared by attaching fine particles of an additive to be positively charged to particles of a toner which is comprised mainly of a binder resin and a colorant and which is to be negatively charged, said developer being designed to be negatively charged under the friction in a hopper, the amount of fine particles of the additive being 0.05 to 3 parts by weight per 100 parts by weight of the toner.

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What is claimed is:

1. A contact-type nonmagnetic one-component developing method using a developing apparatus having at least a developer carrying member and a developer layer thickness control member provided so as to be adjacent to, or to be in contact under pressure with, said developer carrying member, which comprises feeding a developer to said developer carrying member, forming a thin layer of the developer on a surface of the developer carrying member with the developer layer thickness control member with negatively charging the developer under friction, bringing the thin layer of the developer into contact with a photoconductive material holding an electrostatic latent image to develop the electrostatic latent image, and transferring the resultant developed image to an image receptor, said developer being a nonmagnetic one-component developer prepared by attaching fine particles of an additive to be positively charged to particles of a toner which is comprised mainly of a binder resin and a colorant and is to be negatively charged, said which developer being designed to be negatively charged under the friction with a hopper, the amount of fine particles of the additive being 0.05 to 3 parts by weight per 100 parts by weight of the toner.

2. A method according to claim 1, wherein the developing apparatus has a developing roll which is formed of an electrically conductive and elastic material or has a surface layer formed of an electrically conductive material.

3. A method according to claim 2, wherein the electrically conductive elastic material is a product produced by dispersing an electrically conductive powder in a rubber-containing material.

4. A method according to claim 1, wherein the developer layer thickness control member is a doctor blade or a roll which rotates reversely to the rotation of the developer carrying member.

5. A method according to claim 1, wherein the photoconductive material holding an electrostatic latent image is a cylindrical photoconductive drum.

6. A method according to claim 1, wherein the toner contains 1 to 10 parts by weight of the colorant per 100 parts by weight of the binder resin.

7. A method according to claim 1, wherein the developer is a product prepared by attaching 0.05 to 3 parts by weight of fine particles of the additive to 100 parts by weight of the particles of the toner.

8. A method according to claim 1, wherein the fine particles of the additive have a positive tribo-electrified value when measured by a blow-off method.

9. A method according to claim 1, wherein the fine particles of the additive are those produced by surface-treatment of an inorganic fine powder with at least one member selected from the group consisting of aminosilane, silicone oil having an amine in the side chain, a silane coupling agent and a titanium coupling agent.

10. A method according to claim 1, wherein the fine particles of the additive are formed of at least one member selected from the group consisting of alumina, zinc oxide and magnetite.

11. A method according to claim 1, wherein the fine particles of the additive have an average particle diameter of 500 nm or less.