Image forming apparatus method and developing device to obtain a stable image density

An image forming apparatus, comprising:

• a latent image bearing member having a potential thereon;
• and
• a developing device configured to perform a two-level developing operation with a one-component developer including toner particles, the developing device including,
• a conveyor member configured to convey the one-component developer to a developing region where part of the developer-bearing member is closely spaced next to a part of the latent image bearing member;
• a thin layer forming device configured to form the one-component developer on the conveyor member into a uniform thin layer having a height corresponding to 1 to 1.5 times a diameter of the toner particles of the one-component developer.

An image forming apparatus, comprising:

• means for bearing a latent image including image areas, at least some of said image areas having different image potential values thereon;
• and
• means for performing a two-level developing operation using a one-component developer including toner particles, the two-level developing operation performing means including,
• means for conveying the one-component developer from a one-component developer supply and to deliver the one-component developer with a predetermined amount of charge to a developing region where a portion of the means for conveying is closely spaced from and opposed to a portion of the means for bearing a latent image,
• means for forming a uniform thin layer of the one-component developer on the means for conveying prior to the one-component developer with the predetermined amount of charge being delivered to the developing region, and
• means for applying a developing bias voltage to the means for conveying when the two-level developing operation is performed to move at least some of the one-component developer with a predetermined charge adhering to the portion of the means for conveying to the portion of the means for bearing a latent image to form saturated amounts of the one-component developer on the image areas of the portion of the means for bearing a latent image, wherein the saturated amounts do not change with increases of the image potential above a predetermined threshold value to provide an image having a density determined by the saturated amounts.

An image forming apparatus, comprising:

• means for bearing a latent image having various potential levels thereon at different image areas;
• and
• means for performing a two-level developing operation using a one-component developer including toner particles, the two-level developing operation performing means including,
• means for conveying the one-component developer to a developing region where part of the means for conveying is closely spaced next to the means for bearing a latent image, and
• means for forming the one-component developer on the means for conveying into a uniform thin layer having a height corresponding to 1 to 1.5 times a diameter of the toner particles.

A method for performing a two-level developing operation in an image forming apparatus hang a latent image bearing member having a photoconductive surface with a latent image including image areas, at least some of said image areas having different image potential values thereon and a developing device having a conveyor member, comprising the steps of:

• providing a one-component developer including toner particles;
• forming the one-component developer into a uniform thin layer on the conveyor member;
• providing the one-component developer with a predetermined amount of charge and conveying the one-component developer with a predetermined amount of charge to a developing region with the conveyor member so that a conveyor surface portion of the conveyor member is closely spaced from and opposed to a photoconductive surface portion of the latent image bearing member at the developing region;
• conveyor member is closely spaced from and opposed to a photoconductive surface portion of the latent image bearing member at the developing region;
• applying a developing bias voltage to the conveyor member and causing at least some of the one-component developer with the predetermined amount of charge adhering to the conveyor surface portion to move to the photoconductive surface portion to form saturated amounts of the one-component developer on the image areas of the photoconductive surface portion, wherein the saturated amounts do not change with increases of the image potential above a predetermined threshold value to provide an image having a predetermined density determined by the saturated amounts.