Electrophotographic image formation process and apparatus

An image formation method for forming a color image by using a contact type nonmagnetic one-component developing device in accordance with an electrophotographic process, characterized in that, inside said developing device, a flat sheet-like blade made of a metal flexible member and having a distal end thereof chamfered is used as a toner layer thickness-limiting blade, and a toner having a glass transition point of 55 to 70° C., a weight average particle diameter of 6.0 to 10.0 μm, and containing up to 20 number % of particles having particle diameters of 5 μm or below, is used as a developer,

• wherein the surface coarseness of said chamfered portion of said toner layer thickness-limiting blade is not greater than 3 μm when the thickness of said blade is 1 μm.

An image formation apparatus for forming a color image, including a contact type nonmagnetic one-component developing device, characterized in that said developing device has a flat sheet-like blade made of a metal flexible member and having a distal end portion thereof chamfered, as a toner layer thickness-limiting blade for limiting a developer layer thickness on a developing roller provided thereto, and a toner having a glass transition point of 55 to 70° C. and a weight average particle diameter of 6.0 to 10.0 μm, and containing up to 20 number % of particles having particle diameters of 5 μm or below is used as said developer stored in said developing device.

An image formation apparatus for forming a color image, including a contact type nonmagnetic one-component developing device, characterized in that said developing device has a flat sheet-like blade made of a metal flexible member and having a distal end portion thereof chamfered, as a toner layer thickness-limiting blade for limiting a developer layer thickness on a developing roller provided thereto, and a toner having a glass transition point of 55 to 70° C. and a weight average particle diameter of 6.0 to 10.0 μm, and containing up to 20 number % of particles having particle diameters of 5 μm or below is used as said developer stored in said developing device,

• wherein the surface coarseness of said chamfered portion of said toner layer thickness-limiting blade is not greater than 3 μm when the thickness of said blade is 1 mm.

An image formation method for forming a color image by using a contact type nonmagnetic one-component developing device in accordance with an electrophotographic process, characterized in that, inside said developing device, a flat sheet-like blade made of a metal flexible member and having a distal end thereof chamfered is used as a toner layer thickness-limiting blade, and a toner having a glass transition point of 55 to 70° C., a weight average particle diameter of 6.0 to 10.0 μm, and containing up to 20 number % of particles having particle diameters of 5 μm or below, is used as a developer,

• wherein said chamfered portion of said toner layer thickness-limiting blade satisfies the following relation when the chamfer distance of said blade in the thickness-wise direction is h1 and the chamfer distance of said blade in the width-wise direction is h2:
• 1≦h2/h1≦5.

An image formation apparatus for forming a color image, including a contact type nonmagnetic one-component developing device, characterized in that said developing device has a flat sheet-like blade made of a metal flexible member and having a distal end portion thereof chamfered, as a toner layer thickness-limiting blade for limiting a developer layer thickness on a developing roller provided thereto, and a toner having a glass transition point of 55 to 70° C. and a weight average particle diameter of 6.0 to 10.0 μm, and containing up to 20 number % of particles having particle diameters of 5 μm or below is used as said developer stored in said developing device,

• wherein said chamfered portion to said toner layer thickness-limiting blade satisfies the following relation when the chamfer distance of said blade in the thickness-wise direction is h1 and the chamfer distance of said blade in the width-wise direction is h2:
• 1≦h2/h1≦5.