Patent ID: 11966174
Assignee: CANON KABUSHIKI KAISHA
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 4:
5. An electrophotographic image forming apparatus comprising:
an image-bearing member for bearing an electrostatic latent image;
a charging device for primarily charging the image-bearing member;
an exposing device for forming an electrostatic latent image on the image-bearing member that is primarily charged;
a developing member for developing the electrostatic latent image with toner to form a toner image; and
a transferring device for transferring the toner image onto a transfer member,
wherein
the developing member is an electrophotographic member,
the electrophotographic member includes an electro-conductive substrate, an elastic layer on the substrate, and a surface layer on the elastic layer,
the surface layer contains a fine particle and a binder resin,
the surface layer has a thickness of less than 1.0 μm,
the fine particle has an average particle diameter of from 0.1 μm to 0.9 μm,
the fine particle has a volume occupancy of 60 vol % to 99 vol % with respect to 100 vol % of the binder resin in the surface layer,
wherein E1 and E2 satisfy relationships represented by the following formulae (1) and (2):

E1≥1,000 MPa  (1)

200 MPa≥E2≥2 MPa  (2),, where E1 denotes an elastic modulus of the fine particle and E2 denotes an elastic modulus of the binder resin, E1 and E2 being obtained by measurement of force curves with a SPM in a cross-section of a thickness-direction of the surface layer, and, wherein H1 and H2 satisfy relationships represented by the following formulae (3) and (4):

100°≥H1≥50°  (3)

H1−H2≥5°  (4), where H1 denotes an MD-1 hardness, which is measured by bringing a type C indenter into contact with a surface of the surface layer, the surface being opposite to a surface facing the elastic layer, at an indentation depth of 2 mm, and H2 denotes an MD-1 hardness, which is measured by peeling the surface layer from the electrophotographic member to expose a surface of the elastic layer, and bringing the type C indenter into contact with the exposed surface of the elastic layer at an indentation depth of 2 mm.