Developing member, electrophotographic process cartridge, and electrophotographic image forming apparatus

An electrophotographic process cartridge to be removably mounted onto a main body of an electrophotographic image forming apparatus,

• the electrophotographic process cartridge comprising a developing member,
• wherein the developing member includes an electro-conductive substrate and an electro-conductive layer on the substrate,
• wherein an outer surface of the developing member includes a first region, a second region, and a third region,
• wherein, when surface potentials of the first region, the second region, and the third region are measured with a scanning probe microscope provided with a probe by applying a voltage of 4.5 V to the probe under an environment having a temperature of 23° C. and a relative humidity of 50%, the probe being disposed so that distances between the probe and surfaces of the first, second and third regions, are 90 nm, and measured surface potentials of the first, the second and the third regions are defined as V1, V2, and V3, respectively,
• V1 is −0.70 V to −0.50 V;
• V1 and V2 satisfy a relationship of 1.30≤V1/V2≤25.00, and
• V3 is 0.00 V to 0.50 V, and
• wherein the developing member has a portion in which the first region, the second region, and the third region are adjacent to each other in this order.

An electrophotographic image forming apparatus comprising a developing member,

• the developing member comprising:
• an electro-conductive substrate;
• and
• an electro-conductive layer on the substrate,
• wherein an outer surface of the developing member includes a first region, a second region, and a third region,
• wherein, when surface potentials of the first region, the second region, and the third region are measured with a scanning probe microscope provided with a probe by applying a voltage of 4.5 V to the probe under an environment having a temperature of 23° C. and a relative humidity of 50%, the probe being disposed so that distances between the probe and surfaces of the first, the second and the third regions are 90 nm, and measured surface potential of the first, the second and the third regions are defined as V1, V2, and V3, respectively,
• V1 is −0.70 V to −0.50 V;
• V1 and V2 satisfy a relationship of 1.30≤V1/V2≤25.00, and
• V3 is 0.00 V to 0.50 V, and
• wherein the developing member has a portion in which the first region, the second region, and the third region are adjacent to each other in this order.