Process cartridge and electrophotographic apparatus
The process cartridge includes an electrophotographic photosensitive member having a first support and a photosensitive layer; and a charging member. In the photosensitive member when an electric current is measured which flows when a voltage is applied to a surface while being varied, a gradient a 1 of a low electric field region and a gradient a 2 of a high electric field region satisfy a 2 /a 1 ≥1.50, in a graph. The charging member includes a second support having an electroconductive outer surface, and a second electroconductive layer including a matrix and a plurality of domains being dispersed in the matrix, at least a portion of the domain is exposed to an outer surface which includes at least the matrix and at least a portion of the domain, and a volume resistivity ρ M of the matrix is 1.00×10 5 times or higher of a volume resistivity ρ D of the domain.
1. A process cartridge detachably attachable to a main body of an electrophotographic apparatus, the process cartridge comprising:
an electrophotographic photosensitive member; and
a charging member,
wherein the electrophotographic photosensitive member comprises a first support and a photosensitive layer,
when an electric current is measured which flows when a voltage is applied to a surface of the electrophotographic photosensitive member while being varied, there exists a point at which gradients change, in a graph in which a horizontal axis is a square root of an electric field strength E [V/m] in the photosensitive layer, and a vertical axis is a common logarithm of the electric current, and
when a gradient of the graph is represented by a 1 , in a region in which the electric field strength is smaller than that of the point at which the gradients change, and a gradient of the graph is represented by a 2 , in a region in which the electric field strength is larger than that of the point at which the gradients change, a 2 /a 1 is 1.50 or larger; and
the charging member comprises a second support having an electroconductive outer surface, and a second electroconductive layer provided on the outer surface of the second support, wherein
the second electroconductive layer comprises a matrix containing a first rubber, and a plurality of domains that are dispersed in the matrix, wherein
the domain comprises a second rubber and an electron conducting agent,
at least a portion of the domain is exposed to an outer surface of the charging member, and
the outer surface of the charging member comprises at least the matrix and at least a portion of the domain, wherein
when a volume resistivity of the matrix is represented by ρ M [Ω·cm] and a volume resistivity of the domain is represented by ρ D [Ω·cm], ρ M is 1.0×10 5 times or higher of ρ D .
2. The process cartridge according to claim 1 , wherein in the electrophotographic photosensitive member, the gradients a 2 and a 1 satisfy a 2 /a 1 ≥1.80.
3. The process cartridge according to claim 2 , wherein in the electrophotographic photosensitive member, the gradients a 2 and a 1 satisfy a 2 /a 1 ≥2.20.
4. The process cartridge according to claim 1 , wherein in the electrophotographic photosensitive member, a point at which the gradients change exists in a range in which the square root E* 0.5 of the electric field strength is 3000 [(V/m) 0.5 ] or larger and 9000 [(V/m) 0.5 ] or smaller.
5. The process cartridge according to claim 4 , wherein in the electrophotographic photosensitive member, the point at which the gradients change exists in a range in which the square root E* 0.5 of the electric field strength is 5000 [(V/m) 0.5 ] or larger and 7000 [(V/m) 0.5 ] or smaller.
6. The process cartridge according to claim 1 , wherein in the electrophotographic photosensitive member, the gradient a 2 is 0.00070 or larger and 0.00090 or smaller.
7. The process cartridge according to claim 1 , wherein in the electrophotographic photosensitive member, the photosensitive layer contains a phthalocyanine pigment as a charge generation substance.
8. The process cartridge according to claim 1 , wherein in the charging member, a volume resistivity of the matrix is higher than 1.0×10 12 [Ω·cm].
9. The process cartridge according to claim 1 , wherein the gradients a 2 and a 1 of the electrophotographic photosensitive member and an arithmetic mean value D m [μm] of inter-domain distances of the charging member satisfy D m ×a 1 /a 2 ≤10.
10. The process cartridge according to claim 1 , wherein in the charging member, an arithmetic mean value D m of inter-domain distances of the charging member is 40 [μm] or smaller.
11. An electrophotographic apparatus comprising:
an electrophotographic photosensitive member; and
a charging member,
wherein the electrophotographic photosensitive member comprises a first support and a photosensitive layer,
when an electric current is measured which flows when a voltage is applied to a surface of the electrophotographic photosensitive member while being varied, there exists a point at which gradients change, in a graph in which a horizontal axis is a square root of an electric field strength E [V/m] in the photosensitive layer, and a vertical axis is a common logarithm of the electric current, and
when a gradient of the graph is represented by a 1 , in a region in which the electric field strength is smaller than that of the point at which the gradients change, and a gradient of the graph is represented by a 2 , in a region in which the electric field strength is larger than that of the point at which the gradients change, a 2 /a 1 is 1.50 or larger; and
the charging member comprises a second support having an electroconductive outer surface, and a second electroconductive layer provided on the outer surface of the second support, wherein
the second electroconductive layer comprises a matrix containing a first rubber, and a plurality of domains that are dispersed in the matrix, wherein
the domain comprises a second rubber and an electron conducting agent,
at least a portion of the domain is exposed to an outer surface of the charging member, and
the outer surface of the charging member comprises at least the matrix and at least a portion of the domain, wherein
when a volume resistivity of the matrix is represented by ρ M [Ω·cm] and a volume resistivity of the domain is represented by ρ D [Ω·cm], ρ M is 1.0×10 5 times or higher of ρ D .