Electrophotographic photosensitive member, process cartridge, and electrophotographic apparatus
There is provided an electrophotographic photosensitive member having a cylindrical shape, including a plurality of concave portions on a surface thereof, wherein a sum of opening areas of the concave portions is 5% or more and 65% or less based on a total area of a surface layer of the electrophotographic photosensitive member, an average value davg of depths of the concave portions satisfies the following Equation (1), 0.4≤ d avg≤3.0(μm) Equation (1) a sum of opening areas of concave portions having a specific depth d is 95% or more of the sum of the opening areas of the concave portions, an average value Lavg of maximum widths of openings of the concave portions in a circumferential direction of the electrophotographic photosensitive member is 20 μm or more and 200 μm or less, and the electrophotographic photosensitive member has at least one specific region B.
1. An electrophotographic photosensitive member having a cylindrical shape, comprising a plurality of concave portions on a surface thereof,
wherein a sum of opening areas of the concave portions is 5% or more and 65% or less based on a total area of a surface layer of the electrophotographic photosensitive member,
an average value davg of depths of the concave portions satisfies the following Equation (1),
0.4≤ d avg≤3.0(μm) Equation (1)
a sum of opening areas of concave portions having a depth d satisfying the following Equation (2) is 95% or more of the sum of the opening areas of the concave portions,
d avg−0.2≤ d≤d avg+0.2(μm) Equation (2)
an average value Lavg of maximum widths of openings of the concave portions in a circumferential direction of the electrophotographic photosensitive member is 20 μm or more and 200 μm or less, and
the electrophotographic photosensitive member has at least one region B on the surface thereof, where
(band Y0)
a band Y0 is,
when an average value of maximum widths of the openings of the concave portions in an axial direction of the electrophotographic photosensitive member is defined as Wavg,
an annular band including a line LY0 and having a width of 4×Wavg, the line LY0 passing through the center of the electrophotographic photosensitive member in the axial direction as a central line,
(line X0)
a line X0 is,
(i) when two or more shallow concave portions of which 50% or more of an opening area is included in the band Y0 and a depth is 0.5×davg or less are continuously present in the band Y0,
a line in the axial direction of the electrophotographic photosensitive member, passing through a central point of a line segment and being orthogonal to the band Y0, the line segment connecting deepest positions of two concave portions positioned at both ends in the circumferential direction among the shallow concave portions that are continuously present, or
(ii) when the shallow concave portion of which 50% or more of an opening area is included in the band Y0 and a depth is 0.5×davg or less is present alone in the band Y0,
a line in the axial direction of the electrophotographic photosensitive member, passing through the deepest position of the shallow concave portion and being orthogonal to the band Y0,
(region A)
a region A,
on the surface of the electrophotographic photosensitive member,
which is a tetragonal region of 200 μm square partitioned
by lines in the circumferential direction which are formed in parallel to the line LY0 and arranged to have an interval of 200 μm therebetween, and
lines in the axial direction which are formed in parallel to the line X0 in a region up to a position spaced apart from the line X0 by 35 mm and arranged to have an interval of 200 μm therebetween,
is a tetragonal region in which a ratio of the number of shallow concave portions having a depth of 0.5×davg or less to the total number of concave portions of which 50% or more of the opening area is included in the tetragonal region is 25% or more,
(region B)
a region B is a region formed by an aggregate satisfying the following condition 1 among aggregates of the region A in which any one of four sides or four corners of the region A comes in contact with each other, and
(condition 1)
a length of the aggregate in the axial direction of the electrophotographic photosensitive member is 90% or more based on a maximum length of a concave portion formation region in the axial direction of the electrophotographic photosensitive member,
a length of the aggregate in the circumferential direction of the electrophotographic photosensitive member is 1% or more and 10% or less based on the maximum length of the concave portion formation region in the axial direction of the electrophotographic photosensitive member, and
when quadratic function approximation is performed on a central point of each of the regions A constituting the aggregate by a least squares method in an orthogonal coordinate system in which the axial direction of the electrophotographic photosensitive member is the X direction and the circumferential direction thereof is the Y direction, a correlation coefficient R of an approximate curve is 0.5 or more.
2. The electrophotographic photosensitive member according to claim 1 , wherein the correlation coefficient R of the region B is 0.7 or more.
3. The electrophotographic photosensitive member according to claim 1 , wherein a length of the region B in the circumferential direction is 3% or more and 7% or less based on the maximum length of the concave portion formation region in the axial direction of the electrophotographic photosensitive member.
4. An electrophotographic photosensitive member having a cylindrical shape, comprising a plurality of concave portions on a surface thereof,
wherein a sum of opening areas of the concave portions is 5% or more and 65% or less based on a total area of a surface layer of the electrophotographic photosensitive member,
an average value davg of depths of the concave portions satisfies the following Equation (1),
0.4≤ d avg≤3.0(μm) Equation (1)
a sum of opening areas of concave portions having a depth d satisfying the following Equation (2) is 95% or more of the sum of the opening areas of the concave portions,
d avg−0.2≤ d≤d avg+0.2(μm) Equation (2)
an average value Lavg of maximum widths of openings of the concave portions in a circumferential direction of the electrophotographic photosensitive member is 20 μm or more and 200 μm or less, and
the electrophotographic photosensitive member has at least one arc shaped region formed by an aggregate satisfying the following condition 1 on the surface of the electrophotographic photosensitive member:
(condition 1)
the aggregate is an aggregate of shallow concave portions having a depth of 0.5×davg or less,
a length of the aggregate in the axial direction of the electrophotographic photosensitive member is 90% or more based on a maximum length of a concave portion formation region in the axial direction of the electrophotographic photosensitive member,
a length of the aggregate in the circumferential direction of the electrophotographic photosensitive member is 1% or more and 10% or less based on the maximum length of the concave portion formation region in the axial direction of the electrophotographic photosensitive member, and
when quadratic function approximation is performed on a central point of each of the shallow concave portion constituting the aggregate by a least squares method in an orthogonal coordinate system in which the axial direction of the electrophotographic photosensitive member is the X direction and the circumferential direction thereof is the Y direction, a correlation coefficient R of an approximate curve is 0.5 or more.
5. A process cartridge integrally supporting an electrophotographic photosensitive member and a cleaning unit having a cleaning blade disposed to come in contact with the electrophotographic photosensitive member, and detachably attached to a main body of an electrophotographic apparatus, the electrophotographic photosensitive member having a cylindrical shape and comprising a plurality of concave portions on a surface thereof,
wherein a sum of opening areas of the concave portions is 5% or more and 65% or less based on a total area of a surface layer of the electrophotographic photosensitive member,
an average value davg of depths of the concave portions satisfies the following Equation (1),
0.4≤ d avg≤3.0(μm) Equation (1)
a sum of opening areas of concave portions having a depth d satisfying the following Equation (2) is 95% or more of the sum of the opening areas of the concave portions,
d avg−0.2≤ d≤d avg+0.2(μm) Equation (2)
an average value Lavg of maximum widths of openings of the concave portions in a circumferential direction of the electrophotographic photosensitive member is 20 μm or more and 200 μm or less, and
the electrophotographic photosensitive member has at least one region B on the surface thereof, where
(band Y0)
a band Y0 is,
when an average value of maximum widths of the openings of the concave portions in an axial direction of the electrophotographic photosensitive member is defined as Wavg,
an annular band including a line LY0 and having a width of 4×Wavg, the line LY0 passing through the center of the electrophotographic photosensitive member in the axial direction as a central line,
(line X0)
a line X0 is,
(i) when two or more shallow concave portions of which 50% or more of an opening area is included in the band Y0 and a depth is 0.5×davg or less are continuously present in the band Y0,
a line in the axial direction of the electrophotographic photosensitive member, passing through a central point of a line segment and being orthogonal to the band Y0, the line segment connecting deepest positions of two concave portions positioned at both ends in the circumferential direction among the shallow concave portions that are continuously present, or
(ii) when the shallow concave portion of which 50% or more of an opening area is included in the band Y0 and a depth is 0.5×davg or less is present alone in the band Y0,
a line in the axial direction of the electrophotographic photosensitive member, passing through the deepest position of the shallow concave portion and being orthogonal to the band Y0,
(region A)
a region A,
on the surface of the electrophotographic photosensitive member,
which is a tetragonal region of 200 μm square partitioned
by lines in the circumferential direction which are formed in parallel to the line LY0 and arranged to have an interval of 200 μm therebetween, and
lines in the axial direction which are formed in parallel to the line X0 in a region up to a position spaced apart from the line X0 by 35 mm and arranged to have an interval of 200 μm therebetween,
is a tetragonal region in which a ratio of the number of shallow concave portions having a depth of 0.5×davg or less to the total number of concave portions of which 50% or more of the opening area is included in the tetragonal region is 25% or more,
(region B)
a region B is a region formed by an aggregate satisfying the following condition 1 among aggregates of the region A in which any one of four sides or four corners of the region A comes in contact with each other, and
(condition 1)
a length of the aggregate in the axial direction of the electrophotographic photosensitive member is 90% or more based on a maximum length of a concave portion formation region in the axial direction of the electrophotographic photosensitive member,
a length of the aggregate in the circumferential direction of the electrophotographic photosensitive member is 1% or more and 10% or less based on the maximum length of the concave portion formation region in the axial direction of the electrophotographic photosensitive member, and
when quadratic function approximation is performed on a central point of each of the regions A constituting the aggregate by a least squares method in an orthogonal coordinate system in which the axial direction of the electrophotographic photosensitive member is the X direction and the circumferential direction thereof is the Y direction, a correlation coefficient R of an approximate curve is 0.5 or more.