A charging member includes a support member, a conductive elastic layer disposed on the support member, and a front surface layer disposed on the conductive elastic layer. Irregularities with a cycle of shorter than 0.1 mm and irregularities with a cycle of 0.1 mm or longer are distributed on an entirety of an outer circumferential surface of the charging member, and satisfy the following conditions of (1) and (2): (1) The irregularities with the cycle of shorter than 0.1 mm have an average height of 5 μm to 8 μm; and (2) The irregularities with the cycle of 0.1 mm or longer have an average height of 6 μm to 30 μm. A half-value width of a maximum frequency value of a height distribution on the outer circumferential surface is 1 μm to 3 μm.

An electrophotographic apparatus comprising an electrophotographic photosensitive member, a charging device and a developing device, wherein the charging device comprises a conductive member arranged to be capable of contacting the electrophotographic photosensitive member, the conductive layer at the outer surface of the conductive member comprises a matrix and a plurality of domains dispersed in the matrix, at least some of the domains are exposed at the outer surface of the conductive member, the matrix has a volume resistivity R1 of larger than 1.00×10.sup.12 Ω.Math.cm, the volume resistivity R1 of the matrix is 1.0×10.sup.5 times or more a volume resistivity R2 of the domains, the developing device comprises the toner comprising a toner particle and a silica fine particle, and a coverage ratio of the toner surface with the silica fine particles is from 62.0% by area to 100.0% by area as determined by X-ray photoelectron spectroscopy.

In a state that a first voltage is applied to a charging member so as to form a surface potential on a region of an image bearing member and a second voltage the same in polarity as the first voltage is applied to a transfer member, a detection unit detects a transfer current in the region of the image bearing member during one rotation of the image hearing member after the region passes through a charging portion, when an absolute value of the surface potential formed on the region immediately before entry into the charging portion is larger than an absolute value of the surface potential formed on the region when it is positioned upstream of a transfer portion and downstream of the charging portion in a rotational direction of the image bearing member.

In a charging roll for electrophotographic equipment, an outer surface layer of an elastic layer includes a binder resin, large-diameter particles having an average particle diameter of 15-50 μm, and small-diameter particles having an average particle diameter of 3-15 μm, a difference in average particle diameter between the large-diameter particles and the small-diameter particles is 10-35 μm, the small-diameter particles are arranged in one layer in the surface layer, the average distance between the small-diameter particles is not more than 1.2 times the average particle diameter of the small-diameter particles, the thickness a of the binder resin covering the large-diameter particles is within the range of 1.5-3.5 μm, the thickness b of the binder resin covering the small-diameter particles is 3.0-6.0 μm, and the thickness b is larger than the thickness a.

In a charging roll for electrophotographic equipment, an outer surface layer of an elastic layer includes a binder resin, large-diameter particles having an average particle diameter of 15-50 μm, and small-diameter particles having an average particle diameter of 3-15 μm, a difference in average particle diameter between the large-diameter particles and the small-diameter particles is 10-35 μm, the small-diameter particles are arranged in one layer in the surface layer, the average distance between the small-diameter particles is not more than 1.2 times the average particle diameter of the small-diameter particles, the thickness a of the binder resin covering the large-diameter particles is within the range of 1.5-3.5 μm, the thickness b of the binder resin covering the small-diameter particles is 3.0-6.0 μm, and the thickness b is larger than the thickness a.

In an image forming apparatus, a bias controller varies one, while keeping the other fixed, of a charging alternating-current frequency, which is the frequency of the charging alternating-current voltage, and a developing alternating-current frequency, which is the frequency of the developing alternating-current voltage. Specifically, in a case where interference fringes appear in a developed image due to interference between the charging and developing alternating-current frequencies, when the recognizable minimum pitch of the interference fringes is A.sub.1 (mm), the width of the variation region of the other frequency is B.sub.1 (Hz), the rotation speed of an image carrying member is C.sub.1 (mm/sec), and the variation speed of the other frequency in the variation region is D.sub.1 (Hz/sec), the bias controller varies the other frequency at a variation speed D.sub.1 that fulfills |D.sub.1|>B.sub.1/(A.sub.1/C.sub.1).

An electrophotographic apparatus comprising an electrophotographic photosensitive member, a charging device and a developing device, wherein the charging device comprises a conductive member arranged to be capable of contacting the electrophotographic photosensitive member, the conductive layer at the outer surface of the conductive member comprises a matrix and a plurality of domains dispersed in the matrix, at least some of the domains are exposed at the outer surface of the conductive member, the matrix has a volume resistivity R1 of larger than 1.0010.sup.12 .Math.cm, the volume resistivity R1 of the matrix is 1.010.sup.5 times or more a volume resistivity R2 of the domains, the developing device comprises the toner comprising a toner particle and a silica fine particle, and a coverage ratio of the toner surface with the silica fine particles is from 62.0% by area to 100.0% by area as determined by X-ray photoelectron spectroscopy.

In a state that a first voltage is applied to a charging member so as to form a surface potential on a region of an image bearing member and a second voltage the same in polarity as the first voltage is applied to a transfer ember, a detection unit detects a transfer current in the region of the image bearing member during one rotation of the image hearing member after the region passes through a charging portion, when an absolute value of the surface potential formed on the region immediately before entry into the charging portion is larger than an absolute value of the surface potential formed on the region when it is positioned upstream of a transfer portion and downstream of the charging portion in a rotational direction of the image bearing member.

A charging device includes a charging member and a cleaning member. The charging member electrically charges a surface of a charging target member and is rotatable while being in contact with the surface of the charging target member. The cleaning member is in contact with a surface of the charging member and removes a foreign object attached to the surface of the charging member. Surface free energy of the surface of the charging member is 5.00 dynes per centimeter or more. A dynamic friction coefficient of the surface of the charging member and a surface of the cleaning member falls within a range from 0.48 to 0.88 both inclusive. The surface free energy and the dynamic friction coefficient satisfy a relation represented by the following expression (1).
E63+69(1) E is the surface free energy in dynes per centimeter, and is the dynamic friction coefficient.

A charging device includes a charging member that includes a conductive elastic layer and a conductive surface layer disposed on an outer circumferential surface of the conductive elastic layer and a cleaning member that includes a support and a foamed elastic layer disposed on an outer circumferential surface of the support and having a higher surface free energy than the conductive surface layer of the charging member and that rotates in contact with the conductive surface layer of the charging member.