In an example of a method for reducing contamination, a purified imaging oil is formed by filtering an imaging oil through an imaging oil filter, and then filtering the imaging oil through a polar absorbent filter. A surface of an amorphous silicon photoconductor of a liquid electrophotographic printing apparatus is maintained by periodically applying the purified imaging oil to the amorphous silicon photoconductor.

An image forming apparatus includes a photoconductor, a charging member, a voltage applier, a storage unit, a current detector, a characteristic deriver and a voltage setter. The storage unit stores in advance relationship information representing a relationship between an electrical characteristic of discharge products adhering to the surface and a proper inter-peak voltage value capable of properly charging the surface. The current detector detects a current value of a current flowing from the charging member to the photoconductor. The characteristic deriver derives the electrical characteristic of the discharge products adhering to the surface on the basis of an oscillating voltage applied to the charging member by the voltage applier and the current value. The voltage setter sets the proper inter-peak voltage value corresponding to the electrical characteristic derived by the characteristic deriver in the relationship information as the inter-peak voltage value of the alternating-current voltage.

A toner includes a plurality of toner particles each including a toner mother particle and an external additive adhering to a surface of the toner mother particle. The external additive includes hydrotalcite particles. The hydrotalcite particles have a number average primary particle diameter of at least 80 nm and no greater than 1,000 nm. The hydrotalcite particles have a volume resistivity of no greater than 1.010.sup.5 .Math.cm. An amount of the hydrotalcite particles is at least 0.5 parts by mass and no greater than 3.0 parts by mass relative to 100 parts by mass of the toner mother particles.

The present disclosure relates to an electrophotographic photoreceptor which can suppress occurrence of abnormalities such as peeling or falling off of a film from a substrate end portion in a film formation step of a surface layer and maintain and reproduce a stable printing quality even in a use stage after productization, and an image forming apparatus including the same. An electrophotographic photoreceptor includes a cylindrical substrate including a chamfered face located between an substrate outer circumferential surface and a substrate end face, and a surface layer located on the outer circumferential surface. The substrate outer circumferential surface includes a first uneven portion. The chamfered face includes a second uneven portion and a third uneven portion located on a surface of the second uneven portion. A surface roughness Sa of the second uneven portion is larger than a surface roughness Sa of the third uneven portion.

An electrophotographic photosensitive member includes an undercoat layer, a charge generation layer, and a charge transport layer in this order. The undercoat layer contains a cured product of a composition containing an electron transport material, a particle having an average primary particle size of 10 nm or more, and a silicone oil. A content of the particle in the undercoat layer is 3% by mass or more and 20% by mass or less. A content of the silicone oil in the undercoat layer is 0.01% by mass or more and 10% by mass or less relative to the content of the particle.

In an example of a method for reducing contamination, a purified imaging oil is formed by filtering an imaging oil through an imaging oil filter, and then filtering the imaging oil through a polar absorbent filter. A surface of an amorphous silicon photoconductor of a liquid electrophotographic printing apparatus is maintained by periodically applying the purified imaging oil to the amorphous silicon photoconductor.

An average value of a hydrogen content ratio of a surface layer made of hydrogenated amorphous carbon is set to be 0.40 or less and a maximum value of an sp.sup.2 bonding ratio in an outermost surface region of the surface layer made of the hydrogenated amorphous carbon is set to be 0.50 or less.

A cylindrical base body of the disclosure includes an outer peripheral surface and an end surface which is connected to the outer peripheral surface. The outer peripheral surface includes a first inclined surface which is inclined inwardly toward the end surface, the end surface includes a second inclined surface which is inclined inwardly toward the outer peripheral surface and is connected to the first inclined surface, and a connecting portion of the first inclined surface and the second inclined surface has a radiused surface.

An image forming apparatus includes a photoconductor, a charging member, a voltage applier, a storage unit, a current detector, a characteristic deriver and a voltage setter. The storage unit stores in advance relationship information representing a relationship between an electrical characteristic of discharge products adhering to the surface and a proper inter-peak voltage value capable of properly charging the surface. The current detector detects a current value of a current flowing from the charging member to the photoconductor. The characteristic deriver derives the electrical characteristic of the discharge products adhering to the surface on the basis of an oscillating voltage applied to the charging member by the voltage applier and the current value. The voltage setter sets the proper inter-peak voltage value corresponding to the electrical characteristic derived by the characteristic deriver in the relationship information as the inter-peak voltage value of the alternating-current voltage.

A toner includes a plurality of toner particles each including a toner mother particle and an external additive adhering to a surface of the toner mother particle. The external additive includes hydrotalcite particles. The hydrotalcite particles have a number average primary particle diameter of at least 80 nm and no greater than 1,000 nm. The hydrotalcite particles have a volume resistivity of no greater than 1.010.sup.5 .Math.cm. An amount of the hydrotalcite particles is at least 0.5 parts by mass and no greater than 3.0 parts by mass relative to 100 parts by mass of the toner mother particles.