Provided is an electrophotographic photosensitive member that suppresses an image defect resulting from its support and is reduced in long-term potential fluctuation. The electrophotographic photosensitive member is an electrophotographic photosensitive member including a support having a cylindrical shape and a photosensitive layer formed on the support, wherein the support has a surface formed of Al and/or an Al alloy, and wherein the IR peak area ratio A of the surface of the support determined by Fourier transform infrared spectroscopy satisfies the following condition: A≥0.50 where the IR peak area ratio A represents a ratio a/z of a peak area “a” in the range of from 1,016 cm.sup.−1 or more to 1,130 cm.sup.−1 or less to a peak area “z” in the range of from 650 cm.sup.−1 or more to 1,130 cm.sup.−1 or less.

An electrophotographic photoreceptor includes an electrically conductive substrate, and a laminate-type photosensitive layer formed on the electrically conductive substrate. An allowable range of a charging voltage Vx to be applied to the electrophotographic photoreceptor by a charging device is V.sub.0−150≤V.sub.x≤V.sub.0+150, and an electrostatic capacitance per unit area of the electrophotographic photoreceptor is 90 pF/cm.sup.2 or more. VO is an initial charging voltage applied to the electrophotographic photoreceptor. Also, an image forming apparatus and an image forming cartridge can be provided with the electrophotographic photoreceptor.

An image carrier unit, insertable into and removable from an apparatus housing, includes: an image carrier; a protection cover removable from and attachable to the image carrier and including a covering portion and a block, the covering portion covering an exposed portion of the image carrier, the block being disposed on a near side in an insertion-removal direction and protruding in a direction crossing the insertion-removal direction; and a surface opposing a far side of the block in the insertion-removal direction, wherein the block is pressed by a protrusion movable toward the apparatus housing.

An electrophotographic apparatus including an electrophotographic photosensitive member, a charging unit, and a developing unit, wherein the charging unit includes a conductive member disposed to be contactable with the electrophotographic photosensitive member, a conductive layer of the conductive member has a matrix-domain structure, at least some of the domains are exposed at the outer surface of the conductive member, the volume resistivity RI of the matrix is greater than 1.00×10.sup.12 Ω.Math.cm and not greater than 1.00×10.sup.17 Ω.Math.cm, the matrix volume resistivity R1 is at least 1.0×10.sup.5-times the domain volume resistivity R2, and the developing unit includes a toner, the toner includes a binder resin-containing toner particle and an external additive, and the external additive contains fine particles of a hydrotalcite compound.

In an electrophotographic photosensitive member, wrinkles have a convex portion in which a linear shape portion having a length of 50 μm or longer exists, the linear shape portion is parallel to any one of L1 to L150 and L1651 to L1800, and each of L1 to L1800 intersects with the convex portion at a plurality of places, and at least two of the places have different intersection angles; and when height information of the wrinkles is subjected to a frequency analysis, and a two-dimensional power spectrum is obtained, a one-dimensional radial distribution function has at least one local maximum value, and when an angular distribution is calculated from the spectrum at a frequency of the local maximum value, the power values have a particular relationship.

In an example, a photosensitive imaging surface is provided by an extended photodiode structure.

There is disclosed a device such as a printer or temperature control device for a printer. The device may comprise a photoreceptor. The device may further comprise a heat exchanger to regulate a temperature of the photoreceptor. The device may further comprise a temperature regulator to measure a temperature of a surface of the photoreceptor and control the heat exchanger based on the measured temperature. The device may further comprise a superior temperature controller to, during a pre-print phase of a print action, inhibit the control of the heat exchanger by the temperature regulator and control the heat exchanger to provide a specified amount of heat exchange.

A fluorine-containing resin particle contains 0 or more and 30 or less carboxyl groups per 10.sup.6 carbon atoms and 0 ppm or more and 3 ppm or less of a basic compound.

Disclosed is a cylindrical electrophotographic photosensitive member having a region A along an outer surface and a region B along the outer surface. In this electrophotographic photosensitive member, the region A is located on an end side in an axial direction of the electrophotographic photosensitive member relative to the region B, the region A has a specific groove provided on the outer surface of the electrophotographic photosensitive member, an area ratio a1 of the groove is 65% to 100%, the region B has specific concave portions provided on the outer surface of the electrophotographic photosensitive member, and an area ratio a2 of the concave portion is 5% to 65%.

The toner has a toner matrix particle containing a crystalline polyester resin. Associated silica including two or more of primary particles is present on the surface of the toner matrix particle. The coverage with associated silica onto the toner matrix particle is 1% or more to 30% or less, and the adherence strength of associated silica to the toner matrix particle is 20% or more to 90% or less.