In an electrophotographic photosensitive member, a circumferential surface has concave portions that are independent one another; each of the concave portions has an opening, a contour of the opening has an apex having an angle α of more than 0° and 90° or less on at least an upstream side of a rotational direction of the electrophotographic photosensitive member, and has a largest width in an axial direction of the electrophotographic photosensitive member of 20 μm or more and 80 μm or less, a width of the contour in the axial direction of the electrophotographic photosensitive member decreasing from a portion having the largest width toward the apex, when viewing each of the concave portions in the axial direction, each of the concave portions has a depth that decreases from a deepest point of each of the concave portions toward the apex.

The present invention relates to an electrophotographic photoreceptor comprising: a conductive support; and a photosensitive layer on the conductive support, wherein the photosensitive layer contains a charge transport substance, a binder resin, and a compound which has a molecular weight of equal to or less than 350, and is represented by General Formula (1).

An electrophotographic photoreceptor includes: a conductive support; and a photosensitive layer which contains an electric charge generating material and an electric charge transport material, wherein a layer configuring a surface of the electrophotographic photoreceptor contains a resin binder, and conductive particles A and B dispersed in the resin binder, the conductive particles A have a single peak and volume resistance ρ1, the conductive particles B have a single peak and volume resistance ρ2, when a particle diameter of the conductive particles A is set to d1, and a particle diameter of the conductive particles B is set to d2, Expression (1) is satisfied, and when the volume resistance of the conductive particles A is set to ρ1, and the volume resistance of the conductive particles B is set to ρ2, Expression (2) is satisfied:

4×d2≦d1≦20×d2  (1)

10×ρ1<ρ2  (2)

An image forming apparatus includes: an image forming unit configured to form an image pattern on a medium, a predetermined image repeatedly appearing in a first cycle in a sub scanning direction in the image pattern; a density detector configured to optically detect a density of the image pattern in the sub scanning direction; a cyclic image detector configured to detect a feature image having a second cycle corresponding to the first cycle in accordance with a result of the detection; and a state determining unit configured to determine whether a cycle depending on an outer circumference of a rotary member included in the image forming apparatus corresponds to the second cycle when the feature image is detected by the cyclic image detector, and determine that a state of the rotary member has deteriorated when the cycle depending on the outer circumference is determined to correspond to the second cycle.

Provided is a photoconductor including a conductive support, an intermediate layer containing metal oxide particles, and a photoconductive layer. The intermediate layer and the photoconductive layer are provided over the conductive support in the order of reciting. An elastic power (We/Wt value) of the intermediate layer is greater than or equal to 20.0% but less than 35.0%. A Martens hardness (HM) of the intermediate layer is greater than or equal to 350 [N/mm.sup.2] but less than 450 [N/mm.sup.2].

A method is described in which a spectrum of a surface of a photoconductor member is obtained using optical spectroscopy; and an extent of oxidation of the surface is determined based on the obtained spectrum.

An electrophotographic photoreceptor includes a conductive substrate and a single-layer photosensitive layer on the conductive substrate. The photosensitive layer includes a binder resin, at least one selected from a hydroxygallium phthalocyanine pigment and a chlorogallium phthalocyanine pigment, a hole transporting material, and an electron transporting material and has a Martens hardness Hm of 170 N/mm.sup.2 or more and 200 N/mm.sup.2 or less.

The present invention relates to an electrophotographic photoreceptor which is a positive charging type electrophotographic photoreceptor comprising a conductive support and a photosensitive layer on the conductive support, wherein the photosensitive layer contains at least a charge generating material, a hole transport material, an electron transport material, and a binder resin in the same layer, and a residual potential VL.sub.1 at a point at which an exposure amount for forming a latent image is 0.3 μJ/cm.sup.2 is equal to or lower than 130 V when an initial surface potential V0 is set to +700 V, exposure with monochromatic light of 780 nm is performed and measurement is performed by a dynamic method.

An electrophotographic photosensitive member including a surface layer containing a charge generating material and a polyester resin is provided. The polyester resin contains a structure having a 12- or higher-membered cycloalkylene group.

An image forming apparatus which forms an image on a medium on the basis of an input image signal includes: an image carrier configured to carry a developed toner image transferred to the medium on a photoreceptor layer; a contact member arranged so as to be in contact with the surface of the photoreceptor layer; a trace pattern generating unit configured to generate a trace pattern indicating specific information on the image forming apparatus; a composition unit configured to add the trace pattern to the image signal; and an acquiring unit configured to acquire information on the thickness of the photoreceptor layer of the image carrier, wherein the trace pattern is used for arranging a plurality of image areas at respective positions, and the trace pattern generating unit is configured to generate the trace pattern with the image area whose size is reduced in accordance with reduction of the thickness of the photoreceptor layer.