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.

An image forming apparatus includes an electrophotographic photoreceptor that includes a conductive substrate, an undercoat layer provided on the conductive substrate, containing a binder resin and an electron transport material, and satisfying Expression 1-1, and a photosensitive layer provided on the undercoat layer, a charging device that charges a surface of the electrophotographic photoreceptor, an electrostatic latent image forming device that forms an electrostatic latent image on the charged surface of the electrophotographic photoreceptor, a developing device that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image, and a transfer device that transfers the toner image to a surface of a recording medium, in which a moving time of an outer peripheral surface of the electrophotographic photoreceptor, required from charging performed by the charging device to development performed by the developing device, is 90 msec or longer, Expression 1-1: 0.20E.sub.F1E.sub.LUMO10.60 (in Expression 1-1, E.sub.F1 represents a Fermi level of the undercoat layer, and E.sub.LUMO1 represents an energy level of LUMO of the undercoat layer).

An image forming apparatus includes an electrophotographic photoreceptor that includes a conductive substrate, an undercoat layer provided on the conductive substrate, containing a binder resin and an electron transport material, and satisfying Expression 1-1, and a photosensitive layer provided on the undercoat layer, a charging device that charges a surface of the electrophotographic photoreceptor, an electrostatic latent image forming device that forms an electrostatic latent image on the charged surface of the electrophotographic photoreceptor, a developing device that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image, and a transfer device that transfers the toner image to a surface of a recording medium, in which a moving time of an outer peripheral surface of the electrophotographic photoreceptor, required from charging performed by the charging device to development performed by the developing device, is 90 msec or longer,

0.20E.sub.F1E.sub.LUMO10.60Expression 1-1:

(in Expression 1-1, E.sub.F1 represents a Fermi level of the undercoat layer, and E.sub.LUMO1 represents an energy level of LUMO of the undercoat layer).

According to one example, there is provided apparatus for detecting a fault in a printing system. The apparatus comprises a monitoring module to determine the length of a portion of an imaging member as the imaging member rotates; and indicate a fault condition when the determined length is different to a reference length.

An image forming method includes charging operation a surface of the electrophotographic photoreceptor that does not contain lubricant particles in a region of 30% from a surface of an outermost surface layer with respect to a film thickness of the outermost surface layer or contains 5% by mass or less of the lubricant particles with respect to an entirety of the region; forming an electrostatic latent image; developing the electrostatic latent image with a developer to form a toner image; transferring the toner image to a surface of a recording medium; and cleaning the surface of the electrophotographic photoreceptor by bringing a cleaning blade into contact with the surface after the toner image is transferred, wherein a dynamic friction coefficient in a contact portion between the electrophotographic photoreceptor and the cleaning blade is 0.2 or greater and 0.6 or less.