A process cartridge including a drum cartridge, a developing cartridge, and a waste toner container, is provided. The drum cartridge includes a photosensitive drum including a photosensitive layer and a rotation axis extending in an axial direction, a drum cleaner arranged to contact the photosensitive drum, a cleaner frame configured to accommodate the drum cleaner therein, and a waste toner conveyer tube connected with the cleaner frame. The developing cartridge is movable to be attached to and detached from the drum cartridge and includes a developer roller. The waste toner container is movable to be attached to and detached from the drum cartridge. When the developing cartridge and the waste toner container are attached to the drum cartridge, the waste toner container is connected with the waste toner conveyer tube and is located on an opposite side of the developing cartridge to the photosensitive drum.

A process cartridge has a developing roller, a photosensitive drum, and the frame having a first frame rotatably supporting the developing roller and a second frame rotatably supporting the photosensitive drum. The first frame is movable relative to the second frame between a first position and a second position. The developing roller and the photosensitive drum are in contact at the first position and separated at the second position. A developing roller coupling member, a chip having an electrical contact surface and a separation protrusion with a force receiving surface at the lower end of the frame to receive a force to move the first frame from the first position to the second position. When the first frame is in the first position, a lower end of the force receiving surface is not lower than a lower end of the covering portion.

An electrophotographic photosensitive member includes a support member, an electroconductive layer, and photosensitive layer in this order. The electroconductive layer contains a binder and particles. The particles have a core containing titanium oxide, and a coating layer coating the core and containing titanium oxide doped with niobium or tantalum.

The electrophotographic roller has a surface layer comprising an electro-conductive elastic layer on an electro-conductive substrate. The opening of a bowl-shaped resin particle is exposed on the surface of the electrophotographic roller. The number of contact portions of the convex portion with the glass plate in a square region where a length of a nip in a direction along the circumferential direction of the electrophotographic roller of a nip formed by pressing the roller on the glass plate with a specific load applied as the length of one side and is located at any position in the nip is 8 or more. The average value of the areas of the contact portions is 10 m.sup.2 to 111 m.sup.2. The variation coefficient of the areas of the contact portions and the variation coefficient D of the areas of a plurality of Voronoi regions each including a contact portion satisfy specific relationships.

An imaging system for an electrophotographic image forming device according to one example embodiment includes a movable latch positioned to selectively couple a replaceable toner cartridge and a replaceable imaging unit together such that the toner cartridge and the imaging unit are removable from the image forming device as a single unit and to selectively decouple the toner cartridge and the imaging unit such that the toner cartridge and the imaging unit are separately removable from the image forming device. A controller is configured to actuate the latch to couple the toner cartridge and the imaging unit together in response to the controller detecting an error condition requiring removal of both the toner cartridge and the imaging unit from the image forming device in order to permit removal of the toner cartridge and the imaging unit from the image forming device as a single unit.

An imaging system for an electrophotographic image forming device according to one example embodiment includes a movable latch positioned to selectively couple a replaceable toner cartridge and a replaceable imaging unit together such that the toner cartridge and the imaging unit are removable from the image forming device as a single unit and to selectively decouple the toner cartridge and the imaging unit such that the toner cartridge and the imaging unit are separately removable from the image forming device. A controller is configured to actuate the latch to couple the toner cartridge and the imaging unit together in response to the controller detecting an error condition requiring removal of both the toner cartridge and the imaging unit from the image forming device in order to permit removal of the toner cartridge and the imaging unit from the image forming device as a single unit.

An electrophotographic photosensitive member includes a support member, an undercoat layer, and a photosensitive layer adjacent to the undercoat layer in this order, wherein the undercoat layer contains a polymerized product of a composition including an electron transporting material having a polymerizable functional group, a cross-linking agent, and a thermoplastic resin having a polymerizable functional group, and at least one type of particles selected from the group consisting of resin particles having a hollow structure and rubber particles, wherein a content of the electron transporting material in the undercoat layer is 30% by mass or more with respect to a total mass of the composition, and wherein a content of the at least one type of particles in the undercoat layer is 10% by mass or more and 100% by mass or less with respect to the content of the electron transporting material.

An image forming apparatus, including: a photoconductor; a developing device; a developer storage; a supplier configured to supply developer; an optical sensor; and a controller configured to execute: a developing process of developing an electrostatic latent image on the photoconductor; a usage-amount obtaining process of obtaining a usage amount of the developer; a supplying process of supplying the developer to the developing device every time when the obtained usage amount becomes equal to or greater than a first threshold; and a detecting process of detecting, by the optical sensor, an amount of the developer in the developing device every time when the obtained usage amount becomes equal to or greater than a second threshold larger than the first threshold, and wherein the controller is configured to execute the detecting process in a period different from a period in which the developing process is being executed.

An electrophotographic photoreceptor includes a conductive substrate, an undercoat layer provided on the conductive substrate, a charge generation layer provided on the undercoat layer, a charge transport layer provided on the charge generation layer, and a surface organic protective layer provided on the charge transport layer, in which the charge transport layer has a Young's modulus of 5,500 MPa or greater.

An electrophotographic photoreceptor includes a conductive base body and a multilayered photosensitive layer disposed on the conductive base body and including a charge generation layer and a charge transport layer, wherein the charge transport layer is an uppermost surface layer and contains a charge transport material, a polyester resin, and a compound (T) represented by Formula (T) below, the polyester resin includes a polyester resin (1) including at least one selected from the group consisting of a diol unit (P1) represented by Formula (P1), a diol unit (P2) represented by Formula (P2), a diol unit (P3) represented by Formula (P3), a diol unit (P5) represented by Formula (P5), and a diol unit (P6) represented by Formula (P6), the polyester resin (1) further includes a unit including a biphenyl skeleton, and end groups of the polyester resin (1) do not include fluorine atoms.

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