Image forming apparatus for maintaining positions of photosensitive drums relative to casing

摘要

An image forming apparatus includes a cartridge and a casing. The cartridge includes a photosensitive drum, a developing roller, a developing frame, and a drum frame. The developing frame is movable between a contact position and a separated position. A separating member provided on the drum frame acts on the developing frame, so that a reaction force is exerted in a reaction force direction. The casing includes a positioning member, an urging member, and a separation pressing member. The positioning member has a first surface and a second surface. The urging member is configured to urge an end portion of the photosensitive drum toward the positioning member in an urging direction. The first surface is configured to support the end portion at a position downstream of the urging direction. The second surface is configured to support the end portion at a portion downstream of the reaction force direction.

主权项

1. An image forming apparatus comprising:
a cartridge including:
a photosensitive drum configured to rotate about an axis line extending in an axial direction and having an end portion in the axial direction;a developing roller disposed in confrontation with the photosensitive drum;a developing frame rotatably supporting the developing roller and movable between a contact position where the photosensitive drum contacts the developing roller and a separated position where the photosensitive drum is separated from the developing roller; anda drum frame supporting the photosensitive drum, the drum frame having a separating member configured to act on the developing frame so as to dispose the developing frame at the separated position, the separating member acting on the developing frame, so that a reaction force is exerted on the separating member in a reaction force direction; and a casing configured to detachably receive the cartridge, the casing including:
a positioning member configured to position the end portion of the photosensitive drum, the positioning member having a first surface and a second surface extending in a direction different from that of the first surface,an urging member configured to urge the end portion of the photosensitive drum toward the positioning member in an urging direction; anda separation pressing member configured to press the separating member so as to let the separating member act on the developing frame, wherein the first surface is configured to support the end portion of the photosensitive drum at a position downstream of the urging direction, wherein the second surface is configured to support the end portion of the photosensitive drum at a position downstream of the reaction force direction, and wherein the urging member includes a conductive member made of conductive material, the conductive member being configured to contact the end portion of the photosensitive drum so as to be in electrical connection with the photosensitive drum.