Process unit having mounting guides and protective covers

An electrophotographic image forming apparatus comprising:

• a main body;
• a photosensitive drum;
• a developing unit which is detachably mounted in said main body by insertion generally along a mounting direction, said developing unit providing a pair of first protrusions and a pair of second protrusions, each of the protrusions protruding in a direction perpendicular to the mounting direction;
• a pair of first guides provided on the main body of the apparatus for engaging said pair of first protrusions;
• and
• a pair of second guides provided on the main body of the apparatus for engaging said pair of second protrusions, said first and second guides guiding said developing unit to a position facing said photosensitive drum, said pair of first guides having a portion for momentarily catching said pair of first protrusions as the developing unit is being mounted to the main body of the apparatus and a lower portion extending downwardly from the portion for momentarily catching, thereby alleviating any impact to the developing unit during the mounting.

An electrophotographic image forming apparatus comprising:

• a main body;
• a photosensitive drum;
• a developing unit which is detachably mounted in said main body by insertion generally along a mounting direction for the developing unit which is perpendicular to an axis of said photosensitive drum, said developing unit providing a pair of first protrusions and a pair of second protrusions, wherein each of the first and second protrusions protrudes in a direction perpendicular to the mounting direction for the developing unit;
• a pair of first guides provided on said main body for guiding said pair of first protrusions, each of said first guides having a portion for momentarily catching said first protrusions as the developing unit is being mounted to the main body of the apparatus and a lower portion which extends downwardly from said portion for momentarily catching;
• and
• a pair of second guides provided on the main body of the apparatus and extending to a position facing said photosensitive drum for guiding said second protrusions, each second guide including a inclined portion having a shape which is substantially that of an arc centered on the portion of a respective one of said first guides for momentarily catching said first protrusions.

An image forming apparatus comprising:

• a body of the apparatus;
• a photosensitive drum;
• and
• a developing unit, said developing unit being demountable with respect to the body of the apparatus and including a developing sleeve and a shutter member, said shutter member constituting a part of a housing of the developing unit, the shutter member moving to a first position for covering a peripheral surface of the developing sleeve when the developing unit is being demounted from the body of the apparatus, and the shutter member retracting from the first position and moving to a second position for covering a portion of the photosensitive drum when the developing unit is being mounted to the body of the apparatus so that the photosensitive drum is protected by the shutter member in its second position when the body of the apparatus is being opened.

An image forming apparatus comprising:

• a body of the apparatus;
• a photosensitive member unit having a first shutter member, said first shutter member constituting a part of a housing of the photosensitive member unit and being movably attached to the housing to cover a portion of the photosensitive member;
• and
• a developing unit, said developing unit being detachable with respect to the body of the apparatus and providing a developing sleeve and a second shutter member, said second shutter member constituting a part of a housing of the developing unit;
• wherein, as the developing unit is being mounted to the body of the apparatus, said first shutter member retracts from its position for covering a portion of the photosensitive member to open a developing region of the photosensitive member and, at the same time, said second shutter member retracts from its position for covering the developing sleeve to its position for covering a portion of the photosensitive member;
• and
• wherein, as the developing unit is being demounted from the body of the apparatus, said first shutter member returns to its position for covering a portion of the photosensitive member and said second shutter member returns to its position for covering the developing sleeve.