Color image forming apparatus with multiple development units supported by a rotatable carriage

A color image forming apparatus comprising:

• a plurality of development units, each development unit having a toner for a different color and a developing member;
• a carriage for supporting the plurality of development units so as to be attachable/removable with respect to an apparatus main body;
• a carriage driving system for rotating the carriage so as to move the plurality of development units sequentially and switch them between an image forming position and a waiting position;
• a unit positioning system for positioning the development unit at a normal position with respect to the apparatus main body in the image forming position;
• a carriage positioning system for positioning the carriage at a normal position with respect to the apparatus main body;
• and
• a transfer system for transferring a toner image formed by the plurality of development units onto a printing medium;
• wherein the unit positioning system and the carriage positioning system both comprise a pin reciprocating in a direction parallel to a rotation axis of the carriage.

A color image forming apparatus comprising:

• a plurality of development units, each development unit having a toner for a different color and a developing member;
• a carriage for supporting the plurality of development units so as to be attachable/removable with respect to an apparatus main body;
• a carriage driving system for rotating the carriage so as to move the plurality of development units sequentially and switch them between an image forming position and a waiting position;
• a transfer system for transferring a toner image formed by the plurality of development units onto a printing medium;
• a carriage position detecting portion formed integrally with the carriage in an outermost peripheral portion of one of left and right ends of the carriage;
• a position detection sensor for detecting the carriage position detecting portion;
• and
• a unit detecting portion formed integrally with the development unit so as to be located at substantially the same distance from a rotation center of the carriage as the carriage position detecting portion.

A color image forming apparatus comprising:

• a plurality of development units, each development unit having a toner for a different color and a developing member;
• a carriage for supporting the plurality of development units so as to be attachable/removable with respect to an apparatus main body;
• a carriage driving system for rotating the carriage so as to move the plurality of development units sequentially and switch them between an image forming position and a waiting position;
• and
• a transfer system for transferring a toner image formed by the plurality of development units onto a printing medium;
• wherein the carriage comprises left and right carriage side plates that can position the development unit substantially and a hollow pipe member that joins the left and right carriage side plates, and
• the pipe member comprises two-divided sheet-like pipe element members.

A color image forming apparatus comprising:

• a plurality of development units, each development unit having a toner for a different color and a developing member;
• a carriage for supporting the plurality of development units so as to be attachable/removable with respect to an apparatus main body;
• a carriage driving system for rotating the carriage so as to move the plurality of development units sequentially and switch them between an image forming position and a waiting position;
• a transfer system for transferring a toner image formed by the plurality of development units onto a printing medium;
• a unit feeder terminal that is provided on an end face of the development unit perpendicular to a rotation axis of the carriage, for supplying a voltage or an electric current necessary for an image formation to the development unit;
• and
• a main body feeder terminal that is provided in the apparatus main body, for supplying electricity by contacting the unit feeder terminal directly when the development unit is in the image forming position;
• wherein the development unit is supported inside the carriage so as to be capable of reciprocating in a direction parallel to the rotation axis of the carriage.

A color image forming apparatus comprising:

• a plurality of development units, each development unit having a toner for a different color, a developing member and a unit feeder terminal for supplying a voltage or an electric current necessary for an image formation;
• a carriage for supporting the plurality of development units so as to be attachable/removable with respect to an apparatus main body;
• a carriage driving system for rotating the carriage so as to move the plurality of development units sequentially and switch them between an image forming position and a waiting position;
• and
• a transfer system for transferring a toner image formed by the plurality of development units onto a printing medium;
• wherein the apparatus comprises a charge eliminating member for eliminating a residual electric charge in the development unit by contacting the unit feeder terminal directly when the development unit is located out of the image forming position.