Reciprocating driving device

A reciprocating driving device comprising:

• a reciprocating moving member supported to be movable in a predetermined first direction and a second direction opposite to the first direction;
• a first rack provided on said reciprocating moving member;
• a second rack provided on said reciprocating moving member;
• first gear means for moving said reciprocating moving member selectively in the first or second direction by rotating in a predetermined first rotational direction and selectively meshing with said first rack or with said second rack;
• second gear means mounted for rotating in a predetermined second rotational direction;
• and
• supporting means for supporting said first gear means so as that said first gear means revolves around said second gear means while meshing with said second gear means;
• wherein said first gear means moves said reciprocating moving member in the first direction while meshing with said first rack, wherein, after said first gear means detaches from an end portion of said first rack, said first gear means revolves around said second gear means until said first gear means meshes with said second rack, wherein said first gear means moves said reciprocating moving member in the second direction while meshing with said second rack, and wherein, after said first gear means detaches from an end portion of said second rack, said first gear means revolves around said second gear means until said first gear means meshes with said first rack.

An image forming apparatus comprising:

• an original mount for mounting an original supported to be movable in a predetermined first direction and a second direction opposite to the first direction;
• a first rack provided on said original mount;
• a second rack provided in said original mount;
• first gear means for selectively moving said original mount in the first or the second direction by rotating in a predetermined first rotational direction and selectively meshing with said first rack or said second rack;
• second gear means rotating in a predetermined second rotational direction;
• supporting means for supporting said first gear means so that said first gear means is revolvable around said second gear means while meshing with said second gear;
• mounting means for mounting a sheet;
• feed means for feeding the sheet mounted on said mounting means;
• exposure means for sequentially exposing an image of an original mounted on said original mount in accordance with the movement of said original mount in the first direction;
• and
• image forming means for forming the image of the original exposed by said exposure means onto the sheet fed by said feed means,
• wherein said first gear means moves said original mount in the first direction while meshing with said first rack, wherein, after said first gears means detaches from an end portion of said first rack, said first gear means revolves around said second gear means until said first gear means meshes with said second rack, wherein said first gear means moves said original mount in the second direction while meshing with said second rack, and wherein after said first gear means detaches from an end portion of said second rack, said first gear means revolves around said second gear means until it meshes with said first rack.

An image reading apparatus comprising:

• an original mount for mounting an original supported to be movable in a predetermined first direction and a second direction opposite to the first direction;
• a first rack provided on said original mount;
• a second rack provided on said original mount;
• gear means for selectively moving said original mount in the first direction or the second direction by rotating in a predetermined rotational direction and selectively meshing with said first rack or said second rack;
• image reading means for reading the image of the original mounted in moving said original mount.