Image forming apparatus with curl generating means

An image recording apparatus comprising:

• conveying means for feeding out a sheet medium supplied from a paper feed section to a registration portion through a paper path having a curved portion;
• image forming means for forming an image on the fed sheet medium;
• registration means for forming a loop space by once stopping a front edge of the sheet medium in order to correct an oblique movement of the sheet medium, and for feeding out the sheet medium to said image forming means;
• and
• a drum arranged downstream of said registration means in a sheet medium conveying direction for holding the sheet medium and conveying the sheet medium to said image forming means,
• wherein guide members for forming an outside of said paper path curved portion are moveable and the loop space is formed by a movement of at least one of said guide members, wherein at least one of said movable guide members is constructed so that movements of both edges in a paper width direction are independently executed.

An image forming apparatus comprising:

• a rotating body by which a sheet is wound in a direction around a curved surface thereof and held;
• image forming means for forming an image on the sheet held by said rotating body;
• a conveyance path for guiding the sheet to said rotating body;
• and
• curl giving means provided in said conveyance path and for giving a curl to the sheet in the direction in which the sheet is wound around the curved surface of said rotating body;
• and
• oblique movement correcting means provided in said conveyance path and for curving the sheet with once stopping a front edge of the sheet in order to correct an oblique movement of the sheet being conveyed.

A sheet conveying apparatus, comprising:

• conveying means for conveying a sheet;
• oblique movement correcting means for correcting an oblique movement of the sheet by curving the sheet in a direction with once stopping a front edge of the sheet conveyed by said conveying means;
• and
• a guide member moveable with being pushed by the sheet curved by said oblique movement correcting means, said guide member being adapted so that movements of both edges in a sheet width direction are independently executed.

A sheet conveying apparatus, comprising:

• conveying means for conveying a sheet;
• oblique movement correcting means for correcting an oblique movement of the sheet by curving the sheet in a direction with once stopping a front edge of the sheet conveyed by said conveying means;
• a first guide member moveable with being pushed by the sheet curved by said oblique movement correcting means;
• and
• a second guide member provided downstream of said first guide member in a sheet conveying direction and moveable with being pushed by the sheet curved by said oblique movement correcting means.

An image forming apparatus, comprising:

• a rotating body by which a sheet is wound in a direction around a curved surface thereof and held;
• image forming means for forming an image on the sheet held by said rotating body;
• means for defining a conveyance path for guiding the sheet to said rotating body;
• and
• curl giving means provided in said conveyance path defining means and for giving a curl to the sheet in the direction in which the sheet is wound around the curved surface of said rotating body, wherein said curl giving means comprises a primary roller and first and second secondary rollers for curling the sheet as it passes through said conveyance path defining means, and whereafter the sheet continues through said conveyance path in a non-curled state but returns to a curled state when it is wound around the curved surface of said rotating body.

An image forming apparatus, comprising:

• convey means for conveying a sheet;
• a pair of registration rollers for conveying the sheet, said registration roller pair temporally holding a tip end of the sheet conveyed by said convey means to bend the sheet for correcting a skew-feed thereof;
• a guide member shiftable by pressing from the sheet bent by said registration roller pair, both end portions of said guide member in a sheet widthwise direction capable of shifting independently;
• and
• image forming means for forming an image on the sheet the skew-feed of which is corrected by said registration roller pair.

An image forming apparatus, comprising:

• convey means for conveying a sheet;
• a pair of registration rollers for conveying the sheet, said registration roller pair temporally holding a tip end of the sheet conveyed by said convey means to bend the sheet and form a loop portion for correcting a skew-feed thereof;
• a first guide member shiftable by pressing from the loop portion of the sheet bent by said registration roller pair;
• a second guide member disposed down-stream of said first guide member in a sheet convey direction and shiftable by pressing from the sheet bent by said registration roller pair;
• and
• an image forming means for forming an image on the sheet the skew-feed of which is corrected by said registration roller pair.

An image forming method in which a sheet is held on a hold means, then the hold means is rotated to transfer an image of an image bearing member onto the sheet at a transfer position for the image formation, comprising steps of:

• correcting a skew-feed of the sheet by causing a tip end of the sheet to abut against a nip of a stopped pair of curl applying convey rollers, and forming a curl on the sheet in a direction surrounding the hold means by rotating the curl applying convey rollers;
• forming a loop on the sheet by holding the tip end of sheet to which the curl is applied by the nip of a registration roller pair;
• conveying the sheet to the hold means by rotating the registration roller pair;
• and
• separating one roller of the registration roller pair after the sheet tip end reaches the hold means.