Sheet conveying device, document feeder, and image forming apparatus

A document feeder comprising a sheet conveying device including:

• a stacker to stack a sheet;
• a pickup roller to:
• contact the sheet on the stacker;
• and
• pick up the sheet on the stacker in a conveyance direction;
• a conveyor downstream from the pickup roller in the conveyance direction,
• to convey the sheet picked up by the pickup roller in the conveyance direction;
• a separator to:
• contact the conveyor to form a nip to nip the sheet conveyed in the conveyance direction;
• and
• restrict a conveyance of multiple sheets, including the sheet, by the nip in the conveyance direction;
• a pressing member upstream from the pickup roller in the conveyance direction, the pressing member having a state switchable between:
• a pressing state in which the pressing member presses the sheet on the stacker;
• and
• a separated state in which the pressing member is separated from the sheet on the stacker;
• a pressure mechanism to:
• cause the pickup roller to apply a first pressure force to the sheet on the stacker when the pressing member is in the separated state;
• and
• cause the pickup roller to apply a second pressure force smaller than the first pressure force to the sheet on the stacker when the pressing member is in the pressing state;
• and
• a conveyance portion to convey a document as the sheet on the stacker at a position downstream from the conveyor in the conveyance direction.

An image forming apparatus comprising a sheet conveying device including:

• a stacker to stack a sheet;
• a pickup roller to:
• contact the sheet on the stacker;
• and
• pick up the sheet on the stacker in a conveyance direction;
• a conveyor downstream from the pickup roller in the conveyance direction,
• to convey the sheet picked up by the pickup roller in the conveyance direction;
• a separator to:
• contact the conveyor to form a nip to nip the sheet conveyed in the conveyance direction;
• and
• restrict a conveyance of multiple sheets, including the sheet, by the nip in the conveyance direction;
• a pressing member upstream from the pickup roller in the conveyance direction, the pressing member having a state switchable between:
• a pressing state in which the pressing member presses the sheet on the stacker;
• and
• a separated state in which the pressing member is separated from the sheet on the stacker;
• and
• a pressure mechanism to:
• cause the pickup roller to apply a first pressure force to the sheet on the stacker when the pressing member is in the separated state;
• and
• cause the pickup roller to apply a second pressure force smaller than the first pressure force to the sheet on the stacker when the pressing member is in the pressing state.