Sheet conveying apparatus that feeds sheet members, and document reading apparatus and image forming apparatus that include the sheet conveying apparatus

A document reading apparatus comprising:

• a stacking unit configured such that a document is stacked thereon;
• a feeding unit configured to feed a document stacked on the stacking unit;
• a conveying roller that is provided downstream of the feeding unit in a conveying direction in which the document is conveyed, and that is configured to convey the document fed by the feeding unit downstream in the conveying direction;
• a reading unit configured to read the document conveyed by the conveying roller;
• a motor configured to drive the conveying roller;
• a phase determiner configured to determine a rotation phase of a rotor of the motor;
• and
• a controller configured to control a drive current flowing in a winding of the motor based on a value of a torque current component for generating torque on the rotor of the motor and a value of an excitation current component that influences an intensity of magnetic flux passing through the winding of the motor, the torque current component and the excitation current component being current components of the drive current flowing in the winding of the motor and being expressed in a rotating coordinate system that is based on the rotation phase determined by the phase determiner,
• wherein in a state where the conveying roller is conveying a first document that was fed by the feeding unit, if the value of the torque current component of the drive current flowing in the winding of the motor changes from a value greater than or equal to a predetermined value to a value less than the predetermined value, the feeding unit starts feeding of a second document that is to be fed after the first document.

An image forming apparatus comprising:

• a stacking unit configured such that a sheet member is stacked thereon;
• a feeding unit configured to feed a sheet member stacked on the stacking unit;
• a conveying roller that is provided downstream of the feeding unit in a conveying direction in which the sheet member is conveyed, and that is configured to convey the sheet member fed by the feeding unit downstream in the conveying direction;
• an image forming unit configured to form an image on the sheet member conveyed by the conveying roller;
• a motor configured to drive the conveying roller;
• a phase determiner configured to determine a rotation phase of a rotor of the motor;
• and
• a controller configured to control a drive current flowing in a winding of the motor based on a value of a torque current component for generating torque on the rotor of the motor and a value of an excitation current component that influences an intensity of magnetic flux passing through the winding of the motor, the torque current component and the excitation current component being current components of the drive current flowing in the winding of the motor and being expressed in a rotating coordinate system that is based on the rotation phase determined by the phase determiner,
• wherein in a state where the conveying roller is conveying a first sheet member that was fed by the feeding unit, if the value of the torque current component of the drive current flowing in the winding of the motor changes from a value greater than or equal to a predetermined value to a value less than the predetermined value, the feeding unit starts feeding of a second sheet member that is to be fed after the first sheet member.