A medium conveying apparatus includes a plurality of feed rollers, each feed roller rotating independently at a respective speed to feed a medium, a first sensor located on a downstream side of the plurality of feed rollers in a medium conveying direction and also in a central part in a direction perpendicular to the medium conveying direction, to detect the medium, a second sensor and a third sensor located on both sides of the first sensor in the direction perpendicular to the medium conveying direction, to respectively detect the medium, and a processor to change the speed of one of the plurality of feed rollers at least until the first sensor detects the medium when any of the second sensor or the third sensor detects the medium and the first sensor does not detect the medium within a predetermined time.

A sheet feeding device includes a support, a rotation driver, a guide, a support shaft, a biasing member, a leading end sensor, a roller, an outer diameter sensor, and circuitry. The circuitry causes the rotation driver to rotate a spool in a winding direction to determine a timing at which a signal change rate exceeds a change rate threshold as a passing time at which a leading end of a continuous sheet passes through the leading end sensor, causes the rotation driver to rotate the spool by a rotation angle in the winding direction, from the passing time, to position the leading end of the continuous sheet at a feeding start position, and rotates the spool in a feeding direction to feed the continuous sheet from the feeding start position along a guide portion. Further, the circuitry changes the change rate threshold based on an outer diameter of a roll.

A sheet feeding device includes a support, a rotation driver, a guide, a support shaft, a biasing member, a leading end sensor, a roller, an outer diameter sensor, and circuitry. The circuitry causes the rotation driver to rotate a spool in a winding direction to determine a timing at which a signal change rate exceeds a change rate threshold as a passing time at which a leading end of a continuous sheet passes through the leading end sensor, causes the rotation driver to rotate the spool by a rotation angle in the winding direction, from the passing time, to position the leading end of the continuous sheet at a feeding start position, and rotates the spool in a feeding direction to feed the continuous sheet from the feeding start position along a guide portion. Further, the circuitry changes the change rate threshold based on an outer diameter of a roll.

A medium-feeding apparatus includes a movement detector configured to output information on movement of a medium in a first direction parallel to a feeding direction and in a second direction intersecting the feeding direction. A control unit is configured to perform abnormal feeding processing depending on the movement of the medium in the second direction. In the abnormal feeding processing, the control unit stops feeding of the medium when a first value indicating the movement of the medium in the first direction is within an allowable range and when a second value indicating the movement of the medium in the second direction exceeds a threshold, and continues feeding of the medium when the first value is outside the allowable range.

A medium-feeding apparatus includes a movement detector configured to output information on movement of a medium in a first direction parallel to a feeding direction and in a second direction intersecting the feeding direction. A control unit is configured to perform abnormal feeding processing depending on the movement of the medium in the second direction. In the abnormal feeding processing, the control unit stops feeding of the medium when a first value indicating the movement of the medium in the first direction is within an allowable range and when a second value indicating the movement of the medium in the second direction exceeds a threshold, and continues feeding of the medium when the first value is outside the allowable range.

A conveyance device includes a conveyance roller, a registration roller, a sensor, a mode setting part, a storage, a conveyance state determination part and a drive control part. The mode setting part sets the mode to either a plain paper mode or a tab paper mode. The storage stores threshold information corresponding to the mode. The conveyance state determination part determines, when the plain paper mode is set, whether the conveyance state of the recording medium is a skew conveyance state or a tab paper conveyance state, based on the detection result of the sensor and the plain paper mode threshold information. The conveyance state determination part determines, when the tab paper mode is set, whether the conveyance state of the recording medium is the skew conveyance state or the tab paper conveyance state, based on the detection result of the sensor and the tab paper mode threshold information.

A conveyance device includes a conveyance roller, a registration roller, a sensor, a mode setting part, a storage, a conveyance state determination part and a drive control part. The mode setting part sets the mode to either a plain paper mode or a tab paper mode. The storage stores threshold information corresponding to the mode. The conveyance state determination part determines, when the plain paper mode is set, whether the conveyance state of the recording medium is a skew conveyance state or a tab paper conveyance state, based on the detection result of the sensor and the plain paper mode threshold information. The conveyance state determination part determines, when the tab paper mode is set, whether the conveyance state of the recording medium is the skew conveyance state or the tab paper conveyance state, based on the detection result of the sensor and the tab paper mode threshold information.

A conveying device includes a first pair of nipping rollers, a second pair of nipping rollers, a position corrector configured to correct a position of a recording medium in a width direction of the recording medium, an end position detector configured to detect an end position of the recording medium in the width direction, and circuitry configured to, in adjustment of the end position detector, stop conveying the recording medium in response to arrival of a leading end of the recording medium at the end position detector, cause the position corrector to move the recording medium toward an outside of the conveyance passage in the width direction to a position at which the end position detector is covered by the recording medium, adjust the output of the end position detector, and cause the end position detector to detect the recording medium.

A correction structure arranged in a feeding path of a document processing device, comprising: a transmitting means consisted of at least a pair of roller set which are arranged symmetrically on the two sides of the feeding path for transmitting the card evenly, a correcting means consisted of a platform movably arranged at the downstream to the roller set, a receptacle formed on the platform, a elastomer arranged in the receptacle for returning the platform to a predefined location, a back wall extended from the platform toward the feeding path, an opening formed on the back wall to let a card go through, and a friction pad arranged at the bottom of the opening to partly jam the opening, wherein the width of the friction pad is less than the width of the feeding path so the friction pad only contacts the center of the card while transmitting the card.

A correction structure arranged in a feeding path of a document processing device, comprising: a transmitting means consisted of at least a pair of roller set which are arranged symmetrically on the two sides of the feeding path for transmitting the card evenly, a correcting means consisted of a platform movably arranged at the downstream to the roller set, a receptacle formed on the platform, a elastomer arranged in the receptacle for returning the platform to a predefined location, a back wall extended from the platform toward the feeding path, an opening formed on the back wall to let a card go through, and a friction pad arranged at the bottom of the opening to partly jam the opening, wherein the width of the friction pad is less than the width of the feeding path so the friction pad only contacts the center of the card while transmitting the card.