A medium-transporting device includes: a medium-mounting section on which a medium is mounted; a feeding unit that includes a feeding roller and that is configured to be displaced between a contact posture and a separation posture; a first restricting member that is provided downstream of the feeding roller in the transport direction and that is configured to switch between a restriction posture in which the first restricting member restricts movement of the medium and a retreat posture in which the first restricting member permits the movement of the medium; a first motor configured to generate power for rotating the feeding roller; and a second motor configured to generate power for switching a posture of the first restricting member, in which an operation of rotating the feeding roller and an operation of switching the first restricting member from the restriction posture to the retreat posture are performed in parallel.

A medium conveying apparatus includes a conveying roller to convey a medium, and a processor to detect transmission information of an ultrasonic wave transmitted through the medium or thickness information of the medium at a plurality of positions in the conveyed medium, calculate a size of an area in which the transmission information or the thickness information is within a predetermined range in the conveyed medium, determine whether a multi-feed of the medium has occurred, by comparing a value based on the transmission information or the thickness information with a threshold, and execute an abnormality processing when it is determined that the multi-feed of the medium has occurred. The processor changes the threshold according to the size.

A medium conveying apparatus includes a conveying roller to convey a medium, and a processor to detect transmission information of an ultrasonic wave transmitted through the medium or thickness information of the medium at a plurality of positions in the conveyed medium, calculate a size of an area in which the transmission information or the thickness information is within a predetermined range in the conveyed medium, determine whether a multi-feed of the medium has occurred, by comparing a value based on the transmission information or the thickness information with a threshold, and execute an abnormality processing when it is determined that the multi-feed of the medium has occurred. The processor changes the threshold according to the size.

A medium conveying apparatus includes a conveying roller to convey a medium, an overlap detection sensor, a processor to detect an overlap portion in which it is determined that an overlap has occurred on the medium based on a detection output by the overlap detection sensor for the medium conveyed by the conveying roller, calculate an overlap length where the overlap portion is continuous based on a detection result of the overlap portion, determine whether a multi-feed has occurred based on the overlap length, and execute an abnormal processing for the multi-feed based on a determination result of the multi-feed. The processor determines that a first overlap portion and a second overlap portion are continuous when a distance between the first overlap portion and the second overlap portion is within a predetermined distance in calculating the overlap length.

A medium conveying apparatus includes a conveying roller to convey a medium, an overlap detection sensor, a processor to detect an overlap portion in which it is determined that an overlap has occurred on the medium based on a detection output by the overlap detection sensor for the medium conveyed by the conveying roller, calculate an overlap length where the overlap portion is continuous based on a detection result of the overlap portion, determine whether a multi-feed has occurred based on the overlap length, and execute an abnormal processing for the multi-feed based on a determination result of the multi-feed. The processor determines that a first overlap portion and a second overlap portion are continuous when a distance between the first overlap portion and the second overlap portion is within a predetermined distance in calculating the overlap length.

An automatic lifting and feeding device includes a main controller, a material thickness detecting device, a material loading mechanism for placing materials and driving the materials to rise and fall, a material taking mechanism for transferring materials and a height detecting mechanism for detecting the height of the materials, wherein, the material thickness detecting device, the material loading mechanism, the material taking mechanism and the height detecting mechanism are respectively connected to the main controller. The height detecting mechanism includes a bracket and the height testing part connected to the bracket, and the detector for detecting the material distance is arranged on the height testing part. The invention also provides an automatic lifting feeding method. The advantage of the invention is that the height does not need to be adjusted manually. The device can automatically detect the height of the material, and achieves high efficiency.

An automatic lifting and feeding device includes a main controller, a material thickness detecting device, a material loading mechanism for placing materials and driving the materials to rise and fall, a material taking mechanism for transferring materials and a height detecting mechanism for detecting the height of the materials, wherein, the material thickness detecting device, the material loading mechanism, the material taking mechanism and the height detecting mechanism are respectively connected to the main controller. The height detecting mechanism includes a bracket and the height testing part connected to the bracket, and the detector for detecting the material distance is arranged on the height testing part. The invention also provides an automatic lifting feeding method. The advantage of the invention is that the height does not need to be adjusted manually. The device can automatically detect the height of the material, and achieves high efficiency.

An image forming apparatus includes a detection unit to detect recording material fed from a stacking unit, a determination unit, a count unit, and a control unit. The determination unit determines that a feeding failure has occurred when the detection unit does not detect the recording material until elapse of a predetermined period. The count unit counts a number of times the feeding operation is performed for a single sheet of the recording material. When the counted number of feeding operation performance times by when the feeding failure has occurred is smaller than a threshold, the control unit restarts the feeding operation that has been stopped without waiting for a user's operation. When the counted number of feeding operation performance times by when the feeding failure has occurred is at least equal to the threshold, the control unit waits for the user's operation while the feeding operation is stopped.

An image forming apparatus includes a detection unit to detect recording material fed from a stacking unit, a determination unit, a count unit, and a control unit. The determination unit determines that a feeding failure has occurred when the detection unit does not detect the recording material until elapse of a predetermined period. The count unit counts a number of times the feeding operation is performed for a single sheet of the recording material. When the counted number of feeding operation performance times by when the feeding failure has occurred is smaller than a threshold, the control unit restarts the feeding operation that has been stopped without waiting for a user's operation. When the counted number of feeding operation performance times by when the feeding failure has occurred is at least equal to the threshold, the control unit waits for the user's operation while the feeding operation is stopped.

A medium conveying apparatus includes a conveying roller to convey a medium, an overlap detection sensor, a processor to detect an overlap portion in which it is determined that an overlap has occurred on the medium based on a detection output by the overlap detection sensor for the medium conveyed by the conveying roller, calculate an overlap length where the overlap portion is continuous based on a detection result of the overlap portion, determine whether a multi-feed has occurred based on the overlap length, and execute an abnormal processing for the multi-feed based on a determination result of the multi-feed. The processor determines that a first overlap portion and a second overlap portion are continuous when a distance between the first overlap portion and the second overlap portion is within a predetermined distance in calculating the overlap length.