A sheet conveying device includes a control unit. The control unit determines whether a first sheet and a second sheet being double-fed are in a full double feed state in which the first sheet and the second sheet are conveyed while overlapping each other from distal end parts of the first sheet and the second sheet in a conveyance direction or a partial double feed state in which the second sheet is conveyed while overlapping a rear part of the first sheet than the distal end part of the first sheet, stops an operation of a sheet conveying mechanism when it is determined that the sheets are in the full double feed state, and performs double feed elimination control for eliminating the double feeding of the sheets without stopping the sheet conveying mechanism when it is determined that the sheets are in the partial double feed state.

A feeding apparatus includes a feeding member, first and second conveying members, a separation member, and drive and control units. The feeding member feeds a recording material placed on a tray. The separation member and the first conveying member form a nip portion and separates recording materials at the nip portion. The second conveying member conveys a conveyed recording material. The drive unit drives at least the feeding member. The control unit controls to feed first and second recording materials such that a second recording material front edge passes the nip portion before a first recording material rear edge passes the nip portion, and controls to stop the second recording material after the second recording material front edge has passed the nip portion such that the first recording material rear edge reaches the second conveying member before the second recording material front edge reaches the second conveying member.

An ultrasonic device includes an ultrasonic element that performs at least one of transmitting an ultrasonic wave along a first axis and receiving the ultrasonic wave input along the first axis, and a protective member that is provided on the first axis and covers the ultrasonic element, in which the protective member has a plurality of pores through which the ultrasonic wave traveling along the first axis passes.

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 paper conveyance device includes a paper feed unit, a conveyance rotator, a conveyance guide, a multi-feed detection unit, and a control unit. The control unit causes an ultrasonic sensor to transmit an ultrasonic wave in a detection section. The control unit sets a detection execution section and a detection skip section in the detection section. The control unit does not determine whether multi-feed has occurred in the detection skip section. The control unit sets the detection skip section based on a time point at which vibration is applied to conveyed paper.

A printing apparatus includes a feeding roller configured to feed a printing sheet stacked on a stacking unit, a conveyance roller configured to convey the printing sheet fed by the feeding roller, a printing unit configured to print the printing sheet conveyed by the conveyance roller, a conveyance control unit configured to control conveyance of printing sheets so that the trailing edge of a preceding sheet as a printing sheet precedingly fed from the stacking unit and the leading edge of a succeeding sheet as a printing sheet succeedingly fed from the stacking unit overlap each other, and a determination unit configured to determine whether to convey the succeeding sheet to a position facing the printing unit while keeping an overlap state between the preceding sheet and the succeeding sheet.

An ultrasonic device includes: an ultrasonic element that has a transmission surface transmitting an ultrasonic wave and that transmits the ultrasonic wave in a direction intersecting the transmission surface; a wiring arranged at a transmission surface outer circumference of the transmission surface and coupled to the ultrasonic element; a shield covering the wiring; a holder arranged at a shield outer circumference of the shield and extending in the direction; and a protector facing the transmission surface and having a hole through which the ultrasonic wave passes. The shield is provided with a shield opening that faces the transmission surface. The holder is provided with a holder opening that faces the transmission surface. The protector is arranged at the holder opening.

A medium feed apparatus includes a first sensor, a second sensor, a third sensor to detect rotation of the separation roller, and a processor. The processor controls a motor to put the separation roller on hold from when starting the feed of the medium to when the second sensor detects a front end of the medium and generate the drive force from when the second sensor detects the front end of the medium to when the first sensor detects a back end of the medium, and controls the motor to stop the feed roller while generating the drive force if the third sensor detects rotation of the separation roller in the opposite direction to the medium feed direction during feed of the medium.

A paper jam indication estimation device estimates an indication that a paper jam will occur in a paper feed device, and includes: a sound collector that collects a friction sound produced between sheets of paper when the paper is fed into the paper feed device from a holder holding a plurality of sheets of the paper; an estimator that, based on an output result obtained by inputting information pertaining to the friction sound into a trained model that is a machine learning model which has been trained, estimates a presence or absence of an indication that a paper jam will occur in the paper feed device; and an outputter that, when the estimator estimates that the indication that a paper jam will occur is present, outputs, to the paper feed device, a signal that stops the paper from being fed into the paper feed device.

According to an embodiment, a sheet conveying device detects double feeding of sheets by an ultrasonic wave oscillator and an ultrasonic waves receiver provided across a conveying path of the sheets. The sheet conveying device calibrates a threshold voltage on the basis of an offset voltage of an amplifier circuit when the receiver has not received ultrasonic waves.