A sheet conveyance device includes a transmitter circuit, a receiver circuit, an integrator circuit which performs charging of electric charge outputted from the transmitter circuit and outputs a judgment voltage, a drive circuit, and a control circuit. The drive circuit feeds a drive signal to the transmitter circuit. At a lapse of a wait time after changing a level of a transmission instruction signal to a level instructing to feed the drive signal to the transmitter circuit, the control circuit makes the integrator circuit start to perform charging. When adjusting the wait time, the control circuit performs processing for adjustment a plurality of times. The control circuit makes the wait time different in each execution of the processing for adjustment. The control circuit determines a new wait time based on a magnitude of the judgment voltage recognized in each execution of the processing for adjustment.

An image forming apparatus includes an image forming unit configured to form an image on a sheet being conveyed on a horizontal path and a double feed sensor configured to execute double feed detection processing of detecting a state in which a plurality of sheets being conveyed on the horizontal path are conveyed in a duplicate manner. The image forming apparatus includes a double feed detection function table, in which whether to enable or disable the double feed detection processing is set according to a type of a sheet. The image forming apparatus determines whether to execute the double feed detection processing at a time of image formation in accordance with sheet setting information including information on a characteristic of a sheet to be used for the image formation and setting information on whether to execute the double feed detection processing, and the double feed detection function table.

A transport device includes: a medium support unit having a placement surface where a sheet-like medium is placed; a transport unit supplied with the medium placed at the placement surface and transporting the medium in a transport direction along a sheet surface of the medium; an ultrasonic transmitting unit provided at a part of the medium support unit and transmitting an ultrasonic wave; an ultrasonic receiving unit provided at another part of the medium support unit, and receiving the ultrasonic wave and outputting a received signal; and a floating detection unit determining whether a floating of the medium from the placement surface is present or not, based on the received signal.

Provided are a multi-feed detection apparatus, a control method, and a control program to suitably determine whether or not the multi-feed detection apparatus returns a fed medium to a direction of a medium tray when multi-feed has occurred. A multi-feed detection apparatus includes an ultrasonic sensor to generate an ultrasonic signal, a multi-feed determination module to determine that feeding of the medium is normal when a signal value of the ultrasonic signal is equal to or more than a first threshold value, and determine that a multi-feed of the medium has occurred when the signal value of the ultrasonic signal is less than the first threshold value, and a control module to control the feed module to return the fed medium to a direction of the medium tray when the signal value of the ultrasonic signal is less than a second threshold value smaller than the first threshold value.

According to one embodiment, there is provided an image processing apparatus including a sheet storage unit, a pickup roller, a paper feed roller, a separation roller, a roller drive unit, a roller pressing unit, and a drive control unit. The pickup roller picks up a sheet from the sheet storage unit. The paper feed roller conveys the sheet picked up by the pickup roller. The separation roller is disposed to face the paper feed roller. The roller drive unit drives the separation roller. The roller pressing unit presses the separation roller against the paper feed roller. The drive control unit controls the roller drive unit so as to generate a conveying force for conveying the sheet and a returning force for pushing the sheet back in a direction opposite to a conveyance direction.

A transmitter transmits ultrasonic wave of a predetermined volume. A reflected ultrasonic wave receiver receives reflected ultrasonic wave, transmitted from the transmitter and reflected by a sheet. A permeated ultrasonic wave receiver receives permeated ultrasonic wave, transmitted by the transmitter and permeated through the sheet. A volume detector detects reflected volume of the reflected ultrasonic wave, and permeated volume of the permeated ultrasonic wave. The decider identifies a thickness of the sheet being transported by a transport device, and decides whether multifeed of the sheets is occurring, on a basis of a comparison result between the detected reflected volume and a reference reflected volume, and a comparison result between the detected permeated volume and a reference permeated volume.

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 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.

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 medium conveying apparatus includes a floating sensor located on an upstream side of a first roller in the medium conveying direction to detect a floating of the medium placed on a medium tray, a skew sensor located on a downstream side of a second roller in the medium conveying direction to detect a skew of the medium conveyed by the second roller, and a processor to determine whether the floating of the medium has occurred based on an output signal from the floating sensor, determine whether the skew of the medium has occurred based on an output signal from the skew sensor, and determine that a conveyance abnormality of the medium has occurred when the processor determines that the floating of the medium has occurred and the processor determines that the skew of the medium has occurred.