A sheet storage device includes a body, a tray, a rotating member, an angle sensor, and a controller. The tray is vertically repositionable relative to the body and supports a sheet placed on the tray. The rotating member rotates in conjunction with a vertical movement of the tray. The angle sensor detects a rotation angle of the rotating member. The controller is operatively coupled to the angle sensor and determines a remaining number of sheets placed on the tray based on a detection result of the angle sensor.

A medium conveying apparatus includes a first optical sensor located on an upper part of the housing and in a central part of the housing in a direction perpendicular to a medium conveying direction, a second optical sensor located on an upper part of the housing and on a side of the first optical sensor in the direction perpendicular to the medium conveying direction, and a processor to detect a folding of a medium based on the first signal or the second signal, and stop feeding of the medium by the feed roller in accordance with a detection result of the folding of the medium. The first light emitter emits first light toward a downstream side of the medium in the medium conveying direction, and the second light emitter emits second light toward an upstream side of the medium in the medium conveying direction.

An ultrasonic apparatus includes a first ultrasonic sensor that transmits an ultrasonic wave to an object and receives the ultrasonic wave reflected by the object, a second ultrasonic sensor that transmits an ultrasonic wave to the object and receives the ultrasonic wave reflected by the object, an determination circuit that outputs an error signal when the difference between a first distance between the first ultrasonic sensor and the object calculated based on ultrasonic wave transmission and reception processing using the first ultrasonic sensor and a second distance between the second ultrasonic sensor and the object calculated based on ultrasonic wave transmission and reception processing using the second ultrasonic sensor is equal to or greater than a threshold value.

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 first optical sensor located on an upper part of the housing and in a central part of the housing in a direction perpendicular to a medium conveying direction, a second optical sensor located on an upper part of the housing and on a side of the first optical sensor in the direction perpendicular to the medium conveying direction, and a processor to detect a folding of a medium based on the first signal or the second signal, and stop feeding of the medium by the feed roller in accordance with a detection result of the folding of the medium. The first light emitter emits first light toward a downstream side of the medium in the medium conveying direction, and the second light emitter emits second light toward an upstream side of the medium in the medium conveying direction.

A sheet stacker includes a housing, a fence, a first distance measurement sensor, and a second distance measurement sensor. The fence is movable in a fence moving direction on the housing and is configured to regulate a position of an end of a sheet. The first distance measurement sensor is configured to measure a distance between the fence and a first portion of the housing, the first portion being on one side of the housing with respect to the fence in the fence moving direction. The second distance measurement sensor is configured to measure a distance between the fence and a second portion of the housing, the second portion being on another side of the housing with respect to the fence in the fence moving direction.

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 first detector detects a sheet between a first conveyance roller and a confluence position in a conveyance path. The first detector includes a first actuator and a first sensor. The first actuator is rotationally movable by contacting the sheet conveyed by the first conveyance roller. The first sensor is an optical sensor that detects rotational movement of the first actuator. A second detector detects the sheet between a second conveyance roller and the confluence position in a reconveyance path. The second detector includes a second actuator and a second sensor. The second actuator is rotationally movable by contacting the sheet conveyed by the second conveyance roller. The second sensor is an optical sensor that detects rotational movement of the second actuator. A single sensor board supports the first sensor and the second sensor. The sensor board has a wiring pattern connected to the first sensor and the second sensor.

A recoding medium conveying device includes a conveyance belt, a first sensor, a second sensor, and circuitry. The conveyance belt has an endless loop shape and a length capable of conveying a plurality of recording media in one rotation. The first sensor is disposed upstream from the conveyance belt in a conveyance direction of a recording medium and is configured to detect the recording medium. The second sensor is configured to detect a home position of the conveyance belt. The circuitry is configured to adjust a rotation speed of the conveyance belt, while the conveyance belt makes one rotation, to eliminate an amount of deviation between a first detection timing of the recording medium detected by the first sensor and a second detection timing of the home position of the conveyance belt detected by the second sensor.

A medium feeding device includes a storage unit that stores media in a form of a sheet, a delivery unit that is disposed downstream in a medium delivery direction relative to the media stored in the storage unit and that delivers the media individually, a transfer unit that is disposed above the storage unit and that sticks by suction to each of the media stored in the storage unit and transfers the media to the delivery unit individually, and a fluffing unit that is disposed beside the media stored in the storage unit in a direction intersecting the medium delivery direction. The fluffing unit fluffs an upper-side region of the media in a state of being separated by blowing air toward a side of the media. The medium feeding device further includes plural position detection units that are arranged in a region that is on the delivery unit side relative to a position of a downstream end portion, in the medium delivery direction, of each of the media stored in the storage unit and that does not reach a contact portion where the delivery unit comes into contact with the media. The position detection units are arranged at an interval in a width direction of the media intersecting the medium delivery direction. The position detection units detect a position of the downstream end portion, in the medium delivery direction, of each of the media.