A sheet feed apparatus comprises a tray, a pair of first guide sections, and a first optical sensor. The tray has a housing section for accommodating a plurality of sheets. The pair of first guide sections, arranged in the tray, sandwich the sheets in a direction perpendicular to a sheet conveyance direction. The first optical sensor provided above a bottom of the housing section in at least one of the first guide sections, is configured to detect one or more of uppermost sheets accommodated in the housing section.

A sheet conveying device, which is included in an image forming apparatus and a post processing device, includes multiple position detectors and a position corrector. The multiple position detectors are aligned along a sheet conveying direction and configured to detect a side end of a sheet. The position corrector is configured to convey the sheet and correct a position of the sheet based on a positional deviation amount of the sheet, obtained by a detection result of the multiple position detectors. The positional deviation amount of the sheet is obtained by an extreme downstream position detector in the sheet conveying direction, of the multiple position detectors. A position of a subsequent sheet is corrected based on a sum of the positional deviation amount of the sheet and a positional deviation amount of the subsequent sheet.

A sheet feed apparatus comprises a tray, a pair of first guide sections, and a first optical sensor. The tray has a housing section for accommodating a plurality of sheets. The pair of first guide sections, arranged in the tray, sandwich the sheets in a direction perpendicular to a sheet conveyance direction. The first optical sensor provided above a bottom of the housing section in at least one of the first guide sections, is configured to detect one or more of uppermost sheets accommodated in the housing section.

An image forming apparatus includes: an image forming part that forms an image on a sheet conveyed in a conveying path; a transfer part that transfers the image; a conveying roller that is arranged at the upstream of the transfer part in the conveying path, has rollers, and conveys the sheet to the transfer part; roller drive mechanisms that independently rotate the rollers; a first bend detection sensor that is arranged in the conveying path and detects a bend of a front end of the sheet relative to the conveying direction; a sheet rotation angle calculation part that calculates a first rotation offset angle of the front end of the sheet relative to an axial line of the conveying roller; a roller driving amount calculation part that calculates the driving amounts of the roller drive mechanisms; and a drive mechanism control part that controls operations of the roller drive mechanisms.

A sheet conveying device includes a detector configured to detect an attitude of a conveyance target medium, a corrector configured to perform a correcting operation based on a detection result of the detector, and circuitry configured to calculate an angular displacement correction amount and a lateral displacement correction amount of the conveyance target medium, cause the corrector to perform the correcting operation in a direction perpendicular to a sheet conveying direction, based on the lateral displacement correction amount, after the corrector grips the conveyance target medium, and cause the corrector to rotate by the angular displacement correction amount of the conveyance target medium before the corrector grips the conveyance target medium and to perform the correcting operation in a direction of rotation of the conveyance target medium, based on the angular displacement correction amount, after the corrector grips the conveyance target medium.

An image forming apparatus includes a sensor, a tray, a gear, a protruding portion, and a processor. The sensor has a light transmitting unit and light receiving units and is configured to generate an output signal in accordance with an amount of light received by the light receiving units. The gear is configured to rotate in accordance with an amount of sheets stacked on the tray. The protruding portion is configured to rotate with the gear and move into a light path of light emitted from the light emitting unit to the light receiving units to partially block the light, the protruding portion having a width that determines how much light in the light path is blocked and varies gradually from a first end thereof to a second end thereof. The processor is configured to determine the amount of sheets stacked on the tray based on the output signal.

A sheet conveying device, which is incorporated in an image forming apparatus, includes a first detector to detect an angle deviation of a recording medium to a sheet conveying direction, a second detector to detect a lateral shift of the recording medium to a width direction, a third detector to detect at least one of the angle deviation and the lateral shift after correction of the angle deviation detected by the first detector and the lateral shift detected by the second detector, and a rotary body to perform a primary movement by (1) rotating in the sheet conveying direction and returning to a reference position and by (2) moving in the width direction and returning to the reference position, and a secondary movement by performing at least one of (1) and (2) after the primary movement.

A vacuum belt has perforations between belt edges. Some perforations in the vacuum belt are arranged in a pattern. The vacuum belt is positioned adjacent the media supply in a location to move sheets of the print media from the media supply. A light sensor is positioned in a location to detect light passing through the vacuum belt. The light sensor detects a portion of the vacuum belt as limited by an aperture area of the vacuum belt, and the pattern of perforations, and the size and location of the aperture area of the vacuum belt causes the signal output by the light sensor to be constant when the sheets are outside the aperture area of the vacuum belt.

A sheet conveying device, which is included in an image forming apparatus and a post processing device, includes multiple position detectors and a position corrector. The multiple position detectors are aligned along a sheet conveying direction and configured to detect a side end of a sheet. The position corrector is configured to convey the sheet and correct a position of the sheet based on a positional deviation amount of the sheet, obtained by a detection result of the multiple position detectors. The positional deviation amount of the sheet is obtained by an extreme downstream position detector in the sheet conveying direction, of the multiple position detectors. A position of a subsequent sheet is corrected based on a sum of the positional deviation amount of the sheet and a positional deviation amount of the subsequent sheet.

A printer comprises a processor; a media hanger comprising a sensor array receiving space extending along a length of the media hanger; and a sensor array positioned in the sensor array receiving space and communicatively connected to the processor, the sensory array comprising a plurality of sensor pairs, each sensor pair having an emitter and a receiver, the sensor array being configured to: emit light from the emitter outward from the media hanger, detect the emitted light after the emitted light is reflected off a surface of media loaded on the media hanger, transmit signal intensity of the reflected light detected by each of the sensor pairs to the processor; wherein the processor is configured to determine a width of the media loaded on the media hanger based on the signal intensity detected by each of the sensor pairs.