An image forming apparatus includes first and second light emitting units, a light receiving unit for receiving light of the first light emitting unit when it is reflected, and receiving light of the second light emitting unit when it is not reflected, to output a signal of a predetermined level, and a control unit for starting light emission of the first light emitting unit before a front end of a paper sheet reaches an area, stopping light emission of the first light emitting unit while starting light emission of the second light emitting unit before a rear end of the paper sheet passes the area, and detecting a length of the paper sheet based on time after the output signal becomes a predetermined level during light emission of the first light emitting unit until the output signal becomes the predetermined level during light emission of the second light emitting unit.

A paper sheet detection device includes: an optical sensor that includes a light-emitting portion that emits light, and a light-receiving portion that receives the emitted light; a storage portion that stores a first threshold value used for determining whether or not a paper sheet is present in a path of the emitted light, a target light-receiving level set as a target value of a level of the light received by the light-receiving portion in a state where the paper sheet is not present, and a second threshold value that is set to a value that is greater than the first threshold value and less than the target light-receiving level; an estimating portion that determines whether the level of the light received by the light-receiving portion is equal to or greater than the first threshold value and less than the second threshold value, and that estimates whether or not the paper sheet is present; and a light amount adjusting portion that adjusts an amount of the light emitted by the light-emitting portion so that the level of the light received by the light-receiving portion becomes the target light-receiving level in the state where the paper sheet is not present when the estimating portion estimates that the paper sheet is not present after the estimating portion determines that the level of the light received by the light-receiving portion is equal to or greater than the first threshold value and less than the second threshold value.

A sheet type determining device including a guide that guides a sheet along a sheet conveyance path to a destination. The sheet conveyance path is between a first guide surface and a second guide surface facing each other across an interval. The sheet type determining device further includes a determiner that determines a sheet type when the sheet is in the sheet conveyance path, without having contact with the sheet in conveyance, and one or more regulators that regulate a displacement range of the sheet at a determining position, the displacement range being in a direction of the interval of the first and the second guide surfaces. Each of the regulators is a member that protrudes in an arc shape from the first or the second guide surface toward the guide surface opposite, and is spaced from the guide surface or another one of the regulators opposite.

A medium transporting apparatus includes a first medium transport path in which a transport roller pair is provided, a second medium transport path for feeding a medium fed downstream in a medium transport direction from the transport roller pair to an upstream position of the transport roller pair in the first medium transport path, and a medium detection unit for detecting passage of a medium in the first medium transport path, in which a position at which the medium detection unit detects a medium is switched between a transport direction upstream position and a transport direction downstream position of the transport roller pair according to whether or not a medium is transported on the second medium transport path.

A sheet stacking device includes a housing, a discharge tray, a lifting mechanism, a first upper surface detection part, a second upper surface detection part and a control part. The housing has a discharge port. On the discharge tray, the sheet discharged from the discharge port in a predetermined discharge direction is stacked. The lifting mechanism supports the discharge tray. The first upper surface detection part detects a first detected surface of the sheet on the discharge tray. The second upper surface detection part detects a second detected surface of the sheet on the discharge tray on a downstream side of the first detected surface in the sheet discharge direction. The control part controls the lifting mechanism based on a detection result of the first upper surface detection part and a detection result of the second upper surface detection part, and adjusts the discharge tray at a predetermined height.

An example a media sensor device may comprise a light source positioned on a first side of a media pathway, a light path to receive a light from the light source and direct the light through a plurality of openings from the first side of the media pathway to a second side of the media pathway, and a light sensor on the second side of the media pathway to detect print media within the light path based on an intensity of light received from the light source, wherein a heated enclosure aligns the light sensor with the light path.

An image forming apparatus, includes (1) a medium holding unit that holds a recording medium; (2) a guide member configured to be movable, that sets a medium path of the recording medium fed from the medium holding unit as a predetermined path by being locked in a predetermined position, and that is unlocked by a tension of the recording medium; (3) a first conveyance member that is arranged downstream of the medium path of the guide member, and conveys the recording medium; and (4) an image forming unit that forms an image to the recording medium conveyed by the first conveyance member.

A photo-interruptor unit includes a photo-interruptor including a light emitting component, a photosensing portion, and a hook portion configured to deform elastically in a deformation direction, and a supporting portion. The supporting portion includes an attaching surface, a hole through which the hook portion is inserted in an insertion direction, a guide portion configured to guide the hook portion so that the hook portion deforms in the deformation direction in a state where the photo-interruptor is moved in the deformation direction and a movement direction intersecting the insertion direction to be attached to the supporting portion, and a regulating portion configured to protrude from the attaching surface and configured to regulate a position in the movement direction of the photo-interruptor whose hook portion has been guided by the guide portion to a position where the hook portion is overlapped with the hole.

A medium conveying apparatus includes a pick roller feeding a medium, a separation roller placed on a downstream side of the pick roller in a conveying direction of a medium, an arrival detection sensor placed on a downstream side of the separation roller in the conveying direction and detecting arrival of a medium, a lift sensor detecting a lift of a medium between an upstream side of a roller nip of the pick roller and a downstream side of a roller nip of the separation roller, and a processor. The processor determines that a medium is a bound medium when a lift of a medium is detected by the lift sensor in a first predetermined period after detection of a front edge of a medium in a conveying direction by the arrival detection sensor, and executes abnormality processing when a medium is determined to be a bound medium.

A sheet transportation device includes a sheet loading table, a feeding unit that feeds a sheet placed on the sheet loading table, a first detection unit that is provided downstream of the feeding unit in a sheet transportation direction and that detects a position of a leading end of the sheet, a second detection unit that is provided upstream of the feeding unit in the sheet transportation direction and that detects a position of a leading end of a small-size sheet which is smaller than the sheet detected by the first detection unit, and a control unit that starts feeding the sheet based on a result of detection performed by any of the first detection unit or the second detection unit in accordance with a size of the sheet.