Provided is a recording medium detection device which prevents the decline in productivity. The recording medium detection device comprises a first detecting section and a second detecting section. The first detecting section performs a first adjustment process and makes a detection of a recording medium being transported. The second detecting section is located more downstream than the first detecting section in the transportation direction of the recording medium, performs a second adjustment process which takes a longer time than the first adjustment process, and makes a detection of the recording medium being transported.

Provided are a sheet position detection apparatus, a sheet conveyance apparatus, and an image formation apparatus. The sheet position detection apparatus has a first and a second conveyance roller which are arranged to oppose across a sheet to be conveyed and to nip the sheet, and a detector configured to detect an end position of the sheet, the detector has a light emitter and a light receptor arranged on the first conveyance roller side, the light emitter and the light receptor are arranged such that a light emitted from the light emitter is reflected on a reflective face of the second conveyance roller and enters the light receptor, and the detector detects passage of an end of the sheet based on a change in the amount of light entering the light receptor when the sheet shields a light emitted from the light emitter.

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 sheet feeding device includes a sheet stacker configured to stack a sheet bundle; a blower configured to float a sheet on an upper portion of the sheet bundle; a conveyor configured to convey the sheet floated by the blower; a lift configured to lift up and down the sheet stacker; a first reflective optical sensor configured to detect the sheet floated by the blower; a second reflective optical sensor configured to detect the sheet bundle and a side face of the sheet stacker, the side face including a detection region to be detected by the second reflective optical sensor and a non-detection region not to be detected by the second reflective optical sensor; and circuitry configured to control the lift based on a detection result of the first reflective optical sensor and a detection result of the second reflective optical sensor. The circuitry is configured to cause the lift to lift up the sheet stacker in response to a change from a detection state to a non-detection state of the second reflective optical 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.

A method of testing a functional unit includes an optical sensor system (28) for detecting an optical signal from at least a part of a moving material web (14), a data processing system (36) for valuating the optical signals, and a display (38) displaying a state of the material web (14) and arranged in a sensitive range (30) of the sensor system (28).

A roll medium transport apparatus includes a feed roll medium support unit that feeds a roll medium, a takeup roll medium support unit that winds up the roll medium that has been fed, a position acquiring unit that acquires a position of a side end portion of the roll medium that is to be fed, a radiating unit capable of radiating light with a position of the side end portion being used as a reference point. The radiating unit is held by the feed roll medium support unit and allows the light to be radiated to a takeup roll that winds up the roll medium.

A medium supply device includes: a loading unit on which media are loadable in an up-down direction; a supply unit that supplies air to a plural media loaded on the loading unit to float and separate the plural media; a transporting unit that sequentially feed the media that are floated and separated by the supply unit; a photographing unit that photographs a state in which the media are floated and separated by the supply unit; and a light irradiation unit that irradiates end portions of the media on a photographing side of the photographing unit with light from a plural different positions in the up-down direction.

A sensor unit includes an edge detection sensor and an illumination device. The edge detection sensor is disposed in a conveying path of a recording medium and detects a recording medium edge position in a width direction perpendicular to a conveying direction. The illumination device is disposed to face the edge detection sensor in the conveying path and emits light toward the edge detection sensor. The illumination device includes a light source and a diffuser. The light source emits light. The diffuser diffuses the light from the light source and suppresses luminance unevenness.

Provided are a sheet position detection apparatus, a sheet conveyance apparatus, and an image formation apparatus. The sheet position detection apparatus has a first and a second conveyance roller which are arranged to oppose across a sheet to be conveyed and to nip the sheet, and a detector configured to detect an end position of the sheet, the detector has a light emitter and a light receptor arranged on the first conveyance roller side, the light emitter and the light receptor are arranged such that a light emitted from the light emitter is reflected on a reflective face of the second conveyance roller and enters the light receptor, and the detector detects passage of an end of the sheet based on a change in the amount of light entering the light receptor when the sheet shields a light emitted from the light emitter.