A device for detecting a travel distance of a sheet is provided. The device includes a light source for irradiating the sheet surface; an imaging sensor for capturing an image of a pattern of the sheet surface by light reflected from the sheet; a discrete Fourier transformation portion for performing discrete Fourier transformation on two patterns obtained by image capturing at a time interval by the imaging sensor; a high wave number component removal portion for using a threshold determined based on a cycle of concave-convex of the sheet surface to remove a high wave number component from the two patterns having been subjected to the discrete Fourier transformation; and a travel distance calculation portion for determining a travel distance of the sheet based on a phase relationship between the two patterns from which the high wave number component removal portion has removed the high wave number component.

An emission unit of a displacement detector emits laser light to a range in a space in which a target moves. A detection unit detects a distribution of amounts of light reflected from a capture region in the predefined range. Based on a shift of speckle pattern indicated by a difference between the distributions of amounts of reflected light that the detection unit detects at different times, a calculation unit calculates a displacement of the target. A correction unit measures a speckle contrast from the distribution of amounts of reflected light, and based on an error between the measured value and a reference value, corrects the amount of laser light. The reference value is set to the value of a speckle contrast in a case in which the amounts of reflected light fall within the detectable range of the detection unit.

An image forming apparatus includes a memory and a controller. The memory is configured to store information related to a recording medium type detected by a detector in the past. The controller is configured to control a feeder so as to prevent feeding of a recording medium from starting, when a printing operation is started in a first mode, in a case that a recording medium type set through a setting unit and a recording medium type discriminated based on the information stored in the memory do not match with each other.

An image forming apparatus includes an image carrier that holds an image, which is formed by developing a latent image and which is transferred onto a recording medium, a developing device that is disposed adjacent to the image carrier and that develops the latent image, a light-reflection-type sensing unit that is disposed below the developing device in a vertical direction and that detects the image on the image carrier, and a guiding member that guides the recording medium, which is transported between the developing device and the sensing unit, and that covers an upper side of the sensing unit in the vertical direction in a state where a space is ensured on an optical path of the sensing unit.

The present invention provides a recording medium detecting device, an image forming device, an image forming system, a recording medium detecting method, and a non-transitory recording medium storing a computer readable program capable of detecting a grain direction of a recording medium. A recording medium detecting device has: a sensor capable of detecting a recording medium from a first detection direction and a second detection direction different from the first detection direction; and a control unit. The control unit determines a grain direction of a recording medium from first surface property data obtained when the recording medium is detected from the first detection direction and second surface property data obtained when the recording medium is detected from the second detection direction.

An imaging system includes an endless belt, a tensioning system that applies tension to the endless belt, a contact member that engages with the endless belt, and a detector that detects slack at a part of the endless belt. A controller causes the contact member to be separated from the endless belt so that the tensioning system reduces the slack of the endless belt in response to the detector detecting the slack.

According to the present disclosure, a first guide unit is provided with a first opening portion through which light in an optical path connecting a first optical element unit and a second optical element unit passes, a second guide unit is provided with a second opening portion through which light in the optical path connecting the first optical element unit and the second optical element unit passes, the first guide unit is provided with a duct for sending air to the first optical element unit, and the air coming out from the first opening portion hits the second optical element unit via the second opening portion.

A cam transmits and blocks light emitted from a light emitting portion. The cam moves to: a first position at which first and second cartridges are attachable to and detachable from a housing; a second position at which a first development roller contacts a first photosensitive drum, the second position being a position at which the cam has moved in a first direction from the first position; and a third position at which the first development roller is separated from the first photosensitive drum and a second development roller is separated from a second photosensitive drum, the third position being a position at which the cam has moved in the first direction from the second position. During an initial operation, based on a detection result of the sensor, a controller determines which of the first position, the second position, and the third position the cam is located at.

An image forming system including: a reading unit configured to read, through a transparent member, an image on a first sheet conveyed by a conveyance unit; an opposed member provided opposite to the reading unit with respect to the transparent member, the first sheet passing through a gap between the opposed member and the transparent member; and at least one processor configured to control, based on the image read by the reading unit, a geometric characteristic of an image to be formed on a second sheet by an image forming portion, and control a changing unit to change the size of the gap to a first size when the thickness of the first sheet is a first thickness, and to a second size larger than the first size when the thickness of the first sheet is a second thickness larger than the first thickness.

An image reading apparatus connectable to an image forming apparatus includes a feeding roller pair configured to nip and feed a sheet discharged from the image forming apparatus, a contact image sensor configured to read an image on a first surface of the sheet fed by the feeding roller pair, a light-transmissive plate provided opposed to the contact image sensor and having a light-transmission property, a first roller opposing the light-transmissive plate with a gap therebetween on a side opposite from the contact image sensor with respect to the light-transmissive plat, and a second roller positioned upstream of the first roller with respect to a sheet feeding direction and opposing the light-transmissive plate with a gap therebetween on the same side as the first roller.