A housing includes a first opening and a second opening, and encloses a light-emitting element and a first light receiving unit. The first opening is provided in a first light guide path, and is arranged so that light output from the light-emitting element travels toward a target surface. The second opening is provided in a second light guide path arranged between the target surface and the first light receiving unit. The first opening is an exit opening of a through-hole provided penetrating through the housing, and a shape of the through-hole is a shape in which diffracted light of the +1st order and higher orders and diffracted light of the −1st order and higher orders produced at the target surface to be irradiated are not incident on the first light receiving unit.

A housing includes a first opening and a second opening, and encloses a light-emitting element, a first light receiving unit, and a second light receiving unit. The first opening is provided in a first light guide path arranged between the light-emitting element and a first irradiated region of the target surface, and is arranged so that light output from the light-emitting element travels toward the first irradiated region. The second opening is provided in a second light guide path arranged between the first irradiated region and the first light receiving unit, and is arranged so that diffused reflection light from the toner image passes through when the toner image passes the first irradiated region.

An image forming apparatus includes an image processor configured to convert image data based on a first conversion condition; an image forming unit configured to form an image on a sheet based on the image data converted by the image processor, the image forming unit having an image bearing member on which the image is to be formed, a transfer unit configured to transfer the image from the image bearing member onto the sheet, and a fixing unit configured to fix the image to the sheet; a conveyance roller configured to convey the sheet having the image fixed thereto; a reading unit configured to read a pattern image on the sheet conveyed by the conveyance roller; and a detector configured to detect a pattern image on the image bearing member.

Example implementations relate to a system comprising a memory resource to store instructions executable by a processing resource. In some examples, the processing resource can execute instructions to perform a calibration procedure for a printing device including a printing component. Responsive to the calibration procedure, the processing resource can execute instructions to deliver a print material arranged in a compound shape to a calibration image on the printing component included in the printing device. Responsive to performing the delivery, the processing resource can execute instructions to measure a print material density of the print material on the calibration image of the compound shape during the calibration procedure via a density sensor included in the printing device. Furthermore, the processing resource can execute instructions to detect an abnormality in the print material density via signal analysis instructions and provide a notification regarding the print material density abnormality.

An image forming apparatus includes a platen on which an original is to be placed, a feeder configured to feed an original placed on a tray, a sensor configured to detect a sheet on the tray, a lamp provided to the feeder, a reader configured to read the original placed on the platen and to read the original conveyed by the feeder, an image forming unit configured to form an image on a sheet, and a controller. The controller is configured to control the image forming unit to form a first test image on a sheet, control the reader to read the first test image formed on the sheet placed on the platen, control a density of the image to be formed by the image forming unit based on a reading result of the first test image.

An image forming apparatus includes a light beam scanner to scan an image bearer by a light beam according to data on a pattern for image positional deviation correction and a developing device to develop a latent image of the pattern. The pattern is formed on the image bearer by scanning performed by the light beam scanner. The image forming apparatus includes a transfer belt to transfer the pattern to a medium, a sensor to read the pattern to obtain an amount of image positional deviation, a skew correction device to adjust a tilt of an optical member of the light beam scanner according to a skew amount to correct a skew and perform the image positional deviation correction according to the amount of image positional deviation, and circuitry to drive the skew correction device before the image positional deviation correction.

In one example in accordance with the present disclosure, a print device is described. The print device includes multiple consumable components. Each consumable component includes a portion of a hardware-based identifier. At least one sensor of the print device reads multiple portions of the hardware-based identifier. A controller of the print device combines the multiple portions of the hardware-based identifier and verifies the hardware-based identifier to determine an authenticity of the multiple consumable components.

An optical sensor includes a first light emitting diode (LED), a second LED, a first photodiode (PD), and a second PD. The first LED and the second LED are configured to irradiate an optical-axis center point of an intermediate transfer belt. The first PD is arranged at a position at which specularly reflected light of light emitted from the first LED and diffused reflected light of light emitted from the second LED are received. The second PD is arranged at a position at which diffused reflected light of the light emitted from the first LED is received.

An image forming apparatus includes a controller configured to control a first image forming unit such that while a plurality of images are being sequentially formed, a first pattern image is formed in a first sheet-to-sheet area between a first black image and a second black image among the plurality of images on a first photosensitive body, and control the second image forming unit such that while the plurality of images is being sequentially formed, a second pattern image are formed in a second sheet-to-sheet area between a first color image and a second color image among the plurality of images on a second photosensitive body. The first sheet-to-sheet area in a case where the first pattern image is formed without the second pattern image being formed is narrower than the first sheet-to-sheet area in a case where the first pattern image and the second pattern image are formed.

An image forming apparatus includes a first sensor configured to measure measurement images on a first photoreceptor, a second sensor configured to measure measurement images on an intermediate transfer member, and a controller. The controller controls a first image forming unit to form first measurement images, wherein the first measurement images are formed along a rotation direction of the first photoreceptor, and controls the first sensor to measure the first measurement images on the first photoreceptor. The controller further controls the first image forming unit and a second image forming unit to form a plurality of measurement images while a rotation speed of the first photoreceptor is being controlled based on a measurement result of the first sensor, wherein the plurality of measurement images are formed along the predetermined direction of the intermediate transfer member.