An image forming apparatus includes: an image forming unit configured to form an image on a recording material based on first image data; a controller configured to control an image forming operation by the image forming unit; an acquisition unit configured to acquire property information related to a property of the recording material; a setting unit configured to set a control value to be used in the image forming operation; a reader configured to read an image formed on the recording material by the image forming unit, and to output second image data; and a comparison unit configured to compare the first image data to the second image data, wherein the setting unit is further configured to set the control value based on a comparison result from the comparison unit and the property information.

An image forming apparatus includes an image forming portion, a rotatable intermediary transfer belt, a plurality of stretching rollers, an outer roller, a moving mechanism capable of moving a position of the inner roller between a first position and a second position, a recording material feeding member, a driving source, and a controller. The controller controls the driving source so that when an image is formed in a state in which the inner roller is in a first position, a speed ratio Vp/Vb wherein Vp is a driving speed of the feeding member and Vb is a driving speed of the intermediary transfer belt is a first speed ratio, and when the image is formed in a state in which the inner roller is in a second position, the speed ratio Vp/Vb is a second speed ratio smaller than the first speed ratio.

An image forming apparatus including an image forming device, a sensor, and a processor. The image forming device is to form an image on recording medium. The sensor is to irradiate light to the recording medium and detect an amount of light transmitted through the recording medium and an amount of light reflected from the recording medium, resulting in a control of a printing operation of the image forming device based the amount of light transmitted through the printing medium and the amount of light reflected from the printing medium.

An information which includes an image bearing member 1, an intermediary transfer belt 7, a transfer member 8, a voltage source 20 for applying a voltage to the transfer member 8, a detecting portion 21 for detecting a current flowing through the transfer member 8, and a controller 50 for carrying out constant-voltage control so that the voltage applied to the transfer member when a recording material P passes through a transfer portion N2 and in which the controller 50 is capable of changing the voltage applied to the transfer member 8 so that a detection result detected by the detecting portion 21 during transfer falls within a predetermined pass has a constitution in which said controller 50 changes the predetermined range on the basis of the detection result detected by the detecting portion 21 when the voltage is applied to the transfer member 8 in a state in which the recording material P is absent in the transfer portion N2.

A recording material characteristic detecting device that irradiates a first light and a second light to a recording material carried along a predetermined carrying path and detects a transmitted light generated when the first light transmits the recording material and a reflection light generated when the second light is reflected by the recording material, and detects a characteristic of the recording material, comprises: a reflection light source that irradiates the second light toward the carrying path; a reference plate for reflection light arranged oppositely to the reflection light source across the carrying path to reflect the second light; and a light detector arranged oppositely to the reference plate for reflection light across the carrying path to detect at least a reflection light generated in response to reflection of the second light. The reference plate has a higher reflectivity to the second light than a reflectivity to the first light.

Provided is a recording medium detection device which prevents a recording medium from jamming. The device comprises: a first roller and a second roller which nip and transport a recording medium; a roller shaft which rotatably supports the second roller; a shaft support; and a displacement detector. The shaft support supports the roller shaft movably in the thickness direction of the recording medium. The displacement detector detects displacement of the second roller in the thickness direction. The shaft support further supports the second roller movably in the transportation direction of the recording medium through the roller shaft.

An image forming apparatus includes: a sheet feeding tray that stores a sheet; a sheet thickness measurement device that measures a sheet thickness of the sheet fed from the sheet feeding tray; a hardware processor that: determines a type of the sheet of which the sheet thickness is measured, a sheet type associated with each of sheet thickness ranges, and the sheet thickness measured by the sheet thickness measurement device; and adjusts a first sheet thickness range to cause the first sheet thickness range to be expandable to at least one of an upper limit value side or a lower limit value side; and an image former that forms an image on the sheet fed from the sheet feeding tray under image forming conditions corresponding to the sheet type determined by the hardware processor.

An image forming apparatus includes an image forming unit to form an image on a sheet conveyed from a sheet storing unit by a sheet conveying unit, and a registering unit that registers detected sheet thickness information and detected sheet surface characteristics information. Based on information, distinct front and back surfaces of a conveyed predetermined sheet and a type of the conveyed predetermined sheet is determined. If the predetermined sheet type matches a type of an upcoming sheet on which the image will be formed and the determined front and back surfaces matches front and back surfaces of the upcoming sheet, an image is formed on the predetermined sheet. If the predetermined sheet type matches the upcoming sheet type and the determined front and back surfaces do not match the upcoming sheet front and back surfaces, information is displayed conveying that the predetermined sheet front and back surfaces are inverted.

A transfer device includes a rotatable image bearer configured to bear a toner image to be transferred to a recording medium, a first rotator, and a second rotator. The second rotator is configured to contact the first rotator via the rotatable image bearer to form a transfer nip in which the recording medium is sandwiched. The second rotator is rotatable with the image bearer. The transfer device satisfies a conditional expression (t1+R)/(t2+R)>0.98, where t1 represents a thickness of a thinnest recording medium, t2 represents a thickness of a thickest recording medium, and R represents a radius of curvature of the transfer nip.

An image forming system includes an image former that forms an image on a sheet, a reader that reads the image formed on the sheet by the image former, and a hardware processor that controls a conveyance speed of the sheet at the reader in accordance with a physical property value of the sheet.