A color printing unit includes one printing station for each color along with one anode roller. A continuous transfer belt is guided over a deflection roller and a control roller. One or more sensors measure a property of reference markings printed on the transfer belt. A control device for controlling and adjusting the transfer belt acts on the control roller through an actuating motor as a function of the detected properties of the reference markings. The one or more sensors are arranged in the area of the control roller for the transfer belt, by which an additional tension roller saves costs and space. During the measurement, at least for the period in which the printed reference markings pass under the one or more sensors, relative movements between the one or more sensors and the control roller are ruled out.

A belt unit includes a belt that comprises at least one first recess part having an inner wall face and at least one second recess part formed on the inner wall face of the first recess part, and a drive body that drives the belt to rotate.

A belt slippage correcting device includes: a belt moving part that moves a belt in a width direction of the belt; a slippage detector that detects a slippage of the belt in the width direction; a hardware processor that controls a movement of the belt caused by the belt moving part based on the slippage of the belt detected by the slippage detector; and an acquisitor that acquires paper sheet conveying property, wherein the hardware processor controls an amount of movement of the belt caused by the belt moving part based on the paper sheet conveying property acquired by the acquisitor.

A belt slippage correcting device includes: a belt moving part that moves a belt in a width direction of the belt; a slippage detector that detects a slippage of the belt in the width direction; a hardware processor that controls a movement of the belt caused by the belt moving part based on the slippage of the belt detected by the slippage detector; and an acquisitor that acquires paper sheet conveying property, wherein the hardware processor controls an amount of movement of the belt caused by the belt moving part based on the paper sheet conveying property acquired by the acquisitor.

A position detection apparatus detects a position of a target object. One end of a swinging member contacts the target object, and the other end contacts a moving member. (M+1) pieces of sensors are arranged to output signals corresponding to a position of the moving member. Measured parts are disposed on the moving member along loci of measuring positions of the sensors. A detection unit detects the position of the target object based on the output signals of M pieces of sensors when the other sensor outputs a predetermined signal. The measured parts corresponding to the other sensor are provided in 2.sup.M pieces of divided areas that are disposed along a locus corresponding to the other sensor. Each of the measured parts corresponding to the other sensor is disposed in a center portion except both ends in the moving direction in each of the divided areas.

A belt device includes a belt member, a detected unit, a window, an optical detector, and a regulation member. The belt member is movable in a direction of belt movement. The detected unit disposed on at least one side of the belt in a width direction of the belt intersecting with the direction of belt movement and extending in the direction of belt movement. The window transmits detection light emitted toward the detected unit and reflected light from the detected unit. The optical detector detects the detected unit. The regulation member is disposed on at least one side in a width direction of the window to keep the detected unit away from the window.

A belt unit includes a belt that comprises at least one first recess part having an inner wall face and at least one second recess part formed on the inner wall face of the first recess part, and a drive body that drives the belt to rotate.

The intermediate transfer unit includes: an endless intermediate transfer belt which is turned around while carrying a toner image on its outer circumferential surface; and a plurality of rollers on which the intermediate transfer belt is turnably stretched, wherein the intermediate transfer belt has, on its inner circumferential surface, an information recording area in which belt information has been recorded, and the intermediate transfer belt has a mark at a position in the outer circumferential surface where a positional relationship between the mark and the information recording area comes to a specified relationship.

A position detection apparatus detects a position of a target object. One end of a swinging member contacts the target object, and the other end contacts a moving member. (M+1) pieces of sensors are arranged to output signals corresponding to a position of the moving member. Measured parts are disposed on the moving member along loci of measuring positions of the sensors. A detection unit detects the position of the target object based on the output signals of M pieces of sensors when the other sensor outputs a predetermined signal. The measured parts corresponding to the other sensor are provided in 2.sup.M pieces of divided areas that are disposed along a locus corresponding to the other sensor. Each of the measured parts corresponding to the other sensor is disposed in a center portion except both ends in the moving direction in each of the divided areas.