Example implementations relate to determining a correction factor that converts a measured sensor distance (228) to a calibrated sensor distance (222). The measured sensor distance may be based on an amount of substrate advancement through a web printing press (202) between detecting a mark (226-1, . . . , 226-N) on the substrate (204) at a first sensor (212) and detecting the mark at a second sensor (214). The calibrated sensor distance (222) may be the separation between the first sensor and the second sensor.

In one example of the disclosure, an uncalibrated sensor may be calibrated. Calibrated sensor data is obtained. The data relates to an amount of light transmitted through an ink solution of a first colour as a function of ink concentration. An amount of light transmitted through an ink solution of the first colour is measured, using the uncalibrated sensor, at a plurality of ink concentrations. A calibration factor relating the light transmission of the calibrated sensor for the first colour and the light transmission of the uncalibrated sensor for the first colour is determined, using a processor, based on the obtained data and the measurements.

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).

An image forming apparatus includes a first execution circuit, a second execution circuit, and a display circuit. The first execution circuit is configured to execute a first calibration. The second execution circuit is configured to execute a second calibration. The first display circuit is configured to, in a first notification related to a setting of a calibration, display a first object for prompting the execution of the first calibration and not display a second object for prompting the execution of the second calibration, in a first notification related to a calibration setting.

According to some examples, a skew detection device comprises a first roller rotatable around a first axis, a second roller rotatable around a second axis, a first sensor, and a second sensor. The first sensor measures a first rotation parameter from the first roller and the second sensor measures a second rotation parameter from the second roller. A movement of a print media over the device rotates the first contact roller and the second roller, and a controller determines a skew of the print media based on the first and second rotation parameters captured by the first sensor and the second sensor.

According to an embodiment, a sheet conveying device detects double feeding of sheets by an ultrasonic wave oscillator and an ultrasonic waves receiver provided across a conveying path of the sheets. The sheet conveying device calibrates a threshold voltage on the basis of an offset voltage of an amplifier circuit when the receiver has not received ultrasonic waves.

In an example, a print apparatus includes a controller and a printing unit. The controller may control the printing unit to print a media sheet with at least one indicia indicating an intended location of a fold line, wherein the media sheet is to be folded along the fold line. The controller may be to control the printing unit to print the at least one indicia to provide an offset gauge such that, when the media sheet is folded along a formed fold line, the indicia provides an indication of an offset between the intended location of the fold line and the formed fold line.

In some examples, a controller receives an indication from the printing system to initiate a calibration. In response to the indication, the controller activates a sensor assembly as part of a calibration operation that comprises emitting a signal toward a calibration surface of the media output accumulator, and detecting a reflected signal responsive to the emitted signal. The controller calibrates the sensor assembly based on the reflected signal, the sensor assembly to detect a level of media sheets, ejected by the printing system, into the media output accumulator.

A medium transport apparatus includes a medium transport path through which a medium passes, a path state detection section configured to output a detection value corresponding to a state of the medium transport path, a control section configured to compare the detection value output by the path state detection section with a threshold value for the detection value and determine whether an abnormal condition has occurred in the medium transport path, and a storage configured to store history information including the detection value acquired in the past, in which the control section changes the threshold value based on the history information.

This application provides a roller, an inspection method for a camera, a camera inspection apparatus, a coil conveying method, a coil conveying apparatus, an electronic device, a computer-readable storage medium, and a computer program product. The roller includes a roller body and a calibration sheet. The roller body includes a roller surface for supporting a coil; the calibration sheet is located on the roller surface of the roller body and avoids the coil, and the calibration sheet is used for inspection of the camera.