An example method comprises operating a drive unit to advance a substrate in a substrate advance direction toward a printing station. At the printing station, a first line is printed onto the substrate. A drive unit is instructed to advance the substrate in the substrate advance direction by a target amount, and a second line is printed onto the substrate. The distance between the first and second lines in a direction perpendicular to the substrate advance direction is calculated and, based on the calculated difference, a tension of the substrate is modified.

In an example of the disclosure, a first optical sensor positioned adjacent to a web path and having a first sensor beam is utilized to identify a first signal value as the first optical sensor detects an eye-mark as the web is moved along the web path. A second optical sensor positioned adjacent to the web path, downstream of the first optical sensor, and having a second sensor beam, is utilized to identify a second signal value as the second optical sensor detects the eye-mark. A lateral misalignment of the web is determined based upon the first signal value, the second signal value, and a lateral offset of the first sensor beam from the second sensor beam.

An image forming apparatus includes a sheet conveyance portion, a recording portion, a sheet detection portion, and a control portion. In a duplex printing including a first and a second process of printing on a first surface and a second surface of the sheet, in the first process, the control portion calculates a center position of the sheet based on an edge position of the sheet on one side in the width direction and size information of the sheet, prints a first image on the first surface such that the first image is centered on the center position calculated, and prints a reference marker on the first surface. In the second process, the control portion calculates a correction magnification ratio based on a difference between a reading position and the printing position of the reference marker, and corrects a size and a printing position of a second image.

An image forming apparatus includes a sheet conveyance portion, a recording portion, a sheet detection portion, and a control portion. In a duplex printing including a first and a second process of printing on a first surface and a second surface of the sheet, in the first process, the control portion calculates a center position of the sheet based on an edge position of the sheet on one side in the width direction and size information of the sheet, prints a first image on the first surface such that the first image is centered on the center position calculated, and prints a reference marker on the first surface. In the second process, the control portion calculates a correction magnification ratio based on a difference between a reading position and the printing position of the reference marker, and corrects a size and a printing position of a second image.

A printer has a light source that directs light toward a print medium path. An RGB sensor is positioned to receive light from the light source that is reflected by the print medium. An infrared light filter is situated between the RGB sensor and the paper to filter out infrared light. A programmed processor is coupled to an output of the RGB sensor in order to detect form elements in the output from the RGB light sensor, retrieve a stored electronic representation of a form, match the form elements to the stored electronic representation of the form to identify locations on the form, and control printing to the form.

A printer according to an embodiment includes a conveying unit, a holding unit, a supporting unit, a second detecting unit, and a control unit. The conveying unit conveys paper. The holding unit includes a light emitting unit configured to radiate light and a first detecting unit configured to detect the light reflected on the paper. The supporting unit supports the holding unit to be movable in an orthogonal direction orthogonal to a conveying direction of the paper. The second detecting unit is disposed on an opposite side of the light emitting unit across a paper conveying path, on which the conveying unit conveys the paper, and detects the light radiated by the light emitting unit. The control unit determines, based on a detection result of the second detecting unit, whether the light emitting unit is present in a position opposed to the second detecting unit.

A printer according to an embodiment includes a conveying unit, a holding unit, a supporting unit, a second detecting unit, and a control unit. The conveying unit conveys paper. The holding unit includes a light emitting unit configured to radiate light and a first detecting unit configured to detect the light reflected on the paper. The supporting unit supports the holding unit to be movable in an orthogonal direction orthogonal to a conveying direction of the paper. The second detecting unit is disposed on an opposite side of the light emitting unit across a paper conveying path, on which the conveying unit conveys the paper, and detects the light radiated by the light emitting unit. The control unit determines, based on a detection result of the second detecting unit, whether the light emitting unit is present in a position opposed to the second detecting unit.

There is provided a printing apparatus including: a mark detector which detects a mark that is formed on a recording medium and has a width in a first direction in a detection region thereof, and is supported to be rotatable around a rotation shaft that is parallel to a second direction intersecting with the first direction; a driving portion which drives the mark detector in the first direction; an angle determination portion which determines a rotation angle of the mark detector that considers the rotation shaft as a center; and a control portion which matches positions of the detection region and the mark in the first direction by adjusting a position of the mark detector in the first direction by the driving portion based on the rotation angle of the mark detector which is determined by the angle determination portion.

A barcode printer includes a frame on which a paper receiving device, a printing device, a cutting device, and a paper output device are disposed. The paper receiving device receives a plurality of printing papers which is interconnected and folded in a zigzag manner. A front edge of the uppermost printing paper is inserted downward into a paper inlet passage of the printing device. A paper delivering motor moves the uppermost printing paper forward to pass through a gap between a printer and a paper delivering roller. A printer is activated to print a barcode on a lower face of the uppermost printing paper. The front edge of the uppermost printing paper is moved to pass through the cutter and the paper output roller unit. The paper delivering motor is then stopped, and a rear edge of the uppermost printing paper is cut under operation of a paper output motor.

In an example implementation, a method of adjusting frame length in an inkjet web press includes measuring a time T1 between a first sensor sensing a first mark and a second sensor sensing a second mark, and measuring a time T2 between the second sensor sensing the second mark and the first sensor sensing a next first mark. The method includes adjusting a gap between printed frames when T1 does not equal T2.