Process and device for detecting the presence of an object, preferably a leaf sheet-shaped or sheet-shaped object for printing

Abstract

Detecting the presence of an object, preferably a leaf sheet-shaped or sheet-shaped object on a transport path, especially for preparation and / or control of a processing of the object, preferably for printing the object in a printing machine, especially a digital printer, where the object is transported on the transport path past a sensor device, preferably a photoelectric barrier, for detection and registration of the front edge of the object in the transport direction. After detecting the front edge of the object and / or its entrance into the measurement area, it is checked at least once to determine whether the object continues to be present in the measurement area of the sensor device.

Description

FIELD OF THE INVENTION[0001] The invention involves a process and device for detecting the presence of an object, preferably a leaf sheet-shaped or sheet-shaped object on a transport path, especially for preparation and / or control of a processing of the object, preferably for printing the object in a printing machine, especially a digital printer, where the object is transported on the transport path past a sensor device, preferably a photoelectric barrier, for detection and registration of the front edge of the object in the transport direction.BACKGROUND OF THE INVENTION[0002] In the operation of a digital printer, in particular, during the operation of an electrophotographic printer, the imaging operation for printing must be prepared for each sheet to be printed, because a permanent printing block or mold is not used (non-impact printing). That is, the printed image must be recreated for each sheet to be printed, even if the printed image does not change from sheet to sheet. Thi...

AI Technical Summary

Benefits of technology

[0004] The purpose of the invention is thus to improve a process and / or a sensor device to the effect that in spite of high precision, the danger of erroneous detection is reduced. This purpose is achieved in regard to the process in that after detecting the front edge of the object and / or its entrance into the measurement area, it is checked at least once to determine whether the object continues to be present in the measurement area of the sensor device. By this measure according to the invention, it can be reliably ensured that a more expansive object has actually entered into the measurement area of the sensor device and not a local position of interference that only gives the impression of an object.

[0005] According to another embodiment of the process according to the invention, the check is done multiply at defined intervals that can be relatively small, in that the sensor device operates by clock pulses. In this way, the entrance and exit of the object can be detected precisely and it can be recognized that in this entire detected area, only an extended object is present. In the process, the clock pulsing according to the invention can be time-referenced or path-referenced, whereby a timed frequent clock pulsing is allocated to corresponding path distances via another path measurement and can be converted into these path distances. However, different results and advantages result for the different clock pulsings. A timed clock pulsing can be implemented directly for the sensor device and is sufficient if the sensor device itself should make the decision about the presence of an object. If the clock pulsing is performed in a manner referenced to the path distance, the clock pulsing is only as uniform in time as the movement of the transport device used. However, this has the advantage for the direct preparation control, e.g. of an electrophotographic printer, that transport speed fluctuations no longer falsify the measurement result.

Problems solved by technology

One problem, however, can be that the sensor device should detect the entrance into its measurement area in as precise a manner as possible so that the measurement area of the sensor device, for example, through a narrow slit, is set to be as small as possible in order to, in this way, select the measurement inaccuracy that results from the extension of the measurement area itself, to be as small as possible.

A precise sensor device of this type is namely also subject to slight interference effects by phenomena in the measurement area, which mediate the appearance of an existing object.

For example, slightly extended, local damages, such as scratches or soiling, can also readily trigger the sensor device and in this way lead to erroneous triggerings or erroneous switchings of the imaging device of an electrophotographic printer.

Images