Veb Polygraph Leipzig Kombinat Fur Polygraphische Maschinen Und

Veb Kombinat Polygraph 'werner Lamberz Leipzig'

Albrecht Johne

Hans Johne

Karl-Heinz Forster

Horst Schulz

Gunter Weisbach

Alfred Schott

Hans-Jurgen Tappert

Werner Lein

Helmut Schone

Klaus Schanze

Lothar Vetter

Rainer Nitsch

Rudi Riedl

Regina Jungnickel

A pressure control arrangement for controlling pressure between a printing roller and an offset roller by measuring a force exerted in a bearing of the printing roller when the latter rotates with an angle .psi.. The arrangement includes a piezoelectric pickup positioned on the internal surface of the bearing of the printing roller, a measured pressure value processor for receiving a signal from the piezoelectric pickup, an indicator generating a signal corresponding to a desired pressure value and means to compare the first abovementioned signal with the second mentioned signal. The arrangement also includes a positioner circuit which receives the compared signal and applies the same to a drive member which adjusts the position of the bearing of the offset roller thereby adjusting printing pressure between two contacting rollers for printing on sheets of paper.

Device for printing-pressure control

A detecting capacitive structure undergoes changes in capacitance value depending upon whether it is detecting, in the sheet transport path of a printing machine, a normal or single sheet, an absent sheet, or a double or stuck-together sheet, so that corrective action can be initiated, such as the skipping of a printing cycle. The detecting capacitive structure and also a reference capacitive structure constitute the capacitances of two RC circuit stages to which an input signal is applied and then removed. The variations with respect to time of the output signals from the two RC circuit stages are then compared, both during application of the input signal and subsequent to removal of the input signal. This comparison of time responses of the two RC circuit stages serves as the basis of the detection. The effect of the normal, absent or double sheet upon capacitance value is detected by monitoring a response dependent upon the time-constants of the RC circuit stages, without the detecting capacitive structure forming the capacitor of or resonant circuit.

Capacitive detection of absent and/or double sheets in the sheet

A printing machine receives single sheets which are removed from a stack by the suction cups of a feeding mechanism which is combined with a monitoring unit serving to detect the absence of sheets at the undersides of suction cups or the lifting of two or more sheets. The monitoring unit employs a transducer having two feelers which determine the thickness of lifted sheet material and an indicating device which is actuated by the feelers and produces signals serving to indicate the absence of sheets, the lifting of two or more sheets and/or to control the operation of the printing machine. The suction cups can form part of the transducer when the latter is designed to detect only the absence of sheets or they form part of a second transducer which is provided in addition to the first mentioned transducer.

Method and apparatus for controlled feeding of sheets to printing

In first and second modes, the arrangement prints on only one side or on both sides of a sheet, respectively. A sheet is transported along a predetermined path through the arrangement and passes printing devices cooperating to effect printing of the sheet. Changeovers from one to the other mode alter a portion of the sheet transport path, changing its length. A control system for the arrangement includes a shift register. When a sheet arrives at a predetermined location along the path, a sheet-representing signal is applied to the shift register. Shifting pulses applied to the shift register in synchronism with sheet travel cause the sheet-representing signal to travel through the shift register in simulation of sheet travel. As the sheet-representing signal reaches preselected shift-register stages, it causes an actuator associated with such stage to actuate a respective printing device. Thus, the printing devices are controlled in dependence upon the arrival of the sheet at predetermined portions of the path. Upon a change of operating mode, a compensating unit is operable for at least partially offsetting changes in the correlation between shift register stages of the shift register and the associated portions of the path.

Printing arrangement alternatively operated for one-side printing and

Growing community of inventors

Dresden, Germany

Albrecht Johne