Abstract: A method of operating a printer in which, after positioning of a paper web for printing and the printing of the web, the last printed sheet is removed and the leading edge of the web is retracted in a park position. The retraction of the leading edge of the web from this proper printing position until it passes a sensor is detected and this difference in displacement of the drive is stored for correction of advance of the same web from the parking position subsequently.

Abstract: A printer has a drum with at least one slot for receiving sheet-like record carriers. The slot extends into the circumference of the drum and is dimensioned to receive clamping means for holding the record carrier with a clamping fit. The control of the clamping means is effected, for example, by means of disks which are secured adjacent the end faces of the drum and whose circumference is also engaged by the clamping means. The disks are provided at their outer side with a first stopper element, which resiliently co-operates with a second stopper element secured to the housing of the device in such a manner that upon rotation of the drum in the printing direction of rotation one stopper element slips over the other and upon rotation of the drum in opposite direction prevent the rotation of the disk. Thus, the clamping means are passed out of the slot.

Abstract: A matrix printer comprising a printing head which is pivotable, under the influence of the braking effect of a magnetic field, about an axis which is perpendicular to the line direction and to the surface of the paper to be printed. The different printing positions of the printing head realized by said pivoting motion are utilized for printing characters with a comparatively good recognizability at a comparatively low printing speed or, as desired, for printing characters which are less rapidly recognizable at a comparatively high printing speed.Matrix printers of this kind are used, for example, in text editing systems.

Abstract: A detachable paper transport device for a printer having a printing roller, using two transport chains. The device has two side walls on each of which a control lever is pivoted for selecting the spacing between the transport chain and the roller, to compensate for differences in the thickness or number of layers of the paper. The device side walls each have a slotted hole for engaging one member on the printer, and each control lever has a bearing lug for engaging another member on the printer to slide the device along the slotted holes.

Abstract: For the reliable guiding of a record carrier and the printing thereon as far as in the vicinity of the upper and lower edge, a pivotable device is arranged over the printing drum, said device comprising two or more flat hold-down devices which are arranged on a rotatable shaft. The hold-down devices can be slid into a first position in which they engage the printing drum and a second position in which they are lifted off the printing drum. In the first position, the record carrier is deflected to the printing drum during transport, and in the second position it is transported by additional pressure rollers. The device is pivotable about the printing drum into three positions and is constructed as a modular unit. This enables the simultaneous or alternating transport about the printing drum of different record carriers in a different manner.

Abstract: A paper web in an office machine is transported from the one side of a transporter (tractor) comprising a transport chain to the printing backing and back again on the other side of the transporter. In the case of multilayer paper webs, notably webs comprising more than four layers, an increasingly larger wave of the paper web tends to in front of the printing backing. In order to avoid such waves, the associated transporters comprise guide pieces for the paperweb which extend from the tractor to the vicinity of the zone of contact between the paper web and the printing backing and whose surface is situated at least substantially in the plane tangential to the printing backing at this zone of contact.

Abstract: A stylus printing head comprising a number of electromagnets which operate the printing styli and which are clamped on a conical carrier by means of a clamping device. The carrier comprises cradle-shaped, resilient supports for each of the electromagnets. The resilient supports compensate for differences in expansion of the electromagnets, the carrier and the clamping device in reaction to temperature variations occurring. The resilience of the supports is obtained by means of slots in the carrier which enable the use of a plurality of carriers in the same printing head.

Abstract: An electromagnetic drive for a recording pin of a matrix printer, comprising a cylindrical armature which is displaceable by means of an excitation coil and in which a clamping sleeve is provided which comprises an indentation which encloses the recording pin in a clamping manner and whose length governs the position of the recording pin.

Abstract: A method of manufacturing an electro-magnet, comprising two tubular poleshoes which are coaxially arranged with respect to each other and in which an armature is slidable, the inner surface of the poleshoes and the outer surface of the armature being successively degreased and pickled, after which they are provided with a nickel layer by electroplating, and a nickel phosphide layer formed by electroless deposition of a nickel-phosphorus layer which is converted to nickel-phosphide by heating to about 400.degree. C. The electromagnets manufactured by means of the method in accordance with the invention are particularly suitable for us in matrix printers.