Abstract: A device and method for driving a polyphase DC motor, in which a phase selector circuit, in each case, selects only one phase, which is fed to a commutation detection circuit. After each commutation detected by a commutation detection circuit, as a result of a pulse of constant duration generated by a monoflop, the phase discriminator circuit and, as a consequence, the commutation logic are advanced in a fixed and preestablished sequence. This occurs irrespective of the rotation direction of the motor using the sequential logic device embodied by the commutation logic. When the motor rotates in the preferred direction, constant current-flow angles of 120° are achieved for each phase. When the motor rotates in the reverse direction, markedly varying current-flow angles of the individual phases are generated, and these varying current-flow angles, as a function of the course of the specifically corresponding voltages induced in the individual phases, result in a counter-torque.

Abstract: An electronically commutated motor includes a stator carrying a plurality of winding strands and a rotor in which the individual winding strands are controlled via power amplifiers in staggered periods of time, the periods being subdivided into control time and idle time. To reduce the power loss in the power amplifiers and to increase the efficiency in the range of high currents, that the control times are subdivided into an initial time segment and a final time segment. At low motor currents pulsing occurs only in the initial or final time segments in pulse width modulation, while at high currents complete switching through takes place in the initial time segments and additionally in the final time segment for a more or less long period of time or in the final time segments and additionally in the initial time segments for a more or less long period of time.

Abstract: An edge sensor working on ultrasonic principles is used to protect the edge of a travelling web and has a plurality of sensor units with adjacent or overlapping ultrasonic measurement fields between the transmitter and receiver of each unit. The units are switched so that only one unit serves to output a receiver signal when the edge crosses over into the respective measurement field.

Abstract: An edge sensor for a moving web of material includes an elongated light source on which is mounted a receiver containing an active receiver element made of a plastics material with light-absorbing properties. The receiver element comprises an elongated light input surface and at least one light exist on which a light detector is provided. The receiver element is an elongated hollow body made of a light-absorbing plastics material which is supported directly in the receiver in such a way that is light input surface is directly exposed to the light from the light source which falls on the web. A hollow body which is, or can be made, self-supporting directly and without accessories results in a simpler structure and optimal use of light. The hollow body is particularly suitable for use in the tube supports of a standard commercial fluorescent tube housing.

Abstract: A photo-electric scanning device 1, with tubular housings 2, 3 with light source 15 and receiving element 16 and 17, respectively, arranged transversely and enclosing a web between them. The receiving element 17 cooperates with the light source 15 either according to the reflection principle or the light barrier principle. For light source 15 two receiving elements 16, 17 are provided which are capable of being actuated, of which either the first 16 cooperates with the light source 15 according to the reflection principle or the second 17 according to the light barrier principle. The first receiver 16 is closer to the light source 15 than the second receiving element 17. In this manner, operation is continuous with both receiving elements 16, 17.