Abstract: A laser scribing installation for the treatment of grain oriented magnetic sheets, as strip in longitudinal movement, comprising a laser generator for a laser beam, a cylindrical telescopic optical group with varying focal distance for the formation of a laser beam with elliptic section having varying ellipticity as function of the focal distances and a rotating mirror scanner for scanning the laser beam according to a pre-defined angle. The scribing installation further comprises a parabolic reflector extended transversally to the strip for receiving the scanned laser beam and focusing the beam on the strip, as a greatly lengthened elliptic spot, along a treatment path, and wherein the telescopic group is adjustable for modifying the length of one of the axes in the elliptic section of the laser beam incident on the strip.

Abstract: A laser scribing installation for the treatment of grain oriented magnetic sheets, as strip in longitudinal movement, comprising a laser generator for a laser beam, a cylindrical telescopic optical group with varying focal distance for the formation of a laser beam with elliptic section having varying ellipticity as function of the focal distances and a rotating mirror scanner for scanning the laser beam according to a pre-defined angle. The scribing installation further comprises a parabolic reflector extended transversally to the strip for receiving the scanned laser beam and focusing the beam on the strip, as a greatly lengthened elliptic spot, along a treatment path, and wherein the telescopic group is adjustable for modifying the length of one of the axes in the elliptic section of the laser beam incident on the strip.

Abstract: A direct-current electric motor (29) used for, for example, positioning a printing device in an office machine, is controlled by an arrangement comprising a microprocessor (40) which causes the motor digitally to perform accelerations and/or decelerations to maintain it close to a desired speed programmed in relation to the distance to be completed. Control between the actual speed of the motor and the desired speed is effected utilizing the timing signals (FTA, STB) generated by a transducer (35) connected to the motor. During a first phase, the microprocessor compares the times taken to complete a series of angular steps of rotation, the steps following a schedule of decreasing size with stored reference times and effects accelerations and decelerations of durations proportional to any discrepancies.