Abstract: Data is recorded on a magneto-optical carrier (5), the magnetization of which in each recorded area is capable of reflecting a polarized laser beam (28,31,33) with rotation of the plane of polarization due to the Kerr effect in accordance with the direction of megnetization of the area. The plane of polarization of the beam (33',31',28',34) which is reflected in that way is rotated through about 45.degree. by a half-wave plate (35), the output beam (36) of which is resolved into two components by a prism (39). They are such as to permit discrimination between the two reading signals produced by respective detectors (43,44) in accordance with the sign of the output of a comparator (45).

Abstract: A cartridge for a printing ribbon for a typewriter having a character-carrying disc comprises a casing and two oscillating arms between the ends of which a run of the ribbon extends in a straight line on the outside of the casing between the disc and the platen. The arms oscillate from a rest position in which they make the typing point visible, to three or more working positions in which they make it possible to print using one of three tracks of the ribbon. The two oscillating arms are pivoted by means of pins on seats of fixed supports of the casing. Pivotally mounted at the free end of each arm is a guide element, a stem of the guide element being received in a sleeve of the arm. Each guide element is thus capable of modifying its angular position with respect to the respective arm in response to the selection movement so that the ribbon is always held in tension in a uniform manner, irrespective of the track selected.

Abstract: In a digital system for amplitude modulation, the logical signal at acoustic frequency is modulated by means of an ultrasonic frequency signal, the duty-cycle of which can be varied by means of a program. More particularly, the modulating signal is generated by a cyclic counter. The duty-cycle is programmed by writing the corresponding numerical value to a register with a capacity equal to that of the counter. An adder, adding the value of the counter each time to that of the register, generates a carry signal which gives consent to the acoustic signal only for a part of the relative cycle of the modulating signal.

Abstract: The print apparatus comprises a character-carrying element of the `daisywheel` type with flexible spokes which can be selectively positioned in front of a platen roller, a print hammer for moving a selected character towards the platen roller, an actuating solenoid for the print hammer and a damping mechanism which acts on the hammer after the printing of each character. The hammer is directly connected to a movable armature of the solenoid and is returned by a return spring.During the return phase, the armature displaces, against a travel limiting stop, a counteracting weight which is urged towards an intermediate stop by the force of a counteracting spring. A first damping element is disposed between the movable armature and the counteracting weight and a second damping element is disposed between the weight and the travel limiting stop. The two damping elements, operating sequentially, minimize the time required for the hammer to settle down.

Abstract: The key comprises a movable part guided in a fixed support on a base plate and contacts which are closed when the key is depressed against the action of a return spring. The symbol associated with the key is displayed through a window in the key top by an LCD device with a matrix of display areas controlled by an integrated circuit bonded to the underside of the LCD device and fed with signals from the CPU via conductors which enable the integrated circuit to be programmed to define the symbol to be displayed, whereby the keys of a keyboard can be set to match the language currently being used. In an alternative embodiment the key is supported by a flat cable connected with an input circuit of the keyboard and the terminals of the LCD device.

Abstract: The sheet feeder can be mounted on a typewriter or on a printer in a system for processing data. The sheets which are accommodated in a feed magazine are passed to the platen roller by friction stripper rollers. After the printing operation, the sheets are passed on to a collection table positioned in front of the feed magazine. The stripper rollers are permanently connected to the platen roller by way of a mechanical transmission and rotate in the same direction as the platen roller. The stripper rollers are mounted on an oscillating arm to be selectively moved towards or away from the first sheet to be fed, by means of a first cam. Before a fresh sheet is fed, a second cam, also coupled to the platen roller, has to be brought to a reference position by rotating the platen roller enough to expel the current sheet. The platen roller is then rotated in the reverse direction, whereby the second cam actuates a lever, thereby to close a clutch.

Abstract: The logic signals (S0, S1, S2, HL) which define the pixel are combined together with the synchronization signals (HS, VS) by a composer circuit (19) disposed in the display control, to form a single composite signal. The composer circuit (19) is connected by way of a single conductor (21) to a separator circuit (29) for separating the synchronizing signal, disposed in the VDU control circuit (20). The VDU control circuit comprises horizontal and vertical deflection circuits (27, 43 and 28, 44) for a CRT (24) and further comprises a format selector circuit (30) which is capable of sensing the duration of the vertical synchronizing pulse to control the frequency of the video signal vertical deflection circuit (28, 44).

Abstract: A cartridge for a multistrike typing ribbon for printing machines engages a single drive shaft for unidirectional advance movement of the multristrike ribbon and comprises a container having a bottom and two arms which project from a rear wall and which each have an aperture for the ribbon to pass therethrough. An epicyclic transmission arrangement is disposed on the bottom and comprises a series of toothed gears which are coplanar with each other and parallel to the bottom. The drive shaft is engaged with a feed sleeve of the cartridge and is coaxial with the feed roller for the ribbon. The feed sleeve is fixed with respect to the sun gear of the arrangement, the sun gear being engaged with the planet gear which in turn is rotatable on an eccentric pin of a plate. The plate is fixed with respect to a second sleeve which is rotatable about the sleeve and on which the feed roller is fixed.

Abstract: The printer is mounted on a desk-top computer and can print both numeric characters and graphic and calculation symbols in two different colors. The characters and the symbols are provided in a relief configuration in accordance with a matrix of rows and columns on a rubber sheet wrapped around a rotatable drum. The characters in adjacent columns are inked by an inking roller formed by adjacent porous discs which are alternately impregnated with red and black ink. The drum can perform a translatory movement in the axial direction selectively to present to the printing hammers the columns of characters which are linked with black and the columns of characters which are linked with red. The drum is translated fixedly with respect to the inking roller by means of a cam which rotates at a speed half the speed of the drum and engaged with one or other of two cam follower pins which can be selected by means of a solenoid.