Abstract: An identity card or credit card type of card is equipped with a validity-checking device that makes it possible to do away with the use of complementary, sophisticated checking equipment. It results from the association of a structure S.sub.1 comprising at least one layer of piezoelectric material and a structure S.sub.2 comprising a material capable of switching electrically between two optical states (I) and (II) that are different in terms of ocular perception. During the bending of the card, the validity or non-validity of the card can be attested to by the appearance or non-appearance of the validity of the card.

Abstract: The apparatus comprises an X-ray source (6) to generate a beam of radiations (7) through an object (4) or the body of a patient to be examined and a multichannel detector (8) to provide information concerning the intensity of the radiation retransmitted by the object examined. Both the source and detector are mounted on a rotor (2) integral with the stator (1) which surrounds the object (4) examined. It also comprises at least one lateral diffusion light guide (14, 15) wound round the rotor (2) or on the internal surface of the stator (1) to transmit optically between optical receiver and emitter means (9, 10) of the rotor (2) and corresponding optical means (16, 17) of the stator (1), the information provided by the multichannel detector (8) and the control information of the X-ray source (6).

Abstract: Magnetic head structure, including a layer (S1, S2) of a material, such as Sendust, deposited on the magnetic poles and a carbon-based layer (C1) deposited on the preceding layer. The layer (S1, S2) made of magnetic material which has a high coefficient of bonding relative to the magnetic poles and to the carbon-based layer.

Abstract: The apparatus comprises an X-ray source (6) to generate a beam of radiations (7) through an object (4) or the body of a patient to be examined and a multichannel detector (8) to provide information concerning the intensity of the radiation retransmitted by the object examined. Both the source and the detector are mounted on a rotor (2) integral with the stator (1) which surrounds the object (4) examined. It also comprises at least one lateral diffusion light guide (14, 15) wound round the rotor (2) or on the internal surface of the stator (1) to transmit optically between optical receiver and emitter means (9, 10) of the rotor (2) and corresponding optical means (16, 17) of the stator (1), the information provided by the multichannel detector (8) and the control information of the X-ray source (6).

Abstract: Thermomagnetic recording head for use in magnetic tape recording, comprising a layer of a ferromagnetic material set in the vicinity of a magnetic recording medium. A heating means is used to heat the layer of ferromagnetic material locally to a temperature that reaches the Curie point of the ferromagnetic material. Each heated zone is thus demagnetized and constitutes a recording gap for the recording medium.

Abstract: A magnetoresistance-effect sensor for use in a magnetic domain detector for reading data recorded on magnetic tapes or in magnetic bubble memories mainly consists of a layer of semiconductor material which carries a layer of ferrimagnetic material on one face and at least one pair of electrodes disposed along an axis OX on the other face, the layer of ferrimagnetic material being placed in proximity to the magnetic data carrier. A magnetic data item thus induces a magnetic field in the layer of semiconductor material in a direction OY perpendicular to the axis OX of the pair of electrodes.

Abstract: The magnetic recording device with rotating head according to the invention comprises a magnetic recording medium, a cylindrical and rotating head, a fixed magnetic excitation circuit; the head comprising, on its surface, two movable pole pieces separated by a gap and each magnetically linked to an initial and a second magnetic circuit in the shape of a portion of a ring and providing a rotating joint to the passage of the magnetic flux, with the fixed, magnetic excitation circuit possessing an excitation coil that induces an magnetic field in a magnetic circuit having two fixed pole pieces, each magnetically coupled by a gap to one of the said rings.Application: Video tape recorders in particular.

Abstract: The present invention relates to systems for the optical read-out, by reflection, of a data carrier. The present invention provides a read-out system in which two spots are projected which straddle the track being read-out. This method of projection makes use of a projection objective lens associated with an optical deflecting element in the form of a prism or a plate with parallel faces. The beam illuminating the track is split into two halves by a plane section containing the optical axis of the objective lens. The invention may be used for reading out data carriers upon which television signals are recorded.