Abstract: The invention concerns a microcircuit card of the kind comprising:a communication interface;an internal memorypa wired processor unit allowing this internal memory to be addressed from the outside.According to the main characteristic of the invention, provision is made for a secret internal memory zone not addressable from the outside, and the processor unit comprises a wired circuit capable of using the contents of the secret memory for establishing a first serial cryptographic function of two operands and means reacting to the interrogation of predetermined addresses of the internal memory, accompanied by a keyword by applying this keyword and the output of the internal memory as operands of the wired circuit, whilst the output of the wired circuit is applied to the interface.

Abstract: A filtering cell including a resonant circuit having an inductor and capacitor connected in parallel, the inductor being separated into two identical inductors which are connected in series with a midpoint therebetween. A second capacitor is connected at the midpoint and has a quality factor substantially equal to a quality factor of the first inductor, resulting in attenuation at the resonant frequency. Each of the inductors and capacitors are formed by micro-ribbon technology.

Abstract: Device able to continuously tune a coherent and rectilinearly polarized light source. It includes an electro-optical device (5) forming a spectral filter with an electrically modulable transfer function, this electro-optical device being provided so as to select a particular longitudinal mode from all the longitudinal modes able to oscillate inside the external cavity for which the source (1) is provided and which is ended by a reflecting device (3) towards the source of the light emitted by this source, and an electro-optical device (4) for varying the optical length of the cavity, this variation device being placed in the cavity and provided so as to continuously move the position of the selected longitudinal mode, each electro-optical device including a compact electro-optical crystal.

Abstract: A semiconductor device capable of producing a multiwavelength laser effect comprising a substrate having thereon at least two double heterostructure stacks, each stack comprising at least one active layer bounded by two confinement layers, the stacks being in the form of elongated strips disposed side-by-side, electrically insulated from each other. Each stack comprises a P-N junction therein which is individually and electrically operable and which is situated in the vicinity of an active layer of a different composition and rank in each stack. The transverse opposite ends of the strips are optically prepared and the upper surfaces of the strips form an upper surface for the device which is substantially flat.

Abstract: An image system (SPI) provides an image file which is recorded in a memory (3). A segmentation and framing module (M1) isolates each of the characters in the image file within individual matrices. A module (M2) finds primitive shapes in each character matrix by initially finding strokes therein and then substracting the strokes from the matrix. A module (M3) then makes a description of primitive shapes in the form of at least one partially ordered list of primitive shapes, and a module (M4) compares said description with standard description expressed in the same manner in a data base (M5). Character recognition, per se, is performed by determining the distances between the description of a character to be identified and the standard descriptions.

Abstract: This polarization beam splitter for guided light is e.g. produced on Z-propagating, X-cut LiNbO.sub.3 :Ti and comprises in series a passive Y-junction (66), an active phase shifter (68) and an active directional coupler (70), independent of the polarization and able to constitute a 3 dB coupler. Thus, on supplying a light wave to the input of the Y-branch and with the coupler constituting a 3 dB coupler, the TM and TE modes of the input wave are respectively obtained at the outputs of the coupler by appropriately polarizing the phase shifter. Application to optical fiber sensors or transducers and to the coherent transmission of information by monomode optical fibers.

Abstract: This invention relates to a process for surface treatment of a substrate carried by an electrode and immersed in a sealed engraving or deposition chamber equipped with plasma generating means, of the type involving the application to the electrodes, of a variable voltage, produced by a generator that is independent of the plasma generating means, wherein said process comprises the steps of:maintaining within said chamber a continuous plasma that is free of electromagnetic fields;supplying said electrode via a low impedance capacitor using a signal comprised of rectangular voltage pulses having:a variable pulse repetition rate to control the energy distribution function of the positive ionic charges bombarding the substrate,a variable mark-to-space ratio for each pulse to control the time distribution of the negative electron charges and the positive ionic charges bombarding the substrate, anda variable pulse amplitude to control the energy of the positive ionic charges bombarding the substrate.

Abstract: For processing data signals representative of pixels, each of the pictures s scanned, column per column in successive horizontal bands each having a height equal to an entire fraction of the height of the picture, whereby a representation of the picture as pixels distributed in rows and columns is obtained, each band having a common predetermined number of rows. The picture is fractionated into mutually adjacent blocks of pixels each having M pixels in each of N mutually adjacent columns, M and N being predetermined integers and M being a simple multiple of the number of pixels in one column of a band and N being a whole fraction of the number of colums per image.

Abstract: An end equipment comprises a subscriber line interface, a communication controller, a demultiplexing circuit, a multichannel receiving circuit, a multiplexer and a network line interface. The demultiplexing circuit receives data words at a rate n.D from the subscriber line, whereby n is an integer between 1 and a maximum value N. The data words are multiplexed in n independent channels selected among N multiplexed channels in a telecommunications network link at rate N.D. Each of N channels has a basic rate D. During a setting-in and synchronizing phase of a communication, synchronization frame bits are transmitted in the n selected channels. In a multichannel receiving circuit, the synchronization bits in n reception channels of the network link are detected sequentially, and a synchronization is carried out channel by channel.

Abstract: Method and device for the optical filtering and photodetection of intensity-modulated optical signals.Signals are injected into at least one resonating type semiconductor laser amplifier (2) close to the active layer (14) of this amplifier, the latter being polarized below its threshold current and having at least one resonance wavelength adjusted so as to coincide with the wavelength of at least one of the optical signals in order for this optical signal to be amplified by the amplifier, and the voltage existing between the terminals of the amplifier is detected so as to obtain, in the form of an electric signal, the information carried by the amplified optical signal when the angle between the polarization direction of the latter and the direction of the active layer is small.Application for the embodiment of optical receivers.

Abstract: A binary multiplier circuit has a logic operator acting as an exclusive-OR gate generating a first intermediate signal which is an exclusive-OR of a first input and a carry-in input. An inverter generates a second intermediate signal. A second logic operator generates a first output bit which is a symmetrical exclusive-OR of a second input and both the first and second intermediate signals. A second output bit is a symmetrical trigger function of the first and second input, depending on the first and second intermediate signals, and is generated in a transmission gate. Since the carry-in signal passed via the first and second intermediate signals is applied directly to transistors of the transmission gate, carry propagation delay is reduced. A fixed operand is multiplied by a variable operand by storing a partial result of the multiplication using an accumulator and a shift register with the binary calculation circuit.

Abstract: A display screen allowing for the visual display of the contour of an image and a method for controlling such a screen. According to the present invention, the counterelectrode is etched on elementary motifs electrically insulated from each other. Each motif covers part of the addressed electrodes. The display of the image is effected normally, but with the possibility of having its contour appear without using additional means. Such a device finds particular application for display screens.

Abstract: An SOI MOS transistor comprises at least a highly doped lateral stripe (13, 14) of the same conductivity type as the substrate (3). This stripe extends along the edge of the substrate and of the source region (5) and is shorted with the source region through the conductive source layer (11).

Abstract: A sound signal coding method and installation are disclosed, which method, usable particularly for transmitting or storing high quality audio signals in digital form, involves chopping the sound signal into blocks of samples and subjecting the samples of each block to time-frequency transform coding whose coefficients are transmitted in digital form, the reverse operations taking place at reception. At least the most significant coefficients of the transform of each block are subjected to predictive and adaptive coding using the stationary state of the signal over a duration greater than that of a block.

Abstract: The station, in particular a terminal, comprises an oscillator (OS) having a feedback loop (1) and a station inductor element (L10) suitable for conferring a working frequency to the oscillator which varies relative to a rest frequency. The station also includes a station processor connected to the oscillator and capable of processing variations in the working frequency of the oscillator. The portable object, in particular a memory card, includes an electronic circuit which is switchable between an inactive state and an active state in which it sets up a resonant circuit tuned on a frequency which is distinct from the rest frequency while remaining suitable for being coupled inductively with the feedback loop (1) at the rest frequency. The portable object also includes an object processor capable of switching the electronic circuit as a function of the information to be transmitted to the station.

Abstract: A holographic method of the type implementing a conoscopic system including a birefrigent crystal inserted between two polarizers and a photosensitive element, wherein the method includes a step consisting in inserting one-dimensional optical means on the path of the light rays such that the conoscopic system only collects light that is parallel or quasi-parallel to a plane including the axis of the conoscopic system. The invention also provides apparatus for implementing the method.

Abstract: A holographic apparatus of the type comprising a conoscopic system including a birefringent crystal inserted between two polarizers, wherein the apparatus also includes an aperture angle limiter inserted on the path of the light rays and wherein one of the birefringent crystal and the aperture angle limiter is disposed off the optical axis of the apparatus.

Abstract: The method embodying the invention authorizes communication bit rate reservations in a packet switching network. According to the method, a new communication is only accepted by the network if the communication does not exceed a maximum bit rate flowable by the switches of the network. A packet switch in the network comprises a bit rate reservation device for memorizing bit rate informations that are representative of total bit rates flowed by the switch and for processing said information as a function of data carried by service packets. The bit rate reservation device mainly comprises registers respectively associated with multiplex ways of the switch for memorizing the bit rate informations, an adder for incrementing and decrementing the bit rate informations as a function of service packet data, and a comparator for detecting overstepping of the maximum flowable bit rate.

Abstract: Method for producing a display screen with a matrix of transistors provided with an optical mask. This method consists of depositing on a substrate (100) a layer of black polyimide (102) absorbing the visible light and followed by a layer of photosensitive resin, of insolating the resin through a mask masking the channels of the transistors to be embodied, of eliminating the zones insolated with the resin and the sub-adjacent zones of the polyimide, of depositing an ITO layer (106) on the unit, of eliminating the rest of the resin and the ITO surmounting said resin so as to form the drains/sources of the transistors, of successively depositing a layer of hydrogenated amorphous silicon (110), a layer of silicon nitride (112) and a layer of aluminium (114), then of photoengraving the stack of these layers so as to form the grid of the transistors, and finally to render passive the unit with a layer of silicon (116).

Abstract: The process of the invention consists of subjecting a metal oxide coating (106, 108), located on a glass substrate (100), to the action of a gaseous plasma (109) containing 10 to 88% by volume of hydrogen, 2 to 30% by volume of a hydrocarbon and 10 to 50% of an inert vector gas, bringing about the formation of a polymer coating (110) on the parts of the substrate not provided with oxide, by dissocation of the gaseous mixture, and the partial chemical etching of the oxide (106, 108) by the formation of organometallic compounds.