Abstract: An indirect electrostatic printer is characterized in that the intermediate medium in the form of a dielectric tape (1) is mounted in an open loop defined by a supply reel (2), an auxiliary roller (4) over which its path doubles back and a take up reel (3), and in that said auxiliary roller (4) and an associated pressure roller (14) define a combined station (7) for simultaneously transferring and fixing the image on the final medium which is in the form of individual sheets (8), and said auxiliary roller and said pressure roller constituting, together with said tape (1), means for conveying the sheets to a copy delivery station (15).

Abstract: A hard vacuum pump of the type having a pump body (4) to which a multi-stage stator (3) and a multi-stage rotor (2) mounted on a shaft (1) are connected, said shaft (1) being driven by a motor and rotating in at least two ball bearings (5, 6) disposed in a sleeve (18) formed by an extension of said pump body (4), a dynamic molecular seal (7) being set on said shaft (1) at the body end of the sleeve (18), wherein the opposite end (11) of the sleeve (18) is closed, a nozzle (8) communicating with an outside source of gas being provided at said closed end (11), said pump body (4) also being connected to an exterior primary vacuum pump whereby said ball bearings (5, 6), and the rotor (9) of said motor are permanently swept by said gas entering via said nozzle and leaving via said dynamic seal, said gas flowing at a pressure intermediate between atmospheric pressure and the pump discharge pressure.The invention is used in microelectronics techniques.

Abstract: A tracer gas leakage detector mainly comprises a primary vacuum pump which is selectably connectable to a unit to be tested for leakage, an inlet valve also connectable to the unit to be tested and communicating with a measurement cell capable of being evacuated by a primary pump and a secondary pump. The inlet valve includes a motor-controlled valve member to enable the aperture through the inlet valve to be servo-controlled to the inlet pressure of the measurement cell, and conversion means providing an electrical signal representative of the aperture.

Abstract: A digital frequency receiver connected to a processor for the recognition of multifrequency code signals received in signalling time slots and transmitted to the receiver in digital form by at least one time multiplex link. The receiver includes means (MO) for modulating the received signals with signals whose frequency corresponds to a code being used and which are supplied by a digital generator, means (FPB) for low-pass filtering the modulated signals and means (CL) for analyzing the energy contained in the spectrum of the signals received in the neighborhood of the frequencies of the code. The invention is particularly adapted for use in time-switched telephone exchanges.

Abstract: A group of terminal units (GUT) for a digital exchange having distributed control residing in control means comprising microprocessor control units (UC) which are interconnected by means of the exchanges' time switching network (RXA to RXD). The control units UC are connected to each other by a duplicated point-to-point link (RIT1, RIT2) and to the switching network by a coupler (AM) which is provided with a send/receive circuit that operates using a semaphore procedure. Each of the terminal units (UT) includes a control microprocessor (mp) connected to the switching network by a send-receive circuit (ER) using a semaphore, or question and answer, procedure. The terminal units (UT) are controlled by the control units (UC) by interchanging messages using a common procedure for all the terminal units. These messages are interchanged over channels in the links that make up the switching network of the exchange.

Abstract: A security system for an exchange having distributed control. Exchange control is distributed among a plurality of microprocessors and in microprocessor terminal units connected to a time-division switching network. The security system is organized on three levels: (I) a first level comprising security means in each microprocessor for detecting faults and for taking decisions concerning current processing; (II) a second level comprising means for managing said security blocks and for switching over from one block to another and re-configuring the links affected by the switchover; and (III) a third level comprising means for managing the microprocessors of the exchange control means and the two point-to-point links, said third level means comprising two identical peripheral control units controlling respective mass memories each containing a copy of the software needed to run the exchange.

Abstract: A time division exchange controlled by a plurality of control units (UC, UCP), terminal units (UT) and markers (MQ). The control units are connected to each other and to the markers by a data interchange network (RIT) of a type which provides point-to-point serial connections. The network is duplicated and operates using a semaphore procedure. Access to the network is controlled by a duplicated controller (DR). Two-way multiplex links (LX) are provided over switched paths which could be used for voice or data switching. They are also used using a semaphore procedure and serve to provide connections between the control units and the terminal units. These connections are established via the exchange switching network. The invention is applicable to telephone switching or to data switching at subscriber or trunk level.

Abstract: A signal distribution signal for a time-division exchange has a distributed control architecture. Its switching network is organized as a plurality of independent planes (RXA to RXD) with terminal units (UT) and control units (UC) are connected via multiplex links (MX) and are synchronized by a time base (BDG) via clock signal distribution modules (MD). Each terminal or control unit is connected both to the switching network and to the clock signal distribution means by at least two independent parallel connections (F1, F2) each of which comprises multiplex links (MX) connected to different planes of the switching network, and at least one distribution link (D) connected to a different distribution module (MD) for each of said parallel connections connected to a given unit. Such exchanges are used for telecommunications purposes.

Abstract: A connector comprises a socket and a plug. The socket is located on the edge of a printed circuit card and comprises two contact tabs at different distances from the edge. A housing is placed near the tabs to receive the plug and to hold two electrically interconnected spring contact blades in contact with the tabs. If the plug is inserted one way up into the socket, its blades are connected to respective ones of the tabs, therby establishing a connection. Alternatively, if the plug is inserted the other way up, the tabs of the socket are interconnected by the first spring contact blade of the plug, thereby establishing parallel connection.

Abstract: The presence of such signals is detected each time the following detection condition is satisfied, namely: that, for the duration of a predetermined "prior activity" period the amplitude of the signal on the telephone channel exceeds a threshold level while successive maximum values taken at short time intervals remain fairly constant in level. Apparatus for performing the method comprises a threshold level comparator (10) and a difference comparator (11) which control a detector (50) followed by a holdover circuit (60). The invention is particularly applicable to inhibiting echo suppressor circuits during telephone signalling or data transfer by telephone line.

Abstract: A terminal for electrically connecting electrical conductors (6) to rigid electrical terminal pins (7) comprises a plurality of U-shaped individual contacts (2). One arm (20) of each contact (2) is connected to one of the conductors (6). The other arm (23) is flat and is adapted to connect to one of the pins (7). The terminal further comprises identical contact supports (1, 1') having an internal groove (10) with a rounded bottom. It has internal compartments (12) along the lateral walls of this groove (10) and external compartments along the lateral walls of each contact support (1, 1'). The internal compartments (12) accommodate the flat contact arms (23) and the respective pins (7). The external compartments accommodate the contact arms (20) adapted to contact the conductors (6). An insulating member (3) maintains the contact supports (1, 1') in alignment.

Abstract: In a temperature-stabilized microwave filter, each resonant cavity (5) is tuned by means of a tuning rod (10) of a thermally stable material. A first end of each tuning rod (10) extends into the respective cavity (5) without touching its surface. A second end is clamped, remotely of the cavity (5), into the filter body (1-2). At the position of this second end the filter body (1-2) has a bore (13) of substantially the same diameter as the tuning rod (10). The tuning rods (10) are clamped by pairs of retaining screws (15) accommodated in clearance holes in the filter body on one side of a longitudinal groove (21) intersecting the bore (13) and anchored into the filter body (1-2) on the other side of the groove (21).

Abstract: The box comprises a shallow bowl (1) which is hermetically sealed to a bell-shaped cover (2). Repeaters are housed in individual casings (4) which are fitted into a mother board (3) extending over the greater part of the bowl. Connector tabs (20) are provided through the mother board, with pressure contact points for making electrical contact with the individual repeater casings, and self-stripping prongs for making electrical contact with the insulated wires of a cable (8). This arrangement leads to very few connections being made in the path between a cable conductor and a repeater, and enables the box to be wired to a cable on site and without soldering.

Abstract: A cock for low-pressure bleeding of a gas from a gaseous mixture, said cock having a body (1) with an inlet (12) and a pumping outlet (13) for the mixture and a bleed outlet orifice (15), and a valve (2) which co-operates with the valve body and is situated between said orifice and the inlet, wherein the valve includes a semi-permeable membrane with a first surface (6A) which communicates with said inlet and a second surface (6) which communicates with said bleed orifice, the valve assuming a first position in which it allows the mixture to pass directly from the inlet towards the bleed orifice when the pressure of the mixture is lower than a given pressure, and a second position in which it closes the bleed orifice when the pressure of the mixture is higher than said given pressure, the gas to be bled off then passing through said permeable membrane.

Abstract: Subscribers (Ab1 to Ab8) in a telecommunications system are normally connected via respective subscriber lines (L1 to L8) to respective subscriber terminals (T1 to T8). Automatic subscriber line test means are connected via a subscriber line test bus (BL) and various relay contacts (r1 to r8 and re1 to re8) to the subscriber lines for testing purposes. Eight subscriber terminals (T1 to T8) populate a single circuit card, thereby constituting a terminal unit (TU1 to TUp). A group of terminal units is associated with a spare terminal unit (TUS). When a faulty terminal unit is detected, it is taken out of service and the spare terminal unit takes over. This is done by switching the subscriber lines connected to the faulty terminal unit over to the test bus. The spare terminal unit is likewise connected to the test bus. To enable the test means to continue testing the remainder of the telecommunications system without being interrupted by the emergency connection via the test bus, isolator means (I) are provided.

Abstract: The invention relates to a helium leakage detector. It includes a measuring spectrometric cell (8) disposed in parallel with a molecular diffusion pump (6) whose outlet (7) is short-circuited at the inlet (5) by a pipe (10) upstream from a constriction (11) constituted by an adjustable valve.

Abstract: The method relates to the detection of the training sequence of a self-adapting equalizer at the receiver end of a synchronous data-transmission system, the training sequence being preceded a synchronizing transmission of data transformed on coding into a succession of multivalent symbols such that the transmitted signal has a frequency spectrum which is substantially a single large-amplitude spectrum line. The training sequence begins with the transmission of data transformed on coding and at least one null symbol. The method consists in detecting the presence of the large-amplitude spectrum line in the signal formed by the received but not yet equalized symbols by means of a digital filter 40 and in thereafter detecting the first following major drop in absolute amplitude of the signal that lasts throughout the duration of one symbol period. This is done by means of a low amplitude level detector 50.

Abstract: An addressing circuit has a register search counter (20) connected to a first multiplexer (24) and to a second multiplexer (25), a memory (33) connected to the output of the first multiplexer for writing the type of processing of each register, a register counter (26) connected to the second multiplexer which is itself connected by its output to three address registers (28, 30, 32) in series. The output of the second register (30) is connected to the first multiplexer to write address the memory under the control of a write signal (CRW). The register search counter read addresses the memory and stops as soon as a register requiring rapid processing is detected; the second multiplexer receives a transfer signal (ST) to transmit the address applied to the output of the register search counter; the register counter (26) stops during the transfer signal.

Abstract: A multiple stylus print head, e.g. for printing a document in a facsimile system, has at least two parallel lines of styluses with the styluses being offset from one line to the next. Each line of styluses is built up from several tiers of interdigitated conductor pins (C) having tips that constitute the styluses per se. The tiers of pins are held together by respective strips of insulating material (7) forming comb-like structures which are then stacked together in such a manner that the combs fan out from the line of styluses. A plurality of groups (G.sub.1, G.sub.2) of stylus line forming comb structures are stacked together into a single stack.

Abstract: In a method of detecting the presence of speech in a telephone signal, a signal sequence is interpreted as constituting speech if its mean power level exceeds a threshold, the value of which is decreased as the number of passages through zero level in the sequence approaches 1.25 per millisecond (0.25 Hz). A speech detector implementing this method receives pulse code modulated signal samples on its input. It comprises a squaring circuit driving a digital accumulator whose output signal is proportional to the mean power level of each of consecutive 4 millisecond signal sequences. A change of sign detector and a second digital accumulator indicate the number of passages through zero level in each of these sequences. Banks of threshold comparators and a selector circuit are used to choose between the various threshold values. The selected value is lowest when the number of passages through zero level is between 5 and 6 per millisecond.