Abstract: The described cell comprises a mixture of liquid crystals (26), polarizers (28, 30) and alignment layers (22,24). The liquid crystals mixture includes a chiralic compound which induces a helical structure having a pitch greater than or equal to the thickness of the liquid crystal layer. One alignment layer (24) induces a planar alignment, the other (22) induces a hemeotropic alignment. This cell, of low cost, requires low control voltage and provides a very good contrast and a high multiplexing rate. It may be used to advantage in the manufacture of dots matrix display watches.

Abstract: In a reflector-diffuser type liquid crystal display cell, the control electrodes, which are transparent, electronic components and tracks connecting the components to the cell terminals are disposed between the cell front plate and the liquid crystal layer. The counter electrode is disposed on the other side of the liquid crystal layer and has a frosted rough light reflecting and diffusing face over its entire surface situated in the display area and thus itself functions as the cell reflector-diffuser.

Abstract: A barrel spring winding device comprises a solar cell (3) arranged to receive ambient light, a capacitor (4) connected to the terminals of the cell, a stepping motor (6) and a control circuit (5). The input of the circuit is connected to the terminals of the capacitor and its output to the terminals of the motor. The rotor of the motor is operatively connected to wind a barrel spring, for example of a watch. The cell (3) charges the capacitor (4) and when the voltage thereof, measured by a differential amplifier (23), reaches a reference voltage (V.sub.r), the capacitor is connected to the terminals of the motor by a switching transistor (27). Discharge of the capacitor supplies to the motor a drive pulse whose duration is determined by a one-shot flip-flop (25). After the pulse, the capacitor is once again charged by the cell. To prevent the motor from receiving a drive pulse before it has stopped, i.e.

Abstract: A laser includes a discharge tube formed from one piece and penetrating, with play, into an anode chamber on one side and into a cathode chamber on the other side, the anode and cathode chambers having a thermal expansion coefficient different from that of the discharge tube. Bellows are hermetically welded by their first ends to the anode and sealed by a glass bead to the discharge tube at their second ends.

Abstract: A composite material comprising an open pore rigid foam of ceramic, metal, carbon or a plastics material and a solid filler material disposed in the cavities of the foam. The solid filler material forms areas on the surface of the composite material defined by the walls of the cavities in the foam. Depending on the material of the foam, the material filling its cavities may be a metal or a plastics material. The composite material, the production of which is also described, has aesthetic qualities which render it particularly suitable for the production of decorative articles.

Abstract: The method of this invention includes measuring the quantity Eme of electrical energy converted into mechanical energy by the motor during a driving pulse, determining the time required for said quantity of energy to attain a reference value E.sub.ref and interrupting the driving pulse as a function of such time.The arrangement includes means for measuring said quantity Eme of energy, means for determining the time required for such quantity of energy to attain such reference value E.sub.ref and means for effecting interruption of the driving pulse as a function of such time.

Abstract: The method and the device described are intended to avoid the dissipation of electrical energy that occurs in the coil of a stepping motor when the coil is short-circuited permanently between two drive pulses. The method comprises short-circuiting the coil at the end (t1) of the drive pulse, then putting it on open circuit at the instant (t2) when the current (Ic) flowing through it during the short-circuit becomes zero, and short-circuiting the coil again at the instant (t3) when the voltage induced in it by the rotation of the rotor while the coil is on open circuit becomes zero or reaches a predetermined value (Ud). The device is designed to carry out the method. The invention is applicable to the control of stepping motors of the type for instance that are fitted in electronic timepieces having a hand display.

Abstract: The gas laser of this invention includes a discharge tube formed from a plurality of metallic bodies arranged in end to end alignment. The tube is terminated by a cathode chamber at one end and an anode chamber at the other end. Each of the metallic bodies and the cathode and anode chambers is provided at least with one tubular element said elements being joined together by means of a glass welding bead. The material forming said tubular elements has the same coefficient of thermal expansion as glass. The invention finds particular application to completely sealed lasers.

Abstract: The article is provided with a coating resisting wear and corrosion, such coating being for the most part made of a precious metal or alloy of a precious metal, for example gold or an alloy containing gold.The coating is made up of a first layer of such precious metal or alloy thereof comprising discrete inclusions of a metallic compound such as titanium nitride. These inclusions are deposited along with the precious metal in vapor phase and distributed in a substantially homogeneous manner through the entire thickness of the layer, said thickness being equal to or greater than 0.4 .mu.m. A second layer of precious metal or alloy thereof is located between the article and said first layer.The article may be a watch case, a bracelet link or a piece of jewelry.

Abstract: A force sensor comprising a resonator (10) having a frequency that varies with the force being measured. The resonator includes an oscillatory bar (101, 102) and a pair of anchor members (12, 103, 104) that are connected each to a corresponding end portion of the bar and which are adapted to apply the force having to be measured to the bar. The sensor further comprises a tube (16) that surrounds the resonator and which is rigidly secured by its end portions to the anchor members (12).

Abstract: In a gas laser including a discharge tube forming a resonant cavity, a mirror disposed at each end of the cavity, a pump, a gas source and a manometer, a first valve is connected between one end of the tube and a first of the mirrors and a second valve is connected between the other end of the tube and a second of the mirrors. Within the body of each valve is a moving element which may assume a first working position, a second position permitting mirror access and a third position for changing gas. This arrangement permits changing mirrors and/or replacing gas without exposing the cavity to atmospheric pressure and without loss of time.

Abstract: The method according to the invention is applicable to motors comprising a magnetized rotor having two diametrically opposed poles, a stator making up a magnetic circuit having saturable constricted portions and a coil coupled magnetically to the stator. The method consists in applying to the coil an electric pulse, in measuring a control current (I'.sub.01, I'.sub.02) generated within the coil by the electric pulse at the end of a control time interval (t'.sub.o -t.sub.i) and in comparing the control current with a reference current (I.sub.r), the sign of this comparison being representative of the position of the rotor. In order to take into account the variations in the characteristics of the motor with time, the control time interval (t'.sub.o -t'.sub.i) is readjusted periodically by means of first and second electric pulses of a learning signal applied to the coil. The first pulse of this signal generates within the coil a first current (I.sub.1) which reaches the reference current (I.sub.

Abstract: A pager is described for use in an electronic watch. The pager comprises a frame (1) for picking up a magnetic signal and a piezoelectric transducer (11) having a static capacitance on its terminals, for producing a sound. 11To improve sensitivity of reception, a switching circuit (15) connects the transducer (11) in parallel with the frame (1) to tune it by means of the static capacitance to the frequency of the magnetic signal carrier wave. To increase the performance of the transducer (11 ) when it operates as a sound transmitter, the switching circuit (15) connects the frame (1) in series with the transducer (11).

Abstract: This transponder includes a dielectric support, an antenna and a covering layer. The central portion of the antenna forms a self induction loop which, together with the junction capacity of a non-linear component serving to close the loop, provides a circuit resonating at the frequency at which the transponder receives its energy. The antenna radiates energy at double this frequency which energy may be detected by a receiver.

Abstract: A piezoelectric oscillator is described comprising a piezoelectric element, e.g. a tuning fork (10), and a casing (20) formed by a pair of glass plates (22,24). The inner surfaces of the plates have recesses (26,27) that define a housing (28) in which the tuning fork (10) is located, and a pedestal (22a) to which the tuning fork (10) is secured. The inner surface of one of the plates (22) carries a conductive track (30), in the region of the pedestal (22a). This plate (22) is also formed with a hole (44) opening onto the conductive track (30) which seals it off.

Abstract: Some at least of the control signals usually produced by manual control members and applied to the control circuit of the watch to control the performance of the different functions thereof are produced directly from words pronounced by the user, belonging to a pre-determined vocabulary, by an assembly for producing control signals by means of speech, which comprises electro-acoustic means for converting a pronounced word into an analog signal representing that word, means for transforming the analog signal into an item of logic control information and means for transforming the logic information into a control signal which can be directly applied to a control circuit for controlling performance of the function corresponding to the word pronounced.

Abstract: The timepiece comprises an oscillator (1), a frequency divider (2), a control circuit (3), a stepping motor (4), a seconds hand (5), a circuit (7) for detecting steps missed by the motor, an up-down counter (15) having a capacity N, and a flip-flop (16). At each missed step the detecting circuit (7) generates a tally pulse (S.sub.7) which increments the counter (15). The latter is also decremented by periodic pulses appearing on the B output of the frequency divider (2).When a cell supplying the timepiece is nearly exhausted, the number of steps missed per unit of time is high and the counter (15) is, on balance, incremented. When passing from state N-1 to state N the counter issues on its Q.sub.h output a pulse that causes the Q output of the flip-flop (16) to go high. The control circuit (3) produces, in response to this high state of the flip-flop, a signal warning of the imminent end of the cell's life in the form of an irregular motion of the seconds hand (5).

Abstract: The control circuit comprises means for measuring current flow in the motor winding including an auxiliary transistor and means to form periodically a current mirror from such auxiliary transistor and one of the transistors coupled to the winding for applying thereto energization pulses, i.e. motor drive pulses, catch-up pulses or check pulses.

Abstract: A resonator (1) is described for vibrating in a thickness-shear mode and has auxiliary electrodes (7f, 8d) between the zone of its main excitation electrodes (3, 4) and the zone of its connection terminals (5, 6) to generate an auxiliary vibration in opposition of phase with respect to the main vibration.The presence of the auxiliary electrodes (7f, 8d) improves notably the quality factor of the resonator.

Abstract: The micro-resonator comprises, cut from the same quartz crystal, a bar and a suspension frame means. The bar is cut in a substantially Z cut mode. The excitation electrodes are disposed on the sides of the bar. The length of the bar is substantially parallel to the Y axis.This produces a resonator which vibrates in a main mode of extension-compression, at from 0.5 MHz to 4 MHz.