Abstract: This method consists in supplying at least a first alternating signal, at a determined frequency, to one end of a stator coil and recuperating a measurement signal at a second end of said coil, said measurement signal being provided to electronic processing means, which are arranged to extract data relating to a periodic variation of the effective inductance of the stator coil. This variation is a function of the angular position of the rotor. By alternately carrying out such a measurement on the stator coils, three periodic curves can be extracted (SPCA, SPCB, SPCC) defining a zigzag curve (70) allowing the angular position of the rotor to be determined.

Abstract: In order to detect the angular position of a permanent magnet rotor (13) of a brushless motor, measuring means are connected to the windings of the stator in such a way as to form an oscillatory circuit and the variations in the frequency of resonance as a function of the position of rotor are measured. In order to augment these variations, the rotor has a non-magnetic structure (26) around the magnet (14) with zones of different thicknesses or of different permeabilities. This structure can be formed by a metal sleeve, of brass for example, having openings or recesses (44) which can be filled with a dielectric material.

Abstract: The present invention concerns a device (20) for controlling an electric motor (1) including a rotor (6) and at least three stator coils (2, 3, 4) connected between three connection terminals, means (5) for providing three control signals (Ua, Ub, Uc) to said connection terminals, and means (22) for dectecting said rotor angular postion. Said dectecting means include measuring means (24) designed to be connected to the motor, such that the means form with said coils at least two oscillating circuits supplying two respective signals (U1, U2) at two measurement frequencies respectively which are themselves periodic functions of said rotor angular position, and means (26) for calculating a single value corresponding to the two measurement frequencies, this value being the desired angular position.

Abstract: In order to allow a dental instrument such as an air turbine or an electric motor hand piece to be quickly connected or disconnected to a supply unit, a revolving connecting unit is provided with a fixed portion (4), provided with channels (13 to 16) for fluids and electric contact rings (26) at the front, a coupling sleeve (32) freely rotating on the fixed portion, an a stop ring inserted between said sleeve and the fixed portion and rotating freely thereon. The coupling sleeve (32) is secured to the back of the instrument by a bayonet device (38). This sleeve extends far enough forwards to prevent accidental contact between the electric contact rings (26) and an external object when the connecting unit is not connected to an instrument.

Abstract: The invention concerns a multi-purpose revolving connecting assembly intended to connect dental instruments (1a, 1b) having rear portions (22) of different geometrical configurations to a supply source (S).This connecting assembly is characterized in that it includes a nut (16) formed, at the front, of a removable sleeve (50a, 50b) and, at the rear, of a bush (52) which can be connected to the sleeve (50a, 50b) by a screw-nut system, the sleeve (50a, 50b) being provided to be fixed onto the dental instrument (1a, 1b), while the socket (52) has a support surface (58b) intended to abut against the ring (4) axially holding a mobile coupling piece (28a, 28b) on a fixed coupling piece (26).

Abstract: A dental scaler comprises a hollow sleeve and, arranged inside it, a vibrating piezoelectric transducer bearing a scraper, the extremity of which protrudes from the sleeve, and includes an amplifier connected to the transducerk. The transducer includes a base, of a series of piezoelectric chips on the surfaces of which are arranged electrodes connected in such a manner as to define an input and an output, and a head to which the scraper is coupled. The amplifier has an input, an output and two feeder terminals receiving a low direct voltage by way of a cable connected to an external source of voltage. The output and input of the transducer are connected, respectively, to the input and the output of the amplifier to form an oscillator, the frequency of which is determined by the resonant frequency of the transducer coupled to the scraper.