Asulab S.a.

Roland Luthier

Francis Levy

Alain Mocellin

Fridolin Wiget

Raymond Froidevaux

Minoru Kurosawa

The invention concerns a method for exciting and monitoring a piezoelectric motor (M1) in stepping mode, the motor having a resonance frequency (f.sub.R) and being supplied electrically at an excitation frequency (f.sub.E) during each operating step. The method is characterized in that it comprises a monitoring phase which extends at least over several successive steps of said motor and in which, for a present step of said motor, a determined excitation frequency value (f.sub.E +1) is used, the duration (t.sub.E +1) of the present step is measured, said duration (t.sub.E +1) is compared to the duration (t.sub.E) of the preceding step and, according to the result of this comparison, said excitation frequency value (f.sub.E +2) is corrected for the following step in a direction tending to reduce the duration of the step. A circuit is also described which enables the implementation of the method.

Method and circuit for exciting and monitoring a piezoelectric motor in

A piezo-electric motor of the stationary wave tape comprises a stator including piezo-electric excitation means capable of inducing a vibratory motion in the stator, a rotor mounted for rotation relative to the stator, the rotor including a body on which are assembled flexion tabs forming transmission means arranged to transmit the vibratory motion of the stator to the rotor and to rotationally drive such rotor, said flexion tabs following a displacement path relative to the stator, and an angular position detector of the rotor. The motor is characterised in that the detector is arranged near and in line with the displacement path, and in that said detector is formed by one or several piezo-electric sensors allowing to track the passage of the tabs. The motor is particularly suitable for timepieces.

Position detector of the rotor of a piezo-electric motor

A piezoelectric motor. Such motor includes a support (2), a stator (S2, S3) fixed to the support (2), piezoelectric means (10) adapted to be electrically excited so as to induce a vibratory motion in the stator (S2, S3), a rotor (R2, R3) mounted for rotation relative to the support (2), such rotor including a body on which transmission means (36) are arranged and adapted to transmit the vibratory motion of the stator (S2, S3) to the rotor (R2, R3) and in order to drive such rotor in rotation, and elastic support means (79) for the rotor on the stator, characterized in that the body of the rotor is formed by a structure (D2, D3) which is elastically deformable, at least in the direction of the stator, and which at least in part forms the support means (79). The invention is applied, for example, to a timepiece.

Piezoelectric motor

A timepiece comprising a display (2) such as a data display and a driving motor (M1, M2) for driving the display is characterized in that the driving motor comprises a piezo-electric motor directly engaging the display.

Timepiece provided with driving means formed by a piezo-electric motor

The instant invention relates to a piezo-electric motor. The motor comprises:

Piezo-electric motor

A cathodic sputtering operation using a target of a material containing titanium, aluminium, oxygen and nitrogen in an argon atmosphere is disclosed. This sputtering operation gives rise to a layer containing the same elements as the target. The resulting layer is opague, has an attractive, deep and brilliant black color, adheres well to the substrate and is resistant to wear and corrosion. The physical structure of the layer is characterized by a transparent and insulating amorphous phase in which are dispersed a plurality of inclusions having a size on the order of nanometers.

Black-colored coating deposited on a substrate

A cathodic sputtering operation using a target of a material containing titanium, aluminum, oxygen and nitrogen in an argon atmosphere is disclosed. This sputtering operation gives rise to a layer containing the same elements as the target. The resulting layer is opaque, has an attractive, deep and brilliant black color, adheres well to the substrate and is resistant to wear and corrosion.

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St-Sulpice, Switzerland

Roland Luthier