Ebauches S.a.

Roberto Zafferri

Claude Laesser

Jean Depery

Rene Besson

Ali Schneiter

Laurent Grosjean

An electromagnetic stepping motor has a stator with an armature having the shape of an isosceles trapezoid the base of which is interrupted by a central gap and which is provided with three pole faces. The rotor comprises a permanent magnet. The stator comprises two coils one of which is located between a pole face opposite said gap and one of the other two pole faces. The other coil is located between the pole face opposite said gap and the other of said other two pole faces. When a current passes through the coils, the rotor is subjected to magnetic fields having directions which are oblique to each other and which are symmetrical with respect to a diameter of the rotor. The sense of the coil currents determines the sense of the fields. The arrangement is such that one can create in the zone of the rotor a resultant magnetic field which can extend in any one of four different directions dependent on the sense of the currents passing through the coils. By appropriate commutation of the sense of each of the two coil currents, one can cause the resultant magnetic field to rotate in one direction or in the other, to drive the rotor in one or the other directional sense, but always in the same direction for a given field rotation. Thus, the rotor rotates always in the desired direction, even if a rotational step is missed or if the rotor makes one rotational step too many.

Electromagnetic motor rotatable in either direction

A resilient member for connecting a crystal to a watch casing in which the crystal is used for generating acoustic signals. The member is of generally annular configuration with an inner portion rigidly connected to the circumference of the crystal, an outer peripheral portion connected to a supporting member of the watch casing, and a free portion extending between the inner portion and the outer peripheral portion. The free portion has a width and a thickness which permits flexing in a direction normal to the plane of the crystal so that the crystal can vibrate in a direction normal to its plane and act as an acoustical transmitting member.

Watch

An electro-acoustic device for an alarm watch includes a lever moved by an oscillating electromagnetic field created by an electromagnet to vibrate a moving element or glass of the watch and produce a sound. The glass is elastically mounted on a sealing ring of the watch. The lever is mounted by one end to the watch and includes a tapered part adjacent the one end which is elastically deformable thereat so that a free end of the lever opposite the one end may vibrate and its fundamental frequency in response to the oscillating electromagnetic field. The free end of the lever carries a stem coupling the lever to the glass and transmitting the oscillating motion of the lever to the glass, which vibrates on the elastic ring to produce the sound.

Growing community of inventors

Lugano, Switzerland

Roberto Zafferri