US2907940A

US2907940A - Timepiece comprising an electromagnetically maintained oscillating regulator

Info

Publication number: US2907940A
Application number: US719437A
Authority: US
Inventors: Beyner Andre
Original assignee: Ebauches SA
Current assignee: Ebauches SA
Priority date: 1957-03-09
Filing date: 1958-03-05
Publication date: 1959-10-06
Anticipated expiration: 1976-10-06

Description

Oct. 6, 1959 A. BEYNER 2,907,940

TIMEPIECE COMPRISING AN ELECTROMAGNETICALLY MAINTAINED OSCILLATING REGULATOR Filed March 5, L958 l jQ Y A A TTORNE) United States Patent TIMEPIECE COMPRISINGAN ELECTROMAGNET- ICALLY MAINTAINED OSCILLATING REGU- LATOR Andr Beyner, Neucllatel, Switzerland, assignor to Ebauches S.A., Neuchatel, Switzerland 7 The present invention relates to a timepiece comprising an electromagnetically maintained oscillating regulator, of the type in which the movement of the regulator produces'by induction, in a pick-up winding, an impulse signal controlling the feed of a driving winding.

In timepieces of this type, the pick-up and driving windings are generally fixed, their respective magnetic fields being movable and generally being produced by magnets mounted on the oscillating regulator. These magnetic fields are inevitably weak, so that the signal produced in the pick-up winding is also weak.

The object of the present invention is mainly to obviate this disadvantage. v

The timepiece according to the invention is characterised by the fact that it comprises a single, fixed magnetic field, of which the flux crosses the trajectory of the regulator and in which the pick-up winding, which is also fixed, is situated, the regulator supporting both the driving winding and a magnetic screen adapted to sweep the magnetic field in" such manner that, as the said screen passes, the; magnetic flux in which the pick-up winding is situated varies, thus producing the impulse current which controls the feed 'of the driving winding, the latter then ifalso being situated in the magnetic field. The accompanying drawings, in which only the parts necessary for anunde'rstanding of the, invention are,

shown, illustrate by way of example one constructional formof the subject of the invention.

Figure. 1 is a sectional view of a part of a timepiece, taken through the axis of the balance wheel.

Figure 2 is a plan view thereof.

Figure 3 is a diagram of the variations of the magnetic flux and of the voltage induced in the pick-up winding, as a function of time, and,

Figure 4 is a skeleton diagram of the electric circuit of'the timepiece. a

The illustrated timepiece comprises a balance wheel 1,

of which the staff 2 is pivotally mounted between the bot tom plate 3 on the one hand and the balance cock 4 on the other hand. Mounted on the stafi 2 is a disc 5 controlling a pallet 6 intended to convert the oscillatory movements of the balance wheel 1 into a discontinuous rotary movement of a moving member (not shown) connected to the hands. The balance spring is designated by 7, its lower end being fixed to a collet 8 electrically insulated from the staif 2 of the balance wheel by a sleeve 9 of, for example, polytetrafluorethylene (material commercially known under the name Teflon).

The oscillations of the balance wheel 1 are electromagnetically maintained by the following device:

A fixed magnetic field is produced by a first magnet 10,

in the form of a stud, the axis and the magnetisation of which are parallel to the staif 2, which is situated below the balance wheel, and by a second magnet 11, in the form of a stud, the axis and magnetisation of which are also parallel to the staff 2. The said two magnets are connected by an iron plate 12. The magnet 11 supports in addition a second iron plate designated by 13, the

\ 2,907,940 Patented Oct. 6, 1959 free end of which is situated above the magnet 10. The lines of force of the magnetic field thus intersect the trajectory of the balance wheel 1 perpendicularly to the plane of the latter. The two,

magnets

10 and 11 are advantageously constructed of materials having high- The balance wheel 1 supports a driving winding-16 which is so disposed as to lie exactly below the pickup winding 14 when the balance wheel occupies its position of equilibrium. The said driving winding 16 is provided with a central core 17, which is extended by a screen 1711, also of soft ferrite. The feed circuit of the winding 16 extends through the balance spring 7, which is electrically insulated from the frame of the clock-work by the sleeve 9 and by the stud (not shown) for securing its outer end, which stud also consists of an insulating material, or is mounted on the balance cock through an insulating member. The feed circuit of the winding 16 extends on the other hand through the frame of the movement; For this purpose, one of the ends of the winding 16 is connected at 18to the balance wheel 1 and the latter is electrically connected to the bottom plate 3 by an additional hair spring 19 secured to a stud 20. The said additional hair spring is so fine as to produce no additional torque, especially on the balance wheel.

The driving winding 16 is connected on the one hand to the collector of a transistor 21 and on the other hand to the negative terminal of a current source 22, for example a 1.3-volt battery (Figure 4). terminal of the said current source 22 is in turn connected to the emitter of the transistor 21. Finally, the pick-up long as the screen 17a is not situated in the said field.

As soon as the screen enters the magnetic field, it deflects it through the air gap 23 by reason of the fact that its reluctance is substantially lower than that of the air gap 24. The magnetic field in which the pick-up winding is situated thus varies at the passage of the screen 17a in ac cordance with the curve 25 of Figure 3, in which the position of equilibrium of the balance wheel is indicated by an axis 26. This variation of the flux produces a voltage in the winding 14 by induction, in accordance with the law represented by the curve 27 of Figure 3. This signal applied between the base and the emitter of the transistor 21 renders the latter conductive, so that the driving winding 16 is then fed by the source 22. In the illustrated constructional form, the arrangement is such that when the screen enters the magnetic field, with the balance wheel then approaching its position of equilibrium, the impulses produced in the pick-up winding 14 have no effect. The core 17 and the screen 17a are then attracted by the magnetic field, which supplies to the balance wheel the energy necessary for its maintenance. On the other The positive hand, when the balance wheel moves away from its position of equilibrium, with the screen 17a then leaving the magnetic field, the current from the source 22 flows through the, winding .16, whereby the eifect of themagnetic field is neutralised and the braking which would be produced by the attraction of the latter is thus eliminated. This process is symmetrical and therefore takes place regardless of the direction of movement of the, balance wheel,

The arrangement described and illustrated has the advantage of permitting the use of relatively long mag nets.the magnet 11 is of substantially the same height as the movement-the cross-section of which may be very freely dimensioned. It is thus possible to concentrate, a considerable magnetic field in the air gap. The signal produced, in the pick-up winding is thus improved, as also is the operation of the timepiece, and more especially its insensitivity to temperature variations. 7

The invention is not limited to the constructional form illustrated and described. Thus, the magnetic field may b produced by a single magnet instead of two, while driving winding may be disposed at one of the ends of the arm of the balance wheel instead of being situated at the, end of a diameter perpendicular to this arm, as in the present constructional form. It is to be noted that the part of the balance wheel which is situated opposite the. driving winding and which is not shown in the drawings will preferably be thickened to form a counterbalance weightt f Finally, the additional hair spring 19, instead of producing a very low torque, may have the same characteristics as the balance spring 7, so that its action will be added to that of the latter,,the said two springs preferably being coiled in opposite directions.

What I claim is:

In a timepiece comprising an'electromagnetically maintained oscillating regulator, of the type in which the movement of the regulator produces by induction, in a pick-up winding, an impulse signal controlling the feed of a driving winding, in such a timepiece, a single, fixed magnetic field, of which the flux crosses the trajectory of the said regulator and in which the pick-up winding, which is also fixed, is situated, and a magnetic screen se= cured tothe said regulator and adapted to sweep the mag neticfield in such manner that, as the said screen passes, the magnetic flux in which the pick-up winding is situated varies, thus producing the impulse current, which controls. the feed of the driving winding, secured to the said regulator, said driving winding being then also situated in the. magnetic field. V

2. In a timepiece comprising an electromagnetically maintained oscillating regulator, of the type in which the movement of the regulator produces by induction, in a pick-up winding, an impulse signal controlling the feed of a driving winding, in such a timepiece, a single, fixed magnetic field, of which the flux crosses the trajectory of the said regulator and in which the pick-up, winding,

which is also fixed, is situated, a core for the said driving winding, which is secured to the said regulator, and a magnetic screen secured to the said regulator too and adapted to sweep the mganetic field in such manner that, as the said screen passes, the magnetic flux in which the pick-up winding is situated varies, thus producing the impulse current which controls the feed of the driving winding, the latter being then also situated in the mag netic field.

3. Timepiece as claimed in claim 2, in which, the said screen and the said coreof the driving winding are made in one piece of a material having high magnetic permeability. g

4. In a timepiece comprising an electromagnetically maintained oscillating regulator, of the type in which the movement of the regulator; produces by induction, in a pick-up winding, an impulse signal controlling the feed of a driving winding, in such a timepiece, at least one fixed magnet in the form of a 'stud, the axis and the magnetisation of which are parallel to the axis of oscillation of the regulator, producing a magnetic fieldv of which the flux crosses the trajectory of the said regulator and in which the pick-up winding, which is also fixed, is situated, and a magnetic screen secured to the said regulator and adapted to sweep the magnetic field in such manner-that, as the said screen passes, the magnetic flux in which the pick-up windingis situated varies, thus producing the impulse current which controls the feed of of the work, an iron member connecting said magnets,

one of them being situated at a right angle to the trajectory of the regulator, a second iron member secured to,

the other magnet and extending to a point above the first one, producing thus an air gap, the arrangement being such that the regulator is traversed by the magnetic flux when it enters the said air gap, and amagnetic screen secured to the said regulator and adapted to sweep the magnetic field in such manner that, as the said screen passes, the magnetic flux, in which the pick-up winding is situated, varies, thus producing the impulse current which controls the feed of the driving winding, secured to the said regulator, said driving winding being then also situated in the magnetic field.

6'. In a timepiece as claimed in claim 5, the feature that the pick-up winding is fixed to the end of the second iron member, above the first magnet.

No references cited.