System and method for determining at least one parameter relating to an angular movement of an arbor comprising a rotating reflector with contigous oblique chamfers

Patent metadata

Field	Value
Publication number	US-11029648-B2
Application number	US-201916680988-A
Country	US
Kind code	B2
Filing date	Nov 12, 2019
Priority date	Dec 21, 2018
Publication date	Jun 8, 2021
Grant date	Jun 8, 2021

Abstract

A system and method to determine an angular movement of an arbor integral with a crown of a watch, the arbor being rotatable in a longitudinal direction. Included is a rotating reflector mounted on the arbor, and two emitter/detector pairs disposed on either side of the reflector. Each emitter/detector pair includes a light source for illuminating the reflector, and a light detector for receiving the light reflected on the reflector and for generating an electrical signal representative of the reflected light. A processor processes the electrical signals and determine a parameter relating to the angular movement of the arbor. The rotating reflector's visible outer surface changes when the reflector rotates on itself in a regular manner, such that the representative electrical signal generated by said detector of the pair has a substantially sinusoidal shape when the reflector rotates on itself in a regular manner in a same direction of rotation.

First claim

The invention claimed is:

1. A system ( 6 ) for determining at least one parameter relating to an angular movement of an arbor ( 4 ), particularly a stem ( 4 ) integral with a timepiece ( 1 ) crown ( 2 ), the system ( 6 ) comprising:
an arbor ( 4 ) configured to be able to rotate on itself around a longitudinal direction (D 1 );
a rotating reflector ( 8 ) mounted on the arbor ( 4 ), around said arbor ( 4 )
two emitter/detector pairs ( 10 A, 10 B), the two pairs ( 10 A, 10 B) being disposed on either side of the rotating reflector ( 8 ), facing the reflector ( 8 ), each emitter/detector pair ( 10 A, 10 B) comprising a light source ( 16 ) intended to illuminate one part of the reflector ( 8 ), and a light detector ( 18 ) intended to receive a reflected light beam ( 24 ) from the reflector ( 8 ) and to generate an electrical signal ( 26 A, 26 B) representative of said beam ( 24 ); and
a processor configured to process each of the electrical signals generated by the detectors ( 18 ), and to determine, as a function of the processing result, said at least one parameter relating to the angular movement of the arbor ( 4 );
characterized in that the rotating reflector ( 8 ) is formed from a cylinder of revolution, on the edges of which are arranged several contiguous, oblique chamfers ( 14 ), the outer surface ( 12 ) of the non-chamfered part of the reflector ( 8 ) seen from each emitter/detector pair ( 10 A, 10 B) forming an active reflective portion of the reflector ( 8 ) for said pair, which changes when the reflector ( 8 ) rotates on itself, such that the representative electrical signal ( 26 A, 26 B) generated by said detector ( 18 ) of the pair ( 10 A, 10 B) has a substantially sinusoidal shape when the reflector ( 8 ) rotates on itself in a regular manner in a same direction of rotation (S 1 , S 2 ).

2. The system ( 6 ) according to claim 1 , characterized in that the two emitter/detector pairs ( 10 A, 10 B) are arranged with respect to the rotating reflector ( 8 ) such that the two emitters ( 16 ), respectively the two detectors ( 18 ), are arranged head-to-tail with respect to each other.

3. The system ( 6 ) according to claim 1 , characterized in that the two emitter/detector pairs ( 10 A, 10 B) are disposed on either side of the rotating reflector ( 8 ), on a circle whose centre is substantially the centre ( 22 ) of the rotating reflector ( 8 ), and are offset from each other by an angle having a value other than 180°.

4. The system ( 6 ) according to claim 3 , characterized in that the two emitter/detector pairs ( 10 A, 10 B) and the rotating reflector ( 8 ) are arranged to define a substantially Y-shaped spatial arrangement, the rotating reflector ( 8 ) being disposed at the centre of the Y, a first emitter/detector pair ( 10 A) being disposed at the free end of a short arm of the Y, and the other emitter/detector pair ( 10 B) being disposed at the free end of the long arm of the Y.

5. The system ( 6 ) according to claim 1 , characterized in that, in each emitter/detector pair ( 10 A, 10 B), the emitter ( 16 ) and the detector ( 18 ) are optically isolated from each other.

6. The system ( 6 ) according to claim 1 , characterized in that each oblique chamfer ( 14 ) defines an angle substantially equal to 50° with a plane tangent to the outer surface ( 12 ) of the non-chamfered part of the reflector ( 8 ) and parallel to the longitudinal direction (D 1 ).

7. The system ( 6 ) according to claim 5 , characterized in that the rotating reflector ( 8 ) is made of metal, the outer surface ( 12 ) of the non-chamfered part of the metal reflector being polished.

8. A timepiece ( 1 ) comprising a system ( 6 ) for determining at least one parameter relating to an angular movement of an arbor ( 4 ), characterized in that the determination system ( 6 ) conforms to claim 1 .

9. The timepiece ( 1 ) according to claim 8 , characterized in that the timepiece ( 1 ) is a quartz watch provided with a time-setting crown ( 2 ), said arbor ( 4 ) being the stem ( 4 ) integral with the crown ( 2 ).

10. A method for determining at least one parameter relating to the angular movement of an arbor ( 4 ), particularly a stem ( 4 ) integral with a crown ( 2 ) of a timepiece ( 1 ), by means of a determination system ( 6 ) according to claim 1 , the method comprising the following steps, implemented by the processor:
receiving ( 32 ) two electrical signals ( 26 A, 26 B) from two light detectors ( 18 ), each of the electrical signals ( 26 A, 26 B) being representative of a reflected light beam ( 24 ) from the reflector ( 8 ), each of the electrical signals ( 26 A, 26 B) having a substantially sinusoidal shape;
determining ( 34 ) the frequency of each of the two received electrical signals ( 26 A, 26 B);
determining ( 36 ), by comparison between the frequency determined by the processor and a correspondence table pre-stored in memory means of the system ( 6 ), the speed of rotation of the arbor ( 4 ).

11. The method according to claim 10 , characterized in that the method further includes a step ( 38 ), implemented by the processor, consisting in representing the two received electrical signals ( 26 A, 26 B) as the sine and cosine of the same function and calculating an arctangent function ( 39 ) whose variable is the ratio between the two signals.

12. The method according to claim 11 , characterized in that the method further includes a step ( 40 ), implemented by the processor, consisting in determining, according to the sign of the slope of the calculated arctangent function ( 39 ), the direction of rotation of the arbor ( 4 ).

13. The method according to claim 10 , characterized in that the method further includes a step ( 30 ), implemented by the processor, consisting in alternately controlling the illumination of each of the light sources ( 16 ).

14. A non-transitory computer readable medium comprising program instructions stored in memory means and which, when executed by the system ( 6 ) processor, are able to implement the method according to claim 10 , for the determination of at least one parameter relating to an angular movement of an arbor ( 4 ).

Assignees

• Swatch Group Res & Dev Ltd

Inventors

• Tortora Pierpasquale
• Zanesco Vittorio

Classifications

• G04C3/001 Primary

  Electromechanical switches for setting or display · CPC title

• G04D7/002 Primary

  Electrical measuring and testing apparatus · CPC title

• G04D7/12

  Timing devices for clocks or watches for comparing the rate of the oscillating member with a standard {(supporting devices for clocks with built-in recording apparatus G04D1/063; measuring short time intervals G04F10/00; frequency measuring in general H04B, G01R)} · CPC title

• G01D5/3473

  Circular or rotary encoders · CPC title

• G04B9/005 Primary

  by optical indication of the amount of winding · CPC title