| To provide a system and method for determining parameters relating to an angular movement of an arbor.SOLUTION: A system 6 is configured to determine an angular movement of an arbor integral with a crown of a watch, the arbor being rotatable on itself in a longitudinal direction. The system includes a rotating reflector 8 mounted on the arbor, and two emitter/detector pairs 10A, 10B disposed on either side of the reflector. Each of the emitter/detector pairs includes a light source 16 for illuminating the reflector, and a light detector 18 for receiving light 24 reflected on the reflector and for generating an electrical signal representative of the reflected light. The system further includes a processor, which processes the electrical signal generated by the detector and determines a parameter relating to the angular movement of the arbor. The rotating reflector is in the form of a cylinder of revolution, and light absorption point configuration is made on the circumference of an external cylindrical surface. When the reflector rotates on itself in a regular manner and in the same direction S1, S2 of rotation, the representative electrical signal generated by each detector of each pair has a substantially sinusoidal shape.SELECTED DRAWING: Figure 3 |
