# US 11,029,648 B2 · 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 > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,029,648 B2 - Document ID: US11029648B2 - Status: Granted - Kind: B2 - Application number: 16/680,988 - Filed: 2019-11-12 - Published: 2020-06-25 - Granted: 2021-06-08 - Earliest claimed: 2018-12-21 - Assignees: The Swatch Group Research and Development Ltd - Applicants: The Swatch Group Research and Development Ltd - Inventors: Pierpasquale Tortora; Vittorio Zanesco - Web page: https://patentgrep.com/patent/US11029648B2 ## CPC - G04B 9/005: {by optical indication of the amount of winding} - G04C 3/001: {Electromechanical switches for setting or display} - G01D 5/3473: {Circular or rotary encoders} - G01P 3/36: Devices characterised by the use of optical means, e.g. using infrared, visible, or ultraviolet light (G01P3/68 takes precedence; gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams G01C19/64) - G04B: MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS (spring- or weight-driven mechanisms in general F03G; electromechanical clocks or watches G04C; electromechanical clocks with attached or built-in means operating any device at pre-selected times or after predetermined time intervals G04C23/00; clocks or watches with stop devices G04F7/08) - G04C: ELECTROMECHANICAL CLOCKS OR WATCHES - G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR - G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G}) ## 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. ## Claims ### Claim 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 (D1); a rotating reflector (8) mounted on the arbor (4), around said arbor (4) two emitter/detector pairs (10A, 10B), the two pairs (10A, 10B) being disposed on either side of the rotating reflector (8), facing the reflector (8), each emitter/detector pair (10A, 10B) 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 (26A, 26B) 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 (10A, 10B) 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 (26A, 26B) generated by said detector (18) of the pair (10A, 10B) has a substantially sinusoidal shape when the reflector (8) rotates on itself in a regular manner in a same direction of rotation (S1, S2). ### Claim 2 (depends on 1) The system (6) according to claim 1, characterized in that the two emitter/detector pairs (10A, 10B) 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. ### Claim 3 (depends on 1) The system (6) according to claim 1, characterized in that the two emitter/detector pairs (10A, 10B) 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°. ### Claim 4 (depends on 3) The system (6) according to claim 3, characterized in that the two emitter/detector pairs (10A, 10B) 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 (10A) being disposed at the free end of a short arm of the Y, and the other emitter/detector pair (10B) being disposed at the free end of the long arm of the Y. ### Claim 5 (depends on 1) The system (6) according to claim 1, characterized in that, in each emitter/detector pair (10A, 10B), the emitter (16) and the detector (18) are optically isolated from each other. ### Claim 6 (depends on 1) 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 (D1). ### Claim 7 (depends on 5) 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. ### Claim 8 (depends on 1) 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. ### Claim 9 (depends on 8) 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). ### Claim 10 (depends on 1) 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 (26A, 26B) from two light detectors (18), each of the electrical signals (26A, 26B) being representative of a reflected light beam (24) from the reflector (8), each of the electrical signals (26A, 26B) having a substantially sinusoidal shape; determining (34) the frequency of each of the two received electrical signals (26A, 26B); 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). ### Claim 11 (depends on 10) 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 (26A, 26B) as the sine and cosine of the same function and calculating an arctangent function (39) whose variable is the ratio between the two signals. ### Claim 12 (depends on 11) 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). ### Claim 13 (depends on 10) 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). ### Claim 14 (depends on 10) 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).